Polarizer

Abstract

[The technical problem to be solved] The objective of this invention is to obtain a polarizing plate in which the durability of both the polarizer and the retardation layer is improved. Technical means to solve the problem The present invention provides a polarizing plate, which consists of a polarizing film containing a dichroic azo dye, a first hardened layer, a second hardened layer, and a phase retardation layer containing a polymeric liquid crystal compound, which are sequentially deposited in contact. The first hardened layer is a hardened layer composed of polyvinyl alcohol resin, and the second hardened layer is a hardened layer composed of cationic polymeric material.

Description

[Technical Field]

[0001] This invention relates to a polarizing plate, and also to an image display device comprising the polarizing plate. [Previous Technology]

[0002] Conventionally, in image display devices, a method is employed to suppress the reduction in viewability caused by the reflection of external light by arranging an optically laminate with anti-reflective properties on the viewing side of the image display panel. Known optically laminates with anti-reflective properties include circular polarizing plates comprising polarizers and retardation layers.

[0003] When using an image display device in harsh environments, such as when immersed in warm water, the optical properties of the polarizer may easily degrade. Japanese Patent Application Publication No. 2013-105036 describes a method to obtain a polarizer with excellent durability by increasing the boric acid content in the polarizer.

[0003] [Previous Technical Documents]

[0003] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2013-105036

[0005] Furthermore, the optical properties of the retardation layer are easily degraded under harsh environments. The object of the present invention is to provide a polarizing plate with improved durability of both the polarizer and the retardation layer, and an image display device having the polarizing plate.

[0006] The present invention provides the polarizing plate and image display device illustrated below.

[0006] [1] A polarizing plate is formed by sequentially depositing a polarizer containing a dichroic azo pigment, a first hardened layer, a second hardened layer, and a phase retardation layer containing a polymeric liquid crystal compound in contact with each other.

[0006] The aforementioned first hardened layer is a hardened layer of polyvinyl alcohol resin composition.

[0006] The aforementioned second hardened layer is a hardened layer of a cationic polymeric composition.

[0006] [2] The polarizing plate as described in [1], wherein the aforementioned polyvinyl alcohol resin composition contains acetylated modified polyvinyl alcohol.

[0006] [3] The polarizing plate as described in [1] or [2], wherein the degree of saponification of the polyvinyl alcohol resin contained in the aforementioned polyvinyl alcohol resin composition is more than 85 mol% and less than 100 mol%.

[0006] [4] The polarizing plate as described in any one of [1] to [3], wherein the degree of polymerization of the polyvinyl alcohol resin contained in the aforementioned polyvinyl alcohol resin composition is more than 1,000 and less than 5,000.

[0006] [5] The polarizing plate as described in any one of [1] to [4], wherein the aforementioned polyvinyl alcohol resin composition does not contain aldehyde compounds, or contains 8.0 parts by mass or less of aldehyde compounds relative to 100 parts by mass of polyvinyl alcohol resin.

[0006] [6] The polarizing plate as described in any one of [1] to [5], wherein the aforementioned cationic polymeric composition contains an oxetane compound.

[0006] [7] The polarizing plate as described in [6], wherein the aforementioned cationic polymeric composition further contains an epoxy compound.

[0006] [8] The polarizing plate as described in [7], wherein the aforementioned cationic polymeric composition contains 10 to 2000 parts by mass of the aforementioned oxide compound relative to 100 parts by mass of the aforementioned epoxy compound.

[0006] [9] The polarizing plate as described in any one of [1] to [8], wherein the aforementioned cationic polymeric composition further contains a photosensitizer.

[0006]

[10] The polarizing plate as described in any one of [1] to [9], wherein the aforementioned phase difference layer comprises a 1 / 4 wavelength plate layer.

[0006]

[11] An image display device comprising a polarizing plate as described in any one of [1] to

[10] .

[0007] According to the present invention, a polarizing plate with improved durability of both the polarizer and the retardation layer can be provided, as well as an image display device having the polarizing plate. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a schematic cross-sectional view showing an example of the polarizing plate of the present invention.

Implementation Method

[0009] The following description of embodiments of the present invention is based on reference drawings, but the present invention is not limited to the following embodiments. In all the following drawings, the scale has been appropriately adjusted for easy understanding of the constituent elements, and the scale of each constituent element shown in the drawings may not be consistent with the scale of the actual constituent elements.

[0010] 〈Polarizing plate〉

[0010] The polarizing plate of the present invention will be described with reference to FIG1. ​​The polarizing plate 100 of the present invention is formed by sequentially depositing a polarizer 10 containing a dichroic azo dye, a first hardened layer 20, a second hardened layer 30, and a retardation layer 40 containing a polymeric liquid crystal compound in contact with each other. The polarizing plate 100 is, for example, a circular polarizing plate having a linear polarizer and a retardation layer. In this specification, a circular polarizing plate includes an elliptical polarizing plate. A circular polarizing plate can have an anti-reflective function in an image display device.

[0011] Due to the high linearity of the dichroic azo pigment contained in the polarizer, it is suitable for manufacturing polarizers with excellent polarization performance. However, even a very small amount of pigment diffuses outward from the polarizer, which may reduce the optical properties of the polarizer. This diffusion becomes significant, especially at high temperatures, leading to the problem of easy deterioration of the polarizer. A polarizing plate comprising a polarizer containing dichroic azo pigment, a first hardened layer consisting of a polyvinyl alcohol-based resin composition, and a second hardened layer consisting of a cationic polymeric composition in sequential contact can suppress the diffusion of dichroic azo pigment (especially thermal diffusion) and improve the durability of the polarizer. Even at a high temperature of, for example, 85°C, the polarization degree of the polarizing plate of the present invention does not reach 1.0.

[0012] On the other hand, in environments with high temperature and high humidity, the monomers in the phase retardation layer of the cured material containing polymeric liquid crystal compounds tend to diffuse, leading to a problem of phase retardation layer degradation. By depositing the phase retardation layer containing polymeric liquid crystal compounds into a second cured material layer through contact, the diffusion of monomers can be suppressed, thereby improving the durability of the phase retardation layer. Even in environments with high temperature and high humidity, such as 65°C and 90% relative humidity, the phase retardation value of the polarizing plate of the present invention at a wavelength of 550nm does not reach 2.5nm.

[0013] When viewed from above, the optical laminate may be square in shape, preferably square with a long side and a short side, and more preferably rectangular. Each layer constituting the optical laminate may have its corners rounded, its ends cut, or its openings made.

[0014] Optical laminates can be used in, for example, image display devices. Image display devices are not particularly limited, and examples include: organic electroluminescent (organic EL) display devices, inorganic electroluminescent (inorganic EL) display devices, liquid crystal display devices, field emission display devices, etc.

[0015] [Polarizing Film]

[0015] The polarizer may be an extended film adsorbed with bichromatic azo pigment, or a hardened material containing a polymeric liquid crystal compound and a bichromatic azo pigment.

[0016] The extended film adsorbed with a dichroic azo dye can be used, for example, as a polarizer obtained by dyeing a polyvinyl alcohol (hereinafter sometimes abbreviated as "PVA") resin film with a dichroic dye containing a dichroic azo dye and performing uniaxial extension.

[0017] Polyvinyl alcohol-based resins are obtained by saponifying polyvinyl acetate-based resins. Besides polyvinyl acetate homopolymers, polyvinyl acetate-based resins can be copolymers of vinyl acetate and other monomers that can be copolymerized with it. Examples of other monomers that can be copolymerized with vinyl acetate include: unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated urethane compounds, and (meth)acrylamide compounds containing ammonium groups.

[0018] The saponification degree of polyvinyl alcohol (PVA) resins is typically between 85 mol% and 100 mol%, preferably 98 mol% or higher. PVA resins can be modified, and aldehyde-modified polyvinyl formaldehyde, polyvinyl acetal, etc., can also be used. The average degree of polymerization of PVA resins is typically between 1000 and 10000, preferably between 1500 and 5000. The average degree of polymerization of PVA resins can be determined according to JIS K 6726 (1994). When the average degree of polymerization is less than 1000, it is difficult to obtain good polarization performance; when it exceeds 10000, the film processability may sometimes deteriorate.

[0019] Other methods for manufacturing linear polarizing plates containing polyvinyl alcohol-based resin films may include methods comprising the following steps: first, preparing a substrate film; coating a solution of a resin such as a polyvinyl alcohol-based resin onto the substrate film; and performing drying to remove the solvent, thereby forming a resin layer on the substrate film. A primer layer may be pre-formed on the surface of the substrate film where the resin layer is formed. Materials for the primer layer may include, for example, a resin obtained by cross-linking a hydrophilic resin used in linear polarizing films.

[0020] Examples of substrate films include: cyclic polyolefin resin films; cellulose acetate resin films containing resins such as cellulose triacetate and cellulose diacetate; polyester resin films containing resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resin films; (meth)acrylic resin films; and polypropylene resin films, which are thermoplastic resin films generally known in this art. From the viewpoint of thinning, the thickness of the substrate film is typically 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, even more preferably 40 μm or less, and particularly preferably 30 μm or less. Furthermore, it is typically 5 μm or more, and preferably 10 μm or more.

