Pre-treatment of filler with cationic ketene dimer
CA 2040089 A1 · Owner: Hercules Incorporated · Inventors: Dumas, David H.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A filler for paper or paperboard comprising an inorganic pigment and a cellulose-reactive size, a process for preparing the filler in which the inorganic pigment dispersed in water is treated with a dispersion of the cellulose-reactive size before the filler is added to the dispersion of cellulose fibers in a paper machine, and the use of the treated filler in a process for the manufacture of paper and paperboard in order to maintain the capability of the cellulose fiber and filler mixture to receive sizing independently of the level of filler addition.
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 9, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 9, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 9, 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.