KR20240085205A - Polarizing plate with phase difference layers and image display device - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer that can achieve excellent reflection color, more specifically, neutral reflection color with suppressed coloring, when applied to an organic EL display device.
It includes a polarizing plate including a polarizer, a first phase contrast layer, a second phase difference layer, a third phase difference layer, and a fourth phase difference layer in this order, and the second phase difference layer and the third phase difference layer have refractive index characteristics. This relationship represents nx>ny≥nz, the first phase difference layer and the fourth phase difference layer exhibit a refractive index characteristic relationship of nz>nx=ny, and the second phase difference layer has Re(550) of 200 nm to 300 nm. The third retardation layer has a Re (550) of 120 nm to 170 nm, the angle between the slow axis of the second retardation layer and the absorption axis of the polarizer is 5° to 25°, and the slow axis of the third retardation layer is 5° to 25°. A polarizing plate with a retardation layer, wherein the angle formed between the axis and the absorption axis of the polarizer is 65° to 85°.

Description

Polarizer and image display device with phase contrast layer {POLARIZING PLATE WITH PHASE DIFFERENCE LAYERS AND IMAGE DISPLAY DEVICE}

The present invention relates to a polarizing plate with a retardation layer and an image display device.

Recently, with the spread of thin displays, image display devices (organic EL display devices) equipped with organic EL panels have been proposed. Since the organic EL panel contains a highly reflective metal layer, problems such as reflection of external light or reflection of the background are likely to occur. Accordingly, it is known to prevent these problems by providing a circularly polarizing plate on the viewer's side. As a general circularly polarizing plate, it is known that a retardation layer functioning as a λ/4 plate is laminated so that its slow axis forms an angle of about 45° with respect to the absorption axis of the polarizer. In addition, from the viewpoint of obtaining anti-reflection properties in a wide band and wide viewing angle, a circularly polarizing plate has been proposed that further includes a retardation layer functioning as a λ/2 plate and/or a retardation layer exhibiting a refractive index characteristic of nz>nx=ny ( For example, Patent Documents 1 and 2). On the other hand, there is room for further improvement in the reflected color when a circularly polarizing plate is applied to an organic EL display device.

Japanese Patent No. 6786640 Japanese Patent No. 5822006

The main purpose of the present invention is to provide a polarizing plate with a retardation layer that can achieve excellent reflection color, more specifically, neutral reflection color with suppressed coloring, when applied to an organic EL display device.

[1] A polarizing plate with a retardation layer according to an embodiment of the present invention includes a polarizing plate including a polarizer, a first retardation layer, a second retardation layer, a third retardation layer, and a fourth retardation layer in this order. And the second retardation layer and the third retardation layer have refractive index characteristics nx>ny≥nz, and the first retardation layer and the fourth retardation layer have refractive index characteristics nz>nx=ny. Indicates that the second retardation layer has Re (550) of 200 nm to 300 nm, and the third retardation layer has Re (550) of 120 nm to 170 nm, and the slow axis of the second retardation layer and the absorption axis of the polarizer are formed. The angle is 5° to 25°, and the angle between the slow axis of the third retardation layer and the absorption axis of the polarizer is 65° to 85°.

[2] In the polarizing plate with a retardation layer described in [1] above, Rth (550) of the fourth retardation layer may be -50 nm to -110 nm.

[3] In the polarizing plate with a retardation layer according to [1] or [2] above, Rth (550) of the first retardation layer may be -10 nm to -70 nm.

[4] In the polarizing plate with a retardation layer according to any one of [1] to [3] above, Rth (550) of the first retardation layer may be -10 nm to -70 nm, and Rth of the fourth retardation layer ( 550) may be -50nm to -110nm.

[5] The polarizing plate with a retardation layer according to any one of [1] to [4] above may be used in an organic EL display device.

[6] An image display device according to an embodiment of the present invention includes the polarizing plate with a retardation layer according to any one of [1] to [5] above.

According to an embodiment of the present invention, a polarizing plate with a retardation layer that can realize excellent reflection color, more specifically, neutral reflection color with suppressed coloring, when applied to an organic EL display device, is provided.

1 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer in one embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing the schematic configuration of an organic EL display device according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to make the explanation clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiment, but are only examples and do not limit the interpretation of the present invention. In this specification, (meth)acrylic refers to acrylic and/or methacrylic. In addition, in this specification, '~' indicating a numerical range includes the upper and lower numerical limits.

(Definition of terms and symbols)

The definitions of terms and symbols in this specification are as follows.

(1) Refractive index (nx, ny, nz)

'nx' is the refractive index in the direction where the in-plane refractive index is maximum (i.e., slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light with a wavelength of λ nm at 23°C. For example, 'Re(550)' is the in-plane phase difference measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d, when the thickness of the layer (film) is d (nm).

(3) Phase difference in the thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction measured with light with a wavelength of λ nm at 23°C. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d, when the thickness of the layer (film) is d (nm).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, '45°' means 45° clockwise and 45° counterclockwise.

A. Polarizer with phase contrast layer

The polarizing plate with a retardation layer according to an embodiment of the present invention includes a polarizing plate including a polarizer, a first retardation layer, a second retardation layer, a third retardation layer, and a fourth retardation layer in this order. The second retardation layer and the third retardation layer have refractive index characteristics showing a relationship of nx>ny≥nz; The first retardation layer and the fourth retardation layer have refractive index characteristics of nz>nx=ny, and the second retardation layer has Re(550) of 200 nm to 300 nm; The third phase difference layer has Re (550) of 120 nm to 170 nm; The angle between the slow axis of the second retardation layer and the absorption axis of the polarizer is 5° to 25°; The angle between the slow axis of the third retardation layer and the absorption axis of the polarizer is 65° to 85°. In addition, the first retardation layer and the fourth retardation layer whose refractive index characteristics exhibit the relationship nz>nx=ny, the second retardation layer and the third retardation layer functioning as a λ/2 plate and a λ/4 plate, respectively, and the above configuration. By using these in combination, it is possible to obtain a polarizing plate with a retardation layer that can realize extremely excellent reflected color when used in an image display device (for example, an organic EL display device).

A-1. Overall composition of polarizer with phase contrast layer

Fig. 1 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a phase difference layer includes a polarizing plate 10, a first phase difference layer 20, a second phase difference layer 30, a third phase difference layer 40, and a fourth phase difference layer 50. They are included in this order.

