SHEATHHCORE TYPE AROMATIC POLYAMIDE FIBER

摘要

PURPOSE:The title fiber having a reverse double structure of an easily dyeable skin layer (S) and a sparingly dyeable core layer (C) comprising the readily soluble S and the sparingly soluble or insoluble C. CONSTITUTION:An aromatic polyamide fiber, preferably having m-phenylene isophthalamide structural units, and comprising a readily soluble skin layer (S) and a sparingly soluble or insoluble core layer (C). A poly m-phenylene isophthalamide solution is extruded into an aqueous coagulation bath containing an inorganic salt, preferably calcium chloride, and coagulated. The resulting fiber is then washed with water at 0-25 deg.C, drawn in boiling water at 90 deg.C or above, hot-drawn at 320-360 deg.C under such conditions to satisfy the formulas DR1XDR23.5 and DR1 1.5 (DR1 is the draw ratio in boiling water; DR2 is the draw ratio in hot-drawing), and finally dried at 120 deg.C or below.