JPH0812812B2 - Method of manufacturing voltage non-linear resistor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a voltage nonlinear resistor containing zinc oxide as a main component.

(Prior art) Bi ₂ O ₃ , Sb ₂ O ₃ , SiO ₂ , mainly containing zinc oxide,
It is widely known that a resistor containing a small amount of additives such as CO ₃ O ₄ and MnO ₂ exhibits excellent voltage non-linearity, and this property is used for a lightning arrester and the like.

In this voltage non-linear resistor, when lightning surge current is applied to the element, discharge may occur mainly along the element side surface, so-called creeping discharge, and the element may be destroyed. It is common to provide a lateral high resistance layer made of a compound or a Bi—Sb—Si—Zn-based compound.

(Problems to be solved by the invention) In these voltage non-linear resistors, there has been an attempt to increase the varistor voltage (V _1mA ) of resistors to reduce the size of devices such as arresters, and to lower the firing temperature. It is generally known that the varistor voltage increases when the voltage is changed. However, when the firing temperature is lowered, there is a problem that the adhesion between the side surface high resistance layer and the resistor body is lowered, and the lightning surge withstand capability is lowered.

In order to improve this point, the applicant of the present invention has disclosed Japanese Patent Application Laid-Open No. 63-136603.
In the publication, a ZnO-S having a predetermined composition is used as the side surface high resistance layer.
with use of _{iO 2 -Bi 2 O 3 -Sb 2} O 3 based mixture, by increasing the a SiO ₂ 7 to 11 mol% in body, varistor voltage by lowering the sintering temperature is 400V / mm or more It is disclosed that a voltage non-linear resistor having good characteristics can be obtained.

However, in the technique described in JP-A-63-136603 described above, since it is necessary to increase the amount of SiO ₂ added in the element body, it is difficult to uniformly disperse the zinc silicate phase in the element, and the switching surge resistance etc. There was a problem of decrease. In addition, since crystalline SiO ₂ etc. was used as it was without crushing as a Si component addition to the side surface high resistance layer, the particle size was coarse and the zinc silicate phase, which had the effect of becoming uniform, became non-uniform. There was a case to generate. In such a case, the lightning surge withstand capability will not be improved and its variation will be large, and the side surface high resistance layer will also absorb moisture, and it will not be possible to obtain a voltage nonlinear resistor with good characteristics such as lack of long-term reliability. was there.

The object of the present invention is to solve the above-mentioned problems and to obtain good electrical characteristics such as lightning surge resistance even at a high varistor voltage, and to improve the hygroscopicity of the side surface high resistance layer. The present invention is intended to provide a manufacturing method of.

(Means for Solving the Problems) A method of manufacturing a voltage non-linear resistor according to the present invention comprises a zinc oxide as a main component, a bismuth component, an antimony component, and a side surface of a voltage non-linear resistor body containing a silicon component. , At least amorphous silica, antimony compound, bismuth compound,
The zinc compound is 65 to 91 mol% when the amorphous silica is converted to SiO ₂ , the antimony compound is ₂ to 15 mol% when converted to Sb ₂ O ₃ , and the bismuth compound is converted to Bi ₂ O ₃ to 7%. ~ 20 mol%,
Converting zinc compounds to ZnO ZnO / (SiO ₂ + Sb ₂ O ₃ + Bi
₂ O ₃ ) = 0.1 to 1.0 is applied to the mixture for insulation coating, and the side surface of the fired body contains zinc silicate (Zn ₂ SiO ₄ ) and spinel (Zn ₇ Sb ₂ O ₁₂ ) with high resistance. It is characterized by forming a layer.

(Operation) In the configuration described above, as well as the composition constituting the side surface high-resistivity layer with a predetermined amount of _{SiO 2 -Sb 2 O 3 -Bi 2} O 3 quaternary of -ZnO, amorphous as SiO ₂ source material Silica converted to SiO ₂ is 65 to 91 mol%, preferably 73 to 86 mol%, and antimony compound is converted to Sb ₂ O ₃ to ₂ to 15 mol%, preferably 4 to 10 mol%.
Mol%, bismuth compound converted to Bi ₂ O ₃ 7 to 20 mol%, preferably 10 to 17 mol%, zinc compound converted to ZnO ZnO / (SiO ₂ + Sb ₂ O ₃ + Bi ₂ O ₃ ) By mixing so as to be 0.1 to 1.0 (molar ratio), preferably 0.2 to 0.7, good electrical characteristics such as lightning surge resistance can be obtained even at a high varistor voltage, and the hygroscopicity of the side surface high resistance layer can be improved. I also found that it can be improved.