The polarizer 10 includes a polarizer 12 and further includes a protective layer 14 disposed on a side of the polarizer 12 opposite to the side on which the first retardation layer 20 is disposed. In the illustrated example, no protective layer is disposed between the polarizer 12 and the adjacent first retardation layer 20, and the first retardation layer 20 is disposed adjacent to the polarizer 12. By omitting the protective layer in this way, it is possible to contribute to thinning the polarizing plate 100 with a retardation layer. The polarizing plate 100 with a retardation layer is preferably used in an organic EL display device, and is arranged so that the polarizer 12 is on the visible side rather than the first retardation layer 20 in the organic EL display device.

The polarizing plate 100 with a retardation layer further includes an adhesive layer 60 on the side of the fourth retardation layer 50 opposite to the side on which the third retardation layer 40 is disposed. The polarizing plate 100 with a retardation layer can be attached to an optical member such as an organic EL panel using the adhesive layer 60, for example. Although not shown, a release liner is practically bonded to the surface of the adhesive layer 60. The release liner can be temporarily applied until the polarizer with a retardation layer is ready for use. By using a release liner, for example, the adhesive layer 60 is protected and roll formation of the polarizing plate 100 with a retardation layer becomes possible.

The polarizing plate 100 with a retardation layer may further include other functional layers not shown. The type, characteristics, number, combination, arrangement, etc. of other functional layers that the polarizer with a retardation layer may include can be appropriately set depending on the purpose. For example, the polarizing plate with a retardation layer may further include a conductive layer or an isotropic base material with a conductive layer. A polarizing plate with a retardation layer containing a conductive layer or an isotropic substrate with a conductive layer is applied, for example, to a so-called inner touch panel type input display device in which a touch sensor is built into the image display panel. As another example, the polarizing plate with a retardation layer may further include another retardation layer. The optical properties (e.g., refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, and arrangement of other retardation layers may be appropriately set depending on the purpose. As a specific example, on the viewer's side of the polarizer, another phase difference layer (typically a layer that provides an (alternative) circular polarization function and a layer that provides an ultra-high phase difference) is provided to improve visibility when viewed through polarized sunglasses. You can stay. By providing such a layer, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses, and can also be suitably applied to an image display device that can be used outdoors.

Each member constituting the polarizing plate 100 with a retardation layer is typically laminated with any appropriate adhesive layer interposed therebetween. Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. Although not shown, the protective layer 14 is bonded to the polarizer 12 through, for example, an adhesive layer (preferably using an active energy ray-curable adhesive). Also, for example, the polarizer 10 and each retardation layer are each laminated through an adhesive layer (preferably using an active energy ray-curable adhesive) or through an adhesive layer (preferably using an acrylic adhesive). It is done. The thickness of the adhesive layer is, for example, 0.1 μm or more, preferably 0.3 μm to 5 μm, and more preferably 0.5 μm to 3 μm. The thickness of the adhesive layer is, for example, 3 μm or more, preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

The total thickness of the laminated portion from the polarizing plate 10 to the adhesive layer 60 (including the thickness of the adhesive layer) is, for example, 200 μm or less, preferably 150 μm or less, and for example, 30 μm or more, preferably is 50㎛ or more. The thickness of the laminated portion from the polarizer 10 to the fourth retardation layer 50 (thickness excluding the adhesive layer 60 from the total thickness) is, for example, 100 μm or less, preferably 80 μm or less, and, for example, It is 20㎛ or more, preferably 40㎛ or more.

The polarizing plate 100 with a retardation layer may be sheet-shaped or elongated. In this specification, 'elongated shape' means an elongated shape with a sufficiently long length relative to the width, and includes, for example, an elongated shape with a length of 10 or more times the width, preferably 20 times or more. The long-length laminate can be wound into a roll.

A-2. polarizer

The polarizer 10 includes a polarizer 12, and preferably further includes a protective layer 14 on the side of the polarizer 12 opposite to the side on which the first retardation layer 20 is disposed. If necessary, the polarizing plate 10 may include a protective layer on the side of the polarizer 12 where the first phase difference layer 20 is disposed.

A-2-1. polarizer

The polarizer 12 is typically a resin film containing a dichroic substance (for example, iodine). Examples of the resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene/vinyl acetate copolymer-based partially saponified films.

The thickness of the polarizer is, for example, 18 μm or less, preferably 15 μm or less, more preferably 12 μm or less, and still more preferably 8 μm or less. The thickness of the polarizer is preferably 1 μm or more.

The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 40.0% to 46.0%, preferably 41.0% to 45.0%, and more preferably 41.5% to 44.5%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

The polarizer can be manufactured by any suitable method. Specifically, the polarizer may be produced from a single-layer resin film or may be produced using a laminate containing a base material.

The method of producing a polarizer from the single-layer resin film typically includes subjecting the resin film to dyeing treatment and stretching treatment with a dichroic substance such as iodine or a dichroic dye. As the resin film, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films are used. The method may further include insolubilization treatment, swelling treatment, crosslinking treatment, etc. Since this manufacturing method is well known in the art, detailed description is omitted.

A polarizer obtained using a laminate containing the above-described substrate can be produced, for example, using a laminate of a resin substrate and a resin film or resin layer (typically a PVA-based resin layer). Specifically, applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; It can be produced by stretching and dyeing the laminate and using the PVA-based resin layer as a polarizer. In this embodiment, a PVA-based resin layer containing a halide and a PVA-based resin is preferably formed on one side of the resin substrate. Stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. Additionally, stretching may further include air stretching the laminate at a high temperature (eg, 95°C or higher) before stretching in an aqueous boric acid solution, if necessary. Additionally, in this embodiment, the laminate is preferably subjected to a dry shrink treatment in which the laminate is shrunk by 2% or more in the width direction by heating while being conveyed in the longitudinal direction. Typically, the manufacturing method of this embodiment includes performing aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment, and dry shrink treatment on the laminate in this order. By introducing auxiliary stretching, even in the case of applying PVA on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA and achieve high optical properties. In addition, by increasing the orientation of PVA in advance, problems such as a decrease in the orientation of the PVA or dissolution can be prevented when it is immersed in water in the subsequent dyeing process or stretching process, and high optical properties can be achieved. . In addition, in the case where the PVA-based resin layer is immersed in a liquid, compared to the case where the PVA-based resin layer does not contain a halide, the disruption of the orientation of the PVA molecules and the decrease in orientation can be suppressed, and high optical properties can be achieved. It can be achieved. Additionally, high optical properties can be achieved by shrinking the laminate in the width direction through dry shrinkage treatment. A polarizing plate can be obtained by laminating a protective layer on the peeling surface where the resin substrate is peeled from the obtained laminate of the resin substrate/polarizer, or on the surface opposite to the peeling surface. Details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

A-2-2. protective layer

The protective layer 14 may be formed of any suitable resin film that can be used as a protective layer of a polarizer, for example. Specific examples of the resin that is the main component of the resin film include cellulose-based resins such as triacetylcellulose (TAC), polyester-based resins, polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, Examples include polyethersulfone-based resin, polysulfone-based resin, polystyrene-based resin, cycloolefin-based resin such as polynorbornene, polyolefin-based resin, (meth)acrylic-based resin, and acetate-based resin.

