| 摘要 |
PURPOSE:To reduce the edge phenomenon of a developer and to prevent deterioration of quality in the case of copying for a long time, by using an insulating spherical carrier having 5-50mum particle diameters in an electrophotographic developer consisting of a toner and the carrier. CONSTITUTION:The carrier usable for this invention has 5-50mum, preferably, 30-40mum particle diameters, preferably having a saturation magnetization of <=100emu/g, and an apparent density of <=4.5g/cc, preferably, <=2.5g/cc. It can be prepared for this use by granulating ferrite powder or iron powder together with a binder resin. In an example wherein this insulating spherical carrier is used, it is found that continuous copying operations of 100,000 sheets always give sharp images, but in a reference example wherein a conventional iron spherical carrier is used, fog occurs from nearly 50,000 sheets. |
