polarizing plate

Abstract

To obtain a polarizing plate whose durability of both a polarizer and a retardation layer is improved.SOLUTION: Provided is a polarizing plate 100 in which a polarizer 10 containing a dichroic azo dye, a first cured material layer 20, a second cured material layer 30, and a retardation layer 40 containing a cured product of a polymerizable liquid crystal compound are in contact with each other and laminated in this order. The first cured material layer is the cured material layer of a polyvinyl alcohol-based resin composition, and the second cured material layer is the cured material layer of a cationic polymerization composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate, and also to an image display device including this polarizing plate. [Background technology]

[0002] Conventionally, in image display devices, a method has been employed in which an optical laminate with anti-reflective properties is placed on the viewing side of the image display panel to suppress the reduction in visibility due to the reflection of external light. As an optical laminate with anti-reflective properties, a circular polarizer containing a polarizer and a phase difference layer is known.

[0003] When image display devices are used in harsh environments, there is a problem that the optical properties of polarizers tend to deteriorate. Japanese Patent Publication No. 2013-105036 describes that a polarizer with excellent durability can be obtained by increasing the boric acid content in the polarizer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-105036 [Overview of the project] [Problems that the invention aims to solve]

[0005] Furthermore, the optical properties of the phase difference layer tend to deteriorate under harsh environments. The present invention aims to provide a polarizing plate in which both the polarizer and the phase difference layer have improved durability, and an image display device equipped therewith. [Means for solving the problem]

[0006] The present invention provides a polarizing plate and an image display device as illustrated below. [1] A polarizer containing a dichroic azo dye, a first cured layer, a second cured layer, and a phase difference layer containing a cured polymerizable liquid crystal compound are stacked in this order in contact with each other. The first cured layer is a cured layer of a polyvinyl alcohol-based resin composition. The aforementioned second cured layer is a polarizing plate, which is a cured layer of a cationic polymerizable composition. [2] The polyvinyl alcohol-based resin composition comprises acetoacetyl-modified polyvinyl alcohol, as described in [1]. [3] The polarizing plate according to [1] or [2], wherein the degree of saponification of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is 85 mol% or more and 100 mol% or less. [4] The polarizing plate according to any one of [1] to [3], wherein the degree of polymerization of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is 1000 or more and 5000 or less. [5] The polarizing plate according to any one of [1] to [4], wherein the polyvinyl alcohol-based resin composition does not contain an aldehyde compound, or contains 8.0 parts by mass or less of an aldehyde compound per 100 parts by mass of the polyvinyl alcohol-based resin. [6] The cationic polymerizable composition comprises an oxetane compound, and is a polarizing plate according to any one of [1] to [5]. [7] The polarizing plate according to [6], further comprising an epoxy compound in the cationic polymerizable composition. [8] The cationic polymerizable composition comprises 10 to 2000 parts by mass of the oxetane compound per 100 parts by mass of the epoxy compound, the polarizing plate according to [7]. [9] The polarizing plate according to any one of [1] to [8], further comprising a photosensitizer in the cationic polymerizable composition.

[10] The polarizing plate according to any one of [1] to [9], wherein the phase difference layer includes a quarter-wave plate layer. An image display device including a polarizing plate as described in any of

[11] [1] to

[10] . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a polarizing plate in which both the polarizer and the phase difference layer have improved durability, and an image display device equipped therewith. [Brief explanation of the drawing]

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

Embodiments for Carrying out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the following drawings, the scale is appropriately adjusted for easy understanding of each component, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[0010] <Polarizing plate> The polarizing plate according to the present invention will be described with reference to FIG. 1. The polarizing plate 100 according to the present invention includes a polarizer 10 containing a dichroic azo dye, a first cured product layer 20, a second cured product layer 30, and a retardation layer 40 containing a cured product of a polymerizable liquid crystal compound, which are laminated in this order. The polarizing plate 100 is, for example, a circular polarizing plate including a linear polarizer and a retardation layer. In this specification, the circular polarizing plate includes an elliptical polarizing plate. The circular polarizing plate can have an antireflection function in an image display device.

[0011] The dichroic azo dye contained in the polarizer is suitable for producing a polarizer with excellent polarization performance due to its high linearity. However, even a very small amount of the dye diffusing outside the polarizer can reduce the optical properties of the polarizer. Particularly in a high-temperature environment, this diffusion is significant, and there is a problem that the polarizer is likely to deteriorate. A polarizing plate having a structure in which a polarizer containing a dichroic azo dye, a first cured product layer which is a cured product layer of a polyvinyl alcohol-based resin composition, and a second cured product layer which is a cured product layer of a cationic polymerizable composition are in contact in this order can suppress the diffusion (particularly thermal diffusion) of the dichroic azo dye and improve the durability of the polarizer. The polarizing plate according to the present invention has, for example, a change amount of the degree of polarization of the polarizing plate less than 1.0 even when placed in a high-temperature environment of 85°C.

[0012] On the other hand, the phase difference layer containing a cured polymerizable liquid crystal compound had the problem that monomers easily diffused under high temperature and high humidity conditions, causing the phase difference layer to deteriorate easily. By laminating the phase difference layer containing a cured polymerizable liquid crystal compound with a second cured layer in contact, monomer diffusion can be suppressed, and the durability of the phase difference layer can be improved. The polarizing plate according to the present invention exhibits a change in phase difference value of less than 2.5 nm at a wavelength of 550 nm for a quarter-wave plate, even when placed in a high temperature and high humidity environment such as 65°C and 90% relative humidity.

[0013] The optical laminate may, in plan view, be, for example, rectangular, preferably rectangular with a long side and a short side, and more preferably rectangular. Each layer constituting the optical laminate may have rounded corners, notched edges, or perforated edges.

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

[0015] [polarizer] The polarizer may be a stretched film on which a dichroic azo dye is adsorbed, or a cured product of a composition containing a polymerizable liquid crystal compound and a dichroic azo dye.

[0016] As a stretched film on which a dichroic azo dye is adsorbed, for example, a polarizer obtained by dyeing a polyvinyl alcohol (hereinafter sometimes abbreviated as "PVA")-based resin film with a dichroic dye containing a dichroic azo dye and then uniaxially stretching it can be used.

[0017] Polyvinyl alcohol-based resins are obtained by saponifying polyvinyl acetate-based resins. Polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate with other monomers copolymerizable thereto. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth)acrylamide compounds having an ammonium group.

[0018] The degree of saponification of the polyvinyl alcohol resin is usually around 85 mol% to 100 mol%, preferably 98 mol% or higher. The polyvinyl alcohol resin may be modified, and polyvinyl formal, polyvinyl acetal, etc., modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can be determined in accordance with JIS K 6726 (1994). If the average degree of polymerization is less than 1000, it is difficult to obtain desirable polarization performance, and if it exceeds 10000, the film processability may be poor.

[0019] Other methods for manufacturing linear polarizing plates, including polyvinyl alcohol-based resin films, include a method that first prepares a base film, applies a resin solution such as a polyvinyl alcohol-based resin onto the base film, and then removes the solvent by drying or other means to form a resin layer on the base film. A primer layer can be formed in advance on the surface of the base film where the resin layer will be formed. Examples of materials for the primer layer include a resin obtained by crosslinking a hydrophilic resin used in linear polarizers.

[0020] Examples of base films include thermoplastic resin films known in this field, such as cyclopolyolefin resin films; cellulose acetate resin films containing resins such as triacetylcellulose and diacetylcellulose; 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. From the viewpoint of thinning, the thickness of the base film is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, even more preferably 40 μm or less, and still more preferably 30 μm or less, and usually 5 μm or more, preferably 10 μm or more.

[0021] A hard coat layer may be formed on the thermoplastic resin film. The hard coat layer may be formed on one side of the thermoplastic resin film or on both sides. By providing a hard coat layer, a thermoplastic resin film with improved hardness and scratch resistance can be obtained.

