Sheet-shaped photocurable composition, photocurable composition solution, method for producing sheet-shaped photocurable composition, and laminate

Abstract

Provided is a sheet-like photocurable composition comprising the following (A) to (D) components in a sheet-like state at 25°C in a state before curing: (A) component: (meth)acrylic triblock copolymer; (B) component: (meth)acrylate oligomer, wherein the (A) component is excluded; (C) component: monomer having a specific structure and having a (meth)acryloyl group; and (D) component: photoinitiator.

Description

TECHNICAL FIELD

[0001] The present application relates to a photocurable composition which is sheet-shaped at 25°C. BACKGROUND

[0002] For an adhesive used in the assembly of display devices such as organic EL displays, adhesiveness is required to be good in a wide temperature range. Also, in order to improve such characteristics, it has been proposed to use a triblock copolymer elastomer having a hard segment with a high glass transition temperature and a soft segment with a low glass transition temperature in a photocurable composition.

[0003] For example, in Japanese Patent Application Publication No. 2017-036368, a photocurable adhesive composition (adhesive composition) containing a (meth)acrylate triblock copolymer elastomer as a main component and having re-peeling properties is proposed. However, the photocurable adhesive composition disclosed in this document is a composition intended to be used as an adhesive (i.e., capable of re-peeling, in a semi-solid state and remains adhesive at the time of use), and thus is not suitable for use as an adhesive (i.e., does not re-peel, and is adhered to an adherend in a solid state). Specifically, the photocurable adhesive composition disclosed in the above document is peeled off from an adherend (substrate) in a reliability test for the reason that the strength is reduced when left in a high-temperature atmosphere. SUMMARY

[0004] PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] As described above, according to the related art, a photocurable composition using a (meth)acrylate triblock copolymer used in optical applications has been proposed. However, in both normal-temperature and high-temperature environments (e.g., under a 25°C atmosphere and under an 85°C atmosphere), peeling from an adherend (substrate) sometimes becomes a problem. Also, when a (meth)acrylic resin plate, a polyethylene terephthalate (PET) film, or the like is used as an adherend (substrate), it is particularly difficult to improve the peel adhesion strength (adhesion) to these adherends (substrates).

[0006] The present application was completed in view of the above circumstances, and aims to provide a means for improving the peel adhesion strength of a photocurable composition to a resin substrate whose peel adhesion strength is difficult to improve in both normal-temperature and high-temperature environments.

[0007] MEANS FOR SOLVING THE PROBLEM

[0008] The present inventors and others have conducted intensive studies in order to achieve the above object, and as a result, have found that the sheet-shaped photocurable composition described in detail below can improve the peel adhesion strength to a resin substrate whose peel adhesion strength is difficult to improve in both normal-temperature and high-temperature environments, thereby completing the present application.

[0009] To achieve at least one of the above objects, a sheet-like photocurable composition reflecting one aspect of the present application contains the following (A) to (D) components in a sheet-like state at 25°C in a state before curing:

[0010] (A) Component: (Meth)acrylic tri-block copolymer

[0011] (B) Component: (Meth)acrylate oligomer, wherein the above (A) component is excluded

[0012] (C) Component: Compound represented by the following Formula 1

[0013]

[0014] (In the above Formula 1, R 1 is a hydrogen atom or a methyl group, and R 2 is a monovalent organic group containing an oxygen atom)

[0015] (D) Component: Photoinitiator.

[0016] Further, the present inventors have found that the above problems can be solved by using a photocurable composition solution containing the following (A) to (D) components and a solvent, and thus completed the present application.

[0017] To achieve at least one of the above objects, a photocurable composition solution reflecting one aspect of the present application contains the following (A) to (D) components and a solvent:

[0018] (A) Component: (Meth)acrylic tri-block copolymer

[0019] (B) Component: (Meth)acrylate oligomer, wherein the above (A) component is excluded

[0020] (C) Component: Compound represented by the above Formula 1

[0021] (D) Component: Photoinitiator. DETAILED DESCRIPTION

[0022] Hereinafter, the embodiments of the present application will be described. Further, the present disclosure is not limited to the following embodiments. In the present specification, "X to Y" means a range including the lower limit value and the upper limit value of the values (X and Y) described before and after, and means "X or more and Y or less". Further, the concentration, % means mass concentration, mass % respectively unless otherwise specified, and the ratio means mass ratio unless otherwise specified. Further, unless otherwise specified, operations and measurements of physical properties are performed under the conditions of room temperature (20 to 25°C) / relative humidity 40 to 55% RH. In addition, "A and / or B" means each of A and B and combinations thereof.

[0023] Sheet-shaped photocurable composition

[0024] A sheet-shaped photocurable composition (hereinafter, also referred to as "sheet-shaped photocurable composition" or simply "composition") of one embodiment of the present application contains components (A) to (D) below, and is in a sheet shape at 25°C in a state before curing:

[0025] (A) Component: (Meth)acrylic acid-based triblock copolymer

[0026] (B) Component: (Meth)acrylate oligomer, wherein the above (A) component is excluded

[0027] (C) Component: Compound represented by the following Formula 1

[0028]

[0029] (In the above Formula 1, R 1 is a hydrogen atom or a methyl group, and R 2 is a monovalent organic group containing an oxygen atom)

[0030] (D) Component: Photoinitiator

[0031] The sheet-shaped photocurable composition according to one embodiment of the present application can improve the peel adhesion strength to a resin substrate such as a polyethylene terephthalate (PET) film, a (meth)acrylic resin plate, or a triacetyl cellulose (TAC) film in both a normal temperature environment and a high temperature environment (e.g., under an atmosphere at 25°C and under an atmosphere at 85°C), i.e., from a normal temperature environment of about 25°C to a high temperature environment of about 85°C.

[0032] Conventionally, these resin substrates have a hydrophobic surface, and thus it is difficult to perform adhesion using an adhesive. The composition containing a (meth)acrylate-based triblock copolymer has insufficient adhesion to these resin substrates.

[0033] Further, in order to obtain an adhesive that can be used in a wide temperature range, when the above-described triblock copolymer (triblock copolymer having a hard segment and a soft segment) is added to a composition, there is a problem in that similar segments (blocks) are aggregated with each other to form a microphase separation structure, and thus it is difficult to improve the adhesion to a substrate.

[0034] However, it is presumed that the sheet-shaped photocurable composition according to the present application can exert good adhesiveness even to a resin substrate for which it has been difficult to improve the peel adhesion strength by containing the compound contained as the (C) component. Therefore, the sheet-shaped photocurable composition according to the present application can obtain good adhesiveness to a resin substrate even in the case of using a tri-block copolymer of (meth) acrylate. Moreover, by using a tri-block copolymer of (meth) acrylate, excellent adhesiveness can be obtained in a wide temperature range.

[0035] In addition, the above-mentioned mechanism is based on presumption, and the correctness of the mechanism does not affect the technical scope of the present application.

[0036] The sheet-shaped photocurable composition of the present application is in a sheet shape at 25°C in a state before curing. Here, the "sheet shape" means a shape having an extension as a two-dimensional plane, and having a surface and a back surface which are opposed with a distance of a thickness amount therebetween. The thickness is not particularly limited, and is preferably, for example, 5 to 300 μm, and particularly preferably 10 to 200 μm. If the thickness of the sheet-shaped photocurable composition is in the above-mentioned range, the solvent used at the time of production is sufficiently volatilized, and generation of pinholes and voids can be effectively suppressed.

[0037] In addition, in the present specification, the composition which is in a state before curing and is formed into a sheet shape is referred to as a "sheet-shaped photocurable composition". In addition, the composition in a state before processing into a sheet shape and before curing is also simply referred to as a "photocurable composition". Furthermore, the "photocurable composition solution" means a solution containing a solvent in addition to the components contained in the sheet-shaped photocurable composition. In addition, the "cured product" means a substance in which polymerization by light irradiation is performed in a state not containing a solvent with respect to the sheet-shaped photocurable composition.

[0038] Hereinafter, the components contained in the sheet-shaped photocurable composition of one embodiment of the present application will be described.

[0039] <(A) component>

[0040] The (A) component contained in the sheet-shaped photocurable composition of the present application is a (meth)acrylate tri-block copolymer (also referred to as a "(meth)acrylic tri-block copolymer" or simply "tri-block copolymer" in the present specification). Note that, in the present specification, "(meth)acrylate" refers to a compound having a (meth)acryloyl group. Also, the term "(meth)acryloyl group" includes both acryloyl and methacryloyl groups. Thus, for example, the term "(meth)acryloyl group" encompasses both acryloyl (H2C=CH-C(=O)-) and methacryloyl (H2C=C(CH3)-C(=O)-) groups. Also, likewise, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylic acid" encompasses both acrylic acid and methacrylic acid. The (meth)acryloyl group can also be included in the component in the form of a (meth)acryloyloxy group.

[0041] The tri-block copolymer of a (meth)acrylate as the (A) component is a tri-block copolymer obtained by polymerizing a (meth)acrylate monomer (an ester compound having one or more (meth)acryloyl groups). By containing such an (A) component, the sheet-shaped photocurable composition of the present application is excellent in release adhesion strength in both normal-temperature and high-temperature environments (for example, under a 25°C atmosphere and under a 85°C atmosphere). Also, the tri-block copolymer of a (meth)acrylate is excellent in compatibility with a (meth)acrylate oligomer, and in particular, is excellent in compatibility with the (B) component described in detail below. In this way, if the compatibility with the (B) component is good, the transparency becomes high, and a sheet-shaped photocurable composition suitable for display elements or optical uses can be obtained.

