JPH07150015A - Insulating spacer - Google Patents

Abstract

PURPOSE:To provide an insulating spacer low in dielectric constant, excellent on resistance to SF6-decomposed gas and mechanical strengths, and useful for gas-insulating switch devices, etc., by using a composition comprising alumina spherical powder and silica powder as a filler. CONSTITUTION:This spacer is produced by casting a SF6-resistant epoxy resin composition comprising (A) an epoxy resin, (B) a curing agent, and (C) a filler, (i) alumina spherical powder obtained by explosively burning aluminum in the flow of oxygen and (ii) silica powder being compounded as the component C. For example, the component (i) has preferably an average particle diameter of 0.3-5mum and a surface area of 7-20m<2>/g, and the component (ii) has preferably an average particle diameter of 5-15mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a low dielectric constant and is resistant to SF.
_{6 It} relates to insulating spacers used in gas-insulated switchgear, etc., which have excellent decomposition gas properties and mechanical strength.

[0002]

2. Description of the Related Art SF ₆ gas is used as an insulating medium for electrical equipment such as gas-insulated switchgear because it is stable both thermally and chemically and has high dielectric strength and excellent arc extinguishing properties. . It is necessary for the insulator used in this electric equipment to maintain stable characteristics over a long period of time without being corroded or deteriorated by the decomposition product even if the insulating gas is decomposed by the discharge in the equipment. A cast product such as an epoxy resin composition is used as an insulator. Epoxy resin compositions used for electrical insulation usually contain a large amount of silica powder as a filler. By blending silica powder, inexpensive and high-strength cast products can be obtained, but since they may be attacked by SF ₆ gas, alumina powder is usually used for gas insulated switchgear. .

However, alumina powder is expensive.
Further, it has drawbacks such as high specific gravity, high dielectric constant, and poor adhesiveness with epoxy resin. In particular, a high dielectric constant of 9.3 increases the relative dielectric constant of the composite insulator, which lowers the partial discharge resistance of the release electrode system, the partial discharge generation voltage in the peeling, and the mold creeping flashover voltage. Inconvenience in terms of electrical characteristics is likely to occur. Therefore, the dielectric constant is low,
Attempts have been made to suppress the synthetic dielectric constant by partially adding a filler having an SF ₆ decomposition gas resistance to alumina. For example, JP-A-50-17098 and JP-A-52-135400
JP-A-58-18217, magnesium fluoride, JP-A-57-203511 and JP-A-3-200858, aluminum fluoride, JP-A-57-203509. JP-A-57-203510 proposes that calcium fluoride is partially mixed with alumina. However, the compounding of these fillers often impairs the crack resistance and mechanical properties, which are the original purpose of compounding the inorganic fillers, and the compounding amount naturally occurs. In addition, these fillers have not been put to practical use because there is no guarantee that they will be stably supplied.

[0004]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an insulating spacer having a low dielectric constant, excellent SF ₆ decomposition gas resistance, and mechanical strength. is there.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned objects, the present inventors have found that by using a composition containing spherical alumina powder and silica powder as a filler, The inventors have found that the object can be achieved and completed the present invention.

That is, the present invention relates to an epoxy resin, a curing agent,
An epoxy resin composition containing a filler and the like, which is obtained by casting an epoxy resin composition for SF ₆ containing a spherical alumina powder obtained by detonation in an oxygen stream as a filler and a silica powder. Is an insulating spacer.

The present invention will be described in detail below.

The epoxy resin used in the present invention is not particularly limited as long as it has two or more epoxy groups in at least one molecule, and examples thereof include bisphenol A.
Type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A
Type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type or triglycidyl isocyanate type heterocycle Formula epoxy resins, brominated epoxy resins and the like can be used, and these can be used alone or in combination of two or more.

The curing agent for the epoxy resin used in the present invention is preferably an acid anhydride type one, for example, phthalic anhydride, tetrohydrophthalic anhydride, hexahydrophthalic anhydride, nadic acid anhydride, methylnadic acid anhydride. Maleic anhydride, trimellitic acid anhydride, pyromellitic acid anhydride, chlorendic acid anhydride, tetracarboxylic acid benzophenone anhydride, and the like can be used, and these can be used alone or in combination of two or more. It is desirable to use the stoichiometric amount of the curing agent, but it is also possible to change the resin characteristics by deviating from the equivalent amount. Further, a curing accelerator can be used if necessary. As the curing accelerator, a tertiary amine type, a quaternary ammonium salt type, an imidazole type, a DBU type or the like can be used.

