JP3301312B2 - PTC material composition and PTC material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTC material having a positive resistance temperature characteristic (hereinafter abbreviated as PTC characteristic) and a composition thereof. Used to protect the power supply from excessive current.

[0002]

2. Description of the Related Art A resistance element (PTC element) made of a PTC material used for a current control and protection circuit, when an excessive current is applied, the temperature rises due to self-heating due to Joule heat and the element resistance increases. And has the function of reducing the excessive current.

The most common material used for the PTC element is a ceramic obtained by doping BaTiO ₃ with an oxide such as La, Ce, Sr or Pb to form a semiconductor. BaT doped with a small amount of oxide
In the iO ₃ -based semiconductor, below the Curie point, the Schottky barrier at the crystal grain boundary is low due to the ferroelectricity of the grain boundary. It is believed that the Schottky barrier increases and the resistance rises sharply.

Various products using a PTC material composed of BaTiO ₃ or a BaTiO ₃ composition are known. For example, Japanese Patent Application Laid-Open No.
In order to obtain a ceramic heater having a large resistance change width of C, there has been proposed a manufacturing method in which glass powder composed of BaTiO ₃ and a component for semiconductor conversion is mixed with an organic binder, and heat treatment is performed at a temperature lower than a crystal deposition temperature. .

However, the BaT described in the above publication is
In the iO ₃ -based PTC material, the Curie point at which the resistance value sharply increases generally exists in a low temperature range of 100 to 120 ° C. The Curie temperature of the BaTiO ₃ -based PCT material can be controlled by the type and amount of the oxide to be doped. For example, it has been attempted to shift to a higher temperature side by adding Pb (lead) oxide. However, the limit is about 300 to 400 ° C. Further, it is preferable resistivity in the vicinity room as small as possible in order to obtain a high power but, 10 ⁰ ~10 ¹ Ω · cm
The extent was marginal.

The BaTiO ₃ -based PCT material has a drawback that it is difficult to use it in a high-temperature region or a large power because the Curie temperature is high and the room temperature resistivity is not sufficiently low, and the shape is limited. .

As a solution to the above-mentioned disadvantages of the BaTiO ₃ based PCT material, for example, Pt is added to BaPbO ₃ .
bO, B ₂ O _3, PTC materials of the solder glass containing 5-30% by weight of a main component of ZnO, JP 60
-59702. This PTC material has a low room temperature resistivity value of 10 ⁻⁴ to 10 ⁻¹ Ω · cm,
Curie temperature is in the high temperature range of about 750 ° C. But,
The room temperature resistivity fluctuates remarkably due to the influence of the added solder glass, or Pb due to high temperature firing during the manufacturing process.
There is a problem that O is scattered to cause composition fluctuation.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a stable PCT material having a low room temperature resistivity, a high temperature at a resistivity change point, and a large resistance change rate. What you get.

[0009]

The invention according to claim 1 is
V ₂ O ₅ , ZnO and B ₂ O ₃ as main components, Al ₂ O ₃ and
Bi ₂ O ₃ was added, or Al ₂ O ₃ and Li ₂ O ₃ were added.
It is a PTC material composition containing a crystallized glass powder having a crystallization temperature of 500 ° C. or less and a conductive material powder.

[0010]

[0011] The invention according to claim 2 is a device according to claim 1,
In the TC material composition, the conductive material powder is made of a metal powder.

[0012] The invention according to claim 3 is a device according to claim 2 ,
In the TC material composition, the content of the metal powder is 20 to 40 parts by weight with respect to the total of 100 parts by weight of the crystallized glass powder and the metal powder.

[0013] The invention according to claim 4 is a device according to claim 1,
In the TC material composition, the conductive material powder is made of a conductive carbon powder.

[0014] According to Claim 5 invention, P of claim 4, wherein
In the TC material composition, the content of the conductive carbon powder is 5 to 20 parts by weight based on 100 parts by weight of the total of the crystallized glass powder and the conductive carbon powder.

[0015] According to Claim 6 invention, P according to claim 2, wherein
The TC material composition contains low melting glass powder.

[0016] The invention according to claim 7 is the invention according to claim 6 , wherein
In the TC material composition, the content of the crystallized glass powder is 30 to 60 parts by weight with respect to the total of 100 parts by weight of the powder of the crystallized glass, the powder of the low melting point glass, and the metal powder.
The content of the low melting glass powder is 10 to 40 parts by weight, and the content of the metal powder is 20 to 50 parts by weight.

