JPS61243882A - Electrically conductive gasket - Google Patents

Abstract

PURPOSE:To improve electrical conductivity and compression properties for attaining an excellent sealing effect, by forming an electrically conductive gasket for sealing an interior casing of an electronic instrument using a composition comprising a synthetic rubber, an electrically conductive filler and a cork particle. CONSTITUTION:An electrically conductive gasket is formed using a composition comprising a synthetic rubber, an electrically conductive filler such as metallic powder, metallic fiber, metallic flake, carbon black, graphite or carbon fiber and 5-50wt% cork particle having a suitable particle diameter. An electrically conductive composite gasket can be formed by preparing two or more electrically conductive gaskets different in volumetric resistivity and compressibility from each other by using a mixture of the electrically conductive filler with the cork particle in various amount ratios and uniting them in one body.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention relates to a gas nut such as a casing that has excellent sealing properties, shields electromagnetic waves, and prevents static electricity from being charged. The present invention relates to a conductive gas nut that has good conductivity, high compressibility, and good sealing properties.

(Prior Art) Electronic equipment is extremely precise, and radioactive electromagnetic noise (hereinafter referred to as "electromagnetic waves") that enters from the outside can easily cause serious problems such as malfunction and destruction. To prevent this, noise filters are used. Electromagnetic interference is prevented by using metal materials such as steel plates with strong electromagnetic shielding properties for the housing.

In addition, static electricity that causes similar problems has been prevented by applying a composite material or conductive paint that imparts conductivity to the housing or surrounding parts, or by grounding the housing or its surroundings.

Conductive elastic gaskets are used on the joint surfaces of the casings used here, and most of the materials are made by mixing synthetic rubber with conductive fillers to form gaskets. was.

[Problem that the invention seeks to solve]

However, as mentioned above, gaskets made of synthetic rubber and conductive fillers have excellent conductivity, but because the synthetic rubber itself is incompressible, excessive deformation and lateral flow occur when it is installed and tightened, resulting in insufficient electrical conductivity. Not only does it fail to seal, but the material also ages prematurely, making it unusable for a long period of time, which is a serious drawback.

In order to avoid this drawback, foamed gaskets have been developed, but even this type of gasket has large compression set and poor compression recovery, so that satisfactory durability has not been achieved. The present invention solves these drawbacks and provides a conductive gasket composition that has excellent conductivity and compressibility.

Means for Solving Problem C] The present invention is a conductive gas nut that seals the joint surface of a sieve or a pipe body, etc. that is used to house an electronic device;・It is characterized by mixing the desired amount of fillers with excellent conductivity such as carbon black, graphite, and carbon fiber, as well as 5-50% weight ratio of cork grains refined to an appropriate particle size. It is desirable to obtain a resistance in the range of 10-2 to 109 Ω·1.

By further advancing this configuration and mixing variously adjusted conductive fillers and cork grains, at least two types of conductive gaskets with different volume resistivity and compressibility are synthesized, and these are integrated. A composite conductive gasket is constructed.

(Function) The cork used here is natural cork bark,
Its characteristics are that the entire interior is composed of independent cells and has sufficient compressibility and strong compression recovery properties.This cork bark is crushed to the desired particle size to form cork grains, and the cork grains and conductive filling A conductive gasket is formed from a composition in which the material is blended with synthetic rubber.

When this electrically conductive gasket is installed and tightened in a sealed location, the non-compressible rubber transfers deformation pressure to the cork grains containing the compression pressure. The cork grains occupy more than 50% of their cell volume with air, and although they have high compressibility, they have almost no lateral flow properties and generate a strong repulsive restoring force. Therefore, even if a large amount of powdered, fibrous, or flaky metals with extremely poor compressibility or conductive fillers such as carbon or graphite are mixed, the cork grains will exert sufficient compression recovery properties and the entire gasket will be compressed. Improves compressibility and exhibits excellent sealing effect. Of course, the conductive gasket provides the desired electrical conductivity to the sealed casing or the like by means of the conductive filler contained therein, and has the effect of blocking electromagnetic waves or static electricity.

That is, in order to prevent static electricity from being charged, the amount of the filler and cork grains that impart conductivity is adjusted, and in order to prevent the volume resistivity from 10 to 10, the volume specific resistance is When the resistance is set to 101 to 10'Ω·1, a preferable electromagnetic wave shielding effect that satisfies the required conditions can be obtained.

(Example) The following example is a conductive gasket composition formulated to prevent static electricity.

Blended NBR polymer 1oooII stearic acid 1of/Aenca
50f heat resistant anti-aging agent
Anti-aging agent 1 of I Acetylene Black 200gDOP
150g sulfur
5g accelerator
35g cork grains (0.5-2.0% diameter), 1
000F Formed into a gasket shape with the above blended composition,
Physical propertiesVolume resistivity 7X102Ω・1 Hardness 700:rxs Tensile strength 120#/d Elongation 150% Compressibility 29% Recovery rate 85% In this way, the above example has the optimum compressibility and recovery properties for sealing, and is sufficient. Although the present invention is not limited to preventing static electricity, the present invention is also applicable to lowering the volume resistivity by adjusting the conductive filler and cork grains to be mixed. It can also be easily modified to form a gasket that increases conductivity and has a strong electromagnetic wave shielding effect.

The present invention utilizes the characteristic that this volume resistivity can be changed,
Conductive fillers and cork particles are adjusted and blended into synthetic rubber to synthesize conductive gaskets with different specific volume resistivities and compressibility.1 These are molded into one piece or formed, and each is pasted after the molding.・To form a composite conductive gasket.

The conductive composite gasket formed in this way has the aforementioned good compression properties and is capable of complex conductive properties such as effectively reflecting magnetic field waves on the low frequency side, which is generally difficult to shield. (Effects of the Invention) As explained above, the present invention has excellent conductivity and has contradictory effects. O

Claims (2)

[Claims] (1) A conductive gasket that seals the joint surface of a housing or tube body that houses an electronic device; conductive gasket made of synthetic rubber, metal powder, metal fiber, metal flake, carbon black, graphite, carbon fiber, etc. 1. A conductive gasket characterized in that it is formed by mixing a conductive filler and cork grains having an appropriate particle size at a weight ratio of 5 to 50%. (2) A conductive gasket that seals the joint surface of a casing or a pipe body; conductive filler and cork grains are individually mixed into a plurality of synthetic rubbers to achieve conductive volume resistivity and compressibility. A conductive gasket characterized by forming conductive gaskets of different types and integrating them into a composite body.