| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a developing roller, attaining compatibility between softening for reducing damage to toner and prevention of deformation due to pressing from various members in the periphery of the developing roller caused in transport, and a process cartridge for electrophotography and an electrophotographic image forming apparatus including the developing roller, which may obtain an image of high quality over a long period of time from the initial stage of image formation. <P>SOLUTION: In forming the developing roller provided with a conductive elastic layer whose surface is coated with a protective layer on a shaft core body, when the thickness of the protective layer is t, and the universal hardness in the push-in depths 0.1t, t, 10t from the surface of the developing roller having the protective layer are B, C and D, the protective layer satisfying all the following relationships is provided on the surface of the developing roller. (1) The separation area in a tape peeling test between the protective layer and the conductive elastic layer is 50% or more, (2) 0.30B>C>0.05B, (3) C>D>0.10C, (4) 3.00≤B≤50.00(N/mm<SP>2</SP>), and (5) 5≤t≤50μm. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
