Celanese Gmbh

Douglas D Roth

Fredrick A Ethridge

A melt-spinning apparatus is disclosed for reducing the birefringence variability of melt-spun yarn made at high pack throughputs. It involves extruding polymer at an average mass-flow rate through a first group of orifices (defined by specific location in the spinnerette), that is greater than the mass-flow rate of polymer through a second group of orifices (also defined by location in the spinnerette). The apparatus comprises a spinneret having concentric rows of orifices and a centrally located quench means, with the diameter, d.sub.1, of the orifices in the row closest to the quench means being greater than the diameter, d.sub.2, of the orifices in the row furtherest from the quench means by an amount such that d1/d2 is in the range from 1.03 to 1.20.

Melt-spinning apparatus for polyester filaments

A melt-extrusion process is disclosed for reducing the birefringence variability of melt-spun yarn made at high pack throughputs. It involves extruding polymer at an average mass-flow rate through a first group of orifices (defined by specific location in the spinnerette), that is greater than the mass-flow rate of polymer through a second group of orifices (also defined by location in the spinnerette). It is preferred that a spinnerette be used in which the dimensions of the orifices differ from group to group in a defined manner.

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Matthews, NC, United States of America

Douglas D Roth