JP6364239B2 - One-component thermosetting epoxy resin composition - Google Patents

Description

  The present invention relates to an epoxy-thiol curable resin composition, and more specifically, a one-component thermosetting epoxy containing a specific epoxy resin, a specific imidazole compound, and a polythiol compound and excellent in storage stability and fast curing. The present invention relates to a resin composition.

  Epoxy resin compositions are used in a wide range of fields such as adhesives, sealants, and paints, and two-pack type epoxy resins with excellent storage stability are common, but mixing operations of the main agent and curing agent during use In addition, there is a drawback in that workability is poor because thickening proceeds during the work.

  Therefore, in recent years, an operation of mixing the main agent and the curing agent at the time of use is unnecessary, and a one-pack type epoxy resin composition excellent in workability has been used. The latent curing agent used in such a one-pack type epoxy resin composition is usually a solid particle of several μm at room temperature and is dispersed in a liquid epoxy resin. Since the solid particles of this latent curing agent are phase-separated from the epoxy resin at room temperature, it is difficult to cause a curing reaction, and when heated, it melts into the epoxy resin and causes a curing reaction. be called. As such a solid dispersion type latent curing agent, various compounds such as dicyandiamide, a dihydrazide compound, and an amine adduct compound, and microcapsules of amine and imidazole are known (Non-patent Document 1).

  However, when a resin composition containing a solid dispersion type latent curing agent is used as the impregnating adhesive, only the liquid epoxy resin penetrates deeply into the gap, and the solid particles as the curing agent are sufficient in the gap. Since it cannot penetrate, there is a case where the curing becomes non-uniform, and in an extreme case, there is a disadvantage that the gap portion may not be cured at all.

  In addition, in the case of a resin composition using a solid dispersion type latent curing agent, in the case of a paint or a coating agent, the coating thickness is extremely thin so that the curing agent and the epoxy resin cannot be mixed uniformly during curing. When there is a portion, there is a drawback that the cured film becomes non-uniform or a partially uncured portion is generated.

  As a completely liquid one-pack type epoxy resin composition capable of solving the above drawbacks, one using an amine complex of boron trifluoride as a curing agent is known (Patent Document 1). In this case, there is a drawback that corrosive and dangerous hydrogen fluoride gas is generated during curing.

  On the other hand, in a two-pack type curable epoxy resin composition, a resin composition using a compound having a thiol group together with a tertiary amine catalyst is widely known in order to improve room temperature curability. A resin composition using a latent alkali catalyst instead of the tertiary amine has also been proposed as a resin composition improved to a one-pack type. However, this resin composition is not suitable for moisture in the air or ambient moisture. Therefore, its use has been extremely limited (Patent Document 2).

  On the other hand, a polythiol compound having two or more thiol groups in the molecule is used as a curing agent, and a compound having one or more isocyanate groups in the molecule as a curing accelerator and at least one primary and / or in the molecule. A polythiol-based epoxy resin composition having storage stability and excellent curability has also been proposed by using a reaction product with a compound having a secondary amino group (Patent Document 3). However, since the reproducibility of the resin composition disclosed herein is difficult, it cannot be said that it is a practical composition, such as the presence of undissolved residue in the composition.

  Then, the manufacturing method of the completely liquid one-pack type epoxy resin composition which eliminates the fault of said invention progressively was proposed (patent document 4). The resin composition obtained by this method has excellent storage stability and excellent curability despite being uniformly mixed with an epoxy resin and a curing agent, and is said to be suitable for impregnation adhesion or thin film curing. Yes. However, this method is different from the conventional production process and is complicated, and also has a drawback that the acid resistance of the apparatus must be taken into account in order to use a compound having Lewis acidity.

Therefore, a completely liquid one-component thermosetting epoxy resin composition that can be produced by a production process that has been practically used and has storage stability and practical curability that can withstand general distribution is still available. unknown.
Therefore, the present inventors have intensively studied to obtain a completely liquid one-component thermosetting epoxy resin composition that is not yet known, and as a result, combine a specific epoxy resin, a specific imidazole compound, and a polythiol compound. Thus, the inventors have found that the complete liquid one-component thermosetting epoxy resin composition can be easily obtained, and have reached the present invention.

