Patent ID: 7862975
Filing Date: 2011-01-04
Classification: G03G

Abstract:
1. A carrier core material for an electrophotographic developer comprising Li ferrite, maghemite, and Fe 3 O 4 , wherein a part thereof is substituted with Mn, a Li content is 1 to 2.5% by weight, a Mn content is 2 to 7.5% by weight, and a silicon content is 25to 10,000 ppm, a compression breaking strength is 130MPa or more, an SF-1 is 125 to 145, the following equation (1) is satisfied when respective cumulative strengths of spinel crystal structure (110), (210), (211), and (311) faces in X-ray diffraction are respectively I 110 , I 210 , I 211 , and I 311 , a vacuum resistivity R 500 across a 2 mm gap when a measurement voltage of 500 V is applied is 1×10 6 to 5×10 9 Ω, and a vacuum resistivity R 1000 across a 6.5 mm gap when a measurement voltage of 1,000 V is applied is 5×10 7 to 1×10 1 Ω;