Active energy ray-curable composition, cured coating film, and optical sheet

Abstract

The purpose of the present invention is to provide: an active energy ray-curable composition capable of forming an optical sheet having high transparency while having a high refractive index and high hardness; a cured coating film obtained by curing the composition; and an optical sheet having the cured coating film.　The present invention relates to an active energy ray-curable composition containing inorganic fine particles (A), a dispersant (B), a compound (C) having two or more (meth)acrylate groups and having an average active hydrogen concentration of 50-300 mgKOH / g, and a compound (D) having one or more (meth)acrylate groups other than the compound (C). The present invention also relates to a cured coating film of the composition and an optical sheet having the cured coating film.

Description

Active energy ray curable composition, cured coating film and optical sheet

[0001] The present invention relates to an active energy ray-curable composition, a cured coating film of the composition, and an optical sheet having the cured coating film.

[0002] Anti-reflective (LR) films are used on the surfaces of flat panel displays (FPDs) such as liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays. Anti-reflective (LR) films typically have a multilayer structure (substrate / high refractive index layer / low refractive index layer) in which two layers with a large difference in refractive index are formed on a film substrate to prevent reflection. Each of these layers is required to have high hard coating properties to prevent scratches during the manufacturing process of the anti-reflective (LR) film, and each layer is also required to have high transparency.

[0003] Curable compositions for forming coating layers to impart hard coating properties to high-refractive index layers of anti-reflective (LR) films typically combine refractive index-adjustable inorganic fine particles with a curable polyfunctional compound. As a conventional technique for such curable compositions, for example, Patent Document 1 below uses a specific organic-inorganic composite, a polyfunctional (meth)acrylate monomer having at least two (meth)acryloyl groups, and an adhesion promoter that is a compound having an ethylenic double bond and a polar group. Patent Document 2 below also uses a specific compound having six or more acryloyl groups and a compound having a carboxyl group in a metal oxide composition. Patent Document 3 below also uses inorganic oxide fine particles, a specific urethane (meth)acrylate, and a polyfunctional (meth)acrylate.

[0004] JP 2016-3319 A JP 2016-216563 A JP 2023-171010 A

[0005] The inventors have examined the above-mentioned conventional technology and found that the compatibility between the inorganic fine particles and the polyfunctional compound in the curable composition is insufficient, making it difficult to maintain high transparency in the high refractive index layer of the optical sheet.

[0006] Therefore, the problem to be solved by the present invention is to provide an active energy ray-curable composition capable of forming an optical sheet having a high refractive index, high hardness, and high transparency, a cured coating film obtained by curing the composition, and an optical sheet having the cured coating film.

[0007] As a result of intensive research to solve the above problems, the inventors discovered that by controlling the compatibility between highly refractive particles in a curable composition and a matrix that ensures scratch resistance, it is possible to achieve a high refractive index and high hardness without impairing transparency, and thus completed the present invention.

[0008] That is, the present invention relates to the following inventions. [1] An active energy ray-curable composition containing inorganic fine particles (A), a dispersant (B), a compound (C) having two or more (meth)acrylate groups and an average active hydrogen concentration of 50 to 300 mgKOH / g, and a compound (D) other than the compound (C) having one or more (meth)acrylate groups. [2] The active energy ray-curable composition according to [1], wherein the inorganic fine particles (A) are at least one selected from the group consisting of zirconia, titania, niobium oxide, and barium titanate. [3] The active energy ray-curable composition according to [1] or [2], wherein the active hydrogen in the compound (C) is derived from a hydroxyl group. [4] The active energy ray-curable composition according to any one of [1] to [3], wherein the solubility parameter δT of the inorganic fine particles (A) after mixing with the dispersant (B) is greater than 20. [5] The active energy ray-curable composition according to any one of [1] to [4], further comprising a photopolymerization initiator (E). [6] A cured coating film of the active energy ray ray composition according to any one of [1] to [5]. [7] An optical sheet having the cured coating film according to [6] as a coating layer. [8] The optical sheet according to [7], wherein the coating layer has a film refractive index of 1.58 to 1.78. [9] An optical member having the optical sheet according to [7] or [8] on a surface thereof.

