Patent ID: 8343311
Filing Date: 2013-01-01
Classification: D21H

Abstract:
1. A method for producing paper, cardboard or similar materials, which comprises, separately or in a mixture, adding to a fibrous suspension: at least one main retention agent comprising a cationic (co)polymer, and at least one dual retention agent comprising, a crosslinked cationic (co)polymer obtained in the form of a water-in-water type emulsion or standard reverse emulsion other than microemulsion, and placed in solution with gentle stirring prior to its introduction into the fibrous suspension, said crosslinked cationic (co)polymer having a UL viscosity of between 1.3 and 2.7 cps, and an apparent cationicity ratio of between 25 and 75%, and, optionally, before or after the dual agent or the main retention agent, one or more tertiary retention agent(s) selected from the group consisting of mineral particles and organic polymers carrying anionic charges, wherein the at least one main retention agent and the at least one dual retention agent have an overall cationic charge.