JPH10154603A - V type electric resistance temperature characteristic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make feasible of the decision of arbitrarily specific V type shaped temperature characteristics by selectively combining the positive temperature characteristics with the negative temperature characteristics by a method wherein the primary compound particles comprising the grandchild particles discontinuously dispersed and deposited onto the children particle surface are composed of the compound particles furthermore discontinuously dispersed and deposited onto the parent particle surface. SOLUTION: Firstly, the ceramics particles 4 having the negative temperature characteristics as the child particles and the In particles 2 as the grandchild particles are respectively inserted into forcibly charging device having cylindrical oscillating electrode to be respectively applied with positive and negative high voltage so as to fabricate In-NTC compound particles 11 in the mode wherein the In particles 2 are discontinuously dispersed and deposited onto this NTC particle surface. Next, the obtained In-NTC compound particles 11 and the ceramic particles 13 as the parent particles having the positive temperature PTC are inserted into the forcible charging device again to be respectively applied with negative and positive high voltage so that the compound particles 14 whereon the primary In-NTC compound particles 11 are discontinuously dispersed and deposited may be fabricated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a V-type electric resistance temperature characteristic material and a method for producing the same.

[0002]

2. Description of the Related Art Generally, ceramic materials are
Unlike a metal, its electric resistance decreases with an increase in temperature and is called a negative temperature characteristic resistor (NTC material). A resistor having a particularly large temperature coefficient is widely used for a thermistor thermometer or the like. Composite oxides of transition metals such as Mn and Ni are known as typical examples. On the other hand, there are rare ceramic materials having a positive temperature coefficient, which are called positive temperature characteristic resistors (PTC materials), and are used for degaussing elements, motor starting elements, temperature compensating elements, and hair. Widely used for self-control heater materials such as dryers and mosquito traps. BaTiO ₃ is known as a typical example.

[0003] As described above, these temperature characteristic resistor materials are used singly by making use of their respective temperature characteristics. However, materials combining these characteristics are also attracting attention, and their practical development is expected. There are also rare. However, as for the material showing a V-type change in resistance to temperature, which is a combination of both characteristics, conventionally, only materials manufactured by sintering or heat treatment in expensive equipment such as a high-temperature furnace are available, and therefore, the shape is limited, Also required V
The lack of arbitrarily control over the mold properties has severely limited its use and application.

[0004] Actually, as a material exhibiting such a V-type electric resistance temperature characteristic, a BaTiO ₃ -based PTC has hitherto been used.
WO ₃ + Yb ₂ O ₃ (Patent Publication No. 54-275)
55), and also BaTiO ₃ -based P
Ba was replaced with Sr and Pb in the TC material (Sr _x P
b _1-x-0.002 Y _0.003 ) TiO ₃ based material (electro-
Ceramics Magazine No. 93 (1988)). In the former, a V-type temperature characteristic is obtained by adding WO ₃ , and the specific resistance is reduced by adding Yb ₂ O ₃ . In the latter, the specific resistance and the temperature of the lowest resistance value can be changed by changing the Sr / Pb ratio and the Sr / Ti ratio.

However, in these methods, the composition and characteristic value are changed by adding a trace element, and in order to obtain the required temperature characteristic, based on much experience and know-how, from the stage of the raw material. Strict control is needed. Therefore, there is a problem that it is extremely difficult to easily obtain a material having a desired V-type characteristic value. In addition, since both are bulk sintered materials, a sintering process at a high temperature of 1,000 and several hundred degrees Celsius after molding into a required shape is indispensable, and the shape change in this process is large and complicated. It is difficult to obtain a shape, and there is a great limitation on use in an arbitrary shape.

On the other hand, there is also known a material in which a PTC material and a NTC material having a disk shape (diameter 6 mm, thickness 1 mm) are joined and integrated by high-temperature baking with an electrode paste material to give a V-type electric resistance temperature characteristic. (Patent publication Sho 61-
159705). In this case, it is easy to obtain a material having a desired V-type characteristic value, but it is impossible to use the material in an arbitrary complicated shape or to minimize the size, and a high-temperature treatment at about 600 ° C. is indispensable. ing.