The invention according to claim 8 is characterized in that V ₂ O ₅ , ZnO and
And B ₂ O ₃ as main components, and Al ₂ O ₃ and Bi ₂ O ₃ added.
Alternatively, a molded product obtained by molding a PTC material composition containing a powder of crystallized glass having a crystallization temperature of 500 ° C. or less and Al ₂ O ₃ and Li ₂ O ₃ added thereto and a conductive material powder is fired. PTC material.

[0018]

According to a ninth aspect of the present invention, there is provided the method according to the eighth aspect.
In the TC material, the conductive material powder is made of a metal powder.

According to a tenth aspect of the present invention, in the PTC material according to the ninth aspect , the content of the metal powder is 20 parts by weight based on 100 parts by weight of the total of the crystallized glass powder and the metal powder.
４０40 parts by weight.

According to an eleventh aspect of the present invention, in the PTC material according to the eighth aspect , the conductive material powder is made of a conductive carbon powder.

According to a twelfth aspect of the present invention, in the PTC material according to the eleventh aspect , the content of the conductive carbon powder is 5 to 100 parts by weight in total of the crystallized glass powder and the conductive carbon powder. It is 20 parts by weight.

According to a thirteenth aspect of the present invention, there is provided the PTC material according to the ninth aspect, wherein the PTC material composition contains a low-melting glass powder.

According to a fourteenth aspect of the present invention, in the PTC material according to the thirteenth aspect , a total of 100 parts by weight of the crystallized glass powder, the low melting point glass powder, and the metal powder is used.
The content of the crystallized glass powder is 30 to 60 parts by weight, the content of the low melting point glass powder is 10 to 40 parts by weight, and the content of the metal powder is 20 to 50 parts by weight.

[0025]

Embodiments of the present invention will be described below. The PTC material composition of the present invention has a crystallization temperature of 500
It contains a powder of crystallized glass at a temperature of not more than ° C and a powder of a conductive material.

The powder of crystallized glass includes oxides of V (vanadium), Zn (zinc) and B (boron) (V ₂
O ₅ , ZnO and B ₂ O ₃ ) as main components.

By molding and firing a PTC material composition containing the above-mentioned crystallized glass powder and a conductive material powder, the room temperature resistivity is low, the temperature at the resistivity change point is high, and the resistance change A stable PCT material with a high rate can be obtained.

The conductive material powder may be composed of a metal powder or a conductive carbon powder.

If the content of the metal powder or the conductive carbon powder is too large, the rate of change in resistance becomes small,
When the high resistivity in the C characteristic cannot be maintained and is too small, the room temperature resistivity becomes extremely large. Therefore, the content of the metal powder is 20 to 40 parts by weight based on 100 parts by weight in total.
Parts by weight, preferably 25 to 35 parts by weight, and the content in the case of conductive carbon powder is 5 to 20 parts by weight.

Further, the PTC material composition of the present invention comprises a powder containing a crystallized glass and a metal powder, and further contains a powder of a low-melting glass, so that the PTC material of the molded and fired PTC material is obtained. The rate of change in resistance can be further increased.

The content of each of the crystallized glass powder, the low melting glass powder and the metal powder has an appropriate range for improving the PTC characteristics. That is, if the content of the powder of the low-melting glass is too small, the effect of improving the PTC characteristics cannot be obtained, and if it is too large, the room temperature resistivity remarkably increases,
NTC (Negative Temmpe) in which the resistance change rate decreases or the resistance decreases with an increase in temperature.
(Rateure Coefficient) occurs.
On the other hand, if the content of the metal powder is too large, the rate of change in resistance will be small, and it will not be possible to maintain a high resistivity in the PTC characteristics. If it is too small, the resistivity at room temperature will be significantly large. As a result of various studies, the content of the powder of the crystallized glass is 30 to 60 parts by weight with respect to the total of 100 parts by weight of the powder of the crystallized glass, the powder of the low melting point glass, and the metal powder.
Preferably, the content of the low melting glass powder is 40 to 55 parts by weight, preferably 20 to 30 parts by weight, and the content of the metal powder is 20 to 50 parts by weight, preferably 25 to 45 parts by weight. (The range of the hatched portion in FIG. 2).

