Curable composition for forming overcoat layer

Abstract

[Problem] To provide a curable composition capable of forming an overcoat layer having improved impact resistance. [Solution] This curable composition for forming an overcoat layer comprises (a) a polyfunctional (meth)acrylate monomer, (b) organic hollow particles which each has a shell and a hollow part surrounded by the shell and which have an average particle diameter of 10-80 nm, and (c) a polymerization initiator. The organic hollow particles (b) are contained in an amount of 15-50 parts by mass per 100 parts by mass of the polyfunctional (meth)acrylate monomer (a), and the organic hollow particles (b) are particles of a poly((meth)acrylic acid ester).

Description

Curable composition for forming overcoat layer

[0001] The present invention relates to a curable composition useful as a material for forming an overcoat layer, and more particularly to a curable composition capable of forming an overcoat layer having excellent resistance to localized impact.

[0002] Many electronic devices, including smartphones, tablet devices, and other electronic and communication devices, office equipment, entertainment equipment, medical equipment, and lifestyle equipment, are equipped with display panels (liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays) that use liquid crystal display elements or organic light-emitting diode (EL) display elements. These display panels are generally touch panel displays that have the ability to detect touch input from a stylus pen or a user's finger, and types in which a touch-recognition film (touch screen panel) is attached to the panel surface have also been developed, as have touch-integrated display panels in which touch electrodes necessary for touch recognition are incorporated into the display panel during manufacturing.

[0003] The surface of these touch panel displays is usually provided with a protective film (protective layer) called a hard coat layer to provide scratch resistance to prevent scratches on the display surface caused by fingernails or the like when operating the display with fingers, antifouling properties to prevent fingerprints from adhering, and hardness to prevent deformation or breakage when a hard object comes into contact with the display surface. For example, a polarizing plate protective film has been disclosed that has a hard coat layer containing porous acrylic resin particles on at least one side of a film substrate, with the aim of providing excellent pencil hardness and preventing discoloration due to temperature and humidity changes (Patent Document 1). Furthermore, a substrate with a hard coat film, which contains hollow silicone-based microparticle aggregates and aims for high transparency and film strength, has been disclosed, and evaluation results of the pencil hardness and scratch resistance of the hard coat film have been disclosed (Patent Document 2). Furthermore, a hard-coated film has been proposed in which a hard-coat layer containing hollow silica microparticles or the like is formed on at least one side of a polyester film in order to reduce reflectance and achieve high total light transmittance (Patent Document 3), and a substrate with a hard-coat film containing hollow silica-based particles having internal cavities has been proposed as a hard-coat film having excellent adhesion to the substrate and scratch resistance (Patent Document 4).Furthermore, an anti-glare hard-coated film has been disclosed in which the external haze value and 60° gloss value are controlled to desired values, the external haze value varies little depending on the film thickness, and the surface hardness (pencil hardness) is excellent, making it possible to stably produce the anti-glare hard-coated film, and the hard-coat film has a hard-coat layer containing organic microparticles that are not hollow particles on the surface of a transparent plastic film (Patent Document 5).

[0004] Japanese Patent Application Laid-Open No. 2009-198811 Japanese Patent Application Laid-Open No. 2009-56673 Japanese Patent Application Laid-Open No. 2013-25116 Japanese Patent No. 4540979 Japanese Patent No. 5259334

[0005] As described above, in the hard coat layer provided on the display surface, research has been conducted on resistance to scratches and abrasions on the surface, such as pencil hardness and abrasion resistance, but it is difficult to say that sufficient research has been conducted on resistance to local impacts on the display surface, such as when a sharp object such as a stylus pen or ballpoint pen hits the display.

[0006] Color filters used in the above-mentioned liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays are provided with a transparent protective film (overcoat layer) for the purposes of improving durability against solvents, heat, etc., preventing impurities from penetrating through the color filter, and flattening the color filter. The present inventors conducted extensive research focusing on the resistance to local impacts on the LCD and OLED surfaces, and as a result, they focused on imparting impact resistance not to a hard coat layer provided on the display surface, but to an internal layer constituting the display itself, such as the overcoat layer of a color filter. They discovered that blending organic hollow particles into the overcoat layer improves impact resistance when a sharp object strikes the surface, and thus completed the present invention.

[0007] That is, in a first aspect, the present invention relates to a curable composition for forming an overcoat layer, the curable composition comprising: (a) a polyfunctional (meth)acrylate monomer; (b) organic hollow particles having an average particle size of 10 nm to 80 nm, each having a shell and a hollow portion surrounded by the shell; and (c) a polymerization initiator, wherein the (b) organic hollow particles are 15 parts by mass to 50 parts by mass per 100 parts by mass of the (a) polyfunctional (meth)acrylate monomer, and the (b) organic hollow particles are poly(meth)acrylic acid ester particles. In a second aspect, the present invention relates to the curable composition for forming an overcoat layer according to the first aspect, wherein the (a) polyfunctional (meth)acrylate monomer comprises a polyfunctional monomer having 3 to 6 (meth)acryloyl groups per molecule. In a third aspect, the present invention relates to the curable composition for forming an overcoat layer according to the first or second aspect, wherein the (b) organic hollow particles are polymethyl methacrylate particles. As a fourth aspect, the present invention relates to the curable composition for forming an overcoat layer according to the first or second aspect, further comprising (d) a surface modifier. As a fifth aspect, the present invention relates to the curable composition for forming an overcoat layer according to the first or second aspect, further comprising (e) a solvent. As a sixth aspect, the present invention relates to the curable composition for forming an overcoat layer according to the first or second aspect, which does not contain inorganic particles or organic solid particles. As a seventh aspect, the present invention relates to a laminate comprising a film substrate and an overcoat layer on at least one surface of the film substrate, the overcoat layer being a cured product of the curable composition according to the first or second aspect. As an eighth aspect, the present invention relates to a display device comprising the laminate according to the seventh aspect.

