JPS61276849A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:The titled composition useful for insulating treatment for various high-tension coils, having low viscosity and improved impregnating properties, obtained by blending an epoxy resin with a liquid bromine compound, antimony trioxide, inorganic powder and a curing agent of a liquid acid anhydride type in a specific ratio. CONSTITUTION:(A) 100pts.wt. epoxy resin such as bisphenol A diglycidyl ether, etc. is blended with (B) 15-40pts.wt. low-viscosity, liquid bromine compound having about 50wt% bromine content, such as dibromophenylglycidyl ether, dibromocresylglycidyl ether, etc., (C) 5-20pts.wt. antimony trioxide, (D) 100-250 pts.wt. inorganic powder such as silica, hydrated alumina, etc. (one having improved electrical insulating properties), (E) a curing agent of a liquid acid anhydride type (e.g., methyltetrahydrophthalic anhydride, etc.), and a small amount of a reaction promoter (preferably imidazole compound).

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a flame-retardant resin composition for impregnation or injection used for insulation treatment of various high voltage coils such as flyback transformers for television receivers. .

[Technical background of the invention and its problems] Various high voltage coils such as flyback transformers are manufactured by insulating them with epoxy resin compositions. These epoxy resin compositions are required not only to have insulation properties but also to have crack resistance and flame retardancy. Recently, with the miniaturization of coils and the shortening of process time (mainly resin curing time), there has been a demand for resin compositions with lower viscosity and better impregnation properties.

To make epoxy resin compositions flame retardant, a method of adding a solid or powdered halide and antimony trioxide in combination, or adding red phosphorus is used.

However, in order to satisfy the UL standard with these methods,
A large amount of flame retardant is required, and as a result, the flame retardant resin composition has a high viscosity, impregnating properties are reduced, and various properties and workability are poor.

[Object of the Invention] The object of the present invention was to solve the conventional drawbacks, and to provide a flame-retardant resin composition with low viscosity and excellent impregnation properties, which is suitable for downsizing coils and shortening processes. This is what I am trying to do.

[Summary of the Invention] As a result of intensive research aimed at achieving the above object, the present inventors have developed a flame retardant that replaces the conventional solid or powder flame retardant.
The inventors have discovered that a flame-retardant resin composition with low viscosity and excellent impregnability can be obtained by using a specified liquid bromine compound, and have completed the present invention. That is, in the present invention, 15 to 40 parts by weight per 100 parts by weight of epoxy resin.
Containing parts by weight of a liquid bromine compound, 5 to 20 parts by weight of antimony trioxide, and 100 to 250 parts by weight of an inorganic powder,
This is a flame-retardant resin composition characterized by containing a liquid acid anhydride curing agent as a curing agent.

Epoxy resins used in the present invention include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, diglycidyl ether of polycarboxylic acids such as phthalic acid, terephthalic acid, tetrahydrophthalic acid, and hexahydrophthalic acid, and epoxy resins of cyclohexene derivatives. Examples include polyepoxides obtained by chemical reaction, and these can be used alone or in combination. Moreover, a liquid monoepoxy resin can be added as necessary.

The liquid bromine compound used in the present invention exhibits a liquid state at 23°C, has a brome content of about 50 parts, and has a low viscosity. Specific compounds include, for example, dibromophenyl glycidyl ether, dibromocresyl glycidyl ether, etc., and these may be used alone or in combination of two or more. The blending ratio of the liquid bromine compound is 15 to 40 parts by weight per 100 parts by weight of the epoxy resin.
A heavy portion is preferred. If the amount is less than 15 parts by weight, it will not have much effect on flame retardancy, and if it exceeds 40 parts by weight, electrical properties will deteriorate, which is not preferable.

As the antimony trioxide used in the present invention, commercially available products are widely used. The blending ratio of antimony trioxide is preferably 5 to 20 parts by weight based on 100 parts by weight of the epoxy resin. If the amount is less than 5 parts,
The flame retardant effect is poor, and antimony trioxide separates from the resin, which is undesirable.

