Polymer aggregates

Abstract

Polymer aggregates in the form of discrete particles of controlled particle size below 150 microns maximum dimension which are themselves aggregates of primary particles of a polymer or polymers derived from at least one ethylenically unsaturated monomer together with from 0 to about 400%, by weight on the weight of the monomer, of an organic thickener compatible with the monomer, said aggregate particle containing from 0 to about 95% by weight of pigment and/or extender are made by providing an aqueous dispersion of the monomer and thickener, a hydrophilic colloid being present in the aqueous phase of the dispersion and pigment and/or extender optionally being present in either the aqueous phase or the disperse phase, introducing a polymerization initiator into the aqueous phase of the dispersion, and maintaining the dispersion under conditions of high shear and continuing polymerization to substantial completion thereof. The aggregates are useful in coating comositions, e.g. to provide a matt finish.

Dependencies are inferred from the claim text.