Using the PTC material composition as a raw material, the PTC material composition is uniformly mixed and adjusted to produce a molding material, and the molding material is press-molded to produce a molded product. Is fired, crystal precipitation and sintering are advanced to produce the PTC material according to the present invention.

The PTC material obtained by firing contains a conductive material powder at the crystal grain boundaries of crystallized glass.

The conductive material powder at the crystal grain boundaries of the crystallized glass exists as a conductor and forms a conductive circuit. The rapid change of the resistance with respect to the temperature change, that is, the PTC characteristic is
Unlike those based on the ferroelectric-paraelectric transition at the Curie point, such as conventional BaTiO ₃ based PTC materials,
The mechanism of the conductor-insulator transition accompanying the crystal transformation such as the V ₂ O ₃ system, or the conductor circuit of the conductor existing at the crystal grain boundary of the crystallized glass is slightly formed at the crystal grain boundary by the temperature rise. This is presumed to be due to a new mechanism such as being eliminated and cut by a vitreous glass liquid phase or crystals precipitated from this glass liquid phase.

The crystallization temperature of ordinary crystallized glass is 90
At such a high crystallization temperature as 0 to 1000 ° C., the powder of the conductive material becomes unstable and an oxide is formed on the surface, thereby significantly reducing the conductivity.
Using a crystallized glass having a crystallization temperature of 500 ° C. or less,
By sintering at a temperature around 0 ° C., the conductivity of the conductive material powder is maintained, and crystallization and sintering are simultaneously advanced, so that a dense PTC material can be obtained.

As the conductive material powder, metal powder or conductive carbon powder can be used.

The metal powder is stably present as a liquid phase or a solid phase at a temperature of around 500 ° C. at the crystal grain boundary of the crystallized glass of the PTC material, and also has a function of improving the sinterability during sintering.

If the content of the metal powder in the PTC material is too large, the rate of change in resistance will be small, and it will be impossible to maintain a high resistivity in the PTC characteristics. If it is too small, the resistivity at room temperature will be significantly large. Therefore, 20 to 40 parts by weight, preferably 25 to 35 parts by weight, based on 100 parts by weight in total.
Parts by weight.

Also, since the conductive carbon powder in the PTC material has a small specific gravity, if it is too large, it does not mix with the liquid phase of the crystallized glass generated at the time of firing, making sintering difficult. Also, the resistance change rate is the same as that of the conductive carbon. If the amount is too small, the resistivity at room temperature becomes extremely large. Therefore, in the case of conductive carbon powder, the content is 5
To 20 parts by weight.

If the sintering temperature is too low, the crystallization will be insufficient, so that the sintering temperature is about 20 ° C. higher than the crystallization temperature. Therefore, the temperature is set to 550 ° C. or less. According to the results of various investigations, those containing metal powder were fired at 550 ° C. or lower, while those containing conductive carbon powder were fired at 50 ° C. or less.
Good results can be obtained by firing at 0 ° C. or lower.

Further, as described above, the rate of change in PTC resistance can be increased by further adding a low melting point glass powder to the PTC material composition, but the melting point of the low melting point glass powder is lower than the firing temperature. Further, a material having a temperature lower than the crystallization temperature of the crystallized glass powder is used. Is good.

By containing the powder of the low-melting glass, the crystallization and the crystal growth of the crystallized glass progress in the molten low-melting glass at the time of sintering. Effectively exists, the interface of the metal powder increases, and the PTC resistance change width increases.

As the low melting point glass powder, the main components are PbO, B ₂ O ₃ and SiO ₂ (melting point is 300 to 350 ° C.)
Can be used. Since this solder glass has a melting point lower than the firing temperature of the PTC material,
It is suitable for the precipitation and crystal growth of crystallized glass in the molten solder glass to proceed, and has a function of promoting sintering and improving the strength of the sintered PTC material.

The PTC material composition and the crystallized glass of the PTC material according to the present invention contain V ₂ O ₅ , ZnO and B ₂ O ₃ as main components, to which Al ₂ O ₃ and Bi ₂ O ₃ are added, or It is sufficient that the crystallization temperature is 500 ° C. or less, such as the one to which Al ₂ O ₃ and Li ₂ O ₃ are added, and the average particle size of the crystallized glass is not particularly limited, but is usually 3 to 20 μm.
It is preferred that

The conductive material powder may be carbon powder,
Conductive materials such as metal powders such as Sn, Fe, Co, Ni, Mo, W, Ag, Pt or Pd, alloy powders, and mixtures of one or more of these metals or alloy powders Good, but especially room temperature resistivity is 11 ×
Metal powder of 10 ^-6 Ω · cm or less or resistivity at room temperature of 1
A conductive carbon powder of × 10 ⁻³ Ω · cm or less is preferable.