[0021] A hard coating may also be formed on the thermoplastic resin film. The hard coating may be formed on one or both sides of the thermoplastic resin film. By providing a hard coating, a thermoplastic resin film that improves hardness and scratch resistance can be formed.

[0022] Next, the amount of solvent, such as water, in the resin layer can be adjusted as needed. Then, the substrate film and the resin layer are uniaxially stretched. The resin layer is then dyed with a dichroic pigment to adsorb and align the dichroic pigment onto the resin layer. Alternatively, if necessary, the resin layer with the adsorbed and aligned dichroic pigment can be treated with a boric acid aqueous solution, followed by a washing step to remove the boric acid aqueous solution. This produces a polarizer with a resin layer adsorbed and aligned with a dichroic pigment. Each step can be performed using methods generally known.

[0023] The uniaxial stretching of the substrate film and resin layer can be performed before dyeing, during dyeing, or during boric acid treatment after dyeing, or uniaxial stretching can be performed separately in several of these stages. The substrate film and resin layer can be uniaxially stretched in the MD direction (film transport direction). In this case, uniaxial stretching can be performed between rollers with different circumferential speeds, or uniaxial stretching can be performed using hot rollers. Furthermore, the substrate film and resin layer can also be uniaxially stretched in the TD direction (perpendicular to the film transport direction). In this case, a so-called stretching method can be used. Furthermore, the stretching of the substrate film and resin layer can be dry stretching performed in the atmosphere, or wet stretching performed while the resin layer is swollen by a solvent. To exhibit the performance of the polarizer, the elongation ratio is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. There is no particular upper limit to the elongation ratio, but from the viewpoint of suppressing breakage, it is preferably 8 times or less.

[0024] The polarizer produced by the above method can be used as a linear polarizer either by peeling off the substrate film or by using the substrate film together. According to the above method, since the substrate film can be peeled off, the linear polarizer can be made thinner.

[0025] The thickness of the polarizer containing the polyvinyl alcohol resin film is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizer may be 5 μm or more, or 20 μm or less, 15 μm or less, or even 10 μm or less.

[0026] A polarizer can also be formed by coating an alignment film, for example, formed on a substrate film, with a composition containing a polymeric liquid crystal compound and a bichromatic azo pigment, and then polymerizing and curing the polymeric liquid crystal compound. Alternatively, a coating film containing a polymeric liquid crystal compound and a bichromatic azo pigment can be formed by coating a substrate film, and then extending this coating film together with the substrate film to form a polarizer. The material and thickness of the substrate film can be the same as those of the thermoplastic resin film described above. The polarizer can be used as a linear polarizer without peeling off the substrate film, or it can be used as a linear polarizer by peeling off the substrate film from the polarizer.

[0027] A polymerizable liquid crystal compound is a compound that has a polymerizable reactive group and exhibits liquid crystal properties. The polymerizable reactive group is a group that participates in the polymerization reaction, preferably a photopolymerizable reactive group. A photopolymerizable reactive group refers to a group that can participate in the polymerization reaction via an active free radical or acid generated from a photopolymerization initiator. Examples of photopolymerizable functional groups include: vinyl, ethoxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide, and oxetanyl. Among these, acryloxy, methacryloxy, ethoxy, ethylene oxide, and oxetanyl are preferred, with acryloxy being even more preferred. The type of polymerizable liquid crystal compound is not particularly limited; rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof can be used. The liquid crystal properties of polymeric liquid crystal compounds can be thermotropic liquid crystals or lyotropic liquid crystals, and in terms of phase sequence structure, they can be nematic liquid crystals or smectic liquid crystals.

[0028] Examples of compositions containing polymerizable liquid crystal compounds and bichromatic pigments, and methods for manufacturing polarizers using these compositions, include those described in Japanese Patent Application Publication Nos. 2013-37353, 2013-33249, and 2017-83843. In addition to polymerizable liquid crystal compounds and bichromatic pigments, the compositions used to form polarizers may also contain additives such as solvents, polymerization initiators, crosslinking agents, leveling agents, antioxidants, plasticizers, and sensitizers. These components may be used individually or in combination of two or more.

[0029] The polymerization initiator is a compound that enables the polymerization reaction of the polymerizable liquid crystal compound to proceed. From the viewpoint of initiating the polymerization reaction at lower temperatures, a photopolymerization initiator is preferred. Specifically, photopolymerization initiators that generate active free radicals or acids through the action of light can be listed, among which photopolymerization initiators that generate free radicals through the action of light are preferred. The content of the polymerization initiator relative to 100 parts by mass of the total amount of the polymerizable liquid crystal compound is preferably 1 part by mass to 10 parts by mass, and more preferably 3 parts by mass to 8 parts by mass. When within this range, the reaction of the polymerizable groups proceeds sufficiently and the alignment state of the liquid crystal compound is easily stabilized.

[0030] The thickness of the polarizer produced by the above method is usually less than 10 μm, preferably more than 0.5 μm and less than 8 μm, and even more preferably more than 1 μm and less than 5 μm.

[0031] The polarizer can also have a first hardened layer deposited in the presence of an alignment film. From the viewpoints of the accuracy and quality of the alignment angle, as well as the water resistance and bending resistance of the polarizer, the alignment film is preferably a photoalignment film. The thickness of the alignment film is preferably 10 nm to 5000 nm, more preferably 1000 nm or less, and can be 500 nm or less, or even 300 nm or less.

[0032] (Dichromatic azo pigment)

[0032] Examples of dichromatic azo pigments include monoazo pigments, diazo pigments, triazo pigments, tetraazo pigments and stilbene azo pigments, with diazo pigments and triazo pigments being preferred. Examples of such pigments include compounds represented by formula (I) (hereinafter also referred to as "compound (I)").

[0032] K1(-N=N-K2)pN=N-K3 (I)

[0032] In formula (I), K1 and K3 independently represent phenyl groups that may have substituents, naphthyl groups that may have substituents, or monovalent heterocyclic groups that may have substituents; K2 represents p-phenyl groups that may have substituents, naphth-1,4-diyl groups that may have substituents, or divalent heterocyclic groups that may have substituents; p represents an integer from 1 to 4; when p is an integer greater than 2, the plurality of K2s may be the same or different from each other. Within the range of absorption observed in the visible light region, the -N=N- bond can be substituted with -C=C-, -COO-, -NHCO-, or -N=CH- bonds.

[0033] Examples of monovalent heterocyclic groups include groups derived from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole by removing one hydrogen atom. Examples of divalent heterocyclic groups include groups derived from the aforementioned heterocyclic compounds by removing two hydrogen atoms.

[0034] The phenyl, naphthyl and monovalent heterocyclic groups in K1 and K3, and the p-phenyl, naphth-1,4-diyl and divalent heterocyclic groups in K2 may be arbitrarily represented by: alkyl groups having 1 to 4 carbon atoms; alkoxy groups having 1 to 4 carbon atoms such as methoxy, ethoxy, and butoxy; fluoroalkyl groups having 1 to 4 carbon atoms such as trifluoromethyl; cyano; nitro; halogen atoms; substituted or unsubstituted amino groups such as amino, diethylamino, and pyrrolidinyl (substituted amino group refers to an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms, or an amino group having 2 to 8 carbon atoms formed by the bonding of 2 substituted alkyl groups; unsubstituted amino group is -NH2), etc.

[0035] In compound (I), it is preferably a compound represented by any one of the following formulas (I-1) to (I-8).

[0035]

[0035]

[0035]

[0035]

[0035]

[0035]

[0035]

[0035]

[0035] In formulas (I-1) to (I-8),

[0035] B1 to B30 independently represent hydrogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, cyano groups, nitro groups, substituted or unsubstituted amino groups (the definitions of substituted and unsubstituted amino groups are as described above), chlorine atoms, or trifluoromethyl groups;

[0035] n1 to n4 represent integers from 0 to 3 independently;

[0035] When n1 is 2 or more, the multiple B2s can be the same or different from each other.

[0035] When n2 is 2 or more, the multiple B6s can be the same or different from each other.

[0035] When n3 is 2 or more, the multiple B9s can be the same or different from each other.

[0035] When n4 is 2 or more, the multiple B14s can be the same or different from each other.

[0036] The weight-average molecular weight of the dichromatic azo dye is typically between 300 and 2000, preferably between 400 and 1000. When the weight-average molecular weight of the dichromatic azo dye is below the above-mentioned upper limit, the dichromatic azo dye is prone to migration and diffusion outside the polarizer. Even in this case, a polarizing plate having a polarizer containing the dichromatic azo dye in sequential contact with a first hardened layer consisting of a hardened layer of polyvinyl alcohol resin can suppress the diffusion of the dichromatic azo dye (especially thermal diffusion) and improve the durability of the polarizer.

[0037] When the polarizer contains a polymerizable liquid crystal compound, the content of the dichroic azo pigment relative to 100 parts by mass of the polymerizable liquid crystal compound is, for example, 0.1 parts by mass to 50 parts by mass, more preferably 0.1 parts by mass to 20 parts by mass, and even more preferably 0.1 parts by mass to 12 parts by mass. When the content of the dichroic pigment is within this range, the alignment of the polymerizable liquid crystal compound is less likely to be disordered, and a polarizer with high alignment order can be obtained.