[0042] The (A) component is preferably an elastomer that does not contain a reactive functional group. The tensile elongation of the (A) component is preferably 100 to 600%, more preferably 110 to 580%, and particularly preferably 130 to 400%. If the tensile elongation is 100% or more, the softness of the sheet-shaped photocurable composition is improved, and it is easy to follow a concave-convex surface or a curved surface, and the like, and thus excellent adhesion can be exerted to surfaces of various shapes. On the other hand, if the tensile elongation is 600% or less, the sheet-shaped photocurable composition does not become too soft, workability becomes good, and excellent release adhesion strength can be obtained. Also, the photocurable composition is easily molded into a sheet shape. Note that, the above-described tensile elongation is a value measured according to ISO 37:2017.

[0043] As the triblock copolymer of component (A), a triblock copolymer of X-Y-Z type (structure having three kinds of units different from each other) composed of segment X, segment Y and segment Z, a triblock copolymer of X-Y-X type (structure in which one kind of unit is sandwiched by two kinds of the same units) composed of segment X and segment Y, and the like can be used. Further, each of the segments described above can be composed of a single monomer or two or more kinds of monomers. As a method for producing such a triblock copolymer, there is no particular limitation, and a method in which publicly known (meth)acrylate monomers constituting each segment (block) are subjected to living polymerization can be cited. As the method for living polymerization, a method in which anionic polymerization is performed using an organic alkali metal compound as a polymerization initiator, a method in which polymerization is performed using an organic rare earth metal complex as a polymerization initiator, and the like can be cited. Further, by using a polyvalent radical polymerization initiator, a polyvalent radical chain transfer agent, the publicly known (meth)acrylate monomers constituting each segment (block) can be polymerized.

[0044] Among them, the triblock copolymer of component (A) is preferably of X-Y-X type. By using component (A) having such a structure, the peel adhesion strength at normal temperature and at high temperature environment is further improved, and the transparency is good due to good compatibility with component (B) (which will be described in detail below).

[0045] Further, the triblock copolymer of component (A) is preferably a triblock copolymer of X-Y-X type or the like which contains a hard segment X having a high glass transition temperature and a soft segment Y having a low glass transition temperature. Here, the "glass transition temperature" refers to the glass transition temperature (Tg) of the polymer of the monomer constituting the segment. Further, in this specification, the value of the glass transition temperature (Tg) is the value of the midpoint glass transition temperature obtained by subjecting the polymer to thermal analysis at a temperature increase rate of 20°C / min and according to JIS K 7121:1987.

[0046] The glass transition temperature of the segment X described above is preferably 80 to 250°C, more preferably 90 to 200°C, and particularly preferably 100 to 150°C. If the glass transition temperature of the segment X is in the range described above, the adhesion at the time of curing is excellent.

[0047] The glass transition temperature of the segment Y described above is preferably -150 to 0°C, more preferably -100 to -15°C, and particularly preferably -70 to -30°C. If the glass transition temperature of the segment Y is in the range described above, the peel adhesion strength to a resin base material for which the adhesion to a PET film or the like is difficult to improve is further improved at normal temperature and at high temperature environment.

[0048] The component (A) is preferably a tri-block copolymer of (meth)acrylate of X-Y-X type composed of a segment X having a glass transition temperature of 100 to 150°C and a segment Y having a glass transition temperature of -70 to -30°C. Further, the component (A) is preferably a tri-block copolymer of (meth)acrylate of X-Y-X type composed of a segment X and a segment Y each having a glass transition temperature within the above-mentioned preferable ranges. By using such a tri-block copolymer, the desired peel adhesion strength is further improved.

[0049] The monomer constituting the segment X is preferably a methacrylate having a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a methacrylate having a linear or branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl methacrylate. That is, the component (A) is preferably a tri-block copolymer composed of a PMMA (poly(methyl methacrylate)) block and a block other than PMMA. By using a tri-block copolymer having such a structure, the desired peel adhesion strength is further improved.

[0050] Further, the monomer constituting the segment Y is preferably an acrylate having a linear or branched alkyl group having 1 to 20 carbon atoms, more preferably an acrylate having a linear or branched alkyl group having 2 to 15 carbon atoms, further more preferably an acrylate having a linear or branched alkyl group having 3 to 8 carbon atoms, and particularly preferably a n-butyl acrylate. That is, the component (A) preferably contains a PnBA (poly(n-butyl acrylate)) block. By using a tri-block copolymer having such a structure, the desired peel adhesion strength is further improved.

[0051] According to a preferable embodiment of the present application, the segment X of the component (A) is preferably a polymer of a methacrylate having an alkyl group having 1 to 3 carbon atoms, and the segment Y is preferably a polymer of an acrylate having an alkyl group having 3 to 8 carbon atoms. By using a tri-block copolymer having such a structure, the desired peel adhesion strength is further improved. Further, more preferably, the component (A) is a tri-block copolymer of (meth)acrylate of X-Y-X type in which the segment X is a PMMA block and the segment Y is a PnBA block.

[0052] In the (A) component, the content ratio of the segment X, when the entire triblock copolymer is taken as 100% by mass, is preferably 5% by mass or more, more preferably 15% by mass or more, and particularly preferably 25% by mass or more. On the other hand, the upper limit thereof is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 45% by mass or less. Also at this time, the segment X is preferably a PMMA block. By such a configuration, the tensile elongation of the (A) component easily reaches 100% or more, and thus the flexibility of the sheet-like photocurable composition is improved. As a result, since the sheet-like photocurable composition easily follows a concave-convex surface or a curved surface, and the like, excellent adhesion can be exerted to surfaces of various shapes.

[0053] On the other hand, in the above (A) component, the content ratio of the segment Y, when the entire triblock copolymer is taken as 100% by mass, is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 55% by mass or more. On the other hand, the upper limit thereof is preferably 95% by mass or less, more preferably 85% by mass or less, and particularly preferably 75% by mass or less. If the content ratio of each segment is within the above range, the desired peel adhesion strength is further improved.

[0054] Further, in the (A) component, when the entire triblock copolymer is taken as 100% by mass, the content ratio of the segment X is preferably 5 to 60% by mass, and the content ratio of the segment Y is preferably 40 to 95% by mass. In this mode, the content ratios of the segment X and the segment Y are further preferably each one of the above preferable ranges.

[0055] The weight average molecular weight (Mw) of the (A) component is not particularly limited, and is preferably 10,000 to 500,000, more preferably 30,000 to 200,000, further more preferably 40,000 to 150,000, and particularly preferably 50,000 to 100,000. When the weight average molecular weight is 10,000 or more, the curability is further improved. In addition, when the weight average molecular weight is 500,000 or less, the viscosity is lower, and the fusion property at the interface at the time of adhesion to an adherend is further improved, and as a result, the desired peel adhesion strength is further improved. In the present specification, the weight average molecular weight is a polystyrene-converted weight average molecular weight measured by GPC (gel permeation chromatography).

[0056] As the (A) component, either a synthetic product or a commercially available product can be used.

[0057] As specific examples of the commercially available product of the (A) component, there can be mentioned Kurarity (registered trademark, the same applies hereinafter) LA series by Kuraray Co., Ltd. using methyl methacrylate and n-butyl acrylate, Kurarity LK series using methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate, and the like. As specific examples thereof, there can be mentioned Kurarity LA2270, LA2250, LA2140, LA2330, LA3320, and the like by Kuraray Co., Ltd., but are not limited to these.

[0058] The (A) component can be used singly or in combination of two or more. In the case of using two or more in combination, the content of the (A) component refers to the total amount.

[0059] The content of the (A) component is not particularly limited, and is preferably 40 to 90 parts by mass, more preferably 50 to 80 parts by mass, and particularly preferably 60 to 70 parts by mass, relative to 100 parts by mass of the total of the (A) to (D) components. By making the content of the (A) component within the above range, the desired peel adhesion strength is further improved.

[0060] In addition, the content of the (A) component is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, and particularly preferably 60 to 70% by mass, relative to the total mass of the sheet-shaped photocurable composition (in the state after removing volatile components such as a solvent).

[0061] <(B) component>

[0062] The (B) component contained in the sheet-shaped photocurable composition of the present application is a (meth)acrylate oligomer (excluding the above (A) component). The (meth)acrylate oligomer refers to an oligomer having one or more (meth)acryloyl groups. In addition, "oligomer" refers to a polymer in which monomer units (including monomer units other than (meth)acrylate monomer units) are repeated two to several tens of times. Note that a polymer having three segments (blocks) composed of constitutional units from (meth)acrylate monomers is included in the (A) component and is not included in the (B) component.

[0063] The (B) component preferably has two to five (meth)acryloyl groups per one molecule (2- to 5-functional (meth)acrylate oligomer), and more preferably has two (meth)acrylate oligomers. In addition, the (meth)acryloyl group contained in the (B) component is preferably an acryloyl group.

[0064] The weight average molecular weight of the component (B) is preferably from 1,000 to 50,000, more preferably from 1,000 to 30,000, further more preferably from 3,000 to 10,000, and particularly preferably 4,000 or more and less than 10,000. When the weight average molecular weight is 1,000 or more, the curability is good, and when the weight average molecular weight is 50,000 or less, the viscosity is lower, and the fusion at the interface when adhering to an adherend is good, and as a result, the desired peel adhesion strength is improved.

[0065] Further, the glass transition temperature of the component (B) is preferably -100°C or more and 25°C or less, more preferably -100°C or more and 0°C or less, and particularly preferably -30°C or less. By setting the glass transition temperature of the component (B) within the above range, the improvement of the peel adhesion strength is facilitated. On the other hand, the lower limit is not particularly limited.

