Patent ID: 6916862

Claim:
A process for the preparation of a pigment dispersion which comprises a) a pigment surface treatment step of introducing at least one hydrophilic dispersibility-providing group onto the surface of a pigment directly and/or with the interposition of a polyvalent group to form a surface treated pigment that is self-dispersible in water and that comprises said at least one hydrophilic dispersibility-providing group in an amount of not lower than 10×10 −6 per gram of particulate pigment, b) a dispersion step of dispersing a surface-treated pigment obtained at said surface treatment step in an aqueous medium, wherein said dispersion step involves the dispersion of said surface-treated pigment in admixture with a wetting agent and water, wherein the wetting agent is selected from the group consisting of glycol ethers, 1,2-(C 4 -C 10 alkyl)diols, 1,3-(C 4 -C 10 alkyl)diols, 1,5-(C 4 -C 10 alkyl)diols, and 1,6-(C 4 -C 10 alkyl)diols, and is present in amount that enhances a dispersion efficiency of particles of the surface-treated pigment in water, and (c) adding a resin for providing dispersibility an or fixability during and/or after said dispersion step to form said pigment dispersion, wherein the pigment dispersion has a liquid component comprising polyvalent metal ions in a total amount of not more than 600 ppm, wherein the dispersion step results in a dispersion having a pigment concentration of from about 5 to 50% by weight.