Sheet-like heat-curable resin composition

Abstract

To provide a heat-curable resin composition that exhibits high adhesion strength and resistance to high temperature and high humidity, suitable for use in structural bonding applications, and a production method thereof.SOLUTION: A heat-curable resin composition comprises the following components (A) to (D), has a mass ratio of component (A) to component (B) of 10:90 to 90:10, and is in a sheet form at 25°C before curing, wherein (A) component: epoxy resin having a fluorene skeleton, (B) component: epoxy resin having a urethane skeleton, (C) component: film-forming agent (excluding components (A) and (B)), and (D) component: epoxy resin curing agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting resin composition that is in the form of a sheet at 25°C. [Background technology]

[0002] Conventionally, adhesives that are liquid at 25°C, such as epoxy resins, have been used to bond adherends. However, liquid adhesives have concerns about handling and can cause problems such as resin overflow during bonding. In response to this, a sheet adhesive, such as that described in Patent Document 1, is known that can be cut in advance to fit the bonding area, is a sheet that remains solid at room temperature, and has little flow when hardened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-113483 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional sheet adhesives have poor adhesive strength and resistance to high temperatures and humidity, making them difficult to use in applications requiring high adhesive strength, such as structural adhesion. [Means for solving the problem]

[0005] As a result of intensive research to achieve the above object, the inventors discovered a method for producing a thermosetting resin composition that is in the form of a solid sheet at room temperature and has high adhesive strength and resistance to high temperatures and high humidity, thereby completing the present invention.

[0006] The gist of the present invention will now be described. [1] A thermosetting resin composition comprising the following components (A) to (D), wherein the mass ratio of component (A) to component (B) is 10:90 to 90:10, and which is in a sheet form at 25°C before curing. Component (A): Epoxy resin having a fluorene skeleton Component (B): Epoxy resin with a urethane skeleton Component (C): Film-forming agent (excluding components (A) and (B)) Component (D): Epoxy resin hardener [2] The thermosetting resin composition according to [1], which is in a sheet form at 25°C before curing, further contains a liquid epoxy resin (excluding components (A) and (B)) as component (E). [3] The thermosetting resin composition according to [2], which is in a sheet form at 25°C before curing, wherein the component (E) is a bisphenol-type epoxy resin. [4] The thermosetting resin composition according to [2], which is sheet-shaped at 25°C before curing, wherein the component (A) accounts for 5 to 75 mass% of 100 mass% of the total amount of the components (A), (B), and (E), the component (B) accounts for 8 to 50 mass% of 100 mass% of the total amount of the components (A), (B), and (E), and the component (E) accounts for 10 to 75 mass% of 100 mass% of the total amount of the components (A), (B), and (E). [5] The thermosetting resin composition according to [1], which is in a sheet form at 25°C before curing, and which contains a phenoxy resin as the component (C). [6] The thermosetting resin composition according to [1], which is in a sheet form at 25°C before curing, wherein the component (D) contains a thermal latent amine compound. [7] The thermosetting resin composition according to [1], further comprising a silane coupling agent. [8] The thermosetting resin composition according to [1], which is used for structural adhesive applications and is in a sheet form at 25°C before curing. [9] A thermosetting resin composition solution containing the following components (A) to (D) and a solvent, wherein the mass ratio of component (A) to component (B) is 10:90 to 90:10. (A): Epoxy resin with a fluorene skeleton (B): Epoxy resin with a urethane skeleton (C): Film-forming agent (D): Epoxy hardener

[10] A method for producing a sheet-shaped thermosetting resin composition that is in a sheet-like form at 25°C before curing, comprising the step of volatilizing a solvent contained in the thermosetting resin composition solution described in [9]. [Effects of the Invention]

[0007] The present invention provides a heat-curable resin composition that is easy to handle and in sheet form at 25°C, and has high adhesive strength and high temperature and humidity resistance that makes it suitable for structural adhesive applications. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below. In this specification, "X to Y" means "at least X but not more than Y," with the numerical values ​​(X and Y) before and after the "X" being used to mean the lower and upper limits, respectively. In this specification, the term "(meth)acrylic" means both acrylic and methacrylic. Furthermore, "A and / or B" means A, B, and combinations thereof. Here, the term "sheet-like" refers to a shape that has a two-dimensional surface and has a front and back surface that face each other across a distance equal to the thickness. The thickness is not particularly limited, but is preferably 5 to 300 μm, and particularly preferably 25 to 200 μm.

[0009] Component (A) that can be used in the present invention is an epoxy resin having a fluorene skeleton. Component (A) is not particularly limited as long as it is an epoxy resin having a fluorene skeleton, and it may be solid or liquid, but it is preferably a liquid at 25°C in terms of excellent adhesive strength. It is particularly preferable that the viscosity measured at 25°C using a cone-plate rotational viscometer be 0.1 to 100 Pa·s, and most preferably 0.5 to 20 Pa·s. Furthermore, "liquid at 25°C" means that the viscosity measured at 25°C using a cone-plate rotational viscometer is 1000 Pa·s or less.

[0010] The component (A) is not particularly limited as long as it has one or more epoxy groups, but it preferably has two or more, and particularly preferably has two, in order to obtain high adhesive strength.

[0011] The epoxy equivalent of the component (A) is preferably 100 to 1000 g / eq, more preferably 150 to 700 g / eq, and most preferably 250 to 600 g / eq. If the epoxy equivalent is in the range of 100 to 1000 g / eq, both adhesive strength and ease of sheet formation can be achieved.

[0012] Commercially available products of the component (A) include the OGSOL series PG-100, CG-500, EG-200, and EG-280 (manufactured by Osaka Gas Chemicals Co., Ltd.), which may be used alone or in combination.

