Thermosetting epoxy resin composition

Abstract

To provide a thermosetting epoxy resin composition and the like which, even when cured at a low temperature of, for example, 70°C or lower, have good adhesiveness to various organic substrates.SOLUTION: Provided is a thermosetting epoxy resin composition comprising (A) an epoxy resin, (B) a thiol curing agent, and (C) a curing accelerator. The curing accelerator (C) includes a masterbatch type curing accelerator which shows a heat generation start temperature of 40°C or higher and lower than 80°C when differential scanning calorimetry measurements (DSC) are made at a temperature increasing rate of 2°C / min from 25°C to 250°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting epoxy resin composition. [Background technology]

[0002] Epoxy resins and epoxy resin compositions are used in a wide range of applications, such as insulating materials, sealing materials, adhesives, and conductive materials for electronic devices and electrical and electronic components. In particular, electronic devices containing components that deteriorate under high temperature conditions require their manufacture to be carried out at low temperatures in a short time.

[0003] A known method for curing an epoxy resin composition is to use a liquid amine-based curing agent in a so-called two-component epoxy resin composition (hereinafter sometimes referred to as a "two-component epoxy resin composition"), in which two components, an epoxy resin and a curing agent, are mixed and cured at the time of use. While two-component epoxy resin compositions can be cured well at low temperatures, they have the drawback of requiring separate storage of the epoxy resin and the curing agent, and also requiring the two to be measured and mixed quickly and uniformly at the time of use, making them difficult to handle. Furthermore, once the epoxy resin and the curing agent are mixed, their subsequent usable time is limited, making it impossible to mix them in large quantities in advance.

[0004] In order to solve these problems, Patent Documents 1 and 2 aim to achieve both low-temperature curing properties and stability by using a latent curing agent as a curing catalyst for a thiol curing agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2017 / 057019 [Patent Document 2] Patent No. 6667843 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the epoxy resin compositions disclosed in Patent Documents 1 and 2 have the problem that they cannot exhibit sufficient adhesiveness when cured at low temperatures, for example, at 70° C. or lower.

[0007] Therefore, an object of the present invention is to provide a thermosetting epoxy resin composition that exhibits good adhesiveness even when cured at a low temperature, for example, 70°C or less. [Means for solving the problem]

[0008] As a result of extensive research conducted by the present inventors to solve the above-mentioned problems of the conventional art, they found that a thermosetting epoxy resin composition containing a masterbatch-type curing accelerator exhibiting an exotherm onset temperature within a specific range can solve the above-mentioned problems, and thus completed the present invention. That is, the present invention provides the following various aspects.

[0009] [1] (A) an epoxy resin, (B) a thiol curing agent, and (C) a curing accelerator; The (C) curing accelerator includes a masterbatch-type curing accelerator that exhibits an exothermic onset temperature of 40°C or higher and lower than 80°C when measured by differential scanning calorimetry (DSC) at a temperature rise rate of 2°C / min from 25°C to 250°C, A thermosetting epoxy resin composition.

[0010] [2] The heat generation starting temperature of the masterbatch type curing accelerator is 50°C or higher and 65°C or lower. [1] The thermosetting epoxy resin composition according to [1].

[0011] [3] The epoxy resin (A) contains at least one epoxy resin having a viscosity of less than 1 Pa·s at 25°C. [1] or [2]. The thermosetting epoxy resin composition according to [1] or [2].

[0012] [4] The masterbatch type curing accelerator is solid at room temperature, and the circularity of the solid curing agent component contained in the masterbatch type curing accelerator at room temperature is 0.9 or more. The thermosetting epoxy resin composition according to any one of [1] to [3].

[0013] [5] The masterbatch-type curing accelerator contains an amine adduct, which is a reaction product between an epoxy resin and a compound having at least one primary amino group and / or a secondary amino group and no tertiary amino group. The thermosetting epoxy resin composition according to any one of [1] to [4].

[0014] [6] The (C) masterbatch type curing accelerator contains a low molecular weight amine compound. The thermosetting epoxy resin composition according to any one of [1] to [5].

[0015] [7] The thiol curing agent (B) does not have an ester bond. The thermosetting epoxy resin composition according to any one of [1] to [6].

[0016] [8] The masterbatch type curing accelerator is a microcapsule type curing accelerator. The thermosetting epoxy resin composition according to any one of [1] to [7].

[0017] [9] The masterbatch-type curing accelerator has a total calorific value of less than 300 J / g when measured by DSC at a temperature rise rate of 2°C / min from 25°C to 250°C. The thermosetting epoxy resin composition according to any one of [1] to [8]. [Effects of the Invention]

[0018] According to the present invention, it is possible to realize a thermosetting epoxy resin composition or the like that has good adhesiveness even when cured at low temperatures. Furthermore, according to a preferred embodiment of the present invention, it is also possible to realize a thermosetting epoxy resin composition or the like that has good adhesiveness even when cured at low temperatures, is excellent in storage stability and moist heat resistance, and further has good continuous dischargeability using a jet dispenser. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention (hereinafter also referred to as "the present embodiment") will be described in detail. Note that the present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be implemented in various modifications within the scope of its gist.

[0020] [Thermosetting Epoxy Resin Composition] The thermosetting epoxy resin composition of this embodiment has excellent adhesive properties to various organic substrates even when cured at low temperatures. Therefore, the thermosetting epoxy resin composition of this embodiment can be suitably used as a one-component thermosetting adhesive for assembling camera modules for mobile phones, smartphones, tablet devices, drive recorders, in-vehicle cameras, etc. The composition can also be used as an adhesive or liquid sealant for various electronic components.

[0021] The thermosetting epoxy resin composition of the present embodiment comprises (A) an epoxy resin, (B) a thiol curing agent, and (C) a curing accelerator, and the (C) curing accelerator contains a masterbatch-type curing accelerator that exhibits an exotherm onset temperature of 40°C or higher and lower than 80°C when measured by differential scanning calorimetry (DSC) at a temperature rise rate of 2°C / min from 25°C to 250°C.