The average particle size of the conductive material powder is not particularly limited.
Preferably, the average particle size of the conductive carbon is 30 to 100 nm in terms of PTC characteristics.

[0047]

The present invention will be described below in detail with reference to examples and comparative examples. Embodiments 1-28. Table 1 shows the composition of the PTC material composition, the firing temperature, the room temperature resistivity, the resistivity change point and the change rate (resistivity at 500 ° C./room temperature resistivity) in this example.
This is shown together with Comparative Examples 1 to 5.

[0048]

[Table 1]

The PCT material composition of the present example was obtained by using V ₂ O ₅ −
_{ZnO-B 2 O 3 -Al 2} O 3 -Bi 2 O 3 based crystallized glass (crystallization temperature: 430 ° C., a melting point: 670 ° C.) and powder,
Ag, Sn, Cu, Fe, Co, Ni,
At least one metal powder of Mo, W, Pt or Pd was used as a raw material. These metal powders include high-purity reagents (99.
99%).

First, this raw material was weighed and mixed with a crystallized glass and a metal powder with the composition shown in Table 1 above, followed by premixing for 5 minutes with an omni mixer, and then adding acetone for 5 minutes. The mixture was mixed by a stirring machine and further mixed by a wet ball mill for 6 hours to achieve uniformity, thereby obtaining a mixed material.

Next, the above mixed material was left in a normal draft to apparently volatilize acetone, then kept in an oven at 50 ° C. for 1 hour, and further heated to 80 ° C. for 1 hour.
Hold day and night to completely remove acetone and dry to remove PTC
A material composition was obtained.

The obtained PTC material composition was prepared with a diameter of 30 mm.
Of was filled in a mold, the height to form a compact of about 2mm by pressure formed shape. This molded body was heated to a temperature of about 500 ° C. in an electric furnace and allowed to cool naturally to obtain a PTC material. By this heating, crystallization and sintering of the glass progress.

An Ag paste was applied to the obtained PTC material and baked to form an electrode, and the temperature characteristics of resistivity from room temperature to 500 ° C. were measured.

As shown by the results in Table 1 above, Comparative Example 1
(90% by weight of crystallized glass) has a high room temperature resistivity, no resistance change point is observed, and Comparative Examples 2 and 3 (crystallized glass 5
0% by weight), the room temperature resistivity was low, but no resistance change point was observed. On the other hand, Examples 1-28 (the content of crystallized glass was 60-80% by weight and the content of metal powder was 20
40 wt%), the room temperature resistivity of about 10 ⁰ Ω · cm or less, the resistivity change point resistance change rate at 400 ° C. or more 5 or more PTC material is obtained, in particular, the content of crystallized glass Good results were obtained when the metal powder content was 25 to 35% by weight (Examples 4 and 5) at 65 to 75% by weight.

In Comparative Examples 4 and 5, the firing temperature was examined. Good results were obtained when the firing temperature was 450 to 550 ° C. When the temperature was low, it was unsintered, and when the firing temperature was high as in Comparative Example 5 (fired temperature 600 ° C.), foaming occurred and the room temperature resistivity increased, and no resistance change point was observed.

Embodiments 29 to 41. In this embodiment, the crystallized glass and the conductive material powder (metal powder) further contain a low melting point glass. Table 2 shows the composition of the PTC material composition, the firing temperature, the room temperature resistivity, and the resistivity change point. And the rate of change in resistivity (resistivity at 500 ° C./resistivity at room temperature) are shown together with Comparative Examples 6 to 9.

[0057]

[Table 2]

V ₂ O ₅ —ZnO—B ₂ O ₃
-Al ₂ O ₃ -Bi ₂ O ₃ -based crystallized glass (crystallization temperature: 4
A powder having a melting point of 30 ° C. and a melting point of 670 ° C.) was used, and a frit glass based on PbO—B ₂ O ₃ —SiO ₂ —Bi ₂ O ₃ was used as the low melting point glass. Ag powder, metal powder obtained by mixing Ag and Cu, metal powder obtained by mixing Ag, Cu and Pd are used as the conductive material powder, and a high-purity reagent (99.
99%).

