TW202115436A - Set of polarizing plates, and image display device including said set - Google Patents

Abstract

Provided is a set of polarizing plates in which the deviation of the through-hole portion in each polarizing plate is low, and the difference between the deviation amount of a viewing-side polarizing plate and the deviation amount of a rear surface-side polarizing plate is extremely small. This set of polarizing plates comprises a rectangular first polarizing plate disposed on the viewing side of an image display cell, and a rectangular second polarizing plate disposed on the rear surface side. The first polarizing plate has a first polarizer, a protective layer disposed on at least one side thereof, and a first adhesive layer disposed on the image display cell side. The second polarizing plate has a second polarizer, a protective layer disposed on at least one side thereof, a reflective polarizer disposed on the side of the second polarizer opposite to the image display cell, and a second adhesive layer disposed on the image display cell side. The thicknesses of the first polarizer and the second polarizer are each 20 [mu]m or less. The absorption axis of the first polarizer is in the short-side direction, and the absorption axis of the second polarizer is in the long-side direction. The first polarizing plate and the second polarizing plate each have a through-hole in the end thereof or in the vicinity of the end, in positions corresponding to each other.

Description

Assembly of polarizing plate and image display device containing the assembly

The invention relates to a polarizing plate assembly and an image display device containing the assembly.

In image display devices such as mobile phones and notebook personal computers, polarizing plates are widely used in order to realize image display and/or improve the image display performance. In recent years, due to the rapid spread of smartphones and touch panel-type information processing devices, image display devices equipped with cameras have gradually been widely used. In response to this situation, polarizing plates with through holes at positions corresponding to the camera are gradually being widely used. Regarding the polarizing plate having such a through hole, there are various review items for the through hole or its vicinity.

Prior art literature Patent literature Patent Document 1: International Publication No. 2017/047510

The problem to be solved by the invention The present invention is made to solve the above-mentioned problems in the past, and its main purpose is to provide a polarizing plate assembly in which the deviation of each polarizing plate in the through hole portion of the polarizing plate assembly is small, and the viewing side polarizing plate The difference between the offset and the offset of the back side polarizing plate is very small.

Means to Solve the Problem The polarizer assembly of the present invention is composed of a rectangular first polarizer arranged on the viewing side of an image display unit and a rectangular second polarizer arranged on the back side of the image display unit. The first polarizer has a first polarizer, a protective layer disposed on at least one side of the first polarizer, and a first adhesive layer disposed on the side of the image display unit; the second polarizer has a second polarizer , A protective layer disposed on at least one side of the second polarizer, a reflective polarizer disposed on the side of the second polarizer opposite to the image display unit, and a second adhesive disposed on the side of the image display unit Agent layer. The first polarizer and the second polarizer each have a thickness of 20 μm or less, the first polarizer has an absorption axis in the short-side direction, and the second polarizer has an absorption axis in the long-side direction. The first polarizing plate and the second polarizing plate have through holes at their respective ends or at positions corresponding to each other. _{In one embodiment, the distance A 1} (μm) from the outermost part of the image display unit side of the first adhesive layer to the center of the first polarizer in the thickness direction, and the thickness of the first polarizer T _pol1 (μm), the creep value of the first adhesive layer C _psa1 (μm/hr), the thickness of the first adhesive layer T _psa1 (μm), and the thickness T of the protective layer in the first polarizer _pro1 (μm) satisfies the following relationship: (A ₁ ×T _pol1 )×(C _psa1 ×T _psa1 )/T _pro1 =K ₁ ≦300×10 ² (μm ³ /hr) and from the second adhesive layer _{The distance A 2} (μm) from the outermost part of the image display unit side to the center of the second polarizer in the thickness direction _{, the thickness T pol2} (μm) of the second polarizer, and the thickness of the second adhesive layer The creep value C _psa2 (μm/hr), the thickness T _{psa2 (μm) of the second adhesive layer and the thickness T pro2} (μm) of the protective layer in the second polarizer satisfy the following relationship: (A ₂ × T _pol2 )×(C _psa2 ×T _psa2 )/T _pro2 = K ₂ ≦300×10 ² (μm ³ /hr). In one embodiment, the above-mentioned K ₁ and K ₂ are each 200×10 ² (μm ³ /hr) or less. In one embodiment, the creep value C _psa1 of the first adhesive layer is 100 (μm/hr) or less. In one embodiment, the thickness T _pol2 of the second polarizer is 10 μm or less. In one embodiment, the above-mentioned K ₁ and K ₂ are each 150×10 ² (μm ³ /hr) or less. In one embodiment, the thickness T _pol1 of the first polarizer is 10 μm or less. In one embodiment, the thickness T _psa1 of the first adhesive layer and the thickness T _{psa2 of} the second adhesive layer are 10 μm-22 μm, respectively. In one embodiment, the through hole is formed in each corner of the first polarizing plate and the second polarizing plate. In one embodiment, when the first polarizer and the second polarizer are viewed in plan, the distance from the center in the longitudinal direction to the end in the longitudinal direction is L ₁ , and the distance from the first polarizer and the second polarizer is L 1. The distance in the long-side direction from the center of the long-side direction of the second polarizer to the center of the through hole is L ₂ , so that from the center in the short-side direction of the first polarizer and the second polarizer to the short-side direction When the distance to the end is W ₁ and the short-side distance from the center of the first polarizer and the second polarizer in the short-side direction to the center of the through hole is W ₂ , the through hole It is formed at positions where the first polarizer and the second polarizer satisfy 0.85≦L ₂ /L ₁ ≦0.99 and 0.50≦W ₂ /W ₁ ≦0.99. In one embodiment, the diameter of the through hole is 10 mm or less. In one embodiment, the aspect ratios of the first polarizing plate and the second polarizing plate are 1.3 to 2.5, respectively. According to another aspect of the present invention, an image display device is provided. The image display device includes an assembly of an image display unit and the polarizing plate, the first polarizing plate is arranged on the visual side of the image display unit, and the second polarizing plate is arranged on the back side of the image display unit.

Invention effect According to the embodiment of the present invention, a polarizing plate assembly can be provided. The polarizing plate of the polarizing plate assembly has a small deviation in the through hole portion, and the deviation of the viewing-side polarizing plate is the same as that of the back-side polarizing plate. The difference in displacement is very small. The small deviation of the through holes of each polarizing plate can be multiplied to exert its effect when the assembly of the polarizing plate is made. The difference in offset is very small. When the polarizer assembly is applied to an image display device, the design advantage is very large. For example, the assembly of the polarizing plate can be applied to an image display device in which only the camera part is made into a non-display area and/or an image display device without a frame.

The following describes specific embodiments of the present invention with reference to the drawings, but the present invention is not limited by these embodiments. In addition, the drawings are schematically shown for easy viewing, and the ratios of length, width, thickness, etc., and angles in the drawings are different from the actual ones.

