VERFAHREN ZUR HERSTELLUNG VON FLAMMFEST AUSGERUESTETEM POLYSTYROL.

摘要

Fire retardant polystyrene compsns. contg. (a) halogenated hydrocarbon flame retardant agents together with at least one of (b) a synergist for the (a), (c) stabilisers, (d) antioxidants and (e) additives, are made by a multistage mixing process comprising (1) premixing polystyrene with the (a) and part or all of the (c) at temps. up to 100 deg.C, (2) continuously feeding the premix into a continuously operating single or twin screw extruder or kneader, opt. together with further additives, (3) in a subsequent mixing zone of the extruder, feeding into the prod. stream a monomer- and solvent-free melt of a polystyrene resin at 200-250 deg.C, opt. together with other additives, and (4) extruding and granulating the resulting flame resistant polystyrene compsn..