| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a developer that gives stabilized image quality without causing any image defect even after long-term use. Ž<P>SOLUTION: A positively chargeable developer includes at least positively chargeable toner particles containing at least a binding resin and magnetic iron oxide, and an inorganic fine powder. The developer is characterized in that the difference between the zeta potential of the positively chargeable toner particles at the pH of a dispersion liquid when the positively chargeable toner particles are dispersed in water, and the zeta potential of the inorganic fine powder at the same pH is not more than 40 mV, the unconfined yield stress (U<SB>5 kPa</SB>) in the major consolidation stress of 5.0 kPa of the developer is expressed by 0.1 kPa≤U<SB>5 kPa</SB>≤2.5 kPa; and the unconfined yield stress (U<SB>20 kPa</SB>) in the major consolidation stress of 20.0 kPa of the developer is expressed by 2.5 kPa≤U<SB>20 kPa</SB>≤5.5 kPa. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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