[0038] [First Hardened Layer]

[0038] The first hardened layer is a hardened layer composed of polyvinyl alcohol (PVA) resin. This first hardened layer, being a hardened layer composed of PVA resin, prevents the diffusion of dichroic azo pigments from the polarizer. In addition to protecting the surface of the polarizer, this first hardened layer, being a hardened layer composed of PVA resin, also exhibits excellent heat resistance. The first hardened layer typically has adhesion to the polarizer.

[0039] The polyvinyl alcohol-based resin composition may contain, in addition to partially saponified or fully saponified polyvinyl alcohol, modified polyvinyl alcohol such as carboxyl-modified polyvinyl alcohol, acetyl-modified polyvinyl alcohol, hydroxymethyl-modified polyvinyl alcohol, and amino-modified polyvinyl alcohol. From the viewpoint of suppressing the deterioration of polarizers, the polyvinyl alcohol-based resin composition preferably contains acetyl-modified polyvinyl alcohol. Commercially available polyvinyl alcohol-based resins can be used as the polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin composition. Commercially available products include, for example: "PVA-403," a partially saponified polyvinyl alcohol sold by Kuraray Co., Ltd.; "KL-506" and "KL-318," which are partially saponified polyvinyl alcohols with carboxyl modification; and "Z-100," "Z-200," and "Z-300," which are partially saponified polyvinyl alcohols with acetylated modification, sold by Mitsubishi Chemical Co., Ltd.

[0040] The degree of saponification of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is usually about 85 mol% to 100 mol%, preferably 90 mol% or more, and may be 95 mol% or more, or 98 mol% or more.

[0041] The average degree of polymerization of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is usually between 1,000 and 5,000, preferably between 1,500 and 3,000, and may be below 2,000 or below 1,500. When the average degree of polymerization is within this range, the deterioration of the polarizer can be well suppressed.

[0042] The content of polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin composition relative to the mass of the solids of the polyvinyl alcohol-based resin composition is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The solids of the polyvinyl alcohol-based resin composition may be entirely polyvinyl alcohol-based resin (i.e., 100% by mass). The term "solids of the polyvinyl alcohol-based resin composition" refers to the total amount of components remaining after excluding the solvent from the polyvinyl alcohol-based resin composition when the polyvinyl alcohol-based resin composition contains a solvent.

[0043] For the purpose of improving the coatability and processability of the cured polyvinyl alcohol (PVA) resin composition, the PVA resin composition preferably contains a solvent. Examples of solvents in the PVA resin composition include water, or a mixture of water and a hydrophilic organic solvent (e.g., alcohol solvent, ether solvent, ester solvent, etc.). When the PVA resin composition contains a solvent, the solid content is preferably 1% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 10% by mass or less.

[0044] Polyvinyl alcohol-based resin compositions may contain additives such as stabilizers, antioxidants, antistatic agents, ultraviolet absorbers, surface modifiers, and crosslinking agents as needed. Two or more additives may be used alone or in combination. The content of the additives relative to the mass of the solids in the polyvinyl alcohol-based resin composition is preferably between 0.1% and 10% by mass.

[0045] Examples of crosslinking agents include: amine compounds, aldehyde compounds, hydroxymethyl compounds, water-soluble epoxy resins, isocyanate compounds, and polyvalent metal salts. When using polyvinyl alcohol resin as the adhesive component, aldehyde compounds containing glyoxal, hydroxymethyl compounds containing hydroxymethyl melamine, and water-soluble epoxy resins can be used as crosslinking agents. Water-soluble epoxy resins can be, for example, polyamide polyamines that are reactants of polyalkylene polyamines such as diethylenetriamine and triethylenetetramine with dicarboxylic acids such as adipic acid, and polyamide epoxy resins obtained by reacting them with epichlorohydrin. A commercially available example of a water-soluble epoxy resin is "Sumirez Resin (registered trademark) 650 (30)" sold by Taoka Chemical Co., Ltd. Polyvinyl alcohol resin compositions may not contain crosslinking agents. However, from the perspective of suppressing the deterioration of polarizers, the content of aldehyde compounds in the polyvinyl alcohol resin composition is preferably 8.0 parts by weight or less, more preferably 5.0 parts by weight or less, or it may be free of aldehyde compounds.

[0046] The polyvinyl alcohol-based resin composition can be prepared by dissolving polyvinyl alcohol-based resin and optional additives in a solvent. By coating the polyvinyl alcohol-based resin composition onto the surface of one side of a polarizer and drying and removing the solvent, a first hardened layer belonging to the polyvinyl alcohol-based resin composition can be obtained.

[0047] The thickness of the first hardened layer is preferably 0.1 μm to 10 μm, and more preferably 0.3 μm to 2 μm. When the thickness of the first hardened layer is within the above range, the diffusion of the dichroic pigment from the polarizer can be effectively suppressed, and the polarizer can be made thinner.

[0048] [Phase Difference Layer]

[0048] The retardation layer may be one or two or more layers. The retardation layer may have: a substrate film supporting the retardation layer, and an adhesive layer for bonding multiple retardation layers, etc. The retardation layer may further include an alignment film. The retardation layer preferably includes a quarter-wavelength plate layer, and may further include at least one of a half-wavelength plate layer and a positive C layer. When the retardation layer includes a half-wavelength plate layer, the half-wavelength plate layer and the quarter-wavelength plate layer are sequentially stacked from the linear polarizer side. When the retardation layer includes a positive C layer, the quarter-wavelength plate layer and the positive C layer may be sequentially stacked from the linear polarizer side, or the positive C layer and the quarter-wavelength plate layer may be sequentially stacked from the linear polarizer side. The thickness of the phase retardation layer is, for example, 0.1 μm to 10 μm, preferably 0.5 μm to 8 μm, and even more preferably 1 μm to 6 μm.

[0049] The retardation layer is a cured material containing a polymeric liquid crystal compound. The retardation layer can be formed by coating a composition containing a polymeric liquid crystal compound onto a substrate film and then curing it. An alignment film can also be formed between the substrate film and the coated layer. The material and thickness of the substrate film can be the same as those of the aforementioned thermoplastic resin film. The retardation layer can also be assembled onto a polarizing plate in the form of an alignment film and a substrate film. In the retardation layer, the surface facing the polarizer is preferably a layer containing a cured material containing a polymeric liquid crystal compound. The surface of the retardation layer facing the polarizer can be the surface of the layer displaying the retardation, or it can be an alignment film.

[0050] In addition to the layer containing the cured polymeric liquid crystal compound, the phase retardation layer may also include a layer formed of a resin film. The resin film may be the aforementioned thermoplastic resin film.

[0051] The liquid crystal layer displaying the phase difference can be formed using commonly known liquid crystal compounds. There is no particular limitation on the type of liquid crystal compound contained in the composition containing the polymeric liquid crystal compound; rod-shaped liquid crystal compounds, disk-shaped liquid crystal compounds, and mixtures thereof can be used. The composition containing the polymeric liquid crystal compound may also contain a polymeric liquid crystal compound. Examples of liquid crystal compounds include those described in Japanese Patent Application Publication No. 11-513019, Japanese Patent Application Publication No. 2005-289980, Japanese Patent Application Publication No. 2007-108732, Japanese Patent Application Publication No. 2010-244038, Japanese Patent Application Publication No. 2010-31223, Japanese Patent Application Publication No. 2010-270108, Japanese Patent Application Publication No. 2011-6360, Japanese Patent Application Publication No. 2011-207765, Japanese Patent Application Publication No. 2016-81035, Japanese International Publication No. 2017 / 043438, and Japanese Patent Application Publication No. 2011-207765.

[0052] In addition to the liquid crystal compound, the composition containing the polymerizable liquid crystal compound may also contain: polymerization initiator, polymerizable monomer, surfactant, solvent, adhesion modifier, plasticizer, alignment agent, etc. Coating methods for the composition containing the polymerizable liquid crystal compound include commonly known methods such as die casting coating. Curing methods for the composition containing the polymerizable liquid crystal compound include commonly known methods such as irradiation with active energy rays (e.g., ultraviolet light).

[0053] A polarizing plate in which the absorption axis of the polarizer and the slow axis of the retardation layer are arranged at a predetermined angle has an anti-reflection function, that is, it functions as a circular polarizer. When the retardation layer includes a quarter-wavelength plate layer, the angle formed by the absorption axis of the polarizer and the slow axis of the quarter-wavelength plate layer can be 45°±10°. The retardation layer can have positive wavelength dispersion or negative wavelength dispersion. It is preferable that the quarter-wavelength plate layer has negative wavelength dispersion.

[0054] The alignment film system has an alignment constraint force that aligns the polymeric liquid crystal compound contained in the liquid crystal layer forming the phase difference on the alignment film to a desired direction. Examples of alignment films include: alignment polymer films formed from alignment polymers, photoalignment polymer films formed from photoalignment polymers, and trench alignment films having a raised or recessed pattern or a plurality of trenches on the film surface. The thickness of the alignment film is typically 0.01 μm to 10 μm, preferably 0.01 μm to 5 μm.

