JP2021038337A - Epoxy resin composition - Google Patents

Abstract

To provide an epoxy resin composition having improved adhesive strength and containing a flexible epoxy resin.SOLUTION: An epoxy resin composition contains a flexible epoxy resin, a compound having two or more ester groups and two or more thiol groups in the molecule, and a curing agent.SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition comprising a flexible epoxy resin, a specific thiol compound and a curing agent.

Conventionally, epoxy resins have excellent performance in terms of mechanical properties, electrical properties, thermal properties, chemical resistance, adhesiveness, etc., and therefore paints, insulating materials for electrical and electronic use, and adhesives. It is used for a wide range of purposes such as.

However, while the composition using the epoxy resin has the above-mentioned characteristics, the cured product has a drawback that it is poor in flexibility and very brittle. This means that the cured product is destroyed by some strain, which is very problematic in various applications. For example, when an epoxy resin composition is used for bonding or sealing automobiles, home appliances, and other electrical parts, if the cured product is brittle, cracks will occur due to expansion and contraction due to mechanical vibration and heat, and corrosion and performance of metal parts will occur. It causes a decrease and is not preferable.

Therefore, in order to impart flexibility to the cured product obtained by curing the epoxy resin and improve the brittleness, an epoxy resin composition containing the flexible epoxy resin has been proposed (for example, Patent Documents 1 and 2). ..

Japanese Unexamined Patent Publication No. 63-265915 JP-A-2007-23134

However, when the applicants of the present application evaluated the adhesiveness of the epoxy resin composition containing the flexible epoxy resin, it was found that it was necessary to improve the adhesive strength.

An object of the present invention is to provide an epoxy resin composition containing a flexible epoxy resin having improved adhesive strength.

As a result of studies to solve the above problems, the present inventors have found that the epoxy resin composition contains a flexible epoxy resin, a compound having two or more ester groups and thiol groups in the molecule, and a curing agent. We found that we could solve the problem. Specifically, the present invention includes the following inventions.

[1] An epoxy resin composition containing a flexible epoxy resin, a compound having two or more ester groups and two or more thiol groups in the molecule, and a curing agent.

[2] Compounds having two or more ester groups and two or more thiol groups in the molecule include bis (3-mercaptobutylyloxy) butane, tetraethyleneglycolbis (3-mercaptopropionate), and trimethylpropanthris (3-mercaptopropionate). Thioglycolate), pentaerythritol tetrakis (thioglycolate), ethylene glycol dithioglycolate, trimethylolpropanthris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol poly (3-mercaptopropionate) At least one selected from the group consisting of 3-mercaptopropionate), tris-[(2-mercaptopropionyloxy) -ethyl] -isocyanurate and tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate. The epoxy resin composition according to [1].

[3] The epoxy resin composition according to [1] or [2], wherein the compound having two or more ester groups and two or more thiol groups in the molecule each has three or more ester groups and thiol groups.

[4] Any one of [1] to [3], wherein the curing agent is at least one selected from the group consisting of an epoxy resin amine adduct compound, an epoxy resin imidazole adduct compound, a modified aliphatic polyamine compound, and dicyandiamide. The epoxy resin composition according to the section.

[5] A cured product obtained by curing the epoxy resin composition according to any one of [1] to [4].

According to the present invention, it is possible to provide a resin composition containing a flexible epoxy resin and having significantly improved adhesive strength.

Further, the cured product obtained by curing the epoxy resin composition of the present invention can further improve the flexibility as compared with the cured product obtained from the known flexible epoxy resin composition.

The epoxy resin composition of the present invention is characterized by containing a flexible epoxy resin, a compound having two or more ester groups and two or more thiol groups in the molecule, and a curing agent. Hereinafter, the epoxy resin composition of the present invention will be described in detail.

[Flexible epoxy resin]
The flexible epoxy resin used in the present invention is an epoxy resin that exhibits flexibility when cured, and examples thereof include epoxy resins described in Patent Document 1 and Patent Document 2. Specific structures of the flexible epoxy resin include, for example, (a) two or more epoxy groups, and (b) a divalent non-aromatic hydrocarbon group containing _{2 or more −CH 2- in the main skeleton.} And (c) an epoxy compound containing a divalent aromatic-containing hydrocarbon group containing a divalent aromatic group in the main skeleton, or a polymer thereof. The main skeleton refers to the skeleton having the longest chain among the skeletons having two or more epoxy groups at both ends in (a).

