| abstract |
A process aid for dewatering/retention (I) contains a combination of (a) microparticles and (b) a vinylamine copolymer of formula (II) with a charge density of 2-24 m-eq./g. m = 1-99 mole%; n =0-50 mole%; o = 1-99 mole%; A = units of formula (i), (ii), or (iii); p, q,m rt = 1-99 mole%; R<1> = H or Me; X = -CN, -COOR<2>, 0CONR<3>R<4>, -OR<5>, -OCOR<6> and/or R<2>-R<6> = H or 1-4C alkyl. Also claimed are (i) a process for the prodn. of paper or cardboard, in which (I) is added to the aq. pulp suspension as a dewatering/retention aid, and (ii) paper or cardboard prods. contg. (I). |