| 摘要 |
PURPOSE:To permit long-period formation of a high-density image by consisting the titled developer of a carrier, toner particles which are electrified positive by the triboelectrification with the carrier, fine hydrophilic alumina particles, and fine hydrophobic silica particles. CONSTITUTION:This developer is constituted of the carrier, the toner particles which are electrified positive by the triboelectrification with the carrier, the fine hydrophilic alumina particles and the fine hydrophobic silica particles. Alumina which is not subjected to a surface treatment is used for the hydrophilic alumina. The alumina which has 0.010-1.000mum average grain size is satisfactory and is used in an amt. ranging 0.1-3.0wt%, more preferably 1.0-2.0wt% range by the weight of the toner particles. Silica subjected to a hydrophobic treatment of the surface is used as the hydrophobic silica and is satisfactory if the average grain size thereof is in a 0.005-1.000mum range. Said silica is used at 1-30wt% by the weight of the hydrophilic alumina. The long-period formation of the high-density image is permitted for a long period of time. |
