Thermosetting epoxy resin composition and thermosetting epoxy resin sheet

Abstract

To provide a thermosetting epoxy resin composition which is excellent in flexibility before curing, is excellent in storage stability and moldability, has a high glass transition temperature of an obtained cured product, and is excellent in adhesive force to a metal substrate, especially, a Cu (alloy) substrate.SOLUTION: A thermosetting epoxy resin composition contains the following components (A) to (F): (A) a crystalline epoxy resin; (B) a non-crystalline epoxy resin which is solid at 25°C; (C) a phenolic compound; (D) a nitrogen atom-containing curing accelerator; (E) a reaction inhibitor; and (F) an inorganic filler.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermosetting epoxy resin composition which gives a resin sheet having excellent flexibility before curing, storage stability and moldability. [Background technology]

[0002] Epoxy resin compositions have excellent adhesive strength, heat resistance, and electrical properties, and are therefore used as adhesives and sealants in fields such as electrical and electronic equipment parts and automotive parts.

[0003] In recent years, sheet-shaped sealing materials have been considered for the batch molding of large substrates and wafers. Since general sheet-shaped materials are prone to cracking, it has been reported that thermoplastic resins are blended into them (Patent Document 1). However, blending in thermoplastic resins reduces the glass transition temperature of the sheet material after curing, which has caused problems such as limited applications.

[0004] In addition, when the sheet material is stored in a freezer, the resin hardens and becomes easily cracked, so it is recommended to store it in a refrigerator or at room temperature. In order to improve storage stability, an epoxy resin composition has been proposed that uses a phenolic compound as a curing agent and a borate with a phosphorus compound as a curing accelerator (Patent Documents 2 and 3). Although the use of a borate with a phosphorus compound as a curing accelerator provides excellent storage stability, problems such as deterioration of moldability and insufficient adhesive strength with metal substrates have occurred. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-213391 A [Patent Document 2] Patent No. 6857836 [Patent Document 3] JP 2003-292732 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a thermosetting epoxy resin composition which has excellent flexibility before curing, excellent storage stability and moldability, and which has a high glass transition temperature of the obtained cured product and excellent adhesion to metal substrates, particularly Cu (alloy) substrates. [Means for solving the problem]

[0007] As a result of intensive research by the present inventors to solve the above problems, they have found that a thermosetting epoxy resin composition containing a crystalline epoxy resin, a non-crystalline epoxy resin that is solid at 25°C, a phenol compound, a nitrogen-containing curing accelerator, a reaction inhibitor and an inorganic filler can give a cured product which is excellent in flexibility, storage stability and moldability, as well as in heat resistance reliability and moisture resistance reliability, and have thus completed the present invention.

[0008] That is, the present invention provides a thermosetting epoxy resin composition containing the following components (A) to (F): <1> A thermosetting epoxy resin composition comprising the following components (A) to (F): (A) Crystalline epoxy resin (B) Amorphous epoxy resin that is solid at 25°C (C) Phenolic compounds (D) Nitrogen-containing curing accelerator (E) Reaction inhibitor (F) Inorganic filler <2> The component (E) is at least one selected from the group consisting of boric acid, a borate ester compound, and a phosphite ester compound. <1> The thermosetting epoxy resin composition according to claim 1. <3> The borate ester compound and the phosphite ester compound have a monovalent hydrocarbon group having 1 to 10 carbon atoms. <2> The thermosetting epoxy resin composition according to claim 1. <4> The (D) component is a urea-based curing accelerator or an imidazole-based curing accelerator. <1> ~ <3> 13. The thermosetting epoxy resin composition according to claim 12. <5> The blending amount of the (E) component is 0.01 to 5 parts by mass per 100 parts by mass of the total of the (A), (B), and (C) components. <1> ~ <4> 13. The thermosetting epoxy resin composition according to claim 12. <6> Component (F) is spherical silica. <1> ~ <5> 13. The thermosetting epoxy resin composition according to claim 12. <7> <1> ~ <6> 13. A thermosetting epoxy resin sheet obtained by forming the thermosetting epoxy resin composition according to any one of claims 1 to 12 into a sheet shape. <8> The thickness is 0.1 to 5 mm. <7> The thermosetting epoxy resin sheet according to claim 1. Effect of the Invention

[0009] The thermosetting epoxy resin composition of the present invention has excellent flexibility before curing, and therefore can be easily molded into a sheet, and can provide a cured product having excellent storage stability, heat resistance reliability, and moisture resistance reliability. Therefore, the thermosetting epoxy resin composition of the present invention is useful as a sheet-shaped sealing material for collectively molding large substrates or wafers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The thermosetting epoxy resin composition of the present invention will be described in more detail below.

