酸化型自己分散顔料の製造方法及びインクジェット用インクの製造方法

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an oxidized self-dispersible pigment by which variation in the degree of oxidation treatment in oxidized self-dispersible pigments is reduced.SOLUTION: The method for producing an oxidized self-dispersible pigment includes: a pigment dispersion step of obtaining a pigment dispersion by dispersing a pigment having an average particle diameter of ≤250 nm in an aqueous medium; an ozone dissolution step of obtaining an aqueous ozone solution having a concentration of ≥30 ppm by applying a pressure to water in the presence of ozone gas to thereby dissolve ozone; and a pigment oxidation step of obtaining an oxidized self-dispersible pigment by allowing the pigment dispersion to collide against the aqueous ozone solution to thereby oxidize the pigment in the pigment dispersion, wherein the flow rate of the dispersion and the flow rate of the solution in the pigment oxidation step are ≥4.0 mm/s each.