Delignification and bleaching process for chemical paper pulp
CA 2200486 C · Owner: Devic, Michel · Inventors: Devic, Michel
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention consists of a delignification and bleaching process for chemical paper pulp comprising one or more hydrogen peroxide treatments at a temperature exceeding 100 C and at high pressure in the presence of a polymer and an A compound of potassium hydroxide sodium hydroxide or carbonates of an alkaline metal or earth. The process yields a well bleached pulp which nonetheless remains highly polymerized.
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 March 19, 1997 and granted January 15, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 19, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 19, 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.