A. Outline of polarizing plate assembly 1 is a schematic plan view of the first polarizer and the second polarizer in the polarizer assembly of an embodiment of the present invention; FIG. 2 is the first polarizer and the second polarizer in the polarizer assembly of FIG. 1 A schematic cross-sectional view taken from each II-II line; FIG. 3 is a schematic cross-sectional view of an image display device including the assembly of the polarizing plate of FIG. 1. The polarizing plate assembly 100 in the example of the drawing is composed of a first polarizing plate 10 and a second polarizing plate 20. The first polarizing plate and the second polarizing plate respectively correspond to the top view shape of the image display unit, and have a rectangular shape with long sides and short sides. In addition, when referring to the "rectangular shape" in this specification, it also includes a shape including a special-shaped processed part such as an R shape obtained by chamfering each apex as shown in FIG. 1. As shown in FIG. 3, the first polarizing plate 10 is arranged on the viewing side of the image display unit 120, and the second polarizing plate 20 is arranged on the back side of the image display unit 120. In the example of the figure, the first polarizer 10 has a first polarizer 11, a protective layer (outer protective layer) 12 arranged on the viewing side of the first polarizer 11, and an image display unit side of the first polarizer 11 The protective layer (inner protective layer) 13 and the first adhesive layer 14 arranged as the outermost layer on the side of the image display unit 120. The first adhesive layer 14 can be used to bond the first polarizer 10 to the image display unit 120. It is also possible to omit one of the protective layers 12 and 13 according to the purpose. The second polarizer 20 has a second polarizer 21, a reflective polarizer 26 arranged on the back side (the side opposite to the image display unit) of the second polarizer 21, and a reflective polarizer 26 arranged on the image display unit side of the second polarizer 21 The protective layer (inner protective layer) 23 and the second adhesive layer 24 arranged as the outermost layer on the side of the image display unit 120. The second adhesive layer 24 can be used to bond the second polarizer 20 to the image display unit 120. In the second polarizer 20, a reflective polarizer 26 is arranged instead of the outer protective layer. That is, in the second polarizer 20, the reflective polarizer 26 also serves as an outer protective layer. Although the outer protective layer of the second polarizer is omitted in the illustrated example, the reflective polarizer 26 may also be arranged on the back side of the outer protective layer (the side opposite to the image display unit). The reflective polarizer 26 can be attached to the second polarizer 21 or the outer protective layer (when present) through any suitable adhesive layer (for example, 2 μm-20 μm in thickness).

In the embodiment of the present invention, the first polarizing plate 10 has a through hole 15 and the second polarizing plate 20 has a through hole 25. The through holes 15 and 25 are formed at the respective ends of the first polarizing plate and the second polarizing plate or at positions corresponding to each other. By forming the through hole, for example, the camera performance can be prevented from being adversely affected when the camera is embedded in the image display device. In addition, by forming the through hole at or near the end of the polarizing plate, the influence of the through hole on the image display (such as light leakage in the through hole) can be minimized when the polarizing plate is applied to an image display device limit. The through hole can be formed by various methods such as laser processing, cutting with an end mill, and punching with a Thomson knife or a pointed knife (registered trademark). In addition, in this specification, the term "installed at a position corresponding to each other" means that the through holes overlap when two polarizing plates are stacked.

As shown in FIG. 1, the first polarizer 11 has an absorption axis Ab ₁ in the short-side direction, and the second polarizer 21 has an absorption axis Ab ₂ in the long-side direction. Rectangular films tend to shrink along the long side but not along the short side. In addition, the polarizing member (and the polarizing plate as a result) tends to absorb axial shrinkage. Therefore, the absorption axis direction of the second polarizer, which is not easy to shrink by including the reflective polarizer, is the long side direction of the film (the direction of easy shrinkage), and the first, which is easy to shrink compared with the second polarizer, is made The direction of the absorption axis of the polarizer is the short-side direction (the direction that is not easy to shrink), which can reduce the deviation of each polarizer in the through hole part, and can reduce the deviation of the first polarizer and the second polarizer. The difference.

It is also possible to provide a retardation layer on the first polarizer 10 and/or the second polarizer 20 according to needs. The type, number, combination, arrangement position, and characteristics of the retardation layer can be appropriately set according to the purpose. For example, the retardation layer can be a λ/2 plate, a λ/4 plate, or a laminate of these. The λ/2 plate and the λ/4 plate represent the refractive index characteristics of nx>ny≧nz. The in-plane retardation Re(550) of the λ/2 plate should be 180nm~320nm, and the in-plane retardation Re(550) of the λ/4 plate should be 100nm~200nm. For another example, the retardation layer may also be a laminate of a negative B plate (nx>ny>nz) and a positive C plate (nz>nx=ny) or a positive B plate (nz>nx>ny). In addition, "Re(λ)" in this specification refers to the in-plane retardation measured at 23°C with light of wavelength λnm. 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). "Rth(λ)" is the thickness direction retardation measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the thickness direction retardation measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm). "Nx" is the refractive index in the direction where the in-plane refractive index is the largest (that is, the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis (that is, the fast axis direction) in the plane, and " nz" is the refractive index in the thickness direction.

The following specifically describes the constituent elements of the polarizing plate assembly. In addition, the first polarizer and the second polarizer are integrated as a polarizer, and the first polarizer and the second polarizer are integrated as a polarizer. The protective layers of the first and second polarizers The integration is illustrated by a protective layer, and the integration of the first adhesive layer and the second adhesive layer is illustrated by the adhesive layer. Therefore, for example, when referring to "polarizing plate", it can mean "the first polarizing plate and the second polarizing plate...". On the other hand, for example, when the first polarizing plate and the second polarizing plate need to be described separately, the "first" or "second" will be clearly noted.

