Patent ID: 8163816

Claim:
A process for producing a concentrated liquid composition comprising a pigment and a stimuli-responsive dispersant, wherein the pigment having particle size of 100 nm or less is contained in the concentrated liquid composition in a dispersed state, the process comprising: (1) obtaining a solution by dissolving the pigment in a first solvent; (2) mixing the solution with a second solvent to obtain a resulting liquid composition, wherein the stimuli-responsive dispersant is contained in at least one of the first or second solvents and wherein the stimuli-responsive dispersant is a copolymer comprising: (a) a site having a lower critical solution temperature in water or an aqueous solution; and (b) a hydrophobic site, wherein the (a) site is poly(N-isopropylacrylamide) and the (b) site is polystyrene; (3) heating the resulting liquid composition obtained in (2) to a temperature not lower than a first temperature to form an aggregate comprised of pigment particles, wherein the first temperature is the lower critical solution temperature; (4) removing other components except the pigment particles from the resulting liquid composition; and (5) cooling the resulting liquid composition to a temperature not higher than the first temperature to set the pigment particles making up the aggregate comprised of the pigment particles into a dispersed state.