JP2976617B2 - Liquid acid anhydride-based one-part epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in storage stability, is rapidly cured by heating, and has electrical properties after curing.
A cured resin product with excellent thermal and chemical properties is obtained.Completely uniform liquid acid anhydride-based one-part epoxy resin composition with excellent workability and economic efficiency, especially suitable for applications such as impregnation and casting. It is about things.

[0002]

2. Description of the Related Art An epoxy resin composition using an acid anhydride as a curing agent has a low viscosity, so that it can be easily impregnated into narrow gaps, and has electrical, mechanical, thermal and chemical properties after curing. Because of its excellent properties, it is widely used for sealing capacitors, impregnating coils in large motors and generators, sealing transformers, magnetic heads, and the like.

[0003] However, an epoxy resin composition comprising an epoxy resin and an acid anhydride is excellent in storage stability and pot life, but has a disadvantage that it requires a high temperature and a long time for curing. In order to solve such a defect, a tertiary amine or a salt thereof (Japanese Unexamined Patent Publication (Kokai) No. 64-606) is used as a curing accelerator.
25, JP-A-59-140220), imidazole or salts thereof (JP-A-58-83024, JP-A-57-1)
9001), organic phosphines (JP-A-63-3040)
18, JP-A-57-40524), quaternary phosphonium salts (JP-A-1-25487, JP-A-61-15123)
0) etc. are used. When such a curing accelerator is used, the curability is greatly improved, but the disadvantage that storage stability deteriorates is newly generated. Due to poor storage stability, the worker must prepare the composition each time, and at that time, the epoxy resin, acid anhydride, and curing accelerator are each weighed, and not only the workability is bad but also , Errors may occur. Furthermore, since the excess composition cannot be preserved, it must be discarded, which is not preferable in terms of resource saving and environmental problems. Further, as a curing accelerator, a salt of p-toluenesulfonic acid and a tertiary amine such as triethylamine (JP-A-60-452)
No. 0) has been studied, which has excellent storage stability but has a problem in curability.

In order to solve such problems of storage stability and curability, a dispersion-type latent curing accelerator has been studied (JP-A-60-4524 and JP-A-60-72917). Although a material almost satisfying the curability is being obtained, since the curing accelerator is insoluble powder, it does not penetrate into narrow gaps, leaving insufficiently cured portions, resulting in deterioration of various physical properties.

Therefore, development of a liquid acid anhydride-based one-part epoxy resin composition having both excellent storage stability and curability and improved workability has been desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to satisfy the two contradictory conditions of storage stability and curability, and to set the electrical properties, mechanical properties, thermal properties and chemical properties of a cured product after curing. It is an object of the present invention to provide a liquid acid anhydride-based one-part epoxy resin composition having excellent mechanical properties.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, they have found that the curing accelerator for a liquid acid anhydride-based one-part epoxy resin composition has nitrogen at the first position of imidazoles. By using a compound in which atoms are sulfonylated, it has been found that storage stability and curability are improved, and that various properties of a cured product after curing are also excellent. Based on this finding, the present invention has been completed. That is, the present invention comprises, as essential components, (1) an epoxy resin having two or more epoxy groups in one molecule, (2) an acid anhydride, and (3) a compound in which the nitrogen atom at position 1 of imidazoles is sulfonylated.
The mixing ratio of (1) and (2) is such that the ratio of (anhydride equivalent number) / (epoxy equivalent number) is 0.8 to 1.2, and (3) is 0 to 100 parts by weight of epoxy resin. The present invention relates to a liquid acid anhydride-based one-pack epoxy resin composition characterized by being 0.1 to 10 parts by weight and a cured epoxy resin product obtained by heating the same.

The epoxy resin used in the present invention is not particularly limited as long as it has an average of two or more epoxy groups per molecule. For example, bisphenol A, bisphenol F, bisphenol AD,
Catechol, polyglycidyl ether obtained by reacting polychlorophenol such as resorcinol or polyhydric alcohol such as glycerin or polyethylene glycol with epichlorohydrin, or p-hydroxybenzoic acid, β
A glycidyl ether ester obtained by reacting a hydroxycarboxylic acid such as hydroxynaphthoic acid with epichlorohydrin, or a polyglycidyl ester obtained by reacting a polycarboxylic acid such as phthalic acid or terephthalic acid with epichlorohydrin, and further epoxidation Examples include, but are not limited to, phenol novolak resins, epoxidized cresol novolak resins, epoxidized polyolefins, other urethane modified epoxy resins, alicyclic epoxy resins, and the like.

