Composition for forming a hard coat layer, hard coat layer, polarizing plate, and image display device.

Abstract

To provide a hard coat layer forming composition that can suppress the occurrence of reddening in polarizing plates. [Solution] A hard coat layer forming composition comprising a monomer component and a radical polymerization initiator, wherein the monomer component contains an acrylic monomer (a) having a (meth)acryloyl group, at least a portion of the acrylic monomer (a) is a monomer (a1) having an epoxy group, and at least a portion of the acrylic monomer (a) is a monomer (a2) having two or more (meth)acryloyl groups.

Description

[Technical Field]

[0001] This disclosure relates to a composition for forming a hard coat layer, a hard coat layer, a polarizing plate, and an image display device. [Background technology]

[0002] As described in Patent Document 1, it is known that a phenomenon called reddening occurs when a polarizing plate is exposed to a high-temperature environment. Reddening is a phenomenon in which the transmittance on the long wavelength side of approximately 700 nm increases, causing the polarizing plate to appear red when arranged in a crossed nicol configuration. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-152862 [Patent Document 2] Japanese Patent Publication No. 2014-170130 [Patent Document 3] Japanese Patent Publication No. 2009-098658 [Patent Document 4] International Publication No. 2022 / 158482 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] One of the objectives of this disclosure is to provide a hard coat layer forming composition for forming a hard coat layer capable of suppressing the occurrence of reddening in a polarizing plate. Another objective of this disclosure is to provide a hard coat layer capable of suppressing the occurrence of reddening in a polarizing plate, as well as a polarizing plate and an image display device equipped with the hard coat layer. [Means for solving the problem]

[0005] This disclosure relates, for example, to the following [1] to

[17] . [1] It contains a monomer component and a radical polymerization initiator. The monomer component contains an acrylic monomer (a) having a (meth)acryloyl group, At least a portion of the acrylic monomer (a) is a monomer (a1) having an epoxy group, At least a portion of the acrylic monomer (a) is a monomer (a2) having two or more (meth)acryloyl groups. A composition for forming a hard coat layer. [2] The hard coat layer forming composition according to [1], wherein the proportion of monomer (a2) to acrylic monomer (a) is 50% by mass or more and 99.5% by mass or less. [3] The monomer (a2) contains monomer (a2-1) having three or more (meth)acryloyl groups, The hard coat layer forming composition according to [1] or [2], wherein the proportion of monomer (a2-1) to monomer (a2) is 50% by mass or more. [4] A hard coat layer forming composition according to any one of [1] to [3], wherein the content of monomers having a hydroxyl group is 40% by mass or less based on the total amount of the monomer components. [5] A hard coat layer forming composition according to any one of [1] to [4], wherein the proportion of monomer (a1) in the acrylic monomer (a) is 0.5% by mass or more and 10% by mass or less. [6] The hard coat layer forming composition according to any one of [1] to [5], wherein the content of the radical polymerization initiator is 0.11 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the monomer component. [7] A hard coat layer forming composition according to any one of [1] to [6], for forming a hard coat layer that is laminated together with a polarizer to constitute a polarizing plate. [8] The hard coat-forming composition according to [7], wherein the polarizer contains a polyvinyl alcohol-based resin layer in which iodine is adsorbed and oriented. [9] A hard coat layer comprising a cured product of the hard coat-forming composition according to any one of [1] to [8].

[10] Comprising an acrylic polymer having a monomer unit (A) derived from an acrylic monomer (a) having a (meth)acryloyl group, At least a part of the monomer unit (A) is a monomer unit (A1) derived from a monomer (a1) having an epoxy group, At least a part of the monomer unit (A) is a monomer unit (A2) derived from a monomer (a2) having two or more (meth)acryloyl groups, Hard coat layer.

[11] The hard coat layer according to

[10] , wherein the proportion of the monomer unit (A2) in the monomer unit (A) is 50% by mass or more and 99.5% by mass or less.

[12] The monomer unit (A2) contains a monomer unit (A2-1) derived from a monomer (a2-1) having three or more (meth)acryloyl groups, The hard coat layer according to

[10] or

[11] , wherein the proportion of the monomer unit (A2-1) in the monomer unit (A2) is 50% by mass or more.

[13] In the acrylic polymer, the content of the monomer unit derived from the monomer having a hydroxy group is 40% by mass or less based on the total amount of all monomer units in the acrylic polymer. The hard coat layer according to any one of

[10] to

[12] .

[14] The hard coat layer according to any one of

[10] to

[13] , wherein the proportion of the monomer unit (A1) in the monomer unit (A) is 0.5% by mass or more and 10% by mass or less.

[15] A polarizer and A protective film having the hard coat layer according to any one of [9] to

[14] , A polarizing plate comprising the same.

[16] The polarizing plate according to

[15] , wherein the polarizer contains a polyvinyl alcohol-based resin layer in which iodine is adsorbed and oriented.

[17] An image display device comprising the polarizing plate according to

[15] or

[16] and an image display panel. [Effect of the Invention]

[0006] According to the present disclosure, there is provided a composition for forming a hard coat layer capable of suppressing the occurrence of red shift in a polarizing plate. Further, according to the present disclosure, there are provided a hard coat layer capable of suppressing the occurrence of red shift in a polarizing plate, a polarizing plate provided with the hard coat layer, and an image display device. [Brief Description of the Drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a polarizing plate. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of an image display device. [Modes for Carrying Out the Invention]

[0008] Hereinafter, preferred embodiments of the present disclosure will be described in detail.

[0009] [Composition for Forming Hard Coat Layer] The composition for forming a hard coat layer of the present embodiment is a curable composition containing a monomer component and a radical polymerization initiator.

[0010] The monomer component contains an acrylic monomer (a) having a (meth)acryloyl group. At least a part of the acrylic monomer (a) is a monomer (a1) having an epoxy group. Further, at least a part of the acrylic monomer (a) is a monomer (a2) having two or more (meth)acryloyl groups. The (meth)acryloyl group means an acryloyl group or a methacryloyl group.

[0011] In the acrylic monomer (a), monomer (a1) having an epoxy group may be polyfunctional or monofunctional. Furthermore, monomer (a2) may also have an epoxy group.

[0012] In other words, acrylic monomer (a) may include monomers having an epoxy group and one (meth)acryloyl group (monomers corresponding to monomer (a1) but not monomer (a2)), monomers not having an epoxy group and having two or more (meth)acryloyl groups (monomers not corresponding to monomer (a1) but corresponding to monomer (a2)), and monomers having an epoxy group and having two or more (meth)acryloyl groups (monomers corresponding to both monomer (a1) and monomer (a2)). Furthermore, acrylic monomer (a) may include monomers not having an epoxy group and having one (meth)acryloyl group (monomers not corresponding to either monomer (a1) or monomer (a2)).

[0013] According to the inventors' findings, when ammonia gas that enters from the outside comes into contact with the polarizer, the polarizer changes to a reddish color. The hard coat layer forming composition of this embodiment contains a monomer (a1) having an epoxy group as a monomer component, so epoxy groups (or derivatives thereof) remain in the cured product. In other words, with the hard coat layer forming composition of this embodiment, a hard coat layer having epoxy groups (or derivatives thereof) is formed, and this hard coat layer traps the ammonia gas, preventing the ammonia gas from entering the polarizer and suppressing the reddish color change of the polarizer.

