JPH0230017A - Resign mold parts - Google Patents

Abstract

PURPOSE:To improve the mechanical characteristic and the thermal shock resistance of high voltage insulation parts by forming the inorganic film having the main component of aluminum and the thickness below a specific one on the surface of a cast resin, and forming an epoxy resin coating film on the surface of the inorganic film. CONSTITUTION:The surface of a cast resin 2 is degreased with an organic solution, and surface rough machining with a sand blast is made. An aluminum system inorganic filling material 4 using the solution of aluminum is applied to the surface mentioned above with a spray gun at the thickness below 1.0mm. When the thickness is 1.0mm or more, a fine crack is easily occurred on a film surface. Moreover an epoxy coating film 5 is formed on the material 4. This constitution enables mechanical and thermal characteristics to be improved with electric characteristic unlowered since the resin 2 including a glass fiber and a silica powder is unexposable directory to a SF cracked gas by means of the film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a resin molded part for high voltage insulation used in electrical equipment using insulating scum such as sulfur hexafluoride.

(Conventional technology) In recent years, there has been a strong tendency for electrical equipment to become smaller and larger in capacity, and in the high voltage range, insulating gas such as sulfur hexafluoride gas (hereinafter referred to as SF6 gas) is used to insulate equipment. A combination of solid insulation such as epoxy and cast epoxy is used to meet the above requirements.

Materials used for solid insulation of high-voltage equipment are not made of resin alone, but have large amounts of inorganic fillers added to them. Addition of an inorganic filler brings about improvement in thermal shock resistance by reducing the coefficient of thermal expansion, reduction in curing shrinkage, improvement in mechanical properties, abrasion resistance, heat resistance, chemical resistance, and other properties. Typical inorganic fillers are silica powder,
Glass fiber, calcium carbonate, etc. are known. especially,
By filling with glass fibers, thermal shock resistance and mechanical properties can be significantly improved.

However, most of these fillers are unsuitable for high voltage insulating resin molded parts used in SF6 gas.

As is well known, SF6 gas is widely used as an insulating medium for high voltage equipment due to its excellent arc extinguishing properties and dielectric strength. This SF6 gas is usually chemically stable, but decomposes due to arc, corona, heat, etc.

This SF6 gas includes SF4 and 32F2.

There are SOF2, SOF4.302F2, etc., and these decomposed gases react with the above-mentioned inorganic fillers in the presence of moisture, etc., and significantly deteriorate various properties of the cured resin material.

FIG. 4 shows that SF6 decomposed gas is generated in a closed container by a large current arc with an SF6 gas pressure of 4a-tlll, a current duration of 60 sec, and a cycle of 10 discharges and 3-5m groups at 1-hour intervals. It shows the change in insulation resistance of epoxy resin casting materials containing each filler. However, the discharge time indicates the accumulated @ interval. As can be seen from the figure, the system filled with silica powder and glass fiber is affected by decomposition gas and has a significant drop in insulation resistance. These compositions have excellent thermal shock resistance and characteristics within the a range, but S
Its use as an insulating material in F6 gas is highly problematic.

Therefore, one method of making the casting material usable in SF6 gas is to select a filler that is resistant to SF5 decomposition gas.

Alumina powder (203 in A), CaF.

This includes Ca S04, etc., but Ca F, Ca SO4, etc. are not practical in terms of mechanical properties. Among these, alumina powder is resistant to SF6 decomposition gas, as shown in Figure 4, and has mechanical properties similar to those of CaF.

Since it is superior to Ca 804 etc., it has been widely used as a filler for SF6 gas.

(Problems to be Solved by the Invention) However, the alumina powder-filled system is also brittle and considerably inferior in mechanical strength and thermal shock resistance when compared to the silica powder-filled system and the glass IIi fiber-filled system.

- By way of example, the properties of each of the following compositions are shown in Table 1.

Composition-1 Bisphenol type epoxy resin 100 parts by weight Acid anhydride curing agent 85 parts by weight Alumina powder
400 heavy mass curing accelerator
0.5 parts by weight Composition - 2 Bisphenol type epoxy resin 100 parts by weight Acid anhydride curing agent 85 parts by weight Silica powder Glass fiber curing accelerator No. 1 Table 200 parts by weight 200 parts by weight 0.5 @ parts by weight Table 2 The bending strength test method was based on JIS 7203, and the crack resistance index was determined by a thermal shock test under the test conditions shown in Table 2.

(Margin below) *1 unit is °C *2 unit is min *3
After curing, the test casting is left at room temperature a, and the cold test is repeated at a predetermined maximum temperature for a predetermined period of time. As the test progresses, the temperature range of the thermal test gradually increases.

Low temperature is IP cooled to the desired temperature with dry ice.
In a cooling tank containing A, a high or warm) lagoon is obtained in a confinement or heating furnace.

b. The repetition cycle, test order and time for testing the test castings are given in the table above. All temperatures are ±2℃
must be kept within.

As described above, there are various difficulties in obtaining resin molded parts that can be used in SF6 gas and have excellent mechanical strength and thermal shock resistance.

An object of the present invention is to provide a resin molded component that does not deteriorate in electrical properties even when used in SF6 gas and has excellent mechanical properties and thermal shock resistance.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides resin molded parts by applying an alumina-based inorganic filler that is resistant to SF6 decomposition gas to the surface of the casting resin to form a coating of 1# or less. It is characterized by forming a coating film of epoxy resin on the surface.