[0022] (A) Epoxy resin The thermosetting epoxy resin composition of this embodiment contains an epoxy resin (A). The epoxy resin (A) is not particularly limited, and various known epoxy resins can be appropriately selected and used. The epoxy resin (A) is, for example, but not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, tetrabromobisphenol A type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, tetrabromobiphenyl type epoxy resin, diphenyl ether type epoxy resin, benzophenone type epoxy resin, phenyl benzoate type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl sulfoxide type epoxy resin, diphenyl sulfone type epoxy resin, diphenyl disulfide type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutylhydroquinone type epoxy resin, rezo Bifunctional epoxy resins such as rusine-type epoxy resins, methylresorcinol-type epoxy resins, catechol-type epoxy resins, and N,N-diglycidylaniline-type epoxy resins; trifunctional epoxy resins such as N,N-diglycidylaminobenzene-type epoxy resins, o-(N,N-diglycidylamino)toluene-type epoxy resins, and triazine-type epoxy resins; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane-type epoxy resins and diaminobenzene-type epoxy resins; multifunctional epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, triphenylmethane-type epoxy resins, tetraphenylethane-type epoxy resins, dicyclopentadiene-type epoxy resins, naphthol aralkyl-type epoxy resins, and brominated phenol novolac-type epoxy resins;

[0023] Diepoxy resins such as (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, polytetramethylene ether glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexane diglycidyl ether, and dicyclopentadiene diglycidyl ether; triepoxy resins such as trimethylolpropane triglycidyl ether and glycerin triglycidyl ether;

[0024] Cycloaliphatic epoxy resins such as vinyl(3,4-cyclohexene) dioxide and 2-(3,4-epoxycyclohexyl)-5,1-spiro-(3,4-epoxycyclohexyl)-m-dioxane; glycidylamine-type epoxy resins such as tetraglycidylbis(aminomethyl)cyclohexane; hydantoin-type epoxy resins such as 1,3-diglycidyl-5-methyl-5-ethylhydantoin; and

[0025] Epoxy resins with a silicone skeleton such as 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane; 2-ethylhexyl glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, hydrogenated bisphenol A type epoxy resins, silicone-modified epoxy resins, (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether ether, butanediol diglycidyl ether, trimethylolpropane diglycidyl ether, polytetramethylene ether glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexane diglycidyl ether, dicyclopentadiene diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, vinyl(3,4-cyclohexene) dioxide, 2-(3,4-epoxycyclohexyl)-5,1-spiro-(3,4-epoxy)- Glycidylamine-type epoxy resins such as tetraglycidylbis(aminomethyl)cyclohexane; 1,3-diglycidyl-5-methyl-5-ethylhydantoin-type epoxy resins, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane-type epoxy resins, phenyl glycidyl ether, cresyl glycidyl ether, ps-butylphenyl glycidyl ether, styrene oxide, p-tert-butylphenyl glycidyl ether, and o-phenylphenol glycidyl ether aliphatic epoxy resins and alicyclic epoxy resins which can also be used as reactive diluents, such as p-phenylphenol glycidyl ether, N-glycidyl phthalimide, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, α-pinene oxide, allyl glycidyl ether, 1-vinyl-3,4-epoxycyclohexane, 1,2-epoxy-4-(2-methyloxiranyl)-1-methylcyclohexane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, and neodecanoic acid glycidyl ester;The (A) epoxy resin may be used alone or in combination of two or more.

[0026] From the viewpoints of reducing the viscosity of the thermosetting epoxy resin composition and improving the impact resistance of the cured product, it is desirable that the (A) epoxy resin contains an aliphatic epoxy resin or a monofunctional epoxy resin.

[0027] It is desirable that the (A) epoxy resin contains an epoxy resin with a viscosity of less than 1 Pa·s at 25°C. By containing an epoxy resin with a viscosity of less than 1 Pa·s at 25°C, it is possible to conform to the minute irregularities on the surface of the adherend and fill in the recesses, which tends to improve adhesion. In addition, the generation of shear heat between the nozzle and the resin composition when it is discharged from a jet dispenser with a narrow tip diameter is suppressed, which inhibits hardening of the resin composition at the nozzle tip and enables longer continuous discharge times. Another advantage is that there is greater freedom in the filler blend ratio.

[0028] The content of the (A) epoxy resin in the thermosetting epoxy resin composition of this embodiment can be appropriately set depending on the desired performance and is not particularly limited. From the viewpoint of adhesiveness after curing, the content of the (A) epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to the total amount of the resin composition. Furthermore, from the viewpoint of impact resistance of the cured product, the content of the (A) epoxy resin is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, relative to the total amount of the resin composition.

[0029] (B) Thiol curing agent The thermosetting epoxy resin composition of this embodiment contains (B) a thiol curing agent. (B) The thiol curing agent preferably has two or more thiol groups in the molecule. Furthermore, (B) the thiol curing agent preferably contains a thiol compound that does not have an ester bond. By using a thiol compound that does not have an ester bond, the cured product is less likely to undergo hydrolysis even under high-temperature and high-humidity conditions, and the reliability of the adhesive strength tends to be higher.

[0030] Examples of polyfunctional thiol compounds having an ester bond include trimethylolpropane tris(3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd.: TMMP), pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd.: PEMP), tetraethylene glycol bis(3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd.: EGMP-4), and dipentaerythritol hexakis(3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd.: DPMP). ), pentaerythritol tetrakis(3-mercaptobutyrate) (manufactured by Showa Denko K.K.: KarenzMT (registered trademark) PE1), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (manufactured by SC Organic Chemical Co., Ltd.: TEMPIC), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (manufactured by Showa Denko K.K.: KarenzMT (registered trademark) NR1), and the like can be mentioned, but are not particularly limited thereto.

[0031] Examples of thiol curing agents that do not have an ester bond include 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril (trade name: TS-G, manufactured by Shikoku Chemical Industry Co., Ltd.), 1,3,4,6-tetrakis(3-mercaptopropyl)glycoluril (trade name: C3 TS-G, manufactured by Shikoku Chemical Industry Co., Ltd.), 1,3,4,6-tetrakis(mercaptomethyl)glycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a-methylglycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a-methylglycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a-methylglycoluril, and 1,3,4,6-tetrakis(mercaptomethyl)glycoluril. 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-dimethylglycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a,6a-dimethylglycoluril, 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)- Examples of suitable curing agents include, but are not limited to, 3a,6a-diphenylglycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-diphenylglycoluril, pentaerythritol trippropanethiol (trade name: PEPT, manufactured by SC Organic Chemicals), and pentaerythritol tetrapropanethiol. Among these, 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)glycoluril, and pentaerythritol trippropanethiol are particularly preferred from the viewpoints of reactivity and availability. The (B) thiol curing agent may be used alone or in combination of two or more. From the viewpoints of the fluidity of the resin composition, the moist heat resistance of the cured product, and the flexibility of the cured product, thiol compounds having a thioether bond may also be used.