[0014] Furthermore, since the hard coat layer forming composition of this embodiment contains monomer (a2) as a monomer component, the hardness of the cured product is increased, and a hard coat layer with sufficient hardness can be formed. For this reason, the hard coat layer formed from the hard coat layer forming composition of this embodiment can be easily introduced into a polarizing plate by replacing the hard coat layer of an existing polarizing plate or by adding it to the resin layer of an existing polarizing plate.

[0015] Monomer (a1) is a compound having a (meth)acryloyl group and an epoxy group.

[0016] The monomer (a1) may be a compound having one (meth)acryloyl group, or a compound having two or more (meth)acryloyl groups. The number of (meth)acryloyl groups in monomer (a1) may be, for example, 4 or less, 3 or less, or 2 or less.

[0017] The monomer (a1) may be a compound having one epoxy group, or a compound having two or more epoxy groups. The number of epoxy groups in monomer (a1) may be, for example, four or less, three or less, or two or less.

[0018] As monomer (a1), a compound having one (meth)acryloyl group and one epoxy group (hereinafter also referred to as monomer (a1')) can be suitably used.

[0019] Examples of monomer (a1) include glycidyl acrylate and glycidyl methacrylate, with glycidyl methacrylate being preferred.

[0020] The monomer (a1) may be used alone, in combination of two or more types, or a commercially available product containing two or more types may be used.

[0021] The proportion of monomer (a1) in acrylic monomer (a) (i.e., the amount of monomer (a1) on a basis of the total amount of acrylic monomer (a)) may be, for example, 0.5% by mass or more, and may be 0.7% by mass or more, 0.9% by mass or more, 1% by mass or more, 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more. A higher proportion of monomer (a1) tends to more significantly suppress reddening due to ammonia gas. Furthermore, the proportion of monomer (a1) in acrylic monomer (a) may be, for example, 10% by mass or less, and may be 8% by mass or less, 6% by mass or less, 5% by mass or less, or 4% by mass or less. A lower proportion of monomer (a1) tends to make it easier to obtain a hard coat layer with higher hardness.

[0022] Monomer (a2) is a compound having two or more (meth)acryloyl groups.

[0023] The monomer (a2) may or may not have an epoxy group. From the viewpoint of ease of obtaining the monomer, the monomer (a2) may be a compound without an epoxy group.

[0024] Monomer (a2) may be a compound having two (meth)acryloyl groups, or a compound having three or more (meth)acryloyl groups (hereinafter also referred to as monomer (a2-1)). The number of (meth)acryloyl groups in monomer (a2) and monomer (a2-1) may be, for example, 10 or less, 8 or less, 6 or less, or 4 or less.

[0025] From the viewpoint of making it easier to obtain a hard coat layer with higher hardness, it is preferable that monomer (a2) has a high proportion of monomer (a2-1). The proportion of monomer (a2-1) in monomer (a2) (i.e., the amount of monomer (a2-1) on a basis of the total amount of monomer (a2)) may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more, or 100% by mass.

[0026] Examples of monomers (a2) that have two (meth)acryloyl groups include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tricyclodecanedimethanol di(meth)acrylate.

[0027] As for compounds having two (meth)acryloyl groups, compounds that can be synthesized from diols with a small molecular weight, such as ethylene glycol di(meth)acrylate and 1,4-butanediol di(meth)acrylate are preferred.

[0028] Examples of monomers (a2) include monomer (a2-1), such as pentaerythritol tetra(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, PO-modified pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and glycerin tri(meth)acrylate.

[0029] Preferred monomers (a2-1) include pentaerythritol tetra(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, PO-modified pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and glycerin tri(meth)acrylate.

[0030] Trimethylolpropane triacrylate and glycerin triacrylate are more preferred as monomers (a2-1). Because these monomers have a relatively small acrylic equivalent, they can form a cured product with a denser network structure. The formation of a denser network structure reduces the permeation rate of ammonia molecules and increases the opportunities for ammonia molecules to be captured by epoxy groups, thereby further improving the ammonia gas blocking properties of the hard coat layer. These monomers are also preferred because they have few functional groups and are readily available as commercially produced products with relatively large acrylic equivalents and low impurity content. Furthermore, glycerin triacrylate is preferred because its low viscosity makes it easier to reduce the amount of organic solvent in the hard coat layer forming composition (or to create a composition that does not contain organic solvents). In addition, since glycerin triacrylate is obtained from vegetable oil, which is biomass, as a raw material for glycerin, it can also contribute to carbon neutrality.

[0031] The monomer (a2) may be used alone, in combination of two or more types, or a commercially available product containing two or more types may be used.

[0032] Examples of commercially available monomers (a2) include "NK Ester A-DCP", "NK Ester DCP", "NK Ester A-TMPT", "NK Ester TMPT", "NK Ester ATM-35E", and "NK Ester A-TMMT" from Shin Nakamura Chemical Industry Co., Ltd., "Viscote® #195", "Viscote® #300", and "Viscote® #360" from Osaka Organic Chemical Industry Co., Ltd., the acrylate monomers "IRR 214-K", "PETIA", "PETRA", "TMPTA", "TMPEOTA", "EBECRYL 135", "OTA 480", and "EBECRYL L 40" from Daicel Ornex Co., Ltd., "BS710" and "BS730" from Arakawa Chemical Industries, Ltd., and "Aronics® M-920" and "Aronics® M-930" from Toagosei Co., Ltd. Of these, "Aronics® M-930," a commercially available glycerin triacrylate manufactured by Toagosei Co., Ltd., is particularly preferred.

[0033] The proportion of monomer (a2) in acrylic monomer (a) (i.e., the monomer (a2) content on a total basis of acrylic monomer (a)) may be, for example, 50% by mass or more, and may be 70% by mass or more, 90% by mass or more, 92% by mass or more, 94% by mass or more, 95% by mass or more, or 96% by mass or more. A higher proportion of monomer (a2) tends to result in a harder hard coat layer. Furthermore, the proportion of monomer (a2) in acrylic monomer (a) may be, for example, 99.5% by mass or less, and may be 99.3% by mass or less, 99.1% by mass or less, 99% by mass or less, 98.5% by mass or less, 98% by mass or less, or 97.5% by mass or less.

[0034] The acrylic monomer (a) may contain a monomer that does not fall under either monomer (a1) or monomer (a2), that is, a compound having one (meth)acryloyl group and no epoxy group (hereinafter also referred to as monomer (a3)).

[0035] Examples of monomers (a3) ​​include alkyl (meth)acrylates (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, etc.).

[0036] The proportion of monomer (a3) ​​in acrylic monomer (a) may be, for example, 40% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, or even 0% by mass. That is, the total amount of monomers in acrylic monomer (a) that correspond to at least one of monomer (a1) and monomer (a2) may be, for example, 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, or even 100% by mass, based on the total amount of acrylic monomer (a).

[0037] The acrylic monomer (a) may, for example, include a compound having one (meth)acryloyl group and one epoxy group as monomer (a1') as monomer (a1), and a compound having two or more (meth)acryloyl groups and no epoxy groups as monomer (a2') as monomer (a2).