[0022] Next, the amount of solvent, such as water, in the resin layer is adjusted as needed. Then, the base film and the resin layer are uniaxially stretched. Subsequently, the resin layer is dyed with a dichroic dye to adsorb and orient the dichroic dye onto the resin layer. If necessary, the resin layer with the adsorbed and oriented dichroic dye is treated with an aqueous boric acid solution, and a washing step is performed to wash off the aqueous boric acid solution. This produces a polarizer, which is a resin layer with the adsorbed and oriented dichroic dye. Known methods can be used for each step.

[0023] Uniaxial stretching of the base film and resin layer may be performed before dyeing, during dyeing, or during the boric acid treatment after dyeing, or uniaxial stretching may be performed at each of these multiple stages. The base film and resin layer may be uniaxially stretched in the MD direction (film transport direction), in which case uniaxial stretching may be performed between rolls with different peripheral speeds, or uniaxial stretching may be performed using a heated roll. The base film and resin layer may also be uniaxially stretched in the TD direction (direction perpendicular to the film transport direction), in which case the so-called tenter method can be used. Furthermore, the stretching of the base film and resin layer may be dry stretching performed in air, or wet stretching performed with the resin layer swollen with a solvent. In order to exhibit polarizer performance, the stretching ratio should be 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 stretching ratio, but from the viewpoint of suppressing breakage, etc., 8 times or less is preferred.

[0024] The polarizer produced by the above method may be used as a linear polarizer with or without the base film. Because the base film can be removed using the above method, the linear polarizer can be made thinner.

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

[0026] A polarizer can also be formed, for example, by coating an alignment film formed on a base film with a composition containing a polymerizable liquid crystal compound and a dichroic azo dye, and polymerizing and curing the polymerizable liquid crystal compound. Alternatively, a polarizer may be formed by coating a base film with a composition containing a polymerizable liquid crystal compound and a dichroic azo dye to form a coating film, and then stretching this coating film together with the base film. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above. The polarizer may be used as a linear polarizer without peeling off the base film, or it may be used as a linear polarizer after peeling off the base 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, and is preferably a photopolymerizable reactive group. A photopolymerizable reactive group is a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator. Examples of photopolymerizable functional groups include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, acryloyloxy groups, methacryloyloxy groups, oxyranyl groups, and oxetanyl groups. Among these, acryloyloxy groups, methacryloyloxy groups, vinyloxy groups, oxyranyl groups, and oxetanyl groups are preferred, and acryloyloxy groups are more preferred. The type of polymerizable liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof can be used. The liquid crystal properties of the polymerizable liquid crystal compound may be thermotropic or lyotropic, and the phase ordered structure may be nematic or smectic.

[0028] Examples of compositions containing polymerizable liquid crystal compounds and dichroic dyes, and methods for producing polarizers using these compositions, can be found in Japanese Patent Publication No. 2013-37353, Japanese Patent Publication No. 2013-33249, Japanese Patent Publication No. 2017-83843, and others. In addition to polymerizable liquid crystal compounds and dichroic dyes, compositions for forming polarizers may further 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] A polymerization initiator is a compound capable of initiating the polymerization reaction of a polymerizable liquid crystal compound. From the viewpoint of initiating the polymerization reaction under lower temperature conditions, a photopolymerization initiator is preferred. Specifically, photopolymerization initiators that can generate active radicals or acids upon the action of light are mentioned, and among these, photopolymerization initiators that generate radicals upon the action of light are preferred. The content of the polymerization initiator is preferably 1 to 10 parts by mass, and more preferably 3 to 8 parts by mass, per 100 parts by weight of the total amount of the polymerizable liquid crystal compound. Within this range, the reaction of the polymerizable groups proceeds sufficiently, and the orientation state of the liquid crystal compound is easily stabilized.

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

[0031] The polarizer may have an orientation film while the first cured layer is laminated. As the orientation film, an optical orientation film is preferred from the viewpoint of accuracy and quality of the orientation angle, as well as the water resistance and flexibility of the polarizer. The thickness of the orientation film is preferably 10 nm to 5000 nm, more preferably 1000 nm or less, and may be 500 nm or less, or 300 nm or less.

[0032] (Dichroic azo dyes) Examples of the dichroic azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, stilbene azo dyes and the like, with bisazo dyes and trisazo dyes being preferred. For example, a compound represented by the formula (I) (hereinafter also referred to as "compound (I)") can be mentioned. K 1 (-N=N-K 2 ) p -N=N-K 3 (I) [In the formula (I), K 1 and K 3 each independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent or a monovalent heterocyclic group which may have a substituent. K 2 represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent or a divalent heterocyclic group which may have a substituent. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of K 2 may be the same as or different from each other. In the range showing absorption in the visible region, the -N=N- bond may be replaced by a -C=C-, -COO-, -NHCO-, -N=CH- bond.]

[0033] Examples of the monovalent heterocyclic group include a group obtained by removing one hydrogen atom from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, benzoxazole and the like. Examples of the divalent heterocyclic group include a group obtained by removing two hydrogen atoms from the heterocyclic compound.

[0034] K 1 and K 3 The phenyl group, naphthyl group and monovalent heterocyclic group in, and K 2The p-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in this compound may optionally have substituents such as C1-C4 alkyl groups; C1-C4 alkoxy groups such as methoxy, ethoxy, and butoxy groups; C1-C4 fluorinated alkyl groups such as trifluoromethyl groups; cyano groups; nitro groups; halogen atoms; and substituted or unsubstituted amino groups such as amino groups, diethylamino groups, and pyrrolidino groups (a substituted amino group means an amino group having one or two C1-C6 alkyl groups, or an amino group in which two substituted alkyl groups are bonded to each other to form a C2-C8 alkanediyl group. An unsubstituted amino group is -NH2).

[0035] Among the compounds (I), compounds represented by any of the following formulas (I-1) to (I-8) are preferred. [ka] [In equations (I-1) to (I-8), B1 to B30 independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of substituted and unsubstituted amino groups are as described above), a chlorine atom, or a trifluoromethyl group. n1 to n4 represent integers from 0 to 3, independently of each other. If n1 is 2 or more, multiple B 2 They may be the same or different from each other. If n2 is 2 or more, multiple B 6 They may be the same or different from each other. If n3 is 2 or more, multiple B 9 They may be the same or different from each other. If n4 is 2 or more, multiple B 14 They may be the same or different from each other.

[0036] The weight-average molecular weight of the dichroic azo dye is usually between 300 and 2000, preferably between 400 and 1000. When the weight-average molecular weight of the dichroic azo dye is below the above upper limit, the dichroic azo dye is more mobile and more likely to diffuse out of the polarizer. Even in such cases, a polarizer having a configuration in which the polarizer containing the dichroic azo dye and the first cured layer, which is a cured layer of a polyvinyl alcohol-based resin composition, are in contact in this order can suppress the diffusion of the dichroic 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 dye is, for example, 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the polymerizable liquid crystal compound, preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 12 parts by mass or less. When the content of the dichroic dye is within this range, it is less likely to disrupt the orientation of the polymerizable liquid crystal compound, and a polarizer with a high degree of orientational order can be obtained.

[0038] [First cured material layer] The first cured layer is a cured layer of a polyvinyl alcohol-based resin composition. The first cured layer, which is a cured layer of a polyvinyl alcohol-based resin composition, can prevent the diffusion of dichroic azo dye from the polarizer. The first cured layer, which is a cured layer of a polyvinyl alcohol-based resin composition, protects the surface of the polarizer and also has excellent heat resistance. The first cured layer usually has adhesion to the polarizer.

[0039] The polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition may include not only partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, but also modified polyvinyl alcohol resins such as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. From the viewpoint of suppressing the degradation of polarizers, it is preferable that the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition contains acetoacetyl group-modified polyvinyl alcohol. Commercially available polyvinyl alcohol resins may be used as the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition. Examples of commercially available products include "PVA-403," a partially saponified polyvinyl alcohol sold by Kuraray Co., Ltd., "KL-506" and "KL-318," carboxyl group-modified partially saponified polyvinyl alcohols, and "Z-100," "Z-200," and "Z-300," acetoacetyl group-modified partially saponified polyvinyl alcohols sold by Mitsubishi Chemical Corporation.

