Epoxy resin composition

Abstract

To provide an epoxy resin composition which provides a cured product having excellent heat resistance and moisture resistance and is excellent in low-temperature curability and short time curing and generates less volatile components during curing.SOLUTION: There is provided an epoxy resin composition which comprises the following components (A) to (E): (A) 100 pts. mass of an epoxy resin having two or more epoxy groups in one molecule which is not modified with a silicone, (B) a thiol compound having 3 or more thiol groups in one molecule, (C) 0.5 to 100 pts. mass of a silicone-modified epoxy resin, (D) 1.0 to 200 pts. mass of a microcapsule type curing accelerator and (E) 0.05 to 10 pts. mass of a reaction inhibitor, wherein the amount of the component (B) is an amount such that the molar equivalent ratio of the thiol group in the component (B) is 0.1 to 1.0 to the total molar equivalent amount of epoxy groups in the component (A) and the component (C).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an epoxy resin composition, more specifically to an epoxy resin composition containing a thiol compound. [Background technology]

[0002] Epoxy resin compositions have excellent adhesive strength, heat resistance, and electrical properties, and are therefore used as adhesives and sealants in the fields of electrical and electronic equipment parts, automotive parts, etc. In recent years, there has been a demand for epoxy resin compositions that can be cured at low temperatures and in a short time in order to suppress deterioration of parts under high-temperature conditions and to improve productivity.

[0003] Thiol-based curing agents are known as curing agents for epoxy resin compositions that can be cured at low temperatures in a short time. For example, Patent Document 1 and Patent Document 2 describe compositions having an epoxy resin and a thiol compound. Patent Document 1 describes a resin composition that includes a compound that has four thiol groups in the compound and acts as a curing agent for epoxy resins that do not have ester bonds, an epoxy resin, a curing accelerator, and a silane coupling agent. Patent Document 1 describes that the thiol compound does not hydrolyze in a high-temperature and high-humidity environment, and is less likely to cause a decrease in adhesive strength. Patent Document 2 describes a resin composition that includes an epoxy resin, an ester structure-containing polythiol compound, and a carbodiimide. It describes that the resin composition has excellent moisture resistance. In the compositions described in Patent Documents 3 and 4, a thiol-based curing agent is used as a curing agent, and a microcapsule-type curing agent is used as a curing accelerator, thereby enabling short-time curing at low temperatures and storage stability.

[0004] However, as described in these patent documents, conventional epoxy resin compositions containing thiol-based curing agents can be cured at low temperatures, but they require a long time to cure, so they cannot be said to have sufficient curability. In addition, conventional epoxy resin compositions containing thiol-based curing agents can be cured at high temperatures in a short time from the viewpoint of improving productivity, but they are not satisfactory in terms of handleability because voids are generated in the cured product and the substrate is contaminated by the volatile components of the resin. Furthermore, conventional epoxy resin compositions containing thiol-based curing agents have low Tg and insufficient heat resistance, and the adhesive strength is significantly reduced after storage under high temperature and high humidity conditions, so they are not satisfactory in terms of reliability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6534189 [Patent Document 2] JP 2019-123825 A [Patent Document 3] International Publication No. 2017 / 057019 [Patent Document 4] Patent Publication No. 2021-38314 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide an epoxy resin composition which gives a cured product having excellent heat resistance and moisture resistance, has excellent low-temperature curing properties and short-time curing properties, and produces a small amount of volatile components during curing. [Means for solving the problem]

[0007] As a result of intensive research by the inventors to solve the above problems, they have discovered that in an epoxy resin composition comprising an epoxy resin, a thiol compound, a silicone-modified epoxy resin, a microcapsule-type curing accelerator, and a reaction inhibitor, by blending a specific amount of a specific thiol compound having three or more thiol groups in one molecule, the resulting composition has excellent low-temperature curing properties and short-time curing properties, produces little volatile components during curing, and gives a cured product having excellent heat resistance and moisture resistance, thereby completing the present invention.

[0008] That is, the present invention provides the following epoxy resin composition, etc.

[0009] [1] An epoxy resin composition comprising the following components (A) to (E): (A) 100 parts by mass of a non-silicone-modified epoxy resin having two or more epoxy groups in one molecule (B) A thiol compound having three or more thiol groups in one molecule (C) Silicone-modified epoxy resin: 0.5 to 100 parts by mass (D) Microcapsule type hardening accelerator 1.0 to 200 parts by mass (E) Reaction inhibitor 0.05 to 10 parts by mass However, the amount of component (B) is such that the molar equivalent ratio of thiol groups in component (B) to 1 molar equivalent of the total epoxy groups in components (A) and (C) is 0.1 to 1.0. [2] The epoxy resin composition according to [1], wherein the component (B) is a thiol compound having four or more thiol groups in one molecule. [3] The epoxy resin composition according to [1] or [2], wherein the molar equivalent ratio of thiol groups in component (B) per 1 molar equivalent of total epoxy groups in components (A) and (C) is 0.1 to 0.5. [4] The epoxy resin composition according to any one of [1] to [3], wherein the component (D) is a microcapsule-type curing accelerator containing at least one selected from the group consisting of phosphorus compounds, tertiary amine compounds, imidazole compounds, urea compounds, and amine adduct compounds. [5] The epoxy resin composition according to any one of [1] to [4], wherein the component (E) is a borate compound and / or a phosphite compound. [6] The epoxy resin composition according to any one of [1] to [5], wherein the volume average particle size of component (D) is 0.1 to 10 μm. Effect of the Invention