Accordingly, the present invention has been made in view of the above circumstances, and eliminates defects of not only a sintered material but also a laminating material, such as coating, fixing resin of a green compact or a filled body, and the like. It is an object of the present invention to provide a new V-type electric resistance temperature characteristic material which can be used in an arbitrary complicated shape by a simple procedure without high-temperature sintering, and a method for producing the same.

[0008]

The present invention solves the above-mentioned problems by providing a parent particle having a positive or negative electric resistance temperature characteristic, and a negative or positive electric particle having a size smaller than the parent particle diameter. A child particle having a resistance temperature characteristic, and a metal particle that forms an ohmic junction with the parent particle and the child particle, and is composed of a grandchild particle having a size equal to or smaller than the child particle diameter. Provided is a V-type electric resistance temperature characteristic material, wherein the primary composite particles are further constituted by composite particles which are discontinuously dispersed and attached to the surface of the parent particles.

Further, the present invention relates to a child particle having a negative or positive electric resistance temperature characteristic having a size equal to or less than a parent particle diameter, and a metal particle having an ohmic junction with the child particle having a size equal to or less than the child particle diameter. The particles are forcibly charged to opposite polarities, respectively.
Due to the electrostatic force adhesion between the progeny particles and the progeny particles and the repulsion of the same polarity between the progeny particles, the progeny particles are discontinuously dispersed and adhered to the surface of the progeny particles to form primary composite particles. The parent particles having temperature characteristics and the primary composite particles are forcibly charged to opposite polarities, and the primary composite particles are discontinuously dispersed and adhered to the surface of the parent particles to form composite particles. A method for producing a V-type electric resistance temperature characteristic material, characterized by comprising a plurality of fillings to form an electric resistance temperature characteristic material, is also provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention realizes a V-type electric resistance temperature characteristic material having the following new features by the structure of composite particles in two stages by the above-described forced charging treatment. . First, it is characterized in that particles having appropriate negative temperature characteristics and particles having positive temperature characteristics can be separately selected according to the required V-shape. That is, the temperature of the V-shaped valley bottom and the temperature range thereof can be arbitrarily controlled by selecting and combining particles. Furthermore, since the structural unit is not a sintered body bulk but microparticles,
There are no major restrictions on the shape used as a material, and the composite particles can be used in extremely complex shapes without dispersing them in a solvent, applying them as they are, or sintering them at high temperatures as a green compact or packing. And miniaturization is possible.

[0011] In the production of the material of the present invention having such characteristics, according to the above-described method,
Although it is a sintered body, for example, the diameter is 100 μm to several hundred μm.
Positive or negative, and ceramic particles having a negative or positive temperature characteristic of several tens μm to several tens μm, and a diameter of several tens μ
m low work function metal particles can be used. More specifically, for example, first, ceramic particles (NTC particles) having negative temperature characteristics as child particles and metal particles as grandchild particles are forcibly charged to opposite polarities to produce primary composite particles. Next, the composite particles and the ceramic particles (PTC particles) as a parent particle having a positive temperature characteristic are forcibly charged to the opposite polarity to form secondary composite particles. In this case, if the diameter between the parent, child and grandchild particles is appropriately selected, there is no particular restriction on the order of the temperature characteristic, the polarity of the forced charging process, and the order of the charging process. Regarding the size of the particles, generally, the size of the child particles is preferably about 1/5 to 1/30 with respect to the parent particle diameter, from the viewpoint of handling of the particles and the like. As a guide. Further, as the primary composite particles, it is also possible to form a composite particle by attaching a metal in an island shape by vacuum deposition instead of the forced charging treatment.

The material having the composite particles formed as described above as a constituent unit has a structure in which NTC and PTC particles are connected via metal particles. If ohmic bonding with the particles is possible, the contact resistance between the PTC particles and the NTC particles can be almost neglected, and the temperature characteristics of the electric resistance show a V-shaped characteristic in which the NTC characteristics and the PTC characteristics are simply added. Become.

The method of producing composite particles by forced charging has already been proposed by the inventors of the present invention as a new technique (Japanese Patent Application No. 2005005311 and Japanese Patent Application No. Hei 7-203,197).
However, creation of composite particles composed of parent, child, and grandchild particles by NTC, metal, and PTC, and expression of V-type electric resistance temperature characteristics by the use of NTC, metal, and PTC, are completely new according to the present invention. It is proposed. Of course, as for the means for the charging process, a method using a vibrating cylindrical electrode or a method using a counter electrode, or a known charging processing device, for example, a boxer charger or the like can be used. There is no particular limitation as long as control is possible.

