JP3207720B2 - Resin molded component and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded part such as a molded valve in heavy electric equipment and a method of manufacturing the same.

[0002]

2. Description of the Related Art In the field of heavy electrical equipment, resin molded parts for high-voltage insulation are widely used as electric insulation materials and structural materials. Thermosetting resins such as epoxy resin, phenolic resin, polyimide resin, and polyester resin are three-dimensionally crosslinked and have many excellent heat resistance, moisture resistance, chemical resistance, dimensional stability, electrical characteristics, etc. This material is widely used as a resin material for resin molded parts. However, these thermosetting resins are generally very brittle materials, and the mechanical strength is significantly reduced in the presence of stress concentration parts, microcracks, foreign matter, defects, voids, and the like. Some high-pressure insulating resin mold parts have a built-in metal or ceramic, such as a mold valve. In this case, due to the difference in the coefficient of thermal expansion, a residual stress at the time of casting occurs at the resin / ceramic / metal bonding interface, or a large thermal stress occurs due to a temperature difference or a temperature change, resulting in a low toughness heat. Cracks are easily generated in the curable resin.
Once cracks occur, they quickly propagate through the resin without stopping, leading to destruction. In some cases, an accident such as a ground fault is induced.

For example, a mold valve 10 has a structure as shown in FIG. 7, and encloses a vacuum valve 2 with an epoxy resin 11 filled with silica powder. This mold valve 10 is incorporated in a vacuum circuit breaker. By molding the vacuum valve 2 with the epoxy resin 11, insulation along the surface of the vacuum valve 2 is strengthened, and a function of structurally retaining the insulation is provided. As a result, the entire vacuum circuit breaker is very small and downsized. However, as described above, the difference in the coefficient of thermal expansion between the alumina constituting the vacuum valve 2 and the epoxy resin 11 is large, and a large residual stress is generated in the process of cooling from high temperature to room temperature during casting. Alternatively, a large thermal stress is generated due to a temperature change during the suspension of operation. In addition, when it is kept in a cold region, it is expected that it will be cooled down to about −35 ° C. when it passes over the polar sphere by an air wheel, and is exposed to extremely large stress. For this reason, the epoxy resin 11 surrounding the vacuum valve 2 is cracked and mechanically and electrically broken.

At present, in order to avoid such a problem,
A two-stage molding method using a buffer layer has been applied. This is a method of once wrapping the vacuum valve 2 with a soft flexible epoxy resin to a thickness of several millimeters to form a cushion layer 12 and then re-casting the outside with a hard epoxy resin 11 to finish the outer dimensions to predetermined dimensions. It is. Such a two-stage molding method has to be applied to components such as the vacuum valve 2 which are difficult to mold directly due to their thermal expansion coefficient and shape.

[0005]

However, in the two-stage molding method, it is necessary to provide a cushion layer having a predetermined thickness, and equipment and curing conditions different from those of the conventional casting resin are required. This leads to a decrease in efficiency. In addition, a new adhesive interface called a casting epoxy resin appears, and this easily becomes a weak point. For this reason, strict quality control in the casting process is indispensable, and the load on facilities and work increases.

In order to reduce the stress generated at the resin / ceramic / metal interface, it is ideal to make the thermal expansion coefficient of the epoxy resin itself close to that of the ceramic / metal. Epoxy resin alone has a coefficient of thermal expansion that is about one order of magnitude higher than that of ceramics, etc., and is filled with a large amount of inorganic particles such as silica and alumina as described above to reduce the coefficient of thermal expansion. . In this case, since the coefficient of thermal expansion changes substantially according to the composite rule, the stress at the interface can be reduced by filling more inorganic particles. However, when the filler is filled in a large amount, the viscosity of the mixture is significantly increased, and the fluidity, workability, and defoaming property inherent in the casting material are impaired. For this reason, the filling amount has an upper limit practically, and the filling amount is suppressed to a level that maintains the properties as a casting material.

As described above, the two-stage molding method and the high filling method of the inorganic filler each have problems, and molding of components such as a vacuum valve is difficult.

