JPS6046003A - Method of producing varistor - 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 The present invention relates to a method for manufacturing a low voltage varistor containing zinc oxide as a main component.

Conventionally, zinc oxide was used as the main component, and Bias3゜MgO,
Cr2O3, Fe2e3, 5b20s, Coo, MnO
.

Zinc oxide-based varistors, which are formed by molding and sintering a composition containing voltage-sensitive oxides such as NiO and conductive oxides (hereinafter referred to as blanks), are widely used because of their excellent nonlinearity.

These zinc oxide-based varistors have a rise voltage of V l mA /wx when the thickness of the sintered body is 1 m, and various types of rise voltage are manufactured. It is determined by the size of the crystal grains. In other words, in order to obtain a low rise voltage, it is necessary to grow large crystal grains, and conversely, in order to obtain a normal rise voltage, it is necessary to suppress the growth of crystal grains and to configure them from small crystal grains. . The above +NW zinc chloride zinc component is BigOs, MgO, 0r2(Js, Fe2(
Js.

5bx05. In the zinc oxide varistor made by adding OoO, MnO, N1 (Jfx, etc.), the crystal grain size is 15 μm.
It is well known that the rising voltage is about 80V and the voltage is about 20 to 40V depending on the composition. In recent years, there has been a growing demand for lower voltages for oxide varistors.
It has become an important issue to obtain a zinc oxide-based varistor containing large crystal grains. As a means of absorbing these large crystal grains, there is a technique proposed in Japanese Patent Publication No. 11203/1983, for example. This #i acid zinc oxide 99.9
-99. After seven months, it is calcined and hydrothermally decomposed to obtain crystal grains of about 70 μm, and the crystal grains are mixed with a powder whose main component is zinc oxide in an amount of 0.1 to 60% by weight, and then sintered. It is. However, in order to obtain crystal grains by hydrothermal decomposition, the zinc oxide is mixed with BaO or S. r
It is necessary to prepare O, add a binder, mold it, calcinate it at a high temperature of about 1300°C, crush it, and then hydrothermolyze it, which has the drawback of requiring a very large number of steps. Ma'n:. Large crystal grains cannot be obtained unless the calcination temperature after molding is high; for example, to obtain crystal grains with a size of 70 μm,
It requires a high calcination temperature of 300' (!), and there are technical and cost problems such as temperature control and the selection of materials for the sintering furnace. If the calcination temperature is high to obtain the crystal grains, the growth of the crystal grains themselves will progress and the activity change will be small. Since the sintering temperature at which the sintered body is obtained and the calcination temperature are close to each other, the growth of crystal grains approaches its limit, and therefore, during the sintering process at which the sintered body is obtained, the crystal grains do not grow much and are sintered. Even after this process, there was a drawback that only crystal grains with a size not much different from those obtained by the hydrothermal decomposition could be obtained.

The present invention was made in view of the above points, and consists of particles obtained by granulating zinc oxide and titanium oxide into powder particles containing zinc oxide as the main component and at least bismuth oxide added thereto. By adding and mixing the particles and sintering, the particles are dispersed and located inside the sintered body, and crystal grains are grown using these as nuclei. The purpose is to reduce the voltage of the varistor by arranging the grains. The details of the present invention will be explained below with reference to Examples.

Example 1 Zinc oxide powder was mixed with 0003 mol%, 0.01 mol%, and O'. 03 morchi.

0, 1 mole. 0.3 molti. 1.0 molti. 7 types of zinc oxide + titanium oxide mixed with 3.0 molar addition.

A mixed powder is obtained, and a binder and water are added and mixed. When this is put into a spray dryer and granulated, spherical particles in which the water added to the mixed powder has evaporated can be obtained. These spherical particles have a particle size of about 3 to 200 μm, but there are many particles of 60 to 120 μm, and very few particles of about 20 μm. The seven types of particles of zinc oxide + f17 oxide were sorted by Th'f, and the particles of zinc oxide powdered titanium with an average particle size of 100 lt m were selected. 94.5 mol% of zinc oxide + 3 mol% of Mg0 + 0.5 mol% of Hi*Os + 1.0 mol% of Oo0 + MnO o. 5 mol g + NiO o. 5 mol qb, t'L 0.1% by weight and 0.3 mol qb, respectively, based on the main composition.

10 heavy %l 3 0i1-ii%, 6 0W weight%
After addition and mixing and molding, l 100 to l 4
Figure 1 shows the rise voltage of a sintered body sintered for 1 to 8 hours at a temperature of 0 0' (!) in relation to the addition of titanium oxide to zinc oxide.
Figure 2 shows the f-line constant α. In both cases, when the amount of lead oxide + titanium oxide ly particles added to the main composition of the curve attvd is in relation to the weight of O01, the curve +B + B0.
31i quantity Q, curve +0+1dlOfit%, curve (Di
is 30 weight t%, white belt 1 yuzu is 60 weight %.