The acid anhydride used in the present invention is not particularly limited, and is shown below as a typical example. For example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endo Methylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexenedicarboxylic anhydride, Examples include, but are not limited to, alkylstyrene-maleic anhydride copolymers, chlorendic anhydride, tetrabromophthalic anhydride, polyazeleic anhydride, and the like.

The compound in which the nitrogen atom at the 1-position of the imidazole used in the present invention is sulfonylated will be described below. Examples of the compound in which the 1-position nitrogen atom of imidazoles is sulfonylated include, for example, compounds in which the 1-position nitrogen atom of imidazoles is p-toluenesulfonylated, benzenesulfonylated, methanesulfonylated, trifluoromethanesulfonylated, and the like. .

The compound in which the nitrogen atom at the 1-position of the imidazole used in the present invention is sulfonylated can be obtained by converting the corresponding imidazole and the corresponding sulfonyl chloride into an organic solvent such as chloroform, dichloromethane, toluene or the like with a tertiary amine such as triethylamine. It can be prepared by using an amine.

The imidazoles are not particularly limited, but are shown below as typical examples. For example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-n-propylimidazole, 2-isopropylimidazole, 2-phenylimidazole, 2-n-undecylimidazole, 2-n-heptadecylimidazole, 4-methyl Imidazole, 4-phenylimidazole, 2-ethyl-4-methylimidazole, 4-methyl-2-phenylimidazole, 4,5-diphenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4- Examples include, but are not limited to, methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, and the like.

The mixing ratio of the epoxy resin and the acid anhydride in the liquid acid anhydride-based one-part epoxy resin composition of the present invention is (acid anhydride equivalent number) / (epoxy equivalent number) of 0.8 to 0.8.
1.2. Here, acid anhydride equivalent = (molecular weight of acid anhydride) / (number of acid anhydride groups). 1 of imidazoles
The amount of the compound in which the nitrogen atom at the second position is sulfonylated is in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin.

In preparing the liquid acid anhydride-based one-part epoxy resin composition of the present invention, a compound obtained by sulfonating the nitrogen atom at the 1-position of imidazole is dissolved in the acid anhydride in advance, and this is then added to the epoxy resin. It is desirable to mix with the resin.

The liquid acid anhydride-based one-part epoxy resin composition of the present invention may contain various additives such as fillers, diluents, solvents, pigments, flexibility-imparting agents, and antioxidants, if necessary. Can be added.

[0016]

The liquid acid anhydride-based one-part epoxy resin composition of the present invention has excellent storage stability and curability, and the cured product after curing has electrical, mechanical, thermal and chemical properties. Good properties, such as sealing of capacitors, large motors,
It is suitable for applications such as impregnation of coils in generators, sealing of transformers, and magnetic heads. Further, since the storage stability is remarkably excellent, it is possible to supply the epoxy resin as a main component in a state where three components of an epoxy resin, a curing agent, an acid anhydride and a curing accelerator are blended. This eliminates the need for weighing and eliminates the risk of errors during weighing, so that the composition of the present invention is very useful in terms of improving workability. Further, after use, the composition of the present invention is very useful also in terms of saving resources because it can be stored and does not need to be disposable.

[0017]

The present invention will be described in detail below with reference to examples and comparative examples. In the following examples, the stability was evaluated as 2
Alternatively, the viscosity was determined after 3 weeks, and the curability was evaluated by gel time at 150 ° C. The viscosity was measured according to JIS K 6833, and the gel time was measured by a Yasuda gel timer.

Production Example 1 In a three-necked flask, 1.1 equivalents of triethylamine and chloroform were added to and dissolved in imidazoles and imidazoles shown in Table 1, and the equivalents of imidazoles and methanesulfonyl chloride were added dropwise under ice cooling. . After completion of the dropwise addition, the mixture was returned to room temperature and stirred for 3 hours. The precipitated triethylamine hydrochloride was separated by filtration, and the filtrate was concentrated to obtain a crude product of methanesulfonylated imidazoles. By purifying this by column chromatography,
Methanesulfonylated imidazoles (A) to (C) were obtained. Table 1 shows the shapes and melting points of the compounds (A) to (C).