[0040] The degree of saponification of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is usually around 85 mol% to 100 mol%, preferably 90 mol% or more, and may also 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 1000 to 5000, preferably 1500 to 3000, and may be 2000 or less, or 1500 or less. When the average degree of polymerization is within this range, the degradation of the polarizer can be effectively suppressed.

[0042] The amount of polyvinyl alcohol resin contained in the polyvinyl alcohol 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, relative to the mass of the solids content of the polyvinyl alcohol resin composition. The solids content of the polyvinyl alcohol resin composition may be entirely polyvinyl alcohol resin (i.e., 100% by mass). The solids content of the polyvinyl alcohol resin composition refers to the total amount of components excluding the solvent from the polyvinyl alcohol resin composition, if the polyvinyl alcohol resin composition contains a solvent.

[0043] It is preferable that the polyvinyl alcohol-based resin composition contains a solvent, as this improves the applicability and handling properties when preparing cured products of the polyvinyl alcohol-based resin composition. Examples of solvents in the polyvinyl alcohol-based resin composition include water or a mixed solvent of water and a hydrophilic organic solvent (e.g., alcohol solvent, ether solvent, ester solvent, etc.). When the polyvinyl alcohol-based resin composition contains a solvent, its solid content is preferably 1% by mass or more and 30% by mass or less, and more preferably 2% by mass or more and 10% by mass or less.

[0044] The polyvinyl alcohol-based resin composition may optionally contain additives such as stabilizers, antioxidants, antistatic agents, ultraviolet absorbers, surface modifiers, and crosslinking agents. Additives can be used individually or in combination of two or more. The content of the additives is preferably 0.1% to 10% by mass, relative to the mass of the solid content of the polyvinyl alcohol-based resin composition.

[0045] Examples of crosslinking agents include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, and polyvalent metal salts. When polyvinyl alcohol-based resins are used as adhesive components, aldehyde compounds such as glyoxal, methylol compounds such as methylolmelamine, and water-soluble epoxy resins can be used as crosslinking agents. Water-soluble epoxy resins can be polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines, which are reaction products of polyalkylene polyamines such as diethylenetriamine and triethylenetetramine with dicarboxylic acids such as adipic acid. An example of a commercially available water-soluble epoxy resin is "Sumire's Resin (registered trademark) 650(30)" sold by Taoka Chemical Industry Co., Ltd. Polyvinyl alcohol-based resin compositions do not necessarily need to contain crosslinking agents. From the viewpoint of suppressing the degradation of polarizers, the polyvinyl alcohol-based resin composition preferably contains 8.0 parts by mass or less of aldehyde compounds per 100 parts by mass of polyvinyl alcohol-based resin, more preferably 5.0 parts by mass or less, and may not contain any aldehyde compounds at all.

[0046] A polyvinyl alcohol-based resin composition can be prepared by dissolving a polyvinyl alcohol-based resin and, if necessary, additives in a solvent. By coating one surface of a polarizer with the polyvinyl alcohol-based resin composition and drying off the solvent, a first cured layer, which is the cured layer of the polyvinyl alcohol-based resin composition, can be obtained.

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

[0048] [Phase difference layer] The phase difference layer may be one layer or two or more layers. The phase difference layer may have a base film to support the phase difference layer, an adhesive layer to bond multiple phase difference layers, etc. The phase difference layer may further include an alignment film. The phase difference layer preferably includes a quarter-wave plate layer, and may further include at least one of a half-wave plate layer or a positive C layer. When the phase difference layer includes a half-wave plate layer, the half-wave plate layer and the quarter-wave plate layer are laminated in order from the linear polarizer side. When the phase difference layer includes a positive C layer, the quarter-wave plate layer and the positive C layer may be laminated in order from the linear polarizer side, or the positive C layer and the quarter-wave plate layer may be laminated in order from the linear polarizer side. The thickness of the phase difference layer is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

[0049] The phase difference layer contains a cured polymerizable liquid crystal compound. The phase difference layer can be formed by coating a composition containing a polymerizable liquid crystal compound onto a substrate film and curing it. An alignment film may be formed between the substrate film and the coated layer. The material and thickness of the substrate film may be the same as those of the thermoplastic resin film. The phase difference layer may be incorporated into a polarizer in a form having an alignment film and a substrate film. Preferably, the surface of the phase difference layer facing the polarizer is a layer containing a cured polymerizable liquid crystal compound. The surface of the phase difference layer facing the polarizer may be the surface of the layer that exhibits the phase difference, or it may be an alignment film.

[0050] The phase difference layer may include a layer formed from a resin film, in addition to a layer containing a cured polymerizable liquid crystal compound. The resin film may be the thermoplastic resin film described above.

[0051] The liquid crystal layer exhibiting a phase difference can be formed using known liquid crystal compounds. The type of liquid crystal compound included in the composition containing the polymerizable liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof can be used. The composition containing the polymerizable liquid crystal compound may also contain polymer liquid crystal compounds. Examples of liquid crystal compounds include those described in Japanese Patent Publication No. 11-513019, Japanese Patent Publication No. 2005-289980, Japanese Patent Publication No. 2007-108732, Japanese Patent Publication No. 2010-244038, Japanese Patent Publication No. 2010-31223, Japanese Patent Publication No. 2010-270108, Japanese Patent Publication No. 2011-6360, Japanese Patent Publication No. 2011-207765, Japanese Patent Publication No. 2016-81035, International Publication No. 2017 / 043438, and Japanese Patent Publication No. 2011-207765.

[0052] A composition containing a polymerizable liquid crystal compound may also contain polymerization initiators, polymerizable monomers, surfactants, solvents, adhesion improvers, plasticizers, orientation agents, etc., in addition to the liquid crystal compound. Known methods for applying a composition containing a polymerizable liquid crystal compound include die coating. Known methods for curing a composition containing a polymerizable liquid crystal compound include irradiation with active energy rays (e.g., ultraviolet light).

[0053] A polarizer and a phase difference layer arranged such that the absorption axis of the polarizer and the slow axis of the phase difference layer are at a predetermined angle can have an anti-reflective function, i.e., function as a circular polarizer. When the phase difference layer includes a quarter-wave plate layer, the angle between the absorption axis of the polarizer and the slow axis of the quarter-wave plate layer can be 45°±10°. The phase difference layer may have positive wavelength dispersion or negative wavelength dispersion. The quarter-wave plate layer preferably has negative wavelength dispersion.

[0054] The alignment film has an alignment-regulating force that causes the polymerizable liquid crystal compounds contained in the liquid crystal layer that exhibits a phase difference and is formed on these alignment films to be liquid crystal oriented in a desired direction. Examples of alignment films include alignment polymer films formed from alignment polymers, photo-aligning polymer films formed from photo-aligning polymers, and groove alignment films having an uneven pattern or multiple grooves on the film surface. The thickness of the alignment film is usually 0.01 μm to 10 μm, and preferably 0.01 μm to 5 μm.

[0055] Oriented polymer films can be formed by applying a composition in which the oriented polymer is dissolved in a solvent to a substrate film, removing the solvent, and performing a rubbing treatment as needed. The orientation restricting force can be arbitrarily adjusted depending on the surface condition of the oriented polymer and the rubbing conditions.

[0056] A photo-oriented polymer film can be formed by applying a composition containing a polymer or monomer having photoreactive groups and a solvent to a substrate film and irradiating it with polarized light. In this case, the orientation restricting force can be arbitrarily adjusted by the polarized light irradiation conditions for the photo-oriented polymer.

[0057] Glue alignment films can be formed by methods such as: forming an uneven pattern by exposing and developing a photosensitive polyimide film surface through an exposure mask having patterned slits; forming an uncured film of an active energy ray curable resin on a plate-shaped master disc having grooves on its surface, transferring this film to a substrate film, and curing it; or forming an uncured layer of an active energy ray curable resin on a substrate film, and then forming an uneven surface on this layer by pressing a roll-shaped master disc with an uneven surface against it, and curing it.