The polarizing plate 100 with a retardation layer is typically placed on the viewer's side of the image display device, and the protective layer 14 is placed on the viewer's side. Therefore, the protective layer 14 may be subjected to surface treatment such as hard coat (HC) treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as necessary.

The thickness of the protective layer is, for example, 5 μm to 80 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm. In addition, when the above surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

A-3. First phase contrast layer

The first phase difference layer 20 is a so-called positive C plate whose refractive index characteristics exhibit the relationship nz>nx=ny. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane phase difference Re(550) of the first phase difference layer may be less than 10 nm.

The thickness direction retardation Rth (550) of the first phase difference layer is, for example, -10 nm to -120 nm, preferably -10 nm to -100 nm, more preferably -10 nm to -70 nm, even more preferably -20 nm to - It is 60nm.

The first retardation layer preferably has a stab elastic modulus of 50 g/mm or more, more preferably 52 g/mm or more, and still more preferably 55 g/mm or more. The puncture elastic modulus of the first phase contrast layer is, for example, 200 g/mm or less. When the stab elastic modulus of the first retardation layer is in the above range, dimensional changes in the second retardation layer (for example, expansion and contraction of the second retardation layer composed of a stretched film of a resin film) can be appropriately suppressed. In this specification, the stabbing elastic modulus refers to the force (g) just before the retardation film is fractured (or torn) when a needle (piercing jig) is pierced perpendicularly to the main surface of the retardation film (e.g., the first retardation layer). , refers to the value divided by the deformation (mm) at that time. As a needle, a needle with a tip diameter of 1 mmϕ and 0.5R can be used. The needle piercing speed can be set to 0.33 cm/sec. Measurement of the prick elastic modulus can be performed by sandwiching a retardation film between two plates with circular holes of 15 mm or less in diameter (for example, 11 mm in diameter) through which a needle can pass. Measurement of the stab elastic modulus can be performed in an environment with a temperature of 23°C. For example, the stabbing elasticity modulus can be measured for five retardation films, and the average value can be taken as the stabbing elasticity modulus of the retardation film. A commercially available device can be used to measure the stab elastic modulus. Commercially available devices include the handy compression tester "KES-G5 Needle Penetration Force Measurement Specification" manufactured by Katotech Co., Ltd. and the small tabletop tester "EZ Test" manufactured by Shimadzu Seisakusho Co., Ltd.

The first phase difference layer is formed of any suitable material. In one embodiment, the first retardation layer is comprised of a resin film. In another embodiment, the first retardation layer is comprised of an alignment solidification layer of a liquid crystal compound.

Representative materials for the resin film constituting the first retardation layer include resin materials having negative birefringence. A resin having negative birefringence is a resin that exhibits the property of maximizing the refractive index in a direction perpendicular to the stretching direction when uniaxially stretched. Examples of resins having negative birefringence include resins in which chemical bonds or functional groups with high polarization anisotropy, such as aromatic rings or carbonyl groups, are introduced into the side chains. Specific examples of resins having negative birefringence include acrylic resins, styrene-based resins, maleimide-based resins, modified polyolefin-based resins, and fumaric acid ester-based resins. The above resin materials can be used individually or in combination of two or more types.

The acrylic resin can be obtained, for example, by addition polymerizing an acrylate monomer. Examples of the acrylic resin include polymethyl methacrylate (PMMA), polybutyl methacrylate, and polycyclohexyl methacrylate.

The styrene-based resin can be obtained, for example, by addition polymerizing a styrene-based monomer. As styrene-based monomers, for example, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, 2 , 5-dichlorostyrene, p-t-butylstyrene, etc.

The maleimide-based resin can be obtained, for example, by addition polymerizing a maleimide-based monomer. As maleimide monomers, for example, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N- (2-propylphenyl)maleimide, N-(2-isopropylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-dipropylphenyl)maleimide, N- (2,6-diisopropylphenyl)maleimide, N-(2-methyl-6-ethylphenyl)maleimide, N-(2-chlorophenyl)maleimide, N-(2,6-dichlorophenyl)maleimide Mead, N-(2-bromophenyl)maleimide, N-(2,6-dibromophenyl)maleimide, N-(2-biphenyl)maleimide, N-(2-cyanophenyl)maleimide Mead, etc. may be mentioned. Maleimide-based monomers can be obtained from, for example, Tokyo Kasei Kogyo Co., Ltd.

In the above addition polymerization, the birefringence characteristics of the resulting resin can also be controlled by substituting the side chain after polymerization, maleimidation, grafting, etc.

The resin having the negative birefringence may be copolymerized with other monomers. By copolymerizing other monomers, brittleness, moldability, and heat resistance can be improved. Examples of the other monomers include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, and 1-hexene; acrylonitrile; (meth)acrylates such as methyl acrylate and methyl methacrylate; maleic anhydride; and vinyl esters such as vinyl acetate.

When the resin having the negative birefringence is a copolymer of the styrene monomer and the other monomer, the mixing ratio of the styrene monomer is preferably 50 mol% to 80 mol%. When the resin having the negative birefringence is a copolymer of the maleimide monomer and the other monomer, the mixing ratio of the maleimide monomer is preferably 2 mol% to 50 mol%. By mixing within this range, a resin film excellent in toughness and molding processability can be obtained.

The resin having negative birefringence is preferably styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-(meth)acrylate copolymer, styrene-maleimide copolymer, and vinyl ester-maleimide. Copolymers, olefin-maleimide copolymers, etc. are used. These can be used individually or in combination of two or more types. These resins exhibit high negative birefringence and may also have excellent heat resistance. These resins can be obtained from, for example, Nova Chemical Japan or Arakawa Chemical Engineering Co., Ltd.

As the resin having the negative birefringence, a polymer having a repeating unit represented by the following general formula (I) is also preferably used. Such polymers exhibit even higher negative birefringence and can also have excellent heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using an N-phenyl substituted maleimide in which a phenyl group having a substituent at least in the ortho position is introduced as the N substituent of the maleimide monomer as the starting material.

