Curable composition for producing resin sheet

Abstract

[Problem] To provide a curable composition for the production of a resin sheet, said curable composition enabling the achievement of a resin sheet that has excellent mechanical characteristics such as hardness and bending characteristics, while being not susceptible to cracking, and exhibiting excellent impact resistance and water resistance. [Solution] A curable composition for the production of a resin sheet, said composition containing the components (A) to (D) described below, while containing from 0.1% by weight to 30% by weight of the component (A) in a total of 100% by weight of the components (A), (B) and (C) in the composition.　Component (A): one or more substances selected from the group consisting of (A-1) compounds having an optionally substituted benzene ring and a vinyl group or an isopropenyl group, (A-2) multimers of the component (A-1), and (A-3) polymers of the component (A-1) Component (B): a compound having two or more (meth)acryloyl groups Component (C): a compound having an ethylenically unsaturated group, said compound being other than the component (A) and the component (B) Component (D): a radical polymerization initiator

Description

[Technical Field]

[0001] The present invention relates to a curable composition for producing a resin sheet, and the obtained resin sheet can be preferably used as an optical substrate for liquid crystal displays (LCDs) and organic EL displays, and as a cover material for mobile devices, and belongs to these technical fields. In this specification, an acryloyl group or a methacryloyl group is referred to as a (meth)acryloyl group, and an acrylate or a methacrylate is referred to as a (meth)acrylate. [Background technology]

[0002] BACKGROUND ART In recent years, touch panel integrated liquid crystal display devices or touch panel integrated organic EL display devices have been increasingly applied to mobile devices such as smartphones, tablet terminals, and car navigation systems. Conventionally, conductive glass, which is made by forming a thin film of indium tin oxide (hereinafter referred to as "ITO") on glass, has been well known as a transparent conductive thin film for touch panels. However, because the substrate is glass, it is poor in flexibility and processability. Therefore, depending on the application, a transparent conductive sheet made of a polyethylene terephthalate sheet is used because of its advantages such as excellent flexibility, processability, impact resistance, and light weight.

[0003] On the other hand, some touch panels are being adopted with a cover integrated, in which a touch sensor such as ITO is formed directly on the cover glass, known as an OGS (One Glass Solution), because it is expected to contribute to making touch panels thinner and lighter, improving transmittance, and reducing component costs. However, the OGS type has the problem that the touch panel becomes inoperable if the cover glass is broken.

[0004] Therefore, a so-called OPS (One Plastic Solution) has been proposed as a cover material with excellent impact resistance, in which a touch sensor such as ITO is directly formed on a resin sheet. However, conventional acrylic resin or polycarbonate resin sheets have low surface hardness, making them easily scratched, and may also lack toughness, making them susceptible to cracking due to external impact force.

[0005] On the other hand, in order to reduce the weight of mobile devices, plastics are used as cover materials in addition to reducing the weight of touch sensors. However, these cover materials also use the conventional acrylic resin or polycarbonate resin sheets described above, which have the same problems as those described above, namely, low surface hardness that makes them susceptible to scratches, and insufficient toughness that can lead to cracking due to external impact force. Furthermore, resins containing many ester bonds derived from (meth)acryloyl groups, such as polymethyl methacrylate (PMMA), generally have problems with water resistance, have a high water absorption rate under high temperature and humidity conditions, and can cause problems with deformation such as warping when absorbing water.

[0006] Patent Document 1 discloses a plastic member for forming a transparent conductive film, which is obtained by photocuring a photocurable composition containing a bismethacrylate having an alicyclic skeleton and a mercapto compound. However, although the incorporation of a mercapto compound imparts a suitable level of toughness to the cured product, there are problems in that the pot life of the composition is shortened and the surface hardness is reduced.

[0007] Patent Document 2 discloses a transparent resin molded article having a thickness of 50 to 500 μm, which is obtained by photocuring a photocurable composition containing a polyfunctional urethane (meth)acrylate having an alicyclic structure, a bifunctional (meth)acrylate having an alicyclic structure, and a photopolymerization initiator. However, since it is unable to exhibit the same rigidity as glass, there is a problem that defects in appearance occur during the heating process in the transparent conductive film and metal electrode formation process.

[0008] As described above, no resin sheet has been found to date that has satisfactory physical properties for use as an OPS resin or cover material, and it has been particularly difficult to achieve both hardness and toughness.

[0009] In the production of resin sheets, either a photocurable composition or a thermosetting composition as described above is used, and each is selected depending on the purpose and properties. The advantage of thermosetting compositions is that they can be produced using simple equipment, and multiple sheets can be produced simultaneously using one heating device. However, when conventional thermosetting compositions are used, there are problems such as deformation and discoloration of the resin sheets obtained by heating. Furthermore, when the above-mentioned photocurable composition is applied to a thermosetting composition, the same problems arise. Furthermore, curable compositions containing many ester bonds derived from (meth)acryloyl groups, such as PMMA, generally have problems with water resistance, and have a high water absorption rate under high temperature and high humidity conditions, which can lead to problems of deformation such as warping when absorbing water. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-161113 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-56180 Summary of the Invention [Problem to be solved by the invention]

[0011] The present inventors have conducted extensive research to find a curable composition for producing a resin sheet that will produce a resin sheet that has excellent mechanical properties such as hardness and bending properties, is less likely to crack, has excellent impact resistance, and is excellent water resistance. [Means for solving the problem]

[0012] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that a curable composition for producing a resin sheet containing styrene or a derivative thereof and a difunctional or higher functional (meth)acrylate can solve the above-mentioned problems, and have thus completed the present invention.

[0013] The present invention provides a composition comprising the following components (A) to (D): The present invention relates to a curable composition for producing a resin sheet, which contains 0.1 to 30% by weight of component (A) relative to 100% by weight of the total amount of components (A), (B), and (C) in the composition. Component (A): (A-1) one or more compounds selected from the group consisting of a compound having a benzene ring which may have a substituent and a vinyl group or an isopropenyl group, (A-2) a multimer of component (A-1), and (A-3) a polymer of component (A-1). Component (B): a compound having two or more (meth)acryloyl groups Component (C): a compound having an ethylenically unsaturated group other than components (A) and (B). Component (D): Radical polymerization initiator

[0014] As the component (A), one or more selected from the group consisting of styrene or a derivative thereof as the component (A-1), an oligomer of styrene or a derivative thereof as the component (A-2), and a polymer of styrene or a derivative thereof as the component (A-3) are preferred.

[0015] The (B) component preferably contains (B-1) a di(meth)acrylate having a linear or branched alkylene group having 4 to 20 carbon atoms, and further preferably, the (B-1) component is at least one selected from the group consisting of 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. Furthermore, the component (B) preferably contains a compound having three or more (meth)acryloyl groups.

[0016] The component (D) is preferably a photoradical polymerization initiator (D-1) and / or a thermal radical polymerization initiator (D-2).

[0017] The composition of the present invention is preferably used as a thermosetting composition for producing a resin sheet.

[0018] The present invention also relates to a resin sheet made of a cured product of the composition. The physical properties of the resin sheet are preferably such that the bending modulus in a bending test is 2.5 GPa or more, the 63% breaking height in a drop weight test using a 40 g weight with a tip radius of 5 mm is 40 cm or more, the pencil hardness is 3H or more, and the water absorption is 1.0% or less. Furthermore, the thickness of the obtained resin sheet after curing is preferably 100 μm to 10 mm. Furthermore, the resin sheet obtained preferably has a total light transmittance of 90% or more at a thickness of 1 mm.

[0019] A preferred method for producing a resin sheet is to pour the composition into a mold which is composed of a substrate, a substrate for providing a dam, and another substrate in this order, and then heat the composition. The present invention will be described in detail below. [Effects of the Invention]

[0020] According to the composition of the present invention, the resin sheet obtained has excellent mechanical properties such as hardness and bending properties, is resistant to cracking, has excellent impact resistance, and is excellent in water resistance. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram showing an example of a molding die used when producing a resin sheet using the composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides a composition comprising the following components (A) to (D): The present invention relates to a curable composition for producing a resin sheet, which contains 0.1 to 30% by weight of component (A) relative to 100% by weight of the total amount of components (A), (B), and (C) in the composition. Component (A): (A-1) one or more compounds selected from the group consisting of a compound having a benzene ring which may have a substituent and a vinyl group or an isopropenyl group, (A-2) a multimer of component (A-1), and (A-3) a polymer of component (A-1). Component (B): a compound having two or more (meth)acryloyl groups Component (C): a compound having an ethylenically unsaturated group other than components (A) and (B). Component (D): Radical polymerization initiator The components (A) to (D), the composition, the method for producing the resin sheet, and uses of the resin sheet will be described below.

