Essilor International

Essilor International (Compagnie Generale D'optique)

Roger A Mayr

Hsinjin E Yang

Leanirith Yean

Hao-Wen Chiu

Hao Wen Chiu

A method of forming thermoplastic polyurethane (TPU) into an optical lens. Suitable TPUs contain urethane (&#x2014;NHCOO&#x2014;) repeating units that are present in at least 23% by weight. This range of urethane weights is an indicator of a flexural modulus above 1,400 MPa. The TPUs have refractive indices above 1.54 and Abbe numbers above 27. They have glass transition temperatures above about 100 degrees C. The selected TPU can be injection molded to form ophthalmic lenses, that are well suited for use in rimless spectacles. The lenses are highly solvent resistant, while at the same time being readily tintable. The lenses made according the invention meet FDA 21 CFR 801.41 Impact Requirement, and ANSI Z87.1 high velocity impact (HVI) standard.

Thermoplastic polyurethane lenses with a specified weight percentage of urethane repeating units

Methods are disclosed to injection mold resins, like polycarbonate, to form solid optical lenses. The lenses are ideally suited for use as very thin coating carriers. The method involves closing the mold with a clamp force less than the force exerted on the insert during injection. During injection the mold is allowed to breathe thereby overcoming many of the obstacles associated with injection molding very thin lenses. As the injection pressure subsides, the mold begins to close to perform a coining operation, resulting in a strong, high yield carrier or lens.

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Seminole, FL, United States of America

Roger A Mayr