In the general formula (I), R _{1 to} R ₅ each independently represent hydrogen, a halogen atom, carboxylic acid, carboxylic acid ester, hydroxyl group, nitro group, or a straight-chain or branched alkyl group having 1 to 8 carbon atoms. Or represents an alkoxy group (however, R ₁ and R ₅ are not hydrogen atoms at the same time), R ₆ and R ₇ represent hydrogen or a straight-chain or branched alkyl group or alkoxy group having 1 to 8 carbon atoms, and n is an integer of 2 or more. represents.

The resin having negative birefringence is not limited to the above, and for example, resins having negative birefringence described in Japanese Patent Application Publication No. 2008-544304, Japanese Patent Application Publication No. 2008-544317, etc. can be used.

The resin film forming the first retardation layer may further contain any appropriate additives as needed. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. The type and content of additives can be appropriately set depending on the purpose. The content of the additive in the resin film is, for example, about 3% by weight to 10% by weight.

As a manufacturing method for the first retardation layer comprised of the resin film, any suitable manufacturing method can be used. In one embodiment, the resin film containing the above resin material can be used as a first retardation layer as it is after film formation (i.e., in an unstretched state). For example, when forming a film using a solution film forming method using a resin solution containing the above resin material, stress is generated due to volumetric shrinkage when the resin solution is dried on the support, and the polymer molecular chains tend to orient in the in-plane direction. there is. Therefore, by using a resin material that exhibits high birefringence and has a negative intrinsic birefringence, a coating film having a large birefringence in the thickness direction can be formed on the support due to the shrinkage effect during drying, and the coating film can be formed as a positive film as is. It can be used as a C plate.

The thickness of the first retardation layer, which is a resin film, is, for example, 1 μm to 40 μm, preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

The alignment-fixed layer of the liquid crystal compound is a layer in which the liquid crystal compound is oriented in a predetermined direction within the layer, and its orientation state is fixed. Additionally, the 'alignment solidified layer' is a concept that includes an alignment hardened layer obtained by curing a liquid crystal monomer. As the alignment-fixed layer of the liquid crystal compound constituting the first retardation layer, an alignment-fixed layer of a liquid crystal material fixed in homeotropic alignment can be preferably exemplified. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642.

The thickness of the first retardation layer, which is the alignment solidification layer of the liquid crystal compound, is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and still more preferably 0.5 μm to 5 μm.

A-4. Second phase difference layer

The second retardation layer 30 has a refractive index characteristic of nx>ny≥nz. In one embodiment, the second retardation layer can function as a λ/2 plate. The in-plane retardation Re(550) of the second retardation layer is, for example, 200 nm to 300 nm, preferably 220 nm to 290 nm, and more preferably 230 nm to 280 nm. Additionally, here, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny < nz, within a range that does not impair the effect of the present invention.

The Nz coefficient of the second phase difference layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, further preferably 0.9 to 1.5, particularly preferably 0.9 to 1.3. By satisfying this relationship, when the obtained polarizing plate with a retardation layer is used in an image display device, very excellent reflected color can be achieved.

The second retardation layer is arranged so that its slow axis forms an angle with the absorption axis of the polarizer 12 of, for example, 5° to 25°, preferably 10° to 20°, and more preferably about 15°. By having such a configuration, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (as a result, very excellent anti-reflection characteristics) can be obtained.

The second phase difference layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases as the wavelength of the measurement light increases, or may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases as the wavelength of the measurement light increases. , the phase difference value may exhibit flat wavelength dispersion characteristics that hardly change depending on the wavelength of the measurement light. In one embodiment, the second retardation layer exhibits inverse dispersion wavelength characteristics. In this case, Re(450)/Re(550) of the second phase difference layer is, for example, 0.8 or more and less than 1, and is preferably 0.8 or more and 0.95 or less. With this configuration, very excellent anti-reflection properties can be achieved.

In one embodiment, the second retardation layer has an absolute value of the photoelastic coefficient of preferably 2×10 ^-11 m ² /N or less, more preferably 2.0×10 ^-13 m ² /N to 1.5×10 ^- It contains a resin of ¹¹ m ² /N, more preferably 1.0 × 10 ^-12 m ² /N to 1.2 × ^{10 -11} m ² /N. If the absolute value of the photoelastic coefficient is in this range, it is difficult for a phase difference change to occur when shrinkage stress occurs during heating. As a result, thermal unevenness in the resulting image display device can be well prevented.

The second phase difference layer is formed of any suitable material that can satisfy the above characteristics. The second retardation layer is composed of, for example, a resin film or an alignment-fixed layer of a liquid crystal compound.

Resins contained in the resin film include polycarbonate-based resin, polyestercarbonate-based resin, polyester-based resin, polyvinyl acetal-based resin, polyarylate-based resin, cycloolefin-based resin, cellulose-based resin, and polyvinyl alcohol-based resin. , polyamide-based resin, polyimide-based resin, polyether-based resin, polystyrene-based resin, acrylic resin, etc. These resins may be used individually or in combination (e.g., blend, copolymerization). When the second retardation layer exhibits reverse dispersion wavelength characteristics, a resin film containing polycarbonate-based resin or polyestercarbonate-based resin (hereinafter sometimes simply referred to as polycarbonate-based resin) can be suitably used. When the second retardation layer exhibits flat wavelength dispersion characteristics, a resin film containing a cycloolefin-based resin can be suitably used.

As the polycarbonate-based resin, any appropriate polycarbonate-based resin can be used as long as the effect of the present invention is obtained. For example, the polycarbonate resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri, or It contains structural units derived from at least one dihydroxy compound selected from the group consisting of polyethylene glycol, alkylene glycol, or spiroglycol. Preferably, 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, a structural unit derived from alicyclic dimethanol, and/or Contains structural units derived from di, tri or polyethylene glycol; More preferably, it contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol. The polycarbonate-based resin may, if necessary, contain structural units derived from other dihydroxy compounds. In addition, details of polycarbonate-based resins that can be suitably used in the second retardation layer are given, for example, in Japanese Patent Laid-Open Nos. 2014-10291, Japanese Patent Laid-Open Nos. 2014-26266, and Japanese Patent Laid-Open Nos. 2015-2015. It is described in Japanese Patent Application Publication No. 212816, Japanese Patent Application Publication No. 2015-212817, and Japanese Patent Application Publication No. 2015-212818, and the descriptions of these publications are incorporated herein by reference.