[0023] 1. (A) Component The component (A) is at least one member selected from the group consisting of (A-1) a compound having a benzene ring, which may have a substituent, and a vinyl group or an isopropenyl group (hereinafter referred to as "component (A-1)"), (A-2) a multimer of component (A-1) (hereinafter referred to as "component (A-2)"), and (A-3) a polymer of component (A-1) (hereinafter referred to as "component (A-3)"). Examples of the substituent on the benzene ring include alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy and ethoxy, hydrophilic groups such as hydroxyl, carboxyl, sulfone, and salts thereof; ester groups such as acetoxy; and halogen atoms such as chlorine, bromine, and iodine. As the component (A-1), styrene and styrene derivatives are preferred.

[0024] In the component (A-1), a specific example of a compound having a benzene ring and one vinyl group is styrene, and a specific example of a compound having a benzene ring and two or more vinyl groups is divinylbenzene. In the component (A-1), examples of the compound having a substituted benzene ring and a vinyl group include 4-methylstyrene (vinyltoluene), vinylbenzoic acid, tert-butoxystyrene, tert-butylstyrene, hydroxystyrene, sodium styrenesulfonate, acetoxystyrene, methoxystyrene, α-methylchlorostyrene, trifluoromethylstyrene, trimethylsilyloxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, and chloromethylstyrene. Specific examples of the compound containing a benzene ring and an isopropenyl group in the component (A-1) include α-methylstyrene.

[0025] The polymer of component (A-1) that is component (A-2) is preferably a styrene oligomer or an oligomer of a styrene derivative, specific examples of which include styrene dimer, styrene trimer, α-methylstyrene dimer, and α-methylstyrene trimer, with α-methylstyrene dimer being preferred. The term "multimer" of component (A-1) refers to a compound of dimer or more, preferably a compound of trimer or less.

[0026] Specific examples of the component (A-3) include the polymers of the component (A-1) described above, with styrene polymers and polymers of styrene derivatives being preferred. The molecular weight of component (A-3) can be selected arbitrarily as long as it has excellent compatibility with components (B) and (C) and does not cause cloudiness due to separation during curing. The molecular weight of component (A-3) is preferably a number-average molecular weight of 500,000 or less, more preferably 10,000 or less, in terms of excellent viscosity and compatibility during casting. In the present invention, the number average molecular weight (hereinafter referred to as "Mn") means the molecular weight measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0027] The component (A) may be used alone or in combination of two or more.

[0028] The content of component (A) is 0.1 to 30% by weight, preferably 1 to 20% by weight, of 100% by weight of the total of components (A), (B), and (C) in the composition. If the content of component (A) is less than 0.1% by weight, the water resistance of the cured product will decrease; specifically, the water absorption will exceed 1%. On the other hand, if the content exceeds 30% by weight, the hardness of the cured product will decrease; specifically, the pencil hardness will fall below 2H.

[0029] 2.(B) Component The component (B) is a compound having two or more (meth)acryloyl groups. Examples of component (B) include compounds having two (meth)acryloyl groups (hereinafter referred to as "bifunctional (meth)acrylates") and compounds having three or more (meth)acryloyl groups (hereinafter referred to as "trifunctional or higher (meth)acrylates").

[0030] 2-1. Difunctional (meth)acrylate Examples of the bifunctional (meth)acrylate include a di(meth)acrylate having an alkylene group and a polyalkylene glycol di(meth)acrylate.

[0031] A preferred example of the di(meth)acrylate having an alkylene group is a di(meth)acrylate having a linear or branched alkylene group having 4 to 20 carbon atoms [hereinafter referred to as "component (B-1)"]. The component (B-1) is a di(meth)acrylate having a linear or branched alkylene group having a carbon number of 4 to 20. In the present invention, the alkylene group refers to a divalent substituent formed by removing two hydrogen atoms from an alkane. These di(meth)acrylates provide a cured product with superior hardness and scratch resistance compared to di(meth)acrylates having a linear or branched alkylene group with 3 or less carbon atoms, and provide a cured product with superior rigidity and heat resistance compared to compounds with 21 or more carbon atoms. As the divalent linear alkylene group having 4 to 20 carbon atoms in the component (B-1), a 1,4-butylene group, a 1,6-hexylene group, or a 1,9-nonylene group having bonds at both ends is preferred. Specific examples of such compounds include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate.

[0032] The divalent branched alkylene group having 4 to 20 carbon atoms in the component (B-1) is preferably a neopentylene group (2,2-dimethyl-1,3-propylene group), a 2-methyl-1,3-propylene group, or an isobutylene group with a degree of polymerization of 5 or less, which has bonds at both ends. A specific example of such a compound is neopentyl glycol di(meth)acrylate, which is most preferably used.

[0033] Of these compounds, the component (B-1) is preferably at least one selected from 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. Of these compounds, the component (B-1) is more preferably at least one selected from 1,6-hexanediol di(meth)acrylate and 1,9-nonanediol di(meth)acrylate.

[0034] As the polyalkylene glycol di(meth)acrylate, a di(meth)acrylate in which the total number of carbon atoms constituting the polyoxyalkylene group is 4 to 20 is preferred. Specific examples of polyalkylene glycol di(meth)acrylates include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, and poly(1-methylbutylene glycol) di(meth)acrylate.

[0035] Among these compounds, the polyalkylene glycol di(meth)acrylate is preferably at least one selected from polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polybutylene glycol di(meth)acrylate. Of these compounds, the polyalkylene glycol di(meth)acrylate is more preferably at least one selected from polyethylene glycol di(meth)acrylate and polypropylene glycol di(meth)acrylate.

[0036] Examples of the bifunctional (meth)acrylate other than the above include bifunctional (meth)acrylates having an aromatic skeleton, such as di(meth)acrylate of bisphenol A alkylene oxide adduct and bisphenol A di(meth)acrylate; bifunctional (meth)acrylates having an aliphatic skeleton, such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate; Hydroxypivalic acid neopentyl glycol di(meth)acrylate; bifunctional (meth)acrylates having an alicyclic skeleton, such as dimethyloltricyclodecane di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and spiroglycol di(meth)acrylate; In the above, examples of the alkylene oxide adduct include ethylene oxide adducts and propylene oxide adducts.

[0037] In addition to the compounds mentioned above, examples of the bifunctional (meth)acrylate include polyester (meth)acrylate and epoxy (meth)acrylate. These compounds will be explained below.

[0038] 2-1-1. Polyester (meth)acrylate Examples of polyester (meth)acrylates include dehydration condensates of polyester diols and (meth)acrylic acid. Examples of polyester diols include reaction products of diols with dicarboxylic acids or their anhydrides. Examples of diols include low-molecular-weight diols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, as well as alkylene oxide adducts of these compounds. Examples of dicarboxylic acids or anhydrides thereof include dicarboxylic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, fumaric acid, maleic acid, hexahydrophthalic acid, tetrahydrophthalic acid, and trimellitic acid, as well as anhydrides of these compounds.

[0039] 2-1-2.Epoxy (meth)acrylate Epoxy (meth)acrylate is a compound obtained by addition reaction of (meth)acrylic acid with epoxy resin. Examples of epoxy resin include aromatic epoxy resin and aliphatic epoxy resin.

[0040] Specific examples of aromatic epoxy resins include diglycidyl ethers having a benzene skeleton, such as resorcinol diglycidyl ether and hydroquinone diglycidyl ether; bisphenol-type diglycidyl ethers, such as diglycidyl ethers of bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, or alkylene oxide adducts thereof; novolac-type epoxy resins, such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; glycidyl phthalimide; and o-phthalic acid diglycidyl ester.

[0041] Specific examples of aliphatic epoxy resins include diglycidyl ethers of alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol; diglycidyl ethers of polyalkylene glycols such as diglycidyl ethers of polyethylene glycol and polypropylene glycol; diglycidyl ethers of neopentyl glycol, dibromoneopentyl glycol, and alkylene oxide adducts thereof; diglycidyl ethers of hydrogenated bisphenol A and alkylene oxide adducts thereof; and tetrahydrophthalic acid diglycidyl ester. In the above, the alkylene oxide of the alkylene oxide adduct is preferably ethylene oxide, propylene oxide, or the like.

