Photochromic naphthopyrans
CA 2097606 C · Owner: Van Gemert, Barry · Inventors: Van Gemert, Barry
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Described are novel reversible photochromic naphthopyran compounds substituted on the naphthyl portion at the carbon atom juxtaposed to the oxygen of the pyran ring with for example, an acetoxy group. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds e.g. spiro(indolino)-oxazine type compounds are also described.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed November 27, 1991 and granted September 16, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 27, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 27, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.