Preparation of poly(p-phenylene terephthalamide) by mixing solution of p-phenylene diamine with molten terephthaloyl chloride

Claim 1

IN A PROCESS WHEREIN A SOLUTION OF P-PHENYLENE DIAMINE AND HEXAMETHYLPHOSPHORAMIDE IS MIXED WITH MOLTEN TEREPHTHALOYL CHLORIDE AND THE RESULTING MIXTURE IS FORWARDED WITHIN ONE SECOND TO A FIRST POLYMERIZER WHERE IT IS MIXED WITH COOLING TO YIELD A PARTIALLY POLYMERIZED PRODUCT HAVING A VISCOSITY OF FROM ABOUT 10 TO 100 POISES AND A TEMPERATURES OF LESS THAN ABOUT 95*C. AND SAID PRODUCT IS THEN PASSED TO AN EXTERNALLY COOLED SECOND POLYMERIZATION CHAMBER, THE IMPROVEMENT COMPRISING INTRODUCING SAID PARTIALLY POLYMERIZED PRODUCT INTO ONE END OF SAID SCOND POLYMERIZATION CHAMBER AND FORWARDING IT TO THE EXIT OF THE CHAMBER WHILE MIXING AND SHEARING IT AT A RATE OF AT LEAST 100 SEC.*1 AS IT PASSES THROUGH SAID POLYMERIZATION CHAMBER, RECYCLING A PORTION OF IT AS IT FLOWS TOWARDS THE EXIT OF THE POLYMERIZATION CHAMBER IN A PLURALITY OF ZONES ALONG THE FLOW PATH WHEREBY THE RETENTION TIME OF THE RECYCLED MATERIAL IN THE POLYMERIZATION CHAMBER IS INCREASED BEYOND THE TIME IT WOULD HAVE REMAINED IN THE CHAMBER IN THE ABSENCE OF RECYCLING, AND WITHDRAWING A CRUMB-LIKE PRODUCT CONTAINING HIGH MOLECULAR WEIGHT POLY(PPHENYLENE TEREPHTHALAMIDE) FROM THE EXIT OF THE POLYMERIZATION CHAMBER, THE SAID MATERIAL STREAM BEING RETAINED IN THE POLYMERIZATION CHAMBER FOR FROM 1 TO 15 MINUTES AND BEING UNIFORMLY COOLED TO RESULT IN AN EXIT TEMPERATURE BETWEEN ABOUT 40*C. AND 95*C.