CONDUCTIVE RUBBER ROLL, PROCESS CARTRIDGE AND IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a conductive rubber roll that has an improved surface property after extrusion molding, compared to a conventional one.

SOLUTION: The conductive rubber roll has a core bar and a conductive elastic layer provided around the periphery of the core bar. The conductive elastic layer is obtained by vulcanizing unvulcanized rubber containing: raw-material rubber composed of a mixture of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber; and 20 to 60 pts.mass of calcium carbonate with an average particle diameter of 40 to 80 nm based on 100 pts.mass of the raw-material rubber. In the unvulcanized rubber, the point of the intersection of the curves of the storage modulus G' and loss modulus G'' of dynamic visco-elasticity at a shearing speed of 10-7to 10-3rad/sec and at a temperature of 70 to 120°C is 2.0×103to 4.0×104Pa; the MSR value of stress relaxation test at a shearing speed of 2.0×10-3to 10-1rad/sec is 0.4 or greater; and the rubber hardness of the vulcanized conductive elastic layer is 60 or less.

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