Patent ID: 8486227

Claim:
A process for producing paper, board or cardboard by draining a paper stock comprising interfering substances in the presence of one or more polymers which comprise vinylamine units and which have an average molar mass M w of at least 1 million, the process comprising preparing a high-consistency paper stock, metering as said one or more polymers, at least one copolymer of (1) an N-vinyl carboxamide and (2) at least one other ethylenically unsaturated monomer selected from the group consisting of a monoethylenically unsaturated C 3 - to C 5 -carboxylic acid, an ester thereof, a nitrile thereof and an amide thereof, said copolymer comprising vinylamine units and having an average molar mass M w of at least 1 million and a degree of hydrolysis of from 1 to 20 mol % into the high-consistency stock, diluting with water the high-consistency stock to a low-consistency stock, and draining the low-consistency stock.