Ozone treatment of chlorine dioxide/chlorine chlorinated pulp
CA 2017334 C · Owner: International Paper Company · Inventors: Tsai, Ted Y
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention provides for improvements in the preparation of cellulosic wood pulp for use in papermaking and specifically to enhancement of the quality of a pulp which has been subjected to a chlorine-based bleaching agent, by subjecting the chlorinated pulp to ozonation prior to an extraction stage in the bleaching sequence. The improved pulp of the present invention includes reduction of total organically bound chlorine residues in the wood pulp and adsorbed organic halides (AOX) in the effluent and has, good brightness and viscosity. The advantages of the present invention may be accomplished by means of a bleaching sequence that employs as few as four stages namely DZED, with …
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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 May 23, 1990 and granted July 25, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 23, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 23, 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.