JP2939221B2 - SF6 Epoxy resin composition for gas insulated equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an epoxy resin composition that can be used as an insulating member in an insulating device filled with SF ₆ gas.

[0002]

2. Description of the Related Art SF ₆ gas is a colorless, odorless, non-toxic and excellent gaseous insulating material. Since it is gaseous, it is difficult to find a complicated structure between components. And for maintaining insulation of the space between the component and the housing wall. SF ₆ gas has excellent insulating properties as compared with insulation by air or nitrogen, and has excellent performance as a medium for extinguishing an AC arc of high voltage and large current. For this reason,
By using this gas, it is possible to reduce the distance between the space for holding the insulation, compact equipment, because it is possible to stable performance, insulation equipment is using the recent SF ₆ gas Used in many fields.

[0003] By the way, in the case of insulating equipment, insulating properties,
Insulating parts made of epoxy resin having excellent dimensional stability and mechanical strength are often used. 2. Description of the Related Art As an epoxy resin insulating component used for ordinary electric equipment in contact with air, a molded product of a reinforced epoxy resin filled with silica powder is generally used. Fillers such as silica powder are used for the purpose of adjusting the linear expansion coefficient of the resin composition, which is important when embedding a metal conductor, and improving mechanical properties.

On the other hand, in an insulating device filled with SF ₆ gas, when an arc is generated in the device, a small amount of moisture existing in the device and oxygen and hydrogen generated at high temperatures are mixed with SF ₆ gas.
Reacts to change to SOF ₄ or SO ₂ F ₂ and then decompose to hydrogen fluoride (HF). Therefore, at present, it is impossible to use a reinforcing filler that reacts with hydrogen fluoride gas in an epoxy resin used in such an environment.

In fact, in glass fiber reinforced epoxy resin and silica powder reinforced epoxy resin, fillers such as glass fiber and silica powder existing on the surface react as follows, for example. Na ₂ O · SiO ₂ + HF → NaF + H ₂ SiF ₆ + H ₂ O SiO ₂ + HF → H ₂ SiF ₆ + H ₂ O

[0006] As a result of the above reaction, the surface resistance of the reinforced epoxy resin containing a filler such as glass fiber or silica powder sharply decreases and loses its function as an insulating material. Such problems have been taken up by the Institute of Electrical Engineers for many years as an issue, and many searches have been made for inorganic fillers having good durability against SF ₆ decomposition gas.
The results are summarized by a technical committee (IEEJ Technical Report (Part II), No. 342, "Effects of Additives and Fillers of Solid Insulating Materials", 1990).

Although several fillers have been proposed which do not react with hydrogen fluoride gas, the only practical one is alumina, and as a reinforcing material for epoxy resin used in SF ₆ gas insulating equipment, At present, alumina powder is used.

[0008]

However, in order to adjust the coefficient of linear expansion by using alumina powder as a reinforcing material, it is necessary to add a large amount, for example, about 40% by weight or more to the total weight of the finished product. There is a problem in that it is hard and brittle compared to an epoxy resin containing silica powder to the same extent, so that it is easily broken.

As a method of reinforcing the brittleness of such an epoxy resin, a method of filling a fibrous filler has been known for a long time. For example, a reinforced resin mixed with short glass fibers is generally widely used. in use. It is considered that such a reinforcing effect can be obtained by the fact that the fiber dispersed in the epoxy resin and bonded to the epoxy resin has high strength and that the load applied locally is dispersed. Therefore, as a method of improving the brittleness when the above alumina powder is used as a reinforcing material, a method using alumina fibers is considered. However, alumina fibers are expensive and are not produced in large quantities so that they can be widely used as general products. Further, since the fiber shape tends to be round, it is extremely difficult to mix with the epoxy resin. For this reason, at present, filling alumina fibers with epoxy resin has not been put to practical use.

An object of the present invention is to exhibit stable electrical insulation in a decomposition gas of SF ₆ , and to have a small coefficient of thermal expansion,
SF ₆ filled with a fibrous filler showing good mechanical properties
An object of the present invention is to provide an epoxy resin composition for a gas insulating device.

