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WO2022024798A1 - Polarizing plate, polarizing plate with phase difference layer, and image display device including said polarizing plate or said polarizing plate with phase difference layer - Google Patents

Polarizing plate, polarizing plate with phase difference layer, and image display device including said polarizing plate or said polarizing plate with phase difference layer Download PDF

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Publication number
WO2022024798A1
WO2022024798A1 PCT/JP2021/026726 JP2021026726W WO2022024798A1 WO 2022024798 A1 WO2022024798 A1 WO 2022024798A1 JP 2021026726 W JP2021026726 W JP 2021026726W WO 2022024798 A1 WO2022024798 A1 WO 2022024798A1
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WO
WIPO (PCT)
Prior art keywords
polarizing plate
polarizing element
resin
stretching
polarizing
Prior art date
Application number
PCT/JP2021/026726
Other languages
French (fr)
Japanese (ja)
Inventor
幸佑 ▲高▼永
卓史 上条
洋 近野
Original Assignee
日東電工株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日東電工株式会社 filed Critical 日東電工株式会社
Priority to KR1020237003211A priority Critical patent/KR20230042028A/en
Priority to JP2022540177A priority patent/JPWO2022024798A1/ja
Priority to CN202180059184.7A priority patent/CN116158208A/en
Publication of WO2022024798A1 publication Critical patent/WO2022024798A1/en
Priority to JP2024100978A priority patent/JP2024114771A/en

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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363Birefringent elements, e.g. for optical compensation
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00Electroluminescent light sources
    • H05B33/02Details
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00Electroluminescent light sources
    • H05B33/12Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80Constructional details
    • H10K59/8791Arrangements for improving contrast, e.g. preventing reflection of ambient light

Definitions

  • the present invention relates to a polarizing plate, a polarizing plate with a retardation layer, and an image display device including the polarizing plate or the polarizing plate with a retardation layer.
  • the present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a polarizing plate which is extremely thin and in which crack generation in a deformed portion is suppressed.
  • the polarizing plate according to one embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape.
  • the protective layer is made of a resin film having a thickness of 10 ⁇ m or less.
  • the polarizing element is made of a polyvinyl alcohol-based resin film containing a dichroic substance, the single transmittance is x%, and the birefringence of the polyvinyl alcohol-based resin is y, the following formula (1) is used. Meet: y ⁇ 0.011x + 0.525 (1).
  • a polarizing plate has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape.
  • the protective layer is made of a resin film having a thickness of 10 ⁇ m or less.
  • the polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the in-plane retardation of the polyvinyl alcohol-based resin film is znm, the following formula is used. Satisfy (2): z ⁇ -60x + 2875 (2).
  • the polarizing plate according to still another embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape.
  • the protective layer is made of a resin film having a thickness of 10 ⁇ m or less.
  • the polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the orientation function of the polyvinyl alcohol-based resin is f, the following formula (3) is used. Meet: f ⁇ 0.018x + 1.11 (3).
  • the polarizing plate has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape.
  • the protective layer is made of a resin film having a thickness of 10 ⁇ m or less.
  • the polarizing element is made of a polyvinyl alcohol-based resin film containing a dichroic substance, and the piercing strength of the polarizing element is 30 gf / ⁇ m or more.
  • the thickness of the polarizing element is 10 ⁇ m or less.
  • the simple substance transmittance of the above-mentioned extruder is 40.0% or more, and the degree of polarization is 99.0% or more.
  • the variant has a through hole, a V-shaped notch, a U-shaped notch, a recess with a shape similar to a ship shape when viewed in plan view, a rectangular recess when viewed in plan view, and a bathtub when viewed in plan view. It is selected from a group consisting of R-shaped recesses that approximate the shape and combinations thereof.
  • the radius of curvature of the U-shaped notch is 5 mm or less.
  • the resin film comprises at least one resin selected from epoxy resins and (meth) acrylic resins.
  • the resin film is composed of a photocationically cured product of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
  • the resin film is composed of a solidified coating film of an organic solvent solution of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
  • the resin film is composed of a solidified coating film of an organic solvent solution of a thermoplastic (meth) acrylic resin, and the softening temperature of the resin film is 100 ° C. or higher.
  • the thermoplastic (meth) acrylic resin has at least one selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit and a maleimide unit. ..
  • a polarizing plate with a retardation layer is provided.
  • the polarizing plate with a retardation layer includes the above-mentioned polarizing plate and the above-mentioned retardation layer, and the retardation layer is arranged on the side opposite to the side where the above-mentioned protective layer of the above-mentioned polarizing element is arranged.
  • Re (550) of the retardation layer is 100 nm to 190 nm
  • Re (450) / Re (550) is 0.8 or more and less than 1
  • the angle formed by the above-mentioned polarizing element with the absorption axis is 40 ° to 50 °.
  • the retardation layer is laminated on the polarizing plate via an adhesive layer.
  • an image display device includes the above-mentioned polarizing plate or the above-mentioned polarizing plate with a retardation layer.
  • the polarizing plate in a polarizing plate having a deformed shape (deformed portion), by controlling the orientation state of the polyvinyl alcohol (PVA) -based resin of the polarizing element, the polarizing plate is extremely thin, but the deformed portion is formed. It is possible to realize a polarizing plate in which crack generation is suppressed. Further, such a polarizing element (as a result, a polarizing plate) can exhibit practically acceptable optical characteristics.
  • PVA polyvinyl alcohol
  • FIG. 1 It is a schematic diagram which shows an example of the drying shrinkage process using a heating roll in the method of manufacturing a polarizing element which can be used for a polarizing plate by embodiment of this invention. It is the schematic sectional drawing of the polarizing plate with a retardation layer by one Embodiment of this invention. It is a graph which shows the relationship between the simple substance transmittance of the polarizing element produced in an Example and the comparative example, and the birefringence of a PVA-based resin. It is a graph which shows the relationship between the simple substance transmittance of the elemental transmittance and the in-plane phase difference of a PVA-based resin film produced in an Example and a comparative example. It is a graph which shows the relationship between the simple substance transmittance of the elemental transmittance and the orientation function of a PVA-based resin produced in an Example and a comparative example.
  • FIG. 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention.
  • the polarizing plate 100 of the illustrated example has a polarizing element 10 and a protective layer 20 arranged on one side of the polarizing element 10.
  • a separate protective layer (not shown) may be provided on the opposite side of the protector 10 from the protective layer 20 depending on the purpose.
  • the protective layer 20 is made of a resin film having a thickness of 10 ⁇ m or less.
  • the polarizing plate may be used as a viewing-side polarizing plate of an image display device, or may be used as a back-side polarizing plate.
  • the polarizing plate is typically used as a viewing-side polarizing plate.
  • the protective layer 20 may be arranged on the visual recognition side (the side opposite to the image display cell).
  • the polarizing plate according to the embodiment of the present invention has a variant shape other than a rectangle.
  • the term "having a variant other than a rectangle” means that the planar view shape of the polarizing plate has a shape other than a rectangle.
  • the irregular shape is typically a deformed portion that has been deformed. Therefore, in the "polarizing plate having a deformed shape other than a rectangle" (hereinafter, may be referred to as a "deformed polarizing plate”), the entire deformed polarizing plate (that is, the outer edge defining the planar view shape of the polarizing plate) is other than a rectangle.
  • Examples of the irregular shape (deformed portion) include a chamfered corner portion in an R shape, a through hole, and a cutting portion that becomes a concave portion when viewed in a plan view, as shown in FIGS. 2 and 3.
  • Typical examples of the recess include a shape similar to a ship shape, a rectangle, an R shape similar to a bathtub shape, a V-shaped notch, and a U-shaped notch.
  • the shape includes a portion where the outer edge is formed in an arc shape along the rotation direction of the meter needle and the outer edge forms a V-shape (including an R shape) convex inward in the plane direction.
  • the shape of the deformed shape (deformed portion) is not limited to the illustrated example.
  • any appropriate shape for example, ellipse, triangle, quadrangle, pentagon, hexagon, octagon
  • the through hole is provided at an arbitrary appropriate position according to the purpose. As shown in FIG.
  • the through hole may be provided at a substantially central portion of the longitudinal end portion of the rectangular polarizing plate, or may be provided at a predetermined position at the longitudinal end portion of the polarizing plate. It may be provided at the corners; although not shown, it may be provided at the lateral end of the rectangular polarizing plate; at the center of the deformed polarizing plate as shown in FIG. 4 or FIG. It may be provided. As shown in FIG. 3, a plurality of through holes may be provided. Further, the shapes of the illustrated examples may be appropriately combined according to the purpose. For example, a through hole may be formed at any position on the modified polarizing plate of FIG.
  • a V-shaped notch and / or a U-shaped notch may be formed at any appropriate position on the outer edge of the modified polarizing plate of FIG. 4 or FIG. It may be formed.
  • a deformed polarizing plate can be suitably used for an image display device such as an automobile meter panel, a smartphone, a tablet PC or a smart watch.
  • the radius of curvature thereof is, for example, 0.2 mm or more, for example, 1 mm or more, and for example, 2 mm or more.
  • the radius of curvature is, for example, 10 mm or less, and is, for example, 5 mm or less.
  • the radius of curvature (the radius of curvature of the U-shaped portion) is, for example, 5 mm or less, for example, 1 mm to 4 mm, and for example, 2 mm to 3 mm.
  • the variant (deformed portion) can be formed by any suitable method.
  • Specific examples of the forming method include cutting with an end mill, punching with a punching blade such as a Thomson blade, and cutting with laser light irradiation. These methods may be combined.
  • the polarizing element is composed of a PVA-based resin film containing a dichroic substance.
  • the polarizing element satisfies the following formula (1) when the simple substance transmittance is x% and the birefringence of the polyvinyl alcohol-based resin constituting the polarizing element is y.
  • the substituent satisfies the following formula (2) when the simple substance transmittance is x% and the in-plane retardation of the polyvinyl alcohol-based resin film constituting the polarizing element is znm.
  • the polarizing element satisfies the following formula (3) when the simple substance transmittance is x% and the orientation function of the polyvinyl alcohol-based resin constituting the polarizing element is f.
  • the puncture strength of the polarizing element is 30 gf / ⁇ m or more.
  • Double refraction of PVA-based resin in the above deflector hereinafter referred to as PVA double refraction or PVA ⁇ n
  • PVA in-plane phase difference in-plane phase difference of PVA-based resin film
  • the orientation function of the PVA-based resin hereinafter referred to as "orientation function of PVA”
  • the piercing strength of the modulator are both values related to the degree of orientation of the molecular chains of the PVA-based resin constituting the modulator. ..
  • the birefringence, in-plane phase difference and orientation function of PVA can be large as the degree of orientation increases, and the puncture strength can decrease as the degree of orientation increases.
  • the orientation of the molecular chain of the PVA-based resin in the absorption axis direction is larger than that of the conventional polarizing element. Due to the gradualness, heat shrinkage in the absorption axis direction is suppressed. As a result, such a polarizing element (as a result, a polarizing plate) can suppress the occurrence of cracks in the deformed portion while being extremely thin.
  • a polarizing element (as a result, a polarizing plate) is also excellent in flexibility and bending durability, a curved image display device is preferable, a bendable image display device is more preferable, and a folding image display device is more preferable. It can be applied to possible image display devices. Conventionally, it has been difficult to obtain acceptable optical characteristics (typically, simple substance transmittance and degree of polarization) with a polarizing element having a low degree of orientation. It is possible to achieve both a lower degree of orientation of the PVA-based resin and an acceptable optical property.
  • the polarizing element preferably satisfies the following formulas (1a) and / or the following formula (2a), and more preferably the following formulas (1b) and / or the formula (2b).
  • the in-plane retardation value of PVA is the in-plane retardation value of the PVA-based resin film at 23 ° C. and a wavelength of 1000 nm.
  • the birefringence of PVA is a value obtained by dividing the in-plane phase difference of PVA by the thickness of the polarizing element.
  • the method for evaluating the in-plane phase difference of the PVA is also described in Japanese Patent No. 5923760, and can be referred to as necessary.
  • the birefringence ( ⁇ n) of PVA can be calculated by dividing this phase difference by the thickness.
  • Examples of commercially available devices for measuring the in-plane phase difference of PVA at a wavelength of 1000 nm include KOBRA-WR / IR series and KOBRA-31X / IR series manufactured by Oji Measurement Co., Ltd.
  • the orientation function (f) of the polarizing element preferably satisfies the following formula (3a), and more preferably the following formula (3b). If the orientation function is too small, acceptable single transmittance and / or degree of polarization may not be obtained. -0.01x + 0.50 ⁇ f ⁇ -0.018x + 1.11 (3a) -0.01x + 0.57 ⁇ f ⁇ -0.018x + 1.1 (3b)
  • the orientation function (f) is obtained by total internal reflection spectroscopy (ATR) measurement using, for example, a Fourier transform infrared spectrophotometer (FT-IR) and polarized light as measurement light.
  • ATR total internal reflection spectroscopy
  • germanium is used as the crystallite to which the polarizing element is brought into close contact
  • the incident angle of the measurement light is 45 °
  • the polarized infrared light (measurement light) to be incident is the surface to which the sample of the germanium crystal is brought into close contact.
  • the polarization (s - polarized light) that vibrates in parallel with the light is used, and the measurement is performed with the extension directions of the substituents arranged parallel and perpendicular to the polarization direction of the measurement light. Is calculated according to the following formula.
  • the intensity I is a value of 2941 cm -1/3330 cm -1 with 3330 cm -1 as a reference peak.
  • the peak of 2941 cm -1 is considered to be absorption caused by the vibration of the main chain (-CH 2- ) of PVA in the polarizing element.
  • 90 °.
  • Angle of molecular chain with respect to stretching direction
  • Angle of transition dipole moment with respect to molecular chain axis
  • I ⁇ Absorption intensity when the polarization direction of the measurement light and the extension direction of the modulator are perpendicular
  • I // Absorption intensity when the polarization direction of the measurement light and the extension direction of the modulator are parallel
  • the thickness of the polarizing element is preferably 10 ⁇ m or less, more preferably 8 ⁇ m or less.
  • the lower limit of the thickness of the transducer can be, for example, 1 ⁇ m.
  • the thickness of the polarizing element may be 2 ⁇ m to 10 ⁇ m in one embodiment and 2 ⁇ m to 8 ⁇ m in another embodiment.
  • the polarizing element preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm.
  • the simple substance transmittance of the polarizing element is preferably 40.0% or more, more preferably 41.0% or more.
  • the upper limit of the single transmittance can be, for example, 49.0%.
  • the simple substance transmittance of the polarizing element is 40.0% to 45.0% in one embodiment.
  • the degree of polarization of the polarizing element is preferably 99.0% or more, more preferably 99.4% or more.
  • the upper limit of the degree of polarization can be, for example, 99.999%.
  • the degree of polarization of the polarizing element is 99.0% to 99.9% in one embodiment.
  • the polarizing element according to the embodiment of the present invention has a lower degree of orientation of the PVA-based resin constituting the polarizing element than the conventional one and has the above-mentioned in-plane phase difference, birefringence and / or orientation function.
  • One of the features is that such a practically acceptable single-unit transmittance and degree of polarization can be realized. It is presumed that this is due to the manufacturing method described later.
  • the single transmittance is typically a Y value measured with an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
  • the degree of polarization is typically determined by the following equation based on the parallel transmittance Tp and the orthogonal transmittance Tc measured with an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
  • Polarization degree (%) ⁇ (Tp-Tc) / (Tp + Tc) ⁇ 1/2 ⁇ 100
  • the puncture strength of the polarizing element is, for example, 30 gf / ⁇ m or more, preferably 35 gf / ⁇ m or more, more preferably 40 gf / ⁇ m or more, still more preferably 45 gf / ⁇ m or more, and particularly preferably 50 gf / ⁇ m or more. That is all.
  • the upper limit of the piercing strength can be, for example, 80 gf / ⁇ m.
  • the piercing strength indicates the cracking resistance of the polarizing element when the polarizing element is pierced with a predetermined strength.
  • the piercing strength can be expressed as, for example, the strength (breaking strength) at which the polarizing element is cracked when a predetermined needle is attached to a compression tester and the needle is pierced into the polarizing element at a predetermined speed.
  • the piercing strength means the piercing strength per unit thickness (1 ⁇ m) of the polarizing element.
  • the polarizing element is composed of a PVA-based resin film containing a dichroic substance.
  • the PVA-based resin constituting the PVA-based resin film (substantially, a polarizing element) contains an acetoacetyl-modified PVA-based resin.
  • a polarizing element having a desired piercing strength can be obtained.
  • the blending amount of the acetoacetyl-modified PVA-based resin is preferably 5% by weight to 20% by weight, more preferably 8% by weight to 12% by weight, when the total amount of the PVA-based resin is 100% by weight. .. When the blending amount is in such a range, the piercing strength can be in a more suitable range.
  • the decoder can typically be made using a laminate of two or more layers.
  • Specific examples of the polarizing element obtained by using the laminated body include a polarizing element obtained by using a laminated body of a resin base material and a PVA-based resin layer coated and formed on the resin base material.
  • the polarizing element obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it.
  • a PVA-based resin layer is formed on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a stator. obtain.
  • a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin base material. Stretching typically involves immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching preferably further comprises stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in an aqueous boric acid solution.
  • the total magnification of stretching is preferably 3.0 to 4.5 times, which is significantly smaller than usual. Even at the total magnification of such stretching, a stator having acceptable optical properties can be obtained by combining the addition of a halide and the drying shrinkage treatment.
  • the stretching ratio of the aerial auxiliary stretching is preferably larger than the stretching ratio of the boric acid water stretching. With such a configuration, it is possible to obtain a polarizing element having acceptable optical characteristics even if the total magnification of stretching is small.
  • the laminate is preferably subjected to a drying shrinkage treatment of shrinking by 2% or more in the width direction by heating while transporting in the longitudinal direction.
  • the method for producing a polarizing element includes subjecting a laminate to an aerial auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order.
  • auxiliary stretching even when the PVA-based resin is coated on the thermoplastic resin, the crystallinity of the PVA-based resin can be enhanced, and high optical characteristics can be achieved.
  • by increasing the orientation of the PVA-based resin in advance it is possible to prevent problems such as deterioration of the orientation of the PVA-based resin and dissolution when immersed in water in the subsequent dyeing step or stretching step. , It becomes possible to achieve high optical characteristics.
  • the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide.
  • This makes it possible to improve the optical characteristics of the polarizing element obtained through a treatment step of immersing the laminate in a liquid, such as a dyeing treatment and a stretching treatment in water. Further, the optical characteristics can be improved by shrinking the laminated body in the width direction by the drying shrinkage treatment.
  • the obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. The details of the method for manufacturing the stator will be described in Section A-3.
  • a polyvinyl alcohol-based resin layer preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin base material (preferably A PVA-based resin layer) is formed to form a laminated body, and the laminated body is heated in the width direction by performing an aerial auxiliary stretching treatment, a dyeing treatment, and an underwater stretching treatment while transporting the laminated body in the longitudinal direction. It includes performing a dry shrinkage treatment for shrinking by% or more in this order.
  • the content of the halide in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • the drying shrinkage treatment is preferably performed using a heating roll, and the temperature of the heating roll is preferably 60 ° C. to 120 ° C.
  • the shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment is preferably 2% or more.
  • the stretch ratio of the aerial auxiliary stretch is preferably larger than the stretch ratio of the underwater stretch. According to such a manufacturing method, the modulator described in Section A-2 above can be obtained.
  • a laminate containing a PVA-based resin layer containing a halide is prepared, the stretching of the laminate is a multi-step stretching including aerial auxiliary stretching and underwater stretching, and the stretched laminate is heated with a heating roll to have a width.
  • a stator having excellent optical properties typically, single transmittance and degree of polarization
  • A-3-1 Preparation of Laminate
  • any appropriate method can be adopted.
  • a coating liquid containing a halide and a PVA-based resin is applied to the surface of the thermoplastic resin base material and dried to form a PVA-based resin layer on the thermoplastic resin base material.
  • the content of the halide in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • any appropriate method can be adopted as the application method of the coating liquid.
  • a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.) and the like can be mentioned.
  • the coating / drying temperature of the coating liquid is preferably 50 ° C. or higher.
  • the thickness of the PVA-based resin layer is preferably 2 ⁇ m to 30 ⁇ m, more preferably 2 ⁇ m to 20 ⁇ m.
  • the thermoplastic resin base material Before forming the PVA-based resin layer, the thermoplastic resin base material may be surface-treated (for example, corona treatment or the like), or the easy-adhesion layer may be formed on the thermoplastic resin base material. By performing such a treatment, the adhesion between the thermoplastic resin base material and the PVA-based resin layer can be improved.
  • thermoplastic resin base material any suitable thermoplastic resin film can be adopted. Details of the thermoplastic resin base material are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.
  • the coating liquid contains a halide and a PVA-based resin as described above.
  • the coating liquid is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent.
  • the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Among these, water is preferable.
  • the PVA-based resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent.
  • the content of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
  • Additives may be added to the coating liquid.
  • the additive include a plasticizer, a surfactant and the like.
  • the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin.
  • the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the obtained PVA-based resin layer.
  • any suitable resin can be adopted as the PVA-based resin.
  • polyvinyl alcohol and ethylene-vinyl alcohol copolymers can be mentioned.
  • Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
  • the ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer.
  • the saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. ..
  • the degree of saponification can be determined according to JIS K 6726-1994.
  • the PVA-based resin By using a PVA-based resin having such a degree of saponification, a polarizing element having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.
  • the PVA-based resin preferably contains an acetoacetyl-modified PVA-based resin.
  • the average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose.
  • the average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300.
  • the average degree of polymerization can be determined according to JIS K 6726-1994.
  • any suitable halide can be adopted.
  • iodide and sodium chloride can be mentioned.
  • Iodides include, for example, potassium iodide, sodium iodide, and lithium iodide. Among these, potassium iodide is preferable.
  • the amount of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, and more preferably 10 parts by weight to 15 parts by weight with respect to 100 parts by weight of the PVA-based resin. It is a department. If the amount of the halide exceeds 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, the halide may bleed out and the finally obtained polarizing element may become cloudy.
  • the stretching of the PVA-based resin layer increases the orientation of the polyvinyl alcohol molecules in the PVA-based resin layer.
  • the stretched PVA-based resin layer is immersed in a liquid containing water, the polyvinyl alcohol molecules become higher. The orientation of the plastic may be disturbed and the orientation may decrease.
  • the laminate of the thermoplastic resin base material and the PVA-based resin layer is stretched in boric acid water, the laminate is stretched in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin base material. In the case of stretching, the tendency of the degree of orientation to decrease is remarkable.
  • stretching a PVA film alone in boric acid water is generally performed at 60 ° C.
  • stretching of a laminate of A-PET (thermoplastic resin base material) and a PVA-based resin layer is performed. It is carried out at a high temperature of about 70 ° C., and in this case, the orientation of PVA at the initial stage of stretching may decrease before it is increased by stretching in water.
  • A-PET thermoplastic resin base material
  • auxiliary stretching before stretching it in boric acid water.
  • Crystallization of the PVA-based resin in the PVA-based resin layer of the laminated body after the auxiliary stretching can be promoted.
  • the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide.
  • A-3-2 Aerial auxiliary stretching treatment
  • a two-stage stretching method that combines dry stretching (auxiliary stretching) and boric acid water stretching is selected.
  • auxiliary stretching as in the case of two-step stretching, it is possible to stretch while suppressing the crystallization of the thermoplastic resin base material.
  • the PVA-based resin is applied on the thermoplastic resin base material, it is compared with the case where the PVA-based resin is applied on a normal metal drum in order to suppress the influence of the glass transition temperature of the thermoplastic resin base material. Therefore, it is necessary to lower the coating temperature, and as a result, the crystallization of the PVA-based resin becomes relatively low, which may cause a problem that sufficient optical characteristics cannot be obtained.
  • the stretching method of the aerial auxiliary stretching may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Although good, free-end stretching can be positively adopted in order to obtain high optical properties.
  • the aerial stretching treatment includes a heating roll stretching step of stretching the laminate by the difference in peripheral speed between the heating rolls while transporting the laminated body in the longitudinal direction thereof.
  • the aerial stretching treatment typically includes a zone stretching step and a heating roll stretching step.
  • the order of the zone stretching step and the heating roll stretching step is not limited, and the zone stretching step may be performed first, or the heating roll stretching step may be performed first.
  • the zone stretching step may be omitted.
  • the zone stretching step and the heating roll stretching step are performed in this order.
  • the film in the tenter stretching machine, is stretched by grasping the end portion of the film and widening the distance between the tenters in the flow direction (the widening of the distance between the tenters is the stretching ratio).
  • the distance of the tenter in the width direction (perpendicular to the flow direction) is set to approach arbitrarily.
  • it can be set to be closer to the free end stretch with respect to the stretch ratio in the flow direction.
  • the aerial auxiliary stretching may be performed in one step or in multiple steps. When performed in multiple stages, the draw ratio is the product of the draw ratios in each stage.
  • the stretching direction in the aerial auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching.
  • the draw ratio in the aerial auxiliary stretching is preferably 1.0 to 4.0 times, more preferably 1.5 to 3.5 times, and further preferably 2.0 to 3.0 times. be. If the stretch ratio of the aerial auxiliary stretch is in such a range, the total stretch ratio can be set to a desired range when combined with the underwater stretch, and the desired birefringence, in-plane retardation and / or orientation can be set. Functions can be realized. As a result, it is possible to obtain a polarizing element (as a result, a polarizing plate) in which the generation of cracks in the deformed portion is suppressed. Further, as described above, it is preferable that the stretching ratio of the aerial auxiliary stretching is larger than the stretching ratio of the underwater stretching.
  • the ratio of the stretching ratio of the aerial auxiliary stretching to the stretching ratio of the underwater stretching is preferably 0.4 to 0.9, more preferably 0.5 to 0. It is 8.8.
  • the stretching temperature of the aerial auxiliary stretching can be set to an arbitrary appropriate value depending on the forming material of the thermoplastic resin base material, the stretching method, and the like.
  • the stretching temperature is preferably the glass transition temperature (Tg) or higher of the thermoplastic resin base material, more preferably the glass transition temperature (Tg) of the thermoplastic resin base material (Tg) + 10 ° C. or higher, and particularly preferably Tg + 15 ° C. or higher.
  • the upper limit of the stretching temperature is preferably 170 ° C.
  • an insolubilization treatment is performed after the aerial auxiliary stretching treatment and before the underwater stretching treatment or the dyeing treatment.
  • the insolubilization treatment is typically performed by immersing a PVA-based resin layer in a boric acid aqueous solution.
  • the dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically iodine).
  • a cross-linking treatment is performed after the dyeing treatment and before the underwater stretching treatment.
  • the cross-linking treatment is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution. Details of the insolubilization treatment, the dyeing treatment and the crosslinking treatment are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580.
  • thermoplastic resin base material or the PVA-based resin layer can be stretched at a temperature lower than the glass transition temperature (typically, about 80 ° C.), and the PVA-based resin layer is crystallized. Can be stretched while suppressing. As a result, it is possible to manufacture a polarizing element having excellent optical characteristics.
  • any appropriate method can be adopted as the stretching method of the laminated body. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Preferably, free-end stretching is selected.
  • the stretching of the laminate may be carried out in one step or in multiple steps. When performed in multiple stages, the total stretching ratio is the product of the stretching ratios in each stage.
  • the underwater stretching is preferably carried out by immersing the laminate in a boric acid aqueous solution (boric acid water stretching).
  • boric acid aqueous solution as the stretching bath, it is possible to impart rigidity to withstand the tension applied during stretching and water resistance that does not dissolve in water to the PVA-based resin layer.
  • boric acid can generate a tetrahydroxyboric acid anion in an aqueous solution and crosslink with a PVA-based resin by hydrogen bonding.
  • the PVA-based resin layer can be imparted with rigidity and water resistance, can be stretched satisfactorily, and a polarizing element having excellent optical characteristics can be produced.
  • the boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent.
  • the boric acid concentration is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight with respect to 100 parts by weight of water. Is.
  • the boric acid concentration is preferably 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing element having higher characteristics can be produced.
  • an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde or the like in a solvent can also be used.
  • iodide is added to the above stretching bath (boric acid aqueous solution).
  • the elution of iodine adsorbed on the PVA-based resin layer can be suppressed.
  • Specific examples of iodide are as described above.
  • the concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, and more preferably 0.5 parts by weight to 8 parts by weight with respect to 100 parts by weight of water.
  • the stretching temperature (liquid temperature of the stretching bath) is preferably 40 ° C to 85 ° C, more preferably 60 ° C to 75 ° C. At such a temperature, the PVA-based resin layer can be stretched at a high magnification while suppressing dissolution.
  • the glass transition temperature (Tg) of the thermoplastic resin base material is preferably 60 ° C. or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40 ° C., it may not be stretched well even in consideration of the plasticization of the thermoplastic resin base material by water.
  • the immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.
  • the stretching ratio by stretching in water is preferably 1.0 to 2.2 times, more preferably 1.1 times to 2.0 times, and further preferably 1.1 times to 1.8 times. , Even more preferably 1.2 to 1.6 times.
  • the total stretching ratio can be set in a desired range, and the desired birefringence, in-plane retardation and / or orientation function can be realized.
  • a polarizing element as a result, a polarizing plate in which the generation of cracks in the deformed portion is suppressed.
  • the total stretching ratio (the total stretching ratio when the aerial auxiliary stretching and the underwater stretching are combined) is preferably 3.0 to 4.5 times with respect to the original length of the laminated body. , More preferably 3.0 to 4.3 times, still more preferably 3.0 to 4.0 times.
  • the drying shrinkage treatment may be performed by heating the entire zone by zone heating, or by heating the transport roll (using a so-called heating roll) (heating roll drying method). Preferably both are used.
  • heating roll heating roll drying method
  • the crystallization of the thermoplastic resin base material can be efficiently promoted and the crystallinity can be increased, which is relatively low. Even at the drying temperature, the crystallinity of the thermoplastic resin substrate can be satisfactorily increased.
  • the rigidity of the thermoplastic resin base material is increased, and the PVA-based resin layer is in a state of being able to withstand shrinkage due to drying, and curling is suppressed.
  • the laminated body can be dried while being maintained in a flat state, so that not only curling but also wrinkles can be suppressed.
  • the laminated body can be improved in optical characteristics by shrinking in the width direction by a drying shrinkage treatment. This is because the orientation of PVA and the PVA / iodine complex can be effectively enhanced.
  • the shrinkage ratio in the width direction of the laminate by the dry shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 2% to 6%.
  • FIG. 6 is a schematic view showing an example of the drying shrinkage treatment.
  • the laminate 200 is dried while being transported by the transport rolls R1 to R6 heated to a predetermined temperature and the guide rolls G1 to G4.
  • the transport rolls R1 to R6 are arranged so as to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin base material.
  • one surface of the laminate 200 (for example, thermoplasticity) is arranged.
  • the transport rolls R1 to R6 may be arranged so as to continuously heat only the resin substrate surface).
  • Drying conditions can be controlled by adjusting the heating temperature of the transport roll (temperature of the heating roll), the number of heating rolls, the contact time with the heating roll, and the like.
  • the temperature of the heating roll is preferably 60 ° C. to 120 ° C., more preferably 65 ° C. to 100 ° C., and particularly preferably 70 ° C. to 80 ° C.
  • the crystallinity of the thermoplastic resin can be satisfactorily increased, curling can be satisfactorily suppressed, and an optical laminate having extremely excellent durability can be produced.
  • the temperature of the heating roll can be measured with a contact thermometer. In the illustrated example, six transport rolls are provided, but there is no particular limitation as long as there are a plurality of transport rolls.
  • the number of transport rolls is usually 2 to 40, preferably 4 to 30.
  • the contact time (total contact time) between the laminate and the heating roll is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and further preferably 1 to 10 seconds.
  • the heating roll may be provided in a heating furnace (for example, an oven) or in a normal production line (in a room temperature environment). Preferably, it is provided in a heating furnace provided with an air blowing means.
  • a heating furnace provided with an air blowing means.
  • the temperature of hot air drying is preferably 30 ° C to 100 ° C.
  • the hot air drying time is preferably 1 second to 300 seconds.
  • the wind speed of the hot air is preferably about 10 m / s to 30 m / s. The wind speed is the wind speed in the heating furnace and can be measured by a mini-vane type digital anemometer.
  • a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment.
  • the cleaning treatment is typically performed by immersing a PVA-based resin layer in an aqueous potassium iodide solution.
  • the thickness of the protective layer is 10 ⁇ m or less.
  • the thickness of the protective layer is 10 ⁇ m or less, it can contribute to the thinning of the polarizing plate.
  • a protective layer having a thickness of 20 ⁇ m or more has been used.
  • the polarizing element used in the embodiment of the present invention has a lower degree of orientation of the PVA-based resin than the conventional one, and as a result, shrinkage due to heating is small, so that the protective layer has a thickness of 10 ⁇ m or less. Even when the above is used, the generation of cracks during heating is suppressed. Further, such a polarizing element can also contribute to crack suppression in the deformed portion.
  • the thickness of the protective layer is preferably 7 ⁇ m or less, more preferably 5 ⁇ m or less, and further preferably 3 ⁇ m or less.
  • the thickness of the protective layer is, for example, 1 ⁇ m or more.
  • the protective layer is composed of a resin film.