[0032] The content of the (B) thiol curing agent in the thermosetting epoxy resin composition of this embodiment can be appropriately set depending on the desired performance and is not particularly limited. From the viewpoints of low-temperature curing ability, water absorption of the cured product, etc., the thiol group equivalent of the (B) thiol curing agent relative to 1 equivalent of the epoxy group of the (A) epoxy resin is preferably 0.2 or more, more preferably 0.5 or more, and even more preferably 0.7 or more. Furthermore, from the viewpoints of storage stability, etc., the thiol group equivalent of the (B) thiol curing agent relative to 1 equivalent of the epoxy group of the (A) epoxy resin is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less.

[0033] (C) Curing accelerator The thermosetting epoxy resin composition of this embodiment contains (C) a curing accelerator. In this embodiment, the use of at least a masterbatch-type curing accelerator as (C) the curing accelerator improves the uniform dispersion of the curing accelerator in the (A) epoxy resin and (B) thiol curing agent, reducing the occurrence of uneven curing in the cured product obtained using the thermosetting epoxy resin composition of this embodiment. Furthermore, the uniform dispersion of the curing accelerator component also reduces the frequency of clogging of the nozzle tip of the jet dispenser due to aggregation of the curing accelerator component, enabling longer continuous discharge times.

[0034] Here, the masterbatch-type curing accelerator preferably has an exotherm onset temperature (DSC exotherm onset temperature) of 40°C or higher but lower than 80°C, as measured by differential scanning calorimetry (DSC) at a temperature rise rate of 2°C / min from 25°C to 250°C. The exotherm onset temperature is more preferably 45°C or higher but lower than 70°C, even more preferably 50°C or higher but lower than 65°C, and most preferably 51°C or higher but lower than 64°C. A DSC exotherm onset temperature of 40°C or higher under the above conditions means that when the resin composition is heated for curing, it maintains fluidity until the resin composition's temperature reaches 40°C, thereby conforming to the fine irregularities on the adherend surface and filling the irregularities, ensuring a wide adhesive area and increasing adhesive strength. Furthermore, a DSC exotherm onset temperature of less than 80°C under the above conditions means that the resin composition cures sufficiently at low temperatures and can exhibit high adhesive strength. The method for controlling the DSC heat generation initiation temperature to 40°C or higher and lower than 80°C is not particularly limited, but examples thereof include controlling the particle size distribution of the curing accelerator, controlling the specific surface area of ​​the curing accelerator particles, and controlling the softening point of the curing accelerator component.

[0035] Furthermore, the total calorific value of the masterbatch-type curing accelerator measured by DSC is not particularly limited, but is preferably less than 300 J / g. A total calorific value of less than 300 J / g measured by DSC means that the temperature rise during the reaction is small, and this has the effect of making it less likely that deterioration of storage stability due to trace amounts of reaction heat will occur during storage. The total calorific value is preferably less than 290 J / g, and more preferably less than 280 J / g. Note that methods for making the total calorific value by DSC less than 300 J / g are not particularly limited, but examples include reducing the number of functional groups by partially adducting the curing agent, using a resin with a large epoxy equivalent, and partially modifying the epoxy resin with allyl groups, etc.

[0036] As long as the curing accelerator can achieve the effects of the present invention, it is not limited to the following, but from the viewpoint of usable life and the like, a microcapsule-type curing accelerator having a core-shell structure is desirable. Here, the core of the microcapsule-type curing accelerator is preferably composed mainly of an amine adduct obtained by reacting an epoxy resin with an amine compound. The amine compound is not particularly limited, but examples thereof include a compound having at least one primary amino group and / or secondary amino group but no tertiary amino group; a compound having at least one tertiary amino group and at least one active hydrogen group; etc.

[0037] The compound having at least one primary amino group and / or secondary amino group but no tertiary amino group is not particularly limited, and examples thereof include primary amines having no tertiary amino group, such as methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, ethanolamine, propanolamine, cyclohexylamine, isophoronediamine, aniline, toluidine, diaminodiphenylmethane, and diaminodiphenylsulfone; and secondary amines having no tertiary amino group, such as dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, piperidine, piperidone, diphenylamine, phenylmethylamine, and phenylethylamine.

[0038] The compound having at least one tertiary amino group and at least one active hydrogen group is not particularly limited, and examples thereof include amino alcohols such as 2-dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, methyldiethanolamine, triethanolamine, and N-β-hydroxyethylmorpholine; 2-(dimethylaminomethyl)phenol, 2,4,6-trimethyl-2-dimethylaminoethanol, 2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, methyldiethanolamine, triethanolamine, and N-β-hydroxyethylmorpholine; aminophenols such as bis(dimethylaminomethyl)phenol; 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole; Imidazoles such as 2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole; 1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2-methylimidazoline, 2,4-dimethylimidazoline, 2-ethylimidazoline, 2-ethyl-4-methylimidazoline, 2-benzylimidazoline, 2-phenylimidazoline, 2-(o-tolyl)-imidazoline, tetramethylene-bis-imidazoline, 1 Imidazolines such as 1,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,3,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,1,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline, 1,3,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline, 1,2-phenylene-bis-imidazoline, 1,3-phenylene-bis-imidazoline, 1,4-phenylene-bis-imidazoline, 1,4-phenylene-bis-4-methylimidazoline;Tertiary aminoamines such as dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethylamine, dibutylaminoethylamine, N-methylpiperazine, N-aminoethylpiperazine, and diethylaminoethylpiperazine; aminomercaptans such as 2-dimethylaminoethanethiol, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptopyridine, and 4-mercaptopyridine; aminocarboxylic acids such as N,N-dimethylaminobenzoic acid, N,N-dimethylglycine, nicotinic acid, isonicotinic acid, and picolinic acid; and aminohydrazides such as N,N-dimethylglycine hydrazide, nicotinic acid hydrazide, and isonicotinic acid hydrazide.

[0039] Here, the core of the microcapsule-type curing accelerator preferably contains both a reaction product (amine adduct) between a compound having at least one primary amino group and / or secondary amino group but no tertiary amino group and an epoxy resin, and a reaction product (amine adduct) between a compound having at least one tertiary amino group and at least one active hydrogen group and an epoxy resin. By containing both, it becomes easier to control the exothermic onset temperature during DSC measurement to a predetermined temperature.

