Heat setting a tow of synthetic fibers using high pressure dewatering nip

Abstract

An apparatus and method for heat setting a traveling tow of synthetic filaments utilizing a high pressure dewatering nip roll mechanism to remove moisture from the tow prior to heat setting. The high pressure dewatering nip roll mechanism includes a pair of nip rollers exerting a pressure of between about 500 and 2000 pounds per linear inch of transverse nip contact on the traveling tow prior to the tow entering a heat setting apparatus such as a calender apparatus. Moisture content of the traveling tow is reduced to less than 10% moisture by weight and preferably less than 5%. Reducing the moisture content of the tow prior to heat setting reduces the energy required to heat set the tow and, contrary to the prevailing wisdom in the art, does not damage the unheat set filaments of the tow. A process of treating a traveling tow of synthetic filaments is also disclosed which includes the steps of drawing the tow to combine molecule chains and orient the molecules substantially along the filament axis, subjecting the tow to moisture during the drawing step, dewatering the tow using a pair of high pressure dewatering nip rolls and then heat setting the tow to crystallize a majority of the molecules in the synthetic tow material, thereby producing a strong tow while minimizing the amount of energy required to heat set the tow.

Dependencies are inferred from the claim text.