[0066] As the component (B), an epoxy-modified (meth)acrylate oligomer, a urethane-modified (meth)acrylate oligomer, an oligomer having a main skeleton in which a (meth)acrylic monomer is polymerized and having a (meth)acryloyl group at the terminal of the main skeleton, and the like can be exemplified. Among these, from the viewpoint of good adhesion to glass and plastic used in a protective panel, the component (B) is preferably a urethane-modified (meth)acrylate oligomer.

[0067] As the epoxy-modified (meth)acrylate oligomer, an epoxy-modified (meth)acrylate oligomer in which a (meth)acrylic acid is added to a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a linear phenol novolak, and the like can be exemplified, but is not limited to these.

[0068] In the present specification, the urethane-modified (meth)acrylate oligomer refers to an oligomer having one or more urethane bonds and one or more (meth)acryloyl groups. As for the urethane-modified (meth)acrylate oligomer, the preferred number of (meth)acryloyl groups contained per one molecule and the weight average molecular weight are the same as described above with respect to the (meth)acrylate oligomer.

[0069] As the component (B), any one of a synthetic product and a commercially available product can be used. The urethane-modified (meth)acrylate oligomer, which is a preferred form of the component (B), is synthesized, for example, by the reaction of a polyol compound (main skeleton) having two or more hydroxyl groups in the molecule, a compound having two or more isocyanate groups in the molecule, and a (meth)acrylate having one or more hydroxyl groups in the molecule.

[0070] As the polyol compound having 2 or more hydroxyl groups in the molecule, there are, for example, polyether polyol, polyester polyol, caprolactone diol, bisphenol polyol, polyisoprene polyol, hydrogenated polyisoprene polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, castor oil polyol, polycarbonate diol, and the like. Among them, from the viewpoint of excellent transparency and excellent durability, polycarbonate diol, polybutadiene polyol, hydrogenated polybutadiene polyol are preferred, and from the viewpoint that the cured product is less likely to be whitened under a high-temperature high-humidity atmosphere, polycarbonate diol is particularly preferred. These can be used alone or in combination of a plurality of kinds.

[0071] As the compound having 2 or more isocyanate groups in the molecule, there are, for example, aromatic polyisocyanate, alicyclic polyisocyanate, aliphatic polyisocyanate, and the like. Among them, from the viewpoint of obtaining a cured product having flexibility, aliphatic polyisocyanate and alicyclic polyisocyanate are preferred. These can be used alone or in combination of a plurality of kinds. From the viewpoint of improving the desired peel adhesion, the component (B) is preferably an aliphatic urethane-modified (meth) acrylate oligomer synthesized using aliphatic polyisocyanate.

[0072] As the aromatic polyisocyanate, there are, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, triphenylmethane triisocyanate, and the like. As the alicyclic polyisocyanate, there are, for example, isophorone diisocyanate, bis(4-isocyanatocyclohexyl)methane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, norbornane diisocyanate, bicycloheptane triisocyanate, and the like. As the aliphatic polyisocyanate, there are, for example, hexamethylene diisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, and the like. Among them, alicyclic or aliphatic diisocyanate such as isophorone diisocyanate and hexamethylene diisocyanate is preferred, and aliphatic diisocyanate is particularly preferred.

[0073] As the (meth) acrylate having 1 or more hydroxyl groups in the molecule, there are, for example, mono(meth) acrylates of dihydric alcohol such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, polyethylene glycol, and the like; mono(meth) acrylates or di(meth) acrylates of trihydric alcohol such as trimethylol ethane, trimethylol propane, glycerol, and the like; and the like. Among them, from the viewpoint of obtaining a cured product having excellent flexibility, mono(meth) acrylates of dihydric alcohol are preferred, and mono(meth) acrylates of ethylene glycol are more preferred. These can be used alone or in combination of a plurality of kinds.

[0074] The method for synthesizing the urethane-modified (meth)acrylate oligomer is not particularly limited, and a publicly known method can be used. The urethane-modified (meth)acrylate oligomer can be synthesized, for example, by a reaction using each of the above compounds as a raw material, and more specifically, by the following method.

[0075] The polyol compound having two or more hydroxyl groups in a molecule is reacted with the isocyanate compound having two or more isocyanate groups in a molecule, preferably at a molar ratio (polyol compound: isocyanate compound) of 3:1 to 1:3, more preferably at a molar ratio of 2:1 to 1:2, in a diluent (e.g., methyl ethyl ketone, methoxyphenol, or the like) to obtain a urethane prepolymer. Subsequently, the urethane-modified (meth)acrylate oligomer can be synthesized by further reacting the isocyanate groups remaining in the obtained urethane prepolymer with a sufficient amount of the (meth)acrylate compound containing one or more hydroxyl groups in a molecule.

[0076] As the catalyst used at the time of synthesis, for example, lead oleate, tetrabutyl tin, antimony trichloride, triphenyl aluminum, trioctyl aluminum, dibutyl tin dilaurate, copper naphthenate, zinc naphthenate, zinc octoate, zinc octenylate, zirconium naphthenate, cobalt naphthenate, tetra-n-butyl-1,3-diacyloxyditinooxane, triethylamine, 1,4-diazabicyclo[2,2,2]octane, N-ethylmorpholine, and the like can be given. Among them, from the viewpoint of obtaining a cured product having high activity and excellent transparency, dibutyl tin dilaurate, zinc naphthenate, zinc octoate, and zinc octenylate are preferably used. The amount of these catalysts is preferably 0.0001 to 10 parts by mass based on 100 parts by mass of the total amount of the reaction product. In addition, the reaction temperature is usually 10 to 100°C, and particularly preferably 30 to 90°C. The urethane-modified (meth)acrylate oligomer can be used as one that is diluted with a solvent or the monomer having a (meth)acryloyl group described later at the stage of a raw material.

[0077] As specific examples of the commercially available product of the (B) component, UN-1255, UN-9200A, UN-9000PEP, and the like of Konishi Industry Co., Ltd., U-200PA, UA-160TM, and the like of Shin Nakamura Chemical Industrial Co., Ltd., Irgacure® series UV-3000B, UV-3700B, and the like of Mitsubishi Chemical Corporation, TEAI-1000 of Japan Zeon Co., Ltd., EBECRYL (registered trademark) series 230, 270, 4858, 8402, 8804, 8807, 9270, 4513, 8311, 9260, 8701, 4265, 4587, 8210, 1290, 5129, 8310R, 210, 220, and the like of Daicel-allnex Co., Ltd. can be given, but are not limited to these.

[0078] The (B) component can be used singly or in combination of two or more. In the case of combination of two or more, the content of the (B) component refers to the total amount.

[0079] The content of the (B) component is not particularly limited, and is preferably 10 to 80 parts by mass, more preferably 20 to 60 parts by mass, and particularly preferably 30 to 50 parts by mass, relative to 100 parts by mass of the (A) component. If the content of the (B) component is 10 parts by mass or more relative to 100 parts by mass of the (A) component, the peel adhesion strength can be improved in both normal temperature and high temperature environments (under 25°C atmosphere and under 85°C atmosphere), and on the other hand, if the content of the (B) component is 80 parts by mass or less, the flow start temperature at the time of lamination can be lowered, and thermal damage to the adherend can be reduced.

[0080] <(C) component>

[0081] The (C) component contained in the sheet-shaped photocurable composition of the present application is a compound represented by the following Formula 1. The compound represented by the following Formula 1 is a monomer having a (meth)acryloyl group, and is a (meth)acrylamide monomer. By containing such a (C) component, the sheet-shaped photocurable composition of the present application has excellent adhesion to a resin substrate, although it contains a triblock copolymer of a (meth)acrylate ((A) component).

[0082]

[0083] In Formula 1, R 1 is a hydrogen atom or a methyl group, and R 2 is a monovalent organic group containing an oxygen atom. As specific examples of the monovalent organic group containing an oxygen atom, there are monovalent organic groups having a hydroxyl group and / or an ether bond, but the present application is not limited thereto. R 2 When the ether bond is contained, the ether bond is preferably contained in the form of an alkoxy group. That is, R 2 preferably contains a hydroxyl group and / or an alkoxy group.

[0084] From the viewpoint of promoting curing by light irradiation, R 1 in the above Formula 1 is preferably a hydrogen atom. That is, the (C) component is preferably an acrylamide compound. In a more preferable embodiment, as the compound of the (C) component, R 1 in the above Formula 1 is a hydrogen atom, and R 2 contains a hydroxyl group and / or an ether bond. In this case, R 2 more preferably contains a hydroxyl group and / or an alkoxy group.

[0085] Further, R 2 in Formula 1 is preferably a monovalent organic group represented by the following Formula 2.

[0086] * -R' -OA Formula 2

[0087] In Formula 2, R' is a linear or branched alkylene group having 1 to 5 carbon atoms, A is a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and "*" is a bonding point with the nitrogen atom in Formula 1.

[0088] Examples of the linear or branched alkylene group having 1 to 5 carbon atoms for R' include methylene, ethylene, trimethylene, propylene, n-butylene, 1-methylpropylene, 2-methylpropylene, dimethyl ethylene, and ethyl ethylene.

[0089] Examples of the linear or branched alkyl group having 1 to 5 carbon atoms for A include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, amyl, isoamyl, t-amyl, and neopentyl.

[0090] More preferably, the (C) component is a compound in which R 1 is a hydrogen atom, R 2 is a monovalent organic group represented by Formula 2 described above, R' in Formula 2 is a linear or branched alkylene group having 1 to 3 carbon atoms, and A is a hydrogen atom or a linear alkyl group having 2 to 5 carbon atoms. In the above-mentioned mode, A is particularly preferably a hydrogen atom.

