Process for bleaching a paper pulp with ozone and chlorine dioxide
CA 2247532 A1 · Owner: Trichet, Alain · Inventors: Hornsey, Derek; Muguet, Michel; Trichet, Alain
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for bleaching a paper pulp in which the said pulp is subjected successively to the action of ozone and then of chlorine dioxide, or vice versa. The process according to the invention is characterized in that the paper pulp treated is a so-called "low concentration" pulp with a consistency of less than or equal to approximately 5% by weight, the mixing of the ozone with the pulp being carried out in a rotary stirrer in which the pulp is stirred at a low speed while ozone is injected into the pulp, so as to obtain a fluidized pulp, the tangential peripheral speed of the pulp at the walls of the rotary stirrer being less than or equal to approximately 12 m/s but greater than or equal …
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 September 11, 1998. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended September 11, 2018.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 11, 2020.
- 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.