If it exceeds 20 parts by weight, the viscosity becomes high, resulting in poor impregnation and workability, which is not preferred.

Inorganic powders used in the present invention include silica, talc,
Examples include hydrated alumina and calcium carbonate, which may be used alone or in combination.

These inorganic powders preferably have excellent electrical insulation properties. The blending ratio of inorganic powder is 100% epoxy resin
It is desirable that the amount is 100 to 250 parts by weight. If the amount of the blended layer is less than 100 parts by weight, crack resistance and heat dissipation properties will be poor, and the cost will be high, which is not preferable. If it exceeds 250 parts by weight, the viscosity becomes high and workability and impregnating properties are deteriorated, which is not preferable.

Examples of the liquid acid anhydride curing agent used in the present invention include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and the like, which may be used alone or in combination of two or more. When an acid anhydride curing agent is used, a small amount of an imidazole compound or a tertiary amine compound (eg, trisdimethylaminomethylphenol, benzyldimethylamine, etc.) is used as a reaction accelerator. Particularly preferred is an imidazole compound, and when this is used, the stability of the resin composition is good, and an epoxy resin composition with excellent heat resistance can be obtained even if the curing III is low.

The flame-retardant resin composition according to the present invention contains an epoxy resin, a liquid bromine compound, antimony trioxide, an inorganic powder, and a liquid acid anhydride curing agent, and has a predetermined blending ratio. If the blending ratio falls outside of this range, flame retardancy, workability, impregnability, electrical properties, crack resistance, and heat dissipation properties will not be obtained, and the cost will be adversely affected, which is undesirable. However, if necessary, other additives such as diluents, modifiers, colorants, antifoaming agents, etc. may be added without impairing the characteristics of the present invention.
The flame-retardant resin composition thus obtained is used for insulation treatment of various high voltage coils and the like.

[Examples of the Invention] Next, the present invention will be explained by examples, but the present invention is not limited to these examples.

In the following Examples and Comparative Examples, "part" means "heaviest part".

Example 1 As shown in Table 1, 90 parts of bisphenol A glycidyl ether, 10 parts of monoepoxide epoxy resin,
15 parts of dibromocresyl glycidyl ether, 5 parts of antimony trioxide, 80 parts of silica, 100 parts of hydrated alumina,
and 1 part of a silane coupling agent were mixed, and then 80 parts of methyltetrahydrophthalic anhydride as a curing agent and 1 part of benzyldimethylamine as a reaction accelerator were added and mixed to obtain a flame-retardant resin composition. The obtained composition was tested for viscosity, and the heat-cured product was tested for flame retardancy, impregnability (impregnation rate into the impregnated space), and dielectric constant.

The results are shown in Table 1, and the effects of the present invention were recognized.

Examples 2 to 3 Flame-retardant resin compositions were obtained in the same manner as in Example 1 using the compositions shown in Table 1. Various tests were also conducted in the same manner as in Example 1, and the results are shown in Table 1.
As shown in the same table, the effects of the present invention were observed.

Comparative Examples 1-2 Flame-retardant resin compositions were obtained in the same manner as in Example 1 using the compositions shown in Table 1. Various tests were conducted on the obtained composition in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 *1: Yojin Kasei Flame Retardant Table 1 (continued) *2: Evaluation using actual coils [Effects of the invention] As is clear from the above explanation and Table 1, the flame retardant resin composition of the present invention The product has low viscosity and excellent impregnating properties, and is suitable as a resin composition for impregnating and injecting various high voltage coils where these characteristics are important.

Claims (1)

[Claims] 1. Contains 15 to 40 parts by weight of a liquid bromine compound, 5 to 20 parts by weight of antimony trioxide, and 100 to 250 parts by weight of inorganic powder based on 100 parts by weight of the epoxy resin, and contains a liquid acid anhydride-based hardening agent as a hardening agent. A flame-retardant resin composition comprising: