Patent ID: 8647470

Claim:
A process for the production of paper, board, and cardboard having high dry strength, the process comprising: (I) metering into a paper stock an aqueous composition comprising a nanocellulose comprising cellulose fibers and at least one anionic polymer and optionally a water-soluble cationic polymer; (II) draining the paper stock, to obtain paper product; and (III) drying the paper product; wherein the anionic polymer comprises, as polymerized units: (a) at least one monomer selected from the group consisting of a C 1 - to C 20 -alkyl acrylate, a C 1 - to C 20 -alkyl methacrylate, a vinyl ester of a saturated carboxylic acid comprising up to 20 carbon atoms, a vinylaromatic comprising up to 20 carbon atoms, an ethylenically unsaturated nitrile, a vinyl ester of a saturated, monohydric alcohol comprising 1 to 10 carbon atoms, a vinyl halide, and an aliphatic hydrocarbon comprising 2 to 8 carbon atoms and one or two double bonds; (b) at least one anionic monomer selected from the group consisting of an ethylenically unsaturated C 3 - to C 8 -carboxylic acid, a vinylsulfonic acid, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylphosphonic acid, and salts thereof; (c) optionally, at least one monomer selected from the group consisting of a C 1 - to C 10 -hydroxyalkyl acrylate, a C 1 - to C 10 -hydroxyalkyl methacrylate, acrylamide, methacrylamide, an N—C 1 - to C 20 -alkylacrylamide, and an N—C 1 - to C 20 -alkylmethacrylamide; and (d) optionally, a monomer comprising at least two ethylenically unsaturated double bonds in the molecule.