B. Polarizing plate B-1. Overall structure of the polarizing plate In one embodiment, the first polarizing plate 10 should satisfy the following relationship: (A ₁ ×T _pol1 )×(C _psa1 ×T _psa1 )/T _pro1 =K ₁ ≦300×10 ² (μm ³ /hr) where A ₁ is the distance from the outermost part of the first adhesive layer 14 on the image display unit 120 side to the center of the first polarizer 11 in the thickness direction ( µm); T _pol1 is the thickness of the first polarizer 11 (µm); C _psa1 is the creep value of the first adhesive layer 14 (µm/hr), and T _psa1 is the thickness of the first adhesive layer 14 (µm) ; T _pro1 is the thickness of the protective layer in the first polarizer 10 (µm). Similarly, the second polarizer 20 preferably satisfies the following relationship: (A ₂ ×T _pol2 )×(C _psa2 ×T _psa2 )/T _pro2 =K ₂ ≦300×10 ² (μm ³ /hr). Here, A _{2 is the distance (µm) from the outermost} part of the second adhesive layer 24 on the image display unit 120 side to the center of the second polarizer 21 in the thickness direction (µm); T pol2 is the distance of the second polarizer 21 Thickness (µm); C _psa2 is the creep value (µm/hr) _{of the second adhesive layer 24, T psa2} is the thickness of the second adhesive layer 24 (µm); T _pro2 is the protective layer in the second polarizer 20 The thickness (µm). The "creep value" in this manual refers to the creep value at 85°C. The creep value can be measured, for example, according to the following procedure: sticking the adhesive constituting the adhesive layer to the support plate. Fix the support plate to which the adhesive is attached, and apply a load of 500g under it vertically in this state. Measure the offset of the adhesive from the support plate after applying the load for 1 hour, and use the offset as the creep value (μm/hr). _{In addition, the thickness T pro1} of the protective layer in the above relational expression can be obtained from the formula: "total thickness of the first polarizer-thickness of the first adhesive layer-thickness of the first polarizer". That is, T _pro1 is the total thickness of the protective layer 12 and the protective layer 13 and the thickness of the adhesive layer for attaching the protective layer (including the thickness of the polarizer or the protective film and the reflective polarizer through the adhesive layer) The total thickness of the adhesive layer) and the thickness of the surface treatment layer formed on the protective layer 12 as required. The same _{applies to} T pro2 related to the second polarizer. The K ₁ value and K ₂ value should be 250×10 ² (μm ³ /hr) or less, more preferably 200×10 ² (μm ³ /hr) or less, especially 150×10 ² (μm ³ /hr) the following. Hereinafter, the combination of the K ₁ value and the K ₂ value is simply referred to as the K value. The same applies to the distance A, creep value, thickness of the adhesive layer, and thickness of the protective layer. The lower limit of the K value may be, for example, 15×10 ² (μm ³ /hr). As long as the K value is in the above range, the displacement of the through hole portion (essentially the displacement of the adhesive layer) can be significantly suppressed. The technical significance of setting the K value below the predetermined value is as follows: when the moment applied to the adhesive layer and the mobility of the adhesive layer itself are large, the offset of the adhesive layer will become larger, and when the If the restraining force of the movement of the layer is large, the deviation of the adhesive layer will be smaller. The moment applied to the adhesive layer is related to the distance from the image display unit to which the polarizing plate can be attached to the polarizing member and the thickness of the polarizing member; the mobility of the adhesive layer itself is related to the softness of the adhesive layer and The thickness is related; and the restraining force against the movement of the adhesive layer is related to the thickness of the protective layer. By reducing the distance from the image display unit to the polarizer and the thickness of the polarizer, the torque can be reduced; by setting the creep value of the adhesive layer below a predetermined value (make the adhesive layer harder) and make the adhesion The thickness of the agent layer is thin, so that the adhesive layer itself is not easy to move; by setting the thickness T _{pro of the} protective layer within a predetermined range, the restraining force against the movement of the adhesive layer can fall within an appropriate range. Therefore, by adjusting the above-mentioned requirements to control the K value below a predetermined value, the deviation of the adhesive layer can be significantly suppressed. Specifically, the aforementioned distance A is preferably 80 μm or less, and more preferably 50 μm or less. The lower limit of the distance A may be 10 μm, for example. The creep value C _{psa is} preferably 140 μm/hr or less, preferably 130 μm/hr or less, more preferably 120 μm/hr or less, and particularly preferably 100 μm/hr or less. The lower limit of the creep value may be 50 μm/hr, for example. The thickness T _{pro of the} protective layer is preferably 15 μm to 65 μm, more preferably 15 μm to 55 μm. The thickness T _{psa of the} adhesive layer is preferably 22 μm or less, more preferably 10 μm to 22 μm. If the creep value C _{psa is} too small and/or the thickness of the adhesive layer T _{psa is} too small, stress relaxation will become difficult, and the risk of cracking or peeling may increase. If the thickness T _{pro of the} protective layer is too small, it may be difficult to adjust the curl.

As shown in Figure 4, the polarizing plate (the example of the figure is the first polarizing plate 10) is attached to the glass plate (corresponding to the substrate of the image display unit) 130 and subjected to a heating test at 85°C for 120 hours The offset D of the through hole is, for example, 300µm or less, preferably 250µm or less, more preferably 200µm or less, more preferably 150µm or less, particularly preferably 120µm or less, particularly preferably 100µm or less, and most preferably 80µm or less. The smaller the offset D, the better, and the lower the offset D is limited to 10 μm in one embodiment, and 20 μm in another embodiment. In addition, the offset D refers to the largest part of the polarizing plate away from the through hole when viewed in cross section. The reference representative of the through hole portion may be the lower end of the adhesive layer. That is, when the polarizing plate is deviated (to the right in the example of the drawing) mainly due to the shrinkage of the polarizer, it will stop at the glass plate 130 to which the adhesive layer 14 is adhered, and the deflection will be recognized in the through hole portion. In addition, as shown in Figure 4, the through-hole part of the polarizer representative is offset to the side away from the through-hole (the right side of Figure 4), and at the same time, the part facing it is offset in the way that the through-hole protrudes in the past (Figure 4). 4 on the left). According to the embodiment of the present invention, both the first polarizer and the second polarizer can reduce the deviation of the through hole portion (essentially the deviation of the adhesive layer) as described above, so when the assembly of the polarizer is made It can be multiplied to play its effect.

The difference (absolute value) between the offset of the first polarizer and the offset of the second polarizer is, for example, 85 µm or less, preferably 80 µm or less, more preferably 60 µm or less, more preferably 40 µm or less, and particularly preferably 30 µm or less . The smaller the difference in offset, the better. The lower limit of the difference in the offset may be, for example, 3 µm. According to the embodiment of the present invention, the difference between the offset of the first polarizer and the offset of the second polarizer can be kept small. As a result, the polarizing plate assembly can be applied to image display devices in which only the camera part is made into a non-display area and/or image display devices without borders.

The dimensional shrinkage rate of the polarizing plate after the above heating test is preferably 1.0% or less, more preferably 0.6% or less, and more preferably 0.3% or less. The smaller the dimensional shrinkage, the better, and the lower limit of the dimensional shrinkage may be 0.01%, for example. In addition, the dimensional shrinkage rate can be obtained by the following formula. In addition, the size shrinkage rate refers to the size shrinkage rate of the entire polarizing plate attached to the glass plate. When the polarizing plate further has an optical function layer (such as a retardation layer, a reflective polarizer), it means the polarized light including the optical function layer The size shrinkage rate of the board as a whole. In addition, the "size" in the following formula is the size of the absorption axis direction of the polarizing plate (substantially a polarizer). Dimensional shrinkage (%) = {(size before heating test-size after heating test)/size before heating test}×100

In the polarizing plate, the through hole should be formed at any suitable position at or near the end according to the purpose. In one embodiment, the through holes 15 and 25 are formed in the respective corners of the polarizing plate as shown in FIG. 1. In addition, the formation position of the through hole is not limited to the corner portion. The through hole can be formed in the approximate center of the long-side end of the polarizing plate, can be formed in the predetermined position of the long-side end, can be formed in the approximate center of the short-side end, or in the short-side direction The predetermined position of the end. In addition, multiple through holes may be formed, or through holes and notches may be combined.

