Patent ID: 7674409

Claim:
A process for simultaneously drawing multiple ultra-high molecular weight poly(alpha-olefin) (UHMWPO) yarns comprising the steps of: a) forming a plurality of substantially identical gel-spun multi-filament feed yarns comprising an UHMWPO having an intrinsic viscosity measured in decalin at 135° C. from 5 dl/g to 45 dl/g, said feed yarns having a tenacity of from 5 g/d to 65 g/d (0.43 GPa to 5.56 GPa) as measured by ASTM D2256-02, a denier of from 100 to 20,000, and the filaments of said yarns being of from 0.5 to 100 denier/filament (0.055 to 11.1 text/filament); b) winding up said plurality of feed yarns without imparting twist to the yarns; c) unrolling the plurality of feed yarns without imparting twist to the yarns, wherein the unrolling torque is from about 0.6 lb-in (0.07 N-m) to about 1.2 lb-in (0.14 N-m) and the unrolling torque is substantially the same for each yarn; d) passing the plurality of feed yarns simultaneously and continuously into, through, and out of an oven, wherein one or more zones are present along the yarn path, said zones having zone temperatures in the range of about 100° C. to about 165° C., and wherein the exiting speed of the yarns from the oven is greater than the entrance speed of the yarns into the oven, said yarns being drawn in the oven; e) cooling the drawn yarns under tension; and f) winding up a plurality of the drawn yarns without imparting twist thereto.