CONDUCTIVE SPONGE ROLLER

PROBLEM TO BE SOLVED: To provide a conductive sponge rubber roller such as a transfer roller, a charging roller, a developing roller, in which non-uniform foaming is prevented from being produced in vulcanization with vapor or the like and a uniform cell size is ensured. SOLUTION: In the conductive sponge rubber roller in which a rubber layer is formed on a conductive core material, the vulcanizing speed (T10) of the rubber at 160°C is 1.2 to 2.5 min, and the decomposing temperature of a foaming agent is 140 to 165°C. In the manufacture of the conductive sponge rubber, a temperature is raised at a temperature rise rate of 35°C/min or more and vulcanization is carried out at a vulcanizing temperature of 155 to 165°C. Alternatively, the temperature is raised at a temperature rise rate of 35°C/min or more until it reaches 120°C to 130°C, and heat is once retained for 1 to 3 min. Thereafter, a temperature rises at a temperature rise rate of 25°C/min, and vulcanization is carried out at 155 to 165°C. COPYRIGHT: (C)2005,JPO&NCIPI