Abstract: A rubber member for coating a developing roll which is obtained by coating a coating layer component around a developing roll having a rubber substrate layer and curing the coating layer component is described. The coating layer component contains: (A) a liquid binder containing at least a polyol, an isocyanate compound and reactive silicone oil; (B) silicone rubber particles having a hardness according to JIS K6253: 1997 by Durometer A, measured instantaneously, of 20 to 80 degrees, and a rubber particle size of 0.2 to 10 pm; and a diluting solvent. A ratio of a thickness of the coating layer after curing and a particle size of the rubber satisfies: the rubber particle size/a coating layer thickness <0.3.

Abstract: An object is to provide a rubber member for coating a developing roll which is formed a uniform rough surface at a surface of the developing roll, does exert neither damage nor toner stress to the mating member or the toner while maintaining flexibility, is possible to secure a thickness which can sufficiently avoid the effect of the rubber, and can realize non-tackiness and low friction, which can be solved by a rubber member for coating a developing roll which is the rubber member for coating a developing roll obtained by coating a coating layer 13 component at around a developing roll having a rubber substrate layer 12 and curing the same, wherein the coating layer 13 component comprises a liquid binder which contains at least a polyol, an isocyanate compound and reactive silicone oil, silicone rubber particles 101 having a hardness (JIS K6253: 1997) by Durometer A (instantaneous) of 20 to 80 degree and a rubber particle size of 0.