(A) The epoxy group in the two or more epoxy groups is a monovalent group represented by the following formula.

(B) Divalent non-aromatic hydrocarbon group containing 2 or more −CH ₂ − in the main skeleton In the divalent non-aromatic hydrocarbon group, _{the number of −CH 2} − contained in the main skeleton is 2 or more. Is preferable, more preferably 3 or more, still more preferably 4 or more, particularly preferably 5 to 30, and particularly preferably 6 to 20.
The two or more -CH 2 _- may be directly bonded, an ether bond, an ester bond, an amide bond, a double two carbons joined by bonds, two carbon bonded with a triple bond, a thioether It may be bonded via a bond.

Examples of the divalent non-aromatic hydrocarbon group containing two or more -CH _2- in the main skeleton include an alkylene group and an alkyleneoxy group, which have a substituent even if they have a substituent. It does not have to be.
Here, examples of the substituent include a hydroxyl group, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, a silyl group, an acyl group, an acyloxy group, a carboxy group, a cyano group, a nitro group and a hydroxy group. Examples include a group selected from a mercapto group and an oxo group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

The alkyl group used as the substituent may be either linear or branched. The number of carbon atoms of the alkyl group is preferably 1 to 20, more preferably 1 to 14, still more preferably 1 to 12, even more preferably 1 to 6, and particularly preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group and a nonyl group. , And a decyl group. As will be described later, the alkyl group used as the substituent may further have a substituent (secondary substituent). Examples of the alkyl group having such a secondary substituent include an alkyl group substituted with a halogen atom, and specifically, a trifluoromethyl group, a trichloromethyl group, a tetrafluoroethyl group, a tetrachloroethyl group and the like. Can be mentioned.

The number of carbon atoms of the cycloalkyl group used as the substituent is preferably 3 to 20, more preferably 3 to 12, and even more preferably 3 to 6. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and the like.

The alkoxy group used as the substituent may be either linear or branched. The number of carbon atoms of the alkoxy group is preferably 1 to 20, preferably 1 to 12, and even more preferably 1 to 6. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butoxy group, a sec-butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group and a heptyloxy group. Examples thereof include an octyloxy group, a nonyloxy group, and a decyloxy group.

The number of carbon atoms of the cycloalkyloxy group used as the substituent is preferably 3 to 20, more preferably 3 to 12, and even more preferably 3 to 6. Examples of the cycloalkyloxy group include a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

The amino group used as the substituent may be either a linear or branched aliphatic or aromatic group. The number of carbon atoms of the amino group is preferably 1 to 20, preferably 1 to 12, and even more preferably 1 to 6. Examples of the amino group include aminomethyl group, aminoethyl group, aminopropyl group, isopropylamino group, aminobutoxy group, sec-butylamino group, isobutylamino group, tert-butylamino group, aminopentyl group and aminohexyl. Examples thereof include a group, an aminoheptyl group, an aminooctyl group, an aminononyl group, an aminodecyl group, an aminophenyl group and the like.

The silyl group used as the substituent may be either linear or branched. The number of carbon atoms of the silyl group is preferably 1 to 20, preferably 1 to 12, and even more preferably 1 to 6. Examples of the silyl group include methylsilyl group, ethylsilyl group, propylsilyl group, isopropylsilyl group, butoxysilyl group, sec-butylsilyl group, isobutylsilyl group, tert-butylsilyl group, pentylsilyl group, hexylsilyl group and heptylsilyl group. Examples include a group, an octylsilyl group, a nonylsilyl group, and a decylsilyl group.

The acyl group used as a substituent refers to a group represented by the formula: -C (= O) -R ¹ (in the formula, R ¹ is an alkyl group). The ^{alkyl group represented by R 1} may be linear or branched. The number of carbon atoms of the acyl group is preferably 2 to 20, more preferably 2 to 13, and even more preferably 2 to 7. Examples of the acyl group include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, and a pivaloyl group.

The acyloxy group used as a substituent refers to a group represented by the formula: -OC (= O) -R ² (in the formula, R ² is an alkyl group). The ^{alkyl group represented by R 2} may be linear or branched. The number of carbon atoms of the acyloxy group is preferably 2 to 20, more preferably 2 to 13, and even more preferably 2 to 7. Examples of the acyloxy group include an acetoxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group, and a pivaloyloxy group.

