Laminate, polarizer protective film, and polarizing plate

Abstract

To provide: a laminate which is excellent in adhesion between a substrate thereof and a hard coat layer, and surface hardness and surface smoothness of the hard coat layer, in the laminate which has the hard coat layer imparting scratch resistance, the surface hardness, the surface smoothness and so on, to the surface of the substrate including a (meth)acryl-based polymer; a polarizer protective film composed of the laminate; and a polarizing plate formed by sticking the polarizer protective film and the polarizer to each other.SOLUTION: A laminate comprises a hard coat layer including a cured product of a curable composition, which is directly laminated on a surface of a substrate including a (meth)acryl-based polymer (S), in which the curable composition includes a (meth)acrylate (M) having three or more double bonds capable of radical polymerization and a (meth)acryl-based polymer (P) with mass average molecular weight of 1,000 to 70,000.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate having a hard coat layer that imparts scratch resistance, surface hardness, smoothness, and the like to a surface of a (meth)acrylic polymer-containing substrate; a polarizer protective film made of this laminate; and a polarizing plate obtained by bonding this polarizer protective film to a polarizer. [Background technology]

[0002] Conventionally, triacetyl cellulose (TAC) films have been used as protective films for polarizing plates used in liquid crystal displays. Triacetyl cellulose (TAC) films generally have low surface hardness, so a hard coat layer is formed on the surface of the TAC film to prevent scratches.

[0003] In recent years, as liquid crystal displays have become larger and thinner, the use of (meth)acrylic films made of (meth)acrylic polymers with higher moisture permeability resistance than TAC films as polarizing plate protective films has been investigated.

[0004] Furthermore, with the advancement of diversified designs, thinner designs, and larger screen sizes in electronic devices equipped with liquid crystal display devices, such as mobile phones and smartphones, there is an increasing demand for thinner, lighter, less expensive covers for the liquid crystal display devices themselves. While glass substrates are generally used for such display covers, the use of (meth)acrylic sheets is currently being considered in response to the demand for thinner, lighter, less expensive displays.

[0005] However, the surface of a substrate containing a (meth)acrylic polymer has a problem in that it has lower adhesion to a hard coat layer than the surface of a TAC substrate or a polycarbonate substrate, and therefore, studies have been conducted to improve the adhesion between the surface containing a (meth)acrylic polymer and the hard coat layer.

[0006] For example, Patent Document 1 describes a method for improving adhesion to a hard coat layer by mixing an adhesion-imparting component such as rubber particles into a (meth)acrylic substrate. Patent Document 2 describes a method for laminating a primer layer between a (meth)acrylic substrate and a hard coat layer. Patent Document 3 describes a method for laminating a hard coat layer containing a polyol acrylate onto a transparent plastic film. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-161580 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-141074 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-185282 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the methods of Patent Documents 1 to 3 all have the problem of reduced surface hardness as a laminate because soft components are used in the substrate or primer layer. The present invention aims to solve these problems. That is, the present invention provides a laminate having a hard coat layer that imparts scratch resistance, surface hardness, smoothness, etc. to the surface of a substrate containing a (meth)acrylic polymer, the laminate having excellent adhesion between the substrate and the hard coat layer, and excellent surface hardness and surface smoothness of the hard coat layer; a polarizer protective film made of this laminate; and a polarizing plate obtained by bonding the polarizer protective film to a polarizer. The purpose is to provide a board. [Means for solving the problem]

[0009] The above-mentioned problems are solved by the present invention. The gist of the present invention is as follows [1] to [8].

[0010] [1] A laminate in which a hard coat layer containing a cured product of a curable composition is laminated directly on a surface of a substrate containing a (meth)acrylic polymer (S), the curable composition being a curable composition containing a (meth)acrylate (M) having three or more radically polymerizable double bonds and a (meth)acrylic polymer (P) having a mass average molecular weight of 1,000 or more and 70,000 or less. [2] The laminate according to [1], wherein the total mass of the (meth)acrylate (M) and the (meth)acrylic polymer (P) in the curable composition is 70 mass % or more. [3] The laminate according to [1] or [2], wherein the (meth)acrylic polymer (P) in the curable composition has a glass transition temperature (Tg) of 60°C or higher. [4] The laminate according to any one of [1] to [3], wherein the amount of the (meth)acrylic polymer (P) in the curable composition is 10 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the (meth)acrylate (M). [5] The laminate according to any one of [1] to [4], wherein the curable composition further contains a photopolymerization initiator. [6] The laminate according to [5], wherein the photopolymerization initiator is a compound having a maximum absorption wavelength in the region of 200 nm or more and 280 nm or less of the light absorption spectrum. [7] The laminate according to [6], wherein the photopolymerization initiator is benzophenone. [8] The laminate according to any one of [1] to [7], wherein the (meth)acrylate (M) has 4 to 15 radically polymerizable double bonds. [9] The laminate according to any one of [1] to [8], wherein 80% or more of the structural units of the (meth)acrylic polymer (S) contained in the substrate are structural units derived from methyl methacrylate.

[10] A polarizer protective film comprising the laminate according to any one of [1] to [9], wherein the substrate is in the form of a film and has the hard coat layer on only one side thereof.