[0055] An orientation polymer film system can be formed by coating a composition in which the orientation polymer is dissolved in a solvent onto a substrate film, then removing the solvent and performing a brushing treatment as needed. The orientation restraint force can be arbitrarily adjusted by the surface condition of the orientation polymer or the brushing conditions.

[0056] A photo-alignment polymer film can be formed by coating a composition containing a polymer or monomer with photoreactive groups and a solvent onto a substrate film and then irradiating it with polarized light. In this case, the alignment constraint force can be arbitrarily adjusted by means of the polarized light irradiation conditions relative to the photo-alignment polymer.

[0057] The groove alignment film can be formed, for example, by the following methods: by exposing and developing an exposure mask with a patterned slit on the surface of a photosensitive polyimide film to form a raised pattern; by forming an uncured film of an active energy line curing resin on a plate-shaped master with grooves on its surface, and then transferring this film onto a substrate film and curing it; by forming an uncured layer of an active energy line curing resin on a substrate film, and by pressing a roller-shaped master with raised and recessed patterns against this layer to form a raised and recessed pattern and then curing it.

[0058] [Second Hardened Layer]

[0058] The second hardened layer is a hardened layer of a cationic polymeric composition. The second hardened layer typically has adhesion to both the first hardened layer and the retardation layer. The second hardened layer 30 can be bonded to adjacent first hardened layers 20 and retardation layers 40. The second hardened layer, being a cationic polymeric composition, prevents the diffusion of unpolymerized monomers from the retardation layer. In addition to protecting the surface of the retardation layer, the second hardened layer, being a cationic polymeric composition, also exhibits excellent water resistance. When the retardation layer is bonded to the polarizer or the first hardened layer via an adhesive layer or a free radical polymeric second hardened layer, it is difficult to suppress the diffusion of monomers from the retardation layer. Since the hydrophobic cationic polymeric resin can protect the dual-color pigment and the polyvinyl alcohol resin with excellent barrier properties, a polarizing plate with improved durability and thinner profile can be obtained by laminating the second hardened layer, which is a hardened layer of cationic polymeric composition, into the first hardened layer, which is a hardened layer of polyvinyl alcohol resin composition.

[0059] Cationic polymerizable compounds contained in cationic polymerizable compositions refer to compounds or oligomers that harden through cationic polymerization reactions caused by irradiation or heating with active energy lines such as ultraviolet light, visible light, electron beams, and X-rays. Examples include epoxy compounds, oxy compounds, and vinyl compounds. These polymerizable compounds can be used alone or in combination of two or more. In addition to cationic polymerizable compounds, cationic polymerizable compositions may also contain free radical polymerizable compounds as polymerizable compounds. Free radical polymerizable compounds are, for example, compounds in which polymerization reactions can be initiated by free radicals generated from photoradioactive polymerization initiators through light irradiation.

[0060] The content of the cationic polymeric compound contained in the cationic polymeric composition is preferably 80 parts by mass to 100 parts by mass relative to the total mass of the cationic polymeric composition, more preferably 90 parts by mass to 99.5 parts by mass, and even more preferably 95 parts by mass to 99 parts by mass. When the content of the cationic polymeric compound is within this range, a second hardened layer with excellent water resistance and excellent effect in preventing the diffusion of the two-color pigments outside the polarizer can be obtained.

[0061] The cationic polymerizable composition preferably contains a polymerizable compound having a cyclic ether structure as the polymerizable compound. Examples of cyclic ether structures include: ethylene oxide ring, oxo ring, tetrahydrofuran ring, and tetrahydropyran ring. From the viewpoint of suppressing monomer diffusion from the phase difference layer and water resistance, it is preferable to contain a polymerizable compound having a cyclic ether structure with 2 to 4 carbon atoms, and more preferably, an oxo compound.

[0062] Oxygen compounds are compounds having one or more oxygen groups (oxygen rings) within their molecules, and can be any of aliphatic, alicyclic, and aromatic compounds. Examples of oxygen compounds having one oxygen group include 3-ethyl-3-hydroxymethyloxo, 2-ethylhexyloxo, 3-ethyl-3-(phenoxymethyl)oxo, and 3-(cyclohexyloxy)methyl-3-ethyloxo. Furthermore, examples of oxygen compounds having two or more oxygen groups include 1,4-bis[{(3-ethyloxo-3-yl)methoxy}methyl]benzene (also known as "xylenedioxo") and bis(3-ethyl-3-oxo-methyl) ether. These oxygen compounds can be used alone or in combination of two or more. Oxygen compounds can be used as the main component of cationic polymerizable compounds, or they can be used in combination with epoxy compounds.

[0063] The oxygen compound is preferably an oxygen compound having two or more oxygen groups in its molecule. By containing this oxygen compound, a hardened material with high cross-linking density and compactness can be obtained. In combination with the first hardened material layer, a polarizing plate that effectively suppresses the diffusion of dichroic pigments from the polarizer and is not prone to changes in optical properties over time can be obtained.

[0064] The content of the oxygen compound relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition is, for example, 10 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more. When the content of the oxygen compound is at or above the above-mentioned lower limit, it becomes a second hardened layer with superior heat resistance and damp heat resistance. Therefore, in combination with the first hardened layer, the water resistance, heat resistance, and damp heat resistance of the polarizing plate can be effectively improved. This results in a polarizing plate that is less prone to changes in optical performance over time. The content of the oxygen compound relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less. Furthermore, the content of the oxygen and oxycarbon compounds can be a combination of the aforementioned lower and upper limits, preferably 30 to 90 parts by mass, and more preferably 40 to 85 parts by mass, relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition. The content of the oxygen and oxycarbon compounds relative to 100 parts by mass of the cationic polymeric composition is, for example, 25 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and for example, can be less than 100 parts by mass, preferably less than 90 parts by mass, and more preferably less than 85 parts by mass.

[0065] In addition to the oxygen and epoxide compounds, the cationic polymerizable composition preferably contains an epoxy compound as a polymerizable compound. An epoxy compound is a compound having one or more, preferably two or more, epoxy groups within its molecule. In the cationic polymerizable composition, relative to 100 parts by mass of the epoxy compound, it is preferable to contain 10 to 2000 parts by mass of the oxygen and epoxide compounds, more preferably 30 to 1000 parts by mass, and even more preferably 30 to 500 parts by mass.

[0066] Epoxy compounds may be used alone or in combination with two or more. Examples of epoxy compounds include: alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. From the viewpoint of weather resistance, curing speed, and adhesion, epoxy compounds preferably contain alicyclic epoxy compounds or aliphatic epoxy compounds, and more preferably contain alicyclic epoxy compounds.

[0067] An alicyclic epoxy compound is a compound having one or more epoxy groups bonded to an alicyclic ring within its molecule, preferably having two or more epoxy groups bonded to an alicyclic ring within its molecule. "Epoxy groups bonded to an alicyclic ring" refers to cross-linked oxygen atoms -O- in the structure represented by formula (II) below. In formula (I) below, m is an integer from 2 to 5.

[0067]

[0068] Compounds in which the base bond of (CH2)m in the above formula (II) excludes one or more hydrogen atoms and is bonded to other chemical structures can become alicyclic epoxy compounds. One or more hydrogen atoms in (CH2)m can be appropriately substituted by straight-chain alkyl groups such as methyl or ethyl.

[0069] From the viewpoint of increasing the glass transition temperature of the cured material, it is preferable to have an alicyclic epoxy compound having an epoxycyclopentane structure [where m=3 in formula (II) above] or an epoxycyclohexane structure [where m=4 in formula (II) above], and more preferably an alicyclic diepoxy compound represented by formula (IIA) below. The second cured layer, which is a cationic polymerizable composition and contains an alicyclic diepoxy compound represented by formula (IIA) below, has an increased glass transition temperature, which can suppress the diffusion of pigments at high temperatures.

[0070]

[0070] In formula (IIA), R1 and R2 independently represent hydrogen atoms or alkyl groups having 1 to 6 carbon atoms. When the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. The alkyl group having 1 to 6 carbon atoms may be a straight-chain or branched alkyl group. Examples of alkyl groups with an alicyclic structure include cyclopropyl, cyclobutyl, and cyclopentyl.

[0071] In formula (IIA), X represents an oxygen atom, an alkyl diester having 1 to 6 carbon atoms, or a group represented by any of the formulas (IIa) to (IId) below. Examples of alkyl diesters having 1 to 6 carbon atoms include methylene, ethyl, propane-1,2-diyl, etc.

[0071]

[0071]

[0071]

[0071]

[0072] When X in formula (IIA) is a base represented by any of formulas (IIa) to (IId), Y1 to Y4 in each formula are independently alkyldiyl groups with 1 to 20 carbon atoms. When the alkyldiyl group has 3 or more carbon atoms, it may have an alicyclic structure. a and b independently represent integers from 0 to 20.

[0073] Examples of alicyclic epoxides include compounds A through M listed below. The chemical formulas A through M in the following paragraphs correspond to compounds A through M, respectively.

