JPH0815121B2 - Method for producing low voltage non-linear antibody - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a voltage non-linear resistor, and more particularly, to a voltage non-linear resistor suitable for manufacturing a voltage non-linear resistor having good electrical characteristics. The present invention relates to a method for manufacturing a linear resistor.

(Prior Art) Conventionally, in a mixing step in manufacturing a voltage nonlinear resistor, for example, various metals such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, silicon oxide, nickel oxide, and aluminum oxide. Oxide and bismuth borosilicate glass are calcinated as they are or after being calcinated to a predetermined particle size, and these pulverized powders are added to the raw material of zinc oxide, and simply ball mill, vibration mill, emulsifier (for example, Disper mill). ) Or the like to disperse and mix to obtain a raw material powder.

(Problems to be Solved by the Invention) By the way, in the case of a conventional ball mill, a very long time is required for mixing, and in the case of a vibration mill or an emulsifier,
Since the temperature control during mixing has not been sufficiently studied, it was not possible to uniformly disperse and mix each component in the raw material powder, and thus such raw material powder was produced by granulation, molding and firing. It is difficult to improve the electrical characteristics of the voltage non-linear resistor, and there is a disadvantage that the characteristics vary greatly.

The object of the present invention is to solve the above-mentioned conventional problems that occur when mixing various metal oxides and main raw materials in the mixing step, and to obtain good electrical characteristics such as discharge withstand capacity and a certain quality. The present invention proposes a method of manufacturing a voltage non-linear resistor which is advantageous to the above.

(Means for Solving Problems) In the present invention, in the step of adding and mixing various metal oxides that cause voltage nonlinearity as an additive to a raw material containing zinc oxide as a main component, the raw material and the metal Add 0.1 to 2.0 wt% of organic binder to the raw material powder made of oxide, and make the slurry with water content of 30 to 35 wt%.
A method for producing a voltage non-linear resistor characterized by mixing in an emulsifier while forcibly cooling to a temperature of ℃ or less,
As the organic binder added to the raw material powder, polyvinyl alcohol, polyvinylpyrrolidone, ethylene oxide, methyl cellulose, hydroxyethylene cellulose, carboxymethyl cellulose or the like is used.

(Function) The present invention adds an organic binder to these raw material powders when finely pulverized various additives are added to the main raw material of zinc oxide in the above-mentioned constitution to obtain raw material powders for voltage nonlinear resistors. At the same time, adjust the amount of water to a predetermined range to make sludge,
Since this is mixed at a temperature of 40 ° C. or lower, zinc oxide and additives can be mixed uniformly.

The reason for mixing sludge at a temperature of 40 ° C or lower is 40 ° C.
This is because if it exceeds the above range, the mixture will gel during mixing and cannot be mixed uniformly. Especially this temperature is 20-30
It is more preferable to adjust the temperature to ° C.

Moreover, the content is 0.1 to 2.0 with respect to the solid content of the raw material powder.
The reason why it is preferable to be wt% is that polyvinyl alcohol is water-soluble, has a lower viscosity than other binders and is stable, and when granulated powder using polyvinyl alcohol is molded, it has few internal defects. This is because a molded product having a high density can be obtained.

Further, if the content is less than 0.1 wt%, there is no effect, while if it exceeds 2.0 wt%, the electrical characteristics of the voltage nonlinear resistor deteriorate. Therefore, as the organic binder, it is preferable to add polyvinyl alcohol, and the content thereof is preferably within the range of 0.1 to 2.0 wt%.

Hereinafter, a voltage nonlinear resistor containing zinc oxide as a main component,
One example in the case of manufacturing by applying the mixing method of the present invention will be described.

First, a mixture of additives made of bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, silicon oxide, nickel oxide, aluminum oxide and the like adjusted to a predetermined particle size is preferably calcined at 700 to 850 ° C. .

Next, the obtained calcined product is preferably dry-crushed and then finely ground by a wet ball mill. The calcination does not have to be carried out depending on the additive, in which case the additive is directly pulverized by a wet ball mill. The fine pulverization is carried out until the difference in average particle diameter with zinc oxide to be mixed in the next step is 2 μm or less, and more preferably both particles have almost the same average particle diameter.

Next, the zinc oxide powder and a finely pulverized product of the above additives are mixed.

Upon mixing, polyvinyl alcohol as a binder is added to the raw material powder consisting of the zinc oxide powder and the additive in the range of 0.1 to 2.0 wt% with respect to the solid matter of the raw material powder. Then, the water content of this mixture is adjusted to the range of 30 to 35 wt%, and the viscosity is adjusted to 100 cP ± 50. The mixing operation is carried out by using an emulsifier and forcibly cooling the temperature of the slurry to 40 ° C. or lower (preferably 20 to 30 ° C.) and adjusting the temperature for about 80 minutes. Here, as a means for adjusting the temperature, for example, a cooling jacket is provided in the emulsifying machine, cooling water is circulated in this, and the flow rate of the cooling water is controlled by the internal temperature.