[0040] It is also preferable that the core of the microcapsule-type curing accelerator contains a low-molecular-weight amine compound, which enhances curability and allows the cured product to exert sufficient cohesive strength, thereby improving shear adhesive strength.

[0041] The low molecular weight amine compound is not particularly limited, but examples thereof include low molecular weight amine compounds containing a tertiary amino group. Examples of low molecular weight amine compounds having a tertiary amino group include, but are not limited to, trimethylamine, triethylamine, benzyldimethylamine, N,N-dimethyl-ethylamine, N,N-dimethyl-butylamine, N,N-dimethyldecylamine, N,N-dimethyl-m-toluidine, N,N-dimethyl-p-toluidine, 2,6,10-trimethyl-2,6,10-triazaundecane, N,N'-dimethylpiperazine, 1,4-diazabicyclo[2.2.2]octane, 1-azabicyclo[2.2.2]octan-3-one, 1,8-diazabicyclo(5,4,0)-undecene-7,1,5-diazabicyclo( Examples of suitable amine compounds include tertiary amines such as 4,3,0)-nonene-5 and hexamethylenetetramine; imidazoles such as 1-methylimidazole, 1,2-dimethylimidazole, 1-vinylimidazole, 1-allylimidazole, 2-methyl-1-vinylimidazole, and N-acetylimidazole; aromatic tertiary amines such as dimethylaminobenzhydrol, bis[4-(dimethylamino)phenyl]methane, 4,4'-bis(dimethylamino)benzophenone, and 2-diethylamino-N-(2,6-dimethylphenyl)acetamide; and aminopyridines having a tertiary amino group such as 2-dimethylaminopyridine and 4-dimethylaminopyridine. These amine compounds may be used alone or in combination of two or more.

[0042] The concentration of the low molecular weight amine compound contained in the core of the microcapsule-type curing accelerator is not particularly limited, but is preferably 2 to 15 wt%, more preferably 3 to 13 wt%, even more preferably 4 to 12 wt%, and particularly preferably 4 to 10 wt%. By having the proportion of the low molecular weight amine compound contained in the core of the microcapsule-type curing accelerator be 2 to 15 wt%, it becomes easier to achieve both curability at, for example, 55°C and storage stability.

[0043] Methods for microencapsulating the curing accelerator include, but are not limited to, the following methods (1) to (3). (1): After dissolving and dispersing the capsule components and hardening accelerator particles in a solvent, which is the dispersion medium, the solubility of the capsule components in the dispersion medium is reduced, causing the capsules to precipitate on the surface of the epoxy resin hardening accelerator particles. (2) A method in which hardening accelerator particles are dispersed in a dispersion medium, and the capsule-forming material is added to the dispersion medium and precipitated on the hardening accelerator particles. (3) A method in which capsule-forming raw material components are added to a dispersion medium, and the surface of the hardening accelerator particles is used as a reaction site to generate shell-forming materials there. Here, the above methods (2) and (3) are preferred because they allow reaction and coating to be carried out simultaneously.

[0044] After forming capsules using method (2) or (3), the method for separating the encapsulated curing accelerator from the dispersion medium is not particularly limited. However, it is preferable to separate and remove both the unreacted raw materials and the dispersion medium after capsule formation. One such method is to remove the dispersion medium and unreacted capsule-forming material by filtration. After removing the dispersion medium, it is preferable to wash the encapsulated curing accelerator. This allows the unreacted capsule-forming material adhering to the surface of the encapsulated curing accelerator to be removed. The washing method is not particularly limited. When separating the residue by filtration, washing can be performed using a solvent that does not dissolve the dispersion medium or the encapsulated curing accelerator. Furthermore, drying the encapsulated curing accelerator after filtration or washing can yield a powdered microencapsulated curing accelerator. The drying method is not particularly limited. Drying at a temperature below the melting point or softening point of the curing accelerator is preferred, for example, by vacuum drying. By converting the encapsulated curing accelerator into a powder, it can be easily blended with an epoxy resin. Furthermore, using an epoxy resin as a dispersion medium is preferable because a liquid resin composition consisting of the epoxy resin and the microcapsule-type epoxy resin curing accelerator can be obtained simultaneously with capsule formation. The capsule formation reaction is not particularly limited, but is usually carried out at a temperature in the range of -10°C to 150°C, preferably 0°C to 100°C, for a reaction time of 10 minutes to 72 hours, preferably 30 minutes to 24 hours.

[0045] Here, the masterbatch-type curing accelerator is solid at room temperature (25°C) and preferably has a particle ratio of 0.1 to 15% by cumulative volume of particles with a particle diameter of 1 μm or less. The particle ratio of 0.1 to 13% by cumulative volume is more preferably 0.1 to 13%, and even more preferably 0.1 to 11%. By setting the particle ratio of 0.1 to 15% by cumulative volume, it becomes easier to suppress particle aggregation, reducing the frequency of clogging when dispensing from a dispenser and enabling longer continuous dispensing times. Furthermore, the specific surface area of ​​the curing accelerator can be reduced, thereby enabling a higher DSC exothermic temperature. Methods for reducing the particle ratio of 1 μm or less to 15% by cumulative volume include, but are not limited to, classification. The particle diameter refers to the particle diameter measured by laser diffraction particle size distribution measurement.

[0046] Furthermore, from the viewpoints of particle aggregation, composition fluidity, storage stability, and control of DSC heat generation onset temperature, the masterbatch-type curing accelerator preferably has a circularity of 0.9 or more. The circularity of the masterbatch-type curing accelerator is more preferably 0.92 or more, and even more preferably 0.94 or more. Here, circularity can be measured by the method described in the Examples below, and the closer the circularity is to 1, the closer it is to a perfect sphere. There are no particular limitations on the method for controlling the circularity within the above range, but examples include surface modification of the curing accelerator, mechanically rounding the particles, and hot air treatment.

[0047] The content of the (C) curing accelerator in the thermosetting epoxy resin composition of this embodiment can be appropriately set depending on the desired performance and is not particularly limited. From the viewpoints of low-temperature curing ability, water absorption of the cured product, etc., the content of the (C) curing accelerator is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the (A) epoxy resin. Furthermore, from the viewpoints of storage stability, etc., the content of the (C) curing accelerator is preferably 120 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of the (A) epoxy resin.

