JPS6181460A - Electrically conductive composition having heat-sensitive resistance - Google Patents

Abstract

PURPOSE:To provide the titled composition having low electrical resistance at normal temperature and high temperature coefficient of resistance, and suitable for a heat-sensitive resistor element, etc., by compounding a crystalline resin with metal-coated carbon particles at specific ratio, and crosslinking the mixture. CONSTITUTION:(A) 100pts. (vol.) of a crystalline resin (e.g. high-density polyethylene) is compounded with (B) 20-70pts., preferably 30-65pts. of carbon particles (e.g. carbon black having particle diameter of 10mmu-1mu) attached with 5-30wt% metal (e.g. copper, nickel, etc.), and the mixture is kneaded and crosslinked to obtain the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat-sensitive resistive conductive compositions with significant positive temperature coefficient characteristics (P'FC) of electrical resistance.

A variety of materials have been known that have positive temperature coefficient characteristics, particularly materials that have the property of rapidly increasing electrical resistance when reaching a certain temperature range (Japanese Patent Publication No. 36-1
No. 6338 Public Axis, Publication No. 50-33707.

Publication No. 56-10352, etc.).

However, with these conventional materials, if the resistance increase factor is increased when a certain temperature range is reached, the electrical resistance at room temperature also increases, which poses a practical problem.

Therefore, the present inventor solved the problems of the above-mentioned conventional materials,
We have conducted intensive research to develop a material that has low electrical resistance at room temperature and a significantly large increase in electrical resistance when it reaches a certain temperature range. As a result, by blending carbonaceous particles with a metal attached as a conductive filler to a crystalline resin base and crosslinking the crystalline resin, a composition having the desired physical properties was obtained. I found out that it can be done.

The present invention was completed based on this knowledge.

That is, the present invention provides a crosslinked composition comprising a crystalline resin and carbonaceous particles to which a metal is attached, wherein the crystalline resin 1
20 to 00 volume parts of carbonaceous particles to which the metal is attached
A heat-sensitive resistive conductive composition containing 70 parts by volume is provided.

Various types of crystalline resins can be used in the present invention, but usually polyolefins such as high-density polyethylene, low-density polyethylene, polypropylene, ethylene-propylene copolymers, olefin copolymers, various polyamides, polyesters, or These include fluoropolymers and modified products thereof.

Next, in the present invention, carbonaceous particles to which a metal is attached are used as a conductive filler, and the metal to be attached here is a metal with good conductivity such as copper, nickel, tin, gold, silver, or platinum. is preferable, and on the other hand, the carbonaceous particles have a particle size of 10
Suitable examples include carbon black such as oil furnace black, thermalp, rank, acetylene black, and graphite having a particle diameter of about mμ to 1μ, particularly 15 mμ to 100 mμ.

Further, the amount of metal attached to the carbonaceous particles to which the metal is attached is not particularly limited and may be appropriately selected depending on various conditions, but it is usually preferably 5 to 30% by weight based on the carbonaceous particles.

In addition, in order to manufacture carbonaceous particles to which this metal is attached,
Although there are various methods, generally a predetermined metal may be attached to the surface of the carbonaceous particles by chemical plating. Here, chemical plating usually involves adsorbing and activating tin or palladium ions onto carbonaceous particles, and then immersing them in a plating solution containing ions of the specified metal to be deposited to deposit the metal. This is done by

The composition of the present invention is composed of the above-mentioned crystalline resin and carbonaceous particles to which metal is attached, and the mixing ratio is 20 parts by volume of carbonaceous particles to which metal is attached to 100 parts by volume of crystalline resin. It should range from 30 to 65 parts by volume, preferably from 30 to 65 parts by volume. If the blending ratio of carbonaceous particles to which metal is attached is less than 20 parts by volume, the electrical resistance at room temperature will increase, and if it exceeds 70 parts by volume, the increase in electrical resistance will be small when a certain temperature is reached. This poses a practical problem.

The composition of the present invention is produced by blending a crystalline resin and metal-attached carbonaceous particles in a fixed ratio, kneading the mixture, and crosslinking the mixture. The kneading at this time can be carried out under various conditions, but usually 1
The kneading may be carried out at a temperature of 30 to 250° C. for 5 minutes or more, and examples of the kneading machine used include a Banbury mixer and a mixing roll.

