Water-dilutable aqueous coating compositions

Claim 1

A water-dilutable aqueous coating composition which comprises: (A) X parts of a water-dispersible film-forming polymer of molecular weight in the range 2,000-30,000, the polymer comprising (a) anionisable groups, at least partially neutralised with a base when required, selected from --COOH, --SO 3 H and --PO 4 H 2 , or cationisable groups, at least partially neutralised with an acid when required, of structure --N R 1 R 2 , where R 1 and R 2 are H or C 1-18 alkyl or substituted alkyl groups, the same or different, or R 1 and R 2 represent part of a cyclic structure, and (b) non-ionisable water-soluble moieties selected from moieties of polyethylene glycol or its monoethers of molecular weight not greater than 1,000; and moieties of poly(meth)acrylamide, of polyvinylpyrrolidone or of poly 2-ethyl oxazoline and its hydrolysates, all being of molecular weight not greater than 2,000; (B) Y parts of an organic coupling solvent for the film-forming polymer which has a boiling point greater than that of water, where Y=X(Z/100), Z being in the range 0-150, and (C) water, which is characterised in that when a solution of X parts of the water-dispersible polymer in Y parts of the organic coupling solvent or, when Y=O, in water is progressively diluted with water, there is no increase in viscosity of the diluted aqueous solution as measured at 25° C. by a low shear viscometer.