Patent Number: 6,251,555

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

Abstract: Black magnetic composite particles for black magnetic toner according to the present invention comprise: magnetite particle as core particle; fine particles which are adhered or exist on at least a part of the surface of each magnetite particle, and comprise oxides, oxide hydroxides or oxides and oxide hydroxides composed of at least one element selected from the group consisting of Si, Zr, Ti, Al and Ce; and a methyl hydrogen polysiloxane coating layer formed on said fine particles or said fine particles and the exposed surface of the magnetite particle, the average particle size of said black magnetic composite particles being 0.08 to 1.0 .mu.m. 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.

Inventors: Hayashi; Kazuyuki (Hiroshima, JP), Ishitani; Seiji (Hiroshima, JP), Tanaka; Yasuyuki (Onoda, JP), Morii; Hiroko (Hiroshima, JP)

Assignee: Toda Kogyo Corporation

International Classification: G03G 9/083 (20060101); J03G 009/083 (); B32B 005/16 ()

Expiration Date: 06/26/2018