[0009] The active energy ray-curable composition of the present invention can provide a cured coating film that has high transparency while maintaining a high refractive index and high hardness, and is therefore suitable for use in optical sheets for purposes such as anti-reflection in various displays.

[0010] The active energy ray-curable composition of the present invention (hereinafter sometimes simply referred to as the "composition") contains inorganic fine particles (A), a dispersant (B), a compound (C) having two or more (meth)acrylate groups and having an average active hydrogen concentration of 50 to 300 mgKOH / g, and a compound (D) other than the compound (C) having one or more (meth)acrylate groups. The composition of the present invention may further contain other active energy ray-curable compounds, a photoinitiator (E), and the like. In the present invention, "(meth)acrylate" refers to either or both of an acrylate and a methacrylate, and "(meth)acryloyl group" refers to either or both of an acryloyl group and a methacryloyl group.

[0011] [Inorganic fine particles (A)] Inorganic fine particles (A) are particles of inorganic compounds such as metal oxides, and examples thereof include zirconium oxide (zirconia), titanium oxide (titania), niobium oxide, barium titanate, aluminum oxide, silicon oxide, and antimony pentoxide.In the present invention, the inorganic fine particles (A) are preferably zirconia, titania, niobium oxide, and barium titanate.The inorganic fine particles (A) can be used alone or in combination of two or more kinds.

[0012] The solubility parameter δT of the inorganic fine particles (A) after mixing with the dispersant (B) in the composition of the present invention is preferably greater than 20. A solubility parameter δT greater than 20 improves compatibility with the acrylic monomer component in the composition, resulting in better transparency when the composition is cured. The solubility parameter δT, also known as the HSP value, is a physical property defined as the square root of the cohesive energy density and is an index representing the surface properties of the inorganic fine particles (A) after mixing with the dispersant (B). The closer this value is to the HSP value of the solvent, the better the compatibility. The HSP value is a vector quantity expressed as (δD, δP, δH) and is plotted in a three-dimensional space (Hansen space) with the three parameters as coordinate axes. Since the HSP values ​​of commonly used substances (e.g., organic solvents) are available from publicly known sources such as databases, the HSP value of a desired substance can be obtained, for example, by referring to the database. For substances for which HSP values ​​are not registered in the database, the HSP values ​​can be determined based on the chemical structure of the substance using computer software such as Hansen Solubility Parameters in Practice (HSPiP). HSP values ​​can also be determined by the Hansen Solubility Sphere method.

[0013] The refractive index of the inorganic fine particles (A) is, for example, 1.54 or more, preferably 1.58 or more, and more preferably 1.62 or more. The particle shape of the inorganic fine particles (A) is not particularly limited, but may be, for example, spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous, and is preferably spherical. The primary particle size of the inorganic fine particles (A) is preferably 1 to 100 nm, and particularly preferably 1 to 70 nm. The crystal structure of the inorganic fine particles (A) is also not particularly limited, but a monoclinic system is preferred.

[0014] The content of the inorganic fine particles (A) is, for example, 5 to 90% by mass, preferably 8 to 80% by mass, and more preferably 10 to 70% by mass, based on the total amount of solid components in the composition. A larger amount of inorganic fine particles (A) can provide a higher refractive index in the cured coating film, but if the amount is too large, other physical properties such as hardness and transparency may be impaired, so it is necessary to consider the balance between the refractive index and other physical properties.

[0015] [Dispersant (B)] The dispersant (B) has affinity for the inorganic fine particles (A) and the compounds (C) and (D), thereby preventing the aggregation of the inorganic fine particles (A) in the composition. Specifically, in the composition of the present invention, the dispersant (B) affects the particle surface properties of the inorganic fine particles (A), the interaction between particles of the inorganic fine particles (A) component, and the interaction between the inorganic fine particles (A) and other materials. The dispersant (B) can be used alone or in combination of two or more types.