[11] A polarizing plate obtained by laminating the surface of the polarizer protective film according to

[10] that does not have a hard coat layer to a polarizer. [Effects of the Invention]

[0011] According to the present invention, there can be provided a laminate comprising a substrate having a surface comprising a (meth)acrylic polymer and a hard coat layer directly laminated on the surface of the substrate comprising the (meth)acrylic polymer, the laminate having excellent adhesion between the substrate and the hard coat layer and excellent surface hardness and surface smoothness of the hard coat layer; a polarizer protective film comprising this laminate; and a polarizing plate obtained by bonding the polarizer protective film to a polarizer. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present invention, when the expression "(meth)acrylate" is used, it means one or both of "acrylate" and "methacrylate". When the expression "(meth)acryloyl" is used, it means one or both of "acryloyl" and "methacryloyl". When the expression "(meth)acrylic" is used, it means one or both of "acrylic" and "methacrylic".

[0013] The laminate of the present invention is a laminate in which a hard coat layer containing a cured product of a curable composition (hereinafter also simply referred to as a "hard coat layer") is laminated directly on a surface of a substrate containing a (meth)acrylic polymer (S).

[0014] [Hard coat layer] The hard coat layer in the laminate of the present invention contains a cured product of a curable composition containing a (meth)acrylate (M) having three or more radically polymerizable double bonds and a (meth)acrylic polymer (P) having a mass average molecular weight of 1,000 or more and 70,000 or less.

[0015] By including the (meth)acrylate (M) in the curable composition, the surface hardness of the layer containing the cured product of the curable composition is improved.

[0016] Examples of the (meth)acrylate (M) include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-2-hydroxyethyl isocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane hexa(meth)acrylate. Examples of the polyfunctional (meth)acrylate include tri- or higher functional polyfunctional (meth)acrylates such as acrylates; modified polyfunctional (meth)acrylate compounds in which a portion of these (meth)acrylates is substituted with an alkyl group or ε-caprolactone; polyfunctional (meth)acrylates having a nitrogen atom-containing heterocyclic structure such as polyfunctional (meth)acrylates having an isocyanurate structure; polyfunctional (meth)acrylates having a multi-branched resinous structure such as polyfunctional (meth)acrylates having a dendrimer structure and polyfunctional (meth)acrylates having a hyperbranched structure; and urethane (meth)acrylates in which a (meth)acrylate having a hydroxyl group, such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, or dipentaerythritol penta(meth)acrylate, is added to an isocyanate, triisocyanate, or isocyanurate.Among these, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate are preferred from the viewpoint of compatibility with the (meth)acrylic polymer (P), and urethane (meth)acrylate, which is an adduct of a trimer of dipentaerythritol pentaacrylate and hexamethylene diisocyanate, and urethane (meth)acrylate, which is an adduct of dipentaerythritol pentaacrylate and isophorone diisocyanate, are preferred from the viewpoint of pencil hardness. These may be used alone or in combination of two or more.

[0017] The number of radically polymerizable double bonds in the (meth)acrylate (M) is preferably 4 to 15 in terms of the hardness of the hard coat layer.

[0018] The content of the (meth)acrylate (M) in the curable composition is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, relative to 100% by mass of the total of the (meth)acrylate (M) and the (meth)acrylic polymer (P). The higher the content of the (meth)acrylate (M), the higher the hardness of the hard coat layer, and the lower the content, the higher the adhesion between the hard coat layer and the substrate.

[0019] In the present invention, the curable composition contains a (meth)acrylic polymer (P), which improves the smoothness and surface hardness of the hard coat layer. The (meth)acrylic polymer (P) has a mass average molecular weight of 1,000 to 70,000, preferably 3,000 to 50,000, and more preferably 5,000 to 30,000.

[0020] If the mass average molecular weight of the (meth)acrylic polymer (P) is less than 1000, the surface hardness of the hard coat layer may decrease. If the mass average molecular weight of the (meth)acrylic polymer (P) is more than 70000, the smoothness of the hard coat layer may decrease.

[0021] The (meth)acrylic polymer (P) is a polymer having a (meth)acrylic acid alkyl ester as a main structural unit. Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, and n-hexyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, methyl (meth)acrylate is preferred from the viewpoints of the compatibility of the (meth)acrylic polymer (P) with the (meth)acrylate (M) and the heat resistance of the hard coat layer. The (meth)acrylic polymer (P) may have a radically polymerizable double bond.

[0022] The glass transition temperature (Tg) of the (meth)acrylic polymer (P) is preferably 60° C. or higher, more preferably 80° C. or higher, and even more preferably 90° C. or higher, from the viewpoint of improving the mechanical properties of the hard coat layer. Furthermore, the glass transition temperature (Tg) is preferably 140° C. or lower, more preferably 130° C. or lower, and even more preferably 120° C. or lower, from the viewpoint of improving the processability of the laminate having the hard coat layer laminated thereon.

[0023] The glass transition temperature (Tg) can be calculated from the type and mass fraction of the monomers forming the (meth)acrylic polymer (P) using the following Fox formula. 1 / Tg=Σ(Wi / Tg i ) In this formula, Tg is the glass transition temperature (unit: K) of the (meth)acrylic polymer (P), W i is the mass fraction of the monomer unit derived from the monomer i constituting the (meth)acrylic polymer (P), Tg i denotes the glass transition temperature (unit: K) of the homopolymer of monomer i. i The value of can be the value described in POLYMERHANDBOOK Volume 1 (WILEY-INTERSCIENCE).

[0024] The amount of the (meth)acrylic polymer (P) in the curable composition is preferably 5 parts by mass or more and 200 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the (meth)acrylate (M) in terms of the hardness of the hard coat layer.

[0025] The total mass of the (meth)acrylate (M) and the (meth)acrylic polymer (P) in the curable composition is preferably 70% by mass or more, and more preferably 80% by mass or more, in order to improve the hardness of the hard coat layer and the adhesion between the hard coat layer and the substrate.

