Patent ID: 9075340
Filing Date: 2015-07-07
Classification: G03G

Abstract:
1. A developing roller for use in an electrophotographic image forming apparatus, the developing roller comprising: a roller body having an outer peripheral surface, at least the outer peripheral surface being formed from a rubber composition comprising a styrene butadiene rubber, an ionically conductive rubber and a polar rubber as a base rubber, the base rubber comprising the styrene butadiene rubber in a proportion of not less than 10 mass % and not greater than 20 mass % based on an overall amount of the base rubber, the outer peripheral surface of the roller body having a surface roughness Ra of not less than 1.32 μm and less than 1.52 μm, wherein the outer peripheral surface of the roller body is configured so that a toner to be used for electrophotographic image formation has an adhesive force of not less than 23 nN with respect to the outer peripheral surface.