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Abstract

Polymer opaque particles and a process for making same are disclosed. These particles comprise an emulsion polymerized core copolymer having, as one constituent thereof, between about 15% and about 40% by weight of a monomer having the general formula: ##STR1## wherein R.sub.1, R.sub.2 and R.sub.4 are independently selected from hydrogen, nitro, amino nitrile, hydroxyl and halogen groups, and organic radicals such as substituted or unsubstituted alkyl, cycloalkyl or aryl groups, R.sub.3 is selected from hydrogen or substituted or unsubstituted organic radicals such as alkyl, cycloalkyl or aryl groups and A is an organic or inorganic bridge connecting the illustrated atoms, the remainder being a mixture of selected olefinically unsaturated acid and ester monomers, said core particles, in turn being encapsulated with an emulsion polymerized sheath copolymer comprised of one or more nonionic olefinically unsaturated monomers to produce said opaque particles. In the present invention, the core polymer resulting from the polymerization of the above-described monomer has a structure in which ##STR2## is a pendant functional group. The finished particles have an average diametric particle size ranging from about 70 to about 4500 nm. and are free of internal microvoids. The present invention further comprises compositions such as paints and paper coatings containing said particles.

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First Claim