High consistency peroxide bleaching
CA 1281855 C · Owner: Macewen, Hollis D. · Inventors: Mclellan, Fraser; Willoughby, Arnold E.; Rhodes, Adele M.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process is provided for the bleaching of wood pulp with hydrogen or sodium peroxide. The process comprises the steps of adding to a wood pulp a bleach liquor having an effective amount of hydrogen or sodium peroxide bleaching agent and, by weight of the diluted wood pulp 0.5 to 6% sodium, hydroxide, 0 to 5% sodium silicate 0 to 1%, preferably 0.02 to, 0.05%, magnesium sulphate and a chelating agent in an amount, sufficient to sequester heavy metal ions in the pulp to, produce a pulp consistency of 1 to 16% at a temperature in the range of the bleach liquor freezing point to 25°C uniformly, mixing the bleach liquor with the wood pulp and immediately, thickening the diluted wood pulp to a …
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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
- Granted March 26, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended March 26, 2008.
- 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.