GB1042581A - Production of spun yarns - Google Patents

Abstract

In the production of bulked, staple fibre yarn, bonded fibre fabrics, woven and knitted fabrics, a travelling tow of continuous cellulose or wholly synthetic thermoplastic filaments is variably modified e.g. by continuously stretching between pairs of conical and/or cylindrical, variable-speed rollers, and/or relaxing and/or heating and cooling, or by chemical treatment, along or across selected successive portions of the tow, in such continous or discontinuous manner that the modification or a part thereof is retained as a latent property in the filaments pending further treatment. The modification is such that the filaments (or parts thereof or fibres cut therefrom into staple length and perhaps crimped) undergo a corresponding variable change of length by shrinkage or extension when subjected to a uniform length-changing treatment e.g. wet or dry heating or chemical treatment of relaxed or tensioned-filaments at the fibre or (single or plied) yarn stage. The difference in modification extends longitudinally of each filament and/or between different filaments. Individual stapled fibres may have a shrinkage characteristic which varies from a maximum at one end to a minimum at the other end. Staple derived from separately prepared tows, p the filaments of which may differ as regards chemical nature, form and/or denier, may be blended and spun into yarn. A bulky fabric comprises polyacrylinitrile fibres bonded with rubber latex and then subjected to a steam treatment to induce differential shrinkage within and/or between the fibres. In apparatus for subjecting viscose filaments to a variable liquid treatment, Fig. 3 (not shown) the tow passes through a bath 19 containing a water-soluble ethylene urea formaldehyde precondensate and a resinifying catalyst such as magnesium or ammonium chloride, thence through driven nip rollers 20 the squeeze pressure between which is varied (by mechanism comprising rotating arm 23, lever 22 and loading spring 21) so as to effect a variable expression of the bath liquid: alternatively or additionally, the resin concentration of the liquid may be varied. The tow then passes through a curing oven 24, water and finish solution baths 25 and 26 and a drier 27. Staple fibre yarn produced from the resultant filaments is immersed in a shrinking agent e.g. aqueous caustic soda solution, and the yarn thus bulked may be stabilized by cross-linkage or the application of a crease-resistant resin. In the stapling apparatus of Fig. 4 (not shown) polyacrylic tow is fed between rollers 35, 36, and 37, 38. Roller 37 is of rubber and roller 38 is surfaced with rubber, carries cutters 39 and rotates eccentrically so that each cut fibre is relaxed in a continuous variable manner from 0-20% from end to end. Steam and cooling air are directed on to the tow by jets 40 and 41. Yarn spun from this staple and heat-treated develops a structure varying from open on the outer surface to compact at the core. In another apparatus, Fig. 5 (not shown) the tow is stapled by a traversing cutter 42 trailing a steam nozzle 43:yarn spun from the staple and heat-treated shows a sharply defined transition from a compact core to a loose surface.