JPS63170902A - Temperature-sensitive 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] [Object of the Invention] The present invention relates to a temperature-sensitive resistor whose electrical resistance value changes depending on temperature, and particularly relates to an electrical resistor material useful for forming a temperature-sensitive element. .

BACKGROUND ART Conventionally, it has been known to obtain a conductive composition by blending a conductive powder into a synthetic resin, and it is also known to obtain a resistor using such a composition.

It is also known that the electrical resistance value of such a resistor may change depending on the temperature, and Japanese Patent Publication No. 50-33707 describes a method in which fine metal powder, carbon black, etc. are dispersed in a crystalline polymer such as polyethylene or polypropylene. It is known that there are compositions whose electrical resistance rapidly increases near a specific temperature range (transition point), and that the average particle size of such crystalline polymers is from 0.08 microns to 200 microns.
It is disclosed that by dispersing micron spherical carbon powder, a composition can be obtained that has a low initial resistance value and a sufficiently large increase in resistance value at the transition point.

However, the increase in resistance value in this composition occurs when the crystalline polymer transforms into an amorphous state as the temperature rises, so the resistance change does not quickly follow the rise and fall of temperature. It also has drawbacks such as exhibiting a hysteresis phenomenon.
There is also the problem that when the amount of carbon powder blended is increased in order to lower the initial resistance value, the mechanical properties deteriorate.

Furthermore, JP-A-53-86496 discloses that a composition obtained by dispersing a tetraelectric filler in a thermoplastic crystalline polymer exhibits a rapid increase in electrical resistance near its crystal melting temperature. is known, and furthermore, for a crosslinked crystalline polymer whose gel content is at least 0.6 in order to raise the temperature at which a rapid increase in electrical resistance occurs (switching temperature). It is disclosed that a composition containing conductive particles having a diameter of at least 18 mm (80 mm or less in the case of carbon blank) is effective.

However, this composition also suffers from the same drawbacks as mentioned above.

Therefore, the present invention aims to provide a temperature-sensitive resistor having a low initial resistance value, excellent mechanical properties, and high sensitivity.

[Structure of the invention]

. In order to achieve the above object, the inventor of the present invention has conducted various studies on combinations of conductive materials and binders, and has found that the use of specific carbon fibers as a conductive material provides excellent sensitivity. The present inventors have discovered that thermal characteristics can be obtained, and have come up with the present invention.That is, the temperature-sensitive resistor of the present invention is made by bonding a conductive material containing vapor-grown carbon fibers with an organic binder. .

The conductive material used in the present invention is mainly composed of vapor-grown carbon fibers, and conductive carbon powder can be used in combination therewith, if necessary.

The vapor-grown carbon fiber used here is obtained by vapor-phase thermal decomposition of a hydrocarbon compound in a non-oxidizing atmosphere in the presence of a catalyst. Such vapor-grown carbon fibers can be produced by placing a carrier substrate on which fine particles of transition metals such as iron or their compounds as catalysts are attached in a mullite reaction tube installed in a horizontal electric furnace, and Introducing a gaseous mixture of a carrier and a hydrocarbon compound such as ethane or benzene at a temperature of 1000 to 1400°C, thermally decomposing the hydrocarbon in contact with the substrate to grow carbon fibers, and recovering this. obtained by. Furthermore, a substrate such as a ceramic containing silicon is placed in a similar reaction apparatus, and a carrier such as hydrogen, a hydrocarbon compound such as ethane or benzene, and a sulfur-containing substance such as elemental sulfur, hydrogen sulfide, or mercaptan are mixed together. A mixed gas of , or a mixed gas of a carrier such as hydrogen and a sulfur-containing hydrocarbon compound such as dibenzothiophene is introduced at a temperature of 1200-1400°C, and the hydrocarbons in contact with the substrate are thermally decomposed to form carbon fibers. It can also be obtained by growing and collecting it. Such vapor-grown carbon fibers have a diameter of 10 μm and a length of several 1, depending on the reaction conditions.
However, in the present invention, a diameter of 1 to 2 μm can be obtained.
, a length of about 0.1 to 311 can be suitably used.

In addition, carbon black, graphite powder, etc. can be used as conductive carbon powder to be used in combination with vapor-grown carbon fiber, but carbon blanks with a developed structure are preferable, especially Ketjen Black (Lion Akzo Co., Ltd.,
It is preferable to use highly conductive carbon black such as (trade name). The particle size of such carbon powder is as follows:
It is preferably about 10 to 50 μm.

The conductive material in the present invention may be composed only of vapor-grown carbon fibers, but in this case, when the amount of binder is large, the initial resistance becomes large, so if a low resistance value is desired, conductive carbon fibers may be used. There is no particular limit to the content of conductive carbon powder in the conductive material, which is preferably used in combination with powder.
Usually 50% or less is appropriate.

As the binder for the conductive material in the present invention, thermosetting organic binders such as phenol type, urea type, epoxy type, urethane type, unsaturated polyester type, and silicone type can be used. Epoxy-based binders can be suitably used from the surface, but are not limited thereto.

The amount of such a binder to be used is determined based on the balance between electrical resistance and mechanical properties obtained by curing the bond. Usually, it is appropriate to use the amount in the range of 0.2 to 5 with respect to 1 of the conductive material.

-■ The electrical resistance of the temperature-sensitive resistor of the present invention exhibits a large positive temperature coefficient at temperatures of 125° C. or higher, and small hysteresis.

The following vapor-grown carbon fibers FS and FF and pulverized PAN-based carbon fibers FN were prepared as the actual carbon fibers on the plate, and Ketjenblack EC (Lion Akzo Co., Ltd., trade name) was used as the conductive carbon powder. prepared.

