Patent ID: 6080233
Filing Date: 2000-06-27
Classification: C01G,C01P,C09C,G11B,H01F,Y10T

Abstract:
Cobalt-containing iron oxide pigments comprising:a cobalt-containing iron oxide core, the average concentration of cobalt distributed evenly in the innermost 50% by weight of the cobalt-containing iron oxide core being from 0.1 to 1.0% by weight (calculated as Co) based on iron oxide contained therein, and the content of Fe.sup.2+ in the core being from 16 to 22% by weight based on the iron oxide contained in the cobalt-containing iron oxide core; anda cobalt-containing iron oxide surface layer, the average concentration of cobalt in the surface layer of the outermost 10% by weight of the pigment being on average at least five times as high as the average concentration of cobalt in the innermost 50% by weight of the cobalt-containing iron oxide core.