Method of converting a polymerizable composition into thermoplastic polyurethane of improved yellowness index and article obtained by this method
US9163133B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 2009 |
| Grant date | Oct 20, 2015 |
| Priority date | — |
| Expiry date | Sep 27, 2030 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08K2201/014
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
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).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.