Thermoplastic polyurethane lenses with a specified weight percentage of urethane repeating units
US8270089B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 5, 2007 |
| Grant date | Sep 18, 2012 |
| Priority date | — |
| Expiry date | Oct 5, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B1/043
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A method of forming thermoplastic polyurethane (TPU) into an optical lens. Suitable TPUs contain urethane (—NHCOO—) 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.