| abstract |
A method is provided for treating a substrate with a radiation curable coating composition based on a polyester resin esterified with acrylic acid or methacrylic acid and having a hydroxyl number in the range of from 50 to 250 and an ethylenic unsaturation equivalent weight of from 200 to 10,000 grams and on a polyisocyanate that is present in an amount of 0.7 to 1.3 equivalents of isocyanate per equivalent of hydroxyl contained in the composition. The curing of the coating composition is effected in a first stage by subjecting the composition to radiation having a wave length of 200 to 600 nm and in a second stage by reaction between the isocyanate groups of the polyisocyanate and the hydroxyl groups of the polyester resin. |