Process for making a yarn having improved strength retention and yarn made thereby

Abstract

The invention relates to a continuous process for making a yarn comprising filaments of poly (paraphenylene terephthalamide) and the yarn made thereby, the process utilizing a coagulation bath having a temperature of at least 20° C., washing with an aqueous liquid, and drying the filaments under a tension of 0.3 to 1.0 grams per denier wherein the filaments are dried for 0.4 to 0.9 seconds at a temperature of from 250 to 325° C. The yarn has a tenacity of at least 22 gpd, an elongation at break of at least 3.2 percent, and a tensile modulus of from 530 to 700 gpd; the yarn further has a heat-aged strength retention (HASR) of at least 93 percent and the filaments in the yarn have a D110 crystallinity of at least 55 angstroms.

Dependencies are inferred from the claim text.