Tokai Rubber Industries, Ltd.

Naoaki Sasakibara

Kadai Takeyama

Satoshi Suzuki

Kenichi Tsuchiya

Koji Yamaguchi

Yukio Ohyama

Keiichi Ikegami

Tsutomu Saito

Takenori Saito

Fumio Misumi

The charging roller has a base layer formed of an electroconductive rubber composition containing (a) a polar rubber having an unsaturated bond or an ether bond, (b) an ion carrier containing one or more phosphonium salts selected from the group consisting of phosphonium salts having the formulae (1) and (2), and (c) a cross-linker, wherein the amount of (b) component ranges from 0.1 to 10 parts by mass per 100 parts by mass of the (a) component. The formula (1) represents [(HC)(CH)P]+(CFSO)N&#x2014;, and the formula (2) represents [(HC)(CH)P]+(CFSO)&#x2014;.

Electroconductive rubber composition for electrophotographic apparatuses and charging roller for use in electrophotographic apparatuses manufactured using the same

A charging roll includes a shaft and an ionically conductive elastic layer formed around the shaft. The ionically conductive elastic layer is formed of a rubber composition free of any electron-conductive agent and containing 0.7 to 1.0 parts by weight of a peroxide cross-linking agent per 100 parts by weight of an ion-conductive rubber. The ion-conductive rubber is formed of at least one of an epichlorohydrin rubber and a nitrile rubber, and a percentage of a rubber component in the ionically conductive elastic layer measured by thermogravimetric analysis is 90% or more by weight.

Charging roll

A roll has a base material layer, a front surface layer, and stress relaxation layer. The base material layer is made of low hardness rubber material and provided on an outer circumference of a metal core. The stress relaxation layer is provided on the base material layer and made of material which is at least higher in hardness than the base material layer and larger in stretch than the front surface layer. The front surface layer is made of resin material and provided on the stress relaxation layer. The stress relaxation layer is made of rubber material containing self-crosslinking resin. The stress relaxation layer has a thickness in a range of from 5 to 50 &mgr;m, and stress not lower than 5 MPa at 10% stretch.

Roll

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Komaki, Japan

Naoaki Sasakibara