JPH0578444A - Liquid acid anhydride-based one-pack type epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject resin having excellent storage stability, curing properties, mechanical-thermal characteristics after curing and chemical proper ties, comprising an epoxy resin, an acid anhydride and a reactional product of an isocyanate group-containing compound and a secondary amine as essential components. CONSTITUTION:(A) 100 pts.wt. epoxy resin containing plural epoxy groups in one molecule is blended with (B) an acid anhydride and (C) 0.1-10 pts.wt. reactional product of an isocyanate group-containing compound and a secondary amine in a blending ratio (number of equivalents of acid anhydride)/(number of equivalents of epoxy resin) of the component A/B of 0.8-1.2 to give the objective completely uniform composition.

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. Because of its excellent properties, it is widely used for encapsulating capacitors, impregnating coils for large motors, generators, etc., encapsulating transformers, magnetic heads and the like.

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 (Japanese Patent Laid-Open No. 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-61-15123).
0) etc. are used. When such a curing accelerator is used, the curability is greatly 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.

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 gap, leaving insufficient cured portions, resulting in deterioration of various physical properties.

Therefore, it has been earnestly desired to develop a liquid acid anhydride-based one-pack apoxy resin composition having 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 to solve the above-mentioned problems, the present inventors have found that one or more molecules in one molecule of a curing accelerator for a liquid acid anhydride-based one-component epoxy resin composition are used. It was found that the use of a reaction product of a compound having an isocyanato group with a secondary amine improves storage stability and curability, and that the cured product after curing has excellent properties. 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 having one or more isocyanate groups in one molecule. The reaction product of a primary amine is an essential component, and the mixing ratio of (1) and (2) is such that (acid anhydride equivalent number) / (epoxy resin equivalent number) is 0.8 to
1.2, and the addition amount of (3) is 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin, and a liquid acid anhydride-based one-component epoxy resin composition and the same The present invention relates to an epoxy resin cured product obtained by heating.

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,
Polyvalent phenols such as catechol and resorcinol, or polyvalent alcohols such as glycerin and polyethylene glycol.
Poly (glycidyl ether) obtained by reacting chlorophenol 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 an epoxy Examples thereof include, but are not limited to, modified phenol novolac resin, epoxidized cresol novolac resin, epoxidized polyolefin, cycloaliphatic epoxy resin, and other urethane-modified 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 bistrimellitate, glyceryl ortristrimerate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydroanhydride. Phthalic acid, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexenedicarboxylic acid Examples thereof include, but are not limited to, acid anhydrides, alkylstyrene-maleic anhydride copolymers, chlorendic acid anhydrides, tetrabromophthalic anhydride, and polyazelaic acid anhydrides.

The reaction product of the compound having one or more isocyanate groups in one molecule and the secondary amine used in the present invention will be described below. A compound used in the present invention having one or more isocyanate groups in one molecule and 2
The reaction product of the primary amine is obtained by mixing the isocyanate group-containing compound and the secondary amine in an organic solvent such as chloroform or toluene, or in the absence of a solvent, or in a mixture of the epoxy resin and the isocyanate group-containing compound. It can also be prepared by adding a secondary amine.

The compound having one or more isocyanate groups in one molecule is not particularly limited and is shown below as a typical example. For example, n-butyl isocyanate
, Isopropylisocyanate, 2-chloroethylisocyanate, phenylisocyanate, p-chlorophenylisocyanate, benzylisocyanate, hexamethylenediisocyanate, 2-ethylphenylisocyanate , 2,6-dimethylphenyl isocyanate, 2,4-toluene diisocyanate, toluylene diisocyanate, 2,6-toluene diisocyanate,
1,5-naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, tolidine diisocyanate, isophorone diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate , 1,
Examples thereof include, but are not limited to, 3,6-hexamethylene triisocyanate and bicycloheptane triisocyanate.

The secondary amine is not particularly limited and is shown below as a typical example. For example, dimethylamine, diethylamine, di-n-propylamine, di-
n-butylamine, di-n-hexylamine, di-n-
Examples thereof include, but are not limited to, octylamine, morpholine, piperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, piperazine, pyrrolidine, and N-methylbenzylamine.

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. The addition amount of the reaction product of the isocyanate group-containing compound and the secondary amine varies depending on the kind, but is in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin.

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

[0015]

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 be used to 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. Further, 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 saving resources and protecting the environment.

[0016]

The present invention will be described in detail below with reference to examples. In the following examples, stability was evaluated by the viscosity after 1 to 3 months, and curability was evaluated by gel time at 120 or 150 ° C. The viscosity was measured according to JIS K 6833, and the gelling time was measured with a Yasuda gel timer. The glass transition point of the cured product was measured by a TMA penetration method using a thermomechanical analyzer (TMA, manufactured by Rigaku Denki Co., Ltd.) for a sample cured at a predetermined temperature for a certain time. The measurement conditions are a temperature rising rate of 10 ° C / min and a load of 1
0 g, needle diameter 1 mm.

