PROCESS FOR DIMENSIONALLY STABLE POLYESTER YARN

摘要

The invention is directed to a process for production of a dimensionally stable drawn polyethylene terephthalate multifilament yarn having filaments of at least 2.5 denier per filament comprising the steps of: a) extruding a polyethylene terephthalate polymer melt through a spinnerette having a plurality of extrusion orifices to form filaments; b) advancing the extruded multifilament yarn first through a delay zone then through a quenching zone to solidify the filaments in a controlled manner; c) withdrawing the solidified multifilament yarn from the quenching zone at a desired spinning speed V; whereby steps a) through c) are performed under conditions to form a partially-oriented multifilament yarn having an undrawn birefringence ( DELTA nu) of at least 0.020 and wherein DELTA nu = Rf V<2.0> IV<2.4> where IV is the intrinsic viscosity of the undrawn yarn and is at least 0.80 and Rf is at least 9.0 x 10<-3>; then d) hot drawing the partially-oriented multifilament yarn. The process permits production of high undrawn birefringence yarns at lower speeds and lower IV's than previously demonstrated in the prior art.