[0010] The epoxy resin composition of the present invention has excellent low-temperature curing properties and short-time curing properties, produces a small amount of volatile components during curing, and gives a cured product having excellent heat resistance and moisture resistance. Therefore, the epoxy resin composition of the present invention is useful as an adhesive, a sealant, etc. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an example of a graph plotting the relationship between temperature and dimensions of a test piece measured for dimensional changes at temperatures between 25° C. and 300° C. in an example, and illustrates a method for determining the glass transition temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The epoxy resin composition of the present invention comprises an epoxy resin, a thiol compound, a silicone-modified epoxy resin, a microcapsule-type curing accelerator, and a reaction inhibitor, and is characterized in that the thiol compound has three or more thiol groups in one molecule. The present invention will be described in detail below.

[0013] (A) Non-silicone-modified epoxy resin The epoxy resin (A) is the main component of the present invention, is not silicone-modified, and has two or more epoxy groups in one molecule. Furthermore, it is preferable that the epoxy resin has one or more aromatic rings in one molecule.

[0014] The epoxy resin may be any conventionally known epoxy resin as long as it has two or more, preferably three or more, epoxy groups in one molecule, provided that the epoxy resin is an epoxy resin other than a silicone-modified epoxy resin. Examples of the epoxy resin of the component (A) include bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, and bisphenol S type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, and bisphenol F novolac type epoxy resins; alicyclic epoxy resins such as dicyclopentadiene type epoxy resins and 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate; polyfunctional phenol type epoxy resins such as resorcinol type epoxy resins and resorcinol 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, and diglycidyl ether compounds of polycyclic aromatics such as anthracene; and phosphorus-containing epoxy resins obtained by introducing a phosphorus compound into these. These can be used alone or in combination of two or more.

[0015] The component (A) preferably has a viscosity of 10 to 100,000 mPa·s, and more preferably 20 to 50,000 mPa·s at 25° C. The viscosity is a value measured using a B-type viscometer in accordance with JIS K 7117-1:1999.

[0016] The amount of the component (A) is preferably 4 to 60 mass %, more preferably 8 to 55 mass %, and further preferably 12 to 50 mass %, based on the total mass of the epoxy resin composition.

[0017] (B) A thiol compound having three or more thiol groups in one molecule The component (B) is a polythiol compound that acts as a curing agent for epoxy resins, that is, a curing agent for the component (A) and the component (C) described below. The polythiol compound has high low-temperature curing properties and cures epoxy resins at low temperatures in a short time. The component (B) is characterized by having three or more thiol groups in one molecule, preferably four or more thiol groups in one molecule, and more preferably four to six thiol groups in one molecule. If the number of thiol groups in one molecule is two or less, the glass transition temperature of the resulting cured product is low and the heat resistance and moisture resistance are poor, which is not preferred.

[0018] Examples of the polythiol compound include polythiol compounds such as aliphatic polythiol compounds, aromatic polythiol compounds, polythiol compounds having an ether bond, polythiol compounds having an ester bond, and mercaptoalkylglycoluril compounds. Examples of polythiol compounds having an ester bond include trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. Examples of the mercaptoalkyl glycoluril compound include 1,3,4,6-tetrakis(mercaptomethyl) glycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl) glycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl) glycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a-methyl glycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a-methyl glycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a-methyl glycoluril, and 1,3,4,6-tetrakis(mercaptomethyl)-3a-methyl glycoluril. Examples of the mercaptopropyl ether uril include, but are not limited to, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a,6a-dimethylglycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-dimethylglycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a,6a-diphenylglycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a,6a-diphenylglycoluril, and 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-diphenylglycoluril. These may be used alone or in combination of two or more.

[0019] The epoxy resin composition of the present invention is characterized in that the polythiol compound is contained in an amount such that the molar equivalent ratio of the thiol group in the polythiol compound is 0.1 to 1.0 relative to 1 molar equivalent of all epoxy groups in the (A) component and the (C) component described later. The molar equivalent ratio is preferably 0.1 to 0.8, more preferably 0.1 to 0.5, even more preferably 0.2 to 0.5, and particularly preferably 0.2 to 0.4. If the ratio is less than 0.1, the low-temperature curing property may be impaired, unreacted epoxy groups may remain, and the glass transition temperature may decrease or the adhesion may decrease. If the ratio exceeds 1.0, unreacted thiol groups may remain, and cracks may occur during reflow or temperature cycle. In the present invention, the term "equivalent" refers to the molecular weight per functional group. The term "thiol equivalent" refers to the active hydrogen equivalent. The above-mentioned equivalent ratio (molar equivalent ratio) refers to the ratio of the thiol equivalent (active hydrogen equivalent) in the (B) thiol compound to 1 equivalent of epoxy contained in the (A) component and the (C) component, and the (B) thiol compound may be blended in an amount that contains thiol active hydrogen and provides an equivalent ratio of 0.1 to 1.0, preferably within the above-mentioned range.

