Method for controlling size distribution of polymer particles during preparation of aqueous polymer dispersion and aqueous polymer dispersion

摘要

The present disclosure relates to a method for controlling size distribution of formed polymer particles during preparation of aqueous polymer dispersion. The method comprises obtaining an aqueous polysaccharide solution, which comprises about 10 to 40 weight-% polysaccharide containing a free hydroxyl group, such as starch, and polymerising in the polysaccharide solution in the presence of a graft-linking, water-soluble redox system about 30 to 60 weight-% of at least one optionally substituted styrene, about 60 to 30 weight-% of at least one C1-C4-alkyl (meth)acrylate, and 0 to about 10 weight-% of other ethylenically unsaturated copolymerizable monomers. The size distribution of the formed polymer particles is controlled by adjusting viscosity of the polysaccharide solution before the polymerisation to a level less than about 20 mPas.

主权项

1. An aqueous polymer dispersion obtained by free radical emulsion copolymerization of ethylenically unsaturated monomers in the presence of
(a) 10 to 40 weight-% polysaccharide containing a free hydroxyl group, the monomers comprising (b) 30 to 60 weight-% of at least one optionally substituted styrene, (c) 60 to 30 weight-% of at least one C1-C4-alkyl (meth)acrylate, and (d) 0 to 10 weight-% of other ethylenically unsaturated copolymerizable monomers, and using (e) a graft-linking, water-soluble redox system as free radical initiator for the free radical emulsion copolymerization, wherein the sum (a)+(b)+(c)+(d) is 100%, wherein the dry solids content of the dispersion is >35 weight-%, based on the weight of the total dispersion and the polymer dispersion has a D(50) value <60 nm and D(99) value <130 nm for polymer particles in the polymer dispersion.