Accordingly, the present invention reduces the thermal stress at the interface, prevents the occurrence of peeling and cracks at the interface, and eliminates the need for a two-stage molding method having a flexible cushion layer having the above-mentioned problems. It is an object of the present invention to provide a resin molded component excellent in long-term reliability such as crack resistance and heat cycle resistance and electrical characteristics such as corona resistance, and a method for manufacturing the same.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a resin-molded component in which an embedded material is molded with an electrically insulating thermosetting resin. (1) a step of sequentially coating a plurality of thermosetting resins having different coefficients of thermal expansion, each of which is filled with inorganic particles into the embedded material, from the one having a low coefficient of thermal expansion; and (2) a thermosetting resin for casting. And (3) a step of, after casting the thermosetting resin for casting, curing the thermosetting resin and the thermosetting resin for casting. In the above configuration, a resin layer whose coefficient of thermal expansion changes in the thickness direction is easily formed at the interface of the embedded material. Therefore, it is possible to reduce the thermal stress caused at the interface between the embedded material and the thermosetting resin due to the difference in the coefficient of thermal expansion between the two.

According to a second aspect of the present invention, there is provided a resin molded part manufactured by the method of manufacturing a resin molded part according to the first aspect, wherein the amount of the inorganic particles filled in the thermosetting resin is changed. The gist of the invention is to change the coefficient of thermal expansion of the thermosetting resin. Thermosetting resins having different coefficients of thermal expansion can be easily realized.

According to a third aspect of the present invention, there is provided a resin molded part manufactured by the method for manufacturing a resin molded part according to the first aspect, wherein the particle diameter of the inorganic particles filled in the thermosetting resin is changed. The gist of the invention is to change the coefficient of thermal expansion of the thermosetting resin. Thermosetting resins having different coefficients of thermal expansion can be easily realized. Further, in this case, fine packing is possible, and the coefficient of thermal expansion can be changed in a wider range.

According to a fourth aspect of the present invention, there is provided a resin molded part manufactured by the method for manufacturing a resin molded part according to the first aspect. The gist is to form a gradient layer whose expansion coefficient changes continuously. A resin layer whose coefficient of thermal expansion changes continuously is formed at the interface of the embedded material.

According to a fifth aspect of the present invention, there is provided a resin molded part manufactured by the method for manufacturing a resin molded part according to the first aspect, wherein the inorganic particles include silica,
The gist is to use at least one of alumina, glass fiber and dolomite. In the above configuration,
As the inorganic particles, at least one of silica, alumina, glass fiber, and dolomite is used depending on the use environment and the like. The inorganic particles can be made of a material suitable for the use environment and the like, and the thermal stress at the interface can be reduced more reliably.

According to a sixth aspect of the present invention, there is provided a resin molded component manufactured by the method for manufacturing a resin molded component according to the first aspect, wherein the resin main component is a thermosetting resin and a thermosetting resin for casting. The gist of the invention is that any one of epoxy resin, polyimide resin and unsaturated polyester resin is used. In the above-described configuration, any one of an epoxy resin, a polyimide resin, and an unsaturated polyester resin is used as the main resin of the thermosetting resin and the thermosetting resin for casting, depending on the use environment and the like. The resin base material of the thermosetting resin and the thermosetting resin for casting can be made of a resin material according to the use environment and the like. Long-term reliability such as crack generation prevention, crack resistance and heat cycle resistance, and electrical properties such as corona resistance can be further enhanced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Normally, bisphenol-based solid epoxy resins often used in heavy electric equipment (for example, CY22
5, a trade name of Ciba-Geigy) and an acid anhydride curing agent (eg, HY925, a trade name of Ciba-Geigy) and silica powder as an inorganic powder (eg, Hughrex RD)
-8, trade name of Tatsumori Co., Ltd., average particle size 15 μm) The characteristics were evaluated using a heat-curable epoxy casting material composed of a combination of fillers as a basic composition.

[0016]

[Table 1] Table 1 shows the composition of a standard heat-curable epoxy casting material. Usually, in order to perform a casting operation, it is essential that the viscosity be several thousand cp or less.
It is suppressed by filling of about 00 phr (per hundred of resin by weight). FIG. 4 shows the relationship between the silica powder filling amount and the viscosity. When the filling amount exceeds 700 phr, 10
000 cp or more, which is an area unsuitable for casting.

[0017]

[Table 2] Next, the relationship between the filling amount of silica powder and the coefficient of thermal expansion is shown in FIG. The coefficient of thermal expansion tends to decrease as the filling amount increases. When the particle size of the silica powder is large, the filling amount is limited. Therefore, in the high filling region of 60 vol% or more, the silica powder having a small particle size (for example, Hughes Rex FF, trade name of Tatsumori Co., Ltd., average Particle size 2 μm) and 1:
Fill with 1 to achieve fine packing.