[0042] 2-2.3 or more functional (meth)acrylates Examples of tri- or higher functional (meth)acrylates include polyol poly(meth)acrylates such as glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri- or tetra(meth)acrylate, ditrimethylolpropane tri- or tetra(meth)acrylate, and dipentaerythritol tri-, tetra-, penta-, or hexa(meth)acrylate; and Examples of the alkylene oxide adduct include poly(meth)acrylates of polyol alkylene oxide adducts such as tri(meth)acrylate of glycerin alkylene oxide adduct, tri(meth)acrylate of trimethylolpropane alkylene oxide adduct, tri- or tetra(meth)acrylate of pentaerythritol alkylene oxide adduct, tri- or tetra(meth)acrylate of ditrimethylolpropane alkylene oxide adduct, and tri-, tetra-, penta- or hexa(meth)acrylate of dipentaerythritol alkylene oxide adduct. In the poly(meth)acrylate of the polyol alkylene oxide adduct, the alkylene oxide is preferably ethylene oxide or propylene oxide.

[0043] 2-3.Preferred embodiment As the component (B), the above-mentioned compounds may be used alone or in combination of two or more. The (B) component preferably contains the above-mentioned (B-1) component, and the (B-1) component is preferably at least one selected from 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate. In this case, the content of the component (B-1) is preferably 20 to 75% by weight, more preferably 30 to 65% by weight, based on 100% by weight of the total amount of the components (B). Furthermore, it is preferable that the component (B) contains a compound having three or more (meth)acryloyl groups. In this case, the content of the compound having three or more (meth)acryloyl groups is preferably 5 to 99.9 wt%, and more preferably 10 to 90 wt%, of the compound having three or more (meth)acryloyl groups in 100 wt% of the total amount of component (B).

[0044] 2-4.Content ratio The content of component (B) is preferably 60 to 99.9 wt %, more preferably 75 to 98 wt %, of 100 wt % of the total amount of components (A) to (C). By making the content of component (B) 60% by weight or more, the surface hardness such as pencil hardness and 50% impact breaking height of the cured product can be excellent, and by making it 99.9% by weight or less, the water absorption rate of the cured product can be reduced to 1.0% or less. Furthermore, the preferred content of the component (B-1) is 20 to 75% by weight based on 100% by weight of the total amount of the component (B).

[0045] 3.(C) Component The component (C) is a compound having an ethylenically unsaturated group other than the components (A) and (B). Examples of component (C) include a compound other than component (A) that has one ethylenically unsaturated group (hereinafter referred to as "component (C-1)") and a compound other than component (B) that has two or more ethylenically unsaturated groups (hereinafter referred to as "component (C-2)").

[0046] 3-1.(C-1) Component Specific examples of the component (C-1) include compounds having one (meth)acryloyl group (hereinafter referred to as "monofunctional (meth)acrylate"), compounds having an amide group and one ethylenically unsaturated group, compounds having an imide and one ethylenically unsaturated group, unsaturated dicarboxylic acids, vinyl ethers, cyanoacrylates, dialkyl methylene malonates, and allyl ethers, all of which are radically polymerizable compounds. Furthermore, since the composition of the present invention is poured into a mold or coated onto a substrate and cured at room temperature, the component (C-1) is preferably a compound that is liquid at room temperature, and it is preferable not to use low-boiling point compounds such as ethylene and propylene, whose saturated vapor pressure at room temperature is equal to or greater than atmospheric pressure.

[0047] Specific examples of monofunctional (meth)acrylates include: alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; monofunctional (meth)acrylates having an alicyclic group, such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, and 1-adamantyl (meth)acrylate; Aromatic monofunctional (meth)acrylates such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, o-phenylphenol ethylene oxide adduct (1 to 4 mole adduct) (meth)acrylate, p-cumylphenol ethylene oxide adduct (1 to 4 mole adduct) (meth)acrylate, phenyl (meth)acrylate, o-phenylphenyl (meth)acrylate, and p-cumylphenyl (meth)acrylate; and Examples include alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate.

[0048] The monofunctional (meth)acrylate may be a compound having various functional groups. Specific examples include compounds having a carboxyl group, compounds having a hydroxyl group, compounds having a cyclic ether group, and compounds having an alkylaminoalkyl group. Examples of the compound having a carboxyl group include (meth)acrylic acid, polycaprolactone-modified (meth)acrylic acid, Michael addition type polymers of (meth)acrylic acid, carboxyl group-containing (meth)acrylates such as an adduct of 2-hydroxyethyl (meth)acrylate and phthalic anhydride, and an adduct of 2-hydroxyethyl (meth)acrylate and succinic anhydride. Examples of compounds having a hydroxyl group include (meth)acrylates having a hydroxyl group. Examples of the (meth)acrylate having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and hydroxyoctyl (meth)acrylate. Examples of the compound having a cyclic ether group include glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate. Examples of the compound having an alkylaminoalkyl group include alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate.

[0049] Examples of the compound having an amide group and one ethylenically unsaturated group include N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and (meth)acrylamide. Specific examples of (meth)acrylamides include N-alkylacrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nt-butyl(meth)acrylamide; N,N-dialkylacrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; Examples include N-alkoxyalkyl (meth)acrylamides such as N-hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and N-methoxyethyl (meth)acrylamide; and (meth)acryloylmorpholine. Furthermore, examples of compounds having a carbamate group similar to an amide structure include (meth)acrylates having an oxazolidone group, and specific examples thereof include 2-(2-oxo-3-oxazolidinyl)ethyl acrylate.

[0050] An example of a compound having an imide group and one ethylenically unsaturated group is a compound having a maleimide group. Examples of compounds having a maleimide group include (meth)acrylates having a hexahydrophthalimide group and (meth)acrylates having a tetrahydrophthalimide group. Specific examples of (meth)acrylates having a hexahydrophthalimide group include N-(meth)acryloyloxyethylhexahydrophthalimide. Examples of (meth)acrylates having a tetrahydrophthalimide group include N-(meth)acryloyloxyethyltetrahydrophthalimide.

[0051] Unsaturated dicarboxylic acids include maleic acids and fumaric acids. Specific examples of maleic acids include maleic anhydride, maleic acid, and maleic acid esters such as dimethyl maleate, and specific examples of fumaric acids include fumaric acid and fumaric acid esters such as dimethyl fumarate.

[0052] Examples of vinyl ethers include 2-hydroxyethyl vinyl ether, 2-hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, and diethylene glycol monovinyl ether.

[0053] Examples of cyanoacrylates include ethyl α-methylcyanoacrylate and butyl α-methylcyanoacrylate.

[0054] Examples of dialkyl methylene malonates include diethyl methylene malonate and dihexyl methylene malonate.

[0055] Examples of the allyl ethers include trimethylolpropane diallyl ether and pentaerythritol triallyl ether.

[0056] Specific examples of compounds other than those mentioned above include vinyl acetate, acetonitrile, vinylpyridine, and vinylcarbazole.

[0057] 3-2.(C-2) component The component (C-2) is a compound other than the component (B) that has two or more ethylenically unsaturated groups, and examples thereof include a compound having two or more (meth)allyl groups (hereinafter referred to as a "polyfunctional (meth)allyl compound") and allyl (meth)acrylate. Specific examples of polyfunctional (meth)allyl compounds include glycerin di(meth)allyl ether, glycerin tri(meth)allyl ether, trimethylolpropane di(meth)allyl ether, trimethylolpropane tri(meth)allyl ether, pentaerythritol di(meth)allyl ether, pentaerythritol tri(meth)allyl ether, and pentaerythritol tetra(meth)allyl ether.

[0058] As the component (C), the above-mentioned compounds may be used alone or in combination of two or more. The content of component (C) is preferably 0 to 10% by weight, and more preferably 0 to 5% by weight, based on 100% by weight of the total amount of components (A) to (C).

[0059] 4.(D) Component The component (D) is a radical polymerization initiator. When the composition is used as an active energy ray-curable composition, the component (D) to be blended is (D-1) a photoradical polymerization initiator (hereinafter referred to as "component (D-1)"); when the composition is used as a thermosetting composition, the component (D-2) is blended is (D-2) a thermal radical polymerization initiator (hereinafter referred to as "component (D-2)"). Components (D-1) and (D-2) will be described below.

[0060] 4-1.(D-1) Component The component (D-1) is a photoradical polymerization initiator. Component (D-1) is a component to be added when ultraviolet rays and visible light are used as the active energy rays. When electron beams are used, it is not necessarily required to add it, but a small amount can be added as needed to improve curability.

