Patent ID: 9081318
Filing Date: 2015-07-14
Classification: G03G

Abstract:
1. A ferrite carrier core material for an electrophotographic developer, wherein: (1) a ferrite composition contains 0.5 to 2.5% by weight of Sr; and a presence amount of Sr—Fe oxides satisfies the following conditional expression: provided that the total weight of all Sr—Fe oxides=the Sr ferrite+the Sr—Fe oxides other than the Sr ferrite; (2) in the distribution in the number of the shape factor SF-2, the number of particles of 100 or more and less than 105 is 40% by number or more; that of 105 or more and less than 110 is 5 to 40% by number; that of 110 or more and less than 120 is 20% by number or less; that of 120 or more is 10% by number or less; and that of 130 or more is 5% by number or less; (3) the BET specific surface area is 0.15 to 0.30 m (4) the average particle diameter D (5) the magnetization by VSM measurement when a magnetic field of 1K·1000/4π·A/m is impressed is 50 to 65 Am