Core yarn comprising a core of high-strength polyester material, method of manufacturing the same, and the application of selected polyester materials for manufacturing core yarns

摘要

There are described core yarns with selected filamentary polyester cores. The core yarns are characterised in that a) the polyester material of the core filaments has an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25 DEG C) of at least 1.9, and b) the core has a tenacity (specific strength) of at least 60 cN/tex, and c) the core yarn has a seam length to rupture of more than 800 cm in a sewing test under aggravated conditions, said sewing test being carried out on four plies of cotton twill of basis weight 350 g/m2 with 5000 stitches/min, four stitches/cm, a sewing tension of 220 cN and with sewing in the forward direction. The core yarns are obtainable by a process comprising the measures of: i) producing multifilament yarns based on polyesters having an average molecular weight corresponding to a relative solution viscosity (determined on solutions of 1 g of polyester in 100 ml of dichloroacetic acid at 25 DEG C) of at least 1.9 by melt spinning polyester with a take-off speed of at least 1500 m/min, preferably from 1900 to 3200 m/min, and subsequently drawing under conditions such that the yarn has a breaking extension of about 15% and a breaking strength which corresponds to the maximum breaking strength (ultimate tensile strength) obtainable for the yarn in question or is up to 30% below that value, and ii) sheathing this multifilament yarn with fibres of vegetable, regenerated or synthetic origin or mixtures thereof in a conventional manner in such a way that the multifilament yarn will be covered virtually completely.