Patent ID: 10626558

Abstract:
A method of producing paper and board by using at least one water-soluble amphoteric polymer is provided. The water-soluble amphoteric polymer is obtained by copolymerizing a monomer mixture containing a) at least one N-vinylcarboxamide, b) at least one monoethylenically unsaturated monomer having at least one free acid group or at least one acid group in salt form, c) optionally at least one monoethylenically unsaturated monomer other than components (a) and (b), and d) optionally at least one compound having two or more ethylenically unsaturated double bonds, and then partly or wholly hydrolyzing the —CO—R1 groups of the polymer. The cationic monomer units and the anionic monomer units differ in their respective molar fractions, each based on the total number of moles of all monomer units, by not more than 10 mol % in absolute terms.