  • any suitable resin can be used depending on the purpose. Specific examples include (meth) acrylic, cellulose-based such as triacetylcellulose (TAC), polyester-based, polyurethane-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, and polystyrene.
  • Thermoplastic resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, silicone, etc., or active energy ray-curable resins.
  • Resin Glassy polymers such as siloxane-based polymers can be mentioned.
  • examples of the resin forming the resin film include an epoxy resin and a (meth) acrylic resin. These may be used alone or in combination.
  • the resin film constituting the protective layer may be, for example, a molded product of a molten resin, or may be a solidified coating film of a resin solution obtained by dissolving or dispersing the resin in an aqueous solvent or an organic solvent.
  • a cured product of a curable resin for example, a photocationic cured product may be used.
  • the protective layer is a solidified coating film of an organic solvent solution of a thermoplastic (meth) acrylic resin (hereinafter, the (meth) acrylic resin may be simply referred to as “acrylic resin”).
  • acrylic resin a thermoplastic (meth) acrylic resin
  • the protective layer is composed of the solidification of the coating film of the organic solvent solution of the thermoplastic acrylic resin.
  • the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
  • the acrylic resin has a glass transition temperature (Tg) of preferably 100 ° C. or higher.
  • Tg glass transition temperature
  • the softening temperature of the protective layer is also approximately 100 ° C. or higher.
  • the Tg of the acrylic resin is more preferably 110 ° C. or higher, further preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher.
  • the Tg of the acrylic resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower. If the Tg of the acrylic resin is in such a range, the moldability can be excellent.
  • any suitable acrylic resin can be adopted as long as it has Tg as described above.
  • Acrylic resins typically contain an alkyl (meth) acrylate as a main component as a monomer unit (repeating unit).
  • (meth) acrylic means acrylic and / or methacrylic.
  • alkyl (meth) acrylate constituting the main skeleton of the acrylic resin include linear or branched alkyl groups having 1 to 18 carbon atoms. These can be used alone or in combination.
  • any suitable copolymerization monomer may be introduced into the acrylic resin by copolymerization.
  • a based resin can be obtained.
  • the acrylic resin preferably has a repeating unit containing a ring structure.
  • the repeating unit including a ring structure include a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. Only one type of the repeating unit including the ring structure may be contained in the repeating unit of the acrylic resin, or two or more types may be contained.
  • Acrylic resins having a lactone ring unit are described in, for example, Japanese Patent Application Laid-Open No. 2008-181078.
  • Acrylic resins having a glutarimide unit are, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492. It is described in JP-A-2006-337493 and JP-A-2006-337569. The description of these publications is incorporated herein by reference.
  • the content ratio of the repeating unit including the ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and further preferably 20 mol% to 30 mol%. If the content ratio is too small, Tg may be less than 100 ° C., and the heat resistance, solvent resistance and surface hardness of the obtained protective layer may be insufficient. If the content is too high, moldability and transparency may be insufficient.
  • an acrylic resin and another resin may be used in combination. That is, the monomer component constituting the acrylic resin and the monomer component constituting the other resin may be copolymerized, and the copolymer may be used for molding the protective layer described later; the acrylic resin and the other resin.
  • the blend of may be used for forming the protective layer.
  • the protective layer of the present embodiment can be formed, for example, by applying an organic solvent solution of an acrylic resin to the surface of a polarizing element to form a coating film, and solidifying the coating film.
  • any suitable organic solvent capable of dissolving or uniformly dispersing the acrylic resin can be used.
  • the organic solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.
  • the acrylic resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
  • the solution may be applied to any suitable substrate or to a polarizing element.
  • the solidified material of the coating film formed on the substrate is transferred to the polarizing element.
  • a protective layer is directly formed on the polarizing element by drying (solidifying) the coating film.
  • the solution is applied to the polarizing element and a protective layer is formed directly on the polarizing element.
  • Any suitable method can be adopted as the method for applying the solution. Specific examples include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (comma coating method, etc.).
  • a protective layer can be formed by drying (solidifying) the coating film of the solution.
  • the drying temperature is preferably 100 ° C. or lower, more preferably 50 ° C. to 70 ° C. When the drying temperature is in such a range, it is possible to prevent an adverse effect on the polarizing element.
  • the drying time can vary depending on the drying temperature. The drying time can be, for example, 1 to 10 minutes.
  • the protective layer is composed of a photocationic cured product of epoxy resin.
  • the composition for forming the protective layer contains a photocationic polymerization initiator.
  • the photocationic polymerization initiator is a photosensitizer having a function of a photoacid generator, and a typical example thereof is an ionic onium salt composed of a cation portion and an anion portion. In this onium salt, the cation part absorbs light and the anion part becomes a source of acid.
  • Ring-opening polymerization of the epoxy group proceeds by the acid generated from this photocationic polymerization initiator.
  • the protective layer which is the obtained photocationic cured product, has a high softening temperature, and the amount of iodine adsorbed can be reduced. Therefore, it is possible to provide a polarizing plate in which the occurrence of cracks is suppressed and has excellent humidification durability.
  • the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
  • Epoxy resin As the epoxy resin, any suitable epoxy resin can be used, and an epoxy resin having an aromatic ring or an alicyclic ring can be preferably used. In the present embodiment, an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton can be preferably used. Examples of the aromatic skeleton include a benzene ring, a naphthalene ring, a fluorene ring and the like. Only one type of epoxy resin may be used, or two or more types may be used in combination. Preferably, an epoxy resin having a biphenyl skeleton or a bisphenol skeleton or a hydrogenated product thereof is used as the aromatic skeleton. By using such an epoxy resin, a polarizing plate having more excellent durability and excellent flexibility can be provided.
  • the epoxy resin having a biphenyl skeleton is an epoxy resin containing the following structure. Only one type of epoxy resin having a biphenyl skeleton may be used, or two or more types may be used in combination.
  • R 14 to R 21 each independently represent a hydrogen atom, a linear or branched substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, or a halogen element).
  • the epoxy resin having a biphenyl skeleton is an epoxy resin represented by the following formula. (In the equation, R 14 to R 21 are as described above, and n represents an integer of 0 to 6).
  • the epoxy resin having a biphenyl skeleton is an epoxy resin having only a biphenyl skeleton.
  • the epoxy resin having a biphenyl skeleton may contain a chemical structure other than the biphenyl skeleton.
  • the chemical structure other than the biphenyl skeleton include a bisphenol skeleton, an alicyclic structure, an aromatic ring structure and the like.
  • the ratio (molar ratio) of the chemical structure other than the biphenyl skeleton is preferably smaller than that of the biphenyl skeleton.
  • the epoxy resin (epoxy resin after photocation curing) preferably has a glass transition temperature (Tg) of 100 ° C. or higher.
  • Tg glass transition temperature
  • the softening temperature of the protective layer is also approximately 100 ° C. or higher.
  • the Tg of the epoxy resin is more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher.
  • the Tg of the epoxy resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower. When the Tg of the epoxy resin is in such a range, the moldability can be excellent.
  • the epoxy equivalent of the epoxy resin is preferably 100 g / equivalent or more, more preferably 150 g / equivalent or more, and further preferably 200 g / equivalent or more.
  • the epoxy equivalent of the epoxy resin is preferably 3000 g / equivalent or less, more preferably 2500 g / equivalent or less, still more preferably 2000 g / equivalent or less.
  • a more stable protective layer a protective layer having less residual monomer and sufficiently cured
  • "epoxy equivalent” means "mass of epoxy resin containing 1 equivalent of epoxy group” and can be measured according to JIS K7236.
  • the above epoxy resin may be used in combination with another resin. That is, even if a blend of the above epoxy resin (for example, an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton) and another resin is used for molding the protective layer. good.
  • a blend of the above epoxy resin for example, an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton
  • other resins include acrylic resins and oxetane resins.
  • any suitable (meth) acrylic compound can be used.
  • the (meth) acrylic compound for example, a (meth) acrylic compound having one (meth) acryloyl group in the molecule (hereinafter, also referred to as “monofunctional (meth) acrylic compound”), intramolecular.
  • examples thereof include (meth) acrylic compounds having two or more (meth) acryloyl groups (hereinafter, also referred to as “polyfunctional (meth) acrylic compounds”).
  • These (meth) acrylic compounds may be used alone or in combination of two or more.
  • These acrylic resins are described in, for example, Japanese Patent Application Laid-Open No. 2019-168500. The entire description of the publication is incorporated herein by reference.
  • any suitable compound having one or more oxetanyl groups in the molecule is used.
  • Oxetane compound having one oxetane group in the molecule such as oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl; 3-ethyl- 3 ⁇ [(3-ethyloxetane-3-yl) methoxy] methyl ⁇ oxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 4,4'-bis [(3-ethyl) -3-Oxetane) methoxymethyl]
  • An oxetane compound having two or more oxetane groups in a molecule such as biphenyl; and the like.
  • the oxetane resin is preferably 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (2-ethylhexyloxymethyl).
  • Oxetane, 3-Ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl, 3-ethyl-3 ⁇ [(3-ethyloxetane-3-yl) Methyl] methyl ⁇ oxetane and the like are used.
  • These oxetane resins are easily available and can be excellent in dilutability (low viscosity) and compatibility.
  • an oxetane resin having a molecular weight of 500 or less and liquid at room temperature (25 ° C.) is preferably used from the viewpoint of compatibility and adhesiveness. In one embodiment, it preferably contains an oxetane compound containing two or more oxetanel groups in the molecule, one oxetaneyl group and one (meth) acryloyl group or one epoxy group in the molecule.
  • Oxetane compounds are used, more preferably 3-ethyl-3 ⁇ [(3-ethyloxetane-3-yl) methoxy] methyl ⁇ oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic. Acid (3-ethyloxetane-3-yl) methyl is used.
  • the photocationic polymerization initiator is a photosensitive agent having a function of a photoacid generator, and a typical example thereof is an ionic onium salt composed of a cation portion and an anion portion. In this onium salt, the cation part absorbs light and the anion part becomes a source of acid. Ring-opening polymerization of the epoxy group proceeds by the acid generated from this photocationic polymerization initiator.
  • any suitable compound capable of curing an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton by irradiation with light such as ultraviolet rays. Can be used. Only one type of photocationic polymerization initiator may be used, or two or more types may be used in combination.
  • photocationic polymerization initiator examples include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, p- (phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, p- (phenylthio) phenyldiphenylsulfonium hexafluorophosphate, and the like.
  • a triphenylsulfonium salt-based hexafluoroantimonate type photocationic polymerization initiator and a diphenyliodonium salt-based hexafluoroantimonate type photocationic polymerization initiator are used.
  • the protective layer of the present embodiment is formed by, for example, applying a composition containing the epoxy resin and a photocationic polymerization initiator to form a coating film, and irradiating the coating film with light (for example, ultraviolet rays). Can be done.
  • the epoxy resin concentration in the above composition is preferably 10 parts by weight to 30 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
  • the above composition may be applied to any suitable substrate or may be applied to a polarizing element.
  • the cured product of the coating film formed on the substrate is transferred to the polarizing element.
  • the protective layer is directly formed on the polarizing element by, for example, curing the coating film by irradiation with light.
  • the composition is applied to a polarizing element and a protective layer is formed directly on the polarizing element.
  • Curing of the coating film can be performed by irradiating light (typically ultraviolet rays) with an arbitrary appropriate light source so as to obtain an arbitrary appropriate irradiation amount. After the light irradiation, further heat treatment may be performed to complete the curing by the light reaction. The heat treatment can be performed at any suitable temperature and time.
  • light typically ultraviolet rays
  • the heat treatment can be performed at any suitable temperature and time.
  • the protective layer is composed of the solidification of the coating film of the organic solvent solution of the epoxy resin.
  • the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
  • the epoxy resin preferably has a glass transition temperature (Tg) of 100 ° C. or higher.
  • Tg glass transition temperature
  • the softening temperature of the protective layer is also approximately 100 ° C. or higher.
  • the Tg of the epoxy resin is more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher.
  • the Tg of the epoxy resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
  • the Tg of the epoxy resin is in such a range, the moldability can be excellent.
  • the epoxy resin any suitable epoxy resin can be adopted as long as it has Tg as described above.
  • the epoxy resin typically refers to a resin having an epoxy group in its molecular structure.
  • an epoxy resin having an aromatic ring in the molecular structure is preferably used.
  • an epoxy resin having a higher Tg can be obtained.
  • the aromatic ring in the epoxy resin having an aromatic ring in the molecular structure include a benzene ring, a naphthalene ring, a fluorene ring and the like. Only one type of epoxy resin may be used, or two or more types may be used in combination. When two or more kinds of epoxy resins are used, an epoxy resin containing an aromatic ring and an epoxy resin not containing an aromatic ring may be used in combination.
  • epoxy resin having an aromatic ring in its molecular structure examples include bisphenol A diglycidyl ether type epoxy resin, bisphenol F diglycidyl ether type epoxy resin, bisphenol S diglycidyl ether type epoxy resin, and resorcin diglycidyl ether.
  • Type epoxy resin hydroquinone diglycidyl ether type epoxy resin, terephthalic acid diglycidyl ester type epoxy resin, bisphenoxyethanol full orange glycidyl ether type epoxy resin, bisphenol full orange glycidyl ether type epoxy resin, biscresol full orange glycidyl ether type epoxy resin, etc.
  • Epoxy resin having two epoxy groups novolak type epoxy resin, N, N, O-triglycidyl-P- or -m-aminophenol type epoxy resin, N, N, O-triglycidyl-4-amino-m -Or-5-Amino-o-cresol type epoxy resin, 1,1,1- (triglycidyloxyphenyl) methane type epoxy resin and other epoxy resins with three epoxy groups; glycidylamine type epoxy resin (eg, diamino) Examples thereof include epoxy resins having four epoxy groups such as diphenylmethane type, diaminodiphenylsulfone type, and metaxylene diamine type).
  • a glycidyl ester type epoxy resin such as a hexahydrophthalic anhydride type epoxy resin, a tetrahydrophthalic anhydride type epoxy resin, a dimer acid type epoxy resin, and a p-oxybenzoic acid type may be used.
  • the epoxy equivalent of the epoxy resin is preferably 1000 g / equivalent or more, more preferably 3000 g / equivalent or more, and further preferably 5000 g / equivalent or more.
  • the epoxy equivalent of the epoxy resin is preferably 30,000 g / equivalent or less, more preferably 25,000 g / equivalent or less, and further preferably 20,000 g / equivalent or less. When the epoxy equivalent is in the above range, a more stable protective layer can be obtained.
  • epoxy equivalent means "mass of epoxy resin containing 1 equivalent of epoxy group” and can be measured according to JIS K7236.
  • the epoxy resin and another resin may be used in combination. That is, a blend of the epoxy resin and another resin may be used for molding the protective layer.
  • Other resins may be appropriately selected depending on the intended purpose.
  • the protective layer of the present embodiment can be formed, for example, by applying an organic solvent solution containing the epoxy resin to form a coating film and solidifying the coating film.
  • the epoxy resin concentration in the organic solvent solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
  • any suitable solvent capable of dissolving or uniformly dispersing the epoxy resin can be used.
  • the solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.
  • the solution may be applied to any suitable substrate or to a polarizing element.
  • the solidified material of the coating film formed on the substrate is transferred to the polarizing element.
  • a protective layer is directly formed on the polarizing element by drying (solidifying) the coating film.
  • the solution is applied to the polarizing element and a protective layer is formed directly on the polarizing element.
  • a protective layer that is a solidified coating film By drying (solidifying) the coating film of the solution, a protective layer that is a solidified coating film can be formed.
  • the drying temperature is preferably 100 ° C. or lower, more preferably 50 ° C. to 70 ° C. When the drying temperature is in such a range, it is possible to prevent an adverse effect on the polarizing element.
  • the drying time can vary depending on the drying temperature. The drying time can be, for example, 1 to 10 minutes.
  • FIG. 7 is a schematic cross-sectional view of the polarizing plate with a retardation layer according to one embodiment of the present invention.
  • the polarizing plate with a retardation layer 200 in the illustrated example includes the polarizing plate 100 according to the above item A and the retardation layer 120. Therefore, the polarizing plate 200 with a retardation layer has the same variant shape as the polarizing plate 100.
  • the retardation layer 120 can also function as a protective layer for the polarizing element 10.
  • the retardation layer 120 is typically laminated on a polarizing plate 100 (polarizer 10 in the illustrated example) via an adhesive layer (not shown).
  • the adhesive layer is an adhesive layer or an adhesive layer, and is preferably an adhesive layer (for example, an acrylic adhesive layer) from the viewpoint of reworkability and the like.
  • the polarizing plate with a retardation layer may have another protective layer (not shown) on the retardation layer 120 side of the polarizing element 10, if necessary. Further, if necessary, the polarizing plate with a retardation layer may have another retardation layer (not shown) on the opposite side of the polarizing plate 100 of the retardation layer 120.
  • the Re (550) of the retardation layer 120 is preferably 100 nm to 190 nm, and the Re (450) / Re (550) is preferably 0.8 or more and less than 1. Further, the angle formed by the slow axis of the retardation layer 120 and the absorption axis of the polarizing element 10 is preferably 40 ° to 50 °.
  • phase difference layer 120 may have any suitable optical and / or mechanical properties depending on the intended purpose.
  • the retardation layer typically has a slow phase axis.
  • the angle ⁇ formed by the slow axis of the retardation layer and the absorption axis of the polarizing element 10 is preferably 40 ° to 50 °, more preferably 42 ° to 48 ° as described above. Yes, more preferably about 45 °. If the angle ⁇ is in such a range, as will be described later, by using a ⁇ / 4 plate as the retardation layer, a very excellent circularly polarized light characteristic (as a result, a very excellent antireflection characteristic) can be obtained. A polarizing plate with a difference layer can be obtained.
  • the retardation layer preferably shows a relationship in which the refractive index characteristic is nx> ny ⁇ nz.
  • the retardation layer is typically provided to impart antireflection properties to the polarizing plate and can function as a ⁇ / 4 plate in one embodiment.
  • the in-plane retardation Re (550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 160 nm.
  • the Nz coefficient of the retardation layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. .. By satisfying such a relationship, a very excellent reflected hue can be achieved when the obtained polarizing plate with a retardation layer is used in an image display device.
  • the retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It is also possible to exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measured light.
  • the retardation layer exhibits inverse dispersion wavelength characteristics.
  • Re (450) / Re (550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized.
  • the absolute value of the photoelastic coefficient is preferably 2 ⁇ 10 -11 m 2 / N or less, more preferably 2.0 ⁇ 10 -13 m 2 / N to 1.5 ⁇ 10 -11 m 2 /. It contains N, more preferably 1.0 ⁇ 10-12 m 2 / N to 1.2 ⁇ 10-11 m 2 / N.
  • the absolute value of the photoelastic coefficient is in such a range, the phase difference change is unlikely to occur when the shrinkage stress during heating occurs. As a result, thermal unevenness of the obtained image display device can be satisfactorily prevented.
  • the retardation layer is typically composed of a stretched film of a resin film.
  • the thickness of the retardation layer is preferably 70 ⁇ m or less, more preferably 45 ⁇ m to 60 ⁇ m.
  • the thickness of the retardation layer is preferably 40 ⁇ m or less, more preferably 10 ⁇ m to 40 ⁇ m, and further preferably 20 ⁇ m. It is ⁇ 30 ⁇ m.
  • the retardation layer may be composed of any suitable resin film that can satisfy the above characteristics.
  • suitable resins include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, and polyamide resins.
  • a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin) can be preferably used.
  • the polycarbonate-based resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol, and an alkylene.
  • a structural unit derived from a fluorene-based dihydroxy compound a structural unit derived from an isosorbide-based dihydroxy compound
  • an alicyclic diol an alicyclic dimethanol
  • di, tri or polyethylene glycol and an alkylene.
  • alkylene includes structural units derived from at least one dihydroxy compound selected from the group consisting of glycols or spiroglycols.
  • the polycarbonate-based resin is a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and / or di, tri or polyethylene glycol. Containing structural units derived from; more preferably structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. ..
  • the polycarbonate-based resin may contain structural units derived from other dihydroxy compounds, if necessary.
  • polycarbonate-based resin that can be suitably used for the present invention are, for example, JP-A-2014-10291, JP-A-2014-226666, JP-A-2015-212816, JP-A-2015-21217. , 2015-21218, and the description is incorporated herein by reference.
  • the glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 150 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, dimensional changes may occur after film molding, and the image quality of the obtained organic EL panel may be deteriorated. If the glass transition temperature is excessively high, the molding stability during film molding may be deteriorated, and the transparency of the film may be impaired.
  • the glass transition temperature is determined according to JIS K7121 (1987).
  • the molecular weight of the polycarbonate resin can be expressed by the reducing viscosity.
  • the reduced viscosity is measured by using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL, and using a Ubbelohde viscous tube at a temperature of 20.0 ° C. ⁇ 0.1 ° C.
  • the lower limit of the reduction viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more.
  • the upper limit of the reduction viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, and further preferably 0.80 dL / g.
  • the reduced viscosity is smaller than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced.
  • the reduced viscosity is larger than the upper limit value, the fluidity at the time of molding is lowered, and there may be a problem that the productivity and the moldability are lowered.
  • a commercially available film may be used as the polycarbonate resin film.
  • Specific examples of commercially available products include Teijin's product name "Pure Ace WR-S”, “Pure Ace WR-W”, “Pure Ace WR-M”, and Nitto Denko's product name "NRF”. Will be.
  • the retardation layer can be obtained, for example, by stretching a film formed of the above-mentioned polycarbonate resin.
  • a method for forming a film from a polycarbonate-based resin any appropriate molding processing method can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (for example, a casting method), a calendar molding method, and a hot press. The law etc. can be mentioned. Extrusion molding method or cast coating method is preferable. This is because the smoothness of the obtained film can be enhanced and good optical uniformity can be obtained.
  • the molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the retardation layer, and the like. As described above, since many film products of the polycarbonate resin are commercially available, the commercially available film may be subjected to the stretching treatment as it is.
  • the thickness of the resin film can be set to an arbitrary appropriate value according to a desired thickness of the retardation layer, desired optical characteristics, stretching conditions described later, and the like. It is preferably 50 ⁇ m to 300 ⁇ m.
  • any appropriate stretching method and stretching conditions for example, stretching temperature, stretching ratio, stretching direction
  • various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, and fixed-end contraction can be used alone or simultaneously or sequentially.
  • the stretching direction it can be performed in various directions and dimensions such as a length direction, a width direction, a thickness direction, and an oblique direction.
  • the stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C with respect to the glass transition temperature (Tg) of the resin film.
  • a retardation film having the desired optical characteristics for example, refractive index characteristics, in-plane retardation, Nz coefficient
  • the retardation film is produced by uniaxially stretching or fixed-end uniaxially stretching the resin film.
  • the fixed-end uniaxial stretching include a method of stretching the resin film in the width direction (lateral direction) while running the resin film in the longitudinal direction.
  • the draw ratio is preferably 1.1 to 3.5 times.
  • the retardation film can be produced by continuously diagonally stretching a long resin film in the direction of the above angle ⁇ with respect to the longitudinal direction.
  • a long stretched film having an orientation angle of an angle ⁇ with respect to the longitudinal direction of the film (a slow axis in the direction of the angle ⁇ ) can be obtained.
  • Roll-to-roll is possible, and the manufacturing process can be simplified.
  • the angle ⁇ may be an angle formed by the absorption axis of the polarizing element and the slow axis of the retardation layer in the polarizing plate with a retardation layer.
  • the angle ⁇ is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably about 45 °.
  • Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or vertical directions.
  • the tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as the long resin film can be continuously and diagonally stretched.
  • the stretching temperature of the film can change depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably Tg-30 ° C to Tg + 30 ° C, more preferably Tg-15 ° C to Tg + 15 ° C, and most preferably Tg-10 ° C to Tg + 10 ° C. By stretching at such a temperature, a retardation layer having appropriate characteristics in the present invention can be obtained. Tg is the glass transition temperature of the constituent material of the film.
  • an embodiment of the present invention includes an image display device including such a polarizing plate or a polarizing plate with a retardation layer.
  • the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device).
  • the image display device according to the embodiment of the present invention includes the polarizing plate according to the above item A or the polarizing plate with a retardation layer according to the item B on the visible side thereof.
  • the polarizing plate with a retardation layer is laminated so that the retardation layer is on the image display cell side (for example, a liquid crystal cell, an organic EL cell, an inorganic EL cell) (so that the polarizing element is on the visual recognition side).
  • the image display device preferably has a variant shape other than a rectangle. In such an image display device, the effect of the embodiment of the present invention is remarkable.
  • Specific examples of the image display device having a deformed shape include a meter panel of an automobile, a smartphone, a tablet PC, and a smart watch.
  • Thickness Measured using an interference film thickness meter manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"
  • the calculated wavelength range used for the thickness calculation was 400 nm to 500 nm, and the refractive index was 1.53.
  • In-plane phase difference (Re) of PVA A phase difference measuring device (product name manufactured by Oji Measuring Instruments Co., Ltd.) is used for the polarizing element (polarizer unit) obtained by removing the resin base material from the laminate of the polarizing element / thermoplastic resin base material obtained in Examples and Comparative Examples.
  • KOBRA-31X100 / IR was used to evaluate the in-plane phase difference (Rpva) of PVA at a wavelength of 1000 nm (according to the explained principle, from the total in-plane phase difference at a wavelength of 1000 nm, the in-plane phase difference of iodine. (Ri) is subtracted).
  • the absorption edge wavelength was set to 600 nm.
  • Birefringence of PVA ( ⁇ n) The birefringence ( ⁇ n) of PVA was calculated by dividing the in-plane phase difference of PVA measured in (2) above by the thickness of the substituent.
  • a single transmittance Ts, a parallel transmittance Tp, and a orthogonal transmittance Tc were measured using a meter (“V-7100” manufactured by Nippon Spectroscopy Co., Ltd.).
  • These Ts, Tp and Tc are Y values measured by the JIS Z 8701 2 degree field of view (C light source) and corrected for luminosity factor. From the obtained Tp and Tc, the degree of polarization P was determined by the following formula.
  • Polarization degree P (%) ⁇ (Tp-Tc) / (Tp + Tc) ⁇ 1/2 ⁇ 100 It should be noted that the spectrophotometer can be used for the same measurement with "LPF-200" manufactured by Otsuka Electronics Co., Ltd., and the same measurement result can be obtained regardless of which spectrophotometer is used. Has been confirmed. (5) Puncture strength (breaking strength per unit thickness) Compression tester (manufactured by Kato Tech Co., Ltd., product name "NDG5" needle penetration force measurement specification) in which the stator is peeled off from the laminate of the stator / thermoplastic resin base material obtained in Examples and Comparative Examples and a needle is attached.
  • Puncture strength breaking strength per unit thickness
  • Compression tester manufactured by Kato Tech Co., Ltd., product name "NDG5" needle penetration force measurement specification
  • the breaking strength As the evaluation value, the breaking strength of 10 sample pieces was measured, and the average value thereof was used.
  • the needle used had a tip diameter of 1 mm ⁇ and 0.5R.
  • the polarizing element to be measured was fixed by sandwiching a jig having a circular opening having a diameter of about 11 mm from both sides of the polarizing element, and a needle was pierced into the center of the opening to perform a test.
  • the orientation function was calculated according to the following procedure.
  • the incident polarized infrared light is polarized light (s-polarized light) that vibrates parallel to the surface to which the germanium crystal sample is in close contact, and the extension direction of the substituent is perpendicular to the polarization direction of the measurement light (measurement light).
  • polarized light
  • parallel
  • I was calculated from the obtained absorbance spectrum, (2941 cm -1 intensity) I was calculated with reference to (3330 cm -1 intensity).
  • I ⁇ is (2941 cm -1 intensity) / (3330 cm -1 intensity) obtained from the absorbance spectrum obtained when the stretching direction of the modulator is arranged perpendicularly ( ⁇ ) with respect to the polarization direction of the measurement light.
  • I // is obtained from the absorbance spectrum obtained when the stretching direction of the splitter is arranged parallel (//) with respect to the polarization direction of the measurement light (2941 cm -1 intensity) / (3330 cm -1 intensity).
  • (2941 cm -1 intensity) is the absorbance of 2941 cm -1 when 2770 cm -1 and 2990 cm -1 , which are the bottoms of the absorbance spectrum, are used as baselines
  • (3330 cm -1 intensity) is 2990 cm ⁇ .
  • a separator was temporarily attached to the pressure-sensitive adhesive layer of the polarizing plate (or a polarizing plate with a retardation layer).
  • This laminate was cut out to a size of about 130 mm ⁇ about 70 mm.
  • the absorber was cut out so that the absorption axis was in the lateral direction.
  • a U-shaped notch having a width of 5 mm, a depth (length of the recess) of 6.85 mm, and a radius of curvature of 2.5 mm was formed in the central portion of the short side of the cut-out laminate.
  • the U-shaped notch was formed by end milling.
  • the outer diameter of the end mill was 4 mm, the feed rate was 500 mm / min, the rotation speed was 35,000 rpm, the amount of cutting and the number of times of cutting were 0.2 mm / time for rough cutting and 0.1 mm / time for finish cutting, for a total of 2 times.
  • the separator was peeled off from the laminate having the U-shaped notch formed, and attached to a glass plate (thickness 1.1 mm) via an acrylic pressure-sensitive adhesive layer.
  • This evaluation was performed using three polarizing plates (or polarizing plates with a retardation layer), and the number of polarizing plates (or polarizing plates with a retardation layer) in which cracks (substantially L-shaped cracks) were generated was determined. evaluated.
  • Example 1 Preparation of A Polarizer
  • a thermoplastic resin base material an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 ⁇ m) having a long shape, a water absorption of 0.75%, and a Tg of about 75 ° C. was used.
  • One side of the resin base material was subjected to corona treatment (treatment conditions: 55 W ⁇ min / m 2 ).
  • PVA-based resin 100 weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410" are mixed at a ratio of 9: 1. 13 parts by weight of potassium iodide was added to the part to prepare a PVA aqueous solution (coating liquid). The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 ⁇ m, and a laminate was prepared.
  • the obtained laminate was stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching treatment).
  • the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
  • a dyeing bath having a liquid temperature of 30 ° C. an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water
  • underwater stretching treatment the stretching ratio in the underwater stretching treatment was 1.25 times.
  • the laminate was immersed in a washing bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
  • cleaning treatment while drying in an oven kept at 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75 ° C. for about 2 seconds (dry shrinkage treatment).
  • the shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment was 2%. In this way, a polarizing element having a thickness of 7.4 ⁇ m was formed on the resin substrate.
  • the obtained protective layer forming composition can be used in the above 1. It was applied directly (that is, without forming an easy-adhesion layer) to the polarizing element surface of the resin substrate / polarizing element laminate obtained in 1), and the coating film was dried at 60 ° C. for 3 minutes. Then, using a high-pressure mercury lamp, ultraviolet rays were irradiated so that the integrated light amount was 600 mJ / cm 2 , and a protective layer was formed.
  • a photocationic polymerization initiator manufactured by San-Apro Co., Ltd., trade name: CPI (registered trademark) -100P
  • the thickness of the protective layer was 3 ⁇ m.
  • the resin base material was peeled off, and an acrylic pressure-sensitive adhesive layer (thickness 15 ⁇ m) was provided on the peeled surface. In this way, a polarizing plate having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer was obtained.
  • Example 5 The polarizing element (thickness:: 6.7 ⁇ m) was formed. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
  • Example 6-2 A laminate of resin base material / polarizing element (thickness: 6.7 ⁇ m) was obtained in the same manner as in Example 6-1.
  • 20 parts of epoxy resin manufactured by Mitsubishi Chemical Corporation, trade name: jER (registered trademark) YX6954BH30, weight average molecular weight: 36000, epoxy equivalent: 13000
  • jER registered trademark
  • YX6954BH30 weight average molecular weight: 36000, epoxy equivalent: 13000
  • an epoxy resin solution (20%) was added. Obtained.
  • This epoxy resin solution was applied to the surface of the polarizing element of the laminate using a wire bar, and the coating film was dried at 60 ° C. for 3 minutes to form a protective layer formed as a solidified product of the coating film.
  • the thickness of the protective layer was 3 ⁇ m.
  • the resin base material was peeled off, and the same acrylic pressure-sensitive adhesive layer as in Example 1 was provided on the peeled surface. In this way, a polarizing plate having a structure of a protective layer (solidified layer of an epoxy resin coating film) / a polarizing element / an adhesive layer was obtained.
  • Example 6-3 A laminate of resin base material / polarizing element (thickness: 6.7 ⁇ m) was obtained in the same manner as in Example 6-1.
  • a polyurethane-based water-based dispersion resin manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Superflex SF210
  • An adhesive layer was formed.
  • an acrylic resin manufactured by Kusumoto Kasei Co., Ltd., product name: B-7248 which is 100% polymethylmethacrylate was dissolved in 80 parts by weight of methyl ethyl ketone to obtain an acrylic resin solution (20%).
  • This acrylic resin solution was applied to the surface of the easy-adhesion layer using a wire bar, and the coating film was dried at 60 ° C. for 5 minutes to form a protective layer composed of a solidified coating film.
  • the thickness of the protective layer was 2 ⁇ m.
  • a hard coat layer (thickness 3 ⁇ m) was further formed on the surface of the protective layer opposite to the easy-adhesion layer.
