Hochorientierte nichtverstreckte Polyesterfasern und Verfahren zu ihrer Herstellung

摘要

Highly oriented undrawn polyester fibers show a diffraction peak, due to crystals of the polyester, observable in a wide angle x-ray diffraction image of the fibers and having a birefringence of 0.015 to 0.05. A process for preparing highly oriented undrawn core-sheath type conjugated polyester fibers which may have such diffraction and birefringence properties comprises the step of spinning a polyester as the sheath polymer and a polymer having a gradient of elongational viscosity with temperature larger than that of the sheath polymer, at a spinning speed of 4000 to 12000 m/min. The fibers may be falsetwisted to obtain a textured yarn.