HIGH-STRENGTH POLYESTER YARN AND PROCESS FOR ITS PREPARATION

摘要

of the disclosure: The invention relates to a high-strength polyester yarn having a heat shrinkage at 200.degree.C of less than 7X, a degree of elasticity ED20 of at least 90%, a stability quotient SQ of at least 7.5 and a crystallinity of about 57 to 65%. Such yarns can be obtained by high-speed pinning of filaments which have at least a birefringence of 0.025 and an average molecular weight corresponding to a relative viscosity of 1.9 to 2.2 and are subjected to a stretching at high temperatures using a stretch ratio of at least 90X of the maximum cold stretch ratio and a stretching tension between 19 and 23 cN/tex.