JP2005075915A - Curing agent composition for epoxy resin and epoxy resin composition containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the storage stability of a mixture of an acid anhydride-based curing agent, and a tertiary amine-based curing accelerator for an epoxy resin. <P>SOLUTION: One or more kinds of hydroxybenzoic acid esters (C) represented by general formula (1) [wherein, R<SP>1</SP>O is a 2-3C oxyalkylene group; R<SP>2</SP>is a 1-12C linear or branched alkyl group or a 5-12C cycloalkyl group; and n is an integer of 0-10] of 0.1-5 pts. wt. based on the acid anhydride-based curing agent (A) for the epoxy resin of 100 pts. wt. is compounded with a mixture of the component (A) and the tertiary amine-based curing accelerator (B). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a curing agent composition for an epoxy resin, and more specifically, for an epoxy resin including a mixture containing an acid anhydride curing agent and a tertiary amine curing accelerator, and the storage stability of the mixture is improved. The present invention relates to a curing agent composition, an epoxy resin composition containing the epoxy resin curing agent composition, and a storage stability improving method and a storage stability improving agent for the mixture.

  Conventionally known polyamide, polyamine, acid anhydrides and the like are known curing agents for epoxy resins. Among these, since the reaction rate of the epoxy resin and the acid anhydride is very slow, a tertiary amine, a tertiary amine salt, a quaternary ammonium salt, an organic metal salt, or the like is used as a curing accelerator. Of these, tertiary amines, especially imidazoles, are curing accelerators widely used for heat-resistant applications because they give the most cured epoxy resin products with excellent heat resistance.

  The tertiary amine is usually added in an amount of about 0.1 to 5 parts by weight with respect to 100 parts by weight of the epoxy resin. If a curing accelerator is mixed in advance with either the epoxy resin or the acid anhydride, Weighing and mixing time is shortened and blending work is easy. Usually, when a tertiary amine is added to an epoxy resin, the resulting mixture of epoxy resin and tertiary amine increases in viscosity over time and lacks storage stability. For this reason, except in special cases, the tertiary amine is generally added to the acid anhydride.

However, when a mixture of a tertiary amine and an acid anhydride is stored at room temperature for a long time, the acid anhydride is partially decomposed, so carbon dioxide is generated and the storage container expands, and the storage container often ruptures. There's a problem. As a method for solving such a problem, a method of adding water or alcohol to an acid anhydride (Patent Document 1) has been proposed, but this method has an effect of suppressing the generation of carbon dioxide gas to some extent. And cured epoxy resin obtained by curing using an acid anhydride to which alcohol is added have problems such as reduced water resistance and heat resistance.
Japanese Patent Publication No.55-30728

  The present invention includes a mixture containing an acid anhydride curing agent and a tertiary amine curing accelerator, and a curing agent composition for an epoxy resin with improved storage stability of the mixture, and an epoxy resin composition containing the same The purpose is to provide.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors blend a specific hydroxybenzoic acid ester with a specific ratio in a mixture containing an acid anhydride-based curing agent and a tertiary amine-based curing accelerator. As a result, it was found that the storage stability of the obtained curing agent composition for epoxy resin was remarkably improved, and the present invention was completed based on this finding.

  That is, the present invention is a method for improving the storage stability of the following epoxy resin curing agent composition, an epoxy resin composition containing the same, an acid anhydride curing agent and a mixture containing a tertiary amine curing accelerator, The present invention provides a storage stability improver of the mixture and a cured epoxy resin.

  Item 1 (A) An acid anhydride-based curing agent and (B) a tertiary amine-based curing accelerator are contained as essential components, and (C) General formula (1)

［式中、Ｒ¹Ｏは、炭素数２又は３のオキシアルキレン基を表し、Ｒ²は、炭素数１〜１２の直鎖状若しくは分岐鎖状のアルキル基又は炭素数５〜１２のシクロアルキル基を表し、ｎは、０〜１０の整数を表す。］
で表されるヒドロキシ安息香酸エステルから選ばれる少なくとも１種を、（Ａ）成分１００重量部に対して、０．１〜５重量部の割合で含有することを特徴とするエポキシ樹脂用硬化剤組成物。

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
A curing agent composition for epoxy resins, containing at least one selected from hydroxybenzoic acid esters represented by the formula (A) at a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of component (A). Stuff.

  Item 2 (A) component is hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 1-methylnorbornane-2,3-dicarboxylic anhydride, 5 -Methylnorbornane-2,3-dicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid anhydride, 1-methylnadic acid anhydride, 5-methylnadic acid anhydride, nadic acid anhydride, phthalic acid anhydride, Item 2. The curing agent for epoxy resin according to item 1, which is at least one selected from the group consisting of tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride and dodecenyl succinic anhydride. Composition.