The divalent non-aromatic hydrocarbon group containing two or more −CH ₂ − in the main skeleton includes a cycloalkylene group, a cycloalkenylene group, a cycloalkynylene group, and an alkapolyenylene in addition to _{the two or more −CH 2 −.} It may contain a non-aromatic divalent group other than the methylene group, such as a group, an alkadienylene group, and an alkatriinylene group.

Examples of the divalent non-aromatic hydrocarbon group containing two or more −CH ₂ − in the main skeleton include an alkylene group having 2 to 20 carbon atoms which may or may not have a substituent. Alternatively, an alkyleneoxy group having 2 to 20 carbon atoms, which may or may not have a substituent, is preferable. Here, when the above-mentioned carbon number includes a substituent, it is a number excluding the carbon number of the substituent.

The alkyleneoxy group may have, for example, one or more of the structures represented by the following formulas.
(B1) -O-CH (-CH ₃ )-(O- (CH ₂ ) _p ) _q- O-CH (-CH ₃ )-,
(B2)-(O- (CH ₂ ) _r ) _s- ,
(B3)-(O-CH ₂ -CH (-CH ₃ )) _t- ,
(B4) -O-CH ₂ -CH (-OH) -CH _2- (O- (CH ₂ ) _u ) _v ) -O-CH ₂ -CH (-OH) -CH _2- ,
(B5)-(O- (CH ₂ ) _w ) _y- O-CH ₂ -CH (-OH)-and (b6)-(O-CH ₂ -CH (-CH ₃ )) _z- O-CH _2- CH (-OH)-
Here, p, r, u and w are integers of 1 to 20, preferably integers of 1 to 10, more preferably integers of 1 to 6, and even more preferably integers of 1 to 3. Here, q, s, t, v, y and z are integers of 1 to 20, preferably integers of 1 to 10, more preferably integers of 1 to 6, and even more preferably integers of 1 to 3.

及び

を挙げることができる。 (C) Divalent aromatic-containing hydrocarbon group containing a divalent aromatic group in the main skeleton In the divalent aromatic-containing hydrocarbon group containing a divalent aromatic group in the main skeleton, the aromatic group is For example, it may be a phenylene group, a naphthalene group, an anthracene group, or a biphenyl group. The phenylene group may be an ortho, meta, or para phenylene group. The divalent aromatic-containing hydrocarbon group may contain two or more of the aromatic groups. When two or more aromatic groups are contained, the aromatic group may be directly bonded, or may be bonded by an alkylene group, an ether bond, an ester bond, an amide bond, two carbons bonded by a double bond, or a triple bond. It may be bonded via the two carbons and the like. A particularly preferable divalent aromatic-containing hydrocarbon group is

as well as

Can be mentioned.

The epoxy compound of the present invention preferably has a chain-like main skeleton rather than a cyclic shape. If the epoxy compound as a whole is chain-like, a divalent cyclic group such as a divalent aromatic group may be partially contained in the main skeleton. Further, the groups constituting the main skeleton may have the above-mentioned substituents. The polymer of an epoxy compound means a polymer obtained by polymerizing the epoxy compound to, for example, a polymer having a molecular weight of about 500 to 1500.

式（１）及び（２）中、Ｘ、Ｘ^１及びＸ^２で表される２以上の−ＣＨ_２−を主骨格に含む二価の非芳香族炭化水素基である。ここで、２以上の−ＣＨ_２−を主骨格に含む二価の非芳香族炭化水素基の定義は上述したとおりである。式（１）中のｎ個のＸは、互いに同一であっても異なっていてもよい。式（２）中のｍ個のＸ^１、ｍ個のＸ^２は、互いに同一であっても異なっていてもよい。Ｘ、Ｘ^１及びＸ^２は、上述の（ｂ１）〜（ｂ６）から選択される基であってもよい。 The epoxy resin composition of the present invention preferably contains, as a flexible epoxy resin, an epoxy compound represented by the structure represented by the following formula (1) or formula (2) or a polymer thereof.