[0091] Specific examples of the (C) component include hydroxyethyl (meth) acrylamide and N-n-butoxy methyl (meth) acrylamide. These can be used alone or in combination.

[0092] Specific examples of commercially available products of the (C) component include HEAA (registered trademark) by KJ Chemicals Co., Ltd. and NBMA by Shin-Nippon Rika Co., Ltd., but are not limited to these.

[0093] The (C) component can be used alone or in combination with two or more. In the case of using two or more in combination, the content of the (C) component refers to the total amount.

[0094] The content of the (C) component is not particularly limited, and is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 10 parts by mass, further more preferably 1 to 9 parts by mass, particularly preferably 3 to 8 parts by mass, and most preferably 5 to 8 parts by mass, relative to 100 parts by mass of the (A) component. When the content of the (C) component is 0.1 parts by mass or more relative to 100 parts by mass of the (A) component, the adhesion is further improved, and the peel adhesion strength to a resin substrate such as a (meth) acryl resin plate, a TAC film, and a PET film is further improved. On the other hand, if the content of the (C) component is 30 parts by mass or less, the flow start temperature can be reduced, and the thermal damage to the adherend can be reduced.

[0095] In addition, the content of the (C) component is preferably 1 to 50 parts by mass, more preferably 5 to 30 parts by mass, further more preferably 10 to 20 parts by mass, and particularly preferably 12 to 18 parts by mass, relative to 100 parts by mass of the (A) component. When the content of the (C) component is 1 part by mass or more relative to 100 parts by mass of the (A) component, the adhesion is further improved, and the peel adhesion to the aforementioned resin substrate can be further improved. On the other hand, when the content of the (C) component is 50 parts by mass or less, the flow start temperature can be reduced, and thermal damage to the adherend can be reduced.

[0096] <(D) component>

[0097] The (D) component contained in the sheet-shaped photocurable composition of the present application is a photoinitiator (photopolymerization initiator). The photoinitiator refers to a compound that is decomposed by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and the like, and generates radical species, cationic species, or anionic species.

[0098] As the (D) component, a benzophenone-based photoinitiator, a benzoin-based photoinitiator, a benzoin ether-based photoinitiator, a thioxanthone-based photoinitiator, an acyloxyphosphine-based photoinitiator, and the like can be exemplified. These can be used alone or in combination of two or more. Among them, the (D) component preferably contains an acyloxyphosphine-based photoinitiator. A composition containing an acyloxyphosphine photoinitiator is sometimes yellow as it is, but is easily cured by active energy rays in the visible region, and the photocurability is improved.

[0099] As the benzophenone-based photoinitiator, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzil dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]propanone oligomer, and the like can be exemplified, but are not limited thereto.

[0100] As the benzoin-based photoinitiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and the like can be exemplified, but are not limited thereto.

[0101] As the benzophenone-based photoinitiator, benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl diphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(l-oxo-2-propenyl oxy)ethyl]phenyl tetramethyl ammonium bromide, (4-benzoylbenzyl)trimethylammonium chloride, and the like can be given, but are not limited thereto.

[0102] As the thioxanthone-based photoinitiator, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-ketomethochloride, and the like can be given, but are not limited thereto.

[0103] As the acylphosphine oxide-based photoinitiator, for example, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4,6-trimethylbenzoyl-phenyl ethoxy-phosphine oxide, and the like can be given, but are not limited thereto.

[0104] As a specific example of the commercially available product of the (D) component, Omnirad (registered trademark) series TPO and the like by IGM Resins B.V. can be given, but are not limited thereto.

[0105] The (D) component can be used singly in one kind, or two or more kinds can be used in mixture. In the case of using two or more kinds in mixture, the content of the (D) component refers to the total amount.

[0106] The content (addition amount) of the (D) component is not particularly limited, and is preferably 0.1 to 5.0 parts by mass, more preferably 0.1 to 3.0 parts by mass, and particularly preferably 0.3 to 1.0 parts by mass, relative to 100 parts by mass of the (A) component. When the content of the (D) component is 0.1 parts by mass or more relative to 100 parts by mass of the (A) component, a photocurable composition having excellent photocurability can be obtained, and when it is 5.0 parts by mass or less, coloring of the cured product can be effectively prevented.

[0107] In addition, the content (addition amount) of the (D) component is preferably 0.1 to 5.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, relative to 100 parts by mass of the (B) component. In another preferred mode, the content (addition amount) of the (D) component is 0.1 to 1.0 parts by mass relative to 100 parts by mass of the (B) component. When the content of the (D) component is 0.1 parts by mass or more relative to 100 parts by mass of the (B) component, a photocurable composition having excellent photocurability can be obtained, and when it is 5.0 parts by mass or less, coloring of the cured product can be effectively prevented.

[0108] <(E) component>

[0109] The sheet-shaped photocurable composition of the present application preferably further contains a coupling agent as the (E) component in addition to the above-mentioned (A) to (D) components from the viewpoint of improving the adhesion at the interface.

[0110] As the (E) component which can be contained in the sheet-shaped photocurable composition of the present application, a silane coupling agent having an alkoxysilyl group is preferred.

[0111] As specific examples of the silane coupling agent having an alkoxysilyl group, there can be mentioned 2-(3, 4-epoxycyclohexyl)ethyl trimethoxysilane, 3- glycidyloxypropyl triethoxysilane, 3-glycidyloxypropyl methyldimethoxysilane, 3- glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl methyldiethoxysilane and the like glycidyl-containing silane coupling agents; vinyl tri (β-methoxyethoxy) silane, vinyl triethoxysilane, vinyl trimethoxysilane and the like vinyl-containing silane coupling agents; 3- methacryloyloxypropyl trimethoxysilane (γ-methacryloyloxypropyl trimethoxysilane) and the like (meth)acryl-containing silane coupling agents; N-β-(aminoethyl)-γ- aminopropyl trimethoxysilane, γ-aminopropyl triethoxysilane, N-phenyl-γ- aminopropyl trimethoxysilane and the like amino-containing silane coupling agents; other γ-mercaptopropyl trimethoxysilane, γ-chloropropyl trimethoxysilane and the like. These can be used alone or in combination of two or more. Among them, from the viewpoint of further improving the adhesion to the resin substrate, a silane coupling agent containing an epoxy group (glycidyl group) or a (meth)acryl group in addition to the alkoxysilyl group is preferred, and a silane coupling agent containing a methacryl group is most preferred.

[0112] The (E) component can be used alone or in combination of two or more. In the case of using two or more in combination, the content of the (E) component refers to the total amount.

[0113] The content (addition amount) of the (E) component is not particularly limited, and it is preferably 0.05 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and particularly preferably 0.8 to 5 parts by mass, relative to 100 parts by mass of the (A) component. When the content of the (E) component is 0.05 parts by mass or more relative to 100 parts by mass of the (A) component, it is helpful for further improving the peeling adhesion strength, and when it is 15 parts by mass or less, the effect of reducing the outgassing can be obtained.

[0114] Further, the amount of the (E) component is preferably 0.1 to 20 parts by mass, more preferably 3 to 15 parts by mass, relative to 100 parts by mass of the (B) component. When the content of the (E) component is 0.1 parts by mass or more relative to 100 parts by mass of the (B) component, the peel adhesion strength is further improved, and when the content is 20 parts by mass or less, the effect of reducing the emission of gas is obtained.

[0115] <Optional Component>

[0116] The sheet-shaped photocurable composition of the present application can further contain, within the range not impairing the object of the present application, a solvent, a monomer having a (meth)acryloyl group other than the above-mentioned (C) component, a filler such as an inorganic filler and an organic filler, a storage stabilizer, an antioxidant, a light stabilizer, a UV absorber, a plasticizer, a dye, a pigment, a flame retardant, a sensitizer, a thermal initiator, a heavy metal deactivator, an ion scavenger, an emulsifier, a water dispersion stabilizer, an antifoaming agent, a mold release agent, a leveling agent, a wax, a rheology control agent, a surfactant, and the like.

[0117] (Monomer having a (meth)acryloyl group other than the (C) component)

[0118] As the monomer having a (meth)acryloyl group other than the above-mentioned (C) component, a monofunctional monomer, a bifunctional monomer, a trifunctional monomer, a tetrafunctional monomer or higher polyfunctional monomer can be mentioned. A (meth)acrylate monomer is preferred, and a monofunctional or bifunctional (meth)acrylate monomer is particularly preferred. In order to reduce the viscosity of the photocurable composition, the molecular weight of the monomer having a (meth)acryloyl group other than the (C) component is preferably 1000 or less. The molecular weight of such a compound (low molecular weight compound) can be measured by a known method such as gas chromatography-mass spectrometry (GC-MS) method.

[0119] As the monofunctional monomer, (meth)acrylic acid lauryl ester, (meth)acrylic acid stearyl ester, (meth)acrylic acid tetrahydrofurfuryl ester, caprolactone-modified (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid cyclohexyl ester, dicyclopentene (meth)acrylate, (meth)acrylic acid isobornyl ester, (meth)acrylic acid benzyl ester, (meth)acrylic acid phenyl ester, (meth)acrylic acid phenoxyethyl ester, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, (meth)acrylic acid nonylphenoxyethyl ester, (meth)acrylic acid butoxyethyl ester, (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid glyceryl ester, modified (meth)acrylic acid butyl ester, epichlorohydrin-modified phenoxy (meth)acrylate, (meth)acrylic acid N,N-dimethylaminoethyl ester, (meth)acrylic acid N,N-diethylaminoethyl ester, morpholine (meth)acrylate, and the like can be mentioned.

