Process for producing heat-resistant yellow hydrous iron oxide pigment

摘要

The present invention relates to a hydrous iron oxide yellow pigment having exceptional heat resistance and dispersibility, and to a simple production method for the same. The production method involves treating an aqueous dispersion containing hydrous iron oxide particles with a phosphoric acid compound at pH within a range of 4-7, followed by treatment with an aluminum compound at pH within a range of 3-5, then adjustment of pH to neutral and heat treatment, forming a layer of aluminum hydroxide, to obtain a heat resistant hydrous iron oxide yellow pigment. Optionally, after the aluminum hydroxide has been formed, a water-soluble silicate salt may be added to form a coating layer having an aluminum layer and a silica layer on the surfaces of the hydrous iron oxide particles.