[0013] The content of the component (A) is preferably 5 to 75 mass%, more preferably 10 to 70 mass%, even more preferably 15 to 65 mass%, and most preferably 50 to 65 mass%, based on 100 mass% of the total amount of the component (A) and the components (B) and (E) described below. By including 5 to 75 mass%, a thermosetting resin composition with excellent resistance to high temperatures and high humidity can be obtained.

[0014] Component (B) that can be used in the present invention is an epoxy resin having a urethane skeleton, excluding component (A). An epoxy resin having a urethane skeleton is a compound having at least one, preferably two, epoxy groups in an oligomer whose main skeleton is polymerized via urethane bonds. Component (B) is not particularly limited as long as it is an epoxy resin having a urethane skeleton, and may be either solid or liquid, but is preferably liquid at 25°C in terms of excellent adhesive strength.

[0015] The (B) component can be obtained by a method of reacting an isocyanate group-containing high molecular weight substance obtained by reacting a polyol compound with a polyisocyanate compound with an epoxy compound having at least one glycidyl group and one hydroxyl group in the molecule, but is not limited to this.

[0016] Examples of the polyisocyanate compound include diisocyanate compounds such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and 3,4-dimethylhexamethylene diisocyanate, and urethane prepolymers, but are not limited to these.

[0017] Examples of the polyol compound include, but are not limited to, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethyl glycol, and polybutylene glycol; polyconjugated dienes having hydroxyl groups at both ends, such as polybutadiene having hydroxyl groups at both ends; polycaprolactone diols; and polyolefin polyols.

[0018] The epoxy compound having at least one glycidyl group and one hydroxyl group in the molecule is not particularly limited, but can be obtained by reacting a polyol having at least two hydroxyl groups with epichlorohydrin.

[0019] The polyol having at least two hydroxyl groups is not particularly limited, but examples thereof include polyphenols, aliphatic polyols, and alicyclic polyols.

[0020] Examples of the polyphenols include bisphenol A, bisphenol F, tetrabromobisphenol A, phenol novolac, brominated phenol novolac, cresol novolac, brominated cresol novolac, 4,4'-dihydroxybiphenyl, and 1,1,2,2-tetrakis(hydroxyphenyl)ethane. Examples of the aliphatic polyols include polyhydric alcohols such as ethylene glycol and propylene glycol, linear or branched low-molecular-weight polyols such as butanediol, pentanediol, hexanediol, octanediol, decanediol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, and neopentyl glycol, and ethylene oxide or propylene oxide adducts thereof. Examples of the alicyclic polyols include cyclohexanediol, cyclohexanetriol, cyclohexanedimethanol, isopropylidenedicyclohexanol, decalindiol, and tricyclodecanedimethanol. These may be used alone or in combination of two or more, but are not limited to these.

[0021] Commercially available products of the component (B) include the ADEKA Resin series EPU-6, EPU-7N, EPU-11F, EPU-1395, EPU-73B, and EPU-17 (manufactured by ADEKA Corporation), which may be used alone or in combination of two or more.

[0022] The content of the component (B) is preferably 8 to 50 mass%, more preferably 10 to 40 mass%, even more preferably 12 to 35 mass%, and most preferably 12 to 20 mass%, based on 100 mass% of the total amount of the components (A), (B), and (E) described below. A content of 8 mass% will provide a thermosetting resin composition with excellent resistance to high temperatures and high humidity, and a content of 50 mass% or less will provide a thermosetting resin composition with excellent adhesive strength.

[0023] The mass ratio of component (B) to component (A) is 10:90 to 90:10, preferably 20:80 to 85:15, more preferably 30:70 to 85:15, and most preferably 70:30 to 85:15. When the mass ratio to component (A) is 10:90 to 90:10, a thermosetting resin composition having excellent adhesive strength and high-temperature and high-humidity resistance can be obtained.

[0024] Component (C) that can be used in the present invention is a film-forming agent. Components (A) and (B) are often liquid at 25°C, and may also contain component (E), which will be described later. Therefore, in order to form a thermosetting resin composition into a sheet at 25°C, it is preferable to add component (C), which is solid at 25°C. Unlike compositions that are liquid at 25°C, forming a sheet at 25°C prevents the thermosetting resin composition from spilling over the edges of the adherend when used to bond plate-shaped adherends.

[0025] A particularly preferred component (C) is a solid epoxy resin, excluding components (A) and (B). There are no particular restrictions on the solid epoxy resin as long as it is solid at 25°C, but solid epoxy resins having a fluorene skeleton are included in component (A), and solid epoxy resins having a urethane skeleton are included in component (B). Specific examples of solid epoxy resins include solid bisphenol-type epoxy resins such as solid bisphenol A-type epoxy resins and solid bisphenol F-type epoxy resins, and epoxy resins such as phenoxy resins. Among these, when forming the thermosetting composition into a sheet, it is preferable to include phenoxy resin, which has good film strength, and it is even more preferable to use a combination of phenoxy resin and solid bisphenol-type epoxy resin.

[0026] The epoxy equivalent of the component (C) is preferably 100 to 15,000 g / eq, more preferably 200 to 12,500 g / eq, and most preferably 300 to 10,000 g / eq. A range of 100 to 15,000 g / eq allows for both good adhesive strength and ease of sheet formation.

[0027] The phenoxy resin is a polymer obtained by polymerizing a polyfunctional epoxy resin such as a bisphenol-type epoxy resin, and may have residual epoxy groups at its terminals. The weight-average molecular weight is preferably 10,000 to 100,000, and more preferably 30,000 to 80,000. Specific examples of the phenoxy resin include bisphenol-type phenoxy resin, novolac-type phenoxy resin, naphthalene-type phenoxy resin, and biphenyl-type phenoxy resin. These may be used alone or in combination. The phenoxy resin is preferably a bisphenol-type phenoxy resin that is solid at 25°C. Among these, due to their good compatibility with components (A) and (B) of the present invention, more preferred are phenoxy resins obtained by polymerizing bisphenol A-type epoxy resins, phenoxy resins obtained by polymerizing bisphenol F-type epoxy resins, phenoxy resins obtained by copolymerizing bisphenol A-type epoxy resins with bisphenol F-type epoxy resins, and phenoxy resins that are mixtures of these, even more preferred are phenoxy resins obtained by polymerizing bisphenol A-type epoxy resins, and most preferred are phenoxy resins obtained by polymerizing only bisphenol A-type epoxy resins (bisphenol A-type phenoxy resins). These may be used alone or in combination of two or more.

