PROCESS FOR ACHIEVING HIGHER ORIENTATION IN PARTIALLY ORIENTED YARNS

摘要

ABSTRACT OF THE DISCLOSUREProvided is a process for melt spinning a partiallyoriented yarn of increased birefringence, and hence higherorientation, for a given wind-up speed. The process comprisesextruding a molten fiber forming polyester through a shapedorifice to form a molten filamentary material, which is thenpassed in the direction of its length into a quench zone whereinthe filamentary material is contacted with a first gaseousquenching medium. While the filamentary material is still in adeformable state, however, it is passed through a hot zoneprovided with an atmosphere having a temperature greater than thefirst gaseous quenching medium and greater than the glass transi-tion temperature of the molten polyester filamentary material.The filamentary material is then withdrawn from the hot zone andcontacted with a second gaseous quenching medium at a temperaturebelow the glass transition temperature of the filamentarymaterial until the filamentary material is no longer deformable,after which the filamentary material is withdrawn from the quenchzone.-1-