[0061] Specific examples of the component (D-1) include benzil dimethyl ketal, benzil, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 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, oligo[2-hydroxy-2-methyl-1-[4-1-(methylvinyl)phenyl]propanone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl)phenyl]propanone, aromatic ketone compounds such as 2-methyl-1-[4-(methylthio)]phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butan-1-one, ADEKA Optomer N-1414 (manufactured by ADEKA Corporation), phenylglyoxylic acid methyl ester, ethyl anthraquinone, and phenanthrenequinone; benzophenone compounds such as benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 4-(methylphenylthio)phenylphenylmethane, methyl-2-benzophenone, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, N,N'-tetraethyl-4,4'-diaminobenzophenone, and 4-methoxy-4'-dimethylaminobenzophenone; acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenylphosphineate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; Thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propylthioxanthone, 3-[3,4-dimethyl-9-oxo-9H-thioxanthone-2-yl]oxy]-2-hydroxypropyl-N,N,N-trimethylammonium chloride, and fluorothioxanthone; acridone compounds such as acridone and 10-butyl-2-chloroacridone; Oxime esters such as 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)] and ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime); 2,4,5-triarylimidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-phenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, and 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer; and acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane.

[0062] In addition to the above, it is also possible to use a photoradical polymerization initiator having a molecular weight of 350 or more as the component (D-1). A photoradical polymerization initiator having a molecular weight of 350 or more does not cause coloration of the resin sheet obtained by decomposition after light irradiation, and further, when used to produce a transparent conductive film, the decomposition products do not generate outgassing during vacuum deposition of the transparent conductive layer, making it possible to achieve a high vacuum in a short time and preventing a deterioration in the film quality of the conductive layer, which makes it difficult to achieve low resistance.

[0063] Specific examples of the component (D-1) include hydroxyketone polymers, such as the compound represented by the following formula (1): This compound is also preferred because of its excellent compatibility with the components (A), (B), and (C).

[0064] [ka]

[0065] In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group, and n represents a number from 2 to 5. R 2 As the alkyl group, lower alkyl groups such as methyl, ethyl and propyl groups are preferred.

[0066] Specific examples of the compound represented by formula (1) include oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone. This compound is commercially available, and for example, ESACURE KIP 150 (manufactured by Lamberti) is known. ESACURE KIP 150 is a compound represented by the above formula (1) in which R 1 is a hydrogen atom or a methyl group, R 2 is a methyl group, n is a number from 2 to 3, and is a compound having a molecular weight of [(204.3×n+16.0) or (204.3×n+30.1)].

[0067] Examples of other compounds include 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid. This compound is commercially available and is known as Omnirad 754 (manufactured by IGM RESINS BV). Omnirad 754 is a mixture of oxyphenylacetic acid, 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid, 2-(2-hydroxyethoxy)ethyl ester.

[0068] The blending ratio of component (D-1) is preferably 0.01 to 5 parts by weight, and more preferably 0.01 to 3 parts by weight, per 100 parts by weight of the combined total of components (A) to (C). By setting the blending ratio to 0.01 parts by weight or more, the composition can be cured with an appropriate amount of ultraviolet or visible light, improving productivity, while by setting the blending ratio to 5 parts by weight or less, the cured product can have excellent weather resistance and transparency.

[0069] 4-2.(D-2) Component Component (D-2) is a thermal radical polymerization initiator. As the component (D-2), various compounds can be used, and organic peroxides and azo-based initiators are preferred. Among these, organic peroxides are more preferred because they have excellent polymerization initiator efficiency, can reduce outgassing due to polymerization initiator decomposition products, and furthermore, can provide the composition with excellent impact resistance.

[0070] Specific examples of organic peroxides include 1,1-bis(t-butylperoxy)2-methylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(4,4-dibutylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(4,4-dibutylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(4,4-dibutylperoxycyclohexyl)propane, 2,2 ... Oxy)cyclododecane, dilauroyl peroxide, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxypivalate, t-hexylperoxypivalate, 2,5-dimethyl-2,5-di(m-toluoylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexylmono peroxybenzoate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxyacetate, 2,2-bis(t-butylperoxy)butane, t-butyl peroxybenzoate, n-butyl-4,4-bis(t-butylperoxy)valerate, di-t-butylperoxyisophthalate, α,α'-bis(t-butylperoxy)diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butyl peroxyhexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, and t-butyl hydroperoxide.

[0071] Specific examples of azo compounds include 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, azodi-t-octane, and azodi-t-butane. These may be used alone or in combination of two or more. The organic peroxide can also be used in combination with a reducing agent to cause a redox reaction.

[0072] The content of the component (D-2) is preferably 0.01 to 5 parts by weight per 100 parts by weight of the total amount of the components (A) to (C). By setting the proportion of the (D-2) component to 0.01 parts by weight or more, the entire resin sheet can be cured uniformly, and by setting it to 5 parts by weight or less, outgassing caused by remaining low-molecular-weight decomposition products of the polymerization initiator can be reduced.

[0073] 5. Curable composition for producing resin sheet The present invention provides a composition containing the components (A) to (D), The present invention relates to a curable composition for producing a resin sheet, which contains 0.1 to 30% by weight of component (A) relative to 100% by weight of the total amount of components (A), (B), and (C) in the composition.

[0074] The composition can be produced by a conventional method, for example, by stirring and mixing components (A) to (D), and, if necessary, other components.

[0075] The viscosity of the composition may be appropriately set depending on the purpose, and is preferably 5 to 10,000 mPa·s. In the present invention, the viscosity refers to a value measured at 25°C using an E-type viscometer (cone-plate type viscometer).

[0076] The composition of the present invention contains the above components (A) to (D) as essential components, but various other components can be added depending on the purpose. Specific examples of the other components include organic solvents, plasticizers, polymerization inhibitors and / or antioxidants, light resistance improvers, colorants, and chain transfer agents. These components will be explained below. The components described below may be used alone or in combination of two or more.

[0077] 5-1.Other ingredients 1) Organic solvents The composition of the present invention may contain an organic solvent for the purpose of improving the coating properties on the substrate. However, when the resulting resin sheet is to be used for a transparent conductive film, it is preferable that the resin sheet does not contain an organic solvent.

[0078] Specific examples of organic solvents include hydrocarbon solvents such as n-hexane, benzene, toluene, xylene, ethylbenzene, and cyclohexane; alcohol-based solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2-(methoxyethoxy)ethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-isopentyloxyethanol, 2-hexyloxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and propylene glycol monomethyl ether; ether solvents such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, bis(2-methoxyethyl) ether, bis(2-ethoxyethyl) ether, and bis(2-butoxyethyl) ether; ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, diethyl ketone, butyl methyl ketone, methyl isobutyl ketone, methyl pentyl ketone, di-n-propyl ketone, diisobutyl ketone, phoron, isophorone, cyclopentanone, cyclohexanone, and methylcyclohexanone; Ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, methyl glycol acetate, propylene glycol monomethyl ether acetate, and cellosolve acetate; and Examples of the aprotic polar solvent include N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and γ-butyrolactone.

[0079] The proportion of the organic solvent may be set as appropriate, but is preferably 90% by weight or less, more preferably 80% by weight or less, in the composition.

[0080] 2) Plasticizers A plasticizer may be added to impart flexibility to the cured product and reduce brittleness. Specific examples of plasticizers include dialkyl phthalates such as dioctyl phthalate and diisononyl phthalate, dialkyl adipates such as dioctyl adipate, sebacates, azelates, phosphates such as tricresyl phosphate, liquid polyether polyols such as polypropylene glycol, polycaprolactone diols, and liquid polyester polyols such as 3-methylpentanediol adipate, etc. Also included are soft acrylic polymers with an Mn of 10,000 or less. The blending ratio of these plasticizers may be set appropriately, but is preferably 30 parts by weight or less, and more preferably 20 parts by weight or less, per 100 parts by weight of the total of components (A) to (C) (hereinafter referred to as "curable components"). By using 30 parts by weight or less, the strength and heat resistance of the cured product can be improved.

[0081] 3) Polymerization inhibitors and / or antioxidants To improve storage stability, a polymerization inhibitor and / or an antioxidant may be added to the composition of the present invention. As the polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, 2,6-di-tert-butyl-4-methylphenol, and various phenol-based antioxidants are preferred, but sulfur-based secondary antioxidants, phosphorus-based secondary antioxidants, etc. can also be added. The total amount of the polymerization inhibitor and / or antioxidant is preferably 3 parts by weight or less, more preferably 0.5 parts by weight or less, per 100 parts by weight of the total amount of the curable components.

