Developing material for electrophotography, process for preparation

摘要

An iron powder developer carrier for electrophotography having at least the outer surface thereof coated with iron oxide. The iron oxide has a particle size of 50 to 200 mu , an apparent density of 1.5 to 2.5 g/cm3 and a specific surface area of 0.01 to 0.3 m2/g. A process for the preparation of iron powder developer carriers for electrophotography, which comprises the steps of subjecting a starting iron powder to a primary calcination treatment in an inert gas atmosphere without using a binder, pulverizing and classifying said calcination product to prepare an intermediate iron powder, reducing the intermediate iron powder in a reducing atmosphere and washing the intermediate iron powder, and subjecting the intermediate iron powder to an oxidizing calcination treatment.