| 摘要 |
PURPOSE:To prevent the lack of density, carrier attraction and void by specifying the volume resistivity of a mixture composed of two kinds of spheroidal iron powders in a saturation magnetization state which are regulated in the shapes and average grain size of toners. CONSTITUTION:The volume average grain size of the toner is specified to 5 to 15mum and the ratio of the volume average grain size Dv and number average grain size Dp is specified to >=2.0 Dv/Dp. In addition, the spheroidal iron powder is formed of the mixture composed of the spheroidal iron powder A having 80 to 200mum average grain size and >=200emu/g saturation magnetization and the spheroidal iron powder B having <200emu/g saturation magnetization. The ratio of the volume resistivity of the spheroidal iron powder A and the volume resistivity Rb of the spheroidal iron powder B is specified to >=10<2> Rb/Ra and the volume resistivity Rc of the mixture composed of two kinds of the iron powders is specified to 10<5> to 10<12>OMEGA.cm. The lack of density, carrier attraction and void are prevented in this way. |