The cycloolefin-based resin is a general term for resins polymerized using cycloolefin as a polymerization unit, for example, Japanese Patent Application Laid-Open No. 1-240517, Japanese Patent Application Publication No. 3-14882, and Japanese Patent Application Publication No. 3- Resins described in No. 122137 and the like can be mentioned. Specific examples include ring-opening (co)polymers of cycloolefins, addition polymers of cycloolefins, copolymers of cycloolefins and α-olefins such as ethylene and propylene (typically random copolymers), and these in combination with unsaturated carboxylic acids or their Examples include graft modified products modified with derivatives and their hydrides. Specific examples of cycloolefins include norbornene-based monomers. Norbornene-based monomers include, for example, norbornene and its alkyl and/or alkylidene substituents, such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5 -Butyl-2-norbornene, 5-ethylidene-2-norbornene, etc., and polar group substituents such as these halogens; Dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc.; Dimethanooctahydronaphthalene, its alkyl and/or alkylidene substituents, and polar group substituents such as halogen, such as 6-methyl-1,4:5,8-dimethano-1,4,4a,5,6 ,7,8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethyl Liden-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethano- 1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4:5,8-dimethano-1,4,4a,5,6,7,8 ,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl -1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, etc.; Tri-tetramers of cyclopentadiene, such as 4,9:5,8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene, 4, 11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentaanthracene, etc. You can.

Other cycloolefins capable of ring-opening polymerization can be used together within the range that does not impair the purpose of the present invention. Specific examples of such cycloolefins include compounds having one reactive double bond, such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

The cycloolefin resin preferably has a number average molecular weight (Mn) of 25,000 to 200,000, more preferably 30,000 to 100,000, as measured by gel permeation chromatography (GPC) using a toluene solvent. Preferably it is 40,000 to 80,000. If the number average molecular weight is within the above range, a resin film with excellent mechanical strength and excellent solubility, moldability, and flexibility in casting can be obtained.

When the cycloolefin resin is obtained by hydrogenating a ring-opening polymer of norbornene monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. am. Within this range, heat deterioration resistance, light deterioration resistance, etc. are excellent.

Various products of the cycloolefin-based resin are commercially available. Specific examples include the brand names 'Zeonex' and 'Zeonoa' manufactured by Zeon, Japan, the brand names 'Arton' manufactured by JSR, the brand names 'Topas' manufactured by Ticona, and Mitsui Kaga. One example is the brand name 'APEL' manufactured by KUSA.

The second retardation layer can be obtained, for example, by stretching the unstretched resin film. In stretching, any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) can be employed. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end shrinking, and fixed end shrinking may be used singly, simultaneously, or sequentially. Regarding the stretching direction, it can be carried out in various directions or dimensions, such as the longitudinal direction, the width direction, the thickness direction, and the oblique direction. The stretching temperature is preferably Tg-30°C to Tg+60°C, more preferably Tg-10°C to Tg+50°C, relative to the glass transition temperature (Tg) of the resin film.

By appropriately selecting the stretching method and stretching conditions, a resin film having the desired optical properties (eg, refractive index properties, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, the second retardation layer is produced by uniaxial stretching or fixed-end uniaxial stretching of the unstretched resin film. A specific example of fixed-end uniaxial stretching includes a method of stretching the resin film in the width direction (transverse direction) while running it in the longitudinal direction. The stretching ratio is preferably 1.1 to 3.5 times.

The thickness of the second retardation layer, which is a stretched film of the resin film, is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and still more preferably 20 μm to 50 μm. am.

In the second retardation layer composed of an orientation-solidified layer of a liquid crystal compound, typically, rod-shaped liquid crystal compounds are aligned in a state in which they are aligned in the slow axis direction of the second retardation layer (homogeneous orientation). Examples of rod-shaped liquid crystal compounds include liquid crystal polymer and liquid crystal monomer. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by polymerizing the liquid crystal compound after aligning it.

The alignment-fixed layer of the liquid crystal compound (liquid crystal alignment-fixed layer) is formed by subjecting the surface of a predetermined substrate to an orientation treatment, coating the surface with a coating solution containing the liquid crystal compound, and applying the liquid crystal compound to the alignment treatment. It can be formed by orienting in a direction and fixing the orientation state. As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. The treatment conditions for various orientation treatments may be any appropriate conditions depending on the purpose.

The alignment of the liquid crystal compound is achieved by treatment at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned in accordance with the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to polymerization treatment or crosslinking treatment.

As the liquid crystal compound, any suitable liquid crystal polymer and/or liquid crystal monomer can be used. The liquid crystal polymer and liquid crystal monomer may be used individually or in combination. Specific examples of the liquid crystal compound and the manufacturing method of the liquid crystal alignment solidification layer are described in, for example, Japanese Patent Application Laid-Open No. 2006-163343, Japanese Patent Application Publication No. 2006-178389, and International Publication No. 2018/123551. The descriptions of these publications are incorporated herein by reference.

The thickness of the second retardation layer, which is a liquid crystal alignment solidification layer, is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and still more preferably 1 μm to 4 μm. .

A-5. Third phase difference layer

The third retardation layer 40 has a refractive index characteristic of nx>ny≥nz. In one embodiment, the third retardation layer can function as a λ/4 plate. The in-plane retardation Re(550) of the third retardation layer is, for example, 120 nm to 170 nm, preferably 130 nm to 160 nm, and more preferably 140 nm to 150 nm. Additionally, here, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny < nz, within a range that does not impair the effect of the present invention.

The Nz coefficient of the third phase difference layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, further preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. By satisfying this relationship, when the obtained polarizing plate with a retardation layer is used in an image display device, very excellent reflected color can be achieved.

The third retardation layer is arranged so that its slow axis forms an angle with the absorption axis of the polarizer 12, for example, 65° to 85°, preferably 70° to 80°, and more preferably about 75°. The angle formed by the slow axis of the third retardation layer and the slow axis of the second retardation layer is, for example, 50° to 70°, preferably 55° to 65°, and more preferably about 60°. By having such a configuration, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (as a result, very excellent anti-reflection characteristics) can be obtained.

The third phase difference layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases as the wavelength of the measurement light increases, or may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases as the wavelength of the measurement light increases. It may exhibit flat wavelength dispersion characteristics that hardly change depending on the wavelength of the measurement light. In one embodiment, the third retardation layer exhibits inverse dispersion wavelength characteristics. In this case, Re(450)/Re(550) of the third phase difference layer is, for example, 0.8 or more and less than 1, and is preferably 0.8 or more and 0.95 or less. With this configuration, very excellent anti-reflection properties can be achieved.

