Japan Synthetic Rubber Co., Ltd.

Yoji Mori

Shoei Tsuji

Fumio Tsutsumi

Akihiko Morikawa

Yasuhiko Takemura

Itsuki Umeda

Hironori Matsumoto

Yoshiaki Kawamura

Takashi Kawata

Isao Sugita

Masato Sakai

Hidekatsu Gotoh

An ethylene-.alpha.-olefin-non-conjugated diene copolymer rubber composition comprising a low molecular weight component copolymer composed of an ethylene-.alpha.-olefin-non-conjugated diene copolymer having a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 10 to 150, an .alpha.-olefin content of 30 to 60% by weight and an iodine value of 37 to 65, and a high molecular weight component copolymer composed of an ethylene-.alpha.-olefin-non-conjugated diene copolymer having a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 100 to 500, an .alpha.-olefin content of 15 to 50% by weight and an iodine value of 3 to 15, the ratio of the iodine value of the low molecular weight component copolymer to the iodine value of the high molecular weight component copolymer being at least 4/1. The above composition can inhibit a gel from being produced during processing and achieve a high degree of cross-linking and is excellent in compression set, shape-retention and sponge surface skin.

Ethylene-.alpha.-olefin-non-conjugated diene copolymer rubber composition

A rubber composition excellent in shape-retainability also in processibility, compression set and the like, which comprises a single ethylene-.alpha.-olefin-non-conjugated diene copolymer which has (1) a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 80 to 200, (2) a weight average molecular weight/number average molecular weight ratio of 6 or more as measured by a gel permeation chromatography (GPC), and (3) a stress-retention of 0.2 or more after 100 seconds at 80.degree. C. in a compression type stress-relaxation test.

Rubber composition

A rubber composition obtained by subjecting a mixture of (I) 35-95 parts by weight of a fluoroelastomer, (II) 65-5 parts by weight of at least one member selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymer and ethylene-unsaturated carboxylic acid ester copolymer, and an organic peroxide to reaction while imparting shearing deformation to the mixture. A crosslinkable rubber composition can be obtained by compounding the above rubber composition with a crosslinking agent for the fluoroelastomer (I). The above rubber composition is superior in processability, particularly extrusion-processability, sealing property, heat resistance, steam resistance and weather resistance.

Rubber composition and crosslinkable rubber composition

An oil-resistant rubber composition comprising (A) 90 to 10 parts by weight of an unsaturated nitrile-conjugated diene rubber having a .DELTA.Tg of 58.degree. C. or more and an average bound nitrile content of 15 to 50% by weight, (B) 10 to 90 parts by weight of at least one rubber selected from the group consisting of an ethylene-propylene type copolymer rubber, a natural rubber and a polyisoprene and (C) 0 to 50 parts by weight, per 100 parts by weight of the total of (A) and (B), of at least one component (C) selected from the group consisting of a styrene polymer and a polyalkenamer. Said rubber composition is oil-resistant and excellent in mechanical properties such as tear strength, resistance to crack growth, etc.

Oil-resistant rubber composition

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Yokkaichi, Japan

Yoji Mori