Abstract: A polyurethane resin (soluble in organic solvents, preferably in alcohols) being in one embodiment of the present invention the reaction product of at least one diisocyanate components having isocyanate reactive functional groups, said components comprising a first group of at least one polyol, a second group of at least one polyol and a third group of at least one polyol, at least one amine and optionally a terminating agent wherein all polyols of said first group have an average molecular weight from 1000 to 10000 g/mol wherein all polyols of said second group have an average molecular weight from 10000 to 20000 g/mol, and wherein all polyols of said third group have an average molecular weight of equal to or less than 800 g/mol, and the ratio of the equivalent weights of the diisocyanate to the components having isocyanate reactive functional groups is selected such that essentially all of the isocyanate groups of the diisocyanate are present as the reaction product with one of said isocyanate reactive fun