As a buried material, for example, when molding a vacuum valve, the thermal expansion coefficient of alumina constituting the vacuum valve outer tube is 8 × 10 ⁻⁶ / ° C.
0 × 10 ⁻⁶ / ° C. amorphous silica has 4 × 10 ⁻⁷ / ° C. As shown in FIG. 5 and Table 2, when the filling amount of the amorphous silica powder was changed, a composition having an arbitrary coefficient of thermal expansion was obtained. Get. If the vacuum valve is directly molded using this composition, the difference in coefficient of thermal expansion is small,
The generation of thermal stress can be kept small, and the occurrence of cracks and peeling can be prevented. However, as described above, in the high filling region of 60 vol% or more, the viscosity becomes extremely high, so that it is not suitable for the casting operation. The composition suitable for the actual casting is 400 parts by weight of the composition A as shown in Table 1 and a filling amount of about 50 vol% by volume.

Therefore, as shown in FIG. 2, the surface of the vacuum valve 2 is coated with a resin D layer 3 of composition D, and then coated with a resin C layer 4 and a resin B layer 5 of compositions C and B, respectively. Brush coating, dip, etc. are used for coating. These resins having compositions B, C, and D have high viscosity and are not suitable for casting, but are uncured and have fluidity, so that they can be coated on the slightly preheated surface of the vacuum valve 2. In this state, as shown in FIG. 3, the vacuum valve 2 is set in the mold 8, and a resin A7, which is a normal casting material having the composition A, is injected. Since the curing temperature is usually 80 to 150 ° C., each of the coated resin D layer 3, resin C layer 4, and resin B layer 5 melts and the interface disappears. Since the resin of each layer 3, 4 and 5 has the same composition, as shown in FIG.
The gradient layer 6 in which the filling amount of the silica powder changes stepwise toward the layer 7 is formed. The gradient layer 6 has a so-called gradient function in which the coefficient of thermal expansion changes from the vacuum valve 2 to the resin A layer 7 which is a standard casting material, and has a residual stress and a thermal stress caused by a difference in coefficient of thermal expansion. Can be reduced.

The mold valve 1 having the structure shown in FIG. 1 was cast and manufactured by setting the primary curing at 80 ° C. for 15 hours and the secondary curing at 130 ° C. for 15 hours. In addition to this inclined resin mold valve, for comparison, a mold valve of a two-stage molding method using a flexible epoxy resin having a structure of FIG. 7 as a cushion layer, and was directly molded only with a standard casting resin A. A mold valve was manufactured.

Next, the reliability of each of the obtained molded valves was evaluated. As a reliability evaluation method, 0
The liquid phase heat cycle test at 1 ° C. for 1 hour and at 100 ° C. for 1 hour was repeated 10 times, and it was visually confirmed whether or not cracks occurred in the resin mold valve. As a result, cracks were observed on the resin surface after one cycle of the mold valve to which the conventional direct molding method was applied. However, in the case of the mold valve to which the two-stage molding method was applied and the inclined resin mold valve of the present embodiment, there was no particular abnormality even after the completion of 10 cycles, and no crack was observed.

Further, a partial discharge test was performed on the mold valve to which the two-stage molding method was applied after the completion of the liquid phase heat cycle test and the inclined resin mold valve of the present embodiment.
In this test, an alternating current was applied with the discharge charge amount at the start of corona generation being 1 cp. As a result, the mold valve to which the two-stage molding method was applied and the inclined resin mold valve of the present embodiment did not generate corona discharge even when an AC voltage of 50 kV was applied, and maintained the initial corona resistance. . In this case, the mold valve to which the two-stage molding method is applied is manufactured by strictly controlling the casting process, and the inclined resin mold valve of the present embodiment is more excellent in terms of work efficiency.

Next, in order to investigate the crack resistance of the same composition, five oliphant thermal shock washers 9 made of mild steel in accordance with IEC pd 455-2 shown in FIG.
A thermal shock test was performed under the conditions shown in Table 3. Since the coefficient of thermal expansion of mild steel is 11 × 10 ⁻⁶ / ° C., resin C and resin B shown in Table 2 are used.
After coating washer 9 with standard resin A
In this example, the inclined resin molded part of the present embodiment cast and the conventional resin molded part directly molded only with the resin A were manufactured.

The test sample is subjected to a cooling test at a predetermined temperature for a predetermined time. The temperature range gradually increases as the test progresses. The low temperature is obtained in a cooling tank containing ethanol cooled to a desired temperature with dry ice, and the high temperature is obtained by standing at room temperature or by a heating furnace. In the judgment, after taking out from the low temperature side, the presence or absence of a crack is visually observed. Table 4 shows the results.

