Uniformly dyeable nylon 66 fiber and process for the production thereof

Abstract

A nylon 66 fiber capable of being uniformly dyed and having an initial modulus at 20.degree. C. and a relative humidity of 60% of about 15 g/d to about 65 g/d and a relationship of a peak temperature [T.sub.max (.degree.C.)] at peak of dynamic mechanical loss tangent (tan .delta.) measured with a frequency of 110 Hz and a peak value of the dynamic mechanical loss tangent [(tan .delta.).sub.max ] represented by the equation: T.sub.max (.degree.C.).ltoreq.-320(tan .delta.).sub.max +132 The fiber has such a structure that refractive indices are different between an outer layer of the fiber and an inner layer of the fiber. The fiber is made by extruding a melt of nylon 66, passing the extruded filaments through a heating zone provided at the surface of the extrusion nozzle and having a length of at least about 5 cm and a temperature of about 150.degree. C. to about the melting point of the polymer, applying a suction with an aspirator located below the heating zone, and then winding at a winding speed of at least about 4,000 m/min.

Dependencies are inferred from the claim text.