Process to prepare paper, cardboard and cardboard with high dry strength

Process for preparing paper, cardboard and cardboard with high dry strength by separately adding a polymer containing vinylamine units and an anionic polymer compound to a paper pulp, removing water from the paper pulp and drying the products of paper, characterized in that as an anionic polymer compound, at least one copolymer is used which can be obtained by copolymerization of (a) at least one N-vinylcarboxamides of the formula in which R1, R2> = H or means C1 to C6 alkyl, (b) at least one monoethylenically unsaturated monomer containing acidic groups and / or their salts of methalalkaline, alkaline earth or ammonium and optionally (c) other monoethylenically unsaturated monomers, and optionally (d) compounds having at least two ethylenically unsaturated double bonds in the molecule .