JPH0578456A - Liquid acid anhydride-based one pot epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in shelf life and curability and capable of producing a cured material excellent in electrical properties, mechanical properties, etc., after cured by blending an epoxy resin with an acid anhydride and a specified compound in a specified ratio. CONSTITUTION:The objective composition contains (A) an epoxy resin (e.g. bisphenol A) having two or more epoxy groups in one molecule, (B) an acid anhydride (e.g. phthalic anhydride) and (C) a compound (e.g. compound obtained by p-toluenesulfonylation of imidazole at N of 1 position) obtained by sulfonylation of an imidazole at N of 1 position as the essential components, in a ratio of the component (A) to the component (B) expressed in terms of [(number of acid anhydride equivalent)/(number of epoxy equivalent)] and the amount of the component (C) based on 100 pts.wt. epoxy resin are 0.8-1.2 and 0.1-10 pts.wt., respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent storage stability, is rapidly cured by heating, and has electrical characteristics after curing.
Completely uniform liquid acid anhydride-based one-component epoxy resin composition with excellent workability and economic efficiency, which is suitable for applications such as impregnation and casting, because it gives a cured resin product with excellent thermal and chemical properties. 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 is easily impregnated into a narrow space, and its electrical, mechanical, thermal and chemical properties after curing are high. Due to its excellent properties, it is widely used for capacitor encapsulation, coil impregnation for large motors, generators, etc., transformer encapsulation, magnetic heads, etc.

However, while the epoxy resin composition comprising an epoxy resin and an acid anhydride is excellent in storage stability and pot life, it has the drawback of requiring high temperature and long time for curing. In order to eliminate such drawbacks, a tertiary amine or a salt thereof as a curing accelerator (JP-A-64-606)
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-61-152323).
0) etc. are used. When such a curing accelerator is used, the curability is significantly improved, but the storage stability becomes worse, which is a new drawback. Since the storage stability is poor, the worker must prepare the composition each time, and at that time, each of the epoxy resin, the acid anhydride, and the curing accelerator must be weighed, which causes not only poor workability. , There may be an error. Furthermore, since the surplus composition cannot be stored, it must be discarded, which is not preferable in terms of resource saving and environmental problems. Further, a salt of p-toluenesulfonic acid and a tertiary amine such as triethylamine as a curing accelerator (JP-A-60-452).
0) has been investigated, but it has excellent storage stability, but has a problem in curability.

In order to solve such problems of storage stability and curability, dispersion-type latent curing accelerators have been investigated (JP-A-60-4524, JP-A-60-72917), and storage stability, Although curing properties are almost being obtained, since the curing accelerator is an insoluble powder, it will not penetrate into the narrow gaps, and insufficient curing will remain, resulting in deterioration of various physical properties.

Therefore, it has been earnestly desired to develop a liquid acid anhydride-based one-component epoxy resin composition which has excellent storage stability and curability and improved workability.

[0006]

The object of the present invention is to satisfy the two contradictory conditions of storage stability and curability, and to obtain electrical properties, mechanical properties, thermal properties and chemical properties of the cured product after curing. To provide a liquid acid anhydride-based one-component epoxy resin composition having excellent physical properties.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that the nitrogen atom at the 1-position of imidazoles is used as a curing accelerator for a liquid acid anhydride-based one-component epoxy resin composition. It was found that the use of the compound in which the atom was sulfonylated improved the storage stability and the curability, and the cured product after curing was excellent in various properties, and based on this finding, the present invention was completed. That is, the present invention includes (1) an epoxy resin having two or more epoxy groups in one molecule, (2) an acid anhydride, and (3) a compound obtained by sulfonylating the nitrogen atom at the 1-position of imidazoles, as an essential component,
The mixing ratio of (1) and (2) is such that (acid anhydride equivalent number) / (epoxy equivalent number) ratio is 0.8 to 1.2, and (3) is 0 based on 100 parts by weight of the epoxy resin. The present invention relates to a liquid acid anhydride-based one-component epoxy resin composition characterized by being 1 to 10 parts by weight and an epoxy resin cured product obtained by heating the same.

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

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 acid anhydride, ethylene glycol bis trimellitate, glycerol tris trimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endo Methylenetetrahydrophthalic anhydride, Methylendomethylenetetrahydrophthalic anhydride, Methylbutenyltetrahydrophthalic anhydride, Dodecenylsuccinic anhydride, Hexahydrophthalic anhydride, Methylhexahydrophthalic anhydride, Succinic anhydride, Methylcyclohexenedicarboxylic anhydride, Examples thereof include, but are not limited to, alkylstyrene-maleic anhydride copolymer, chlorendic anhydride, tetrabromophthalic anhydride, and polyazelaic anhydride.

