JPS6059681B2 - conductive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive material, and more particularly to a conductive material using short conductive fibers.

As a conductive material using conductive short fibers, for example, one in which a deposit of conductive short fibers is filled with resin is known.

However, in such conventional conductive materials, resin, which is an electrical insulator, is attached so as to wrap around the contact points between conductive short fibers, so the proportion of conductive short fibers (hereinafter referred to as short fiber content) in the conductive material is The disadvantage is that even if the electrical conductivity (referred to as the electrical conductivity) is quite high, the electrical conductivity is not very high. An object of the present invention is to solve the above-mentioned drawbacks of conventional conductive materials and to provide a conductive material that exhibits high electrical conductivity even when the short fiber content is low.

The above-mentioned object of the present invention has a deposit of conductive short fibers and a resin or elastomer filled with this deposit, and the conductive short fibers are integrated with each other by a carbide at their intersection points. This is achieved by a conductive material characterized in that it is bonded to and electrically connected to the conductive material.
The conductive material of the present invention will be described in detail. The conductive short fibers are made of metal fibers such as gold fibers, silver fibers, stainless steel fibers, and nickel fibers, and conductive fibers such as carbon fibers and graphite fibers.

Plating metals such as gold, silver, nickel, etc. on the surface of glass fibers, silicon carbide fibers, boron fibers, organic high elastic fibers, polyamide fibers, polyester fibers, etc., which themselves have no or almost no conductivity, The fibers may be made conductive by thermal spraying, vapor deposition, etc., and in the present invention, such fibers are also referred to as conductive fibers. The conductive fibers described above are usually in the form of short fibers having a diameter of several microns to several tens of microns and a fiber length of several hundred microns to several hundred millimeters.

The deposit is, for example, like a mat, in which short conductive fibers such as those described above lie in random directions in a two-dimensional plane.

The conductive short fibers may be oriented in a direction intersecting a two-dimensional plane. The conductive short fibers constituting such a deposit are preferably dispersed as uniformly as possible. Further, the porosity of the deposit is preferably about 60 to 99 (%). That is, if the porosity is too low, resin or elastomer will not penetrate well, and if the porosity is too high, the conductivity will decrease. The carbide that binds conductive short fibers together at their intersections in the deposit is
Examples are those obtained by firing polyvinyl alcohol, phenolic resin, furan resin, pitch, etc.

The drawing schematically shows how the conductive short fibers 2, 2 are bound together by the carbide 1. The carbide 1 is attached so as to cover the intersections of the conductive short fibers 2, 2. The resin filled in the deposit in which conductive short fibers are bound to the sorcerous body by carbide at their intersections is a thermosetting resin such as epoxy resin, unsaturated polyester resin, phenol resin, or polyimide resin. Resins and thermoplastic resins such as polyamide resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, acrylonitrile, butadiene, and styrene resin. The elastomer may also include acrylic-butadiene elastomer, silicone elastomer, chloroprene elastomer, and ethylene propylene elastomer. The use of such elastomers provides flexibility to the conductive material. The conductive material of the present invention as described above is manufactured, for example, as follows.

That is, the conductive short fibers are dispersed using turbulent airflow or water flow, and are then dropped onto a wire mesh and deposited thereon.

Next, this deposit is impregnated with an aqueous or alcoholic solution of polyvinyl alcohol or phenol resin, dried, and processed into a predetermined shape.
) to carbonize the polyvinyl alcohol or phenol resin, and bind and integrate the conductive short fibers at their intersections. The integrated deposit is then filled with a resin or elastomer, for example by vacuum impregnation. As explained above, in the conductive material of the present invention, since the conductive short fibers constituting the deposit are bound to the saw body by the carbide at the intersection points, the conductive short fibers are bound to each other by the carbide. This means that they are completely electrically connected, and exhibit high electrical conductivity even when the short fiber content is low.

The conductive material of the present invention can be used in a wide range of applications, such as cases of electronic devices, antennas, gaskets for waveguides, and key switches for electronic desktop calculators.

Example As a conductive short fiber, carbon fiber "Trega" T-300 manufactured by Toray Industries, Inc. (number of single yarns: 300) cut into a length of about 12 m was used.
Using a turbulent stream of water, each single fiber was dispersed and dropped onto a wire mesh to be deposited.

Next, the above deposit of short carbon fibers is impregnated with a 3% aqueous solution of phenolic resin, air-dried, the phenol resin is further cured, and then heated at about 1000°C for about 1 hour to carbonize the phenol resin. did.

As a result, the short carbon fibers were bound together by the phenolic resin carbide and electrically connected.The porosity of the deposit after binding was approximately 80%. Next, the deposit after binding the short fibers with carbide is impregnated with epoxy resin by a vacuum impregnation method, and further heated at about 130° C. for about 2 hours to harden the epoxy resin. , a conductive material according to the present invention was obtained.

Next, when we measured the resistivity of the above conductive material, we found that
It was approximately 3.3×10 −2 Ω●Cm.

[Brief explanation of the drawing]

The drawing is a schematic perspective view schematically showing how conductive short fibers are bound together by carbide in the conductive material according to the present invention. 1: Carbide, 2: Conductive short fiber.

Claims (1)

[Claims] 1 It has a deposit of conductive short fibers and a resin or elastomer filled with this deposit, and the conductive short fibers are bound together by carbide at their intersection points, and the conductive short fibers are bonded together by carbide at their intersection points, A conductive material characterized by being connected to each other.