Abstract: Paper, board and cardboard are produced by shearing the paper stock, adding a microparticle system comprising a cationic polymer and a finely divided inorganic component to the paper stock after the last shearing stage before the head box, draining the paper stock with sheet formation and drying the sheets, by a process in which cationic polyacrylamides, polymers containing vinylamine units and/or polydiallyldimethylammonium chloride having an average molar mass Mw of in each case at least 500 000 Dalton and a charge density of in each case not more than 4.0 meq/g are used as cationic polymers of the microparticle system.

Abstract: Paper, board and cardboard are produced by shearing the paper stock, adding a microparticle system comprising a cationic polymer and a finely divided inorganic component to the paper stock after the last shearing stage before the head box, draining the paper stock with sheet formation and drying the sheets, by a process in which cationic polyacrylamides, polymers containing vinylamine units and/or polydiallyldimethylammonium chloride having an average molar mass Mw of in each case at least 500 000 Dalton and a charge density of in each case not more than 4.0 meq/g are used as cationic polymers of the microparticle system.

Abstract: Paper and cardboard are produced by draining a paper stock by a method in which a stock having a consistency of from 2.5 to 5% by weight is used as a starting material, and (a) from 0.1 to 2% by weight of an activated bentonite are added and the stock consistency is then brought to 0.3-2% by weight by dilution with water, after which (b) from 0.01 to 0.1% by weight of a cationic polyelectrolyte having a charge density of not less than 4 meq/g of polyelectrolyte is added and distributed therein, and, after thorough mixing (c) from 0.003 to 0.3% by weight of a high molecular weight polymer based on acrylamide or methacrylamide is metered in and mixed with the paper stock, the percentages in each case being based on dry paper stock, and the resulting pulp is drained on a wire. The paper obtained is distinguished in particular by good printing properties in the offset printing process.