Process for preparing cellulose esters by use of carboxylic acids
CA 2059130 C · Owner: Eastman Chemical Company · Inventors: Edgar, Kevin J.; Buchanan, Charles M.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for reducing the degree of substitution of cellulose esters employing carboxylic acids as solvolysis promoters is disclosed. Exemplary cellulose esters are cellulose acetate cellulose propionate, cellulose butyrate cellulose acetate propionate, and, cellulose acetate butyrate.
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
- Filed April 9, 1991 and granted May 11, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 9, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 9, 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.