JPH0812854A - Epoxy resin composition for gas insulation equipment and epoxy cast product - Google Patents

Abstract

PURPOSE:To obtain the subject composition stabilized electrically, thermally, mechanically and chemically, by incorporating a resin base composed of a crosslinked acrylic rubber fine particle-contg. epoxy resin and acid anhydride curing agent with powder of an inorganic compound except boron compounds and silicon compounds. CONSTITUTION:This composition is obtained by incorporating 100 pts.wt. of an epoxy resin base composed of (A) a cross-inked acrylic rubber particle-contg. epoxy resin and (B) an acid anhydride curing agent (e.g. phthalic anhydride, trimellitic anhydride) with (C) as filler, 100-400 pts.wt. of powder of an inorganic compound (e.g. alumina, calcium carbonate) except boron compounds and silicon compounds. It is preferable that the crosslinked acrylic rubber fine particle content of the epoxy resin in the component A be 1-30wt.%. The crosslinked acrylic rubber fine particles are recommended to obtain by polycrosslinking of an acrylic ester monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy cast product used in electric equipment filled with sulfur hexafluoride gas, especially in coexistence with an insulating gas, and an epoxy resin composition for obtaining the same.

[0002]

2. Description of the Related Art SF ₆ gas (sulfur hexafluoride gas) has excellent electrical insulation and arc extinguishing properties, is chemically stable, and can reduce the size and weight of equipment. Widely used to insulate electrical equipment such as transformers, transformers, power cable terminal bushings, and busbars.

This SF ₆ gas is decomposed by an arc or corona discharge generated in the equipment to generate a highly reactive decomposition product, so that it is used in electric equipment used together with SF ₆ gas. The epoxy cast product is formed to have long-term durability without being corroded or deteriorated by the insulating gas decomposition product.

[0004] The durability of epoxy cast products against insulating gas decomposition products is largely related to the characteristics of the filler, which is one of the main components of epoxy cast products, and usually aluminum oxide (alumina) is used as the filler. ) Is added in an amount of about 70% by weight.

The use of alumina as a filler improves the durability of the epoxy cast product against insulating gas decomposition products, but increases the dielectric constant. This causes local electric field concentration due to the insulation design of the electric equipment or the shape of the epoxy cast product, and when the electric field concentration occurs, the desired dielectric breakdown characteristics may not be satisfied. Therefore, there is a strong demand for reduction of the dielectric constant in epoxy cast products for ultrahigh pressure gas insulation equipment.

In this regard, dolomite, sodium fluoride, calcium fluoride, magnesium fluoride, aluminum fluoride and the like are known as fillers having a dielectric constant smaller than that of alumina and resistant to insulating gas decomposition products. However, an epoxy cast product made from a cured epoxy resin containing these fillers has a disadvantage that cracks are likely to occur in a portion where a metal conductor, an electrode fitting, etc. are embedded.

On the other hand, as a method for improving the crack resistance of the epoxy cast product, a method of compounding a liquid carboxyl group-terminated butadiene acrylonitrile copolymer rubber has been proposed, but its electrical insulation is insufficient.

[0008] In recent years, the amount of heat generated by electric equipment has increased due to higher performance and miniaturization, and the epoxy cast products used in such electric equipment are more frequently exposed to high temperatures. The epoxy cast product is used in consideration of temperature rise because its electrical and mechanical properties are remarkably deteriorated when its heat distortion temperature is exceeded.

[0009]

However, according to the conventional epoxy cast product for gas insulation equipment, when it is constructed so as to improve the heat resistance, cracks easily occur and the crack resistance is improved. Since it has the contradictory characteristic of lowering the heat resistance, there is a problem that it is difficult to satisfy these characteristics at the same time.

Accordingly, it is an object of the present invention to provide an epoxy resin composition and an epoxy cast product for gas insulation equipment, which have electrically, thermally, mechanically and chemically stable properties.

[0011]

The present invention provides electrical, thermal,
In order to impart mechanically and chemically stable properties, 100 parts by weight of an epoxy resin base consisting of an epoxy resin containing crosslinked acrylic rubber fine particles and an acid anhydride curing agent is added with a boron compound or a silicon compound as a filler. Provided are an epoxy resin composition for a gas insulation device, which contains 100 to 400 parts by weight of a powder of an inorganic compound to be removed, and an epoxy cast product obtained by casting and curing the resin composition.

The epoxy resin used in the present invention includes:
There are bisphenol-based epoxy resins, cycloaliphatic epoxy resins, novolac-type epoxy resins, and naphthalene-based epoxy resins, and if necessary, two or more kinds of resins can be mixed and used.

Particularly, in the present invention, a crosslinked acrylic rubber-dispersed epoxy resin in which crosslinked acrylic rubber fine particles prepared by polymerizing and cross-linking an acrylic acid ester monomer in advance so as to contain crosslinked acrylic rubber fine particles is uniformly dispersed in an epoxy resin. use.