[0073] A: 3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylic acid ester

[0073] B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexane carboxylic acid ester

[0073] C: Ethyl bis(3,4-epoxycyclohexane carboxylate),

[0073] D: Bis(3,4-epoxycyclohexylmethyl) adipate

[0073] E: Bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate,

[0073] F: Diethylene glycol bis(3,4-epoxycyclohexyl methyl ether),

[0073] G: Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether),

[0073] H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrihelica[5.2.2.5.2.2]cosicosane,

[0073] I: 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxane[5.5]undecane,

[0073] J: 4-Vinylcyclohexene dioxide,

[0073] K: Limonene Dioxide

[0073] L: Bis(2,3-epoxycyclopentyl) ether,

[0073] M: Dicyclopentadiene dioxide.

[0074]

[0074]

[0075]

[0076] For readily available applications, the alicyclic epoxy compound is preferably 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate. Furthermore, from the viewpoint of effectively inhibiting pigment diffusion, the 1,2-epoxy-4-(2-epoxyethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol is preferred. The alicyclic epoxy compound can be used alone or in combination with several different alicyclic epoxy compounds.

[0077] The content of the alicyclic epoxy compound is preferably 1 part by mass to 80 parts by mass relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition, more preferably 3 parts by mass to 70 parts by mass, and even more preferably 3 parts by mass to 60 parts by mass. When the content of the alicyclic epoxy compound is within this range, curing by irradiation with active energy rays such as ultraviolet light proceeds rapidly, and a hardened layer (second hardened layer) with excellent heat resistance and resistance to humid heat and sufficient hardness can be formed.

[0078] An aliphatic epoxy compound is a compound having at least one epoxy ring bonded to an aliphatic carbon atom within its molecule, preferably having two or more epoxy rings within its molecule. For example, an aliphatic epoxy compound has at least one ethylene oxide ring (a 3-membered cyclic ether) bonded to an aliphatic carbon atom within its molecule, preferably having two or more. Aliphatic epoxy compounds include, for example: monofunctional epoxy compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; difunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trifunctional or more functional epoxy compounds such as trimethylolpropane triglycidyl ether and neopentyl tetraglycidyl ether; and epoxy compounds such as 4-vinylcyclohexene dioxide and limonene dioxide, which have one epoxy group directly bonded to an alicyclic ring and an ethylene oxide ring bonded to an aliphatic carbon atom.

[0079] From the viewpoint that a cationic polymeric composition with low viscosity and easy coating can be obtained, it is preferred to be a difunctional epoxy compound (also known as "aliphatic dieoxy compound") having two ethylene oxide rings bonded to aliphatic carbon atoms in the molecule as represented by the following formula (III).

[0079]

[0079] In formula (III), Z represents an alkyl group having 1 to 9 carbon atoms, an alkylene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent group represented by the formula -CmH2m-Z1-CnH2n-. -Z1- represents -O-, -CO-O-, -O-CO-, -SO2-, -SO-, or CO-, and m and n each independently represent an integer of 1 or more. However, the sum of m and n is 9 or less.

[0080] The divalent alicyclic hydrocarbon group can be, for example, a divalent alicyclic hydrocarbon group with 4 to 8 carbon atoms, such as a divalent residual group represented by the following formula (IIIA).

[0080]

[0081] Specific examples of compounds represented by formula (III) can be listed as follows: diglycidyl ether of alkyl diol; diglycidyl ether of oligoalkyl diol with a repeat number of about 4; diglycidyl ether of alicyclic diol, etc.

[0082] Examples of diols (ethylene glycols) capable of forming aliphatic diepoxides represented by formula (III) include: ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1, Alkanediols such as 5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, and 1,9-nonanediol; oligoalkyl alkyldiols such as diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol; and alicyclic diols such as cyclohexanediol and cyclohexanediol.

[0083] From the viewpoint of obtaining a cationic polymeric composition with low viscosity and easy coating, the aliphatic epoxy compound preferably contains: 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether. Regarding maintaining optical properties, 1,6-hexanediol diglycidyl ether and neopentyl tetraethanolamine polyglycidyl ether are preferred. The aliphatic epoxy compound can be used alone or in combination with several different aliphatic epoxy compounds.

[0084] When the cationic polymeric composition contains an aliphatic epoxy compound, the content of the aliphatic epoxy compound relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition is, for example, 1 part by mass to 90 parts by mass, more preferably 1 part by mass to 40 parts by mass, more preferably 3 parts by mass to 30 parts by mass, even more preferably 5 parts by mass to 20 parts by mass, and particularly preferably 7 parts by mass to 15 parts by mass. When the content of the aliphatic epoxy compound is within this range, a cationic polymeric composition with low viscosity and easy coating can be formed.

[0085] Aromatic epoxy compounds are compounds having an aromatic ring and an epoxy group within their molecules. Specific examples include: bisphenol-type epoxy compounds or oligomers thereof, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenolic varnish-type epoxy resins, such as phenolic varnish epoxy resin, cresol phenolic varnish epoxy resin, and hydroxybenzaldehyde phenolic varnish epoxy resin; multifunctional epoxy compounds such as glycidyl ether of 2,2',4,4'-tetrahydroxydiphenylmethane and glycidyl ether of 2,2',4,4'-tetrahydroxydiphenyl ketone; and multifunctional epoxy resins such as epoxidized polyvinylphenol.

[0086] From the viewpoint of reducing the viscosity of cationic polymerizable compositions, the aromatic epoxy compound preferably contains at least one compound selected from the group consisting of: glycidyl ethers of phenols, glycidyl ethers of aromatic compounds having two or more alcoholic hydroxyl groups, glycidyl ethers of polyphenols, glycidyl esters of benzoic acids, glycidyl esters of polyacids, epoxides of styrene oxides, or divinylbenzene epoxides. Regarding improving the curability of cationic polymerizable compositions, the aromatic epoxy compound preferably has an epoxy equivalent of 80 to 500. The aromatic epoxy compound can be used alone or in combination with several different aromatic epoxy compounds.

[0087] Aromatic epoxy compounds may be commercially available, such as: Denacol EX-121, Denacol EX-141, Denacol EX-142, Denacol EX-145, Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, OnCoat EX-1020, OnCoat EX-1030, OnCoat EX-1040, OnCoat EX-1050, OnCoat EX-1051, OnCoat EX-1010, OnCoat EX-1011, OnCoat 1012 (all manufactured by Nagase Chemtex); Ogsol PG-100, Ogsol EG-200, Ogsol EG-210, Ogsol EG-250 (all manufactured by Osaka). Gas Chemicals (manufactured); HP4032, HP4032D, HP4700 (manufactured by DIC); ESN-475V (manufactured by Nippon Steel & Sumitomo Chemical); Epikote YX8800, jER 828EL (manufactured by Mitsubishi Chemical); Marproof G-0105SA, Marproof G-0130SP (manufactured by Nippon Oil Company); Epiclon N-665, Epiclon HP-7200 (manufactured by DIC); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501H, EPPN-501HY, EPPN-502H, NC-7000L (manufactured by Nippon Kayaku Co., Ltd.); Adeka Glycerol ED-501, Adeka Glycerol ED-502, Adeka Glycerol ED-509, Adeka Glycerol ED-529, Adeka Resin EP-4000, Adeka Resin EP-4005, Adeka Resin EP-4100, Adeka Resin EP-4901 (all manufactured by ADEKA); TECHMORE VG-3101L, EPOX-MKR710, EPOX-MKR151 (all manufactured by Printec), etc.

[0088] When the cationic polymeric composition contains aromatic epoxy compounds, the cationic polymeric composition becomes a hydrophobic resin, thereby the resulting hardened layer (second hardened layer) also becomes hydrophobic. Therefore, under high temperature and high humidity conditions, it can prevent moisture from intruding from the outside and effectively suppress the movement of the dichroic pigments contained in the polarizer.

[0089] The content of aromatic epoxy compounds relative to 100 parts by mass of all polymeric compounds contained in the cationic polymeric composition is preferably 1 part by mass and 70 parts by mass, more preferably 5 parts by mass and 60 parts by mass, even more preferably 7 parts by mass and 55 parts by mass, and particularly preferably 10 parts by mass and 50 parts by mass. When the content of aromatic epoxy compounds is within this range, the hydrophobicity of the second hardened layer can be improved, and the diffusion of the dichroic pigment to the outside of the polarizer under high temperature and high humidity conditions can be more effectively suppressed.

[0090] The hydrogenated epoxy compound is an epoxypropyl ether of a polyol having an alicyclic ring. It can be obtained by selectively hydrogenating an aromatic polyol to its aromatic ring in the presence of a catalyst and under pressure, and then epoxypropylating the resulting nucleohydrogenated polyhydroxy compound. Specific examples of aromatic polyols include, for example: bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; phenolic varnish-type resins such as phenolic varnish resins, cresol phenolic varnish resins, and hydroxybenzaldehyde phenolic varnish resins; and multifunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxydiphenyl ketone, and polyvinylphenol. An alicyclic polyol obtained by reacting epichlorohydrin with the aromatic ring of an aromatic polyol can be used to form an epoxypropyl ether. Among the hydrogenated epoxy compounds, a preferred example is the diglycidyl ether of hydrogenated bisphenol A.