(Function) Since an inorganic coating and a resin layer that are resistant to SF6 decomposition gas are formed on the surface of the casting resin, it protects the internal casting resin from SF6 decomposition gas and at the same time ensures electrical insulation along the surface. Furthermore, the mechanical properties of the entire resin molded part are shared by the casting resin.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a resin insulator which is an embodiment of the resin molded part according to the present invention, and FIG. 2 is a cross-sectional view of A of FIG.
FIG. Resin insulator 1 has the above composition-2
A casting resin 2 manufactured by casting using a material of 2 and having an uneven surface on its outer peripheral surface, a metal insert 3 embedded in both ends of the casting resin 2 and having a screw hole (not shown), It consists of an alumina-based inorganic film 4 having SF6 decomposition gas resistance formed on the outer surface of the mold resin 2, and an epoxy coating film 5 containing no inorganic filler formed on the surface of this alumina-based inorganic film 4.

Next, a method for manufacturing the alumina-based inorganic film 4 and the epoxy coating film 5 will be explained.

Using the material of Composition-2 described above, the surface of the casting resin 2 obtained by casting is degreased with an organic solvent, and the surface is roughened by sandblasting. Nutac N is an alumina-based inorganic filler that uses alcohol as a solvent on its surface.
-1100 (product name of Shinyo Shirorenga Co., Ltd.) with a thickness of 1.0.
Apply the following using a spray gun to avoid uneven coating.

The thickness is 1.0. If the temperature exceeds that level, fine cracks are likely to occur on the surface of the coating.

As shown in FIG. 3, the adhesive strength of the alumina-based inorganic filler tends to increase as the surface roughness of the adherend increases. Therefore, taking this into consideration, the surface roughness of the casting resin 2 is set to 1.
40 terms or more.

The drying conditions are: dry to the touch at room temperature x approximately 1 hour;
In this example, the temperature was set at 120°C for 10 minutes or more.

The alumina-based inorganic coating 4 thus obtained is dense and can be used as is, but when attached to equipment, there is a risk that it may come into contact with other objects and damage the alumina-based inorganic coating 4. Therefore, in order to protect the film, a bisphenol type epoxy resin, Araldite CY232 (trade name of Nippon Ciba-Geigi Co., Ltd.) is added to the surface of the film.
100FI part, hardener H which is an amine hardener
10 parts by weight of '1'951 (trade name of Nippon Ciba Geigi Co., Ltd.) is applied to form an epoxy coating film 5. A brush was used to apply the formulation, and the drying conditions were 60'.
C1Hr or more. By doing so, the alumina-based inorganic coating 4 is protected from the outside.

New tack made with the above alumina-based inorganic filler
The cured product of N-1100 has properties close to those of ceramics, and its coating is dense and has excellent resistance to SF6 gas. In this way, with the alumina-based inorganic coating 4,
Since the casting resin 2 containing glass fibers and silica powder is not directly exposed to SF6 decomposition gas, its mechanical properties do not deteriorate.

Next, the characteristics of the resin insulator according to the above embodiment and the resin insulator manufactured using a conventional alumina powder-filled casting material will be compared.

First, the initial surface resistance of both is 10150 or more, which is about 0. 3 containing SF6 decomposition gas with I Vo1%
．． Even after being left in SF6 gas at OKgf/cm2 gauge pressure for 10 days, both maintained a resistance of 1013Ω or more.

Next, a liquid phase cooling/heating cycle of 1 hour at 0°C and 1 hour at 100°C was performed 10 times, and the bending strength before and after was determined.

The bending test was performed using a cantilever beam loading method in accordance with JIS regulations, and the tip of the resin insulator was used. A static bending load is applied to a50m, and the breaking load is determined. The initial breaking strength of the resin insulator made of the conventional alumina powder-filled casting material and the resin insulator of the above example was 640K on average of the three pieces.
(Jf was 880 Kgf, but after the cooling/heating cycle, the breaking strength of the resin insulator made of the conventional casting material decreased to an average of 420 KQf, which was lower than the load capacity of 600 Kgf. However, the resin insulator according to the above example There was almost no change in g4 from 800 even after the cooling/heating cycle.In addition, visual inspection after the cooling/heating cycle revealed no blistering, cracking, or peeling of the alumina-based inorganic coating 4 or epoxy coating 5. .

"Effects of the Invention" As explained above, according to the present invention, SF6
It is possible to provide a resin molded part that does not suffer from deterioration of properties even by decomposed gas and has excellent mechanical and thermal properties.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of a resin insulator according to an embodiment of the present invention, Fig. 2 is an enlarged view of part A in Fig. 1, and Fig. 3 is an alumina-based inorganic insulator used in an embodiment of the present invention. A diagram showing the relationship between the surface roughness of the adherend and adhesive strength of the filler. Figure 4 is a diagram showing the change in insulation resistance of an epoxy cast product in SF5 decomposition gas using various fillers as parameters. be. 1...Resin insulator, 2...Casting resin 3...Metal insert 4...Alumina-based fi organic coating 5...Epoxy coating Agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken Figure 1 Figure 2 Figure 4 Chart &1#-? (,um) Figure 3

Claims (1)

[Claims] A resin molded part, characterized in that an inorganic film containing alumina as a main component and having a thickness of 1.0 mm or less is formed on the surface of a casting resin, and an epoxy resin coating film is further formed on the surface.