[0020] (C) Silicone-modified epoxy resin The component (C) is a silicone-modified epoxy resin. The silicone-modified epoxy resin improves the curability and moisture resistance reliability of the epoxy resin composition. The silicone-modified epoxy resin may be a copolymer obtained by reacting an alkenyl-containing epoxy resin with an organohydrogenpolysiloxane. Examples of the alkenyl-containing epoxy resin include those represented by the following formulas (1) to (3). [ka] [ka] [ka]

[0021] In the above formulas (1) to (3), R 1 is a glycidyl group (2,3-epoxypropyl group), X is independently a hydrogen atom or a bromine atom, n is a number of 0 or more, preferably a number of 0 to 50, and more preferably a number of 1 to 20. m is an integer of 0 or more, preferably a number of 1 to 5, and more preferably 1.

[0022] The organohydrogenpolysiloxane may be a compound represented by the following average composition formula (4). H a (R 2 ) b SiO (4-a-b) / 2 (4)

[0023] In the above formula (4), R 2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxy group, an alkoxy group having 1 to 10 carbon atoms, or an alkenyloxy group having 2 to 10 carbon atoms. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, decyl group, etc., aryl groups such as phenyl group, tolyl group, etc., aralkyl groups such as benzyl group, phenylethyl group, etc., and halogen-substituted monovalent hydrocarbon groups in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with halogen atoms, etc. Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, isopropoxy group, n-hexyloxy group, etc. Examples of the alkenyloxy group include vinyloxy group, propenoxy group, isopropenoxy group, etc.

[0024] In the above formula (4), a and b are numbers satisfying 0.001 ≦ a ≦ 1, 1 ≦ b ≦ 3, and 1 < a + b ≦ 4, preferably 0.01 ≦ a ≦ 0.1, 1.8 ≦ b ≦ 2, and 1.85 ≦ a + b ≦ 2.1.

[0025] The organohydrogenpolysiloxane represented by the above formula (4) desirably has 1 to 1,000 silicon atoms, preferably 2 to 400 silicon atoms, more preferably 5 to 200 silicon atoms in one molecule. Examples of the organohydrogenpolysiloxane include the compounds represented by formula (5).

Chemical formula

[0026] In the above formula (5), R 2It is the same as described above, preferably a methyl group or a phenyl group. p is a number from 0 to 1,000, preferably a number from 3 to 400, q is a number from 0 to 20, preferably a number from 0 to 5, and more preferably q = 0. Further, p + q satisfies 1 < p + q ≤ 1,000, preferably 2 < p + q < 400, and even more preferably 5 < p + q < 200.

[0027] Examples of such organohydrogenpolysiloxanes include compounds of the following formula.

Chemical formula

[0028] The organohydrogenpolysiloxane preferably has a weight average molecular weight of 100 to 100,000, more preferably 500 to 20,000. When the weight average molecular weight of the organohydrogenpolysiloxane is within the above range, depending on the structure or weight average molecular weight of the alkenyl group-containing epoxy resin reacted with the organohydrogenpolysiloxane, a uniform structure in which the organohydrogenpolysiloxane is uniformly dispersed in the matrix or a sea-island structure in which the organohydrogenpolysiloxane forms fine layer separation in the matrix appears.

[0029] When the weight average molecular weight of the organohydrogenpolysiloxane is relatively small, especially when it is 100 to 10,000, a uniform structure is formed. Also, when the weight average molecular weight of the organohydrogenpolysiloxane is relatively large, especially when it is 10,000 to 100,000, a sea-island structure is formed. Either the uniform structure or the sea-island structure may be selected according to the application. When the weight average molecular weight of the organohydrogenpolysiloxane is less than 100, the resulting cured product becomes rigid and brittle, which is not preferable. Also, when the weight average molecular weight of the organohydrogenpolysiloxane is greater than 100,000, the sea-island structure becomes large and local stress is generated in the resulting cured product, which is not preferable.

[0030] In this specification, the weight average molecular weight is a weight average molecular weight measured by gel permeation chromatography (GPC) using polystyrene as a standard substance, and is a value measured under the following conditions. [GPC measurement conditions] Developing solvent: Tetrahydrofuran Flow rate: 0.6mL / min Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 20 μL (sample concentration: 0.5% by mass in tetrahydrofuran solution) Detector: Differential refractometer (RI)

[0031] The method of reacting the alkenyl group-containing epoxy resin with the organohydrogenpolysiloxane can be a known method, for example, a method of adding the alkenyl group-containing epoxy resin with the organohydrogenpolysiloxane in the presence of a platinum catalyst. In this way, a silicone-modified epoxy resin can be obtained. The organohydrogenpolysiloxane is preferably copolymerized in an amount such that the SiH group of the organohydrogenpolysiloxane is 0.1 to 1 mole per mole of the alkenyl group of the alkenyl group-containing epoxy resin.

