Coloured hydrogel objects and their production
CA 1291301 C · Owner: Da Costa, Nicholas M. · Inventors: Da Costa, Nicholas M.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Shaped organic polymer hydrogels especially, contact lenses, are provided with opaque or translucent colouring so as to he capable of masking effectively any underlying colour, e.g. the natural colour of the eye. The hydrogel may be rendered opaque by precipitation in situ of a white or yellow water-insoluble, inorganic material e.g. barium sulphate and then coloured with a suitable dyestuff.
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
- Granted October 29, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended October 29, 2008.
- 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.