It is a divalent non-aromatic hydrocarbon group containing two _{or more −CH 2} ^{− represented by X, X 1} and X ² in the main skeleton in the formulas (1) and (2). Here, the definition of a divalent non-aromatic hydrocarbon group containing two or more −CH _{2− in the main skeleton is as described above.} The n Xs in the formula (1) may be the same as or different from each other. X ^1, m-number of X ² m pieces of the formula (2) may being the same or different. X, X ¹ and X ² may be a group selected from the above-mentioned (b1) to (b6).

式（２）’中のＸ^３−６及びＡｒ^３−４の定義は、上述したＸやＡｒの定義と同様である。式（２）’中のＸ^３、Ｘ^４、ｍ’個のＸ^５、ｍ’個のＸ^６は、互いに同一であっても異なっていてもよい。Ｘ及びＸ^３−６は、上述の（ｂ１）〜（ｂ６）から選択される基であってもよい。ｍ’は１〜２０の整数、好ましくは１〜１０の整数である。 In formulas (1) and (2), Ar, Ar ¹ and Ar ² may be the same or different from each other, and may or may not have a substituent. It is a divalent aromatic-containing hydrocarbon group containing an aromatic group in the main skeleton. The definition of a divalent aromatic-containing hydrocarbon group containing a divalent aromatic group in the main skeleton is as described above.
In the formulas (1) and (2), n and m are independently integers of 1 to 20, preferably 1 to 10.
Further, the epoxy resin of the formula (2) may have a structure represented by the following formula (2)'.

^{The definitions of X 3-6} and Ar ^{3-4 in} the formula (2)'are the same as the definitions of X and Ar described above. ^{'X 3, X} 4, m' in number of ^X 5, m 'number of ^{X 6} Equation (2) may being the same or different. X and X ^3-6 may be groups selected from the above-mentioned (b1) to (b6). m'is an integer of 1 to 20, preferably an integer of 1 to 10.

また、例えば、以下の構造（ｈはそれぞれ０〜２０の整数、好ましくは０〜５の整数であり、ｉ、ｊはそれぞれ独立に１〜２０の整数、好ましくは１〜５の整数である）が挙げられる。

Examples of the structure of the flexible epoxy resin or a polymer thereof used in the present invention include the following structures (k is an integer of 1 to 20, preferably an integer of 1 to 5).

Further, for example, the following structure (h is an integer of 0 to 20, preferably an integer of 0 to 5, and i and j are independently integers of 1 to 20, preferably an integer of 1 to 5). Can be mentioned.

The epoxy equivalent of the flexible epoxy resin used in the present invention is, for example, 200 to 1000 g / eq, preferably 300 to 600 g / eq. When the epoxy equivalent is 200 or more, the volatility is low, the viscosity is not low, and the viscosity is easy to handle, which is preferable. Further, when the epoxy equivalent of the epoxy resin is 1000 g / eq or less, the viscosity does not become high and it is suitable in terms of handling. Here, the epoxy equivalent is the mass of the epoxy resin containing one equivalent of the epoxy group, and can be measured according to, for example, JIS K 7236 (2009).

Specific examples of the flexible epoxy resin used in the present invention include, for example, EXA-4850-150, EXA-4816, and EXA-4822 manufactured by DIC Corporation; EP-4000S, EP-4000SS, EP-4003S manufactured by ADEKA Corporation. EP-4010S and EP-4011S; BEO-60E and BPO-20E manufactured by New Japan Chemical Co., Ltd .; YL7175-500, YL7175-1000, YL7410, and YX-7105 manufactured by Mitsubishi Chemical Corporation; and SR-FXB manufactured by Sakamoto Pharmaceutical Co., Ltd. Etc. are exemplified. These may be used alone or in combination of two or more.
[Other epoxy resins]

The epoxy resin composition of the present invention may contain an epoxy resin other than the above-mentioned flexible epoxy resin. Other epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, and catechol. Polyglycidyl ether obtained by reacting polyhydric phenol such as resorcin or polyhydric alcohol such as glycerin or polyethylene glycol with epihalohydrin, glycidyl ether obtained by reacting hydroxycarboxylic acid such as p-oxybenzoic acid with epihalohydrin. Obtained by reacting a polycarboxylic acid such as an ester, phthalic acid, or terephthalic acid with an epihalohydrin to a polyglycidyl ester, 4,4-diaminodiphenylmethane, m-aminophenol, 4-aminophenol, etc., and an epihalohydrin. Examples thereof include polyglycidylamine type epoxy resins and phenol novolac type epoxy resins. Among these epoxy resins, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin and biphenyl type epoxy resin are preferable, bisphenol A type epoxy resin and bisphenol F type epoxy resin are more preferable, and bisphenol A type epoxy resin. Resin is particularly preferred. These epoxy resins may be used alone or in combination of two or more.

