Improved polyester fiber and method for the production thereof.

摘要

A polyester fiber having a tenacity of at least 4.0 g/d comprises a copolyester having a degree of polymerization of from 80 to 100 of which copolyester 1.0 to 2.0 mol % of its acid component is metal sulfoisophthalic residues, 0.5 to 1.9 weight % of the copolyester being glycol residues provided by a glycol having a molecular weight of from 400 to 6000. The polyester fiber is readily dyed with basic dyes.

The polyester fiber can be prepared by spinning the copolyester at a shear rate of ≤10<Sup>4</Sup> sec<Sup>-1</Sup>, a spinning draft ratio of s250, a back pressure of the spinneret of ≥40kg/cm<Sup>2</Sup> and a shear stress of ≤(Q+0.7)×10<Sup>7</Sup> dynes/cm<Sup>2</Sup>, where Q is the mass output rate per single hole (g/min).