[0091] The cationic polymeric composition may further contain other curing compounds besides those described above. Specific examples of other curing compounds include lactone compounds, cyclic acetal compounds, cyclic thioether compounds, spiroacetate compounds, and other cationic polymeric compounds besides those described above.

[0092] The cationic polymerizable composition preferably contains a polymerization initiator to initiate polymerization. The polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator. For example, when the cationic polymerizable composition contains oxygen compounds, epoxy compounds, etc., as polymerizable compounds, a photocationic polymerization initiator is preferably used.

[0093] Photocationic polymerization initiators are those that generate cationic species or Lewis acids by irradiation with active energy lines such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of cationic polymerizable compounds. Since photocationic polymerization initiators act as catalysts through light, they exhibit excellent stability and workability even when mixed with polymerizable compounds. Examples of compounds that generate cationic species or Lewis acids by irradiation with active energy lines include: onium salts of aromatic monazite or aromatic strontium salts, aromatic diazonium salts, and iron-aromatic hydrocarbon complexes.

[0094] Aromatic monazite salts are compounds having a diarylmonazite cation, typically including diphenylmonazite cations. Aromatic strontium salts are compounds having a triarylstrontium cation, typically including triphenylstrontium cations, 4,4'-bis(diphenylstrontium)diphenylsulfide cations, etc. Aromatic diazonium salts are compounds having a diazonium cation, typically including benzenediazonium cations. Iron-aromatic complexes are typically cyclopentadiene iron(II)aromatic cation complexes.

[0095] The above-mentioned cations and anions (negative ions) pair to form photocationic polymerization initiators. Examples of anions constituting photocationic polymerization initiators include: specific phosphorus anions [(Rf)nPF6-n]-, hexafluorophosphate anions PF6-, hexafluoroantimonate anions SbF6-, pentafluorohydroxyantimonate anions SbF5(OH)-, hexafluoroarsenate anions AsF6-, tetrafluoroborate anions BF4-, and tetra(pentafluorophenyl)borate anions B(C6F5)4-, etc. From the viewpoint of the curability of the polymerizable compound and the safety of the resulting second cured layer, specific phosphorus anions [(Rf)nPF6-n]- and hexafluorophosphate anions PF6- are preferred photocationic polymerization initiators.

[0096] Photocationic polymerization initiators can be used alone or in combination of different types. Among them, aromatic strontium salts also have ultraviolet absorption characteristics in the wavelength region around 300 nm, so they have excellent curing properties and can produce cured products with good mechanical strength and adhesion strength, thus they are preferred.

[0097] The content of the polymerization initiator in the cationic polymerizable composition is typically 0.5 parts by mass to 10 parts by mass relative to 100 parts by mass of the polymerizable compound, preferably 6 parts by mass or less, and more preferably 3 parts by mass or less. When the content of the polymerization initiator is within this range, the polymerizable compound can be sufficiently hardened, and the hardened layer formed by the obtained hardened product can be endowed with high mechanical strength and adhesion strength.

[0098] The cationic polymerizable composition may contain commonly used additives in the curable composition as needed. Examples of such additives include: ion traps, antioxidants, chain transfer agents, polymerization accelerators (polyols, etc.), sensitizers, sensitizing auxiliaries, light stabilizers, adhesion promoters, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, leveling agents, silane coupling agents, pigments, antistatic agents, ultraviolet absorbers, etc.

[0099] Examples of sensitizers include photosensitizers. Photosensitizers are compounds that exhibit maximum absorption at wavelengths longer than the maximum absorption wavelength exhibited by photocationic polymerization initiators, thereby promoting the polymerization initiation reaction initiated by the photocationic polymerization initiator. Furthermore, photosensitizing auxiliaries are compounds that further promote the effect of the photosensitizer. By formulating photosensitizers and photosensitizing auxiliaries, a hardened layer with desired properties can be formed even when the polarizing plate contains a film with low UV transmittance.

[0100] The photosensitizer is preferably a compound that exhibits maximum absorption in light with a wavelength longer than, for example, 380 nm. Examples of such photosensitizers include anthracene compounds as described below.

[0100] 9,10-Dimethoxyanthracene,

[0100] 9,10-Diethoxyanthracene,

[0100] 9,10-Dipropoxyanthracene,

[0100] 9,10-Diisopropoxyanthracene,

[0100] 9,10-Dibutoxyanthracene,

[0100] 9,10-Dipentoxyanthracene,

[0100] 9,10-Dihexyloxyanthracene,

[0100] 9,10-bis(2-methoxyethoxy)anthracene,

[0100] 9,10-bis(2-ethoxyethoxy)anthracene,

[0100] 9,10-bis(2-butoxyethoxy)anthracene,

[0100] 9,10-bis(3-butoxypropoxy)anthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-dimethoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-diethoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-dipropoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-diisopropoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-dibutoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-dipentoxyanthracene,

[0100] 2-Methyl- or 2-ethyl-9,10-dihexyloxyanthracene.

[0101] A leveling agent is an additive that adjusts the flowability of a curing component, thereby making the coating obtained by applying the component smoother. Examples of leveling agents include polysiloxane-based, polyacrylate-based, and perfluoroalkyl-based leveling agents, such as silane coupling agents. Commercially available leveling agents may also be used.

[0102] The content of the leveling agent relative to 100 parts by mass of the polymeric compound is preferably 0.01 parts by mass to 5 parts by mass, and more preferably 0.05 parts by mass to 3 parts by mass. When the content of the leveling agent is within this range, the second hardened layer tends to become smoother.

[0103] The thickness of the second hardened layer is preferably 0.1 μm to 10 μm, and more preferably 0.2 μm to 2 μm. When the thickness of the second hardened layer is within this range, it can further perform the function of protecting the phase retardation layer and preventing the diffusion of dichroic pigments from the polarizer, and achieve the thinning of the polarizer plate.

[0104] The second hardened layer system can be formed by coating an uncured second hardened layer forming composition onto the surface of the first hardened layer 20 or the phase retardation layer 40 that is in contact with the polarizer 10, or by dripping an uncured second hardened layer forming composition between the first hardened layer 20 and the phase retardation layer 40, and then overlapping the polarizer 10 and the phase retardation layer 40 with the first hardened layer 20 in between, and then pressing them together from above and below using, for example, a bonding roller, to harden the second hardened layer forming composition. The hardening process can be performed by irradiation with active energy lines (in the case of active energy line hardening compositions) or by heating (in the case of thermosetting compositions). The active energy lines can be irradiated from the polarizer 10 side or from the phase retardation layer 40 side.

[0105] When coating the composition for forming the uncured second hardened layer, various coating methods can be used, such as doctor blade, wire rod, die coater, corner wheel coater, gravure coater, etc. Alternatively, the adhesive can be poured into the interlayer to be bonded.

[0106] The irradiation conditions of the active energy line can be any suitable conditions that allow the aforementioned active energy line hardening composition to harden. For example, the accelerating voltage of the electron beam irradiation is preferably 5 kV to 300 kV, more preferably 10 kV to 250 kV. When the accelerating voltage is less than 5 kV, there is a risk that the electron beam may not reach the active energy line hardening composition, resulting in insufficient hardening. When the accelerating voltage exceeds 300 kV, the penetrating force through the sample is too strong, causing the electron beam to bounce back, which may damage the film or polarizer. The irradiation linear amount is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation linear amount is less than 5 kGy, the active energy line hardening composition becomes insufficiently hardened. When it exceeds 100 kGy, it may damage the retardation layer, resulting in a decrease in mechanical strength or yellowing, and the desired optical properties cannot be obtained.

[0107] Electron beam irradiation is usually carried out in an inert gas, but it can also be carried out in the atmosphere or under conditions where a small amount of oxygen is introduced, as needed.

[0108] In the UV-curing type, the light irradiation intensity of the active energy line curing composition is determined according to the composition and is not particularly limited, but is preferably 10 to 1000 mJ / cm². When the light irradiation intensity is less than 10 mJ / cm², the reaction time becomes too long; when it exceeds 1000 mJ / cm², the constituent materials of the composition may yellow due to the heat emitted from the light source and the heat generated by the adhesive during polymerization. The irradiation intensity is preferably in the wavelength region below 400 nm, and more preferably in the wavelength region of 280 to 320 nm. Irradiation is performed once or several times at this light irradiation intensity, and the cumulative light intensity is set in a manner that is preferably 10 mJ / cm² or more, and more preferably 100 to 1000 mJ / cm². When the cumulative light intensity of the above composition is less than 10 mJ / cm², the generation of active species from the polymerization initiator is insufficient, and the curing of the composition becomes inadequate. On the other hand, when the cumulative light intensity exceeds 1000 mJ / cm2, the irradiation time becomes extremely long, which is not conducive to improving productivity. At this time, the cumulative light intensity in which wavelength region (UVA (320 to 390 nm) or UVB (280 to 320 nm) etc.) must be used will vary depending on the type of membrane used or the combination of its components.

