Black iron oxide pigments of high tinting strength, process for preparing them and their use

摘要

Highly pure and highly color intensive black anisometric magnetite iron oxide pigment having an FeO content of from 26 to 29% by weight and manganese content of less than 0.1% by weight, said pigment further having a specific BET surface area of from 5 to 15 square meters per gram and being needle shaped particles with an average needle diameter of 0.1 to 0.2 mu m and an average needle length of from 0.6 to 0.8 mu m are produced by producing alpha -FeOOH particles by alkali precipitation of an iron salt solution with a nuclear formation stage oxidation and a pigment growth stage oxidation followed by reduction and passivation.