[0026] Examples of methods for producing the (meth)acrylic polymer (P) include solution polymerization, suspension polymerization, and emulsion polymerization. The mass average molecular weight of the (meth)acrylic polymer (P) can be adjusted by the polymerization initiator, chain transfer agent, solids concentration, reaction conditions, etc.

[0027] The curable composition used in the present invention may contain an organic solvent. In this case, it is preferable to use a particulate (meth)acrylic polymer (P) because it can be easily dissolved in the organic solvent. A suspension polymerization method is preferred as a method for producing the particulate (meth)acrylic polymer (P).

[0028] The (meth)acrylic polymer (P) can be produced by suspension polymerization, for example, by dissolving water, An example of such a method is to add a polymerization initiator to an aqueous suspension containing a dispersant and a monomer, heat the suspension to carry out suspension polymerization, and then filter, wash, dehydrate, and dry the aqueous suspension after polymerization.

[0029] Examples of dispersants used in the suspension polymerization method include poly(alkali metal (meth)acrylate), copolymers of alkali metal (meth)acrylate and methyl (meth)acrylate, polyvinyl alcohol having a saponification degree of 70% to 100%, and methyl cellulose, etc. These may be used alone or in combination of two or more.

[0030] The amount of the dispersant added in the suspension polymerization method is preferably 0.005 parts by mass or more and 5 parts by mass or less, and more preferably 0.01 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of all the monomers to be polymerized, from the viewpoint of improving the dispersion stability in the suspension polymerization and the washability, dewaterability, drying property, and flowability of the resulting particulate polymer.

[0031] In the suspension polymerization method, an electrolyte such as sodium carbonate, sodium sulfate, manganese sulfate, etc. may be added to the aqueous suspension for the purpose of improving dispersion stability.

[0032] Examples of polymerization initiators used in the suspension polymerization method include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxy 2-ethylhexanoate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, and t-hexyl hydroperoxide; and inorganic peroxides such as hydrogen peroxide, sodium persulfate, and ammonium persulfate. These may be used alone or in combination of two or more.

[0033] A chain transfer agent can be used when producing the (meth)acrylic polymer (P). Examples of chain transfer agents include mercaptans such as n-dodecyl mercaptan, thioglycolic acid esters such as octyl thioglycolate, cobalt metal complexes such as bis(boron difluorodiphenyl glyoximate)cobalt(II), α-methylstyrene dimer, and terpinolene. These may be used alone or in combination of two or more. Among these, cobalt metal complexes such as bis(boron difluorodiphenyl glyoximate)cobalt(II) are preferred from the viewpoints of odor reduction of the curable composition and weather resistance of the cured product of the curable composition.

[0034] The polymerization temperature when producing the (meth)acrylic polymer (P) is preferably 50° C. or higher and 130° C. or lower, more preferably 60° C. or higher and 100° C. or lower, from the viewpoints of short-term polymerization and polymerization stability.

[0035] In the present invention, the curable composition preferably further contains a photopolymerization initiator.

[0036] The photopolymerization initiator, when added to the curable composition, has a catalytic action of inducing a polymerization reaction by light irradiation, and is therefore expected to improve the curability of the curable composition. Examples of the photopolymerization initiator include a photoradical generator and a photoacid generator.

[0037] Examples of the photoradical generator include benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, and 1-hydroxycyclohexyl phenyl ketone (e.g., Omnirad (registered trademark)). oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester [e.g., commodity name: 184, manufactured by IGM]. Omnirad (registered trademark) 754, manufactured by IGM], 2-hydroxy-1-{4-[ 4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl 1-methyl-propan-1-one [e.g., trade name "Omnirad (registered trademark) 127" manufactured by IGM], 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one [e.g., trade name "Omnirad (registered trademark) 2959" manufactured by IGM], 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, etc. acetophenones such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, benzophenones such as benzophenone and its derivatives, formic acid derivatives such as methyl benzoylformate, ethyl benzoylformate, etc. These may be used alone or in combination of two or more.

[0038] Known photoacid generators can be used, including diaryliodonium salts and triarylsulfonium salts. Specific examples include anion salts of di(alkyl-substituted)phenyliodonium, such as PF6 salts, SbF5 salts, and tetrakis(perfluorophenyl)borate salts. Among these, PF6 salts of dialkylphenyliodonium (trade name "Omnicat (registered trademark) 250", manufactured by IGM) are preferred due to their excellent curability and acid generation efficiency. These may be used alone or in combination of two or more.

[0039] As the photopolymerization initiator, a photoradical generator having a maximum absorption wavelength in the wavelength range of 200 nm to 315 nm in the light absorption spectrum is preferred, since when a curable composition applied to a substrate is irradiated with active energy rays to form a layer containing a cured product, the curing in the depths of the coating film is delayed compared to the surface, thereby improving adhesion between the layer containing the cured product and the surface of the substrate containing the (meth)acrylic polymer (S). A photoradical generator having a maximum absorption wavelength in the short wavelength range of 200 nm to 280 nm (hereinafter, such a photoradical generator is particularly referred to as "photoradical generator (X)") is more preferred. Examples of the photoradical generator (X) include 1-hydroxycyclohexyl phenyl ketone, a mixture of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester. 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl) -benzyl]-phenyl}-2-methyl-propan-1-one, 1-[4-(2-hydro [2-hydroxyethoxyphenyl]-2-hydroxy-2-methyl-1-propan-1-one, benzophenones, and acetophenones.

