Aqueous pigment ink composition

摘要

Disclosed is an aqueous pigment ink composition comprising water and oxidized carbon black dispersed stably in the water, wherein said oxidized carbon black is obtained by oxidizing carbon black using hypohalous acid and/or salt thereof and wherein at least a part of an acidic group existing on the surface of said oxidized carbon black associates with an amine compound to form an ammonium salt. The aqueous pigment ink composition realizes smooth printing with ink jet nozzle, and smooth writing with fine pen tip and it has sufficient density. Further, the recorded traces obtained by using the ink composition is excellent in water resistance.