Hereinafter, examples will be shown, and embodiments of the present invention will be described in more detail.

[0015]

【Example】

(Example 1) For example, using the charging device shown in FIG. 1, first, ceramic particles (4) having a negative temperature characteristic (NTC) having a particle diameter of 26 to 32 μm as child particles and particle diameters as grandchild particles Each of the In particles (2) having a size of 20 μm or less is charged into a forced charging device having cylindrical vibrating electrodes (1) and (3),
A positive and negative high voltage (4 kV) is applied to each of them for 5 minutes by the high voltage power supply devices (5) and (6), thereby forcibly charging them in opposite polarities, and the same voltage is simultaneously applied to each of the electrode openings (9) and (10). The ceramic NTC particles (4) are used as a core by electrostatic attraction acting between the positively charged ceramics NTC particles (4) and the negatively charged In particles (2) shown in an enlarged manner in FIG. Then, In-NTC composite particles (11) in a form in which the In particles (2) are discontinuously dispersed and adhered to the surface of the NTC particles (4) are produced. In addition,
FIG. 1 also shows a counter electrode (12) that is grounded together with the piezoelectric elements (7) and (8).

Next, as shown in FIG. 2, the obtained In-N
The TC composite particles (11) and the ceramic particles (13) as a parent particle having a positive temperature characteristic (PTC) having a particle diameter of 150 to 212 μm are charged again into a forced charging device, and negative and positive high voltages are applied to each of them. (4 kV) for 5 minutes to forcibly charge the battery to the opposite polarity. In the same manner as described above, as shown in FIG.
Primary In-NTC composite particles (11) composed of NTC ceramic particles (4) having particles (2) discontinuously dispersed and adhered to the surface thereof are similarly mixed particles (14) discontinuously dispersed and adhered to the surface thereof. Make it. Here, the contact resistance between the parent-child particles, that is, the contact resistance between the PTC ceramic particles (13) as the parent particles and the NTC ceramic particles (4) as the child particles is reduced to a resistance value corresponding to the specific resistance of the metal In. I have.

The composite particles (14) thus obtained
4 as shown in FIG.
0), a cell is filled so as to have a thickness of 1 to 1.5 mm, and a cell whose both ends are suppressed by a stainless steel rod (22) via an In foil (21) is assembled. The cell was set in a thermostat, and while the temperature of the thermostat was raised and lowered, the electric resistance of the cell was measured by a constant current application method using an electrometer with the rod (22) as an electrode. FIG. 5 shows the temperature-electric resistance characteristic results obtained in this manner.
From this figure, it can be seen that the V-type temperature characteristic shows 6 MΩ at 90 ° C. Example 2 Ceramic particles (NTC particles) having a negative temperature characteristic (NTC) having a particle size of 26 to 32 μm as child particles were charged into an appropriate vacuum evaporation apparatus, and tungsten particles set in a resistance heating electrode were used. After putting the small mass of In into the basket, the inside of the tank is evacuated to 1 × 10 ⁻⁵ Torr by a vacuum pump. Then, apply a voltage to the basket for about 7
Heating to 00 ° C. and holding the melting and evaporating of the In mass for about 1 minute, vacuum vapor deposition of In that forms ohmic contact with the surface of the NTC ceramic particles in an island shape. Next, the island-like In-adhered NTC particles and a particle size of 150 to 2
Ceramic particles having a positive temperature characteristic (PTC) of 12 μm were charged into a vibrating cylindrical electrode type forced charging device in the same manner as in FIG. 2, and a negative and positive high voltage (4 kV), respectively.
Is applied for about 5 minutes to forcibly charge the battery to the opposite characteristic, and then simultaneously discharged to the same region, and P is applied by electrostatic attraction between both particles.
Island-like In attached N on TC ceramic particles
A composite particle in which TC particles are dispersed and adhered discontinuously is produced.
The composite particles thus obtained were filled in a quartz tube (20) having an inner diameter of 2 mm and having a thickness of 1 to 1.5 mm as shown in FIG. 4 to assemble a cell, and the temperature-electric resistance characteristics were measured. FIG. 6 shows the result. A V-shaped temperature characteristic having an electric resistance of 1 MΩ at a temperature of 70 ° C. is obtained.

