IRON OXIDE PARTICLES AND PROCESS FOR PRODUCING THE SAME

摘要

Disclosed herein is iron oxide particles comprising: 100 parts by weight of material iron oxide particles having a specific surface area represented by the following formula (1): 6/(p~d3) x ~s (1) wherein p represents a specific gravity of said iron oxide particles, d3 represents an area-average particle diameter (0.1 .mu.m ~ d3 ~ 1.0 .mu.m) and ~s represents an area shape factor) (1.0 ~ ~s ~ 2.0); and 0.25 to 10 parts by weight (calculated as an oxide) of the fine particles of the oxygen compound, the fine particles of the hydrate or mixed fine particles thereof of one element selected from the group consisting of Al, Si, Zr and Ti, which are adhered to the surfaces of said iron oxide particles; the increment of said specific surface area of said iron oxide particles being 1 to 6 m2/g, and the increment of said specific surface area with respect to the amount of said fine particles being not less than 0.35.