METHOD OF PRODUCING MAGNETIC IRON OXIDE

摘要

A process for producing a magnetic iron oxide having a dark enough color to provide opacity to thin coatings of the magnetic oxide in a binder comprising the steps of: a) reducing alpha -Fe2O3 in a non-oxidizing atmosphere using an organic reductant at 250 to 600 DEG C to form an iron oxide precursor having 25 to 45 mole % Fe<+2> based on total Fe (i.e., Fe<+2> and Fe<+3>); b) oxidizing the iron oxide precursor to form gamma -Fe2O3 until carbon content is from 0.5-3 % by weight of the iron oxide particles; and c) heating the gamma -Fe2O3 in an inert atmosphere at a temperature of about 400 to 550 DEG C to a magnetic oxide particle having 10 to 40 mole % Fe<+2> based on total Fe.