[0040] The content of the photopolymerization initiator in the curable composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 parts by mass or more, relative to 100 parts by mass of the total of the compounds having a (meth)acryloyl group in the curable composition, from the viewpoint of improving curability. Furthermore, from the viewpoint of good stability of the curable composition, the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Furthermore, from the viewpoint of adhesion, the proportion of the photoradical generator (X) in the photopolymerization initiator is preferably 5% by mass or more, more preferably 30% by mass or more, and even more preferably 70% by mass or more. 90% by mass or more is particularly preferred.

[0041] Furthermore, the curable composition of the present invention may contain "other components" other than the (meth)acrylate (M), the (meth)acrylic polymer (P), and the photopolymerization initiator, provided that the effects of the present invention are not impaired. Examples of other components include organic solvents, ultraviolet absorbers, hindered amine light stabilizers, fillers, silane coupling agents, polymerizable diluents such as (meth)acrylates other than the (meth)acrylate (M), antistatic agents, organic pigments, organic particles, inorganic particles, leveling agents, dispersants, thixotropy-imparting agents (thickeners), antifoaming agents, and antioxidants.

[0042] The organic solvent is not particularly limited and can be appropriately selected in consideration of the types of components contained in the curable composition. Specific examples of the organic solvent include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone (MEK), acetone, methyl isobutyl ketone (MIBK), and cyclohexanone; ether solvents such as diethyl ether, isopropyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether (PGM), anisole, and phenetole; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate, and ethylene glycol diacetate; amide solvents such as dimethylformamide, diethylformamide, and N-methylpyrrolidone; cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; and halogenated solvents such as dichloromethane and chloroform.

[0043] The organic solvent may be used alone or in combination of two or more. Among these, ester-based solvents, ether-based solvents, alcohol-based solvents, and ketone-based solvents are preferred because they provide good compatibility between the (meth)acrylate (M) and the (meth)acrylic polymer (P).

[0044] The amount of organic solvent used is not particularly limited and is appropriately determined taking into consideration the coatability of the curable composition, the viscosity and surface tension of the liquid, and compatibility with the solid content. The solid content concentration of the curable composition is adjusted by the amount of organic solvent. The solid content concentration of the curable composition is preferably 20% by mass or more and 95% by mass or less, and more preferably 25% by mass or more and 80% by mass or less. Here, the "solid content" in the curable composition means the components other than the solvent in the curable composition.

[0045] The viscosity of the curable composition is preferably 30 mPa·s or less, more preferably 25 mPa·s or less, in terms of improving the coatability and smoothness of the hard coat layer.

[0046] The method for producing the curable composition is not particularly limited, and examples thereof include a method of mixing a (meth)acrylate (M), a (meth)acrylic polymer (P), and, if necessary, a polymerization initiator, an organic solvent, other components, etc. When mixing the components, it is preferable to mix them uniformly using a commonly used disperser, a stirrer, etc.

[0047] [Base material] The substrate in the laminate of the present invention contains a (meth)acrylic polymer (S) on the surface on which the hard coat layer is laminated. The substrate may be in the form of a sheet, a film, or the like.

[0048] The (meth)acrylic polymer (S) means a polymer having at least one monomer selected from (meth)acrylic acid and derivatives of (meth)acrylic acid as a main constituent unit. Examples of the derivatives of (meth)acrylic acid include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and the like. Examples of (meth)acrylic acid esters include n-butyl acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isoamyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, adamantyl (meth)acrylate, and γ-butyrolactone (meth)acrylate. These may be used alone or in combination of two or more. Among these, methyl methacrylate is preferred because it provides good transparency and optical properties to the substrate, and γ-butyrolactone (meth)acrylate is preferred because it provides good mechanical properties and heat resistance to the substrate.

[0049] The (meth)acrylic polymer (S) may also contain structural units of other monomers in addition to (meth)acrylic acid and (meth)acrylic acid derivatives, provided that the heat resistance, transparency, and surface hardness are not impaired. Examples of such other monomers include aromatic vinyl compounds, diene compounds, unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides, maleimides, and (meth)acrylamide derivatives. These may be used alone or in combination of two or more.

[0050] Among these, unsaturated carboxylic anhydrides and maleimides are preferred from the viewpoint of the heat resistance of the substrate. Examples of unsaturated carboxylic anhydrides include maleic anhydride. Examples of maleimides include maleimide and N-phenylmaleimide. Examples of (meth)acrylamide derivatives include (meth)acrylamide and N,N-dimethyl(meth)acrylamide. These may be used alone or in combination of two or more. Among these, maleimides are preferred from the viewpoint of improving the mechanical properties and heat resistance of the substrate.

[0051] In the present invention, the content of the structural units of the (meth)acrylic acid and (meth)acrylic acid derivatives in the (meth)acrylic polymer (S) is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 97% by mass or more and 100% by mass or less, relative to 100% by mass of the (meth)acrylic polymer (S), in order to improve the mechanical properties and optical properties of the substrate.

[0052] The mass average molecular weight (Mw) of the (meth)acrylic polymer (S) is preferably 70,000 or more, more preferably 100,000 or more, even more preferably 150,000 or more, and particularly preferably 200,000 or more, from the viewpoint of obtaining sufficient toughness of the substrate. The mass average molecular weight (Mw) of the (meth)acrylic polymer (S) is preferably 1,500,000 or less, more preferably 1,000,000 or less, and even more preferably 700,000 or less, from the viewpoint of reducing the melt viscosity of the substrate and improving moldability.