[0028] Component (C) can be a commercially available product, specifically, but not limited to, the PhenoTohto series (YP-50, YP-50S, YP-55, YP-70, ZX-1356-2, FX-316 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) and the jER series (1001, 1002, 1004, 1007, 1256, 4005P, 4007P, 4010P, 4250, 4275 (manufactured by Mitsubishi Chemical Corporation)), and PKHB, PKHC, PKHH, PKHJ, PKFE (manufactured by Tomoe Engineering Co., Ltd.). Component (C) may be diluted with a solvent at the raw material stage, and examples of commercially available products diluted with a solvent include, but are not limited to, jER1001B80 and jER1256B40 (manufactured by Mitsubishi Chemical Corporation).

[0029] The amount of component (C) added in the present invention is preferably 20 to 200 parts by mass, more preferably 50 to 150 parts by mass, and most preferably 75 to 125 parts by mass, per 100 parts by mass of the total amount of components (A), (B), and (E), which will be described later. When component (C) is 20 parts by mass or more, the thermosetting resin composition after molding into a sheet does not become sticky, and release films and the like are easily peeled off. On the other hand, when component (C) is 200 parts by mass or less, excellent adhesive strength is achieved.

[0030] Component (D) that can be used in the present invention is an epoxy resin curing agent. Examples of epoxy resin curing agents include amine compounds and / or phenol compounds. Component (D) may be liquid or solid at 25°C. It may be used alone or in combination with two or more curing agents, as long as it can react with components (A), (B), and (E), described below, to form a cured product. A curing agent that is liquid at 25°C and a curing agent that is solid at 25°C may be used by dissolving or dispersing them together. However, a solid curing agent is preferred for its excellent shelf life after molding into a sheet, and a solid curing agent alone is more preferred. A powder is most preferred. The powder preferably has an average particle size of 0.1 to 20 μm, more preferably 0.1 to 10 μm, and most preferably 0.5 to 5 μm. The average particle size of component (D) refers to the particle size at 50% cumulative volume (D50) in the particle size distribution determined by laser diffraction scattering.

[0031] The component (D) preferably contains an amine compound, which allows the curing temperature to be relatively low, and most preferably contains a thermally latent amine compound, which provides excellent shelf life. A thermally latent amine compound is an amine compound that has no activity toward epoxy resins at room temperature, but becomes activated by application of heat or other stimuli through dissolution, decomposition, or a rearrangement reaction, thereby promoting curing. Furthermore, silane coupling agents containing amino groups are available as optional amine compounds, as described below, but are not included in component (D) and are treated as optional silane coupling agents.

[0032] As the thermally latent amine compound, imidazole compounds, epoxy adduct-type amine compounds, dicyandiamide, dihydrazide compounds, and other amine compounds can also be used. These can be used alone or in combination of two or more. However, dicyandiamide and / or imidazole compounds are preferred from the viewpoint of excellent storage stability, and a combination of dicyandiamide and an imidazole compound is even more preferred from the viewpoint of being able to cure at a relatively low temperature. When dicyandiamide and an imidazole compound are used in combination, the mass ratio of each is preferably 90:10 to 10:90, more preferably 90:10 to 30:70, and most preferably 80:20 to 50:50. A range of 90:10 to 10:90 allows for the production of a thermosetting resin composition with excellent adhesive strength.

[0033] Examples of the imidazole compounds as the thermal latent amine compounds include imidazole, 2-methylimidazole, 2-heptadecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-furan. phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolium zolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like, but are not limited to these. Specific examples of imidazole compounds include, but are not limited to, the Curesol series SIZ, 2MZ-H, C11Z, C17Z, 1.2DMZ, 2E4MZ, 2PZ, 2PZ-PW, 2P4MZ, 1B2MZ, 1B2PZ, 2MZ-CN, C11Z-CN, 2E4MZ-CN, 2PZ-CN, C11Z-CNS, 2PZCNS-PW, 2MZ-A, 2MZA-PW, C11Z-A, 2E4MZ-A, 2MA-OK, 2MAOK-PW, 2PZ-OK, 2PHZ-PW, and 2P4MHZ-PW (manufactured by Shikoku Chemicals Corporation).

[0034] Examples of epoxy adduct amine compounds as thermally latent amine compounds include, but are not limited to, the Amicure series, such as PN-23, PN-H, PN-31, PN-40, PN-50, PN-F, PN-23J, PN-31J, PN-40J, MY-24, and MY-25 (manufactured by Ajinomoto Fine-Techno Co., Ltd.), the Fujicure series, such as FXE-1000, FXR-1020, FXR-1030, FXR-1081, FXR-1020, and FXR-1121 (manufactured by T&K TOKA Corporation), and the Novacure series, such as HX-3921HP, HX-3941HP, and HX-3088 (manufactured by Asahi Kasei E-Materials Corporation).

[0035] Examples of dicyandiamide as a thermally latent amine compound include Omicure DDA-5 (manufactured by PTI Japan Co., Ltd.), DICY7, DICY15, DICY50 (manufactured by Mitsubishi Chemical Corporation), and DD, D25F (manufactured by Nippon Carbide Industries Co., Ltd.), but are not limited to these.