Next, the obtained mixed sludge is degassed under reduced pressure, preferably granulated into fine particles with a spray dryer, and then the granulated product is pressure-molded into a predetermined shape under a molding pressure of 800 to 1000 kg / cm ² . 800-1000 at the temperature rising / falling speed of 50-70 ℃ / hr
The binder is scattered and removed by calcination under the conditions of a temperature of 1 to 5 hours. Next, an insulating coating layer is formed on the side surface of the calcined body that has been calcined.

This insulating coating layer is an oxide paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as organic binders to bismuth oxide, antimony oxide, silicon oxide, etc., and calcining this to a thickness of 30 to 100 μm. Apply to the sides of the body. Next, this is heated / cooled at a rate of 40-60 ° C / hr, 1000-1
The main calcination is performed at 300 ° C., preferably 1200 ° C. for 3 to 7 hours.

In addition, a glass paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to glass powder is applied on the above-mentioned insulating coating layer to a thickness of 100 to 200 μm, and the temperature rising / falling rate is 100 to 100 in air. 200 ° C / hr, 400-60
The glass layer is preferably formed by heat treatment under the condition of 0 ° C. holding time of 0.5 to 2 hours. Finally, both end surfaces of the voltage non-linear resistor are polished smoothly and aluminum electrodes are provided by thermal spraying to obtain the voltage non-linear resistor.

(Example) Example-1 A sample to which the mixing method of the present invention is applied in a voltage nonlinear resistor having a diameter of 47 mm and a thickness of 20 mm manufactured by the method described above.
Nos. 1 to 4 and Comparative Examples Nos. 5 and 6 in which either the temperature at the time of mixing or the organic binder were out of the scope of the present invention were prepared, and the defect occurrence rate, voltage nonlinear index, surge withstand breakdown rate (% ) And leakage current ratio were compared and investigated.

The defect occurrence rate is obtained by performing ultrasonic flaw detection on the obtained sample and checking the number of defects having a diameter of 0.5 mm or more, and obtaining the ratio thereof. The voltage nonlinear index α is I = KV ^α
V ₁ mA and V ₁₀₀ based on (I: current, V: voltage, K: proportional constant)
It was calculated from the ratio with μA.

The discharge withstand capability was obtained by repeatedly applying the current of 1000 A and 1200 A 20 times with a current waveform of 2 ms, and then obtaining the number of device breakdowns as the surge withstand breakdown rate. Electricity was applied at 95%, and it was calculated from the current ratio I ₁₀₀ hours / I ₀ hours 100 hours after the application of electricity immediately after the application.

 The results are shown in Table-1.

As can be seen from Table-1, the sample Nos. 1 to 4 obtained by applying the mixing method of the present invention have a much smaller defect occurrence rate than the comparative examples Nos. 5 and 6, and have a high voltage nonlinearity. Of the voltage non-linearity α, the leakage current ratio, as well as good electrical characteristics such as voltage non-linearity, voltage life, and lightning surge withstand capability. It was found that the standard deviation value (σ) was also small, and there was little variation in characteristics.

Example 2 Similarly, in a voltage non-linear resistor having a diameter of 47 mm and a thickness of 20 mm produced by the above-described method, the influence of the content (wt%) of polyvinyl alcohol added during the mixing of the raw material powders on the electrical characteristics is examined. Therefore, in the mixing process, sample Nos. 7 to 12 obtained from raw material powders whose contents were variously changed
Prepared.

Similar to Example 1, these sample Nos. 7 to 12 were examined for the ratio of defect occurrence rate, voltage non-linearity index, surge withstand breakdown rate (%) and leakage current.

 The results are shown in Table-2.

As is clear from Table-2, it was confirmed that all of the samples No. 8 to No. 11 produced by the raw material powder to which the mixing method according to the present invention was applied show good values.

(Effect of the invention) According to the present invention, it is possible to uniformly mix a raw material powder mainly composed of zinc oxide and various additives in a mixing step in a short time.
It is possible to industrially manufacture a voltage non-linear resistor having few defects and having good surge withstand capability and electric life characteristic.

Claims (2)

[Claims] 1. A metal oxide containing, as an additive, various metal oxides that cause voltage non-linearity.
In the mixing step, 0.1 to 2.0 is added to the raw material powder consisting of the raw material and the metal oxide.
Adds wt% organic binder and water content is 30 ~ 35wt
%, And a method for producing a voltage non-linear resistor, characterized in that the slurry is forcibly cooled to a temperature of 40 ° C. or lower and mixed by an emulsifying machine. 2. The method for producing a voltage nonlinear resistor according to claim 1, wherein the organic binder is polyvinyl alcohol.