[0019]

[Table 1]

Production Example 2 A chloroform solution of p-toluenesulfonyl chloride was placed in a three-necked flask, and while stirring at room temperature, an equivalent amount of p-toluenesulfonyl chloride was obtained from a dropping funnel.
The chloroform solution of 1.2 equivalents of triethylamine was added dropwise to the imidazoles and p-toluenesulfonyl chloride shown in (1). After completion of the dropwise addition, the mixture was stirred at room temperature for 3 to 5 hours. After completion of the reaction, the solvent was distilled off under reduced pressure to obtain a crude product. Ethyl acetate was added thereto, and the insoluble material was filtered off. The filtrate was concentrated and purified by column chromatography.
p-Toluenesulfonylated imidazoles (D)-
(G) was obtained. Table 2 shows the shapes of the compounds (D) to (G).

[0021]

[Table 2]

Example 1 Methanesulfonylated imidazoles (A) to (C) prepared by the above method were added to 10 parts by weight of methylhexahydrophthalic anhydride, HN-5500 (trade name of Hitachi Chemical Co., acid anhydride equivalent: 166). ) Was added and dissolved by heating at 120 ° C. for 15 minutes. Bisphenol A type epoxy resin, Epicoat 828 (product name of Yuka Shell Co., epoxy equivalent 190), 100 parts by weight, HN-5
The epoxy resin compositions (a) to (c) were obtained by adding 85 parts by weight of 500 and 5 parts by weight of a solution in which the methanesulfonylated imidazole was dissolved, followed by defoaming and mixing. (A) to (c) were completely uniform liquids.
(A)-(c) gel time at 150 ° C., initial viscosity,
Table 3 shows the viscosities after standing at 25 ° C. for 3 weeks. Further, (a) to (c) are carried out at 120 ° C. for 2 hours or 150 ° C.
By curing at 30 ° C. for 30 minutes, a good cured product could be obtained.

[0023]

[Table 3]

Example 2 A p-weight was added to 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.).
One part by weight of toluenesulfonylated imidazole is dissolved at room temperature, and 100 parts by weight of Epicoat 828 (trade name of Yuka Shell Co., Ltd.) is added thereto, followed by defoaming and mixing to obtain epoxy resin compositions (d) to (g). I got (D) ~
(G) was a completely uniform liquid. Table 4 shows the initial viscosities (d) to (g) and the viscosities after standing at 25 ° C. for 2 weeks. By curing (d) to (g) at 120 ° C. for 1.5 to 2 hours, a good cured product was obtained.

[0025]

[Table 4]

Comparative Example 1 1-cyanoethyl-2-ethyl-4-methylimidazole (100 parts by weight of Epikote 828 (trade name of Yuka Shell Co., Ltd.) and 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.) Curesol 2E4MZ-CN (Shikoku Chemicals) (1 part by weight) was added to obtain an epoxy resin composition (x). (X) was completely liquid. The gel time of this (x) at 120 ° C. was 9 minutes. In addition, the initial viscosity was 10 poise at 25 ° C., and it was gelled after standing at 25 ° C. for 2 days.

Comparative Example 2 2-Ethyl-4-methylimidazole 1 was added to a mixture of 100 parts by weight of Epikote 828 (trade name of Yuka Shell Co.) and 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.).
By adding parts by weight, an epoxy resin composition (y) was obtained.
(Y) was completely liquid. The gel time of this (y) at 120 ° C. was 5 minutes. The initial viscosity was 7 poise at 25 ° C., and the gel was formed after standing at 25 ° C. for 2 days.

Continuation of front page (56) References JP-A-63-75024 (JP, A) JP-A-2-84426 (JP, A) JP-A-64-70523 (JP, A) JP-A-63-92639 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08G 59/40 C08G 59/50-59/58

Claims (2)

(57) [Claims] An essential component is (1) an epoxy resin having two or more epoxy groups in one molecule, (2) an acid anhydride, and (3) a compound in which a nitrogen atom at the 1-position of imidazoles is sulfonylated. The mixing ratio of (1) and (2) is such that the (acid anhydride equivalent number) / (epoxy equivalent number) ratio is 0.8 to 1.2,
(3) is 0.1 to 100 parts by weight of the epoxy resin.
A liquid acid anhydride-based one-part epoxy resin composition, which is 10 parts by weight. 2. A cured epoxy resin obtained by heating the one-part liquid acid anhydride-based epoxy resin composition according to claim 1.