[0011]

The present invention SUMMARY OF] is a SF ₆ gas insulated equipment epoxy resin composition characterized in that filled with calcium silicate textiles in epoxy resin as at least part of the stiffener.

In one embodiment according to the present invention, alumina powder may be further filled as a reinforcing material. That is, one embodiment according to the present invention, SF _6, characterized in that filled in an epoxy resin and a calcium silicate textiles and alumina powder as at least part of the stiffener
It is an epoxy resin composition for gas insulation equipment.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors first searched for a fibrous filler that is durable against decomposition gas of SF ₆ , and because of the currently available inorganic compound fibers and currently not processed into fibers, only available in powder, but collected, including compounds that may in the future be developed as fibers, to evaluate durability against decomposition gas of SF _6.

The compounds of interest are silicon oxide, titanium oxide, and a group of boron oxides and are liable to be complex oxides.
A composite oxide composed of a combination with a trivalent metal oxide was selected.

[0015] A curing agent is added to an epoxy resin (for example, trade name "Araldite" manufactured by Ciba-Geigy) commonly used for molding equipment insulation parts, and the above-mentioned powder and fiber are used as fillers to form an epoxy resin and a cured resin. 2 for the total amount of the agent
A sample which was mixed so as to be 0% by weight and molded and hardened into a plate shape was cut into a strip shape, and a measurement sample having surface resistance measurement leads attached to both ends was prepared. The measurement sample was exposed to a desiccator containing a small amount of hydrofluoric acid at the bottom and containing HF gas therein to accelerate and degrade the sample.
The change with time of the surface resistance was measured from the outside, and the durability of SF _{6 to} the decomposition gas was evaluated. Some of the obtained results,
It is shown in Table 1 and FIG. In Table 1 and FIG.
All values of 3 Ω or more are shown as 13 Ω.

[0016]

[Table 1]

As is clear from the results shown in Table 1 and FIG.
It can be seen that the surface resistance of the silica powder decreases with the exposure time, and the durability of the silica powder to the decomposition gas of SF ₆ is inferior to that of the alumina powder. However,
It was found that calcium silicate, which is a composite oxide of silicon oxide and calcium oxide, exhibited excellent durability against SF ₆ decomposition gas . Also, the composite oxide, besides when used alone, showed a similar durability even in any state in which physical or chemically mixed.

The calcium silicate fiber is CaO.SiO ₂
Is a fiber of a composite oxide represented by the general formula (I), and is generally obtained by crushing and classifying rock (wollastonite) produced worldwide. Commercially available products include spherical, columnar (fibrous),
Although there are many low reinforcing performances mixed with lumps, preferred calcium silicate fibers suitable for the present invention are mainly fibrous materials having an average fiber diameter of 0.5 to 5 microns and an average fiber length of 10 to 50 microns. It is a selected product, and as a commercial product, a product name “VISTAL” (manufactured by Otsuka Chemical Co., Ltd.) can be mentioned.

[0019]

The fiber geometry of calcium silicate textiles is not particularly limited, the aspect ratio is 5-100
It is preferred that The amount of the fibrous filler added to the epoxy resin varies depending on the purpose of use, but is preferably about 5 to 50% by weight of the entire epoxy resin composition. 5
If the amount is less than the weight percentage, the effect of improving the coefficient of linear expansion and mechanical properties may not be sufficiently obtained. Conversely, if it exceeds 50% by weight, the filling amount becomes too large, and the fluidity of the epoxy resin composition before curing becomes poor, and the moldability may be reduced. A more preferred amount of the fibrous filler is 15
３０30% by weight.

Further, as described above in the present invention may be used in combination with calcium silicate textiles, and alumina powder.
In this case, the total amount of the alumina powder and the fibrous filler is preferably in the range of 10 to 60% by weight of the entire epoxy resin composition, and the amount of the fibrous filler is based on the total of these fillers. Preferably it is in the range of 10 to 90% by weight.

As described above, the epoxy resin composition of the present invention can be used in the same manner as conventionally used alumina powder,
Exhibit stable electrical insulation in the decomposition gas of SF _6. Further, the coefficient of thermal expansion can be adjusted to be small, and can be used as a substitute for the conventional alumina powder. Further, according to the present invention, the brittleness, which has been regarded as a weak point of the epoxy resin filled with alumina powder, can be improved.