[0011] (A) Crystalline epoxy resin The component (A) is an epoxy resin having crystallinity, and a known crystalline epoxy resin may be used. The crystalline epoxy resin may be any epoxy resin having crystallinity, without being limited by its molecular structure, molecular weight, etc. Examples include biphenyl type epoxy resins, bisphenol type epoxy resins, and stilbene type epoxy resins. These may be used alone or in combination of two or more. Bisphenol A type epoxy resins or bisphenol F type epoxy resins are preferred. In the present invention, the term "resin having crystallinity" refers to a resin that changes from a solid state to a liquid state at a temperature equal to or higher than its melting point, has high fluidity, and crystallizes at a temperature lower than its melting point. In particular, bisphenol A type epoxy resins or bisphenol F type epoxy resins that crystallize at room temperature, particularly those having a melting point of 40° C. or higher, are preferred.

[0012] In the thermosetting epoxy resin composition of the present invention, the blending amount of component (A) is preferably in the range of 5 to 35 parts by mass, more preferably 8 to 33 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of the total of components (A), (B), and (C). When the blending amount is 5 parts by mass or more, sufficient flexibility can be imparted to the sheet obtained by molding, and when the blending amount is 35 parts by mass or less, there is no risk of the tackiness becoming strong, the holding power as a sheet decreasing, or the glass transition temperature of the resin constituting the sheet becoming too low, while maintaining sufficient flexibility.

[0013] (B) Amorphous epoxy resin that is solid at 25°C Component (B) is a non-crystalline epoxy resin other than component (A) that is solid at 25° C., and any known epoxy resin can be used. The epoxy resin that is solid at 25° C. can be used without being limited by molecular structure, molecular weight, etc., so long as it is solid and non-crystalline at 25° C. Examples of the epoxy resin include biphenol-type epoxy resins such as amorphous bisphenol A type epoxy resins, amorphous bisphenol F type epoxy resins, 3,3',5,5'-tetramethyl-4,4'-biphenol type epoxy resins and 4,4'-biphenol type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, stilbene type epoxy resins, triazine skeleton-containing epoxy resins, fluorene skeleton-containing epoxy resins, trisphenol alkane type epoxy resins, biphenyl type epoxy resins, xylylene type epoxy resins, biphenyl aralkyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, alicyclic epoxy resins, diglycidyl ether compounds of polyfunctional phenols and polycyclic aromatics such as anthracene, phosphorus-containing epoxy resins obtained by introducing a phosphorus compound into these, and silicone-modified epoxy resins.

[0014] In the thermosetting epoxy resin composition of the present invention, the blending amount of the (B) component is preferably 15 to 75 parts by mass, and more preferably 20 to 70 parts by mass, per 100 parts by mass of the combined total of the (A), (B), and (C) components. The ratio of the amounts of the (A) and (B) components is preferably in the range of 30 to 90 parts by mass, more preferably 40 to 85 parts by mass, and even more preferably 50 to 85 parts by mass, of the (B) component relative to 100 parts by mass of the total of the (A) and (B) components. If it is 30 parts by mass or more, the moldability is good, and if it is 90 parts by mass or less, there is no risk of a decrease in the mechanical properties of the obtained cured product.

[0015] (C) Phenolic compounds The component (C) is a phenolic compound, and may be any known phenolic compound. The phenolic compound can be used without being limited by its molecular structure, molecular weight, etc. Examples of the phenolic compound include phenol novolac resin, cresol novolac resin, phenol aralkyl resin, naphthol aralkyl resin, trisphenol alkane resin, terpene modified phenolic resin, and dicyclopentadiene modified phenolic resin. These may be used alone or in combination of two or more. These phenolic compounds can be selected without being limited by their molecular weight, softening point, and amount of hydroxyl groups, but those with a low softening point and a relatively low viscosity are preferred.

