Patent ID: 8382948
Filing Date: 2013-02-26
Classification: D21H

Abstract:
1. A process for producing paper, comprising adding 0.01 to 1.00% by weight, based on dry fiber, of water-soluble, amphoteric copolymers to a high-consistency fiber stock, and adding a filler to the high-consistency fiber stock, wherein the water-soluble, amphoteric copolymers are obtained by a polymerization process comprising: (1) copolymerization of a mixture comprising a) at least one N-vinylcarboxamide of the general formula in which R b) at least one monomer which is selected from the group consisting of c) optionally, at least one monoethylenically unsaturated monomer differing from the components (a) and (b), and d) optionally, at least one compound which has at least two ethylenically unsaturated double bonds in the molecule, wherein the monomer mixture comprises at least one monomer (b) having at least one free acid group and/or an acid group in salt form; and (2) subsequent partial or complete hydrolysis of the groups —CO—R