Method for making end-capped polycarbonates from bisphenol monochloroformate polycarbonate oligomers
CA 2039834 A1 · Owner: Silva, James M. · Inventors: Fyvie, Thomas J.; Silva, James M.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
RD-19,636, A METHOD FOR MAKING END CAPPED POLYCARBONATES FROM BISPHENOL, MONOCHLOROFORMATE POLYCARBONATE OLIGOMERS Abstract of the Disclosure, Aromatic polycarbonates are prepared by initially phogenating a mixture of bisphenol and aqueous alkali metal hydroxide under interfacial reaction conditions to form an oligomeric bisphenol monochloroformate followed by the further introduction of phosgene and base and thereafter the elimination of reacted phosgene and the incorporation or endcapping phenol and tertiary organic amine and additional alkali metal hydroxide into the mixture. Reduced phosgene 2. usage, the substantial elimination of emulsion formation increased pH measurement accuracy …
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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
- Filed April 4, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 4, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 4, 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
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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.