[0038] In this case, the total amount of monomer (a1') and monomer (a2') may be, for example, 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, or 100% by mass, based on the total amount of acrylic monomer (a).

[0039] The monomer component may further contain other monomers besides the acrylic monomer (a).

[0040] Other monomers can be any monomer that can be radically polymerized with acrylic monomer (a). Examples of other monomers include styrene.

[0041] The proportion of acrylic monomer (a) in the monomer components (i.e., the content of acrylic monomer (a) on a basis of the total amount of monomer components) may be, for example, 80% by mass or more, and from the viewpoint of obtaining the above-mentioned effects more significantly, it may be 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more, or even 100% by mass.

[0042] The monomer component may contain monomer (b) having a hydroxyl group. Monomer (b) may exist, for example, as a byproduct during the synthesis of monomer (a2).

[0043] The monomer (b) content may be, for example, 40% by mass or less based on the total amount of monomer components, and may also be 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less, or even 0% by mass. By reducing the monomer (b) content, the consumption of epoxy groups due to the reaction between hydroxyl groups and epoxy groups can be avoided, and the reddening of the polarizing plate by ammonia gas can be suppressed more significantly.

[0044] A radical polymerization initiator can be any agent that generates radicals and initiates the polymerization reaction of monomer components. Photoradical polymerization initiators are preferred as radical polymerization initiators.

[0045] As the radical polymerization initiator, known radical polymerization initiators may be used. For example, as radical polymerization initiators, those exemplified as polymerization initiators in Japanese Patent Application Publication No. 2014-170130 and those exemplified as photoradical initiators in Japanese Patent Application Publication No. 2009-098658 may be used as appropriate.

[0046] Examples of radical polymerization initiators include acetophenones, benzoins, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfonium compounds, rhofin dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins.

[0047] The radical polymerization initiator may be a commercially available product. Examples of commercially available photoradical polymerization initiators include BASF's "Irgacure® 651", "Irgacure® 184", "Irgacure® 819", "Irgacure® 907", "Irgacure® 1870" (CGI-403 / Irgacure® 184 = 7 / 3 mixed initiator), "Irgacure® 500", "Irgacure® 369", "Irgacure® 1173", "Irgacure® 2959", "Irgacure® 4265", "Irgacure® 4263", "Irgacure® 127", "OXE01", etc.; and Nippon Kayaku Co., Ltd.'s "Kayacure® Examples include "DETX-S", "KayaCure® BP-100", "KayaCure® BDMK", "KayaCure® CTX", "KayaCure® BMS", "KayaCure® 2-EAQ", "KayaCure® ABQ", "KayaCure® CPTX", "KayaCure® EPD", "KayaCure® ITX", "KayaCure® QTX", "KayaCure® BTC", "KayaCure® MCA", etc.; and "Esacure®" manufactured by Sartmar (KIP100F, KB1, EB3, BP, X33, KTO46, KT37, KIP150, TZT), etc.

[0048] Radical polymerization initiators may be used individually or in combination of two or more types.

[0049] The content of the radical polymerization initiator may be, for example, 0.1 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more, per 100 parts by mass of the monomer component. Alternatively, the content of the radical polymerization initiator may be, for example, 15 parts by mass or less, 10 parts by mass or less, 8 parts by mass or less, 6 parts by mass or less, or 5 parts by mass or less, per 100 parts by mass of the monomer component.

[0050] From the viewpoint of avoiding a reduction in effectiveness due to the consumption of epoxy groups, it is desirable that compositions for forming a hard coat layer substantially contain cationic polymerization initiators (especially photocationic polymerization initiators). Substantially containing cationic polymerization initiators means, for example, that the content of cationic polymerization initiators is 0.3 parts by mass or less per 100 parts by mass of monomer components. The content of cationic polymerization initiators may be 0.2 parts by mass or less, 0.1 parts by mass or less, or 0 parts by mass per 100 parts by mass of monomer components.

[0051] The hard coat layer forming composition may further contain other components besides those mentioned above.

[0052] The hard coat layer forming composition may contain, for example, a solvent. A hard coat layer forming composition containing a solvent can be suitably used as a coating liquid for forming a hard coat layer (also called a hard coat layer forming coating liquid or hard coat liquid).

[0053] The solvent is not particularly limited and any solvent capable of dissolving the monomer component is acceptable. A solvent that dries easily is preferred.

[0054] Examples of solvents include ketone-based solvents such as methyl ethyl ketone, acetylacetone, and acetone; ester-based solvents such as dimethyl carbonate, methyl acetate, and ethyl acetate; and aromatic hydrocarbon-based solvents such as toluene.

[0055] The solvent may be appropriately selected depending on the type of monomer component, etc. Furthermore, the solvent may be appropriately selected depending on the type of resin layer (base film) on which the hard coat layer is formed, etc. For example, when using a cellulose acylate film as the base film, using methyl ethyl ketone, methyl acetate, acetone, toluene, etc. as the solvent tends to further improve the adhesion between the base film and the hard coat layer.

[0056] The solvent may be used alone or in combination of two or more types.

[0057] The solvent content is not particularly limited, and may be adjusted as appropriate, for example, so that the solid content concentration of the hard coat layer forming solution falls within the preferred range described later.

[0058] When the hard coat layer forming composition is a coating liquid containing a solvent, the solid content concentration of the coating liquid may be, for example, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more. Alternatively, the solid content concentration of the hard coat layer forming coating liquid may be, for example, 90% by mass or less, 80% by mass or less, 75% by mass or less, or 70% by mass or less.

[0059] The hard coat layer forming composition may further contain additives as components other than those mentioned above. Examples of additives include silica fine particles, fluorine-containing compounds, and silicone-based compounds.

[0060] The amount of additives is not particularly limited and may be adjusted as appropriate within the range in which the above-described effects can be obtained. The amount of additives may be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, or even 0% by mass, based on the total amount of solids in the hard coat layer forming composition. That is, the total amount of monomer components and radical polymerization initiators in the hard coat layer forming composition may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, or even 100% by mass, based on the total amount of solids.

[0061] The cured product of the hard coat layer forming composition functions as a hard coat layer. The cured product of the hard coat layer forming composition can also be defined as the cured solid component of the hard coat layer forming composition. For example, when the hard coat layer forming composition contains a solvent, the cured product may be the hard coat layer forming composition after drying and curing. That is, the cured product of the hard coat layer forming composition can also be defined as the dried and cured product of the hard coat layer forming composition.

[0062] The hard coat layer forming composition may, for example, be applied to a resin layer as a coating liquid, and then dried and cured to form a hard coat layer.

[0063] The drying method is not particularly limited and should be any method that can sufficiently remove the solvent from the coating film. Examples of drying methods include heating, reduced pressure, and combinations thereof.

[0064] The curing method is not particularly limited and can be any method that generates active species from a radical polymerization initiator and polymerizes the monomer components. Curing may be carried out by, for example, light irradiation. Light irradiation may be, for example, ultraviolet irradiation.

[0065] The conditions for light irradiation are not particularly limited; any conditions that allow for the generation of active species from the radical polymerization initiator and the polymerization of monomer components are acceptable. The conditions for light irradiation may be appropriately adjusted depending on the type and amount of monomer components, the type and amount of radical polymerization initiator, the thickness of the coating film, etc.

