| abstract |
A process for producing paperboard or the like which consists, separately or in a mixture, of adding to the fibrous suspension: at least one main retention agent consisting of a cationic (co) polymer, and at least one dual retention agent consisting of a crosslinked cationic (co) polymer obtained in the form of a dispersion and placed in solution prior to its introduction into the fibrous suspension with slight stirring, said crosslinked cationic (co) polymer having a UL viscosity of between 1, 3 and 2.7 cps, preferably 1.5 and 2.4 cps, and - an apparent cationicity ratio 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 inorganic particles and organic polymers carrying anionic charges. |