[0032] The amount of the silicone modified epoxy resin (C) in the composition of the present invention is 0.5 to 100 parts by mass, preferably 1 to 80 parts by mass, and more preferably 2 to 60 parts by mass, per 100 parts by mass of the component (A).

[0033] (D) Microcapsule type hardening accelerator The (D) component is a microcapsule type curing accelerator that accelerates the reaction between the epoxy resins (A) and (C) and the thiol compound (B). The curing accelerator (catalyst) used as an active ingredient in the core material (core particle) of the microcapsule preferably has a reaction temperature (i.e., a temperature at which catalytic action is exerted) of 50°C or higher so as to exhibit storage stability and rapid curing at a low temperature above a certain temperature. Examples of such curing accelerators include phosphorus compounds, tertiary amine compounds, imidazole compounds, urea compounds, and amine adduct compounds.

[0034] Examples of the phosphorus compound include triorganophosphine compounds such as tributylphosphine, triphenylphosphine, tri(methylphenyl)phosphine, tri(nonylphenyl)phosphine, tri(methoxyphenyl)phosphine, diphenyltolylphosphine, triphenylphosphine·triphenylborane, and quaternary phosphonium salts such as tetraphenylphosphonium·tetraphenylborate. Among these, triphenylphosphine and tri(methylphenyl)phosphine are preferred.

[0035] Examples of the tertiary amine compound include amine compounds having an alkyl group or an aralkyl group as a substituent bonded to a nitrogen atom, such as triethylamine, benzyldimethylamine, benzyltrimethylamine, and α-methylbenzyldimethylamine; cycloamidine compounds such as 1,8-diazabicyclo[5.4.0]undecene-7 and 1,4-diazabicyclo[2.2.2]octane, and their phenol salts, octylate salts, and oleate salts, and their salts with organic acids and salts or complex salts of quaternary boron compounds. Among these, 1,8-diazabicyclo[5.4.0]undecene-7 and 1,4-diazabicyclo[2.2.2]octane are preferred.

[0036] Examples of the imidazole compound include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2,4-dimethylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 1,2-diethylimidazole, 2-phenyl-4-methylimidazole, 2,4,5-triphenylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-allyl-4,5-diphenylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Among these, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole, 1,2-dimethylimidazole, 1,2-diethylimidazole, 2,4-dimethylimidazole and 2-phenyl-4-methylimidazole are preferred.

[0037] Examples of the urea compound include N,N-dimethyl-N'-phenylurea, N,N-dimethyl-N'-(3,4-dichlorophenyl)urea, 4,4'-methylenebis(phenyldimethylurea), aromatic dimethylurea compounds, aliphatic dimethylurea compounds, toluenebisdimethylurea, dimethylaminocarboxylaminomethyltrimethylcyclohexyldimethylurea, etc. Among these, aromatic dimethylurea compounds and aliphatic dimethylurea compounds are preferred.

[0038] Examples of the amine adduct compound include a compound having an amino group obtained by reacting at least one compound selected from the group consisting of a carboxylic acid compound, a phenol compound, an isocyanate compound, and an epoxy resin with an amine compound.

[0039] Examples of the carboxylic acid compound include succinic acid, adipic acid, sebacic acid, phthalic acid, and dimer acid.

[0040] Examples of the phenol compound include monophenols such as phenol, cresol, xylenol, carvacrol, motil, and naphthol, and polyphenols such as catechol, resorcin, hydroquinone, bisphenol A, bisphenol F, pyrogallol, and phloroglucin.

[0041] Examples of the isocyanate compound include ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4-4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane, 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, and 1,5-naphthalene diisocyanate.

[0042] Examples of the epoxy compound include butyl glycidyl ether, hexyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, para-tert-butylphenyl glycidyl ether, paraxylyl glycidyl ether, bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, and bisphenol S type epoxy resins, novolac type epoxy resins such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, and bisphenol F novolac type epoxy resins, dicyclopentadiene type epoxy resins, 3,4-epoxy resins, and the like. Examples of epoxy resins include alicyclic epoxy resins such as 3',4'-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate, polyfunctional phenolic epoxy resins such as resorcinol-type epoxy resins and resorcinol novolac-type epoxy resins, stilbene-type epoxy resins, triazine skeleton-containing epoxy resins, fluorene skeleton-containing epoxy resins, triphenol alkane-type epoxy resins, biphenyl-type epoxy resins, xylylene-type epoxy resins, biphenyl aralkyl-type epoxy resins, naphthalene-type epoxy resins, and diglycidyl ether compounds of polycyclic aromatics such as anthracene, as well as phosphorus-containing epoxy resins obtained by introducing a phosphorus compound into these.

[0043] Examples of the amine compound include methylamine, ethylamine, propylamine, butylamine, ethylenediamine, 1,2-propanediamine, tetramethyleneamine, 1,5-diaminopentane, hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2,2,4-triethylhexamethyldiamine, 1,2-diaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentane, cyclohexylamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, aminoethylpiperazine, diethylaminopropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, and piperazine.

