GB905247A - Method and apparatus for treating filament yarn to impart potential crimp thereto - Google Patents

Abstract

Potential crimp is imparted to "molecularly <PICT:0905247/IV(a)/1> <PICT:0905247/IV(a)/2> orientable", i.e. undrawn, synthetic, continuous mono- or multi-filament yarn made from a thermoplastic polymer by passing the yarn through a zone wherein the temperature of the yarn is elevated and the yarn is stretched to a predetermined extent thereby to increase the orientation thereof, most of the stretching being concentrated in the area where the yarn temperature is elevated, and thereafter continuously deforming the heated and stretched yarn into a corrugated shape simultaneously with cooling thereof by continuously passing the yarn between interengaging toothed wheels. Crimp and resultant bulk/stretch properties are developed and set by subjecting the drawn and deformed yarn (or fabric comprising such yarn) to a final heat treatment in a hot aqueous medium such as steam or by dry heat or a combination of both in relaxed condition. Irregular or regular variations in yarn speeds and stretch ratios may be used to impart corresponding effects in the yarn. The yarn may be twisted or untwisted, or compositely formed of yarns having different composition and denier, the undrawn yarn may be treated together with drawn yarn or with a yarn of non-thermoplastic material such as regenerated cellulose, and/or the yarn or constituent filaments thereof may be of circular or non-circular, e.g. X- or Y-shaped, cross-section and/or tubular. The thermoplastic polymer may be a polyamide, polyester, polyacrylonitrile, polyethylene, polypropylene, polyurethane, copolymer of vinyl acetate and vinyl chloride or vinylidene chloride or acrylonitrile and a minor proportion of at least one mono-olefinic compound or vinyl chloride and acrylonitrile, or blend or mixture thereof, and is formed into yarn by melt extrusion or wet or dry spinning processes. As shown in Fig. 1, nylon yarn 10 passes from a package 11, as doffed from a spinning machine, around a snubbing bar 13, through a guide 14 and advancing nip rolls 15, several turns around a heated draw pin 16, where most stretching occurs, between, and one or more helical turns around, gear-driven, meshing, toothed corrugating wheels 17 and 18 (one or both of which may be uniformly tapered) and separator roller (or bar) 25 axially inclined thereto, thence through guide 26 to be taken up as a bobbin 28 on a ring twisting assembly 27. The pin 16 is of stainless or chromium-plated steel or bonded ceramic or alumina, which may be flame-plated with sintered tungsten carbide, and is heated by an internal, removable electric heating element, Fig. 2 (not shown) high frequency heating or a heated fluid therewithin. In the operation of the complete yarn treating apparatus shown in Fig. 5, unoriented yarn 10, withdrawn from package 11 and passing around pin 13 and through guide 14, is led through the nip between a floating spring-loaded, rubbercovered idler roller 46 and driven roller 48, around the latter and idler roller 47, thence over and in contact with an electrically heated plate 49 and through and around wheels 17, 18, and separator 25. Drawn, deformed yarn falls on to an endless driven belt 53, or is deposited thereon in a zig-zag pattern by means of a traverse piddler (not shown) and is carried through a cabinet 54 housing radiant heating lamps 55 thereby developing the crimp in the yarn which passes through a traverse guide 56 and is wound into a package 60.