[0120] As the difunctional monomer, for example, neopentyl glycol di(meth)acrylate, bisphenol A di(meth)acrylate, epichlorohydrin-modified bisphenol A di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, di(meth)acryloyl isocyanurate, and the like can be exemplified.

[0121] As the trifunctional monomer, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, epichlorohydrin-modified trimethylolpropane tri(meth)acrylate, epichlorohydrin-modified glycerol tri(meth)acrylate, tri(acryloyloxyethyl) isocyanurate, and the like can be exemplified.

[0122] As the polyfunctional monomer, for example, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, alkyl-modified dipentaerythritol pentaacrylate, dipentaerythritol hexa(meth)acrylate, and the like can be exemplified. These polymerizable monomers can be used alone or in combination of two or more.

[0123] In another preferred mode, the monomer having a (meth)acryloyl group other than the (C) component is a (meth)acrylate having one or more ether bonds and one or more (meth)acryloyl groups. As the (meth)acrylate, a polyether monomer (polyether (meth)acrylate) having a repeating structure of 8 to 30 ether bonds in one molecule is preferred. When the repeating structure of the ether bond is 8 or more, the white turbidity caused by separation between the polyether monomer and moisture from the outside that permeates into the interior of the cured product under a high-temperature high-humidity atmosphere is further inhibited. On the other hand, the polyether monomer having a repeating structure of 30 or less ether bonds is difficult to crystallize between the monomers, and the white turbidity of the cured product is further inhibited. These can be used alone or in combination of a plurality of kinds.

[0124] As the (meth)acrylate having an ether bond and a (meth)acryloyl group (polyether (meth)acrylate), for example, polyethylene glycol mono(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol mono(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetrahydrofuran mono(meth)acrylate, polytetrahydrofuran di(meth)acrylate, and the like can be exemplified.

[0125] The molecular weight of the above polyether (meth)acrylate is preferably in the range of 200 to 5000, and more preferably 250 to 3000.

[0126] As specific examples of commercially available products of the above polyether (meth) acrylate, for example, M-90G, AM-130G, M-230G, A-400, A-600, APG-700, A-1000, 9G, 14G, 23G, 1206PE, etc. of Shin-Nakamura Chemical Co., Ltd., PDE-600, PDP-700, ADE-600, etc. of NOF Corporation, Light ester series 130MA, 130A, 14EG, 14EG-A, etc. of Kyoei Chemical Co., Ltd. can be given, but are not limited thereto.

[0127] (Inorganic filler)

[0128] As specific examples of the inorganic filler, glass powder, fumed silica powder, silica powder, alumina powder, mica powder, silicone rubber powder, calcium carbonate powder, aluminum nitride powder, carbon powder, kaolin clay powder, dry clay mineral powder, dry diatomaceous earth powder, metal powder, etc. can be given. In addition, as the fumed silica powder, fumed silica powder obtained by chemically modifying (hydrophobizing) the surface with organochlorosilane, polyorganosiloxane, hexamethyldisilazane, etc. can be given, but are not limited thereto. As specific examples of commercially available products of the inorganic filler, for example, AEROSIL (registered trademark) series R974, R972, R972V, R972CF, R805, R812, R812S, R816, R8200, RY200, RX200, RY200S, R202, etc. of Nippon AEROSIL Co., Ltd. can be given. In order to improve flowability, etc. and increase the mechanical strength of the cured product, the content (amount of blending) of the inorganic filler is preferably about 0.1 to 100 parts by mass with respect to 100 parts by mass of the total of the above (A) to (D) components.

[0129] (Ultraviolet absorber)

[0130] Examples of ultraviolet absorbers include, but are not limited to, 2-(5-chloro-2-benzotriazolyl)-6-tert-butyl-p-cresol, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)benzotriazole, tetra(1,2,2,6,6-pentamethylpiperidin-4-yl)butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate. Specific examples of commercially available ultraviolet absorbers include ADEKA's Adekastab (registered trademark) LA-52, LA-57, LA-63P, LA-68, LA-72, LA-77Y, and LA-77G, as well as JF-90 and JF-95 manufactured by Seongbuk Chemical Industry Co., Ltd., but are not limited to these.

[0131] <Flow start temperature>

[0132] The sheet-like photocurable composition of the present invention preferably has a temperature of 60 to 120°C before curing when tanδ = 1. By keeping this temperature within the above range, the photocurable composition can be easily processed into a film and can be easily laminated at room temperature. Furthermore, the temperature at which tanδ = 1 can be measured using a rheometer. tanδ is calculated from the storage modulus (G') and the loss modulus (G"), and has the relationship tanδ = G" / G'. "tanδ = 1" refers to the temperature at the interface between the solid and liquid.

[0133] <Energy Storage Elastic Modulus>

[0134] Furthermore, the sheet-like photocurable composition of the present invention, after curing, preferably has a storage modulus of 0.1 × 10⁻⁶ at 25°C. 7 ~10.0×10 7 Pa, more preferably 0.1 × 10 Pa 7 ~5.0×10 7 Pa. The above-mentioned energy storage elastic modulus can be measured at various frequencies using DMA (Dynamic Viscoelasticity Measurement). For example, the value at a frequency of 1 Hz can be given.

[0135] [Photocurable composition solution]

[0136] In this invention, in order to process the photocurable composition in its uncured state before curing by light irradiation into a sheet shape, a solvent may also be used to mix the components contained in the aforementioned sheet-shaped photocurable composition. That is, another aspect of this invention is a photocurable composition solution comprising the following components (A) to (D) and a solvent:

[0137] (A) component: (meth)acrylic tri-block copolymer

[0138] (B) component: (meth)acrylate oligomer, wherein the (A) component is excluded

[0139] (C) component: compound represented by the above formula 1

[0140] (D) component: photoinitiator

[0141] <solvent>

[0142] As the solvent, there can be mentioned alcohols such as methanol and ethanol; chlorine-based solvents such as dichloroethane and trichloroethane; fluorine-based solvents such as trichlorofluoroethane; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ethers such as dimethyl ether and methyl ethyl ether; hydrocarbon-based solvents such as pentane, hexane, heptane, and cyclohexane; aromatic solvents such as benzene, toluene, and xylene; and the like. Among these, in view of the compatibility with the (A) to (C) components, a ketone-based solvent is preferred.

[0143] The content of the solvent contained in the photocurable composition solution is not particularly limited, and is preferably 30 to 200 parts by mass, more preferably 50 to 100 parts by mass, relative to 100 parts by mass of the total mass of the (A) to (D) components. If it is within this range, it is easier to produce a film thickness of 300 μm or less, further 200 μm or less, when the photocurable composition is molded into a sheet shape.

[0144] [Method for producing photocurable composition solution / sheet-shaped photocurable composition]

[0145] [Method for producing photocurable composition solution]

[0146] The method for producing the photocurable composition solution of the present application is not particularly limited, and each of the components and the solvent can be mixed by a publicly known mixing method. The order of addition of the components is not particularly limited, but it is preferred that the (A) component and the solvent are first added to a stirring tank and stirred, and then the other components are added and stirred. At this time, in the case where the solvent is volatilized in the mixing, it is preferred that the volatilized portion of the solvent is supplemented. The production conditions are not particularly limited, but in view of the purpose of inhibiting the viscosity from becoming high, it is preferred that the production is performed under light-shielded conditions. Further, the mixing conditions are not particularly limited, and the mixing temperature is preferably 10 to 70°C, more preferably 20 to 50°C, particularly preferably room temperature (25°C), and the mixing time (total time in the case where it is performed in two stages) is preferably 0.1 to 5 hours, more preferably 30 minutes to 3 hours.

[0147] [Method for producing sheet-shaped photocurable composition]

[0148] As a method of processing the photocurable composition into a sheet shape (a method of producing a sheet-shaped photocurable composition), a publicly known technique can be used. For example, a method in which a solvent is added to each component contained in the photocurable composition to intentionally prepare a raw solution (photocurable composition solution) having a reduced viscosity, the raw solution is coated on a release paper or a release film (hereinafter also referred to as "release film or the like") on which a release treatment has been performed in advance (coating step), and the solvent is dried (drying step) to process into a sheet shape can be exemplified. Thereby, a photocurable composition in a sheet shape at 25°C in a state before curing is obtained. That is, another aspect of the present application is a method of producing a photocurable composition, which is a method of producing a photocurable composition in a sheet shape at 25°C in a state before curing, including volatilizing a solvent contained in the above-mentioned photocurable composition solution. At this time, volatilization of the solvent on a release paper or a release film is preferable.

[0149] As the coating step, a publicly known coating method can be used, and as specific examples, a flow coating method, a roll coating method, a gravure roll coating method, a wire bar coating method, a lip die coating method, and the like can be exemplified, but are not limited thereto. The thickness (film thickness) of the raw solution (photocurable composition solution) at the time of coating is not particularly limited, and is preferably 50 to 300 μm.

[0150] In addition, as the drying step, a publicly known drying method can be used. As a drying device used at this time, there is no particular limitation, and for example, a hot air drying oven or an IR oven, and the like can be exemplified. In addition, a conveyor for conveying the release film or the like in a state in which the raw solution is coated can be provided in the hot air drying oven.

[0151] The temperature of the drying step is not particularly limited, and is a temperature at which the solvent contained in the raw solution is sufficiently volatilized, and for example, is preferably 40 to 150°C, and more preferably 60 to 120°C. In addition, the drying time is not particularly limited, and for example, is preferably 1 to 20 minutes, and more preferably 3 to 10 minutes. Furthermore, the drying step can be performed in multiple stages by changing the drying temperature.

