the homopolymers of gt 40 u00b0 c suitable examples are t butyl acrylate methyl methacrylate ethyl methacrylate isopropyl methacrylate t butyl methacrylate cyclohexyl methacrylate and trimethylcyclohexyl methacrylate methyl methacrylate and t butyl acrylate are preferred the nitrocellulose cellulose nitrate used in the coating material of the invention as component b should be soluble in organic ester solvents for example nitrocellulose with a nitrogen content of 11 8 to 12 25 nitrogen is suitable for this purpose such a nitrocellulose is soluble in esters and practically insoluble in alcohols it can however be blended to a large extent with alcohols and aromatic compounds ester solvents in which the nitrocellulose usable pursuant to the invention is soluble are for example those esters which are suitable for the above solution polymerization for the preparation of component a and those which may also be contained later on in the finished coating materials it is advantageous if the intrinsic viscosity of the nitrocellulose expressed by the k value of h fikentscher cellulosechemie 13 page 58 1932 falls in the range of 300 to 600 measurement 2 g of nitrocellulose in 100 ml of acetone at 25 u00b0 c preferably a nitrocellulose with a k value of 400 such as collodiumwolle u00ae e 400 b wolff walsrode ag is used for cross linking the inventive vehicle mixture of copolymer and estersoluble nitrocellulose polyisocyanates component c are used these polyisocyanates are typical polyisocyanates for paints or paint polyisocyanates similar to those described in the literature for example in the european patent no b1 00 68 383 there especially on page 2 line 57.