| 摘要 |
PURPOSE:To uniformize surface characteristics and to eliminate fluctuations in electrostatic chargeability by welding fine spherical resin powder formed by a soap-free polymn. method on the surface of a binder resin in which fine magnetic powder is dispersed and incorporated, thereby forming a resin film. CONSTITUTION:The fine magnetic powder and the binder resin are melted and kneaded and the mixture is solidified, ground and classified to form unshaped or spherical magnetic particles. The fine spherical resin powder having the average grain size smaller than the average grain size of such magnetic particles is formed by the soap-free polymn. method. The fine resin powder formed in such a manner is electrostatically adhered to the surface of the magnetic particles and is welded thereto by application of impact force thereto to form the resin film on the magnetic particles. The uniformity of the surface condition is thereby improved and, therefore, the electrostatic charge is uniformly executed and the good image is maintained for a long period of time; in addition, a printing operation is facilitated, since the permissible range of a toner concn. is wide. |