  • the hard coat (HC) layer is 70 parts by weight of dimethylol-tricyclodecanediacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate DCP-A), isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate IB-XA). ) 20 parts by weight, 1,9-nonanediol diacrylate (Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate 1.9NA-A) 10 parts by weight, and a photopolymerization initiator (BASF Co., Ltd., trade name: Irgacure 907).
  • dimethylol-tricyclodecanediacrylate manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate DCP-A
  • isobornyl acrylate manufactured by Kyoeisha Chemical Co., Ltd., trade name: light
  • a polarizing element (thickness: 6.2 ⁇ m) was formed on the resin substrate in the same manner as in Example 1 except that: 7) was used. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
  • a polarizing element (thickness: 6.0 ⁇ m) was formed on the resin substrate in the same manner as in Example 1 except that: 7) was used. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
  • Example 1 The polarizing element (thickness:: 5.5 ⁇ m) was formed. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
  • Comparative Example 2-2 Protective layer (solidified layer of epoxy resin coating film) / polarizing element / adhesive in the same manner as in Comparative Example 2-1 except that the protective layer was formed using the same epoxy resin solution as in Example 6-2. A polarizing plate having a layer structure was obtained.
  • Example 17 1. Preparation of a retardation film constituting the retardation layer Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C.
  • the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.
  • a long resin film having a thickness of 130 ⁇ m was prepared by using a film forming apparatus equipped with a chill roll (set temperature: 120 to 130 ° C.) and a winder.
  • the obtained long resin film was stretched while adjusting so that a predetermined retardation was obtained, to obtain a retardation film having a thickness of 48 ⁇ m.
  • the stretching conditions were a stretching temperature of 143 ° C. and a stretching ratio of 2.8 times in the width direction.
  • the Re (550) of the obtained retardation film was 141 nm, the Re (450) / Re (550) was 0.86, and the Nz coefficient was 1.12.
  • Example 2 the same acrylic pressure-sensitive adhesive layer as in Example 1 was provided on the surface of the retardation layer.
  • a polarizing plate with a retardation layer having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / pressure-sensitive adhesive layer / retardation layer / pressure-sensitive adhesive layer was obtained.
  • Comparative Example 5 A laminate of resin base material / polarizing element (thickness: 5.5 ⁇ m) was obtained in the same manner as in Comparative Example 2-1. A retardation layer having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / pressure-sensitive adhesive layer / retardation layer / pressure-sensitive adhesive layer in the same manner as in Example 17 except that this laminate is used. A polarizing plate was obtained.
  • FIGS. 8 to 10 show the relationship between the simple substance transmittance of the polarizing element obtained in Examples and Comparative Examples, ⁇ n of PVA, the in-plane phase difference, or the orientation function, respectively.
  • ⁇ n of PVA simple substance transmittance of the polarizing element obtained in Examples and Comparative Examples
  • ⁇ n of PVA in-plane phase difference
  • the orientation function is the same (as a result, the degree of orientation is the same)
  • the single transmittance is high, the deformed shape is processed. It can be seen that cracks are likely to occur in the portion. For example, when ⁇ n is around 35 ( ⁇ 10 -3 ) in FIG.
  • the polarizing plate of the present invention is used for an image display device, and is particularly preferably used for an image display device having a deformed shape such as an automobile meter panel, a smartphone, a tablet PC, or a smart watch.

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Abstract

Provided is a polarizing plate in which the occurrence of cracking in a deformed portion is suppressed although being extremely thin. This polarizing plate includes a polarizer, and a protective layer provided on at least one side of the polarizer, and has a deformed shape other than a rectangular shape. The protective layer comprises a resin film having a thickness of 10 μm or less. The polarizer comprises a PVA-based resin film containing a dichroic material. In one embodiment, expression (1) is satisfied when the single transmittance of the polarizer is denoted by x%, and the birefringence of PVA-based resin is denoted by y. In another embodiment, expression (2) is satisfied when the single transmittance of the polarizer is denoted by x%, and the in-plane phase difference of the PVA-based resin film is denoted by z nm. In still another embodiment, expression (3) is satisfied when the single transmittance of the polarizer is denoted by x%, and the orientation function of the PVA-based resin is denoted by f. In yet another embodiment, the piercing strength of the polarizer is 30 gf/μm or more. (1): y < -0.011x+0.525 (2): z < -60x+2875 (3): f < -0.018x+1.11

Description

偏光板、位相差層付偏光板、ならびに、該偏光板または該位相差層付偏光板を含む画像表示装置An image display device including a polarizing plate, a polarizing plate with a retardation layer, and the polarizing plate or a polarizing plate with a retardation layer.
 本発明は、偏光板、位相差層付偏光板、ならびに、該偏光板または該位相差層付偏光板を含む画像表示装置に関する。 The present invention relates to a polarizing plate, a polarizing plate with a retardation layer, and an image display device including the polarizing plate or the polarizing plate with a retardation layer.
 近年、液晶表示装置およびエレクトロルミネセンス(EL)表示装置(例えば、有機EL表示装置、無機EL表示装置)に代表される画像表示装置が急速に普及している。画像表示装置の画像形成方式に起因して、画像表示装置の少なくとも一方には偏光板が配置されている。近年、画像表示装置の薄型化への要望が高まるのに伴い、偏光板についても薄型化の要望が高まっている。ところで、近年、偏光板を矩形以外に加工すること(異形加工:例えば、ノッチおよび/または貫通穴の形成)が望まれる場合がある。しかし、薄型偏光板の異形加工部においては、クラックが発生しやすいという問題がある。 In recent years, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have rapidly become widespread. Due to the image forming method of the image display device, a polarizing plate is arranged on at least one of the image display devices. In recent years, as the demand for thinner image display devices has increased, the demand for thinner polarizing plates has also increased. By the way, in recent years, it may be desired to process a polarizing plate to a shape other than a rectangle (deformed processing: for example, formation of a notch and / or a through hole). However, there is a problem that cracks are likely to occur in the deformed portion of the thin polarizing plate.
特開2001-343521号公報Japanese Unexamined Patent Publication No. 2001-343521
 本発明は上記従来の課題を解決するためになされたものであり、その主たる目的は、極めて薄型でありながら、異形加工部におけるクラック発生が抑制された偏光板を提供することにある。 The present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a polarizing plate which is extremely thin and in which crack generation in a deformed portion is suppressed.
 本発明の1つの実施形態による偏光板は、偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有し、かつ、矩形以外の異形を有する。該保護層は10μm以下の厚みを有する樹脂膜で構成されている。該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂の複屈折をyとした場合に、下記式(1)を満たす:
  y<-0.011x+0.525        (1)。
 本発明の別の実施形態による偏光板は、偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有し、かつ、矩形以外の異形を有する。該保護層は10μm以下の厚みを有する樹脂膜で構成されている。該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂フィルムの面内位相差をznmとした場合に、下記式(2)を満たす:
  z<-60x+2875        (2)。
 本発明のさらに別の実施形態による偏光板は、偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有し、かつ、矩形以外の異形を有する。該保護層は10μm以下の厚みを有する樹脂膜で構成されている。該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂の配向関数をfとした場合に、下記式(3)を満たす:
  f<-0.018x+1.11    (3)。
 本発明のさらに別の実施形態による偏光板は、偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有し、かつ、矩形以外の異形を有する。該保護層は10μm以下の厚みを有する樹脂膜で構成されている。該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、偏光子の突き刺し強度が30gf/μm以上である。
 1つの実施形態において、上記偏光子の厚みは10μm以下である。
 1つの実施形態において、上記偏光子の単体透過率は40.0%以上であり、かつ、偏光度が99.0%以上である。
 1つの実施形態においては、上記異形は、貫通穴、V字ノッチ、U字ノッチ、平面視した場合に船形に近似した形状の凹部、平面視した場合に矩形の凹部、平面視した場合にバスタブ形状に近似したR形状の凹部、およびこれらの組み合わせからなる群から選択される。
 1つの実施形態においては、上記U字ノッチの曲率半径は5mm以下である。
 1つの実施形態においては、上記樹脂膜は、エポキシ樹脂および(メタ)アクリル系樹脂から選択される少なくとも1種の樹脂を含む。
 1つの実施形態においては、上記樹脂膜はエポキシ樹脂の光カチオン硬化物で構成されており、該樹脂膜の軟化温度は100℃以上である。
 1つの実施形態においては、上記樹脂膜はエポキシ樹脂の有機溶媒溶液の塗布膜の固化物で構成されており、該樹脂膜の軟化温度は100℃以上である。
 1つの実施形態においては、上記樹脂膜は熱可塑性(メタ)アクリル系樹脂の有機溶媒溶液の塗布膜の固化物で構成されており、該樹脂膜の軟化温度は100℃以上である。1つの実施形態においては、上記熱可塑性(メタ)アクリル系樹脂は、ラクトン環単位、無水グルタル酸単位、グルタルイミド単位、無水マレイン酸単位およびマレイミド単位からなる群から選択される少なくとも1つを有する。
 本発明の別の局面によれば、位相差層付偏光板が提供される。当該位相差層付偏光板は、上記の偏光板と位相差層とを含み、該位相差層は、上記偏光子の上記保護層が配置された側と反対側に配置されている。
 1つの実施形態においては、上記位相差層のRe(550)は100nm~190nmであり、Re(450)/Re(550)は0.8以上1未満であり、該位相差層の遅相軸と上記偏光子の吸収軸とのなす角度は40°~50°である。
 1つの実施形態においては、上記位相差層は粘着剤層を介して上記偏光板に積層されている。
 本発明のさらに別の局面によれば、画像表示装置が提供される。当該画像表示装置は、上記の偏光板または上記の位相差層付偏光板を含む。
The polarizing plate according to one embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape. The protective layer is made of a resin film having a thickness of 10 μm or less. When the polarizing element is made of a polyvinyl alcohol-based resin film containing a dichroic substance, the single transmittance is x%, and the birefringence of the polyvinyl alcohol-based resin is y, the following formula (1) is used. Meet:
y <−0.011x + 0.525 (1).
A polarizing plate according to another embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape. The protective layer is made of a resin film having a thickness of 10 μm or less. The polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the in-plane retardation of the polyvinyl alcohol-based resin film is znm, the following formula is used. Satisfy (2):
z <-60x + 2875 (2).
The polarizing plate according to still another embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape. The protective layer is made of a resin film having a thickness of 10 μm or less. The polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the orientation function of the polyvinyl alcohol-based resin is f, the following formula (3) is used. Meet:
f <−0.018x + 1.11 (3).
The polarizing plate according to still another embodiment of the present invention has a polarizing element and a protective layer arranged on at least one side of the polarizing element, and has a non-rectangular shape. The protective layer is made of a resin film having a thickness of 10 μm or less. The polarizing element is made of a polyvinyl alcohol-based resin film containing a dichroic substance, and the piercing strength of the polarizing element is 30 gf / μm or more.
In one embodiment, the thickness of the polarizing element is 10 μm or less.
In one embodiment, the simple substance transmittance of the above-mentioned extruder is 40.0% or more, and the degree of polarization is 99.0% or more.
In one embodiment, the variant has a through hole, a V-shaped notch, a U-shaped notch, a recess with a shape similar to a ship shape when viewed in plan view, a rectangular recess when viewed in plan view, and a bathtub when viewed in plan view. It is selected from a group consisting of R-shaped recesses that approximate the shape and combinations thereof.
In one embodiment, the radius of curvature of the U-shaped notch is 5 mm or less.
In one embodiment, the resin film comprises at least one resin selected from epoxy resins and (meth) acrylic resins.
In one embodiment, the resin film is composed of a photocationically cured product of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
In one embodiment, the resin film is composed of a solidified coating film of an organic solvent solution of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
In one embodiment, the resin film is composed of a solidified coating film of an organic solvent solution of a thermoplastic (meth) acrylic resin, and the softening temperature of the resin film is 100 ° C. or higher. In one embodiment, the thermoplastic (meth) acrylic resin has at least one selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit and a maleimide unit. ..
According to another aspect of the present invention, a polarizing plate with a retardation layer is provided. The polarizing plate with a retardation layer includes the above-mentioned polarizing plate and the above-mentioned retardation layer, and the retardation layer is arranged on the side opposite to the side where the above-mentioned protective layer of the above-mentioned polarizing element is arranged.
In one embodiment, Re (550) of the retardation layer is 100 nm to 190 nm, Re (450) / Re (550) is 0.8 or more and less than 1, and the slow axis of the retardation layer. The angle formed by the above-mentioned polarizing element with the absorption axis is 40 ° to 50 °.
In one embodiment, the retardation layer is laminated on the polarizing plate via an adhesive layer.
According to yet another aspect of the present invention, an image display device is provided. The image display device includes the above-mentioned polarizing plate or the above-mentioned polarizing plate with a retardation layer.
 本発明の実施形態によれば、異形(異形加工部)を有する偏光板において、偏光子のポリビニルアルコール(PVA)系樹脂の配向状態を制御することにより、極めて薄型でありながら、異形加工部におけるクラック発生が抑制された偏光板を実現することができる。また、このような偏光子(結果として、偏光板)は、実用上許容可能な光学特性を発揮し得る。 According to the embodiment of the present invention, in a polarizing plate having a deformed shape (deformed portion), by controlling the orientation state of the polyvinyl alcohol (PVA) -based resin of the polarizing element, the polarizing plate is extremely thin, but the deformed portion is formed. It is possible to realize a polarizing plate in which crack generation is suppressed. Further, such a polarizing element (as a result, a polarizing plate) can exhibit practically acceptable optical characteristics.
本発明の1つの実施形態による偏光板の概略断面図である。It is a schematic sectional drawing of the polarizing plate by one Embodiment of this invention. 本発明の実施形態による偏光板における異形または異形加工部の一例を説明する概略平面図である。It is a schematic plan view explaining an example of the deformed or deformed processed part in the polarizing plate by embodiment of this invention. 本発明の実施形態による偏光板における異形または異形加工部の変形例を説明する概略平面図である。It is a schematic plan view explaining the deformation example of the deformed or deformed part in the polarizing plate by embodiment of this invention. 本発明の実施形態による偏光板における異形または異形加工部のさらなる変形例を説明する概略平面図である。It is a schematic plan view explaining the further modification of the deformed or deformed processed portion in the polarizing plate according to the embodiment of the present invention. 本発明の実施形態による偏光板における異形または異形加工部のさらなる変形例を説明する概略平面図である。It is a schematic plan view explaining the further modification of the deformed or deformed processed portion in the polarizing plate according to the embodiment of the present invention. 本発明の実施形態による偏光板に用いられ得る偏光子の製造方法における加熱ロールを用いた乾燥収縮処理の一例を示す概略図である。It is a schematic diagram which shows an example of the drying shrinkage process using a heating roll in the method of manufacturing a polarizing element which can be used for a polarizing plate by embodiment of this invention. 本発明の1つの実施形態による位相差層付偏光板の概略断面図である。It is the schematic sectional drawing of the polarizing plate with a retardation layer by one Embodiment of this invention. 実施例および比較例で作製した偏光子の単体透過率とPVA系樹脂の複屈折との関係を示すグラフである。It is a graph which shows the relationship between the simple substance transmittance of the polarizing element produced in an Example and the comparative example, and the birefringence of a PVA-based resin. 実施例および比較例で作製した偏光子の単体透過率とPVA系樹脂フィルムの面内位相差との関係を示すグラフである。It is a graph which shows the relationship between the simple substance transmittance of the elemental transmittance and the in-plane phase difference of a PVA-based resin film produced in an Example and a comparative example. 実施例および比較例で作製した偏光子の単体透過率とPVA系樹脂の配向関数との関係を示すグラフである。It is a graph which shows the relationship between the simple substance transmittance of the elemental transmittance and the orientation function of a PVA-based resin produced in an Example and a comparative example.
 以下、本発明の実施形態について説明するが、本発明はこれらの実施形態には限定されない。 Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
A.偏光板
A-1.偏光板の全体構成
 図1は、本発明の1つの実施形態による偏光板の概略断面図である。図示例の偏光板100は、偏光子10と、偏光子10の一方の側に配置された保護層20と、を有する。目的に応じて、偏光子10の保護層20と反対側に別の保護層(図示せず)が設けられてもよい。保護層20は10μm以下の厚みを有する樹脂膜で構成されている。偏光板は、画像表示装置の視認側偏光板として用いられてもよく、背面側偏光板として用いられてもよい。偏光板は、代表的には視認側偏光板として用いられる。この場合、保護層20は、視認側(画像表示セルと反対側)に配置され得る。
A. Polarizing plate A-1. Overall Configuration of Polarizing Plate FIG. 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. The polarizing plate 100 of the illustrated example has a polarizing element 10 and a protective layer 20 arranged on one side of the polarizing element 10. A separate protective layer (not shown) may be provided on the opposite side of the protector 10 from the protective layer 20 depending on the purpose. The protective layer 20 is made of a resin film having a thickness of 10 μm or less. The polarizing plate may be used as a viewing-side polarizing plate of an image display device, or may be used as a back-side polarizing plate. The polarizing plate is typically used as a viewing-side polarizing plate. In this case, the protective layer 20 may be arranged on the visual recognition side (the side opposite to the image display cell).
 本発明の実施形態による偏光板は、矩形以外の異形を有する。本明細書において「矩形以外の異形を有する」とは、偏光板の平面視形状が矩形以外の形状を有することをいう。異形は、代表的には、異形加工された異形加工部である。したがって、「矩形以外の異形を有する偏光板」(以下、「異形偏光板」と称する場合がある)は、異形偏光板全体(すなわち、偏光板の平面視形状を規定する外縁)が矩形以外である場合のみならず、矩形の偏光板の外縁から内方に離間した部分に異形加工部が形成されている場合も包含する。偏光板において、このような異形加工部にはクラックが発生しやすいところ、本発明の実施形態によれば、そのようなクラックを顕著に抑制することができる。より詳細には、以下のとおりである。通常の(すなわち、異形ではない)偏光板(実質的には、偏光子)においては、クラックは多くの場合偏光子の吸収軸(延伸方向)に沿って発生する。一方、異形加工部においては、L字クラック(吸収軸に対して斜め方向のクラック)が発生し得る。本発明の実施形態によれば、後述するように、偏光子のPVA系樹脂の分子鎖の吸収軸方向への配向を従来の偏光子よりも緩やかにすることにより、通常のクラックのみならずこのようなL字クラックも顕著に抑制することができる。 The polarizing plate according to the embodiment of the present invention has a variant shape other than a rectangle. As used herein, the term "having a variant other than a rectangle" means that the planar view shape of the polarizing plate has a shape other than a rectangle. The irregular shape is typically a deformed portion that has been deformed. Therefore, in the "polarizing plate having a deformed shape other than a rectangle" (hereinafter, may be referred to as a "deformed polarizing plate"), the entire deformed polarizing plate (that is, the outer edge defining the planar view shape of the polarizing plate) is other than a rectangle. This includes not only a certain case but also a case where a deformed portion is formed in a portion inwardly separated from the outer edge of the rectangular polarizing plate. In the polarizing plate, cracks are likely to occur in such a deformed portion, and according to the embodiment of the present invention, such cracks can be remarkably suppressed. More details are as follows. In a normal (ie, non-deformed) polarizing plate (essentially a polarizing element), cracks often occur along the absorber's absorption axis (stretching direction). On the other hand, L-shaped cracks (cracks in the diagonal direction with respect to the absorption axis) may occur in the deformed portion. According to the embodiment of the present invention, as will be described later, by making the orientation of the molecular chain of the PVA-based resin of the polarizing element in the direction of the absorption axis gentler than that of the conventional polarizing element, not only ordinary cracks but also this crack can be achieved. Such L-shaped cracks can also be remarkably suppressed.
 異形(異形加工部)としては、例えば図2および図3に示すように、隅部をR形状に面取りしたもの、貫通穴、平面視した場合に凹部となる切削加工部が挙げられる。凹部の代表例としては、船形に近似した形状、矩形、バスタブ形状に近似したR形状、V字ノッチ、U字ノッチが挙げられる。異形(異形加工部)の別の例としては、図4および図5に示すように、自動車のメーターパネルに対応した形状が挙げられる。当該形状は、外縁がメーター針の回転方向に沿った円弧状に形成され、かつ、外縁が面方向内方に凸のV字形状(R形状を含む)をなす部位を含む。言うまでもなく、異形(異形加工部)の形状は図示例に限定されない。例えば、貫通穴の形状は、図示例の略円形以外に目的に応じて任意の適切な形状(例えば、楕円形、三角形、四角形、五角形、六角形、八角形)が採用され得る。また、貫通穴は、目的に応じて任意の適切な位置に設けられる。貫通穴は、図3に示すように、矩形状の偏光板の長手方向端部の略中央部に設けられてもよく、長手方向端部の所定の位置に設けられてもよく、偏光板の隅部に設けられてもよく;図示していないが、矩形状の偏光板の短手方向端部に設けられてもよく;図4または図5に示すように、異形偏光板の中央部に設けられてもよい。図3に示すように、貫通穴を複数設けてもよい。さらに、図示例の形状を目的に応じて適切に組み合わせてもよい。例えば、図2の異形偏光板の任意の位置に貫通穴を形成してもよく;図4または図5の異形偏光板の外縁の任意の適切な位置にV字ノッチおよび/またはU字ノッチを形成してもよい。このような異形偏光板は、自動車のメーターパネル、スマートフォン、タブレット型PCまたはスマートウォッチ等の画像表示装置に好適に用いられ得る。なお、例えば異形がR形状を含む場合、その曲率半径は、例えば0.2mm以上であり、また例えば1mm以上であり、また例えば2mm以上である。一方、曲率半径は、例えば10mm以下であり、また例えば5mm以下である。また例えば、異形がU字ノッチである場合、その曲率半径(U字部分の曲率半径は)、例えば5mm以下であり、また例えば1mm~4mmであり、また例えば2mm~3mmである。 Examples of the irregular shape (deformed portion) include a chamfered corner portion in an R shape, a through hole, and a cutting portion that becomes a concave portion when viewed in a plan view, as shown in FIGS. 2 and 3. Typical examples of the recess include a shape similar to a ship shape, a rectangle, an R shape similar to a bathtub shape, a V-shaped notch, and a U-shaped notch. As another example of the irregular shape (deformed portion), as shown in FIGS. 4 and 5, there is a shape corresponding to the instrument panel of an automobile. The shape includes a portion where the outer edge is formed in an arc shape along the rotation direction of the meter needle and the outer edge forms a V-shape (including an R shape) convex inward in the plane direction. Needless to say, the shape of the deformed shape (deformed portion) is not limited to the illustrated example. For example, as the shape of the through hole, any appropriate shape (for example, ellipse, triangle, quadrangle, pentagon, hexagon, octagon) may be adopted depending on the purpose other than the substantially circular shape in the illustrated example. Further, the through hole is provided at an arbitrary appropriate position according to the purpose. As shown in FIG. 3, the through hole may be provided at a substantially central portion of the longitudinal end portion of the rectangular polarizing plate, or may be provided at a predetermined position at the longitudinal end portion of the polarizing plate. It may be provided at the corners; although not shown, it may be provided at the lateral end of the rectangular polarizing plate; at the center of the deformed polarizing plate as shown in FIG. 4 or FIG. It may be provided. As shown in FIG. 3, a plurality of through holes may be provided. Further, the shapes of the illustrated examples may be appropriately combined according to the purpose. For example, a through hole may be formed at any position on the modified polarizing plate of FIG. 2; a V-shaped notch and / or a U-shaped notch may be formed at any appropriate position on the outer edge of the modified polarizing plate of FIG. 4 or FIG. It may be formed. Such a deformed polarizing plate can be suitably used for an image display device such as an automobile meter panel, a smartphone, a tablet PC or a smart watch. For example, when the variant includes an R shape, the radius of curvature thereof is, for example, 0.2 mm or more, for example, 1 mm or more, and for example, 2 mm or more. On the other hand, the radius of curvature is, for example, 10 mm or less, and is, for example, 5 mm or less. Further, for example, when the irregular shape is a U-shaped notch, the radius of curvature (the radius of curvature of the U-shaped portion) is, for example, 5 mm or less, for example, 1 mm to 4 mm, and for example, 2 mm to 3 mm.
 異形(異形加工部)は、任意の適切な方法により形成され得る。形成方法の具体例としては、エンドミルによる切削、トムソン刃等の打ち抜き刃による打ち抜き、レーザー光照射による切断が挙げられる。これらの方法は組み合わせてもよい。 The variant (deformed portion) can be formed by any suitable method. Specific examples of the forming method include cutting with an end mill, punching with a punching blade such as a Thomson blade, and cutting with laser light irradiation. These methods may be combined.
A-2.偏光子
 偏光子は、二色性物質を含むPVA系樹脂フィルムで構成されている。1つの実施形態において、偏光子は、単体透過率をx%とし、当該偏光子を構成するポリビニルアルコール系樹脂の複屈折をyとした場合に、下記式(1)を満たす。1つの実施形態において、偏光子は、単体透過率をx%とし、当該偏光子を構成するポリビニルアルコール系樹脂フィルムの面内位相差をznmとした場合に、下記式(2)を満たす。1つの実施形態において、偏光子は、単体透過率をx%とし、当該偏光子を構成するポリビニルアルコール系樹脂の配向関数をfとした場合に、下記式(3)を満たす。1つの実施形態において、偏光子の突き刺し強度は、30gf/μm以上である。
   y<-0.011x+0.525    (1)
   z<-60x+2875        (2)
   f<-0.018x+1.11     (3)
A-2. Polarizer The polarizing element is composed of a PVA-based resin film containing a dichroic substance. In one embodiment, the polarizing element satisfies the following formula (1) when the simple substance transmittance is x% and the birefringence of the polyvinyl alcohol-based resin constituting the polarizing element is y. In one embodiment, the substituent satisfies the following formula (2) when the simple substance transmittance is x% and the in-plane retardation of the polyvinyl alcohol-based resin film constituting the polarizing element is znm. In one embodiment, the polarizing element satisfies the following formula (3) when the simple substance transmittance is x% and the orientation function of the polyvinyl alcohol-based resin constituting the polarizing element is f. In one embodiment, the puncture strength of the polarizing element is 30 gf / μm or more.
y <-0.011x + 0.525 (1)
z <-60x + 2875 (2)
f <-0.018x + 1.11 (3)
 上記偏光子におけるPVA系樹脂の複屈折(以下、PVAの複屈折またはPVAのΔnと表記する)、PVA系樹脂フィルムの面内位相差(以下、「PVAの面内位相差」と表記する)、PVA系樹脂の配向関数(以下、「PVAの配向関数」と表記する)および偏光子の突き刺し強度はいずれも、偏光子を構成するPVA系樹脂の分子鎖の配向度と関連する値である。具体的には、PVAの複屈折、面内位相差および配向関数は、配向度の上昇に伴って大きい値となり得、突き刺し強度は、配向度の上昇に伴って低下し得る。本発明の実施形態による偏光子(すなわち、上記式(1)~(3)または突き刺し強度を満たす偏光子)は、PVA系樹脂の分子鎖の吸収軸方向への配向が従来の偏光子よりも緩やかであることに起因して、吸収軸方向の加熱収縮が抑制される。その結果、このような偏光子(結果として、偏光板)は、極めて薄型でありながら、異形加工部におけるクラック発生を抑制することができる。また、このような偏光子(結果として、偏光板)は可撓性および折り曲げ耐久性にも優れることから、好ましくは湾曲した画像表示装置、より好ましくは折り曲げ可能な画像表示装置、さらに好ましくは折り畳み可能な画像表示装置に適用され得る。従来、配向度が低い偏光子では許容可能な光学特性(代表的には、単体透過率および偏光度)を得るのが困難であったところ、本発明の実施形態に用いられる偏光子は、従来よりも低いPVA系樹脂の配向度と許容可能な光学特性とを両立することができる。 Double refraction of PVA-based resin in the above deflector (hereinafter referred to as PVA double refraction or PVA Δn), in-plane phase difference of PVA-based resin film (hereinafter referred to as “PVA in-plane phase difference”). , The orientation function of the PVA-based resin (hereinafter referred to as "orientation function of PVA") and the piercing strength of the modulator are both values related to the degree of orientation of the molecular chains of the PVA-based resin constituting the modulator. .. Specifically, the birefringence, in-plane phase difference and orientation function of PVA can be large as the degree of orientation increases, and the puncture strength can decrease as the degree of orientation increases. In the polarizing element according to the embodiment of the present invention (that is, the polarizing element satisfying the above formulas (1) to (3) or the piercing strength), the orientation of the molecular chain of the PVA-based resin in the absorption axis direction is larger than that of the conventional polarizing element. Due to the gradualness, heat shrinkage in the absorption axis direction is suppressed. As a result, such a polarizing element (as a result, a polarizing plate) can suppress the occurrence of cracks in the deformed portion while being extremely thin. Further, since such a polarizing element (as a result, a polarizing plate) is also excellent in flexibility and bending durability, a curved image display device is preferable, a bendable image display device is more preferable, and a folding image display device is more preferable. It can be applied to possible image display devices. Conventionally, it has been difficult to obtain acceptable optical characteristics (typically, simple substance transmittance and degree of polarization) with a polarizing element having a low degree of orientation. It is possible to achieve both a lower degree of orientation of the PVA-based resin and an acceptable optical property.
 偏光子は、好ましくは下記式(1a)および/または式(2a)を満たし、より好ましくは下記式(1b)および/または式(2b)を満たす。
  -0.004x+0.18<y<-0.011x+0.525   (1a)
  -0.003x+0.145<y<-0.011x+0.520   (1b)
  -40x+1800<z<-60x+2875   (2a)
  -30x+1450<z<-60x+2850   (2b)
The polarizing element preferably satisfies the following formulas (1a) and / or the following formula (2a), and more preferably the following formulas (1b) and / or the formula (2b).
-0.004x + 0.18 <y <-0.011x + 0.525 (1a)
-0.003x + 0.145 <y <-0.011x + 0.520 (1b)
-40x + 180 <z <-60x + 2875 (2a)
-30x + 1450 <z <-60x + 2850 (2b)
 本明細書において、上記PVAの面内位相差は、23℃、波長1000nmにおけるPVA系樹脂フィルムの面内位相差値である。近赤外領域を測定波長とすることにより、偏光子中のヨウ素の吸収の影響を排除することができ、位相差を測定することが可能となる。また、上記PVAの複屈折(面内複屈折)は、PVAの面内位相差を偏光子の厚みで割った値である。 In the present specification, the in-plane retardation value of PVA is the in-plane retardation value of the PVA-based resin film at 23 ° C. and a wavelength of 1000 nm. By setting the measurement wavelength in the near-infrared region, the influence of absorption of iodine in the polarizing element can be eliminated, and the phase difference can be measured. The birefringence of PVA (in-plane birefringence) is a value obtained by dividing the in-plane phase difference of PVA by the thickness of the polarizing element.
 PVAの面内位相差は、下記のように評価する。まず、波長850nm以上の複数の波長で位相差値を測定し、測定された位相差値:R(λ)と波長:λのプロットを行い、これを下記のセルマイヤー式に最小二乗法でフィッティングさせる。ここで、AおよびBはフィッティングパラメータであり最小二乗法により決定される係数である。
  R(λ)=A+B/(λ-600
 このとき、この位相差値R(λ)は、波長依存性のないPVAの面内位相差(Rpva)と、波長依存性の強いヨウ素の面内位相差値(Ri)とに下記のように分離することができる。
  Rpva= A
  Ri  = B/(λ-600
 この分離式に基づいて、波長λ=1000nmにおけるPVAの面内位相差(すなわちRpva)を算出することができる。なお、当該PVAの面内位相差の評価方法については、特許第5932760号公報にも記載されており、必要に応じて、参照することができる。
 また、この位相差を厚みで割ることでPVAの複屈折(Δn)を算出することができる。
The in-plane phase difference of PVA is evaluated as follows. First, the phase difference value is measured at a plurality of wavelengths having a wavelength of 850 nm or more, the measured phase difference value: R (λ) and the wavelength: λ are plotted, and this is fitted to the following Selmeyer equation by the least squares method. Let me. Here, A and B are fitting parameters and coefficients determined by the least squares method.
R (λ) = A + B / (λ 2-600 2 )
At this time, the phase difference value R (λ) is divided into the in-plane phase difference (Rpva) of PVA having no wavelength dependence and the in-plane phase difference value (Ri) of iodine having a strong wavelength dependence as follows. Can be separated.
Rpva = A
Ri = B / (λ 2-600 2 )
Based on this separation formula, the in-plane phase difference (that is, Rpva) of PVA at a wavelength of λ = 1000 nm can be calculated. The method for evaluating the in-plane phase difference of the PVA is also described in Japanese Patent No. 5923760, and can be referred to as necessary.
Further, the birefringence (Δn) of PVA can be calculated by dividing this phase difference by the thickness.
 上記波長1000nmにおけるPVAの面内位相差を測定する市販の装置としては、王子計測社製のKOBRA-WR/IRシリーズ、KOBRA-31X/IRシリーズ等があげられる。 Examples of commercially available devices for measuring the in-plane phase difference of PVA at a wavelength of 1000 nm include KOBRA-WR / IR series and KOBRA-31X / IR series manufactured by Oji Measurement Co., Ltd.