[0036] Dihydrazide compounds as thermally latent amine compounds include, but are not limited to, adipic dihydrazide, sebacic dihydrazide, dodecane dihydrazide, isophthalic dihydrazide, salicylic hydrazide, 1,3-bis(hydrazinocarbonoethyl)-5-isopropylhydantoin, and 7,11-octadecadiene-1,18-dicarbohydrazide. Specific commercial products include ADH, SDH, DDH, IDH, and SAH (manufactured by Otsuka Chemical Co., Ltd.), and the Amicure series includes VDH-J and UDH (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

[0037] Other known thermally latent amine compounds include, but are not limited to, 1,2,3-benzotriazole.

[0038] Examples of the phenolic compound include phenol novolac polymer, bisphenol A novolac polymer, cresol novolac polymer, polyparavinylphenol polymer, etc. Specific examples include TD-2131, TD-2106, VH-4150, VH-4170, KA-1160, and KA-1163 (manufactured by DIC Corporation), Maruka Linker M (manufactured by Maruzen Petrochemical Co., Ltd.), MEH-7500 series, and MEH-7851 series (manufactured by Meiwa Kasei Co., Ltd.), but are not limited to these.

[0039] The amount of component (D) added is preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass, and most preferably 5 to 10 parts by mass, per 100 parts by mass of the total amount of components (A), (B), and (E) described below. If the amount is 1 part by mass or more, excellent adhesive strength after curing will be achieved, and if the amount is 20 parts by mass or less, excellent ease of forming into a sheet will be achieved.

[0040] Component (E) that can be used in the present invention is a liquid epoxy resin, excluding components (A) and (B). Component (E) is not particularly limited as long as it is an epoxy resin that is liquid at 25°C. However, the aforementioned epoxy resin having a fluorene skeleton (component (A)) and epoxy resin having a urethane skeleton (component (B)) (excluding component (A)) are treated as components (A) and (B), respectively. A liquid at 25°C refers to a viscosity of 1000 Pa·s or less measured at 25°C using a cone-plate rotational viscometer. Furthermore, in this specification, the term "liquid epoxy resin" refers to all epoxy resins that are liquid at 25°C, excluding components (A), (B), and the silane coupling agent described below.

[0041] The component (E) is not particularly limited as long as it is a liquid epoxy resin having one or more epoxy groups per molecule, but it is preferable that it contains a liquid epoxy resin having two or more epoxy groups per molecule in terms of excellent curing properties and workability. Specific examples of the component (E) include bisphenol-type epoxy resins, hydrogenated bisphenol-type epoxy, 1,2-butanediol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, (poly)ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 2,3-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether. Examples of suitable epoxy resins include alkylene glycol epoxy resins such as ether and 1,4-cyclohexanedimethanol diglycidyl ether, novolac epoxy resins such as phenol novolac epoxy resins and cresol novolac epoxy resins; glycidyl amine compounds such as N,N-diglycidyl-4-glycidyloxyaniline, 4,4'-methylenebis(N,N-diglycidylaniline), tetraglycidyldiaminodiphenylmethane, and tetraglycidyl-m-xylylenediamine; and naphthalene epoxy resins having four glycidyl groups. These may be used alone or in combination of two or more. However, bisphenol-type epoxy resins are preferred due to their excellent resistance to high temperatures and high humidity, and bisphenol-type epoxy resins having two or more epoxy groups are preferred. Furthermore, the silane coupling agent containing an epoxy group, which will be described later, is not considered as component (E) but is considered as a silane coupling agent.

[0042] The bisphenol epoxy resin is not particularly limited as long as it is an epoxy resin having a bisphenol skeleton, and examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AD ​​epoxy resin, rubber-modified bisphenol epoxy resin, polyoxyalkylene-modified bisphenol epoxy resin, etc. These may be used alone or in combination of two or more, but it is preferable to include bisphenol A epoxy resin because of its excellent resistance to high temperatures and high humidity.

[0043] Commercially available products of component (E) include, but are not limited to, jER828, 801, 806, 807, YX8000, and YX8034 (manufactured by Mitsubishi Chemical Corporation), Epicron 830, 850, EXA-830CRP, EXA-830LVP, EXA-850CRP, and EXA-835LV (manufactured by DIC Corporation), Adeka Resin EP-4100, EP-4000, EP-4000S, EP-4080, EP-4085, EP-4088, EPR-4023, EPR-1309, and EP-4920 (manufactured by ADEKA Corporation), and TEPIC (manufactured by Nippon Chemi-Con Corporation). Examples of such an anti-fungal agent include KF-101, KF-1001, KF-105, X-22-163B, and X-22-9002 (manufactured by Shin-Etsu Chemical Co., Ltd.), Denacol EX411, 314, 201, 212, and 252 (manufactured by Nagase ChemteX Corporation), DER-331, 332, 334, 431, and 542 (manufactured by The Dow Chemical Company), YH-434, YH-434L, and ST-3000 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Rikaresin HBE-100 (manufactured by New Japan Chemical Co., Ltd.), and Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.). These may be used alone or in combination of two or more.

[0044] The content of the component (E) is preferably 0 to 80% by mass, more preferably 10 to 75% by mass, and most preferably 20 to 60% by mass, based on 100% by mass of the total amount of the components (A), (B), and (E). By keeping the content at 80% by mass or less, a thermosetting resin composition with excellent resistance to high temperatures and high humidity can be obtained.

[0045] The thermosetting resin composition of the present invention may contain an appropriate amount of optional components such as a silane coupling agent, a filler, a colorant such as a pigment or a dye, a storage stabilizer, a plasticizer, an antioxidant, an antifoaming agent, an antiaging agent, an ultraviolet absorber, a leveling agent, a rheology control agent, an emulsifier, a release agent, a heat dissipation material, and a flame retardant, as long as the effects of the present invention are not impaired.

