Patent ID: 8361366

Claim:
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 to 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 draw ratio of from about 1.1:1 to about 30:1; f) removing solvents from said gel yarn while drawing to form an essentially dry yarn containing less than about 10 weight percent of solvents; g) drawing said dry yarn in at least one stage to form a partially oriented yarn having a tenacity of at least about 12 g/d, wherein said partially oriented yarn is produced at a rate of at least about 0.35 g/min per filament of said 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; unrolling said partially oriented yarn, and drawing said partially oriented yarn in at least one stage in a forced convection air oven at a temperature of from about 130° C. to about 160° C. to a draw ratio of from about 1.8:1 to about 10:1 to form a highly oriented yarn having a tenacity of from about 38 g/d to about 70 g/d (34.2 to 63 g/dtex): k) cooling said highly oriented yarn under tension and winding it up; wherein steps a) through i) are conducted continuously in sequence and are discontinuous with continuous sequential steps j) to k).