| 摘要 |
PROBLEM TO BE SOLVED: To provide a carrier core material which achieves high-speed development with stable high image quality even when adopting a high-performance electrophotographic developing machine such as MFP, and which can extend the life of a magnetic carrier, and to provide a magnetic carrier. SOLUTION: The carrier core material for an electrophotographic developer comprises powder having a magnetic portion of a composition represented by MO-Fe<SB>2</SB>O<SB>3</SB>(wherein, M is a divalent metal element such as Mn, Mg or Fe) and a nonmagnetic portion containing SiO<SB>2</SB>derived from SiO<SB>2</SB>fine powder material with an average particle diameter of≤2μm, and having an apparent density of≤2.0 g/cm<SP>3</SP>, a residual magnetization of≤3 A m<SP>2</SP>/kg, and an electric resistance of≥10<SP>5</SP>Ωcm at an applied voltage of 250 V. COPYRIGHT: (C)2008,JPO&INPIT
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