PROCESS FOR MANUFACTURING PAPER AND BOARD HAVING IMPROVED RETENTION AND DRAINAGE PROPERTIES

摘要

Process for manufacturing a sheet of paper and/or board having improved retention and drainage properties, according to which, before formation of said sheet and/or board, added to the fibrous suspension are at least two retention aids respectively: a main retention aid corresponding to a (co)polymer having a cationic charge density of greater than 2 meq/g, obtained by Hofmann degradation reaction, a secondary retention aid corresponding to a water-soluble or water-swellable polymer having an anionic charge density of greater than 0.1 meq/g, characterized in that: the main retention aid is introduced into the fibrous suspension in a proportion of 100 to 800 g/t of dry pulp, the secondary retention aid is introduced into the fibrous suspension in a proportion of 50 to 800 g/t of dry pulp and has an intrinsic viscosity IV of greater than 3 dl/g.