[0109] In this invention, the light source used for polymerizing and hardening the composition by irradiation with active energy lines is not particularly limited, and examples include: low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. From the viewpoint of energy stability or ease of use, an ultraviolet light source with a light emission distribution at a wavelength below 400 nm is preferred.

[0110] When using active energy line curing composition, heat treatment can also be performed simultaneously with or after irradiation with active energy line. Before forming the coating layer of the composition, one or both of the bonding surfaces can also be subjected to easy-adhesion treatment such as saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, or anchoring coating treatment.

[0111] The glass transition temperature of the second hardened layer is, for example, 0°C or higher, and may be 20°C or higher or 50°C or higher. The glass transition temperature of the second hardened layer is, for example, 150°C or lower.

[0112] The glass transition temperature of the second cured layer can be calculated by the following steps. A second cured layer is formed between two 25 μm thick extended films of cyclic polyolefin resin. The container containing the above-mentioned test sample is placed in a differential scanning calorimeter (DS, TA Instruments). While purging with nitrogen gas, the temperature is lowered from 20°C to -60°C. After reaching -60°C, it is held for 1 minute, and then the temperature is increased from -60°C to 150°C at a rate of 10°C / min. Once 150°C is reached, the temperature is immediately lowered to 20°C. Then, the midpoint glass transition temperature specified in JIS K 7121-1987 "Method for Determination of Glass Transition Temperature of Plastics" is obtained from the DSC curve obtained when the temperature is increased from -60°C to 150°C, and this is set as the glass transition temperature of the second cured layer.

[0113] From the viewpoint of improving the durability of the polarizing plate, the storage modulus of the second hardened layer at a temperature of 30°C is preferably 100 MPa or more, more preferably 1000 MPa or more, even more preferably 1500 MPa or more, and particularly preferably 2000 MPa or more. On the other hand, if the storage modulus of the second hardened layer is too high, the adhesive hardened layer becomes too hard, and the processability of the polarizing plate may sometimes decrease. Therefore, the storage modulus of the adhesive hardened layer at a temperature of 30°C is preferably 10000 MPa or less, more preferably 8000 MPa or less, and even more preferably 5000 MPa or less.

[0114] The storage modulus of the second hardened layer at a temperature of 80°C is, for example, 10 MPa or more or 20 MPa or more, preferably 100 MPa or more or 1000 MPa or more. The storage modulus of the second hardened layer at a temperature of 80°C is preferably 5000 MPa or less, more preferably 4000 MPa or less, and even more preferably 3500 MPa or less.

[0115] The storage modulus of the second hardened layer can be calculated by the following steps. A second hardened layer is formed between two cyclic polyolefin resin films with a thickness of 50 μm. This is cut into 5 mm × 30 mm pieces, and one of the cyclic polyolefin resin films is peeled off to obtain a second hardened layer with a resin film attached. With its long side as the stretching direction, the second hardened layer with a resin film attached is held in a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement & Control Co., Ltd. with the clamps spaced 2 cm apart. The stretching and shrinkage frequency is set to 10 Hz, and the heating rate is set to 10 °C / min. The storage modulus at each temperature is then calculated.

[0116] 〈Manufacturing Method of Optical Laminates〉

[0116] There is no particular limitation on the manufacturing method of the optical laminate. One type includes the following steps: coating a polyvinyl alcohol-based resin composition onto the surface of a polarizer and curing it to form a first cured layer; and depositing the first cured layer and the retardation layer formed on the surface of the polarizer with a cationic polymeric composition in between, and curing the cationic polymeric composition to form a second cured layer.

[0117] 〈Image Display Device〉

[0117] The image display device includes an image display panel and the aforementioned polarizing plate. In the image display device, the polarizing plate may be disposed in front of the image display panel (viewing side). The image display panel is not particularly limited, and examples include: liquid crystal display panel, organic electroluminescent (organic EL) display panel, inorganic electroluminescent (inorganic EL) display panel, plasma display panel, field emission display panel, etc. Alternatively, a circular polarizing plate may be disposed on the viewing side of an organic EL display device to construct the image display device.

[0118] The image display device of the present invention can be used as a portable device such as a smartphone or tablet computer, a television, a digital photo frame, an electronic signboard, a measuring instrument or measuring device, an office machine, a medical machine, a computer, etc. The image display device of the present invention exhibits excellent durability even when used in harsh environments.

[0118] [Example]

[0119] The present invention is described in more detail below with examples and comparative examples, but the invention is not limited to these examples. In this example, the polarizer, the first hardening layer, the second hardening layer and the phase difference layer shown below are used to fabricate the polarizer plate.

[0120] 〈Preparation of Laminations in Example 1〉

[0120] [Fabrication of Polarizing Film with Substrate Film]

[0120] A film with a hard coating on one side, made of polyethylene terephthalate (PET) with a thickness of 38 μm, is used as a substrate film. The hard-coated side of this substrate film is corona-treated to form a photoalignment film. A polarizer-forming composition, obtained by mixing a polymerizable liquid crystal compound, a dichroic azo dye, a polymerization initiator, a leveling agent, and a solvent, is coated onto the photoalignment film and dried. Then, UV irradiation is performed to form a polarizer. A surface protective film is then laminated to the substrate film side.

[0121] [Formation of the first hardened layer]

[0121] The polarizer side surface of the prepared polarizer with substrate film was subjected to corona treatment. To achieve a cured film thickness of 1.0 μm, a polyvinyl alcohol-based resin composition was coated onto the corona-treated polarizer side surface using a rod coating method (speed 30 mm / s). The corona treatment conditions were: output 800 W, processing speed 10 m / min, 1 cycle. The polyvinyl alcohol-based resin composition used was a composition obtained by preparing acetylated acetylated modified polyvinyl alcohol (trade name "Z-220", Mitsubishi Chemical Co., Ltd.) with pure water. Details of Z-220 are shown in Table 1. The coating layer of the polyvinyl alcohol-based resin composition was dried at 100°C for 2 minutes to obtain a polarizer with a first cured layer.

[0122] [Preparation of the phase difference layer]

[0122] An integral product comprising a first protective film / alignment film / quarter-wavelength plate / adhesive layer / positive C layer / alignment film / second protective film is prepared as a phase retardation layer. The quarter-wavelength plate and positive C layer are layers in which a composition containing a polymerizable liquid crystal compound is coated onto the alignment film, dried, and cured by UV irradiation. The first protective film is a 100 μm thick PET film, and the second protective film is a 38 μm thick PET film.

[0123] [Attachment: Bonding of the polarizer and phase retardation layer in the first hardened layer]

[0123] The first hardened layer side surface of the polarizer with the first hardened layer attached and the first protective film of the retardation layer were peeled off, and the exposed surfaces were subjected to corona treatment. The corona treatment conditions were 800W output, 10m / min processing speed, and one cycle. A UV-curable cationic polymeric composition was coated between the corona-treated first hardened layer and the retardation layer, and the two laminates were bonded using a laminator. The thickness of the second hardened layer was 1.5μm. The lamination conditions were a speed of 2.5m / min. UV irradiation was performed once using a UV irradiation device at 400mJ / cm². The lamp used was an "H Bulb" manufactured by Fusion UV Systems. The ambient temperature during UV irradiation was 23°C and the relative humidity was 55%RH. Through the above processing, the polarizing plate of Example 1 is obtained, in which a polarizing film containing a dichroic azo dye, a first hardened layer, a second hardened layer, and a phase retardation layer containing a polymeric liquid crystal compound are sequentially deposited in contact.

[0124] (Modulation of cationic polymeric components)

[0124] The cationic polymerizable composition was prepared by mixing the components shown in Table 2 below at the mixing ratios shown in Table 2 (in parts by mass) and then degassing. The cationic polymerization initiator (B-1) was prepared with a 50% propylene carbonate solution, and its solid content is expressed in Table 2. The glass transfer temperature and storage modulus were determined according to the description in [Second Cured Layer] above.

[0125] 〈Fabrication of Laminated Structures in Examples 2 to 7〉

[0125] Except for using the polyvinyl alcohol-based resin composition with the product name "Z-200" shown in Table 1 as the first hardened layer, the polarizing plate of Example 2 was prepared in the same manner as in Example 1. Except for further adding glyoxal to the polyvinyl alcohol-based resin composition with the dosage shown in Table 3, the polarizing plates of Examples 3 to 6 were prepared in the same manner as in Example 2. Except for using the polyvinyl alcohol-based resin composition with the product name "PVA117" shown in Table 1 as the first hardened layer, the polarizing plate of Example 7 was prepared in the same manner as in Example 1.

[0126] [Table 1]

[0127] [Table 2]

[0128] The compounds in Table 2 are as described below.

[0128] (Catonic polymeric compound (A))

[0128] A-1: 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (trade name: CEL2021P, manufactured by Daicel Inc.)

[0128] A-2: 1,2-Epoxy-4-(2-Epoxyethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (trade name: EHPE3150, manufactured by Daicel Inc.)

[0128] A-3: 3-Ethyl-3{[(3-ethyloxo-3-yl)methoxy]methyl}oxo (Trade name: OXT-221, manufactured by Dong-A Synthetic Co., Ltd.)

