JPH1046007A - Epoxy resin composition and epoxy resin cast product for gas insulating instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition which can exhibit excellent resistance to corrosion, high voltage, heat and crack by formulating a powder of liquid crystal polymer fiber. SOLUTION: The epoxy resin composition is obtained by formulating a powder of liquid crystal polymer fiber. As a fiber powder, is used, for example, a pulverized powder of liquid crystal polyester, liquid crystal polyamide or the like. In addition to the fiber powder, an epoxy resin, a curing agent, a curing accelerator, an impact resistance enhancer and the like may be added to the objective composition. The epoxy resin is, for example, bisphenol epoxy resin, novolak type epoxy rein or the like. As a curing agent, are generally used an acid anhydride, for example, phthalic anhydride in many cases. As an impact resistance improving agent, is cited, for example, rubber particles having a double-layered structure comprising the core made of styrene-butadiene rubber or acrylic rubber and the shell made of polymethyl methacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an epoxy resin composition and an epoxy resin cast product for gas-insulated equipment. More specifically them if the present invention is a gas, for example sulfur hexafluoride gas (hereinafter, referred to as "SF ₆ gas") an epoxy resin composition for gas-insulated electric apparatus filled with and gas-insulated apparatus comprising it and Casting It relates to an epoxy resin casting.

[0002]

2. Description of the Related Art SF ₆ gas is widely used as a small measuring insulating material for electric equipment because of its excellent electric insulation and arc-extinguishing properties. Electrical equipment filled with SF ₆ gas includes circuit breakers, disconnectors, transformers, power cable terminal pushings, busbars, and the like. Since SF ₆ gas is a chemical substance, it may be chemically decomposed by arc discharge or corona discharge generated in electric equipment. The decomposition product generated by this chemical decomposition is a chemical substance containing sulfur and fluorine, and therefore has high chemical reactivity and corrosiveness.

[0003] corrosion resistance such SF other than _six gas material used in the SF ₆ gas insulated electrical apparatus is excellent in translation is required. Of course, excellent corrosion resistance is also required for epoxy resin cast products for gas insulation equipment.

[0004] It is generally known that the corrosion resistance of an epoxy resin casting is greatly affected by the filler to be incorporated. Conventionally, aluminum oxide (hereinafter, referred to as “alumina”) has been widely used as a corrosion-resistant filler for epoxy resin cast products.

[0005] On the other hand, recent electric equipment has been required to further improve performance.

[0006] The first demand for such performance improvement is an improvement in high voltage resistance.

As a method of improving the high voltage characteristics of an epoxy resin cast product for gas insulating equipment, it is effective to reduce the dielectric constant of the epoxy resin cast product. In other words, when an epoxy resin casting for a gas insulating device is molded using an epoxy resin having a large dielectric constant and in a shape such that local electric field concentration is likely to occur, the epoxy resin casting is subject to local electric field concentration. This is because it is known that dielectric breakdown occurs at a relatively low voltage. For these reasons, there is a strong demand for a low dielectric constant epoxy resin composition for gas-insulated equipment.

However, conventionally used epoxy resin compositions for gas-insulated equipment containing alumina are 40 to 7 epoxy resin compositions.
Since a large amount of alumina of 0% by weight is blended, it is difficult to lower the dielectric constant.

A second requirement for improved performance is improved heat resistance. That is, the operating temperature of an electric device is increased with the increase in the voltage, the capacity, and the miniaturization of the electric device, and heat resistance that can be used at such a high operating temperature is required.

[0010] The heat resistance of an epoxy resin cast product for gas insulation equipment is evaluated by the heat deformation temperature. This is because it is known that when an epoxy resin cast product for a gas insulating device is used at a temperature exceeding the heat deformation temperature, its electrical and mechanical properties are sharply reduced.

However, there is a concern that crack resistance is deteriorated in an epoxy resin cast product for gas insulated equipment having an increased heat distortion temperature because flexibility is inevitably reduced. That is, it is difficult to achieve both heat resistance and crack resistance of an epoxy resin cast product.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned drawbacks of the prior art, to provide excellent corrosion resistance and excellent high voltage resistance. An object of the present invention is to provide an epoxy resin composition capable of exhibiting characteristics, heat resistance, and crack resistance, and an epoxy resin cast product for a gas insulating device obtained by casting the same.

[0013]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an epoxy resin composition comprising a liquid crystal polymer fiber powder and an epoxy resin for a gas-insulated apparatus obtained by casting the same. Found in cast products.

In the present invention, the liquid crystal polymer fiber powder is a powder obtained by pulverizing high-strength and high-modulus fibers having a highly developed molecular orientation, such as liquid crystalline polyester and liquid crystalline polyamide. Examples of commercially available liquid crystal polymer fiber powders include Pet Run from Kuraray Co., Ltd. and Kevlar from Dupont Toray Kevlar.

The epoxy resin composition for gas-insulated equipment of the present invention contains, in addition to the liquid crystal polymer fiber powder, an epoxy resin, a curing agent, a curing accelerator, an impact-resistant reinforcing agent, a filler, a coloring agent, an antioxidant, and a surface. A treating agent or the like can be blended.

Here, as the epoxy resin, bisphenol epoxy resin, novolak type epoxy resin,
There are a cyclic aliphatic epoxy resin, a naphthalene epoxy resin and the like. In this case, these can be appropriately blended as needed.

As the curing agent, an acid anhydride-based curing agent is frequently used. Examples of such an acid anhydride-based curing agent include phthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylene. Hixahydrophthalic anhydride, trimellitic anhydride and the like. If necessary, two or more of these acid anhydride-based curing agents may be blended to form a paper sheet.