  Item 3 The component (B) is lauryldimethylamine, dimethylcyclohexylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol, 1,8-diazabicyclo [5 , 4,0] undec-7-ene, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2 -Phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1- Cyanoethyl-2-undecyl Midazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-undecylimidazolylethyl) ) -1,3,5-triazine, 2,4-diamino-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole and Item 3. The curing agent composition for an epoxy resin according to Item 1 or 2, which is at least one selected from the group consisting of 2-phenyl-4-methyl-5-hydroxymethylimidazole.

  Item 4 The component (B) is 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl- 4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2 -Undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-un Decylimidazolylethyl) -1,3,5-triazine, 2,4 From diamino-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole Item 4. The epoxy resin curing agent composition according to Item 3, which is at least one member selected from the group consisting of:

  Item 5. The epoxy resin curing agent composition according to any one of Items 1 to 4, wherein the component (C) is at least one selected from the group consisting of compounds with n = 0 in the general formula (1).

  Item 6. An epoxy resin composition comprising the epoxy resin and the epoxy resin curing agent composition according to any one of Items 1 to 5.

  Item 7. The epoxy resin composition according to Item 6, comprising the epoxy resin and the curing agent composition for epoxy resin according to Item 5.

Item 8 is a method for improving the storage stability of a mixture containing (A) an acid anhydride curing agent and (B) a tertiary amine curing accelerator as essential components,
(i) (C) General formula (1)

［式中、Ｒ¹Ｏは、炭素数２又は３のオキシアルキレン基を表し、Ｒ²は、炭素数１〜１２の直鎖状若しくは分岐鎖状のアルキル基又は炭素数５〜１２のシクロアルキル基を表し、ｎは、０〜１０の整数を表す。］
で表されるヒドロキシ安息香酸エステルから選ばれる少なくとも１種を配合するか、又は、
(ii)（Ａ）成分に（Ｃ）成分を予め配合してなる混合物を（Ｂ）成分と混合することからなり、且つ、
(i)及び(ii)のいずれの場合も、（Ｃ）成分の配合量が、（Ａ）成分１００重量部に対して、０．１〜５重量部であることを特徴とする方法。

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
Or at least one selected from hydroxybenzoic acid esters represented by:
(ii) mixing a mixture of (A) component and (C) component in advance with (B) component; and
In both cases (i) and (ii), the amount of component (C) is 0.1 to 5 parts by weight per 100 parts by weight of component (A).

  Item 9 The method according to Item 8, wherein the component (C) is at least one selected from the group consisting of compounds wherein n = 0 in the general formula (1).

  Item 10 General formula (1)

［式中、Ｒ¹Ｏは、炭素数２又は３のオキシアルキレン基を表し、Ｒ²は、炭素数１〜１２の直鎖状若しくは分岐鎖状のアルキル基又は炭素数５〜１２のシクロアルキル基を表し、ｎは、０〜１０の整数を表す。］
で表されるヒドロキシ安息香酸エステルから選ばれる少なくとも１種を含むことを特徴とする、（Ａ）酸無水物系硬化剤及び（Ｂ）三級アミン系硬化促進剤を必須成分として含有する混合物の貯蔵安定性向上剤。

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
A mixture containing (A) an acid anhydride-based curing agent and (B) a tertiary amine-based curing accelerator as essential components, comprising at least one selected from hydroxybenzoic acid esters represented by: Storage stability improver.

  Item 11 The storage stability improver according to Item 10, wherein n is 0.

  Item 12 An epoxy resin cured product obtained by curing the epoxy resin composition according to Item 6 or 7.

  According to the present invention, 0.1 to 5 parts by weight of a hydroxybenzoic acid ester is blended with 100 parts by weight of the acid anhydride curing agent in a mixture containing the acid anhydride curing agent and the tertiary amine curing accelerator. As a result, the amount of carbon dioxide generated in the resulting epoxy resin curing agent composition is greatly suppressed, and an epoxy resin curing agent composition having excellent storage stability can be obtained.

  The cured epoxy resin obtained by curing the epoxy resin using the curing agent composition of the present invention has excellent heat resistance and electrical characteristics.

  Hereinafter, the present invention will be described in detail.

<Curing agent composition for epoxy resin>
The curing agent composition for epoxy resin of the present invention is a composition containing an acid anhydride curing agent (A), a tertiary amine curing accelerator (B), and a hydroxybenzoic acid ester (C).

Component (A): Acid anhydride-based curing agent The acid anhydride-based curing agent for epoxy resin that is component (A) used in the present invention is particularly limited as long as it has an acid anhydride group in the molecule. A wide range of conventionally known acid anhydride curing agents for epoxy resins can be used.

  As the acid anhydride curing agent used in the present invention, those having a wide range of acid anhydride equivalents can be used, but generally the acid anhydride equivalent is 98 to 500, preferably 150 to 300 acid anhydride. It is preferable to use a system curing agent.

