Modified aliphatic polyurethane polymers and method of preparing and using same

A process for preparing a light stable, fast reacting, polyester-modified aliphatic polyurethane polymeric reaction product, which process comprises admixing and reacting a composition, which composition comprises:

• (a) 100 parts by weight of a trimerized or biuret polymethylene polyisocyanate prepolymer having free NCO groups;
• (b) 10 to 150 parts by weight of an unsaturated polyester prepared by the reaction of an unsaturated polycarboxylic acid with a polyhydroxyl compound, and which polyester contains from about 0 to 40 percent by weight of a compatible unsaturated monomer adapted for a cross linking reaction with the unsaturated polyester;
• (c) a metal salt promotor for the unsaturated polyester to promote the cross linking of the unsaturated polyester, the metal salt promotor present in an amount sufficient to promote a cross linking reaction;
• (d) a peroxide initiator for the unsaturated polyester in an amount sufficient to initiate the cross linking reaction of the unsaturated polyester;
• and
• (e) an aromatic or cycloaliphatic polyamine in a stoichiometric amount ranging from the amount to react with all or substantially all of the free NCO groups of the prepolymer and in a maximum amount to also react with the hydroxyl groups of the unsaturated polyester.