JP-A-9-52942 JP-A-2-36220 Japanese Patent Laid-Open No. 06-21970 WO2005 / 070991

"Review Epoxy Resin", edited by Epoxy Resin Technology Association, published on November 19, 2003

Therefore, the first object of the present invention is to provide a one-part thermosetting epoxy resin composition having sufficient storage stability and excellent curability even though the epoxy resin and the curing agent are uniformly mixed. Is to provide.
The second object of the present invention is that it has sufficient storage stability and excellent curability even though the epoxy resin and the curing agent are uniformly compatible, and is suitable for impregnating adhesive and thin film uniform coating. Another object of the present invention is to provide a completely liquid one-component thermosetting epoxy resin composition.

The above-mentioned objects of the present invention include (A) an epoxy resin component, (B) an imidazole compound represented by the following general formula (II), and (C) a polythiol compound, and does not contain an isocyanate group-containing compound. A one-component thermosetting epoxy resin composition comprising 10% to 100% by mass of a compound represented by the following average composition formula (I) in 100% of the epoxy resin component (A): Achieved by.

Average composition formula (I)
In the above formula, l is 0, 1 or 2, m is a positive number of 0.1 or more and less than 50, ^{R 1} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, ^{R 2} is a group:
Or the group:
R ³ and R ⁴ are each independently a hydrogen atom or an unsubstituted or fluorine-substituted methyl group, and n is an integer of 4 to 12.

General formula (II);
In the general formula (II), k is an integer of 1 to 5, j is 1 , and R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Or an aryl group, wherein R ⁸ is a group when k is 1.
When k is an integer of 2 to 5, an alkylene group having 1 to 20 carbon atoms, an arylene group, or a group:
R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a cyanomethyl group when k is 1, and when k is an integer of 2 to 5. Is a hydrocarbon group having 1 to 20 carbon atoms.

In this invention, it is preferable that 5-30 mass% of the epoxy resin which is the said (A) component is an epoxy compound represented by the following general formula (III).
Formula (III)
However, R ¹⁰ and R ¹¹ in the above formula each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
In addition, R ² in the average composition formula (I) is preferably the following group.

  In the present invention, j in the general formula (II) is preferably 1, and the polythiol compound as the component (C) is dipentaerythritol hexa (3-mercaptobutyrate) and / or 1 , 3,5-tris (3-mercaptopropyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione.

Furthermore, in the present invention, it is preferable to contain a silane coupling agent as the component (D). In particular, the silane coupling agent as the component (D) is represented by the following general formula (IV). It is preferable that it is an agent.
Formula (IV)
However, p and q in the above formula represent 0, 1, 2 or 3, p + q is 3, R ¹² and R ¹³ are alkyl groups having 1 to 4 carbon atoms, and R ¹⁴ is 1 to 4 carbon atoms. 20 alkylene group or arylene group, R ¹⁵ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group, or an alkyl group which may contain an oxygen atom, a nitrogen atom or a sulfur atom.

  According to the present invention, a practical resin composition having a balance between moderate curing characteristics and storage stability can be easily obtained using readily available raw materials. Especially when it is a completely liquid one-component resin composition that does not contain a solid curing agent component at room temperature, it is a one-component thermosetting epoxy that is excellent in workability and suitable for narrow space and impregnation bonding. A resin composition is obtained.

Hereinafter, the one-component thermosetting epoxy resin composition of the present invention will be described in detail.
In general, one-component thermosetting resin compositions containing isocyanate may cause foam deterioration during curing due to moisture absorbed, or deterioration of properties due to increased viscosity of the composition. Strict humidity control is required during storage and handling. Has the disadvantage of becoming. Therefore, in the present invention, from the above viewpoint, the composition does not particularly use a compound containing an isocyanate group.

