Process for preparing an aqueous dispersion of pigment containing particles

Abstract

A process for preparing an aqueous dispersion of pigment particles is described. The pigment particle contains a pigment and an aminoplast resin which surrounds or embeds the pigment. The process includes (i) a step of subjecting an aqueous suspension of a pigment in the form of coarse particles to milling so that the coarse particles are comminuted in the presence of a polymeric dispersant to a particle diameter d(v 0.9) of below 1500 nm, as determined by laser diffraction; and (ii) a step of polycondensation of an aminoplast pre-condensate in the aqueous suspension of the comminuted particles of the pigment obtained in step (i) or during the milling of step (i). The polycondensation is performed in the presence of an acid catalyst at pH of below 5.5. The aqueous dispersion obtained by the process and the use of the aqueous dispersion for tinting waterborne liquid coating composition are also described.

Dependencies are inferred from the claim text.