| 摘要 |
PROBLEM TO BE SOLVED: To provide an excellent developing roller causing no image density irregularities in a halftone image part, even when printing is performed after the developing roller is left under a high temperature and high humidity environment (for instance, 30°C and 80%RH), and causing no black spot and white spot in the halftone image part, even when a large number of sheets are printed, so that a high-quality print image is continuously obtained. SOLUTION: In an electrophotographic developing roller configured in such a manner that a cover layer having at least a conductive agent and a resin is directly formed on the circumference of a conductive shaft body, the conductive shaft body satisfies the following conditions: (1) the surface of the conductive shaft body is a nickel plated layer formed by an electroless nickel plating method; (2) the film thickness of the nickel plated layer is 2-8μm; and (3) the corrosion resistance of the conductive shaft body after the nickel plated layer is formed has a rating number of 6 to 10 in the salt spray test. COPYRIGHT: (C)2008,JPO&INPIT |
