water in addition to the organic solvent application_number US 73566476 A description the polyurethanes in the surface coating and adhesive coating solutions which contain only one organic solvent are so called aromatic polyurethanes or aliphatic polyurethanes which may be obtained in known manner it is possible to use one component polyurethanes which are not subjected to a cross linking reaction however they may also be polyurethanes of the type which may be crosslinked for example with formaldehyde resins with acid catalysis the polyurethanes may be prepared in known manner either in the melt or in solution both by the one shot process and also by way of a prepolymer suitable dihydroxy polyesters and or dihydroxy polyethers are preferably those with molecular weights of from about 600 to 4000 and particularly those with molecular weights of from about 800 to 2500 the dihydroxy polyesters are obtained in known manner from one or more dicarboxylic acids preferably containing at least six carbon atoms or one or more dihydric alcohols instead of using the free polycarboxylic acids it is also possible to use the corresponding polycarboxylic acid anhydrides or esters of lower alcohols or mixtures thereof for producing the polyesters the polycarboxylic acids may be aliphatic cycloaliphatic aromatic and or heterocyclic and may optionally be substituted for example by halogen atoms and or be unsaturated examples of such polycarboxylic acids are succinic acid pimelic acid adipic acid suberic acid azelaic acid sebacic acid phthalic acid isophthalic acid trimellitic acid phthalic acid anhydride tetrahydrophthalic acid anhydride hexahydrophthalic acid anhydride tetrachlorophthalic acid anhydride endomethylene tetrahydrophthalic acid anhydride glutaric acid anhydride maleic acid maleic acid anhydride fumaric acid dimeric and trimeric fatty acids.