[0044] Among these, amine adduct compounds obtained by reacting an isocyanate resin or an epoxy resin with an amine compound are preferred.

[0045] These curing accelerators may be used either individually or in combination of two or more.

[0046] The shell material for microencapsulating the curing accelerator must have a melting point of 50 to 90° C. from the viewpoint of maintaining storage stability and ensuring fast curing. The material of the shell material is not particularly limited as long as it has such a melting point, and all known materials can be used, for example, (meth)acrylic monomers, such as alkyl esters having 1 to 8 carbon atoms such as acrylic acid esters, itaconic acid esters, crotonic acid esters, etc.; alkyl esters in which the alkyl group of the alkyl ester has a substituent such as an allyl group; monofunctional monomers such as styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, etc.; and polymers obtained by (co)polymerizing one or more monomers selected from polyfunctional monomers such as ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, divinylbenzene, bisphenol A di(meth)acrylate, and methylene bis(meth)acrylamide. Among these, polymers of (meth)acrylate monomers are preferred.

[0047] The microcapsule-type hardening accelerator of component (D) is a microcapsule containing a hardening accelerator such as an imidazole compound or a tertiary amine compound as a core component in such a shell material, and the manufacturing method thereof includes, but is not limited to, the following methods (a) to (c).

[0048] (a) A method in which a shell material and core particles of a microcapsule-type hardening accelerator are dissolved or dispersed in a solvent that is a dispersion medium, and then the solubility of the shell material in the dispersion medium is reduced to precipitate the shell on the surface of the core particles of the microcapsule-type hardening accelerator.

[0049] (b) A method in which core particles of a microcapsule-type hardening accelerator are dispersed in a dispersion medium, and the above-mentioned shell material is added to the dispersion medium to precipitate on the core particles of the microcapsule-type hardening accelerator.

[0050] (c) A method in which the above shell material is added to a dispersion medium, and the surface of the core particle of the microcapsule-type hardening accelerator is used as a reaction site to form a shell there.

[0051] Examples of the dispersion medium used in the above production methods (a) to (c) include solvents and resins. Examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, propylene glycol monomethyl ethyl ether acetate, benzene, toluene, xylene, cyclohexane, methanol, ethanol, isopropanol, n-butanol, butyl carbitol, and water. Examples of the resins include epoxy resins, phenolic resins, maleimide resins, cyanate ester resins, and silicone resins. Among these, aromatic hydrocarbons such as toluene and alcohols such as n-butanol are preferred as dispersion media with good dispersibility.

[0052] The microcapsule type curing accelerator obtained by such a method preferably has an average particle size of 0.1 to 10 μm, particularly 1 to 5 μm. If the average particle size is too small, the specific surface area becomes large, and there is a risk that the viscosity of the epoxy resin composition becomes high when mixed. If the average particle size exceeds 10 μm, the dispersion in the epoxy resin composition becomes non-uniform, which may cause a decrease in reliability. The average particle size is a volume average particle size measured by a laser diffraction method.

[0053] The blending amount of the (D) component is 1.0 to 200 parts by mass, and more preferably 5 to 150 parts by mass, per 100 parts by mass of the above-mentioned (A) epoxy resin. When the blending amount of the (D) component is 1.0 to 200 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.

[0054] (E) Reaction inhibitor (E) The reaction inhibitor is added for the purpose of improving storage stability, and is not particularly limited, and any known one can be used. Examples of the reaction inhibitor include boric acid ester compounds, aluminum chelate compounds, phosphorous acid ester compounds, organic acids, etc. Among them, boric acid ester compounds and phosphorous acid ester compounds are preferred.

[0055] Examples of borate 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, triethanolamine borate, etc. Among these, triisopropyl borate is preferred.

[0056] Examples of the aluminum chelate compound include triethyl aluminate, tripropyl aluminate, triisopropyl aluminate, tributyl aluminate, and trioctyl aluminate.

[0057] Examples of the phosphite ester compound include phosphorous acid, 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, and di-p-fluorophenyl phosphite. Among these, phosphorous acid is preferred. These reaction inhibitors can be used alone or in combination of two or more.

[0058] The blending amount of the (E) component is 0.05 to 10 parts by mass, more preferably 0.05 to 5, and even more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the above-mentioned (A) epoxy resin. When the blending amount of the (E) component is 0.05 to 10 parts by mass, the reaction suppression effect is sufficiently obtained, and furthermore, there is no risk of a decrease in Tg or a decrease in bending strength due to insufficient curing.

[0059] Other Additives The epoxy resin composition of the present invention can be obtained by blending the above-mentioned components (A) to (E) 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 inorganic fillers, flame retardants, ion trapping agents, antioxidants, adhesion promoters, stress reducing agents, colorants, and coupling agents.

[0060] The inorganic filler is added for the purpose of reducing the thermal expansion coefficient of the epoxy resin composition and improving the moisture resistance reliability. The inorganic filler is preferably spherical. In this specification, "spherical" refers to particles having an aspect ratio of 2.0 or less, preferably 1.5 or less. By using spherical particles of the inorganic filler, the viscosity of the epoxy resin composition can be further reduced, and an epoxy resin that is liquid at 25°C can be suitably provided.