[0008] According to the present invention, it is possible to provide a curable composition for forming an overcoat layer that can impart impact resistance to the overcoat layer. Furthermore, according to the present invention, it is possible to provide a laminate including an overcoat layer obtained from the curable composition, a laminate that has excellent impact resistance when a sharp object hits the surface, and a display device including the laminate.

[0009] <Curable Composition for Forming Overcoat Layer> The curable composition for forming an overcoat layer (hereinafter also simply referred to as the curable composition) of the present invention specifically relates to a curable composition for forming an overcoat layer that contains: (a) a polyfunctional (meth)acrylate monomer; (b) organic hollow particles having an average particle size of 10 nm to 80 nm and each having a shell and a hollow portion surrounded by the shell; and (c) a polymerization initiator, wherein the (b) organic hollow particles are poly(meth)acrylic acid ester particles in an amount of 15 to 50 parts by mass per 100 parts by mass of the (a) polyfunctional (meth)acrylate monomer. Hereinafter, each of the components (a) to (c) will be described.

[0010] [(a) Polyfunctional (meth)acrylate Monomer] In the curable composition of the present invention, examples of the (a) polyfunctional (meth)acrylate monomer include monomers selected from the group consisting of polyfunctional (meth)acrylate compounds described below, as well as monomers selected from the group consisting of polyfunctional urethane (meth)acrylate compounds, oxyalkylene-modified products thereof (oxyalkylene-modified polyfunctional monomers), and monomers selected from the group consisting of lactone-modified polyfunctional (meth)acrylate compounds. The (a) polyfunctional (meth)acrylate monomer can be used alone or in combination of two or more from the group consisting of the various (meth)acrylate compounds described above. In the present invention, the term "(meth)acrylate compound" includes both acrylate compounds and methacrylate compounds; for example, "(meth)acrylic acid" includes acrylic acid and methacrylic acid. Furthermore, in the present invention, the term "(meth)acryloyl group" includes both acryloyl groups and methacryloyl groups.

[0011] In the present invention, preferred examples of the (a) polyfunctional (meth)acrylate monomer include polyfunctional monomers having at least two (meth)acryloyl groups in one molecule, more preferably polyfunctional monomers having at least three, for example, 3 to 6, (meth)acryloyl groups in one molecule, or monomers selected from the group consisting of oxyalkylene-modified polyfunctional (meth)acrylate compounds having at least three (meth)acryloyl groups in one molecule.

[0012] Among the (a) polyfunctional (meth)acrylate monomers, examples of the polyfunctional (meth)acrylate compounds (provided that they do not have a urethane bond) include trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 1,3-propane Diol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tricyclo[5.2.1.0 ２，６] decanedimethanol di(meth)acrylate, dioxane glycol di(meth)acrylate, 2-hydroxy-1-acryloyloxy-3-methacryloyloxypropane, 2-hydroxy-1,3-di(meth)acryloyloxypropane, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, bis[4-(meth)acryloylthiophenyl]sulfide, bis[2-(meth)acryloylthioethyl]sulfide, 1,3-adamantanediol di(meth)acrylate, 1,3-adamantanedimethanol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate can be mentioned. Among these, preferred polyfunctional (meth)acrylate compounds include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and mixtures of two or more thereof.

[0013] The polyfunctional urethane (meth)acrylate compound is a compound having a plurality of acryloyl groups or methacryloyl groups in one molecule and having one or more urethane bonds [—NHC(═O)O—], and may further have a urea bond [—NHC(═O)NH—]. Examples of the polyfunctional urethane (meth)acrylate compound include a compound obtained by reacting a polyfunctional isocyanate with a (meth)acrylate having a hydroxy group, and a compound obtained by reacting a polyfunctional isocyanate with a (meth)acrylate having a hydroxy group, and a polyol, but the polyfunctional urethane (meth)acrylate compound that can be used in the present invention is not limited to these examples.

[0014] Examples of the polyfunctional isocyanate include tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hexamethylene diisocyanate. Examples of the (meth)acrylate having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and tripentaerythritol hepta(meth)acrylate. Examples of the polyol include diols such as ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol; polyester polyols that are reaction products of these diols with aliphatic dicarboxylic acids or dicarboxylic anhydrides such as succinic acid, maleic acid, and adipic acid; polyether polyols; and polycarbonate diols.

[0015] In the oxyalkylene-modified product (oxyalkylene-modified polyfunctional monomer), examples of the oxyalkylene-modified include oxymethylene-modified, oxyethylene-modified, and oxypropylene-modified. Examples of the oxyalkylene-modified polyfunctional monomer include oxyalkylene-modified compounds of the polyfunctional (meth)acrylate compounds or polyfunctional urethane (meth)acrylate compounds. The oxyalkylene-modified polyfunctional monomers can also be used alone or in combination of two or more. Examples of the oxyalkylene-modified polyfunctional (meth)acrylate compounds include (meth)acrylate compounds of polyols modified with oxyalkylene. Examples of the polyols include glycerin, diglycerin, triglycerin, tetraglycerin, pentaglycerin, hexaglycerin, decaglycerin, polyglycerin, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol.

