JPS5975604A - Method of producing voltage nonlinear resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] F94 relates to a method for manufacturing a positive nonlinear resistor whose main component is zinc oxide and whose sintered body itself has voltage nonlinear resistance characteristics.

[Technical background and problems of the invention]

Voltage nonlinear resistors are generally called varistors.

Taking advantage of its excellent non-ceramic voltage-current characteristics, it is widely used in lightning arresters and surge absorbers for voltage stabilization and surge absorption. As a representative example,
Zinc oxide palistakaal has been developed in recent years. The main ingredient is zinc oxide, with small amounts of bismuth, antimony,
It is constructed by adding oxides such as cobalt, manganese, chromium, etc., mixing, granulating and molding, then firing at high temperature in air, and attaching electrodes to the sintered body. Its non-linear resistance characteristics are very excellent, and the sintered body consists of a grain boundary layer formed by zinc oxide particles and the surrounding cold material. It is thought that this is caused by the interface between the grain boundary layer and the grain boundary layer.

However, when these voltage nonlinear resistors are industrially mass-produced, not only the nonlinear resistance characteristics deteriorate and the characteristics vary, but also other performance deterioration such as energized life and voltage resistance occur. There is a problem with that.

As one of the reasons! l! ! The influence of impurity contamination during the manufacturing process is considered. For this reason, it goes without saying that the purity of the raw materials themselves and the quality and wear of the manufacturing equipment must be regulated, but large amounts are used in the mixing, pulverizing, granulating, and crystalline resistance layer forming processes during manufacturing. It is also important to regulate the purity of water.

Therefore, N, which affects the nonlinear resistance characteristics during the manufacturing process,
It is not desirable to use tap water that contains impurities such as , K, O, and F4 ions. Furthermore, even if pure water obtained by deionizing tap water with an ion V exchange resin is used, it is also important to regulate the purity of the pure water.

[Purpose of the invention]

The present invention is considered to be one point above m, and by regulating the purity of water used in the entire manufacturing process, stable non-iI! The object of the present invention is to provide a method for manufacturing a voltage nonlinear resistor having a thin resistance.

[Advancement of invention]

The oxidation of the present invention] 1i Lead is the main component, and at least one kind of total flexure oxide is added and mixed, and this mixture is granulated and fired. In the manufacturing method of a voltage non-linear resistor, the purity of the water used in large quantities in each step of the raw material mixing, pulverization, granulation, side coating for forming a high resistance layer, etc. is converted into resistance value. It is considered to be regulated to 10 x 10'Ωα or more.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. Zinc oxide (ZnO) 97.5mr2% and bismuth oxide (Bt)
gos) copal oxide) (Oo2oB) + manganese oxide, antimony oxide (sb2oB) + chromium oxide (O
Weigh out 0.57 Fll-J S powders (20 g), respectively.

Impurities contained in each raw material at this time (1'll + K, o
'a.

etc.) was used at 5 x lo'wt% or less.

Next, this is put into a mixing/pulverizing machine along with a dispersant, lubricant, and binder, and further mixed in a slurry state with 80 to 150 wt% of water injected for 1 to 3 hours. The purity of 10 x 10'Ω or higher, which can be continuously obtained with a mixed bed type automatic water purification device, was used.

The slurry after mixing and pulverization is dried and granulated using a spray dryer, and compression molded to a diameter of 40 to 130 ya and a thickness of 25 mm.

After that, primary firing is performed in air at 500°ε to remove the added dispersant, lubricant, and twinder, and secondary firing is performed at 1050°C, which is necessary to form a high-resistance layer on the side surface. .

After the secondary firing, a pre-prepared slurry-like C: high-resistance product was spray-coated on the side of the fired product, and Shi et al.
Third firing is performed at 00 to 1250°C.

In order to completely form the high resistance layer on the tertiary fired product, reapply the finishing high resistance coating, which has been prepared in the form of a slurry, on the side surface of the fired product and bake at 500 to 600°C. .

