Patent ID: 8404083

Claim:
A process for producing paper, board or cardboard, comprising: adding at least one water-soluble cationic polymer and at least one water-soluble polymeric anionic compound to a paper stock; draining the paper stock with formation of a sheet; drying the sheet; and, wherein the water-soluble cationic polymer comprises (a) a polymer comprising a vinylamine and (b) a polymer comprising an ethylenimine, wherein the water-soluble polymeric anionic compound carries at least one acid group or a salt thereof selected from the group consisting of a carboxyl group, a sulfo group and a phosphonic acid group, wherein the water-soluble polymeric anionic compound has a charge density of >0.5 meg/g, and wherein the addition metering of the water-soluble cationic polymer is effected by adding the polymer comprising a vinylamine and the polymer comprising an ethylenimine individually in sequence or a mixture thereof into the paper stock.