[0152] The sheet-shaped photocurable composition thus formed has a configuration in which the release film or the like is formed on the sheet-shaped photocurable composition (a configuration in which the release film or the like is attached to one surface of the sheet-shaped photocurable composition) as described above. In addition, the sheet-shaped photocurable composition can have the release film or the like attached to both surfaces. Furthermore, in the case where the release film or the like is not used at the time of coating, or in the case where a release film or the like other than the release film used at the time of coating is used, the release film or the like can be additionally attached to one surface or both surfaces of the sheet-shaped photocurable composition.

[0153] As the release paper, there is no particular limitation, and for example, a release paper obtained by providing a coating layer composed of a release agent such as clay, polyethylene, or polypropylene on at least one side of a paper such as high-quality paper, kraft paper, or glassine paper, and applying a release agent such as a silicone-based, fluorine-based, or alkyd-based release agent thereon can be mentioned.

[0154] As the material of the release film, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, cloth, nonwoven fabric, and the like can be mentioned. Among them, from the viewpoint of releasability, plastic films are preferred. The thickness of the release film is preferably 5 to 300 μm, and more preferably 25 to 200 μm. In addition, the release film is preferably a film subjected to release treatment using a fluorine-based compound, a silicone-based compound, a long-chain alkyl-based compound, or the like.

[0155] [Cured product and method for producing the same]

[0156] The sheet-shaped photocurable composition of the present application can be cured by irradiation of light (active energy rays such as ultraviolet rays, visible light, and the like). That is, another aspect of the present application is a cured product obtained by curing the above-described sheet-shaped photocurable composition. The light referred to here is light in a broad sense, and includes radioactive rays such as α-rays or β-rays, electromagnetic waves such as γ-rays or X-rays, electron beams (EB), and irradiation light having a wavelength of 150 to 750 nm. Among them, the irradiation light is preferably in the wavelength region of 150 to 750 nm, and preferably ultraviolet rays having a wavelength of about 150 to 400 nm or visible light having a wavelength of about 400 to 750 nm.

[0157] The light source used for curing the sheet-shaped photocurable composition is not particularly limited, and for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, xenon lamps, metal halide lamps, LED lamps, and the like can be mentioned. In addition, as the apparatus for curing the sheet-shaped photocurable composition of the present application by light irradiation (active energy ray irradiation), an irradiation apparatus having the above-described light source (high-pressure mercury lamp, LED lamp, and the like) can be used. As specific examples of the apparatus, a belt conveyor type irradiator, a point irradiator, and the like can be mentioned, but are not limited thereto.

[0158] The range of the cumulative light amount is not particularly limited, and preferably, the above-described light source is used to perform curing at a cumulative light amount of 1 to 100 kJ / m 2 , more preferably 5 to 70 kJ / m 2 , and particularly preferably 10 to 50 kJ / m 2 .

[0159] [Stack]

[0160] As described above, by preparing a photocurable composition solution (stock solution) by adding a solvent to each component contained in the sheet-shaped photocurable composition of the present application, applying the stock solution to an adherend, and then allowing the solvent to evaporate (disperse), a laminate of the sheet-shaped photocurable composition and the adherend at 25°C can be formed. That is, another embodiment of the present application is a laminate having a configuration in which a first adherend, a sheet-shaped photocurable composition, and a second adherend are sequentially attached (laminated), wherein the sheet-shaped photocurable composition is formed by allowing the solvent contained in the photocurable composition solution to evaporate on the first adherend and / or the second adherend.

[0161] As a preferred embodiment of the method for manufacturing the laminate described above, a method in which, first, a photocurable composition solution (stock solution) is applied to a first adherend (or a second adherend), and then a sheet-shaped photocurable composition is formed by allowing the solvent contained in the stock solution to evaporate (dry), and then a second adherend (or a first adherend) is laminated on the sheet-shaped photocurable composition can be mentioned.

[0162] Further, by irradiating the sheet-shaped photocurable composition contained in the laminate thus obtained (a laminate having a configuration in which a first adherend, a sheet-shaped photocurable composition, and a second adherend are sequentially laminated) with active energy rays, the sheet-shaped photocurable composition is cured, whereby the first adherend and the second adherend can be bonded. Thus, another embodiment of the present application is a bonding method including a step of applying a photocurable composition solution (stock solution) to a first adherend, a step of allowing the solvent contained in the stock solution to evaporate (dry) to form a sheet-shaped photocurable composition, a step of laminating a second adherend on the sheet-shaped photocurable composition, and a step of curing the sheet-shaped photocurable composition by irradiating the sheet-shaped photocurable composition with active energy rays. Further, the drying conditions and the curing conditions at this time are not particularly limited, and are the same as the drying conditions described in the item of the method for manufacturing the sheet-shaped photocurable composition described above and the curing conditions described in the item of the cured product and the method for manufacturing the same described above, respectively.

[0163] Further, as described above, in a preferred embodiment of the sheet-shaped photocurable composition of the present application, the sheet-shaped photocurable composition can be obtained by allowing the solvent contained in the photocurable composition solution to evaporate on a release film or the like, and has a configuration in which a release film or the like is attached to one surface of the sheet-shaped photocurable composition.

[0164] Thus, another preferred embodiment of the method (bonding method) for bonding a first adherend and a second adherend together includes a step (bonding step) of bonding two transparent adherends using a sheet-shaped photocurable composition having a release film or the like attached to one surface thereof. The bonding step preferably includes a lamination step and a curing step.

[0165] In the lamination step, preferably, the face (exposed face) of the side of the sheet-like photocurable composition, from which the unattached release film is removed, is attached (bonded) to one adherend (first adherend) and a laminator is used while applying pressure and heat to attach. Then, the release film is peeled off and another adherend (second adherend) is attached using the laminator. In this case, the lamination pressure is not particularly limited, and for example, it is preferably 0.1 to 3 MPa. In addition, the lamination temperature is not particularly limited, and for example, it is preferably 15 to 100°C.

[0166] As the device used in the attachment, instead of the laminator, a vacuum press, a vacuum laminator, an autoclave, or the like capable of attaching in a vacuum or a reduced pressure atmosphere can also be used.

[0167] As the curing step, the sheet-like photocurable composition is cured by irradiating the laminated body (laminated body composed of the first adherend - sheet-like photocurable composition - second adherend) after the lamination with active energy rays, whereby the two adherends can be bonded. In addition, the curing conditions at this time are not particularly limited and are the same as the conditions described in the above [cured product and method for producing the same] item.

[0168] [Use]

[0169] The sheet-like photocurable composition of the present application can be used for the assembly of display devices such as liquid crystal displays or organic EL displays. Specifically, it is suitable for the assembly of display elements, cover plates, touch panels, and the like to display devices, the assembly of organic EL elements themselves.

[0170] Although the embodiments of the present application have been described in detail, it should be understood that the scope of the present application is to be interpreted only by the appended claims, and not by the description, which is illustrative and exemplary, since it is illustrative and exemplary.

[0171] The present application includes the following aspects and embodiments.

[0172] 1. A sheet-like photocurable composition comprising the following (A) to (D) components, which is in a sheet shape at 25°C in a state before curing:

[0173] (A) component: (meth)acrylic triblock copolymer;

[0174] (B) component: (meth)acrylate oligomer, wherein the (A) component is excluded;

[0175] (C) component: compound represented by the following Formula 1

[0176]

[0177] In the Formula 1, R1is a hydrogen atom or a methyl group, and R2is a monovalent organic group containing an oxygen atom.

[0178] (D) Component: photoinitiator.

[0179] 2. The sheet-shaped photocurable composition according to the above 1, wherein 0.1 parts by mass to 10 parts by mass of the (C) component is contained with respect to 100 parts by mass of the (A) component.

[0180] 3. The sheet-shaped photocurable composition according to the above 1 or 2, wherein 10 parts by mass to 80 parts by mass of the (B) component is contained with respect to 100 parts by mass of the (A) component.

[0181] 4. The sheet-shaped photocurable composition according to any one of the above 1 to 3, wherein R 1 in the formula 1 is a hydrogen atom, and R 2 contains a hydroxyl group and / or an ether bond.

[0182] 5. The sheet-shaped photocurable composition according to any one of the above 1 to 4, wherein the (B) component is a urethane-modified (meth)acrylate oligomer.

[0183] 6. The sheet-shaped photocurable composition according to any one of the above 1 to 5, further comprising a coupling agent as an (E) component.

[0184] 7. A photocurable composition solution comprising the following (A) to (D) components and a solvent:

[0185] (A) Component: (meth)acrylic triblock copolymer;

[0186] (B) Component: (meth)acrylate oligomer, wherein the foregoing (A) component is excluded;

[0187] (C) Component: compound represented by the above formula 1;

[0188] (D) Component: photoinitiator.

[0189] 8. A production method of a sheet-shaped photocurable composition, which is a production method of a photocurable composition that is in a sheet shape at 25°C in a state before curing, comprising a step of volatilizing the solvent contained in the photocurable composition solution according to the above 7.

[0190] 9. The production method of a sheet-shaped photocurable composition according to the above 8, wherein the volatilization of the solvent is performed on a release paper or a release film.

[0191] 10. A laminate having a constitution in which a first adherend, a sheet-like photocurable composition, and a second adherend are sequentially attached, the sheet-like photocurable composition being formed by volatilization of the solvent contained in the photocurable composition solution described in the above item 7 on the first adherend and / or the second adherend.

[0192] [Examples]

[0193] The present application is explained in more detail by the following examples, but the present application is not limited to these examples. Hereinafter, the photocurable composition containing a solvent (i.e., the photocurable composition solution) is also simply referred to as "stock solution". In addition, the photocurable composition in a sheet shape at 25°C before curing, which is obtained by volatilizing the solvent from the "stock solution", is also simply referred to as "sheet-like composition". In addition, unless otherwise specified, operations, tests, and the like are performed in an environment of 25°C, 55% RH.