[0048] (D) Additives The thermosetting resin composition of this embodiment may further contain an additive (D). Examples of the additive (D) include, but are not limited to, organic fillers, inorganic fillers, diluents, pigments, dyes, flow control agents, thickeners, reinforcing agents, mold release agents, wetting agents, flame retardants, surfactants, organic solvents, conductive fine particles, crystalline alcohols, and resins. These may be used alone or in combination of two or more.

[0049] Examples of organic fillers include, but are not limited to, thermoplastic resins such as triblock copolymers, thermoplastic elastomers, carbon fibers, cellulose, polyethylene powder, and polypropylene powder.

[0050] Examples of inorganic fillers include, but are not limited to, fused silica, crystalline silica, alumina, talc, silicon nitride, aluminum nitride, coal tar, glass fiber, asbestos fiber, boron fiber, quartz powder, mineral silicates, mica, asbestos powder, slate powder, and the like.

[0051] The diluent may be, but is not limited to, a reactive diluent or a non-reactive diluent. Examples of reactive diluents include, but are not limited to, cresol, ethylphenol, propylphenol, p-butylphenol, p-amylphenol, hexylphenol, octylphenol, nonylphenol, dodecylphenol, octadecylphenol, and terpene phenol. Examples of non-reactive diluents include, but are not limited to, dioctyl phthalate, dibutyl phthalate, and benzyl alcohol.

[0052] Examples of the stabilizer include, but are not limited to, borate compounds, titanate compounds, aluminate compounds, zirconate compounds, isocyanate compounds, carboxylic acids, and acid anhydrides.

[0053] The borate compound is not particularly limited, but examples thereof include trimethyl borate, triethyl borate (triethyl borate), tripropyl borate, triisopropyl borate, tributyl borate (tributyl 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. Furthermore, cyclic borate esters having a cyclic structure within the molecule can also be used as the borate compound. Examples of cyclic borate esters include tris-o-phenylene bisborate, bis-o-phenylene pyroborate, bis-2,3-dimethylethylenephenylene pyroborate, bis-2,2-dimethyltrimethylene pyroborate, etc. Products containing such borate esters include, for example, "Cureduct" (registered trademark) L-01B (Shikoku Chemicals Corporation), "Cureduct" (registered trademark) L-07N (Shikoku Chemicals Corporation), etc.

[0054] The titanate compound is not particularly limited, but examples thereof include tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraoctyl titanate.

[0055] The aluminate compound is not particularly limited, but examples thereof include triethyl aluminate, tripropyl aluminate, triisopropyl aluminate, tributyl aluminate, and trioctyl aluminate.

[0056] The zirconate compound is not particularly limited, but examples thereof include tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, and tetrabutyl zirconate.

[0057] The isocyanate compound is not particularly limited, but examples thereof include butyl isocyanate, isopropyl isocyanate, 2-chloroethyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, benzyl isocyanate, hexamethylene diisocyanate, 2-ethylphenyl isocyanate, 2,6-dimethylphenyl isocyanate, tolylene diisocyanate (e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate), 1,5-naphthalene diisocyanate, diphenylmethane-4,4′-diisocyanate, tolidine diisocyanate, isophorone diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, and bicycloheptane triisocyanate.

[0058] The carboxylic acid is not particularly limited, but examples thereof include saturated aliphatic monobasic acids such as formic acid, acetic acid, propionic acid, butyric acid, caproic acid, and caprylic acid; unsaturated aliphatic monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid; halogenated fatty acids such as monochloroacetic acid and dichloroacetic acid; monobasic hydroxy acids such as glycolic acid, lactic acid, and acetic acid; aliphatic aldehyde acids and ketone acids such as glyoxylic acid; aliphatic polybasic acids such as oxalic acid, malonic acid, succinic acid, and maleic acid; aromatic monobasic acids such as benzoic acid, halogenated benzoic acid, toluic acid, phenylacetic acid, cinnamic acid, and mandelic acid; and aromatic polybasic acids such as phthalic acid and trimesic acid.

[0059] The acid anhydride is not particularly limited, and examples thereof include aliphatic polybasic acid anhydrides such as succinic anhydride, dodecynylsuccinic anhydride, maleic anhydride, an adduct of methylcyclopentadiene and maleic anhydride, hexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride; and aromatic polybasic acid anhydrides such as phthalic anhydride, trimellitic anhydride, and pyrrolimellitic anhydride.

[0060] Examples of pigments include, but are not limited to, kaolin, aluminum oxide trihydrate, aluminum hydroxide, chalk powder, gypsum, calcium carbonate, antimony trioxide, pentone, silica, aerosol, lithopone, baryte, and titanium dioxide.

[0061] Examples of dyes include, but are not limited to, natural dyes such as plant-derived dyes such as madder and indigo, and mineral-derived dyes such as yellow ochre and red clay, synthetic dyes such as alizarin and indigo, and fluorescent dyes.

[0062] Examples of flow control agents include, but are not limited to, silane coupling agents; organic titanium compounds such as titanium tetraisopropoxide and titanium diisopropoxybis(acetylacetonate); and organic zirconium compounds such as zirconium tetra-n-butoxide and zirconium tetraacetylacetonate.

[0063] Examples of thickeners include, but are not limited to, animal-based thickeners such as gelatin; plant-based thickeners such as polysaccharides and cellulose; and chemically synthesized thickeners such as polyacrylics, modified polyacrylics, polyethers, urethane-modified polyethers, and carboxymethyl cellulose.

[0064] Examples of the reinforcing agent include, but are not limited to, polyethylene sulfone powder such as "Sumika Excel PES" manufactured by Sumitomo Chemical Co., Ltd.; nano-sized functional group-modified core-shell rubber particles such as "Kane Ace MX" manufactured by Kaneka Corporation; and silicone-based reinforcing agents such as polyorganosiloxane.

[0065] Examples of the release agent include, but are not limited to, fluorine-based release agents, silicone-based release agents, and acrylic-based release agents made from a copolymer of glycidyl (meth)acrylate and a linear alkyl (meth)acrylate ester having 16 to 22 carbon atoms.

[0066] Examples of wetting agents include, but are not limited to, unsaturated polyester copolymer wetting agents having acidic groups, such as acrylic polyphosphate ester.

[0067] Examples of flame retardants include, but are not limited to, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, halogen-based flame retardants such as chlorine compounds and bromine compounds, phosphorus-based flame retardants such as condensed phosphate esters, antimony-based flame retardants such as antimony trioxide and antimony pentoxide, and inorganic oxides such as silica fillers.