 偏光子の配向関数(f)は、好ましくは下記式(3a)を満たし、より好ましくは下記式(3b)を満たす。配向関数が小さすぎると、許容可能な単体透過率および/または偏光度が得られない場合がある。
  -0.01x+0.50<f<-0.018x+1.11   (3a)
  -0.01x+0.57<f<-0.018x+1.1    (3b)
The orientation function (f) of the polarizing element preferably satisfies the following formula (3a), and more preferably the following formula (3b). If the orientation function is too small, acceptable single transmittance and / or degree of polarization may not be obtained.
-0.01x + 0.50 <f <-0.018x + 1.11 (3a)
-0.01x + 0.57 <f <-0.018x + 1.1 (3b)
 配向関数(f)は、例えば、フーリエ変換赤外分光光度計(FT-IR)を用い、偏光を測定光として、全反射減衰分光(ATR:attenuated total reflection)測定により求められる。具体的には、偏光子を密着させる結晶子はゲルマニウムを用い、測定光の入射角は45°入射とし、入射させる偏光された赤外光(測定光)は、ゲルマニウム結晶のサンプルを密着させる面に平行に振動する偏光(s偏光)とし、測定光の偏光方向に対し、偏光子の延伸方向を平行および垂直に配置した状態で測定を実施し、得られた吸光度スペクトルの2941cm-1の強度を用いて、下記式に従って算出される。ここで、強度Iは、3330cm-1を参照ピークとして、2941cm-1/3330cm-1の値である。なお、f=1のとき完全配向、f=0のときランダムとなる。また、2941cm-1のピークは、偏光子中のPVAの主鎖(-CH-)の振動に起因する吸収であると考えられている。
          f=(3<cosθ>-1)/2
           =(1-D)/[c(2D+1)]
            =-2×(1-D)/(2D+1)
ただし、
c=(3cosβ-1)/2で、2941cm-1の振動の場合は、β=90°である。
θ:延伸方向に対する分子鎖の角度
β:分子鎖軸に対する遷移双極子モーメントの角度
D=(I)/(I//)  (この場合、PVA分子が配向するほどDが大きくなる)
 :測定光の偏光方向と偏光子の延伸方向が垂直の場合の吸収強度
// :測定光の偏光方向と偏光子の延伸方向が平行の場合の吸収強度
The orientation function (f) is obtained by total internal reflection spectroscopy (ATR) measurement using, for example, a Fourier transform infrared spectrophotometer (FT-IR) and polarized light as measurement light. Specifically, germanium is used as the crystallite to which the polarizing element is brought into close contact, the incident angle of the measurement light is 45 °, and the polarized infrared light (measurement light) to be incident is the surface to which the sample of the germanium crystal is brought into close contact. The polarization (s - polarized light) that vibrates in parallel with the light is used, and the measurement is performed with the extension directions of the substituents arranged parallel and perpendicular to the polarization direction of the measurement light. Is calculated according to the following formula. Here, the intensity I is a value of 2941 cm -1/3330 cm -1 with 3330 cm -1 as a reference peak. When f = 1, it is completely oriented, and when f = 0, it is random. Further, the peak of 2941 cm -1 is considered to be absorption caused by the vibration of the main chain (-CH 2- ) of PVA in the polarizing element.
f = (3 <cos 2 θ> -1) / 2
= (1-D) / [c (2D + 1)]
= -2 x (1-D) / (2D + 1)
However,
In the case of vibration of 2941 cm -1 with c = (3cos 2 β-1) / 2, β = 90 °.
θ: Angle of molecular chain with respect to stretching direction β: Angle of transition dipole moment with respect to molecular chain axis D = (I ) / (I // ) (In this case, D becomes larger as the PVA molecule is oriented)
I : Absorption intensity when the polarization direction of the measurement light and the extension direction of the modulator are perpendicular I // : Absorption intensity when the polarization direction of the measurement light and the extension direction of the modulator are parallel
 偏光子の厚みは、好ましくは10μm以下であり、より好ましくは8μm以下である。偏光子の厚みの下限は、例えば1μmであり得る。偏光子の厚みは、1つの実施形態においては2μm~10μm、別の実施形態においては2μm~8μmであってもよい。偏光子の厚みをこのように非常に薄くすることにより、熱収縮を非常に小さくすることができる。このような構成が、偏光板の異形加工部におけるクラック発生の抑制にも寄与し得ると推察される。 The thickness of the polarizing element is preferably 10 μm or less, more preferably 8 μm or less. The lower limit of the thickness of the transducer can be, for example, 1 μm. The thickness of the polarizing element may be 2 μm to 10 μm in one embodiment and 2 μm to 8 μm in another embodiment. By making the thickness of the stator very thin in this way, the heat shrinkage can be made very small. It is presumed that such a configuration can also contribute to suppressing the occurrence of cracks in the deformed portion of the polarizing plate.
 偏光子は、好ましくは、波長380nm~780nmのいずれかの波長で吸収二色性を示す。偏光子の単体透過率は、好ましくは40.0%以上であり、より好ましくは41.0%以上である。単体透過率の上限は、例えば49.0%であり得る。偏光子の単体透過率は、1つの実施形態においては40.0%~45.0%である。偏光子の偏光度は、好ましくは99.0%以上であり、より好ましくは99.4%以上である。偏光度の上限は、例えば99.999%であり得る。偏光子の偏光度は、1つの実施形態においては99.0%~99.9%である。本発明の実施形態による偏光子は、当該偏光子を構成するPVA系樹脂の配向度が従来よりも低く、上記のような面内位相差、複屈折および/または配向関数を有するにもかかわらず、このような実用上許容可能な単体透過率および偏光度を実現できることを1つの特徴とする。これは、後述する製造方法に起因するものと推察される。なお、単体透過率は、代表的には、紫外可視分光光度計を用いて測定し、視感度補正を行なったY値である。偏光度は、代表的には、紫外可視分光光度計を用いて測定して視感度補正を行なった平行透過率Tpおよび直交透過率Tcに基づいて、下記式により求められる。
   偏光度(%)={(Tp-Tc)/(Tp+Tc)}1/2×100
The polarizing element preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the polarizing element is preferably 40.0% or more, more preferably 41.0% or more. The upper limit of the single transmittance can be, for example, 49.0%. The simple substance transmittance of the polarizing element is 40.0% to 45.0% in one embodiment. The degree of polarization of the polarizing element is preferably 99.0% or more, more preferably 99.4% or more. The upper limit of the degree of polarization can be, for example, 99.999%. The degree of polarization of the polarizing element is 99.0% to 99.9% in one embodiment. Despite the fact that the polarizing element according to the embodiment of the present invention has a lower degree of orientation of the PVA-based resin constituting the polarizing element than the conventional one and has the above-mentioned in-plane phase difference, birefringence and / or orientation function. One of the features is that such a practically acceptable single-unit transmittance and degree of polarization can be realized. It is presumed that this is due to the manufacturing method described later. The single transmittance is typically a Y value measured with an ultraviolet-visible spectrophotometer and corrected for luminosity factor. The degree of polarization is typically determined by the following equation based on the parallel transmittance Tp and the orthogonal transmittance Tc measured with an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
Polarization degree (%) = {(Tp-Tc) / (Tp + Tc)} 1/2 × 100
 偏光子の突き刺し強度は、例えば30gf/μm以上であり、好ましくは35gf/μm以上であり、より好ましくは40gf/μm以上であり、さらに好ましくは45gf/μm以上であり、特に好ましくは50gf/μm以上である。突き刺し強度の上限は、例えば80gf/μmであり得る。偏光子の突き刺し強度をこのような範囲とすることにより、異形加工部にクラックが発生すること、および、偏光子が吸収軸方向に沿って裂けることを顕著に抑制することができる。その結果、屈曲性に非常に優れた偏光子(結果として、偏光板)が得られ得る。突き刺し強度は、所定の強さで偏光子を突き刺した時の偏光子の割れ耐性を示す。突き刺し強度は、例えば、圧縮試験機に所定のニードルを装着し、当該ニードルを所定速度で偏光子に突き刺したときに偏光子が割れる強度(破断強度)として表され得る。なお、単位から明らかなとおり、突き刺し強度は、偏光子の単位厚み(1μm)あたりの突き刺し強度を意味する。 The puncture strength of the polarizing element is, for example, 30 gf / μm or more, preferably 35 gf / μm or more, more preferably 40 gf / μm or more, still more preferably 45 gf / μm or more, and particularly preferably 50 gf / μm or more. That is all. The upper limit of the piercing strength can be, for example, 80 gf / μm. By setting the piercing strength of the polarizing element within such a range, it is possible to remarkably suppress the occurrence of cracks in the deformed portion and the splitting of the polarizing element along the absorption axis direction. As a result, a polarizing element having very excellent flexibility (as a result, a polarizing plate) can be obtained. The piercing strength indicates the cracking resistance of the polarizing element when the polarizing element is pierced with a predetermined strength. The piercing strength can be expressed as, for example, the strength (breaking strength) at which the polarizing element is cracked when a predetermined needle is attached to a compression tester and the needle is pierced into the polarizing element at a predetermined speed. As is clear from the unit, the piercing strength means the piercing strength per unit thickness (1 μm) of the polarizing element.
 偏光子は、上記のとおり、二色性物質を含むPVA系樹脂フィルムで構成される。好ましくは、PVA系樹脂フィルム(実質的には、偏光子)を構成するPVA系樹脂は、アセトアセチル変性されたPVA系樹脂を含む。このような構成であれば、所望の突き刺し強度を有する偏光子が得られ得る。アセトアセチル変性されたPVA系樹脂の配合量は、PVA系樹脂全体を100重量%としたときに、好ましくは5重量%~20重量%であり、より好ましくは8重量%~12重量%である。配合量がこのような範囲であれば、突き刺し強度をより好適な範囲とすることができる。 As described above, the polarizing element is composed of a PVA-based resin film containing a dichroic substance. Preferably, the PVA-based resin constituting the PVA-based resin film (substantially, a polarizing element) contains an acetoacetyl-modified PVA-based resin. With such a configuration, a polarizing element having a desired piercing strength can be obtained. The blending amount of the acetoacetyl-modified PVA-based resin is preferably 5% by weight to 20% by weight, more preferably 8% by weight to 12% by weight, when the total amount of the PVA-based resin is 100% by weight. .. When the blending amount is in such a range, the piercing strength can be in a more suitable range.
 偏光子は、代表的には、二層以上の積層体を用いて作製され得る。積層体を用いて得られる偏光子の具体例としては、樹脂基材と当該樹脂基材に塗布形成されたPVA系樹脂層との積層体を用いて得られる偏光子が挙げられる。樹脂基材と当該樹脂基材に塗布形成されたPVA系樹脂層との積層体を用いて得られる偏光子は、例えば、PVA系樹脂溶液を樹脂基材に塗布し、乾燥させて樹脂基材上にPVA系樹脂層を形成して、樹脂基材とPVA系樹脂層との積層体を得ること;当該積層体を延伸および染色してPVA系樹脂層を偏光子とすること;により作製され得る。本実施形態においては、好ましくは、樹脂基材の片側に、ハロゲン化物とポリビニルアルコール系樹脂とを含むポリビニルアルコール系樹脂層を形成する。延伸は、代表的には積層体をホウ酸水溶液中に浸漬させて延伸することを含む。さらに、延伸は、好ましくは、ホウ酸水溶液中での延伸の前に積層体を高温(例えば、95℃以上)で空中延伸することをさらに含む。本発明の実施形態においては、延伸の総倍率は好ましくは3.0倍~4.5倍であり、通常に比べて顕著に小さい。このような延伸の総倍率であっても、ハロゲン化物の添加および乾燥収縮処理との組み合わせにより、許容可能な光学特性を有する偏光子を得ることができる。さらに、本発明の実施形態においては、好ましくは空中補助延伸の延伸倍率がホウ酸水中延伸の延伸倍率よりも大きい。このような構成とすることにより、延伸の総倍率が小さくても許容可能な光学特性を有する偏光子を得ることができる。加えて、積層体は、好ましくは長手方向に搬送しながら加熱することにより幅方向に2%以上収縮させる乾燥収縮処理に供される。1つの実施形態においては、偏光子の製造方法は、積層体に、空中補助延伸処理と染色処理と水中延伸処理と乾燥収縮処理とをこの順に施すことを含む。補助延伸を導入することにより、熱可塑性樹脂上にPVA系樹脂を塗布する場合でも、PVA系樹脂の結晶性を高めることが可能となり、高い光学特性を達成することが可能となる。また、同時にPVA系樹脂の配向性を事前に高めることで、後の染色工程や延伸工程で水に浸漬された時に、PVA系樹脂の配向性の低下や溶解等の問題を防止することができ、高い光学特性を達成することが可能になる。さらに、PVA系樹脂層を液体に浸漬した場合において、PVA系樹脂層がハロゲン化物を含まない場合に比べて、ポリビニルアルコール分子の配向の乱れ、および配向性の低下が抑制され得る。これにより、染色処理および水中延伸処理等、積層体を液体に浸漬して行う処理工程を経て得られる偏光子の光学特性を向上し得る。さらに、乾燥収縮処理により積層体を幅方向に収縮させることにより、光学特性を向上させることができる。得られた樹脂基材/偏光子の積層体はそのまま用いてもよく(すなわち、樹脂基材を偏光子の保護層としてもよく)、樹脂基材/偏光子の積層体から樹脂基材を剥離し、当該剥離面に目的に応じた任意の適切な保護層を積層して用いてもよい。偏光子の製造方法の詳細については、A-3項で説明する。 The decoder can typically be made using a laminate of two or more layers. Specific examples of the polarizing element obtained by using the laminated body include a polarizing element obtained by using a laminated body of a resin base material and a PVA-based resin layer coated and formed on the resin base material. The polarizing element obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a stator. obtain. In the present embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin base material. Stretching typically involves immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching preferably further comprises stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in an aqueous boric acid solution. In the embodiment of the present invention, the total magnification of stretching is preferably 3.0 to 4.5 times, which is significantly smaller than usual. Even at the total magnification of such stretching, a stator having acceptable optical properties can be obtained by combining the addition of a halide and the drying shrinkage treatment. Further, in the embodiment of the present invention, the stretching ratio of the aerial auxiliary stretching is preferably larger than the stretching ratio of the boric acid water stretching. With such a configuration, it is possible to obtain a polarizing element having acceptable optical characteristics even if the total magnification of stretching is small. In addition, the laminate is preferably subjected to a drying shrinkage treatment of shrinking by 2% or more in the width direction by heating while transporting in the longitudinal direction. In one embodiment, the method for producing a polarizing element includes subjecting a laminate to an aerial auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when the PVA-based resin is coated on the thermoplastic resin, the crystallinity of the PVA-based resin can be enhanced, and high optical characteristics can be achieved. At the same time, by increasing the orientation of the PVA-based resin in advance, it is possible to prevent problems such as deterioration of the orientation of the PVA-based resin and dissolution when immersed in water in the subsequent dyeing step or stretching step. , It becomes possible to achieve high optical characteristics. Further, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This makes it possible to improve the optical characteristics of the polarizing element obtained through a treatment step of immersing the laminate in a liquid, such as a dyeing treatment and a stretching treatment in water. Further, the optical characteristics can be improved by shrinking the laminated body in the width direction by the drying shrinkage treatment. The obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. The details of the method for manufacturing the stator will be described in Section A-3.
A-3.偏光子の製造方法
 上記偏光子の製造方法は、好ましくは、長尺状の熱可塑性樹脂基材の片側に、ハロゲン化物とポリビニルアルコール系樹脂(PVA系樹脂)とを含むポリビニルアルコール系樹脂層(PVA系樹脂層)を形成して積層体とすること、および、積層体に、空中補助延伸処理と、染色処理と、水中延伸処理と、長手方向に搬送しながら加熱することにより幅方向に2%以上収縮させる乾燥収縮処理と、をこの順に施すことを含む。PVA系樹脂層におけるハロゲン化物の含有量は、好ましくは、PVA系樹脂100重量部に対して5重量部~20重量部である。乾燥収縮処理は、加熱ロールを用いて処理することが好ましく、加熱ロールの温度は、好ましくは60℃~120℃である。乾燥収縮処理による積層体の幅方向の収縮率は、好ましくは2%以上である。さらに、空中補助延伸の延伸倍率は、好ましくは水中延伸の延伸倍率よりも大きい。このような製造方法によれば、上記A-2項で説明した偏光子を得ることができる。特に、ハロゲン化物を含むPVA系樹脂層を含む積層体を作製し、上記積層体の延伸を空中補助延伸及び水中延伸を含む多段階延伸とし、延伸後の積層体を加熱ロールで加熱して幅方向に2%以上収縮させることにより、優れた光学特性(代表的には、単体透過率および偏光度)を有する偏光子を得ることができる。
A-3. Method for manufacturing a polarizing element In the above method for manufacturing a polarizing element, a polyvinyl alcohol-based resin layer (preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin base material (preferably A PVA-based resin layer) is formed to form a laminated body, and the laminated body is heated in the width direction by performing an aerial auxiliary stretching treatment, a dyeing treatment, and an underwater stretching treatment while transporting the laminated body in the longitudinal direction. It includes performing a dry shrinkage treatment for shrinking by% or more in this order. The content of the halide in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin. The drying shrinkage treatment is preferably performed using a heating roll, and the temperature of the heating roll is preferably 60 ° C. to 120 ° C. The shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment is preferably 2% or more. Further, the stretch ratio of the aerial auxiliary stretch is preferably larger than the stretch ratio of the underwater stretch. According to such a manufacturing method, the modulator described in Section A-2 above can be obtained. In particular, a laminate containing a PVA-based resin layer containing a halide is prepared, the stretching of the laminate is a multi-step stretching including aerial auxiliary stretching and underwater stretching, and the stretched laminate is heated with a heating roll to have a width. By shrinking by 2% or more in the direction, a stator having excellent optical properties (typically, single transmittance and degree of polarization) can be obtained.
A-3-1.積層体の作製
 熱可塑性樹脂基材とPVA系樹脂層との積層体を作製する方法としては、任意の適切な方法が採用され得る。好ましくは、熱可塑性樹脂基材の表面に、ハロゲン化物とPVA系樹脂とを含む塗布液を塗布し、乾燥することにより、熱可塑性樹脂基材上にPVA系樹脂層を形成する。上記のとおり、PVA系樹脂層におけるハロゲン化物の含有量は、好ましくはPVA系樹脂100重量部に対して5重量部~20重量部である。
A-3-1. Preparation of Laminate As a method for preparing a laminate of a thermoplastic resin base material and a PVA-based resin layer, any appropriate method can be adopted. Preferably, a coating liquid containing a halide and a PVA-based resin is applied to the surface of the thermoplastic resin base material and dried to form a PVA-based resin layer on the thermoplastic resin base material. As described above, the content of the halide in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
 塗布液の塗布方法としては、任意の適切な方法を採用することができる。例えば、ロールコート法、スピンコート法、ワイヤーバーコート法、ディップコート法、ダイコート法、カーテンコート法、スプレーコート法、ナイフコート法(コンマコート法等)等が挙げられる。上記塗布液の塗布・乾燥温度は、好ましくは50℃以上である。 Any appropriate method can be adopted as the application method of the coating liquid. For example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.) and the like can be mentioned. The coating / drying temperature of the coating liquid is preferably 50 ° C. or higher.
 PVA系樹脂層の厚みは、好ましくは2μm~30μm、さらに好ましくは2μm~20μmである。延伸前のPVA系樹脂層の厚みをこのように非常に薄くし、かつ、後述するように延伸の総倍率を小さくすることにより、従来よりもPVA系樹脂の配向度が低いにもかかわらず許容可能な単体透過率および偏光度を有する偏光子を得ることができる。 The thickness of the PVA-based resin layer is preferably 2 μm to 30 μm, more preferably 2 μm to 20 μm. By making the thickness of the PVA-based resin layer before stretching very thin in this way and reducing the total magnification of stretching as described later, it is acceptable even though the degree of orientation of the PVA-based resin is lower than before. It is possible to obtain a polarizing element having a possible single transmittance and a degree of polarization.
 PVA系樹脂層を形成する前に、熱可塑性樹脂基材に表面処理(例えば、コロナ処理等)を施してもよいし、熱可塑性樹脂基材上に易接着層を形成してもよい。このような処理を行うことにより、熱可塑性樹脂基材とPVA系樹脂層との密着性を向上させることができる。 Before forming the PVA-based resin layer, the thermoplastic resin base material may be surface-treated (for example, corona treatment or the like), or the easy-adhesion layer may be formed on the thermoplastic resin base material. By performing such a treatment, the adhesion between the thermoplastic resin base material and the PVA-based resin layer can be improved.
A-3-1-1.熱可塑性樹脂基材
 熱可塑性樹脂基材としては、任意の適切な熱可塑性樹脂フィルムが採用され得る。熱可塑性樹脂基材の詳細については、例えば特開2012-73580号公報に記載されている。当該公報は、その全体の記載が本明細書に参考として援用される。
A-3-1-1. Thermoplastic resin base material As the thermoplastic resin base material, any suitable thermoplastic resin film can be adopted. Details of the thermoplastic resin base material are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.
A-3-1-2.塗布液
 塗布液は、上記のとおり、ハロゲン化物とPVA系樹脂とを含む。上記塗布液は、代表的には、上記ハロゲン化物および上記PVA系樹脂を溶媒に溶解させた溶液である。溶媒としては、例えば、水、ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミド、N-メチルピロリドン、各種グリコール類、トリメチロールプロパン等の多価アルコール類、エチレンジアミン、ジエチレントリアミン等のアミン類が挙げられる。これらは単独で、または、二種以上組み合わせて用いることができる。これらの中でも、好ましくは、水である。溶液のPVA系樹脂濃度は、溶媒100重量部に対して、好ましくは3重量部~20重量部である。このような樹脂濃度であれば、熱可塑性樹脂基材に密着した均一な塗布膜を形成することができる。塗布液におけるハロゲン化物の含有量は、好ましくは、PVA系樹脂100重量部に対して5重量部~20重量部である。
A-3-1-2. Coating liquid The coating liquid contains a halide and a PVA-based resin as described above. The coating liquid is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Among these, water is preferable. The PVA-based resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, it is possible to form a uniform coating film in close contact with the thermoplastic resin base material. The content of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.
 塗布液に、添加剤を配合してもよい。添加剤としては、例えば、可塑剤、界面活性剤等が挙げられる。可塑剤としては、例えば、エチレングリコールやグリセリン等の多価アルコールが挙げられる。界面活性剤としては、例えば、非イオン界面活性剤が挙げられる。これらは、得られるPVA系樹脂層の均一性や染色性、延伸性をより一層向上させる目的で使用され得る。 Additives may be added to the coating liquid. Examples of the additive include a plasticizer, a surfactant and the like. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the obtained PVA-based resin layer.
 上記PVA系樹脂としては、任意の適切な樹脂が採用され得る。例えば、ポリビニルアルコールおよびエチレン-ビニルアルコール共重合体が挙げられる。ポリビニルアルコールは、ポリ酢酸ビニルをケン化することにより得られる。エチレン-ビニルアルコール共重合体は、エチレン-酢酸ビニル共重合体をケン化することにより得られる。PVA系樹脂のケン化度は、通常85モル%~100モル%であり、好ましくは95.0モル%~99.95モル%、さらに好ましくは99.0モル%~99.93モル%である。ケン化度は、JIS K 6726-1994に準じて求めることができる。このようなケン化度のPVA系樹脂を用いることによって、耐久性に優れた偏光子が得られ得る。ケン化度が高すぎる場合には、ゲル化してしまうおそれがある。上記のとおり、PVA系樹脂は、好ましくはアセトアセチル変性されたPVA系樹脂を含む。 Any suitable resin can be adopted as the PVA-based resin. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymers can be mentioned. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. .. The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a degree of saponification, a polarizing element having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur. As described above, the PVA-based resin preferably contains an acetoacetyl-modified PVA-based resin.
 PVA系樹脂の平均重合度は、目的に応じて適切に選択し得る。平均重合度は、通常1000~10000であり、好ましくは1200~4500、さらに好ましくは1500~4300である。なお、平均重合度は、JIS K 6726-1994に準じて求めることができる。 The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.
 上記ハロゲン化物としては、任意の適切なハロゲン化物が採用され得る。例えば、ヨウ化物および塩化ナトリウムが挙げられる。ヨウ化物としては、例えば、ヨウ化カリウム、ヨウ化ナトリウム、およびヨウ化リチウムが挙げられる。これらの中でも、好ましくは、ヨウ化カリウムである。 As the above-mentioned halide, any suitable halide can be adopted. For example, iodide and sodium chloride can be mentioned. Iodides include, for example, potassium iodide, sodium iodide, and lithium iodide. Among these, potassium iodide is preferable.
 塗布液におけるハロゲン化物の量は、好ましくは、PVA系樹脂100重量部に対して5重量部~20重量部であり、より好ましくは、PVA系樹脂100重量部に対して10重量部~15重量部である。PVA系樹脂100重量部に対するハロゲン化物の量が20重量部を超えると、ハロゲン化物がブリードアウトし、最終的に得られる偏光子が白濁する場合がある。 The amount of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, and more preferably 10 parts by weight to 15 parts by weight with respect to 100 parts by weight of the PVA-based resin. It is a department. If the amount of the halide exceeds 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, the halide may bleed out and the finally obtained polarizing element may become cloudy.
 一般に、PVA系樹脂層が延伸されることによって、PVA系樹脂層中のポリビニルアルコール分子の配向性が高くなるが、延伸後のPVA系樹脂層を、水を含む液体に浸漬すると、ポリビニルアルコール分子の配向が乱れ、配向性が低下する場合がある。特に、熱可塑性樹脂基材とPVA系樹脂層との積層体をホウ酸水中延伸する場合において、熱可塑性樹脂基材の延伸を安定させるために比較的高い温度で上記積層体をホウ酸水中で延伸する場合、上記配向度低下の傾向が顕著である。例えば、PVAフィルム単体のホウ酸水中での延伸が60℃で行われることが一般的であるのに対し、A-PET(熱可塑性樹脂基材)とPVA系樹脂層との積層体の延伸は70℃前後の温度という高い温度で行われ、この場合、延伸初期のPVAの配向性が水中延伸により上がる前の段階で低下し得る。これに対して、ハロゲン化物を含むPVA系樹脂層と熱可塑性樹脂基材との積層体を作製し、積層体をホウ酸水中で延伸する前に空気中で高温延伸(補助延伸)することにより、補助延伸後の積層体のPVA系樹脂層中のPVA系樹脂の結晶化が促進され得る。その結果、PVA系樹脂層を液体に浸漬した場合において、PVA系樹脂層がハロゲン化物を含まない場合に比べて、ポリビニルアルコール分子の配向の乱れ、および配向性の低下が抑制され得る。これにより、染色処理および水中延伸処理等、積層体を液体に浸漬して行う処理工程を経て得られる偏光子の光学特性を向上し得る。 Generally, the stretching of the PVA-based resin layer increases the orientation of the polyvinyl alcohol molecules in the PVA-based resin layer. However, when the stretched PVA-based resin layer is immersed in a liquid containing water, the polyvinyl alcohol molecules become higher. The orientation of the plastic may be disturbed and the orientation may decrease. In particular, when the laminate of the thermoplastic resin base material and the PVA-based resin layer is stretched in boric acid water, the laminate is stretched in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin base material. In the case of stretching, the tendency of the degree of orientation to decrease is remarkable. For example, while stretching a PVA film alone in boric acid water is generally performed at 60 ° C., stretching of a laminate of A-PET (thermoplastic resin base material) and a PVA-based resin layer is performed. It is carried out at a high temperature of about 70 ° C., and in this case, the orientation of PVA at the initial stage of stretching may decrease before it is increased by stretching in water. On the other hand, by preparing a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin base material, and stretching the laminate in air at a high temperature (auxiliary stretching) before stretching it in boric acid water. , Crystallization of the PVA-based resin in the PVA-based resin layer of the laminated body after the auxiliary stretching can be promoted. As a result, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This makes it possible to improve the optical characteristics of the polarizing element obtained through a treatment step of immersing the laminate in a liquid, such as a dyeing treatment and a stretching treatment in water.
A-3-2.空中補助延伸処理
 特に、高い光学特性を得るためには、乾式延伸(補助延伸)とホウ酸水中延伸を組み合わせる、2段延伸の方法が選択される。2段延伸のように、補助延伸を導入することにより、熱可塑性樹脂基材の結晶化を抑制しながら延伸することができる。さらには、熱可塑性樹脂基材上にPVA系樹脂を塗布する場合、熱可塑性樹脂基材のガラス転移温度の影響を抑制するために、通常の金属ドラム上にPVA系樹脂を塗布する場合と比べて塗布温度を低くする必要があり、その結果、PVA系樹脂の結晶化が相対的に低くなり、十分な光学特性が得られない、という問題が生じ得る。これに対して、補助延伸を導入することにより、熱可塑性樹脂上にPVA系樹脂を塗布する場合でも、PVA系樹脂の結晶性を高めることが可能となり、高い光学特性を達成することが可能となる。また、同時にPVA系樹脂の配向性を事前に高めることで、後の染色工程や延伸工程で水に浸漬された時に、PVA系樹脂の配向性の低下や溶解等の問題を防止することができ、高い光学特性を達成することが可能になる。
A-3-2. Aerial auxiliary stretching treatment In particular, in order to obtain high optical properties, a two-stage stretching method that combines dry stretching (auxiliary stretching) and boric acid water stretching is selected. By introducing auxiliary stretching as in the case of two-step stretching, it is possible to stretch while suppressing the crystallization of the thermoplastic resin base material. Furthermore, when the PVA-based resin is applied on the thermoplastic resin base material, it is compared with the case where the PVA-based resin is applied on a normal metal drum in order to suppress the influence of the glass transition temperature of the thermoplastic resin base material. Therefore, it is necessary to lower the coating temperature, and as a result, the crystallization of the PVA-based resin becomes relatively low, which may cause a problem that sufficient optical characteristics cannot be obtained. On the other hand, by introducing auxiliary stretching, it is possible to improve the crystallinity of the PVA-based resin even when the PVA-based resin is applied on the thermoplastic resin, and it is possible to achieve high optical characteristics. Become. At the same time, by increasing the orientation of the PVA-based resin in advance, it is possible to prevent problems such as deterioration of the orientation of the PVA-based resin and dissolution when immersed in water in the subsequent dyeing step or stretching step. , It becomes possible to achieve high optical characteristics.
 空中補助延伸の延伸方法は、固定端延伸(たとえば、テンター延伸機を用いて延伸する方法)でもよいし、自由端延伸(たとえば、周速の異なるロール間に積層体を通して一軸延伸する方法)でもよいが、高い光学特性を得るためには、自由端延伸が積極的に採用され得る。1つの実施形態においては、空中延伸処理は、上記積層体をその長手方向に搬送しながら、加熱ロール間の周速差により延伸する加熱ロール延伸工程を含む。空中延伸処理は、代表的には、ゾーン延伸工程と加熱ロール延伸工程とを含む。なお、ゾーン延伸工程と加熱ロール延伸工程の順序は限定されず、ゾーン延伸工程が先に行われてもよく、加熱ロール延伸工程が先に行われてもよい。ゾーン延伸工程は省略されてもよい。1つの実施形態においては、ゾーン延伸工程および加熱ロール延伸工程がこの順に行われる。また、別の実施形態では、テンター延伸機において、フィルム端部を把持し、テンター間の距離を流れ方向に広げることで延伸される(テンター間の距離の広がりが延伸倍率となる)。この時、幅方向(流れ方向に対して、垂直方向)のテンターの距離は、任意に近づくように設定される。好ましくは、流れ方向の延伸倍率に対して、自由端延伸により近くなるように設定され得る。自由端延伸の場合、幅方向の収縮率=(1/延伸倍率)1/2で計算される。 The stretching method of the aerial auxiliary stretching may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Although good, free-end stretching can be positively adopted in order to obtain high optical properties. In one embodiment, the aerial stretching treatment includes a heating roll stretching step of stretching the laminate by the difference in peripheral speed between the heating rolls while transporting the laminated body in the longitudinal direction thereof. The aerial stretching treatment typically includes a zone stretching step and a heating roll stretching step. The order of the zone stretching step and the heating roll stretching step is not limited, and the zone stretching step may be performed first, or the heating roll stretching step may be performed first. The zone stretching step may be omitted. In one embodiment, the zone stretching step and the heating roll stretching step are performed in this order. Further, in another embodiment, in the tenter stretching machine, the film is stretched by grasping the end portion of the film and widening the distance between the tenters in the flow direction (the widening of the distance between the tenters is the stretching ratio). At this time, the distance of the tenter in the width direction (perpendicular to the flow direction) is set to approach arbitrarily. Preferably, it can be set to be closer to the free end stretch with respect to the stretch ratio in the flow direction. In the case of free end stretching, it is calculated by shrinkage rate in the width direction = (1 / stretching ratio) 1/2 .
 空中補助延伸は、一段階で行ってもよいし、多段階で行ってもよい。多段階で行う場合、延伸倍率は、各段階の延伸倍率の積である。空中補助延伸における延伸方向は、好ましくは、水中延伸の延伸方向と略同一である。 The aerial auxiliary stretching may be performed in one step or in multiple steps. When performed in multiple stages, the draw ratio is the product of the draw ratios in each stage. The stretching direction in the aerial auxiliary stretching is preferably substantially the same as the stretching direction in the underwater stretching.
