JPS5825087B2 - Method for manufacturing conductive polymer molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a conductive polymer molded article.

Conventionally, various methods have been proposed for producing conductive polymer molded articles, including methods in which conductive particles such as metal powder or powdered carbon black are contained or coated in polymer molded articles.

The main problem with these conventional techniques is that although conductive particles are applied to the molded product to cover its surface, the resulting molded product has a relatively low conductivity. The conductivity of the synthetic fiber was 109Ω/crrL or more when expressed in terms of electrical resistance.

The reason for this is that the degree of filling of the conductive particles covering the polymer molded article or the structure of the molded article is insufficient.

The object of the present invention is to obtain very good electrical conductivity, i.e. 107Ω/
The object of the present invention is to provide a polymer molded product having an electrical resistance value of crrL or less, and to provide a manufacturing method that eliminates the above-mentioned drawbacks.

ゝThroughout the present invention, the term 11 polymer molded product “1
It also includes fabrics such as filaments, fibers, ropes, tapes, films, and woven fabrics, knitted nonwoven fabrics, etc. obtained by assembling filaments or fibers.

In the present invention, "coating" means creating a state in which the particles uniformly cover the surface of the molded article and do not easily peel off due to friction or the like.

The present inventors have discovered that when a polymer molded article is stretched and coated with conductive particles on its surface, the molded article has excellent conductivity, and has completed the present invention.

That is, the structure of the present invention is to stretch a molded article made of an elastically stretchable polymer having an elastic recovery rate of 70% or more at a stretching rate of 50% or more and cover the conductive particles by stretching the molded article by at least 50%. It is in.

The stretchable polymer referred to in the present invention has an elongation degree of 50% or more, preferably 80% or more with respect to its original length, and an elastic recovery rate of 70% or more, preferably 90% or more. It refers to polymers.

In the case of a fabric structure, the structure must be elastically extensible in at least one direction to the same degree as the molded article.

Molded products made of polymers that have an elongation rate of 50% or less and an elastic recovery rate of 70% or less do not have good conductivity, perhaps because the degree of filling of the conductive particles coated on the surface of the molded product is insufficient. It is difficult to grant it.

Examples of polymers that can be applied to the present invention include so-called elastic polymers obtained by sufficiently annealing natural rubber, synthetic rubber, polyurethane, polyethylene, polypropylene, and polyoxymethylene polymers with a crystallinity of 40% or more. It is a stretchable polymer that has rubber elasticity or energy elasticity.

In the present invention, a molded product made of the above-mentioned stretchable polymer is stretched,
The molded article is coated with conductive particles.

The degree of elongation is advantageously at least 50%, preferably at least 80%, relative to the original length.

The conductive particles referred to in the present invention are, for example, carbon black or metal powders made of silver, copper, iron, zinc, aluminum, and alloys thereof, and the appropriate particle size is one with an average diameter of 5 microns or less. , and more preferably 1 micron or less.

As for the method of coating the polymer molded article with conductive particles, it is preferable that no other substance intervenes between the particles.

A method suitable for the present invention includes dissolving the surface of the elongated polymer molded article with a solvent or softening the surface, and then coating the surface with conductive particles.

In particular, the physical properties of the polymer molded product were sacrificed as much as possible (
If not, a solvent dissolution method is preferred, and surface dissolution can be achieved, for example, by sufficiently moistening the surface of the molded article with a good polymeric solvent constituting the molded article before or during elongation.

Further, coating with conductive particles can be achieved by immersing or running an elongated product whose surface has been sufficiently dissolved or sufficiently wetted with a solvent in a particle bath or a fluidized bed of particles.

It is important to coat the conductive particles as densely as possible, and it is preferable to coat the surface of the molded article with an excessive amount of particles, for example, in multiple layers.

Naturally, the stretching force applied to the polymer molded article is released after the conductive particles are completely covered with the molded article.

After releasing the stretching force, the resulting polymer molded product of the present invention has an electrical resistance value of 10<7 >Ω/c/rt or less, and has extremely good electrical conductivity.

Furthermore, since the conductive particles are fixed to the surface of the molded polymer product obtained by the present invention, the particles do not peel off and the product has excellent durability.

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

Example 1 A polyurethane monofilament (750% elongation, 98% elongation recovery rate at 500% elongation) made of butane 4-diol and hexamethylene diisocyanate and having a diameter of 0.5 MAIL was moistened with dimethylformamide. 40.50.100.30 for each department
Carbon black powder was coated on the monofilament surface by immersion in a conductive carbon black powder bath with an average diameter of 1 micron under 0% elongation.

After 1 hour of coating, the stretching force was released and the film was left in a constant humidity and constant temperature room at 40% humidity and 25° C. for 24 hours to completely evaporate and remove residual dimethylformamide.

The electrical resistance value of the obtained carbon black coated yarn was measured in the above-mentioned constant humidity and constant temperature room using an electrical resistance measuring device TR-6354A manufactured by K., MINI-MULTIMETER.
Measured using

The results are shown in Table 1.

As is clear from Table 1, the product of the present invention coated with carbon black powder under elongation of 50% or more has a resistance of 107Ω/cm.
It can be seen that it has excellent conductivity as shown below.

Example 2 Copolymer of butadiene and acrylonitrile (NB
A synthetic rubber tape with a thickness of 0.8 mrn and a width of 5 mm consisting of a material (abbreviated as R) is immersed in chloroform at 50°C, which is a good solvent for NBR, and when the surface of the tape has melted, it is pulled out and the tape is The surface was coated with copper powder by immersing it in a copper powder bath with an average diameter of 3 microns under 100% elongation.

After the copper powder completely coated the tape surface, the stretching force was released, residual chloroform was removed by evaporation in the same manner as in Example 1, and the electrical resistance value was measured between arbitrary points on the tape surface.

Electrical resistance value is 3.5X104~4.3X10610Ω/
cm, and had good conductivity.

Further, even when the electrical resistance value was measured after wiping the tape three times with a bleached cloth, the value did not change at all, and the peeling resistance was also satisfactory.

Claims (1)

[Claims] A molded article made of an elastically stretchable polymer having an elastic recovery rate of 70% or more at an elongation rate of 150% or more, and coated with conductive particles by elongating the molded article by at least 50%. A method for producing a conductive polymer molded article having an electrical resistance value of crrL or less.