[0058] [Second cured material layer] The second cured layer is a cured layer of a cationic polymerizable composition. The second cured layer typically has adhesion to the first cured layer and to the phase difference layer. The second cured layer 30 can bond adjacent first cured layers 20 and phase difference layers 40. The second cured layer, being a cured layer of a cationic polymerizable composition, can prevent the diffusion of unpolymerized monomers from the phase difference layer. The second cured layer, being a cured layer of a cationic polymerizable composition, protects the surface of the phase difference layer and also has excellent water resistance. When the phase difference layer is bonded to the polarizer or the first cured layer by an adhesive layer or a radical polymerizable second cured layer, it is difficult to suppress the diffusion of monomers from the phase difference layer. Since a polyvinyl alcohol-based resin, which has excellent barrier properties against dichroic dyes and unpolymerized monomers, can be protected by a hydrophobic cationic polymerizable resin, the second cured layer, which is the cured layer of the cationic polymerizable composition, can be laminated in contact with the first cured layer, which is the cured layer of the polyvinyl alcohol-based resin composition, thereby further improving the durability of the polarizer and enabling the production of a thinner polarizing plate.

[0059] The cationic polymerizable compounds contained in the cationic polymerizable composition are compounds or oligomers that undergo a cationic polymerization reaction and harden upon irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays, or upon heating. Examples include epoxy compounds, oxetane compounds, and vinyl compounds. These polymerizable compounds may be used individually or in combination of two or more. In addition to cationic polymerizable compounds, the cationic polymerizable composition may also contain radical polymerizable compounds. Radical polymerizable compounds are compounds that can initiate a polymerization reaction, for example, by radical species generated from a photoradical polymerization initiator upon irradiation with light.

[0060] The content of the cationic polymerizable compound in the cationic polymerizable composition is preferably 80 parts by mass or more and 100 parts by mass or less, more preferably 90 parts by mass or more and 99.5 parts by mass or less, and even more preferably 95 parts by mass or more and 99 parts by mass or less, based on 100 parts by mass of the total mass of the cationic polymerizable composition. When the content of the cationic polymerizable compound is within this range, a second cured layer can be obtained that has excellent water resistance and excellent diffusion prevention effect of dichroic dyes outside the polarizer.

[0061] Cationic polymerizable compositions preferably contain polymerizable compounds having a cyclic ether structure as polymerizable compounds. Examples of cyclic ether structures include oxirane rings, oxetane rings, tetrahydrofuran rings, and tetrahydropyran rings. In particular, from the viewpoint of suppressing monomer diffusion from the phase difference layer and water resistance, it is preferable to include polymerizable compounds having a cyclic ether structure with 2 to 4 carbon atoms, and more preferably to include oxetane compounds.

[0062] Oxetane compounds are compounds having one or more oxetanyl groups (oxetane rings) in their molecule, and may be aliphatic, alicyclic, or aromatic compounds. Examples of oxetane compounds having one oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, 3-ethyl-3-(phenoxymethyl)oxetane, and 3-(cyclohexyloxy)methyl-3-ethyloxetane. Examples of oxetane compounds having two or more oxetanyl groups include 1,4-bis[{(3-ethyloxetane-3-yl)methoxy}methyl]benzene (also called "xylylenebisoxetane") and bis(3-ethyl-3-oxetanylmethyl) ether. These oxetane compounds may be used individually or in combination of two or more. Oxetane compounds may be used as the main component of cationic polymerizable compounds, or they may be used in combination with epoxy compounds.

[0063] The oxetane compound preferably contains an oxetane compound having two or more oxetanyl groups in its molecule. By including such an oxetane compound, a dense cured product with high crosslinking density can be obtained, and in combination with the first cured product layer, the diffusion of dichroic dye from the polarizer can be effectively suppressed, resulting in a polarizer that is less prone to changes in optical performance over time.

[0064] The oxetane compound content may be, 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, based on 100 parts by mass of the total amount of polymerizable compounds contained in the cationic polymerizable composition. When the oxetane compound content is above the above lower limit, a second cured layer with superior heat resistance and moisture-heat resistance is formed, and in combination with the first cured layer, the water resistance, heat resistance and moisture-heat resistance of the polarizing plate can be effectively improved. As a result, a polarizing plate that is less prone to changes in optical performance over time can be obtained. The oxetane compound content 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, based on 100 parts by mass of the total amount of polymerizable compounds contained in the cationic polymerizable composition. Furthermore, the content of the oxetane compound may be a combination of the lower and upper limits mentioned above, preferably 30 to 90 parts by mass, more preferably 40 to 85 parts by mass, per 100 parts by mass of the total amount of polymerizable compounds contained in the cationic polymerizable composition. The content of the oxetane compound may be, for example, 25 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, per 100 parts by mass of the total amount of the cationic polymerizable composition, preferably 90 parts by mass or less, more preferably 85 parts by mass or less.

[0065] The cationic polymerizable composition preferably contains an epoxy compound in addition to the oxetane compound as a polymerizable compound. An epoxy compound is a compound having one or more, preferably two or more, epoxy groups in its molecule. The cationic polymerizable composition preferably contains 10 to 2000 parts by mass, more preferably 30 to 1000 parts by mass, and even more preferably 30 to 500 parts by mass, of the oxetane compound per 100 parts by mass of the epoxy compound.

[0066] Epoxy compounds may be used individually or in combination of two or more. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. In particular, from the viewpoint of weather resistance, curing speed, and adhesion, it is preferable that the epoxy compound contains an alicyclic epoxy compound or an aliphatic epoxy compound, and more preferably an alicyclic epoxy compound.

[0067] Alicyclic epoxy compounds are compounds having one or more epoxy groups bonded to an alicyclic ring within the molecule, preferably two or more epoxy groups bonded to an alicyclic ring within the molecule. "Epoxy group bonded to an alicyclic ring" refers to the cross-linking oxygen atom -O- in the structure shown in formula (II) below. In formula (I) below, m is an integer between 2 and 5. [ka]

[0068] (CH2) in the above equation (II) m Compounds in which a group with one or more hydrogen atoms removed is bonded to another chemical structure can be alicyclic epoxy compounds. (CH2) m One or more hydrogen atoms in the molecule may be appropriately substituted with linear alkyl groups such as methyl or ethyl groups.

[0069] From the viewpoint of increasing the glass transition temperature of the cured product, alicyclic epoxy compounds having an epoxycyclopentane structure (m=3 in formula (II) above) or an epoxycyclohexane structure (m=4 in formula (II) above) are preferred, and alicyclic diepoxy compounds represented by the following formula (IIA) are more preferred. The second cured layer, which is the cured product layer of a cationic polymerizable composition containing the alicyclic diepoxy compound represented by the following formula (IIA), has a high glass transition temperature and can suppress the diffusion of the dye at high temperatures.

[0070] [ka] In formula (IIA), R 1 and R 2 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and if 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 linear or branched alkyl group, and examples of alkyl groups having an alicyclic structure include cyclopropyl group, cyclobutyl group, and cyclopentyl group.

[0071] In formula (IIA), X represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a group represented by any of the following formulas (IIa) to (IId). Examples of alkanediyl groups having 1 to 6 carbon atoms include the methylene group, ethylene group, and propane-1,2-diyl group. [ka]

[0072] If X in equation (IIA) is a base represented by any of equations (IIa) to (IId), then Y in each equation 1 ~Y 4 Each of these is an alkanediyl group having 1 to 20 carbon atoms, and if the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure. a and b each represent an integer from 0 to 20 independently.

[0073] Examples of alicyclic epoxy compounds include the following compounds A to M. The chemical formulas A to M shown in the following paragraphs correspond to compounds A to M, respectively. A: 3,4-Epoxycyclohexylmethyl 3,4-Epoxycyclohexanecarboxylate, B: 3,4-Epoxy-6-methylcyclohexylmethyl 3,4-Epoxy-6-methylcyclohexanecarboxylate, C: Ethylene bis(3,4-epoxycyclohexanecarboxylate), D: Bis(3,4-epoxycyclohexylmethyl) adipate, E: Bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: Diethylene glycol bis(3,4-epoxycyclohexylmethyl ether), G: Ethylene glycol bis(3,4-epoxycyclohexylmethyl ether), H:2,3,14,15-Diepoxy-7,11,18,21-Tetraoxatrispiro[5.2.2.5.2.2]Henicosane, I:3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane, J:4-Vinylcyclohexene dioxide, K: Limonene dioxide, L: Bis(2,3-epoxycyclopentyl) ether, M: Dicyclopentadiene dioxide.