[0046] The thermosetting resin composition of the present invention may contain a silane coupling agent. Examples of the silane coupling agent include silane coupling agents containing an epoxy group such as 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane; vinyl group-containing silane coupling agents such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, and vinyltrimethoxysilane; silane coupling agents containing a (meth)acrylic group such as γ-methacryloxypropyltrimethoxysilane; silane coupling agents containing an amino group such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; γ-mercaptopropyltrimethoxysilane; γ-chloropropyltrimethoxysilane; and oligomers thereof. Among these, silane coupling agents containing an epoxy group are preferred because of their excellent adhesive strength. These may be used alone or in combination of two or more. Furthermore, compounds listed as silane coupling agents are not included in the components (A), (B), and (E).

[0047] Commercially available silane coupling agents include, but are not limited to, KBM-1003, KBE-1003, KBM-303, KBM-403, KBE-403, KBM-502, KBE-502, KBM-503, KBE-503, KBM-5103, KBM-1403, KBM-602, KBM-603, KBM-903, and KBE-903 (manufactured by Shin-Etsu Chemical Co., Ltd.), and Z-6610, Z-6044, Z-6825, Z-6033, and Z-6062 (manufactured by Dow Corning Toray Co., Ltd.).

[0048] The amount of the silane coupling agent added is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and most preferably 1 to 10 parts by mass, per 100 parts by mass of the total amount of the components (A), (B), and (E). If the amount is 0.1 part by mass or more, the adhesive strength after curing is excellent, and if the amount is 20 parts by mass or less, the thermosetting resin composition will not become sticky after being molded into a sheet.

[0049] The thermosetting resin composition of the present invention may contain a filler. Examples of fillers include organic fillers and inorganic fillers, with inorganic fillers being preferred due to their superior adhesive strength after curing. Specific examples of inorganic fillers include 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, dried clay mineral powder, dried diatomaceous earth powder, and metal powder. Furthermore, examples of fumed silica powder include those whose surfaces have been chemically modified (hydrophobized) with organochlorosilanes, polyorganosiloxanes, hexamethyldisilazane, etc., but are not limited thereto. Specific examples of commercially available inorganic fillers include the Aerosil (registered trademark) series R974, R972, R972V, R972CF, R805, R812, R812S, R816, R8200, RY200, RX200, RY200S, and R202 manufactured by Nippon Aerosil Co., Ltd.

[0050] In the present invention, a solvent can be used to process the thermosetting resin composition in an uncured state before being cured by heat into a sheet and to mix the components contained in the thermosetting resin composition. That is, another aspect of the present invention is a thermosetting resin composition solution containing the following components (A) to (D) and a solvent, in which the mass ratio of component (A) to component (B) is 10:90 to 90:10: (A): Epoxy resin with a fluorene skeleton (B): Epoxy resin with a urethane skeleton (C): Film-forming agent (D): Epoxy hardener

[0051] Examples of the solvent include alcohols such as methanol and ethanol, chlorinated solvents such as dichloroethane and trichloroethane, fluorinated solvents such as trichlorofluoroethane, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, ethers such as dimethyl ether and methyl ethyl ether, hydrocarbon solvents such as pentane, hexane, heptane, and cyclohexane, and aromatic solvents such as benzene, toluene, and xylene. Among these, ketone solvents are preferred in view of compatibility with components (A) to (C).

[0052] The content of the solvent contained in the thermosetting resin composition solution is not particularly limited, but is preferably 5 to 80% by mass, more preferably 10 to 75% by mass, and most preferably 30 to 70% by mass, relative to 100% by mass of the entire thermosetting resin composition solution. A content of 5 to 80% by mass provides excellent workability when molding the thermosetting resin composition into a sheet. The thermosetting resin composition solution refers to a liquid solution containing components (A) to (D) and a solvent. The thermosetting resin composition also refers to a composition containing components (A) to (D) from which the solvent contained in the thermosetting resin composition solution has been removed by a drying process.

[0053] The method for producing the thermosetting resin composition solution according to the present invention is not particularly limited, and can be obtained by mixing the above-mentioned components and solvent using a known mixing method. The order in which the components are added is not particularly limited, but it is preferable to first add component (C) and the solvent to a stirring vessel and stir, and then add the other components and stir. Component (C) may be diluted with a solvent at the raw material stage. In this case, if the solvent evaporates during mixing, it is preferable to replenish the evaporated solvent. The viscosity during mixing is not particularly limited, but to prevent the viscosity from becoming too high, the temperature is preferably 10 to 70°C, more preferably 20 to 50°C, and particularly preferably room temperature (25°C), and the mixing time is preferably 0.1 to 5 hours, more preferably 30 minutes to 3 hours.

[0054] By including a solvent in the thermosetting resin composition solution, it is possible to obtain a thermosetting resin composition in an uncured state in a sheet form at 25°C (hereinafter also referred to as a sheet-shaped thermosetting resin composition) by a drying step without going through a heat curing step. The sheet-shaped thermosetting resin composition is solid even before the curing reaction progresses because it includes component (C), but by making it a thermosetting resin composition solution containing a solvent, it is easy to mold into a sheet, and an uncured sheet-shaped thermosetting resin composition can be obtained by a drying step.

[0055] Known techniques can be used to process a thermosetting resin composition solution into a sheet (a method for producing a sheet-shaped thermosetting resin composition). For example, a method is available in which a thermosetting resin composition solution is prepared by intentionally lowering the viscosity by adding a solvent to the thermosetting resin composition, and the thermosetting resin composition solution is applied to a release paper or release film (hereinafter also referred to as "release film, etc.") whose surface has been previously subjected to a release treatment (coating step), followed by drying the solvent (drying step) to produce a sheet. This results in a thermosetting resin composition that is in a sheet form at 25°C before curing. That is, yet another aspect of the present invention is a method for producing a thermosetting resin composition that is in a sheet form at 25°C before curing, which method includes volatilizing the solvent contained in the thermosetting resin composition solution. In this case, the solvent is preferably volatilized on the release paper or release film.

