JP2001263497A - Conductive gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a gasket material exhibiting high sealing performance, maintaining resiliency for a long period of time, with excellent conductivity given to a rubber material. SOLUTION: In the gasket material formed of a conductive rubber material with a conductive filler added, 20-200 pts.wt. of cork grain is added to 100 pts.wt. of the rubber material to improve electromagnetic wave shielding function and sealing performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielding material which is required to have a function of shielding electromagnetic waves, and more particularly to an electromagnetic wave shielding gasket material which is required to have a function of shielding water, oil, dust and the like in addition to electromagnetic wave shielding properties.

[0002]

2. Description of the Related Art Conventionally, as a conductive gasket material for shielding electromagnetic waves, a metal net or a cloth on which metal is vapor-deposited on the surface is coated around a highly elastic core material such as urethane sponge. A gasket material having a composite structure or a rubber material filled with carbon black or metal powder is known.

[0003]

However, in a gasket material in which a sponge material such as urethane is coated with a metal net or a metal vapor-deposited cloth, the gasket material is excellent in conductivity, but the compression set of the sponge core material is large, so that the gasket material has a long compression life. There is a major drawback in that the sealing performance cannot be maintained over a long period. In addition, in rubber materials filled with carbon black or metal powder, a large amount of conductive filler must be added in order to obtain high conductivity. In order to obtain a margin, the tightening force is increased, which may cause deformation of the mating flange, which may increase the risk of impairing the sealing performance. Further, since the rubber itself is incompressible, the rubber material causes a lateral flow at the time of fastening, so that sufficient sealing properties cannot be obtained. As a countermeasure for preventing the lateral flow, a fitting mounting structure in which a concave groove is formed in the mating flange and an O-ring-shaped gasket material is mounted in the groove has been implemented. Cost, which greatly affects the cost.

The present invention has been made in view of the above-mentioned drawbacks, and a gasket material capable of imparting good conductivity to a rubber material and exhibiting high sealing performance while maintaining elasticity for a long period of time. It is intended to provide.

[0005]

The present invention will be described in detail with reference to a gasket material made of a conductive rubber material obtained by adding a conductive filler to a rubber material and imparting an electromagnetic wave shielding function. The cork particles obtained by pulverizing a natural cork bark into granules with respect to 100 parts by weight of the rubber material are used as a carbon-based conductive filler, and the cork particles are 20 to 200 parts by weight.
It is characterized by the addition of parts by weight.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Rubber materials used in the present invention include natural rubber, isoprene rubber, acrylonitrile butadiene rubber, butadiene rubber, styrene butadiene rubber, ethylene propylene rubber, acrylic rubber, chloroprene rubber, silicon rubber, and fluoro rubber. One or more of them are appropriately blended and used.

[0007] Examples of the carbon-based conductive filler of the conductive filler include carbon black, graphite, carbon fiber, and the like, and one or more of them may be appropriately mixed and used. On the other hand, metal-based conductive fillers such as silver powder, copper powder, stainless steel powder, stainless flake, aluminum flake, etc. can also obtain conductivity, but are disadvantageous in terms of weight, and have a light weight cork particle. It is not preferable because the meaning of mixing may be lost.

The number of cork grains to be added is in the range of 20 to 200 parts by weight based on 100 parts by weight of the rubber material. This is 2
If the amount is less than 0 parts by weight, the effect of reducing the rubber hardness due to the addition of cork particles and the effect of preventing the rubber material from laterally flowing at the time of fastening are difficult to be obtained. Further, when the number of added cork particles is 200 parts by weight or more, the conductivity of the cork rubber is greatly deteriorated.

The particle size of the cork particles is not particularly limited, but is preferably about 0.1 to 5 mm in diameter in order to sufficiently exhibit its characteristics of light specific gravity, impermeability and compression recovery. Particularly, those having a diameter of 0.5 to 3 mm are preferable.

[0010]

Examples and comparative examples are shown below. In a cork rubber in which cork particles are added in an amount of 20 to 200 parts by weight with respect to 100 parts by weight of the rubber material, the rubber hardness can be reduced and the lateral flow of the rubber can be prevented without a significant change in conductivity. (Examples 1 to 4) When 10 parts by weight of cork particles were added, almost no decrease in rubber hardness was recognized, and rubber lateral flow also occurred. (Comparative Example 2) Addition of 250 parts by weight of cork particles causes a significant decrease in conductivity. (Comparative Example 3)

Table 1

[0012]

According to the present invention, by adding cork particles to the rubber material, the lateral flow of the rubber is reduced, so that it is not necessary to form a groove on the flange surface as in the case of the conventional conductive rubber gasket material. A gasket can be mounted on the flange surface. Further, by adding cork particles and a carbon-based conductive filler to the rubber material, the specific gravity of the material is reduced, and the weight of the gasket material can be reduced. Further, the amount of the expensive conductive filler added per unit volume is reduced, so that the cost can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/10 C09K 3/10 QZ F Term (Reference) 3J040 FA06 FA11 HA12 HA30 4H017 AA02 AA03 AA20 AA29 AA34 AA39 AB01 AB07 AB17 AC10 AD03 4J002 AC011 AC031 AC061 AC071 AC081 AC091 AH002 BB151 BD121 BG041 CD031 DA036 FA046 FD116 GJ02

Claims (2)

[Claims] 1. A gasket material comprising a conductive rubber material obtained by adding a conductive filler to a rubber material, wherein the conductive filler is a carbon-based conductive filler, and based on 100 parts by weight of the rubber material, A conductive gasket comprising 20 to 200 parts by weight of cork particles. 2. The conductive gasket according to claim 1, wherein the carbon-based conductive filler is appropriately mixed with one or more of carbon black, graphite, and carbon fiber.