[0074] [ka]

[0075] [ka]

[0076] Due to its easy availability, 3,4-epoxycyclohexylmethyl3,4-epoxycyclohexanecarboxylate is preferred as the alicyclic epoxy compound. Furthermore, from the viewpoint of effectively suppressing the diffusion of the dye, the 1,2-epoxy-4-(2-oxyranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol is preferred. The alicyclic epoxy compound may be used alone or in combination of several different types.

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

[0078] Aliphatic epoxy compounds are compounds that have at least one epoxy ring bonded to an aliphatic carbon atom within their molecule, preferably two or more epoxy rings within their molecule. For example, an aliphatic epoxy compound has at least one oxirane ring (a three-membered cyclic ether) bonded to an aliphatic carbon atom within its molecule, preferably two or more. Examples of aliphatic epoxy compounds include monofunctional epoxy compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; bifunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trifunctional or more epoxy compounds such as trimethylolpropane triglycidyl ether and pentaerythritol 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 oxirane ring bonded to an aliphatic carbon atom.

[0079] From the viewpoint of obtaining a cationic polymerizable composition with low viscosity and easy application, a bifunctional epoxy compound (also called an "aliphatic diepoxy compound") having two oxirane rings bonded to aliphatic carbon atoms in its molecule, represented by the following formula (III), is preferred. [ka] [In formula (III), Z is an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or formula -C m H 2m -Z 1 -C n H 2n - represents a divalent group. -Z 1 The dash (-) represents -O-, -CO-O-, -O-CO-, -SO2-, -SO-, or CO-, and m and n each independently represent an integer greater than or equal to 1. However, the sum of m and n is 9 or less.

[0080] The divalent alicyclic hydrocarbon group may be, for example, a divalent alicyclic hydrocarbon group having 4 to 8 carbon atoms, such as the divalent residue shown in the following formula (IIIA). [ka]

[0081] Specific examples of compounds represented by formula (III) include diglycidyl ethers of alkanediols; diglycidyl ethers of oligoalkylene glycols with up to 4 repeating units; and diglycidyl ethers of alicyclic diols.

[0082] Diols (glycols) that can form the aliphatic diepoxy compound 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-1,5-pentanediol, and 2-methyl-2,4-pentanediol. Examples include diols, alkanediols such as 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; oligoalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol; and alicyclic diols such as cyclohexanediol and cyclohexanedimethanol.

[0083] From the viewpoint of obtaining a cationic polymerizable composition with low viscosity and easy application, it is preferable that the aliphatic epoxy compound includes 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether. In terms of maintaining optical performance, 1,6-hexanediol diglycidyl ether and pentaerythritol polyglycidyl ether are preferred. As the aliphatic epoxy compound, one type of aliphatic epoxy compound may be used alone, or a combination of several different types may be used.

[0084] When a cationic polymerizable composition contains an aliphatic epoxy compound, the content of the aliphatic epoxy compound may be, for example, 1 to 90 parts by mass, preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, even more preferably 5 to 20 parts by mass, and particularly preferably 7 to 15 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in the cationic polymerizable composition. When the content of the aliphatic epoxy compound is within this range, a cationic polymerizable composition with low viscosity and easy application can be obtained.

[0085] Aromatic epoxy compounds are compounds that have an aromatic ring and an epoxy group in their molecule. Specific examples include bisphenol-type epoxy compounds or their oligomers, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; novolac-type epoxy resins, such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy compounds, such as glycidyl ether of 2,2',4,4'-tetrahydroxydiphenylmethane and glycidyl ether of 2,2',4,4'-tetrahydroxybenzophenone; and polyfunctional epoxy resins, such as epoxidized polyvinylphenol.

[0086] From the viewpoint of reducing the viscosity of the cationic polymerizable composition, it is preferable that the aromatic epoxy compound contains at least one 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 polyhydric phenols, glycidyl esters of benzoic acids, glycidyl esters of polybasic acids, styrene oxide, or epoxidized divinylbenzene. To improve the curability of the cationic polymerizable composition, it is preferable that the aromatic epoxy compound has an epoxy equivalent of 80 to 500. As the aromatic epoxy compound, one aromatic epoxy compound may be used alone, or a combination of several different types may be used.

[0087] As aromatic epoxy compounds, commercially available products can be used, 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); Ogusol PG-100, Ogusol EG-200, Ogusol EG-210, Ogusol EG-250 (all manufactured by Osaka Gas Chemical Co., Ltd.); HP4032, HP4032D, HP4700 (all manufactured by DIC Corporation); E SN-475V (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.); Epicote YX8800, jER828EL (manufactured by Mitsubishi Chemical Corporation); Marproof G-0105SA, Marproof G-0130SP (manufactured by NOF Corporation); Epiclon N-665, Epiclon HP-7200 (both manufactured by DIC Corporation); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501 Examples include H, EPPN-501HY, EPPN-502H, NC-7000L (all manufactured by Nippon Kayaku Co., Ltd.); Adekaglycirol ED-501, Adekaglycirol ED-502, Adekaglycirol ED-509, Adekaglycirol ED-529, Adekaresin EP-4000, Adekaresin EP-4005, Adekaresin EP-4100, Adekaresin EP-4901 (all manufactured by ADEKA Corporation); TECHMORE VG-3101L, EPOX-MKR710, EPOX-MKR151 (all manufactured by Printec Co., Ltd.).

[0088] When a cationic polymerizable composition contains an aromatic epoxy compound, the cationic polymerizable composition becomes a hydrophobic resin, and the resulting cured layer (second cured layer) is also hydrophobic. Therefore, it is possible to prevent the intrusion of moisture from the outside under high temperature and high humidity conditions and effectively suppress the movement of dichroic pigments contained in polarizers.

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

[0090] Hydrogenated epoxy compounds are glycidyl ethers of polyols having an alicyclic ring, and can be obtained by selectively hydrogenating the aromatic ring of an aromatic polyol under pressure and in the presence of a catalyst to obtain a nuclear hydrogenated polyhydroxy compound, which is then glycidyl etherified. Specific examples of aromatic polyols include bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac-type resins such as phenol novolac resins, cresol novolac resins, and hydroxybenzaldehyde phenol novolac resins; and polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. Glycidyl ethers can be obtained by reacting an alicyclic polyol, obtained by hydrogenating the aromatic ring of an aromatic polyol, with epichlorohydrin. Among hydrogenated epoxy compounds, diglycidyl ether of hydrogenated bisphenol A is a preferred example.

[0091] The cationic polymerizable composition may further contain other curable compounds other than those mentioned above. Specific examples of these other curable compounds include other cationic polymerizable compounds other than those mentioned above, such as lactone compounds, cyclic acetal compounds, cyclic thioether compounds, and spiro-othoester compounds.

[0092] Cationic polymerizable compositions preferably contain a polymerization initiator to initiate polymerization. The polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator. For example, when a cationic polymerizable composition contains an oxetane compound, an epoxy compound, or the like as a polymerizable compound, it is preferable to use a photocationic polymerization initiator.

[0093] Photocationic polymerization initiators generate cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of cationic polymerizable compounds. Because photocationic polymerization initiators act catalytically with light, they exhibit excellent storage stability and workability even when mixed with polymerizable compounds. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

[0094] Aromatic iodonium salts are compounds having diaryliodonium cations, typically including diphenyliodonium cations. Aromatic sulfonium salts are compounds having triarylsulfonium cations, typically including triphenylsulfonium cations, 4,4'-bis(diphenylsulfonio)diphenylsulfide cations, and the like. Aromatic diazonium salts are compounds having diazonium cations, typically including benzenediazonium cations. Iron-arene complexes are typically cyclopentadienyl iron(II)arene cation complex salts.