[0016] In the lactone-modified polyfunctional (meth)acrylate compound, the lactone used for the lactone modification can be ε-caprolactone. Examples of the lactone-modified polyfunctional (meth)acrylate compound include ε-caprolactone-modified pentaerythritol tri(meth)acrylate, ε-caprolactone-modified pentaerythritol tetra(meth)acrylate, ε-caprolactone-modified dipentaerythritol penta(meth)acrylate, and ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0017] [(b) Organic Hollow Particles] The component (b) is organic hollow particles (hereinafter also referred to simply as "(b) organic hollow particles") that have a shell and a hollow portion surrounded by the shell and have an average particle diameter of 10 nm to 80 nm. In the curable composition of the present invention, the (b) organic hollow particles can impart impact resistance to an overcoat layer formed from the composition.

[0018] In the (b) organic hollow particles, the shell (outer shell) is composed of an organic polymer layer. Compared to inorganic particles such as silica, the (b) organic hollow particles have a flexible shell and are expected to have better impact absorption. The (b) organic hollow particles of the present invention can use poly(meth)acrylic acid ester particles containing a poly(meth)acrylic acid ester as the polymer constituting the organic polymer layer. Examples of the poly(meth)acrylic acid ester include homopolymers of alkyl (meth)acrylic acid esters having 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, mystyryl (meth)acrylate, cetyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate, as well as copolymers of two or more of these alkyl (meth)acrylic acid esters.

[0019] Furthermore, the organic polymer layer constituting the shell may contain a copolymer of the alkyl(meth)acrylate with an acrylic monomer such as (meth)acrylonitrile, (meth)acrylamide, (meth)acrylic acid, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, cumyl methacrylate, or dimethylaminomethyl (meth)acrylate; an aromatic vinyl monomer such as vinylpyridine, 2-acryloyloxyethyl phthalate, itaconic acid, fumaric acid, styrene, α-methylstyrene, p-methylstyrene, or p-chlorostyrene; a vinyl ester such as vinyl acetate or vinyl propionate; a halogen-containing monomer such as vinyl chloride or vinylidene chloride; or ethylene, propylene, or the like. Furthermore, the organic polymer layer may be a homopolymer / copolymer of the alkyl(meth)acrylic acid ester crosslinked with a crosslinkable monomer, and examples of the crosslinkable monomer include di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, and ethylene oxide-modified trimethylolpropane tri(meth)acrylate. polyfunctional (meth)acrylic acid esters such as tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and further pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate; polyfunctional acrylamide derivatives such as N,N'-methylenebis(meth)acrylamide, N,N'-ethylenebis(meth)acrylamide; polyfunctional allyl derivatives such as butadiene, diallylamine, diallyl maleate, diallyl fumarate, diallyl succinate, tetraallyloxyethane, and triallyl isocyanurate; and aromatic allyl derivatives such as divinylbenzene, divinylnaphthalene, and diallyl phthalate.

[0020] Among these, polymethyl methacrylate particles can be preferably used as the (b) organic hollow particles. Hollow polymethyl methacrylate particles have the transparency and flexibility unique to polymethyl methacrylate, and, combined with their hollowness, they are suitable as particles with excellent impact resistance. Commercially available polymethyl methacrylate particles (hollow particles) can be used, and examples include Techpolymer (registered trademark) NH, Techpolymer TP-NH, and Techpolymer XX series (Sekisui Plastics Co., Ltd.).

[0021] The shape of the (b) organic hollow particles themselves can be, for example, bead-like and approximately spherical, such as approximately spherical particles or true spherical particles with an aspect ratio of 1.5 or less.

[0022] The average particle size of the (b) organic hollow particles used in the present invention is in the range of 10 nm to 80 nm, and for example, particles in the range of 30 nm to 80 nm can be used. The average particle size (nm) used here refers to the average particle size measured by dynamic light scattering (DLS) (DLS average particle size: Z-average particle size). By setting the average particle size of the (b) organic hollow particles within the above-mentioned range, a cured film with excellent impact resistance can be obtained. The (b) organic hollow particles are not particularly limited in terms of particle size distribution, but are preferably monodisperse fine particles with a uniform particle size. Furthermore, the (b) organic hollow particles are preferably selected so that their average particle size satisfies the range of (b) organic hollow particle average particle size b / film thickness a = 0.01 to 1.0, relative to the film thickness of the cured film obtained from the curable composition of the present invention, as described below.

[0023] In the present invention, the (b) organic hollow particles are used in an amount of 10 parts by mass to 65 parts by mass, for example, 15 parts by mass to 50 parts by mass, and preferably 15 parts by mass to 45 parts by mass, relative to 100 parts by mass of the (a) polyfunctional (meth)acrylate monomer. If the content of the (b) organic hollow particles is too low, the impact resistance of the overcoat layer obtained from the curable composition may decrease. On the other hand, if the content of the (b) organic hollow particles is excessive, the surface flatness of the overcoat layer obtained from the curable composition may not be achieved.

[0024] Furthermore, the curable composition of the present invention may contain organic hollow particles other than the (b) organic hollow particles [poly(meth)acrylic acid ester hollow particles], for example, organic hollow particles having a shell (outer shell) organic polymer layer made of polystyrene, polyimide, polyvinyl chloride, polyacetal, polyethylene terephthalate, or the like, within the range that does not impair the effects of the present invention.