[0016] Examples of the dispersant (B) include carboxylic acid esters, sulfate esters, sulfonate esters, and phosphate esters, among which phosphate esters are preferred because of their excellent dispersibility for the inorganic fine particles (A). The phosphate ester may be any of a phosphate monoester, a phosphate diester, and a phosphate triester, with a phosphate monoester being particularly preferred.

[0017] In particular, from the viewpoints of improving compatibility with the polymerizable components in the composition and improving the bleeding resistance and hardness of the cured coating film, it is more preferable that the phosphate ester has a (meth)acryloyl group in the molecule. For example, one represented by the following structural formula (1) is particularly preferable.

[0018] (In the formula R １ is a hydrogen atom or a methyl group, and R ２ is an alkylene chain having 2 to 4 carbon atoms, x is an integer of 4 to 10, y is an integer of 1 or more, and n is an integer of 1 to 3.

[0019] As the dispersant (B), a mixture containing various dispersants, including organosilicon compounds, in addition to the above-mentioned phosphate esters, as optional components may be used. Specific examples of the organosilicon compounds include organosilicon compounds such as hexamethyldisilazane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, phenyltrimethoxysilane, propyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane.

[0020] The content of the dispersant (B) is, for example, 2 to 15 mass %, preferably 5 to 12 mass %, more preferably 7 to 10 mass %, based on the total amount of solid components in the composition in order to provide suitable dispersibility. The content of the dispersant (B) is, for example, 5 to 40 mass parts, preferably 8 to 30 mass parts, more preferably 10 to 25 mass parts, based on 100 mass parts of the inorganic fine particles (A).

[0021] [Compound (C)] Compound (C) having two or more (meth)acrylate groups and an average active hydrogen concentration of 50 to 300 mgKOH / g can maintain high hardness when formed into a cured coating film, while improving compatibility with inorganic fine particles (A) in particular, and serves to ensure transparency when formed into a cured coating film. Compound (C) is preferably a compound having a hydroxyl group. In the case of a compound having a hydroxyl group, the active hydrogen group is a hydroxyl (—OH) group. Compound (C) can be used alone or in combination of two or more types.

[0022] The average active hydrogen concentration in the monomer of compound (C) is preferably 70 to 300 mgKOH / g, more preferably 80 to 300 mgKOH / g. When the average active hydrogen concentration is within this range, compatibility with the inorganic fine particles (A) can be particularly improved, resulting in improved transparency when the cured coating film is formed. The active hydrogen in compound (C) is preferably derived from a hydroxyl group (—OH group). The active hydrogen group here refers to a hydroxyl group, a carboxyl group, an amino group, a secondary amino group, a thiol group, etc. The average active hydrogen concentration can be expressed as mgKOH / g converted from the molar concentration. For example, the hydroxyl value (mgKOH / g) can be calculated using the following formula: For example, if 1 mol of OH groups is present in 100 g of solids, (1 mol * 56100) / 100 g = 561 mgKOH / g. The hydroxyl value (mgKOH / g) was measured in accordance with JIS test method K 0070-1992. Average active hydrogen concentration: <total amount of active hydrogen (mol) * 56,100> / total weight (g)

[0023] Examples of the compound (C) having two (meth)acrylate groups include glycerin diacrylate (average active hydrogen concentration 280 mgKOH / g), Denacol DA-314, and N,N'-methylenebis.

[0024] An example of the compound (C) having three (meth)acrylate groups is pentaerythritol triacrylate (average active hydrogen concentration: 197 mgKOH / g).

[0025] An example of the compound (C) having four or more (meth)acrylate groups is dipentaerythritol pentaacrylate (average active hydrogen concentration: 107 mgKOH / g).