  Specifically, hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 1-methylnorbornane-2,3-dicarboxylic anhydride, 5-methylnorbornane -2,3-dicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid anhydride, 1-methylnadic acid anhydride, 5-methylnadic acid anhydride, nadic acid anhydride, phthalic acid anhydride, tetrahydrophthalic acid Examples include anhydrides, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, and terpene diene or triene compounds such as α-terpinene and alloocimene and maleic anhydride. Diels-Alder reactants and of these anhydrides with unsaturated bonds Containing additives, including structural isomers or geometric isomers of these acid anhydrides, mixtures or modified products thereof are exemplified. Among them, acid anhydride curing agents that are liquid at room temperature by methods such as structural isomerization, geometric isomerization, and mixing of two or more of these acid anhydrides are exemplified.

  In addition, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, ethylene glycol bisanhydro trimellitate, deacetic acid condensation product of triacetin and trimellitic anhydride, and hydrogenated products of these compounds A polyfunctional acid anhydride can also be used in combination.

  These acid anhydride curing agents may be used alone or in combination of two or more.

  Among these, hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 1-methylnorbornane-2,3-dicarboxylic anhydride, 5-methylnorbornane- 2,3-dicarboxylic anhydride, norbornane-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, and 4-methyltetrahydrophthalic anhydride are preferred. Among these, 4-methylhexahydrophthalic anhydride, a mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride are particularly preferable. In this mixture, the weight ratio of both components is not particularly limited, but the ratio (a1: a2) of 3-methyltetrahydrophthalic anhydride (a1) to 4-methyltetrahydrophthalic anhydride (a2) is 1: 9-9: 1, particularly 2: 8 to 8: 2.

(B) Component: Tertiary amine-based curing accelerator As the tertiary amine-based curing accelerator of the (B) component used in the present invention, epoxy resins or epoxy resins and (A) an acid anhydride-based curing agent are used. There is no particular limitation as long as it has an action of promoting the reaction. For example, lauryldimethylamine, dimethylcyclohexylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol, 1,8-diazabicyclo [5,4,0] undeca -7-ene, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methyl Imidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecyl Imidazole 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-undecylimidazolylethyl)- 1,3,5-triazine, 2,4-diamino-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole, 2- Tertiary amines such as phenyl-4-methyl-5-hydroxymethylimidazole can be mentioned. Furthermore, a salt of the tertiary amine and a carboxylic acid (for example, a fatty acid having 1 to 30 carbon atoms, particularly 1 to 8 carbon atoms) can also be used. These curing accelerators can be used alone or in admixture of two or more.

  Among these tertiary amine-based curing accelerators, imidazole-based curing accelerators are preferable. Specifically, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2 -Ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1 -Cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3 , 5-triazine, 2,4-diamino-6- 2-undecylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4, Examples include 5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc., among which 2-ethyl-4-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole Is preferred.

  (B) Although it can select suitably from the range currently used as a compounding quantity of a component, generally it is 0.1-5 with respect to 100 weight part of acid anhydride type hardening | curing agents which are (A) components. It is preferable to use parts by weight, and more preferably 0.3 to 4 parts by weight. When the blending amount is less than 0.1 parts by weight, the curing rate is lowered, and when it exceeds 5 parts by weight, the mechanical strength such as Tg is lowered.

Component (C): Hydroxybenzoic acid ester The hydroxybenzoic acid ester of the component (C) represented by the general formula (1) used in the present invention is commercially available, or hydroxybenzoic acid and the general formula (2).

［式中、Ｒ¹及びＲ²は一般式（１）と同義であり、ｎは０〜１０の整数を表す。］
で表されるアルコール成分とを、常法に従って、好ましくは窒素等の不活性ガス雰囲気下、エステル化触媒の存在下又は無触媒下で加熱攪拌しながらエステル化することにより容易に製造することができる化合物である。一般式（２）で表されるアルコール成分は公知であるか公知の方法により製造できる入手容易な化合物である。

[In the formula, R ¹ and R ² are as in formula (1) synonymous, n represents an integer of 0. ]
Can be easily produced by esterification with heating and stirring in the presence of an esterification catalyst or in the absence of a catalyst, preferably in an inert gas atmosphere such as nitrogen, according to a conventional method. It is a compound that can be. The alcohol component represented by the general formula (2) is a known compound or an easily available compound that can be produced by a known method.

  As the component (C), a compound in which n = 0 in the general formula (1), that is, a linear or branched alkyl (carbon number 1 to 12) ester of hydroxybenzoic acid, a cycloalkyl hydroxybenzoate (carbon Examples are esters of formula 5-12) and esters of alkoxypolyalkylene glycol and hydroxybenzoic acid represented by the general formula (2) where n = 1 to 10 (particularly n = 1 or 2).

Examples of the alkylene oxide having 2 or 3 carbon atoms represented by R ¹ include ethylene oxide and propylene oxide, and ethylene oxide is particularly preferable. The addition form of these alkylene oxides may be any one of single addition of one alkylene oxide, random addition, block addition or alternating addition of two alkylene oxides.

