Method of converting a polymerizable composition into thermoplastic polyurethane of improved yellowness index and article obtained by this method

摘要

Method of producing a thermoplastic polyurethane having a light stabilization useful for ophthalmic applications, comprising combining precursors of a polyurethane and at least one antioxidant, and incorporating therein, either before, during or after polymerization, at least one light stabilizer, said method being characterized in that the antioxidant is benzenepropanoic acid, 3(1,1-dimethylethyl)-4-hydroxy-5-methyl-1,1′-[1,2-ethanediylbis(oxy-2,1-ethanediyl)]ester and the light stabilizer is bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate together with at least one additional component chosen from among phenol, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methyl and 2,2′-methylenebis(6-(2H-benzotriazol-2-yl)-4-1,1,3,3-tetramethylbutyl)phenol).

主权项

1. A method of converting a polymerizable composition into thermoplastic polyurethane for use as an ophthalmic lens, said method comprising:
combining precursors of the polyurethane with a plurality of additives including:
(i) an antioxidant which is benzenepropanoic acid, 3(1,1-dimethylethyl)-4-hydroxy-5-methyl-1,1′-[1,2-ethanediylbis(oxy-2,1-ethanediyl)] ester is present in the amount of 0.1 to 1% by weight;(ii) a light stabilizer component bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate is present in the amount of 0.1 to 1% by weight; and(iii) phenol, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methyl present in the amount of 0.1 to 1% by weight; and conducting a conversion step forming a thermoplastic polyurethane.