[0026] The content of compound (C) is, for example, 5 to 40 mass%, preferably 10 to 35 mass%, and more preferably 15 to 30 mass%, relative to the total amount of solid components in the composition, from the viewpoint of improving the hardness and transparency of the cured coating film.

[0027] [Compound (D)] Compound (D) having one or more (meth)acrylate groups other than compound (C) is a component that adjusts physical properties such as hardness and transparency of a cured coating film in the composition. Compound (D) preferably has two or more (meth)acrylate groups, more preferably three or more (meth)acrylate groups, from the viewpoint of being able to improve the crosslinking density and increase the hardness of the cured coating film. In other words, compound (D) is preferably a polyfunctional (meth)acrylate. Compound (D) can be used alone or in combination of two or more.

[0028] Examples of the compound (D) include glycerin tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol tetra(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0029] The content of compound (D) is, for example, 3 to 30 mass%, preferably 5 to 25 mass%, and more preferably 10 to 20 mass%, relative to the total amount of solid components in the composition, from the viewpoint of improving the hardness and transparency of the cured coating film.

[0030] The composition of the present invention may further contain a urethane (meth)acrylate, which is obtained by reacting a polyisocyanate with a (meth)acrylate having a hydroxyl group.

[0031] Examples of polyisocyanates include aliphatic polyisocyanates and aromatic polyisocyanates, but aliphatic polyisocyanates are preferred because they can reduce coloration of the cured coating film of the active energy ray-curable composition of the present invention.

[0032] Aliphatic polyisocyanates are compounds in which the moieties excluding the isocyanate groups are composed of aliphatic hydrocarbons. Specific examples of these aliphatic polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; and alicyclic polyisocyanates such as norbornane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexylisocyanate), 1,3-bis(isocyanatomethyl)cyclohexane, 2-methyl-1,3-diisocyanatocyclohexane, and 2-methyl-1,5-diisocyanatocyclohexane. Trimers obtained by trimerizing the above-mentioned aliphatic polyisocyanates or alicyclic polyisocyanates can also be used as the aliphatic polyisocyanates. These aliphatic polyisocyanates can be used alone or in combination of two or more.

[0033] Examples of the (meth)acrylate having a hydroxyl group include 1,4-butanediol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and pentaerythritol tri(meth)acrylate, with pentaerythritol tri(meth)acrylate being particularly preferred.

[0034] The urethane (meth)acrylate may be one obtained by addition reaction of one molecule of the polyisocyanate with a plurality of molecules of the (meth)acrylate having a hydroxyl group.

[0035] As the urethane (meth)acrylate synthesized from the above-mentioned compound, a compound having two or more polymerizable functional groups is preferred, a compound having three or more polymerizable functional groups is more preferred, and a compound having four or more polymerizable functional groups is even more preferred, since this improves the hardness of the cured coating film of the composition of the present invention.

[0036] From the viewpoint of improving the hardness and transparency of the cured coating film, the content of the urethane (meth)acrylate is preferably 50% by mass or less, more preferably 40% by mass or less, and most preferably 30% by mass or less, based on the total amount of solid components in the composition.

[0037] [Photoinitiator (E)] The composition of the present invention may contain a photoinitiator (E). Various initiators can be used as the photoinitiator (E), and preferred examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, thioxanthone and thioxanthone derivatives, 2,2'-dimethoxy-1,2-diphenylethan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one. The photoinitiator (E) can be used alone or in combination of two or more kinds.

[0038] Among the above-mentioned compounds, it is particularly preferable to use compounds that have high solubility in water, i.e., high hydrophilicity, such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one.

[0039] The content of the photoinitiator (E) is not particularly limited, but is, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass relative to 100 parts by mass of the photocurable components such as the compounds (C) and (D), in order to easily obtain suitable curability, hardness, and the like.