[0053] Furthermore, portions of the substrate other than the surface on which the hard coat layer is directly laminated, such as the interior or opposite surface of the substrate, may be made of a material different from the (meth)acrylic polymer (S). Examples of such different materials include polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, polyimide resins, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, polycycloolefin resins, triacetyl cellulose resins, and (meth)acrylic polymers different from the (meth)acrylic polymer (S). Among these, polycarbonate resins are preferred because of their excellent transparency and heat resistance, and polyvinyl alcohol resins are preferred because of their excellent chemical resistance. Therefore, the substrate is preferably one in which a layer of the (meth)acrylic polymer (S) is laminated on a layer of one of these resins.

[0054] In this specification, the term "mass average molecular weight" refers to the polystyrene-equivalent mass average molecular weight measured by gel permeation chromatography.

[0055] The glass transition temperature (Tg) of the (meth)acrylic polymer (S) is preferably 80°C or higher and 150°C or lower, more preferably 90°C or higher and 145°C or lower, and even more preferably 100°C or higher and 140°C or lower, in order to improve the flex resistance of the substrate.

[0056] The surface of the substrate of the present invention containing the (meth)acrylic polymer (S) may contain other polymers in addition to the (meth)acrylic polymer (S) as long as the effects of the present invention are not impaired. Examples of such other polymers include acetate polymers, polyester polymers, polyethersulfone polymers, polysulfone polymers, polycarbonate polymers, polyamide polymers, polyimide polymers, polyolefin polymers, cyclic olefin polymers such as norbornene polymers, polyarylate polymers, polystyrene polymers, polyvinyl alcohol polymers, and mixtures thereof. Thermosetting or ultraviolet-curable polymers such as (meth)acrylic, urethane, (meth)acrylurethane, epoxy, and silicone polymers can also be used. These may be used alone or in combination of two or more.

[0057] The (meth)acrylic polymer (S) can be produced by polymerizing a mixture of the above-mentioned monomers. An azo-based polymerization initiator is preferably used for the polymerization. When an azo-based polymerization initiator is used, the heat resistance of the substrate is improved compared to when a peroxide-based polymerization initiator is used.

[0058] Examples of the azo-based polymerization initiator include azobisisobutyronitrile, azobisisovaleronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2' -Azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile) nitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2,2'-azobis[2-methyl-N-{1,1-bis (hydroxymethyl)-2-hydroxyethyl}propionamide], 2,2'-azobis[2-methyl-N-{2-(1-hydroxybutyl)}propionamide], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl- 2-Methylpropionamide), 2,2'-Azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]disulfate dihydrate, 2,2'-Azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride 2,2'-azobis[2-{1-(2-hydroxyethyl)-2-imidazolin-2-yl}propane]dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(2-methylpropionamidine)dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methyl-propionamidine], 2,2'-azobis(2-methylpropionamidoxime), dimethyl 2,2'-azobisbutyrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2,4,4-trimethylpentane). These may be used alone or in combination of two or more.

[0059] The substrate can be produced, for example, by molding the (meth)acrylic polymer (S) by any method, such as an inflation method, a melt extrusion molding method such as a T-die method, a solution casting method, or a calendar method. Furthermore, uniaxial or biaxial stretching may be carried out as necessary.

[0060] In addition to the (meth)acrylic polymer (S), the substrate may contain additives such as a functional polymer, an ultraviolet absorber, an antioxidant, a plasticizer, a release agent, a coloring inhibitor, a colorant, an antistatic agent, a flame retardant, a retardation reducing agent, inorganic particles, and organic particles.

[0061] [Method of manufacturing laminate] The method for producing the laminate of the present invention is not particularly limited, and examples thereof include a method of applying the curable composition to a surface of a substrate containing the (meth)acrylic polymer (S) and curing the composition. Note that the laminate of the present invention may have a hard coat layer formed on a part of the surface of the substrate, for example, on one side when the substrate is in the form of a sheet or film, or may have a hard coat layer formed on the other side, for example, on the back side when the substrate is in the form of a sheet or film.

[0062] Examples of methods for applying the curable composition to a substrate include reverse coating, gravure coating, rod coating, bar coating, Mayer bar coating, die coating, and spray coating.

[0063] Examples of methods for curing the curable composition applied to a substrate include drying the composition at 40° C. or higher and 100° C. or lower, followed by irradiation with active energy rays at 40° C. or higher and 100° C. or lower. Examples of active energy rays include ultraviolet rays, electron beams, X-rays, infrared rays, and visible light. Among these, ultraviolet rays and electron beams are preferred from the viewpoints of the curability of the curable composition and prevention of deterioration of the substrate.

[0064] When ultraviolet rays are used as the active energy rays, various ultraviolet irradiation devices can be used. The light source of the ultraviolet irradiation device can be a xenon lamp, a high-pressure mercury lamp, a metal halide lamp, an LED-UV lamp, or the like.

[0065] The amount of ultraviolet light irradiation is determined appropriately depending on the reaction rate of the (meth)acryloyl group required in the curing process, but is usually 10 mJ / cm 2 More than 10000mJ / cm 2In view of the curability of the curable composition, the flexibility of the cured product, etc., 2 More than 5000mJ / cm 2 Less than 20 mJ / cm is preferred 2 More than 3000mJ / cm 2 The following is more preferred:

[0066] When electron beams are used as the active energy rays, various electron beam irradiation devices can be used. The irradiation dose of electron beams is determined appropriately depending on the reaction rate of the (meth)acryloyl group required in the curing step, but is usually 0.5 Mrad to 20 Mrad. From the viewpoints of the curability of the curable composition, the flexibility of the cured product, and prevention of damage to the substrate, it is preferably 1 Mrad to 15 Mrad.

[0067] In forming the hard coat layer, the application and curing of the curable composition may be carried out once or multiple times. Repeating the application and curing multiple times can prevent warping of the substrate.

