US Patent 7268203 Polymer dispersant having hyperbranched structures

Polyurethanes having hyperbranched structures, selected from hyperbranched polyurethanes containing at least one pigment affinity group and modified hyperbranched polyurethanes, are used as polymeric dispersing additives for pigments. A preferred process for preparing modified polymeric dispersing additives comprises reacting a hyperbranched polyurethane having from 2 to 100 NCO groups and a molar mass of from 500 to 50,000 g/mol with one or more polyether derivatives.