A process for the manufacture of paper
CA 2108028 C · Owner: Carre, Bruno · Inventors: Carlson, Ulf; Carre, Bruno
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for improved dewatering and retention in the manufacture of paper where a retention agent containing anionic groups and being based on a polysaccharide or being an acrylamide-based polymer and an alkaline solution of an aluminate are added to the stock containing lignocellulose-containing fibres and optionally fillers. The pH of the stock prior to the addition of the aluminate should be below about 7 to obtain the desired cationic aluminium hydroxide complexes in the stock. The present process is cost effective and insensitive to the content of calcium in the white water.
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 June 12, 1992 and granted May 27, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 12, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 12, 2014.
- 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.