[0068] Examples of surfactants include, but are not limited to, anionic surfactants such as alkylbenzene sulfonates and alkyl polyoxyethylene sulfates, cationic surfactants such as alkyl dimethyl ammonium salts, amphoteric surfactants such as alkyl dimethyl amine oxides and alkyl carboxy betaines, and nonionic surfactants such as linear alcohols and fatty acid esters having 25 or more carbon atoms.

[0069] Examples of organic solvents include, but are not limited to, toluene, xylene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), ethyl acetate, and butyl acetate.

[0070] Examples of conductive fine particles include, but are not limited to, carbon black, graphite, carbon nanotubes, fullerenes, iron oxide, gold, silver, aluminum powder, iron powder, nickel, copper, zinc, chromium, solder, nano-sized metal crystals, and intermetallic compounds.

[0071] Examples of crystalline alcohols include, but are not limited to, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, pentaerythritol, sorbitol, sucrose, and trimethylolpropane.

[0072] Examples of resins include, but are not limited to, polyester resin, polyurethane resin, acrylic resin, polyether resin, melamine resin, and modified epoxy resins such as urethane-modified epoxy resin, rubber-modified epoxy resin, and alkyd-modified epoxy resin.

[0073] The above-mentioned (D) additives can be added in functionally equivalent amounts. For example, pigments and / or dyes can be added in amounts that can impart a desired color to the thermosetting epoxy resin composition of the present embodiment.

[0074] The thermosetting epoxy resin composition of the present embodiment contains at least the above-mentioned (A) epoxy resin, (B) thiol curing agent, and (C) curing accelerator. From the viewpoints of corrosiveness, usable life, reactivity, etc., the total chlorine content in the composition is preferably 2000 ppm or less, more preferably 1500 ppm or less, and even more preferably 900 ppm or less.

[0075] (Application) The thermosetting epoxy resin composition of this embodiment and the cured product obtained therefrom can be used in various applications where epoxy resins are used as materials. It is particularly useful as a one-component thermosetting adhesive for assembling camera modules. It is also suitable for, but not limited to, adhesives for electronic device housings, semiconductor encapsulants such as underfills and moldings, conductive adhesives such as anisotropic conductive films (ACFs), and printed wiring boards such as solder resists and coverlay films. [Example]

[0076] The present invention will be explained in more detail below with reference to Preparation Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. Note that the values ​​of various production conditions and evaluation results shown below represent preferred upper or lower limits in the embodiments of the present invention, and preferred ranges may be defined by combining the above-mentioned upper or lower limits with the values ​​of the following Examples or values ​​of the Examples themselves.

[0077] First, the methods for measuring the physical properties and characteristics used in the Preparation Examples, Examples, and Comparative Examples are shown below.

[0078] (Differential scanning calorimetry (DSC) measurement) Approximately 10 mg of the curing accelerator was weighed out using an EXSTER7020 (Hitachi High-Tech Science Corporation), and the temperature was raised from 25°C to 250°C at a rate of 2°C / min to obtain a DSC curve. The intersection of the baseline before the onset of heat generation and the tangent to the point where the change in heat generation reaches its maximum value after the onset of heat generation was defined as the onset of heat generation temperature. The total heat generation amount was calculated by integrating the heat flow from the onset to the end of the heat generation over time.

[0079] (Circularity) Using a flow particle image analyzer FPIA-3000S (manufactured by Spectris, Inc.), the circularity of each curing accelerator was determined by measuring a dispersion in which each curing accelerator particle obtained during the manufacturing process was dispersed in cyclohexane at 0.5 mass%. Encapsulated particles were considered to be uniformly encapsulated, and the circularity of the curing accelerator was used as is.

[0080] (particle size distribution) Using a particle size distribution analyzer (HORIBA LA-920, manufactured by Horiba Ltd.), D50 and the proportion of particles less than 1 μm were measured by the laser diffraction / light scattering method.

[0081] (Measurement of tensile shear adhesive strength of thermosetting epoxy resin composition) According to JIS K6850, the tensile shear adhesive strength was measured after curing at 60°C for 30 minutes and 55°C for 30 minutes. Here, a liquid crystal polymer (Sumika Super E6007LHF (Sumitomo Chemical Co., Ltd.)) was used as the mating material to be adherend. Five tensile shear adhesive strength measurements were performed, and the average of the five measurements was calculated. This average was used as the tensile shear adhesive strength. Tensile shear adhesive strengths of 10 MPa or more were evaluated as ◎, 8 MPa or more but less than 10 MPa as ○, 5 MPa or more but less than 8 MPa as △, and less than 5 MPa as ×. Compositions that did not cure and could not be measured were described as "uncured."

[0082] (Pot life) The initial viscosity of each thermosetting epoxy resin composition at 25°C was measured using an E-type viscometer, and the time required for the viscosity to increase by 1.2 times or more from the initial state was measured and recorded as the pot life. The pot life was then evaluated as follows: ⊚ for 14 days or more, ◯ for 7 days or more but less than 14 days, △ for 3 days or more but less than 7 days, and × for less than 3 days.

[0083] (Heat and humidity resistance test) Samples prepared under the same conditions as those used to measure the tensile shear adhesive strength of thermosetting epoxy resin compositions were left for 168 hours in an environment of 85°C and 85% relative humidity, and the tensile shear adhesive strength was measured before and after exposure to high temperature and high humidity. Using the adhesive strength before exposure to high temperature and high humidity as the standard, the adhesive strength retention rate after exposure to high temperature and high humidity was evaluated as follows: ⊚ if 90% or more was retained but less than 90%, ◯ if 75% or more but less than 90%, △ if 50% or more but less than 75%, and × if less than 50%. Compositions whose adhesive strength could not be measured because they did not cure were described as "uncured."

[0084] (Continuous discharge) A syringe (PSY-50F manufactured by Musashi Engineering Co., Ltd.) was filled with 40 g of the thermosetting epoxy resin composition, and the time it took to discharge the composition without clogging was measured at a rate of 1 mg / sec. The results were evaluated as follows: 5 hours or more: ◎; 3 hours to less than 5 hours: ◯; 1 hour to less than 3 hours: △; and less than 1 hour: ×.