[0016] The amount of component (C) in the thermosetting epoxy resin composition of the present invention is preferably an amount such that the molar ratio of phenolic hydroxyl groups in component (C) to the total mole of epoxy groups in components (A) and (B) is 0.5 to 2, and more preferably 0.7 to 1.5. If the molar ratio is within the above range, there is no risk of deterioration in the curability and mechanical properties of the thermosetting epoxy resin composition. In the thermosetting epoxy resin composition of the present invention, the total amount of the (A), (B) and (C) components is preferably 10 to 80 mass%, more preferably 15 to 70 mass%, and even more preferably 15 to 60 mass%.

[0017] (D) Nitrogen-containing curing accelerator Component (D) is a nitrogen atom-containing curing accelerator, which is blended for the purpose of accelerating the curing of the epoxy resins (Components (A) and (B)) and the phenolic compound (C). Examples of the curing accelerator include tertiary amine compounds such as triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, and 1,8-diazabicyclo[5.4.0]undecene-7; imidazole compounds (imidazole-based curing accelerators) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct; 1,1-dimethylurea, 1 Examples of urea-based curing accelerators include 1,3-trimethylurea, 1,1-dimethyl-3-ethylurea, 1,1-dimethyl-3-phenylurea, 1,1-diethyl-3-methylurea, 1,1-diethyl-3-phenylurea, 1,1-dimethyl-3-(3,4-dimethylphenyl)urea, 1,1-dimethyl-3-(p-chlorophenyl)urea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and N'-[3-[[[(dimethylamino)carbonyl]amino]methyl]-3,5,5-trimethylcyclohexyl]-N,N-dimethylurea.

[0018] The amount of the curing accelerator is preferably 0.05 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the total of components (A), (B), and (C). When the amount is 0.05 to 20 parts by mass, there is no risk of the balance of the heat resistance and moisture resistance of the cured product of the composition becoming poor, or the curing speed during molding becoming very slow or fast.

[0019] (E) Reaction inhibitor The (E) component is a reaction inhibitor, and is blended for the purpose of improving the storage stability of the thermosetting epoxy resin composition. The (E) component reaction inhibitor is not particularly limited, and any known reaction inhibitor can be used. Examples of the reaction inhibitor include boric acid, borate ester compounds, aluminum chelate compounds, phosphite compounds, and organic acids. Among them, borate ester compounds and phosphite compounds are preferred. Among the borate ester compounds and phosphite compounds, those having a monovalent hydrocarbon group having 1 to 10 carbon atoms are preferred.

[0020] Examples of borate ester compounds include trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, tripentyl borate, triallyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, trinonyl borate, tridecyl borate, tridodecyl borate, trihexadecyl borate, trioctadecyl borate, tris(2-ethylhexyloxy)borane, bis(1,4,7,10-tetraoxaundecyl)(1,4,7,10,13-pentaoxatetradecyl)(1,4,7-trioxaundecyl)borane, tribenzyl borate, triphenyl borate, tri-o-tolyl borate, tri-m-tolyl borate, and triethanolamine borate.

[0021] Examples of the aluminum chelate compound include triethyl aluminate, tripropyl aluminate, triisopropyl aluminate, tributyl aluminate, and trioctyl aluminate.

[0022] Examples of phosphite compounds include monomethyl phosphite, dimethyl phosphite, monoethyl phosphite, diethyl phosphite, monobutyl phosphite, dibutyl phosphite, monolauryl phosphite, dilauryl phosphite, monooleyl phosphite, dioleyl phosphite, monophenyl phosphite, diphenyl phosphite, mononaphthyl phosphite, dinaphthyl phosphite, di-o-tolyl phosphite, di-m-tolyl phosphite, di-p-tolyl phosphite, di-p-chlorophenyl phosphite, di-p-bromophenyl phosphite, di-p-fluorophenyl phosphite, and the like. These reaction inhibitors may be used either individually or in combination of two or more.

[0023] The amount of the reaction inhibitor (E) is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the total of the components (A), (B), and (C). When the amount is 0.01 to 5 parts by mass, there is no risk of the balance of the heat resistance and moisture resistance of the cured product of the composition becoming poor, or the curing speed during molding becoming extremely slow.

[0024] (F) Inorganic filler The component (F) is an inorganic filler, which is blended to increase the strength of the thermosetting epoxy resin composition of the present invention. As the inorganic filler of the component (F), those usually blended in epoxy resin compositions or silicone resin compositions can be used. For example, silicas such as spherical silica, fused silica, and crystalline silica; inorganic nitrides such as silicon nitride, aluminum nitride, and boron nitride; alumina, glass fibers, and glass particles can be mentioned. From the viewpoints of excellent reinforcing effect and suppression of warping of the obtained cured product, it is preferable that the component (F) contains silicas, and more preferably contains spherical silica.

