SURFACE-TREATED CARBON BLACK AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain the subject excellent pigment excellent in initial dispersibility and long-term dispersibility to water or organic solvents and hardly causing aggregation of pigment particles by dispersing carbon black into a sulfonation reaction solvent and introducing a sulfonic acid group onto the particle surface with a sulfonating agent. SOLUTION: A sulfonic acid group is introduced to the surface of particles of carbon black by a sulfonating agent (e.g. sulfamic acid or chlorosulfuric acid) by dispersing carbon black (preferably having 10-0.01μm particle diameter) into a sulfonation reaction solvent (e.g. sulfolane or N-methyl-pyrrolidone). Carbon black is preferably dispersed by a method finely dispersing the aggregate particles with a grinder or dispersing machine. The grinder or dispersing machine includes e.g. a two roll mill for finely dispersing by shear stress. Furthermore, the grinder or dispersing machine preferably has acid resistance.