[0056] The coating step can be carried out by a known coating method, and specific examples thereof include, but are not limited to, a flow coating method, a roll coating method, a gravure roll method, a wire bar method, a lip die coating method, etc. The thickness of the thermosetting resin composition solution during coating is not particularly limited, but is preferably 10 to 300 μm, and more preferably 50 to 250 μm.

[0057] Furthermore, a known drying method can be used for the drying step. The drying device used here is not particularly limited, but examples include a hot air drying oven and an IR oven. A conveyor for transporting a release film or the like coated with the thermosetting resin composition solution may be provided in the hot air drying oven. This step does not cure the thermosetting resin composition, but rather dries the solvent to obtain a sheet-like thermosetting resin composition in an uncured state.

[0058] The temperature in the drying step is not particularly limited as long as it is a temperature at which the solvent contained in the thermosetting resin composition solution is sufficiently volatilized, but is preferably, for example, 25 to 150°C, and more preferably 40 to 120°C. The drying time is also not particularly limited, but is preferably, for example, 1 to 20 minutes, and more preferably 3 to 10 minutes. Furthermore, the drying step may be carried out in multiple stages by changing the drying temperature.

[0059] The sheet-shaped thermosetting resin composition thus formed has a configuration in which it is formed on a release film or the like as described above (a configuration in which a release film or the like is laminated to one side of the thermosetting resin composition). The sheet-shaped thermosetting resin composition may also have a release film or the like laminated to both sides. Specifically, it is preferable to laminate a release film or the like to the other side of the sheet-shaped thermosetting resin composition after the drying step, on which no release film or the like is laminated, using a roller or the like. Furthermore, when a release film or the like is not used during the coating process, or when a release film or the like other than that used during the coating process is used, a separate release film or the like may be laminated to one or both sides of the sheet-shaped thermosetting resin composition. When release films are laminated to both sides, it is preferable to use release films with different releasability. It is even more preferable to use a release film that has weaker releasability (is more difficult to peel) as the release film laminated to the sheet-shaped thermosetting resin composition after the drying step than the release film used during the coating process.

[0060] The release paper is not particularly limited, but examples include paper such as fine paper, kraft paper, or glassine paper, on at least one side of which is provided a coating layer made of a filler such as clay, polyethylene, or polypropylene, and on which is coated a silicone-based, fluorine-based, or alkyd-based release agent.

[0061] Examples of materials for the release film include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, as well as cloth and nonwoven fabric. Among these, plastic films are preferred from the viewpoint of releasability. The thickness of the release film is preferably 5 to 300 μm, more preferably 25 to 200 μm. Furthermore, the release film is preferably one that has been subjected to a release treatment using a fluorine-based compound, a silicone-based compound, a long-chain alkyl compound, or the like.

[0062] The sheet-shaped thermosetting resin composition formed on the release film is transferred to a first adherend using a roll laminator or the like. When using a sheet-shaped thermosetting resin composition with release films attached to both sides, the release films with strong releasability (easily peeled) are peeled off before transfer. The other release film is then peeled off, and the second adherend is positioned and placed, and heated and bonded using a vacuum laminator, a heat-pressure bonding machine, an autoclave, a hot-air drying oven, or the like. The second adherend may be one onto which the sheet-shaped thermosetting resin composition has been transferred. The heating temperature is preferably 60 to 120°C, more preferably 70 to 100°C, the pressure is preferably 0.05 to 1.0 MPa, and the heating time is preferably 5 to 120 seconds. This results in a laminate consisting of the first adherend, the thermosetting resin composition, and the second adherend. Alternatively, the thermosetting resin composition solution may be applied to a first adherend, dried, and then a second adherend may be attached thereto in the same manner as described above to produce a laminate. Alternatively, the thermosetting resin composition solution may be applied to both a first adherend and a second adherend, and the resulting laminate may be used to produce a laminate. The sheet-like thermosetting resin composition of the present invention preferably exhibits fluidity in the range of 40 to 130°C. "Exhibiting fluidity" means that the viscosity of the thermosetting resin composition is preferably 10,000 Pa·s or less, more preferably 5,000 Pa·s or less, and is preferably, but not limited to, 500 Pa·s or more.

[0063] The sheet-shaped thermosetting resin composition of the present invention may be cut into any desired shape before being transferred to the first adherend. By cutting out any desired shape in advance, the sheet-shaped thermosetting resin composition is prevented from being stuck to unnecessary areas and from spilling out.

[0064] It is preferable to further heat the laminate. Heating the laminate initiates the reaction of the thermosetting resin composition, resulting in even better adhesive strength and resistance to high temperatures and high humidity. The laminate may be heated using a heat press machine, autoclave, hot air drying oven, etc., and the temperature conditions are preferably 80 to 200°C, more preferably 100 to 180°C, and most preferably 120 to 170°C. The heating time is preferably 5 minutes to 3 hours, more preferably 10 minutes to 2 hours, and most preferably 20 minutes to 1.5 hours. The thermosetting resin composition of the present invention initiates curing by this heating step, and a cured product can be obtained.

[0065] The sheet-shaped thermosetting resin composition of the present invention can be used in a variety of applications. Specific examples include adhesion, sealing, casting, coating, etc. of automobile bodies, switches, headlamps, engine internal parts, electrical components, drive engines, brake oil tanks, front hoods, fenders, body panels such as doors, windows, etc.; in the electronic materials field, adhesion, sealing, casting, coating, etc. of flat panel displays (liquid crystal displays, organic EL displays, light-emitting diode displays, field emission displays), video discs, CDs, DVDs, MDs, pickup lenses, hard disks, etc.; in the battery field, adhesion, sealing, casting, coating, etc. of lithium batteries, lithium ion batteries, etc. The resin composition can be used for bonding, sealing, coating, etc. of batteries, manganese batteries, alkaline batteries, fuel cells, silicon solar cells, dye-sensitized batteries, organic solar cells, etc.; in the optical component field, bonding and sealing, etc. of optical fiber materials around optical switches and optical connectors, optical passive components, optical circuit components, and optoelectronic integrated circuits; in the optical equipment field, bonding and sealing, etc. of camera modules, lens materials, viewfinder prisms, target prisms, viewfinder covers, light-receiving sensors, photographic lenses, and projection television lenses; and in the infrastructure field, bonding, lining materials, and sealing materials for gas pipes, water pipes, etc. The sheet-shaped thermosetting resin composition of the present invention is particularly suitable for structural adhesive applications due to its high adhesive strength and excellent resistance to high temperatures and humidity. Examples of applications for structural adhesive applications include automobile bodies, automobile parts, machine tools, aircraft parts, motors, generators, transformers, and other areas requiring welding. [Example]

[0066] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. (Hereinafter, the thermosetting resin composition will also be referred to simply as the composition, and the thermosetting resin composition solution will also be referred to as the stock solution.)

