Developing roller, process cartridge and electrophotographic image forming apparatus
Abstract:
A developing roller that suppresses contamination of the surface of a photosensitive member and also obtains a high-quality image. The developing roller includes an electro-conductive substrate, an electro-conductive elastic layer and a surface layer which are stacked in this order, wherein the surface layer has resin particles that are dispersed in a polyurethane matrix, an outer surface of the surface layer has a first protrusion originating in first resin particle and a second protrusion originating in second resin particle, wherein the first resin particle contains polyurethane, an elastic modulus E1 of the first resin particle is 100 to 2000 MPa, an elastic modulus E2 of the second resin particle is 2 to 50 MPa, a maximum height roughness Rz of the outer surface is 6 to 18 μm, and a peak vertex density Spd is 5.0×103 to 5.0×104(1/mm2).
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