Bleaching pulp with high-pressure o2
CA 2376528 A1 · Owner: Barde, Nana · Inventors: Vallance, William D.; Barde, Nana
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for oxygen bleaching pulp in which the pulp is pre-treated prior to oxygen bleaching (52), e.g. to remove the hexeneuroonic acid. Oxygen bleaching (36, 42) is accomplished at high pressure in two stages with a medium consistency pump (32). The wash from the bleaching stage is not recycled into the chemical recovery system. A final whitening sequence includes at least one chlorine dioxide stage followed by an alkaline peroxide stage with no intervening wash is also included.
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 June 2, 2000. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended June 2, 2020.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 2, 2022.
- 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.