Mixtures of thermoplastic polymers in powder form

DETAILED DESCRIPTION What is claimed is: 1.
A process for the production of mixtures of thermoplastic polymers in powder form from aqueous emulsions of a) a thermoplastic resin in the form of a homopolymer or copolymer of styrene, .
alpha.
-methyl styrene, methyl methacrylate or acrylonitrile optionally containing up to 30% by weight of a rubber and b) a rubber-rich polymer of styrene, .
alpha.
-methyl styrene, acrylonitrile, methyl methacrylate on a diene or alkyl acrylate rubber having a rubber content of 50 to 90% by weight, characterized in that separate aqueous emulsions of a) and b) having polymer contents of 15 to 50% by weight are separately but continuously or semicontinuously mixed in separate product streams with a coagulation solution at 50.
degree.
to 100.
degree.
C.
thereby causing separate coagulation of the polymers a) and b), whereupon the product streams are combined and the polymer mixture is then separated off.
2.
A process as claimed in claim 1, characterized in that 50 to 95% by weight of component a) and 5 to 50% by weight of component b) are mixed.
3.
Mixtures of thermoplastic polymers in powder form obtained by the process claimed in claim 1.




Description:
This invention relates to a process for the production of mixtures of thermoplastic polymers in powder form from aqueous emulsions of the polymers.
The process is technically particularly simple and gives powder-form mixtures of reduced dust content, improved free flow and stability in storage, so that subsequent processing is also made much easier.
Mixtures of thermoplastic resins (for example copolymers of vinyl compounds) and graft polymers of vinyl compounds on rubbers and also mixtures of various graft polymers of vinyl compounds on rubbers are technically important thermoplastic molding compositions.
Many of these resins and graft polymers have to be produced in aqueous emulsion and isolated therefrom.
To produce molding compositions containing resin and graft polymers, the emulsions of the polymers accumulating may be mixed and the resulting mixture worked up