Polyurethane dispersants

A non-aqueous composition comprising a particulate solid, an organic medium and a polyurethane dispersant having a number average molecular weight between 2000 and 50,000 and laterally attached solvent-solubilising side chains of a polyester, optionally including mixtures with solvent-solubilising polyether and/or polyacrylate side chains wherein the polyurethane dispersant comprises the reaction product of polyisocyanates having an average functionality of 2.0 to 2.1, compounds having at least one polyester having at least two groups which react with isocyanates which are located at one end of the compound such that the polyester thereby forms laterally attached solvent-solubilising chains, optionally compounds having an acid or amino group further having at least two groups which react with isocyanates, optionally one or more formative compounds having number average molecular weights of 32 to 3000 which have at least two groups which react with isocyanates, and optionally one or more compounds which act as chain terminators.