In the present invention, as the impact-resistant reinforcing agent, polymethyl methacrylate having a core portion composed of styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, acrylic rubber or the like, and a shell portion having good dispersibility in an epoxy resin composition, Poly (methyl methacrylate-styrene), poly (methyl methacrylate-glycidyl methacrylate)
The rubber particles have a two-layer structure and are composed of fine particles having a particle diameter of about 100 to 1,000 nm.

[0019]

Next, Examples and Comparative Examples of the epoxy resin composition of the present invention and an epoxy resin cast product for gas-insulated equipment will be described.

(Description of Compounding Agents) First, the compounding agents used in Examples and Comparative Examples will be described.

Epoxy Resin As the epoxy resin, Epicoat 828, a bisphenol-based liquid epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., was used.

Acid anhydride-based curing agent Araldite HT903, a tetrahydroanhydride-phthalic anhydride-based curing agent manufactured by Ciba-Geigy Japan, Ltd., was used as the acid anhydride-based curing agent.

Impact Strengthening Agent Paraloid EXL2655, a styrene-butadiene rubber-based core shell type rubber particle manufactured by Kureha Chemical Industry Co., Ltd., was used as the impact strengthening agent.

Liquid Crystal Polymer Fiber Powder A powder having an average particle size of 25 μm produced by pulverizing Petrun from Kuraray Co., Ltd. and Kevlar from Dupont Toray Kevlar Co., Ltd. was used.

(Blending of Epoxy Resin Composition for Gas Insulated Equipment) Next, various blending agents were blended according to Examples and Comparative Examples shown in Table 1.

[0026]

[Table 1]

(Production of Epoxy Resin Cast Products for Gas Insulated Equipment) Next, the epoxy resin compositions for gas insulated equipment of Examples and Comparative Examples shown in Table 1 were subjected to defoaming treatment at 100 ° C. under reduced pressure. And then inject it into the given mold, then
An epoxy resin casting for gas-insulated equipment was manufactured by primary curing at 0 ° C. for 20 hours and then secondary curing at 170 ° C. for 20 hours.

(Characteristics test) Characteristic tests were carried out on electrical properties, heat resistance properties, mechanical properties, resistance to SF ₆ gas partial decomposition gas, and crack resistance.

These characteristic tests were performed in accordance with the characteristic test method specified by JIS.

The SF ₆ gas used in the gas insulated equipment is decomposed by an arc or corona discharge generated in the equipment, and reacts with SF ₂ , SF ₄ , S ₂ F ₂ , SOF ₂ , SOF _4, etc. This produces strong decomposition products. For most product among these degradation products are SF _4, the case of SF _4,
When it comes into contact with water or water vapor, it undergoes a decomposition reaction such as SF ₄ + H ₂ O → SOF ₂ + 2HF SF ₂ + H ₂ O → SO ₂ + 2HF to generate highly corrosive hydrofluoric acid.

Therefore, there is a close correlation between the resistance of the insulating material to SF ₆ discharge decomposition gas and the resistance to hydrofluoric acid (HF), and the resistance to SF ₆ discharge decomposition gas can be predicted by an HF resistance test. Here, a special grade hydrofluoric acid having a concentration of 46% placed in a vat was placed on the bottom of a plastic desiccator in a room, and a test piece of 100 mmφ × 3 mmt was placed on a shelf having a hydrogen fluoride atmosphere inside the desiccator. After leaving it to stand for a period of time, the surface was wiped, dried in a fume hood for 24 hours, and then the dielectric constant, dielectric loss tangent, and volume resistivity were measured and compared with the initial values before the HF resistance test. The dielectric constant, dielectric tangent, and volume resistivity conform to JIS K6911, and the dielectric constant and dielectric tangent are determined by a Schering bridge.
The measurement was performed at 60 Hz and 1000 V, and the volume resistivity was measured at DC 500 V for one minute using a super insulation meter.

The crack resistance was determined by performing a heat cycle test shown in Table 2 on a test piece having a diameter of 30 mm and a length of 50 mm in which a bolt made of M12 steel having a length of 40 mm was embedded, and the number of cracks generated was determined. . The ethanol layer cooled by a refrigerator was used on the low temperature side of the heat cycle test, and the air constant temperature layer was used on the high temperature side.

As can be seen from the test results in Table 1, Comparative Example 1 in which the liquid crystal polymer fiber powder was not blended had a low heat distortion temperature, poor mechanical strength, and also poor crack resistance.

Further, Comparative Example 2 in which alumina powder is blended as a filler has a large dielectric constant, and as a result, it is difficult to improve high voltage resistance.

On the other hand, Examples 1 to 3 of the present invention have a high heat distortion temperature, are excellent in corrosion resistance, mechanical strength and crack resistance, and have a small dielectric constant and exhibit excellent high voltage resistance. Can be.

[0036]

The epoxy resin composition for gas-insulated equipment according to the present invention has a high heat distortion temperature and excellent corrosion resistance, mechanical strength and crack resistance when an epoxy resin casting for gas-insulated equipment is manufactured. Since it has a small dielectric constant and can exhibit excellent high voltage resistance, it is industrially useful.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 67:02 77:00)

Claims (4)

[Claims] 1. An epoxy resin composition comprising a liquid crystal polymer fiber powder. 2. The epoxy resin composition according to claim 1, wherein the liquid crystal polymer fiber powder is a liquid crystal polyester fiber powder or a liquid crystal polyamide fiber powder. 3. The epoxy resin composition according to claim 1, wherein the liquid crystal polymer fiber powder is liquid crystal polyester fiber powder or liquid crystal polyamide fiber powder, and the curing agent is an acid anhydride-based curing agent. 4. An epoxy resin cast product for gas-insulated equipment, characterized by casting an epoxy resin composition containing a liquid crystal polymer fiber powder.