JPH02105886A - Conductive gasket composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which is excellent in airtightness and heat resistance, is an elastic body, has a high compressibility and good sealing properties, can shield electromagnetic waves and can prevent the buildup of static electricity by mixing a rubber with a graphitization product of a vapor growth process carbon fiber. CONSTITUTION:A synthetic rubber and/or a natural rubber is mixed with 1-99 pts.wt., per pt.wt. former, graphitization product of a vapor growth process carbon fiber (which has a diameter <=5mum, desirably 0.01-0.5mum and a length which is not particularly limited but is usually <=5000mum, or a product formed by breaking, cutting or grinding said fiber, wherein the purity of carbon is desirably at least 99.5%, the degree of graphitization is height and a lattice constant is 6.78-6.72) to obtain a conductive gasket composition which can seal the bonding faces of a box, a pipe or the like for housing an electronic device therein. This composition is excellent in airtightness and heat resistance, is an elastic body, and has a sufficient conductivity, a high compressibility and good sealing properties.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a gasket that has excellent airtightness and heat resistance, blocks electromagnetic waves, and prevents static electricity. The present invention relates to an electrically conductive gasket composition having good sealing properties and high compressibility.

(Prior Art) Since electronic devices are extremely precise, radiated electromagnetic noise entering from the outside can easily cause malfunctions and serious damage. To prevent this, a noise filter is installed and the housing is made of metal material such as steel plate with strong electromagnetic shielding properties to prevent electromagnetic interference. In addition, static electricity, which causes similar problems, has been prevented by methods such as using composite materials that give conductivity to the housing or surrounding parts, applying conductive paint, or grounding.

On the joint surface of the casing used here, a gasket was formed by mixing a conductive filler, metal powder, metal fiber, metal flake, Kazen black, etc. with synthetic sam.

(Problems to be Solved by the Invention) However, as mentioned above, conductive gaskets made of synthetic and natural beams and conductive fillers have excellent conductivity, but the rubber itself is incompressible, so when installed, This has serious drawbacks, such as excessive deformation and lateral flow caused by tightening and failure to achieve a sufficient seal, and premature aging of the material, making it unsustainable for long-term use.

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 properties, so that satisfactory durability has not been achieved.

The present invention eliminates these drawbacks and provides a conductive gasket composition that has excellent conductivity, radiation shielding properties, compressibility, morphological stability, and material antiaging properties.

(Means for solving the problem) The present inventors have developed a vapor-grown carbon fiber graphitized material as a new carbon material, and the characteristics of this material.
While conducting basic research on reactivity, they also conducted various practical tests focusing on the unique morphology and chemical and thermal stability of this fiber. It was discovered that the properties act specifically and that excellent sealing properties can be achieved depending on the state of dispersion with other substances, and as a result of further study, the present invention was arrived at.

The present invention is a conductive gasket composition for sealing the bonding surface of a housing or a tube body, etc. that houses an electronic device, and the composition is composed of synthetic rubber and natural rubber mixed with graphitized vapor-grown carbon fiber. This is a conductive gasket composition formed by mixing in a weight ratio of 99%.

A conductive gasket composition is obtained.

In the present invention, the graphitized material of vapor grown carbon fiber is
It is a graphitic material obtained by heat-treating a fibrous carbonaceous material such as a hydrocarbon in the presence of a catalyst and growing it in a vapor phase, that is, a vapor-grown carbon fiber. The graphitized material of the vapor-grown carbon fiber of the present invention can be found in various forms such as fibrous, crushed or cut, and when the fiber is observed with an electron microscope, the core part is The graphitized material of the vapor grown carbon fiber of the present invention has a unique shape consisting of a tree-ring-like carbon layer surrounding it. , which has undergone processing such as crushing, cutting, etc.

The graphitized vapor grown carbon fiber of the present invention preferably has a diameter of 5 μm or less, generally 0.01 to 4 μm, particularly 0.01 to 2 μm, and more preferably 0.01 to 1 μm.
The fiber length is most preferably 0.01 to 0.5 μm, and there is no particular restriction on the length of the fiber. Generally, it is 500 μm or less, but it may be shorter than 100 μm or 100 μm.
It may be m1 or 1.0 μm, and fibrous materials obtained by crushing, cutting, or pulverizing this into shorter lengths, or granular or irregularly shaped materials can also be used.

