Patent ID: 8703865

Claim:
A method of producing an aqueous dispersion of polymer-encapsulated pigment, comprising the steps of: (a) preparing an aqueous pigment dispersion comprising at least one organic pigment P selected from the group consisting of azo, isoindolinone, isoindoline, anthanthrone, thioindigo, thiazineindigo, triarylcarbonium, quinophthalone, anthraquinone, dioxazine, phthalocyanine, quinacridone, quinacridonequinone, indanthrone, perylene, perinone, pyranthrone, diketopyrrolopyrrole, isoviolanthrone, and azomethine pigments, at least one surfactant T, and water; (b) providing a monomer miniemulsion stabilized by a hydrophobic organic compound having a water solubility at 20° C. of not more than 5×10 −5 g/l and and wherein the monomer miniemulsion includes at least one polymerizable monomer M, at least one surfactant T1 and water, wherein the miniemulsion is in the form of droplets and wherein the droplets have a size of less than or equal to 1000 nm by a homogenization step; (c) producing a pigment-containing monomer miniemulsion by combining and homogenizing the aqueous pigment dispersion from step (a) and the monomer miniemulsion from step (b), and (d) polymerizing the pigment-containing monomer miniemulsion from step (c) in the presence of a polymerization initiator by heat or both to form the polymer-encapsulated pigment, wherein the polymer-encapsulated pigment has a homopolymer content of less than 5% by weight based on the total weight of the encapsulated pigment particles.