Black magnetic composite particles for black magnetic toner and black magnetic toner using the same

摘要

Black magnetic composite particles for black magnetic toner which have an average particle size of from 0.08 to 1.0 mu m, comprising: (i) magnetite particles as core particles; (ii) fine particles on at least a part of the surface of each magnetite particle, comprising an oxide and/or an oxide hydroxide of at least one element selected from Si, Zr, Ti, Al and Ce; and (iii)a methyl hydrogen polysiloxane coating layer on said fine particles or on said fine particles and the exposed surface of the magnetite particles. Such black magnetic composite particles are suitable for a black magnetic toner which can exhibit not only an excellent flowability but also a high volume resistivity.