GB832822A - Improvements in the production of thermoplastic polymeric materials - Google Patents

Abstract

Graft polymers are prepared by polymerizing 100 parts of a monomeric mixture of 50-90 parts styrene and 10-50 methacrylonitrile in the presence of a stable aqueous dispersion of 20-70 parts of rubbery polybutadiene-1,3. The butadiene may be polymerized in aqueous emulsion until about 75% has been converted to polymer, the excess monomer removed, e.g. by steam distillation, and the styrene-methacrylonitrile added and polymerized. Oxygen-yielding catalysts, e.g. hydrogen peroxide, potassium persulphate, or redox catalysts, e.g. cumene hydroperoxide or benzoyl peroxide with a heavy metal salt and sorbose or fructose are preferably present, as may also such polymerization modifiers, e.g. di-(sec.butyl) or di-(2-methyl-butyl) disulphide, dialkyl xanthogen disulphides, nitrodiaryl polysulphides and primary, secondary and tertiary alkyl mercaptans, e.g. dodecyl mercaptan. The usual emulsifying agents may be present as may pigments, fillers and stabilizers. The products may be shaped or moulded and vulcanized.