Dispersants from linear polyurethanes

A non-aqueous composition comprising a particulate solid, an organic medium and a polyurethane dispersant;

• said polyurethane dispersant comprising a) at least one essentially linear anchoring backbone segment including laterally attached to said essentially linear anchoring backbone segment tertiary and/or quaternized tertiary amine groups comprising one or more tertiary nitrogen atom wherein the tertiary nitrogen atom of said tertiary amine groups is separated from said backbone by at least one intervening atom and b) terminally attached to said anchoring backbone segment are one or more solvent-solubilising terminal chain(s) of a polyester, polyether, or polyacrylate, including mixtures of such terminal chains;
• wherein said essentially linear anchoring backbone segment is comprised of repeating units derived from an isocyanate component reacted with a tertiary and/or quaternized tertiary amine component, wherein said isocyanate component comprised reactive isocyanate groups having an average functionality of from about 2.0 to about 2.2 and said tertiary and/or quaternized tertiary amine component comprised groups reactive with isocyanate groups, wherein about 75 to about 95 mole % of the total of said reactive isocyanate groups of said isocyanate component were reacted with groups on said amine component that are reactive with isocyanate groups to form said anchoring backbone segment and
• wherein the total weight percentage of solvent-solubilising terminal chains is not less than 20% based on the total weight of polyurethane dispersant and said solvent-solubilizing terminal chains have a number average molecular weight of 500 to 5000 Dalton.