Specific examples of other commonly available epoxy resins include bisphenol A type (hereinafter sometimes abbreviated as BPA type) epoxy resin (Mitsubishi Chemical's "jER828EL", "jER827", "jER1001") and bisphenol. F-type epoxy resin ("jER807" manufactured by Mitsubishi Chemical Co., Ltd.), liquid bisphenol AF-type epoxy resin ("ZX1059" manufactured by Nippon Steel Chemical Co., Ltd.), epoxy resin with hydrogenated structure ("YX8000" manufactured by Mitsubishi Chemical Co., Ltd.), dicyclo Pentaziene type polyfunctional epoxy resin ("HP7200" manufactured by DIC), epoxy resin having a butadiene structure ("PB-3600" manufactured by Daicel Chemical Industry Co., Ltd.), epoxy resin having a biphenyl structure ("NC3000H" manufactured by Nippon Kayaku Co., Ltd.) , "NC3000L", "YX4000" manufactured by Mitsubishi Chemical Co., Ltd.) and the like.

The amount of the other epoxy resin used in combination is usually 0.1 to 50 parts by weight, preferably 5 to 35 parts by weight, based on 100 parts by weight of the flexible epoxy resin. By using 0.1 to 50 parts by weight of another epoxy resin, the adhesive strength can be further improved.

[Compound having two or more ester groups and two or more thiol groups in the molecule]
Specific examples of the compound having two or more ester groups and two or more thiol groups in the molecule include bis (3-mercaptobutylyloxy) butane, tetraethylene glycol bis (3-mercaptopropionate), and trimethylolpropane. Tris (thioglycolate), pentaerythritol tetrakis (thioglycolate), ethylene glycol dithioglycolate, trimethylpropanthris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol Poly polyols and mercaptoorganic compounds such as poly (3-mercaptopropionate), tris-[(2-mercaptopropionyloxy) -ethyl] -isocyanurate and tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate. Examples thereof include thiol compounds obtained by the esterification reaction of acids. Among these compounds having two or more ester groups and two or more thiol groups in the molecule, the flexibility of the cured product obtained by curing the epoxy resin composition of the present invention can be further improved, and thus the ester in the molecule. Compounds having 3 or more groups and 3 or more thiol groups are preferable, and trimethylolpropanthris (thioglycolate), pentaerythritol tetrakis (thioglycolate), ethylene glycol dithioglycolate, and trimethylolpropanthris (3-mercaptopropionate) are preferable. ), Pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol poly (3-mercaptopropionate), tris-[(2-mercaptopropionyloxy) -ethyl] -isocyanurate and tris-[(3- Mercaptopropionyloxy) -ethyl] -isocyanurate is more preferred, with trimethylolpropanthris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate) and tris-[(3-mercaptopropionyloxy)- Ethyl] -isocyanurate is more preferred. Further, these may be used alone or in combination of two or more.

The amount of the compound having two or more ester groups and two or more thiol groups in the molecule used in the present invention is the total amount of all epoxy resins (flexible epoxy resin and other epoxy resins) contained in the epoxy resin composition of the present invention. ) 100 parts by weight, usually 1 to 100 parts by weight, preferably 10 to 90 parts by weight, more preferably 20 to 70 parts by weight, still more preferably 30 to 60 parts by weight.