[0095] The above cations, paired with anions, constitute a photocationic polymerization initiator. Examples of anions that constitute the photocationic polymerization initiator include special phosphorus anions [(Rf)nPF6-n]-, hexafluorophosphate anions PF6-, hexafluoroantimonate anions SbF6-, pentafluorohydroxyantimonate anions SbF5(OH)-, hexafluoroarsenate anions AsF6-, tetrafluoroborate anions BF4-, and tetrakis(pentafluorophenyl)borate anions B(C6F5)4-. Among these, from the viewpoint of curability of the polymerizable compound and safety of the resulting second cured layer, it is preferable that the photocationic polymerization initiator is a special phosphorus anion [(Rf)nPF6-n]- or a hexafluorophosphate anion PF6-.

[0096] The photocationic polymerization initiator may be used alone or in combination of several different types. Among these, aromatic sulfonium salts are preferred because they have excellent curing properties due to their ultraviolet absorption characteristics even in the wavelength region around 300 nm, and can produce cured products with good mechanical strength and adhesive strength.

[0097] The content of the polymerization initiator in the cationic polymerizable composition is usually 0.5 parts by mass to 10 parts by mass, preferably 6 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of the polymerizable compound. When the content of the polymerization initiator is within this range, the polymerizable compound can be sufficiently cured, and the cured layer composed of the resulting cured product can be given high mechanical strength and adhesive strength.

[0098] Cationic polymerizable compositions may optionally contain additives commonly used in curable compositions. Examples of such additives include ion trapping agents, antioxidants, chain transfer agents, polymerization accelerators (such as polyols), sensitizers, sensitizing aids, light stabilizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, leveling agents, silane coupling agents, dyes, antistatic agents, and UV absorbers.

[0099] Examples of sensitizers include photosensitizers. Photosensitizers are compounds that exhibit maximum absorption at wavelengths longer than the maximum absorption wavelength shown by photocationic polymerization initiators, thereby promoting the polymerization initiation reaction by photocationic polymerization initiators. Photosensitizing aids are compounds that further enhance the action of photosensitizers. By incorporating photosensitizers and photosensitizing aids, a cured layer with desired performance 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 at wavelengths longer than 380 nm. Examples of such photosensitizers include the anthracene compounds described below. 9,10-Dimethoxyanthracene, 9,10-Diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-Diisopropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-Dipentyloxyanthracene, 9,10-Dihexyloxyanthracene, 9,10-Bis(2-methoxyethoxy)anthracene, 9,10-Bis(2-ethoxyethoxy)anthracene, 9,10-Bis(2-butoxyethoxy)anthracene, 9,10-Bis(3-butoxypropoxy)anthracene, 2-methyl-or 2-ethyl-9,10-dimethoxyanthracene, 2-methyl-or 2-ethyl-9,10-diethoxyanthracene, 2-methyl-or 2-ethyl-9,10-dipropoxyanthracene, 2-methyl- or 2-ethyl-9,10-diisopropoxyanthracene 2-methyl-or 2-ethyl-9,10-dibutoxyanthracene, 2-methyl-or 2-ethyl-9,10-dipentyloxyanthracene, 2-methyl-or 2-ethyl-9,10-dihexyloxyanthracene.

[0101] Leveling agents are additives that adjust the fluidity of a curable composition and make the resulting coating flatter. Examples include silicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents such as silane coupling agents. Commercially available leveling agents may also be used.

[0102] The leveling agent content 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, per 100 parts by mass of polymerizable compound. When the leveling agent content is within this range, the second cured layer tends to be smoother.

[0103] The thickness of the second cured layer is preferably 0.1 μm to 10 μm, more preferably 0.2 μm to 2 μm. When the thickness of the second cured layer is within this range, the protective function against the phase difference layer and the function of preventing the diffusion of dichroic dye from the polarizer can be further exhibited, and the polarizer can be made thinner.

[0104] The second cured layer can be formed by coating the surface of the first cured layer 20 or the phase difference layer 40, which is provided in contact with the polarizer 10, with an uncured second cured layer forming composition, or by dropping the uncured second cured layer forming composition between the first cured layer 20 and the phase difference layer 40, overlapping the polarizer 10 on which the first cured layer 20 is provided with the phase difference layer 40 via the uncured second cured layer forming composition, bonding them by pressing from above and below using, for example, a bonding roll, and then curing the second cured layer forming composition. Curing can be performed by irradiating with active energy rays (in the case of an active energy ray curable composition) or by heating (in the case of a thermosetting composition). The active energy rays may be irradiated from the polarizer 10 side or from the phase difference layer 40 side.

[0105] Various coating methods can be used to coat the uncured second-cured layer-forming composition, such as doctor blades, wire bars, die coaters, comma coaters, and gravure coaters. Alternatively, a method involving casting an adhesive between the layers to be bonded can also be employed.

[0106] The irradiation conditions for the active energy rays can be any suitable conditions as long as they are capable of curing the active energy ray-curable composition. For example, for electron beam irradiation, the acceleration voltage is preferably 5kV to 300kV, and more preferably 10kV to 250kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the active energy ray-curable composition, resulting in insufficient curing. If the acceleration voltage exceeds 300kV, the penetrating force through the sample may be too strong, causing the electron beam to bounce back and potentially damaging the film or polarizer. The irradiation dose is 5 to 100kGy, more preferably 10 to 75kGy. If the irradiation dose is less than 5kGy, the active energy ray-curable composition will be insufficiently cured. If it exceeds 100kGy, the phase difference layer will be damaged, resulting in a decrease in mechanical strength and yellowing, making it impossible to obtain the desired optical properties.

[0107] Electron beam irradiation is usually performed in an inert gas environment, but if necessary, it may also be performed in air or under conditions with a small amount of oxygen introduced.

[0108] In UV-curable types, the light irradiation intensity to the active energy ray-curable composition is determined for each composition and is not particularly limited, but is generally between 10 and 1000 mJ / cm². 2 Preferably, the light irradiation intensity is 10 mJ / cm². 2 If it is less than 1000 mJ / cm², the reaction time will be too long. 2 If the irradiation intensity exceeds this, the heat radiated from the light source and the heat generated during polymerization of the adhesive may cause yellowing of the constituent materials of the composition. The irradiation intensity is preferably in the wavelength range of 400 nm or less, and more preferably in the wavelength range of 280 to 320 nm. The light is irradiated once or multiple times at such an irradiation intensity, and the accumulated light amount is preferably 10 mJ / cm². 2More preferably, 100 to 1000 mJ / cm² 2 Set it so that the integrated light amount on the above composition is 10 mJ / cm². 2 If the value is less than 1000 mJ / cm², the generation of active species derived from the polymerization initiator will be insufficient, resulting in inadequate curing of the composition. On the other hand, if the integrated light intensity is 1000 mJ / cm² 2 Beyond this point, the irradiation time becomes extremely long, which is detrimental to productivity. In this case, the required integrated light dose in which wavelength range (such as UVA (320-390nm) or UVB (280-320nm)) is needed will differ depending on the type of film used and the combination of compositions.

[0109] The light source used for polymerization curing of the composition by irradiation with active energy rays in the present invention is not particularly limited, but 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 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 and simplicity of the apparatus, an ultraviolet light source having an emission distribution with a wavelength of 400 nm or less is preferred.

[0110] Even when using an active energy ray curable composition, heat treatment may be performed simultaneously with or after irradiation with active energy rays. Before forming the coating layer of the composition, one or both bonding surfaces may be subjected to an easy-adhesion treatment such as saponification, corona discharge, plasma treatment, flame treatment, primer treatment, or anchor 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 using the following procedure. A second cured layer is formed between two stretched films of cyclic polyolefin resin with a thickness of 25 μm. The container containing the sample for measurement is set in a differential scanning calorimeter (DS, TA Instruments), and the temperature is lowered from 20°C to -60°C while purging with nitrogen gas. After reaching -60°C, the temperature 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. The midpoint glass transition temperature specified in JIS K 7121-1987 "Method for Measuring Transition Temperatures of Plastics" is determined from the DSC curve obtained when the temperature is increased from -60°C to 150°C, and this is taken as the glass transition temperature of the second cured layer.