First, this raw material was weighed and blended with a crystallized glass, a low-melting glass powder and a metal powder according to the composition shown in Table 2 above, followed by pre-mixing as in Examples 1-28.
A mixed material was obtained through mixing with an Ishikawa stirring mill and homogenization with a wet ball mill, and the mixed material was dried in a normal draft and in an oven to obtain a PTC material composition.

The obtained PTC material compositions were prepared as in Examples 1 to
Pressure molding in the same way as 28, diameter 30mm, height about 2mm
Was formed. This molded body is placed in an electric furnace at 500 ° C.
The PTC material was obtained by heating to the temperature before and after and allowing it to cool naturally.
By this heating, crystallization and sintering of the glass progress.

An Ag paste was applied to the obtained PTC material and baked to form an electrode, and the temperature characteristics of resistivity from room temperature to 500 ° C. were measured. FIG. 2 shows composition 1 of the present example and composition 2 of the comparative example.

As shown in the results of Table 2, 30 to 60% by weight of crystallized glass, 10 to 40% by weight of low melting glass,
The room temperature resistivity was about 10 in the range of 20 to 50% by weight of the metal powder, that is, in the range including the composition 2 of the example (the hatched portion in FIG. 2).
A PTC material having ⁰ Ω · cm or less, a resistivity change point of 400 ° C. or more, and a resistance change rate of 5 or more is obtained. In particular, crystallized glass 35 to 55% by weight, low melting point glass 15 to 35% by weight,
Good characteristics can be obtained in the range of 25 to 45% by weight of the metal powder. Comparative examples 6 and 7 outside the composition indicated by the oblique lines (composition 2 of the comparative example in FIG. 2) have high room temperature resistivity, and comparative example 8 has low room temperature resistivity but no resistance change point was observed.

Good results are obtained when the firing temperature is in the range of 450 to 500 ° C. higher than the crystallization temperature of the crystallized glass. Comparative Example 9 examines the firing temperature, and shows that even if the composition is within the range of the hatched portion in FIG. 2, when the firing temperature exceeds 500 ° C., foaming occurs and the room temperature resistivity increases.

Embodiments 42 to 45. In this example, conductive carbon was used as a raw material of the conductive material powder. Table 3 shows the composition of the PTC material composition, firing temperature, room temperature resistivity, resistivity change point, and resistance change rate (500 ° C.). At room temperature / resistivity at room temperature) along with Comparative Examples 10 to 13.

[0065]

[Table 3]

V ₂ O ₅ —ZnO—B ₂ O ₃ is used for the crystallized glass.
-Al ₂ O ₃ -Bi ₂ O ₃ -based crystallized glass (crystallization temperature: 4
A powder having a high purity (99.99%) with an average particle diameter of 50 nm was used as the conductive carbon.

First, this raw material was weighed and blended with the composition shown in Table 3 above, followed by pre-mixing as in Examples 1-28.
A mixed material was obtained through mixing with an Ishikawa stirring mill and homogenization with a wet ball mill, and the mixed material was dried in a normal draft and in an oven to obtain a PTC material composition.

The obtained PTC material compositions were prepared in Examples 1 to
Pressure molding in the same way as 28, diameter 30mm, height about 2mm
Was formed. This molded body is placed in an electric furnace at 500 ° C.
The PTC material was obtained by heating to the temperature before and after and allowing it to cool naturally.
By this heating, crystallization and sintering of the glass progress.

An Ag paste was applied to the obtained PTC material and baked to form electrodes, and the temperature characteristics of resistivity from room temperature to 500 ° C. were measured.

As shown in the results in Table 3, 80 to 95% by weight of crystallized glass and 5 to 20% by weight of conductive carbon
Room temperature resistivity (Example 42-45) is about 10 ⁰ Ω · cm
Hereinafter, a PTC material having a resistivity change point of 400 ° C. or more and a resistance change rate of 5 or more is obtained. In the case of a composition outside this composition (Comparative Examples 10 and 11), the room temperature resistivity is high and the resistance change point is high. It was not observed (Comparative Example 10), and even if observed, the resistance change rate was small (Comparative Example 11).