 空中補助延伸における延伸倍率は、好ましくは1.0倍~4.0倍であり、より好ましくは1.5倍~3.5倍であり、さらに好ましくは2.0倍~3.0倍である。空中補助延伸の延伸倍率がこのような範囲であれば、水中延伸と組み合わせた場合に延伸の総倍率を所望の範囲に設定することができ、所望の複屈折、面内位相差および/または配向関数を実現することができる。その結果、異形加工部におけるクラック発生が抑制された偏光子(結果として、偏光板)を得ることができる。さらに、上記のとおり、空中補助延伸の延伸倍率は水中延伸の延伸倍率よりも大きいことが好ましい。このような構成とすることにより、延伸の総倍率が小さくても許容可能な光学特性を有する偏光子を得ることができる。より詳細には、空中補助延伸の延伸倍率と水中延伸の延伸倍率との比(水中延伸/空中補助延伸)は、好ましくは0.4~0.9であり、より好ましくは0.5~0.8である。 The draw ratio in the aerial auxiliary stretching is preferably 1.0 to 4.0 times, more preferably 1.5 to 3.5 times, and further preferably 2.0 to 3.0 times. be. If the stretch ratio of the aerial auxiliary stretch is in such a range, the total stretch ratio can be set to a desired range when combined with the underwater stretch, and the desired birefringence, in-plane retardation and / or orientation can be set. Functions can be realized. As a result, it is possible to obtain a polarizing element (as a result, a polarizing plate) in which the generation of cracks in the deformed portion is suppressed. Further, as described above, it is preferable that the stretching ratio of the aerial auxiliary stretching is larger than the stretching ratio of the underwater stretching. With such a configuration, it is possible to obtain a polarizing element having acceptable optical characteristics even if the total magnification of stretching is small. More specifically, the ratio of the stretching ratio of the aerial auxiliary stretching to the stretching ratio of the underwater stretching (underwater stretching / aerial auxiliary stretching) is preferably 0.4 to 0.9, more preferably 0.5 to 0. It is 8.8.
 空中補助延伸の延伸温度は、熱可塑性樹脂基材の形成材料、延伸方式等に応じて、任意の適切な値に設定することができる。延伸温度は、好ましくは熱可塑性樹脂基材のガラス転移温度(Tg)以上であり、さらに好ましくは熱可塑性樹脂基材のガラス転移温度(Tg)+10℃以上、特に好ましくはTg+15℃以上である。一方、延伸温度の上限は、好ましくは170℃である。このような温度で延伸することで、PVA系樹脂の結晶化が急速に進むのを抑制して、当該結晶化による不具合(例えば、延伸によるPVA系樹脂層の配向を妨げる)を抑制することができる。 The stretching temperature of the aerial auxiliary stretching can be set to an arbitrary appropriate value depending on the forming material of the thermoplastic resin base material, the stretching method, and the like. The stretching temperature is preferably the glass transition temperature (Tg) or higher of the thermoplastic resin base material, more preferably the glass transition temperature (Tg) of the thermoplastic resin base material (Tg) + 10 ° C. or higher, and particularly preferably Tg + 15 ° C. or higher. On the other hand, the upper limit of the stretching temperature is preferably 170 ° C. By stretching at such a temperature, it is possible to suppress the rapid progress of crystallization of the PVA-based resin and suppress defects due to the crystallization (for example, hindering the orientation of the PVA-based resin layer due to stretching). can.
A-3-3.不溶化処理、染色処理および架橋処理
 必要に応じて、空中補助延伸処理の後、水中延伸処理や染色処理の前に、不溶化処理を施す。上記不溶化処理は、代表的には、ホウ酸水溶液にPVA系樹脂層を浸漬することにより行う。上記染色処理は、代表的には、PVA系樹脂層を二色性物質(代表的には、ヨウ素)で染色することにより行う。必要に応じて、染色処理の後、水中延伸処理の前に、架橋処理を施す。上記架橋処理は、代表的には、ホウ酸水溶液にPVA系樹脂層を浸漬させることにより行う。不溶化処理、染色処理および架橋処理の詳細については、例えば特開2012-73580号公報に記載されている。
A-3-3. Insolubilization treatment, dyeing treatment and cross-linking treatment If necessary, an insolubilization treatment is performed after the aerial auxiliary stretching treatment and before the underwater stretching treatment or the dyeing treatment. The insolubilization treatment is typically performed by immersing a PVA-based resin layer in a boric acid aqueous solution. The dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically iodine). If necessary, a cross-linking treatment is performed after the dyeing treatment and before the underwater stretching treatment. The cross-linking treatment is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution. Details of the insolubilization treatment, the dyeing treatment and the crosslinking treatment are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580.
A-3-4.水中延伸処理
 水中延伸処理は、積層体を延伸浴に浸漬させて行う。水中延伸処理によれば、上記熱可塑性樹脂基材やPVA系樹脂層のガラス転移温度(代表的には、80℃程度)よりも低い温度で延伸し得、PVA系樹脂層を、その結晶化を抑えながら延伸することができる。その結果、優れた光学特性を有する偏光子を製造することができる。
A-3-4. Underwater stretching treatment The underwater stretching treatment is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment, the thermoplastic resin base material or the PVA-based resin layer can be stretched at a temperature lower than the glass transition temperature (typically, about 80 ° C.), and the PVA-based resin layer is crystallized. Can be stretched while suppressing. As a result, it is possible to manufacture a polarizing element having excellent optical characteristics.
 積層体の延伸方法は、任意の適切な方法を採用することができる。具体的には、固定端延伸でもよいし、自由端延伸(例えば、周速の異なるロール間に積層体を通して一軸延伸する方法)でもよい。好ましくは、自由端延伸が選択される。積層体の延伸は、一段階で行ってもよいし、多段階で行ってもよい。多段階で行う場合、延伸の総倍率は、各段階の延伸倍率の積である。 Any appropriate method can be adopted as the stretching method of the laminated body. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Preferably, free-end stretching is selected. The stretching of the laminate may be carried out in one step or in multiple steps. When performed in multiple stages, the total stretching ratio is the product of the stretching ratios in each stage.
 水中延伸は、好ましくは、ホウ酸水溶液中に積層体を浸漬させて行う(ホウ酸水中延伸)。延伸浴としてホウ酸水溶液を用いることで、PVA系樹脂層に、延伸時にかかる張力に耐える剛性と、水に溶解しない耐水性とを付与することができる。具体的には、ホウ酸は、水溶液中でテトラヒドロキシホウ酸アニオンを生成してPVA系樹脂と水素結合により架橋し得る。その結果、PVA系樹脂層に剛性と耐水性とを付与して、良好に延伸することができ、優れた光学特性を有する偏光子を製造することができる。 The underwater stretching is preferably carried out by immersing the laminate in a boric acid aqueous solution (boric acid water stretching). By using the boric acid aqueous solution as the stretching bath, it is possible to impart rigidity to withstand the tension applied during stretching and water resistance that does not dissolve in water to the PVA-based resin layer. Specifically, boric acid can generate a tetrahydroxyboric acid anion in an aqueous solution and crosslink with a PVA-based resin by hydrogen bonding. As a result, the PVA-based resin layer can be imparted with rigidity and water resistance, can be stretched satisfactorily, and a polarizing element having excellent optical characteristics can be produced.
 上記ホウ酸水溶液は、好ましくは、溶媒である水にホウ酸および/またはホウ酸塩を溶解させることにより得られる。ホウ酸濃度は、水100重量部に対して、好ましくは1重量部~10重量部であり、より好ましくは2.5重量部~6重量部であり、特に好ましくは3重量部~5重量部である。ホウ酸濃度を1重量部以上とすることにより、PVA系樹脂層の溶解を効果的に抑制することができ、より高特性の偏光子を製造することができる。なお、ホウ酸またはホウ酸塩以外に、ホウ砂等のホウ素化合物、グリオキザール、グルタルアルデヒド等を溶媒に溶解して得られた水溶液も用いることができる。 The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight with respect to 100 parts by weight of water. Is. By setting the boric acid concentration to 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing element having higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde or the like in a solvent can also be used.
 好ましくは、上記延伸浴(ホウ酸水溶液)にヨウ化物を配合する。ヨウ化物を配合することにより、PVA系樹脂層に吸着させたヨウ素の溶出を抑制することができる。ヨウ化物の具体例は、上述のとおりである。ヨウ化物の濃度は、水100重量部に対して、好ましくは0.05重量部~15重量部、より好ましくは0.5重量部~8重量部である。 Preferably, iodide is added to the above stretching bath (boric acid aqueous solution). By blending iodide, the elution of iodine adsorbed on the PVA-based resin layer can be suppressed. Specific examples of iodide are as described above. The concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, and more preferably 0.5 parts by weight to 8 parts by weight with respect to 100 parts by weight of water.
 延伸温度(延伸浴の液温)は、好ましくは40℃~85℃、より好ましくは60℃~75℃である。このような温度であれば、PVA系樹脂層の溶解を抑制しながら高倍率に延伸することができる。具体的には、上述のように、熱可塑性樹脂基材のガラス転移温度(Tg)は、PVA系樹脂層の形成との関係で、好ましくは60℃以上である。この場合、延伸温度が40℃を下回ると、水による熱可塑性樹脂基材の可塑化を考慮しても、良好に延伸できないおそれがある。一方、延伸浴の温度が高温になるほど、PVA系樹脂層の溶解性が高くなって、優れた光学特性が得られないおそれがある。積層体の延伸浴への浸漬時間は、好ましくは15秒~5分である。 The stretching temperature (liquid temperature of the stretching bath) is preferably 40 ° C to 85 ° C, more preferably 60 ° C to 75 ° C. At such a temperature, the PVA-based resin layer can be stretched at a high magnification while suppressing dissolution. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin base material is preferably 60 ° C. or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40 ° C., it may not be stretched well even in consideration of the plasticization of the thermoplastic resin base material by water. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and there is a possibility that excellent optical characteristics cannot be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.
 水中延伸による延伸倍率は、好ましくは1.0倍~2.2倍であり、より好ましくは1.1倍~2.0倍であり、さらに好ましくは1.1倍~1.8倍であり、さらにより好ましくは1.2倍~1.6倍である。水中延伸における延伸倍率がこのような範囲であれば、延伸の総倍率を所望の範囲に設定することができ、所望の複屈折、面内位相差および/または配向関数を実現することができる。その結果、異形加工部におけるクラック発生が抑制された偏光子(結果として、偏光板)を得ることができる。延伸の総倍率(空中補助延伸と水中延伸とを組み合わせた場合の延伸倍率の合計)は、上記のとおり、積層体の元長に対して、好ましくは3.0倍~4.5倍であり、より好ましくは3.0倍~4.3倍であり、さらに好ましくは3.0倍~4.0倍である。塗布液へのハロゲン化物の添加、空中補助延伸および水中延伸の延伸倍率の調整、および乾燥収縮処理を適切に組み合わせることにより、このような延伸の総倍率であっても許容可能な光学特性を有する偏光子を得ることができる。 The stretching ratio by stretching in water is preferably 1.0 to 2.2 times, more preferably 1.1 times to 2.0 times, and further preferably 1.1 times to 1.8 times. , Even more preferably 1.2 to 1.6 times. When the stretching ratio in underwater stretching is in such a range, the total stretching ratio can be set in a desired range, and the desired birefringence, in-plane retardation and / or orientation function can be realized. As a result, it is possible to obtain a polarizing element (as a result, a polarizing plate) in which the generation of cracks in the deformed portion is suppressed. As described above, the total stretching ratio (the total stretching ratio when the aerial auxiliary stretching and the underwater stretching are combined) is preferably 3.0 to 4.5 times with respect to the original length of the laminated body. , More preferably 3.0 to 4.3 times, still more preferably 3.0 to 4.0 times. By appropriately combining the addition of a halide to the coating liquid, the adjustment of the stretching ratios of the aerial auxiliary stretching and the underwater stretching, and the drying shrinkage treatment, even the total magnification of such stretching has acceptable optical properties. A modulator can be obtained.
A-3-5.乾燥収縮処理
 上記乾燥収縮処理は、ゾーン全体を加熱して行うゾーン加熱により行っても良いし、搬送ロールを加熱する(いわゆる加熱ロールを用いる)ことにより行う(加熱ロール乾燥方式)こともできる。好ましくは、その両方を用いる。加熱ロールを用いて乾燥させることにより、効率的に積層体の加熱カールを抑制して、外観に優れた偏光子を製造することができる。具体的には、加熱ロールに積層体を沿わせた状態で乾燥することにより、上記熱可塑性樹脂基材の結晶化を効率的に促進させて結晶化度を増加させることができ、比較的低い乾燥温度であっても、熱可塑性樹脂基材の結晶化度を良好に増加させることができる。その結果、熱可塑性樹脂基材は、その剛性が増加して、乾燥によるPVA系樹脂層の収縮に耐え得る状態となり、カールが抑制される。また、加熱ロールを用いることにより、積層体を平らな状態に維持しながら乾燥できるので、カールだけでなくシワの発生も抑制することができる。この時、積層体は、乾燥収縮処理により幅方向に収縮させることにより、光学特性を向上させることができる。PVAおよびPVA/ヨウ素錯体の配向性を効果的に高めることができるからである。乾燥収縮処理による積層体の幅方向の収縮率は、好ましくは1%~10%であり、より好ましくは2%~8%であり、特に好ましくは2%~6%である。
A-3-5. Drying Shrinkage Treatment The drying shrinkage treatment may be performed by heating the entire zone by zone heating, or by heating the transport roll (using a so-called heating roll) (heating roll drying method). Preferably both are used. By drying using a heating roll, it is possible to efficiently suppress the heating curl of the laminate and produce a polarizing element having an excellent appearance. Specifically, by drying the laminated body along the heating roll, the crystallization of the thermoplastic resin base material can be efficiently promoted and the crystallinity can be increased, which is relatively low. Even at the drying temperature, the crystallinity of the thermoplastic resin substrate can be satisfactorily increased. As a result, the rigidity of the thermoplastic resin base material is increased, and the PVA-based resin layer is in a state of being able to withstand shrinkage due to drying, and curling is suppressed. Further, by using the heating roll, the laminated body can be dried while being maintained in a flat state, so that not only curling but also wrinkles can be suppressed. At this time, the laminated body can be improved in optical characteristics by shrinking in the width direction by a drying shrinkage treatment. This is because the orientation of PVA and the PVA / iodine complex can be effectively enhanced. The shrinkage ratio in the width direction of the laminate by the dry shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 2% to 6%.
 図6は、乾燥収縮処理の一例を示す概略図である。乾燥収縮処理では、所定の温度に加熱された搬送ロールR1~R6と、ガイドロールG1~G4とにより、積層体200を搬送しながら乾燥させる。図示例では、PVA樹脂層の面と熱可塑性樹脂基材の面を交互に連続加熱するように搬送ロールR1~R6が配置されているが、例えば、積層体200の一方の面(たとえば熱可塑性樹脂基材面)のみを連続的に加熱するように搬送ロールR1~R6を配置してもよい。 FIG. 6 is a schematic view showing an example of the drying shrinkage treatment. In the drying shrinkage treatment, the laminate 200 is dried while being transported by the transport rolls R1 to R6 heated to a predetermined temperature and the guide rolls G1 to G4. In the illustrated example, the transport rolls R1 to R6 are arranged so as to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin base material. For example, one surface of the laminate 200 (for example, thermoplasticity) is arranged. The transport rolls R1 to R6 may be arranged so as to continuously heat only the resin substrate surface).
 搬送ロールの加熱温度(加熱ロールの温度)、加熱ロールの数、加熱ロールとの接触時間等を調整することにより、乾燥条件を制御することができる。加熱ロールの温度は、好ましくは60℃~120℃であり、さらに好ましくは65℃~100℃であり、特に好ましくは70℃~80℃である。熱可塑性樹脂の結晶化度を良好に増加させて、カールを良好に抑制することができるとともに、耐久性に極めて優れた光学積層体を製造することができる。なお、加熱ロールの温度は、接触式温度計により測定することができる。図示例では、6個の搬送ロールが設けられているが、搬送ロールは複数個であれば特に制限はない。搬送ロールは、通常2個~40個、好ましくは4個~30個設けられる。積層体と加熱ロールとの接触時間(総接触時間)は、好ましくは1秒~300秒であり、より好ましくは1~20秒であり、さらに好ましくは1~10秒である。 Drying conditions can be controlled by adjusting the heating temperature of the transport roll (temperature of the heating roll), the number of heating rolls, the contact time with the heating roll, and the like. The temperature of the heating roll is preferably 60 ° C. to 120 ° C., more preferably 65 ° C. to 100 ° C., and particularly preferably 70 ° C. to 80 ° C. The crystallinity of the thermoplastic resin can be satisfactorily increased, curling can be satisfactorily suppressed, and an optical laminate having extremely excellent durability can be produced. The temperature of the heating roll can be measured with a contact thermometer. In the illustrated example, six transport rolls are provided, but there is no particular limitation as long as there are a plurality of transport rolls. The number of transport rolls is usually 2 to 40, preferably 4 to 30. The contact time (total contact time) between the laminate and the heating roll is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and further preferably 1 to 10 seconds.
 加熱ロールは、加熱炉(例えば、オーブン)内に設けてもよいし、通常の製造ライン(室温環境下)に設けてもよい。好ましくは、送風手段を備える加熱炉内に設けられる。加熱ロールによる乾燥と熱風乾燥とを併用することにより、加熱ロール間での急峻な温度変化を抑制することができ、幅方向の収縮を容易に制御することができる。熱風乾燥の温度は、好ましくは30℃~100℃である。また、熱風乾燥時間は、好ましくは1秒~300秒である。熱風の風速は、好ましくは10m/s~30m/s程度である。なお、当該風速は加熱炉内における風速であり、ミニベーン型デジタル風速計により測定することができる。 The heating roll may be provided in a heating furnace (for example, an oven) or in a normal production line (in a room temperature environment). Preferably, it is provided in a heating furnace provided with an air blowing means. By using both drying with a heating roll and hot air drying together, a steep temperature change between the heating rolls can be suppressed, and shrinkage in the width direction can be easily controlled. The temperature of hot air drying is preferably 30 ° C to 100 ° C. The hot air drying time is preferably 1 second to 300 seconds. The wind speed of the hot air is preferably about 10 m / s to 30 m / s. The wind speed is the wind speed in the heating furnace and can be measured by a mini-vane type digital anemometer.
A-3-6.その他の処理
 好ましくは、水中延伸処理の後、乾燥収縮処理の前に、洗浄処理を施す。上記洗浄処理は、代表的には、ヨウ化カリウム水溶液にPVA系樹脂層を浸漬させることにより行う。
A-3-6. Other Treatments Preferably, a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment. The cleaning treatment is typically performed by immersing a PVA-based resin layer in an aqueous potassium iodide solution.
A-4.保護層
 保護層の厚みは10μm以下である。保護層の厚みが10μm以下であることにより、偏光板の薄型化に寄与し得る。また、従来、偏光子の加熱時の収縮に追随して偏光子を保護する観点から、20μm以上の厚みを有する保護層が用いられている。これに対し、本発明の実施形態で用いられる偏光子は、上記の通り、従来よりもPVA系樹脂の配向度が低く、結果として、加熱による収縮が小さいことから、厚みが10μm以下の保護層を用いた場合であっても、加熱時のクラックの発生が抑制される。さらに、このような偏光子は、異形加工部におけるクラック抑制にも貢献し得る。
A-4. Protective layer The thickness of the protective layer is 10 μm or less. When the thickness of the protective layer is 10 μm or less, it can contribute to the thinning of the polarizing plate. Further, conventionally, from the viewpoint of protecting the polarizing element by following the shrinkage of the polarizing element during heating, a protective layer having a thickness of 20 μm or more has been used. On the other hand, as described above, the polarizing element used in the embodiment of the present invention has a lower degree of orientation of the PVA-based resin than the conventional one, and as a result, shrinkage due to heating is small, so that the protective layer has a thickness of 10 μm or less. Even when the above is used, the generation of cracks during heating is suppressed. Further, such a polarizing element can also contribute to crack suppression in the deformed portion.
 保護層の厚みは、好ましくは7μm以下であり、より好ましくは5μm以下であり、さらに好ましくは3μm以下である。保護層の厚みは、例えば1μm以上である。 The thickness of the protective layer is preferably 7 μm or less, more preferably 5 μm or less, and further preferably 3 μm or less. The thickness of the protective layer is, for example, 1 μm or more.
 保護層は樹脂膜で構成される。樹脂膜を形成する樹脂としては、目的に応じて任意の適切な樹脂が用いられ得る。具体例としては、(メタ)アクリル系、トリアセチルセルロース(TAC)等のセルロース系、ポリエステル系、ポリウレタン系、ポリビニルアルコール系、ポリカーボネート系、ポリアミド系、ポリイミド系、ポリエーテルスルホン系、ポリスルホン系、ポリスチレン系、ポリノルボルネン系、ポリオレフィン系、アセテート系等の熱可塑性樹脂;(メタ)アクリル系、ウレタン系、(メタ)アクリルウレタン系、エポキシ系、シリコーン系等の熱硬化型樹脂または活性エネルギー線硬化型樹脂;シロキサン系ポリマー等のガラス質系ポリマーが挙げられる。1つの実施形態において、樹脂膜を形成する樹脂としては、エポキシ樹脂、(メタ)アクリル系樹脂が挙げられる。これらは、単独で用いてもよく組み合わせて用いてもよい。 The protective layer is composed of a resin film. As the resin forming the resin film, any suitable resin can be used depending on the purpose. Specific examples include (meth) acrylic, cellulose-based such as triacetylcellulose (TAC), polyester-based, polyurethane-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, and polystyrene. Thermoplastic resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, silicone, etc., or active energy ray-curable resins. Resin: Glassy polymers such as siloxane-based polymers can be mentioned. In one embodiment, examples of the resin forming the resin film include an epoxy resin and a (meth) acrylic resin. These may be used alone or in combination.
 保護層を構成する樹脂膜は、例えば、溶融樹脂の成形物であってもよく、樹脂を水性溶媒または有機溶媒に溶解または分散して得られる樹脂溶液の塗布膜の固化物であってもよく、硬化型樹脂の硬化物(例えば、光カチオン硬化物)であってもよい。 The resin film constituting the protective layer may be, for example, a molded product of a molten resin, or may be a solidified coating film of a resin solution obtained by dissolving or dispersing the resin in an aqueous solvent or an organic solvent. , A cured product of a curable resin (for example, a photocationic cured product) may be used.
 1つの実施形態において、保護層は、熱可塑性(メタ)アクリル系樹脂(以下、(メタ)アクリル系樹脂を単に「アクリル系樹脂」と称する場合がある)の有機溶媒溶液の塗布膜の固化物、エポキシ樹脂の光カチオン硬化物、あるいはエポキシ樹脂の有機溶媒溶液の塗布膜の固化物であり得る。以下、具体的に説明する。 In one embodiment, the protective layer is a solidified coating film of an organic solvent solution of a thermoplastic (meth) acrylic resin (hereinafter, the (meth) acrylic resin may be simply referred to as “acrylic resin”). , A photocationically cured product of an epoxy resin, or a solidified product of a coating film of an organic solvent solution of an epoxy resin. Hereinafter, a specific description will be given.
A-4-1.熱可塑性アクリル系樹脂の有機溶媒溶液の塗布膜の固化物
 1つの実施形態においては、保護層は熱可塑性アクリル系樹脂の有機溶媒溶液の塗布膜の固化物で構成されている。本実施形態の保護層の軟化温度は、加湿耐久性の観点から、好ましくは100℃以上、より好ましくは115℃以上、さらに好ましくは120℃以上、特に好ましくは125℃以上であり、また、成形性の観点から、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。
A-4-1. Solidification of the coating film of the organic solvent solution of the thermoplastic acrylic resin In one embodiment, the protective layer is composed of the solidification of the coating film of the organic solvent solution of the thermoplastic acrylic resin. From the viewpoint of humidification durability, the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
 アクリル系樹脂は、ガラス転移温度(Tg)が好ましくは100℃以上である。その結果、保護層の軟化温度も、ほぼ100℃以上となる。アクリル系樹脂のTgが100℃以上であれば、このような樹脂から得られた保護層を含む偏光板は、クラック耐性に加えて加湿耐久性にも優れたものとなり得る。アクリル系樹脂のTgは、より好ましくは110℃以上、さらに好ましくは115℃以上、さらにより好ましくは120℃以上、特に好ましくは125℃以上である。一方、アクリル系樹脂のTgは、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。アクリル系樹脂のTgがこのような範囲であれば、成形性に優れ得る。 The acrylic resin has a glass transition temperature (Tg) of preferably 100 ° C. or higher. As a result, the softening temperature of the protective layer is also approximately 100 ° C. or higher. When the Tg of the acrylic resin is 100 ° C. or higher, the polarizing plate containing the protective layer obtained from such a resin can be excellent in humidification durability in addition to crack resistance. The Tg of the acrylic resin is more preferably 110 ° C. or higher, further preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher. On the other hand, the Tg of the acrylic resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower. If the Tg of the acrylic resin is in such a range, the moldability can be excellent.
 アクリル系樹脂としては、上記のようなTgを有する限りにおいて任意の適切なアクリル系樹脂が採用され得る。アクリル系樹脂は、代表的には、モノマー単位(繰り返し単位)として、アルキル(メタ)アクリレートを主成分として含有する。本明細書において「(メタ)アクリル」とは、アクリルおよび/またはメタクリルを意味する。アクリル系樹脂の主骨格を構成するアルキル(メタ)アクリレートとしては、直鎖状または分岐鎖状のアルキル基の炭素数1~18のものを例示できる。これらは単独であるいは組み合わせて使用することができる。さらに、アクリル系樹脂には、任意の適切な共重合モノマーを共重合により導入してもよい。アルキル(メタ)アクリレートの種類、数、組み合わせおよび配合比、共重合モノマーの種類、数、組み合わせおよび配合比、ならびに、重合条件等を適切に設定することにより、所望の保護層を形成し得るアクリル系樹脂が得られ得る。 As the acrylic resin, any suitable acrylic resin can be adopted as long as it has Tg as described above. Acrylic resins typically contain an alkyl (meth) acrylate as a main component as a monomer unit (repeating unit). As used herein, the term "(meth) acrylic" means acrylic and / or methacrylic. Examples of the alkyl (meth) acrylate constituting the main skeleton of the acrylic resin include linear or branched alkyl groups having 1 to 18 carbon atoms. These can be used alone or in combination. Further, any suitable copolymerization monomer may be introduced into the acrylic resin by copolymerization. Acrylic that can form a desired protective layer by appropriately setting the type, number, combination and compounding ratio of the alkyl (meth) acrylate, the type, number, combination and compounding ratio of the copolymerization monomer, and the polymerization conditions. A based resin can be obtained.
 アクリル系樹脂は、好ましくは、環構造を含む繰り返し単位を有する。環構造を含む繰り返し単位としては、ラクトン環単位、無水グルタル酸単位、グルタルイミド単位、無水マレイン酸単位、マレイミド(N-置換マレイミド)単位が挙げられる。環構造を含む繰り返し単位は、1種類のみがアクリル系樹脂の繰り返し単位に含まれていてもよく、2種類以上が含まれていてもよい。ラクトン環単位を有するアクリル系樹脂は、例えば特開2008-181078号公報に記載されている。グルタルイミド単位を有するアクリル系樹脂は、例えば、特開2006-309033号公報、特開2006-317560号公報、特開2006-328334号公報、特開2006-337491号公報、特開2006-337492号公報、特開2006-337493号公報、特開2006-337569号公報に記載されている。これらの公報の記載は本明細書に参考として援用される。 The acrylic resin preferably has a repeating unit containing a ring structure. Examples of the repeating unit including a ring structure include a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. Only one type of the repeating unit including the ring structure may be contained in the repeating unit of the acrylic resin, or two or more types may be contained. Acrylic resins having a lactone ring unit are described in, for example, Japanese Patent Application Laid-Open No. 2008-181078. Acrylic resins having a glutarimide unit are, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492. It is described in JP-A-2006-337493 and JP-A-2006-337569. The description of these publications is incorporated herein by reference.
 アクリル系樹脂における環構造を含む繰り返し単位の含有割合は、好ましくは1モル%~50モル%、より好ましくは10モル%~40モル%、さらに好ましくは20モル%~30モル%である。含有割合が少なすぎると、Tgが100℃未満となる場合があり、得られる保護層の耐熱性、耐溶剤性および表面硬度が不十分となる場合がある。含有割合が多すぎると、成形性および透明性が不十分となる場合がある。 The content ratio of the repeating unit including the ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and further preferably 20 mol% to 30 mol%. If the content ratio is too small, Tg may be less than 100 ° C., and the heat resistance, solvent resistance and surface hardness of the obtained protective layer may be insufficient. If the content is too high, moldability and transparency may be insufficient.
 本発明の実施形態においては、アクリル系樹脂と他の樹脂とを併用してもよい。すなわち、アクリル系樹脂を構成するモノマー成分と他の樹脂を構成するモノマー成分とを共重合し、当該共重合体を後述する保護層の成形に供してもよく;アクリル系樹脂と他の樹脂とのブレンドを保護層の成形に供してもよい。 In the embodiment of the present invention, an acrylic resin and another resin may be used in combination. That is, the monomer component constituting the acrylic resin and the monomer component constituting the other resin may be copolymerized, and the copolymer may be used for molding the protective layer described later; the acrylic resin and the other resin. The blend of may be used for forming the protective layer.
 本実施形態の保護層は、例えば、偏光子表面に、アクリル系樹脂の有機溶媒溶液を塗布して塗布膜を形成し、当該塗布膜を固化させることによって形成され得る。 The protective layer of the present embodiment can be formed, for example, by applying an organic solvent solution of an acrylic resin to the surface of a polarizing element to form a coating film, and solidifying the coating film.
 有機溶媒としては、アクリル系樹脂を溶解または均一に分散し得る任意の適切な有機溶媒を用いることができる。有機溶媒の具体例としては、酢酸エチル、トルエン、メチルエチルケトン(MEK)、メチルイソブチルケトン(MIBK)、シクロペンタノン、シクロヘキサノンが挙げられる。 As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the acrylic resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.
 溶液のアクリル系樹脂濃度は、溶媒100重量部に対して、好ましくは3重量部~20重量部である。このような樹脂濃度であれば、偏光子に密着した均一な塗布膜を形成することができる。 The acrylic resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
 溶液は、任意の適切な基材に塗布してもよく、偏光子に塗布してもよい。基材に塗布する場合には、基材上に形成された塗布膜の固化物が偏光子に転写される。偏光子に塗布する場合には、塗布膜を乾燥(固化)させることにより、偏光子上に保護層が直接形成される。好ましくは、溶液は偏光子に塗布され、偏光子上に保護層が直接形成される。このような構成であれば、転写に必要とされる接着剤層または粘着剤層を省略することができるので、偏光板をさらに薄くすることができる。溶液の塗布方法としては、任意の適切な方法を採用することができる。具体例としては、ロールコート法、スピンコート法、ワイヤーバーコート法、ディップコート法、ダイコート法、カーテンコート法、スプレーコート法、ナイフコート法(コンマコート法等)が挙げられる。 The solution may be applied to any suitable substrate or to a polarizing element. When applied to a substrate, the solidified material of the coating film formed on the substrate is transferred to the polarizing element. When applied to a polarizing element, a protective layer is directly formed on the polarizing element by drying (solidifying) the coating film. Preferably, the solution is applied to the polarizing element and a protective layer is formed directly on the polarizing element. With such a configuration, the adhesive layer or the pressure-sensitive adhesive layer required for transfer can be omitted, so that the polarizing plate can be further thinned. Any suitable method can be adopted as the method for applying the solution. Specific examples include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (comma coating method, etc.).
 溶液の塗布膜を乾燥(固化)させることにより、保護層が形成され得る。乾燥温度は、好ましくは100℃以下であり、より好ましくは50℃~70℃である。乾燥温度がこのような範囲であれば、偏光子に対する悪影響を防止することができる。乾燥時間は、乾燥温度に応じて変化し得る。乾燥時間は、例えば1分~10分であり得る。 A protective layer can be formed by drying (solidifying) the coating film of the solution. The drying temperature is preferably 100 ° C. or lower, more preferably 50 ° C. to 70 ° C. When the drying temperature is in such a range, it is possible to prevent an adverse effect on the polarizing element. The drying time can vary depending on the drying temperature. The drying time can be, for example, 1 to 10 minutes.
A-4-2.エポキシ樹脂の光カチオン硬化物
 1つの実施形態においては、保護層は、エポキシ樹脂の光カチオン硬化物で構成される。このような保護層を用いることにより、クラックの発生が抑制され、かつ、優れた加湿耐久性が得られ得る。上記のとおり、保護層が光カチオン硬化物であるため、保護層形成用組成物は光カチオン重合開始剤を含む。光カチオン重合開始剤は、光酸発生剤の機能を持つ感光剤であり、代表的にはカチオン部とアニオン部とからなるイオン性のオニウム塩が挙げられる。このオニウム塩において、カチオン部は光を吸収し、アニオン部は酸の発生源となる。この光カチオン重合開始剤から発生した酸によりエポキシ基の開環重合が進行する。得られる光カチオン硬化物である保護層は軟化温度が高く、ヨウ素吸着量が低減され得る。そのため、クラックの発生が抑制され、かつ、優れた加湿耐久性を有する偏光板を提供することができる。
A-4-2. Photocationic cured product of epoxy resin In one embodiment, the protective layer is composed of a photocationic cured product of epoxy resin. By using such a protective layer, the generation of cracks can be suppressed and excellent humidification durability can be obtained. As described above, since the protective layer is a photocationic cured product, the composition for forming the protective layer contains a photocationic polymerization initiator. The photocationic polymerization initiator is a photosensitizer having a function of a photoacid generator, and a typical example thereof is an ionic onium salt composed of a cation portion and an anion portion. In this onium salt, the cation part absorbs light and the anion part becomes a source of acid. Ring-opening polymerization of the epoxy group proceeds by the acid generated from this photocationic polymerization initiator. The protective layer, which is the obtained photocationic cured product, has a high softening temperature, and the amount of iodine adsorbed can be reduced. Therefore, it is possible to provide a polarizing plate in which the occurrence of cracks is suppressed and has excellent humidification durability.