[0025] The curable composition of the present invention may contain inorganic particles (inorganic hollow particles, inorganic solid particles) and organic solid particles to the extent that the effects of the present invention are not impaired, but is preferably free of these inorganic particles and organic solid particles. Even in an embodiment that does not contain these inorganic particles or organic solid particles, it is acceptable for the composition to contain these particles at the impurity level.

[0026] [(c) Polymerization Initiator] Examples of the (c) polymerization initiator used in the curable composition of the present invention include polymerization initiators that generate radicals when irradiated with active energy rays such as electron beams, ultraviolet rays, and X-rays, particularly ultraviolet rays. Examples of the (c) polymerization initiator include benzoins, alkylphenones, thioxanthones, azo compounds, azides, diazo compounds, o-quinonediazides, acylphosphine oxides, oxime esters, organic peroxides, benzophenones, biscoumarins, bisimidazoles, titanocenes, thiols, halogenated hydrocarbons, trichloromethyltriazines, and onium salts such as iodonium salts and sulfonium salts. These may be used alone or in combination of two or more. In the present invention, from the viewpoints of transparency, surface curability, and thin-film curability, it is preferable to use alkylphenones as the (c) polymerization initiator. The use of alkylphenones makes it possible to obtain a cured film with improved impact resistance.

[0027] Examples of the alkylphenones include α-hydroxyalkylphenones such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methylpropan-1-one, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; α-aminoalkylphenones such as 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one; 2,2-dimethoxy-1,2-diphenylethan-1-one; and methyl phenylglyoxylate.

[0028] In the present invention, the polymerization initiator (c) is used in an amount of 1 to 20 parts by mass, preferably 2 to 10 parts by mass, per 100 parts by mass of the polyfunctional (meth)acrylate monomer (a).

[0029] [(d) Surface Modifier] The curable composition of the present invention may contain (d) a surface modifier. As the (d) surface modifier used in the present invention, a fluorine-based surface modifier may be used. Specific examples of the fluorine-based surface modifier include perfluoropolyethers containing a poly(oxyperfluoroalkylene) group.

[0030] The number of carbon atoms in the alkylene group in the poly(oxyperfluoroalkylene) group is not particularly limited, but preferably is 1 to 4. That is, the poly(oxyperfluoroalkylene) group refers to a group having a structure in which divalent fluorocarbon groups having 1 to 4 carbon atoms and oxygen atoms are alternately linked, and the oxyperfluoroalkylene group refers to a group having a structure in which divalent fluorocarbon groups having 1 to 4 carbon atoms and oxygen atoms are linked. Specifically, -[OCF ２ ]-(oxyperfluoromethylene group), -[OCF ２ CF ２ ]-(oxyperfluoroethylene group), -[OCF ２ CF ２ CF ２]-(oxyperfluoropropane-1,3-diyl group), -[OCF ２ C (CF ３ )F]-(oxyperfluoropropane-1,2-diyl group). The oxyperfluoroalkylene groups may be used singly or in combination of two or more, in which case the bonding of the multiple types of oxyperfluoroalkylene groups may be either block bonding or random bonding.

[0031] Among these, the poly(oxyperfluoroalkylene) group is -[OCF ２ ]-(oxyperfluoromethylene group) and -[OCF ２ CF ２ It is preferable to use a group having both the repeating unit: -[OCF ]-(oxyperfluoroethylene group). ２ ]-と-[OCF ２ CF ２ ]- and in a molar ratio of [repeating unit: -[OCF ２ ]-]: [Repeating unit: −[OCF ２ CF ２

[0033] Preferably, it is a group containing the repeating units in a ratio of 1:1 to 2:1, more preferably a group containing the repeating units in a ratio of approximately 1:1. The bonding of these repeating units may be either block bonding or random bonding. The total number of repeating units of the oxyperfluoroalkylene group is preferably in the range of 5 to 30, more preferably in the range of 7 to 21. The weight average molecular weight (Mw) of the poly(oxyperfluoroalkylene) group measured in polystyrene equivalent by gel permeation chromatography is 1,000 to 5,000, preferably 1,500 to 3,000.

[0032] In the present invention, as component (d), a perfluoropolyether containing a poly(oxyperfluoroalkylene) group and having an active energy ray polymerizable group at the end of its molecular chain via a urethane bond (hereinafter simply referred to as "perfluoropolyether having a polymerizable group at the end of the molecular chain") can be used. The end of the molecular chain of the perfluoropolyether may be either all or some of the ends of the molecular chain. When the molecular chain of the perfluoropolyether is linear, all or some of the ends of the molecular chain are both ends and one end of the linear molecular chain, respectively. Note that perfluoropolyethers having a polymerizable group at the end of the molecular chain can exclude perfluoropolyethers having a poly(oxyalkylene) group between the poly(oxyperfluoroalkylene) group and the urethane bond. In addition, the perfluoropolyether having a polymerizable group at the end of the molecular chain has excellent compatibility with component (a), thereby preventing the overcoat layer from becoming cloudy and enabling the formation of an overcoat layer with a transparent appearance.

[0033] Examples of the active energy ray polymerizable group include a (meth)acryloyl group and a vinyl group.