Figure 3 is a curve diagram showing the relationship between the amount of these particles added to the main group e and the rise voltage using zinc oxide titanium oxide particles with an average particle size of 1100 tt, and Figure 4 is a curve diagram showing the relationship between the amount of these particles added to the main group e and the rise voltage. It is a curve diagram showing the relationship between the amount and the non-linear coefficient.
Mol mol φ combination, curve j (Utd O, 01 mol %, curve @
[1 dO, lmol/l/%, curve I11 is 1.0 mol%
, shows the case where Wd+J+ke is 3.0 mole φ. Furthermore, Fig. 5 Ic shows that titanium oxide is compared to zinc oxide.
ko, white group showing the relationship between the size of zinc oxide + titanium oxide particles and the rise voltage when 7 particles of lead oxide + titanium oxide added by 1 mol were added at 10% by weight to the main group Fli. 11): and the 2π6 diagram is a curve diagram showing the relationship between particle size and nonlinear coefficient. As is clear from this result, the amount of f3''y added to Fi zinc oxide at the rising voltage in Figure 1 is good if it is less than 0.01 mol, except for the curve diagram, but at the rising voltage in Figure 2, it is better to In the 16th line VK, the curved report (except for one) shows that the addition amount of titanium oxide is good at 1.0 mol φ, and that it decreases rapidly when it exceeds this. From the results in Figure 2 and Figure 2, the value of titanium oxide added to lead oxide is 0.01 to 1.0.
The molar φ is good, and the amount of the IE lead oxide titanium decaoxide particles added to the main composition is preferably 0.3 to 30 folds. Also, in Figures 3 and 4, 111 lead oxide-titanium oxide.
1. 'l Nitake quality is inferior, and the song I in Figure 4? 3a
+・■1 indicates that the non-straight IJ mooring is inferior. In Fig. 3, the amount of added zinc oxide and titanium oxide particles relative to the main composition is 0.3 times Il: +r, n.
Figure 4 shows that the F130i1 is good up to an excellent level, but beyond this point it rapidly deteriorates. Therefore, the amount of titanium oxide to be added to zinc oxide is 0.01 to 1.0 mole φ, since the zinc oxide + titanium oxide particles relative to the main composition have shown good results. Therefore, this range shows exactly the same results as in FIGS. 1 and 2.

Furthermore, the relationship between the particle diameter of zinc oxide + titanium oxide, the rise voltage, and the nonlinear coefficient is shown in FIGS. 5 and 6.

Note that titanium oxide t added to sample Vi zinc oxide was 0.
A 1 molar color was obtained using particles in which 1 mol [d%] of zinc oxide and titanium decaoxide were added to and mixed with the main composition having the same composition as in the above example. Figure 5j? In Fig. 6, the same amount as in the 11th embodiment is applied to the conventional main composition.
[ljm,! = Acid ratio f17 Powder is added, these are mixed and IC sintered together at a temperature of 1100 to 1400'O for 1 to 8 hours. The granulation process of zinc oxide deca titanium oxide is omitted. . According to this, when the average particle size of the zinc oxide + titanium oxide particles granulated with Spray Dry-Y is 10 μm, the nonlinear coefficient is unchanged from the conventional one, and the rise voltage V l mA /vs is 43 μm compared to the conventional one.
A very low voltage varistor that drops from V to 33V to 14F
It is clear that the rise voltage decreases rapidly as the average particle size increases. However, the nonlinear coefficient starts to decrease rapidly when the average particle size exceeds 100 μm, compared to the conventional 28, and reaches 22 at 200 μm, which is a usable value, but 30011I! At 1, it drops further to 8, a value that is not usable.

From the above, it can be determined that the particle diameter Filo to 2001 tm when granulating lead oxide + titanium oxide is an appropriate range.

Based on this result, titanium oxide was added in an amount of 0.01 to 1.0 mol to the lead oxide powder, and -C was granulated with an average particle size of lO~2.
00 μm of Ill lead oxide + titanium oxide particles were obtained, and these were mixed with 111j lead oxide + Mg 13i203 + Co (J
0.3 to 30 for the main composition consisting of +MnO+NiU
By adding 7f#% to form mixed particles and sintering them together, a low voltage varistor with excellent characteristics such as rise voltage and nonlinear coefficient can be obtained.Example 2 In Example 1, oxidation was used as the main composition. Three lead ten MgO ten l3
tlo3 +OoU+MnO+N1(J to e was described above, but in this Example 2, a case will be described in which VCS b 20 s and (3r 20 !S are added to make it the main composition. S b 203 and Cr2O3 are Sb g (J3 and Varistors whose main component is zinc oxide containing Crt(J3i) cannot be expected to grow crystal grains of zinc oxide and the crystals become small, so they are used for relatively high voltage applications and are unsuitable for low voltage applications. First, chili oxide powder was added to zinc oxide powder (1,003 mol%, 0.01 mole).

