Patent ID: 7122081

Claim:
A process for particle size reduction of organic pigments to improve the optical properties of pigments wherein the process comprises (a) milling a mixture comprising: i.) from about 10 to about 60 wt. % of one or more crude organic pigments, ii.) from about 0.1 to about 25 wt. % of water soluble styrene copolymer dispersant based on the dry weight of the crude organic pigment, iii.) optionally from about 0.1 to about 1.0 wt. % of a defoamer, iv.) optionally from about 0.1 to about 5.0 wt. % of an additive based on the dry weight of the crude organic pigment, and v.) greater than about 10 wt. % water wherein components i.), iii.), and v.) weights are based on the total weight of the mixture, and (b) isolating the organic pigment.