  Examples of the epoxy resin as component (A) used in the present invention include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as hydroquinone, resorcin, pyrocatechol, and phloroglucinol; dihydroxynaphthalene, biphenol, methylene bisphenol (Bisphenol F), methylene bis (orthocresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropylidene bis (orthocresol), tetrabromobisphenol A, 1,3-bis (4-hydroxycumylbenzene), 1 , 4-bis (4-hydroxycumylbenzene), 1,1,3-tris (4-hydroxyphenyl) butane, 1,1,2,2-tetra (4-hydroxyphenyl) ethane, thiobisphenol Polyglycidyl ether compounds of polynuclear polyhydric phenol compounds such as alcohol, sulfonyl bisphenol, oxybisphenol, phenol novolak, orthocresol novolak, ethylphenol novolak, butylphenol novolak, octylphenol novolak, resorcin novolak, terpene phenol; ethylene glycol, propylene glycol , Butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, polyglycidyl ethers of polyhydric alcohols such as bisphenol A-ethylene oxide adduct; maleic acid, fumaric acid, itaconic acid , Succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacine , Dimer acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, aliphatic, aromatic or fatty such as endomethylenetetrahydrophthalic acid Glycidyl esters of cyclic polybasic acids and homopolymers or copolymers of glycidyl methacrylate; N, N-diglycidylaniline, bis (4- (N-methyl-N-glycidylamino) phenyl) methane, di Epoxy compounds having a glycidylamino group such as glycidyl orthotoluidine; vinylcyclohexene diepoxide, dicyclopentanediene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6 Methylcyclo Epoxidation products of cyclic olefin compounds such as hexylmethyl-6-methylcyclohexanecarboxylate and bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate; Epoxidation of epoxidized polybutadiene, epoxidized styrene-butadiene copolymer, etc. Examples thereof include heterocyclic compounds such as conjugated diene polymers and triglycidyl isocyanurate. In addition, these epoxy resins have been made high molecular weight by using those internally crosslinked by a prepolymer of terminal isocyanate, or polyvalent active hydrogen compounds (polyhydric phenol, polyamine, carbonyl group-containing compound, polyphosphate ester, etc.). It may be a thing.

  The epoxy resin preferably has an epoxy equivalent of 70 to 3000, and more preferably 90 to 2000. If the epoxy equivalent is less than 70, the physical properties of the cured product may be lowered, and if it is greater than 3000, sufficient curability may not be obtained.

The compound represented by the average composition formula (I) contained in the epoxy resin which is the component (A) used in the present invention is obtained after the one-component thermosetting epoxy resin composition of the present invention is cured. It is a compound for balancing heat resistance and chemical resistance.

Average composition formula (I)
In the above formula, l is 0, 1 or 2, m is a positive number of 0.1 or more and less than 50, ^{R 1} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, ^{R 2} is a group:
Or the group:
R ³ and R ⁴ are each independently a hydrogen atom or an unsubstituted or fluorine-substituted methyl group, and n is an integer of 4 to 12.

In the present invention, the one-component thermosetting epoxy resin composition of the present invention contains 10 to 100% by mass of the compound represented by the above average composition formula (I) in the epoxy resin as the component (A). It is necessary to balance the heat resistance and chemical resistance after the product is cured. When the content of the compound represented by the general formula (I) is less than 10% by mass, the one-component thermosetting epoxy resin composition of the present invention after curing can obtain sufficient heat resistance and chemical resistance. Can not.
In the present invention, it is preferable that the average composition formula (I) R ² in is a group of the following.

The component (B) used in the present invention is a component that acts as a curing catalyst, and an imidazole compound represented by the following general formula (II) is used.
General formula (II);
In the general formula (II), k is an integer of 1 to 5, j is 1 , and R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Or an aryl group, R ⁸ is a group when k is 1,
When k is an integer of 2 to 5, an alkylene group having 1 to 20 carbon atoms, an arylene group, or a group:
R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a cyanomethyl group when k is 1, and when k is an integer of 2 to 5. Is a hydrocarbon group having 1 to 20 carbon atoms.

In this invention, it is preferable to set the usage-amount of (B) component used with respect to 100 mass parts of (A) component to 0.1-10 mass parts, and it is especially referred to as 0.5-5 mass parts. preferable. When the amount is less than 0.1 parts by mass, sufficient curability cannot be obtained. When the amount is more than 10 parts by mass, the cured resin composition cannot obtain sufficient heat resistance. As a result, the physical properties are reduced.
Examples of the component (B) used in the present invention include the compounds exemplified below, but the present invention is not limited thereto.