[0068] The thickness of the hard coat layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more from the viewpoint of pencil hardness and scratch resistance of the resulting laminate, and is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less from the viewpoint of crack resistance.

[0069] The thickness of the substrate used in the laminate of the present invention is arbitrary. When the substrate is in the form of a film, the thickness is preferably 10 μm or more and 3 mm or less, more preferably 15 μm or more and 2 mm or less, and more preferably 20 μm or more and 3 mm or less. It is more preferable that the thickness is between 1 mm and 1 mm.

[0070] The thickness of the laminate of the present invention is also arbitrary. In the case of a film-like laminate, the thickness of the laminate is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, in order to ensure that each layer fully exhibits its respective function. Furthermore, in order to meet the demand for thinner and lighter products to which the laminate is applied, the thickness of the laminate is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less.

[0071] The laminate of the present invention is a laminate in which a hard coat layer containing a cured product of a curable composition containing a (meth)acrylate (M) and a (meth)acrylic polymer (P) is directly laminated on the surface of a substrate containing a (meth)acrylic polymer (S). The laminate has excellent adhesion between the substrate and the hard coat layer, as well as excellent surface hardness. Therefore, the laminate of the present invention can be suitably used for surface covers of a wide range of products, including optical display components such as touch panels and liquid crystal televisions; automobile-related components such as lamp-related products and window-related products (rear windows, side windows, skylights, etc.); and household items such as housings for various electrical devices, decorative panels, and furniture. Among these, the laminate is suitable for optical display components, and particularly suitable for use as a polarizer protective film or display protective film that is attached to a polarizer in the production of a polarizing plate for a display.

[0072] The polarizer protective film of the present invention is a laminate of the present invention in which the substrate is in the form of a film and has the hard coat layer on only one side thereof. The polarizing plate of the present invention is obtained by laminating the surface of the polarizer protective film of the present invention, which does not have a hard coat layer, to a polarizer. The polarizer protective film can be laminated to one side or both sides of the polarizer. An adhesive, a pressure-sensitive adhesive, or the like can be used for lamination. [Example]

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0074] [Mass average molecular weight (Mw) of (meth)acrylic polymer (P)] Measurements were performed using a gel permeation chromatography (GPC) "HLC-8120" (manufactured by Tosoh Corporation). The column used was a TSKgel G5000HXL*GMHXL-L (manufactured by Tosoh Corporation). A calibration curve was prepared using standard polystyrenes F288 / F80 / F40 / F10 / F4 / F1 / A5000 / A1000 / A500 (manufactured by Tosoh Corporation) and styrene. The polymer was dissolved in tetrahydrofuran to a concentration of 0.4%, and 100 μl of the solution was used for the measurement at a column oven temperature of 40° C. The mass average molecular weight (Mw) was calculated in terms of standard polystyrene.

[0075] The examples and comparative examples were evaluated by the following methods.

[0076] [viscosity] The viscosity of the curable composition was measured at 25°C using a Brookfield viscometer (BL viscometer manufactured by Toki Sangyo Co., Ltd.), and evaluated according to the following criteria. (Viscosity evaluation criteria) ○: Viscosity is low at 15 mPa·s or less, and coating properties are excellent. △: Viscosity is greater than 15 mPa·s and less than 35 mPa·s, making it difficult to apply. ×: Viscosity is greater than 35 mPa·s, requiring a long time for coating, and the coatability is poor.

[0077] [Smoothness] The appearance of the hard coat layer of the obtained laminate was visually inspected and evaluated according to the following criteria. (Smoothness evaluation criteria) ◯: No bar coater marks on the hard coat layer. △: Thin bar coater marks remain on the hard coat layer. ×: Bar coater marks are clearly visible on the entire surface of the hard coat layer.

[0078] [Adhesion] The obtained laminate was evaluated according to the cross-cut peel test of JIS K-5400 (number of cross-cuts: 100), and was evaluated according to the following criteria depending on the number of cross-cuts remaining after the peel test. (Adhesion evaluation criteria) ◎: 100 squares remained after the test (= no peeled squares). ○: The number of squares remaining after the test is between 70 and 99. △: The number of squares remaining after the test is between 10 and 69. ×: The number of squares remaining after the test is between 0 and 9.

[0079] [Pencil hardness] The surface of the cured product of the curable composition of the obtained laminate was measured for pencil hardness without scratching under a load of 500 g using a JIS pencil hardness tester in accordance with JIS K-5400, and evaluated according to the following criteria. (Evaluation standard for pencil hardness) ○: The pencil hardness is excellent, being rank F or higher. ×: The pencil hardness is inferior, less than rank F.

[0080] [(Meth)acrylate (M)] The following commercially available products were used as the (meth)acrylate (M) having three or more radically polymerizable double bonds. (B-1I) Viscoat #300 (Osaka Organic Chemical Industry Ltd.) A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (B-1II) Kayarad DPHA (Nippon Kayaku Co., Ltd.) Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (B-1III) KRM8452 (manufactured by Daicel Allnex Co., Ltd.) A mixture of the reaction product (10-functional urethane acrylate) of two equivalents of dipentaerythritol pentaacrylate with one equivalent of hexamethylene diisocyanate and dipentaerythritol hexaacrylate (B-1IV) UV1700B (Mitsubishi Chemical Corporation) A mixture of the reaction product (a 10-functional urethane acrylate) of two equivalents of dipentaerythritol pentaacrylate with one equivalent of isophorone diisocyanate and dipentaerythritol hexaacrylate (B-1V) NK Oligo U-15HA (Shin-Nakamura Chemical Co., Ltd.) A mixture of the reaction product of three equivalents of dipentaerythritol pentaacrylate with one equivalent of the trimer of hexamethylene diisocyanate (a 15-functional urethane acrylate) and dipentaerythritol hexaacrylate

[0081] For comparison, the following commercially available products were used as (meth)acrylates having one radically polymerizable double bond in the comparative examples. (B-1VI) HEA (Osaka Organic Chemical Industry Ltd.) 2-Hydroxyethyl Acrylate

[0082] [(Meth)acrylic polymer (P)] As the (meth)acrylic polymer (P) having a mass average molecular weight of 1,000 or more and 70,000 or less, polymer (B-2I) produced by the method described in the following Production Examples 1-1 to 1-3 was used.

