Method for producing paper, paperboard and cardboard
CA 2469758 A1 · Owner: Blum, Thierry · Inventors: Bohlmann, Klaus; Linhart, Friedrich; Hemel, Ralf
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method for producing paper paperboard and , cardboard by draining the pulp on a sieve in the presence of at least one , cationic polymer. Before sheets are formed a mixture of at least one , essentially linear cationic polyelectrolyte and an optical brightening agent is added to the pulp, said mixture containing at least two parts by weight of the polyelectrolyte per part by weight of the optical brightening agent.
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 December 6, 2002. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended December 6, 2022.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 6, 2024.
- 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.