Thermoplastic and thermoset polymer compositions

Claim 1

A process for preparing a thermoplastic polymer composition comprising thermoplastic matrix polymer and, distributed throughout the thermoplastic matrix polymer, substantially spherical core-shell polymer particles, said particles having an average diameter of from 2 to 15 μm and a particle size distribution such that at least 90% by weight of the particles fall within ±20% of the average particle diameter, a core of rubbery alkyl acrylate polymer and one or more shells, the outer shell of which is compatible with the matrix polymer, wherein the process comprises: A) polymerizing a first aqueous emulsion of the one or more monomers which, when polymerized, produce a particulate composition comprising polymer particles; B) performing one or more times the steps of 1) swelling the particles of the particulate composition produced in A), or if appropriate the particles of B2), with one or more monomers, and 2) polymerizing the swelling monomer within the particles until all of the monomers have been polymerized; and c) polymerizing one or more monomers which are polymerizable to form a polymer compatible with the matrix polymer to produce the core-shell polymer particles, and blending the resulting core-shell polymer particles, in an amount of 0.1 to 40% by weight of the total composition, with said thermoplastic matrix polymer.