METHOD OF PREPARING ACTYLONITRILE/STYRENE COPOLYMER OF LOWERED RESIDUAL NITRILE COMPONENT CONTENT

摘要

PURPOSE: To prepare an acrylonitrile/styrene copolymer of lowered residual nitrile component content by subjecting a polymer solution to a vacuum treatment, introducing the treated polymer solution into a vented extruder, adding a specified amount of water in divided portions to a position upstream of the vent hole, removing the water and the volatiles from the vent hole and extruding the polymer. ;CONSTITUTION: A stock solution comprising about 50-95 pts.wt. styrene monomer, about 5-50 pts.wt. acrylonitrile monomer, 0-30 pts.wt. other monomers and a polymerization initiator is introduced into a reactor and polymerized. The polymerization solution leaving the reactor is passed through a vacuum tank at a pressure of 5-500mmHg and a temperature of about 100-250°C to lower the residual acrylonitrile monomer content to about 0.003-0.5 pt.wt. per 100 pts.wt. polymer. The polymer is fed into a twin-screw extruder having at least two vent holes, 1-30 pts.wt. water is added to the polymer from at least two water addition sections situated upstream of the vent holes in divided portions, the water and the volatiles are removed from the vent holes at a degree of vacuum of 5-500mmHg, and the polymer is kneaded and extruded to obtain an acrylonitrile/styrene copolymer of a residual acrylonitrile monomer content of below about 0.001 pt.wt.;COPYRIGHT: (C)1996,JPO