| 摘要 |
PROBLEM TO BE SOLVED: To obtain magnetite particles having such various characteristics as oil absorption, electric resistance, magnetic characteristics and environmental resistance improved in a well-balanced state and chiefly used as a powdery material for an electrostatic copying magnetic toner and as a powdery black pigment for a coating material. SOLUTION: The magnetite particles contain 0.2-1.0 wt.% (expressed in terms of silicon) silicon component, which exists continuously from the insides toward the outsides, to the magnetite, the silicon component is exposed to the surfaces of the particles by 0.01-0.3 wt.% and the shells of the particles have been coated with a metallic compd. of one or more metals bonded to the silicon component. The metals are selected from among Zn, Mn, Cu, Ni, Co, Cr, Cd, Al, Sn, Mg and Ti. |