In one embodiment, the third retardation layer has an absolute value of the photoelastic coefficient of preferably 2×10 ^-11 m ² /N or less, more preferably 2.0×10 ^-13 m ² /N to 1.5×10 ^- It contains a resin of ¹¹ m ² /N, more preferably 1.0 × 10 ^-12 m ² /N to 1.2 × ^{10 -11} m ² /N. If the absolute value of the photoelastic coefficient is in this range, it is difficult for a phase difference change to occur when shrinkage stress occurs during heating. As a result, thermal unevenness in the resulting image display device can be well prevented.

The third phase difference layer is formed of any suitable material that can satisfy the above characteristics. The third phase difference layer is composed of, for example, a resin film or an alignment solidification layer of a liquid crystal compound.

Examples of the resin contained in the resin film include the same resin as the resin contained in the resin film constituting the second phase difference layer. The third phase difference layer can be obtained, for example, by stretching an unstretched resin film. As described with respect to the second phase difference layer, any appropriate stretching method and stretching conditions (e.g., stretching temperature, stretching ratio, stretching direction) can be employed in stretching. By appropriately selecting the stretching method and stretching conditions, a resin film having the desired optical properties (eg, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained.

The thickness of the third retardation layer, which is a stretched film of the resin film, is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and still more preferably 20 μm to 50 μm. am.

As the liquid crystal compound contained in the alignment-fixed layer of the liquid crystal compound, any suitable liquid crystal polymer and/or liquid crystal monomer can be used. Specifically, a liquid crystal compound similar to the liquid crystal compound contained in the liquid crystal alignment solidification layer constituting the second phase contrast layer can be exemplified, and its production method is as described above.

The thickness of the third retardation layer, which is a liquid crystal alignment solidification layer, is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and still more preferably 1 μm to 4 μm. .

A-6. Fourth phase difference layer

The fourth phase difference layer 50 is a so-called positive C plate whose refractive index characteristics exhibit the relationship nz>nx=ny. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane phase difference Re(550) of the fourth phase difference layer may be less than 10 nm.

The thickness direction retardation Rth (550) of the fourth phase difference layer is, for example, -10 nm to -120 nm, preferably -30 nm to -110 nm, more preferably -50 nm to -110 nm, even more preferably -60 nm to -100 nm. am. In one embodiment, the sum of Rth (550) of the first phase difference layer and the fourth phase difference layer is, for example, -50 nm to -240 nm, preferably -60 nm to -220 nm.

The fourth retardation layer preferably has a stab elastic modulus of 50 g/mm or more, more preferably 52 g/mm or more, and still more preferably 55 g/mm or more. The puncture elastic modulus of the fourth phase contrast layer is, for example, 200 g/mm or less. When the puncture elastic modulus of the fourth retardation layer is in the above range, dimensional changes in the third retardation layer (for example, expansion and contraction of the third retardation layer composed of a stretched film of a resin film) can be appropriately suppressed.

The fourth phase difference layer is formed of any suitable material. In one embodiment, the fourth retardation layer is comprised of a resin film. In another embodiment, the fourth retardation layer is comprised of an alignment solidification layer of a liquid crystal compound.

As a material for the resin film constituting the fourth retardation layer, the same resin material as that for the resin film constituting the first retardation layer can be used. For example, by adjusting the thickness of the resin film, a fourth retardation layer having a desired thickness direction retardation can be obtained.

The thickness of the fourth retardation layer, which is a resin film, is, for example, 1 μm to 40 μm, preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

As the alignment-fixed layer of the liquid crystal compound constituting the fourth phase contrast layer and its forming method, the alignment-fixed layer of the liquid crystal compound constituting the first phase contrast layer and its forming method can be similarly applied. Additionally, the first phase difference layer and the fourth phase difference layer may be made of the same material or may be made of different materials. For example, one side may be comprised of a resin film, and the other may be comprised of a liquid crystal alignment solidification layer. The first retardation layer comprised of a resin film can also function as a protective layer of the polarizer when the protective layer on the first retardation layer side of the polarizer is omitted.

The thickness of the fourth retardation layer, which is an alignment solidification layer of the liquid crystal compound, is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and still more preferably 0.5 μm to 5 μm.

A-7. adhesive layer

The adhesive layer 60 is provided on the side of the fourth retardation layer 50 opposite to the side where the third retardation layer 40 is disposed. As described above, the polarizing plate 100 with a retardation layer can be bonded to a member such as an organic EL panel through the adhesive layer 60.

The adhesive layer 60 may be made of any suitable adhesive. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and mixing ratio of monomers forming the base resin of the adhesive, the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive having desired properties according to the purpose can be prepared. The base resin of the adhesive may be used individually, or may be used in combination of two or more types. As the base resin, acrylic resin is preferably used. Specifically, the adhesive layer is preferably composed of an acrylic adhesive.

The adhesive layer can be formed by applying and drying an adhesive composition containing additives such as a base resin and a crosslinking agent, and a solvent. For example, the adhesive layer can be formed by directly applying the adhesive composition to the adherend. Also, for example, the adhesive composition can be applied to a separately prepared substrate such as a base film to form an adhesive layer, which can then be transferred to the adherend. Drying is typically performed by heating.

The thickness of the adhesive layer is, for example, 5 μm or more, preferably 10 μm or more, for example, 100 μm or less, preferably 80 μm or less.

A-8. release liner

Examples of the release liner include flexible plastic films. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. The thickness of the release liner is, for example, 3 μm or more and, for example, is 200 μm or less. The surface of the release liner is coated with a release agent. Specific examples of the release agent include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.

B. Image display device

The polarizing plate with a retardation layer described in item A is typically applied to an image display device, preferably an image display device including a metal layer, and more preferably an organic electroluminescence (organic EL) display device. . Therefore, the image display device according to the embodiment of the present invention is provided with the above-described polarizing plate with a retardation layer. The organic EL display device according to an embodiment of the present invention typically includes an organic EL panel and the polarizing plate with a retardation layer disposed on the viewer's side.

The organic EL display device 200 illustrated in FIG. 2 includes an organic EL panel 120 and a polarizing plate 100 with a retardation layer disposed on the viewer side thereof. The polarizing plate 100 with a retardation layer is arranged so that the first retardation layer 20 is closer to the organic EL panel 120 than the polarizer 12, and is bonded to the organic EL panel 120 with an adhesive layer 60. there is. The organic EL panel 120 includes metal members (e.g., electrodes, sensors, wiring, metal layers), but since the polarizer 100 with a retardation layer has excellent anti-reflection characteristics, reflection caused by the metal members is prevented. It can be prevented appropriately.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, various measurement methods are as follows. Additionally, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on weight.

