| 摘要 |
PURPOSE:To restrain change of chargeability characteristics and to obtain an image high in density without causing toner scattering and image fog by specifying the range of conductivity of the developing toner comprising a binder resin, a carbon black and a carbon black dispersion stabilizer both contained in the binder. CONSTITUTION:The spherical electrostatic charge developing toner comprises the binder resin and the carbon black and the carbon black dispersion stabilizer contained in the binder and it has a conductivity of 5X10<-9> - 5X10<-11>S/cm. When it is set in this range, a large amount of charge triboelectrified because of good fluidity is properly moderated and stable chargeability characteristics is obtained. Since the carbon black has hydroxyl and carboxylic groups and is deteriorated in compatibility with a monomer for constituting the lipophilic binder resin, and in order to allow the carbon black to stably exist in the monomer, the monomer having the carbon black immersed is prepolymerized in advance to form a grafted carbon black, thus permitting the obtained toner to be superior in chargeability characteristics and a high-quality image to be obtained without scattering of the toner and image fog. |