[0025] The average particle size of the inorganic filler of component (F) is not particularly limited, but the average particle size is preferably 0.1 to 40 μm, and more preferably 0.5 to 40 μm. In the present invention, the average particle size is the mass average particle size D 50(or median diameter).

[0026] In addition, when producing the thermosetting epoxy resin composition of the present invention, a combination of inorganic fillers having a plurality of particle size ranges may be used as component (F) from the viewpoint of increasing the fluidity of the epoxy resin composition. In such a case, it is preferable to use a combination of spherical silica having a fine particle size range of 0.1 to 3 μm, a medium particle size range of 3 to 7 μm, and a coarse particle size range of 10 to 40 μm, and it is more preferable that the average particle size of the entire component (E) is in the range of 0.5 to 40 μm as a result of combining these. In order to further increase the fluidity, it is preferable to use spherical silica having an even larger average particle size.

[0027] (F) The inorganic filler is preferably surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. Examples of such coupling agents include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane, amino silanes such as γ-aminopropyltriethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane, and mercapto silanes such as γ-mercaptopropyltrimethoxysilane and γ-(thiiranylmethoxy)propyltrimethoxysilane. The amount of the coupling agent used in the surface treatment and the surface treatment method are not particularly limited.

[0028] The blending amount of the (F) inorganic filler is preferably 5 to 94 mass %, more preferably 10 to 92 mass %, still more preferably 20 to 90 mass %, and particularly preferably 50 to 90 mass %, based on the total mass of the thermosetting epoxy resin composition.

[0029] <Other additives> The epoxy resin composition of the present invention can be obtained by blending the above-mentioned components (A) to (F) in the prescribed amounts, and other additives can be added as necessary within the range that does not impair the object and effect of the present invention. Such additives include adhesion promoters, flame retardants, ion trapping agents, mold release agents, stress reducing agents, colorants, etc.

[0030] The flame retardant is added for the purpose of imparting flame retardancy, and any known flame retardant can be used without any particular limitation. Examples of the flame retardant include phosphazene compounds, silicone compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, and molybdenum oxide.

[0031] The adhesive aid is blended for the purpose of increasing the adhesiveness to silicon wafers, metal substrates, and organic substrates. There is no particular limitation, and known adhesive aids can be used. For example, coupling agents such as silane coupling agents and titanate coupling agents can be blended, and among them, silane coupling agents are preferred.

[0032] Examples of such coupling agents include epoxy-functional alkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino-functional alkoxysilanes such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; mercapto-functional alkoxysilanes such as γ-mercaptopropyltrimethoxysilane; and amine-functional alkoxysilanes such as γ-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0033] The ion trapping agent is added for the purpose of trapping ion impurities contained in the resin composition and preventing thermal deterioration and moisture absorption deterioration, and is not particularly limited and any known ion trapping agent can be used. Examples of the ion trapping agent include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides.

[0034] The release agent is added for the purpose of enhancing the releasability during molding, and any known release agent can be used without any particular limitation. Examples of the release agent include waxes such as carnauba wax, rice wax, polyethylene, polyethylene oxide, montanic acid, ester compounds of montanic acid with saturated alcohol, 2-(2-hydroxyethylamino)-ethanol, ethylene glycol, glycerin, etc.; stearic acid, stearic acid esters, stearic acid amide, ethylene bisstearic acid amide, copolymers of ethylene and vinyl acetate, etc., and one type may be used alone or two or more types may be used in combination.

[0035] The stress reducing agent is added for the purpose of reducing the stress of the thermosetting epoxy resin composition, and all known agents can be used without any particular limitation. Examples of the stress reducing agent include silicone compounds such as silicone oil, silicone resin, silicone modified epoxy resin, and silicone modified phenolic resin; thermoplastic elastomers such as styrene resin and acrylic resin; and the like, which may be used alone or in combination of two or more.