In the general formula (1), R ² is a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms. A linear or branched alkyl group of 1 to 12, particularly 1 to 8, is preferable.

  The substitution position of the hydroxyl group of the hydroxybenzoic acid ester represented by the general formula (1) is not particularly limited, and may be o-, m-, or p-position.

Among these hydroxybenzoic esters, a compound in which n = 0 in the general formula (1), that is, a linear or branched C ₁ -C ₁₂ (particularly C ₁ -C ₈ ) alkyl ester of hydroxybenzoic acid, C ₅ -C ₁₂ cycloalkyl esters of hydroxybenzoic acid are preferred, in particular benzoic acid linear or branched C ₁ -C ₁₂ (especially C ₁ -C ₈₎ alkyl esters are preferred.

Specific examples of the hydroxybenzoic acid ester represented by the general formula (1) include methyl hydroxybenzoate, ethyl hydroxybenzoate, n-propyl hydroxybenzoate, isopropyl hydroxybenzoate, n-butyl hydroxybenzoate, and hydroxybenzoate. Isobutyl acid, n-pentyl hydroxybenzoate, n-hexyl hydroxybenzoate, n-heptyl hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, n-octyl hydroxybenzoate, n-nonyl hydroxybenzoate, isononyl hydroxybenzoate, hydroxybenzoic acid n- decyl, etc. hydroxybenzoic acid lauryl o-, m- or p- hydroxybenzoic acid linear or branched C ₁ -C ₁₂ alkyl esters; hydroxybenzoic acid cyclopentyl, hydroxybenzoic acid Sik Hexyl, o- of hexyl, etc., to hydroxybenzoic acid 4-methylcyclohexyl, m- or p- hydroxybenzoic acid C ₅ -C ₁₂ cycloalkyl ester; hydroxybenzoic acid ester of methoxypolyethylene glycol (n = 1~10), methoxy polypropylene Hydroxybenzoic acid ester of glycol (n = 1-10), hydroxybenzoic acid ester of ethoxypolyethylene glycol (n = 1-10), hydroxybenzoic acid ester of ethoxypolypropylene glycol (n = 1-10), 1-propoxypolyethylene Hydroxybenzoate of glycol (n = 1-10), Hydroxybenzoate of 1-propoxypolypropylene glycol (n = 1-10), Hydroxybenzoate of 2-propoxypolyethylene glycol (n = 1-10) Acid ester, hydroxybenzoic acid ester of 2-propoxypolypropylene glycol (n = 1-10), hydroxybenzoic acid ester of 1-butoxypolyethylene glycol (n = 1-10), 1-butoxypolypropylene glycol (n = 1-10) ), Hydroxybenzoic acid ester of cyclohexyloxypolyethylene glycol (n = 1-10), hydroxybenzoic acid ester of cyclohexyloxypolypropylene glycol (n = 1-10), 2-ethyl-1-hexyloxypolyethylene Linear or branched C ₁ -C ₁₂ such as hydroxybenzoic acid ester of glycol (n = 1 to 10), hydroxybenzoic acid ester of 2-ethyl-1-hexyloxypolypropylene glycol (n = 1 to 10), etc. Archi O-, m- or p-hydroxybenzoic acid esters of oxypolyalkylene glycol or C ₅ -C ₁₂ cycloalkyloxy polyalkylene glycol.

Among these, in particular, a compound in which n = 0 in the general formula (1), in particular, methyl hydroxybenzoate, ethyl hydroxybenzoate, n-propyl hydroxybenzoate, isopropyl hydroxybenzoate, n-butyl hydroxybenzoate, hydroxy Isobutyl benzoate, n-pentyl hydroxybenzoate, n-hexyl hydroxybenzoate, n-heptyl hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, n-octyl hydroxybenzoate, n-nonyl hydroxybenzoate, isononyl hydroxybenzoate Linear or branched C ₁ -C ₁₂ alkyl ester of o-, m- or p-hydroxybenzoic acid, such as n-decyl hydroxybenzoate, lauryl hydroxybenzoate, cyclopentyl hydroxybenzoate, hydroxybenzoic acid Cyclo Hexyl, a cyclohexyl, etc., to hydroxybenzoic acid 4-methylcyclohexyl o-, m- or p- hydroxybenzoic acid C ₅ -C ₁₂ cycloalkyl ester.

Among these, in particular, methyl hydroxybenzoate, ethyl hydroxybenzoate, n-propyl hydroxybenzoate, isopropyl hydroxybenzoate, n-butyl hydroxybenzoate, isobutyl hydroxybenzoate, n-pentyl hydroxybenzoate, n-hydroxybenzoate n- O- such as hexyl, n-heptyl hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, n-octyl hydroxybenzoate, n-nonyl hydroxybenzoate, isononyl hydroxybenzoate, n-decyl hydroxybenzoate, lauryl hydroxybenzoate, etc. Preferred are linear or branched C ₁ -C ₁₂ alkyl esters of m- or p-hydroxybenzoic acid, especially linear or branched C ₁ -C ₈ alkyl esters.

