| 摘要 |
PURPOSE:To obtain a titled compsn. which provides an image having always good and stable image quality even if an environmental condition or toner density changes by sharing the respective functions for forming images to three kinds of specific particles having different grain sizes. CONSTITUTION:A binder resin and 30-80wt% ferromagnetic powder having 0.01-2mum average grain size are melted, kneaded and ground, whereby magnetic particles (B) having 40emg/g saturation magnetization, >=10<12>OMEGAcm electric resistivity at 5kV/cm electric field and >=10<10>OMEGAcm at 20kV/cm and 15-70mum avrage grain size are obtd. (A) Magnetic particles having >=40emg/g saturation magnetization and 5-200mum average grain size (e.g.; spherical iron powder coated with methyl methacyrlate resin), the component B and (C) non-magnetic particles having 5-25mum average grain size (e.g. 1 styrene base resin) are mixed in descending order of A>B>C in average grain size so as to contain 100:20- 2:10-1 A:B:C ratio based on weight. |