[Curing agent]
As the curing agent contained in the epoxy resin composition of the present invention, those generally used as a curing agent for epoxy resins can be used, and among them, from the viewpoint of handleability of the epoxy resin composition, it is possible to use. A latent curing agent can be preferably used. In the present invention, the latent curing agent is a compound that is insoluble in the above-mentioned epoxy resin at room temperature (25 ° C.), solubilizes by heating, and functions as a curing agent for the epoxy resin. Examples thereof include an imidazole compound solid at room temperature, an epoxy resin amine adduct compound, an epoxy resin imidazole adduct compound, a modified aliphatic polyamine compound, and dicyandiamide. Among these latent curing agents, epoxy resin amine adduct compounds, epoxy resin imidazole adduct compounds, modified aliphatic polyamine compounds and dicyandiamide are preferable. Examples of the imidazole compound solid at room temperature include 2-heptadecylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-undecylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-. Phenyl-4-benzyl-5-hydroxymethylimidazole, 2,4-diamino-6- (2-methylimidazolyl- (1))-ethyl-S-triazine, 2,4-diamino-6- (2'-methyl) Imidazolyl- (1)')-Ethyl-S-triazine isocyanuric acid adduct, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1- Cyanoethyl-2-methylimidazole-trimeritate, 1-cyanoethyl-2-phenylimidazole-trimeritate, N- (2-methylimidazolyl-1-ethyl) -urea, N, N'-(2-methylimidazolyl- (1)-) Ethyl) -aziboyldiamide and the like are exemplified. Examples of the epoxy resin amine adduct compound include Ajinomoto Fine-Techno Co., Ltd. Amicure MY-24, Amicure MY-R, and adduct compounds shown in JP-A-57-100127. Examples of the epoxy resin imidazole adduct compound include Ajinomoto Fine-Techno's Amicure PN-23, Amicure PN-R, and Air Product Japan's Sanmide LH-210. Examples of the modified aliphatic polyamine compound include Fujicure FXE-1000 and Fujicure FXR-1121 manufactured by T & K TOKA Co., Ltd. These curing agents may be used alone or in combination of two or more.

The amount of the curing agent used in the present invention is usually 0.1 to 100 parts by weight, preferably 1 to 60 parts by weight, more preferably 1 to 60 parts by weight, based on 100 parts by weight of the total epoxy resin contained in the epoxy resin composition of the present invention. 5 to 30 parts by weight.

<Other additives>
The epoxy resin composition of the present invention further comprises a reactive diluent, solvent, additive (eg, curing accelerator, inorganic filler, flame retardant, sizing agent, coupling agent, colorant, thixotropic agent, stabilizer, charge). It may contain an inhibitor, etc.).

<Method for preparing epoxy resin of the present invention>
For the preparation of the epoxy resin composition of the present invention, a general stirring and mixing device and mixing conditions are applied in the same manner as in the usual method for preparing an epoxy resin composition. For example, a flexible epoxy resin, a compound having two or more ester groups and two or more thiol groups in the molecule, and a curing agent, and if necessary, another epoxy resin, a reactive diluent, a solvent, an additive, etc. are made uniform. The epoxy resin composition of the present invention can be prepared by sufficiently mixing up to. Examples of the device used at this time include a mixing roll, a dissolver, a planetary mixer, a kneader, and an extruder. As the mixing conditions, the epoxy resin or the like may be dissolved and / or reduced in viscosity and heated in order to improve the stirring and mixing efficiency. Further, it may be cooled as necessary to remove frictional heat generation, reaction heat generation and the like.

<Cured product obtained by curing the epoxy resin composition of the present invention>
Subsequently, a method for producing a cured product obtained by curing the epoxy resin composition of the present invention and the cured product will be described in detail.

A cured product obtained by curing the epoxy resin composition of the present invention can be obtained, for example, by pouring the epoxy resin composition of the present invention into a mold, casting it, and then curing it by heat. When curing by heat, the curing temperature varies depending on the type of curing agent and epoxy resin used, but is usually 25 to 250 ° C, preferably 80 to 200 ° C, and more preferably 80 to 150 ° C. Further, when curing by heat, it may be cured at a high temperature at once, but it may be cured by gradually raising the temperature, for example, by performing initial curing and then subsequent curing. At that time, for example, the initial curing may be performed at 80 to 150 ° C., and the post-curing may be performed at 100 ° C. to 230 ° C.

The cured product obtained by curing the epoxy resin composition of the present invention has improved adhesive strength as compared with the cured product obtained from a known flexible epoxy resin composition, and further, as shown in Examples described later. Since the flexibility is also improved, it can be suitably used as an adhesive or a sealing agent for, for example, automobiles, home appliances and other electric parts.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the examples, each measured value was in accordance with the following method and measurement conditions.