The particle size of the crosslinked acrylic rubber fine particles used in the present invention is about 0.1 to several μm, and the effect of improving the toughness and crack resistance of the epoxy cured resin is remarkable,
It was found that there is no defect that heat resistance and electric properties are deteriorated unlike the known carboxyl group-terminated butadiene acrylonitrile copolymer liquid rubber.

The content of the crosslinked acrylic rubber fine particles in the epoxy resin is not particularly limited, but it is preferably 1 to 30% by weight in the epoxy resin. 1% by weight
If the amount is less than the above range, the use effect is not sufficiently exhibited, and if the amount is more than 30% by weight, the defoaming property at the time of degassing under reduced pressure is deteriorated, which is not preferable.

The acid anhydride epoxy curing agent used in the present invention includes phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylendomethylene anhydride. Tetrahydrophthalic acid, trimellitic anhydride, etc. may be mentioned, and two or more of these may be used in combination.

In the present invention, powders of inorganic compounds other than boron compounds and silicon compounds are used as fillers, and alumina, calcium fluoride, magnesium fluoride, aluminum fluoride, magnesium oxide, hydrated alumina, calcium carbonate, calcium sulfate. Etc., and two or more kinds may be used in combination.

The amount of the filler used is preferably 100 to 400 parts by weight based on 100 parts by weight of the epoxy resin base consisting of the epoxy resin and the acid anhydride curing agent. If the filler is used as much as possible within the range where casting workability and mechanical strength are allowed to decline, the amount of shrinkage during curing and the expansion coefficient of the cured resin will be smaller, improving crack resistance and heat dissipation. To do.
When the amount of the filler used is less than 100 parts by weight, crack resistance becomes insufficient, and when it is more than 400 parts by weight, the casting operation becomes difficult.

[0019]

According to the present invention, a powdery inorganic compound 1 obtained by removing the boron compound and the silicon compound from the epoxy resin base 1
By adding 0.00 to 400 parts by weight as a filler, it is possible to improve the durability against the decomposition product of SF ₆ gas with a low dielectric constant. Further, the acrylic rubber fine particles added at the same time improve the mechanical properties without lowering the heat resistance with a low dielectric constant.

[0020]

EXAMPLES Hereinafter, the epoxy resin composition for gas insulation equipment and the epoxy cast product of the present invention will be described in detail.

The epoxy resin composition of the present invention comprises an epoxy resin base composed of an epoxy resin, acrylic rubber fine particles and a curing agent, and a filler added to the epoxy resin base.

Epoxy resins include bisphenol solid resin Epicoat 1001 (Epoxy equivalent 450-500 manufactured by Shell Chemical Co., Ltd.), cycloaliphatic epoxy celoxide 2021 (epoxy equivalent 128-140 manufactured by Daicel Chemical Industries, Ltd.), Bisphenol-based epoxy resin Epicoat 828 [Shell Chemical Co., Ltd. epoxy equivalent 18
4 to 194], CX-MN77 [made by Nippon Shokubai Kagaku Kogyo KK, viscosity 500 poise (25 ° C.), epoxy equivalent 23
0] and CX-MN201 [solid resin, epoxy equivalent 560] were used.

Both CX-MN77 and CX-MN201 are acrylic rubber fine particles uniformly dispersed in a bisphenol epoxy resin in an amount of 20 parts by weight. These epoxy resins may be used as a mixture of two or more kinds as required.

Further, in the present invention, a crosslinked acrylic rubber-dispersed epoxy resin obtained by uniformly dispersing crosslinked acrylic rubber fine particles prepared by polymerizing and crosslinking an acrylic acid ester monomer in advance so as to contain the crosslinked acrylic rubber fine particles is usually used. It is also possible to use it in combination with the epoxy resin.

The curing agent is an acid anhydride type epoxy curing agent, and in this embodiment, methyltetrahydrophthalic anhydride [Me-THPA, manufactured by Hitachi Chemical Co., Ltd., trade name HN].
2200] and tetrahydrophthalic anhydride type curing agent TH
PA [Hitachi Ciba Geigy Co., Ltd. product name Hardener H
T903] was used. Benzyldimethylamine [BDMA, manufactured by Nippon Kayaku Co., Ltd.] was used as the curing accelerator.

The filler is a powder of an inorganic compound containing no boron compound or silicon compound, and in this embodiment, alumina, calcium fluoride or aluminum fluoride was used.

On the other hand, the above epoxy resin base contains
If necessary, a colorant, an antioxidant, etc. may be added.

Epoxy resin compositions were prepared as Examples 1 to 5 by selecting and blending the above materials (Table 1).

At this time, Comparative Examples 1 and 4 made of an epoxy resin base containing no acrylic rubber particles,
Comparative Examples 2, 3, 6 and 7 in which a boron compound or a silicon compound was used as the filler, and the filler content was 100.
Comparative Example 5 containing less than or equal to parts by weight was simultaneously prepared (Table 1).