[0194] <Preparation of photocurable composition solution (stock solution)>

[0195] [Examples 1 to 13 and Comparative Examples 1 to 11]

[0196] (1) The following ingredients were prepared in order to prepare a stock solution.

[0197] (A) Component: (Meth)acrylic acid triblock copolymer

[0198] • (Meth)acrylic acid triblock copolymer (PMMA-PnBA-PMMA triblock copolymer containing PMMA (polymethyl methacrylate: glass transition temperature 105°C) about 40 mass%, PnBA (poly-n-butyl acrylate: glass transition temperature -54°C) about 60 mass%) (tensile elongation: 149%) (Kurarity (registered trademark, hereinafter the same) LA2270 manufactured by Kuraray Co., Ltd.)

[0199] • (Meth)acrylic acid triblock copolymer (PMMA-PnBA-PMMA triblock copolymer having a weight average molecular weight of about 60,000, containing PMMA about 30 mass%, PnBA about 70 mass%) (tensile elongation: 380%) (Kurarity LA2250 manufactured by Kuraray Co., Ltd.)

[0200] • (Meth)acrylic acid triblock copolymer (PMMA-PnBA-PMMA triblock copolymer containing PMMA about 20 mass%, PnBA about 80 mass%) (tensile elongation: 570%) (Kurarity LA2140 manufactured by Kuraray Co., Ltd.)

[0201] • Aromatic amide-based copolymer (Kurarity LA 2300 manufactured by Kuraray Co., Ltd.) (Tensile elongation: 490%) • (Meth)acrylic triblock copolymer (PMMA-PnBA-PMMA triblock copolymer containing PMMA about 20 mass%, PnBA about 80 mass%) (Tensile elongation: 490%) (Kurarity LA2330 manufactured by Kuraray Co., Ltd.)

[0202] • (Meth)acrylic triblock copolymer (PMMA-PnBA-PMMA triblock copolymer containing PMMA about 15 mass%, PnBA about 85 mass%) (Tensile elongation: 540%) (Kurarity LA3320 manufactured by Kuraray Co., Ltd.)

[0203] Further, the value of the tensile elongation of the above-mentioned (A) component is a value determined based on ISO 37:2017.

[0204] • (B) Component: (Meth)acrylate oligomer

[0205] • Aliphatic urethane-modified diacrylate (Number of functional groups: 2, Weight average molecular weight (Mw): 5000, Glass transition temperature: -55°C) (EBECRYL (registered trademark) 230 manufactured by Daicel- allnex Co., Ltd.)

[0206] • (C) Component: (Meth)acrylate monomer represented by the above-mentioned Formula 1

[0207] • HEAA (hydroxyethyl acrylamide) (HEAA (registered trademark) manufactured by KJ Chemicals Co., Ltd.)

[0208] • NBMA (N-n-butoxymethyl acrylamide) (manufactured by Xingbang Chemical Co., Ltd.)

[0209] • (C’) Component: Monomer other than the above-mentioned (C) component

[0210] • Ethoxylated (9) trimethylolpropane triacrylate (SR502 manufactured by Sartomer Co., Ltd.)

[0211] • Polyethylene glycol #600 dimethacrylate (NK ester 14G manufactured by Shin-nakamura Chemical Co., Ltd.)

[0212] • 2-Hydroxyethyl methacrylate acid phosphate ester (JPA-514 manufactured by Jiebei Chemical Industry Co., Ltd.)

[0213] • Mono (2-hydroxyethyl methacrylate) phosphate ester (JAMP-514 manufactured by Jiebei Chemical Industry Co., Ltd.)

[0214] • Dimethyl acrylamide (DMAA (registered trademark) manufactured by KJ Chemicals Co., Ltd.)

[0215] • Acryloylmorpholine (ACMO (registered trademark) manufactured by KJ Chemicals)

[0216] • Dimethylaminopropyl acrylamide (DMAPAA (registered trademark) manufactured by KJ Chemicals)

[0217] • Diethyl acrylamide (DEAA (registered trademark) manufactured by KJ Chemicals)

[0218] (D) Component: Photoinitiator

[0219] • 2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad (registered trademark) TPO manufactured by IGM Resins B.V.)

[0220] (E) Component: Coupling agent

[0221] • 3-Methacryloyloxypropyl trimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.)

[0222] Solvent

[0223] • Methyl ethyl ketone (reagent).

[0224] (2) Each component was mixed by stirring to obtain a stock solution, by the following procedure.

[0225] (A) The components and the solvent (methyl ethyl ketone) were weighed and stirred in a stirring kettle for 1 hour under an atmosphere of 25°C. At this time, if the solvent had volatilized from the total weight before stirring, the volatilized portion of the solvent was supplemented. Thereafter, the (B) component, the (C) component (or the (C') component), the (D) component, and the (E) component were weighed and added to the stirring kettle, and stirred for 30 minutes in the dark. The content (the amount of preparation) of each component in each stock solution is shown in Table 1. In addition, the values in Table 1 are all recorded in units of mass parts. In addition, a blank indicates that the component was not added.

[0226] [Table 1]

[0227]

[0228]

[0229] Evaluation

[0230] The liquid precursor of Examples 1 to 13 and Comparative Examples 1 to 11 was each made into a sheet-shaped composition by the following production method. Then, using the sheet-shaped composition, a rheometer measurement (before curing), a peel adhesion strength measurement (after curing), a haze measurement (after curing), and a dynamic viscoelasticity measurement (DMA) (after curing) were performed. The results obtained from these evaluations (tests) for each sheet-shaped composition are shown in Table 2 below. In Table 2, the number of each sheet-shaped composition is indicated directly reflecting the number of the liquid precursor described in Table 1.

[0231] [Production method of sheet-shaped composition]

[0232] The liquid precursor of Examples 1 to 13 and Comparative Examples 1 to 11 was each coated on a release film with a gap of 200 μm using a coater. Then, drying was performed by sequentially passing through a drying production line of 1.5 m in length under an atmosphere of 80°C at a speed of 500 mm / minute, and a drying production line of 1.5 m in length under an atmosphere of 100°C at a speed of 500 mm / minute, whereby the liquid precursor was made into a sheet shape. By this operation, a sheet-shaped composition was obtained.

[0233] Then, a sheet was produced by attaching a release film different from the above to the sheet-shaped composition. The thickness of the film including the two kinds of release films was measured with a thickness gauge, and the thickness of the sheet (after drying) was obtained by subtracting the thickness of the two kinds of release films, and was 100 μm in each case. In drying for volatilizing the solvent, the solvent starts to dry from the surface of the liquid precursor, and it is difficult for the solvent in the inside to volatilize. Therefore, if the film thickness is thickened, a bubble is sometimes left in the inside of the coated film, and therefore the gap at the time of coating is preferably 300 μm or less (lower limit: more than 0 μm).

[0234] [Rheometer measurement (before curing)]

[0235] The sheet-shaped composition obtained by the above step was peeled from the release film, and 7 sheets were overlapped so that the thickness of the whole was 700 μm, and degassing was performed using a vacuum laminator. A viscoelasticity measurement was performed using a HAAKE MARS III of Thermo Fisher Corporation in a temperature range of 0 to 130°C. The temperature at which tan δ = 1 was taken as the "flow start temperature (°C)", and the value is shown in Table 2. In the present application, it can be said that when the flow start temperature is 60 to 120°C, lamination can be performed at ordinary temperature.

[0236] [Peel adhesion strength measurement (after curing)]

[0237] COSMOSHINE Y (registered trademark) A4300 (PET film) manufactured by Toyobo Co., Ltd. having a length of 100 mm x width of 25 mm x thickness of 50 μm was combined with an acrylic resin plate manufactured by Mitsubishi Rayon Co., Ltd. having a length of 100 mm x width of 25 mm x thickness of 2 mm to produce a test piece, and the 180-degree peeling adhesion strength was measured according to JIS K 6854-2: 1999. As the production conditions of the test piece, the following were performed. First, for the PET film, the sheet-shaped composition to which a release film was attached on the side opposite to the PET film side was overlapped on a region having a length of 70 mm x width of 25 mm, and in this state, the sheet-shaped composition was laminated by a hot roll laminator at a roll temperature of 25°C and a pressure of 0.2 MPa, and then the release film was peeled off, the acrylic resin plate was overlapped, and the sheet-shaped composition was again laminated by the laminator. Then, in an autoclave, the sheet-shaped composition was left for 20 minutes at 70°C in an atmosphere at a pressure of 0.5 MPa. After confirming that the temperature of the test piece was reduced to room temperature, the sheet-shaped composition was cured by irradiating ultraviolet rays (light source: high-pressure mercury lamp) with a belt conveyor-type ultraviolet irradiator at a cumulative light quantity of 30 kJ / m 2 The strength was measured by stretching the sheet-shaped composition at a speed of 60 mm / minute using an Autograph AGX-V series manufactured by Shimadzu Corporation, and the average value was used as the "peeling adhesion strength (KN / m)". The peeling strengths at 25°C and 85°C were referred to as "peeling adhesion strength 1" and "peeling adhesion strength 2", respectively, and the values are shown in Table 2. The above "peeling adhesion strength 1" is preferably 1.0 KN / m or more, and the above "peeling adhesion strength 2" is preferably 0.3 KN / m or more. On the other hand, the upper limit is not particularly limited, and the peeling adhesion strength 1 is preferably 3.0 KN / m or less, and the peeling adhesion strength 2 is preferably 2.0 KN / m or less. In addition, the peeling adhesion strength at 85°C was measured as follows. First, a constant-temperature tank attached to the Autograph AGX-V series was set to 85°C, and the constant-temperature tank was slid from the rear side of the Autograph AGX-V series, and the jaws and the test piece (the test piece held by the upper and lower jaws) were set so as to be covered by the constant-temperature tank. Then, after the jaws and the test piece were left in the constant-temperature tank for 10 minutes, the strength was measured as described above.