[0066] The illuminance during light irradiation is, for example, 100-1000 mW / cm². 2 The irradiation dose in light irradiation may be, for example, 50 to 1000 mJ / cm². 2 That's fine.

[0067] The hard coat layer formed from the hard coat layer forming composition has sufficient hardness as a hard coat layer and can suppress the reddening of the polarizing plate.

[0068] The hard coat layer forming composition may be a composition for forming a hard coat layer that is laminated together with a polarizer to constitute a polarizing plate, and can also be called a hard coat layer forming composition for polarizing plates.

[0069] According to the inventors' findings, when a polarizer contains a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented, it is prone to reddening due to ammonia gas. For this reason, the hard coat layer forming composition of this embodiment can be particularly suitably used as a composition for forming a hard coat layer laminated on a polarizer containing a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented.

[0070] <Hard coat layer> The hard coat layer of this embodiment contains an acrylic polymer having monomer units (A) derived from an acrylic monomer (a) having a (meth)acryloyl group.

[0071] At least a portion of monomer unit (A) is monomer unit (A1) derived from monomer (a1) having an epoxy group. At least a portion of monomer unit (A) is monomer unit (A2) derived from monomer (a2) having two or more (meth)acryloyl groups.

[0072] In this embodiment, the hard coat layer contains an acrylic polymer with monomer units (A1), and the epoxy groups (or derivatives thereof) of these monomer units (A1) trap ammonia gas. Therefore, the hard coat layer of this embodiment prevents ammonia gas from entering the polarizer and suppresses the reddening of the polarizer.

[0073] The hard coat layer of this embodiment may be used to replace the hard coat layer of an existing polarizing plate, or it may be placed on top of the resin layer of an existing polarizing plate.

[0074] The hard coat layer in this embodiment may be formed from the hard coat layer forming composition described above.

[0075] In an acrylic polymer, monomer units may be derived from a monomer having an epoxy group and one (meth)acryloyl group (a monomer that corresponds to monomer (a1) but not monomer (a2)) (monomer units that correspond to monomer (A1) but not monomer (A2)), or monomer units may be derived from a monomer that does not have an epoxy group and has two or more (meth)acryloyl groups (a monomer that does not correspond to monomer (a1) but corresponds to monomer (a2)) (monomer units that do not correspond to monomer (A1) but correspond to monomer (A2)), or monomer units may be derived from a monomer having an epoxy group and two or more (meth)acryloyl groups (a monomer that corresponds to both monomer (a1) and monomer (a2)) (monomer units that correspond to both monomer (A1) and monomer (A2)). Furthermore, the acrylic polymer may have monomer units derived from monomers that do not have epoxy groups and have one (meth)acryloyl group (monomers that do not fall under either monomer (a1) or monomer (a2)).

[0076] In this specification, "monomer-derived monomer units" refers to constituent units that can be formed by the polymerization reaction of monomers.

[0077] A monomer unit (A1) is a monomer unit derived from a monomer (a1). Examples of monomers (a1) are the same as those mentioned above.

[0078] The ratio of monomer units (A1) to monomer units (A) (i.e., the content of monomer units (A1) relative to the total amount of monomer units (A)) may be, for example, 0.5% by mass or more, and may be 0.7% by mass or more, 0.9% by mass or more, 1% by mass or more, 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more. A higher ratio of monomer units (A1) tends to more significantly suppress reddening due to ammonia gas. Furthermore, the ratio of monomer units (A1) to monomer units (A) may be, for example, 10% by mass or less, and may be 8% by mass or less, 6% by mass or less, 5% by mass or less, or 4% by mass or less. A lower ratio of monomer units (A1) tends to make it easier to obtain a hard coat layer with higher hardness.

[0079] A monomer unit (A2) is a monomer unit derived from a monomer (a2). Examples of monomers (a2) are the same as those mentioned above.

[0080] The monomer unit (A2) may be a monomer unit derived from a compound having two (meth)acryloyl groups, or it may be a monomer unit (A2-1) derived from a compound having three or more (meth)acryloyl groups (monomer (a2-1)). Examples of compounds having two (meth)acryloyl groups and monomer (a2-1) are the same as those described above.

[0081] From the viewpoint of achieving higher hardness in the hard coat layer, it is preferable that monomer units (A2) have a high proportion of monomer units (A2-1). The proportion of monomer units (A2-1) to monomer units (A2) (i.e., the content of monomer units (A2-1) based on the total amount of monomer units (A2)) may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more, or even 100% by mass.

[0082] The ratio of monomer units (A2) to monomer units (A) (i.e., the content of monomer units (A2) on a basis of the total amount of monomer units (A)) may be, for example, 50% by mass or more, and may also be 70% by mass or more, 90% by mass or more, 92% by mass or more, 94% by mass or more, 95% by mass or more, or 96% by mass or more. A higher ratio of monomer units (A2) tends to result in a higher hardness of the hard coat layer. Furthermore, the ratio of monomer units (A2) to monomer units (A) may be, for example, 99.5% by mass or less, and may also be 99.3% by mass or less, 99.1% by mass or less, 99% by mass or less, 98.5% by mass or less, 98% by mass or less, or 97.5% by mass or less.

[0083] Monomer unit (A) may contain monomer unit (A3) that does not correspond to either monomer unit (A1) or monomer unit (A2). Monomer unit (A3) can be defined as a monomer that does not correspond to either monomer (a1) or monomer (a2), that is, a monomer unit derived from a compound having one (meth)acryloyl group and no epoxy group (hereinafter also referred to as monomer (a3)). Examples of monomer (a3) ​​are the same as those mentioned above.

[0084] The monomer unit (A) may, for example, include monomer unit (A1') derived from a compound (monomer (a1')) having one (meth)acryloyl group and one epoxy group as monomer unit (A1), and monomer unit (A2') derived from a compound (monomer (a2')) having two or more (meth)acryloyl groups and no epoxy groups as monomer unit (a2').

[0085] In this case, the total amount of monomer units (A1') and monomer units (A2') may be, for example, 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, or even 100% by mass, based on the total amount of monomer units (A).

[0086] The acrylic polymer may further contain other monomer units besides monomer unit (A).

[0087] Other monomeric units include monomeric units derived from the other monomers mentioned above.

[0088] The monomer unit (A) content in the acrylic polymer may be, for example, 80% by mass or more, based on the total amount of all monomer units in the acrylic polymer. From the viewpoint of obtaining the above-mentioned effects more significantly, it may be 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more, or even 100% by mass.

[0089] The acrylic polymer may contain monomer units (B) derived from monomer (b) having a hydroxyl group. Examples of monomer (b) are the same as those described above.

[0090] The monomer unit (B) content in the acrylic polymer may be, for example, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less, or even 0% by mass, based on the total amount of all monomer units in the acrylic polymer.

[0091] The hard coat layer may further contain additives as components other than the acrylic polymer. Examples of additives include silica nanoparticles, fluorine-containing compounds, and silicone compounds.

[0092] The amount of additives is not particularly limited and may be adjusted as appropriate within the range in which the above-mentioned effects can be obtained. The amount of additives may be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, or even 0% by mass, based on the total amount of the hard coat layer. That is, the amount of acrylic polymer in the hard coat layer may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, or even 100% by mass.