The spherical alumina powder used in the present invention is a true spherical alumina fine powder obtained by detonating aluminum powder in an oxygen stream. The manufacturing method thereof is as described in JP-A-60-255602.
It can be manufactured by the MC (Vaporrized Metal Combustion) method. The average particle size of spherical alumina powder is 0.1-
The thickness is preferably 10 μm, more preferably 0.3 to 5 μm. If the average particle size is less than 0.1 μm, the flow characteristics of the resin will be poor and voided cast products cannot be obtained. On the other hand, if it exceeds 10 μm, it may settle in the resin composition and the uniformity of the cast product may be lost, which is not preferable. The surface area of the spherical alumina powder is preferably 5 to 30 m ² / g, more preferably 7 to 20 m ² / g. Surface area 5
If it is less than m ² / g, a large amount must be added without any effect on the SF ₆ gas resistance of the cast product, and the average particle size becomes large, which is disadvantageous in that it precipitates. 30 m surface area
If it exceeds ² / g, it becomes too fine and the viscosity of the resin increases,
It is not preferable because the workability is lowered. Regarding the compounding ratio of the spherical alumina powder, it is desirable that the ratio of the spherical alumina powder to the total surface area of the filler to be filled in the epoxy resin composition is 50% or more, more preferably 60 to 80%.

The silica powder used in the present invention can be used without any particular limitation as long as it is one that is usually used for casting or the like. For example, fused silica obtained by melting silica stone, crystalline silica produced naturally, and the like can be used. This silica powder may be dry pulverized or wet pulverized using a ball mill or a vibration mill, but any of them can be used. As the shape of silica powder, crushed type,
There are spherical types and the like, but any of them may be used, and these may be mixed and used. The average particle size of the silica powder is preferably 1 to 25 μm, more preferably 5 to 15 μm from the viewpoint of workability and sedimentation property. <1 μm or 25 μm
If it exceeds m, workability and sedimentation are poor, which is not preferable.

The above-mentioned alumina spherical powder and silica powder to be blended as a filler can be used without treatment, but it is preferable to treat them beforehand with a coupling agent such as a silane-based, aluminum-based or titanium-based coupling agent. In this case, it is preferable to add 0.2 to 3 parts by weight to 100 parts by weight of the filler. If it is less than 0.2 part by weight, the wettability between the resin and the filler is not effective, and if it exceeds 3 parts by weight, it is not effective and the cost is increased, which is not preferable.

The blending ratio of the filler of spherical alumina powder and silica powder is not particularly limited, but it is desirable to blend 100 to 500 parts by weight with respect to 100 parts by weight of the epoxy resin.
If the proportion is less than 100 parts by weight, the linear expansion coefficient of the resin will be large, resulting in poor dimensional accuracy and crack resistance of the cast product.If it exceeds 500 parts by weight, the viscosity of the resin will be high and workability will be increased. Is not preferable.

The SF ₆ -resistant epoxy resin composition used in the present invention contains an epoxy resin, a curing agent, an alumina spherical powder and a silica powder, but is a flame retardant within the range not deviating from the object of the present invention and if necessary. , Other additives such as a colorant and a viscosity reducing agent can be added and blended.

The epoxy resin composition for SF ₆ used in the present invention is mixed with an epoxy resin, spherical alumina powder, silica powder and other additives under a reduced pressure of 100 ° C. or more and mixed well, and then a curing agent, It can be manufactured by mixing a curing accelerator. The SF ₆ -resistant epoxy resin composition thus produced is vacuum cast, and primary curing is performed at 100 to 150 ° C. to such an extent that cracks do not occur, and then 120 to 150 after mold release.
The insulating spacer can be manufactured by performing the secondary curing at ℃.