[Adhesive strength test]
The epoxy resin compositions obtained in each Example, Comparative Example and Reference Example were applied to a steel plate (JIS3100 C1100P: 1.6 × 25 × 100 mm) as an adherend, and cured at 150 ° C. for 60 minutes for testing. I made a piece. The prepared test piece was allowed to cool in a room at 25 ° C., and the steel-steel tensile shear adhesive strength was measured according to the method for measuring the tensile shear adhesive strength in JIS K 6850.

<Examples 1 to 16, Comparative Example 1 and Reference Example 1>
The materials were weighed into plastic containers so as to have the compounding composition (part by weight) shown in Table 1, mixed sufficiently using a disper (ROBO MIX manufactured by TOKUSHU KIKA), and then defoamed to obtain an epoxy resin composition. .. With respect to the obtained epoxy resin composition, the steel-steel tensile shear adhesive strength was measured according to the above measuring method. The results are shown in Table 1. The details of each material used are as follows.

EXA-4850-150: Vinyl ether-modified bisphenol type epoxy resin manufactured by DIC ・ EXA-4816: DIC company, aliphatic chain modified bisphenol A type epoxy resin ・ DER331: Dow Chemical Co., Ltd., bisphenol A type epoxy resin ・Amicure PN-23: Ajinomoto Fine Techno Co., Ltd., Epoxy resin imidazole adduct compound, Fujicure-FXR-1121: T & K TOKA, modified aliphatic polyamine compound, Fujicure-FXE-1000: T & K TOKA, modified aliphatic polyamine compound -TEMPIC: SC Organic Chemical Co., Ltd., Tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate ・ TMMP: SC Organic Chemical Co., Ltd., trimethylolpropanthris (3-mercaptopropionate)
・ PEMP: Pentaerythritol tetrakis (3-mercaptopropionate) manufactured by SC Organic Chemistry Co., Ltd.
BD1: Showa Denko Co., Ltd., Bis (3-mercaptobutylyloxy) Butane Aerosil 200: Nippon Aerosil Co., Ltd., fine powder silica

[Flexibility confirmation test]
The epoxy resin compositions obtained in each Example, Comparative Example and Reference Example were poured into a mold and cured at 150 ° C. for 180 minutes to prepare a cured product. The obtained cured product was processed to prepare a No. 3 dumbbell type test piece (thickness 3 mm). Tensile test [tensile speed: 5 mm / min, load FS: 5 kN, distance between chucks] for the above test piece using a Tensileon universal material tester (manufactured by Orientec Co., Ltd.) according to the measurement method of JIS K 7161. (Distance between marked lines): 60 mm] was performed, and the tensile elongation at break of the cured product was measured. The results are shown in Table 2.

<Examples 17 to 20, Comparative Example 2 and Reference Example 2>
The materials were weighed into plastic containers so as to have the compounding composition (part by weight) shown in Table 2, mixed sufficiently using a disper (ROBO MIX manufactured by TOKUSHU KIKA), and then defoamed to obtain an epoxy resin composition. .. With respect to the obtained epoxy resin composition, the tensile elongation at break was measured according to the above measuring method. The results are shown in Table 2.

Claims (5)

An epoxy resin composition containing a flexible epoxy resin, a compound having two or more ester groups and two or more thiol groups in the molecule, and a curing agent. Compounds having two or more ester groups and two or more thiol groups in the molecule are bis (3-mercaptobutylyloxy) butane, tetraethyleneglycolbis (3-mercaptopropionate), and trimethylpropanthris (thioglycolate). ), Pentaerythritol tetrakis (thioglycolate), ethylene glycol dithioglycolate, trimethylolpropanthris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol poly (3-mercapto) Propionate), tris-[(2-mercaptopropionyloxy) -ethyl] -isocyanurate and tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate, at least one selected from the group. The epoxy resin composition according to claim 1. The epoxy resin composition according to claim 1 or 2, wherein the compound having two or more ester groups and two or more thiol groups in the molecule each has three or more ester groups and thiol groups. The epoxy resin according to any one of claims 1 to 3, wherein the curing agent is at least one selected from the group consisting of an epoxy resin amine adduct compound, an epoxy resin imidazole adduct compound, a modified aliphatic polyamine compound and dicyandiamide. Composition. A cured product obtained by curing the epoxy resin composition according to any one of claims 1 to 4.