Process for bleaching of lignocellulose-containing material
CA 2040871 C · Owner: Samuelsson, Marie R. · Inventors: Basta, Jiri J.; Lundgren, Per G.; Holtinger, Lillemor K.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to a process for delignification and bleaching of chemically digested lignocellulose-containing pulp for reduced formation and discharge of halogenated organic compounds, while preserving the pulp quality, where the prebleaching with halogen-containing bleaching agent is replaced by a treatment in a first, step, with the addition of a complexing agent at elevated temperature and at a pH from 3.1 to 9.0 and in a second, step, by using a peroxide-containing compound under alkaline conditions, whereupon spent liquor from the final bleaching with halogen-containing compounds is recycled to the first or second step of the halogen-free prebleaching.
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 April 19, 1991 and granted May 20, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 19, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 19, 2013.
- 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.