Porous ferrite core material for electrophotographic developer, resin-coated ferrite carrier and electrophotographic developer using the ferrite carrier

摘要

A porous ferrite core material for an electrophotographic developer wherein the apparent density thereof is 1.5 to 1.9 g/cm 3 , the shape factor SF-2 thereof is 101 to 110 and the magnetization as measured with a VSM at 1K·1000/4À·A/m is 40 to 60 Am 2 /kg, a resin-coated ferrite carrier for an electrophotographic developer obtained by coating the surface of the porous ferrite core material with a resin, and an electrophotographic developer using the ferrite carrier.