Process for producing regenerated cellulose filaments

Claim 1

PROCESS FOR PRODUCING REGENERATED CELLULOSE FILAMENTS WHICH COMPRISES (1) EXTRUDING HIGHLY XANTHATED VISCOSE, CONTAINING 3-11% BY WEIGHT CELLULOSE AND 3-13% BYY WEIGHT TOTAL ALKALI, SAID VISCOSE HAVING A XANTHATE RATIO OF AT LEAST ABOUT 50 AND A VISCOSITY OF LESS THAN ABOUT 150 POISES, INTO A PRIMARY AQUEOUS ACIDIC PECIPITATION BATH TO FORM GEL FILAMENTS UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, SAID PRIMARY BATH CONTAINING 40-180 GMS./1. OF SULFURIC ACID, 150-400 GMS./1. OF SODIUM SULFATE AND 10-150 GMS./1. OF ZINC SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF ABOUT 45 TO 80*C., SAID GEL FILAMENTS BEING CONTROLLED TO BE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO, (2) PASSING THE RESULTANT FILAMENTS, UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, THROUGH A SECONDARY BATH CONTAINING 5-30 GMS./1. OF SULFURIC ACID, 30-120 GMS./1. OF SODIUM SULFATE AND 0-100 GMS./1. OF ZINC SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF ABOUT 5 TO 30*C., SAID GEL FILAMENTS BEING CONTROLLED TO BE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO IMMEDIATELY PRIOR TO STRETCHING, AND 9 TAINED AT A TEMPERATURE OF ABOUT 10 50*C., SAID (3) STRETCHING SAID FILAMENTS MORE THAN TWICE WHILE PASSING THEM THROUGH A THIRD AND FOURTH BATH, SAID THIRD BATH BEING AT LEAST EQUAL IN REGENERATING POWER TO THE SECONDARY BATH, AND CONTAINING 10-50 GMS./1. OF SULFURIC ACID, 30-120 GMS./1. OF SODUIM SULFATE AND 0-100 GMS./1. OF ZINC SULFATE AND BEING MAINTHIRD BATH REDUCING THE RESIDUAL XANTHATE RATIO BY AT MOST 70%, SAID FOURTH BATH CONTAINING 30-100 GMS./1. OF SULFURIC ACID AND 0-200 GMS./1. OF SODIUM SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF TO 100% AND AT SAID FOURTH BATH 10 TO 80%, AND EACH SUCCESSIVE BATH IN THE PLURALITY OF BATHS BEING AT LEAST AS STRONG IN REGENERATING POWER AS ITS PRECEDING BATH. ABOVE 50*C., THE STRETCH AT SAID THIRD BATH BEING 30