JPH0925394A - Heat-resistant thremosetting resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack thermosetting resin composition excellent in heat resistance, shelf stability, workability, etc. SOLUTION: This composition contains as the essential components N,N'-(4,4'- diphenylmethane)bismaleimide, 2,2'-bis[4-(4-maleimidephenoxy)phenyl]propane, an epoxy resin that is liquid at ordinary temperature, a curing agent comprising an acid anhydride that is liquid at ordinary temperature, a polymerization initiator comprising an organic peroxide, and a latent cure accelerator.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an insulating material for electric equipment,
In particular, the present invention relates to a one-component heat-resistant thermosetting resin composition that is most suitable for impregnation and casting of rotating machines, transformers, etc. and has excellent heat resistance and storage stability.

[0002]

2. Description of the Related Art In recent years, there has been an increasing need for miniaturization and weight reduction of electric equipment, and the operating temperature of the electric equipment tends to rise accordingly, so that impregnation and injection of electric equipment used in rotating machines, transformers, etc. Heat resistance is also required for the mold insulating material. BACKGROUND ART Conventionally, as an insulating material for impregnation and casting of electric equipment insulation having heat resistance, a resin composition represented by a system composed of an epoxy resin and an acid anhydride curing agent is optimal and widely used. There is.

However, this resin composition is generally limited to the heat-resistant class F class, and it is difficult to use it in electric equipment which requires heat resistance higher than the H-class class. Therefore, there has been proposed a resin composition in which an epoxy resin, an acid anhydride curing agent and a bismaleimide compound are blended to improve heat resistance. N, N 'is the most widely used compound as the bismaleimide compound used here.
-(4,4'-diphenylmethane) bismaleimide may be mentioned.

[0004]

However, in order to improve the heat resistance of these resin compositions, N, N'-
Despite the need to increase the amount of (4,4'-diphenylmethane) bismaleimide compounded, N, N '-(4,4'
-Diphenylmethane) bismaleimide has poor solubility in epoxy resins and the like, so if the compounding amount is increased,
The storage stability of the composition becomes extremely poor, and a serious problem occurs that crystals of N, N '-(4,4'-diphenylmethane) bismaleimide precipitate during storage or during work, making it unusable. .

Further, in order to prevent crystal precipitation, N, N '-(4,4'-diphenylmethane) bismaleimide is dissolved by heating in an epoxy resin, and a part of the maleimide is dissolved at a relatively high temperature. Although a means of using after a polymerization reaction has been proposed, the polymerization reaction requires a relatively long time and, at the same time, it is difficult to control the reaction, so that the cost tends to increase. Further, in such a method, an increase in the viscosity of the obtained resin composition is unavoidable, and it is necessary to work at a high temperature in order to use it for applications requiring low viscosity such as impregnation and casting. Pot life tends to be a problem. Therefore, in these resin compositions, N, N '-(4,4'-
The present situation is to obtain and use a resin composition having good storage stability even if the heat resistance is sacrificed to some extent by reducing the compounding amount of diphenylmethane) bismaleimide.

[0006]

The present invention has been made to solve the above-mentioned problems, and is a one-liquid type excellent in heat resistance and storage stability suitable for electrical insulation of rotating machines, transformers and the like. It is intended to provide a resin composition, and as described in detail below, by optimally combining two kinds of bismaleimide compounds, the precipitation of the bismaleimide component is suppressed, and the one-liquid type excellent in heat resistance is provided. The inventors have found that a heat-resistant thermosetting resin composition can be obtained, and completed the present invention.

That is, the present invention provides: (A) N, N '-(4,4'-diphenylmethane) bismaleimide (B) 2,2'-bis [4- (4-maleimidophenoxy)
Phenyl] propane (C) Epoxy resin that is liquid at room temperature (D) Acid anhydride that is liquid at room temperature (E) Organic peroxide polymerization initiator (F) Latent curing accelerator (A) to (B) are essential It is a heat-resistant thermosetting resin composition characterized by comprising as a component.

The component (A) used in the present invention is N, N '-(4,4'
-Diphenylmethane) bismaleimide, which is represented by Chemical Formula 1, and component (B) is 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane, which is represented by the general formula: Chemical Formula 2 .

[0009]

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In these components (A) and (B) exhibiting heat resistance, the total amount of [(A) + (B)] should be 20 to 40% by weight based on the total resin composition. It is desirable to mix them. If the blending amount is 20% by weight or less, the desired heat resistance cannot be obtained, and if it is 40% by weight or more, precipitation of the bismaleimide component, increase in viscosity, brittleness of the cured product, etc. occur, and it is used for impregnation and casting. Becomes less practical.

On the other hand, the component (A) N, N '-(4,4'-diphenylmethane) bismaleimide and the component (B) 2,2'-bis [4
It is desirable to select a compounding ratio between-(4-maleimidophenoxy) phenyl] propane such that the ratio of [(A) / [(A) + (B)]] is 30 to 70%.
If this ratio is 30% or less, it becomes difficult to achieve low viscosity. On the other hand, when the proportion of the component (A) is 70% or more, the component (A) is precipitated during storage and storage stability is significantly deteriorated.

The component (C) used in the present invention is
Any epoxy resin which is liquid at room temperature and which contains two or more epoxy groups in one molecule can be used without particular limitation, but a resin that can lower the viscosity and maintain heat resistance is desirable. Specific examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin and the like. These resins may be used alone or in combination of two or more.

Examples of the component (D) acid anhydride which is liquid at room temperature used in the present invention include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methylhymic acid anhydride. Are used alone or in combination of two or more.

