JPS61218622A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:The titled composition which provides a cured material having improved mechanical characteristics and crack resistance, and has improved fluidity, comprising epoxy sin, a curing agent and a mixture of alumina particles and alumina fibers in a specific ratio. CONSTITUTION:The aimed composition comprising (A) 100pts.wt. epoxy resin, (B) 8-120pts.wt. curing agent (e.g., phthalic anhydride, etc.), and (C) 100-500pts. wt., preferably 200-400pts.wt. mixture of alumina particles [preferably compris ing <20wt% alumina particles having >=30mu particle diameter and >=50wt% alumina particles having >=15mu particle diameter] and alumina fibers (preferably having 2-15mu diameter and 2-500mu length).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an epoxy resin composition, and more particularly,
The present invention relates to an epoxy resin composition having good fluidity and comprising an epoxy resin, a curing agent, and alumina particles and alumina fibers.

[Technical background of the invention and its problems]

Mixing various curing agents and fillers with epoxy resin,
Cured products obtained by heating and curing are widely used as insulators for electrical equipment. This cured epoxy resin is required to have excellent physical and chemical properties such as resistance to sulfur hexafluoride and decomposition gases generated, mechanical properties, and crack resistance.

Conventionally, inorganic fibers such as glass fibers have been used as fillers for the purpose of improving the physical and chemical properties of cured epoxy resin products. However, in general, inorganic powders such as alumina are used as fillers in epoxy resins for various purposes, but when fibrous fillers are used for reinforcement, the viscosity of the composition increases significantly. However, since the fluidity is poor, effective casting of the epoxy resin composition has been difficult.

[Purpose of the invention]

The object of the present invention is to provide an epoxy resin composition that has good fluidity and good casting workability.

[Summary of the invention]

The present invention relates to an epoxy resin composition comprising an epoxy resin, a curing agent, and alumina particles having a specific particle size and alumina fibers having a specific diameter and length.

The epoxy resin used in the present invention may be of any type as long as it is generally known as an epoxy resin. Specific examples of this resin include bisphenol A diglycidyl ether and its dimer, dimer, epoxy resin obtained from novolac type phenol resin and epichlorohydrin, and epoxy resin obtained from polyhydric alcohol or polyalkylene oxide and epichlorohydrin. resin,
Examples include epoxy resins containing cyclohexene oxide groups.

The curing agent used in the present invention may be any known curing agent for epoxy resins. Specific examples of this curing agent include 7-talic anhydride, hexahydroheptalic anhydride, tetrahydrophthalic anhydride,
Acid anhydrides such as methyl-hexahydro-7-talic anhydride, methyl-tetrahydro-7-talic anhydride, methyl-Nadic anhydride, dodecenyl succinic anhydride, pyromellitic anhydride; triethylenetetramine, meta-phenylenediamine, tris(dimethylaminomethyl) ) Amines such as phenol;
Examples include dicyandiamide; boron trisulfide-amine complex; imidazole, etc., and one type or a mixture of two or more types selected from the group consisting of these can be used.

The alumina particles used in the present invention have a particle size of 30βm or more, which accounts for less than 20% by weight of the total alumina particles, and 1
Particles having a particle size distribution of 50% by weight or more are particles having a diameter of 5 μm or less. If the particle size distribution is outside the above range, when used in combination with the alumina fibers according to the present invention, either a very large increase in viscosity will result or there will be little improvement in mechanical properties.

The alumina fiber used in the present invention has a diameter of 2 to 15 μm.
The fibers have a length of 2 to 500 μm.

If the diameter and length of the fibers are outside the above ranges, the fibers will have a high viscosity and will be unsuitable for casting operations. Such alumina fibers include Safil (manufactured by IC Corporation), Nextel (manufactured by 3M Corporation), MAF (manufactured by Mitsubishi Kasei Corporation), and Fibermax (manufactured by Toshiba Mono7 Lux Co., Ltd.).
For example, ceramic fibers such as Alsene (manufactured by Denki Kagaku Kogyo Co., Ltd.) may be pulverized with a ball mill, and then classified to use those having a desired length. (a) Epoxy resin and φ)
The mixing ratio of the curing agent is 8 to 200 parts by weight per 100 parts by weight of the epoxy resin. The blending amounts of (C-1) alumina particles and (C-2) alumina fibers vary depending on the use or required properties of the composition, but are usually 100 to 500 parts by weight per 100 parts by weight of the epoxy resin as a mixture of the components.
Parts by weight are used, preferably from 200 to 400 parts by weight. If it is less than 100 parts by weight, the alumina particles and alumina fibers will settle and will not be uniformly dispersed, and if it is more than 500 parts by weight, the viscosity will be extremely high and filling will be difficult.