[0036] Method for producing thermosetting epoxy resin composition The thermosetting epoxy resin composition of the present invention is obtained by blending the above-mentioned epoxy resins (A) and (B), (C) phenol hardening compound, (D) nitrogen atom-containing curing accelerator, (E) reaction inhibitor, (F) inorganic filler and other additives in a predetermined composition ratio and mixing them thoroughly and uniformly with a mixer or the like. The epoxy resin composition is then molded into a sheet to obtain a thermosetting epoxy resin composition sheet. Molding can be performed, for example, by a T-die extrusion method using a twin-screw extruder equipped with a T-die at the tip. Alternatively, the thermosetting epoxy resin composition can be melted and mixed with a hot roll, kneader, extruder, etc., then cooled and solidified, and crushed to an appropriate size, and the crushed product can be heated and melted at 70 to 120 ° C. between pressure members, compressed and molded into a sheet. The thermosetting epoxy resin sheet of the present invention preferably has a thickness of 0.1 to 5.0 mm, more preferably 0.15 to 3.0 mm.

[0037] The sheet obtained from the thermosetting epoxy resin composition of the present invention has excellent flexibility before curing. The composition also has good handleability, and upon curing, a thermosetting epoxy resin sheet is obtained which has a high glass transition temperature and is also excellent in storage stability and moldability. The curing conditions for the thermosetting epoxy resin sheet of the present invention are not particularly limited. EXAMPLES

[0038] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0039] The raw materials used in the examples and comparative examples are shown below. (A) Crystalline epoxy resin (A1): Bisphenol A type epoxy resin (YL-6810: manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 170, melting point 45°C)

[0040] (B) Amorphous epoxy resin that is solid at 25°C (B1): Cresol novolac type epoxy resin (EPICLON N-665: manufactured by DIC Corporation, epoxy equivalent 210, softening point 65°C) (B2): Trisphenolmethane epoxy resin (EPPN-501H: manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 168, softening point 53°C) (B3): Biphenyl aralkyl type epoxy resin (NC-3000H: manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 272, softening point 70°C)

[0041] (C) Phenolic compounds (C1): Phenol novolac resin (BRG-555: manufactured by Aica Kogyo Co., Ltd., hydroxyl equivalent: 107) (C2): Trisphenolmethane resin (MEH-7500: manufactured by Meiwa Kasei Co., Ltd., hydroxyl equivalent: 97) (C3): Phenol biphenyl aralkyl resin (MEH-7851SS: manufactured by Meiwa Kasei Co., Ltd., hydroxyl equivalent 199)

[0042] (D) Nitrogen-containing curing accelerator (D1): 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ-PW, manufactured by Shikoku Chemical Industry Co., Ltd.) (D2): 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (2MAOK-PW, manufactured by Shikoku Chemical Industry Co., Ltd.) (D3): Aliphatic dimethylurea (U-CAT 3513N, San-Apro Co., Ltd.) (D') Nitrogen-free curing accelerator (for comparison) (D'1): Triphenylphosphine (TPP, manufactured by Hokko Chemical Industry Co., Ltd.)

[0043] (E) Reaction inhibitor (E1): Trimethylborate (TMB, manufactured by Daihachi Chemical Industry Co., Ltd.) (E2): Tri-n-butyl borate (TBB, manufactured by Daihachi Chemical Industry Co., Ltd.)

[0044] (F) Inorganic filler (F1): Spherical fused silica (fused spherical silica with a mass average particle size of 14 μm, manufactured by Tatsumori Co., Ltd.)

[0045] Other Ingredients Amine compound: 4,4'-diaminodiphenylmethane (DDM, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0046] <Examples 1 to 11 and Comparative Examples 1 to 5> The above components were premixed in a Henschel mixer in the proportions (parts by mass) shown in Table 1, and then a thermosetting epoxy resin composition was obtained using a twin-screw extruder. In the following examples and comparative examples, the amount of component (C) is such that the molar ratio of phenolic hydroxyl groups in component (C) to the total of 1 mole of epoxy groups in components (A) and (B) is 1.0.

[0047] [Flexibility of uncured resin sheet] The thermosetting epoxy resin composition obtained by the above method was molded into a sheet of 100 mm x 100 mm and 0.5 mm thick to prepare a thermosetting epoxy resin sheet, and a bending test was carried out on the sheet in an uncured state. The flexibility of the uncured resin sheet was evaluated by assigning an O to a sheet that could be folded in two without cracking, and an X to a sheet that cracked when folded. The results are shown in Table 1.

