Tokai Rubber Industries, Ltd.

Tetsuya Itoh

Wataru Imamura

Nobuya Yoshida

Saburou Hayashi

Takafumi Yamamoto

Kenichi Tsuchiya

Hiroki Sugiura

Atsuhiro Kawano

Masahiko Takashima

Masahiko Itoh

Satoshi Tatsumi

Jiro Iwashiro

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.

Conductive roll

A conductive roll sequentially has a conductive layer of an elastic material, a resistance adjusting layer, and a protective layer which are formed on an outer periphery of a shaft. The resistance adjusting layer is formed from a composition containing 10 to 150 parts by weight of an electron conductive agent, not more than two parts by weight of an ion conductive agent and 20 to 80 parts by weight of an insulating filler, relative to 100 parts by weight of nitrile rubber, or nitrile rubber hydride as a base material. The roll has a properly controlled environment dependence of its electric resistance, and avoids any trouble, such as enlarged picture defects, when employed in an electrophotographic process.

A charging roll which is held in contact with an outer circumferential surface of an image bearing medium for charging the surface of the image bearing medium by application of a DC voltage and an AC voltage which is superimposed on the DC voltage, the charging roll comprising: a center shaft; an electrically conductive base layer formed on an outer circumferential surface of the shaft; an outer structure formed on an outer circumferential surface of the conductive base layer; and the charging roll having Asker C hardness of less than 48 degrees as measured upon application of 1 kg load thereto and micro rubber hardness in a range of 65-85 degrees as measured upon application of 33.85 g load thereto.

Charging roll

Growing community of inventors

Komaki, Japan

Tetsuya Itoh