| 摘要 |
PURPOSE:To allow the control of an electrostatic charge quantity without coating spinel type ferrite with a high-polymer resin by using said ferrite as a base material and adding CaO thereto. CONSTITUTION:The CaO is incorporated at 0.1-10wt.% into the ferrite material having the compsn. consisting of 40-60mol% Fe2O3, 20-40mol% MgO, 5-20% ZnO, and 0.5-15mol% CuO. Saturation magnetization does not increase and the surface smoothness is impaired if the contents of the Fe2O3 and MgO are below the prescribed ratios. The adequate saturation magnetization is not obtainable and the Curie temp. falls if the content of the ZnO is beyond the prescribed mol%. The effect of improving the surface characteristic is not obtd. if the content of the CuO is below 0.5mol% and the fusion of the carrier particles to each other arises if the ratio exceeds 15mol%. There is substantially no effect to the electrostatic charge quantity of a toner if the amt. of the CaO to be added is below 0.1wt.% and the saturation magnetization decreases drastically if the ratio exceeds 10wt.%. The electrostatic charge quantity is freely controlled in this way without requiring the resin coating. |