[0082] 4) Light resistance improver The composition of the present invention may contain a light resistance improver such as an ultraviolet absorber or a light stabilizer. Examples of ultraviolet absorbers include benzotriazole compounds such as 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole; Triazine compounds such as 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-isooctyloxyphenyl)-s-triazine; Examples of the benzophenone compounds include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3',4,4'-tetrahydroxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone. Examples of the light stabilizer include hindered amine light stabilizers such as low molecular weight hindered amine compounds such as N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, bis(1,2,6,6-)pentamethyl-4-piperidyl)-2-(3,5-ditertiarybutyl-4-hydroxybenzyl)-2-n-butylmalonate, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate; and high molecular weight hindered amine compounds such as N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine and bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate. The blending ratio of the light resistance improver is preferably 0 to 5 parts by weight, more preferably 0 to 1 part by weight, relative to 100 parts by weight of the total amount of the curable components.

[0083] 5) Coloring agents The colorant may include a pigment and a dye. Examples of the pigment include organic pigments and inorganic pigments. Specific examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow, and pyrazolone red; soluble azo pigments such as litol red, heliobordeaux, pigment scarlet, and permanent red 2B; derivatives of vat dyes such as alizarin, indanthrone, and thioindigo maroon; phthalocyanine organic pigments such as phthalocyanine blue and phthalocyanine green; quinacridone organic pigments such as quinacridone red and quinacridone magenta; perylene organic pigments such as perylene red and perylene scarlet; and isoindoline. isoindolinone-based organic pigments such as perinone yellow and isoindolinone orange; pyranthrone-based organic pigments such as pyranthrone red and pyranthrone orange; thioindigo-based organic pigments; condensed azo-based organic pigments; benzimidazolone-based organic pigments; quinophthalone-based organic pigments such as quinophthalone yellow, isoindoline-based organic pigments such as isoindoline yellow; and other pigments such as flavanthrone yellow, acylamide yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, and dioxazine violet. Specific examples of the inorganic pigment include titanium oxide, barium sulfate, calcium carbonate, zinc oxide, lead sulfate, yellow lead, zinc yellow, red iron oxide (red iron (III) oxide), cadmium red, ultramarine, Prussian blue, chromium oxide green, cobalt green, umber, titanium black, and synthetic iron black. Carbon black, which is an example of the filler, can also be used as an inorganic pigment. As the dye, various conventionally known compounds can be used. The blending ratio of the colorant may be appropriately set depending on the purpose, and is preferably 0.00001 to 1.0 part by weight, and more preferably 0.00001 to 0.1 part by weight, per 100 parts by weight of the total amount of the curable components.

[0084] 6) Chain transfer agent A chain transfer agent can also be used to control the polymer structure, such as the primary chain length, of the cured product. Examples of chain transfer agents include mercaptans, dithioester compounds, xanthate compounds, trithiocarbonate compounds, dithiocarbamate compounds, and carbon tetrachloride. The α-methylstyrene dimer of component (A) also functions as a chain transfer agent.

[0085] Among the examples of mercaptans, polyfunctional mercaptans may be blended as needed for the purposes of preventing cure shrinkage of the cured composition and imparting toughness. As the polyfunctional mercaptan, various compounds can be used as long as they have two or more mercapto groups. For example, pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, etc. may be mentioned. The proportion of the polyfunctional mercaptan is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and particularly preferably 5 parts by weight or less, per 100 parts by weight of the curable component. By keeping this proportion 20 parts by weight or less, it is possible to prevent a decrease in the heat resistance and rigidity of the resulting cured product.

[0086] 7) Other ingredients other than those mentioned above In addition to the other components described above, the composition of the present invention may also contain a release agent, a filler, a soluble polymer, and the like. The release agent is blended to facilitate the release of the resulting resin sheet from the substrate. As the release agent, various surfactants can be used as long as they allow release from the substrate and do not cloud the compounded liquid or cured product. Examples include anionic surfactants such as alkylbenzenesulfonic acid, cationic surfactants such as alkylammonium salts, nonionic surfactants such as polyoxyethylene alkyl ethers, amphoteric surfactants such as alkylcarboxybetaines, and surfactants containing fluorine or silicon. The filler is blended for the purpose of improving the mechanical properties of the resulting resin sheet. The filler can be either an inorganic compound or an organic compound. Examples of inorganic compounds include silica and alumina. Examples of organic compounds include polymers. When the resin sheet obtained from the composition of the present invention is used for optical applications, the filler is preferably one that does not deteriorate the optical properties. The soluble polymer is blended for the purpose of improving the mechanical properties of the resulting resin sheet. The soluble polymer means a polymer that dissolves in the composition. In the present invention, a polymer that does not dissolve in the composition is called a filler to distinguish it from the soluble polymer. The blending ratio of these other compounds is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less, per 100 parts by weight of the curable component.

[0087] For the purpose of adjusting the optical properties of the resulting resin sheet, an infrared absorbing agent, a visible light blocking and infrared transmitting agent, an ultraviolet absorbing agent, a coloring agent, and the like may be blended. Examples of the ultraviolet absorber and colorant include the same compounds as those mentioned above. Visible light-shielding / infrared-transmitting agents block light in the 400 to 800 nm range and transmit near-infrared light of 800 nm or more, and are generally used in combination with dyes that absorb in the visible light range of 400 to 800 nm. Examples of dyes that absorb in the visible light range include phthalocyanine compounds, polymethine dyes, diphenylmethane dyes, triphenylmethane dyes, cyanine dyes, merocyanine dyes, and azo compounds.

[0088] Examples of the infrared absorbing agent include near-infrared absorbing agents. Examples of the near-infrared absorbing agent include near-infrared absorbing dyes, which are dyes that have absorption in the near-infrared region of 700 to 2000 nm. Examples of near-infrared absorbing dyes include cyanine dyes having an extended polymethine skeleton, phthalocyanine dyes having aluminum or zinc at the center, various naphthalocyanine compounds, nickel dithiolene complexes having a planar tetracoordinate structure, squarylium dyes, quinone compounds, diimmonium compounds, and azo compounds.

[0089] 5-2. Physical properties of cured product The cured product of the composition of the present invention preferably has a flexural modulus of 2.5 GPa or more, more preferably 3.0 GPa or more, in a bending test. A cured product of the composition having this modulus will have excellent rigidity. The elastic modulus in the bending test in the present invention means a value calculated from a strain of 0.1% and a stress of 1% in a bending test carried out at a support distance of 30 mm and a bending speed of 0.2 mm / min.

[0090] Furthermore, the cured product of the composition of the present invention preferably has excellent impact resistance as a physical property. Specifically, the 63% breaking height in a drop weight test using a 40 g weight with a tip radius of 5 mm is preferably 40 cm or more, and more preferably 45 cm or more.

[0091] Furthermore, the cured product of the composition of the present invention preferably has high hardness, specifically a pencil hardness of 3H or more. The pencil hardness in the present invention means a value measured by a method in accordance with JIS K-5600.

[0092] Furthermore, the physical properties of the cured product of the composition of the present invention are preferably excellent in water resistance, and the water absorption is preferably 1.0% or less, more preferably 0.95% or less. The water absorption rate in the present invention means a value measured in accordance with JIS K 7209. Specifically, the weight of a test piece of 1 mm thick and 60 × 60 mm is measured, and the test piece is placed in a constant temperature and humidity chamber at 85°C and 85% RH for 72 hours, and then the weight of the test piece is measured, and the water absorption rate means the rate of change in weight before and after the test.

[0093] When the cured product of the composition of the present invention is used for optical purposes, the total light transmittance is preferably 90% or more, and more preferably 91% or more. In the present invention, the total light transmittance refers to the result of measurement of a test piece having a thickness of 1 mm in accordance with JIS K7375.

[0094] The cured product of the composition of the present invention preferably has excellent physical properties such as flexural modulus in a bending test, impact resistance, pencil hardness, and water resistance. Specifically, it is preferable that the bending modulus in a bending test is 2.5 GPa or more, the 63% breaking height in a drop weight test using a 40 g weight with a tip radius of 5 mm is 40 cm or more, the pencil hardness is 3H or more, and the water absorption is 1.0% or less.