Example 1 Toluylene diisocyanate 10.1 was placed in a three-necked flask.
A chloroform solution of 15.0 g of di-n-butylamine was added dropwise from a dropping funnel while adding g of chloroform solution and stirring at room temperature. After completion of dropping, the mixture was further stirred for 5 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (A). Methylhexahydrophthalic anhydride, HN-5500 (Hitachi Chemical Co., Ltd. trade name, acid anhydride equivalent 166) To 85 parts by weight of (A), 1.0 part by weight of (A) was added and dissolved by stirring at room temperature. The epoxy resin composition (a) was obtained by mixing 100 parts by weight of A-type epoxy resin, Epicort 828 (trade name of Yuka Shell Co., epoxy equivalent 190).
(A) was completely liquid and cured at 120 ° C. in 150 minutes. The initial viscosity was 6.8 poise at 25 ° C, and the viscosity after standing at 25 ° C for 3 months was 3 ° C at 25 ° C.
It was 3.4 poise.

Example 2 A 1 L three-necked flask was charged with 5.0 of phenyl isocyanate.
g of chloroform solution was added, and while stirring at room temperature, a chloroform solution of 5.4 g of di-n-butylamine was added dropwise from the dropping funnel. After completion of dropping, the mixture was further stirred for 3 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (B). To 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), 1.0 part by weight of (B) was added and dissolved by stirring at room temperature.
Epoxy resin composition (b) was obtained by mixing with 100 parts by weight of 28 (trade name of Yuka Shell Co., Ltd.). (B) is completely liquid and has a gel time of 135 at 120 ° C.
Min, the gel time at 150 ° C. was 26 minutes. Also,
Initial viscosity is 6.4 poise at 25 ° C, 25 ° C
The viscosity after standing for 3 months at 25 ° C. was 34.2 poise. The glass transition point of the cured product of (b) after curing at 120 ° C. for 4 hours is 110 ° C., and the dielectric constant (25 ° C., 1
kHz) was 3.4, the dielectric loss tangent (25 ° C., 1 kHz) was 0.5%, and the water absorption rate after standing for 1 hour in boiling water was 0.3%.

Example 3 A 1 L three-necked flask was charged with hexamethylene diisocyanate.
9.8 g of chloroform solution was added, and 15.0 g of di-n-butylamine was added from a dropping funnel while stirring at room temperature.
Was added dropwise. After completion of dropping, the mixture was further stirred for 5 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (C). To 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), 1.0 parts by weight of (C) was added and dissolved by stirring at room temperature, and then 100 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.) Epoxy resin composition (c) was obtained by mixing with parts.
(C) was completely liquid and cured at 120 ° C. in 150 minutes. The initial viscosity was 7.0 poise at 25 ° C, and the viscosity after standing at 25 ° C for 3 months was 3 ° C at 25 ° C.
It was 0.2 poise.

Example 4 A 1 L three-necked flask was charged with 5.0 g of 2,6-dimethylphenylisocyanate in chloroform, and while stirring at room temperature, 4.4 g of di-n-butylamine was added from a dropping funnel. Was added dropwise. After finishing the dropping
It was stirred for another 5 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (D). HN-55
(D) was added to 85 parts by weight of 00 (Hitachi Chemical Co., Ltd. product name).
Epoxy resin composition (d) was obtained by adding 0 parts by weight and stirring at room temperature to dissolve and then mixing with 100 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.).
Got (D) was completely liquid and cured at 120 ° C. in 120 minutes. The initial viscosity is 5.4 poise at 25 ° C, and the viscosity after standing at 25 ° C for 1 month is 2
It was 28.2 poise at 5 ° C.

Example 5 A 2-liter three-necked flask was charged with 2-ethylphenylisocyanate.
A chloroform solution (2.3 g) was added, and a chloroform solution (2.0 g) of di-n-butylamine was added dropwise from a dropping funnel while stirring at room temperature. After completion of dropping, the mixture was further stirred for 3 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (E). To 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), 1.0 part by weight of (E) was added and dissolved by stirring at room temperature.
An epoxy resin composition (e) was obtained by mixing 100 parts by weight of G. 828 (trade name of Yuka Shell Co., Ltd.).
(E) was completely liquid and cured at 120 ° C. in 150 minutes. The initial viscosity was 7.8 poise at 25 ° C, and the viscosity after standing at 25 ° C for 2 months was 3 ° C at 25 ° C.
It was 0.8 poise.

Example 6 1.1 g of a chloroform solution of diethylamine was placed in a 1 L three-necked flask, and a solution of 2.5 g of 2-ethylphenyl isocyanate in chloroform was added dropwise from a dropping funnel while stirring under ice cooling. .. After completion of dropping, the mixture was further stirred for 3 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (F). To 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), 1.0 parts by weight of (F) was added and dissolved by stirring at room temperature.
An epoxy resin composition (f) was obtained by mixing with 100 parts by weight of 28 (trade name of Yuka Shell Co., Ltd.). (F) was completely liquid and cured at 120 ° C. in 150 minutes. The initial viscosity was 6.4 poise at 25 ° C, and the viscosity after standing at 25 ° C for 1 month was 24.8 poise at 25 ° C.