[0085] [Synthesis of epoxy resin curing accelerator (AD)] (Production Example 1-1) 284 g of triethylenetetramine (manufactured by Fujifilm Corporation, commonly known as TETA) was dissolved in 284 g of toluene solution, and after heating to 60°C, 720 g of a 50 mass % toluene solution of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER828") was added and reacted. The reaction solution was then heated under reduced pressure and the toluene was distilled off from the reaction solution, yielding epoxy resin curing accelerator AD-1.

[0086] (Production Example 1-2) 237 g of 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., product name: 2E4MZ) was dissolved in 237 g of toluene solution, and after heating to 80°C, 720 g of a 50 mass % toluene solution of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER806") was added and reacted. Next, the reaction solution was heated and reduced pressure, and the toluene was distilled off from the reaction solution, yielding epoxy resin curing accelerator AD-2.

[0087] (Production Example 1-3) In a 100g solution of 1-butanol, Dimethylaminopropylamine After heating to 50°C, 200 g of a 1-butanol solution containing 50% by mass of isophorone diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd., commonly known as IPDI) was added and reacted. The reaction solution was then heated under reduced pressure and the 1-butanol was distilled off, yielding epoxy resin curing accelerator AD-3.

[0088] [Production of epoxy resin curing accelerator (H)] (Production Example 2-1) 100 g of AD-1 obtained in Production Example 1-1 was taken and heated at 160°C, after which 100 g of AD-2 and 22 g of triethylenediamine (manufactured by Tosoh Corporation, product name TEDA) were further added and the mixture was melted and mixed with stirring for 3 hours to obtain epoxy resin curing accelerator H-1.

[0089] (Production Example 2-2) 80 g of AD-1 obtained in Production Example 1-1 and 120 g of AD-2 obtained in Production Example 1-2 were each separated and mixed, and the mixture was heated at 180°C. 20 g of 1-azabicyclo[2,2,2]octane (manufactured by TCI) was then added, and the mixture was melted and mixed with stirring for 3 hours to obtain epoxy resin curing accelerator H-2.

[0090] (Production Example 2-3) 70 g of AD-1 obtained in Production Example 1-1 and 130 g of AD-2 obtained in Production Example 1-2 were each taken and mixed, and the mixture was heated at 180°C. 10 g of diazabicycloundecene (manufactured by TCI) was then added, and the mixture was melted and mixed with stirring for 3 hours to obtain epoxy resin curing accelerator H-3.

[0091] [Production of epoxy resin curing accelerator (P)] (Production Example 3-1) The epoxy resin curing accelerator H-1 obtained in Production Example 2-1 was pulverized using a jet mill (manufactured by Nisshin Engineering, "CJ25 model") at a pulverization pressure of 0.5 MPa s and a raw material supply rate of 7 kg / hr to obtain epoxy resin curing accelerator P-1.

[0092] (Production Example 3-2) The epoxy resin curing accelerator H-2 obtained in Production Example 2-2 was ground using a jet mill (Nisshin Engineering, CJ25 model) at a grinding pressure of 0.5 MPa·s and a feed rate of 15 kg / hr. The particles were then classified using an air classifier (Nisshin Engineering, Turbo Classifier) ​​to obtain particles with a diameter of 1 μm or less. The resulting curing accelerator was then heat-treated using a Nippon Pneumatic Meteor Rainbow MR-10 at a feed rate of 2.0 kg / hr and a temperature of 180°C. The container was equipped with a cyclone collector and a bag filter. Circulating cooling water at 0°C was passed through the powder recovery section to cool the container to below 40°C. Air controlled at 25°C and 10% humidity was introduced as cooled air after the hot air treatment. The resulting mixture was then classified using the classifier to obtain epoxy resin curing accelerator P-2.

[0093] (Production Example 3-3) The epoxy resin curing accelerator H-3 obtained in Production Example 2-3 was treated in the same manner as in Production Example 3-2 to obtain a curing accelerator P-3.

[0094] (Production Example 3-4) The epoxy resin curing accelerator AD-2 obtained in Production Example 1-2 was pulverized using a jet mill (Nisshin Engineering, "CJ25 type") at a pulverization pressure of 0.5 MPa·s and a raw material feed rate of 7 kg / hr. Then, using a Kryptron Orb manufactured by EarthTechnica Corporation, the mixture was pulverized at a rotation speed of 13,500 rpm, a feed rate of 5 kg / hr, and an air volume of 3 m3 under an environment of a temperature of 10°C and a humidity of 30%. 3 / min, shape correction treatment was performed to obtain epoxy resin curing accelerator P-4.

[0095] (Production Example 3-5) The epoxy resin curing accelerator AD-2 obtained in Production Example 1-2 was pulverized using a jet mill (manufactured by Nisshin Engineering, "CJ25 model") at a pulverization pressure of 0.5 MPa s and a raw material supply rate of 7 kg / hr for two passes to obtain epoxy resin curing accelerator P-5.

[0096] (Production Example 3-6) The epoxy resin curing accelerator AD-3 obtained in Production Example 1-3 was treated in the same manner as in Production Example 3-5 to obtain an epoxy resin curing accelerator P-6.

[0097] [Preparation and Evaluation of Curing Accelerators] (Preparation Example 1) 100 g of the epoxy resin hardening accelerator P-1 obtained in Preparation Example 3-1 was added to 140 g of methylcyclohexane and dispersed in the methylcyclohexane. Then, 0.5 g of isophorone diisocyanate was further added and the mixture was allowed to react at 30°C for 4 hours. After the reaction was completed, the mixture was filtered, washed, and dried. The resulting reaction product was dispersed in a mixture of 100 g of YL983U (a bisphenol F-type epoxy resin manufactured by Mitsubishi Chemical Corporation) and 100 g of YL980 (a bisphenol A-type epoxy resin manufactured by Mitsubishi Chemical Corporation) to obtain the masterbatch-type hardening accelerator MB-1 of Preparation Example 1. The resulting masterbatch-type hardening accelerator was subjected to DSC measurement to determine the hardening initiation temperature. The results are shown in Table 1.

[0098] (Preparation Example 2) To 100 g of YL983U (a bisphenol F-type epoxy resin manufactured by Mitsubishi Chemical Corporation), 100 g of the epoxy resin hardening accelerator P-2 obtained in Preparation Example 3-2 was added, and 1.5 g of hexamethylene diisocyanate was further added. The mixture was reacted at 30°C for 4 hours and filtered to obtain the masterbatch-type hardening accelerator MB-2 of Preparation Example 2.