The resistance value of the V-type temperature characteristic is equal to that of the first embodiment.
In Example 2, the lower values were attributable to PTC ceramic particles and N
This is considered to indicate that the In particles exist more reliably between the TC ceramic particles.

[0019]

As described in detail above, according to the present invention, the positive temperature characteristic and the negative temperature characteristic can be individually selected with a large degree of freedom, and by combining these, any desired V-shaped shape can be obtained. Temperature characteristics can be determined. This effect is due to the fact that the material itself is not a bulk sintered body but the constituent units are small particles, and there is no great restriction on the used shape and the size can be minimized. It can be applied to a heater having a low-temperature holding function, an overcurrent prevention function, a switch, a surge absorption, a constant current holding function, and an overcooling / overheating prevention function.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a state of a forced charging process using a vibrating cylindrical electrode type charging device of the present invention.

FIG. 2 is a schematic diagram similar to FIG.

FIG. 3 is a schematic view illustrating a composite particle including a parent, a child, and a grandchild particle.

FIG. 4 is a schematic diagram illustrating a cell for measuring electric resistance-temperature characteristics.

FIG. 5 is a relational diagram showing a measurement result of electric resistance-temperature characteristics when a composite cell is filled in a quartz cell.

FIG. 6 is a relationship diagram showing measurement results of electric resistance-temperature characteristics of composite particles formed of island-like In-attached NTC particles and PTC parent particles.

[Explanation of symbols]

 1, 3 cylindrical electrode 2 In grandchild particles 4 NTC ceramic particles 5, 6 high-voltage power supply 7, 8 piezoelectric element 9 opening of cylindrical electrode 1 10 opening of cylindrical electrode 3 11 In-NTC composite particles 12 grounded counter electrode 13 PTC ceramic particles 14 Composite particles 20 Transparent quartz tube with 2 mm inner diameter 21 In foil 22 Stainless steel rod electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Fudoji 1-2-1 Sengen, Tsukuba-city, Ibaraki Pref., National Institute of Science and Technology (72) Inventor Norio Shintani 1-2-1 Sengen, Tsukuba-shi, Ibaraki No. Science and Technology Agency, Metal Materials Research Laboratory

Claims (4)

[Claims] An ohmic junction between a parent particle having a positive or negative electric resistance temperature characteristic, a child particle having a negative or positive electric resistance temperature characteristic having a size equal to or less than the parent particle diameter, and a parent particle and a child particle. In the metal particles, the primary composite particles composed of the grandchild particles having a size equal to or smaller than the child particle diameter, and the grandchild particles were discontinuously dispersed and adhered to the surface of the child particles, were further discontinuously dispersed and adhered to the surface of the parent particle. A V-type electric resistance temperature characteristic material, comprising a composite particle. 2. A V-type electronic resistance temperature characteristic material formed by filling or coating the plurality of composite particles according to claim 1. 3. A child particle having a negative or positive electric resistance temperature characteristic having a size equal to or less than the parent particle diameter, and a grandchild particle having a size equal to or less than the child particle diameter formed of a metal particle which is in ohmic contact with the child particle. Each is forcibly charged to the opposite polarity, and due to the electrostatic force adhesion between the child particles and the grandchild particles and the repulsion of the same polarity between the grandchild particles, the grandchild particles are discontinuously dispersed and adhered to the surface of the child particles to form primary composite particles, Next, the parent particles having positive or negative electric resistance temperature characteristics and the primary composite particles are forcibly charged to opposite polarities, and the primary composite particles are discontinuously dispersed and adhered to the surface of the parent particles, thereby forming composite particles. And forming a plurality of the composite particles to form an electric resistance temperature characteristic material. 4. A method according to claim 2, wherein the metal to be ohmic-bonded is vacuum-deposited in the form of islands on the surface of the child particles to disperse and attach the grandchild particles.
A method for producing a V-type electric resistance temperature characteristic material.