Production of cellulose carbamate
CA 2260782 A1 · Owner: Rhodia Acetow Aktiengesellschaft · Inventors: Karstens, Ties; Stein, Armin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of producing cellulose carbamate is described in which: (a) cellulose is brought into contact with liquid ammonia at an initial pressure exceeding atmospheric pressure and a temperature of at least about 25 ~C in the , presence of urea, the quantity of liquid ammonia sufficing at least to wet the surface of the cellulose; (b)the volume available to the cellulose-urea-liquid ammonia system is enlarged explosively lowering the pressure by at least 5 , bar and an activated mixture of cellulose and urea is obtained; (c) the activated mixture of cellulose and urea is taken up in an inert organic carrier for the reaction, and heated to a temperature between about 110 ~C and 150 ~C …
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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 July 8, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 8, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 8, 2019.
- 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.