  These hydroxybenzoic acid esters can be used alone or in admixture of two or more.

  (C) As addition amount of a component, 0.1-5 weight part with respect to 100 weight part of (A) component, Especially 0.5-4 weight part is preferable. When the amount is less than 0.1 part by weight, the effect of storage stability decreases, and when the amount exceeds 5 parts by weight, the physical properties of the cured epoxy resin tend to be lowered.

  The addition temperature of component (C) can be sufficiently dissolved and mixed at room temperature, but can be dissolved and mixed by heating at a temperature not higher than the boiling point of the acid anhydride, if necessary.

  The component (C) may be mixed with the component (A) in advance, or may be added to and mixed with the mixture of the component (A) and the component (B).

  Moreover, the mixture containing an acid anhydride and a tertiary amine-based curing accelerator may produce a precipitate at a temperature of room temperature (5-35 ° C.) or less, but the curing agent composition for epoxy resins of the present invention. Then, since it contains the compound represented by the general formula (1) as the component (C), there is almost no formation of precipitates, and a uniform transparent solution epoxy resin curing agent composition can be obtained. .

  In addition, in this specification, room temperature refers to the temperature range of 5-35 degreeC.

  Although the hardening | curing agent composition for epoxy resins of this invention can be prepared by using combining said (A) component, (B) component, and (C) component suitably, the following combination is especially preferable.

(A) (A) a mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + (B) 2-ethyl-4-methylimidazole + (C) hydroxybenzoic acid linear or branched Chain C1-C8 alkyl ester (A) (A) Mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + (B) 2-methylimidazole + (C) linear chain of hydroxybenzoic acid Or branched C1-C8 alkyl ester (U) (A) Mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + (B) 1-benzyl-2-methylimidazole + (C ) Linear or branched C1-C8 alkyl ester of hydroxybenzoic acid (D) (A) 4-methylhexahydrophthalic anhydride + (B) 2-ethyl-4-methylimidazole + (C) hydro Linear or branched C1-C8 alkyl ester of benzoic acid (e) (A) 4-methylhexahydrophthalic anhydride + (B) 2-methylimidazole + (C) hydroxybenzoic acid linear Or branched C1-C8 alkyl ester (F) (A) 4-methylhexahydrophthalic anhydride + (B) 1-benzyl-2-methylimidazole + (C) hydroxybenzoic acid linear or branched chain More specifically, the following combinations are preferred.

A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + methyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + ethyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-propyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + isopropyl benzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-butyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + isobutyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-pentyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-hexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-heptyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + 2-ethylhexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-octyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + methyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + ethyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride, 2-methylimidazole, n-propyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + isopropyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + n-butyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + isobutyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + n-pentyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + n-hexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + n-heptyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + 2-ethylhexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 2-methylimidazole + n-octyl hydroxybenzoate;
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + methyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + ethyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-propyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + isopropyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1 + 1-benzyl-2-methylimidazole + n-butyl hydroxybenzoate,
Mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + isobutyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-pentyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-hexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-heptyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + 2-ethylhexyl hydroxybenzoate,
A mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-octyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + methyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + ethyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-propyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + isopropyl benzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-butyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + isobutyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-pentyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-hexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-heptyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + 2-ethylhexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-ethyl-4-methylimidazole + n-octyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + methyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + ethyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + n-propyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + isopropyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + n-butyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + isobutyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + hydroxybenzoic acid n-pentyl,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + n-hexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + n-heptyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + 2-ethylhexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 2-methylimidazole + n-octyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + methyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + ethyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-propyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + isopropyl benzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-butyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + isobutyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + hydroxybenzoic acid n-pentyl,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-hexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-heptyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + 2-ethylhexyl hydroxybenzoate,
4-methylhexahydrophthalic anhydride + 1-benzyl-2-methylimidazole + n-octyl hydroxybenzoate and the like.

  In addition, in the curing agent composition for epoxy resin of the present invention, if necessary, in a molecule such as water, methanol, ethanol and other lower alcohols having 1 to 4 carbon atoms, ethylene glycol, propylene glycol, and phenylpropylene glycol. A modifying agent such as a compound having at least one hydroxyl group can be added as long as the effects of the present invention are not impaired.

  Furthermore, flexibility-imparting agents such as polyalkylene glycols, antioxidants, plasticizers, lubricants, silane-based coupling agents, surface treatment agents, flame retardants, antistatic agents, colorants, antistatic agents as necessary Agents, leveling agents, ion trapping agents, sliding properties improving agents, various rubbers, impact resistance improving agents such as organic polymer beads, thixotropic agents, surfactants, surface tension reducing agents, antifoaming agents, anti-settling agents Conventionally known additives such as a light diffusing agent, an ultraviolet absorber, an antioxidant, a release agent, a fluorescent agent, a conductive filler, a pigment, and a dye can also be added. The mixing ratio of these additives is not particularly limited.

