GB1258905A - - Google Patents

Abstract

1,258,905. Spinning and finishing yarns. IMPERIAL CHEMICAL INDUSTRIES Ltd. 5 March, 1969 [27 March, 1968; 26 Aug., 1968 (3)], Nos. 14764/68; 40616/68; 40617/68 and 40618/68. Headings D1F and D1W. Composite yarn comprises a core component 1 of stretch i.e. set false-twisted, synthetic continuous filaments and at least one wrapping component 3 of synthetic continuous filaments 5 formed around the core in helices the direction of which reverses, as at 7, 9, and 11, 13, at intervals along the yarn the covering provided thereby being a uniform, integrated filamentary body. Yarn is "high order" or "low order" according to whether the helical wrapping is applied continuously, Fig. 1, or intermittently, Fig. 2. At least 95% by number of the intervals between reversals are of length (l) less than 2cm. and at least 50% thereof may be less than 0.5cm. The continuous filaments e.g. of nylon or polyethylene terephthalate, for core and/or wrapping may be chemically, physically and/or aesthetically similar or different e.g. as regards birefringence, "natural draw ratio", cross-sectional shape (circular or trilobal), and/or may be bifilar or conjugate in sheath-core or side-by-side arrangement. In the manufacture of the yarn the at least two components are supplied to, in sequence, a feed means, a heating zone, a false-twisting element, and are withdrawn therefrom under a higher tension than that under which they are supplied, the components differing as to their extensibility under the stresses on entering the yarn section of increasing twist gradient i.e. the heating zone. The components may be, differently drawn i.e. undrawn, partly or fully drawn, and the withdrawing tension may be sufficient to effect drawing of the yarn in such section, and/or enter the section at different speeds, and/or have been differently heat treated e.g. at different temperatures. Yarn torque may be balanced by doubling core yarns of opposite torques or the torque in a single core yarn may be suppressed by heat treatment. As shown, undrawn yarns 15 and 17 of different birefringence values are merged at a guide 19 as they are withdrawn from packages 16 and 18 by a feed roll assembly 21 whence they enter a section of increasing twist gradient, passing to a false-twisting and drawing stage comprising heater plate 27 (whereon yarn twist reaches a maximum) friction twisting tube 29 and draw roll assembly 31. In the section upstream of tube 29, the component of greater extensibility forms a unidirectional helix around the other component, and it is stated that, downstream of tube 29, the core yarn has a set false-twisted core and a wrapping component of alternating helix direction. The core yarn passes to a heater plate 37, thence to a relax roll assembly 39, on to wind-up (not shown).