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

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

The imidazoles are not particularly limited and 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 thereof include methyl-5-hydroxymethylimidazole and 2-phenyl-4-benzyl-5-hydroxymethylimidazole, but the invention is not limited thereto.

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

When preparing the liquid acid anhydride-based one-component epoxy resin composition of the present invention, a compound in which the nitrogen atom at the 1-position of the imidazole group is sulfonylated is dissolved in advance in an acid anhydride, and the epoxy compound is added. It is desirable to mix with a resin.

The liquid acid anhydride-based one-pack type epoxy resin composition of the present invention may contain various additives such as a filler, a diluent, a solvent, a pigment, a flexibility-imparting agent and an antioxidant, if necessary. Can be added.

[0016]

The liquid acid anhydride-based one-pack type epoxy resin composition of the present invention has excellent storage stability and curability, and has excellent electrical properties, mechanical properties, thermal properties, and chemical properties after curing. Since it has good physical properties, it can seal capacitors, large motors,
Suitable for coil impregnation of generators, transformer sealing, magnetic heads, etc. Further, since the storage stability is remarkably excellent, it becomes possible to supply the composition in which the three components of the epoxy resin as the main component, the acid anhydride as the curing agent and the curing accelerator are blended. This saves the trouble of weighing and eliminates the risk of errors occurring during weighing, and thus the composition of the present invention is very useful in improving workability. Furthermore, since it can be stored after use, it does not have to be thrown away, and the composition of the present invention is very useful in terms of resource conservation and protection of the environment.

[0017]

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

Production Example 1 1.1 equivalents of triethylamine and chloroform were added to and dissolved in imidazoles and imidazoles shown in Table 1 in a three-necked flask, and imidazoles and equivalents of methanesulfonyl chloride were added dropwise under ice cooling. .. After completion of dropping, the mixture was returned to room temperature and stirred for 3 hours. The precipitated triethylamine hydrochloride was filtered off, 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 three-necked flask was charged with a chloroform solution of p-toluenesulfonyl chloride, and the mixture was stirred at room temperature and the amount of p-toluenesulfonyl chloride equivalent to that in Table 2 was added from a dropping funnel.
A chloroform solution of 1.2 equivalents of triethylamine was added dropwise to the imidazoles and p-toluenesulfonyl chloride shown in. After completion of dropping, 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 to this, insoluble matter was filtered off, the filtrate was concentrated, and then 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 10 parts by weight of methylhexahydrophthalic anhydride and HN-5500 (Hitachi Kasei Co., Ltd., acid anhydride equivalent 166) were added to the methanesulfonylated imidazoles (A) to (C) prepared by the above method. ) Was added and the mixture was dissolved by heating at 120 ° C. for 15 minutes. Bisphenol A type epoxy resin, Epicoat 828 (trade name of Yuka Shell Co., epoxy equivalent 190) 100 parts by weight, HN-5
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 above-mentioned methanesulfonylated imidazoles were dissolved and performing defoaming mixing. (A) to (c) were completely uniform liquids.
(A) to (c) gel time at 150 ° C., initial viscosity,
Table 3 shows the viscosity after standing for 3 weeks at 25 ° C. Also, (a) to (c) at 120 ° C. for 2 hours or 150
A good cured product could be obtained by curing at 30 ° C. for 30 minutes.

[0023]

[Table 3]

Example 2 In 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), p-
Epoxy resin compositions (d) to (g) were prepared by dissolving 1 part by weight of toluenesulfonylated imidazoles at room temperature, adding 100 parts by weight of Epicoat 828 (trade name of Yuka Shell Co., Ltd.), and performing defoaming mixing. 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. A good cured product was obtained by curing (d) to (g) at 120 ° C. for 1.5 to 2 hours.

[0025]

[Table 4]

Comparative Example 1 A mixture of 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.) was added to 1-cyanoethyl-2-ethyl-4-methylimidazole ( 1 part by weight of Curezol 2E4MZ-CN, trade name of Shikoku Kasei Co., Ltd. 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. The initial viscosity was 10 poise at 25 ° C., and it was gelated 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 Epicoat 828 (trade name of Yuka Shell Co., Ltd.) 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 it was gelated after standing at 25 ° C. for 2 days.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Takeuchi 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Ajinomoto Co., Inc. Central Research Laboratory

Claims (2)

[Claims] 1. 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 obtained by sulfonylating the nitrogen atom at the 1-position of imidazoles, The mixing ratio of (1) and (2) is (acid anhydride equivalent number) / (epoxy equivalent number) ratio of 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. An epoxy resin cured product obtained by heating the liquid acid anhydride-based one-component epoxy resin composition according to claim 1.