<Epoxy resin composition>
The epoxy resin composition used for this invention is a composition containing an epoxy resin and the hardening | curing agent composition for epoxy resins of this invention.

  Examples of the epoxy resin used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, hydroquinone type epoxy resin, Naphthalene skeleton type epoxy resin, tetraphenylolethane type epoxy resin, DPP type epoxy resin, trishydroxyphenylmethane type epoxy resin, dicyclopentagenphenol type epoxy resin, 3,4-epoxycyclohexylmethyl-3 ', 4'- Alicyclic epoxy resins such as epoxycyclohexanecarboxylate and vinylcyclohexene diepoxide, diglycidyl ether of bisphenol A ethylene oxide adduct, bisphenol Diglycidyl ether of propylene oxide adduct, cycloglycan dimethanol diglycidyl ether, polyglycidyl ether of aliphatic polyhydric alcohol, polyglycidyl ester of polybasic acid such as diglycidyl ester of hexahydrophthalic anhydride, butyl glycidyl ether And glycidyl ether having one epoxy group such as alkyl glycidyl ether such as lauryl glycidyl ether, phenyl glycidyl ether, and cresyl glycidyl ether. These compounds can be used alone or in combination of two or more.

  The epoxy equivalent of the epoxy resin is not particularly limited and can be appropriately selected from a wide range. Usually, an epoxy resin having an epoxy equivalent of 90 to 5000, preferably 150 to 1000, particularly preferably 150 to 500 is used. Is advantageous.

  The compounding amount of the epoxy resin curing agent composition used in the present invention can be appropriately selected from a wide range. Usually, the equivalent ratio (An / Ep) of the acid anhydride group (An) to the epoxy group (Ep) is: It is advantageous to use in the range of about 0.7 to 1.2, preferably about 0.8 to 1.1.

  In the epoxy resin composition of the present invention, the conventionally known additive described in the section <Epoxy resin curing agent composition> as an optional component depending on the application and purpose, as long as the effects of the present invention are not impaired. Can be added.

  From the viewpoint of using an epoxy resin and an acid anhydride-based curing agent in a ratio of the above-mentioned acid anhydride / epoxy group equivalent ratio range, the epoxy resin curing agent composition of the present invention is blended with an epoxy resin. In general, the epoxy resin composition may be prepared at the following blending ratio. First, a book containing (A) an acid anhydride curing agent, (B) a tertiary amine curing accelerator, and (C) a hydroxybenzoic acid ester represented by the general formula (1) in 100 parts by weight of an epoxy resin. The curing agent composition of the invention is 1.3 to 700 parts by weight, preferably 10 to 300 parts by weight, more preferably 20 to 240 parts by weight, and if necessary, the above-mentioned additives are added so as not to impair the effects of the present invention. The epoxy resin composition of the present invention can be produced by adding the amount and further mixing.

  The epoxy resin composition thus obtained can be applied to sealing, impregnation, coating, insulation, etc. of electric / electronic parts such as coils and transformers.

  As the means for blending the epoxy resin composition and optional components of the present invention, known conventional means known in this field can be used. Examples thereof include stirring and mixing, roll and melt mixing with a kneader, wet mixing using an appropriate organic solvent, and dry mixing.

  Curing conditions for curing the epoxy resin composition containing the epoxy resin curing agent of the present invention are not particularly limited, and are performed under known conventional curing conditions (for example, 50 to 200 ° C. for 1 minute to 24 hours). be able to.

<Hardened epoxy resin>
A cured product obtained by curing the epoxy resin composition of the present invention under the above-mentioned curing conditions can be used in a wide range of industrial fields because of its excellent balance of heat resistance, insulation, and the like. It can be advantageously used in the fields of electric / electronic fields such as electrical insulating materials and heat-resistant paints.

<Method for improving storage stability>
As described above, the mixture of the acid anhydride curing agent as the component (A) and the tertiary amine curing accelerator as the component (B), as it is, generates carbon dioxide. Although the storage stability is inferior, the mixture is obtained by blending the compound represented by the general formula (1), which is the component (C) of the present invention, into the mixture of the component (A) and the component (B). It is possible to suppress the generation of carbon dioxide from the water and improve the storage stability.

  As a blending method of the component (C), for example, the component (C) may be added to and mixed with the mixture of the component (i) (A) and the component (B), and (ii) the component (A) (C) component may be blended in advance and then mixed with component (B).

Accordingly, the present invention is a method for improving the storage stability of a mixture containing (A) an acid anhydride curing agent and (B) a tertiary amine curing accelerator as essential components,
(i) Mixing the component (C) with the mixture, or
(ii) Mixing the component (C) with the component (A) in advance and mixing the component (B) with the component (B), and in both cases (i) and (ii) The blending amount is 0.1 to 5 parts by weight with respect to 100 parts by weight of the component (A).