The blending ratio of alumina particles and alumina fibers is appropriately selected depending on the particle size distribution of the alumina particles used, the diameter and length of the alumina fibers, and the fluidity and required properties of the cured product. -1) + (C-21 weight ratio is within the range of 1 to 0.8, preferably 0.2 to 0.7. If it is less than 0.1, the effect of improving the crack resistance of the cured product is weak. If the value exceeds 0.8, the viscosity of the composition becomes too high and the casting operation becomes difficult.

The epoxy resin composition of the present invention may contain alumina particles of commonly used particle sizes, large sulfur heptadide decomposition gas-resistant magnesium, calcium, barium, etc., as necessary, within a range that does not impair the effects of the present invention. , aluminum heptadide, sulfate, carbonate, dolomite powder, titanium oxide powder, as well as organic and inorganic colorants.

Additives such as surface modifiers such as silane cagulin agents, curing accelerators such as imidal-based, tertiary amine-based, and metal complex-based agents may be appropriately blended.

The method for producing the epoxy resin composition of the present invention is not particularly limited, and each component may be put into a mixer such as an all-purpose mixer and mixed and stirred uniformly.

The epoxy resin composition of the present invention is used as a raw material for producing various insulators for electrical equipment, particularly solid insulators for electrical equipment insulated with sulfur hexa7tide.

〔Effect of the invention〕

The epoxy resin composition of the present invention has good fluidity, which facilitates the casting operation, and allows for the inclusion of a larger amount of filler than in conventional products, thereby reducing manufacturing costs.

[Examples and test examples of the invention]

Example 1 Each component shown in Table 2 was put into a universal mixer (Sanei Seisakusho Co., Ltd.) and mixed and stirred to obtain Composition 380F of the present invention (Product 1 of the present invention).

Examples 2 and 3 Each component shown in Table 2 was treated in the same manner as in Example 1 to obtain composition 3802 of the present invention (present invention products 2 and 3).

Test Example Each component shown in Table 2 was treated in the same manner as in Example 1, and a comparative product 1.
3802 each of 2 and 3 were obtained.

Inventive products 1.2 and 3 and comparative products 1.2 and 3 were used as raw materials, and after thorough mixing and degassing, the mixture was vacuum cast into a predetermined mold, heated to 115°C for 10 hours, and further heated to 130°C for 15 hours. After heating for a period of time, cured products 4.5 and 6 of the present invention and cured products 4, 5 and 6 of comparative products were obtained.

Furthermore, the present invention products 1.2 and 3 and the comparative product 1.2,
and 3 were used to test the flowability.

Fluidity is determined by the viscosity when inventive products 1, 2, and 3 and comparative products 1.2 and 3 are poured into a predetermined mold using their own weight after degassing, and the workability when vacuum degassing is performed after casting. was determined by visual inspection. The mark ◎ indicates that the viscosity is low and defoaming after casting is easy, the mark Δ indicates that casting is possible but vacuum defoaming is not possible, and the mark X indicates that casting is impossible.

The cured products 4, 5 and 6 of the invention and the comparative cured products 4, 5 and 6t were used to test mechanical properties and crack resistance. Mechanical properties are determined by JIS K as bending strength.
-6911.

Crack resistance was determined by rapidly heating and rapidly cooling a disc-shaped cured product test piece with an oliphant washer embedded in it with a thickness of 0.64α, and examining whether or not cracks occurred in the cured product layer. was evaluated using the Oliphant washer test method. That is, the cured product was subjected to the cooling and heating cycles shown in Table 1, and the arithmetic mean value of the cycle numbers at which cracks occurred in the test piece was shown as the crack resistance index. This indicates that a cured product with a large crack resistance index has excellent crack resistance (thermal shock resistance).

[Results of the invention]

As is clear from the results shown in Table 2, the product of the present invention was superior to the comparative product in fluidity.

Further, as is clear from the results shown in Table 3, the cured products of the present invention were superior to the cured products of the comparative product in terms of mechanical properties and crack resistance.

Table 1 (Note) High temperature side (25℃): Hold the test piece for 30 minutes in a hot air circulation constant temperature bath maintained at 25 to 30℃.

Claims (1)

[Claims] 1. (a) 100 parts by weight of epoxy resin, (b) curing agent 8
-120 parts by weight and 100-500 parts by weight of a mixture of alumina particles and alumina fibers. 2. The alumina particles contain less than 20% by weight of the total alumina particles having a particle size of 30 μm or more, and 50% by weight or more of the alumina particles having a particle size of 15 μm or more, and the alumina fibers have a diameter of 2 to 15 μm and a length of The epoxy resin composition according to claim 1, which has a diameter of 2 to 500 μm. 3. The epoxy resin composition according to claim 1, wherein the blending ratio of alumina particles to the entire alumina particle and alumina fiber mixture is 0.1 to 0.8 by weight.