Essilor International (compagnie Generale D'optique)

Essilor International

Timothy E Herod

Hsinjin E Yang

Hao-Wen Chiu

Robert Rist

Richard Neuzil

Margie Hendrickson

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&#x2032;-methylenebis(6-(2H-benzotriazol-2-yl)-4-1,1,3,3-tetramethylbutyl)phenol).

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

A process for producing a curved substrate () covered with a film () comprises a heat treatment of the film performed between a step of preforming said film and a step of assembling the film with the substrate. A maximum temperature of the pre-assembling heat treatment is higher than another maximum temperature of a post-assembling heat treatment (F) which is performed after the assembling step. Then the assembly of the substrate () with the film () is not altered during said post-assembling heat treatment. In particular, no defect and no delamination appear, and no change in the curved shape of the substrate is caused by the post-assembling heat treatment, even if the substrate () has a low glass transition temperature.

Process for producing a curved substrate covered with a film

A method for thermoforming a thin thermoplastic carrier with uniformity of thickness at optical quality. The sheet to be thermoformed is heated and placed on a vented platform equipped with a mold insert. The thermoformer's platens clamp a shroud over the sheet. A low pressure air stream is introduced into the shroud and deflected from a direct path leading to the mold insert.

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St. Petersburg, FL, United States of America

Timothy E Herod