Patent GB-1487674-A (GB)
Title: Bulked composite elastic yarn
IPC: D02J1/00
Filed: 1975-09-04
Abstract: 1487674 Bulked composite yarn; knitting E I DU PONT DE NEMOURS & CO 4 Sept 1975 [5 Sept 1974] 36471/75 Headings D1F, D1K and D1W A composite yarn comprises one or more uncrimped elastic yarns 1 and at least 5 synthetic continuous filaments 20 of relatively inelastic material to protect the elastic yarn(s), the relaxed composite yarn being bulky, having the elastic yarn(s) straight and being capable of being extended at least 100% when stretched until the elastic yarn(s) first become load-bearing the stretched yarn having the relatively inelastic filaments 20 entangled tightly around the elastic yarn(s) 1 in intermittent zones of random braid-like structure and otherwise extending substantially parallel to the elastic yarn, there being an average entanglement spacing of less than 10 cm and the filaments 20 being substantially free of crunoidal or other surface loops when the yarn is in said stretched condition. The composite yarn is produced by continuously feeding elastic yarn 1 and continuous filaments 5 through a fluid bulker 9 in which at least one fluid jet impinges on the yarn at an angle of 90‹ Œ 45‹ to separate the filaments and entangle them around yarn 1, yarn 1 being fed under tension sufficient to extend it at least 100% over its relaxed length and filaments 20 being fed at 0 Œ 2% overfeed. Manual and automatic methods for determining the average entanglement separation are described. The elastic yarn is preferably spandex. In examples 3 and 4 two such yarns are used and parts of the filaments are caused to pass between the two spandex yarns. In examples 1 and 2 a coalesced multifilament spandex yarn is used. The elastic yarn is fed at up to 12.2 m. per second and combined with the inelastic filaments whilst stretched 400%. The filaments may be of nylon, polyester, polypropylene cellulose acetate or regenerated cellulose. They may show crimp when relaxed, due to false twisting or to the use of bicomponent filaments. The filaments may be of different types e.g. nylon and cellulose acetate, or untextured high potential shrinkage polyester and textured nylon so that on shrinkage the polyester filaments are load bearing. The bundle of filaments supplied has no more than producer's twist. The entanglement fluid is ambient temperature air. The resultant composite yarn has substantially zero unidirectional torque.  Fabrics The yarn may be used in woven fabrics, circular knit fabrics or stretch warpknit fabrics made on tricot or raschel machines, composite yarns 10, Fig. 6 may be knit on the front or back bar and nylon yarns 25 on the other bar. Loops 23 protrude from the composite yarn and partially obscure openings 26. A fine surface is achieved when the inelastic filaments are textured and a loop-pile surface when they are non-textured. When the inelastic filaments are bicomponent and thus of high shrinkage or latent crimp a more compacted nap is formed (Fig. 7 not shown). The composite yarn can be intermittently knit and laid in e.g. knit on one course and laid in on one or more courses before repeating the knit course. Yarn tension apparatus (Fig. 9, not shown) is described for estimating the delivery tension in the yarn as it is unwound from a package and delivered to knitting machine, and the residual tension in the yarn as knitting is stopped. These tensions should be less than 5 and 4 grams respectively.