The mixing ratio of these acid anhydrides is 0.7 per equivalent of the epoxy group of the component (C) epoxy resin.
It is desirable to mix up to 1.2 equivalents. If the content exceeds this range, the reaction between the epoxy group and the acid anhydride group is not sufficiently carried out, which adversely affects the physical properties of the cured product.

The organic peroxide polymerization initiator of component (E) is added in a trace amount for the purpose of improving the curing reactivity of the resin composition, and specifically, methyl isobutyl ketone peroxide, lauroyl. Although peroxide, benzoyl peroxide, tertiary butyl peroxide, dicumyl peroxide, etc. can be mentioned, it is necessary to select a compound that does not decompose at the working temperature. These organic peroxide polymerization initiators are added in an amount of 0.01 to 2% by weight based on the total amount of the components [(A) + (B)].

The latent curing accelerator of the component (F) is specifically an amine adduct type compound, a compound obtained by encapsulating fine powder of an imidazole compound, acetylacetone chromium, acetylacetone zinc, acetylacetone cobalt or the like. Acetylacetone metal salt or the like is used. These latent curing accelerators are components [(A)
+ (B) + (C)] in the range of 0.01 to 10% by weight.

The resin composition of the present invention can be obtained by mixing the above components. Specifically, the component (C), which is a liquid epoxy resin at room temperature, is heated to 120 to 160 ° C. (A) and component (B) are added while stirring to dissolve,
After cooling to 70 ° C, (D) a liquid acid anhydride at room temperature,
The desired resin composition can be easily obtained by adding the component (E) organic peroxide polymerization initiator and the component (F) latent curing accelerator.

It is also possible to add a filler, a flame retardant, a reinforcing fiber and the like to the obtained resin composition within a range that does not impair the original purpose, to obtain a composite material.

The resin composition thus obtained according to the present invention is heated at a temperature of 150 to 250 ° C. for 1 to 24 hours,
A cured product having excellent heat resistance can be easily obtained.

[0020]

The one-component heat-resistant thermosetting resin composition of the present invention is
N, N '-(4,4'-diphenylmethane) bismaleimide, which is easy to precipitate, and 2,2'-bis [4- (4
By using both compounds of -maleimidophenoxy) phenyl] propane, a stable one-component heat-resistant thermosetting resin composition having excellent storage stability and workability and having heat resistance of the cured product is obtained.

[0021]

Next, the present invention will be described with reference to examples.
The present invention is not limited by these examples.

Example 1 60 parts by weight of a bisphenol F type epoxy resin was placed in a flask and heated to 130 ° C., and 20 parts by weight of N, N ′-(4,4′-diphenylmethane) bismaleimide and 2,2′-bis were added. [4-
(4-Maleimidophenoxy) phenyl] propane 20
After gradually adding 20 parts by weight of the mixture and heating at the same temperature for 20 minutes to form a uniform liquid, it was cooled to 70 ° C. and 53 parts by weight of methyl tetrahydrophthalic anhydride, 0.3 parts by weight of dicumyl peroxide, HX3741 (latent) 0.2 part by weight of a heat-curing accelerator, manufactured by Asahi Kasei Co., Ltd. was added to obtain a brown-colored transparent one-component heat-resistant thermosetting resin composition.

Examples 2 to 3 In the same manner as in Example 1 except that the composition shown in Table 1 was used, uniform one-component heat-resistant thermosetting resin compositions were obtained.

Comparative Example 1 Similar to Example 1, bisphenol F type epoxy resin
Add 60 parts by weight to a flask and heat to 130 ° C, then add N, N '-(4,
4'-diphenylmethane) bismaleimide 40 parts by weight was gradually added and heated at the same temperature for 20 minutes to form a uniform liquid,
After cooling to 70 ° C, 53 parts by weight of methyl tetrahydrophthalic anhydride, 0.3 parts by weight of dicumyl peroxide, HX3741
(A latent curing accelerator microcapsulated with an imidazole compound, manufactured by Asahi Kasei Corporation) 0.2 part by weight was added to obtain a one-component heat-resistant thermosetting resin composition, but bismaleimide was obtained during cooling. Was deposited, and a stable heat-resistant thermosetting resin composition could not be obtained.

Comparative Example 2 70 parts by weight of a bisphenol F type epoxy resin was placed in a flask and heated to 170 ° C., and 30 parts by weight of N, N ′-(4,4′-diphenylmethane) bismaleimide was gradually added thereto. After heating at temperature for 3 hours, a part of bismaleimide is reacted to form a uniform liquid, then cooled to 70 ° C and 63 parts by weight of methyltetrahydrophthalic anhydride, dicumyl peroxide.
0.3 parts by weight and 0.2 parts by weight of HX3741 were added to obtain a one-component heat-resistant thermosetting resin composition.

The viscosity and storage stability of the resin compositions obtained in Examples 1 to 3 and Comparative Example 2 were measured. Further, the heat distortion temperature and the heat loss of the cured product obtained by curing the obtained resin composition at 180 ° C. for 4 hours and further at 200 ° C. for 8 hours were measured, and the results are shown in Table 1. In each case, excellent characteristics were exhibited, and the effects of the present invention could be exhibited.

[0027]

[Table 1]

[0028]

As is clear from the above description and Table 1, the resin composition of the present invention is a one-component heat-resistant thermosetting resin composition excellent in heat resistance, storage stability, workability and the like. And is suitable as a resin composition for impregnating and casting a class H rotating machine and transformer.

Claims (1)

[Claims] 1. (A) N, N '-(4,4'-diphenylmethane) bismaleimide (B) 2,2'-bis [4- (4-maleimidophenoxy)
Phenyl] propane (C) Epoxy resin that is liquid at room temperature (D) Acid anhydride curing agent that is liquid at room temperature (E) Organic peroxide polymerization initiator (F) Latent curing accelerator And a heat-resistant thermosetting resin composition.