Here, the amorphous silica is converted to SiO ₂ of 65 to 91 mol%, the antimony compound is converted to Sb ₂ O ₃ of ₂ to 15 mol%, and the bismuth compound is converted to Bi ₂ O ₃ of 7 to 20 mol%,
Converting zinc compounds to ZnO ZnO / (SiO ₂ + Sb ₂ O ₃ + Bi
₂ O ₃ ) is numerically limited to a composition of 0.1 to 1.0 (molar ratio), because when any composition is out of this range, electrical characteristics such as lightning surge withstand capability will become apparent as will be apparent from Examples described later. This is because the characteristics deteriorate.

Here, the amorphous silica reacts with the zinc compound by firing to form zinc silicate. Further, the antimony compound reacts with the zinc compound to generate spinel. It is considered that these zinc silicates and spinels play an important role in improving the adhesion between the lateral high-resistance layer and the resistor body and the lightning surge withstand characteristics of the device. The zinc compound needs to react with the amorphous silica or the antimony compound by firing, and it is not preferable that the zinc compound remains as a zinc compound after firing. Further, it is preferable that zinc silicate is continuously produced.
Further, it is considered that the bismuth compound smoothly promotes the above reaction as a flux and also diffuses into the resistor body, and plays an important role in improving the characteristics such as switching surge resistance.

Also, the use of amorphous silica as the SiO ₂ source material provides a uniform and good zinc silicate phase in the side surface high-resistance layer, which improves the lightning surge resistance and reduces its variation, This is because the hygroscopicity of the resistance layer is also improved.

The method for producing the amorphous silica to be used is not particularly limited, but if one obtained from the metathesis reaction of sodium silicate or one obtained by the thermal decomposition of silicon tetrachloride is used, various characteristics can be obtained. Is preferable, which is preferable. The purity of SiO ₂ is preferably 95% or more.

Furthermore, the average particle size of the amorphous silica, antimony compound, bismuth compound, and zinc compound used is 10 μm.
The following is preferred.

Here, as the composition of the insulating coating mixture other than amorphous silica, an antimony compound, a bismuth compound, and a zinc compound are specified, but each compound is 1000 ° C. or less, preferably 80
Any substance that can be converted into an oxide at 0 ° C or lower may be used. Specific examples thereof include carbonates, nitrates and hydroxides, with oxides being most preferred.

Further, the composition of the voltage non-linear resistor element body is not limited, and any conventionally known composition can be used, but in particular, 0.1 to 7 mol% of the silicon component in terms of SiO ₂ is more preferable. It is preferably 0.5 to 4 mol%. The silicon component precipitates in the grain boundary phase together with the bismuth component and has the effect of improving the varistor voltage (V _1mA ). If it is less than 0.1 mol%, the grain growth suppressing effect is insufficient and the varistor voltage may not be improved, and the electric life and limit voltage characteristics may deteriorate. If it exceeds 7 mol%, the lightning surge withstand capability deteriorates and lightning surge resistance may deteriorate. This is because the varistor voltage after applying the surge may decrease. Amorphous is more preferable because the reaction proceeds smoothly.

(Example) In order to obtain a voltage nonlinear resistor containing zinc oxide as a main component, first, a zinc oxide raw material adjusted to a predetermined particle size and bismuth oxide, cobalt oxide, manganese oxide, antimony oxide adjusted to a predetermined particle size, A predetermined amount of an additive made of chromium oxide, silicon oxide, nickel oxide, silver oxide, boron oxide or the like is mixed. Silver nitrate or boric acid may be used instead of silver oxide or boron oxide. Bismuth borosilicate glass containing silver is preferably used. At this time, a predetermined amount of a polyvinyl alcohol aqueous solution and a predetermined amount of an aluminum nitrate solution as an aluminum oxide source are added to these raw material powders, preferably mixed by a disper mill, and then granulated preferably by a spray dryer. Get the granules.
After granulation, it is molded into a predetermined shape under a molding pressure of 800 to 1000 kg / cm ² . 800 ~ at the temperature rising / falling speed of 50 ~ 70 ℃ / hr
Preliminary calcination is performed under the condition of 1000 ° C holding time of 1 to 5 hours.

Before calcination, the molded body should be heated / cooled at a rate of 10-100 ° C / hr.
It is preferable to keep the binder at 400 to 600 ° C. for 1 to 10 hours to scatter and remove the binder. Here, the element body of the present invention refers to a molded body, a degreased body obtained by heat-treating the molded body under the above conditions, or a calcined body.