0.03 mole, 0.1 mole, 0.3 mole, 3.0
Add molar ratio and mix and granulate with spray dryer L7'tf
1 of zinc oxide + titanium oxide particles were obtained, and in the same manner as in Example 1, spherical particles of lead oxide + titanium oxide with an average particle size of 100 μm were obtained. These particles are made of zinc oxide 94 mol%
+ M g 03 mol% → -Bi2030I mol% + O
OU 1.0 mo#%-1-Mn00.5 mole ratio+Ni0
0.5 molar ratio +5b20a O,3 molar ratio +0120s
0.1% by weight based on the main composition consisting of 0.2 molar ratio
, 0.3 weight cutter, 10 weight cutter, 30 weight cutter, and 60 weight cutter are respectively added and mixed and molded.
l 400'C! The rise voltage when sintered at a temperature of 1 to 8 hours is shown in FIG. 1 in relation to the addition of titanium oxide to 111j lead oxide, and also in the non-1'i line coefficient II diagram. In both curves, when the amount of lead decathoxide particles added to the main composition of curve IKIFi is 0.1% by weight, the peak of the curve is 0.3% by weight, and the curve IM is 10% by weight.
N shows a 300% by weight curve (O = 600% by weight).

Furthermore, Fig. 9 shows a curve diagram showing the relationship between the amount of addition of this particle and the rise voltage for the Ail main composition using zinc oxide 1 + titanium oxide particles with an average particle size of 100 μm, and Fig. 10 VC shows the relationship between the amount of addition of this particle and the rise voltage of this particle. A curve diagram showing the relationship between the amount added and the nonlinear coefficient is shown.

Curve IP+ is salivary lead oxide + titanium oxide. If the amount of titanium oxide added to zinc oxide in the particles is 0.003 mol, the curve IQI is 0.01 mol, the curve is 0.1 mol, and the curve IS is 1 mol 10 mol. Curve (1) shows the case of 3.0 mol. Set @Figure 11 [HI
The relationship between the size of zinc oxide and titanium oxide particles and the rise voltage when 10% of titanium oxide is added to the main composition of lead decaoxide titanium particles with 0.1 molar addition of titanium oxide and zinc oxide. The flX1g diagram is a curve diagram showing the relationship between particle size and nonlinear coefficient. Note that each sintering was performed at a temperature of 1100 to 1400'O for 1 to 8 hours.

As is clear from these results, the rise voltages and nonlinear coefficients shown in FIGS. 7 and 8 are similar to those in FIGS. 1 and 2 of Example 1. Although it is not written by II, the amount of titanium oxide added to zinc oxide is 0.01 to 1, except for song #■ Okobi 10.
．． A range of 0 molar coefficient is good.

Therefore, from the results in Figures 7 and 8, it is clear that the amount of titanium oxide added to zinc oxide is between 0.01 and 1.0 mol, and that the titanium oxide particles are added to the main composition. A good range of the amount is 0.3 to 30% by weight. It can also be confirmed from FIGS. 9 and 10 that this range shows good results in terms of characteristics. As in Example 1, the relationship between the oxide curve, the size of the titanium lead decathoxide particles, the rise voltage, and the nonlinear coefficient is shown in FIGS. 11 and 1 and 12. For the sample, the amount of titanium oxide added to zinc oxide was 0.
A sample was used in which 10 tons of zinc chloride and titanium oxide particles were added to the main composition at a ratio of 1 mole. In the figure, "conventional" refers to JJL composite which is made by directly adding and mixing the same first generation zinc oxide and titanium oxide powder as in the example to the main composition and sintering it.
I am very careful. As a result, although the absolute values of both the rise voltage and the nonlinear coefficient are large, they show the same tendency of characteristics as in Example 1. The average particle size of the 4I oxide + titanium oxide particles is in the range of 10 to 200 μn. can do.