[0067] [Examples 1 to 3, Comparative Examples 1 to 9] The following ingredients were prepared to prepare the stock solution: Component (A): Epoxy resin having a fluorene skeleton OGSOL EG-280 (a bifunctional epoxy resin with a fluorene skeleton, viscosity (25°C): 7.4 Pa·s, epoxy equivalent: 460 g / epoxy, manufactured by Osaka Gas Chemicals Co., Ltd.) Component (B): Epoxy resin with a urethane skeleton ADEKA RESIN EPU-73B (a mixture of a bifunctional urethane-based epoxy resin (35% by mass) and a bifunctional bisphenol A-type epoxy resin (65% by mass) (viscosity (25°C): 130 Pa·s), manufactured by ADEKA Corporation) is an epoxy resin component with a urethane skeleton. (C) Component: Film-forming agent Phenoxy resin component of jER1256B40 (mixture of bisphenol A phenoxy resin (40% by mass) and methyl ethyl ketone (60% by mass), manufactured by Mitsubishi Chemical Corporation) -jER1001B80 (a mixture of solid bisphenol A epoxy (80% by mass) and methyl ethyl ketone (20% by mass), manufactured by Mitsubishi Chemical Corporation) solid epoxy resin component Component (D): Epoxy resin hardener DICY7 (dicyandiamide, average particle size: 3 μm, manufactured by Mitsubishi Chemical Corporation) Curesol 2MAOK-PW (2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, average particle size: 2 μm, manufactured by Shikoku Chemicals Corporation) Optional ingredients Component (E): Liquid epoxy resin Bisphenol A epoxy resin component of ADEKA Resin EPU-73B (a mixture of bifunctional urethane-based epoxy resin (35% by mass) and bifunctional bisphenol A epoxy resin (65% by mass) (viscosity (25°C): 130 Pa·s) manufactured by ADEKA Corporation) ADEKA RESIN EPR-2000 (bifunctional NBR rubber-modified epoxy resin, viscosity (25°C): 23 Pa·s, manufactured by ADEKA Corporation) jER154 (phenolic novolac epoxy resin, viscosity (50°C): 50 Pa·s, manufactured by Mitsubishi Chemical Corporation) EPICLON EXA-4850-150 (epoxy resin with a bifunctional polyether backbone, viscosity (25°C): 15 Pa·s, manufactured by DIC Corporation) jER828 (difunctional bisphenol A epoxy resin, viscosity (25°C): 13 Pa·s, manufactured by Mitsubishi Chemical Corporation) EPICLON EXA-835LV (a mixture of difunctional bisphenol A epoxy resin and difunctional bisphenol F epoxy resin, mass ratio 50:50, viscosity (25°C): 2 Pa·s, manufactured by DIC Corporation) jER807 (difunctional bisphenol F epoxy resin, viscosity (25°C): 4 Pa·s, manufactured by Mitsubishi Chemical Corporation) silane coupling agent KBM-403 (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) solvent Methyl ethyl ketone in jER1256B40 (a mixture of bisphenol A-type phenoxy resin (40% by mass) and methyl ethyl ketone (60% by mass), manufactured by Mitsubishi Chemical Corporation) Methyl ethyl ketone in jER1001B80 (a mixture of solid bisphenol A epoxy (80% by mass) and methyl ethyl ketone (20% by mass), manufactured by Mitsubishi Chemical Corporation) Methyl ethyl ketone (reagent)

[0068] [Adjusting the stock solution] The stock solutions of Examples 1 to 3 and Comparative Examples 1 to 9 were prepared using the following manufacturing method. Components (A) to (C), optional components, and a solvent were weighed and stirred for 30 minutes using a planetary mixer. Next, component (D) was weighed and added, and the mixture was stirred for an additional 30 minutes using a planetary mixer to obtain a stock solution. Detailed preparation amounts are shown in Table 1, and all values ​​are expressed in parts by mass. Table 1 also shows the "mass ratio of component (A) to component (B)."

[0069] [Table 1]

[0070] [Production of sheet-shaped composition] Using the stock solutions of Examples 1 to 3 and Comparative Examples 1 to 9, sheet-shaped compositions (hereinafter referred to as sheet compositions) were prepared at 25°C. Each of the stock solutions of Examples 1 to 3 and Comparative Examples 1 to 9 was coated onto a release film to a film thickness of 100 μm using a coating machine. The stock solutions were then dried at a speed of 500 mm / min through a 1.5 m long drying line in an 80°C atmosphere, thereby forming the stock solutions into sheets. Sheet compositions were obtained through this procedure.

[0071] Then, a different release film was laminated to produce a sheet with two types of release films. The release film used for lamination had weaker releasability (less peelable) than the release film coated with the sheet composition. For lamination, the sheet composition sandwiched between the two types of release films was passed through a 2 kg roller to laminate them. For each sheet obtained in this way, the film thickness including the two types of release films was measured with a thickness gauge, and the thickness of the two types of release films was subtracted to determine the film thickness (after drying) of the sheet composition. All were 50 μm.