The graphitized vapor grown carbon fiber of the present invention has a high carbon purity, generally 98.5% or more, particularly 99% or more, and most preferably 99.5% or more.

In addition, the graphitized material of the vapor grown carbon fiber of the present invention is a highly graphitic material, and furthermore, in the structural analysis by X-ray analysis, the graphitized material has a lattice constant of 6.88 or less. , preferably 6.86 or less, particularly preferably in the range of 6.80 to 6.70, most preferably 6.78 to
It is in the range of 6.72.

The graphitized product of the vapor grown carbon fiber of the present invention can be obtained by heat treating the vapor grown carbon fiber at a high temperature, and the heat treatment temperature is 1500°C or higher, preferably 17°C.
00°C or higher, particularly 2000°C or higher), and the most preferred range is 2100 to 3000°C.

In the present invention, the gasket composition containing the graphitized material of the vapor grown carbon fiber is a composition in which the graphitized material of the vapor grown carbon fiber is present as a component of the conductive gasket composition. , the amount of graphitized material of the vapor grown carbon fiber in the composition ranges from 1 to 99% in the solid components of the composition.
% by weight. Preferably 3.0 to 99.0
% by weight of the composition, most preferably 4.
It is 0 to 98% by weight.

In the present invention, the effect of graphitized vapor grown carbon fiber is to improve the airtightness, heat resistance, oil resistance, antifreeze resistance, chemical resistance, solvent resistance, etc. of the conductive gasket composition. In addition, it is excellent in dispersion and bonding with the d-inder used in the composition, and furthermore, it has the effect of improving the mechanical strength of the composition, and these are combined to appear as a synergistic effect.

In order to maximize such effects, it is preferable that the graphitized material of the vapor-grown carbon fiber is used in an extremely fine state and in the form of fibers, since the effects are remarkable. In this case, the diameter of the fibers is not small, and the ratio of fiber length/fiber diameter is 5 or more, preferably 10 or more, particularly 20 or more, and most preferably 80 or more.

As mentioned above, the gasket composition of the present invention is characterized by containing a graphitized material of vapor grown carbon fiber, but the conductive gasket composition also includes: Fibers other than graphitized carbon fibers, fillers, agents and additives thereof, etc. can be selected and used as required.

In particular, the Nono inder is used within the scope of the purpose of the present composition. Organic resins and rubbers are used, and shims are particularly preferably used, for example,
Acrylic rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, chloroprene rubber, fluorine rubber,
Synthetic rubbers such as shrimp chlorophyllin rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, ethylene propylene rubber, ethylenezolopylene diene rubber, and silicone rubber, and natural rubber can be mentioned.

Nono Inder is used to bond graphitized vapor grown carbon fibers, and also to bond fibers and fillers other than graphitized vapor grown carbon fibers, which are used as needed. Although it is a necessary material, if used in excess, it will reduce the heat resistance and stress relaxation properties of the gasket, so the amount used should be determined in balance with the bonding effect. In general,
1. per 100 parts by weight of graphitized material of vapor grown carbon fiber.
The range is preferably from 0 to 1000 parts by weight, particularly preferably from 4.0 to 900 parts by weight, and most preferably from 5 to 500 parts by weight.

Various organic and inorganic fibers can be used as the vapor-grown carbon fibers other than graphitized fibers, but fibers with excellent heat resistance are preferable, such as various ceramic fibers/1-1 quartz. Glass fins - rock wool, stainless steel fins - carbon fiber, alumina fiber
Alumina silicate finose, other inorganic fibrous materials such as asbestos, and organic fibers such as kynor fiber, aramid fiber, and polyimide fiber can also be used.
If dust causes a decrease in heat resistance, airtightness, chemical resistance, etc., it is necessary to consider reducing the amount used or not using these fibers as much as possible within the purpose of using them.

In addition, various fillers, chemicals, and additives that have been conventionally used in gasket compositions can be used. If the amount used is excessive, there is a risk of degrading the gasket's properties, so the amount must be appropriately controlled depending on the purpose of use.