As can be seen from Table 4, cracks were confirmed to occur in the conventional resin mold parts in 9 to 11 cycles, whereas no cracks occurred in the inclined resin mold parts in the present embodiment even in 17 cycles. It exhibited excellent thermal shock resistance.
In addition, stable characteristics with little variation were obtained.

If the target object is copper used for a conductor or the like, the coefficient of thermal expansion is 17 × 10 ⁻⁶ / ° C. Casting with a typical resin A is effective in reducing residual stress and thermal stress.

As described above, it has been experimentally proved that the inclined resin molded part of this embodiment is superior in thermal, mechanical and electrical properties and has high reliability as compared with the conventional resin molded part. Was done.

[0028]

[Table 3]

[Table 4] In the above-described embodiment, silica is used as the material of the filling inorganic particles, but at least one of alumina, glass fiber, and dolomite may be used in addition to the silica. Although an epoxy resin is used as the main resin of the thermosetting resin having a different composition and the thermosetting resin for casting, a polyimide resin or an unsaturated polyester resin can also be used.

[0029]

As described above, according to the present invention, without using a two-stage molding method having a flexible cushion layer, the thermal stress at the interface is reduced, and peeling and cracking at the interface are prevented. In addition, it is possible to provide a resin molded component excellent in long-term reliability such as crack resistance and heat cycle resistance and electrical characteristics such as corona resistance, and a method of manufacturing the same.

[0030]

[0031]

[0032]

[0033]

[0034]

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold valve which is an embodiment of a resin mold component according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a view for explaining casting of a thermosetting resin for casting in the method of manufacturing a resin molded part according to the present embodiment.

FIG. 4 is a diagram showing a relationship between a filling amount and a viscosity when an amorphous silica powder is filled in an epoxy resin.

FIG. 5 is a diagram showing a relationship between a filling amount and a coefficient of thermal expansion when an amorphous silica powder is filled in an epoxy resin.

FIG. 6 is a view showing an oliphant thermal shock washer which is an example of an embedded object in the present embodiment.

FIG. 7 is a sectional view showing a mold valve manufactured by a conventional two-stage molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold valve (resin mold part) 2 Vacuum valve (embedding) 3 Resin D layer (thermosetting resin with different composition) 4 Resin C layer (thermosetting resin with different composition) 5 Resin B layer (heat with different composition) Curable resin) 6 Inclined layer 7 Resin A layer (thermosetting resin for casting) 8 Mold

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kimiya Sato 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant (72) Inventor Miwa Jinno 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Plant (72) Inventor Yoshihiko Hirano 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside the Hamakawasaki Plant, Toshiba Corporation (56) References JP-A-63-51647 (JP, A) JP-A-62-62344 (JP) , A) Fully open sho 59-81040 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21 / 56,23 / 31

Claims (6)

(57) [Claims] 1. A implant a method of manufacturing a resin molded component is molded with an electrically insulating thermosetting resin, to the implant, the inorganic particles are filled, the thermal expansion coefficient
A plurality of thermosetting resins with different thermal expansion coefficients
A step of sequentially coating from the casting thermosetting resin comprising the steps of casting, the casting thermosetting resin after casting, the thermosetting
Curing the resin and the thermosetting resin for casting . 2. A resin molded part manufactured by the method for manufacturing a resin molded part according to claim 1, wherein the thermosetting resin is used.
Changing the filling amount of the inorganic particles filled in the conductive resin
Changes the coefficient of thermal expansion of the thermosetting resin.
A resin molded part characterized by being made to work. 3. A resin molded part manufactured by the method for manufacturing a resin molded part according to claim 1, wherein
Changing the particle size of the inorganic particles filled in the curable resin
Changes the coefficient of thermal expansion of the thermosetting resin.
A resin molded part characterized by being made to work. 4. A resin molded part manufactured by the method for manufacturing a resin molded part according to claim 1, wherein the thermosetting resin is used.
Melts the thermosetting resin and eliminates the interface between the thermosetting resins.
To form a gradient layer in which the coefficient of thermal expansion changes continuously.
A resin molded part characterized by comprising: 5. A resin molded part produced by the method for producing a resin molded part according to claim 1, wherein the inorganic particles are made of at least one of silica, alumina, glass fiber, and dolomite. Characterized resin molded parts. 6. A resin molded part manufactured by the method for manufacturing a resin molded part according to claim 1, wherein a main resin of the thermosetting resin and the thermosetting resin for casting is an epoxy resin, a polyimide. A resin molded part characterized by using either a resin or an unsaturated polyester resin.