 本実施形態の保護層の軟化温度は、加湿耐久性の観点から、好ましくは100℃以上、より好ましくは110℃以上、さらに好ましくは120℃以上、特に好ましくは125℃以上であり、また、成形性の観点から、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。 From the viewpoint of humidification durability, the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
A-4-2-1.エポキシ樹脂
 エポキシ樹脂としては、任意の適切なエポキシ樹脂を用いることができ、芳香環または脂環を有するエポキシ樹脂が好ましく用いられ得る。本実施形態においては、好ましくは芳香族骨格および水素添加された芳香族骨格からなる群より選択される少なくとも1種を有するエポキシ樹脂を用いることができる。芳香族骨格としては、例えば、ベンゼン環、ナフタレン環、フルオレン環等が挙げられる。エポキシ樹脂は1種のみを用いてもよく、2種以上を組み合わせて用いてもよい。好ましくは芳香族骨格としてビフェニル骨格もしくはビスフェノール骨格を有するエポキシ樹脂またはその水添物が用いられる。このようなエポキシ樹脂を用いることにより、より優れた耐久性を有し、屈曲性にも優れた偏光板が提供され得る。
A-4-2-1. Epoxy resin As the epoxy resin, any suitable epoxy resin can be used, and an epoxy resin having an aromatic ring or an alicyclic ring can be preferably used. In the present embodiment, an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton can be preferably used. Examples of the aromatic skeleton include a benzene ring, a naphthalene ring, a fluorene ring and the like. Only one type of epoxy resin may be used, or two or more types may be used in combination. Preferably, an epoxy resin having a biphenyl skeleton or a bisphenol skeleton or a hydrogenated product thereof is used as the aromatic skeleton. By using such an epoxy resin, a polarizing plate having more excellent durability and excellent flexibility can be provided.
 1つの実施形態において、ビフェニル骨格を有するエポキシ樹脂は、以下の構造を含むエポキシ樹脂である。ビフェニル骨格を有するエポキシ樹脂は1種のみを用いてもよく、2種以上を組み合わせて用いてもよい。
Figure JPOXMLDOC01-appb-C000001
(式中、R14~R21は、それぞれ独立して、水素原子、炭素数1~12の直鎖状もしくは分岐状の置換または非置換の炭化水素基、または、ハロゲン元素を表す)。
In one embodiment, the epoxy resin having a biphenyl skeleton is an epoxy resin containing the following structure. Only one type of epoxy resin having a biphenyl skeleton may be used, or two or more types may be used in combination.
Figure JPOXMLDOC01-appb-C000001
(In the formula, R 14 to R 21 each independently represent a hydrogen atom, a linear or branched substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, or a halogen element).
 1つの実施形態においては、ビフェニル骨格を有するエポキシ樹脂は下記式で表されるエポキシ樹脂である。
Figure JPOXMLDOC01-appb-C000002
(式中、R14~R21は上記の通りであり、nは0~6の整数を表す)。
In one embodiment, the epoxy resin having a biphenyl skeleton is an epoxy resin represented by the following formula.
Figure JPOXMLDOC01-appb-C000002
(In the equation, R 14 to R 21 are as described above, and n represents an integer of 0 to 6).
 1つの実施形態において、ビフェニル骨格を有するエポキシ樹脂はビフェニル骨格のみを有するエポキシ樹脂である。ビフェニル骨格のみを有するエポキシ樹脂を用いることにより、得られる保護層の耐久性がさらに向上し得る。別の実施形態においては、ビフェニル骨格を有するエポキシ樹脂はビフェニル骨格以外の化学構造を含んでいてもよい。ビフェニル骨格以外の化学構造としては、例えば、ビスフェノール骨格、脂環式構造、芳香族環構造等が挙げられる。この場合、ビフェニル骨格以外の化学構造の割合(モル比)はビフェニル骨格よりも少ないことが好ましい。 In one embodiment, the epoxy resin having a biphenyl skeleton is an epoxy resin having only a biphenyl skeleton. By using an epoxy resin having only a biphenyl skeleton, the durability of the obtained protective layer can be further improved. In another embodiment, the epoxy resin having a biphenyl skeleton may contain a chemical structure other than the biphenyl skeleton. Examples of the chemical structure other than the biphenyl skeleton include a bisphenol skeleton, an alicyclic structure, an aromatic ring structure and the like. In this case, the ratio (molar ratio) of the chemical structure other than the biphenyl skeleton is preferably smaller than that of the biphenyl skeleton.
 上記エポキシ樹脂(光カチオン硬化後のエポキシ樹脂)は、好ましくはガラス転移温度(Tg)が100℃以上である。その結果、保護層の軟化温度も、ほぼ100℃以上となる。エポキシ樹脂のTgが100℃以上であれば、得られる保護層を含む偏光板は、耐久性に優れたものとなりやすい。エポキシ樹脂のTgは、より好ましくは110℃以上、さらに好ましくは120℃以上、特に好ましくは125℃以上である。一方、エポキシ樹脂のTgは、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。エポキシ樹脂のTgがこのような範囲であれば、成形性に優れ得る。 The epoxy resin (epoxy resin after photocation curing) preferably has a glass transition temperature (Tg) of 100 ° C. or higher. As a result, the softening temperature of the protective layer is also approximately 100 ° C. or higher. When the Tg of the epoxy resin is 100 ° C. or higher, the obtained polarizing plate including the protective layer tends to have excellent durability. The Tg of the epoxy resin is more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher. On the other hand, the Tg of the epoxy resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower. When the Tg of the epoxy resin is in such a range, the moldability can be excellent.
 上記エポキシ樹脂のエポキシ当量は、好ましくは100g/当量以上であり、より好ましくは150g/当量以上、さらに好ましくは200g/当量以上である。また、エポキシ樹脂のエポキシ当量は、好ましくは3000g/当量以下であり、より好ましくは2500g/当量以下、さらに好ましくは2000g/当量以下である。エポキシ当量が上記範囲であることにより、より安定した保護層(残存モノマーが少なく、十分に硬化した保護層)が得られる。なお、本明細書において「エポキシ当量」とは、「1当量のエポキシ基を含むエポキシ樹脂の質量」をいい、JIS K 7236に準じて測定することができる。 The epoxy equivalent of the epoxy resin is preferably 100 g / equivalent or more, more preferably 150 g / equivalent or more, and further preferably 200 g / equivalent or more. The epoxy equivalent of the epoxy resin is preferably 3000 g / equivalent or less, more preferably 2500 g / equivalent or less, still more preferably 2000 g / equivalent or less. When the epoxy equivalent is in the above range, a more stable protective layer (a protective layer having less residual monomer and sufficiently cured) can be obtained. In the present specification, "epoxy equivalent" means "mass of epoxy resin containing 1 equivalent of epoxy group" and can be measured according to JIS K7236.
 本実施形態においては、上記エポキシ樹脂と他の樹脂とを併用してもよい。すなわち、上記エポキシ樹脂(例えば、芳香族骨格および水素添加された芳香族骨格からなる群より選択される少なくとも1種を有するエポキシ樹脂)と他の樹脂とのブレンドを保護層の成形に供してもよい。他の樹脂としては、例えば、アクリル系樹脂、オキセタン系樹脂が挙げられる。 In this embodiment, the above epoxy resin may be used in combination with another resin. That is, even if a blend of the above epoxy resin (for example, an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton) and another resin is used for molding the protective layer. good. Examples of other resins include acrylic resins and oxetane resins.
 アクリル系樹脂としては、任意の適切な(メタ)アクリル系化合物を用いることができる。例えば、(メタ)アクリル系化合物としては、例えば、分子内に一個の(メタ)アクリロイル基を有する(メタ)アクリル系化合物(以下、「単官能(メタ)アクリル系化合物」ともいう)、分子内に二個以上の(メタ)アクリロイル基を有する(メタ)アクリル系化合物(以下、「多官能(メタ)アクリル系化合物」ともいう)が挙げられる。これらの(メタ)アクリル系化合物は、単独で用いてもよく、2種類以上組み合わせて用いてもよい。これらのアクリル系樹脂については、例えば特開2019-168500号公報に記載されている。当該公報は、その全体の記載が本明細書に参考として援用される。 As the acrylic resin, any suitable (meth) acrylic compound can be used. For example, as the (meth) acrylic compound, for example, a (meth) acrylic compound having one (meth) acryloyl group in the molecule (hereinafter, also referred to as “monofunctional (meth) acrylic compound”), intramolecular. Examples thereof include (meth) acrylic compounds having two or more (meth) acryloyl groups (hereinafter, also referred to as “polyfunctional (meth) acrylic compounds”). These (meth) acrylic compounds may be used alone or in combination of two or more. These acrylic resins are described in, for example, Japanese Patent Application Laid-Open No. 2019-168500. The entire description of the publication is incorporated herein by reference.
 オキセタン樹脂としては、分子内にオキセタニル基を1個以上有する任意の適切な化合物が用いられる。例えば、3-エチル-3-ヒドロキシメチルオキセタン、3-エチル-3-(2-エチルヘキシルオキシメチル)オキセタン、3-エチル-3-(フェノキシメチル)オキセタン、3-エチル-3-(シクロヘキシルオキシメチル)オキセタン、3-エチル-3-(オキシラニルメトキシ)オキセタン、(メタ)アクリル酸(3-エチルオキセタン-3-イル)メチル等の分子内にオキセタニル基を1個有するオキセタン化合物;3-エチル-3{[(3-エチルオキセタン-3-イル)メトキシ]メチル}オキセタン、1,4-ビス[(3-エチル-3-オキセタニル)メトキシメチル]ベンゼン、4,4’-ビス[(3-エチル-3-オキセタニル)メトキシメチル]ビフェニル等の分子内にオキセタニル基を2個以上有するオキセタン化合物;等が挙げられる。これらオキセタン樹脂は1種のみを用いてもよく、2種以上を組み合わせてもよい。オキセタン樹脂としては、好ましくは3-エチル-3-ヒドロキシメチルオキセタン、1,4-ビス[(3-エチル-3-オキセタニル)メトキシメチル]ベンゼン、3-エチル-3-(2-エチルヘキシルオキシメチル)オキセタン、3-エチル-3-(オキシラニルメトキシ)オキセタン、(メタ)アクリル酸(3-エチルオキセタン-3-イル)メチル、3-エチル-3{[(3-エチルオキセタン-3-イル)メトキシ]メチル}オキセタン等が用いられる。これらのオキセタン樹脂は、容易に入手可能であり、希釈性(低粘度)、相溶性に優れ得る。 As the oxetane resin, any suitable compound having one or more oxetanyl groups in the molecule is used. For example, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (cyclohexyloxymethyl). Oxetane compound having one oxetane group in the molecule such as oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl; 3-ethyl- 3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 4,4'-bis [(3-ethyl) -3-Oxetane) methoxymethyl] An oxetane compound having two or more oxetane groups in a molecule such as biphenyl; and the like. Only one kind of these oxetane resins may be used, or two or more kinds thereof may be combined. The oxetane resin is preferably 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (2-ethylhexyloxymethyl). Oxetane, 3-Ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl, 3-ethyl-3 {[(3-ethyloxetane-3-yl) Methyl] methyl} oxetane and the like are used. These oxetane resins are easily available and can be excellent in dilutability (low viscosity) and compatibility.
 1つの実施形態においては、相溶性や接着性の点から、好ましくは分子量500以下であり、室温(25℃)で液状のオキセタン樹脂が用いられる。1つの実施形態においては、好ましくは分子内に2個以上のオキセタニル基を含有するオキセタン化合物、分子内に1個のオキセタニル基と1個の(メタ)アクリロイル基または1個のエポキシ基を含有するオキセタン化合物が用いられ、より好ましくは3-エチル-3{[(3-エチルオキセタン-3-イル)メトキシ]メチル}オキセタン、3-エチル-3-(オキシラニルメトキシ)オキセタン、(メタ)アクリル酸(3-エチルオキセタン-3-イル)メチルが用いられる。これらのオキセタン樹脂を用いることにより、保護層の硬化性および耐久性が向上し得る。 In one embodiment, an oxetane resin having a molecular weight of 500 or less and liquid at room temperature (25 ° C.) is preferably used from the viewpoint of compatibility and adhesiveness. In one embodiment, it preferably contains an oxetane compound containing two or more oxetanel groups in the molecule, one oxetaneyl group and one (meth) acryloyl group or one epoxy group in the molecule. Oxetane compounds are used, more preferably 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 3-ethyl-3- (oxylanylmethoxy) oxetane, (meth) acrylic. Acid (3-ethyloxetane-3-yl) methyl is used. By using these oxetane resins, the curability and durability of the protective layer can be improved.
A-4-2-2.光カチオン重合開始剤
 光カチオン重合開始剤は、光酸発生剤の機能を持つ感光剤であり、代表的にはカチオン部とアニオン部とからなるイオン性のオニウム塩が挙げられる。このオニウム塩において、カチオン部は光を吸収し、アニオン部は酸の発生源となる。この光カチオン重合開始剤から発生した酸によりエポキシ基の開環重合が進行する。光カチオン重合開始剤としては、紫外線等の光照射により芳香族骨格および水素添加された芳香族骨格からなる群より選択される少なくとも1種を有するエポキシ樹脂を硬化させることができる任意の適切な化合物を用いることができる。光カチオン重合開始剤は1種のみを用いてもよく、2種以上を組み合わせて用いてもよい。
A-4-2-2. Photocationic polymerization initiator The photocationic polymerization initiator is a photosensitive agent having a function of a photoacid generator, and a typical example thereof is an ionic onium salt composed of a cation portion and an anion portion. In this onium salt, the cation part absorbs light and the anion part becomes a source of acid. Ring-opening polymerization of the epoxy group proceeds by the acid generated from this photocationic polymerization initiator. As the photocationic polymerization initiator, any suitable compound capable of curing an epoxy resin having at least one selected from the group consisting of an aromatic skeleton and a hydrogenated aromatic skeleton by irradiation with light such as ultraviolet rays. Can be used. Only one type of photocationic polymerization initiator may be used, or two or more types may be used in combination.
 光カチオン重合開始剤としては、例えば、トリフェニルスルホニウムヘキサフルオロアンチモネート、トリフェニルスルホニウムヘキサフルオロホスフェート、p-(フェニルチオ)フェニルジフェニルスルホニウムヘキサフルオロアンチモネート、p-(フェニルチオ)フェニルジフェニルスルホニウムヘキサフルオロホスフェート、4-クロルフェニルジフェニルスルホニウムヘキサフルオロホスフェート、4-クロルフェニルジフェニルスルホニウムヘキサフルオロアンチモネート、ビス[4-(ジフェニルスルフォニオ)フェニル]スルフィドビスヘキサフルオロホスフェート、ビス[4-(ジフェニルスルフォニオ)フェニル]スルフィドビスヘキサフルオロアンチモネート、(2,4-シクロペンタジエン-1-イル)[(1-メチルエチル)ベンゼン]-Fe-ヘキサフルオロホスフェート、ジフェニルヨードニウムヘキサフルオロアンチモネート等が挙げられる。好ましくは、トリフェニルスルホニウム塩系ヘキサフルオロアンチモネートタイプの光カチオン重合開始剤、ジフェニルヨードニウム塩系ヘキサフルオロアンチモネートタイプの光カチオン重合開始剤が用いられる。 Examples of the photocationic polymerization initiator include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, p- (phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, p- (phenylthio) phenyldiphenylsulfonium hexafluorophosphate, and the like. 4-Chlorphenyl diphenyl sulfonium hexafluorophosphate, 4-chlorphenyl diphenyl sulfonium hexafluoroantimonate, bis [4- (diphenyl sulfonio) phenyl] sulfide bishexafluoro phosphate, bis [4- (diphenyl sulfonio) phenyl ] Sulfoxybishexafluoroantimonate, (2,4-cyclopentadiene-1-yl) [(1-methylethyl) benzene] -Fe-hexafluorophosphate, diphenyliodonium hexafluoroantimonate and the like. Preferably, a triphenylsulfonium salt-based hexafluoroantimonate type photocationic polymerization initiator and a diphenyliodonium salt-based hexafluoroantimonate type photocationic polymerization initiator are used.
 本実施形態の保護層は、例えば、上記エポキシ樹脂と光カチオン重合開始剤とを含む組成物を塗布して塗膜を形成し、該塗膜に光(例えば、紫外線)を照射することにより形成され得る。 The protective layer of the present embodiment is formed by, for example, applying a composition containing the epoxy resin and a photocationic polymerization initiator to form a coating film, and irradiating the coating film with light (for example, ultraviolet rays). Can be done.
 上記組成物におけるエポキシ樹脂濃度は、溶媒100重量部に対して、好ましくは10重量部~30重量部である。このような樹脂濃度であれば、偏光子に密着した均一な塗布膜を形成することができる。 The epoxy resin concentration in the above composition is preferably 10 parts by weight to 30 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
 上記組成物は、任意の適切な基材に塗布してもよく、偏光子に塗布してもよい。基材に塗布する場合には、基材上に形成された塗布膜の硬化物が偏光子に転写される。偏光子に塗布する場合には、塗布膜を例えば光照射により硬化させることにより、偏光子上に保護層が直接形成される。好ましくは、上記組成物は偏光子に塗布され、偏光子上に保護層が直接形成される。このような構成であれば、転写に必要とされる接着剤層または粘着剤層を省略することができるので、偏光板をさらに薄くすることができる。組成物の塗布方法としては、上述の通りである。 The above composition may be applied to any suitable substrate or may be applied to a polarizing element. When applied to a substrate, the cured product of the coating film formed on the substrate is transferred to the polarizing element. When the coating film is applied to the polarizing element, the protective layer is directly formed on the polarizing element by, for example, curing the coating film by irradiation with light. Preferably, the composition is applied to a polarizing element and a protective layer is formed directly on the polarizing element. With such a configuration, the adhesive layer or the pressure-sensitive adhesive layer required for transfer can be omitted, so that the polarizing plate can be further thinned. The method for applying the composition is as described above.
 塗布膜の硬化は、任意の適切な光源を用いて任意の適切な照射量となるように光(代表的には紫外線)を照射することにより行われ得る。光照射後、光反応による硬化を完結させるために加熱処理をさらに施してもよい。加熱処理は任意の適切な温度および時間で行われ得る。 Curing of the coating film can be performed by irradiating light (typically ultraviolet rays) with an arbitrary appropriate light source so as to obtain an arbitrary appropriate irradiation amount. After the light irradiation, further heat treatment may be performed to complete the curing by the light reaction. The heat treatment can be performed at any suitable temperature and time.
A-4-3.エポキシ樹脂の有機溶媒溶液の塗布膜の固化物
 1つの実施形態においては、保護層はエポキシ樹脂の有機溶媒溶液の塗布膜の固化物で構成される。本実施形態の保護層の軟化温度は、加湿耐久性の観点から、好ましくは100℃以上、より好ましくは110℃以上、さらに好ましくは120℃以上、特に好ましくは125℃以上であり、また、成形性の観点から、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。
A-4-3. Solidification of the coating film of the organic solvent solution of the epoxy resin In one embodiment, the protective layer is composed of the solidification of the coating film of the organic solvent solution of the epoxy resin. From the viewpoint of humidification durability, the softening temperature of the protective layer of the present embodiment is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and molding. From the viewpoint of properties, it is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower.
A-4-3-1.エポキシ樹脂
 本実施形態において、エポキシ樹脂は、好ましくはガラス転移温度(Tg)が100℃以上である。その結果、保護層の軟化温度も、ほぼ100℃以上となる。エポキシ樹脂のTgが100℃以上であれば、このような樹脂から得られた保護層を含む偏光板は、耐久性に優れたものとなりやすい。エポキシ樹脂のTgは、より好ましくは110℃以上、さらに好ましくは120℃以上、特に好ましくは125℃以上である。一方、エポキシ樹脂のTgは、好ましくは300℃以下、より好ましくは250℃以下、さらに好ましくは200℃以下、特に好ましくは160℃以下である。エポキシ樹脂のTgがこのような範囲であれば、成形性に優れ得る。
A-4-3-1. Epoxy resin In the present embodiment, the epoxy resin preferably has a glass transition temperature (Tg) of 100 ° C. or higher. As a result, the softening temperature of the protective layer is also approximately 100 ° C. or higher. When the Tg of the epoxy resin is 100 ° C. or higher, the polarizing plate containing the protective layer obtained from such a resin tends to have excellent durability. The Tg of the epoxy resin is more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher. On the other hand, the Tg of the epoxy resin is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 160 ° C. or lower. When the Tg of the epoxy resin is in such a range, the moldability can be excellent.
 エポキシ樹脂としては、上記のようなTgを有する限りにおいて任意の適切なエポキシ樹脂が採用され得る。エポキシ樹脂は、代表的には、分子構造内にエポキシ基を有する樹脂をいう。エポキシ樹脂としては、好ましくは分子構造内に芳香族環を有するエポキシ樹脂が用いられる。芳香族環を有するエポキシ樹脂を用いることにより、より高いTgを有するエポキシ樹脂が得られ得る。分子構造内に芳香族環を有するエポキシ樹脂における芳香族環としては、例えば、ベンゼン環、ナフタレン環、フルオレン環等が挙げられる。エポキシ樹脂は1種のみを用いてもよく、2種以上を組み合わせて用いてもよい。2種以上のエポキシ樹脂を用いる場合、芳香族環を含むエポキシ樹脂と、芳香族環を含まないエポキシ樹脂を組み合わせて用いてもよい。 As the epoxy resin, any suitable epoxy resin can be adopted as long as it has Tg as described above. The epoxy resin typically refers to a resin having an epoxy group in its molecular structure. As the epoxy resin, an epoxy resin having an aromatic ring in the molecular structure is preferably used. By using an epoxy resin having an aromatic ring, an epoxy resin having a higher Tg can be obtained. Examples of the aromatic ring in the epoxy resin having an aromatic ring in the molecular structure include a benzene ring, a naphthalene ring, a fluorene ring and the like. Only one type of epoxy resin may be used, or two or more types may be used in combination. When two or more kinds of epoxy resins are used, an epoxy resin containing an aromatic ring and an epoxy resin not containing an aromatic ring may be used in combination.
 分子構造内に芳香族環を有するエポキシ樹脂としては、具体的には、ビスフェノールAジグリシジルエーテル型エポキシ樹脂、ビスフェノールFジグリシジルエーテル型エポキシ樹脂、ビスフェノールSジグリシジルエーテル型エポキシ樹脂、レゾルシンジグリシジルエーテル型エポキシ樹脂、ヒドロキノンジグリシジルエーテル型エポキシ樹脂、テレフタル酸ジグリシジルエステル型エポキシ樹脂、ビスフェノキシエタノールフルオレンジグリシジルエーテル型エポキシ樹脂、ビスフェノールフルオレンジグリシジルエーテル型エポキシ樹脂、ビスクレゾールフルオレンジグリシジルエーテル型エポキシ樹脂等の2つのエポキシ基を有するエポキシ樹脂;ノボラック型エポキシ樹脂、N,N,O-トリグリシジル-P-又は-m-アミノフェノール型エポキシ樹脂、N,N,O-トリグリシジル-4-アミノ-m-又は-5-アミノ-o-クレゾール型エポキシ樹脂、1,1,1-(トリグリシジルオキシフェニル)メタン型エポキシ樹脂等の3つのエポキシ基を有するエポキシ樹脂;グリシジルアミン型エポキシ樹脂(例えば、ジアミノジフェニルメタン型、ジアミノジフェニルスルホン型、メタキシレンジアミン型)等の4つのエポキシ基を有するエポキシ樹脂等が挙げられる。また、ヘキサヒドロ無水フタル酸型エポキシ樹脂、テトラヒドロ無水フタル酸型エポキシ樹脂、ダイマー酸型エポキシ樹脂、p-オキシ安息香酸型等のグリシジルエステル型エポキシ樹脂を用いてもよい。 Specific examples of the epoxy resin having an aromatic ring in its molecular structure include bisphenol A diglycidyl ether type epoxy resin, bisphenol F diglycidyl ether type epoxy resin, bisphenol S diglycidyl ether type epoxy resin, and resorcin diglycidyl ether. Type epoxy resin, hydroquinone diglycidyl ether type epoxy resin, terephthalic acid diglycidyl ester type epoxy resin, bisphenoxyethanol full orange glycidyl ether type epoxy resin, bisphenol full orange glycidyl ether type epoxy resin, biscresol full orange glycidyl ether type epoxy resin, etc. Epoxy resin having two epoxy groups; novolak type epoxy resin, N, N, O-triglycidyl-P- or -m-aminophenol type epoxy resin, N, N, O-triglycidyl-4-amino-m -Or-5-Amino-o-cresol type epoxy resin, 1,1,1- (triglycidyloxyphenyl) methane type epoxy resin and other epoxy resins with three epoxy groups; glycidylamine type epoxy resin (eg, diamino) Examples thereof include epoxy resins having four epoxy groups such as diphenylmethane type, diaminodiphenylsulfone type, and metaxylene diamine type). Further, a glycidyl ester type epoxy resin such as a hexahydrophthalic anhydride type epoxy resin, a tetrahydrophthalic anhydride type epoxy resin, a dimer acid type epoxy resin, and a p-oxybenzoic acid type may be used.
 エポキシ樹脂のエポキシ当量は、好ましくは1000g/当量以上であり、より好ましくは3000g/当量以上、さらに好ましくは5000g/当量以上である。また、エポキシ樹脂のエポキシ当量は、好ましくは30000g/当量以下であり、より好ましくは25000g/当量以下、さらに好ましくは20000g/当量以下である。エポキシ当量が上記範囲であることにより、より安定した保護層が得られる。なお、本明細書において「エポキシ当量」とは、「1当量のエポキシ基を含むエポキシ樹脂の質量」をいい、JIS K 7236に準じて測定することができる。 The epoxy equivalent of the epoxy resin is preferably 1000 g / equivalent or more, more preferably 3000 g / equivalent or more, and further preferably 5000 g / equivalent or more. The epoxy equivalent of the epoxy resin is preferably 30,000 g / equivalent or less, more preferably 25,000 g / equivalent or less, and further preferably 20,000 g / equivalent or less. When the epoxy equivalent is in the above range, a more stable protective layer can be obtained. In the present specification, "epoxy equivalent" means "mass of epoxy resin containing 1 equivalent of epoxy group" and can be measured according to JIS K7236.
 本実施形態においては、エポキシ樹脂と他の樹脂とを併用してもよい。すなわち、エポキシ樹脂と他の樹脂とのブレンドを保護層の成形に供してもよい。他の樹脂は、目的に応じて適切に選択され得る。 In this embodiment, the epoxy resin and another resin may be used in combination. That is, a blend of the epoxy resin and another resin may be used for molding the protective layer. Other resins may be appropriately selected depending on the intended purpose.
 本実施形態の保護層は、例えば、上記エポキシ樹脂を含む有機溶媒溶液を塗布して塗膜を形成し、該塗膜を固化させることにより、形成され得る。有機溶媒溶液におけるエポキシ樹脂濃度は、溶媒100重量部に対して、好ましくは3重量部~20重量部である。このような樹脂濃度であれば、偏光子に密着した均一な塗布膜を形成することができる。 The protective layer of the present embodiment can be formed, for example, by applying an organic solvent solution containing the epoxy resin to form a coating film and solidifying the coating film. The epoxy resin concentration in the organic solvent solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the polarizing element can be formed.
 上記有機溶媒としては、エポキシ樹脂を溶解または均一に分散し得る任意の適切な溶媒を用いることができる。溶媒の具体例としては、酢酸エチル、トルエン、メチリエチルケトン(MEK)、メチルイソブチルケトン(MIBK)、シクロペンタノン、シクロヘキサノンが挙げられる。 As the organic solvent, any suitable solvent capable of dissolving or uniformly dispersing the epoxy resin can be used. Specific examples of the solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.
 溶液は、任意の適切な基材に塗布してもよく、偏光子に塗布してもよい。基材に塗布する場合には、基材上に形成された塗布膜の固化物が偏光子に転写される。偏光子に塗布する場合には、塗布膜を乾燥(固化)させることにより、偏光子上に保護層が直接形成される。好ましくは、溶液は偏光子に塗布され、偏光子上に保護層が直接形成される。このような構成であれば、転写に必要とされる接着剤層または粘着剤層を省略することができるので、偏光板をさらに薄くすることができる。溶液の塗布方法としては、上述の通りである。 The solution may be applied to any suitable substrate or to a polarizing element. When applied to a substrate, the solidified material of the coating film formed on the substrate is transferred to the polarizing element. When applied to a polarizing element, a protective layer is directly formed on the polarizing element by drying (solidifying) the coating film. Preferably, the solution is applied to the polarizing element and a protective layer is formed directly on the polarizing element. With such a configuration, the adhesive layer or the pressure-sensitive adhesive layer required for transfer can be omitted, so that the polarizing plate can be further thinned. The method of applying the solution is as described above.
 溶液の塗布膜を乾燥(固化)させることにより、塗布膜の固化物である保護層が形成され得る。乾燥温度は、好ましくは100℃以下であり、より好ましくは50℃~70℃である。乾燥温度がこのような範囲であれば、偏光子に対する悪影響を防止することができる。乾燥時間は、乾燥温度に応じて変化し得る。乾燥時間は、例えば1分~10分であり得る。 By drying (solidifying) the coating film of the solution, a protective layer that is a solidified coating film can be formed. The drying temperature is preferably 100 ° C. or lower, more preferably 50 ° C. to 70 ° C. When the drying temperature is in such a range, it is possible to prevent an adverse effect on the polarizing element. The drying time can vary depending on the drying temperature. The drying time can be, for example, 1 to 10 minutes.
B.位相差層付偏光板
B-1.位相差層付偏光板の全体構成
 図7は、本発明の1つの実施形態による位相差層付偏光板の概略断面図である。図示例の位相差層付偏光板200は、上記A項に記載の偏光板100と位相差層120とを含む。したがって、位相差層付偏光板200は、偏光板100と同様の異形を有する。位相差層付偏光板200においては、位相差層120が偏光子10の保護層としても機能し得る。位相差層120は、代表的には、接着層(図示せず)を介して、偏光板100(図示例では、偏光子10)に積層されている。接着層は、接着剤層または粘着剤層であり、リワーク性等の観点からは粘着剤層(例えば、アクリル系粘着剤層)であることが好ましい。図示しないが、必要に応じて、位相差層付偏光板は、偏光子10の位相差層120側に別の保護層(図示せず)を有していてもよい。また、必要に応じて、位相差層付偏光板は、位相差層120の偏光板100と反対側に、別の位相差層(図示せず)を有していてもよい。別の位相差層は、代表的には、屈折率特性がnz>nx=nyの関係を示すいわゆるポジティブCプレートである。
B. Polarizing plate with retardation layer B-1. Overall Configuration of Polarizing Plate with Difference Layer FIG. 7 is a schematic cross-sectional view of the polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate with a retardation layer 200 in the illustrated example includes the polarizing plate 100 according to the above item A and the retardation layer 120. Therefore, the polarizing plate 200 with a retardation layer has the same variant shape as the polarizing plate 100. In the polarizing plate 200 with a retardation layer, the retardation layer 120 can also function as a protective layer for the polarizing element 10. The retardation layer 120 is typically laminated on a polarizing plate 100 (polarizer 10 in the illustrated example) via an adhesive layer (not shown). The adhesive layer is an adhesive layer or an adhesive layer, and is preferably an adhesive layer (for example, an acrylic adhesive layer) from the viewpoint of reworkability and the like. Although not shown, the polarizing plate with a retardation layer may have another protective layer (not shown) on the retardation layer 120 side of the polarizing element 10, if necessary. Further, if necessary, the polarizing plate with a retardation layer may have another retardation layer (not shown) on the opposite side of the polarizing plate 100 of the retardation layer 120. Another retardation layer is typically a so-called positive C plate whose refractive index characteristic shows a relationship of nz> nx = ny.
 位相差層120のRe(550)は、好ましくは100nm~190nmであり、Re(450)/Re(550)は、好ましくは0.8以上1未満である。さらに、位相差層120の遅相軸と偏光子10の吸収軸とのなす角度は、好ましくは40°~50°である。 The Re (550) of the retardation layer 120 is preferably 100 nm to 190 nm, and the Re (450) / Re (550) is preferably 0.8 or more and less than 1. Further, the angle formed by the slow axis of the retardation layer 120 and the absorption axis of the polarizing element 10 is preferably 40 ° to 50 °.
