Nippon Zeon Company, Ltd.

Tetsuo Waku

Akio Ueda

Nagatoshi Sugi

Tetsu Ohishi

Hiromitsu Kikuchi

Keiji Komuro

Souichi Suzuki

Michiharu Yogosawa

Takeshi Ooishi

A rubber covered roll of a structure that a rubber layer is formed on the surface of a roll-like base is provided. The rubber layer is a layer formed of a vulcanizate of a rubber composition comprising 25-95 wt. % of copolymer rubber (A) obtained by copolymerizing 28-70 mol % of an alkylene oxide, 28-70 mol % of an epihalohydrin and 2-15 mol % of an ethylenically unsaturated epoxide, and 5-75 wt. % of unsaturated rubber (B). The rubber covered roll does not contaminate any photosensitive member, stably has a low electric resistance, and is low in dependence of electric resistance on environment and in hardness. An image-forming apparatus equipped with the rubber covered roll as a development roll or charging roll, and a rubber composition for the rubber covered roll are also provided.

Rubber covered roll, rubber composition, and image-forming apparatus

A rubber composition for tire treads includes (Ia) an oil-extended rubber having a Mooney viscosity (ML.sub.1+4, 100.degree. C) of 20 to 70 which is prepared by adding 20 to 80 parts of a hydrocarbon oil to 100 parts by weight of a rubber terpolymer which is composed of 2 to 13% by weight of combined styrene, 15 to 70% by weight of combined 1,3-butadiene and 17 to 83% by weight of combined 1,3-pentadiene with the dienes having a total 1,4-bond content of at least 65 mole%, (II) vulcanization additives, and (III) 30 to 110 parts by weight, per 100 parts by weight of the oil-extended rubber (Ia), of a carbon black for rubber having an average particle diameter of not more than 60 m.mu. the rubbery copolymer has a glass transistion temperature of -70.degree. to -20.degree. C., and is produced by emulsion-polymerization at 0.degree. to 30.degree. C.

Rubber composition for tire treads

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Kawasaki, Japan

Tetsuo Waku