| 摘要 |
PURPOSE:To provide a developer with an uniform charge and obtain a stable image even in the case of repeatedly using it by providing a coating layer containing a positively electrifying resin to the developer, a carbon conductive material, and a negatively electrifying material to the developer on the surface. CONSTITUTION:As a positively electrifying resin, phenol resins, epoxy resins, polycarbonate resins, and the like are used, and, in general, any material causing a straight polar frictional electrification to a developer may be used. As a carbon conductor, carbon black is added in an amount of 5-50 parts by weight to 100 parts by weight of the resin to conductor negative electrification by the friction with the developer. The work function Wf (eV) of the negatively electrifying material and the work function Wft (eV) of the developer satisfy the relation of 0<(Wf-Wft)<=5(eV). The adding materials within this range include polytetrafuloroethylene resins, polyethylene resins, silicone resins and the like. Thus, an image of high quality can be obtained over a long period.
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