JPS63201074A - Manufacture of high temperature ptc material - 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 [Industrial Field of Application] The present invention relates to a method for producing high temperature PTC materials. More specifically, the present invention comprises a composition consisting of BaPbO+ alone or containing BaPbO3 as a main component (hereinafter collectively referred to as "BaPbO*-based composition"), which has a high temperature range. positive resistance temperature characteristic (PT
C characteristics).

[Conventional technology]

Conventionally, BaTi0. Alternatively, PTC materials made of BaTiO3-based compositions and various products using such materials are well known. In order to manufacture the glass frit, it has been proposed to mix a glass frit made of BaTiO3 and a component that converts it into a semiconductor with an organic binder and heat-treat the mixture at a temperature below the crystallization temperature. However, such BaTiOt-based PTC materials have the drawback that the Curie point (CP), which is the temperature at which the resistance value rapidly increases, exists in a low temperature range of typically 100 to 120°C. pb for this material
Attempts have been made to shift the Curi point to a higher temperature side by adding oxides, but
00℃ is the limit, and in order to obtain large power,
Although it is desirable that the specific resistance (ρ) be as small as possible, the limit is approximately 1 to 10 Ω·C−.

For example, BaPbO3, I'bO, B
20. .

Solder glass whose main component is ZnO at a weight ratio of 5 to 3
A PTC material characterized by containing 0% of
It is reported in the publication No. 0-59702.

This high temperature PTC material has a value of ρ of 10-4 to 10-IΩ
・The cII is quite low, and the temperature change point of ρ (resistance change point; that is, one Curie point CP) is about 750.
℃, so it is very useful. Other BaPb
O3-based PTC materials are also attracting attention as high-temperature PTC materials because they similarly have a low ρ and have a CP in a high-temperature range.

[Problem that the invention seeks to solve]

Although the 13aPbO, based PTC material has the important advantages mentioned above, it also has some manufacturing problems. As is well known, it is difficult to form solid solutions in BaPbO3-based materials, so when manufacturing them using conventional manufacturing methods, such as the solid phase method, it is necessary to perform calcination two or more times during the process. During such a calcination process, there is a problem in that the composition of the resulting material varies due to the scattering of PbO. In addition, since such materials are difficult to sinter, even when they are made into a paste and printed on a substrate to form electrodes or thick film PTC materials, the baking temperature is approximately 800 to 95°C.
The temperature needs to be 0° C., and there are problems such as composition fluctuations due to PbO scattering, similar to the above. Furthermore, there is a problem in that the room temperature resistance fluctuates significantly due to the influence of glass frit added to improve film-forming properties during paste formation. It is desirable that these problems be solved, since they are hindering the widespread practical use of BaPbO3-based PTC materials.

[Means for solving problems]

According to the present invention, the above-mentioned problems are solved by a method for manufacturing a high-temperature PTC material made of a BaPbO3-based composition, comprising:
This problem can be solved by a method characterized by including a step of crystallizing an amorphous BaPbO3 composition obtained by thermal spraying by heating it at a temperature below its melting point.

In carrying out the method of the present invention, it is preferable that the amorphous BaPbO1-based composition is turned into a paste and then subjected to heat treatment. In order to improve adhesive strength, a glass frit or the like may be contained in addition to a solvent for pasting.

The use of glass frit will not cause variations in cold resistance as in the prior art. heat treatment temperature,
That is, as will be explained below, the baking temperature can be lowered by about 100° C. or more compared to the conventional example.

As described above, the amorphous BaPbO3 composition of the present invention is made amorphous by rapid cooling using a thermal spraying method. Thermal spraying can be carried out according to conventional methods, for example using an arc, or using a flame, plasma or the like.

The 13aPbOz composition of the present invention may be BaPbO3 alone, or may be a composition containing additives commonly used in this field.

As an example of the latter, [1
aPbO1 with excessive addition of PB, and TiO□ to shift the resistance change point to the high temperature side and make it controllable.
, ZrOz, etc., and SiO□, 5iJ1. to obtain a dense sintered body. Flux such as SiC (
sintering aids) and others.

Ba used to prepare BaPbO5-based compositions
PbO3-based calcined products can be prepared using a variety of techniques commonly used in the art, with the exception of Ba(NOs)2. The most useful is a coprecipitation method in which a starting material such as Pb(NOz)z is added dropwise to a (NH4)2CO3 solution. In addition to this coprecipitation method, an alkoxide method using a metal alkoxide as a starting material and others can be used as necessary.

〔Example〕

The present invention will be explained in more detail by way of examples.

Special grade reagents Ha(NOz)z and Pb prepared as raw materials
(NO3)z was dissolved in pure water to make an aqueous solution. Ba and p
Each aqueous solution was measured so that the molar ratio of b was 1=1, and mixed under stirring in a glass container. The resulting mixed solution was added dropwise to a 4N (NH4)2CO3 solution prepared in advance at a rate of 40 ml/win while stirring with a stirrer. (Ba
, Pb)COs coprecipitate was generated. This coprecipitate was decanted several times and then dried. After coarsely pulverizing these coprecipitates using a Raikai machine, they were calcined at 800° C. for 2 hours in an oxygen atmosphere. This calcined product was further wet-pulverized in a ball mill, dried, and then calcined at 800° C. for 2 hours in an oxygen atmosphere. Thereafter, it was ground in a ball mill and dried. BaPbO5 powder was obtained.

