Preparation of low molecular weight cellulose esters
CA 2078876 A1 · Owner: Buchanan, Charles M. · Inventors: Buchanan, Charles M.; Parker, Stephen W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process is disclosed for the preparation of low molecular weight, high hydroxyl cellulose esters ideally suited for use in coating applications. The new synthetic procedure involves treating a cellulose polymer with trifluoroacetic acid a mineral acid, an, acyl or aryl anhydride in an appropriate carboxylic solvent followed by, optionally, in situ hydrolysis. Typical reaction times for conversion to a triester are 5 to 30 minutes while typical hydrolysis times for far hydrolyzed mixed esters range from 4 to 7 hours. Molecular weight loss occurs during formation of the cellulose triester permitting concentrated reaction mixtures and easier isolation of the product ester.
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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 12, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 12, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 12, 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.