Copolymers of poly(vinyl trifluoroacetate) or poly(vinyl alcohol)
CA 1238748 A · Owner: Minnesota Mining And Manufacturing Company · Inventors: Ofstead, Ronald F.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure Novel, non-crosslinked copolymers of vinyl trifluoroacetate (VTA) and up to 5 weight percent of the VTA of certain comonomers, such as vinyl esters or disubstituted ethylene monomers, are disclosed. Solvolysis of these copolymers provides novel water-insoluble non-crosslinked, poly(vinyl alcohol) copolymers which can be hydrated to copolymers having controllably variable hydrogel properties and high strength. Such poly(vinyl alcohol) copolymers are particularly desirable as optical devices such as contact lenses.
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 June 28, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended June 28, 2005.
- 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.