| 摘要 |
PURPOSE:To enhance image quality by widening size distribution of toner particles, changing triboelectrification treatment for giving negative chargeability in accordance with the diameters of the toner particles, and averaging the charge amt. of each toner particle per unit weight. CONSTITUTION:A thermoplastic resin and a colorant are mixed to prepare a toner wide in particle size distribution. The toner is classified into larger and smaller diameter fractions, each is subjected to treatment for giving negative chargeability in conditions different from each other and mixed so as to average a charge amt. of each particle per unit weight. For example, a chargeable fine powder, such as hydrophobic silica, is added to the toner fraction having 10- 25mum size distribution in an amt. of 0.3-1wt% of this toner, and a smaller amt. of chargeable powder is added or a less chargeable fine powder, such as alumina, is added to an amt. of smaller diameter toner to adjust each charge amt. of both toner fractions to a same level. |
