| 摘要 |
PURPOSE:To obtain magnetic toner with superior transferability, dispersibility, image characteristics, etc. by blending iron oxide type magnetic powder covered with a layer of oxides having different oxidation states and a thermoplastic resin. CONSTITUTION:Fe3O4 powder is slowly heated in air with stirring, maintained at about 200 deg.C for an adequate time, and cooled to convert part of the Fe3O4 surface into gamma-Fe2O3. The resulting powder is then mixed with a thermoplastic resin such as epoxy resin, styrene type resin or rosin resin and carbon black to obtain magnetic toner. The magnetic powder is preferably surface-treated by about 10-90vol% as the vol. ratio of Fe3O4/Fe2O3. The converted magnetic powder may be formed by suitably reducing Fe3O4. |
