Production of paper, paperboard, or cardboard having high dry strength using polymeric anionic compound and polymer comprising vinylamine units
CA 2586076 C · Owner: Niessner, Manfred · Inventors: Schall, Norbert; Niessner, Manfred; Sturm, Berthold
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method for producing high dry strength paper paperboard or cardboard by separately adding a vinyl amine unit-containing polymer and a polymeric anionic compound to a paper pulp draining the paper , pulp and drying the paper products. The inventive method is characterized by using at least one copolymer as the polymeric anionic compound which is obtained by copolymerizing (a) at least one N-propenoic acid amide of formula (I), wherein R1, R2 = H or C1 to C6 alkyl (b) at least one acid group-, containing monoethylenically unsaturated monomer and/or the alkali metal salts, alkaline earth metal salts or ammonium salts thereof and optionally (c) other …
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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 November 21, 2005 and granted March 15, 2016. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 21, 2025.
- Certificates of supplementary protection extend only drug patents, and it isn't classified as one.
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Timeline
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.