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US 7,922,867 B2Granted
Method for producing paper, paperboard and cardboard having high dry strength
AssigneeBASF SE
InventorsNorbert Schall, Ellen Krueger, Martin Ruebenacker
Life of this patent
Estimating the term…
Abstract
Process for the production of paper, board and cardboard having high dry strength by separate addition of a polymer comprising vinylamine units and of ligninsulfonic acid and/or a ligninsulfonate to a paper stock, draining of the paper stock and drying of the paper products.
Claims13
A process for the production of paper, board or cardboard, having high dry strength, the process comprising separate addition of a cationic polymer comprising vinylamine units, and of a polymeric anionic compound to a paper stock,
- draining of the paper stock and
- drying the product thereof,
- wherein the polymeric anionic compound comprises
- (i) ligninsulfonic acid and/or a ligninsulfonate and
- (ii) at least one copolymer which is obtainable by copolymerization of
- (a) at least one N-vinylcarboxamide of the formula
- where R1, R2 is H or C1- to C6-alkyl,
- (b) at least one monoethylenically unsaturated monomer comprising acid groups and/or the alkali metal, alkaline earth metal or ammonium salts thereof and, optionally,
- (c) at least one other monoethylenically unsaturated monomer, and, optionally,
- (d) at least one compound which has at least two ethylenically unsaturated double bonds in the molecule.
7 more elements
A method for increasing the dry strength of paper, board or cardboard, comprising adding
- (i) ligninsulfonic acid and/or at least one ligninsulfonate and
- (ii) at least one copolymer which is obtainable by copolymerization of
- (a) at least one N-vinylcarboxamide of the formula
- where R1, R2 is H or C1- to C6-alkyl,
- (b) at least one monoethylenically unsaturated monomer comprising acid groups and/or the alkali metal, alkaline earth metal or ammonium salts thereof and, optionally,
- (c) at least one other monoethylenically unsaturated monomer, and, optionally,
- (d) at least one compound which has at least two ethylenically unsaturated double bonds in the molecule,
- as an additive to paper stock in the production of said paper, board or cardboard in the presence of at least one cationic polymer comprising vinylamine units.
5 more elements
Dependencies are inferred from the claim text.