| 摘要 |
PURPOSE:To provide a toner carrier for electrophotography having improved electrical resistance, by heat-treating a ferrite composed of CuO, ZnO and Fe2O3 at specific molar ratios. CONSTITUTION:Mixed powder having a composition of 5-30mol% of CuO, 10- 30mol% of ZnO and 45-70mol% of Fe2O3, wherein a part of the composition may be substituted with one or more kinds of metals having >=1 valence, is granulated and calcined. The produced ferrite is heat-treated in nitrogen atmosphere, etc. to obtain the objective ferrite carrier for electrophotography. The ferrite carrier obtained by this treatment has an electrical resistance of 10<2>- 10<13>OMEGA-cm, and the toner carrier prepared by this treatment has a saturation magnetization of about >=10emu/g, a magnetic permeability of about >=10, a Curie temperature of about >=100 deg.C, and particle strength of about >=1,000g/cm<2>, etc. |
