Process for producing hygroscopic acrylic fibers

Claim 1

A PROCESS FOR PRODUCING HYGROSCOPIC ACRYLIC FIBERS WHICH INCLUDES THE STEPS OF A. PREPARING A SPINNING SOLUTION BY DISSOLVING AN ACRYLONITRILE COPOLYMER CONTAINING MORE THAN 50% BY WEIGHT OF ACRYLONITRILE WITH AT LEAST ONE OTHER POLYMERIZABLE MONOMER HAVING THE $C=C$ STRUCTURE AND COPOLYMERIZABLE THEREWITH IN A SOLVENT THEREOF, B. EXTRUDING SAID SPINNING SOLUTION INTO AN AQUEOUS COAGULATION LIQUID CONTAINING SAID SOLVENT TO FORM FIBERS, CONTAINING OPEN CAPILLARY VOIDS, C. STRETCHING THE THUS FORMED FIBERS, D. ANNEALING THE STRETCHED FIBERS IN THE WET STATE WITH SATURATED STEAM AT A PRESSURE OF 0.3 TO 2.8 KG/CM2, E. DRYING THE ANNEALED FIBERS AT A TEMPERATURE OF LOWER THAN 110*C, AND F. TREATING THE FIBERS WITH AN AQUEOUS SOLUTION CONTAINING A COMPOUND AS A MODIFIER SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, ALKALI METAL CARBONATE SULFURIC ACID, HYDROCHLORIC ACID AND HYDROXYLAMINE SALT TO RENDER THE SURFACE OF THE FIBERS HYDROPHILIC AND ACCELERATE CONDENSATION OF MOISTURE IN THE VOIDS.