a polyurethane coating layer , with self - repairing properties , for panes made of glass and / or plastic materials , which are exposed to atmospheric agents . the coating layer according to the invention is formed from a reactive mixture of a trifunctional isocyanate component such as the biurets or isocyanurates of 1 , 6 hexamethylenediisocyanate , having a content of about 15 to 25 % by weight of nco radicals and a polyalcohol component chosen from the plurifunctional polyester polyalcohols having about a 3 to 12 % by weight content of oh radicals .