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In the present invention, in order to improve the balance between workability and adhesiveness, the epoxy resin as the component (A) preferably contains a compound represented by the following general formula (III).
General formula (III)
However, R ¹⁰ and R ¹¹ in the above formula each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

  In the present invention, the compound represented by the general formula (III) is preferably contained in the epoxy resin as the component (A) in an amount of 5 to 30% by mass from the viewpoint of balancing workability and adhesiveness. . If it is less than 5% by mass, sufficient workability and adhesiveness may not be obtained. If it is more than 30% by mass, physical properties of the cured product such as heat resistance and chemical resistance are impaired.

  The polythiol compound of component (C) used in the present invention is a compound that acts as a curing agent. Specifically, for example, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (thioglycolate), ethylene Polyols and mercapto organic acids such as glycol dithioglycolate, trimethylolpropane tris (β-thiopropionate), pentaerythritol tetrakis (β-thiopropionate), dipentaerythritol poly (β-thiopropionate) A thiol compound having two or more thiol groups in the molecule, which does not require the use of a basic substance in the production process, such as a thiol compound obtained by the esterification reaction of 1, 4-butanedithiol, 1, 6-hexanedithiol, 1,10-de An alkyl polythiol compound such as dithiol; a terminal thiol group-containing polyether; a terminal thiol group-containing polythioether; a thiol compound obtained by a reaction between an epoxy compound and hydrogen sulfide; a terminal thiol group obtained by a reaction between a polythiol compound and an epoxy compound In the case of using a basic substance as a reaction catalyst in the production process, such as a thiol compound having an alkali metal ion concentration of 50 ppm or less, a thiol group is added in the molecule. Mention may be made of thiol compounds having at least one.

  As a method for dealkalizing a polythiol compound produced using a basic substance as a reaction catalyst, for example, a polythiol compound to be treated is dissolved in an organic solvent such as acetone or methanol, and an acid such as dilute hydrochloric acid or dilute sulfuric acid is used. After neutralization by addition, a method of removing the generated salt by extraction and / or washing, a method of removing by adsorption using an ion exchange resin, a method of separating and purifying a polythiol compound by distillation, etc. It is done.

  In the present invention, among the above thiol compounds, in particular, dipentaerythritol hexa (3-mercaptobutyrate) and / or 1,3,5-tris (3-mercaptopropyl) -1,3,5- It is preferable to use triazine-2,4,6 (1H, 3H, 5H) -trione because of excellent balance between storage stability and curability.

  In the present invention, the use ratio of the component (A) to the component (C) is usually preferably 0.2 to 2.0 in terms of (number of thiol equivalents / number of epoxy equivalents). If it is less than 0.2, sufficient rapid curability may not be obtained, and if it is more than 2.0, physical properties of the cured product such as heat resistance may be impaired. In the present invention, it is preferable that the ratio (the number of thiol equivalents / the number of epoxy equivalents) is 0.5 to 1.5 from the viewpoint of stabilizing the physical properties of the cured product.

When the one-component thermosetting epoxy resin composition of the present invention is used for an application that requires impregnation adhesive or thin film uniform coating property, the component (A), the component (B), and the component (C) Although but it is necessary to be compatible to uniform one liquid with each other at normal temperature, if used for other purposes, need only be uniformly mixed, so that the liquid form at room temperature, It is not an essential condition that the components (A), (B) and (C) are compatible with each other.

In the one-component thermosetting epoxy resin composition of the present invention, it is preferable to use a silane coupling agent as the component (D). As such a silane coupling agent, for example, a compound represented by the general formula (IV) is preferable.
Formula (IV)
However, p and q in the above formula represent an integer of 0 to 3, p + q is 3, R ¹² and R ¹³ are alkyl groups having 1 to 4 carbon atoms, and R ¹⁴ is an alkyl group having 1 to 20 carbon atoms. An alkylene group or an arylene group, R ¹⁵ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group, or an alkyl group that may contain an oxygen atom, a nitrogen atom, or a sulfur atom.

