Improved high speed process for forming fully drawn polyester yarn
(57) @ An improved process is provided for producing fully drawn multifilamentary polyethylene
terephthalate yarn via a high speed melt spinning process wherein the multifilamentary
material following solidification is passed through a heated conditioning zone wherein
substantial crystallisation takes place. Such multifilamentary product is withdrawn
from the conditioning zone at a speed in excess of 8000 feet (2438 m) per minute and
a conventional drawing step is not required. In accordance with the concept of the
present invention it surprisingly has been found that the uniformity of the multifilamentary
product is enhanced by the inclusion of a minor substantially uniformly dispersed
concentration of particulate silicon dioxide (e.g. fumed silica) in the molten polyethylene
terephthalate polymer prior to extrusion and such subsequent processing. In a particularly
preferred embodiment the particulate silicon dioxide is substantially uniformly dispersed
within the polyethylene terephthalate as a result of its prior admixture with the
reactants which were polymerised to form the polyethylene terephthalate.