Scale deposit inhibitor for kraft digesters and method for controlling scale deposition in kraft digesters
CA 2114692 C · Owner: Togo, Akira · Inventors: Shibata, Takanori; Togo, Akira
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A scale deposit inhibitor and a method for continuously controlling scale deposition applicable to a digester and its peripheral equipment used in kraft pulp manufacture are disclosed, the scale deposit inhibitor comprising a maleic acid-acrylic acid-hypophosphorous acid terpolymer having a maleic acid unit to acrylic acid unit molar ratio of 1:4 to 4:1, a hypophosphorous acid unit content of 1 to 12 mol% and, a weight average molecular weight of 500 to 10000. The scale deposit inhibitor is added to a cooking liquor in a concentration of 0.01 to 10 ppm per ppm of a calcium ion in the cooking liquor.
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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
- Filed February 1, 1994 and granted September 29, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 1, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 1, 2016.
- 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.