Process for continuously dissolving acrylonitrile polymer and spinning the resulting solution

Claim 1

A PROCESS WHICH COMPRISES CONTINUOUSLY PASSING ACRYLONITRILE POLYMER, SELECTED FROM THE GROUP CONSISTING OF HOMOPOLYMERS OF ACRYLONITRILE AND COPOLYMERS OF ACRYLONITRILE WITH UNSATURATED MONOMERS COPOLYMERIZABLE THEREWITH WHEREIN THE COPOLYMERS CONTAIN AT LEAST ABOUT 85% COMBINED ACRYLONITRILE BY WEIGHT, IN THE FORM OF SUBSTANTIALLY DRY, SMALL GRANULES INTO A ZONE OF REDUCED PRESSURE, SIMULTANEOUSLY INTRODUCING INTO THE SAME ZONE TWO STREAMS OF A LIQUID, SELECTED FROM THE GROUP CONSISTING OF DIMETHYLFORMAMIDE AND DIMETHYLACETAMIDE, IN THE FORM OF TWO-SEPARATED CONCENTRIC CYLINDRICAL CURTAINS OF LIQUID ABOUT THE ENTERING ACRYLONITRILE POLYMER, SAID ZONE BEING MAINTAINED AT A REDUCED PRESSURE ZONE LESS THAN ABOUT 10LBS./SQ. IN. ABS., ADMIXING THE SOLVENT AND ACRYLONITRILE POLYMER IN THE REDUCED PRESSURE ZONE UNTIL SOLUTION IS EFFECTED, CONTINUOUSLY DISCHARGING THE SAID SOLUTION FROM THE REDUCED PRESSURE ZONE AND SPINNING SAID SOLUTION, AS SOON AS FORMED AND WITHOUT RECIRCULATION, AT SUPERATMOSPHERIC PRESSURE INTO FIBERS, RESIDENCE TIME OF THE LIQUID AND ACRYLONITRILE POLYMER IN THE REDUCED PRESSURE ZONE BEING BETWEEN ABOUT 5 SECONDS AND ABOUT 5 MINUTES.