Thermoplastic compositions in powder form

Claim 1

In an improved process for the production of a pulverulent mixture consisting of (A) from 60 to 99 parts, by weight of the pulverulent mixture, of a brittle copolymer consisting of from 35 to 5%, by weight of brittle copolymer, of acrylonitrile and from 95 to 65%, by weight of brittle copolymer, of a monomer of styrene, α-methylstyrene, methyl methacrylate or mixtures thereof; and (B) from 1 to 40 parts, by weight of the pulverulent mixture, of a rubber-elastic polymer of (1) a flexible rubber-elastic polymer having a glass transition temperature less than 20° C., (2) a graft polymer, the rubber basis of which has a glass transition temperature of less than 20° C., or mixtures of (1) and (2), the improvement consisiting of; in a first stage, a latex of (A) or a mixture of a latex of (A) and a part of a latex of (B) are coagulated by the addition of a coagulant at a temperature of from 20° to 100° C., in a second stage, the latex of (B) or the remaining part of the latex of (B) is added and a sufficient amount of additional coagulent, water or mixtures thereof, is added during the second stage or after the second stage, but before a third stage to obtain a solids to water weight ratio of from 1:3 to 1:15, and in a third stage, the precipitated mixture of (A) and (B) is separated from the aqueous phase and dried.