In one embodiment, as shown in FIG. 5, let the distance from the center of the polarizer in the longitudinal direction to the end in the longitudinal direction be L ₁ , and let the length from the center of the polarizer in the longitudinal direction to the center of the through hole be L 1 The distance in the side direction is L ₂ , the distance from the center in the short side direction of the polarizer to the end in the short side direction is W ₁ , and the short side direction from the center in the short side direction of the polarizer to the center of the through hole When the distance between is W ₂ , the through hole should be formed at a position that satisfies 0.85≦L ₂ /L ₁ ≦0.99 and 0.50≦W ₂ /W ₁ ≦0.99. L ₂ /L _{1 is} more preferably 0.90 to 0.97, and more preferably 0.92 to 0.96. W ₂ /W _{1 is} more preferably 0.75 to 0.95.

The diameter R of the through hole is preferably 10mm or less, more preferably 8mm or less, and more preferably 5mm or less. The lower limit of the diameter of the through hole may be, for example, 2 mm, and for example, may be 1.5 mm. The ratio D/R of the offset D to the diameter R of the through hole is preferably 15% or less, preferably 10% or less, more preferably 6% or less, and particularly preferably 5% or less. On the other hand, the lower the D/R limit, the better. According to the embodiment of the present invention, the offset D is extremely small as described above, so even if the diameter of the through hole is reduced, D/R can be kept within the above range. Therefore, even if the diameter of the through hole is reduced, the adverse effect on the camera performance can be substantially prevented. As a result, the polarizing plate used in the embodiment of the present invention can be applied to an image display device in which only the camera part is made into a non-display area and/or an image display device without a frame.

The aspect ratio of the polarizer should be 1.3~2.5. At this time, the size of the polarizing plate is, for example, 145 mm to 155 mm in length and 65 mm to 75 mm in width, or 230 mm to 240 mm in length and 140 mm to 150 mm in width. That is, the polarizing plate of the embodiment of the present invention can be suitably used for a smart phone or a tablet PC. The size of a smart phone, for example, can be 120mm~200mm in length and 30mm~120mm in width.

B-2. Polarizing parts The representative of the polarizer is composed of a resin film containing a dichroic substance. As for the resin film, any suitable resin film that can be used as a polarizer can be used. The resin film is typically a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film. The resin film may be a single-layer resin film or a laminate of two or more layers.

A specific example of a polarizer composed of a single-layer resin film may include a PVA-based resin film that has been dyed and stretched with iodine (representatively, uniaxially stretched). The above-mentioned dyeing with iodine can be performed by immersing a PVA-based film in an iodine aqueous solution, for example. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3~7 times. Stretching can be carried out after the dyeing treatment, or it can be carried out while dyeing. Also, it can be stretched and then dyed. The PVA-based resin film can be subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. according to demand. For example, immersing a PVA-based resin film in water for washing before dyeing can not only clean the dirt or anti-blocking agent on the surface of the PVA-based film, but also swell the PVA-based resin film to prevent uneven dyeing.

Specific examples of polarizers obtained by using a laminate include a laminate of a resin substrate and a PVA resin layer (PVA resin film) laminated on the resin substrate, or a laminate of a resin substrate and coating A polarizer obtained by forming a laminate of PVA-based resin layers on the resin substrate. The polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it, A PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and the laminate is extended and dyed to make the PVA-based resin layer into a polarizer. In this embodiment, stretching typically includes immersing the laminate in a boric acid aqueous solution and stretching. In addition, if necessary, the stretching may further include stretching the laminate in the air at a high temperature (for example, 95°C or higher) before stretching in an aqueous boric acid solution. The obtained resin substrate/polarizer laminate can be used directly (that is, the resin substrate can be used as the protective layer of the polarizer), or the resin substrate can be peeled from the resin substrate/polarizer laminate and placed on the release surface Lay any appropriate protective layer for later use depending on the purpose. The details of the manufacturing method of the polarizer are described in, for example, Japanese Patent Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. This specification uses the records of these patent documents as references.

The thickness of the polarizer is preferably 20 µm or less, preferably 12 µm or less, and more preferably 10 µm or less. The lower limit of the thickness of the polarizer is 1 µm in one embodiment, and 3 µm in another embodiment. As long as the thickness of the polarizer is within the above range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

The polarizer should exhibit absorption dichroism at any wavelength from 380nm to 780nm. The single transmittance of the polarizer is, for example, 41.5%-46.0%, and preferably 43.0%-46.0%, more preferably 44.5%-46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, preferably 99.0% or more, and more preferably 99.9% or more.

B-3. Protective layer The protective layers 12, 13, and 23 are formed of any suitable film that can be used as a protective layer of the polarizer. Specific examples of the material that becomes the main component of the film include cellulose resins such as cellulose triacetate (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, and polyamides. Transparent resins such as imine-based, polyether-based, poly-based, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate-based transparent resins, etc. In addition, thermosetting resins such as (meth)acrylic, urethane, (meth)acrylate urethane, epoxy, and silicone resins, or ultraviolet curable resins, etc. may also be mentioned. Other examples include glassy polymers such as silicone polymers. In addition, the polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted iminium group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, Examples include resin compositions having alternating copolymers composed of isobutylene and N-methylmaleimide and acrylonitrile-styrene copolymers. The polymer film may be, for example, an extruded product of the above-mentioned resin composition.

The outer protective layer (especially the outer protective layer 12 of the first polarizing plate) may also be subjected to surface treatments such as hard coating treatment, anti-reflection treatment, anti-adhesion treatment, and anti-glare treatment as needed. And/or, the outer protective layer can also be processed as needed to improve the visibility through polarized sunglasses (representatively, imparting (elliptical) circular polarization function and imparting ultra-high phase difference). By performing the above processing, even when the display screen is visualized through a polarizing lens such as polarized sunglasses, excellent visibility can still be achieved. Therefore, the assembly of polarizing plates can also be suitably used in image display devices that can be used outdoors.

The inner protective layers 13, 23 are preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0nm~10nm, and the thickness direction retardation Rth(550) is -10nm~+10nm. Here, "Re(λ)" is the in-plane retardation measured at 23°C with light of wavelength λnm. 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). "Rth(λ)" is the thickness direction retardation measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the thickness direction retardation measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm). nx is the refractive index in the direction in which the in-plane refractive index is the largest (that is, the slow axis direction), ny is the refractive index in the direction orthogonal to the slow axis in the plane (that is, the fast axis direction), and nz is the direction in the thickness direction. Refractive index.