  Also in this method, the use ratio of the component (A) and the component (B), the preferred compounds of the respective components, and the preferred combinations of the respective components are the same as those described in the above section <Curing agent composition for epoxy resin>. It is.

<Storage stability improver>
As described above, by blending the compound represented by the general formula (1), which is the component (C) of the present invention, into the mixture of the component (A) and the component (B), Carbon dioxide generation can be suppressed and storage stability can be improved.

  Accordingly, the present invention provides a storage stability improver for a mixture of the component (A) and the component (B), characterized by comprising the compound represented by the general formula (1) as the component (C). It is also what you do.

  Preferred examples of the component (C) used as the storage stability improver, preferred combinations with the components (A) and (B), and the respective usage ratios of the components (A), (B) and (C) Etc. are the same as those described in the section <Curing agent composition for epoxy resin>.

  Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to these examples.

Example 1
A 7: 3 (weight ratio) mixture of 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride (below) was added to a 200 mL four-necked flask equipped with a stir bar, thermometer, and nitrogen gas inlet tube. , Abbreviated as “MeTHPA”) 100 g, 2 g of methyl salicylate (ie, methyl o-hydroxybenzoate) and 2 g of 2-ethyl-4-methylimidazole (product name “CUREZOL 2E4MZ”, Shikoku Chemical Industries, Ltd.) Manufactured, hereinafter referred to as “2E4MZ”), and heated and mixed at 80 ° C. for 30 minutes with stirring to prepare a curing agent composition for epoxy resin.

Example 2
A curing agent composition for epoxy resin was prepared in the same manner as in Example 1 except that methyl salicylate was changed to methyl p-hydroxybenzoate.

Example 3
A curing agent composition for epoxy resin was prepared in the same manner as in Example 1 except that methyl salicylate was changed to n-propyl p-hydroxybenzoate.

Example 4
A curing agent composition for epoxy resin was prepared in the same manner as in Example 1 except that methyl salicylate was changed to 2-ethylhexyl p-hydroxybenzoate.

Comparative Example 1
In Example 1, except that methyl salicylate was not blended, the same operation as in Example 1 was performed to prepare a mixture composed of an acid anhydride curing agent and a tertiary amine curing accelerator.

Example 5
A curing agent composition for epoxy resin was prepared in the same manner as in Example 4 except that 2E4MZ was changed to lauryldimethylamine (hereinafter abbreviated as “2PTA”).

Comparative Example 2
A mixture comprising an acid anhydride and a tertiary amine curing accelerator was prepared in the same manner as in Example 5 except that 2-ethylhexyl p-hydroxybenzoate was not blended in Example 5.

Test example 1
The test method in Test Example 1 is as follows. That is, glass test tubes each containing 52 g of epoxy resin curing agent composition prepared in Examples 1 to 5 (containing 50 g of MeTHPA) and 51 g of a mixture prepared in Comparative Examples 1 and 2 (containing 50 g of MeTHPA) were used. It left still in a 40 degreeC thermostat for 3 days, and measured the gas generation amount.

  The amount of gas generated was measured as follows. The curing agent composition for epoxy resin prepared in Examples 1 to 5 and the mixture prepared in Comparative Examples 1 and 2 were placed in a cylindrical glass test tube having an inner diameter of 2.7 cm and a height of 20 cm, respectively. After replacing the inside of the test tube with nitrogen, it was sealed with a rubber stopper equipped with a device for measuring the internal pressure. The test tube was left in a constant temperature bath at 40 ° C. for 3 days, and the gas corresponding to the amount of gas generated was collected using a graduated syringe while confirming the difference between the internal pressure and the external pressure with a manometer. Correction was performed using a test tube containing only MeTHPA as a blank.

  The results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1, and the results of Example 5 and Comparative Example 2 are shown in Table 2. The gas generation amounts shown in Tables 1 and 2 are values converted to 0 ° C. and 1 atm (101.3 kPa). The smaller the amount of gas generated, the better the storage stability.

表１及び表２より、炭酸ガス発生量が、無添加の場合と比較して著しく抑制されていることが明らかである。

From Table 1 and Table 2, it is clear that the amount of carbon dioxide gas generated is remarkably suppressed as compared with the case of no addition.

  In addition, 2-ethylhexyl p-hydroxybenzoate used in Examples 4 and 5 is handled in that it has a low odor and is easily soluble when added to a mixture of an acid anhydride and a tertiary amine curing accelerator. It had the advantage of being easy.

Example 6
To 90 g of the epoxy resin curing agent composition containing the acid anhydride curing agent, tertiary amine curing accelerator and hydroxybenzoic acid ester (that is, methyl p-hydroxybenzoate) produced in Example 2, bisphenol A was added. Type epoxy resin (product name “Epicoat 828”, Japan Epoxy Resin Co., Ltd., epoxy equivalent 190) 100 g was mixed at room temperature and defoamed to obtain a uniform solution to obtain an epoxy resin composition.

