Acrylonitrile-styrene copolymer filaments and process of producing same

Claim 1

A PROCESS FOR PRODUCTION OF A FILAMENT CONSISTING ESSENTIALLY OF ACRYLONITRILE-STYRENE COPOLYMER WHICH COMPRISES COPOLYMERIZING ACRYLONITRILE AND STYRENE IN AQUEOUS EMULSION USING AN INORGANIC POLYMERIZATION CATALYST AND TEMPERATURES NOT ABOVE ABOUT 75* C., IN MONOMER WEIGHT RATIOS OF ABOUT 4:1 OF ACRYLONITRILE: STYRENE, DISSOLVING THE RESULTING COPOLYMER IN DIMETHYL FORMAMIDE, ADJUSTING THE SOLUTION CONCENTRATION TO VISCOSITY BETWEEN ABOUT 300 AND ABOUT 1000 POISES, EXTRUDING SAID SOLUTION IN FILAMENT FORM INTO A WATER BATH WHEREIN THE DIMETHYL FORMAMIDE CONTENT OF EXTRUDED FILAMENT IS REDUCED TO ABOUT 50-80 WEIGHT PERCENT AND WATER ENTERS THE FILAMENT FORMING A SURFACE GELLED FILAMENT OF TENSILE STRENGTH AT LEAST ABOUT 0.1 GRAM PER DENIER; PASSING SAID FILAMENT THROUGH A HOT EVAPORATING ZONE IN WHICH TEMPERATURES OF ABOUT 130*-150* C. ARE REACHED AND WHEREIN THE DIMETHYL FORMAMIDE CONTENT OF SAID FILAMENT IS REDUCED TO NOT MORE THAN ABOUT 8% BY WEIGHT, GEL BEING THUS CONVERTED TO COHERENT SOLID FILAMENT OF TENSILE STRENGTH AT LEAST ABOUT 0.5 GRAM PER DENIER; AND THEREAFTER STRETCHING SAID FILAMENT IN A ZONE MAINTAINED AT TEMPERATURES BETWEEN ABOUT 140* C. AND ABOUT 175* C. TO BETWEEN ABOUT 250% AND ABOUT 1400% BEYOUND THE ORGINAL FILAMENT LENGTH.