Good results can be obtained when the firing temperature is in the range of 450 to 500 ° C. higher than the crystallization temperature of the crystallized glass. In Comparative Examples 12 and 13, the firing temperature was studied. When the firing temperature exceeded 500 ° C., foaming occurred and the firing temperature was low (43).
0 ° C.), the room temperature resistivity is high and the resistance change rate is negative (NTC characteristic).

In Examples 1 to 45, V _{2
O 5 -ZnO-B 2 O 3} -Al 2 O 3 -Bi 2 O 3 system was used a powder of crystallized _{glass, V 2 O 5 -ZnO-B} 2 O 3 -Al
Similar PTC characteristics were obtained when powder of ₂ O ₃ —Li ₂ O ₃ crystallized glass was used.

[0073]

According to the first to fourteenth aspects of the present invention, a PTC material having a low room temperature resistivity, a high temperature at a resistance change point, a large resistance change rate, and stable PTC characteristics can be obtained.

According to the sixth, seventh, thirteenth, and fourteenth aspects of the present invention, the rate of change in resistance can be further increased, and
A PTC material exhibiting C characteristics is obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing temperature characteristics of a general PTC material.

FIG. 2 is a diagram showing a composition range of a PTC material containing a low melting point glass of the present invention.

[Explanation of symbols]

 1 Composition of Example 2 Composition of Comparative Example

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01C ^7/ 02-7/22

Claims (14)

(57) [Claims] 1. A composition comprising V ₂ O ₅ , ZnO and B ₂ O ₃ as main components.
And Al ₂ O ₃ and Bi ₂ O ₃ were added, or Al ₂ O ₃
A PTC material composition comprising: a powder of crystallized glass to which O ₃ and Li ₂ O ₃ are added, the crystallization temperature of which is 500 ° C. or lower; and a conductive material powder. 2. The PTC material composition according to claim 1 , wherein the conductive material powder comprises a metal powder . 3. The sum of the powder of crystallized glass and the metal powder
The metal powder content is 20 to 40 parts by weight based on 100 parts by weight.
The PTC material composition according to claim 2 , wherein the PTC material composition is part by weight . 4. The conductive material powder is a conductive carbon powder.
PTC material composition according to claim 1, characterized in that it consists of. 5. A powder of crystallized glass and a conductive carbon powder.
Conductive carbon powder with respect to 100 parts by weight in total
The PTC material composition according to claim 4 , wherein the content of PTC is 5 to 20 parts by weight . 6. The PTC material composition according to claim 2, further comprising a low melting glass powder . 7. Powder of crystallized glass and powder of low-melting glass
For a total of 100 parts by weight of powder and metal powder,
Low melting glass with a content of lath powder of 30 to 60 parts by weight
Powder content is 10 to 40 parts by weight, metal powder content
PTC material composition according to claim 6, wherein the but 20 to 50 parts by weight. 8. A composition comprising V ₂ O ₅ , ZnO and B ₂ O ₃ as main components.
And Al ₂ O ₃ and Bi ₂ O ₃ were added, or Al ₂ O ₃
The crystallization temperature to which O ₃ and Li ₂ O ₃ are added is 500 ° C. or less
Containing crystallized glass powder and conductive material powder
A PTC material obtained by firing a molded product obtained by molding a PTC material composition . 9. The PTC material according to claim 8 , wherein the conductive material powder comprises a metal powder . 10. A combination of a crystallized glass powder and a metal powder.
The metal powder content is 20 to 4 with respect to a total of 100 parts by weight.
The PTC according to claim 9, wherein the amount is 0 parts by weight.
material. 11. The PTC material according to claim 8 , wherein the conductive material powder comprises a conductive carbon powder. 12. A conductive carbon powder based on a total of 100 parts by weight of a crystallized glass powder and a conductive carbon powder.
The PTC material according to claim 11 , wherein the content of the powder is 5 to 20 parts by weight . 13. The method of claim 1, wherein the PTC material composition comprises a low melting glass.
The PTC according to claim 9, wherein the PTC contains a powder.
material. 14. A method for producing a powder of crystallized glass and a glass having a low melting point.
Crystallized for a total of 100 parts by weight of powder and metal powder
30-60 parts by weight of glass powder, low melting point glass
Powder content is 10 to 40 parts by weight, metal powder content
Claim amount, characterized in that 20 to 50 parts by weight 1
3. The PTC material according to 3 .