The thickness of the protective layer can be any appropriate thickness. The thickness of the protective layer is, for example, 10 μm to 50 μm, and preferably 20 μm to 40 μm. In addition, when the surface treatment is applied, the thickness of the protective layer includes the thickness of the surface treatment layer. In addition, the "thickness of the protective layer" mentioned here refers to the respective thicknesses of the outer protective layers 12, 22 and the inner protective layer 13, which are different from _{T pro1} and T _{pro2 in the above formula.}

B-4. Adhesive layer The adhesive layer is as described above, and can be used to attach the polarizing plate to the image display unit. The adhesive layer can typically be composed of an acrylic adhesive (acrylic adhesive composition). The acrylic adhesive composition typically contains a (meth)acrylic polymer as a main component. The (meth)acrylic polymer may be contained in the adhesive composition at a ratio of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more in the solid content of the adhesive composition. The (meth)acrylic polymer contains an alkyl (meth)acrylate as a main component as a monomer unit. In addition, (meth)acrylate means acrylate and/or methacrylate. The alkyl (meth)acrylate is preferably contained in a ratio of 80% by weight or more in the monomer components forming the (meth)acrylic polymer, and more preferably contained in a ratio of 90% by weight or more. Examples of the alkyl group of the alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average carbon number of the alkyl group is preferably 3-9, more preferably 3-6. The preferred alkyl (meth)acrylate is butyl acrylate. The monomers (comonomers) constituting the (meth)acrylic polymer include carboxyl group-containing monomers, hydroxyl group-containing monomers, amine group-containing monomers, aromatic-containing monomers in addition to (meth)acrylic acid alkyl esters. Cyclo (meth)acrylates, heterocyclic ring-containing vinyl monomers, etc. Representative examples of comonomers include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic adhesive composition preferably contains a silane coupling agent and/or a crosslinking agent. Examples of the silane coupling agent include epoxy-containing silane coupling agents. Examples of the crosslinking agent include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. In addition, the acrylic adhesive composition may contain an antioxidant and/or a conductive agent. The thickness of the adhesive layer is preferably 22µm or less as mentioned above, and more preferably 10µm~22µm. The details of the adhesive layer or the acrylic adhesive composition have been described in, for example, Japanese Patent Laid-Open No. 2006-183022, Japanese Patent Laid-Open No. 2015-199942, Japanese Patent Laid-Open No. 2018-053114, and Japanese Patent In the Publication No. 2016-190996 and International Publication No. 2018/008712, this specification uses the records of these publications as references.

_{The storage elastic modulus G 2} 'of the adhesive layer at -40℃ is preferably 1.0×10 ⁵ (Pa) or more, more preferably 1.0×10 ⁶ (Pa) or more, and more preferably 1.0×10 ⁷ (Pa) or more , Especially preferably 1.0×10 ⁸ (Pa) or more. The storage elastic modulus G ₂ ′ may be 1.0×10 ⁹ (Pa) or less, for example.

B-5. Reflective polarizer The reflective polarizer 26 can be provided on the side (rear side) of the second polarizer 20 opposite to the image display unit 120 as described above. By providing a reflective polarizer, the second polarizer is less likely to shrink than the first polarizer. As a result, by making the absorption axis direction of the second polarizing plate the long side direction of the film (the direction that is easy to shrink), and setting the absorption axis direction of the first polarizing plate to the short side direction (the direction that is not easy to shrink), each can be reduced. The deviation of the polarizing plate in the through hole portion can reduce the difference between the deviation of the first polarizing plate and the deviation of the second polarizing plate.

The reflective polarizer has a function of transmitting polarized light in a specific polarization state (polarization direction) and reflecting light in a polarization state other than this state. The reflective polarizer can be either a linear polarization separation type or a circular polarization separation type. Hereinafter, as an example, a description will be given of a reflective polarizer of a linear polarization separation type. In addition, the reflective polarizer of the circular polarization separation type can be, for example, a laminate of a film with a cholesteric liquid crystal immobilized and a λ/4 plate.

Fig. 6 is a schematic perspective view of an example of a reflective polarizer. The reflective polarizer is a multilayer laminate in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, the total number of layers of the multilayer laminate may be 50~1000. In the example of the figure, the refractive index nx in the x-axis direction of the A layer is greater than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of the B layer is substantially the same as the refractive index ny in the y-axis direction. . Therefore, the refractive index difference between the A layer and the B layer is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction is the reflection axis, and the y-axis direction is the transmission axis. The refractive index difference between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3. In addition, the x-axis direction corresponds to the extending direction of the reflective polarizer in the manufacturing method of the reflective polarizer.

The A layer is preferably made of a material that can exhibit birefringence through extension. Representative examples of the materials include naphthalene dicarboxylic acid polyester (for example, polyethylene naphthalate), polycarbonate, and acrylic resin (for example, polymethyl methacrylate). It is preferably polyethylene naphthalate. The above-mentioned layer B is preferably made of a material that does not substantially exhibit birefringence even if it is stretched. Representative examples of the materials include copolyesters of naphthalenedicarboxylic acid and terephthalic acid.

In the reflective polarizer, the interface between the A layer and the B layer transmits light with a first polarization direction (such as p-wave) and reflects light with a second polarization direction orthogonal to the first polarization direction (such as s-wave). ). A part of the reflected light at the interface between the A layer and the B layer is transmitted as light having the first polarization direction, and a part is reflected as light having the second polarization direction. Inside the reflective polarizer, the reflection and transmission are repeated many times, so the light utilization efficiency can be improved.

In one embodiment, the reflective polarizer may also include a reflective layer R as shown in FIG. 6 as the outermost layer on the side opposite to the image display unit. By providing the reflective layer R, the light that has not been used in the end and returned to the outermost part of the reflective polarizer can be further used, so that the light use efficiency can be further improved. The reflective layer R represents a multilayer structure through the polyester resin layer to exhibit a reflective function.

The overall thickness of the reflective polarizer can be appropriately set according to the purpose, the total number of layers included in the reflective polarizer, and so on. The overall thickness of the reflective polarizer is preferably 10μm~150μm.

As the reflective polarizer, for example, what is described in Japanese Patent Publication No. 9-507308 and Japanese Patent Application Publication No. 2013-235259 can be used. Reflective polarizers can be used directly, or they can be used after secondary processing (for example, extension). Examples of commercially available products include DBEF manufactured by 3M Corporation and APF manufactured by 3M Corporation.

C. Image display device The polarizing plate assembly of the embodiment of the present invention can be suitably applied to an image display device as described above. Therefore, the image display device is also included in the embodiment of the present invention. The image display device includes an assembly of an image display unit and a polarizing plate. The assembly of the polarizing plate is the assembly of the polarizing plate of the embodiment of the present invention described in the above items A to B. As shown in FIG. 3, the image display device 200 has an image display unit 120, a first polarizing plate 10 arranged on the viewing side of the image display unit 120, and a second polarizing plate 20 arranged on the back side of the image display unit 120.

The image display device may be a liquid crystal display device, an organic electroluminescence (EL) display device, and a quantum dot display device. Preferably, it is a liquid crystal display device. The effect brought by the assembly of the polarizing plate is very significant. Example

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. The evaluation items of the embodiment are as follows. Moreover, as long as there is no special note, the "parts" and "%" in the examples are the basis of weight.