[0238] [Measurement of haze (haze) (after curing)]

[0239] The sheet-shaped composition from which one release film was peeled off was made to adhere to an alkali-free glass plate having a thickness of 0.7 mm x width of 100 mm x length of 100 mm, and was transferred using a hot roll laminator in which the roll temperature was set to 25°C. Then, the other release film was peeled off, and the same alkali-free glass plate as described above was attached. Then, the test piece was put into a diaphragm-type vacuum laminator, and was degassed for 120 seconds, and was pressurized at a pressure of 0.1 MPa for 180 seconds at a temperature at which the flow of each sheet-shaped composition started. Finally, the sheet-shaped composition was cured by irradiating ultraviolet rays (light source: high-pressure mercury lamp) with a cumulative light quantity of 30 kJ / m2 A sample of the cured product of the sheet-form composition adhered to an alkali-free glass was produced by irradiating ultraviolet rays (light source: high-pressure mercury lamp) in the same manner as described above. For this sample, the haze value was measured using a spectrophotometer haze meter SH7000 manufactured by Nippon Denshoku Industries Co., Ltd. in the following manner. The transmittance of wavelengths in the range of 780 nm to 380 nm was measured, and the haze value was calculated according to JIS K 7136:2000. The number of trials was set to N = 3, and the average value was calculated. The results are shown in Table 2 as "haze value (unitless)". In the case of use for optical applications, the haze value is preferably 0.50 or less, and more preferably 0.30 or less. On the other hand, the lower limit is not particularly limited, and is about 0.01.

[0240] [Dynamic viscoelasticity measurement (DMA) (after curing)]

[0241] A cured product was produced by irradiating ultraviolet rays (light source: high-pressure mercury lamp) with a belt conveyor type ultraviolet irradiator to a sheet-form composition having a length of 60 mm, a width of 10 mm, and a thickness of 0.7 mm, so that the cumulative light quantity was 30 kJ / m 2 . Measurement was performed using a dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Technologies Science Corporation at a frequency of 1 Hz and a temperature range of -50 to 100°C. The "storage elastic modulus (x 10 7 Pa)" at a frequency of 1 Hz and 25°C was confirmed, and the value is shown in Table 2. In Table 2, the unit is shown as "x 10 7 Pa". The storage elastic modulus is preferably 0.1 x 10 7 to 10.0 x 10 7 Pa.

[0242] [Table 2]

[0243] Test item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Flow start temperature 80 116 116 79 65 73 107 97 93 89 74 86 77 Peel adhesion strength 1 1.24 1.14 1.00 1.30 1.11 1.10 1.00 1.00 1.13 1.14 1.24 1.27 1.38 Peel adhesion strength 2 0.61 0.49 0.38 0.55 0.39 0.70 0.70 0.50 0.58 0.68 0.70 0.68 0.84 Haze 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Storage elastic modulus 4.6 2.6 1.7 1.3 0.7 0.5 0.5 0.2 0.2 0.4 0.4 0.4 0.4

[0244] Test item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Flow start temperature 120 92 84 104 78 80 80 80 80 80 80 Peel adhesion strength 1 0.97 0.90 0.88 0.37 0.57 0.54 0.51 0.57 0.61 0.54 0.61 Peel adhesion strength 2 0.40 0.54 0.35 0.14 0.46 0.41 0.38 0.44 0.50 0.42 0.49 Haze 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Storage elastic modulus 1.5 0.7 0.3 0.3 3.2 3.2 3.2 3.2 3.2 3.2 3.2

[0245] In the measurement test of the peeling strength using a PET film, which is generally difficult to improve the peeling strength, as the adherend (substrate), in Examples 1 to 13, 1.0 KN / m or more at 25°C in the atmosphere, 0.3 KN / m or more at 85°C in the atmosphere, while showing high peeling strength. Although the reason is not clear, it is presumed that by using the compound represented by Formula 1 as the (C) component, the sheet-shaped composition becomes a state of high moderate affinity to the surface of the PET film, and a high peeling adhesive strength is obtained. In addition, for example, Comparative Examples 2 to 4 can reduce the storage elastic modulus of the cured product, but in the case of a composition not containing the (C) component in the present application, the peeling adhesive strength is small, and it is considered that peeling occurs at the interface of the cured product and the adherend. Furthermore, from the examples and comparative examples, it can be seen that the flow initiation temperature varies depending on the kind of the (A) component, and it is considered that by setting the temperature to the flow initiation temperature of each sheet-shaped composition at the time of performing the lamination operation, while performing the lamination operation, the haze can be suppressed to a low level.

[0246] [Industrial applicability]

[0247] The present application can be used for the assembly of display devices such as liquid crystal displays or organic EL displays. Specifically, it is suitable for the assembly of display elements, cover plates, touch panels, VR goggles, and the like as display devices or the assembly of organic EL elements themselves, and the adherend can be applied even if it is not a flat surface but a curved surface.

[0248] This application is based on Japanese Patent Application No. 2020-205609 filed on December 11, 2020, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A sheet-like photocurable composition comprising the following (A) to (D) components, which is sheet-like at 25°C in a state before curing: (A) component: a (meth) acrylate tri-block copolymer of X-Y-X type composed of a segment X and a segment Y; (B) component: a (meth) acrylate monomer other than the (A) component; (C) component: at least one selected from the group consisting of hydroxyethyl (meth) acrylamide and N-n-butoxymethyl (meth) acrylamide; (D) component: a photoinitiator, the content of the (A) component is 40 to 90 parts by mass relative to 100 parts by mass of the total of the (A) to (D) components, the content of the (B) component is 10 to 80 parts by mass relative to 100 parts by mass of the (A) component, the content of the (C) component is 0.1 to 30 parts by mass relative to 100 parts by mass of the (A) component, and the content of the (D) component is 0.1 to 5.0 parts by mass relative to 100 parts by mass of the (A) component, the monomer constituting the segment X is a methacrylate having a linear or branched alkyl group having 1 to 5 carbon atoms, and the monomer constituting the segment Y is an acrylate having a linear or branched alkyl group having 3 to 8 carbon atoms.

2. The sheet-like photocurable composition according to claim 1, wherein the content of the (A) component is 40 to 90 parts by mass relative to 100 parts by mass of the total of the (A) to (D) components, the content of the (B) component is 20 to 60 parts by mass relative to 100 parts by mass of the (A) component, and the content of the (C) component is 0.1 to 10 parts by mass relative to 100 parts by mass of the (A) component. (B) Component: urethane-modified (meth)acrylate oligomer, wherein, 3. The sheet-like photocurable composition according to claim 1 or 2, wherein the content of the (A) component is 40 to 90% by mass relative to the total mass of the sheet-like photocurable composition.

4. The sheet-like photocurable composition according to any one of claims 1 to 3, further comprising a coupling agent as a (E) component.

5. The sheet-like photocurable composition according to claim 4, wherein the content of the (E) component is 0.1 to 5.0 parts by mass relative to 100 parts by mass of the (A) component.

6. A photocurable composition solution comprising the following (A) to (D) components and a solvent: (A) component: a (meth) acrylate tri-block copolymer of X-Y-X type composed of a segment X and a segment Y; (B) component: a (meth) acrylate monomer other than the (A) component; (C) component: at least one selected from the group consisting of hydroxyethyl (meth) acrylamide and N-n-butoxymethyl (meth) acrylamide; (D) component: a photoinitiator, the content of the (A) component is 40 to 90 parts by mass relative to 100 parts by mass of the total of the (A) to (D) components, the content of the (B) component is 10 to 80 parts by mass relative to 100 parts by mass of the (A) component, the content of the (C) component is 0.1 to 30 parts by mass relative to 100 parts by mass of the (A) component, and the content of the (D) component is 0.1 to 5.0 parts by mass relative to 100 parts by mass of the (A) component, the monomer constituting the segment X is a methacrylate having a linear or branched alkyl group having 1 to 5 carbon atoms, and the monomer constituting the segment Y is an acrylate having a linear or branched alkyl group having 3 to 8 carbon atoms.

7. A method for producing a sheet-like photocurable composition, which is a method for producing a photocurable composition that is sheet-like at 25°C in a state before curing, comprising a step of volatilizing the solvent contained in the photocurable composition solution according to claim 6.

8. The method for producing a sheet-like photocurable composition according to claim 7, wherein the volatilization of the solvent is performed on a release paper or a release film.

2. The sheet-like photocurable composition according to claim 1, wherein 9. The method for producing a sheet-like photocurable composition according to claim 7 or 8, wherein the volatilization of the solvent is performed in a vacuum.

3. The sheet-like photocurable composition according to claim 1 or 2, wherein, ​ 4. The sheet-like photocurable composition according to claim 1 or 2, wherein, ​ 5. The sheet-like photocurable composition according to claim 1 or 2, wherein, ​ ​ ​ (B) Component: urethane-modified (meth)acrylate oligomer, wherein, ​ ​ ​ ​ ​ ​ ​ ​ 8. The method for producing a sheet-shaped photocurable composition according to claim 7, wherein ​ 9. A laminate having a constitution in which a first adherend, a sheet-like photocurable composition, and a second adherend are successively attached, the sheet-like photocurable composition is formed by volatilization of the solvent contained in the photocurable composition solution of claim 6 on the first adherend and / or the second adherend.

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