At this time, after the secondary firing and after the tertiary firing, the water for the high-resistance forming slurry used is the same as when mixing the raw materials.

Both planes of a zero-order sintered body made of 10×10'°Ωα or more are polished, and aluminum electrodes are attached using Wf material to produce a voltage nonlinear resistor.

In this way, the electrical characteristics of the nonlinear resistor published in gl
'! : 0 shown in Figures 1 to 3 Figure 1 shows the voltage when 100 cm of vlmA (voltage between terminals when 1 mA is applied to the non-linear resistor) is applied to the non-linear resistor in a constant temperature bath at 120°C. Rate of change in leakage current (R/IR
8) is shown. Figure 2 also shows the rate of change in the value of Vl mA (Δv/v1) when a current of 10KA is applied up to 100 times.
mb). In each figure C, the solid line A shows the characteristics of the conventional non-linear resistor, and the dashed line B shows the characteristics of the non-linear resistor according to the present invention.

As is clear from FIG. 1, the nonlinear resistor according to the present invention has significantly improved change in leakage current with respect to am; iit pressure compared to the conventional nonlinear resistor C, and in other words, has improved life characteristics. ing. Further, as is clear from FIG. 2, the nonlinear resistor according to the present invention has significantly improved impact current resistance i characteristics as compared to the conventional nonlinear resistor.

The reason why we were able to obtain improved characteristics in terms of rate of change, variation, etc. shown in Figures 1 and 2 is that the non-linear characteristics were subtly reduced by regulating the purity of the water used during the manufacturing process. It is possible to suppress the influencing Na and KI F4.Oa ions, which seems to be directly linked to the stabilization of the grain boundary layer of zinc oxide.

As for the purity of the water, as a result of investigation, it was found that the effect can be obtained by using water with a purity of 10 x 10'Ω bacteria or higher.

It is V1mA + IR (resistance leakage current) O, which is the initial characteristic during mass production that affects charging characteristics and shock current control characteristics.
This can be said from the fact that the distribution of the variations in (silence = capacity) etc. is as shown in Figure 3.

The E curve in Figure 3 shows the variation distribution when ordinary tap water is used, and the 9 curve shows the purity of water from 1 to 10 x 104Ω3.
．． a[fl+a! is the variation distribution when using a material with a resistance of 10 x 10'Ωm or more.

In Figure 3, for example, if there is a difference of 30 inches or more from the control value, it is determined that the lot is defective.If ordinary tap water is used, the purity of the bacteria will be approximately 30%, 1 to 10 x 10'Ω. Even if water was used, there was a probability of danger of approximately 10%.

According to the present invention, the standard variation is represented by the 0 curve ti1
It is possible to eliminate all defective lots.

Note that the material composition and manufacturing equipment method shown in the examples are not necessarily limited to the above examples as long as they contain zinc oxide as a main component and can provide varistor characteristics.

It goes without saying that the present invention is applicable not only to the mixing, pulverizing, and high-resistance forming steps in the manufacturing process, but also to any process that requires water.

〔Effect of the invention〕

As explained above, according to the present invention C, by regulating the purity of the water used in the manufacturing process 8 of the voltage nonlinear resistor, the energizing life and impact large current characteristics can be improved, resulting in a highly reliable nonlinear resistor. can provide 0

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the relationship between energization time and leakage current of a voltage nonlinear resistor according to Example C of the present invention, FIG. 0 (7317) Agent Patent Attorney is a characteristic diagram showing the variation in characteristics in
Noriyuki Chika (and 1 other person) 1 Fig. 1 1θθ 2θθ CM) Charging time Fig. 2 Inu, OK) Good lgurusu hit〃a Mohammedan (circling Fig. 3)

Claims (1)

[Scope of Claims] 1. Zinc M ide is the main component, at least a metal oxide of the yuzu type or more is added and mixed therein, the mixture is granulated and then fired, and the fired body is coated with a side surface coating. A voltage nonlinear resistor characterized in that the purity of the water used in each step 8+- is 10 x 10'Ωυ or more in terms of resistance value. manufacturing method.