Process for the delignification of cellulose containing raw materials
CA 2062474 A1 · Owner: Kunz, Rudolf G. · Inventors: Kunz, Rudolf G.; Janssen, Wim; Klein, Wolfdieter
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In the disclosed three step process for the delignification of cellulose containing raw material, the cellulose extraction is achieved by using an extraction solution of concentrated acetic acid at elevated temperature and pressures. The obtained acetic acid wet cellulose is treated in a second step with the aforementionned extraction solution and an added amount of nitric acid with a subsequent washing or extraction with water or with the extraction solution. In a third process step the obtained, acetic acid wet cellulose is treated with an ozone containing gas. The use of halogenous additives or bleaching agents is no longer required for this process. The process provides for a residual …
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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 March 6, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended March 6, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 6, 2014.
- 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.