Example 7 A chloroform solution of 3.1 g of diethylamine was placed in a 1 L three-necked flask, and a solution of 5.0 g of phenylisocyanate in chloroform was added dropwise from the dropping funnel while stirring under ice cooling. After completion of dropping, the mixture was stirred for 5 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (G). HN-5500 (Hitachi Chemical Co., Ltd. product name) 8
An epoxy resin composition was prepared by adding 4.0 parts by weight of (G) to 5 parts by weight of the mixture, stirring the mixture at room temperature to dissolve it, and then mixing it with 100 parts by weight of Epicote 828 (trade name of Yuka Shell Co., Ltd.). (G) was obtained. (G) was completely liquid, and the gel time at 120 ° C. was 55 minutes. The initial viscosity was 9.0 poise at 25 ° C., which was 2
The viscosity after standing at 5 ° C for 1 month was 27.2 poise at 25 ° C.

Example 8 A 1 L three-necked flask was charged with p-chlorophenylisocyanate.
A chloroform solution (7.0 g) was added, and a chloroform solution (5.9 g) of di-n-butylamine was added dropwise from the dropping funnel while stirring at room temperature. After completion of dropping, the mixture was further stirred for 5 hours. After completion of the reaction, the solvent was distilled off and the residue was dried under reduced pressure to obtain a white solid (H). To 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.), 1.0 part by weight of (H) was added and dissolved by stirring at room temperature.
An epoxy resin composition (h) was obtained by mixing 100 parts by weight of G. 828 (trade name of Yuka Shell Co., Ltd.).
(H) was completely liquid and cured at 120 ° C. in 150 minutes. The initial viscosity was 6.4 poise at 25 ° C, and the viscosity after standing at 25 ° C for 3 months was 32.8 at 25 ° C.
It was a poise.

Example 9 20 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.) and 1.5 g of hexamethylene diisocyanate were mixed, and 2,6-dimethylmorpholine 1 was mixed with stirring under ice cooling. .0
g was added. To 20 parts by weight of this product, 80 parts by weight of Epicote 828 was added, and further mixed with 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.) to obtain an epoxy resin composition (i). (I) is completely liquid, 1
Cured in 150 minutes at 20 ° C. The initial viscosity was 7.5 poise at 25 ° C, and the viscosity after standing at 25 ° C for 1 month was 24.0 poise at 25 ° C.

Example 10 20 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.) and 1.5 g of hexamethylene diisocyanate were mixed, and 1.0 g of hexamethyleneimine was added while stirring under ice cooling. added. To 20 parts by weight of this product, 80 parts by weight of Epicote 828 was added, and further mixed with 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.) to obtain an epoxy resin composition (j). (J) is completely liquid,
Cured in 60 minutes at ° C. The initial viscosity is 25 ° C.
Was 6.8 poise, and the viscosity after standing at 25 ° C. for 1 month was 34.0 poise at 25 ° C.

Comparative Example 1 A mixture of 100 parts by weight of Epicort 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 U-CAT which is a DBU-phenol salt.
An epoxy resin composition (k) was obtained by adding 0.3 part by weight of SA-1 (trade name of San-Apro Co., Ltd.). (K) was completely liquid, and the gel time at 120 ° C. was 50 minutes. The initial viscosity was 8.0 poise at 25 ° C., the viscosity after standing for 1 week at 25 ° C. was 41.0 poise at 25 ° C., and gelation occurred after 2 weeks.

Comparative Example 2 2-Ethyl-4 of 2-ethylhexanoic acid was added to a mixture of 100 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.) and 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.).
1 part by weight of methyl imidazole salt was added to obtain an epoxy resin composition (1). (L) is completely liquid,
The gel time at 120 ° C. was 10 minutes. The initial viscosity is 12.5 poise at 25 ° C, and 1 at 25 ° C.
It had gelled after being left for a week.

Comparative Example 3 A tertiary amine having a phenolic hydroxyl group was added to a mixture of 100 parts by weight of Epicort 828 (trade name of Yuka Shell Co., Ltd.) and 85 parts by weight of HN-5500 (trade name of Hitachi Chemical Co., Ltd.). An epoxy resin composition (m) was obtained by adding 1 part by weight of certain DMP-30. (M) was completely liquid.
(M) 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. (1) An epoxy resin having two or more epoxy groups in one molecule, (2) an acid anhydride, (3) a compound having one or more isocyanate groups in one molecule, and a secondary. The reaction product of amine is an essential component, and the mixing ratio of (1) and (2) is (acid anhydride equivalent number) / (epoxy resin equivalent number) of 0.8 to 1.2, and (3) A liquid acid anhydride-based one-pack type epoxy resin composition, wherein the added amount is 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin. 2. An epoxy resin cured product obtained by heating the liquid acid anhydride-based one-component epoxy resin composition according to claim 1.