[0095] 5-3.Film Thickness When the composition of the present invention is used in a resin sheet, the thickness of the resin sheet may be appropriately set depending on the purpose. In particular, when used as a replacement for glass such as OPS, the thickness is preferably 100 μm to 10 mm, more preferably 200 μm to 3 mm, and particularly preferably 300 μm to 2 mm.

[0096] 6. Manufacturing method of resin sheet As a method for producing a resin sheet using the composition of the present invention, various methods can be adopted. In the technical field of the resin sheet according to the present invention, a relatively thick resin sheet is often called a sheet, and a relatively thin resin sheet is often called a film. As described above, in the present invention, the term "resin sheet" means a resin sheet or a resin film.

[0097] Specifically, when an active energy ray-curable composition is used as the composition, the following four production methods can be mentioned, for example. 1) Method 1-1 A method in which the composition is applied to a substrate and then cured by irradiating it with active energy rays. 2) Method 1-2 A method in which a composition is applied to a substrate, and then laminated to another substrate, and then the composition is cured by irradiating it with active energy rays. 3) Method 1-3 A method in which the composition is poured into a substrate having a space and then cured by irradiating it with active energy rays. 4) Method 1-4 A method in which a composition is poured into a substrate having a hollow space, and then laminated to another substrate, and then the composition is cured by irradiating it with active energy rays. In these production methods, heating can also be carried out after irradiation with active energy rays. When the resin sheet obtained from the composition of the present invention is used as a glass substitute, the above-mentioned Production Method 1-4 is preferred. When a resin sheet obtained from the composition of the present invention is used as a polarizer protective film, the above Production Methods 1-1 and 1-2 are preferred.

[0098] When a thermosetting composition is used as the composition, the following four production methods can be mentioned, for example. 5) Method 2-1 A method in which the composition is applied to a substrate and then heated to cure the composition. 6) Method 2-2 A method in which a composition is applied to a substrate, and then laminated to another substrate, and then heated to cure the composition. 7) Method 2-3 A method in which the composition is poured into a substrate having a space and heated to harden the composition. 8) Method 2-4 A method in which a composition is poured into a substrate with a hollow space, and then laminated to another substrate, and then heated to harden the composition. When the resin sheet obtained from the composition of the present invention is used as a glass substitute, the above-mentioned Production Method 2-4 is preferred. When a resin sheet obtained from the composition of the present invention is used as a polarizer protective film, the above Production Methods 2-1 and 2-2 are preferred.

[0099] The polymerization method may be either a batch method or a continuous method. An example of a continuous method is a method in which a belt-shaped substrate is continuously supplied with the composition as a coating or poured substrate. Another example of the continuous method is a method called a continuous casting method, in which two continuous mirror-finished stainless steel belts are arranged one above the other like a caterpillar, a composition is poured between the belts, and polymerization is continuously carried out between the belts while the belts are slowly moved, thereby producing a resin sheet. For glass replacement applications, the batch method is preferred.

[0100] 6-1. Base material As the substrate, either a releasable substrate or a substrate that does not have releasability (hereinafter referred to as a "non-releasable substrate") can be used. Examples of the releasable substrate include metal, glass, release-treated polymer films, and releasable surface-untreated polymer films (hereinafter collectively referred to as "release materials"). To facilitate the release of the cured product, the surface of the substrate may be subjected to a release treatment, for example, by coating or treating the surface of the substrate with silicone or the like. Examples of release-treated polymer films and surface-untreated polymer films having releasability include silicone-treated polyethylene terephthalate films, surface-untreated polyethylene terephthalate films, surface-untreated cycloolefin polymer films, and surface-untreated OPP films (polypropylene).

[0101] To achieve low haze and surface smoothness for the resin sheet obtained from the composition of the present invention, a substrate having a surface roughness (center line average roughness) Ra of 0.15 μm or less is preferably used, more preferably 0.001 to 0.100 μm. Furthermore, the haze is preferably 3.0% or less.

[0102] Specific examples of the substrate include glass, polyethylene terephthalate film, cycloolefin polymer film, OPP film (oriented polypropylene), polyvinyl alcohol, cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose, acrylic resin, polyester, polycarbonate, polyarylate, polyethersulfone, and cyclic polyolefin resins containing cyclic olefins as monomers such as norbornene. In the present invention, the surface roughness Ra means the average roughness calculated by measuring the irregularities on the surface of the film.

[0103] Examples of non-releasable substrates include various plastics other than those mentioned above, such as polyvinyl alcohol, cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose, acrylic resins, polyesters, polycarbonates, polyarylates, polyethersulfones, and cyclic polyolefin resins containing cyclic olefins as monomers, such as norbornene. When the composition of the present invention is used as a polarizer protective material, a polyvinyl alcohol film impregnated with iodine or a dye and then stretched, that is, a polarizer film, serves as the substrate. When the resin sheet or film, which is a polymer of the curable composition, is used in practical applications in a state where the substrate and the cured layer are integrated without being peeled off from the substrate, physical or chemical treatments such as corona discharge treatment can be applied to the surface of the substrate in order to improve the adhesion between the two layers.

[0104] An example of a substrate having a space is a substrate having a recess, which is formed by drilling a hole of a predetermined shape to achieve a desired film thickness in a formwork material. In this case, after the composition is poured into a substrate having a recess, another substrate can be placed on top of the substrate having the recess. Another example of a substrate having a space is a mold material on which a weir (spacer) is provided so that the cured product has a desired film thickness (hereinafter referred to as a "molding mold"). In this case, another substrate can also be placed on top of the weir.

[0105] An example of the mold will be explained with reference to FIG. Figures 1(a1-1) and (a1-2) show examples of a mold consisting of two substrates (Figure 1: (a1-1)(1) and (a1-2)(1)'), two substrates with excellent releasability (Figure 1: (a1-1)(2) and (a1-2)(2)'), and one substrate for providing a dam (Figure 1: (a1-1)(3)). Figure 1(a2) shows an example of a mold consisting of two substrates [(1) and (1)' in Figure 1(a2)] and one substrate for providing a dam [(3) in Figure 1(a2)].

[0106] As shown in Fig. 1, the substrate for providing the dam may have a shape with a hole at the top [(3-1) in Fig. 1: (a1-1)] for injecting the composition, or a shape without a hole, and preferably has a hole at the top for injecting the composition. Various materials can be used as the substrate for providing the dam, and an example of such a material is silicone rubber.

[0107] Specific examples of (a1-1) and (a1-2) in FIG. 1 include a mold composed of two sheets of glass as substrates, two sheets of release-treated film, and one substrate for providing a dam. A release-treated film (Fig. 1(a1-1)(2)) is placed on top of the glass (Fig. 1(a1-1)(1)), and a substrate for providing a weir (Fig. 1(a1-1)(3)) is placed on top of that to form a spacer. A release-treated film (Fig. 1(a1-2)(2)') is then placed on top of that, and glass (Fig. 1(a1-2)(1)') is placed on top of that to form the spacer.

[0108] A specific example of (a2) in Figure 1 is when release-treated glass or metal is used as the substrate [(1) and (1)' in Figure 1: (a2)], and the cured product has excellent release properties, so the two release-treated films in (a1-1) and (a1-2) in Figure 1 are not necessary. In addition, when the cured product of the composition itself has excellent releasability, glass can also be used as the substrate [(1) and (1)' in Figure 1: (a2)]. An example of a composition in which the cured product itself has excellent releasability is one in which a release agent is blended into the composition.

[0109] 6-2. Pre-treatment of the composition When applying or injecting the composition of the present invention, it is preferable to use a composition that has been purified after stirring and mixing the raw material components, in order to prevent the inclusion of foreign matter and the occurrence of defects such as voids in the resulting resin sheet and to provide it with excellent optical properties. As a method for purifying the composition, a method of filtering the composition is simple and preferable. Examples of the filtering method include pressure filtration. The filtration accuracy is preferably 10 μm or less, more preferably 5 μm or less. The smaller the filtration accuracy, the better. The lower limit is preferably 0.1 μm, as this can prevent clogging of the filter, reduce the frequency of filter replacement, and improve productivity.

[0110] In producing a resin sheet, it is preferable to degas the mixture after blending the components to prevent bubbles from being contained in the cured product. Examples of degassing methods include leaving the mixture to stand, vacuum decompression, centrifugation, a cyclone (rotating / revolving mixer), a gas-liquid separation membrane, ultrasonic waves, pressure vibration, and degassing using a multi-screw extruder.