In this Example 2, 0.01 to 1.0 to zinc oxide powder
Adding 7% of malti oxide and granulating it to an average particle size of lO~
Seven particles of titanium decaoxide with a diameter of 200 μm were obtained, and these were combined into zinc oxide + MgO + Bi*Os + OoO + MnO + NiU + 5b20! I
By adding and mixing 0.3 to 30% by weight to the main composition consisting of +Or sO+ and sintering them together, a varistor with excellent rise voltage and nonlinear coefficient characteristics can be obtained. Therefore, the main composition containing 5bsO:+ and 0rpOs, which inhibit the grain growth of zinc oxide, contains lead oxide+.
Even when titanium oxide particles are added, the crystal grain #''ii grows, which has the effect of lowering the voltage.

As described above, in the VC process of the present invention, after granulating the powder of zinc oxide and titanium oxide, the resulting powder is added to the main composition mainly consisting of zinc oxide, mixed, molded, and sintered to form a varistor. This varistor has a large crystal grain size, so it has the characteristic of reducing the rise voltage without reducing the nonlinear coefficient.
MnO, NiU.

3t) Although the case where 2Qs and Orgys are added has been described, other metal oxides such as 5iOz and OuO
.

A1z03. HaO, OaO, SrO, PbU, 5n0
2゜kgwo, medium size Isen'1r02. La2O3,Pr
6 (Jll.

Fears, BaO3, etc. may be added, but the material is not limited to these as long as it becomes an oxide at high temperatures in air. However, the present invention is made of a sintered body containing lead oxide, bismuth oxide, VC oxide, 1ti lead, and titanium oxide particles as the main components, and can obtain the effect of lowering the voltage of the varistor 1. , the M g O, Oo
Which gold PA oxide has the effect of improving the characteristics as a varistor, but it is not an essential requirement from the four points of the present invention, which is to reduce the voltage.

[Brief explanation of drawings]

The drawings are all curve diagrams showing the characteristics of the present invention, reference examples, and conventional examples. Figure 1 shows the relationship between the amount of titanium oxide added to zinc oxide and the rise voltage, and Figure 2 shows the relationship between the amount of titanium oxide added and the non-linear relationship. Figure 3 shows the relationship between the addition of zinc oxide + titanium oxide particles to the main composition and the rise voltage.1. Figure 4 shows the relationship between the added amount of ITj lead titanium decaoxide particles and the non-linear coefficient, Figure 5 shows the relationship between the average particle diameter of titanium decaoxide particles and the rise voltage. Similarly, the relationship between the average particle diameter of zinc oxide + titanium oxide particles and the nonlinear coefficient, @Figure 7 to Figure 12 are curve diagrams showing the characteristics according to other examples. Figure 8 shows the relationship between the amount of titanium oxide added and the nonlinear coefficient, and Figure 9 shows the relationship between the amount of zinc oxide + titanium oxide particles added and the rise voltage for the main composition. Similarly, Figure 10 shows the relationship between the added amount of titanium oxide particles in zinc oxide soil and the nonlinear coefficient, and Figure 11 shows the average particle diameter and rise 9 of titanium oxide particles in zinc oxide soil.
Figure 12 also shows the relationship between zinc oxide and titanium oxide. FIG. 6 is a curve 6 diagram showing the relationship between the average particle diameter of particles and a nonlinear coefficient. Patent application - Marukon Electronics Co., Ltd. White Shi4hif? >Key≦,,,1 (Moshi 7o) Fig. 4 flJ a114 hi condolence story - F Baseng 4 hit 9! - Or bow the cold method CWtμノ ■ If Showa 4 Ni'a 41) t ■ Pre seven tens of Gun gong q1 9% cliff (,/J layer 9 薇Ihi term H1 nshi tahiketa) leaf Vertical piece (μm) Fig. 8

Claims (1)

[Claims] A step of mixing tl+zinc oxide powder and titanium oxide powder and then granulating them to obtain zinc oxide+titanium oxide particles, a step of sorting the particles by average particle size, and a step of sorting the particles in the step. 1. A method for manufacturing a varistor, comprising a step of adding and mixing particles to a main composition containing at least zinc oxide and bismuth oxide to obtain a mixture of particles, and a step of shaping and sintering the mixed particles after the step. (2) The method for manufacturing a varistor according to claim (1), characterized in that the granulation process is carried out using a spray dryer. (3) The amount of titanium oxide added to zinc oxide is 0.0
The method for manufacturing a varistor according to claim 1 or claim 2, wherein the content is 1 to 1.0 mol%. (4) The average particle size of zinc oxide + titanium oxide particles is 10-2
Claim 1 (1) characterized in that the diameter is 00 μm.
) to (3). (5) The amount of zinc oxide + titanium oxide particles added to the main composition is 0.3. -30% by weight of any one of claims (1) to (4).
A method of manufacturing the described barista.