[0083] [Production Example 1-1] Production of Dispersant (X) In a flask equipped with a stirrer, a condenser, and a thermometer, 900 parts of deionized water, 60 parts of sodium 2-sulfoethyl methacrylate, 10 parts of potassium methacrylate, and 12 parts of methyl methacrylate were placed and stirred, and the temperature was raised to 50°C while the atmosphere in the flask was replaced with nitrogen. Next, 2,2'-azobis(2-methylpropionamidine) dihydrochloride was added as a polymerization initiator to the flask. 0.08 parts of salt was added, and the temperature was further increased to 60°C. After the temperature was increased, methacrylate was added using a dropping pump. 18 parts of methyl acrylate was continuously added dropwise at a rate of 0.24 parts / min. After keeping at 0°C for 6 hours, the mixture was cooled to room temperature to obtain a clear aqueous solution of dispersant (X) with a solid content of 10%.

[0084] [Production Example 1-2] Production of chain transfer agent (Y) In a flask equipped with a stirrer, 1.00 g of cobalt(II) acetate tetrahydrate, 1.93 g of diphenylglyoxime, and 80 ml of diethyl ether (previously deoxygenated by nitrogen bubbling) were placed under a nitrogen atmosphere and stirred at room temperature for 30 minutes. Next, 10 ml of boron trifluoride diethyl ether complex was added, and the mixture was stirred for an additional 6 hours. The resulting reaction mixture was filtered, and the solid was washed with diethyl ether and dried in vacuo for 15 hours to obtain 2.12 g of chain transfer agent (Y) as a reddish-brown solid.

[0085] [Production Example 1-3] Production of polymer (B-2I) A flask equipped with a stirrer, condenser, and thermometer was charged with 145 parts of deionized water, 0.1 parts of sodium sulfate, and 0.25 parts of dispersant (X), and the mixture was stirred to form a homogeneous aqueous solution. A monomer mixture of 100 parts of methyl methacrylate, 0.005 parts of chain transfer agent (Y), and 0.4 parts of 2,2'-azobis(2-methylbutyronitrile) was then added to the flask to form an aqueous suspension. The atmosphere in the flask was then purged with nitrogen, and the mixture was heated to 80°C and reacted for approximately 1 hour. To further increase the polymerization rate, the mixture was heated to 93°C and maintained there for 1 hour. The reaction mixture was then cooled to 40°C to obtain an aqueous polymer suspension. This aqueous polymer suspension was filtered through a nylon filter cloth with a 45 μm mesh. The filtrate was washed with deionized water and dried at 40°C for 16 hours to obtain polymer (B-2I). The glass transition temperature (Tg) of polymer (B-2I) was 82°C, and the weight average molecular weight (Mw) was 7,800.

[0086] Polymers (B-2II) to (B-2V) The polymers (B-2II) to (B-2IV) used as the (meth)acrylic polymer (P) in the examples and the polymer (B-2V) used in the comparative examples were the following commercially available products.

[0087] (B-2II) AA6 (manufactured by Toagosei Co., Ltd.) Polymer with a mass average molecular weight (Mw) of 12,000 and a glass transition temperature (Tg) of 95°C (B-2III) BR87 (Mitsubishi Chemical Corporation) Polymer with a mass average molecular weight (Mw) of 25,000 and a glass transition temperature (Tg) of 106°C (B-2IV)BR83 (Mitsubishi Chemical Corporation) Polymer with a mass average molecular weight (Mw) of 40,000 and a glass transition temperature (Tg) of 105°C (B-2V) BR80 (Mitsubishi Chemical Corporation) Polymer with a mass average molecular weight (Mw) of 100,000 and a glass transition temperature (Tg) of 104°C

[0088] As the photopolymerization initiator, the following commercially available products were used in the examples and comparative examples. (C-1) Benzophenone (manufactured by Daido Chemical Industry Co., Ltd.) (C-2) Omnirad-184 (manufactured by IGM) 1-Hydroxycyclohexyl phenyl ketone

[0089] [Example 1] A flask was charged with 30 parts by mass of "B-1I" as the (meth)acrylate (M), 70 parts by mass of "B-1II", 20 parts by mass of "B-2I" as the (meth)acrylic polymer (P), and 5 parts by mass of C-1 as a photopolymerization initiator, and the resulting mixture was diluted with a 50:50 (weight ratio) mixed solvent of isopropyl alcohol (IPA) and methyl isobutyl ketone (MIBK) to a solids concentration of 35% by mass to obtain a curable composition.

