Patent ID: 7846363
Filing Date: 2010-12-07
Classification: D01D,D01F,Y10T

Abstract:
1. A process for the production of a multi-filament poly(alpha-olefin) yarn comprising the steps of: a) forming a solution of a poly(alpha-olefin) in a solvent at an elevated temperature, said poly(alpha-olefin) having an intrinsic viscosity when measured in decalin at 135° C. of from about 5 to about 45 dl/g; b) passing said solution through a multi-filament spinneret to form a solution yarn, said spinneret being at an elevated temperature; c) drawing said solution yarn at a draw ratio of from about 1.1:1 to about 30:1; d) rapidly cooling said solution yarn to a temperature below the gel point of said solution, to form a gel yarn; e) drawing said gel yarn in at least one stage to a first draw ratio DR1; f) removing solvents from said get yarn while drawing at a second draw ratio DR2 in at least one stage to form an essentially dry yarn containing less than about 10 weight percent of solvents; g) drawing said dry yarn to a third draw ratio DR3 of from about 1.10:1 to about 2.00:1 in at least one stage to form a partially oriented yarn; h) optionally relaxing said partially oriented yarn from about 0.5 to about 5% of its length; i) winding up said partially oriented yarn; j) unrolling said partially oriented yarn and drawing it in at least one stage at a temperature of from 130° C. to 160° C. to a fourth draw ratio DR4 f from about 1.8:1 to about 10:1 to form a highly oriented yarn having a tenacity of from about 38 to about 70 g/d (34.2 to 63 g/dtex) as measured by ASTM D2256-02 at 10 inch (25.4 cm) gauge length and a strain rate of 100%/min; k) cooling said highly oriented yarn under tension and winding it up; wherein the product of the draw ratios DR1×DR2×DR3 is greater than or equal to about 5:1, wherein the fractional off-line draw of the dry yarn (FOLDY), defined by the relationship, is from about 0.75 to about 0.95, and wherein steps a) through i) are conducted continuously in sequence and are discontinuous with continuous sequential steps j) to k).