Scale control in aqueous systems
CA 2029073 C · Owner: W.R. Grace & Co.-Conn. · Inventors: Cuisia, Dionisio G.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A composition and process for preventing the deposition of scale and sludge in aqueous systems comprising adding to the system the combination of three or more additives selected from the group consisting of a) polyacrylic acid copolymer of alkylsulfonate and malefic anhydride and mixtures thereof, b) hydroxy ethylidene diphosphonic acid amino, (trimethyl phosphonic acid), diethylenetriamine pentaacetic acid, and mixtures thereof, and c) copolymer of styrene sulfonate and malefic anhydride, copolymer of acrylic acid and acrylamide, poly(acrylic acid-co-hypophosphite) and mixtures thereof, and wherein the combination contains at least one additive selected from each of a), b) and c).
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 October 31, 1990 and granted December 12, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 31, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 31, 2012.
- 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.