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Abstract

Poly(ethylene terephthalate) filaments of enhanced dyeability, low boil-off shrinkage (even in as-spun condition), good thermal stability over a large temperature range; and useful as texturing feed yarns and/or as hard yarns requiring no further drawing are prepared by spinning at extremely high speeds, and are characterized by a long period spacing above 300 A in their as-spun condition, and, whether in as-spun condition or after heat-treatment, by a low skin-core value as measured by a differential birefringence in relation to their stress measured at 20% extension (which correlates approximately with the spinning speed), a large crystal size, and low amorphous orientation. The continuous filament yarns may be draw-textured to provide textured yarns which also show enhanced dyeability. The staple fiber yarns also have very useful properties as compared with conventional staple yarns. A preferred process of spinning at these extremely high speeds is characterized by the use of a spinneret with capillary-dimensions that produce high shear as the polyester is extruded, and is applicable also to copolyesters, whose filaments show a similar low skin-core in relation to their stress at 20% extension, the precise values for copolymers being different from the relationship for poly(ethylene terephthalate).

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First Claim