1. Thickness

The thickness of 1㎛ or less was measured using a scanning electron microscope (manufactured by Nippon Electronics, product name 'JSM-7100F'). Thickness exceeding 1㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

2. In-plane phase difference Re(λ) and thickness direction phase difference Rth(λ)

Using a Muller matrix polarimeter (manufactured by Axometrics, product name 'Axoscan'), the in-plane phase difference and thickness direction phase difference at each wavelength were measured at 23°C.

3. Refractive index

The average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive index (nx, ny, nz) was calculated from the phase difference value.

4. Group transmittance and polarization

Using a spectrophotometer (manufactured by Otsuka Electronics, 'LPF-200'), the single transmittance (Ts), parallel transmittance (Tp), and orthogonal transmittance (Tc) of the polarizer were measured. These Ts, Tp, and Tc are Y values measured with a 2-degree field of view (C light source) according to JIS Z8701 and subjected to visibility correction. From the obtained Tp and Tc, the polarization degree of the polarizing plate (polarizer) was determined using the following formula.

Polarization degree (%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

[Manufacture Example 1: Production of polarizer (A)]

(Production of polarizer)

As a thermoplastic resin substrate, an amorphous isophthalic copolymerization polyethylene terephthalate film (thickness 100 μm), which is long and has a Tg of about 75°C, was used, and corona treatment was performed on one side of the resin substrate.

100 parts by weight of PVA-based resin mixed with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Company, brand name 'Gosenex Z410') at a ratio of 9:1, and 13 parts by weight of potassium iodide. The added product was dissolved in water to prepare a PVA aqueous solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air auxiliary stretching treatment).

Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, the final single transmittance (Ts) of the polarizer obtained is the desired value. It was immersed for 60 seconds while adjusting the concentration to achieve this (dyeing treatment).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, and the total stretching ratio was adjusted in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed to increase the size by 5.5 times (underwater stretching treatment).

After that, the laminate was immersed in a washing bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment).

Afterwards, it was dried in an oven maintained at about 90°C and brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75°C (dry shrink treatment).

In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

(Production of polarizer (A))

An HC-TAC film was bonded as a protective layer to the surface of the obtained polarizer (the side opposite to the resin substrate) through an ultraviolet curing adhesive. Specifically, the ultraviolet curing adhesive was applied to a thickness of 1.0 μm and bonded using a roll machine. Afterwards, UV rays were irradiated from the protective layer side to cure the adhesive. In addition, the HC-TAC film is a film in which a hard coat (HC) layer (7 μm thick) is formed on a triacetylcellulose (TAC) film (25 μm thick), and the TAC film is bonded to the polarizer side. Next, the resin substrate was peeled and removed to obtain a polarizing plate (A) having the structure of [polarizer/TAC protective layer with HC]. The single transmittance of the polarizer (A) was 43% and the polarization degree was 99.9%.

[Production Example 2A: Production of positive C plate (A)]

In an autoclave equipped with a stirrer, cooling tube, nitrogen introduction tube, and thermometer, 48 parts by weight of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical, brand name: Metrose 60SH-50), 15601 parts by weight of distilled water, and diisopropyl fumarate. Add 8161 parts by weight, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of t-butylperoxypivalate as a polymerization initiator, nitrogen bubbling was performed for 1 hour, and then stirred at 49°C for 24 hours. maintained, and radical suspension polymerization was performed. It was then cooled to room temperature, and the suspension containing the resulting polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure. The obtained fumaric acid ester-based resin was dissolved in a toluene/methyl ethyl ketone mixed solution (toluene/methyl ethyl ketone, 50% by weight/50% by weight) to make a 20% solution. Additionally, 5 parts by weight of tributyl trimellitate was added as a plasticizer to 100 parts by weight of fumaric acid ester resin to prepare dope. As a support film, a biaxially stretched film (75 μm thick) of polyester (polyethylene-terephthalate/isophthalate copolymer) was used. The dope adjusted to the support film was applied so that the film thickness after drying was 8 μm, and dried at 140°C. As a result, a resin film (positive C plate (A)) exhibiting refractive index characteristics of nz>nx=ny was obtained. The thickness of the positive C plate (A) was 8㎛, the in-plane retardation Re(550) ≒0nm, and the thickness direction retardation Rth(550) was -40nm.

[Production Example 2B: Production of positive C plate (B)]

A resin film (positive C plate (B)) exhibiting refractive index characteristics of nz>nx=ny was obtained in the same manner as in Production Example 2A except that the coating thickness of the resin solution was changed. The thickness of the positive C plate (B) was 17㎛, the in-plane retardation Re(550) ≒0nm, and the thickness direction retardation Rth(550) was -80nm.

[Production Example 2C: Production of positive C plate (C)]

A resin film (positive C plate (C)) exhibiting refractive index characteristics of nz>nx=ny was obtained in the same manner as in Production Example 2A except that the coating thickness of the resin solution was changed. The thickness of the positive C plate (C) was 26㎛, the in-plane retardation Re(550) ≒0nm, and the thickness direction retardation Rth(550) was -120nm.

[Manufacture Example 3: Production of λ/2 plate (A) (second phase difference layer)]

10 g of a polymerizable liquid crystal displaying a nematic liquid crystalline phase (manufactured by BASF, brand name 'Paliocolor LC242', expressed in the formula below), and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name ' 3 g of Ilgacure 907') was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness 38㎛) was rubbed using a rubbing cloth, and orientation treatment was performed. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer when bonding to the polarizing plate. The liquid crystal coating liquid was applied to this alignment treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer formed in this way was irradiated with light of 1 mJ/cm2 using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal alignment solidification layer (λ/2 plate (A)) on the PET film. The thickness of the λ/2 plate (A) was 2.5 μm, and the in-plane retardation Re(550) was 270 nm. Additionally, the λ/2 plate (A) exhibited refractive index characteristics of nx>ny=nz.

[Manufacture Example 4: Production of λ/4 plate (A) (third phase difference layer)]

Except that the coating thickness was changed and the orientation treatment direction was set to 75° when viewed from the viewing side with respect to the direction of the absorption axis of the polarizer, a liquid crystal alignment solidification layer (λ/4 plate) was prepared in the same manner as in Production Example 3 on the PET film. (A)) was formed. The thickness of the λ/4 plate (A) was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. Additionally, the λ/4 plate (A) exhibited refractive index characteristics of nx>ny=nz.