The crosslinking treatment carried out after kneading can be carried out by various means, such as a method of adding a crosslinking agent such as an organic peroxide, a method of using ozone, a method of irradiating with active energy rays such as electron beams, etc. can be mentioned. Here, the organic peroxide is Hensil peroxide.

t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, t-butyl peroxide, 2.5-dimethyl-2゜5-di(t-
butylperoxy)hexyne-3 and the like.

The degree of crosslinking mentioned above is not particularly limited and may be determined as appropriate depending on each situation; It should be adjusted.

The heat-sensitive resistive conductive composition of the present invention thus obtained has a low electrical resistance at room temperature and a large resistance increase ratio when the temperature rises, and exhibits extremely advantageous properties as a heat-sensitive resistive material.

In particular, a composition with a small content of carbonaceous particles has a significantly large increase in electrical resistance when the temperature is increased, and a composition with a large content of carbonaceous particles has a property that the electrical resistance at room temperature is extremely small.

It can be effectively used as a material.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 50 g of carbon black with an average particle size of 43 mμ (manufactured by Mitsubishi Chemical Industries: Diabranok E) was mixed with 10 mJ of a catalyst solution containing palladium chloride and stannous chloride (manufactured by Okuno Pharmaceutical Co., Ltd.: Conditioner EPC) and 30 mJ of hydrochloric acid. !
and 160 mL of water for 5 minutes, filtered, and washed with water. Next, this carbon black was immersed in dilute sulfuric acid with a concentration of 10 vol. 1%, and washed with water to activate the carbon blank. !!, and 460 m of electroless copper plating solution containing copper sulfate, formaldehyde, tartrate, etc. was added dropwise to this, copper plating was applied, and the resulting copper-plated carbon black was washed with water and dried. The copper content is 12.5 wt%,
The specific gravity was 2.07.

Copper plated carbon bra 7ri 3 obtained in this way
1.9g and high-density polyethylene (manufactured by Idemitsu Petrochemical):
38.1 g of Idemitsu polyethylene 550 B) were kneaded for 20 minutes at 170°C using a laboplasto mill, and 0.21 g of 2.5-dimethyl-2,5-di(t-butylperoxy)hexyne-3 was added as a crosslinking agent. g was added and kneaded for 2 minutes to effect crosslinking.

Next, the crosslinked composition obtained in this way (this).

The composition consisted of 38.9 parts by volume of copper-plated carbon black per 100 parts by volume of high-density polyethylene. ) to wall thickness 1
It was formed into a sheet with a thickness of 1 mm, and electrolytic copper foil was then pressure-bonded to both sides of the sheet. A square section of 1 cm on a side was taken out from the obtained sheet, and its specific resistance at 25° C. was measured, and it was found to be 4.7 Ω·. Also, the resistance value when this product is heated to 150°C is 10" of the resistance value at 25°C.
・It was three times as large.

Comparative Example 1 Example 1 except that 31.9 g of carbon black (dia blank E) with an average particle size of 43 mμ was used as it was in place of the copper-plated carbon black.
Similarly, the mixture was kneaded with high-density polyethylene and crosslinked to obtain a composition. The specific resistance of this product at 25℃ is 4.7Ω・
The resistance value when the temperature was raised to 150°C was 104.9 times the resistance value at 25°C.

Example 2 In Example 1, copper-plated carbon bluff inner core was used for 100 parts by volume of high-density polyethylene. The same operation as in Example I was performed except that the mixture was blended so that the amount was 0 parts by volume. The specific resistance of the obtained crosslinked composition at 25°C was 1.8 Ω·mark, and the resistance value when the temperature was raised to 150°C was toh-'' times the resistance value at 25°C.

Example 3 The same operation as in Example 1 was carried out except that high-density polyethylene was blended so as to have a volume of 100. The specific resistance of the obtained crosslinked composition at 25°C was 0.82 Ω·mark, and the resistance value when the temperature was raised to 150°C was 104 times the resistance value at 25°C.

Claims (3)

[Claims] (1) A crosslinked composition comprising a crystalline resin and carbonaceous particles to which a metal is attached, wherein 20 to 70 parts by volume of the carbonaceous particles to which the metal is attached are blended to 100 parts by volume of the crystalline resin. A heat-sensitive resistive conductive composition. (2) The composition according to claim 1, wherein the carbonaceous particles to which metal is attached are copper-plated carbon black. (3) The composition according to claim 1, wherein the amount of metal attached to the carbonaceous particles to which the metal is attached is 5 to 30% by weight based on the carbonaceous particles.