[0111] 6-3. Coating or injection The coating method for coating the composition on a substrate may be appropriately selected depending on the purpose, and examples include coating methods using a conventionally known bar coater, applicator, doctor blade, knife coater, comma coater, reverse roll coater, die coater, lip coater, gravure coater, microgravure coater, etc. When the composition is injected into a substrate having a space, the composition may be placed in an injection device such as a syringe or an injection apparatus and then injected.

[0112] In this case, the thickness of the resin sheet may be appropriately set depending on the desired thickness of the resin sheet. In particular, when used as a glass replacement, preferably for OPS, the thickness is preferably 100 μm to 5 mm, more preferably 200 μm to 3 mm, and particularly preferably 300 μm to 2 mm. When used as a polarizer protective layer, the thickness is preferably 10 μm to 2 mm, and more preferably 20 μm to 200 μm.

[0113] 6-4. Active energy ray irradiation When an active energy ray-curable composition is used as the composition, examples of the active energy ray include ultraviolet rays, visible light, electron beams, and X-rays, with ultraviolet rays and visible light being preferred since they can form a thick film of the cured product. Examples of the ultraviolet ray irradiation device include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a black light lamp, a UV electrodeless lamp, and an LED. The irradiation conditions such as the dose and irradiation intensity of the active energy ray irradiation may be appropriately determined depending on the composition used, the substrate, the purpose, and the like.

[0114] In this case, the film can be heated after irradiation with active energy rays. Examples of the heating method include the same methods as those described below. Heat treatment can cause stabilization through molecular chain rearrangement, progression of polymerization reactions, coupling reactions of frozen radicals, and the like, and is expected to improve heat resistance and optical properties. The heating temperature is preferably 50°C to 250°C, and more preferably 100°C to 200°C. If the heating temperature is too low, the effect of the heat treatment will be low, and if it is too high, there is a risk of a decrease in toughness due to crosslinking reactions, etc. The heating time is preferably 1 hour to 1 day, and more preferably 2 to 10 hours. If the heating time is too short, the effect of the heat treatment will be low, and if it is too long, there is a risk of a decrease in toughness due to crosslinking reactions, etc.

[0115] 6-5.Heating When a thermosetting composition is used as the composition, examples of the heating method include immersion in a heat medium bath such as heat and oil, use of a heat press, and holding in a temperature-controlled constant temperature bath. When heating, the conditions such as the heating temperature may be appropriately set depending on the composition used, the substrate, the purpose, etc. The heating temperature is preferably 40°C to 250°C. The heating time may be appropriately set depending on the composition used and the desired resin sheet, etc., and may be 3 hours or more. The upper limit of the heating time is preferably 24 hours or less from an economical viewpoint.

[0116] The heating temperature can also be changed depending on the purpose. For example, this can be achieved when using thermal polymerization initiators with different decomposition temperatures. Specific examples of the temperature include a method in which polymerization is carried out at a relatively low temperature of about 40 to 80°C for several hours, followed by polymerization at a relatively high temperature of 100°C or higher for several hours.

[0117] 7. Applications of resin sheets The resin sheet produced from the composition of the present invention is excellent in various physical properties such as the flexural modulus, impact resistance, and water resistance described above, and can be used in various applications where these physical properties are required. For example, the material may be used as a cover material for mobile devices, specifically display covers for in-vehicle displays and the like, and housing covers for mobile phones, smartphones, smartwatches and the like.

[0118] Furthermore, a resin sheet produced from the composition of the present invention has excellent optical properties and can be particularly preferably used as an optical sheet. The optical sheet formed from the composition of the present invention can be used for a variety of optical applications. More specifically, optical applications requiring a high elastic modulus and low water absorption include polarizer protective films for liquid crystal displays, protective films for polarizing plates for organic electroluminescence (EL) displays, support films for prism sheets, and photomasks. Furthermore, applications requiring high optical properties such as high transparency and low retardation include liquid crystal display devices such as light guide films, films for LED lighting or organic EL lighting, and light guide plates. Furthermore, applications requiring scratch resistance, weather resistance, and heat resistance include light-resistant (weather-resistant) sheets for outdoor use such as solar cells, transparent heat-resistant sheets for flexible electronics, automobile instrument panel covers, vehicle-mounted mirrors and their covers, covers and electrode substrate sheets used in touch panel-integrated liquid crystal display devices, and wearable display elements. In addition, applications requiring further heat resistance include transparent conductive sheets that require electrode film formation at high temperatures, and transparent heaters and covers for the purpose of preventing fogging of surveillance cameras. Furthermore, a resin sheet containing a visible light absorbent can also be used as a cover for an infrared sensor that blocks visible light that becomes noise when receiving near-infrared light.

[0119] The optical sheet formed from the composition of the present invention has excellent heat resistance and can be preferably used for producing a transparent conductive sheet. As the composition used for this purpose, a solvent-free composition containing no organic solvent is preferred, as it can suppress outgassing during vacuum deposition of the transparent conductive layer. Furthermore, the optical sheet of the present invention has excellent heat resistance, flexibility, and high strength even when it is a thick film, and therefore can also be used as a transparent conductive sheet substrate for OPS. In this case, it is more preferable to use an optical sheet with a film thickness of 0.5 mm or more and 1.5 mm or less.

[0120] The transparent conductive sheet may be produced by a conventional method. Examples of metal oxides that form the transparent conductor layer include indium oxide, tin oxide, zinc oxide, titanium oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium-zinc composite oxide, and titanium-niobium composite oxide. Of these, indium-tin composite oxide and indium-zinc composite oxide are preferred from the viewpoints of environmental stability and circuit processability. The transparent conductor layer may be formed by a conventional method, such as a method in which the transparent conductor layer is formed by sputtering using the optical sheet of the present invention and the metal oxide using a vacuum film forming apparatus. More specifically, examples of such a method include using the metal oxide as a target material, dehydrating and degassing the material, evacuating the material to create a vacuum, and then heating the optical sheet to a predetermined temperature, followed by forming a transparent conductor layer on the optical sheet using a sputtering device. [Example]

[0121] The present invention will be described in more detail below with reference to examples and comparative examples. In the following description, "parts" means parts by weight and "%" means % by weight.

[0122] 1. Examples 1 to 7, Comparative Examples 1 and 2 In Comparative Example 1, commercially available polymethyl methacrylate (Acrylite L manufactured by Mitsubishi Rayon Co., Ltd., hereinafter referred to as "PMMA") was used. 1) Production of UV-curable composition The components (A), (B), (C), and (D-1) shown in Table 1 below were blended in the proportions shown in Table 1 below, mixed with stirring, and then degassed under vacuum to produce ultraviolet-curable compositions. The numbers for components (A), (B), (C), and (D-1) in Table 1 indicate the number of parts.

[0123] [Table 1]

[0124] The abbreviations in Table 1 have the following meanings. (B) Component NDDA: 1,9-nonane diacrylate, "A-NOD-N" manufactured by Shin-Nakamura Chemical Co., Ltd. TMP-MA: Trimethylolpropane trimethacrylate, manufactured by Kyoeisha Chemical Co., Ltd., "Light Ester TMP" M-309: Trimethylolpropane triacrylate, Aronix M-309 manufactured by Toagosei Co., Ltd. (C) Component P-30: Pentaerythritol triallyl ether, "Neoallyl P-30" manufactured by Osaka Soda Co., Ltd. (D) Component Om1173: 2-hydroxy-2-methyl-1-phenyl-propan-1-one, "Omnirad 1173" manufactured by IGM Resins B.V.

[0125] 2) Manufacturing of resin sheets As a mold for producing a resin sheet, a mold shown in FIG. 1(a2) was used. Two glass plates (80 mm × 80 mm, 3 mm thick) and one silicone plate (1.0 mm thick) were used. The glass plates had been treated with a silicone compound for release. The silicone plate had a hole at the top for injecting the composition. A silicone plate (Fig. 1(a2):(3)) was placed on top of a glass plate (Fig. 1(a2):(1)) to form a spacer, and a glass plate (Fig. 1(a2):(1)') was placed on top of that to form the mold.

[0126] The composition obtained above was injected into the cavity of the silicone plate of the mold using a syringe. The mold was then irradiated with ultraviolet light (high-pressure mercury lamp) from one side of the glass plate side using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd.) at an illuminance of 130 mW / 3 m. 2 The film was exposed 20 times using UV-A (UV POWER PU3K, manufactured by Fusion UV Systems Japan Co., Ltd.) at a conveyor speed of 5 m / min. The irradiated surface was turned over after each exposure. After cooling, the glass was removed from the mold, and the resulting cured product was heated at 150°C for 16 hours to obtain a resin sheet.