[0048] [Glass transition temperature] Using a mold conforming to the EMMI standard, molding temperature 175℃, molding pressure 6.9N / mm 2 The above 0.5 mm thick thermosetting epoxy resin sheet was cured under the conditions of 180 s molding time and 180 s post-curing at 180°C for 4 hours. The glass transition temperature and thermal expansion coefficient of test pieces made from the post-cured cured product were measured using a TMA (TMA8310, Rigaku Corporation). The heating program was set to a heating rate of 5°C / min, and a constant load of 49 mN was applied to the post-cured test piece. The dimensional change of the test piece was then measured between 25°C and 300°C. The relationship between the dimensional change and temperature was plotted on a graph. The glass transition temperatures of the examples and comparative examples were determined from the graph of dimensional change and temperature thus obtained. The results are shown in Table 1.

[0049] [Storage stability] The minimum melt viscosity of each thermosetting epoxy resin composition was measured at a temperature of 175°C using a high-temperature flow tester (manufactured by Shimadzu Corporation, product name: Flow Tester CFT-500) with a nozzle of 1 mm diameter under a pressure of 25 kgf. Furthermore, each thermosetting epoxy resin composition was placed in a thermostatic chamber set at 50°C, and the minimum melt viscosity after leaving for 72 hours was also measured under the same conditions. The percentage of the minimum melt viscosity after leaving for 72 hours at 50°C relative to the minimum melt viscosity immediately after production was taken as storage stability, and the results are shown in Table 1.

[0050] [Bending strength] According to JIS K6911, each thermosetting epoxy resin composition was transfer molded at 175°C for 180 seconds under a molding pressure of 6.9 MPa, and then post-cured at 180°C for 4 hours to obtain test pieces measuring 100 mm x 100 mm and 4 mm thick. The test pieces were subjected to a three-point bending test using an autograph manufactured by Shimadzu Corporation to determine the bending strength. The results are shown in Table 1.

[0051] [Adhesive strength] Each thermosetting epoxy resin composition of the Examples and Comparative Examples was transferred onto a Cu alloy (Olin C7025) substrate measuring 15 mm x 15 mm and 0.15 mm in thickness at 175°C for 180 seconds under a molding pressure of 6.9 MPa to form a molded product with a base area of ​​10 mm 2 After molding a 3.5 mm-high molded product, it was post-cured at 180°C for 4 hours to obtain a test piece. A shear force was then applied to the molded product at a shear rate of 0.2 mm / s using a die shear tester (manufactured by DAGE), and the shear strength (adhesive strength) was measured when the molded product peeled off from the substrate surface. The results are shown in Table 1.

[0052] [Table 1]

Claims

1. The following components (A) to (F): (A) Crystalline epoxy resin (B) Amorphous epoxy resin that is solid at 25°C (C) one or more phenolic compounds selected from phenol novolac resins, cresol novolac resins, phenol aralkyl resins, naphthol aralkyl resins, trisphenol alkane resins, terpene-modified phenolic resins, and dicyclopentadiene-modified phenolic resins; (D) Nitrogen-containing curing accelerator (E) Reaction inhibitor (F) Inorganic filler In the thermosetting epoxy resin composition, the total amount of the components (A), (B) and (C) is 10 to 80 mass %, the amount of component (A) is in the range of 5 to 35 parts by mass, the amount of component (B) is in the range of 15 to 75 parts by mass, the amount of component (D) is in the range of 0.05 to 20 parts by mass, and the amount of component (E) is in the range of 0.01 to 5 parts by mass, relative to 100 parts by mass combined of component (A), component (B), and component (C); The amount of component (C) blended is an amount such that the ratio of moles of phenolic hydroxyl groups in component (C) to the combined total of 1 mole of epoxy groups in components (A) and (B) is 0.5 to 2.

2. 2. The thermosetting epoxy resin composition according to claim 1, wherein the component (E) is at least one member selected from the group consisting of boric acid, a borate ester compound, and a phosphite ester compound.

3. 3. The thermosetting epoxy resin composition according to claim 2, wherein the borate ester compound and the phosphite ester compound have a monovalent hydrocarbon group having 1 to 10 carbon atoms.

4. 4. The thermosetting epoxy resin composition according to claim 1, wherein the component (D) is a urea-based curing accelerator or an imidazole-based curing accelerator.

5. 5. The thermosetting epoxy resin composition according to claim 1, wherein the component (F) is spherical silica.

6. A thermosetting epoxy resin sheet obtained by forming the thermosetting epoxy resin composition according to any one of claims 1 to 5 into a sheet.

7. The thermosetting epoxy resin sheet according to claim 6, having a thickness of 0.1 to 5 mm.

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