Method for preparing delignified and bleached chemical paper pulps
CA 2189796 C · Owner: Schirmann, Jean-Pierre · Inventors: Devic, Michel; Schirmann, Jean-Pierre
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method wherein a cooked lignocellulose pulp is (a) delignified using oxygen (b) processed with a transition metal complexing or sequestering agent and washed and (c) processed with hydrogen peroxide in the presence of an alkali metal silicate at a temperature of over 100 ~C and at a pressure of 5-200 bar.
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 14, 1995 and granted August 22, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 14, 2015.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 14, 2017.
- 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.