Photochromic composition resistant to fatigue including spiro ¬indoline-2,3'-¬3h -naphth ¬2,1-b ¬1,4 oxamine (so) dye and ultraviolet stabilizer
CA 1181978 A · Owner: American Optical Corporation · Inventors: Chu, Nori Y.C.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The organic photochromic composition of this invention comprises spiro indoline-2,3'-3H-naphth 2,1-b 1,4 oxazine (SO) dye and an unconventional ultraviolet stabilizer. The ultraviolet stabilizer improves the light fatigue resistance of the SO dye and will not hinder the photocolorability of the photochromic composition. -1-
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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
- Granted February 5, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 5, 2002.
- 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
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.