[0034] The perfluoropolyether having a polymerizable group at the end of the molecular chain is not limited to one having one active energy ray-polymerizable group at the end of the molecular chain, but may be one having two or more active energy ray-polymerizable groups at the end of the molecular chain. For example, examples of terminal structures containing an active energy ray-polymerizable group include structures of the following formulae [A1] to [A5], and structures in which the acryloyl group in these structures is substituted with a methacryloyl group.

[0035]

[0036] An example of such perfluoropolyether having a polymerizable group at the end of the molecular chain is a compound represented by the following formula [2]: (In formula [2], A represents one of the structures represented by formulas [A1] to [A5] and structures in which the acryloyl group in these structures is substituted with a methacryloyl group, and PFPE represents the poly(oxyperfluoroalkylene) group (wherein L １ The side directly bonded to is an oxy end, and the side bonded to the oxygen atom is a perfluoroalkylene end. １ represents an alkylene group having 2 or 3 carbon atoms substituted with 1 to 3 fluorine atoms, each m independently represents an integer of 1 to 5, L ２ represents an (m+1)-valent residue obtained by removing OH from an (m+1)-valent alcohol.

[0037] The alkylene group having 2 or 3 carbon atoms and substituted with 1 to 3 fluorine atoms includes —CH ２ CHF-, -CH ２ CF ２ -, -CHFCF ２ -, -CH ２ CH ２ CHF-, -CH ２ CH ２ CF ２ -, -CH ２ CHFCF ２ -, etc., -CH ２ CF ２ - is preferred.

[0038] Partial structure (A-NHC(=O)O) in the compound represented by the above formula [2] ｍ L ２ Examples of - include structures represented by the following formulas [B1] to [B12]. (In formulas [B1] to [B12], A represents one of the structures represented by formulas [A1] to [A5] and structures in which an acryloyl group in these structures is substituted with a methacryloyl group.) Among the structures represented by formulas [B1] to [B12], formulas [B1] and [B2] correspond to the case where m = 1, formulas [B3] to [B6] correspond to the case where m = 2, formulas [B7] to [B9] correspond to the case where m = 3, and formulas [B10] to [B12] correspond to the case where m = 5. Of these, the structure represented by formula [B3] is preferred, and the combination of formula [B3] and formula [A3] is particularly preferred.

[0039] Among the perfluoropolyethers having a polymerizable group at the end of the molecular chain, particularly preferred are compounds having a partial structure represented by the following formula [1]: The partial structure represented by formula [1] corresponds to the portion of the compound represented by formula [2] excluding A-NHC(=O). n in formula [1] represents the repeating unit -[OCF ２ CF ２ ]- and the number of repeating units -[OCF ２ ]-, and is preferably an integer in the range of 5 to 30, more preferably an integer in the range of 7 to 21. ２ CF ２ ]- and the number of repeating units -[OCF ２ The ratio of the number of repeating units to the number of repeating units is preferably in the range of 2:1 to 1:2, and more preferably in the range of about 1:1. The bonding of these repeating units may be either block bonding or random bonding.

[0040] In the present invention, when a perfluoropolyether having a polymerizable group at the molecular chain terminal is used, it can be used in a proportion of, for example, 0.05 to 10 parts by mass, or 0.1 to 5 parts by mass, per 100 parts by mass of the aforementioned (a) polyfunctional (meth)acrylate monomer. By using 10 parts by mass or less of the perfluoropolyether having a polymerizable group at the molecular chain terminal, it is possible to obtain an overcoat layer that is sufficiently compatible with the (a) polyfunctional (meth)acrylate monomer, and that is less opaque.

[0041] The perfluoropolyether having a polymerizable group at the end of the molecular chain is, for example, a perfluoropolyether represented by the following formula [3]: (In formula [3], PFPE, L １ , L ２ and m have the same meaning as in the formula [2] above.) with an isocyanate compound having a polymerizable group, that is, a compound in which an isocyanato group is bonded to a bond in the structure represented by the formulas [A1] to [A5] above or in a structure in which the acryloyl group in these structures is substituted with a methacryloyl group (for example, 2-(meth)acryloyloxyethyl isocyanate, 1,1-bis((meth)acryloyloxymethyl)ethyl isocyanate, etc.), to form a urethane bond.

[0042] In addition, the perfluoropolyether containing poly (oxyperfluoroalkylene) group, which is a specific example of the (d) component: surface modifier of the curable composition of the present invention, is a perfluoropolyether containing poly (oxyperfluoroalkylene) group, and has an active energy ray polymerizable group at one end (one end) of its molecular chain via a urethane bond, and has a hydroxyl group at the other end (other end) of its molecular chain, or a perfluoropolyether containing poly (oxyperfluoroalkylene) group as represented by the above formula [3], and has a hydroxyl group at both ends of its molecular chain [compound that does not have an active energy ray polymerizable group].It is possible to add the condition that there is no poly (oxyalkylene) group between the poly (oxyperfluoroalkylene) group and the urethane bond, and between the poly (oxyperfluoroalkylene) group and the hydroxyl group.

[0043] [(e) Solvent] The curable composition of the present invention may further contain (e) a solvent, i.e., it can be used in the form of a varnish (film-forming material). The solvent may be appropriately selected in consideration of the ability to dissolve and disperse the components (a) to (d) and, if desired, other additives described below, as well as the workability during application for forming the cured film (overcoat layer) described below and the drying properties before and after curing. For example, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, tetralin, etc.; aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, mineral spirits, cyclohexane, etc.; halides such as methyl chloride, methyl bromide, methyl iodide, dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, o-dichlorobenzene, etc.; esters or ester ethers such as ethyl acetate, propyl acetate, butyl acetate, methoxybutyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate (PGMEA), etc.; diethyl ether, tetrahydrofuran (THF), 1,4-dioxane, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether (PGMEA), etc. ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), di-n-butyl ketone, cyclopentanone, cyclohexanone; alcohols such as methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol, isobutyl alcohol, tert-butyl alcohol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP); and sulfoxides such as dimethyl sulfoxide (DMSO), as well as mixtures of two or more of these solvents.