[0128] (Catonic polymerization initiator (B))

[0128] B-1: "CPI-100P", manufactured by Sun Apro Co., Ltd., 50% by mass solution

[0128] (Photosensitive adjuvant (C))

[0128] C-1: 1,4-Diethoxynaphthalene

[0129] 〈Comparative Example 1: Fabrication of Laminated Materials〉

[0129] A laminate without a first hardened layer and a second hardened layer, with a polarizer and a retardation layer bonded together through an adhesive layer, was prepared as Comparative Example 1 using the following steps. First, an adhesive sheet with an acrylic adhesive layer of 5 μm thickness, serving as the adhesive layer, was prepared between a lightly releaseable film and a heavily releaseable film. The polarizer side of the polarizer of the substrate film described in Example 1 was bonded to the exposed surface of the lightly releaseable film after the adhesive sheet was peeled off. Before bonding, the surface of the polarizer was subjected to one corona treatment at an output of 800 W and a processing speed of 10 m / min, and the surface of the adhesive layer was subjected to three corona treatments at an output of 280 W and a processing speed of 10 m / min. The exposed surface after the first protective film of the retardation layer described in Example 1 was peeled off was bonded to the exposed surface of the heavily releaseable film after the adhesive sheet was peeled off. Before bonding, the surface of the phase retardation layer was subjected to one corona treatment at an output of 800W and a processing speed of 10m / min, and the surface of the adhesive layer was subjected to three corona treatments at an output of 280W and a processing speed of 10m / min. This yielded the laminate of Comparative Example 1. Methods not specifically described are the same as in Example 1.

[0130] 〈Comparative Example 2: Fabrication of Laminated Materials〉

[0130] A laminate without a second hardened layer and with a polarizer and a retardation layer bonded together via an adhesive layer was prepared as Comparative Example 2. The laminate of Comparative Example 2 was obtained using the same method as the laminate of Comparative Example 1, except that the polarizer used was the same as the polarizer with the first hardened layer described in Example 2. Specifically, the adhesive layer was laminated onto the first hardened layer side of the polarizer with the first hardened layer described in Example 1, and then the 1 / 4 wavelength plate side of the retardation layer described in Example 1 was laminated onto the side of the adhesive layer opposite to the first hardened layer.

[0131] 〈Preparation of the Lamination Material in Comparative Example 3〉

[0131] A composite material containing a polarizer with a first hardened layer and a retardation layer bonded together with a second hardened layer and an adhesive layer was obtained as Comparative Example 3. First, a polarizer with a first hardened layer as in Example 2 was prepared. Corona treatment was applied to the first hardened layer side of the polarizer with the first hardened layer, and a cationic polymeric composition was coated between the corona-treated surface and the untreated cyclic olefin film. The two composite materials were then bonded together using a laminator. After the composition was hardened by irradiation with ultraviolet light to form a second hardened layer, the cyclic olefin film was peeled off. Next, the second hardened layer side of the polarizer was bonded to the exposed surface after the lightly peelable film of the adhesive sheet of Comparative Example 1 was peeled off. Then, the exposed surface after the first protective film of the retardation layer described in Example 1 was peeled off was bonded to the exposed surface after the heavily peelable film of the adhesive sheet was peeled off. The composite material of Comparative Example 3 was obtained by the above operations. The methods not specifically described are the same as those in Example 1 or Comparative Example 1.

[0132] 〈Durability Assessment of Polarizing Films and Phase Retardation Layers〉

[0132] The second protective film was peeled off from the laminate of the examples and comparative examples and bonded to an acrylic adhesive sheet (with release film) with a thickness of 15 μm. This laminate was cut to a size of 30 mm × 30 mm and bonded to an alkali-free glass (trade name: Eagle XG, 40 mm × 40 mm × 0.7 mm thickness) manufactured by Corning Corporation by peeling off the acrylic adhesive layer exposed by the release film. The sample was prepared by autoclaving at a temperature of 50°C.

[0133] [Measurement of polarization]

[0133] Each sample was placed in an oven set at a high temperature (85°C for drying) for 168 hours. The luminescence factor-corrected polarization (Py1) (%) before being placed in the oven and the luminescence factor-corrected polarization (Py2) (%) after being placed in the oven for 168 hours were measured using a spectrophotometer (V-7100 manufactured by Japan Spectrophotometer Co., Ltd.), and the change ΔPy was calculated according to the following formula.

[0133] △Py=|Py2-Py1|

[0133] The following criteria shall be used to evaluate △Py.

[0133] A: The change in polarization ΔPy did not reach 0.5.

[0133] B: The change in polarization ΔPy is greater than or equal to 0.5 but less than 1.0.

[0133] C: The change in polarization ΔPy is 1.0 or higher.

[0134] [Measurement of phase difference]

[0134] Test samples were prepared using the same method as described above. Each sample was placed in an oven set under high temperature and high humidity conditions (temperature 65°C, relative humidity 90%RH) for 168 hours. The in-plane phase difference value (Re1) (nm) at a wavelength of 550nm before being placed in the oven and the in-plane phase difference value (Re2) (nm) at a wavelength of 550nm after being placed in the oven for 168 hours were measured using a phase difference measuring device KOBRA-WPR (manufactured by Oji Measurement Equipment Co., Ltd.), and the change ΔRe was calculated according to the following formula.

[0134] △Re=|Re2-Re1|

[0134] The following criteria shall be used to evaluate △Re.

[0134] A: The change in phase difference ΔRe did not reach 0.5.

[0134] B: The change in phase difference ΔRe is greater than or equal to 0.5 but less than or equal to 2.5.

[0134] C: The change in phase difference ΔRe is 2.5 or more.

[0135] [Warm Water Immersion Test]

[0135] A sample of polarizing plate laminated onto alkali-free glass was prepared using the same method as described above. The sample was cut into strips of 50mm × 20mm with the absorption axis of the polarizer as the long side, and the dimensions along the long side were accurately measured. Holding the sample by one short side with a gripper, approximately 80% of the long side was immersed in a 60°C water bath for 3 minutes. The sample was then removed from the water bath and the water was wiped off. Due to the immersion in warm water, the polarizer of the polarizing plate shrank. The degree of shrinkage of the polarizer was measured as the distance from one end of the sample (one end of the glass) to one end of the shrunken polarizer at the center of the short side of the sample. The measured values ​​were evaluated using the following criteria.

[0135] A: The distance from one end of the sample to one end of the polarizer is less than 3mm.

[0135] B: The distance from one end of the sample to one end of the polarizer is greater than 3mm.

[0136] [Table 3]

[0137] A polarizing plate is deposited in sequence with a first hardened layer, a second hardened layer, and a retardation layer. The first hardened layer is a hardened layer of a polyvinyl alcohol-based resin composition, and the second hardened layer is a hardened layer of a cationic polymeric composition. The polarizing plate exhibits a small ΔPy at 85°C, suggesting that pigment diffusion in the polarizing plate is suppressed at high temperatures. Furthermore, the polarizing plate also exhibits a small ΔRe at 65°C and 90% RH, indicating that monomer diffusion in the retardation layer is suppressed under high temperature and high humidity conditions. Moreover, it is known that water resistance is improved when the polyvinyl alcohol-based resin composition contains acetyl-modified polyvinyl alcohol.

Claims

1. A polarizing plate comprising a polarizer containing a bichromatic azo dye, a first hardened layer, a second hardened layer, and a phase retardation layer containing a polymerizable liquid crystal compound, wherein the first hardened layer is a hardened layer of a polyvinyl alcohol-based resin composition, the second hardened layer is a hardened layer of a cationic polymeric composition, the degree of polymerization of the polyvinyl alcohol-based resin contained in the polyvinyl alcohol-based resin composition is 1000 to 5000, and the polyvinyl alcohol-based resin composition contains acetylated modified polyvinyl alcohol.

2. The polarizing plate as claimed in claim 1, wherein the degree of saponification of the polyvinyl alcohol resin contained in the aforementioned polyvinyl alcohol resin composition is 85 moles or more and 100 moles or less.

3. The polarizing plate as claimed in claim 1 or 2, wherein the aforementioned polyvinyl alcohol resin composition is free of aldehyde compounds, or contains 8.0 parts by mass or less of aldehyde compounds relative to 100 parts by mass of polyvinyl alcohol resin.

4. The polarizing plate as claimed in claim 1 or 2, wherein the aforementioned cationic polymeric composition contains an oxetane compound.

5. The polarizing plate as claimed in claim 4, wherein the aforementioned cationic polymeric composition further contains an epoxy compound.

6. The polarizing plate as claimed in claim 5, wherein the aforementioned cationic polymeric composition contains 10 to 2000 parts by mass of the aforementioned oxide compound relative to 100 parts by mass of the aforementioned epoxy compound.

7. The polarizing plate as claimed in claim 1 or 2, wherein the aforementioned cationic polymeric composition further contains a photosensitizer.

8. The polarizing plate as claimed in claim 1 or 2, wherein the aforementioned phase difference layer comprises a quarter-wavelength plate layer.

9. An image display device comprising a polarizing plate as described in any one of claims 1 to 8.

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