[0040] The composition of the present invention may further contain a solvent. The solvent is preferably an organic solvent highly miscible with water, such as an ether solvent, an alcohol solvent, an aliphatic solvent, an aromatic solvent, a nitrogen-containing solvent, a sulfur-containing solvent, or a carboxylic acid anhydride. Specific examples of the solvent include ether solvents such as 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane; alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, ethylene glycol, propylene glycol, 1-methoxy-2-propanol, and polyethylene glycol monomethyl ether acetate (PGMEA); aliphatic solvents such as hexane and cyclohexane; aromatic solvents such as toluene and xylene; solvents containing a nitrogen atom in the molecule such as acetonitrile, nitromethane, dimethylformamide, hexamethylphosphoric triamide, triethylamine, and pyridine; solvents containing a sulfur atom in the molecule such as dimethyl sulfoxide and carbon disulfide; and carboxylic acid anhydrides such as acetic anhydride.

[0041] Among the solvents exemplified above, alcohol-based solvents such as polyethylene glycol monomethyl ether acetate (PGMEA), ethanol, 1-propanol, 2-propanol, and 1-methoxy-2-propanol are preferred, and polyethylene glycol monomethyl ether acetate (PGMEA) is particularly preferred.

[0042] [Other Components] The composition of the present invention may contain other components in addition to those described above. Representative examples of other components include fillers. For example, silica can be blended as a filler to improve hard coat properties.

[0043] The silica is not limited, and known silica particles such as powdered silica and colloidal silica can be used. Examples of commercially available powdered silica particles include Aerosil 50 and 200 manufactured by Nippon Aerosil Co., Ltd., Sildex H31, H32, H51, H52, H121, and H122 manufactured by Asahi Glass Co., Ltd., E220A and E220 manufactured by Nippon Silica Industry Co., Ltd., SYLYSIA470 manufactured by Fuji Silysia Co., Ltd., and SG Flake manufactured by Nippon Sheet Glass Co., Ltd.

[0044] Furthermore, examples of commercially available colloidal silica include methanol silica sol, IPA-ST, MEK-ST, PGM-ST, NBA-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP, ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, and ST-OL, all of which are manufactured by Nissan Chemical Industries, Ltd.

[0045] Reactive silica may be used as the silica. Examples of reactive silica include silica modified with a reactive compound. Examples of reactive compounds include reactive silane coupling agents having a hydrophobic group, compounds having a (meth)acryloyl group, compounds having a maleimide group, and compounds having a glycidyl group. Examples of commercially available powdered silica modified with a compound having a (meth)acryloyl group include Aerosil RM50 and R711 manufactured by Nippon Aerosil Co., Ltd., and examples of commercially available colloidal silica modified with a compound having a (meth)acryloyl group include MIBK-SD, MIBK-SD-L, MIBK-AC-2140Z, and MEK-AC-2140Z manufactured by Nissan Chemical Industries, Ltd. Other examples of reactive silica include silica modified with a glycidyl group such as 3-glycidoxypropyltrimethoxysilane and then subjected to an addition reaction with acrylic acid, and silica modified with a compound having 3-isocyanatepropyltriethoxysilane and a hydroxyl group and a (meth)acryloyl group subjected to a urethane reaction.

[0046] The shape of the silica fine particles is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous particles can be used. For example, commercially available hollow silica fine particles such as "Silinax (registered trademark)" manufactured by Nittetsu Mining Co., Ltd. can be used. The primary particle diameter is preferably in the range of 5 to 200 nm. If the diameter is 5 nm or more, the inorganic fine particles are sufficiently dispersed in the composition, and if the diameter is 200 nm or less, sufficient strength of the cured product can be maintained.

[0047] The amount of silica blended is preferably 3 to 60% by mass based on 100% by mass of the composition.

[0048] [Cured Coating Film] The cured coating film of the present invention can be obtained by applying or molding the composition onto a substrate, volatilizing the solvent, and irradiating with active energy rays, or by irradiating the composition without using a substrate with active energy rays.