[0044] Furthermore, a solvent having a high boiling point can be used for the purpose of controlling the dispersibility of the (b) organic hollow particles during drying after coating. Examples of such solvents include cyclohexyl acetate, propylene glycol diacetate, 1,3-butylene glycol diacetate, 1,4-butanediol diacetate, 1,6-hexanediol diacetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, 3-methoxybutyl acetate, ethylene glycol, diethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, 3-methoxybutanol, dipropylene glycol dimethyl ether, and dipropylene glycol methyl-n-propyl ether.

[0045] The amount of (e) solvent used is not particularly limited, but is used at a concentration such that the solid content concentration in the curable composition of the present invention becomes 1% by mass to 70% by mass, preferably 5% by mass to 50% by mass. Here, the solid content concentration (also referred to as non-volatile content concentration) represents the content of the solid content (all components excluding the solvent component) relative to the total mass (total mass) of the components (a) to (d) (and other additives, if desired) in the curable composition of the present invention.

[0046] [Other Additives] Furthermore, to the curable composition of the present invention, one or more of generally added additives, such as a polymerization accelerator, a polymerization inhibitor, a photosensitizer, a leveling agent, a surfactant, an adhesion imparting agent, a plasticizer, an ultraviolet absorber, a light stabilizer, an antioxidant, a storage stabilizer, an antistatic agent, an inorganic filler, a pigment, and a dye, may be appropriately blended, as needed, either singly or in combination, as long as the effects of the present invention are not impaired.

[0047] <Overcoat Layer (Cured Film)> The curable composition of the present invention can be applied (coated) onto a substrate to form a coating film, and then cured by irradiating the coating film with active energy rays such as ultraviolet rays, thereby forming an overcoat layer (cured film) on the substrate. That is, the overcoat layer in the laminate described below can be composed of a cured product (cured film) of the curable composition of the present invention. Examples of the substrate include various resins (polyesters such as polycarbonate, polymethacrylate, polystyrene, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), polyurethane, thermoplastic polyurethane (TPU), polyolefin, polyamide, polyimide, epoxy resin, melamine resin, triacetyl cellulose (TAC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polyvinyl chloride (PVC), polypropylene (PP), norbornene-based resin, etc.), metal, wood, paper, glass, slate, etc. The shape of these substrates may be a plate, a film, or a three-dimensional molded object. Furthermore, on the surface of the substrate, for example, a primer layer, an ultraviolet absorbing layer, an infrared absorbing layer, a near-infrared absorbing layer, an electromagnetic wave absorbing layer, a color correction layer, a refractive index adjusting layer, a weather-resistant layer, an antireflection layer, an antistatic layer, a discoloration preventing layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, an electrode layer, a color filter layer, or the like may be formed as a layer below the overcoat layer, and a plurality of layers below the overcoat layer may be laminated. The layer to be formed on the surface of the substrate is not particularly limited as long as it does not impair the effects of the present invention.

[0048] The method for applying the composition to the substrate can be appropriately selected from cast coating, spin coating, blade coating, dip coating, roll coating, spray coating, bar coating, die coating, inkjet printing, and printing methods (such as relief printing, intaglio printing, lithographic printing, and screen printing). Among these, roll-to-roll methods can be used. From the viewpoint of thin-film coating properties, relief printing, particularly gravure coating, can be used. It is preferable to filter the curable composition of the present invention before application using a filter having a pore size of approximately 0.2 μm. If necessary, a solvent may be added to the curable composition of the present invention during application. Examples of the solvent include the various solvents listed in the above section [(e) Solvent].

[0049] After applying the curable composition of the present invention to a substrate to form a coating film, the coating film is pre-dried as needed using a heating means such as a hot plate or oven to remove the solvent (solvent removal step). The heat drying conditions are preferably, for example, 40°C to 120°C for about 30 seconds to 10 minutes. After drying, the coating film is cured by irradiating it with active energy rays such as ultraviolet light. Examples of active energy rays include ultraviolet light, electron beams, and X-rays, with ultraviolet light being particularly preferred. Examples of light sources that can be used for ultraviolet irradiation include sunlight, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and UV-LEDs. The polymerization may then be completed by post-baking, specifically by heating using a heating means such as a hot plate or oven.

[0050] The thickness of the cured film formed after drying and curing can usually be about 0.01 μm to 100 μm, alternatively 0.01 μm to 50 μm, alternatively 0.05 μm to 40 μm, or alternatively 0.1 μm to 35 μm.

[0051] <Laminate> Using the curable composition of the present invention, a laminate having an overcoat layer on at least one surface (surface) of a film substrate can be produced. This laminate is also within the scope of the present invention. The laminate is intended for use in various display elements such as touch panels and liquid crystal displays.

[0052] The overcoat layer in the laminate of the present invention can be formed by a method including the steps of applying the curable composition of the present invention onto a film substrate to form a coating film, optionally removing the solvent by heating, and irradiating the coating film with active energy rays such as ultraviolet rays to cure the coating film.

