Use of hydrolysed polymers of n-vinyl carboxylic acid amides as agents for increasing the dry strength of paper, card and cardboard
CA 2247052 A1 · Owner: Schuhmacher, Rudolf · Inventors: Rubenacker, Martin; Schuhmacher, Rudolf; Utecht, Jens
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Proposed is the use, as agents for increasing the dry strength of paper card , and cardboard, of partially hydrolysed polymers of N-vinyl carboxylic acid amides obtained by the homopolymerization of N-vinyl carboxylic acid amides of the formula (I) in which R1 and R2 are H or C1-C6 alkyl and by splitting off 0.5 to 95 mole % of the groups of the formula (II) in which R1 is H or C1-C6 alkyl.
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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 20, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended February 20, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 20, 2019.
- 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.