[0093] The hard coat layer can be formed, for example, by applying the above-mentioned hard coat layer forming composition as a coating liquid onto the resin, and then drying and curing it.

[0094] The hard coat layer may have a pencil hardness of, for example, H or higher. Such a hard coat layer can be suitably used as a hard coat layer for polarizing plates. The pencil hardness of the hard coat layer may be, for example, 2H or higher, or 3H or higher. Furthermore, from the viewpoint of balancing hardness and resistance to cracking, the pencil hardness of the hard coat layer may be, for example, 4H or lower.

[0095] In this specification, the pencil hardness of the hard coat layer is measured according to the "scratch hardness (pencil method)" described in JIS K 5600.

[0096] The thickness of the hard coat layer may be, for example, 3 μm or more, but may also be 4 μm or more, 5 μm or more, or 6 μm or more. A thicker hard coat layer allows the hard coat layer to trap ammonia gas more reliably, and can more significantly suppress the reddening of the polarizer. The thickness of the hard coat layer may be, for example, 20 μm or less, but may also be 15 μm or less, 12 μm or less, or 10 μm or less. A thinner hard coat layer reduces the overall thickness of the polarizer, allowing for a smaller size polarizer.

[0097] The hard coat layer in this embodiment may be a hard coat layer that is laminated together with a polarizer to form a polarizing plate, and can also be called a hard coat layer for polarizing plates.

[0098] According to the inventors' findings, when a polarizer contains a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented, it is prone to reddening due to ammonia gas. For this reason, the hard coat layer of this embodiment can be particularly suitably used as a hard coat layer laminated on a polarizer containing a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented.

[0099] <Polarizing plate> The polarizing plate of this embodiment comprises a polarizer and a first protective film disposed on one side of the polarizer. The first protective film has the hard coat layer described above (a hard coat layer formed from the hard coat layer forming composition of the above embodiment, or the hard coat layer of the above embodiment).

[0100] The polarizing plate of this embodiment is equipped with a specific hard coat layer, which allows ammonia gas that enters from the outside to be trapped by the hard coat layer, thereby suppressing the reddening of the polarizing plate.

[0101] The polarizing plate of this embodiment may be equipped with a first protective film on the viewing side of the polarizer. This makes it possible to suppress the intrusion of ammonia gas, which is present or generated on the viewing side of the polarizer, into the polarizer.

[0102] The polarizing plate of this embodiment may further include a second protective film disposed on the other side of the polarizer. The second protective film may or may not have the hard coat layer described above (a hard coat layer formed from the hard coat layer forming composition of the above embodiment, or the hard coat layer of the above embodiment).

[0103] The polarizing plate of this embodiment may further include a first bonding layer for bonding a polarizer and a first protective film. Alternatively, the polarizing plate of this embodiment may further include a second bonding layer for bonding a polarizer and a second protective film.

[0104] The polarizer may be any polarizer used in a known polarizer plate.

[0105] The polarizer may be, for example, a polyvinyl alcohol-based resin layer on which a dichroic dye is adsorbed and oriented.

[0106] The polyvinyl alcohol-based resin layer may be, for example, a uniaxially oriented film.

[0107] The polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin layer may be, for example, a saponified polyvinyl acetate-based resin. The degree of saponification of the polyvinyl acetate-based resin may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 99 mol% or more.

[0108] Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers. The other monomer can be any monomer copolymerizable with vinyl acetate, such as unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids.

[0109] The degree of polymerization of the polyvinyl alcohol-based resin (or the polyvinyl acetate-based resin) may be, for example, 1000 or more, or 1500 or more. Furthermore, the degree of polymerization of the polyvinyl alcohol-based resin (or the polyvinyl acetate-based resin) may be, for example, 10000 or less, or 5000 or more.

[0110] The polyvinyl alcohol-based resin may be modified. Examples of modified polyvinyl alcohol-based resins include polyvinyl formal, polyvinyl acetal, and polyvinyl butyral modified with aldehydes.

[0111] Examples of dichroic dyes include iodine and water-soluble dichroic dyes.

[0112] The thickness of the polarizer is not particularly limited, but may be, for example, 1 μm or more, 5 μm or more, or 8 μm or more. Alternatively, the thickness of the polarizer may be, for example, 50 μm or less, 40 μm or less, or 30 μm or less.

[0113] The method for manufacturing the polarizer is not particularly limited, and known methods can be used. For example, the method for manufacturing the polarizer may involve sequentially performing a swelling step, a dyeing step, a crosslinking step, a washing step, and a drying step.

[0114] The swelling process involves immersing the raw film in a swelling solution to cause it to swell. The raw film may be a polyvinyl alcohol-based resin film.

[0115] The dyeing process involves immersing the film, after the swelling process, in a dyeing solution containing a dichroic dye, thereby adsorbing and orienting the dichroic dye onto the film.

[0116] The crosslinking process is a process of bringing a crosslinking solution into contact with the film to perform a crosslinking treatment. The crosslinking process may be performed for purposes such as water resistance, hue adjustment (complementary color), etc. The crosslinking treatment may be performed multiple times. When the crosslinking treatment is performed multiple times, the crosslinking treatment may be performed multiple times for the purpose of water resistance, or multiple crosslinking treatments may be performed multiple times for the purpose of hue adjustment. However, it is preferable to perform the crosslinking treatment for the purpose of water resistance at least once and the crosslinking treatment for the purpose of hue adjustment at least once, and it is more preferable to perform the crosslinking treatment for the purpose of hue adjustment after the crosslinking treatment for the purpose of water resistance.

[0117] The washing process involves washing the film after the crosslinking process by immersing it in a washing solution. The washing solution may be, for example, water. The drying process involves drying the film after the washing process. The drying method is not particularly limited and may be, for example, a method of heating the film after the washing process at 30 to 100°C.

[0118] In the polarizer manufacturing method, uniaxial stretching may be performed as a stretching process between each step, that is, before, after, or during any one or more steps.

[0119] The first protective film comprises a resin layer as a base material (also called a base film) and a hard coat layer provided on one side of the resin layer.

[0120] The resin layer is not particularly limited and can be appropriately selected from various transparent films that can be used for polarizing plates. The material constituting the resin layer may be, for example, a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc.

[0121] Examples of thermoplastic resins that constitute the resin layer include cellulose ester resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; (meth)acrylic resins; cyclic polyolefin resins such as cycloolefin resins and norbornene resins; polyarylate resins; polystyrene resins; and polyvinyl alcohol resins. The materials that constitute the resin layer may also be mixtures of these.

[0122] The resin layer may also be a cured resin layer formed from a curable resin. Examples of curable resins include (meth)acrylic, urethane, acrylic urethane, epoxy, and silicone resins. The curable resin may be a thermosetting resin or an ultraviolet curable resin.

[0123] As the material constituting the resin layer, at least one thermoplastic resin selected from the group consisting of cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins is preferred.

[0124] On the side of the resin layer of the first protective film opposite to the side to which the polarizer is bonded, a functional layer other than the hard coat layer (for example, an anti-reflective layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, etc.) may be provided. These functional layers may be provided as part of the first protective film, or they may be provided separately as a separate component from the first protective film.

