| abstract |
PROBLEM TO BE SOLVED: To provide an oxidized carbon black suitable for use as an aqueous ink for an ink jet printer, a production method, and an aqueous dispersion thereof. SOLUTION: This carbon black is obtained by liquid-phase oxidation of a carboxyl group to 2 to 5 μmol / m 2 with peroxodiacid or peroxodioate, and a part or all of the generated carboxyl group has a dissociation constant (pKa). A process for neutralizing oxidized carbon black and carbon black after liquid phase oxidation to remove residual salts, wherein the carbon black is neutralized with an alkali solution of less than 5. Further, the oxidized carbon black is dispersed in an aqueous dispersion medium, and the average particle diameter Dupa50% of the carbon black particle aggregate is 50 to 130 nm, the maximum particle diameter Dupa99% is 150 to 320 nm, and the half width ΔD of the particle size distribution is ΔD. ratio ΔDupa (mod) between upa (mode) and mode diameter Dupa (mode) e) An aqueous dispersion that has been classified to have a value of / Dupa (mode) of 1.20 or less. |