Examples of pigment dispersants are described in British Pat. Nos. 1108261, 1339930, 1346298, 1373660 and 1393401 and in U.S. Pat. No. 3940353. Such pigment dispersants are generally compounds containing a solvent-compatible organic radical of molecular weight at least 500 and a polar pigment-compatible radical.
Pigments dispersants can also be used to prepare dispersions of pigments in a solvent which can be mixed into different types of paints without requiring subsequent grinding or milling of the paint. Such pre-dispersions can be used to supply paint quickly without needing to keep stocks of many types of paint each in many colours. There is a need for a pigment dispersant which can be used in this way with a wide variety of film-forming resins and solvents.