| 摘要 |
PURPOSE:To provide an electrically insulating electrophotographic toner capable of increasing image-developing density and lowering fog density, by preventing electrostatic agglomeration of toner particles and enhancing fluidity. CONSTITUTION:An electrophotographic toner consisting of an electrically insulating toner particles proper and a fluidizing agent of fine powder uniformly attached over these particle surfaces is prepared by coating the vapor phase- prepared silica of which the silanol group of the surface is blocked by organosilane, on the surfaces of the toner particles by a dry type blending or the like to attach the hydrophobic silica uniformly and evenly to them, and then, covering the toner particles thus treated with a vapor phase-prepared alumina, titania, or silica having <=10<13>ohm-cm volume resistivity measured at 20 deg.C in 60% relative humidity. A preferable weight ratio of the hydrophobic silica to the vapor phase-prepared alumina, etc. is 9:1-1:9, preferably 6:1-1:6, most preferably, 5:1- 1:5, and a preferable total weight to be used for covering is 0.1-5wt%, preferably, 0.2-2wt% based on the toner particles proper in the view point of fluidity. |