  Examples of the silane coupling agent represented by the general formula (IV) include 3-aminopropyl-trimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, Examples thereof include N- (2-aminoethyl) aminopropylmethyldimethoxysilane and 3-phenylaminopropyltrimethoxysilane. The composition containing the silane coupling agent represented by the general formula (IV) can contain a silane coupling agent other than the silane coupling agent represented by the general formula (IV). The silane coupling agent other than the silane coupling agent represented by the general formula (IV) is not particularly limited, and can be appropriately selected from known ones.

  In the present invention, if necessary, a curing catalyst other than the imidazole compound; a reactive or non-reactive diluent (plasticizer) such as monoglycidyl ethers, dioctyl phthalate, dibutyl phthalate, benzyl alcohol, and coal tar; Filler or pigment such as glass fiber, carbon fiber, cellulose, silica sand, cement, kaolin, clay, aluminum hydroxide, bentonite, talc, silica, fine powder silica, titanium dioxide, carbon black, graphite, iron oxide, bitumen Lubricants such as candelilla wax, carnauba wax, wax, botaro, beeswax, lanolin, whale wax, montan wax, petroleum wax, fatty acid wax, fatty acid ester, fatty acid ether, aromatic ester, aromatic ether; Agent; thixotropic agent Antioxidants; light stabilizers; ultraviolet absorbers; flame retardants; antifoaming agents; rust inhibitors; may contain known additives such as colloidal silica and colloidal alumina, and further, such as xylene resins and petroleum resins Adhesive resins can also be used in combination.

  The one-component thermosetting epoxy resin composition of the present invention includes, for example, paints and adhesives for concrete, cement mortar, various metals, leather, glass, rubber, plastic, wood, cloth, paper, and the like; Adhesives used for adhesive labels, frozen food labels, removable labels, POS labels, adhesive wallpaper, adhesive flooring, etc. Art paper, lightweight coated paper, cast coated paper, coated paperboard, carbonless copy paper, impregnated paper, etc. Resins used for processed paper; fiber treatment agents such as natural fibers, synthetic fibers, glass fibers, carbon fibers, and metal fibers, converging agents, anti-fraying agents, and processing agents; architectures such as sealing materials, cement admixtures, and waterproofing materials Materials: Can be used for a wide range of applications such as sealants for electronic and electrical equipment.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

  A one-component thermosetting epoxy resin composition was prepared with the formulation shown in Table 1 below, and the following evaluation was performed. The number of the curing catalyst is the number of the imidazole compound described in the specification. The results are as shown in Table 2.

(Glass transition point)
A DSC chart was measured using a differential scanning calorimeter DSC 6220 manufactured by SII Nano Technologies, Inc. with a temperature rising rate of 10 ° C./min and a scanning temperature range of 25 to 300 ° C. Further, the secondary temperature increase was performed under the same conditions, and the glass transition point was measured from the inflection point of the heat capacity.
◎: 70 ° C. or more ○: 65 ° C. to less than 70 ° C. Δ: 55 ° C. to less than 65 ° C. x: less than 55 ° C.

(Adhesiveness)
The shear adhesive strength in a steel plate / steel plate after being cured at 90 ° C. for 1 hour was determined by a method according to JIS K 6850.
◎: 10 MPa or more ○: 5 MPa to less than 10 MPa Δ: 1 MPa to less than 5 MPa × less than 1 MPa

(Swelling resistance)
The obtained one-pack thermosetting epoxy resin composition was cured at 90 ° C. for 1 hour to prepare an evaluation test piece having a size of 10 mm × 10 mm × 0.1 mm. The test piece was dipped in a solution of N-methylpyrrolidone / water = 1/1 and swelled at 60 ° C. for 1 week, and then the weight increase was measured to obtain the swelling rate.
A: Less than 10% B: 10% to less than 15% Δ: 15% to less than 20% x: 20% or more

EP1: Bisphenol A diglycidyl ether (epoxy equivalent 190 g / eq)
EP2: Bisphenol F diglycidyl ether (epoxy equivalent 170 g / eq)
EP3: Cresol novolac epoxy resin (epoxy equivalent 160 g / eq)
EP4: Dicyclopentadienephenol type epoxy resin (epoxy equivalent 239 g / eq)

