| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-component developer which can retain stable charging property and fluidity even at different printing ratios in long-term repetitive printing by a two-component developing method, prevents variation in toner concentration attributed to instability of fluidity even in a system in which toner concentration is controlled with a magnetic permeability sensor, prevents contamination within a machine and reduction in image density due to carrier flying, and can maintain excellent image quality. SOLUTION: The two-component developer includes a carrier and a toner, wherein the carrier is obtained by coating a ferrite core material with a silicone resin, in a volume particle size distribution of the carrier, carrier of 50% cumulative frequency has a volume particle diameter (Dc<SB>50</SB>) of 65-80μm and carrier of 90% cumulative frequency has a volume particle diameter (Dc<SB>90</SB>) of 100-120μm, the carrier has a saturation magnetization of 64-69 Am<SP>2</SP>/kg, the toner has a volume median particle diameter of 8.0-9.0μm and a coefficient of variation to a volume particle size distribution of 23-28%, and the two-component developer has a toner concentration of 5.0-10 wt.%. COPYRIGHT: (C)2009,JPO&INPIT
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