| 摘要 |
PURPOSE:To obtain images which are superior in density, resolution, etc. and are free from transfer drop-out by uniformly dispersing an electric charge control agent in magnetic toner particles and further contg. a specific amount of an electric charge control agent of the reversed polarity on the outside of the toner particles. CONSTITUTION:(A) About 30-70wt% magnetic powder of about 0.1-5 microns particle sizes of magnetite, or magnetic metals such as nickel, iron and the like, (B) about 70-30wt% a binder resin such as ethylene-vinyl acetate copolymer, and (C) about 1-10wt% an electric charge control agent are mixed uniformly, whereby magnetic toner particles are prepd. Thence, 0.1-10wt% an electric charge control agent of the reversed polarity from that of the C component is contained on the outside of such magnetic particles, whereby an intended electric charge type magnetic toner is obtained. As an embodiment for the electric charge control agents, nigrosine type dyes of positive electric charge type (e.g.; Nigrosine Base Ex), metallized dyes of negative electric charge type (e.g.; Valifast Black 3804), etc. are enumerated. |