Polyvinyl alcohol (PVA) was added to the BaPbO3 powder prepared as described above, and the resulting slurry was granulated using a spray dryer. Particles with an average particle size of 30 μm were obtained.Then, the unobtained PbOz particles were melted with a thermal spray gun while maintaining the arc condition at several thousand degrees, and then sprayed into pure water and quenched. As a result, glass beads having an amorphous 13aPbO1 composition and a particle size of 10 to 45μ were obtained. To 100 g of the obtained glass beads, 10 g of a 10% solution of PVA was added, a solvent was added to form a paste, and this paste was coated on an alumina substrate in a thick film of 100 to 200 μm by screen printing. The formed paste coating film was subjected to different temperatures = 700°C (Example 1), 750°C (Example 2)
, 800°C (Example 3), 850°C (Example 4) and 900°C (
Example 5) After baking for 20 minutes under zero order, the baked sample was baked with Ag paste as an electrode, and the specific resistance (ρ2°) at 20°C was measured by the four-terminal method. Good results were obtained as shown in Table 1 below and FIG. 1 attached.

Samples were prepared in the same manner as described in Examples 1 to 5 above. However, in the case of this example, the molar ratio of Ba and pb is 1:
1.2 (Pb rich), and 75
Baking temperatures of 0°C (Example 6) and 850°C (Example 7) were applied. Good results were obtained as shown in Table 1 below.

Takumi Salmon 10 Samples were prepared in the same manner as described in Examples 1 to 5 above. However, in the case of this example, glass frit was added during paste preparation for the purpose of improving the adhesive strength after paste baking, and glass frit was added at 700°C (Example 8), 750°C (Ran (9)), and 800°C (Example 10). ) was applied.Good results were obtained as shown in Table 1 below.

Ari Ni Takumi Shido (Comparative Example) Samples were prepared in the same manner as those described in Examples 1 to 5 above. However, for comparison, BaPbO3 used in this example
The calcined product was prepared not by the coprecipitation method but by the following conventional method.

BaC01 and pb,o were used as starting materials.

These raw materials were wet mixed in a ball mill with a molar ratio of Ba to Pb of 1=1. After drying, the mixture was calcined at 900° C. for 2 hours in an oxygen atmosphere. Thereafter, it was ground in a ball mill and dried. Further, it was calcined at 900° C. for 2 hours in an oxygen atmosphere, pulverized in a ball mill, and dried.

BaPbO powder was obtained. The obtained BaPbO3
Add 10g of 10% solution of PVA to ioog,
A solvent was added to make a paste. Furthermore, in these examples, glass frit was added for the purpose of improving adhesive strength, as in PA8 to Example 10, and different baking temperatures were used.
800°C (Example 11), 850°C (Example 12), 900°C (
Example 13) and 950°C (Example 14) were applied.

Undesirable results were obtained as shown in Table 1 below and Figure 1 attached.

Comparative Example) Samples were prepared in the same manner as described in Examples 11 to 14 above. However, in the case of this example, the molar ratio of Ba and pb is 1
: 1.2 (Pb rich), and 8
A baking temperature of 50°C was applied. The obtained results are as follows:
Shown in the table.

First step I BaPbO3 700
6.6 Xl0-' 7502 Ba
PbO57505, 6X10-Co Resistance 3
BaPbO, 8006, 0xlO-co
7604 BaPbO18506,3xl
O-' 7605 BaPbO
39007, 9xlO-ri 7606
BaPb, , 203 750 7.
2xlO-' 7407 BaPb,,,
0. 850 8.6xlO-'
7408 BaPbO + force test 71
7. ) 700 6.
7X10-' 7509
BaPbO5 + fp' test 7 littutes 750
6. lX10-'
75010 BaPbO5+jp'tes7
Ritsu 800 6.3xl
O-' 75011 (Kamihika"1jlf
) BaPb! Jx+lj'Tesufuri,)
800 6.2xlO-2750
12 (11'N) BaPbO5+6'test 7 lits 850 1.6xlO-
” 75013 (upper hi ai'if)
BaPbO5+9'Tess7su,) 900
2.0 mowing 0-2 75
014 (Upper MU BaPbO3 +1'Tesfuri,) 950 5. lX1
0-2 76015 (Kamihi Hanakko f!K)
BaPb+, 203+6'Tess7suJ 850
2.5xlO-2740 From the above table and FIG. It can be seen that the elements produced by the conventional method are greatly influenced by the baking temperature and have a large specific resistance. Furthermore, this effect of the method of the invention is due to p
It can be seen that similar results can be achieved for b-rich systems and systems to which glass frit is added.

Furthermore, when comparing the conventional method and the method of the present invention at the baking temperature at which the specific resistance is minimized, the method of the present invention has a baking temperature of approximately 100%.
Since it is possible to lower the temperature by more than .degree. C. and to perform baking at a low temperature, there is little influence of compositional fluctuations due to scattering of Pb, etc., and therefore a BaPbO3-based composition can be obtained at low cost.

〔Effect of the invention〕

According to the present invention, it is possible to suppress the baking temperature dependence of resistivity to a low level, and it is also possible to lower resistivity compared to the conventional method. Furthermore, amorphous BaPb as a paste
O5-based compositions are effective in lowering the baking temperature compared to conventional compositions, and can actually lower the baking temperature by about 100°C or more. Furthermore, in the present invention, since additives such as glass frit can be used with almost no effect on specific resistance, it is possible to improve adhesive strength.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the baking temperature dependence of resistivity of high-temperature PTC materials produced by the method of the present invention and the conventional method.

Claims (1)

[Claims] 1. A method for producing a high-temperature PTC material consisting of a BaPbO_3-based composition, which comprises amorphous BaP obtained by a thermal spraying method.
A method for producing a high-temperature PTC material, comprising the step of crystallizing a bO_3-based composition by heat-treating it at a temperature below its melting point. 2. The manufacturing method according to claim 1, wherein heat treatment is performed after the amorphous BaPbO_3-based composition is made into a paste. 3. The manufacturing method according to claim 2, wherein a glass frit is added to the paste of the amorphous BaPbO_3-based composition.