[0125] The thickness of the first protective film is not particularly limited, but from the viewpoint of handling in the manufacturing process, it may be, for example, 1 μm or more, 10 μm or more, 20 μm or more, or 30 μm or more. Also, from the viewpoint of thinning the polarizing plate, the thickness of the first protective film may be, for example, 200 μm or less, 100 μm or less, 80 μm or less, or 60 μm or less.

[0126] The first protective film has a moisture permeability of 350 g / m² in an environment with a temperature of 40°C and a relative humidity of 90%. 2 It may be less than or equal to 24 hours. The above moisture permeability is measured in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0127] The above moisture permeability is 300g / (m 2 It may be less than 24 hours, and 200g / (m 2 It may be less than 24 hours. Also, the above moisture permeability is, for example, 50 g / (m 2 • 24 hours or more, and 80g / (m 2 • 24 hours or more, or 100g / (m 2 • 24 hours or longer is also acceptable.

[0128] The first protective film may be bonded to the polarizer, for example, via the first bonding layer described later. The first protective film may be bonded to the polarizer on the side opposite to the side on which the hard coat layer is provided.

[0129] Either one or both of the surfaces of the first protective film to which the polarizer is bonded, and the surfaces of the polarizer to which the first protective film is bonded, may be surface-treated. Examples of surface treatments include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0130] The second protective film has a resin layer (base film) as a substrate.

[0131] As the resin layer in the second protective film, the same one as the resin layer in the first protective film can be exemplified.

[0132] On the surface of the resin layer in the second protective film opposite to the surface to which the polarizer is bonded, functional layers such as a hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer, and an antiglare layer may be provided. These functional layers may be provided as a part of the second protective film, or may be provided separately as a separate body from the second protective film.

[0133] The second protective film may have, as the functional layer, the above-mentioned hard coat layer (the hard coat layer formed from the hard coat layer-forming composition of the above embodiment, or the hard coat layer of the above embodiment).

[0134] The thickness of the second protective film is not particularly limited, but from the viewpoint of handling properties in the manufacturing process, it may be, for example, 1 μm or more, and may be 10 μm or more, 20 μm or more, or 30 μm or more. Also, from the viewpoint of thinning the polarizing plate, the thickness of the second protective film may be, for example, 200 μm or less, and may be 100 μm or less, 80 μm or less, or 60 μm or less.

[0135] The second protective film may have, for example, a moisture permeability of 350 g / (m 2 ·24 h) or less in an environment of 40°C and 90% relative humidity. The above moisture permeability is measured in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0136] The above moisture permeability may be 300 g / (m 2 ·24 h) or less, and may be 200 g / (m 2 ·24 h) or less. Also, the above moisture permeability may be, for example, 50 g / (m 2 ·24 h) or more, and may be 80 g / (m 2 ·24 h) or more, or 100 g / (m 2 ·24 h) or more.

[0137] The second protective film may be bonded to the polarizer, for example, via a second bonding layer described later. The second protective film may be bonded to the polarizer on the side opposite to the side where the hard coat layer is provided.

[0138] Either one or both of the surfaces of the second protective film to which the polarizer is bonded, and the surfaces of the polarizer to which the second protective film is bonded, may be surface-treated. Examples of surface treatments include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0139] The first bonding layer is the layer that bonds the first protective film to the polarizer, and the second bonding layer is the layer that bonds the second protective film to the polarizer.

[0140] The first and second bonding layers may be adhesive layers or adhesive layers (curable adhesive layers), and are preferably adhesive layers (curable adhesive layers).

[0141] The adhesive layer may be a layer composed of an adhesive composition. The adhesive composition may be any adhesive composition that exhibits excellent optical transparency and can be appropriately selected from known adhesive compositions. Examples of adhesive compositions include those having acrylic resins, urethane resins, silicone resins, polyvinyl ether resins, etc., as base polymers. Of these, adhesive compositions using acrylic resins as the base polymer are preferred from the viewpoint of excellent transparency, adhesive strength, re-peelability, weather resistance, heat resistance, etc. The adhesive composition may further contain crosslinking agents, silane compounds, antistatic agents, etc.

[0142] The adhesive layer may be a layer composed of a cured product of the adhesive composition. The adhesive composition can be appropriately selected from known adhesive compositions used for polarizing plates. Examples of adhesive compositions include aqueous adhesive compositions obtained by dissolving or dispersing a curable adhesive component in water, and active energy ray curable adhesive compositions containing active energy ray curable compounds.

[0143] Water-based adhesive compositions are preferred as adhesive compositions. Examples of water-based adhesive compositions include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex adhesives, and water-based polyester adhesives.

[0144] The thickness of the first and second bonding layers is not particularly limited. When using a water-based adhesive composition, the thickness may be, for example, 1 to 5000 nm or 10 to 1000 nm. When using an active energy ray-curable adhesive composition, the thickness of the first and second bonding layers may be, for example, 0.1 to 10 μm or 0.5 to 5 μm. When using an adhesive composition, the thickness of the first and second bonding layers may be, for example, 0.1 to 30 μm, 3 to 30 μm or 5 to 25 μm.

[0145] Figure 1 is a schematic cross-sectional view showing an example of a polarizing plate. As shown in Figure 1, the polarizing plate 10 comprises a polarizer 11 and a first protective film 12 and a second protective film 13 that protect the polarizer 11. In the polarizing plate 10, the first protective film 12 is laminated on one side of the polarizer 11 via a first bonding layer 14, and the second protective film 13 is laminated on the other side of the polarizer 11 via a second bonding layer 15.

[0146] The first protective film 12 is a protective film laminated on the viewing side. The second protective film 13 is a protective film laminated on the panel side. The first protective film 12 and the second protective film 13 may be laminated to the polarizer 11 using, for example, a roll laminating machine.

[0147] <Image display device> The image display device of this embodiment comprises the polarizing plate and the image display panel described above.

[0148] In the image display device of this embodiment, the polarizing plate may be laminated on the image display panel via a third bonding layer.

[0149] The image display device of this embodiment may further include a transparent member laminated on the side of the polarizing plate opposite to the image display panel side. The transparent member may be laminated with the polarizing plate via a fourth bonding layer.

[0150] The image display panel is not particularly limited and may be appropriately selected from known image display panels. Examples of image display panels include liquid crystal display panels, organic electroluminescent (organic EL) display panels, inorganic electroluminescent (inorganic EL) display panels, plasma display panels, and field emission type display panels.

[0151] Examples of transparent components include a front transparent plate (window layer) and a touch panel. A transparent plate with appropriate mechanical strength and thickness is preferred for the front transparent plate. Examples of such transparent plates include transparent resin plates such as acrylic resin and polycarbonate resin, glass plates, and laminates thereof. Examples of touch panels include various types of touch panels such as resistive, capacitive, optical, and ultrasonic touch panels, glass plates with touch sensor functionality, and transparent resin plates with touch sensor functionality.

[0152] The third and fourth bonding layers may be adhesive layers or curable adhesive layers. Examples of adhesive layers and curable adhesive layers are the same as those described above. The third bonding layer is preferably an adhesive layer.