[0053] Examples of the film substrate include resin films among the substrates listed above in the section <Overcoat Layer (Cured Film)>. Examples include films of polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyurethane, thermoplastic polyurethane (TPU), polycarbonate, polymethacrylate, polystyrene, polyolefin, polyamide, polyimide, triacetyl cellulose (TAC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polyvinyl chloride (PVC), and polypropylene (PP).

[0054] The film substrate may have, on its surface, for example, a primer layer, an ultraviolet absorbing layer, an infrared absorbing layer, a near-infrared absorbing layer, an electromagnetic wave absorbing layer, a color correction layer, a refractive index adjusting layer, a weather-resistant layer, an antireflection layer, an antistatic layer, a discoloration preventing layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, an electrode, a color filter layer, or the like, formed as a layer below the overcoat layer, or a plurality of layers below the overcoat layer may be laminated. The layer formed on the surface of the film substrate is not particularly limited as long as it does not impair the effects of the present invention.

[0055] The method for applying the curable composition of the present invention to the film substrate (coating film forming step) and the method for irradiating the coating film with active energy rays (curing step) can be the same as those described above in <Overcoat layer (cured film)>. Since the curable composition of the present invention contains a solvent (in the form of a varnish), the coating film may be dried to remove the solvent after the coating film forming step, if necessary. In this case, the method for drying the coating film (solvent removal step) described above in <Overcoat layer (cured film)> can be used.

[0056] The thickness of the overcoat layer thus obtained can be set to be about 1 to 1000 times the average particle size of the (b) organic hollow particles. The thickness of the overcoat layer can be, for example, 0.01 μm to 100 μm, 0.01 μm to 50 μm, 0.05 μm to 40 μm, or 0.1 μm to 35 μm.

[0057] 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. In the examples, the apparatus and conditions used for sample preparation and physical property analysis are as follows:

[0058] (1) Coating by bar coater Apparatus: Automatic Film Applicator AB3125 manufactured by TQC Sheen Co., Ltd. Bar: A-Bar OSP-100 manufactured by OSG System Products Co., Ltd., maximum wet film thickness 100 μm (equivalent to wire bar #37) Coating speed: 4 m / min (2) Oven Apparatus: Two-layer clean oven (top and bottom type) PO-250-45-D manufactured by Sanki Keiso Co., Ltd. (3) UV curing Apparatus: CV-110QC-G manufactured by Heraeus Co., Ltd. Lamp: High-pressure mercury lamp H-bulb manufactured by Heraeus Co., Ltd. (4) Gel permeation chromatography (GPC) Apparatus: HLC-8420GPC manufactured by Tosoh Corporation Column: Tosoh Corporation TSKgel (registered trademark) G2000HXL, G3000HXL Column temperature: 40°C Eluent: tetrahydrofuran Detector: UV (5) Laser microscope (pen drop test, dent depth measurement, crack confirmation) Equipment: Digital microscope VK-X250 manufactured by Keyence Corporation

[0059] The abbreviations have the following meanings: Ac1: polyfunctional acrylate [Aronix (registered trademark) M-933, manufactured by Toagosei Co., Ltd.] PFPE1: perfluoropolyether having the following structure, which has two hydroxy groups at each end of a molecular chain containing a poly(oxyperfluoroalkylene) group, without a poly(oxyalkylene) group in between [Fomblin (registered trademark) T4, manufactured by Solvay Specialty Polymers] １９ F-NMR and １ Number average molecular weight calculated from H-NMR analysis results: 2200 (In the above formula, m represents the repeating unit -(CF ２ CF ２ O)-, and n is the number of repeating units -(CF ２The number of repeating units (m+n)- satisfies 5≦(m+n)≦40, and m and n each independently represent an integer of 0 or more. When both repeating units are present, these repeating units are bonded by block bonds, random bonds, or block bonds and random bonds. BEI: 1,1-bis(acryloyloxymethyl)ethyl isocyanate [Karenz (registered trademark) BEI, manufactured by Resonac Corporation] DOTDD: dioctyltin dineodecanoate [Neostan (registered trademark) U-830, manufactured by Nitto Kasei Co., Ltd.] O2959: 2-hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methylpropan-1-one [Omnirad (registered trademark) 2959, manufactured by IGM Resins] PGME: propylene glycol monomethyl ether PGMEA: propylene glycol monomethyl ether acetate HP1: organic hollow particle (polymethyl methacrylate hollow particle) dispersion [manufactured by Sekisui Plastics Co., Ltd., trade name Techpolymer (registered trademark) XX-6066Z, average particle size 65 nm, solid content concentration 10 mass%] HP2: organic hollow particle (polymethyl methacrylate hollow particle) dispersion [manufactured by Sekisui Plastics Co., Ltd., trade name Techpolymer (registered trademark) XX-7161Z, average particle size 80 nm, solid content concentration 10 mass%] SP1: organic solid particle (polymethyl methacrylate solid particle) [manufactured by Sekisui Plastics Co., Ltd., trade name Techpolymer (registered trademark) SSX-103, average particle size 3 μm, used after being made into a dispersion with a solid content concentration of 40 mass%]

[0060] [Production Example 1] Production of perfluoropolyether (S1) having four acryloyl groups via urethane bonds at each end of a molecular chain containing a poly(oxyperfluoroalkylene) group. 1.19 g (0.5 mmol) of PFPE1, 0.52 g (2.2 mmol) of BEI, 0.017 g of DOTDD (0.01 times the total mass of PFPE1 and BEI), and 1.67 g of PGMEA were charged into a screw tube. This mixture was stirred at room temperature (approximately 23 ° C.) for 24 hours using a stirrer tip to obtain a 50 wt% PGMEA solution of the target compound S1. The weight average molecular weight (Mw) of the obtained S1 measured in polystyrene equivalent by GPC was 2,300, and the dispersity (Mw (weight average molecular weight) / Mn (number average molecular weight)) was 1.0.