(1) Offset The first polarizing plate and the second polarizing plate in the assembly of the polarizing plates obtained in the Examples and Comparative Examples were attached to a glass plate (manufactured by Matsunami Glass Co., Ltd., length 350mm×width 250mm×thickness 1.1mm) through an adhesive layer. Make test specimens. For each test sample, it is used for heating test at 85°C and 120 hours. After the test, an optical microscope (MX61L) manufactured by OLYMPUS was used to measure the shift amount of the first polarizer or the second polarizer (essentially the first adhesive layer or the second adhesive layer) at the through hole portion. In addition, the measurement system was performed on three test samples, and the maximum value of the three measurement values was used as the offset.

＜Manufacturing example 1＞ The monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was fed into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. With respect to 100 parts of the monomer mixture (solid content), 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts by weight of ethyl acetate were fed together, and nitrogen was introduced while slowly stirring. After the nitrogen substitution, the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution (a) of an acrylic polymer with a weight average molecular weight (Mw) of 1.56 million. With respect to 100 parts of the solid content of the obtained acrylic polymer (a) solution, 0.1 part of isocyanate crosslinking agent (trade name: TAKENATE D160N, trimethylolpropane hexamethylene diisocyanate, manufactured by Mitsui Chemicals Co., Ltd.) is blended , Benzyl peroxide (trade name: NYPER BMT 40SV, manufactured by Nippon Oil & Fat Co., Ltd.) 0.3 parts, thiol group-containing silane coupling agent (trade name: X-41-1810, manufactured by Shin-Etsu Chemical Co., Ltd., Alkoxy amount: 30%, mercaptan equivalent: 450 g/mol) 0.3 part and antioxidant (trade name: Irganox 1010, hindered phenol series, manufactured by BASF Japan) 0.2 part, and adhesive composition A was obtained.

＜Manufacturing example 2＞ Use a monomer mixture containing 81.8 parts of butyl acrylate, 16 parts of phenoxyethyl acrylate, 1.5 parts of N-vinyl-2-pyrrolidone, 0.3 parts of acrylic acid and 0.4 parts of 4-hydroxybutyl acrylate. In the same manner as in Production Example 1, a solution of acrylic polymer (b) with a weight average molecular weight (Mw) of 1.57 million was prepared. Acrylic polymer (b) is used. Silane coupling agent contains thiol group-containing silane coupling agent (trade name: X-41-1056, manufactured by Shin-Etsu Chemical Co., Ltd., alkoxy content: 30%, mercaptan equivalent) : 450g/mol) 0.2 part, no antioxidant is used, and 0.5 part of lithium bis(trifluoromethanesulfonyl)imide (manufactured by Mitsubishi Materials Corporation) is further added, except for the above, in the same manner as in Production Example 1 The adhesive composition B was obtained.

＜Manufacturing example 3＞ Use a monomer mixture containing 80.3 parts of butyl acrylate, 16 parts of phenoxyethyl acrylate, 3 parts of N-vinyl-2-pyrrolidone, 0.3 parts of acrylic acid and 0.4 parts of 4-hydroxybutyl acrylate. In the same manner as in Production Example 1, a solution of acrylic polymer (c) with a weight average molecular weight (Mw) of 1.5 million was prepared. Use acrylic polymer (c), set the blending amount of silane coupling agent to 0.1 part, and add conductive agent (1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide), 5 parts of ionic liquid manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., except for the above, the adhesive composition C was obtained in the same manner as in Production Example 1.

＜Manufacturing example 4＞ In the same manner as in Production Example 1, a solution of acrylic polymer (d) with a weight average molecular weight (Mw) of 1.65 million was prepared. With respect to 100 parts of the solid content of the obtained acrylic polymer (d) solution, 0.1 part of isocyanate crosslinking agent (trade name: TAKENATE D110N, trimethylolpropane hexamethylene diisocyanate, manufactured by Mitsui Chemicals Co., Ltd.) is blended , Benzyl peroxide (trade name: NYPER BMT 40SV, manufactured by Nippon Oil & Fat Co., Ltd.) 0.3 parts and silane coupling agent containing acetyl acetyl group (trade name: A-100, manufactured by Soken Chemical Co., Ltd.) 0.2 parts , And the adhesive composition D is obtained.

＜Manufacturing Example 5＞ Silane coupling agent containing thiol group (trade name: X-41-1810, manufactured by Shin-Etsu Chemical Co., Ltd., alkoxy content: 30%, mercaptan equivalent: 450g/mol) 0.2 parts, except Otherwise, the adhesive composition E was obtained in the same manner as in Production Example 1.

<Example 1> (Making the first polarizing plate) The polarizer (first polarizer) is a film (thickness 12 μm) obtained by uniaxially extending a long-side polyvinyl alcohol (PVA)-based resin film containing iodine in the longitudinal direction (MD direction). On both sides of the polarizer, the long HC-TAC film to be the outer protective layer and the long acrylic resin film (thickness 20μm) to be the inner protective layer are attached so that the longitudinal directions of both sides are aligned. Together. In addition, the HC-TAC film is a cellulose triacetate (TAC) film (thickness of 25 μm) with a hard coat (HC) layer (thickness of 7 μm) formed on the film, and the TAC film is bonded to form the polarizer side. The adhesive composition B is used on the surface of the inner protective layer to form an adhesive layer (the first adhesive layer: thickness 20µm) to obtain a structure having an outer protective layer/first polarizer/inner protective layer/first adhesive layer The first polarizing plate. The first polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the first polarizer becomes the short-side direction.

(Making the second polarizing plate) Except for using TAC film (thickness 25µm) instead of HC-TAC film as the outer protective layer, a polarizing plate was obtained in the same manner as in the case of the first polarizing plate. After bonding the reflective polarizer (thickness 26µm) on the surface of the outer protective layer through the general adhesive layer (thickness 12µm), the adhesive composition E is used to form the second adhesive layer (thickness 20µm) on the surface of the reflective polarizer. Thus, a second polarizer having a configuration of reflective polarizer/outer protective layer/second polarizer/inner protective layer/second adhesive layer was obtained. The second polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the second polarizer becomes the longitudinal direction.

(Assembly of polarizing plate) The first polarizing plate obtained in the above manner was used as the viewing side polarizing plate, and the second polarizing plate was used as the back side polarizing plate to make an assembly of the polarizing plate of the embodiment. The obtained polarizing plate assembly was used for the above-mentioned offset evaluation. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate. In addition, in Table 1, "0°" refers to the long side direction, and "90°" refers to the short side direction.