[0072] The sheet-shaped compositions were used to measure the adhesive strength and resistance to high temperatures and humidity as described below. The results are shown in Table 2. In Table 2, the numbers of the respective sheet-shaped compositions are expressed by directly reflecting the numbers of the original solutions listed in Table 1.

[0073] [Preparation of test specimens] The two types of release films were peeled off, and the composition sides of each sheet-like composition were placed on an SPCC-SD sheet measuring 25 mm wide x 100 mm long x 1.6 mm thick, with the easily peelable release film removed, so that they overlapped in an area of ​​25 mm x 10 mm. The sheet was then passed through a hot roll laminator at a roll temperature of 80 ° C and a pressure of 0.2 MPa to prepare a test piece. The remaining release film was then peeled off, and the test pieces were stacked together so that the sheet compositions overlapped, and then secured in place with a pinch. The stacked test pieces were placed in a hot air drying oven at 150 ° C for 1 hour. The test pieces were removed from the hot air drying oven and cooled at 25 ° C for 1 hour to prepare test pieces.

[0074] [Adhesive strength] The initial shear bond strength was measured as the adhesive strength using the following test method. The test piece was fixed to the chuck of a universal tensile tester and pulled in the shear direction at a pulling rate of 10 mm / min at 25°C to measure the "maximum load." The "initial shear bond strength (MPa)" was calculated by dividing the "maximum load" by the "adhesion area." The test details were in accordance with JIS K6850:1999, and evaluation was performed according to the following evaluation criteria. Pass: 36 MPa or more The upper limit is not particularly limited, but is 60 MPa or less.

[0075] [High temperature and high humidity resistance] The prepared test specimens were placed in a high-temperature, high-humidity chamber at 65°C and 95% RH for 500 hours. The specimens were removed from the chamber and cooled at 25°C for 1 hour. The specimens were then secured to the chuck of a universal tensile tester and pulled in the shear direction at 25°C at a rate of 10 mm / min to measure the "maximum load." The "maximum load" was divided by the "bond area" to calculate the "post-durability shear bond strength (MPa)." Test details were in accordance with JIS K6850:1999. The "initial shear bond strength" and "post-durability shear bond strength" were used to calculate the "post-durability change rate (%)" using the following formula, and the results were evaluated according to the following criteria. In Table 2, "-" indicates that the initial shear bond strength did not meet the acceptable criteria and was therefore not measured. · Change rate after durability (%) = ((shear adhesive strength after durability / initial shear adhesive strength) - 1) x 100 Pass: -50% or more The upper limit is not particularly limited, but is not more than 100%.

[0076] [Table 2]

[0077] Examples 1 to 3 had high initial shear bond strength and reduced change rate after durability testing, confirming that they had excellent adhesive strength and high-temperature, high-humidity resistance. In contrast, Comparative Example 1, which is a composition that does not contain component (B), had a large change rate after durability testing, confirming that it had poor high-temperature, high-humidity resistance. Comparative Example 2, which is a composition with a mass ratio of components (A) to (B) of 92:8, outside the range of 10:90 to 90:10, had a large change rate after durability testing, confirming that it had poor high-temperature, high-humidity resistance. Comparative Example 3, which is a composition that does not contain component (A), had a low initial shear bond strength, confirming that it had poor adhesive strength. Comparative Examples 4 to 9, which are compositions that do not contain component (B) but instead contain component (E), had low initial shear bond strength, confirming that it had poor adhesive strength. [Industrial Applicability]

[0078] The thermosetting resin composition of the present invention has excellent adhesive strength and resistance to high temperatures and high humidity, and is therefore applicable to a variety of fields requiring high durability and reliability, and is particularly useful for structural adhesive applications.

Claims

1. A thermosetting resin composition comprising the following components (A) to (D), wherein the mass ratio of component (A) to component (B) is 10:90 to 90:10, and the composition is in a sheet form at 25°C before curing: Component (A): Epoxy resin having a fluorene skeleton Component (B): Epoxy resin having a urethane skeleton Component (C): film-forming agent (excluding components (A) and (B)) Component (D): Epoxy resin curing agent

2. 2. The thermosetting resin composition according to claim 1, which is in a sheet form at 25°C before curing, further comprising a liquid epoxy resin (excluding components (A) and (B)) as component (E).

3. 3. The thermosetting resin composition according to claim 2, which is in a sheet form at 25°C before curing, wherein the component (E) is a bisphenol-type epoxy resin.

4. 3. The thermosetting resin composition according to claim 2, which is sheet-shaped at 25°C before curing, wherein the component (A) accounts for 5 to 75 mass% of 100 mass% of the total amount of the components (A), (B), and (E), the component (B) accounts for 8 to 50 mass% of 100 mass% of the total amount of the components (A), (B), and (E), and the component (E) accounts for 10 to 75 mass% of 100 mass% of the total amount of the components (A), (B), and (E).

5. 2. The thermosetting resin composition according to claim 1, which is in a sheet form at 25°C before curing, wherein the component (C) comprises a phenoxy resin.

6. 2. The thermosetting resin composition according to claim 1, which is in a sheet form at 25°C before curing, wherein the component (D) comprises a thermal latent amine compound.

7. The thermosetting resin composition according to claim 1 , further comprising a silane coupling agent.

8. The thermosetting resin composition according to claim 1, which is in a sheet form at 25°C before curing and is used for structural adhesive applications.

9. A thermosetting resin composition solution containing the following components (A) to (D) and a solvent, wherein the mass ratio of component (A) to component (B) is 10:90 to 90:10: (A): Epoxy resin having a fluorene skeleton (B): Epoxy resin having a urethane skeleton (C): Film-forming agent (D): Epoxy curing agent

10. 10. A method for producing a sheet-shaped thermosetting resin composition that is in a sheet-like form at 25°C before curing, the method comprising the step of volatilizing a solvent contained in the thermosetting resin composition solution according to claim 9.

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