EP5: Dicyclopentadiene dimethanol type epoxy resin (epoxy equivalent 165 g / eq)
EP6: The following aminophenol epoxy resin (epoxy equivalent 95 g / eq)
T-1: Trimethylolpropane tris (3-mercaptobutyrate)
T-2: Dipentaerythritol Hexakis (3-mercaptopropionate)
T-3: 1,3,5-tris (3-mercaptopropyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione
C-1: 3-Glycidylpropyl-trimethoxysilane
C-2: 3-aminopropyl-trimethoxysilane

  The one-component thermosetting epoxy resin composition of the present invention is a practical resin composition that is easily obtained using readily available raw materials and has a balance between moderate curing characteristics and storage stability, and in particular. In the case of a completely liquid one-pack type resin composition that does not contain a solid curable resin component at room temperature, it has excellent workability and is also suitable for narrow space bonding and impregnation bonding. is there.

Claims (8)

(A) an epoxy resin component, (B) an imidazole compound represented by the following general formula (II), and (C) a polythiol compound, which does not contain an isocyanate group-containing compound, A one-component thermosetting epoxy resin composition comprising 10 to 100% by mass of a compound represented by the following average composition formula (I) in 100% of an epoxy resin component;
Average composition formula (I)
In the above formula, l is 0, 1 or 2, m is a positive number of 0.1 or more and less than 50, ^{R 1} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, ^{R 2} is a group:
Or the group:
R ³ and R ⁴ are each independently a hydrogen atom or an unsubstituted or fluorine-substituted methyl group, and n is an integer of 4 to 12;
Formula (II)
In the general formula (II), k is an integer of 1 to 5, j is 1, and R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Or an aryl group, wherein R ⁸ is a group when k is 1.
When k is an integer of 2 to 5, an alkylene group having 1 to 20 carbon atoms, an arylene group, or a group:
R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a cyanomethyl group when k is 1, and when k is an integer of 2 to 5. Is a hydrocarbon group having 1 to 20 carbon atoms. Wherein 5 to 30 mass% of the epoxy resin in 100% as the component (A) is an epoxy compound represented by the following formula (III), single-liquid type thermosetting epoxy resin according to claim 1 Composition;
Formula (III)
However, R ¹⁰ and R ¹¹ in the above formula each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The one-component thermosetting epoxy resin composition according to claim 1, wherein R ² in the average composition formula (I) is the following group.
  The polythiol compound as the component (C) is dipentaerythritol hexa (3-mercaptobutyrate) and / or 1,3,5-tris (3-mercaptopropyl) -1,3,5-triazine- The one-component thermosetting epoxy resin composition according to any one of claims 1 to 3, comprising 2,4,6 (1H, 3H, 5H) -trione.   The one-component thermosetting epoxy resin composition according to any one of claims 1 to 4, further comprising a silane coupling agent as component (D). The one-component thermosetting epoxy resin composition according to claim 5, wherein the silane coupling agent as the component (D) is a silane coupling agent represented by the following general formula (IV).
Formula (IV)
However, p and q in the above formula represent an integer of 0 to 3, p + q is 3, R ¹² and R ¹³ are alkyl groups having 1 to 4 carbon atoms, and R ¹⁴ is an alkyl group having 1 to 20 carbon atoms. An alkylene group or an arylene group, R ¹⁵ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group, or an alkyl group that may contain an oxygen atom, a nitrogen atom, or a sulfur atom.   The silane coupling agent as the component (D) is 3-aminopropyl-trimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, N- (2-amino) The one-component thermosetting epoxy resin according to claim 5 or 6, which is at least one compound selected from the group consisting of (ethyl) aminopropylmethyldimethoxysilane and 3-phenylaminopropyltrimethoxysilane. Composition. The one-component thermosetting epoxy resin composition according to any one of claims 1 to 7 , wherein the components (A) to (C) are compatible with each other at room temperature and are in a uniform liquid state. A one-component thermosetting epoxy resin composition .