Surface-treated organic pigment and process for the production thereof

摘要

A surface-treated organic pigment excellent in initial dispersibility and long-term dispersion stability in water and an organic solvent and free from the coagulation of pigment particles, obtained by reacting a sulfonating agent with an organic pigment dispersed in a solvent in which the organic pigment is insoluble or sparingly soluble, and thereby introducing a sulfonic acid group to the surface of each particle of the organic pigment.