Sizing agents for paper based on finely divided aqueous dispersions

摘要

Sizing agents for paper are based on finely divided aqueous dispersions of copolymers obtainable by copolymerizing from 40 to 140 parts by weight of a monomer mixture of (a) from 20 to 65% by weight of (meth)acrylonitrile, (b) from 35 to 80% by weight of one or more acrylates of monohydric saturated C3-C8-alcohols and (c) from 0 to 10% by weight of other ethylenically unsaturated copolymerizable monomers, the weight percentages (a), (b) and (c) always adding up to 100, in the manner of an emulsion polymerization in 100 parts by weight of an aqueous solution containing in solution from 2.7 to 15% by weight of a degraded starch having a viscosity ni from 0.04 to less than 0.12 dl/g at from 40 DEG to 100 DEG C. in the presence of a peroxide initiator.