[0153] The image display device may further comprise other layers besides those described above. These other layers may be appropriately selected from, for example, layers applied to known image display devices. The image display device may also further comprise a bonding layer for bonding these layers to the other layers. For example, polarizing plates may be placed on both sides of the image display panel. In this case, the polarizing plate placed on the viewing side of the image display panel may be, for example, the polarizing plate described above, and the polarizing plate placed on the other side may be, for example, a known polarizing plate.

[0154] Figure 2 is a schematic cross-sectional view showing an example of an image display device. As shown in Figure 2, the image display device 100 comprises a polarizing plate 10, an image display panel 20, and a transparent member 30. In the image display device 100, the image display panel 20 is laminated to one side of the polarizing plate 10 via a third bonding layer 40, and the transparent member 30 is laminated to the other side of the polarizing plate 10 via a fourth bonding layer 50. The polarizing plate 10 may be a polarizing plate positioned on the viewing side of the image display panel 20. Positioning the polarizing plate 10 on the viewing side of the image display panel 20 makes it easier to prevent red distortion in the polarizing plate.

[0155] In the image display device 100, the image display panel 20 is laminated on the second protective film 13 side of the polarizing plate 10, and the transparent member 30 is laminated on the first protective film 12 side of the polarizing plate 10.

[0156] Applications of the image display device of this embodiment include, for example, televisions, personal computers, mobile devices (e.g., mobile phones, tablet terminals, etc.), and in-vehicle applications. Specific examples of in-vehicle applications include car navigation systems, speedometers, touch panels for air conditioners, backup monitors, and rear monitors.

[0157] The polarizing plate and image display device of this embodiment are less prone to reddening of the polarizing plate even when exposed to high-temperature environments. For this reason, the polarizing plate and image display device of this embodiment can be suitably used in applications where they may be exposed to high-temperature environments for extended periods. For example, in automotive applications such as car navigation systems and backup monitors, the polarizing plate and image display device may be exposed to high-temperature environments for extended periods. For this reason, the polarizing plate and image display device of this embodiment can be suitably used in automotive applications.

[0158] In this embodiment, "high temperature environment" means an environment of 100°C or higher, and may be, for example, an environment of 105°C or higher. Also, "long period of time" means 100 hours or more, and may be, for example, 120 hours or more.

[0159] The source of ammonia gas is not particularly limited. Examples of ammonia gas include ammonia gas present in the air, and ammonia gas generated in the storage, transportation, and usage environments of polarizing plates and image display devices.

[0160] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above. [Examples]

[0161] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0162] (Manufacturing Example 1: Fabrication of a polarizer) A 30 μm thick polyvinyl alcohol-based resin film was immersed in pure water at 21.5°C for 79 seconds (swelling step), and then immersed for 151 seconds in an aqueous solution at 23°C with a mass ratio of potassium iodide / boric acid / water of 2 / 2 / 100 and containing 1.0 mM iodine (dyeing step). Subsequently, the film removed from the aqueous solution was immersed for 76 seconds in an aqueous solution at 68.5°C with a mass ratio of potassium iodide / boric acid / water of 2.5 / 4 / 100 (first crosslinking step). Subsequently, the film removed from the aqueous solution was immersed for 11 seconds in an aqueous solution at 45°C with a mass ratio of potassium iodide / boric acid / zinc chloride / water of 3 / 5.5 / 0.6 / 100 (second crosslinking step, metal ion treatment step). Subsequently, the film extracted from the aqueous solution was immersed in a washing solution (washing step), and the film extracted from the washing solution was dried at 38°C (drying step) to obtain a polarizer with a thickness of 12 μm in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly carried out in the dyeing step and the first crosslinking step, and the total stretching ratio was 5.85 times. The thickness of the obtained polarizer was measured using a Nikon Corporation digital micrometer "MH-15M".

[0163] (Manufacturing Example 2: Preparation of Adhesive Composition) 50 g of acetoacetyl-modified polyvinyl alcohol resin (manufactured by Mitsubishi Chemical Corporation: Gosenex Z-410) was dissolved in 950 g of pure water, heated at 90°C for 2 hours, and then cooled to room temperature to obtain an acetoacetyl-modified polyvinyl alcohol resin solution. To the obtained acetoacetyl-modified polyvinyl alcohol resin solution, 0.33 parts by mass of maleic acid, 10 parts by mass of glyoxal, and 20 parts by mass of urea were added per 100 parts by mass of the acetoacetyl-modified polyvinyl alcohol resin to obtain an adhesive composition.

[0164] (Example 1) (1) Preparation of a composition for forming a hard coat layer A hard coat layer forming composition is obtained by mixing 94.0 parts by mass of trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-TMPTA), 3.0 parts by mass of glycidyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.), 3.0 parts by mass of a photopolymerization initiator (manufactured by BASF, Irgacure 907), and 81.8 parts by mass of methyl ethyl ketone.

[0165] (2) Preparation of the first protective film A base film (cellulose acylate film TJ40, manufactured by Fujifilm Corporation, 1340 mm wide, 40 μm thick) wound in a roll is unwound, and a hard coat layer formation composition is applied using a die coating method with a slot die at a transport speed of 30 m / min. The coating layer is then dried at 60°C for 150 seconds. Subsequently, under nitrogen purging and an oxygen concentration of approximately 0.1%, an illuminance of 400 mW / cm is applied using an air-cooled metal halide lamp (manufactured by iGraphic Co., Ltd.) with an output of 160 W / cm. 2 , irradiation amount 120mJ / cm 2 The coating layer is cured by irradiation with ultraviolet light to form a hard coat layer. The thickness of the coating layer is adjusted so that the hard coat layer has a thickness of 7 μm. Next, the side of the base film opposite to the hard coat layer is saponified to obtain a protective film (first protective film) having a hard coat layer on one side of the base film. The pencil hardness of the hard coat layer is 3H.

[0166] (3) Fabrication of polarizing plates As a second protective film, a phase difference film (a laminate of a liquid crystal layer (first phase difference layer) and a cycloolefin polymer film (second phase difference layer)) described in

[0147] of International Publication No. 2022 / 158482 is prepared. Next, the first protective film is laminated onto one side of the polarizer fabricated in Manufacturing Example 1 via the adhesive composition prepared in Manufacturing Example 2, and the second protective film is laminated onto the other side via the adhesive composition prepared in Manufacturing Example 2. Lamination is performed using a roll laminating machine. The first protective film is laminated so that the side opposite to the hard coat layer side is on the polarizer side. The second protective film is laminated so that the first phase difference layer is on the polarizer side, and the slow phase axis of the second phase difference layer is parallel to the absorption axis of the polarizer. The amount of adhesive composition prepared in Manufacturing Example 2 applied is adjusted so that the thickness after drying is 80 nm. After lamination using a roll laminating machine, the polarizing plate is dried at 75°C for 8 minutes.

[0167] (Example 2) Except for changing the amount of trimethylolpropane triacrylate to 96.0 parts by mass and the amount of glycidyl methacrylate to 1.0 part by mass, a hard coat layer forming composition, a first protective film, and a polarizing plate are prepared in the same manner as in Example 1.

[0168] (Example 3) Except for changing the amount of trimethylolpropane triacrylate to 64.0 parts by mass and adding 30.0 parts by mass of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., A-TMM-3, triacrylate content: 37% by mass), the hard coat layer forming composition, the first protective film, and the polarizing plate are prepared in the same manner as in Example 1.