[0113] The storage modulus of the second cured layer at a temperature of 30°C is preferably 100 MPa or higher, more preferably 1000 MPa or higher, more preferably 1500 MPa or higher, and particularly preferably 2000 MPa or higher, from the viewpoint of improving the durability of the polarizing plate. On the other hand, if the storage modulus of the second cured layer is too high, the adhesive cured layer may become too hard, which may reduce the processability of the polarizing plate. For this reason, the storage modulus of the adhesive cured layer at a temperature of 30°C is preferably 10000 MPa or lower, more preferably 8000 MPa or lower, and even more preferably 5000 MPa or lower.

[0114] The storage modulus of the second cured layer at a temperature of 80°C is preferably, for example, 10 MPa or more or 20 MPa or more, and preferably 100 MPa or more or 1000 MPa or more. The storage modulus of the second cured 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 cured layer can be calculated using the following procedure. A second cured layer is formed between two 50 μm thick cyclic polyolefin resin films. This is cut to a size of 5 mm × 30 mm, and one of the cyclic polyolefin resin films is peeled off to obtain a second cured layer with the resin film attached. This second cured layer with the resin film attached is gripped with a gripping distance of 2 cm using the "DVA-220" dynamic viscoelasticity measuring device manufactured by IT Measurement Control Co., Ltd., with its long side facing the tensile direction. The tensile and contraction frequencies are set to 10 Hz and the heating rate to 10 °C / min, and the temperature is increased to determine the storage modulus at each temperature.

[0116] <Method for manufacturing optical laminates> The method for manufacturing the optical laminate is not particularly limited. One embodiment includes the steps of: applying a polyvinyl alcohol-based resin composition to the surface of a polarizer and curing it to form a first cured layer; and laminating the first cured layer formed on the surface of the polarizer with a phase difference layer interposed by a cationic polymerizable composition, and curing the cationic polymerizable composition to form a second cured layer.

[0117] <Image display device> The image display device includes an image display panel and the polarizing plate described above. In the image display device, the polarizing plate can be configured, for example, by being placed on the front (viewing side) of the image display panel. The image display panel is not particularly limited and includes, for example, a liquid crystal display panel, an organic electroluminescent (organic EL) display panel, an inorganic electroluminescent (inorganic EL) display panel, a plasma display panel, a field emission type display panel, and the like. The circular polarizing plate may also be placed on the viewing side of the organic EL display device to configure the image display device.

[0118] The image display device according to the present invention can be used in mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic signboards, measuring instruments and gauges, office equipment, medical equipment, computer equipment, etc. The image display device according to the present invention is highly durable even when used in harsh environments. [Examples]

[0119] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In this example, a polarizing plate was made using the polarizer, first cured layer, second cured layer and phase difference layer shown below.

[0120] <Fabrication of the laminate in Example 1> [Fabrication of polarizers with base film] A 38 μm polyethylene terephthalate (PET) film with a hard coat layer on one side was used as the base film. After corona treatment of the hard coat layer side surface of the base film, a photo-alignment film was formed. 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 was applied to the photo-alignment film, dried, and irradiated with UV light to form a polarizer. Furthermore, a protective film was laminated to the base film side.

[0121] [Formation of the first hardened layer] Corona treatment was performed on the polarizer side surface of the fabricated polarizer with a substrate film, and a polyvinyl alcohol-based resin composition was applied by bar coating (speed 30 mm / sec) to a cured film thickness of 1.0 μm. The corona treatment conditions were 800 W output, 10 m / min processing speed, and one pass. As the polyvinyl alcohol-based resin composition, a composition prepared with acetoacetyl-modified polyvinyl alcohol (trade name "Z-220", Mitsubishi Chemical Corporation) was used. Details of Z-220 are shown in Table 1. The coated 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] [Preparing the phase difference layer] As a phase difference layer, an integrated product was prepared consisting of a first protective film, an alignment film, a quarter-wave plate layer, an adhesive layer, a positive C layer, an alignment film, and a second protective film. The quarter-wave plate layer and the positive C layer are layers formed by coating a composition containing a polymerizable liquid crystal compound onto the alignment film, drying, and curing with UV irradiation. The first protective film was a PET film with a thickness of 100 μm, and the second protective film was a PET film with a thickness of 38 μm.

[0123] [Bonding of polarizer with first cured layer and phase difference layer] Corona treatment was performed on the surface of the first cured layer and the surface of the phase difference layer after the first protective film was removed from the polarizer with the first cured layer. The corona treatment conditions were an output of 800W, a processing speed of 10m / min, and one pass. The two laminates were bonded together using a laminator while applying an ultraviolet-curable cationic polymerizable composition between the corona-treated first cured layer surface and the phase difference layer surface. The thickness of the second cured layer was 1.5μm. The lamination conditions were a speed of 2.5m / min. Ultraviolet light was supplied using an ultraviolet irradiation device at UVB 400mj / cm². 2 The lamp was irradiated once. The lamp used was an "H bulb" manufactured by Fusion UV Systems. The environment during UV irradiation was a temperature of 23°C and a relative humidity of 55% RH. As a result, a polarizing plate of Example 1 was obtained, in which a polarizer containing a dichroic azo dye, a first cured product layer, a second cured product layer, and a phase difference layer containing a cured polymerizable liquid crystal compound were laminated in this order.

[0124] (Preparation of cationic polymerizable compositions) The cationic polymerizable composition was prepared by mixing the components shown in Table 2 in the proportions (in parts by mass) shown in Table 2, and then degassing the mixture. The cationic polymerization initiator (B-1) was included as a 50% propylene carbonate solution, and its solid content is shown in Table 2. The glass transition temperature and storage modulus were measured according to the description in the [Second Cured Layer] section above.

[0125] <Fabrication of laminates in Examples 2-7> The polarizing plate of Example 2 was prepared in the same manner as in Example 1, except that the polyvinyl alcohol-based resin composition used for the first cured layer was the product name "Z-200" shown in Table 1. The polarizing plates of Examples 3 to 6 were prepared in the same manner as in Example 2, except that glyoxal was further added to the polyvinyl alcohol-based resin composition in the amounts shown in Table 3. The polarizing plate of Example 7 was prepared in the same manner as in Example 1, except that the polyvinyl alcohol-based resin composition used for the first cured layer was the product name "PVA117" shown in Table 1.

[0126] [Table 1]

[0127] [Table 2]

[0128] The compounds in Table 2 are as follows: (Cationically polymerizable compound (A)) A-1: 3',4'-Epoxycyclohexylmethyl 3,4-Epoxycyclohexanecarboxylate (Trade name: CEL2021P, manufactured by Daicel Corporation) A-2: 1,2-epoxy-4-(2-oxyranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (Trade name: EHPE3150, manufactured by Daicel Corporation) A-3: 3-Ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (Trade name: OXT-221, manufactured by Toagosei Co., Ltd.) (Cationic polymerization initiator (B)) B-1: "CPI-100P", manufactured by Sunapro Co., Ltd., 50% by mass solution (Photosensitizer (C)) C-1: 1,4-diethoxynaphthalene

[0129] <Preparation of the laminated material of Comparative Example 1> As Comparative Example 1, a laminate was prepared in which a polarizer and a phase difference layer were bonded via an adhesive layer, without having a first cured layer and a second cured layer. First, an adhesive sheet was prepared in which a 5 μm thick acrylic adhesive layer was provided between a lightly release film and a heavily release film. The polarizer side of the polarizer with the base film described in Example 1 was bonded to the side of the adhesive sheet from which the lightly release film had been peeled off. Before bonding, the polarizer surface was subjected to corona treatment once at an output of 800 W and a processing speed of 10 m / min, and the adhesive layer surface was subjected to corona treatment three times at an output of 280 W and a processing speed of 10 m / min. The side of the phase difference layer from which the first protective film described in Example 1 had been peeled off was bonded to the side of the adhesive sheet from which the heavily release sheet had been peeled off. Before bonding, the phase difference layer surface was subjected to corona treatment once at an output of 800 W and a processing speed of 10 m / min, and the adhesive layer surface was subjected to corona treatment three times at an output of 280 W and a processing speed of 10 m / min. This yielded the laminate of Comparative Example 1. The method is the same as in Example 1, except as specifically described.