[0049] The substrate used to form the cured coating film can be a transparent substrate in the form of a film, sheet, or plate. The material of the substrate can be appropriately selected depending on the application, etc., and examples include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins such as triacetyl cellulose, polycarbonate resins, methyl methacrylate copolymers, styrene resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, vinyl chloride resins, polymethacrylimide resins, etc. Inorganic substrates such as glass substrates can also be used.

[0050] Examples of methods for applying the composition of the present invention to a substrate include die coating, microgravure coating, gravure coating, roll coating, comma coating, air knife coating, kiss coating, spray coating, dip coating, spinner coating, brush coating, solid coating by silk screen, wire bar coating, and flow coating.

[0051] The active energy rays that cure the composition of the present invention include ionizing radiation such as ultraviolet rays, electron beams, α-rays, β-rays, γ-rays, etc. When ultraviolet rays are used as the active energy rays, examples of devices that irradiate the ultraviolet rays include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, electrodeless lamps (fusion lamps), chemical lamps, black light lamps, mercury-xenon lamps, short arc lamps, helium-cadmium lasers, argon lasers, sunlight, and LED lamps.

[0052] The thickness of the cured coating film is preferably 20 nm or more, more preferably 35 nm or more, and even more preferably 50 nm or more, in order to ensure sufficient hardness and to suppress curling of the film due to cure shrinkage of the coating film, although the thickness can be changed appropriately depending on the application and is not particularly limited thereto.

[0053] [Optical Sheet] The optical sheet of the present invention has the above-mentioned cured coating film as a coating layer on a portion of the substrate, and the refractive index of the cured coating film is preferably 1.58 to 1.78. A refractive index in this range is suitable for use in displays that require a high refractive index. The optical sheet of the present invention is a concept that also includes optical films.

[0054] The optical sheet of the present invention can be used as an anti-reflection (LR) film for flat panel displays (FPDs) such as liquid crystal displays (LCDs), organic electroluminescent displays (OLEDs), and plasma displays (PDPs). It can also be used as part of a polarizing plate for cameras, sunglasses, aircraft and vehicle windows, etc. There are no particular limitations on the application of the optical sheet, as long as it is intended for surface protection or anti-reflection.

[0055] [Optical Member] The optical member of the present invention has the above-described optical sheet on its surface. Examples of the optical member include flat panel displays (FPDs) such as liquid crystal displays (LCDs) and organic electroluminescent displays (OLEDs).

[0056] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples as long as it does not depart from the gist of the invention. Parts and percentages in the examples are all by mass unless otherwise specified.

[0057] (Examples 1 to 7, Comparative Examples 1 to 6) Each compound was melt-mixed to prepare a resin composition according to the formulation shown in Tables 1 and 2 below. The resulting composition was evaluated. The numerical values ​​for the composition blend amounts in the tables are parts by mass. The solubility parameter δT of the inorganic fine particles (A) after mixing with the dispersant (B) was calculated by the Hansen dissolved sphere method.

[0058] [Preparation of Evaluation Sample] The composition was applied to a 125 μm-thick PET film (trademark registered "Lumirror", manufactured by Toray Industries, Inc.) using a bar coater to a film thickness of 6 μm, dried at 80° C. for 1 minute, and then irradiated with an ultraviolet ray irradiation device (high-pressure mercury lamp, manufactured by Eye Graphics Co., Ltd.) in an air atmosphere at an irradiation dose of 3 kJ / m ２ A polyester film having a cured coating film was obtained as an evaluation sample.

[0059] <Film Refractive Index> The refractive index of the cured coating film of the evaluation sample obtained above was measured at a reference wavelength (589 nm) using a multi-wavelength Abbe refractometer (DR-M2) manufactured by ATAGO Co., Ltd. The values ​​in the table indicate the refractive index of the cured coating film.

