Method of bleaching cellulose pulp with ozone
CA 2012771 C · Owner: Henricson, Kaj · Inventors: Peltonen Juhani; Henricson, Kaj; Laxen, Torolf
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Ozone bleaching has been extensively studied in laboratory and pilot scale. It has been proved that at low consistencies, i.e. less than 5 %, ozone dissolves well in water and thus good transfer of substance between the ozone and the fibers in the water is achieved. On the other hand, it has been discovered that the ozone being a, gaseous substance, reacts well also directly with a fiber surface which, however, presupposes that the consistency of the suspension is over 25 %. Further it has been, discovered that in the intermediate range between said consistencies ozone cannot satisfactorily contact the fibers. However, both environmental and pumping factors determine the operation to be …
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 22, 1990 and granted March 26, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 22, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 22, 2012.
- 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.