＜Comparative example 1＞ The first polarizer is punched so that the absorption axis direction of the first polarizer becomes the long side direction, and the second polarizer is punched so that the absorption axis direction of the second polarizer becomes the short side direction. In addition, the polarizing plate assembly was obtained in the same manner as in Example 1. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

<Example 2> (Making the first polarizing plate) The adhesive composition C was used to form the first adhesive layer (thickness 20 µm), except that it was the same as in Example 1 to obtain an outer protective layer/first polarizer/inner protective layer/first adhesive layer The first polarizing plate of the composition. The first polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the first polarizer becomes the short-side direction.

(Making the second polarizing plate) The thermoplastic resin substrate is a long strip of amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100μm) with a Tg of about 75°C, and corona treatment is applied to one side of the resin substrate. . A 9:1 mixture of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") to form a PVA-based resin 13 parts by weight of potassium iodide was added to 100 parts by weight, and the resultant was dissolved in water to prepare a PVA aqueous solution (coating liquid). The above-mentioned 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 to produce a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching treatment). Next, the layered body was immersed in an insoluble bath (a boric acid aqueous solution obtained by blending 4 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 (insoluble treatment). Next, adjust the concentration of the dyeing bath at a liquid temperature of 30°C (with respect to 100 parts by weight of water, an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7) so that the monomer transmittance ( Ts) becomes the desired value and is immersed in it for 60 seconds at the same time (dyeing treatment). Next, it was immersed in a cross-linking 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 with a liquid temperature of 40°C) for 30 seconds (cross-linking treatment) . Then, while immersing the layered body in a boric acid aqueous solution (boric acid concentration of 4% by weight, potassium iodide concentration of 5% by weight) at a liquid temperature of 70°C, uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds In order to make the total extension ratio up to 5.5 times (extension treatment in water). After that, the layered body was immersed in a washing bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment). After that, while drying in an oven maintained at about 90°C, the contact surface temperature was maintained at about 75°C with a heated roll made of SUS (drying shrinkage treatment). In the above manner, a polarizer with a thickness of about 5 µm is formed on the resin base material to obtain a laminate having the composition of the resin base material/second polarizer. A TAC film (thickness 20 μm) was attached to the surface of the polarizer of the obtained laminate (the surface on the side opposite to the resin substrate) as an inner protective layer. Next, the resin substrate is peeled off, and a reflective polarizer (thickness 26 µm) is attached to the peeled surface through a general adhesive layer (thickness 12 µm). The adhesive composition D was used to form an adhesive layer (thickness 20 µm) on the surface of the inner protective layer to obtain a second polarizing plate with a composition of reflective polarizer/second polarizer/inner protective layer/second adhesive layer. The second polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the second polarizer becomes the longitudinal direction.

(Assembly of polarizing plate) The first polarizing plate obtained in the above manner was used as the viewing side polarizing plate, and the second polarizing plate was used as the back side polarizing plate to make an assembly of the polarizing plate of the embodiment. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

＜Comparative example 2＞ The first polarizer is punched so that the absorption axis direction of the first polarizer becomes the long side direction, and the second polarizer is punched so that the absorption axis direction of the second polarizer becomes the short side direction. In addition, the polarizing plate assembly was obtained in the same manner as in Example 2. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

<Example 3> (Making the first polarizing plate) Cycloolefin resin film (thickness 13µm) is used instead of acrylic resin film as the inner protective layer, and adhesive composition C is used instead of adhesive composition B to form the first adhesive layer (thickness 20µm). In the same manner as in Example 1, a first polarizing plate having a configuration of outer protective layer/first polarizer/inner protective layer/first adhesive layer was obtained. The first polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the first polarizer becomes the short-side direction.

(Making the second polarizing plate) In the same manner as in Example 2, a laminate having a resin base material/second polarizer configuration was obtained. A TAC film (thickness 20 μm) was attached to the surface of the polarizer of the obtained laminate (the surface on the side opposite to the resin substrate) as an inner protective layer. Next, the resin substrate is peeled off, and a reflective polarizer (thickness 26 µm) is attached to the peeled surface through a general adhesive layer (thickness 12 µm). Use the adhesive composition D on the surface of the inner protective layer to form a second adhesive layer (thickness 20 µm) to obtain a second polarized light having a composition of reflective polarizer/second polarizer/inner protective layer/second adhesive layer board. The second polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the second polarizer becomes the longitudinal direction.

(Assembly of polarizing plate) The first polarizing plate obtained in the above manner was used as the viewing side polarizing plate, and the second polarizing plate was used as the back side polarizing plate to make an assembly of the polarizing plate of the embodiment. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

<Comparative Example 3> The first polarizer is punched so that the absorption axis direction of the first polarizer becomes the long side direction, and the second polarizer is punched so that the absorption axis direction of the second polarizer becomes the short side direction. In addition, the polarizing plate assembly was obtained in the same manner as in Example 3. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

<Example 4> (Making the first polarizing plate) In the same manner as the second polarizing plate of Example 2, a laminate having a resin base material/polarizer configuration was obtained. An HC-TAC film was attached as an outer protective layer to the surface of the polarizer of the obtained laminate (the surface on the opposite side to the resin substrate). Next, the resin substrate is peeled off, and the adhesive composition A is used on the peeled surface to form an adhesive layer (thickness 15 µm) to obtain a structure with outer protective layer/first polarizer/inner protective layer/first adhesive layer The first polarizing plate. The first polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the first polarizer becomes the short-side direction.

(Second Polarizing Plate) The same second polarizing plate as in Example 3 was used.

(Assembly of polarizing plate) The first polarizing plate obtained in the above manner was used as the viewing side polarizing plate, and the second polarizing plate was used as the back side polarizing plate to make an assembly of the polarizing plate of the embodiment. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

<Comparative Example 4> (Making the first polarizing plate) The polarizer (first polarizer) is a film (thickness 22 μm) obtained by uniaxially extending a long polyvinyl alcohol (PVA)-based resin film containing iodine in the longitudinal direction (MD direction). On both sides of the polarizer, the long TAC film (thickness 40μm) to be the outer protective layer and the long acrylic resin film (thickness 30μm) to be the inner protective layer are respectively aligned so that the longitudinal directions of both sides are aligned. The way fits. The adhesive composition D was used on the surface of the inner protective layer to form an adhesive layer (thickness 20 µm) to obtain a first polarizing plate with a composition of outer protective layer/first polarizer/inner protective layer/first adhesive layer. The first polarizer is punched out to a size of 148mm in length and 70mm in width, and a through hole with a diameter of 3.9mm is formed in the corner. At this time, punching is performed so that the absorption axis direction of the first polarizer becomes the short-side direction.

(Second Polarizing Plate) The same second polarizing plate as in Example 1 was used.

(Assembly of polarizing plate) The first polarizing plate obtained in the above manner was used as the viewing side polarizing plate, and the second polarizing plate was used as the back side polarizing plate to make the assembly of the polarizing plate of the comparative example of cost. The obtained polarizing plate assembly was subjected to the same evaluation as in Example 1. The results are shown in Table 1 together with the detailed configuration of the first polarizing plate and the second polarizing plate.