  Subsequently, after pouring the said composition into a type | mold, it heat-hardened at 100 degreeC for 2 hours, and also at 130 degreeC for 5 hours. The obtained cured epoxy resin was cut into a size for measurement, and the physical properties of the cured product were measured according to the following method.

1) Glass transition temperature The glass transition temperature was measured using a differential scanning calorimeter (DSC) according to JIS K7121. The measurement temperature was 25 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min.

2) Volume resistivity The volume resistivity was measured according to JIS K6911.

3) Dielectric constant and dielectric loss tangent The dielectric constant and dielectric loss tangent were measured in accordance with JIS K6911. The measurement frequency is 1 MHz.

As a result, the glass transition temperature was 141 ° C., the volume resistivity was 10 ¹⁶ Ω · cm, the dielectric constant (1 MHz) was 3.1, and the dielectric loss tangent (1 MHz) was 1.1%.

  As can be seen from these physical properties, the cured product obtained from the epoxy resin composition of the present invention has an excellent balance of heat resistance, insulation, and the like, and can be used in a wide range of industrial fields. It can be advantageously used in the fields of electrical and electronic materials such as insulating materials and heat resistant paints.

  According to the present invention, the mixture containing the acid anhydride curing agent (A) and the tertiary amine curing accelerator (B) is represented by the general formula (1) as the component (C). By blending the hydroxybenzoic acid ester, the amount of carbon dioxide generated in the mixture is greatly suppressed, and a curing agent composition for epoxy resins excellent in storage stability can be obtained. Moreover, the hardened | cured material excellent in heat resistance and an electrical property can be obtained by hardening the epoxy resin composition which mix | blended this.

Claims (12)

(A) An acid anhydride-based curing agent and (B) a tertiary amine-based curing accelerator are contained as essential components, and (C) General formula (1)

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
A curing agent composition for epoxy resins, containing at least one selected from hydroxybenzoic acid esters represented by the formula (A) at a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of component (A). Stuff. (A) component is hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 1-methylnorbornane-2,3-dicarboxylic anhydride, 5-methyl Norbornane-2,3-dicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid anhydride, 1-methylnadic acid anhydride, 5-methylnadic acid anhydride, nadic acid anhydride, phthalic acid anhydride, tetrahydrophthal 2. The curing agent composition for epoxy resin according to claim 1, which is at least one selected from the group consisting of an acid anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, and dodecenyl succinic anhydride. . Component (B) is lauryldimethylamine, dimethylcyclohexylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol, 1,8-diazabicyclo [5,4. , 0] undec-7-ene, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl -4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl- 2-undecyl imida , 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-undecylimidazolyl) Ethyl) -1,3,5-triazine, 2,4-diamino-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole And at least one selected from the group consisting of 2-phenyl-4-methyl-5-hydroxymethylimidazole. Component (B) is 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4- Methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-un Decylimidazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- (2-methylimidazolylethyl) -1,3,5-triazine, 2,4-diamino-6- (2-undecylimidazolyl) Ethyl) -1,3,5-triazine, 2,4-dia From no-6- (2-ethyl-4-methylimidazolylethyl) -1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole The hardening | curing agent composition for epoxy resins of Claim 3 which is at least 1 sort (s) chosen from the group which consists of. (C) Component is at least 1 sort (s) chosen from the group which consists of a compound which is n = 0 in General formula (1), The hardening | curing agent composition for epoxy resins in any one of Claims 1-4. The epoxy resin composition containing an epoxy resin and the hardening | curing agent composition for epoxy resins in any one of Claims 1-5. The epoxy resin composition of Claim 6 containing the epoxy resin and the hardening | curing agent composition for epoxy resins of Claim 5. A method for improving the storage stability of a mixture containing (A) an acid anhydride curing agent and (B) a tertiary amine curing accelerator as essential components,
(i) (C) General formula (1)

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
Or at least one selected from hydroxybenzoic acid esters represented by:
(ii) mixing a mixture of (A) component and (C) component in advance with (B) component; and
In both cases (i) and (ii), the amount of component (C) is 0.1 to 5 parts by weight per 100 parts by weight of component (A). The method according to claim 8, wherein the component (C) is at least one selected from the group consisting of compounds in which n = 0 in the general formula (1). General formula (1)

[Wherein R ¹ O represents an oxyalkylene group having 2 or 3 carbon atoms, and R ² represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl having 5 to 12 carbon atoms. Represents a group, and n represents an integer of 0 to 10. ]
A mixture containing (A) an acid anhydride-based curing agent and (B) a tertiary amine-based curing accelerator as essential components, comprising at least one selected from hydroxybenzoic acid esters represented by: Storage stability improver. The storage stability improver according to claim 10, wherein n is 0. The epoxy resin hardened | cured material formed by hardening | curing the epoxy resin composition of Claim 6 or 7.