[0023] The calcium silicate textiles can be filled in a resin other than the epoxy resin, it is possible to obtain the same stable electrical insulation, also to reduce the thermal expansion coefficient, to obtain good mechanical properties Is what you can do. For example, it can be applied to an unsaturated polyester resin, an alkyd resin, and an amino resin to obtain a fiber reinforced resin (FRP) having good durability against hydrogen fluoride (HF).

[0024]

The epoxy resin composition of the present invention exhibits, SF ₆
Calcium silicate textiles having excellent durability against HF gas is an exploded gas fills as at least a part of the reinforcing member. Therefore, even in the decomposition gas of SF ₆ ,
Surface resistance (insulation resistance) is hardly reduced, and stable electrical insulation is exhibited. Further, the coefficient of linear expansion can be adjusted with the same or better performance than alumina powder conventionally used as a filler.

Further, since it is a fibrous filler, mechanical properties, particularly brittleness, can be remarkably improved as compared with the conventionally used epoxy resin reinforced with alumina powder. Therefore, a short circuit accident due to vibration and impact destruction can be prevented, and the performance can be stabilized. Furthermore, since the size and thickness of the insulating parts can be reduced, the amount of the insulating material used can be reduced, and as a result, the equipment can be downsized, and not only the economical effect,
This can greatly contribute to streamlining the layout and improving workability.

[0026]

Example 1 Calcium silicate fiber treated with silane coupling ("Vistal", manufactured by Otsuka Chemical Co., Ltd., chemical formula Ca
100 g of SiO ₃ , an average fiber diameter of 3 μm, and an average fiber length of 23 μm were uniformly mixed with 220 g of an epoxy resin (trade name “CY225” manufactured by Ciba-Geigy) heated to 60 ° C., and then heated to 60 ° C. 180 g of a curing agent (trade name “HY225” manufactured by Ciba Geigy) is added and mixed, and the pressure is reduced to 5 mmHg by a vacuum defoamer.
The mixture was stirred and defoamed for 3 hours. The mixed uncured resin mixture was mixed with a 150 mm × 160 mm 3 mm thick and 4 mm
In order to form a plate having a thickness of 30 mm and a block having a thickness of 15 mm of 130 mm × 50 mm, the resin mixture is cast in a mold previously heated to 100 ° C., and further placed in the defoaming device for 2 hours, followed by vacuum degassing. 5 hours at 80 ° C., an additional 13
Curing was performed in two stages in an air-circulating thermostat at 0 ° C. for 10 hours. After turning off the power of the thermostat and leaving it to cool for 5 hours, the molded product was taken out of the mold.

From the plates and blocks obtained as described above, samples for measuring mechanical properties and electrical properties were cut out, and these properties were measured in accordance with JIS K6911. The time-dependent change in the insulation resistance in the HF gas is the same as the time-dependent change in the surface resistance of the epoxy resin filled with the various fillers described above, by exposing the measurement sample in a desiccator containing hydrofluoric acid. The measurement was performed by measuring the surface resistance. 10mm as sample for measurement
(Width), 50mm (length), 3mm (thickness) using a strip-shaped sample, a hole of 3mm in the diameter of each sample 10mm from the end, and the portion up to 15mm from both ends with conductive paint After coating and drying, insulated lead wires having terminals fixed to the holes at both ends were attached to form measurement terminals. The measurement was performed using a 1000 V insulation resistance measuring instrument. The upper limit of the measurement was 10 ¹³ Ω. Table 2 shows the measurement results.

[0028]

Comparative Example 1 The procedure of Example 1 was repeated except that the calcium silicate used in Example 1 was replaced with silane-coupled alumina powder (trade name "Nissorundum LA # 1200", manufactured by Taihei Corundum Co., Ltd.). A measurement sample was prepared in the same manner as in Example 1,
Mechanical and electrical properties were measured. Table 2 shows the measurement results.

COMPARATIVE EXAMPLE 2 The procedure of Example 1 was repeated, except that the calcium silicate used in Example 1 was replaced with silane-coupled silica powder ("Crystalite A-1" (trade name, manufactured by Moritaki Co., Ltd.)). Example 1
A measurement sample was prepared in the same manner as described above, and the mechanical and electrical properties were measured. Table 2 shows the measurement results.