[0061] Examples of inorganic fillers include silicas such as fused silica, crystalline silica, and cristobalite; metal oxides such as aluminum oxide, titanium oxide, and magnesium oxide; and nitrides such as silicon nitride, aluminum nitride, and boron nitride. Among them, silicas are preferably used in consideration of the availability of materials and the stability of quality. The average particle size of these inorganic fillers is preferably 0.01 to 50 μm, more preferably 0.05 to 30 μm, and can be selected according to the application. The average particle size may be, for example, the volume average particle size measured by a laser diffraction method. The type of inorganic filler can be used alone or in combination of two or more types.

[0062] In order to strengthen the bond strength between the resin component and the inorganic filler, 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, a 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 for the surface treatment and the surface treatment method are not particularly limited. The coupling agent may be added separately to the composition of the present invention as component (F).

[0063] The content of the inorganic filler in the composition of the present invention is preferably 20 to 1,200 parts by mass, more preferably 50 to 1,000 parts by mass, and even more preferably 100 to 800 parts by mass, per 100 parts by mass of the total of the above (A) to (E).

[0064] 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.

[0065] 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.

[0066] The amount of the other components added varies depending on the application of the epoxy resin composition of the present invention, but usually the total amount is 5% by mass or less of the entire composition.

[0067] Method for producing epoxy resin composition The method for producing the epoxy resin composition of the present invention is not particularly limited. For example, a composition can be obtained by mixing, stirring, dissolving and / or dispersing (A) a silicone-unmodified epoxy resin, (B) a thiol compound, (C) a silicone-modified epoxy resin, (D) a microcapsule-type curing accelerator and (E) a reaction inhibitor, either simultaneously or separately, while optionally carrying out a heat treatment. Depending on the application, at least one of other additives such as inorganic fillers, flame retardants, ion trapping agents and coupling agents can be added and mixed into the mixture of components (A) to (E) to obtain the epoxy resin composition of the present invention.

[0068] The epoxy resin composition of the present invention is preferably liquid at 25° C. The viscosity of the composition is preferably 1 to 650 Pa·s, more preferably 5 to 500 Pa·s at 25° C. The viscosity is measured using an E-type viscometer in accordance with JIS Z 8803:2011.

[0069] The method for producing the composition and the device for mixing, stirring and dispersing are not particularly limited. For example, a mortar and pestle machine equipped with a stirring and heating device, a two-roll mill, a three-roll mill, a ball mill, a planetary mixer, a mass colloider, or the like can be used, and these devices may be used in appropriate combination. The curing conditions of the epoxy resin composition are not particularly limited, but for example, the composition may be heated at a temperature in the range of 60 to 200°C, preferably 80 to 180°C, for 30 minutes to 10 hours, preferably 1 to 5 hours. The epoxy resin composition of the present invention can be cured at a low temperature and in a short time. Therefore, the composition can be cured well even at a temperature in the range of 70°C to 130°C for about 10 minutes to 2 hours. EXAMPLES

[0070] 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.

[0071] The components used in the examples and comparative examples are as follows. (A) Non-silicone-modified epoxy resin (A1) Epoxy resin: a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin (ZX1059, viscosity at 25°C 1,900 to 2,600 mPa·s: manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) (A2) Epoxy resin: naphthalene type epoxy resin (HP4032D, viscosity 25 Pa s at 25°C: manufactured by DIC Corporation)

[0072] (B) Thiol Compound (B1) Thiol compound: 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril (TS-G, manufactured by Shikoku Chemical Industry Co., Ltd.) (B2) Thiol compound: 1,3,4,6-tetrakis(3-mercaptopropyl)glycoluril (C3TS-G, manufactured by Shikoku Chemical Industry Co., Ltd.) (B3) Thiol compound: pentaerythritol tetrakis(3-mercaptobutyrate) (Karenz MT PE1, manufactured by Showa Denko K.K.) (B4) Thiol compound: 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (Kalends MT NR1, Showa Denko K.K.) (B5) Comparative thiol compound: tetraethylene glycol bis(3-mercaptopropionate) (EGMP-4, manufactured by SC Organic Chemicals)

