Process for producing self-crimping polyester yarn

Abstract

Provided is a process for forming and modifying a self-crimping polyester yarn comprising a plurality of polyester filaments having thick and thin regions along their lengths which are out of phase from filament to filament. The plurality of filaments are produced by first forming a plurality of combined streams of molten melt spun polyester by combining at least first and second extruded molten streams of fiber forming polyester travelling at different extrusion speeds to thereby form thick and thin regions in the combined streams out of phase from other combined streams. The combined streams are then quenched and thereby transformed into solid filaments in a solidification zone provided with a gaseous atmosphere at a temperature below the glass transition temperature of the polyester. The resulting filaments are then passed in the direction of their lengths through a conditioning zone, which zone is provided with a gaseous atmosphere at a temperature sufficient to produce polyester filaments which exhibit a percent yarn shrinkage in the range of from about 10 to about 45 percent. The resulting filaments are withdrawn from the conditioning zone at a substantially constant wind-up speed. The yarn thus obtained still exhibits a useful degree of crimp as well as properties similar to those observed in yarns spun at much higher wind-up speeds.