Patent ID: 6406593
Filing Date: 2002-06-18
Classification: C08F,D21H

Abstract:
A process of making paper or paper board comprising forming a cellulosic suspension, flocculating the suspension, mechanically shearing the suspension and reflocculating the suspension, draining the suspension on a screen to form a sheet and then drying the sheet,wherein the suspension is flocculated by introducing a cationic water-soluble polymer that has been formed from a water-soluble monomer or monomer blend comprising at least one monomer, of intrinsic viscosity above 3 dl/g into the suspension, wherein in that the water soluble polymer exhibits a rheological oscillation value of tan delta at 0.005 Hz of above 1.1 (calculated on a 1.5% by weight aqueous solution of polymer), wherein the cellulosic suspension is reflocculated by introducing a flocculating material in which the flocculating material is an anionic branched water-soluble polymer that has been formed from water-soluble ethylenically unsaturated anionic monomer or monomer blend and branching agent and wherein the flocculating polymer has an intrinsic viscosity above 4 dl/g and a tan delta at 0.005 Hz of above 0.7 (calculated on a 1.5% by weight aqueous solution of polymer), wherein the mechanical shearing is achieved by passing the flocculated cellulosic suspension through one or more shear stages selected from a centriscreen and a fan pump.