[0127] 3) Evaluation method The resin sheets thus obtained were evaluated for water absorption, pencil hardness, flexural modulus, total light transmittance, and drop weight test according to the following methods. The results are shown in Table 1.

[0128] (1) Water absorption rate The weight of each 1mm thick, 60x60mm test piece was measured, and then it was placed in a constant temperature and humidity chamber at 85°C and 85%RH for 72 hours, after which the weight of the test piece was measured again. The water absorption rate was calculated based on the change in weight of each test piece immediately before and after the test.

[0129] (2) Pencil hardness The surface hardness of the obtained resin sheet was measured in accordance with JIS K-5600.

[0130] (3) Flexural modulus Five test pieces, each 40 mm long and 10 mm wide, were cut out from a resin sheet measuring 80 mm x 80 mm and 1 mm thick, and a three-point bending test was performed using an Instron 5566A (support distance 30 mm, 0.2 mm / sec, 25°C, 50% RH). The average value of the five test pieces was taken as the flexural modulus (GPa).

[0131] (4) Drop weight test (63.2% impact breaking height: impact resistance) Test pieces measuring 60 mm in length and 60 mm in width were cut from the resulting resin sheet. According to JIS K7211-1, the resulting resin sheet was placed on a metal ring with a diameter of 50 mm. A 40 g conical weight with a tip diameter of 5 mm was dropped onto the center of the resin molded body from a predetermined height (in 10 cm increments). The frequency of test piece breakage at each height was determined for 10 or more tests. The frequency distribution of test pieces that broke at each drop height was approximated to a Weibull distribution, and the Weibull distribution parameters α and β were calculated using the least squares method. β corresponds to the height (cm) at which 63.2% of the test pieces break, and this was used to evaluate impact resistance.

[0132] (5) Total light transmittance The total light transmittance of a resin sheet with a thickness of 1 mm was measured in accordance with JIS K7375.

[0133] 4) Summary The resin sheets obtained from the compositions of Examples 1 to 7 all had improved impact resistance (drop weight test) compared to commercially available PMMA. The composition of Comparative Example 2, which did not contain component (A) and was composed only of components (B) and (C), had a water absorption rate exceeding 1.0%. In contrast, the compositions of Examples 1 to 3 showed a decrease in water absorption rate depending on the amount of styrene (component (A)) added (0.1 to 5% by weight), and even adding just 0.1 part by weight was effective in reducing water absorption rate. The compositions of Examples 4 to 7 were compositions to which 5% by weight of various styrene derivatives was added as component (A). Similar to the composition of Example 3 containing styrene as component (A), the compositions of Examples 4 to 7 had the effect of reducing water absorption while maintaining pencil hardness, flexural modulus, impact resistance (drop weight test), and total light transmittance.

[0134] 2. Examples 8 to 15, Comparative Examples 3 and 4 1) Preparation of thermosetting composition The components (A), (B), and (D-2) shown in Table 2 below were blended in the proportions shown in Table 2 below, mixed with stirring, and then degassed under vacuum to produce a thermosetting composition. The numbers for components (A), (B), (C), and (D-2) in Table 2 indicate the number of parts.

[0135] [Table 2]

[0136] The abbreviations in Table 2, other than those defined above, have the following meanings. Component (A) AS-6: Terminally functionalized polystyrene, Mn: 6,000, "Macromonomer AS-6" manufactured by Toagosei Co., Ltd. Polystyrene: GPC standard sample Mn: 64,000 (Sigma-Aldrich) (B) Component DPCA30: Poly(meth)acrylate of dipentaerythritol and ε-caprolactone adduct, manufactured by Nippon Kayaku Co., Ltd., PKAYARAD DPCA-30D, hexafunctional acrylate (D-2) Component V-60: 2,2'-azobisisobutyronitrile, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0137] 2) Manufacturing of resin sheets The composition obtained above was injected using a syringe into the hole [(a2):(3-1) in Figure 1] of the silicone plate of the mold. The mold was placed in a drying oven and heated at 60°C for 0.5 hours, and then heated to 120°C over 6 hours (heating rate: 10°C / hour) to cure the composition. After cooling to room temperature, the glass was removed from the mold and the mold was demolded to obtain a resin sheet.

[0138] 3) Evaluation method The resin sheet thus obtained was evaluated for water absorption, pencil hardness, flexural modulus, total light transmittance, and drop weight test in the same manner as described above. The results are shown in Table 2.

[0139] 4) Summary The composition of Example 8, which added styrene (monomer) as component (A-1) as component (A), and the compositions of Examples 9 to 12, which added two types of polystyrene with different molecular weights as component (A-3) as component (A), all maintained their pencil hardness, flexural modulus, impact resistance (drop weight test), and total light transmittance while reducing water absorption. Similarly to the previous examples, the compositions of Examples 13 to 15, which added other components (A-1) (p-vinyltoluene, α-methylstyrene) and (A-2) (α-methylstyrene dimer) as component (A), also maintained their other physical properties while reducing water absorption. On the other hand, the composition of Comparative Example 3, which did not contain component (A), showed increased water absorption and decreased water resistance.Furthermore, the composition of Comparative Example 4, which contained styrene as component (A) at a content of 60% by weight, exceeding the upper limit of 30% by weight, showed a decreased pencil hardness of 2H and also a decreased impact resistance (drop weight test). [Industrial Applicability]

[0140] The composition of the present invention can be used to produce a resin sheet. The obtained resin sheet can be used for various purposes, and is preferably used as an optical sheet and a cover material for mobile devices. The optical sheet can be preferably used for producing a transparent conductive sheet, and more preferably used for producing a transparent conductive sheet for a touch panel.

Claims

1. A composition comprising the following components (A) to (D): A curable composition for producing a resin sheet, comprising 0.1 to 30 wt % of component (A), 60 to 99.8 wt % of component (B), and 10 wt % or less of component (C), relative to a total of 100 wt % of components (A), (B), and (C) in the composition. Component (A): (A-1) one or more compounds selected from the group consisting of a compound having a benzene ring, which may have a substituent, and a vinyl group or an isopropenyl group, (A-2) a multimer of component (A-1), and (A-3) a polymer of component (A-1). Component (B): a compound having two or more (meth)acryloyl groups Component (C): a compound having two or more ethylenically unsaturated groups other than components (A) and (B). Component (D): Radical polymerization initiator

2. 2. The curable composition for producing a resin sheet according to claim 1, wherein the component (A) comprises one or more selected from the group consisting of styrene or a derivative thereof as the component (A-1), an oligomer of styrene or a derivative thereof as the component (A-2), and a polymer of styrene or a derivative thereof as the component (A-3).

3. 3. The curable composition for producing a resin sheet according to claim 1 or claim 2, wherein the component (B) comprises (B-1) a di(meth)acrylate having a linear or branched alkylene group having 4 to 20 carbon atoms.

4. The curable composition for producing a resin sheet according to claim 3, wherein the component (B-1) is at least one selected from the group consisting of 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate.

5. The curable composition for producing a resin sheet according to any one of claims 1 to 4, wherein the component (B) comprises a compound having three or more (meth)acryloyl groups.

6. The curable composition for producing a resin sheet according to any one of claims 1 to 5, wherein the component (D) comprises (D-1) a photoradical polymerization initiator.

7. The curable composition for producing a resin sheet according to any one of claims 1 to 6, wherein the component (D) comprises (D-2) a thermal radical polymerization initiator.

8. A thermosetting composition for producing a resin sheet, comprising the composition according to any one of claims 1 to 7.

9. A resin sheet comprising a cured product of the composition according to any one of claims 1 to 8.

10. 10. The resin sheet according to claim 9, wherein the bending modulus in a bending test is 2.5 GPa or more, the 63% breaking height in a drop weight test using a 40 g weight with a tip radius of 5 mm is 40 cm or more, the pencil hardness is 3H or more, and the water absorption is 1.0% or less.

11. The resin sheet according to claim 9 or claim 10, wherein the thickness of the cured product is 100 μm to 10 mm.

12. The resin sheet according to any one of claims 9 to 11, having a total light transmittance of 90% or more at a thickness of 1 mm.

13. A method for producing a resin sheet, comprising pouring the composition according to claim 8 into a mold which is composed of a substrate, a substrate for providing a dam, and another substrate in this order, and then heating the composition.

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