[0016]

The insulating spacer of the present invention has a low dielectric constant by casting the epoxy resin composition for SF ₆ resistance using alumina spherical powder and silica powder as the filler.
It is stable against SF ₆ decomposition gas and has excellent mechanical strength.

[0017]

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

Examples 1 to 3 According to the blending composition shown in Table 1, SF ₆ resistant epoxy resin compositions were produced. That is, an epoxy resin and a filler of spherical alumina powder and silica powder were added and sufficiently mixed under a reduced pressure condition of 120 ° C., and then a curing agent was added and mixed to prepare an SF ₆ epoxy resin composition. This composition
It was cast in a mold preheated to 120 ° C., defoamed at 0.5 Torr for 20 minutes, and primary cured in the mold at 120 ° C. for 15 hours. After mold release
The insulating spacer was manufactured by carrying out secondary curing at 130 ° C. for 15 hours. It has an electrode 2 and a fixing bush 3 and is resistant to S
It was cast with the epoxy resin composition 1 for F ₆ , and its sectional view is shown in FIG. 1.

Comparative Examples 1 to 2 S resistance to S was measured in the same manner as in Examples according to the blending composition shown in Table 1.
An epoxy resin composition for F ₆ was produced. In addition, an insulating spacer was manufactured in the same manner as in the example.

With respect to the insulating spacers obtained in Examples 1 to 3 and Comparative Examples 1 to 2, SF ₆ decomposition gas resistance, dielectric constant, tensile strength and bending strength were tested. The results are shown in Table 1 and FIG. Shown in 2. The present invention is excellent in mechanical strength and has a dielectric constant equivalent to that of silica powder, so that the remarkable effect of the present invention can be confirmed.

[0021]

[Table 1] * 1: Product name manufactured by Ciba Geigy. * 2: Product name manufactured by Ciba Geigy. * 3: Spherical particles produced by VMC method, average particle size 0.5μ
m, surface area 16 m ² / g, treated with N-β (aminoethyl) γ-aminopropyltrimethoxysilane. * 4: Spherical particles produced by VMC method, average particle size 2μm
, Surface area 10 m ² / g, treated with N-β (aminoethyl) γ-aminopropyltrimethoxysilane. * 5: Average particle size of 10 μm, surface area manufactured by the Bayer method
Untreated at 3.4 m ² / g. * 6: Wet-milled fused silica, average particle size 13 μm, surface area 3.2 m ² / g, treated with γ-glycidoxytrimethoxysilane * 7: Dry-milled crystalline silica, average particle size 20 μm,
Untreated product with a surface area of 2.9 m ² / g * 8: Measured according to JIS-K-6911. * 9: A polypropylene container containing 50 g of 46 wt% HF solution was placed in an acrylic desiccator having an internal volume of 64 l. Put the test piece in the desiccator and keep it sealed,
The time variation of the surface resistance was measured with an ultra-insulation meter and comparative evaluation was performed. The results are shown in FIG. 2. Example 1 according to the present invention
In Nos. 3 to 3, the surface resistance did not decrease sharply even after 10 hours, remained substantially flat even after 40 hours, and the surface resistance maintained 10 ¹³ or more. ○ mark… 10 ¹³ or more, × mark…
10 ¹³ or less.

[0022]

As is apparent from the above description and the results of Table 1 and FIG. 2, the insulating spacer of the present invention has a low dielectric constant, excellent SF ₆ decomposition gas resistance, and mechanical strength. , Reliable.

[Brief description of drawings]

FIG. 1 shows a partially cutaway front view of an insulating spacer of the present invention.

FIG. 2 shows a surface resistance value-exposure time characteristic diagram for comparatively evaluating SF ₆ decomposition gas resistance.

[Explanation of symbols]

1 Epoxy resin composition for SF ₆ resistance 2 Electrode 3 Bushing for fixing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Asahina 2-9-5 Shiba Park, Minato-ku, Tokyo Tatsumoriuchi Co., Ltd.

Claims (1)

[Claims] 1. An epoxy resin composition containing an epoxy resin, a curing agent, a filler, etc., for SF ₆ resistance, wherein a spherical alumina powder obtained by detonating in an oxygen stream as a filler and silica powder are blended. An insulating spacer formed by casting an epoxy resin composition.