[0060] <Pencil Hardness> The pencil hardness of the surface of the cured coating film of the evaluation sample obtained above was measured under a load of 500 g in accordance with JIS K5600-5-4 (1999). Five measurements were made for each hardness, and the hardness at which no scratches were observed four or more times was defined as the surface hardness of the laminate film. The pencil hardness was ranked in descending order of hardness as 3H, 2H, H, F, HB, and B, with 3H or higher being considered acceptable.

[0061] <Coating Film Haze> The haze value of the evaluation sample obtained above was measured using a haze meter ("NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS test method K7136:2000. A haze value of less than 1.0% was considered pass (◯). A haze value of 1.0% or more but less than 1.5% was considered fail (△), and a haze value of 1.5% or more was considered fail (×).

[0062]

[0063]

[0064] The abbreviations shown in Tables 1 and 2 represent the following compounds: Zirconia: Product name "UEP-100" (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) Phosphate ester compound (1): [In the formula, R １ is a methyl group, and R ２ is an ethylene chain having 2 carbon atoms, x is 5, y is 2 (average value), and n is an integer of 1 to 3. Phosphate ester compound (2): Phosphate ester compound (3): KBM-503: 3-methacryloxypropyltrimethoxysilane; product name "KBM-503" (manufactured by Shin-Etsu Chemical Co., Ltd.); glycerin diacrylate; average active hydrogen concentration 280 mg KOH / g; MIRAMER M340: pentaerythritol triacrylate; product name "MIRAMER M340" (manufactured by MIWON Co., Ltd.), average active hydrogen concentration 197 mg KOH / g; MIRAMER M500: dipentaerythritol pentaacrylate; product name "MIRAMER M500" (manufactured by MIWON Co., Ltd.), average active hydrogen concentration 107 mg KOH / g; MIRAMER M420: pentaerythritol tetraacrylate; product name "MIRAMER M420" (manufactured by MIWON Co., Ltd.); MIRAMER M600: Dipentaerythritol hexaacrylate; product name "MIRAMER M600" (manufactured by MIWON Co., Ltd.) KOMERATE T003: Trimethylolpropane acrylate; product name "KOMERATE T003" (manufactured by Green Chemical Co., Ltd.) KOMERATE A011: 2-phenylphenoxyethyl acrylate; product name "KOMERATE A011" (manufactured by Green Chemical Co., Ltd.) Runtecure 1104: 1-hydroxy-cyclohexylphenyl ketone; product name "Runtecure 1104" (manufactured by Runtec Co., Ltd.) Omnirad 907: 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by IGM Resins Co., Ltd.) PGMEA: polyethylene glycol monomethyl ether acetate

[0065] It can be seen that in Example 1-7 in Table 1 above, the pencil hardness of the cured coating film is higher, the haze is lower, and the transparency is better than in Comparative Example 1-6 in Table 2.

Claims

1. An active energy ray-curable composition containing inorganic fine particles (A), a dispersant (B), a compound (C) having two or more (meth)acrylate groups and an average active hydrogen concentration of 50 to 300 mg KOH / g, and a compound (D) having one or more (meth)acrylate groups other than the compound (C).

2. The active energy ray-curable composition according to claim 1, wherein the inorganic fine particles (A) are at least one selected from the group consisting of zirconia, titania, niobium oxide, and barium titanate.

3. The active energy ray-curable composition according to claim 1, wherein the active hydrogen in the compound (C) is derived from a hydroxyl group.

4. The active energy ray-curable composition according to claim 1, wherein the solubility parameter δT of the inorganic fine particles (A) after mixing with the dispersant (B) is greater than 20.

5. The active energy ray-curable composition according to claim 1, further comprising a photopolymerization initiator (E).

6. A cured coating film of the active energy ray composition according to any one of claims 1 to 5.

7. An optical sheet having the cured coating film according to claim 6 as a coating layer.

8. The optical sheet according to claim 7, wherein the film refractive index of the coating layer is 1.58 to 1.

78.

9. An optical member having the optical sheet according to claim 8 on its surface.

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