[0099] (Preparation Example 3) To 120 g of YL980 (a bisphenol A-type epoxy resin manufactured by Mitsubishi Chemical Corporation), 100 g of the epoxy resin hardening accelerator P-3 obtained in Preparation Example 3-3 was added, and 4.5 g of hexamethylene diisocyanate was further added. The mixture was reacted at 30°C for 5 hours and filtered to obtain the masterbatch-type hardening accelerator MB-3 of Preparation Example 3.

[0100] (Preparation Example 4) 100 g of the epoxy resin hardening accelerator P-4 obtained in Preparation Example 3-4 was added to 140 g of methylcyclohexane and dispersed in the methylcyclohexane. 2.0 g of 1,6-hexanediisocyanate was then added, and the mixture was allowed to react at 40°C for 3 hours. After the reaction was completed, the mixture was filtered, washed, and dried. The resulting reaction product was dispersed in 200 g of YL983U (bisphenol F-type epoxy resin, manufactured by Mitsubishi Chemical Corporation) to obtain the microcapsule-type hardening accelerator MB-4 of Preparation Example 4.

[0101] (Preparation Example 5) 100 g of the epoxy resin hardening accelerator P-5 obtained in Preparation Example 3-5 was added to 140 g of methylcyclohexane and dispersed in the methylcyclohexane. 15.0 g of 1,6-hexanediisocyanate was then added and the mixture was reacted at 60°C for 3 hours. After the reaction was completed, the mixture was filtered, washed, and dried. The resulting reaction product was dispersed in 200 g of EXA850CRP (bisphenol A-type epoxy resin manufactured by DIC Corporation) to obtain the masterbatch-type hardening accelerator MB-5 of Preparation Example 5.

[0102] (Preparation Example 6) The non-masterbatch epoxy resin curing accelerator P-6 obtained in Production Example 3-6 was used as curing accelerator P-6 in Preparation Example 6.

[0103] The evaluation results of the heat generation initiation temperatures of the curing accelerators of Preparation Examples 1 to 6 are shown in Table 1. Note that the curing accelerator of Preparation Example 6 was not made into a masterbatch, so no heat was generated during DSC measurement.

[0104] [Table 1]

[0105] Table 2 also shows the results of various evaluations of the curing accelerators of Preparation Examples 1 to 4 and Comparative Preparation Examples 1 and 2.

[0106] [Table 2]

[0107] [ Reference examples 1~2, Example 2~4、6~15 and Comparative Examples 1 to 8] Using the epoxy resin curing accelerators (MB-1) to (MB-5) and (P-6) prepared above, thermosetting epoxy resin compositions were prepared according to the formulations shown in Tables 3 and 4 below.

[0108] The various materials used here are listed below. EXA835LV: DIC bisphenol A, F-type mixed epoxy resin, viscosity at 25°C 2.2 Pa·s, epoxy equivalent weight 170 g / eq EXA830CRP: DIC high-purity bisphenol F epoxy resin, viscosity at 25°C 1.6 Pa·s, epoxy equivalent weight 161 g / eq EX-146: Nagase ChemteX Corporation, ter-butylphenyl glycidyl ether, viscosity at 25°C 0.02 Pa·s, epoxy equivalent 206 g / eq CDMDG: Showa Denko cyclohexanedimethanol diglycidyl ether, viscosity at 25°C 0.03 Pa·s, epoxy equivalent 136 g / eq PEMP: SC Organic Chemicals, Pentaerythritol tetrakis(3-mercaptopropionate), SH equivalent 124g / eq PEPT: SC Organic Chemicals Pentaerythritol trippropanethiol, SH equivalent 138g / eq TS-G: Shikoku Chemicals Co., Ltd. 1,3,4,6-tetrakis(2-mercaptoethyl) glycoluril, SH group equivalent 94g / eq

[0109] According to the above, tests were carried out on the shear adhesive strength when cured at 60° C. and 55° C., the pot life, the humidity and heat resistance, and the continuous dischargeability. The evaluation results are shown in Tables 3 and 4.

[0110] [Table 3]

[0111] [Table 4] [Industrial Applicability]

[0112] The thermosetting epoxy resin composition of the present invention can be widely and effectively used in various applications such as insulating materials, sealing materials, adhesives, adhesives for electronic device casings, conductive adhesives, and conductive materials for electronic devices and electric / electronic components, and can be particularly effectively used as one-component thermosetting adhesives for assembling camera modules for mobile phones, smartphones, tablet terminals, drive recorders, in-vehicle cameras, etc.; adhesives for various electronic components; liquid sealants; etc.

Claims

1. (A) an epoxy resin, (B) a thiol curing agent, and (C) a curing accelerator; the (C) curing accelerator contains a masterbatch-type curing accelerator that exhibits an exotherm onset temperature of 50°C or higher but lower than 80°C when measured by differential scanning calorimetry (DSC) at a temperature rise rate of 2°C / min from 25°C to 250°C, the masterbatch-type curing accelerator comprises an amine adduct which is a reaction product of an epoxy resin and a compound having at least one primary amino group and / or a secondary amino group and no tertiary amino group; A thermosetting epoxy resin composition.

2. The heat generation initiation temperature of the masterbatch-type curing accelerator is 50°C or higher and 65°C or lower. The thermosetting epoxy resin composition according to claim 1.

3. The epoxy resin (A) contains at least one epoxy resin having a viscosity of less than 1 Pa·s at 25°C. The thermosetting epoxy resin composition according to claim 1 or 2.

4. The masterbatch type curing accelerator is solid at room temperature, and the circularity of the solid curing agent component contained in the masterbatch type curing accelerator at room temperature is 0.9 or more. The thermosetting epoxy resin composition according to any one of claims 1 to 3.

5. The masterbatch-type curing accelerator (C) contains a low-molecular-weight amine compound. The thermosetting epoxy resin composition according to any one of claims 1 to 4.

6. The thiol curing agent (B) does not have an ester bond. The thermosetting epoxy resin composition according to any one of claims 1 to 5.

7. The masterbatch type curing accelerator is a microcapsule type curing accelerator. The thermosetting epoxy resin composition according to any one of claims 1 to 6.

8. The masterbatch-type curing accelerator has a total calorific value of less than 300 J / g when measured by DSC at a temperature rise rate of 2°C / min from 25°C to 250°C. The thermosetting epoxy resin composition according to any one of claims 1 to 7.

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