FS: Obtained using sulfur and silicon catalyst (diameter:
FF: Obtained using an iron-based catalyst (diameter: approximately 1 μm, length: approximately 0.3 to 0.5 fins) FN: Trading card MLD -300 (Toshisha, product name) (diameter: approx. 7 μm
, length: approx. 0.3 mm) As the binder, Epicure 812 (trade name, Shell Chemical Co., Ltd.) was used as the epoxy resin (E-1), and Epicure (trade name, Shell Chemical Co., Ltd.) was used as the curing agent (E-2). ) was prepared.

According to the blending amounts shown in Table 1, first mix carbon powder with epoxy resin, then add and mix carbon fiber,
Thereafter, a curing agent was added and thoroughly kneaded. The thus obtained compound was injected into a mold and cured by heating under pressure at 120° C. for 3 hours to obtain a cured product measuring vertical length x width 7 CIIX x thickness 1 + u.

Table 1 Sample A B CD E"F"G"H"E
-1100# // 〃# // /l //Carbon powder 10〃〃〃〃3050 Carbon fiber FS 30 60-- --m=〃FF-
-3060---- 〃FN----306O-- EJ 20 #N // N // /l' //
*Comparative Example The temperature of these cured products was gradually raised and then lowered, and changes in electrical resistance during this time were examined. The results are shown in Table 2 as changes in volume resistivity with respect to temperature. Further, the data for samples A, C, E, and G are shown as a graph in FIG.

Looking at these results, the cured product of the present invention has sensitive temperature-sensitive characteristics, and almost no hysteresis phenomenon is observed.
It can be seen that this is a temperature-sensitive resistor with good switching characteristics.

Table 2 Volume resistivity (Ω・ca) (En indicates ×10fi, n is the preparation sample A B CD E”F”
G"H" temperature ("C) 25 4.83.06.74.1 7.9 5.4 2
3.411.950 5.14.46.54.635.
228.9 21.110.8100 4.84.27
．． 43.793.6 1.2E21B, 87.4125
5.36.88.99.4 7.9E25.6E21
6.35.9150 2, IF34.3E36.4E3
7.0 mark 9.2E26.9E212.46.4175
4.6E87.9E73.9E66.3E58.3E2
6.7E29.88.3200 1, a2.4E74.
3E71. IF74.8E26.3E28.69.91
75 8.7B74.9E75. IF52.4 Group 40.
3 4.3E28.88.4150 4.0E21.6
E34.4E31.8E2B, 711.9 B, 68
．． 3125 5.55.97.28.7 8.0 7.
3 8.2 B, 3100 4.74.17.24.2
9.3 4.4 8.47.150 4.42.87
．． 03.9 8.7 4.2 B, 17.125 4
．． 42.87.03.6 3.0 4.0 8.67.
1 Example Ll A blend was prepared according to Table 3 in the same manner as in Example 1, except that an unsaturated polyester binder and a urethane binder were used as binders.

The unsaturated polyester binder used was a base resin (P
-1) is a combination of Eborafuku G-85 (Nippon Shokubai Kagaku Co., Ltd., trade name): benzoyl peroxide as a curing agent (P-2), and the urethane binder used is:
Coronate 4090 (trade name, manufactured by Nippon Polyurethane Kogyo Co., Ltd.) was used as the main resin (U-1), and a combination of methylenebis-orthochloroaniline was used as the curing agent (U-2).

The thus obtained formulations were heated and cured under pressure under the conditions listed in Table 3, and each was heated to 1 cI11
A cured body having dimensions of x width 71 x thickness In was obtained.

Regarding these cured bodies, the temperature dependence of electrical resistance was measured in the same manner as in Example 1, and the results are shown in the second graph.
Shown in the figure.

The results show that the cured product of the present invention has excellent temperature-sensitive properties regardless of the binder used.

Table 3 Sample IJK"LMN" p-i ioo 〃〃--- U-1---100〃〃 Carbon powder IQ /l 〃/F // /
/Carbon fiber FS 30 --30 --〃FF-3
0--30- -〃FN--30--30 P-21〃--- U-2--12,7" ” Curing conditions = 80℃ x 10 minutes - 120℃ x 4 hours - [ [Effects of the Invention] The temperature-sensitive resistor of the present invention is made by bonding a conductive material containing vapor-grown carbon fibers with an organic binder, and has a positive temperature-sensitive property with a sharp electric resistance. , it can be used as a highly reliable temperature-sensitive element with sufficient mechanical properties that can be used at high temperatures.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are graphs showing the temperature-sensitive characteristics of electrical resistance of the temperature-sensitive resistor of the present invention and the resistor of a comparative example, respectively. Patent Applicant Yazaki Sogyo Co., Ltd. Temperature (0C) Figure 1; l/L ('C) Figure 2 Procedure Amendment 4 (Voluntary) April 2, 1986 Commissioner of the Patent Office Black 1) Akio Tono 1, 1 Dairy Cattle 1986 Patent Application No. 001830 2 Name of the invention Temperature-sensitive resistor 3 Relationship to the case of the person making the amendment 1 Dairy Cattle Applicant Address 1-4-28 Mita, Minato-ku, Tokyo Name (689)
) Yasaki Sogyo Co., Ltd. 4, Agent

Claims (3)

[Claims] (1) A temperature-sensitive resistor formed by bonding a conductive material containing vapor-grown carbon fiber with an organic binder. (2) The temperature-sensitive resistor according to claim 1, wherein the conductive material contains conductive carbon powder in addition to vapor-grown carbon fiber. (3) The carbon fiber according to claim 1 or 2, wherein the vapor-grown carbon fiber is obtained by thermally decomposing a hydrocarbon compound in the presence of a catalyst in a non-oxidizing atmosphere. Temperature resistor.