The graphitized vapor-grown carbon fiber used here has sufficient compressibility and strong compression recovery in terms of morphology. In addition, without adding metal powders, fibers, or flakes, the graphitized vapor-grown carbon fiber alone provides compressibility, airtightness, anti-aging properties, and
Corrosivity is improved.

The strong compressive recovery properties of graphitized vapor-grown carbon fibers increase the compressibility of the entire gasket and provide an excellent sealing effect.

Of course, the conductive gasket composition is intended to provide the desired electrical conductivity to the casing sealed by the vapor-grown carbon fiber graphitized material contained therein, and has the effect of blocking electromagnetic waves or static electricity.

That is, in order to prevent static electricity, the volume resistivity value is adjusted by adjusting the blending amount of the graphitized material and filler of the vapor-grown carbon fiber that imparts conductivity and the synthetic rubber or natural rubber. It is sufficient to mix the resistivity so that it is in the range of 101 to 10 Ω・tan, and in order to prevent electromagnetic interference, the volume resistivity can be adjusted to 10'''3 to 10 Ω.
By setting it to 2Ω·α, a preferable electromagnetic wave shielding effect that meets the required conditions can be obtained.

(Example) The present invention will be explained below using examples.

Example 1 Vapor grown carbon fiber with a diameter of 0.05 to 0.1 μm (trisacetylacetonate iron and benzene were grown at 1400'C)
) was synthesized in a floating state at 2400°C.
A graphitized product with a carbon content of 99% and a lattice constant of 6.74 was obtained by heat treatment, which was slightly crushed to facilitate dispersion.
And, when observed with an electron microscope, the fiber length is substantially 5.0μ.
A graphitized product of vapor-grown carbon fiber having a size of 50 m or more was obtained. A conductive gas kerato composition for preventing electromagnetic interference was prepared and evaluated using the graphitized material of the vapor-grown carbon fiber in the following proportions.

Blend Amount> NBR Polymer Zinc Stearate OP 00t f f 0f Graphitized product of vapor grown carbon fiber 1002 The above blended composition was formed into a gasket shape, and the obtained physical properties are shown below.

Volume resistivity value 2.3X10-2Ω・m Hardness
80” JIS tensile strength 211Ky10n2 elongation
160% Compression rate 32% Recovery rate 91% Example 2 The graphitized material of the vapor grown carbon fiber used was the same as in Example 1, and the blending amount was as shown below to form a conductive gasket composition for preventing electromagnetic interference. Created and evaluated objects.

Blend amount> NB Polymer 100? Stearic acid 1 to zinc white
3fDOP
10 f accelerator
2f vapor phase grown carbon fiber graphitized product 7
f The above blended composition was formed into a gasket shape, and the obtained physical properties are shown below.

Volume resistivity value 1.6X10'Ω・ω hardness
88°JIS tensile strength 230 K9/, Z elongation
142% Compression rate 29% Recovery rate 88% From the examples, the conductive gasket composition using the graphitized material of vapor-grown carbon fiber is effective in reflecting magnetic field waves on the low frequency side, which is generally considered difficult to shield. The material can be used as a shielding material in a wide range of fields, and can be used to meet complex conductivity requirements such as electrical conductivity.

(Effects of the Invention) The conductive gasket composition of the present invention has excellent conductivity, electromagnetic shielding properties, airtightness, heat resistance, oil resistance, antifreeze resistance, chemical resistance, solvent resistance, aging corrosion resistance, etc. In addition, the composition has good mechanical strength, and the present invention is a gasket composition that has excellent electrical conductivity and good compressibility, which is a contradictory effect, and completely shields electromagnetic waves. It is an ideal conductive gasket composition that can provide long-term sealing due to its antistatic properties and strong compression recovery properties, and is extremely useful in industrial applications, particularly in electronic equipment.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] A conductive gasket composition for sealing the joint surfaces of a housing or a tube body, etc., in which an electronic device is installed, which is made by adding graphitized vapor-grown carbon fiber to synthetic rubber or natural rubber from 1 to 99%.
Conductive gasket composition formed by mixing % weight ratio