ELECTROPHOTOGRAPHIC DEVELOPER

摘要

PURPOSE:To obtain the excellent electrophotographic developer having excellent developability and developer life by eliminating the need for replenishing carriers at the time of running and stabilizing the electrifying property of a toner during the fluctuation in humidity. CONSTITUTION:(1) The grain size distribution of the toner of the electrophotographic developer having the toner and the carrier is regulated and the volumetric average grain size of the toner is set to 4 to 10mum. The toner particle group of <=4mum satisfies the following equation: N/V=-0.32N+k, where N is the number of pieces % of the toner particles having <=4mum grain size and a positive number from 17 to 20; V is volumetric % of the toner particles having <=4mum grain size; k denotes a positive number from 13 to 20. (2) The carrier has a core material formed by dispersing a magnetic material into a binder resin and the resin coating the surface of the core material consists of a styrene/acryl polymer and the weight average mol.wt. thereof is 30000 to 70000 and the weight average mol.wt./number average mol.wt. 2 to 10.