Nikaido, Marmelstein, Murray & Oram
Electrically conductive rubber material used for electrophotographic copying apparatus
 The invention provides an electrically conductive rubber material for use in an electrophotographic copying apparatus of a composition which will prevent bleeding and blooming so as to obtain a image of high quality. The electrically conductive rubber material comprises a diene type rubber and a rubber which contains no double bond in its principal chain, which rubber is cross-linked with a metallic salt cross-linking agent. A portion of the diene type rubber butadiene rubber in a proportion to the total parts by weight of rubber of 10-30 parts by weight. The proportion of the rubber containing no double bond in its principal chain to the total parts by weight of rubber is not less than 15 parts by weights. 5-100 parts by weight of carbon black per 100 parts by weight of rubber are added to serve as an electrical conductivity imparting agent. Not more than 3 parts by weight of oil ingredient, use as a softening agent, plasticizer and the like, per 100 parts by weight of rubber as measured by solvent extraction by acetone is also permitted. Preferably, the rubber containing no double bond in its principal chain is EPDM rubber. 
Sumitomo Rubber Industries, Ltd.
G C C C C C C C C C C
G03G C08L C08K C08L C08L C08L C08L C08L C08K C08K C08L
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Shunichi Hitoshi
Yabushita Itani