Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1993-01-27
1995-08-29
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525210, 525211, 525216, 525218, 525233, 525234, 525238, C08L 2316, C08L 2328, C08L 3320
Patent
active
054460980
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a covulcanizable rubber composition comprising a partially hydrogenated unsaturated nitrile-conjugated diene copolymer, a chlorinated ethylene-propylene copolymer and a vulcanizer.
BACKGROUND ART
A partially hydrogenated unsaturated nitrile-conjugated diene copolymer is well known as a rubber having good heat-aging resistance, oil resistance and rancid gasoline resistance. To utilize these good characteristics and impart other characteristics to this rubber, proposals have heretofore been made wherein the copolymer is blended with other rubbers. Among the rubber blends, a blend thereof with an ethylene-propylene-diene copolymer (hereinafter abbreviated to "EPDM") is well known as a rubber composition having good heat-aging resistance, oil resistance and ozone resistance (Japanese Unexamined Patent Publication No. 58-40332, 61-40342, 61-283639 and 62-190241). However, the partially hydrogenated unsaturated nitrile-conjugated diene copolymer rubber and EPDM have greatly different solubility parameters and hence, when mixed together, it is almost impossible that they form a uniformly dispersed mixture. Further, these copolymer rubbers exhibit different rates of vulcanization. Therefore, properties of a vulcanized rubber from the composition of these copolymer rubbers are restricted. Especially, the constant-elongation fatigue properties are not satisfactory.
BRIEF SUMMARY OF THE INVENTION
An object of the invention is to overcome the above-mentioned defects of the conventional rubber compositions and to provide a covulcanizable rubber composition comprising a partially hydrogenated unsaturated nitrile-conjugated diene copolymer, which is characterized as exhibiting an improved processing property when mixed, and as providing a vulcanized rubber having a drastically improved constant-elongation fatigue properties.
In accordance with the present invention, there is provided a covulcanizable rubber composition comprising a partially hydrogenated unsaturated nitrile-conjugated diene copolymer having an iodine value not larger than 120, a chlorinated ethylene-propylene copolymer and a vulcanizer.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a graph showing a relationship of the composition of the copolymer rubber with the number of times at which the rubber sample is broken when the constant-elongation fatigue properties are tested.
BEST MODE FOR CARRYING OUT THE INVENTION
The partially hydrogenated unsaturated nitrile-conjugated diene copolymer rubber is prepared by partially hydrogenating conjugated diene units of an unsaturated nitrile-conjugated diene copolymer rubber by a conventional method (for example, a method described in Japanese Examined Patent Publication No. 60-58242 and 62-61045), the latter copolymer rubber being prepared, for example, by an emulsion polymerization or solution polymerization procedure.
As specific examples of the unsaturated nitrile, there can be mentioned acrylonitrile and methacrylonitrile. As specific examples of the conjugated diene, there can be mentioned 1,3-butadiene, 2,3-dimethylbutadiene, isoprene and 1,3-pentadiene. If desired, the unsaturated nitrile and the conjugated diene are copolymerized with other copolymerizable ethylenically unsatureated monomers. As specific examples of the copolymerizable monomers, there can be mentioned unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid, and salts thereof, alkyl esters of unsaturated carboxylic acids such as methyl acrylate and butyl acrylate, alkoxyalkyl esters of unsaturated carboxylic acids such as methoxy acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, acrylamide, methacrylamide, N-substituted acrylamides such as N-methylolacrylamide, N,N'-dimethylolacrylamide and N-ethoxymethylacrylamide, and N-substituted methacrylamides such as N-methylolmethacrylamide, N,N'-dimethylolmethacrylamide and N-ethoxymethylmethacrylamide. Provided that the purport of the invention is not injured, the copolymerizable ethylenically unsaturat
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Fujita Haruhiko
Fukuda Hideo
Shimoda Hideyoshi
You Shiryu
Nippon Zeon Co. Ltd.
Seidleck James J.
Warzel M. L.
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