Hydrophilic, swellable graft copolymers, their preparation and use
CA 2013115 C · Owner: Riegel, Ulrich · Inventors: Riegel, Ulrich; Engelhardt, Friedrich
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to hydrophilic swellable, graft copolymers composed, in random distribution of 0.5 to 20 %, by weight of radicals of the general formula I (see formula I), 79 to 99 % by weight of radicals containing an acidic group of, the general formula II, (see formula II) and 0.1 to 2 % by weight of crosslinking structures which are derived from monomers having at least two olefinically unsaturated double bands, where the radicals X Y, R1 to R4 and n, have the meanings given in Claim 1 and which are used as , absorbents for water and aqueous solutions.
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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 March 27, 1990 and granted November 16, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 27, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 27, 2012.
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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.