During the manufacture of paper from a cellulosic suspension, retention is improved by adding to the suspension a water soluble cationic polymer containing 0.1 to 15 mole % cationic monomer groups and having an intrinsic viscosity of at least 4 dl/g and then adding a substantially water...http://www.google.es/patents/US5733414?utm_source=gb-gplus-sharePatente US5733414 - Process of making paper