The blending ratios in Table 1 are parts by weight. In addition, parts by weight of the acrylic rubber fine particles contained in the mixed epoxy resin are shown.

[0031]

[Table 1]

The epoxy resin compositions of Examples 1 to 5 and Comparative Examples 1 to 7 were poured into a mold, first cured at 100 ° C. for 10 hours, then secondarily cured at 130 ° C. for 20 hours, and further cured.
A test piece (cast product) was prepared by tertiary curing at 0 ° C. for 20 hours.

Next, each test piece was evaluated for HF resistance and crack resistance, and the results are shown in Table 2.

[0034]

[Table 2]

The HF resistance was evaluated by placing a reagent grade hydrofluoric acid containing a vat on the bottom of a plastic digitizer in a room and placing the inside of the digitizer on a shelf with a hydrogen fluoride atmosphere and an outer diameter of 100 mm. A 3 mm test piece was left standing for 40 hours and then taken out, and after the surface was wiped, it was dried in a draft for 24 hours, and then the dielectric constant, dielectric loss tangent and volume resistivity were measured, before the HF resistance test at 20 ° C. Was compared with the initial value of.

In Table 2, the dielectric constant, the dielectric loss tangent and the volume resistivity are measured in accordance with JIS K6911, and the dielectric constant and the dielectric loss tangent are measured at 50 Hz and 1000 V by a Schering bridge. It was measured.

On the other hand, the crack resistance is M12 and the length is 40 mm.
28mm in diameter and 50mm in length with steel bolts embedded in
The heat cycle test shown in Table 3 was carried out on the test piece of No. 3, and the number of stages in which cracks were generated was determined and shown as a crack resistance index. The low temperature side of the heat cycle test used an ethanol tank cooled by a refrigerator, and the high temperature side used an air constant temperature tank.

[0038]

[Table 3]

The relationship between the cured resin and the resistance to SF ₆ discharge decomposition gas of the cured resin will be described. SF ₆ gas used in SF ₆ gas insulation equipment is decomposed by an arc or corona discharge generated in the equipment to generate SF ₆ gas. ₂ , SF ₄ , S ₂ F ₂ , S
It produces highly reactive decomposition products such as OF ₂ , SOF ₄ , and SO ₂ F ₄ . The most produced of these decomposition products is SF ₄ , and in the case of SF ₄ , when contacted with water or steam,

[0040]

Embedded image

Similarly, in SOF ₂ ,

[0042]

Embedded image

By carrying out the decomposition reaction as described above, hydrofluoric acid having a strong corrosive property is produced.

Therefore, the SF ₆ discharge decomposition gas resistance and the hydrofluoric acid resistance of the insulating material have a close correlation, and the SF ₆ discharge decomposition gas resistance can be predicted by the HF resistance test.

The epoxy resin compositions of Examples 1 to 5 have improved crack resistance, less deterioration in electrical characteristics in the HF resistance test, and excellent characteristics for SF ₆ gas insulation equipment. Was confirmed.

Comparative Examples 1, 4 and 5 had remarkably insufficient crack resistance, and Comparative Examples 2, 3, 6 and 7 had other dielectric constants, dielectric loss tangents and volume resistivities after the HF resistance test. The decrease is remarkable compared to.

[0047]

As described above, according to the present invention, 100 parts by weight of an epoxy resin base comprising an epoxy resin containing crosslinked acrylic rubber fine particles and an acid anhydride curing agent is added to a boron compound or a silicon compound as a filler. Since 100 to 400 parts by weight of the powder of the inorganic compound other than is mixed, electrically, thermally, mechanically and chemically stable characteristics can be imparted.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location // B29K 63:00 B29L 31:26 (72) Inventor Kazuo Suzuki 5 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1-1 No. 1 within Hitachi Cable FM Co., Ltd.

Claims (3)

[Claims] 1. 100 to 400 parts by weight of an inorganic compound powder excluding a boron compound and a silicon compound as a filler with respect to 100 parts by weight of an epoxy resin base comprising an epoxy resin containing crosslinked acrylic rubber fine particles and an acid anhydride curing agent. An epoxy resin composition for gas-insulated equipment, characterized in that the composition is mixed. 2. Crosslinked acrylic rubber fine particles are obtained by polymerizing and crosslinking an acrylic acid ester monomer.
The epoxy resin composition for gas insulation equipment according to claim 1. 3. 100 to 400 parts by weight of an inorganic compound powder excluding a boron compound and a silicon compound as a filler, based on 100 parts by weight of an epoxy resin base comprising an epoxy resin containing crosslinked acrylic rubber fine particles and an acid anhydride curing agent. An epoxy cast product for gas insulation equipment, which is obtained by casting and curing an epoxy resin composition containing parts.