[0073] (C) Silicone-modified epoxy resin A 1-liter four-neck flask equipped with a reflux condenser, a thermometer, a stirrer, and a dropping funnel was charged with the following formula (6): [ka] 200 g of phenol novolak resin (phenol equivalent 125, allyl equivalent 1,100) modified with allyl glycidyl ether represented by the formula (II), 800 g of chloromethyloxirane, and 0.6 g of cetyltrimethylammonium bromide were added and heated, and stirred and mixed at a temperature of 110° C. for 3 hours. The mixture was cooled to a temperature of 70° C. and reduced in pressure to 160 mmHg, and then 128 g of a 50% aqueous solution of sodium hydroxide was added dropwise thereto over a period of 3 hours while azeotropically dehydrating. The resulting contents were reduced in pressure to distill off the solvent, and then dissolved in a mixed solvent of 300 g of methyl isobutyl ketone and 300 g of acetone, washed with water, and the solvent was removed under reduced pressure to obtain a product represented by the formula (7) below. [ka] An allyl group-containing epoxy resin (allyl equivalent: 1590, epoxy equivalent: 190) was obtained. This epoxy resin was mixed with 170 g of methyl isobutyl ketone, 330 g of toluene, and 0.07 g of a 2-ethylhexanol-modified chloroplatinic acid solution having a platinum concentration of 2% by mass, and subjected to azeotropic dehydration for 1 hour. The mixture was heated at reflux temperature to obtain a mixture of the following formula (8): [ka] 133 g of organopolysiloxane (weight average molecular weight 8000) represented by the formula was added dropwise over a period of 30 minutes. After further stirring and reaction at the same temperature for 4 hours, the resulting contents were washed with water and the solvent was distilled off under reduced pressure to obtain a yellowish-white opaque solid copolymer. The epoxy equivalent was 280, the ICI melt viscosity at 150°C measured using a cone / plate viscometer in accordance with ASTM D4287 was 800 mPa·s, and the silicon content was 31 mass%.

[0074] (D) Microcapsule type hardening accelerator (D1) Tertiary amine microcapsule type curing accelerator (HX5945HP, average particle size 2 μm, manufactured by Asahi Kasei Corporation) (D2) Imidazole-based microcapsule type curing accelerator (HX9322HP, average particle size 2 μm, manufactured by Asahi Kasei Corporation) (D3) Imidazole-based microcapsule type curing accelerator (HX3941HP, average particle size 5 μm, manufactured by Asahi Kasei Corporation) Curing accelerator for comparison (non-microcapsule type curing accelerator) (D4) 2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ-PW, manufactured by Shikoku Kasei Co., Ltd.) (D5) Amine-epoxy adduct-based latent curing catalyst (product name: Fujicure FXR-1081, manufactured by T&K TOKA Corporation)

[0075] (E) Reaction inhibitor (E1) Triisopropyl borate (Tokyo Chemical Industry Co., Ltd.) (E2) Phosphorous acid (Tokyo Chemical Industry Co., Ltd.)

[0076] (F) Other additives (F1) Silane coupling agent: γ-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0077] The above components were mixed in the amounts (parts by mass) shown in Tables 1 and 2 to obtain epoxy resin compositions. Each composition and the cured product obtained by curing each composition were evaluated for viscosity, storage stability, adhesive strength, glass transition temperature (Tg), heat resistance, moisture resistance, and drop resistance by the methods shown below. The results are shown in Tables 1 and 2. The "molar equivalent ratio" shown in Tables 1 and 2 refers to the ratio of the thiol equivalent (active hydrogen equivalent) in component (B) to the epoxy equivalent in components (A) and (C), and means molar equivalent.

[0078] (1) Viscosity measurement The epoxy resin compositions obtained in Examples 1 to 17 and Comparative Examples 1 to 7 were all liquid at 25° C. In accordance with JIS Z 8803:2011, a sample was set at a measurement temperature of 25° C. using an E-type viscometer, and the viscosity was measured 2 minutes later (initial viscosity).

[0079] (2) Confirmation of storage stability The viscosity of each epoxy resin composition after 24 hours at 25° C. was measured in the same manner as above. The rate of change (%) of the viscosity after 24 hours relative to the initial viscosity was determined to evaluate the storage stability.

[0080] (3) Adhesive strength after low-temperature curing Each epoxy resin composition of the Examples and Comparative Examples was poured into a mold to obtain a truncated cone-shaped test piece with an upper diameter of 2 mm, a lower diameter of 5 mm, and a height of 3 mm. The test piece was placed on an aluminum plate and cured at 80°C for 10 minutes. After curing, the test piece was cooled to room temperature and the shear adhesive strength was measured.

[0081] (4) Adhesive strength after high temperature curing Each epoxy resin composition of the Examples and Comparative Examples was poured into a mold to obtain a truncated cone-shaped test piece with an upper diameter of 2 mm, a lower diameter of 5 mm, and a height of 3 mm. The test piece was placed on an aluminum plate and cured at 180°C for 10 seconds. After curing, the test piece was cooled to room temperature and the shear adhesive strength was measured.

[0082] Preparation of cured sample Each of the epoxy resin compositions of the Examples and Comparative Examples was heat-cured at 80° C. for 1 hour and then at 120° C. for 1 hour, and molded to obtain a cured product.

[0083] (5) Measurement of glass transition temperature (Tg) The cured products obtained above were processed into test pieces of 5×5×15 mm, and the test pieces were then set in a thermal dilatometer TMA8140C (manufactured by Rigaku Corporation). The heating program was set to a heating rate of 5° C. / min, and a constant load of 19.6 mN was applied, after which the dimensional change of the test pieces was measured between 25° C. and 300° C. The relationship between the dimensional change and the temperature was plotted in a graph (an example of the graph is shown in FIG. 1). From the graph of the dimensional change and the temperature thus obtained, the glass transition temperatures in the examples and comparative examples were determined by the method for determining the glass transition temperature described below.