[0090] The obtained curable composition was applied to the surface of the methacrylic polymer side of a laminated sheet (AW-20U, manufactured by Shine Techno Co., Ltd.; thickness = 0.2 mm) of a methacrylic polymer with 100% structural units derived from methyl methacrylate as the base material and a polycarbonate resin using a bar coater #12 so that the coating film would have a thickness of 5 μm after drying, and then heated and dried at 80°C for 2 minutes. The coating film of the curable composition was then coated with a high-pressure mercury lamp "US5-X0401" manufactured by Iwasaki Electric Co., Ltd., with an accumulated light dose of 300 mJ / cm. 2The curable composition was cured by irradiating it with ultraviolet light once so that the curable composition was cured, and a hard coat layer was laminated on the surface of the substrate containing the methacrylic polymer. The obtained laminate was evaluated for smoothness, adhesion, and pencil hardness as described above. The composition of the curable composition (unit: parts by mass) is shown in Table 1, and the evaluation results are shown in Table 2.

[0091] [Examples 2 to 14] Each curable composition was prepared in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Table 1. The composition was then coated and cured to form a hard coat layer on the surface of the substrate. The obtained laminates were evaluated for smoothness, adhesion, and pencil hardness as described above. The evaluation results are shown in Table 2.

[0092] [Examples 15 and 16] Laminates were obtained and evaluated in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Table 1 and coating was performed using a bar coater #10 so that the coating thickness after drying would be 5 μm. The evaluation results are shown in Table 2.

[0093] [Comparative Example 1] Curable compositions were obtained in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Table 3. When curing the curable composition, the curing was insufficient with the same cumulative light dose as in Example 1, so the curing conditions were changed to a cumulative light dose of 400 mJ / cm 2 The curable composition was applied and cured in the same manner as in Example 1, except that the ultraviolet light was irradiated in one pass at 1000 kJ / min, thereby laminating a hard coat layer on the surface of the substrate. The obtained laminate was evaluated for smoothness, adhesion, and pencil hardness as described above. The evaluation results are shown in Table 4.

[0094] [Comparative Examples 2 and 3] Each curable composition was prepared in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Table 3. The composition was then coated and cured to form a hard coat layer on the surface of the substrate. The obtained laminates were evaluated for smoothness, adhesion, and pencil hardness as described above. The evaluation results are shown in Table 4.

[0095] Comparative Example 4 Curable compositions were obtained in the same manner as in Example 1, except that the formulation of the curable composition was changed as shown in Table 3. When curing the curable composition, the curing was insufficient with the same cumulative light dose as in Example 1, so the curing conditions were changed to a cumulative light dose of 600 mJ / cm 2 The curable composition was applied and cured in the same manner as in Example 1, except that the ultraviolet light was irradiated in one pass at 100°C. The coating layer was laminated. The obtained laminate was evaluated for smoothness, adhesion, and pencil hardness as described above. The evaluation results are shown in Table 4.

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4]

[0100] As shown in Table 4, Comparative Example 1 is a curable composition that does not contain a (meth)acrylic polymer (P). In Comparative Examples 2 and 3, a curable composition containing a (meth)acrylic polymer having a mass-average molecular weight outside the range specified in the present application was used, resulting in high viscosity of the curable composition and poor smoothness of the hard coat layer. In Comparative Example 4, a curable composition containing a (meth)acrylate having no more than three radically polymerizable double bonds was used, resulting in poor pencil hardness. [Industrial Applicability]

[0101] The laminate of the present invention can be widely applied to displays such as liquid crystal displays, organic electroluminescence displays, electronic paper, touch panels, smartphones, etc. In particular, it can be suitably used as a polarizer protective film to be attached to a polarizer in the production of a polarizing plate for a display, or a display protective film.

Claims

1. A method for producing a laminate in which a hard coat layer containing a cured product of a curable composition is directly laminated on a surface of a substrate containing a (meth)acrylic polymer (S), the method comprising: the curable composition comprises a (meth)acrylate (M) having three or more radically polymerizable double bonds and a (meth)acrylic polymer (P) having a mass average molecular weight of 1,000 or more and 70,000 or less, the total mass of the (meth)acrylate (M) and the (meth)acrylic polymer (P) in the curable composition is 80 mass% or more, the (meth)acrylic polymer (P) is a polymer having a (meth)acrylic acid alkyl ester as a structural unit, the (meth)acrylic polymer (P) has a glass transition temperature (Tg) of 60°C or higher, the (meth)acrylic acid alkyl ester is at least one selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, and t-butyl (meth)acrylate; The method for producing a laminate, wherein the number of squares remaining after the cross-cut peel test (number of cross-cuts: 100) of the laminate is evaluated in accordance with JIS K-5400 is 70 or more.

2. 2. The method for producing a laminate according to claim 1, wherein the amount of the (meth)acrylic polymer (P) in the curable composition is 10 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the (meth)acrylate (M).

3. The method for producing a laminate according to claim 1 or 2, wherein the curable composition further contains a photopolymerization initiator.

4. 4. The method for producing a laminate according to claim 3, wherein the photopolymerization initiator is a compound having a maximum absorption wavelength in the region of 200 nm to 280 nm in the light absorption spectrum.

5. The method for producing a laminate according to claim 4, wherein the photopolymerization initiator is benzophenone.

6. The method for producing a laminate according to any one of claims 1 to 5, wherein the (meth)acrylate (M) has 4 to 15 radically polymerizable double bonds.

7. The method for producing a laminate according to any one of claims 1 to 6, wherein 80 mass% or more of the structural units of the (meth)acrylic polymer (S) contained in the base material are structural units derived from methyl methacrylate.

8. A method for producing a polarizer protective film, comprising: Using the method for producing a laminate according to any one of claims 1 to 7, The method for producing a polarizer protective film includes obtaining a laminate in which the substrate is in the form of a film and the hard coat layer is provided on only one side of the substrate.

9. A method for producing a polarizing plate, comprising laminating the surface of the polarizer protective film obtained by the method according to claim 8, the surface not having the hard coat layer, to a polarizer.

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