Patent ID: 6376597
Filing Date: 2002-04-23
Classification: C09B,C09D

Abstract:
A pigment dispersion comprising:(a) pigment; (b) an aqueous carrier selected from water and a mixture of water and at least one organic solvent; and (c) a pigment dispersant prepared by polymerizing a composition comprising, (i) at least one prepolymer having a radically polymerizable group at a head end of said prepolymer and an initiator residue at a tail end, said prepolymer being prepared by controlled radical polymerization of at least one radically polymerizable ethylenically unsaturated first monomer, said prepolymer having a polydispersity index of less than 2.0; and (ii) at least one radically polymerizable ethylenically unsaturated second monomer to produce a polymer backbone segment in said pigment dispersant; wherein said prepolymer after polymerization with (c)(ii) is in the form of polymeric segments pendent to said polymeric backbone segment, at least a portion of each pendent polymeric segment is hydrophilic, and the polymeric backbone segment is hydrophobic, wherein the pigment dispersant has the following structure: where M represents a residue of the radically polymerizable ethylenically unsaturated second monomer (c)(ii); x is the number of occurrences of M randomly distributed along the polymer chain; T-(E)s-(G)p-&PHgr; represents the prepolymer; y is the number of occurrences of the prepolymer randomly distributed along the polymer chain; T represents the radically polymerizable group at the head end of said prepolymer; E represents a block of hydrophilic residues of at least one radically polymerizable ethylenically unsaturated monomer; G represents a block of residues of one or more monomers selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, alkyl (meth)acrylates having from 6 to 20 carbon atoms in the alkyl group and an oxirane monomer reacted with a carboxylic acid; &PHgr; represents the initiator residue, x and y are selected such that the total weight ratio of the prepolymer (c)(i) to M (c)(ii) is from 1:10 to 10:1; p is from 1 to 300; and s is from 1 to 300.