[Table 1]

It is obvious from Table 1 that, compared with the comparative example, the assembly of the polarizing plate of the embodiment of the present invention can significantly reduce the difference (absolute value) between the offset of the first polarizer and the offset of the second polarizer. Therefore, when the polarizer assembly of the embodiment of the present invention is applied to an image display device, the design advantage is very great.

Industrial availability The assembly of the polarizing plate of the present invention can be suitably used for image display devices, especially suitable for image display devices with cameras represented by smart phones, tablet PCs or smart watches.

10: The first polarizer 11: the first polarizer 12: the outer protective layer 13: the inner protective layer 14: the first adhesive layer 15: the through hole 20: the second polarizer 21: the second polarizer 22: the outer protective layer 23: inner protective layer 24: second adhesive layer 25: through hole 100: polarizing plate assembly 120: image display unit 130: glass plate 200: image display device A: distance (Figure 4), with birefringence Layer A (Figure 6) Ab ₁ , Ab ₂ : Absorption axis B: Substantially non-birefringent layer D: Offset L ₁ : Distance from the center of the polarizer in the longitudinal direction to the end in the longitudinal direction L ₂ : Long side direction from the center of the long side direction of the polarizer to the center of the through hole R: Reflective layer II: Line W ₁ : Distance W from the center of the short side direction of the polarizer to the end of the short side direction ₂ : The distance in the short-side direction from the center of the first polarizer and the second polarizer in the short-side direction to the center of the through hole

1 is a schematic plan view of a first polarizing plate and a second polarizing plate in a polarizing plate assembly according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view taken along line II-II of the first polarizer and the second polarizer in the assembly of the polarizer of Fig. 1, which corresponds to each arrangement position of the first polarizer and the second polarizer. Schematic cross-sectional view. 3 is a schematic cross-sectional view of an image display device including the assembly of the polarizing plate of FIG. 1. Fig. 4 is an enlarged cross-sectional view of an important part of the polarizing plate used in the assembly of the polarizing plate according to the embodiment of the present invention, which is offset in the through hole portion. 5 is a schematic plan view illustrating the formation position of the through hole in the polarizing plate used in the polarizing plate assembly of the embodiment of the present invention. 6 is a schematic perspective view of an example of the reflective polarizer of the second polarizer that can be used in the polarizer assembly of the embodiment of the present invention.

10: The first polarizer

15: Through hole

20: The second polarizer

25: Through hole

Ab ₁ , Ab ₂ : Absorption axis

II: Line

Claims (13)

A polarizing plate assembly is composed of a rectangular first polarizing plate arranged on the viewing side of an image display unit and a rectangular second polarizing plate arranged on the back side of the image display unit; The first polarizer has a first polarizer, a protective layer disposed on at least one side of the first polarizer, and a first adhesive layer disposed on the side of the image display unit; The second polarizer has a second polarizer, a protective layer disposed on at least one side of the second polarizer, a reflective polarizer disposed on the opposite side of the second polarizer from the image display unit, and a configuration The second adhesive layer on the side of the image display unit; The thickness of the first polarizer and the second polarizer are respectively 20 μm or less; The first polarizer has an absorption axis in the short-side direction, and the second polarizer has an absorption axis in the long-side direction; The first polarizing plate and the second polarizing plate have through holes at their respective ends or at positions corresponding to each other. _{The polarizing plate of claim 1, wherein the distance A 1} (μm) from the outermost part of the image display unit side of the first adhesive layer to the center of the first polarizer in the thickness direction, the first polarizer The thickness of the piece T _pol1 (μm), the creep value C _psa1 (μm/hr) of the first adhesive layer, the thickness T _psa1 (μm) of the first adhesive layer, and the protective layer in the first polarizer The thickness T _pro1 (μm) satisfies the following relationship: (A ₁ ×T _pol1 )×(C _psa1 ×T _psa1 )/T _pro1 =K ₁ ≦300×10 ² (μm ³ /hr) And, from the second _{The distance A 2} (μm) from the outermost part of the image display unit side of the adhesive layer to the center of the second polarizer in the thickness direction, the thickness T _pol2 (μm) of the second polarizer, and the second adhesive The creep value C _psa2 (μm/hr) of the agent layer, the thickness T _{psa2 (μm) of the second adhesive layer and the thickness T pro2} (μm) of the protective layer in the second polarizing plate satisfy the following relationship: ( A ₂ ×T _pol2 )×(C _psa2 ×T _psa2 )/T _pro2 = K ₂ ≦300×10 ² (μm ³ /hr). Such as the polarizing plate assembly of claim 2, wherein the aforementioned K ₁ and K ₂ are respectively 200×10 ² (μm ³ /hr) or less. The polarizing plate assembly of claim 2 or 3, wherein the creep value C _psa1 of the first adhesive layer is 100 (μm/hr) or less. The polarizing plate assembly of any one of claims 1 to 4, wherein the thickness T _pol2 of the aforementioned second polarizing member is 10 μm or less. Such as the polarizing plate assembly of any one of claims 2 to 5, wherein the aforementioned K ₁ and K ₂ are respectively 150×10 ² (μm ³ /hr) or less. The polarizing plate assembly of any one of claims 1 to 6, wherein the thickness T _pol1 of the first polarizing member is 10 μm or less. The polarizing plate assembly of any one of claims 1 to 7, wherein the thickness T _{psa1 of the} first adhesive layer and the thickness T _{psa2 of} the second adhesive layer are 10 μm-22 μm, respectively. The polarizing plate assembly of any one of claims 1 to 8, wherein the through hole is formed in the respective corners of the first polarizing plate and the second polarizing plate. Such as the polarizing plate assembly of claim 9, wherein when the first polarizer and the second polarizer are viewed from above, the distance from the center in the longitudinal direction to the end in the longitudinal direction is L ₁ , and the distance from the first polarizer and the second polarizer is L 1. 1 The distance in the long side direction from the center of the long side of the polarizer and the second polarizer to the center of the aforementioned through hole is L ₂ , so that from the center of the first polarizer and the second polarizer in the short side direction The distance from the end in the short-side direction is W ₁ , and the distance in the short-side direction from the center of the first polarizer and the second polarizer in the short-side direction to the center of the through hole is W ₂ In this case, the through hole is formed at a position where the first polarizer and the second polarizer satisfy 0.85≦L ₂ /L ₁ ≦0.99 and 0.50≦W ₂ /W ₁ ≦0.99. The polarizing plate assembly of any one of claims 1 to 10, wherein the diameter of the through hole is 10 mm or less. Such as the assembly of the polarizing plate of any one of claims 1 to 11, wherein the aspect ratios of the first polarizing plate and the second polarizing plate are 1.3 to 2.5, respectively. An image display device comprising an assembly of an image display unit and a polarizing plate as claimed in any one of claims 1 to 12; the first polarizing plate is arranged on the viewing side of the image display unit, and the second polarizing plate is arranged on The back side of the image display unit.

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