JP2001036285A - Electromagnetic shielding rubber sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-use electromagnetic shielding rubber sheet which is inexpensive, excellent in electromagnetic shielding performance and flexible. SOLUTION: The electromagnetic shielding rubber sheet comprises carbon cloth as a core material, which is covered by vulcanized conductive rubber having a composition of 100 parts of ethylene propylene rubber, 50 to 80 parts of conductive carbon black, 15 to 25 parts of paraffin-based oil, 0.5 to 2.0 parts of stearic acid, 3.0 to 10.0 parts of zinc oxide, 0.5 to 5.0 parts of polyethylene glycol, 0.5 to 10.0 parts of vulcanization accelerator and 0.3 to 3.0 parts of sulfur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber sheet for electromagnetic shielding.

[0002]

2. Description of the Related Art With the spread of personal computers and other various electronic devices, it has become an important issue to protect those electronic devices and their electronic components from static electricity and radio interference. Therefore, various electromagnetic shielding materials have been developed and provided, but those with excellent electromagnetic shielding performance are expensive,
At present, it has not been used on a daily basis because of its thickness and poor flexibility.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above description, and has as its object to provide an electromagnetic shield which is inexpensive, has excellent electromagnetic shielding performance, and is flexible and easy to use. To provide a rubber sheet for use.

[0004]

The above object can be attained by a rubber sheet for an electromagnetic shield comprising a carbon cloth as a core material and covering the core material with a vulcanized conductive rubber having the following composition. Ethylene propylene rubber 100 parts Conductive carbon black 50 parts or more and 80 parts or less Paraffinic oil 15 parts or more and 25 parts or less Stearic acid 0.5 parts or more and 2.0 parts or less Zinc oxide 3.0 parts or more and 10.0 parts or less Polyethylene glycol 0.5 parts or more and 5.0 parts or less Vulcanization accelerator 0.5 parts or more and 10.0 parts or less Sulfur 0.3 part or more and 3.0 parts or less

It is also recommended that a fatty acid-based processing aid be added to the conductive rubber having the above composition in an amount of from 0.3 part to 1.0 part in order to improve mold releasability.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A carbon cloth as a core material of a rubber sheet for an electromagnetic shield according to the present invention is made of a plain weave using a bundle of carbon fibers or a twisted carbon yarn.
The cloth is made of satin weave, twill weave, or the like. For example, carbon cloth (trade name: Torayca) manufactured by Toray Industries Inc. shown in Table 1 below can be used. When a prototype was manufactured using the fabric number CO6343, good results were obtained.

[0007]

[Table 1]

The above-mentioned carbon cloth is used as a core material, and a conductive rubber having the following composition is applied to the carbon cloth so as to sufficiently penetrate between the fibers of the carbon cloth, and vulcanized while heating to 160 to 170 ° C. And got the final product. Ethylene propylene rubber 100 parts Conductive carbon black 60 parts Paraffin oil 20 parts Stearic acid 1 part Zinc oxide 5 parts Polyethylene glycol 1 part Fatty acid processing aid 0.5 part Vulcanization accelerator 3.2 parts Sulfur 1.4 parts

As the conductive carbon black, for example, "Denka Black (trade name)" manufactured by Denki Kagaku Kogyo Co., Ltd. and "Ketjen Black EC (trade name)" manufactured by Lion Akzo Co., Ltd. are preferably used. By adding these conductive carbon blacks, the conductivity of the product sheet can be significantly improved, and the electromagnetic shielding performance can be improved.

[0010] The paraffinic oil is added as a softening agent for adjusting the hardness, and specifically, for example, a process oil (trade name: PW-380) manufactured by Idemitsu Co., Ltd. is suitably used. Its characteristic is that the specific gravity (15/4 ℃) is 0.
8769, color ASTM (Saybolt) +30, flash point (COC)
Is 300 ° C, kinematic viscosity (c.St) is 381.6 at 40 ° C, 30.1 at 100 ° C
0, pour point -15.0 ° C, total acid value (mgKOH / g) 0.01 or less,
The aniline point is 144.0 ° C, the viscosity specific gravity constant is 0.7942, the refractive index is 1.4806, the refraction intersection is 1.0438, and the sulfur content (wt%) is 6 pp.
m, average molecular weight 746, ring analysis (ndM) 0% C _A ,
27.0% C _N and 73.0% C _P.

[0011] Stearic acid is added for the purpose of improving the dispersibility and wear resistance of carbon and for the purpose of softening. Zinc oxide is added as a vulcanization accelerator in sulfur vulcanization of rubber. Polyethylene glycol is added as a vulcanization accelerator and activator. Fatty acid-based processing aids are added to improve mold releasability, and specifically, Stractol or the like is used.

As the vulcanization accelerator, thiazoles (for example, N-cyclohexyl-2-benzothiazole sulfenamide existing chemical substance number (5) 256), thiurams (for example, Di
pentamethylenethiuramtetrasulfide Existing chemical substance number (5) 793), dithiocarbamates (eg, Zi
nc dibutyldithiocarbamate Existing chemical number (2) 2
122) and the like are mixed and used at an appropriate ratio.

The electromagnetic shielding performance of the rubber sheet for electromagnetic shielding according to the present invention manufactured as described above is shown by the graphs of FIGS. In FIG. 1, "101-
"M" is a plain weave, "Shield H" is the vertical shield performance, and "Shield V" is the horizontal shield performance. Further, in FIG. 2, “910-M” is vertical and horizontal weave.

The present invention is configured as described above.
According to the present invention, it is possible to provide a rubber sheet for electromagnetic shielding which is inexpensive, has excellent electromagnetic shielding performance, and is flexible and easy to use.

[Brief description of the drawings]

FIG. 1 is a graph showing the electromagnetic shielding performance of one embodiment of the rubber sheet for electromagnetic shielding according to the present invention.

FIG. 2 is a graph showing the electromagnetic shielding performance of another example of the rubber sheet for electromagnetic shielding according to the present invention.

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Claims (1)

[Claims] 1. An electromagnetic shielding rubber sheet comprising a carbon material as a core material and a vulcanized conductive rubber having the following composition. Ethylene propylene rubber 100 parts Conductive carbon black 50 parts or more and 80 parts or less Paraffinic oil 15 parts or more and 25 parts or less Stearic acid 0.5 parts or more and 2.0 parts or less Zinc oxide 3.0 parts or more and 10.0 parts or less Polyethylene glycol 0.5 parts or more and 5.0 parts or less Vulcanization accelerator 0.5 parts or more and 10.0 parts or less Sulfur 0.3 part or more and 3.0 parts or less