[Manufacture Example 5: Production of adhesive layer (A)]

A monomer containing 91.5 parts of butylacrylate, 3 parts of acrylic acid, 0.5 parts of 4-hydroxybutylacrylate, and 5 parts of acryloyl morpholine in a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser. The mixture was added. Additionally, for 100 parts of this monomer mixture, 0.1 part of 2,2'-azobisisobutyronitrile was added along with 100 parts of ethyl acetate as a polymerization initiator, and nitrogen gas was introduced while gently stirring to purge the flask with nitrogen. , the liquid temperature in the flask was maintained at around 55°C and polymerization reaction was performed for 8 hours. Next, ethyl acetate was added to the obtained reaction liquid to adjust the solid concentration to 12% by weight, and a solution of an acrylic polymer with a weight average molecular weight (Mw) of 2.5 million was prepared.

With respect to 100 parts of solid content of the obtained acrylic polymer solution, 0.3 parts of benzoyl peroxide of peroxide-based crosslinking agent (product name: Kniper BMT, manufactured by Nippon Yushi Co., Ltd.) and trimethylolpropane/tolylene diisocyanate adduct (product name: Coronate L, Tosoh) An acrylic adhesive was prepared by mixing 0.2 part of the silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) with 0.2 part of the silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.).

The obtained acrylic adhesive was applied to the peeling surface of a 38-μm-thick PET film (MRF38, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.), which is a release liner whose peeling surface was treated with silicone, and dried to form an adhesive layer with a thickness of 20 μm. (A) was formed.

[Example 1]

The positive C plate (A) is bonded to the polarizer side of the polarizer (A) as a first retardation layer, and then the λ/2 plate (A) and the second retardation layer are bonded on the positive C plate (A). 3 As a phase difference layer, the above λ/4 plate (A) was transferred from PET film in this order. At this time, the slow axis of the λ/2 plate (A) and the slow axis of the λ/4 plate (A) are transferred ( bonding) was performed. The positive C plate (A) was bonded to the λ/4 plate (A) side of the obtained laminate as a fourth retardation layer. Each retardation layer was bonded through an ultraviolet curing adhesive (approximately 1 μm thick).

The adhesive layer (A) was bonded to the positive C plate (A) side of the obtained laminate with a release liner, and [polarizing plate (A)/positive C plate (A)/λ/2 plate (A)/λ/4 plate] (A)/positive C plate (A)/adhesive layer (A)/release liner] was obtained.

[Examples 2 to 9, Comparative Examples 1 to 7]

Polarizing plates with a retardation layer of Examples 2 to 9 were obtained in the same manner as in Example 1 except that different combinations selected from positive C plates (A to C) were used as the first and fourth retardation layers. In addition, Example 1 except that both the first and fourth retardation layers were not used, or only one of the first and fourth retardation layers selected from positive C plates (A to C) was used. In the same manner as above, polarizing plates with a retardation layer of Comparative Examples 1 to 7 were obtained.

Table 1 shows the combinations of positive C plates (A to C) used in the polarizing plates with a retardation layer obtained in the examples and comparative examples.

[Table 1]

<Reflection color evaluation>

The organic EL display device (manufactured by Samsung, product number 'Galaxy A41') was disassembled and the organic EL panel was taken out. The release liner was peeled from the polarizing plate with a retardation layer obtained in the examples and comparative examples, and the exposed adhesive layer (A) was bonded to the organic EL panel to prepare a measurement sample. Using a display measurement system (manufactured by Konica Minolta, 'DMS505'), light is irradiated from the polarizer (A) side of the measurement sample, azimuth angle: 0° to 360° (15° intervals), polar angle: L at 45°. ^* a ^* b ^* values (SCE method) were measured. Using the obtained L ^* a ^* b ^* values, the reflection color ΔE00 was calculated using the following equations (1) to (7). The maximum value of ΔE00 obtained in each measurement is shown in Table 2. Additionally, the smaller the value of ΔE00, the smaller the coloring due to reflection, and the better the reflected color.

(1) C ^* =√(a ^* ^2+b ^* ^2)

(2) G=0.5×(1-√((C ^* /2)^7/((C ^* /2)^7+25^7)))

(3) a'=a ^* (1+G)

(4) C'=√(a'^2+b ^* ^2)

(5) SL=1+0.015×(L ^* /2-50)^2/√(20+(L ^* /2-50)^2)

(6) SC=1+0.045×C’/2

(7)ΔE00=√((L ^* /SL)^2+(C'/SC)^2)

[Table 2]

As shown in Table 2, for a polarizing plate with a retardation layer including a polarizer, a λ/2 plate, and a λ/4 plate in this order, there is a gap between the polarizer and the λ/2 plate or between the λ/2 plate and the λ/4 plate. By placing one positive C plate on the side opposite to the side on which it is placed, coloring of the reflection color can be suppressed, and the configuration of [polarizer/positive C plate/λ/2 plate/λ/4 plate/positive C plate] By arranging an additional positive C plate as much as possible, a reflected color with coloring more appropriately suppressed can be realized.

[Industrial applicability]

The polarizing plate with a retardation layer according to an embodiment of the present invention can be used, for example, in an image display device. Representative image display devices include liquid crystal display devices, organic EL display devices, and inorganic EL display devices, and organic EL display devices are preferred.

10: Polarizer
12: Polarizer
14: protective layer
20: first phase contrast layer
30: second phase contrast layer
40: Third phase difference layer
50: fourth phase difference layer
60: Adhesive layer
100: Polarizer with phase contrast layer
200: Organic EL display device

Claims (6)

It includes a polarizing plate including a polarizer, a first phase difference layer, a second phase difference layer, a third phase difference layer, and a fourth phase difference layer in this order,
The second retardation layer and the third retardation layer have refractive index characteristics of nx>ny≥nz,
The first retardation layer and the fourth retardation layer have refractive index characteristics of nz>nx=ny,
The second phase difference layer has Re (550) of 200 nm to 300 nm,
The third phase difference layer has Re (550) of 120 nm to 170 nm,
The angle between the slow axis of the second retardation layer and the absorption axis of the polarizer is 5° to 25°,
The angle between the slow axis of the third retardation layer and the absorption axis of the polarizer is 65° to 85°,
Polarizer with phase contrast layer. According to paragraph 1,
A polarizing plate with a retardation layer, wherein Rth (550) of the fourth retardation layer is -50 nm to -110 nm. According to paragraph 1,
A polarizing plate with a retardation layer, wherein Rth (550) of the first retardation layer is -10 nm to -70 nm. According to paragraph 1,
Rth (550) of the first phase difference layer is -10nm to -70nm,
A polarizing plate with a retardation layer, wherein Rth (550) of the fourth retardation layer is -50 nm to -110 nm. According to paragraph 1,
A polarizing plate with a retardation layer used in an organic EL display device. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 5.