B-2.位相差層
 位相差層120は、目的に応じて任意の適切な光学的特性および/または機械的特性を有し得る。位相差層は、代表的には遅相軸を有する。1つの実施形態においては、位相差層の遅相軸と偏光子10の吸収軸とのなす角度θは、上記のとおり好ましくは40°~50°であり、より好ましくは42°~48°であり、さらに好ましくは約45°である。角度θがこのような範囲であれば、後述するように位相差層をλ/4板とすることにより、非常に優れた円偏光特性(結果として、非常に優れた反射防止特性)を有する位相差層付偏光板が得られ得る。
B-2. Phase difference layer The phase difference layer 120 may have any suitable optical and / or mechanical properties depending on the intended purpose. The retardation layer typically has a slow phase axis. In one embodiment, the angle θ formed by the slow axis of the retardation layer and the absorption axis of the polarizing element 10 is preferably 40 ° to 50 °, more preferably 42 ° to 48 ° as described above. Yes, more preferably about 45 °. If the angle θ is in such a range, as will be described later, by using a λ / 4 plate as the retardation layer, a very excellent circularly polarized light characteristic (as a result, a very excellent antireflection characteristic) can be obtained. A polarizing plate with a difference layer can be obtained.
 位相差層は、好ましくは屈折率特性がnx>ny≧nzの関係を示す。位相差層は、代表的には偏光板に反射防止特性を付与するために設けられ、1つの実施形態においてはλ/4板として機能し得る。この場合、位相差層の面内位相差Re(550)は、好ましくは100nm~190nm、より好ましくは110nm~170nm、さらに好ましくは130nm~160nmである。なお、ここで「ny=nz」はnyとnzが完全に等しい場合だけではなく、実質的に等しい場合を包含する。したがって、本発明の効果を損なわない範囲で、ny<nzとなる場合があり得る。 The retardation layer preferably shows a relationship in which the refractive index characteristic is nx> ny ≧ nz. The retardation layer is typically provided to impart antireflection properties to the polarizing plate and can function as a λ / 4 plate in one embodiment. In this case, the in-plane retardation Re (550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 160 nm. Here, "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effect of the present invention is not impaired.
 位相差層のNz係数は、好ましくは0.9~3、より好ましくは0.9~2.5、さらに好ましくは0.9~1.5、特に好ましくは0.9~1.3である。このような関係を満たすことにより、得られる位相差層付偏光板を画像表示装置に用いた場合に、非常に優れた反射色相を達成し得る。 The Nz coefficient of the retardation layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. .. By satisfying such a relationship, a very excellent reflected hue can be achieved when the obtained polarizing plate with a retardation layer is used in an image display device.
 位相差層は、位相差値が測定光の波長に応じて大きくなる逆分散波長特性を示してもよく、位相差値が測定光の波長に応じて小さくなる正の波長分散特性を示してもよく、位相差値が測定光の波長によってもほとんど変化しないフラットな波長分散特性を示してもよい。1つの実施形態においては、位相差層は、逆分散波長特性を示す。この場合、位相差層のRe(450)/Re(550)は、好ましくは0.8以上1未満であり、より好ましくは0.8以上0.95以下である。このような構成であれば、非常に優れた反射防止特性を実現することができる。 The retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It is also possible to exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measured light. In one embodiment, the retardation layer exhibits inverse dispersion wavelength characteristics. In this case, Re (450) / Re (550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized.
 位相差層は、光弾性係数の絶対値が好ましくは2×10-11/N以下、より好ましくは2.0×10-13/N~1.5×10-11/N、さらに好ましくは1.0×10-12/N~1.2×10-11/Nの樹脂を含む。光弾性係数の絶対値がこのような範囲であれば、加熱時の収縮応力が発生した場合に位相差変化が生じにくい。その結果、得られる画像表示装置の熱ムラが良好に防止され得る。 In the retardation layer, the absolute value of the photoelastic coefficient is preferably 2 × 10 -11 m 2 / N or less, more preferably 2.0 × 10 -13 m 2 / N to 1.5 × 10 -11 m 2 /. It contains N, more preferably 1.0 × 10-12 m 2 / N to 1.2 × 10-11 m 2 / N. When the absolute value of the photoelastic coefficient is in such a range, the phase difference change is unlikely to occur when the shrinkage stress during heating occurs. As a result, thermal unevenness of the obtained image display device can be satisfactorily prevented.
 位相差層は、代表的には樹脂フィルムの延伸フィルムで構成される。1つの実施形態において、位相差層の厚みは、好ましくは70μm以下であり、より好ましくは45μm~60μmである。位相差層の厚みがこのような範囲であれば、加熱時のカールを良好に抑制しつつ、貼り合わせ時のカールを良好に調整することができる。また、後述するように位相差層がポリカーボネート系樹脂フィルムで構成される実施形態においては、位相差層の厚みは、好ましくは40μm以下であり、より好ましくは10μm~40μmであり、さらに好ましくは20μm~30μmである。位相差層が、このような厚みを有するポリカーボネート系樹脂フィルムで構成されることにより、カールの発生を抑制しつつ、折り曲げ耐久性および反射色相の向上にも寄与し得る。 The retardation layer is typically composed of a stretched film of a resin film. In one embodiment, the thickness of the retardation layer is preferably 70 μm or less, more preferably 45 μm to 60 μm. When the thickness of the retardation layer is within such a range, it is possible to satisfactorily adjust the curl at the time of bonding while satisfactorily suppressing the curl at the time of heating. Further, as described later, in the embodiment in which the retardation layer is made of a polycarbonate resin film, the thickness of the retardation layer is preferably 40 μm or less, more preferably 10 μm to 40 μm, and further preferably 20 μm. It is ~ 30 μm. By forming the retardation layer with a polycarbonate-based resin film having such a thickness, it is possible to contribute to the improvement of bending durability and the reflected hue while suppressing the generation of curl.
 位相差層は、上記の特性を満足し得る任意の適切な樹脂フィルムで構成され得る。そのような樹脂の代表例としては、ポリカーボネート系樹脂、ポリエステルカーボネート系樹脂、ポリエステル系樹脂、ポリビニルアセタール系樹脂、ポリアリレート系樹脂、環状オレフィン系樹脂、セルロース系樹脂、ポリビニルアルコール系樹脂、ポリアミド系樹脂、ポリイミド系樹脂、ポリエーテル系樹脂、ポリスチレン系樹脂、アクリル系樹脂が挙げられる。これらの樹脂は、単独で用いてもよく組み合わせて(例えば、ブレンド、共重合)用いてもよい。位相差層が逆分散波長特性を示す樹脂フィルムで構成される場合、ポリカーボネート系樹脂またはポリエステルカーボネート系樹脂(以下、単にポリカーボネート系樹脂と称する場合がある)が好適に用いられ得る。 The retardation layer may be composed of any suitable resin film that can satisfy the above characteristics. Typical examples of such resins include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, and polyamide resins. , Polyethylene resin, polyether resin, polystyrene resin, acrylic resin and the like. These resins may be used alone or in combination (eg, blending, copolymerization). When the retardation layer is composed of a resin film exhibiting a reverse dispersion wavelength characteristic, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin) can be preferably used.
 上記ポリカーボネート系樹脂としては、本発明の効果が得られる限りにおいて、任意の適切なポリカーボネート系樹脂を用いることができる。例えば、ポリカーボネート系樹脂は、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、脂環式ジオール、脂環式ジメタノール、ジ、トリまたはポリエチレングリコール、ならびに、アルキレングリコールまたはスピログリコールからなる群から選択される少なくとも1つのジヒドロキシ化合物に由来する構造単位と、を含む。好ましくは、ポリカーボネート系樹脂は、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、脂環式ジメタノールに由来する構造単位ならびに/あるいはジ、トリまたはポリエチレングリコールに由来する構造単位と、を含み;さらに好ましくは、フルオレン系ジヒドロキシ化合物に由来する構造単位と、イソソルビド系ジヒドロキシ化合物に由来する構造単位と、ジ、トリまたはポリエチレングリコールに由来する構造単位と、を含む。ポリカーボネート系樹脂は、必要に応じてその他のジヒドロキシ化合物に由来する構造単位を含んでいてもよい。なお、本発明に好適に用いられ得るポリカーボネート系樹脂の詳細は、例えば、特開2014-10291号公報、特開2014-26266号公報、特開2015-212816号公報、特開2015-212817号公報、特開2015-212818号公報に記載されており、当該記載は本明細書に参考として援用される。 As the above-mentioned polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as the effects of the present invention can be obtained. For example, the polycarbonate-based resin has a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol, and an alkylene. Includes structural units derived from at least one dihydroxy compound selected from the group consisting of glycols or spiroglycols. Preferably, the polycarbonate-based resin is a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and / or di, tri or polyethylene glycol. Containing structural units derived from; more preferably structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. .. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds, if necessary. Details of the polycarbonate-based resin that can be suitably used for the present invention are, for example, JP-A-2014-10291, JP-A-2014-226666, JP-A-2015-212816, JP-A-2015-21217. , 2015-21218, and the description is incorporated herein by reference.
 前記ポリカーボネート系樹脂のガラス転移温度は、110℃以上150℃以下であることが好ましく、より好ましくは120℃以上140℃以下である。ガラス転移温度が過度に低いと耐熱性が悪くなる傾向にあり、フィルム成形後に寸法変化を起こす可能性があり、又、得られる有機ELパネルの画像品質を下げる場合がある。ガラス転移温度が過度に高いと、フィルム成形時の成形安定性が悪くなる場合があり、又フィルムの透明性を損なう場合がある。なお、ガラス転移温度は、JIS K 7121(1987)に準じて求められる。 The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 150 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, dimensional changes may occur after film molding, and the image quality of the obtained organic EL panel may be deteriorated. If the glass transition temperature is excessively high, the molding stability during film molding may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K7121 (1987).
 前記ポリカーボネート系樹脂の分子量は、還元粘度で表すことができる。還元粘度は、溶媒として塩化メチレンを用い、ポリカーボネート濃度を0.6g/dLに精密に調製し、温度20.0℃±0.1℃でウベローデ粘度管を用いて測定される。還元粘度の下限は、通常0.30dL/gが好ましく、より好ましは0.35dL/g以上である。還元粘度の上限は、通常1.20dL/gが好ましく、より好ましくは1.00dL/g、更に好ましくは0.80dL/gである。還元粘度が前記下限値より小さいと成形品の機械的強度が小さくなるという問題が生じる場合がある。一方、還元粘度が前記上限値より大きいと、成形する際の流動性が低下し、生産性や成形性が低下するという問題が生じる場合がある。 The molecular weight of the polycarbonate resin can be expressed by the reducing viscosity. The reduced viscosity is measured by using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g / dL, and using a Ubbelohde viscous tube at a temperature of 20.0 ° C. ± 0.1 ° C. The lower limit of the reduction viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduction viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, and further preferably 0.80 dL / g. If the reduced viscosity is smaller than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is larger than the upper limit value, the fluidity at the time of molding is lowered, and there may be a problem that the productivity and the moldability are lowered.
 ポリカーボネート系樹脂フィルムとして市販のフィルムを用いてもよい。市販品の具体例としては、帝人社製の商品名「ピュアエースWR-S」、「ピュアエースWR-W」、「ピュアエースWR-M」、日東電工社製の商品名「NRF」が挙げられる。 A commercially available film may be used as the polycarbonate resin film. Specific examples of commercially available products include Teijin's product name "Pure Ace WR-S", "Pure Ace WR-W", "Pure Ace WR-M", and Nitto Denko's product name "NRF". Will be.
 位相差層は、例えば、上記ポリカーボネート系樹脂から形成されたフィルムを延伸することにより得られる。ポリカーボネート系樹脂からフィルムを形成する方法としては、任意の適切な成形加工法が採用され得る。具体例としては、圧縮成形法、トランスファー成形法、射出成形法、押出成形法、ブロー成形法、粉末成形法、FRP成形法、キャスト塗工法(例えば、流延法)、カレンダー成形法、熱プレス法等が挙げられる。押出成形法またはキャスト塗工法が好ましい。得られるフィルムの平滑性を高め、良好な光学的均一性を得ることができるからである。成形条件は、使用される樹脂の組成や種類、位相差層に所望される特性等に応じて適宜設定され得る。なお、上記のとおり、ポリカーボネート系樹脂は、多くのフィルム製品が市販されているので、当該市販フィルムをそのまま延伸処理に供してもよい。 The retardation layer can be obtained, for example, by stretching a film formed of the above-mentioned polycarbonate resin. As a method for forming a film from a polycarbonate-based resin, any appropriate molding processing method can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (for example, a casting method), a calendar molding method, and a hot press. The law etc. can be mentioned. Extrusion molding method or cast coating method is preferable. This is because the smoothness of the obtained film can be enhanced and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the retardation layer, and the like. As described above, since many film products of the polycarbonate resin are commercially available, the commercially available film may be subjected to the stretching treatment as it is.
 樹脂フィルム(未延伸フィルム)の厚みは、位相差層の所望の厚み、所望の光学特性、後述の延伸条件等に応じて、任意の適切な値に設定され得る。好ましくは50μm~300μmである。 The thickness of the resin film (unstretched film) can be set to an arbitrary appropriate value according to a desired thickness of the retardation layer, desired optical characteristics, stretching conditions described later, and the like. It is preferably 50 μm to 300 μm.
 上記延伸は、任意の適切な延伸方法、延伸条件(例えば、延伸温度、延伸倍率、延伸方向)が採用され得る。具体的には、自由端延伸、固定端延伸、自由端収縮、固定端収縮等の様々な延伸方法を、単独で用いることも、同時もしくは逐次で用いることもできる。延伸方向に関しても、長さ方向、幅方向、厚さ方向、斜め方向等、様々な方向や次元に行なうことができる。延伸の温度は、樹脂フィルムのガラス転移温度(Tg)に対し、Tg-30℃~Tg+60℃であることが好ましく、より好ましくはTg-10℃~Tg+50℃である。 For the above stretching, any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) can be adopted. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, and fixed-end contraction can be used alone or simultaneously or sequentially. As for the stretching direction, it can be performed in various directions and dimensions such as a length direction, a width direction, a thickness direction, and an oblique direction. The stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C with respect to the glass transition temperature (Tg) of the resin film.
 上記延伸方法、延伸条件を適宜選択することにより、上記所望の光学特性(例えば、屈折率特性、面内位相差、Nz係数)を有する位相差フィルムを得ることができる。 By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained.
 1つの実施形態においては、位相差フィルムは、樹脂フィルムを一軸延伸もしくは固定端一軸延伸することにより作製される。固定端一軸延伸の具体例としては、樹脂フィルムを長手方向に走行させながら、幅方向(横方向)に延伸する方法が挙げられる。延伸倍率は、好ましくは1.1倍~3.5倍である。 In one embodiment, the retardation film is produced by uniaxially stretching or fixed-end uniaxially stretching the resin film. Specific examples of the fixed-end uniaxial stretching include a method of stretching the resin film in the width direction (lateral direction) while running the resin film in the longitudinal direction. The draw ratio is preferably 1.1 to 3.5 times.
 別の実施形態においては、位相差フィルムは、長尺状の樹脂フィルムを長手方向に対して上記の角度θの方向に連続的に斜め延伸することにより作製され得る。斜め延伸を採用することにより、フィルムの長手方向に対して角度θの配向角(角度θの方向に遅相軸)を有する長尺状の延伸フィルムが得られ、例えば、偏光子との積層に際してロールトゥロールが可能となり、製造工程を簡略化することができる。なお、角度θは、位相差層付偏光板において偏光子の吸収軸と位相差層の遅相軸とがなす角度であり得る。角度θは、上記のとおり、好ましくは40°~50°であり、より好ましくは42°~48°であり、さらに好ましくは約45°である。 In another embodiment, the retardation film can be produced by continuously diagonally stretching a long resin film in the direction of the above angle θ with respect to the longitudinal direction. By adopting diagonal stretching, a long stretched film having an orientation angle of an angle θ with respect to the longitudinal direction of the film (a slow axis in the direction of the angle θ) can be obtained. Roll-to-roll is possible, and the manufacturing process can be simplified. The angle θ may be an angle formed by the absorption axis of the polarizing element and the slow axis of the retardation layer in the polarizing plate with a retardation layer. As described above, the angle θ is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably about 45 °.
 斜め延伸に用いる延伸機としては、例えば、横および/または縦方向に、左右異なる速度の送り力もしくは引張り力または引き取り力を付加し得るテンター式延伸機が挙げられる。テンター式延伸機には、横一軸延伸機、同時二軸延伸機等があるが、長尺状の樹脂フィルムを連続的に斜め延伸し得る限り、任意の適切な延伸機が用いられ得る。 Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or vertical directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as the long resin film can be continuously and diagonally stretched.
 上記延伸機において左右の速度をそれぞれ適切に制御することにより、上記所望の面内位相差を有し、かつ、上記所望の方向に遅相軸を有する位相差層(実質的には、長尺状の位相差フィルム)が得られ得る。 By appropriately controlling the left and right velocities in the stretching machine, a retardation layer having the desired in-plane phase difference and having a slow phase axis in the desired direction (substantially long). A phase difference film) can be obtained.
 上記フィルムの延伸温度は、位相差層に所望される面内位相差値および厚み、使用される樹脂の種類、使用されるフィルムの厚み、延伸倍率等に応じて変化し得る。具体的には、延伸温度は、好ましくはTg-30℃~Tg+30℃、さらに好ましくはTg-15℃~Tg+15℃、最も好ましくはTg-10℃~Tg+10℃である。このような温度で延伸することにより、本発明において適切な特性を有する位相差層が得られ得る。なお、Tgは、フィルムの構成材料のガラス転移温度である。 The stretching temperature of the film can change depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably Tg-30 ° C to Tg + 30 ° C, more preferably Tg-15 ° C to Tg + 15 ° C, and most preferably Tg-10 ° C to Tg + 10 ° C. By stretching at such a temperature, a retardation layer having appropriate characteristics in the present invention can be obtained. Tg is the glass transition temperature of the constituent material of the film.
C.画像表示装置
 上記偏光板または位相差層付偏光板は、画像表示装置に適用され得る。したがって、本発明の実施形態は、そのような偏光板または位相差層付偏光板を含む画像表示装置を包含する。画像表示装置の代表例としては、液晶表示装置、エレクトロルミネセンス(EL)表示装置(例えば、有機EL表示装置、無機EL表示装置)が挙げられる。本発明の実施形態による画像表示装置は、その視認側に上記A項に記載の偏光板またはB項に記載の位相差層付偏光板を備える。位相差層付偏光板は、位相差層が画像表示セル(例えば、液晶セル、有機ELセル、無機ELセル)側となるように(偏光子が視認側となるように)積層されている。画像表示装置は、好ましくは、矩形以外の異形を有する。このような画像表示装置において、本発明の実施形態による効果が顕著である。異形を有する画像表示装置の具体例としては、自動車のメーターパネル、スマートフォン、タブレット型PC、スマートウォッチが挙げられる。
C. Image display device The above-mentioned polarizing plate or a polarizing plate with a retardation layer can be applied to an image display device. Therefore, an embodiment of the present invention includes an image display device including such a polarizing plate or a polarizing plate with a retardation layer. Typical examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device). The image display device according to the embodiment of the present invention includes the polarizing plate according to the above item A or the polarizing plate with a retardation layer according to the item B on the visible side thereof. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the image display cell side (for example, a liquid crystal cell, an organic EL cell, an inorganic EL cell) (so that the polarizing element is on the visual recognition side). The image display device preferably has a variant shape other than a rectangle. In such an image display device, the effect of the embodiment of the present invention is remarkable. Specific examples of the image display device having a deformed shape include a meter panel of an automobile, a smartphone, a tablet PC, and a smart watch.
 以下、実施例によって本発明を具体的に説明するが、本発明はこれら実施例によって限定されるものではない。各特性の測定方法は以下の通りである。なお、特に明記しない限り、実施例および比較例における「部」および「%」は重量基準である。 Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.
(1)厚み
 干渉膜厚計(大塚電子社製、製品名「MCPD-3000」)を用いて測定した。厚み算出に用いた計算波長範囲は400nm~500nmで、屈折率は1.53とした。
(2)PVAの面内位相差(Re)
 実施例および比較例で得られた偏光子/熱可塑性樹脂基材の積層体から樹脂基材を剥離除去した偏光子(偏光子単体)について、位相差測定装置(王子計測機器社製 製品名「KOBRA-31X100/IR」)を用いて、波長1000nmにおけるPVAの面内位相差(Rpva)を評価した(説明した原理にしたがい、波長1000nmにおけるトータルの面内位相差から、ヨウ素の面内位相差(Ri)を引いた数値である)。吸収端波長は600nmとした。
(3)PVAの複屈折(Δn)
 上記(2)で測定したPVAの面内位相差を、偏光子の厚みで割ることによりPVAの複屈折(Δn)を算出した。
(4)単体透過率および偏光度
 実施例および比較例で得られた偏光子/熱可塑性樹脂基材の積層体から樹脂基材を剥離除去した偏光子(偏光子単体)について、紫外可視分光光度計(日本分光社製「V-7100」)を用いて単体透過率Ts、平行透過率Tp、直交透過率Tcを測定した。これらのTs、TpおよびTcは、JIS Z 8701の2度視野(C光源)により測定して視感度補正を行なったY値である。得られたTpおよびTcから、下記式により偏光度Pを求めた。
   偏光度P(%)={(Tp-Tc)/(Tp+Tc)}1/2×100
 なお、分光光度計は、大塚電子社製「LPF-200」等でも同等の測定をすることが可能であり、いずれの分光光度計を用いた場合であっても同等の測定結果が得られることが確認されている。
(5)突き刺し強度(単位厚み当たりの破断強度)
 実施例および比較例で得られた偏光子/熱可塑性樹脂基材の積層体から偏光子を剥離し、ニードルを装着した圧縮試験機(カトーテック社製、 製品名「NDG5」ニードル貫通力測定仕様)に載置し、室温(23℃±3℃)環境下、突き刺し速度0.33cm/秒で突き刺し、偏光子が割れたときの強度を破断強度とした。評価値は試料片10個の破断強度を測定し、その平均値を用いた。なお、ニードルは、先端径1mmφ、0.5Rのものを用いた。測定する偏光子については、直径約11mmの円形の開口部を有する治具を偏光子の両面から挟んで固定し、開口部の中央にニードルを突き刺して試験を行った。
(6)PVAの配向関数
 実施例および比較例で得られた偏光子/熱可塑性樹脂基材の積層体から樹脂基材を剥離除去した偏光子(偏光子単体)について、樹脂基材を剥離した面と反対側の面に対して、フーリエ変換赤外分光光度計(FT-IR)(Perkin Elmer社製、商品名:「Frontier」)を用い、偏光された赤外光を測定光として、偏光子表面の全反射減衰分光(ATR:attenuated total reflection)測定を行った。偏光子を密着させる結晶子はゲルマニウムを用い、測定光の入射角は45°入射とした。配向関数の算出は以下の手順で行った。入射させる偏光された赤外光(測定光)は、ゲルマニウム結晶のサンプルを密着させる面に平行に振動する偏光(s偏光)とし、測定光の偏光方向に対し、偏光子の延伸方向を垂直(⊥)および平行(//)に配置した状態で各々の吸光度スペクトルを測定した。得られた吸光度スペクトルから、(3330cm-1強度)を参照とした(2941cm-1強度)Iを算出した。Iは、測定光の偏光方向に対し偏光子の延伸方向を垂直(⊥)に配置した場合に得られる吸光度スペクトルから得られる(2941cm-1強度)/(3330cm-1強度)である。また、I//は、測定光の偏光方向に対し偏光子の延伸方向を平行(//)に配置した場合に得られる吸光度スペクトルから得られる(2941cm-1強度)/(3330cm-1強度)である。ここで、(2941cm-1強度)は、吸光度スペクトルのボトムである、2770cm-1と2990cm-1をベースラインとしたときの2941cm-1の吸光度であり、(3330cm-1強度)は、2990cm-1と3650cm-1をベースラインとしたときの3330cm-1の吸光度である。得られたIおよびI//を用い、式1に従って配向関数fを算出した。なお、f=1のとき完全配向、f=0のときランダムとなる。また、2941cm-1のピークは、偏光子中のPVAの主鎖(-CH-)の振動起因の吸収といわれている。また、3330cm-1のピークは、PVAの水酸基の振動起因の吸収といわれている。
   (式1)f=(3<cosθ>-1)/2
        =(1-D)/[c(2D+1)]
但し
c=(3cosβ-1)/2
で、上記のように2941cm-1を用いた場合、β=90°⇒y=-2×(1-D)/(2D+1)である。
θ:延伸方向に対する分子鎖の角度
β:分子鎖軸に対する遷移双極子モーメントの角度
D=(I)/(I//
:測定光の偏光方向と偏光子の延伸方向が垂直の場合の吸収強度
//:測定光の偏光方向と偏光子の延伸方向が平行の場合の吸収強度
(7)クラック発生率
 実施例および比較例で得られた偏光板(または位相差層付偏光板)の保護層表面に表面保護フィルムを仮着した。次いで、当該偏光板(または位相差層付偏光板)の粘着剤層にセパレーターを仮着した。この積層体を約130mm×約70mmに切り出した。このとき、偏光子の吸収軸が短手方向となるように切り出した。切り出した積層体の短辺の中央部に幅5mm、深さ(凹部の長さ)6.85mm、曲率半径2.5mmのU字ノッチを形成した。U字ノッチは、エンドミル加工により形成した。エンドミルの外径は4mm、送り速度は500mm/分、回転数は35000rpm、削り量および削り回数は粗削り0.2mm/回、仕上げ削り0.1mm/回の合計2回であった。U字ノッチを形成した積層体からセパレーターを剥離し、アクリル系粘着剤層を介してガラス板(厚み1.1mm)に貼り付けた。最後に、表面保護フィルムを剥離し、保護層/偏光子/粘着剤層/ガラス板(または保護層/偏光子/粘着剤層/位相差層/粘着剤層/ガラス板)の構成を有する試験サンプルを得た。この試験サンプルを-40℃で30分間保持した後85℃で30分間保持することを300サイクル繰り返すヒートショック試験に供し、試験後のL字クラック発生の有無を目視で確認した。この評価を3枚の偏光板(または位相差層付偏光板)を用いて行い、クラック(実質的には、L字クラック)の発生した偏光板(または位相差層付偏光板)の数を評価した。
(1) Thickness Measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The calculated wavelength range used for the thickness calculation was 400 nm to 500 nm, and the refractive index was 1.53.
(2) In-plane phase difference (Re) of PVA
A phase difference measuring device (product name manufactured by Oji Measuring Instruments Co., Ltd.) is used for the polarizing element (polarizer unit) obtained by removing the resin base material from the laminate of the polarizing element / thermoplastic resin base material obtained in Examples and Comparative Examples. KOBRA-31X100 / IR ”) was used to evaluate the in-plane phase difference (Rpva) of PVA at a wavelength of 1000 nm (according to the explained principle, from the total in-plane phase difference at a wavelength of 1000 nm, the in-plane phase difference of iodine. (Ri) is subtracted). The absorption edge wavelength was set to 600 nm.
(3) Birefringence of PVA (Δn)
The birefringence (Δn) of PVA was calculated by dividing the in-plane phase difference of PVA measured in (2) above by the thickness of the substituent.
(4) Single Transmittance and Polarization Degree The ultraviolet-visible spectrophotometric degree of the polarizing element (polarizer unit) obtained by peeling and removing the resin base material from the polarizing element / thermoplastic resin base material laminates obtained in Examples and Comparative Examples. A single transmittance Ts, a parallel transmittance Tp, and a orthogonal transmittance Tc were measured using a meter (“V-7100” manufactured by Nippon Spectroscopy Co., Ltd.). These Ts, Tp and Tc are Y values measured by the JIS Z 8701 2 degree field of view (C light source) and corrected for luminosity factor. From the obtained Tp and Tc, the degree of polarization P was determined by the following formula.
Polarization degree P (%) = {(Tp-Tc) / (Tp + Tc)} 1/2 × 100
It should be noted that the spectrophotometer can be used for the same measurement with "LPF-200" manufactured by Otsuka Electronics Co., Ltd., and the same measurement result can be obtained regardless of which spectrophotometer is used. Has been confirmed.
(5) Puncture strength (breaking strength per unit thickness)
Compression tester (manufactured by Kato Tech Co., Ltd., product name "NDG5" needle penetration force measurement specification) in which the stator is peeled off from the laminate of the stator / thermoplastic resin base material obtained in Examples and Comparative Examples and a needle is attached. ), And pierced at a piercing speed of 0.33 cm / sec under a room temperature (23 ° C ± 3 ° C) environment, and the strength when the polarizing element was broken was defined as the breaking strength. As the evaluation value, the breaking strength of 10 sample pieces was measured, and the average value thereof was used. The needle used had a tip diameter of 1 mmφ and 0.5R. The polarizing element to be measured was fixed by sandwiching a jig having a circular opening having a diameter of about 11 mm from both sides of the polarizing element, and a needle was pierced into the center of the opening to perform a test.
(6) PVA Orientation Function The resin base material was peeled off from the spectrometer (separator alone) from which the resin base material was peeled off from the laminate of the spectrometer / thermoplastic resin base material obtained in Examples and Comparative Examples. A Fourier transform infrared spectrophotometer (FT-IR) (manufactured by Perkin Elmer, trade name: "Frontier") is used for the surface opposite to the surface, and polarized infrared light is used as measurement light for polarization. Total internal reflection spectroscopy (ATR) measurement of the child surface was performed. Germanium was used as the crystallite to which the polarizing element was brought into close contact, and the incident angle of the measured light was 45 °. The orientation function was calculated according to the following procedure. The incident polarized infrared light (measurement light) is polarized light (s-polarized light) that vibrates parallel to the surface to which the germanium crystal sample is in close contact, and the extension direction of the substituent is perpendicular to the polarization direction of the measurement light (measurement light). ⊥) and parallel (//) were arranged, and the respective absorbance spectra were measured. From the obtained absorbance spectrum, (2941 cm -1 intensity) I was calculated with reference to (3330 cm -1 intensity). I is (2941 cm -1 intensity) / (3330 cm -1 intensity) obtained from the absorbance spectrum obtained when the stretching direction of the modulator is arranged perpendicularly (⊥) with respect to the polarization direction of the measurement light. Further, I // is obtained from the absorbance spectrum obtained when the stretching direction of the splitter is arranged parallel (//) with respect to the polarization direction of the measurement light (2941 cm -1 intensity) / (3330 cm -1 intensity). Is. Here, (2941 cm -1 intensity) is the absorbance of 2941 cm -1 when 2770 cm -1 and 2990 cm -1 , which are the bottoms of the absorbance spectrum, are used as baselines, and (3330 cm -1 intensity) is 2990 cm . It is the absorbance of 3330 cm -1 with 1 and 3650 cm -1 as the baseline. Using the obtained I and I // , the orientation function f was calculated according to Equation 1. When f = 1, it is completely oriented, and when f = 0, it is random. Further, the peak of 2941 cm -1 is said to be absorption caused by vibration of the main chain (-CH 2- ) of PVA in the polarizing element. The peak of 3330 cm -1 is said to be absorbed due to the vibration of the hydroxyl group of PVA.
(Equation 1) f = (3 <cos 2 θ> -1) / 2
= (1-D) / [c (2D + 1)]
However, c = (3cos 2 β-1) / 2
Then, when 2941 cm -1 is used as described above, β = 90 ° ⇒ y = -2 × (1-D) / (2D + 1).
θ: Angle of molecular chain with respect to stretching direction β: Angle of transition dipole moment with respect to molecular chain axis D = (I ) / (I // )
I : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing element are perpendicular to each other I // : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing element are parallel (7) Crack occurrence rate A surface protective film was temporarily attached to the surface of the protective layer of the polarizing plate (or the polarizing plate with a retardation layer) obtained in Examples and Comparative Examples. Next, a separator was temporarily attached to the pressure-sensitive adhesive layer of the polarizing plate (or a polarizing plate with a retardation layer). This laminate was cut out to a size of about 130 mm × about 70 mm. At this time, the absorber was cut out so that the absorption axis was in the lateral direction. A U-shaped notch having a width of 5 mm, a depth (length of the recess) of 6.85 mm, and a radius of curvature of 2.5 mm was formed in the central portion of the short side of the cut-out laminate. The U-shaped notch was formed by end milling. The outer diameter of the end mill was 4 mm, the feed rate was 500 mm / min, the rotation speed was 35,000 rpm, the amount of cutting and the number of times of cutting were 0.2 mm / time for rough cutting and 0.1 mm / time for finish cutting, for a total of 2 times. The separator was peeled off from the laminate having the U-shaped notch formed, and attached to a glass plate (thickness 1.1 mm) via an acrylic pressure-sensitive adhesive layer. Finally, a test in which the surface protective film is peeled off and has a structure of a protective layer / a polarizing element / an adhesive layer / a glass plate (or a protective layer / a polarizing element / an adhesive layer / a retardation layer / an adhesive layer / a glass plate). A sample was obtained. This test sample was held at −40 ° C. for 30 minutes and then held at 85 ° C. for 30 minutes for 300 cycles of repeated heat shock tests, and the presence or absence of L-shaped cracks after the test was visually confirmed. This evaluation was performed using three polarizing plates (or polarizing plates with a retardation layer), and the number of polarizing plates (or polarizing plates with a retardation layer) in which cracks (substantially L-shaped cracks) were generated was determined. evaluated.
