Tokai Rubber Industries, Ltd.

Kenichi Tsuchiya

Hiroki Sugiura

Satoshi Suzuki

Nobuya Yoshida

Kadai Takeyama

Masanari Umeda

Naoaki Sasakibara

Tetsuya Itoh

Shiro Miyamori

Yasuyuki Hayasaki

Atsuhiro Kawano

Masahiko Takashima

Fumio Misumi

Satoshi Tatsumi

Jiro Iwashiro

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

An electrically conductive roll includes a shaft body and at least a conductive elastic layer formed by extrusion on an outer circumferential surface of the shaft body. The conductive elastic layer is formed from at least one conductive rubber composition which includes a rubber material, a thermoplastic resin having crosslinkable double bonds and a melting point in a range from 40&#xb0; C. to 100&#xb0; C., and at least one conductive agent. The thermoplastic resin is included in an amount of 5 to 50 wt. % of a total amount of the rubber material and the thermoplastic resin.

Conductive roll

An electrically conductive roll includes a center shaft, an electrically conductive elastic layer formed on an outer circumferential surface of the center shaft, and a resistance adjusting layer formed radially outwardly of the electrically conductive elastic layer. The resistance adjusting layer is formed of a rubber composition which includes a rubber material, a thermoplastic resin having crosslinkable double bonds, at least one electron-conductive agent, at least one ion-conductive agent, and at least one electrically insulating filler. The thermoplastic resin, the at least one electron-conductive agent, the at least one ion-conductive agent, and the at least one electrically insulating filler are included in the rubber composition in respective amounts of 3-40 parts by weight, 10-150 parts by weight, not greater than 2 parts by weight, and 20-80 parts by weight, per 100 parts by weight of the rubber material.

An electrically semi-conductive roll including a center shaft and a plurality of layers formed radially outwardly of the center shaft, wherein an outermost layer of the plurality of layers which is held in rolling contact with an outer circumferential surface of a photosensitive drum is formed by using a resin composition which contains as a base resin material a fluorine-modified acrylate resin.

Semi-conductive roll whose outermost layer is formed by using fluorine-modified acrylate resin as base resin material

A charging roll comprising a center shaft an electrically conductive rubber layer formed on an outer circumferential surface of the center shaft and having a relatively low hardness a resistance adjusting layer formed radially outwardly of the conductive rubber layer and a protective layer formed radially outwardly of the resistance adjusting layer. The resistance adjusting layer is formed of a rubber composition prepared by mixing a rubber material with particles of an electron-conductive material and particles of an electrically insulating material. The rubber composition comprises 10-50 parts by weight of the electrically insulating material per 100 parts by weight of the electron-conductive material.

Charging roll whose resistance adjusting layer contains insulating particles dispersed therein

Semi-conductive roll whose outermost layer is formed by using

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Komaki, Japan

Kenichi Tsuchiya