[0061] [Examples 1 to 2, Comparative Examples 1 and 2] The following components listed in Table 1 were mixed to prepare curable compositions having the solid content concentrations listed in Table 1. Here, the solid content refers to components other than the solvent (including the solvent listed in Table 1, the solvent of the surface modifier (solution), and the dispersion medium of each particle). In Table 1, [parts] represents [parts by mass] and [%] represents [% by mass]. Polyfunctional (meth)acrylate monomer: 100 parts by mass of the polyfunctional (meth)acrylate monomer listed in Table 1. Surface modifier: 0.8 parts by mass of a 50% by mass PGMEA solution of S1 (solid content: 0.4 parts by mass). Particles: The particles (as solid content) listed in Table 1 in the amount listed in Table 1. Polymerization initiator: 5.0 parts by mass of O2959. Solvent: The solvent listed in Table 1 in an amount that results in the solid content concentration listed in Table 1.

[0062]

[0063] [Creation of Cured Film] The curable compositions of Examples 1 and 2 and Comparative Examples 1 and 2 were applied to an A4-sized double-sided easy-adhesion treated PET film [Lumirror (registered trademark) U403, manufactured by Toray Industries, Inc., thickness 100 μm] using a bar coater to obtain a coating film. This coating film was dried in an oven at 65°C for 3 minutes to remove the solvent. The obtained film was exposed to light at an exposure dose of 700 mJ / cm under a nitrogen atmosphere. ２ A laminate having an overcoat layer (cured film) with a layer thickness (film thickness) of approximately 30 μm was produced by irradiating and exposing the curable composition with UV light of 1000 nm. In the following description, the example numbers of the curable compositions will also be used as the example numbers of the overcoat layer and the laminate, and the example numbers for the evaluation of the drop impact test.

[0064] [Drop Impact Test (Pen Drop Test)] A pen drop test was performed to evaluate the impact resistance of the overcoat layer. Each laminate was placed on a glass substrate with the overcoat layer facing up, and a sharp, narrow-tipped pen (manufactured by DONG-A Co., Ltd., tip diameter: 0.3 mmφ, total length: 125 mm, weight: 10 g) was dropped from a height of 190 mm from the laminate (distance from the laminate to the tip of the pen) so that the tip of the pen struck the overcoat layer perpendicularly. Immediately after the test, the point of impact was visually observed to confirm the occurrence of dents or cracks, and the depth (maximum value) of the dent caused by the impact on the surface of the overcoat layer was measured using a laser microscope. In this test, if the depth of the pen drop dent (dent) in the laminate having the overcoat layer was 50 μm or less, the overcoat layer could be evaluated as having high impact resistance. The results obtained and the film thickness of the overcoat layer are shown in Table 2.

[0065]

[0066] As shown in Table 2, in Examples 1 and 2, which contained organic hollow particles, only shallow dents were observed after the pen drop test, and the dents (maximum depth) were also small. Furthermore, no cracks were observed around the dents. On the other hand, in Comparative Example 1, which did not contain any particles, not only dents but also cracks spreading from the dents were observed after the pen drop test. Furthermore, the dent depth in Comparative Example 1 was greater than in Examples 1 and 2, confirming that this resulted in a deterioration in impact resistance. Furthermore, in Comparative Example 2, which contained organic solid particles, dents and cracks spreading from the dents were observed after the pen drop test. The dent depth was also greater than in Examples 1 and 2, confirming that the addition of organic solid particles was insufficient to improve impact resistance.

Claims

1. A curable composition for forming an overcoat layer, comprising: (a) a polyfunctional (meth)acrylate monomer; (b) organic hollow particles having an average particle size of 10 nm to 80 nm and each having a shell and a hollow portion surrounded by the shell; and (c) a polymerization initiator; wherein the curable composition for forming an overcoat layer contains 15 to 50 parts by mass of the (b) organic hollow particles per 100 parts by mass of the (a) polyfunctional (meth)acrylate monomer; and the (b) organic hollow particles are poly(meth)acrylic acid ester particles.

2. The curable composition for forming an overcoat layer according to claim 1, wherein the (a) polyfunctional (meth)acrylate monomer comprises a polyfunctional monomer having 3 to 6 (meth)acryloyl groups in one molecule.

3. The curable composition for forming an overcoat layer according to claim 1 or 2, wherein the (b) organic hollow particles are polymethyl methacrylate particles.

4. The curable composition for forming an overcoat layer according to claim 1 or claim 2, further comprising (d) a surface modifier.

5. The curable composition for forming an overcoat layer according to claim 1 or claim 2, further comprising (e) a solvent.

6. The curable composition for forming an overcoat layer according to claim 1 or 2, which does not contain inorganic particles or organic solid particles.

7. A laminate comprising a film substrate and an overcoat layer on at least one surface of the film substrate, wherein the overcoat layer is a cured product of the curable composition according to claim 1 or 2.

8. A display device comprising the laminate according to claim 7.

Images