[0084] How to determine the glass transition temperature (Tg) As shown in Figure 1, any two temperatures at or below the inflection point temperature at which a tangent to the dimensional change-temperature curve is obtained are designated as T1 and T2, and any two temperatures at or above the inflection point temperature at which a similar tangent is obtained are designated as T1' and T2'. The dimensional changes at T1 and T2 are designated as D1 and D2, respectively, and the intersection of the line connecting points (T1, D1) and (T2, D2) with the line connecting points (T1', D1') and (T2', D2') with the dimensional changes at T1' and T2' is designated as D1' and D2', respectively, and the glass transition temperature (T g ) was decided.

[0085] (6) Heat resistance (adhesive strength retention after storage at 150℃) Each epoxy resin composition of the Examples and Comparative Examples was poured into a mold to obtain a test piece in the shape of a truncated cone with an upper diameter of 2 mm, a lower diameter of 5 mm, and a height of 3 mm. The test piece was placed on an aluminum plate and cured by heating at 80°C for 1 hour and then at 120°C for 1 hour. After curing, the obtained test piece was cooled to room temperature and the shear adhesive strength was measured, and the measurement result was used as the initial value. The obtained test piece was stored in an oven at 150°C for 150 hours, and then cooled to room temperature and the shear adhesive strength was measured. More specifically, the adhesive strength retention after storage at 150°C was calculated by the following formula.

number

[0086] (7) Moisture resistance (adhesive strength retention after PCT storage) Each epoxy resin composition of the examples and comparative examples was poured into a mold to obtain a truncated cone-shaped test piece with an upper diameter of 2 mm, a lower diameter of 5 mm, and a height of 3 mm. The test piece was placed on an aluminum plate and cured by heating at 80°C for 1 hour and then at 120°C for 1 hour. After curing, the obtained test piece was cooled to room temperature and the shear adhesive strength was measured, and the measurement result was used as the initial value. The obtained test piece was stored in PCT (121°C / humidity 100% / 2atm) for 96 hours, and then cooled to room temperature and the shear adhesive strength was measured. More specifically, the adhesive strength retention after PCT storage was calculated by the following formula.

number

[0087] (8) Drop resistance test Each epoxy resin composition of the Examples and Comparative Examples was applied onto a copper substrate, a copper block of 10 mm x 10 mm x 10 mm thick was placed on the applied surface, and the test piece was heated at 80°C for 1 hour and then at 120°C for 1 hour to cure. After curing, the test piece was cooled to room temperature. The test piece was dropped from a height of 100 cm. The drop was repeated 10 times, and the number of drops until the copper block peeled off from the copper substrate was recorded.

[0088]

Table 1

[0089]

Table 2

Claims

1. An epoxy resin composition comprising the following components (A) to (E): (A) 100 parts by weight of a non-silicone-modified epoxy resin having two or more epoxy groups in one molecule (B) A thiol compound having three or more thiol groups in one molecule (C) Silicone-modified epoxy resin: 0.5 to 100 parts by mass (D) Microcapsule type hardening accelerator 1.0 to 200 parts by mass (E) Reaction inhibitor: 0.05 to 10 parts by mass However, the amount of component (B) is an amount such that the molar equivalent ratio of thiol groups in component (B) to 1 molar equivalent of the total epoxy groups in components (A) and (C) is 0.1 to 1.0, and the silicone-modified epoxy resin (C) is a copolymer obtained by reacting one or more alkenyl group-containing epoxy resins represented by formulas (1) to (3) with the organohydrogenpolysiloxane represented by formula (5). 【Chemistry 1】 【Chemistry 2】 【Chemistry 3】 (In formulas (1) to (3), R 1 is a glycidyl group (2,3-epoxypropyl group), X is independently a hydrogen atom or a bromine atom, n is a number from 0 to 50, and m is a number from 1 to 5.) 【Chemistry 4】 (In formula (5), R 2 is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxy group, an alkoxy group having 1 to 10 carbon atoms, or an alkenyloxy group having 2 to 10 carbon atoms, p is a number from 0 to 1,000, q is a number from 0 to 20, and p+q is a number that satisfies 1<p+q≦1,000.)

2. 2. The epoxy resin composition according to claim 1, wherein the component (B) is a thiol compound having four or more thiol groups in one molecule.

3. 3. The epoxy resin composition according to claim 1, wherein the molar equivalent ratio of thiol groups in component (B) to the total molar equivalent of epoxy groups in components (A) and (C) is 0.1 to 0.

5.

4. 4. The epoxy resin composition according to claim 1, wherein the component (D) is a microcapsule-type curing accelerator containing at least one selected from the group consisting of a phosphorus compound, a tertiary amine compound, an imidazole compound, a urea compound, and an amine adduct compound.

5. 5. The epoxy resin composition according to claim 1, wherein the component (E) is a borate compound and / or a phosphite compound.

6. 6. The epoxy resin composition according to claim 1, wherein the volume average particle size of component (D) is 0.1 to 10 μm.

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