METHOD FOR PRODUCING EXPANDING STYRENE POLYMER GRANULES

A method for supplying molten polymer and expanding agent flows to a mixing area, by dispersing the expanding agent in a polymer melt by a rapid dividing mixing in a first static mixer, holding and intensively dividingly mixing the thus obtained mixture in a second static mixer, cooling the mixture, during mixing, in a third static mixer to an intermediate temperature, cooling the mixture to a granulation temperature, extruding polymer threads and subsequently quenching and granulating them. During processing, a weight ratio between the polymer melt flow Gp and the expanding agent flow GBA ranges from 13.0 to 19.0, a temperature in the first static mixer for rapid dividing mixing is calculated according to formula (I), in the second and third static mixed according to formulas (II) and (III), respectively, wherein GBA max. is the quantity of a maximum possible expanding agent flow, GBBct. is the quantity of the used expanding agent flow at the ratio between the melt flow index and a weight average molecular mass (Mw) ranges within of (0.8-12.0)×10−5. The method of this invention makes it possible to produce polysteren in the form of expanding granules, within a wide range of molecular masses, and a shock-resistant polysterene.