Next, a side surface high resistance layer is formed on the side surface of the element body. In the present invention, the bismuth compound is 7 to 20 mol% in terms of Bi ₂ O ₃ , the antimony compound is ₂ to 15 mol% in terms of Sb ₂ O ₃ , and the amorphous silica is 65 in terms of SiO _2. ~ 91 mol%, ZnO / SiO ₂ + Sb ₂ O ₃ + Bi ₂ O ₃ ) = 0.1 in terms of zinc compound converted to ZnO
Ethyl cellulose as an organic binder in a predetermined amount of ~ 1.0,
The mixture paste for the side surface high resistance layer to which butyl carbitol, n-butyl acetate, etc. are added is applied to the side surface of the element body to a thickness of 60 to 300 μm. At this time, in the present invention, the average particle size is 10
Amorphous silica of less than μm is used. Next, this is heated / cooled at a rate of 40-60 ° C / hr, 1000-1250 ° C, preferably 1050-119.
The main firing is performed at 0 ° C. for 3 to 7 hours. In addition, a glass paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate or the like to a glass powder as an organic binder is applied to the above-mentioned lateral high-resistance layer to a thickness of 100 to 300 μm,
It is preferable to form a glass layer by heat-treating in air at a temperature rising / falling rate of 100 to 200 ° C./hr and a holding time of 400 to 1000 ° C. for 0.5 to 2 hours.

After that, both end surfaces of the obtained voltage nonlinear resistor are
Polishing is carried out with water, preferably oil, with an abrasive corresponding to # 400 to 2000 such as ₂ O ₃ or diamond. Next, after cleaning the polished surface, electrodes are provided on the polished both end surfaces by, for example, aluminum, for example, by thermal spraying to obtain a voltage nonlinear resistor.

Hereinafter, the results of actually measuring various characteristics of the voltage nonlinear resistor within and outside the range of the present invention will be described.

Example In a voltage non-linear resistor having a diameter of 47 mm and a thickness of 20 mm prepared by the method described above, in order to investigate the influence of the composition in the mixture for the lateral high resistance layer, the composition of the element body was Bi ₂ O ₃ 1.0 mol% , Co ₃ O ₄ 0.7 mol%, MnO ₂ 0.5 mol%, Sb ₂ O ₃ 1.0 mol%, Cr ₂ O ₃ 0.5 mol%, NiO 0.5 mol%, Al ₂ O ₃ 0.005 mol%, amorphous SiO ₂ 1.0 mol% and the balance ZnO, and 0.01-0.5 wt% of bismuth borosilicate glass containing silver. The composition of the lateral high resistance layer uses amorphous silica as silicon and the composition shown in Table 1. And Comparative Examples which do not satisfy the scope of the present invention in any of the compositions of the sample No. 1 to 30 within the scope of the present invention in which the varistor voltage is changed by changing the firing temperature and the composition of the side surface high resistance layer. Sample No. 1 ~ 22
Were prepared, and the varistor voltage (V _1mA ), lightning surge resistance, switching surge resistance, and hygroscopicity of the side surface high resistance layer were measured. The results are shown in Table 1.

In Table 1, the lightning surge withstand is shown as the energy withstand, and the energy withstand is a means to relatively evaluate the withstand of resistors having different varistor voltages, and the energy value (current x voltage x application time). Indicate. The switching surge resistance is indicated by x when the current of 400 A, 500 A and 600 A was repeatedly applied 20 times with a current waveform of 2 ms and was broken, and when it was not broken, it was indicated by ◯. The hygroscopicity of the side high-resistance layer, 2 while pressure 200 kg / cm ² the device in the fluorescent flaw detection solution
The moisture absorption state after being immersed for 4 hours was inspected, and those with no bleeding on the side surface high resistance layer were marked with ◯, and those with bleeding were marked with x.

From the results shown in Table 1, the resistors of Sample Nos. 1 to 30 of the present invention having the composition of the high resistance layer within the range of the present invention can obtain good electrical characteristics even with a high varistor voltage, and Comparative sample No. 1 which does not satisfy the present invention in any point
It was found that it showed good electrical characteristics such as lightning surge resistance and good moisture resistance of the lateral high resistance layer, compared with ~ 22.

(Effects of the Invention) As is clear from the above description, according to the method for manufacturing a voltage nonlinear resistor of the present invention, by limiting the composition in the high resistance layer, good electrical characteristics such as lightning surge withstand capability can be obtained. Can be obtained even at a high varistor voltage, and a voltage non-linear resistor that can also improve the hygroscopicity in the side surface high resistance layer can be obtained.

Claims (1)

[Claims] 1. At least amorphous silica, an antimony compound, a bismuth compound, and a zinc compound are provided on the side surface of a voltage nonlinear resistor element body containing zinc oxide as a main component and containing a bismuth component, an antimony component, and a silicon component. Amorphous silica
Converted to SiO ₂ 65-91 mol%, antimony compound Sb ₂ O
₃ to 2 to 15 mol%, bismuth compound to Bi ₂ O ₃ to 7 to 20 mol%, zinc compound to ZnO and ZnO /
(SiO ₂ + Sb ₂ O ₃ + Bi ₂ O ₃ ) = 0.1 to 1.0 is applied to the mixture for insulation coating to form a high resistance layer containing zinc silicate and spinel on the side surface of the fired body. A method of manufacturing a characteristic voltage non-linear resistor.