| 摘要 |
<p>A water-dispersible carbon black pigment excellent in water dispersibility and ink performance; and a process for producing an aqueous carbon black dispersion. The water-dispersible carbon black pigment comprises a mixture of a carbon black (A) having a nitrogen-adsorption specific surface area of 150 m<SUP>2</SUP>/g or larger, a DBP absorption of 95 cm<SUP>3</SUP>/100 g or higher, and a specific coloring power of 120% or higher and a carbon black (B) having a nitrogen-adsorption specific surface area smaller than 150 m<SUP>2</SUP>/g, a DBP absorption less than 95 cm<SUP>3</SUP>/100 g, and a specific coloring power of 120% or higher in a proportion of from 20:80 to 80:20 by weight, these carbon blacks having undergone a surface oxidation treatment and a neutralization treatment, and at least the carbon black (A) having undergone a disaggregation treatment. The process comprises separately dispersing the carbon black (A) and the carbon black (B) in an aqueous oxidizing agent solution to conduct an oxidation treatment, subjecting these carbon blacks to a neutralization treatment, subjecting at least the carbon black (A) to a disaggregation treatment, thereafter purifying them, subsequently mixing the carbon black (A) with the carbon black (B) in a proportion of from 20:80 to 80:20 by weight, and then dispersing the resultant water-dispersible carbon black pigment into an aqueous medium.</p> |
