Process for the preparation of a calcium sulphate-based aqueous suspension
CA 2114652 C · Owner: Sart, Michel · Inventors: Sart, Michel; Guidi, Tomizio
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method for preparing an aqueous calcium-sulphate based suspension particularly for use as a filler or coating pigment in paper manufacturing wherein a calcium sulphate slurry is formed by means of a first viscosity-regulating additive containing a copolymer which is obtained from at least two different kinds of ethylene monomers a second viscosity-regulating additive including an alkali metal phosphate or polyphosphate and optionally a third viscosity-regulating additive containing a cellulose ether the amount of added viscosity-regulating additive being such that the viscosity is 250-2500 mPa.s preferably 500-2000 mPa.s, and that the concentration of solid matter is 60-77 % preferably …
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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 August 3, 1992 and granted December 10, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 3, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 3, 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
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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.