[0169] Furthermore, pentaerythritol triacrylate is a compound having a hydroxyl group, and in the hard coat layer forming composition of Example 3, approximately 11% by mass of the monomer component is a compound having a hydroxyl group.

[0170] (Example 4) A hard coat layer forming composition, a first protective film, and a polarizing plate are prepared in the same manner as in Example 1, except that 94.0 parts by mass of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., A-TMM-3, triacrylate content: 37% by mass) is added instead of trimethylolpropane triacrylate.

[0171] In addition, the hard coat layer forming composition of Example 4 is a compound in which approximately 38% by mass of the monomer component has a hydroxyl group.

[0172] (Example 5) A hard coat layer forming composition is obtained by mixing 94.0 parts by mass of glycerin triacrylate (Aronix® M-930, manufactured by Toagosei Co., Ltd.), 3.0 parts by mass of glycidyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.), 3.0 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by BASF), and 51.8 parts by mass of methyl ethyl ketone. Using the obtained hard coat layer forming composition, a hard coat layer forming composition, a first protective film, and a polarizing plate are prepared in the same manner as in Example 1.

[0173] (Comparative Example 1) Except for omitting glycidyl methacrylate and changing the amount of trimethylolpropane triacrylate to 97.0 parts by mass, a hard coat layer forming composition, a first protective film, and a polarizing plate are prepared in the same manner as in Example 1.

[0174] The polarizing plates obtained in Examples 1-5 and Comparative Example 1 were subjected to ammonia gas exposure tests using the following method. The results are shown in Table 1.

[0175] <Ammonia gas exposure test> (1) Fabrication of polarizing plates with adhesive layer An adhesive sheet is prepared by laminating a PET film with a release agent on both sides of a commercially available sheet-type acrylic adhesive layer. The thickness of the adhesive layer is 25 μm, and the storage modulus is 0.06 MPa. One side of the PET film of the adhesive sheet is peeled off to expose the adhesive layer, and this is laminated to the second protective film surface of the polarizing plate prepared above to obtain a polarizing plate with an adhesive layer.

[0176] (2) Preparation of evaluation laminates A polarizing plate with an adhesive layer is cut to a size of 40 mm x 35 mm so that the absorption axis and the longer side are parallel. Next, the PET film on the adhesive layer is peeled off to expose the adhesive layer, and a 50 mm x 40 mm alkali-free glass (Corning's "EAGLE XG") is bonded onto the adhesive layer to obtain an evaluation laminate.

[0177] (3) Ammonia gas exposure test The orthogonal transmittance at a wavelength of 700 nm was measured for the obtained evaluation laminate using a spectrophotometer with an integrating sphere (V-7100, manufactured by JASCO Corporation). The orthogonal transmittance was 0.01% or less in all cases.

[0178] Next, the evaluation laminate and 0.07 ml of 10% ammonia aqueous solution are placed in a 500 ml sealed plastic bottle and left to stand at 60°C for 120 hours. The evaluation laminate is removed, and the orthogonal transmittance is measured using a spectrophotometer with an integrating sphere (JASCO Corporation, V-7100). The ammonia concentration in the sealed plastic bottle in this test is 20,000 ppm.

[0179] [Table 1]

[0180] As shown in Table 1, in Examples 1 to 5, the increase in orthogonal transmittance at a wavelength of 700 nm after exposure of the evaluation laminate to ammonia gas is suppressed compared to Comparative Example 1. In other words, in Examples 1 to 5, the occurrence of red discoloration is suppressed compared to Comparative Example 1.

[0181] Furthermore, a comparison of Examples 1, 3, and 4 confirms that the lower the amount of monomer containing a hydroxyl group, the more significantly the increase in orthogonal transmittance at a wavelength of 700 nm after exposure to ammonia gas, i.e., the suppression of reddening. [Explanation of symbols]

[0182] 10...Polarizing plate, 11...Polarizer, 12...First protective film, 13...Second protective film, 14...First bonding layer, 15...Second bonding layer, 20...Image display panel, 30...Transparent component, 40...Third bonding layer, 50...Fourth bonding layer, 100...Image display device.

Claims

1. It contains a monomer component and a radical polymerization initiator. The monomer component contains an acrylic monomer (a) having a (meth)acryloyl group, At least a portion of the acrylic monomer (a) is a monomer (a1) having an epoxy group, At least a portion of the acrylic monomer (a) is a monomer (a2) having two or more (meth)acryloyl groups. A composition for forming a hard coat layer.

2. The hard coat layer forming composition according to claim 1, wherein the proportion of monomer (a2) to acrylic monomer (a) is 50% by mass or more and 99.5% by mass or less.

3. The monomer (a2) contains monomer (a2-1) having three or more (meth)acryloyl groups, The hard coat layer forming composition according to claim 1, wherein the proportion of monomer (a2-1) to monomer (a2) is 50% by mass or more.

4. The hard coat layer forming composition according to claim 1, wherein the content of monomers having a hydroxyl group is 40% by mass or less based on the total amount of the monomer components.

5. The hard coat layer forming composition according to claim 1, wherein the proportion of monomer (a1) in the acrylic monomer (a) is 0.5% by mass or more and 10% by mass or less.

6. The hard coat layer forming composition according to claim 1, wherein the content of the radical polymerization initiator is 0.1 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the monomer component.

7. The hard coat layer forming composition according to claim 1, for forming a hard coat layer that is laminated together with a polarizer to constitute a polarizing plate.

8. The hard coat forming composition according to claim 7, wherein the polarizer comprises a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented.

9. A hard coat layer comprising a cured product of the hard coat forming composition described in claim 1.

10. The acrylic polymer contains monomer units (A) derived from an acrylic monomer (a) having a (meth)acryloyl group, At least a portion of the monomer unit (A) is a monomer unit (A1) derived from a monomer (a1) having an epoxy group, At least a portion of the monomer unit (A) is a monomer unit (A2) derived from a monomer (a2) having two or more (meth)acryloyl groups. Hard court layer.

11. The hard coat layer according to claim 10, wherein the ratio of monomer unit (A2) to monomer unit (A) is 50% by mass or more and 99.5% by mass or less.

12. The monomer unit (A2) contains monomer units (A2-1) derived from monomers (a2-1) having three or more (meth)acryloyl groups, The hard coat layer according to claim 10, wherein the proportion of monomer units (A2-1) to monomer units (A2) is 50% by mass or more.

13. The hard coat layer according to claim 10, wherein the content of monomer units derived from monomers having a hydroxyl group in the acrylic polymer is 40% by mass or less based on the total amount of all monomer units in the acrylic polymer.

14. The hard coat layer according to claim 10, wherein the ratio of monomer unit (A1) to monomer unit (A) is 0.5% by mass or more and 10% by mass or less.

15. Polarizer and, A protective film having a hard coat layer according to claim 9 or 10, A polarizing plate equipped with a polarizing plate.

16. The polarizer according to claim 15, wherein the polarizer includes a polyvinyl alcohol-based resin layer on which iodine is adsorbed and oriented.

17. An image display device comprising a polarizing plate and an image display panel as described in claim 15.

Images