[0031]

[Table 2]

The following can be seen from the results in Table 2. (1) Accelerated deterioration test of insulation resistance when exposed to HF gas As is clear from Comparative Example 1, epoxy resin containing alumina powder has little change in insulation resistance with time.
The epoxy resin blended with the silica powder of Comparative Example 2 has significantly reduced insulation resistance. The epoxy resin blended with the calcium silicate fiber of Example 1 has the same performance as the epoxy resin blended with alumina .

[0033] (2) Tensile strength and flexural epoxy resin containing a calcium silicate textiles strength Example 1, the epoxy resin containing the alumina powder of Comparative Example 1 in the tensile strength is almost equal, at break The bending strength is significantly improved as compared with the epoxy resin of Comparative Example 1 and the epoxy resin of Comparative Example 2.

(3) Brittleness (Charpy Impact Value) The epoxy resin of Example 1 has a significantly improved Charpy impact value as compared with the epoxy resins of Comparative Examples 1 and 2. Therefore, the brittleness is greatly improved.

(4) Linear Expansion Coefficient The epoxy resin of Example 1 has a smaller linear expansion coefficient than the epoxy resins of Comparative Examples 1 and 2.

(5) Relative Dielectric Constant The epoxy resin of Example 1 has a relative dielectric constant substantially equal to that of Comparative Examples 1 and 2.

As apparent from the above, an epoxy resin filled with calcium silicate textiles of Example 1 according to the present invention is excellent in resistance to hydrogen fluoride (FH) gas, more conventional alumina It can be seen that the brittleness of the powder-filled epoxy resin is improved, and that it has more mechanical properties than the epoxy resin filled with silica powder.
In addition, it can be seen that the adjustment effect of the linear expansion coefficient of the epoxy resin is higher than that of the conventional alumina powder.

Examples 2-3 and Comparative Example 3 In Examples 2 and 3 , the calcium silicate fiber used in Example 1 and the alumina powder used in Comparative Example 1 were used together in the proportions shown in Table 3. In Comparative Example 3, as shown in Table 3, only the alumina powder used in Comparative Example 1 was used as a filler.

In the same manner as in Example 1, 160 g of an epoxy resin (trade name "CY225") and a curing agent (trade name "H225")
Y225 ”) A total of 200 g (40% by weight of the total) of the fillers shown in Table 3 were added to 130 g of the mixture, and then a measurement sample was prepared in the same manner as in Example 1, and the mechanical and electrical properties were measured. evaluated. Table 4 shows the measurement results. In addition,
In the exposure test in hydrogen fluoride gas, no decrease in insulation resistance was observed in any of the measurement samples after 200 hours.

[0040]

[Table 3]

[0041]

[Table 4]

As is clear from the results in Table 4, the mechanical properties such as bending strength and Charpy impact value are improved by using calcium silicate fiber in combination with alumina powder. Further, the coefficient of linear expansion is even smaller than when alumina powder is used alone. In particular, it can be seen that the bending strength and the Charpy impact value were significantly improved in Example 2 in which the amount of the calcium silicate fiber was substantially the same as that of the alumina powder and was blended at about 20% by weight based on the total amount.

It can be seen that the relative dielectric constant has almost the same performance as Comparative Example 3 using alumina powder alone.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change with time of surface resistance of an epoxy resin filled with various fillers in hydrogen fluoride.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takio Tasaka 463 Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Inside the Otsuka Chemical Co., Ltd. Tokushima Plant (56) References JP-A-5-65365 (JP, A) JP-A-59-232160 (JP, A) JP-A-2-55757 (JP, A) JP-A-7-70412 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 63 / 00-63/10 C08K 7/10 C08K 3/22

Claims (2)

(57) [Claims] 1. A calcium silicate textiles an SF ₆ gas insulated equipment epoxy resin composition characterized in that filled in the epoxy resin as at least part of the stiffener. 2. A calcium silicate textiles and alumina powder, the SF ₆ gas insulation apparatus epoxy resin composition characterized in that filled in the epoxy resin as at least part of the stiffener.