[0130] <Preparation of the laminated material for Comparative Example 2> As Comparative Example 2, a laminate was prepared in which a polarizer with a first cured layer and a phase difference layer were bonded together via an adhesive layer, without having a second cured layer. The laminate of Comparative Example 2 was obtained by the same method as the manufacturing method of the laminate of Comparative Example 1, except that the polarizer with a first cured layer of Example 2 was used as the polarizer. Briefly, an adhesive layer was laminated on the first cured layer side of the polarizer with a first cured layer described in Example 1, and then the quarter-wave plate layer side of the phase difference layer described in Example 1 was laminated on the side of the adhesive layer opposite to the first cured layer.

[0131] <Fabrication of the laminated material of Comparative Example 3> As Comparative Example 3, a laminate was obtained in which a polarizer with a first cured layer and a phase difference layer were bonded together via a second cured layer and an adhesive layer. First, the polarizer with a first cured layer of Example 2 was prepared. The first cured layer side of the polarizer with the first cured layer was subjected to corona treatment, and the two laminates were bonded together using a laminator while applying a cationic polymerizable composition between the corona-treated surface and a cycloolefin film that had not been corona-treated. After curing the composition by ultraviolet irradiation to form a second cured layer, the cycloolefin film was peeled off. Next, the second cured layer side of the polarizer was bonded to the side of the adhesive sheet of Comparative Example 1 from which the light-release film had been peeled off. Furthermore, the side of the phase difference layer described in Example 1 from which the first protective film had been peeled off was bonded to the side of the adhesive sheet from which the heavy-release sheet had been peeled off. As a result, the laminate of Comparative Example 3 was obtained. Unless otherwise specifically described, the methods are the same as in Example 1 or Comparative Example 1.

[0132] <Durability evaluation of polarizers and phase difference layers> The second protective film was peeled off from the laminates of the examples and comparative examples, and bonded to an acrylic adhesive sheet (with separator film) with a thickness of 15 μm. This laminate was cut to a size of 30 mm x 30 mm, the separator film was peeled off, and it was bonded to Corning's alkali-free glass (product name: Eagle XG, 40 mm x 40 mm x 0.7 mm thick). Samples were prepared by autoclaving at a temperature of 50°C.

[0133] [Measurement of polarization] Each sample was placed in an oven set to high temperature (85°C dry) conditions for 168 hours. The luminous efficiency-corrected polarization degree (Py1) (%) before being placed in the oven and the luminous efficiency-corrected polarization degree (Py2) (%) after being placed in the oven for 168 hours were measured using a spectrophotometer (V-7100 manufactured by JASCO), and the change in ΔPy was calculated based on the following formula. ΔPy=|Py2-Py1| ΔPy was evaluated based on the following criteria. A: Change in polarization degree ΔPy is less than 0.5 B: Change in polarization degree ΔPy is 0.5 or greater and less than 1.0 C: Change in polarization degree ΔPy is 1.0 or greater.

[0134] [Measuring Phase Difference Values] Test samples were prepared using the same method as described above. Each sample was left in an oven set to 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 550 nm before being placed in the oven and the in-plane phase difference value (Re2) (nm) at a wavelength of 550 nm after being left in the oven for 168 hours were measured using a phase difference measuring device KOBRA-WPR (manufactured by Oji Instruments Co., Ltd.), and the change in value, ΔRe, was calculated based on the following formula. ΔRe=|Re2-Re1| ΔRe was evaluated based on the following criteria. A: The change in phase difference value ΔRe is less than 0.5 B: The change in phase difference value ΔRe is between 0.5 and less than 2.5. C: The change in phase difference value ΔRe is 2.5 or greater.

[0135] [Hot water immersion test] Samples were prepared using the same method as described above, with polarizers laminated onto alkali-free glass. The samples were cut into strips measuring 50 mm x 20 mm, with the absorption axis of the polarizer as the longer side, and the dimensions in the longer side were accurately measured. One short side of the sample was grasped with a gripping tool, and approximately 80% of the sample in the longer side was immersed in a 60°C water bath for 3 minutes. After that, the sample was removed from the water bath and the moisture was wiped off. The polarizer of the polarizer shrinks when immersed in hot water. The degree of this shrinkage of the polarizer was measured by measuring the distance from the edge of the sample (edge ​​of the glass) to the edge of the shrunk polarizer at the center of the short side of the sample. The obtained measurements were evaluated according to the following criteria. A: The distance from the edge of the sample to the edge of the polarizer is 3 mm or less. B: The distance from the edge of the sample to the edge of the polarizer is greater than 3 mm.

[0136] [Table 3]

[0137] A polarizing plate in which a polarizer, a first cured layer, a second cured layer, and a phase difference layer are laminated in this order, with the first cured layer being a cured layer of a polyvinyl alcohol-based resin composition and the second cured layer being a cured layer of a cationic polymerizable composition, exhibits a small ΔPy at 85°C, suggesting that the diffusion of the polarizer's dye at high temperatures is suppressed. Furthermore, such a polarizing plate exhibits a small ΔRe at 65°C and 90% RH relative humidity, suggesting that monomer diffusion in the phase difference layer at high temperature and high humidity is suppressed. In addition, it was found that water resistance is improved when the polyvinyl alcohol-based resin composition includes acetoacetyl-modified polyvinyl alcohol. [Explanation of symbols]

[0138] 100 polarizing plate, 10 polarizer, 20 first cured material layer, 30 second cured material layer, 40 retardation layer.

Claims

1. A polarizer containing a dichroic azo dye, a first cured layer, a second cured layer, and a phase difference layer comprising a layer containing a cured polymerizable liquid crystal compound are stacked in this order in contact with each other. The first cured layer is a cured layer of a polyvinyl alcohol-based resin composition. The aforementioned second cured layer is a cured layer of a cationic polymerizable composition, (1) or (2) below: (1) The second cured layer and the layer containing the cured polymerizable liquid crystal compound are in contact. (2) The phase difference layer further comprises an alignment film disposed adjacent to the layer containing the cured polymerizable liquid crystal compound, wherein the second cured product layer and the alignment film are in contact. Satisfying the conditions, A polarizing plate wherein the storage modulus of the second cured layer at a temperature of 30°C is 2000 MPa or more.

2. The polarizing plate according to claim 1, wherein the polyvinyl alcohol-based resin composition comprises acetoacetyl-modified polyvinyl alcohol.

3. The polarizing plate according to claim 1 or 2, wherein the degree of saponification of the polyvinyl alcohol-based resin contained in the polyvinyl alcohol-based resin composition is 85 mol% or more and 100 mol% or less.

4. The polarizing plate according to any one of claims 1 to 3, wherein the degree of polymerization of the polyvinyl alcohol resin contained in the polyvinyl alcohol resin composition is 1000 or more and 5000 or less.

5. The polarizing plate according to any one of claims 1 to 4, wherein the polyvinyl alcohol-based resin composition does not contain an aldehyde compound, or contains 8.0 parts by mass or less of an aldehyde compound per 100 parts by mass of the polyvinyl alcohol-based resin.

6. The polarizing plate according to any one of claims 1 to 5, wherein the cationic polymerizable composition comprises an oxetane compound.

7. The polarizing plate according to claim 6, wherein the cationic polymerizable composition further comprises an epoxy compound.

8. The polarizing plate according to claim 7, wherein the cationic polymerizable composition contains 10 to 2000 parts by mass of the oxetane compound per 100 parts by mass of the epoxy compound.

9. The polarizing plate according to any one of claims 1 to 8, further comprising a photosensitizer in the cationic polymerizable composition.

10. The polarizing plate according to any one of claims 1 to 9, wherein the layer containing the cured polymerizable liquid crystal compound is a quarter-wave plate layer.

11. An image display device including a polarizing plate according to any one of claims 1 to 10.

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