| 摘要 |
PROBLEM TO BE SOLVED: To provide a ferrite core material for an electrophotographic developer having a low apparent density, less likely causing impregnation of a resin, and having a small ruggedness degree on a particle surface, a ferrite carrier for an electrophotographic developer using the porous ferrite core material, and an electrophotographic developer using the ferrite carrier.SOLUTION: The porous ferrite core material for an electrophotographic developer is a material having a resin-coated surface and not filled with a resin; and the porous ferrite core material has a metal component comprising 10 to 16.2 wt.% of Mn, 0.2 to 3 wt.% of Mg, 48 to 60 wt.% of Fe, and 0.14 to 0.88 wt.% of Sr, an apparent density of 1.5 to 1.9 g/cm, a shape factor SF-2 of 101 to 110, and a magnetization of 40 to 60 Am/kg measured with a VSM (vibrating sample magnetometer) in a magnetic field of 1K 1000/4π A/m. In a spectrum obtained by Raman spectroscopy near the surface of the porous ferrite core material, a half-width value Wof a peak derived from the ferrite is 53.08 to 56 cmand a standard deviation Wis 3 cmor less.SELECTED DRAWING: None |