[実施例1]
1.偏光子の作製
 熱可塑性樹脂基材として、長尺状で、吸水率0.75%、Tg約75℃である、非晶質のイソフタル共重合ポリエチレンテレフタレートフィルム(厚み:100μm)を用いた。樹脂基材の片面に、コロナ処理(処理条件:55W・min/m)を施した。
 ポリビニルアルコール(重合度4200、ケン化度99.2モル%)およびアセトアセチル変性PVA(日本合成化学工業社製、商品名「ゴーセファイマーZ410」)を9:1で混合したPVA系樹脂100重量部に、ヨウ化カリウム13重量部を添加し、PVA水溶液(塗布液)を調製した。
 樹脂基材のコロナ処理面に、上記PVA水溶液を塗布して60℃で乾燥することにより、厚み13μmのPVA系樹脂層を形成し、積層体を作製した。
 得られた積層体を、130℃のオーブン内で周速の異なるロール間で縦方向(長手方向)に2.4倍に自由端一軸延伸した(空中補助延伸処理)。
 次いで、積層体を、液温40℃の不溶化浴(水100重量部に対して、ホウ酸を4重量部配合して得られたホウ酸水溶液)に30秒間浸漬させた(不溶化処理)。
 次いで、液温30℃の染色浴(水100重量部に対して、ヨウ素とヨウ化カリウムを1:7の重量比で配合して得られたヨウ素水溶液)に、最終的に得られる偏光子の単体透過率(Ts)が40.5%となるように濃度を調整しながら60秒間浸漬させた(染色処理)。
 次いで、液温40℃の架橋浴(水100重量部に対して、ヨウ化カリウムを3重量部配合し、ホウ酸を5重量部配合して得られたホウ酸水溶液)に30秒間浸漬させた(架橋処理)。
 その後、積層体を、液温62℃のホウ酸水溶液(ホウ酸濃度4.0重量%、ヨウ化カリウム5.0重量%)に浸漬させながら、周速の異なるロール間で縦方向(長手方向)に延伸の総倍率が3.0倍となるように一軸延伸を行った(水中延伸処理:水中延伸処理における延伸倍率は1.25倍)。
 その後、積層体を液温20℃の洗浄浴(水100重量部に対して、ヨウ化カリウムを4重量部配合して得られた水溶液)に浸漬させた(洗浄処理)。
 その後、90℃に保たれたオーブン中で乾燥しながら、表面温度が75℃に保たれたSUS製の加熱ロールに約2秒接触させた(乾燥収縮処理)。乾燥収縮処理による積層体の幅方向の収縮率は2%であった。
 このようにして、樹脂基材上に厚み7.4μmの偏光子を形成した。
[Example 1]
1. 1. Preparation of A Polarizer As a thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape, a water absorption of 0.75%, and a Tg of about 75 ° C. was used. One side of the resin base material was subjected to corona treatment (treatment conditions: 55 W · min / m 2 ).
100 weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") are mixed at a ratio of 9: 1. 13 parts by weight of potassium iodide was added to the part to prepare a PVA aqueous solution (coating liquid).
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm, and a laminate was prepared.
The obtained laminate was stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water), the polarizing element finally obtained is charged. It was immersed for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) was 40.5% (staining treatment).
Then, it was immersed in a cross-linked bath having a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight) having a liquid temperature of 62 ° C., the rolls having different peripheral speeds are subjected to the longitudinal direction (longitudinal direction). ) Was uniaxially stretched so that the total stretching ratio was 3.0 times (underwater stretching treatment: the stretching ratio in the underwater stretching treatment was 1.25 times).
Then, the laminate was immersed in a washing bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75 ° C. for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment was 2%.
In this way, a polarizing element having a thickness of 7.4 μm was formed on the resin substrate.
2.偏光板の作製
 ビフェニル骨格を有するエポキシ樹脂(三菱ケミカル社製、商品名:jER(登録商標) YX4000)15部とオキセタン樹脂(東亞合成社製、商品名:アロンオキセタン(登録商標) OXT-221)10重量部と、をメチルエチルケトン73部に溶解し、エポキシ樹脂溶液を得た。得られたエポキシ樹脂溶液に、光カチオン重合開始剤(サンアプロ社製、商品名:CPI(登録商標)-100P)2部を添加し、保護層形成組成物を得た。得られた保護層形成組成物を、上記1.で得られた樹脂基材/偏光子の積層体の偏光子表面に直接(すなわち、易接着層を形成せずに)ワイヤーバーを用いて塗布し、塗布膜を60℃で3分間乾燥した。次いで、高圧水銀ランプを用いて積算光量が600mJ/cmとなるよう紫外線を照射し、保護層を形成した。保護層の厚みは3μmであった。次いで、樹脂基材を剥離し、剥離面にアクリル系粘着剤層(厚み15μm)を設けた。このようにして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
2. 2. Fabrication of Plate Plate 15 parts of epoxy resin having a biphenyl skeleton (manufactured by Mitsubishi Chemical Co., Ltd., trade name: jER (registered trademark) YX4000) and oxetane resin (manufactured by Toagosei Co., Ltd., trade name: Aron Oxetane (registered trademark) OXT-221) 10 parts by weight and 73 parts of methyl ethyl ketone were dissolved to obtain an epoxy resin solution. To the obtained epoxy resin solution, two parts of a photocationic polymerization initiator (manufactured by San-Apro Co., Ltd., trade name: CPI (registered trademark) -100P) was added to obtain a protective layer forming composition. The obtained protective layer forming composition can be used in the above 1. It was applied directly (that is, without forming an easy-adhesion layer) to the polarizing element surface of the resin substrate / polarizing element laminate obtained in 1), and the coating film was dried at 60 ° C. for 3 minutes. Then, using a high-pressure mercury lamp, ultraviolet rays were irradiated so that the integrated light amount was 600 mJ / cm 2 , and a protective layer was formed. The thickness of the protective layer was 3 μm. Next, the resin base material was peeled off, and an acrylic pressure-sensitive adhesive layer (thickness 15 μm) was provided on the peeled surface. In this way, a polarizing plate having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer was obtained.
[実施例2~4]
 ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は実施例1と同様にして、樹脂基材上に偏光子(厚み:7.4μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Examples 2 to 4]
A polarizing element (thickness: 7.4 μm) was formed on the resin substrate in the same manner as in Example 1 except that dyeing baths having different iodine concentrations (weight ratio of iodine to potassium iodide = 1: 7) were used. did. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例5]
 水中延伸の延伸倍率を1.46倍としたこと(結果として、延伸の総倍率を3.5倍としたこと)以外は実施例1と同様にして、樹脂基材上に偏光子(厚み:6.7μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Example 5]
The polarizing element (thickness:: 6.7 μm) was formed. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例6-1]
 ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は実施例5と同様にして、樹脂基材上に偏光子(厚み:6.7μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Example 6-1]
A polarizing element (thickness: 6.7 μm) was formed on the resin substrate in the same manner as in Example 5 except that dyeing baths having different iodine concentrations (weight ratio of iodine to potassium iodide = 1: 7) were used. did. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例6-2]
 実施例6-1と同様にして樹脂基材/偏光子(厚み:6.7μm)の積層体を得た。一方、エポキシ樹脂(三菱ケミカル株式会社製、商品名:jER(登録商標) YX6954BH30、重量平均分子量:36000、エポキシ当量:13000)20部をメチルエチルケトン80部に溶解し、エポキシ樹脂溶液(20%)を得た。このエポキシ樹脂溶液を、上記積層体の偏光子表面にワイヤーバーを用いて塗布し、塗布膜を60℃で3分間乾燥して、塗布膜の固化物として構成される保護層を形成した。保護層の厚みは3μmであった。次いで、樹脂基材を剥離し、剥離面に実施例1と同様のアクリル系粘着剤層を設けた。このようにして、保護層(エポキシ樹脂の塗布膜の固化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Example 6-2]
A laminate of resin base material / polarizing element (thickness: 6.7 μm) was obtained in the same manner as in Example 6-1. On the other hand, 20 parts of epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: jER (registered trademark) YX6954BH30, weight average molecular weight: 36000, epoxy equivalent: 13000) was dissolved in 80 parts of methyl ethyl ketone, and an epoxy resin solution (20%) was added. Obtained. This epoxy resin solution was applied to the surface of the polarizing element of the laminate using a wire bar, and the coating film was dried at 60 ° C. for 3 minutes to form a protective layer formed as a solidified product of the coating film. The thickness of the protective layer was 3 μm. Next, the resin base material was peeled off, and the same acrylic pressure-sensitive adhesive layer as in Example 1 was provided on the peeled surface. In this way, a polarizing plate having a structure of a protective layer (solidified layer of an epoxy resin coating film) / a polarizing element / an adhesive layer was obtained.
[実施例6-3]
 実施例6-1と同様にして樹脂基材/偏光子(厚み:6.7μm)の積層体を得た。得られた積層体の偏光子面に、易接着層としてポリウレタン系の水系分散樹脂(第一工業製薬社製、製品名:スーパーフレックスSF210)を厚みが0.1μmになるように塗布し、易接着層を形成した。一方、100%ポリメチルメタクリレートであるアクリル系樹脂(楠本化成社製、製品名:B-728)20重量部をメチルエチルケトン80重量部に溶解し、アクリル系樹脂溶液(20%)を得た。このアクリル系樹脂溶液を、易接着層表面にワイヤーバーを用いて塗布し、塗布膜を60℃で5分間乾燥して、塗布膜の固化物として構成される保護層を形成した。保護層の厚みは2μmであった。さらに、保護層の易接着層と反対側の面にさらにハードコート層(厚み3μm)を形成した。ハードコート(HC)層は、ジメチロール-トリシクロデカンジアクリレート(共栄社化学製、商品名:ライトアクリレートDCP-A)70重量部、イソボルニルアクリレート(共栄社化学製、商品名:ライトアクリレートIB-XA)20重量部、1,9-ノナンジオールジアクリレート(共栄社化学製、商品名:ライトアクリレート1.9NA-A)10重量部、さらに、光重合開始剤(BASF社製、商品名:イルガキュア907)3重量部を、適当な溶媒を用いて混合し、得られた塗工液を、硬化後に3μmになるように保護層面上に塗布し、次いで、溶媒を乾燥させ、高圧水銀ランプを用いて積算光量300mJ/cmとなるよう紫外線を窒素雰囲気下にて照射すること形成した。最後に、樹脂基材を剥離し、剥離面に実施例1と同様のアクリル系粘着剤層を設けた。このようにして、HC層/保護層(アクリル樹脂の塗布膜の固化層)/易接着層/偏光子/粘着剤層の構成を有する偏光板を得た。
[Example 6-3]
A laminate of resin base material / polarizing element (thickness: 6.7 μm) was obtained in the same manner as in Example 6-1. A polyurethane-based water-based dispersion resin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Superflex SF210) was applied as an easy-adhesion layer to the polarizing surface of the obtained laminate so that the thickness was 0.1 μm. An adhesive layer was formed. On the other hand, 20 parts by weight of an acrylic resin (manufactured by Kusumoto Kasei Co., Ltd., product name: B-728) which is 100% polymethylmethacrylate was dissolved in 80 parts by weight of methyl ethyl ketone to obtain an acrylic resin solution (20%). This acrylic resin solution was applied to the surface of the easy-adhesion layer using a wire bar, and the coating film was dried at 60 ° C. for 5 minutes to form a protective layer composed of a solidified coating film. The thickness of the protective layer was 2 μm. Further, a hard coat layer (thickness 3 μm) was further formed on the surface of the protective layer opposite to the easy-adhesion layer. The hard coat (HC) layer is 70 parts by weight of dimethylol-tricyclodecanediacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate DCP-A), isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light acrylate IB-XA). ) 20 parts by weight, 1,9-nonanediol diacrylate (Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate 1.9NA-A) 10 parts by weight, and a photopolymerization initiator (BASF Co., Ltd., trade name: Irgacure 907). 3 parts by weight were mixed using an appropriate solvent, and the obtained coating liquid was applied onto the protective layer surface so as to be 3 μm after curing, and then the solvent was dried and integrated using a high-pressure mercury lamp. It was formed by irradiating ultraviolet rays in a nitrogen atmosphere so that the amount of light was 300 mJ / cm 2 . Finally, the resin base material was peeled off, and the same acrylic pressure-sensitive adhesive layer as in Example 1 was provided on the peeled surface. In this way, a polarizing plate having a structure of an HC layer / a protective layer (a solidified layer of an acrylic resin coating film) / an easy-adhesion layer / a polarizing element / an adhesive layer was obtained.
[実施例7~8]
 ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は実施例5と同様にして、樹脂基材上に偏光子(厚み:6.7μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Examples 7 to 8]
A polarizing element (thickness: 6.7 μm) was formed on the resin substrate in the same manner as in Example 5 except that dyeing baths having different iodine concentrations (weight ratio of iodine to potassium iodide = 1: 7) were used. did. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例9~12]
 水中延伸の延伸倍率を1.67倍としたこと(結果として、延伸の総倍率を4.0倍としたこと)、および、ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は実施例1と同様にして、樹脂基材上に偏光子(厚み:6.2μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Examples 9 to 12]
The stretch ratio of stretching in water was 1.67 times (as a result, the total ratio of stretching was 4.0 times), and the dyeing baths with different iodine concentrations (weight ratio of iodine and potassium iodide = 1). A polarizing element (thickness: 6.2 μm) was formed on the resin substrate in the same manner as in Example 1 except that: 7) was used. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例13~16]
 水中延伸の延伸倍率を1.88倍としたこと(結果として、延伸の総倍率を4.5倍としたこと)、および、ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は実施例1と同様にして、樹脂基材上に偏光子(厚み:6.0μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Examples 13 to 16]
The stretching ratio of stretching in water was 1.88 times (as a result, the total ratio of stretching was 4.5 times), and the dyeing baths with different iodine concentrations (weight ratio of iodine and potassium iodide = 1). A polarizing element (thickness: 6.0 μm) was formed on the resin substrate in the same manner as in Example 1 except that: 7) was used. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[比較例1]
 水中延伸の延伸倍率を2.29倍としたこと(結果として、延伸の総倍率を5.5倍としたこと)以外は実施例1と同様にして、樹脂基材上に偏光子(厚み:5.5μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Comparative Example 1]
The polarizing element (thickness:: 5.5 μm) was formed. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[比較例2-1]
 ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は比較例1と同様にして、樹脂基材上に偏光子(厚み:5.5μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Comparative Example 2-1]
A polarizing element (thickness: 5.5 μm) was formed on the resin substrate in the same manner as in Comparative Example 1 except that dyeing baths having different iodine concentrations (weight ratio of iodine to potassium iodide = 1: 7) were used. did. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[比較例2-2]
 実施例6-2と同様のエポキシ樹脂溶液を用いて保護層を形成したこと以外は比較例2-1と同様にして、保護層(エポキシ樹脂の塗布膜の固化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Comparative Example 2-2]
Protective layer (solidified layer of epoxy resin coating film) / polarizing element / adhesive in the same manner as in Comparative Example 2-1 except that the protective layer was formed using the same epoxy resin solution as in Example 6-2. A polarizing plate having a layer structure was obtained.
[比較例2-3]
 実施例6-3と同様のアクリル樹脂溶液を用いて保護層を形成したこと以外は比較例2-1と同様にして、保護層(アクリル樹脂の塗布膜の固化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Comparative Example 2-3]
Protective layer (solidified layer of acrylic resin coating film) / polarizing element / adhesive in the same manner as in Comparative Example 2-1 except that the protective layer was formed using the same acrylic resin solution as in Example 6-3. A polarizing plate having a layer structure was obtained.
[比較例3~4]
 ヨウ素濃度が異なる染色浴(ヨウ素とヨウ化カリウムの重量比=1:7)を用いたこと以外は比較例1と同様にして、樹脂基材上に偏光子(厚み:5.5μm)を形成した。以下の手順は実施例1と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層の構成を有する偏光板を得た。
[Comparative Examples 3 to 4]
A polarizing element (thickness: 5.5 μm) was formed on the resin substrate in the same manner as in Comparative Example 1 except that dyeing baths having different iodine concentrations (weight ratio of iodine to potassium iodide = 1: 7) were used. did. The following procedure was the same as in Example 1 to obtain a polarizing plate having a protective layer (photocationic curing layer of epoxy resin) / polarizing element / adhesive layer.
[実施例17]
1.位相差層を構成する位相差フィルムの作製
 撹拌翼および100℃に制御された還流冷却器を具備した縦型反応器2器からなるバッチ重合装置を用いて重合を行った。ビス[9-(2-フェノキシカルボニルエチル)フルオレン-9-イル]メタン29.60質量部(0.046mol)、イソソルビド(ISB)29.21質量部(0.200mol)、スピログリコール(SPG)42.28質量部(0.139mol)、ジフェニルカーボネート(DPC)63.77質量部(0.298mol)及び触媒として酢酸カルシウム1水和物1.19×10-2質量部(6.78×10-5mol)を仕込んだ。反応器内を減圧窒素置換した後、熱媒で加温を行い、内温が100℃になった時点で撹拌を開始した。昇温開始40分後に内温を220℃に到達させ、この温度を保持するように制御すると同時に減圧を開始し、220℃に到達してから90分で13.3kPaにした。重合反応とともに副生するフェノール蒸気を100℃の還流冷却器に導き、フェノール蒸気中に若干量含まれるモノマー成分を反応器に戻し、凝縮しないフェノール蒸気は45℃の凝縮器に導いて回収した。第1反応器に窒素を導入して一旦大気圧まで復圧させた後、第1反応器内のオリゴマー化された反応液を第2反応器に移した。次いで、第2反応器内の昇温および減圧を開始して、50分で内温240℃、圧力0.2kPaにした。その後、所定の攪拌動力となるまで重合を進行させた。所定動力に到達した時点で反応器に窒素を導入して復圧し、生成したポリエステルカーボネート系樹脂を水中に押し出し、ストランドをカッティングしてペレットを得た。
[Example 17]
1. 1. Preparation of a retardation film constituting the retardation layer Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. Bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] 29.60 parts by mass (0.046 mol) of methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42 of spiroglycol (SPG) .28 parts by mass (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC) and calcium acetate monohydrate 1.19 x 10 -2 parts by mass (6.78 x 10- ) as a catalyst. 5 mol) was charged. After substituting nitrogen under reduced pressure in the reactor, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was 13.3 kPa 90 minutes after reaching 220 ° C. The phenol vapor produced by the polymerization reaction was guided to a reflux condenser at 100 ° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the non-condensed phenol vapor was guided to a condenser at 45 ° C. for recovery. Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.
 得られたポリエステルカーボネート系樹脂(ペレット)を80℃で5時間真空乾燥をした後、単軸押出機(東芝機械社製、シリンダー設定温度:250℃)、Tダイ(幅200mm、設定温度:250℃)、チルロール(設定温度:120~130℃)および巻取機を備えたフィルム製膜装置を用いて、厚み130μmの長尺状の樹脂フィルムを作製した。得られた長尺状の樹脂フィルムを、所定の位相差が得られるように調整しながら延伸し、厚み48μmの位相差フィルムを得た。延伸条件は、幅方向に、延伸温度143℃、延伸倍率2.8倍であった。得られた位相差フィルムのRe(550)は141nmであり、Re(450)/Re(550)は0.86であり、Nz係数は1.12であった。 After vacuum-drying the obtained polyester carbonate-based resin (pellet) at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Toshiba Machinery Co., Ltd., cylinder set temperature: 250 ° C.), T-die (width 200 mm, set temperature: 250). A long resin film having a thickness of 130 μm was prepared by using a film forming apparatus equipped with a chill roll (set temperature: 120 to 130 ° C.) and a winder. The obtained long resin film was stretched while adjusting so that a predetermined retardation was obtained, to obtain a retardation film having a thickness of 48 μm. The stretching conditions were a stretching temperature of 143 ° C. and a stretching ratio of 2.8 times in the width direction. The Re (550) of the obtained retardation film was 141 nm, the Re (450) / Re (550) was 0.86, and the Nz coefficient was 1.12.
2.位相差層付偏光板の作製
 実施例6-1と同様にして樹脂基材/偏光子(厚み:6.7μm)の積層体を得た。積層体の偏光子表面に実施例1と同様にして保護層(エポキシ樹脂の光カチオン硬化層)を形成した。次いで、樹脂基材を剥離し、剥離面に上記で得られた位相差フィルム(位相差層)を、厚み5μmのアクリル系粘着剤層を介して貼り合わせた。その際、位相差層の遅相軸と偏光子の吸収軸とが45°の角度をなすようにして貼り合わせた。最後に、位相差層表面に実施例1と同様のアクリル系粘着剤層を設けた。このようにして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層/位相差層/粘着剤層の構成を有する位相差層付偏光板を得た。
2. 2. Preparation of polarizing plate with retardation layer A laminate of resin base material / polarizing element (thickness: 6.7 μm) was obtained in the same manner as in Example 6-1. A protective layer (photocationic curing layer of epoxy resin) was formed on the surface of the polarizing element of the laminate in the same manner as in Example 1. Next, the resin base material was peeled off, and the retardation film (phase difference layer) obtained above was attached to the peeled surface via an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm. At that time, the slow axis of the retardation layer and the absorption axis of the polarizing element were bonded so as to form an angle of 45 °. Finally, the same acrylic pressure-sensitive adhesive layer as in Example 1 was provided on the surface of the retardation layer. In this way, a polarizing plate with a retardation layer having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / pressure-sensitive adhesive layer / retardation layer / pressure-sensitive adhesive layer was obtained.
[比較例5]
 比較例2-1と同様にして樹脂基材/偏光子(厚み:5.5μm)の積層体を得た。この積層体を用いたこと以外は実施例17と同様にして、保護層(エポキシ樹脂の光カチオン硬化層)/偏光子/粘着剤層/位相差層/粘着剤層の構成を有する位相差層付偏光板を得た。
[Comparative Example 5]
A laminate of resin base material / polarizing element (thickness: 5.5 μm) was obtained in the same manner as in Comparative Example 2-1. A retardation layer having a structure of a protective layer (photocationic curing layer of epoxy resin) / polarizing element / pressure-sensitive adhesive layer / retardation layer / pressure-sensitive adhesive layer in the same manner as in Example 17 except that this laminate is used. A polarizing plate was obtained.
 実施例および比較例で得られた偏光板または位相差層付偏光板を上記(2)~(7)の評価に供した。結果を表1に示す。 The polarizing plates obtained in Examples and Comparative Examples or the polarizing plates with a retardation layer were subjected to the evaluations (2) to (7) above. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
 表1から明らかなように、実施例の偏光板および位相差層付偏光板は、異形加工部(U字ノッチ部分)のクラック発生が抑制されている。 As is clear from Table 1, in the polarizing plate of the embodiment and the polarizing plate with a retardation layer, the generation of cracks in the deformed portion (U-shaped notch portion) is suppressed.
 また、図8~図10にそれぞれ、実施例および比較例で得られた偏光子の単体透過率とPVAのΔn、面内位相差または配向関数との関係を示す。図8~図10に示される通り、複屈折、面内位相差または配向関数が同程度(結果として、配向度が同程度)であったとしても、単体透過率が高い場合には、異形加工部においてクラックが発生しやすいことがわかる。例えば、図8においてΔnが35(×10-3)付近を見ると、単体透過率が約44.2%より大きくなると式(1)を満たさなくなり、結果として、比較例4のようにクラックが発生する。よって、異形加工部におけるクラックの発生を効果的に抑制するためには、PVA系樹脂の配向度に加えて単体透過率(結果として、二色性物質の吸着量)の調整も重要であることがわかる。また、式(1)、式(2)および/または式(3)を満たす偏光子は、これらの調整が好適に行われたものであり、異形加工部におけるクラックの発生が好適に抑制され得ることがわかる。 Further, FIGS. 8 to 10 show the relationship between the simple substance transmittance of the polarizing element obtained in Examples and Comparative Examples, Δn of PVA, the in-plane phase difference, or the orientation function, respectively. As shown in FIGS. 8 to 10, even if the birefringence, the in-plane phase difference, or the orientation function is the same (as a result, the degree of orientation is the same), if the single transmittance is high, the deformed shape is processed. It can be seen that cracks are likely to occur in the portion. For example, when Δn is around 35 (× 10 -3 ) in FIG. 8, when the simple substance transmittance becomes larger than about 44.2%, the equation (1) is not satisfied, and as a result, cracks are generated as in Comparative Example 4. appear. Therefore, in order to effectively suppress the occurrence of cracks in the deformed portion, it is important to adjust the single transmittance (as a result, the amount of adsorbed dichroic substance) in addition to the degree of orientation of the PVA-based resin. I understand. Further, the polarizing element satisfying the formula (1), the formula (2) and / or the formula (3) is preferably adjusted, and the generation of cracks in the deformed portion can be suitably suppressed. You can see that.
 本発明の偏光板は、画像表示装置に用いられ、特に、自動車のメーターパネル、スマートフォン、タブレット型PC、スマートウォッチ等の異形を有する画像表示装置に好適に用いられる。 The polarizing plate of the present invention is used for an image display device, and is particularly preferably used for an image display device having a deformed shape such as an automobile meter panel, a smartphone, a tablet PC, or a smart watch.

Claims (17)

  1.  偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有する偏光板であって、
     該偏光板は矩形以外の異形を有し、
     該保護層は10μm以下の厚みを有する樹脂膜で構成されており、
     該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂の複屈折をyとした場合に、下記式(1)を満たす、偏光板:
       y<-0.011x+0.525     (1)。
    A polarizing plate having a polarizing element and a protective layer arranged on at least one side of the polarizing element.
    The polarizing plate has a shape other than a rectangle and has a variant shape.
    The protective layer is made of a resin film having a thickness of 10 μm or less.
    When the polarizing element is made of a polyvinyl alcohol-based resin film containing a dichroic substance, the single transmittance is x%, and the birefringence of the polyvinyl alcohol-based resin is y, the following formula (1) is used. Satisfying, polarizing plate:
    y <−0.011x + 0.525 (1).
  2.  偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有する偏光板であって、
     該偏光板は矩形以外の異形を有し、
     該保護層は10μm以下の厚みを有する樹脂膜で構成されており、
     該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂フィルムの面内位相差をznmとした場合に、下記式(2)を満たす、偏光板:
       z<-60x+2875        (2)。
    A polarizing plate having a polarizing element and a protective layer arranged on at least one side of the polarizing element.
    The polarizing plate has a shape other than a rectangle and has a variant shape.
    The protective layer is made of a resin film having a thickness of 10 μm or less.
    The polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the in-plane retardation of the polyvinyl alcohol-based resin film is znm, the following formula is used. A polarizing plate that satisfies (2):
    z <-60x + 2875 (2).
  3.  偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有する偏光板であって、
     該偏光板は矩形以外の異形を有し、
     該保護層は10μm以下の厚みを有する樹脂膜で構成されており、
     該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、単体透過率をx%とし、該ポリビニルアルコール系樹脂の配向関数をfとした場合に、下記式(3)を満たす、偏光板:
       f<-0.018x+1.11    (3)。
    A polarizing plate having a polarizing element and a protective layer arranged on at least one side of the polarizing element.
    The polarizing plate has a shape other than a rectangle and has a variant shape.
    The protective layer is made of a resin film having a thickness of 10 μm or less.
    The polarizing element is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and when the single transmittance is x% and the orientation function of the polyvinyl alcohol-based resin is f, the following formula (3) is used. Satisfying, polarizing plate:
    f <−0.018x + 1.11 (3).
  4.  偏光子と、該偏光子の少なくとも一方の側に配置された保護層と、を有する偏光板であって、
     該偏光板は矩形以外の異形を有し、
     該保護層は10μm以下の厚みを有する樹脂膜で構成されており、
     該偏光子は、二色性物質を含むポリビニルアルコール系樹脂フィルムで構成され、かつ、突き刺し強度が30gf/μm以上である、偏光板。
    A polarizing plate having a polarizing element and a protective layer arranged on at least one side of the polarizing element.
    The polarizing plate has a shape other than a rectangle and has a variant shape.
    The protective layer is made of a resin film having a thickness of 10 μm or less.
    The polarizing element is a polarizing plate made of a polyvinyl alcohol-based resin film containing a dichroic substance and having a piercing strength of 30 gf / μm or more.
  5.  前記偏光子の厚みが10μm以下である、請求項1から4のいずれかに記載の偏光板。 The polarizing plate according to any one of claims 1 to 4, wherein the polarizing element has a thickness of 10 μm or less.
  6.  前記偏光子の単体透過率が40.0%以上であり、かつ、偏光度が99.0%以上である、請求項1から5のいずれかに記載の偏光板。 The polarizing plate according to any one of claims 1 to 5, wherein the single-unit transmittance of the polarizing element is 40.0% or more, and the degree of polarization is 99.0% or more.
  7.  前記異形が、貫通穴、V字ノッチ、U字ノッチ、平面視した場合に船形に近似した形状の凹部、平面視した場合に矩形の凹部、平面視した場合にバスタブ形状に近似したR形状の凹部、およびこれらの組み合わせからなる群から選択される、請求項1から6のいずれかに記載の偏光板。 The irregular shape is a through hole, a V-shaped notch, a U-shaped notch, a concave portion having a shape similar to a ship shape when viewed in a plane, a rectangular concave portion when viewed in a plane, and an R shape which is similar to a bathtub shape when viewed in a plane. The polarizing plate according to any one of claims 1 to 6, which is selected from the group consisting of recesses and combinations thereof.
  8.  前記U字ノッチの曲率半径が5mm以下である、請求項7に記載の偏光板。 The polarizing plate according to claim 7, wherein the radius of curvature of the U-shaped notch is 5 mm or less.
  9.  前記樹脂膜が、エポキシ樹脂および(メタ)アクリル系樹脂から選択される少なくとも1種の樹脂を含む、請求項1から8のいずれかに記載の偏光板。 The polarizing plate according to any one of claims 1 to 8, wherein the resin film contains at least one resin selected from an epoxy resin and a (meth) acrylic resin.
  10.  前記樹脂膜がエポキシ樹脂の光カチオン硬化物で構成されており、該樹脂膜の軟化温度が100℃以上である、請求項1から9のいずれかに記載の偏光板。 The polarizing plate according to any one of claims 1 to 9, wherein the resin film is composed of a photocationically cured product of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
  11.  前記樹脂膜がエポキシ樹脂の有機溶媒溶液の塗布膜の固化物で構成されており、該樹脂膜の軟化温度が100℃以上である、請求項1から9のいずれかに記載の偏光板。 The polarizing plate according to any one of claims 1 to 9, wherein the resin film is composed of a solidified coating film of an organic solvent solution of an epoxy resin, and the softening temperature of the resin film is 100 ° C. or higher.
  12.  前記樹脂膜が熱可塑性(メタ)アクリル系樹脂の有機溶媒溶液の塗布膜の固化物で構成されており、該樹脂膜の軟化温度が100℃以上である、請求項1から9のいずれかに記載の偏光板。 The method according to any one of claims 1 to 9, wherein the resin film is composed of a solidified coating film of an organic solvent solution of a thermoplastic (meth) acrylic resin, and the softening temperature of the resin film is 100 ° C. or higher. The polarizing plate according to the description.
  13.  前記熱可塑性(メタ)アクリル系樹脂が、ラクトン環単位、無水グルタル酸単位、グルタルイミド単位、無水マレイン酸単位およびマレイミド単位からなる群から選択される少なくとも1つを有する、請求項12に記載の偏光板。 12. According to claim 12, the thermoplastic (meth) acrylic resin has at least one selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit and a maleimide unit. Polarizer.
  14.  請求項1から13のいずれかに記載の偏光板と、位相差層と、を含み、
     該位相差層が、前記偏光子の前記保護層が配置された側と反対側に配置されている、位相差層付偏光板。
    The polarizing plate according to any one of claims 1 to 13 and a retardation layer are included.
    A polarizing plate with a retardation layer, wherein the retardation layer is arranged on the side opposite to the side on which the protection layer of the polarizing element is arranged.
  15.  前記位相差層のRe(550)が100nm~190nmであり、Re(450)/Re(550)が0.8以上1未満であり、
     該位相差層の遅相軸と前記偏光子の吸収軸とのなす角度が40°~50°である、請求項14に記載の位相差層付偏光板。
    The Re (550) of the retardation layer is 100 nm to 190 nm, and Re (450) / Re (550) is 0.8 or more and less than 1.
    The polarizing plate with a retardation layer according to claim 14, wherein the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing element is 40 ° to 50 °.
  16.  前記位相差層が粘着剤層を介して前記偏光板に積層されている、請求項14または15に記載の位相差層付偏光板。 The polarizing plate with a retardation layer according to claim 14 or 15, wherein the retardation layer is laminated on the polarizing plate via an adhesive layer.
  17.  請求項1から13のいずれかに記載の偏光板または請求項14から16のいずれかに記載の位相差層付偏光板を備える、画像表示装置。 An image display device comprising the polarizing plate according to any one of claims 1 to 13 or the polarizing plate with a retardation layer according to any one of claims 14 to 16.
PCT/JP2021/026726 2020-07-29 2021-07-16 Polarizing plate, polarizing plate with phase difference layer, and image display device including said polarizing plate or said polarizing plate with phase difference layer WO2022024798A1 (en)

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JP2022540177A JPWO2022024798A1 (en) 2020-07-29 2021-07-16
CN202180059184.7A CN116158208A (en) 2020-07-29 2021-07-16 Polarizing plate, polarizing plate with retardation layer, and image display device comprising the polarizing plate or polarizing plate with retardation layer
JP2024100978A JP2024114771A (en) 2020-07-29 2024-06-24 Polarizing plate, polarizing plate with retardation layer, and image display device comprising polarizing plate or polarizing plate with retardation layer

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