Yarn process
United States Patent MacFarlane *Apr. 1, 1975 YARN PROCESS [56] References Cited [75] Inventor: Iain Mackay MacFarlane, Shelby, UNITED S TES ENTS 3,022,565 2/1962 Fitzgerald 57/157 5 4 3,404,525 10/1968 Tompkins 57/157 TS [731 Asslgnee&#39; a lndustr&#39;es Chdrlmte 3,435,603 l/1969 Rice 57/34 HS 3,708,970 l/l973 MacFarlane. 57/140 R =l 1 Notice; The portion of the term of this 3,733,801 5/1973 Jones 57/157 TS patent subsequent to Jan. 9, 1990. has been disclaimed. Primary E.\&#39;ammer-.lohn Petrakes 1 Flledi p 1972 Attorney, Agent, or FirmHerlbert M. Adrian, Jr. 21] Appl. No.1 290,675  
  Related US. Application Data 57 ABSTRACT [63] 32 110985 Textile denier, multifilament, false twist crimped, heat set stabilized synthetic yarn and a simultaneous draw- 52 0.5. CI. 57/157 TS 57/157 3 texturing Pmcess for Pmdw [51] Int. Cl. D02g 1/02 [58] Field of Search 57/34 HS, 34 R, 157 TS, 6 Claims, 1 Drawing Figure YARN PROCESS This is a continuation-in-part of Ser. No. 110,985 filed Jan. 29, 1971, now U.S. Pat. No. 3,708,970.  
  The present invention relates to a process to produce draw-textured, and stabilized synthetic multifilament yarns, particularly polyester and nylon yarns. The preferred polyester is polyethylene terephthalate.  
  Undrawn yarn of textile denier can be fed into a false twist zone consisting sequentially of a heater, a false twister and a draw roll, the latter operating at a speed sufficient to draw the yarn at the desired draw ratio. The false twist backs up into the heated zone to a draw neck point located therein, wherein the twist is set into the yarn. A yarn snubbing device, such as a snubbing pin, can be positioned between the yarn feeding means and the heater, in which case the yarn draws at a draw neck point located on or adjacent the snubbing device. The yarn, where desired, is then sequentially, and in a continuous manner, overfed through a heated zone and packaged.  
  Filamentation during the draw texturing process is most prone to occur between the spindle and the draw roll. This is because the highest tensions to which the yarn is subjected during draw texturing occur in that region of the operation wherein drawing tension is compounded by tension imposed by the spindle. In the usual lagged operation sequence, wherein the yarn is not being simultaneously drawn and false twist textured, the yarn is not under drawing tension. Thus, the yarn has been drawn at its optimised draw ratio, say about 3.65 for polyethylene terephthalate yarn, of spun birefringence about 5.8 X and spun I.V. about 0.63 and then separately false twist textured. However, when these conditions are combined in simultaneous draw texturing, tenacity usually drops slightly, but often filamentation of the yarn significantly increases at the conventional lagged operation twist insertion levels. Filamentation can be eliminated by significant draw ratio reduction, but with corresponding deterioration in tenacity. However, it has been quite unexpectedly found that in the simultaneous draw texturing operation, actual tension as measured along the yarn longitudinally decreases with increase in twist level which results in improved tensile properties, particularly tenacity, by enabling the use of a higher draw ratio and reduced filamentation. In fact, filamentation value without deleteriously influencing tenacity and elongation, can be decreased from about 10 to 30 at about 55 tpi; to about 0 to 0.4 at the higher twist frequency levels based on 150 to 170 denier yarn.  
  In fact, yarn filamentation decreases to where it is below that of the lagged operation yarn as determined by filamentation value, disclosed more fully hereinafter. Although not entirely understood, it is believed that higher twist translates a greater proportion of the total drawing and spindle induced tension into a force vector perpendicular or tangential to the longitudinal axis of the yarn, thereby reducing the tension component which the yarn must bear in the lengthwise direction. Thus, higher draw ratios corresponding to higher filament tensions can be employed, i.e., draw ratios approaching the optimised draw ratio of about 3.60 to 3.70 can be employed, i.e., 3.40 to 3.55. Heretofore, to avoid excessive filamentation, draw ratios in the simultaneous draw texturing process of the order of about 3.2 were believed to be about the highest useable in practice.  
  Filamentation value characterizes the yarn not only in a physical sense but is indicative of its improved performance properties, as will be apparent. This is because the characteristic relates directly to the number of times a fabric construction machine, in this case a knitting machine, will be stopped per unit length of fabric due to yarn filamentation. In other words, the theoretical and visual improvement by selection of yarn processing conditions translates into improved fabric construction efficiency.  
  Filamentation value is based. on knot free yarn and is the actual number of machine stops due to filamentation (most usually a loose filament caught underneath adjacent layers of yarn on the feed package) per 30 feeds (30 feed packages) per 10 fabric yards on a Fouquet Interlock Knitter. The knitting machine is set to 15 to 18 rotations per minute with the machine stop mechanism being set at medium sensitivity.  
 EXAMPLE An as spun 510/36 yarn oflinear fiber-formable polyethylene terephthalate (having an intrinsic viscosity of about 0.63, a birefringence of about 5.7 X 10*, polymerized from polyester monomer produced by the direct esterification of terephthalic acid with ethylene glycol, such polymer having a free glycol content of less than about 2.25 mol percent) is draw textured in a continuous operation in accordance with the following process conditions and with reference to the Drawing.  
  The undrawn yarn having a producer twist of about 0 turns per inch, is supplied from supply package 3 to the draw texturing operation. The yarn is pulled off of the supply cheese by positively controlled feed roll 5. Draw roll 7 is operated at a peripheral speed so that the yarn is drawn 3.45 times, based on feed and draw roll surface linear speeds in the drawing zone between feed roll 5 and draw roll 7. Hot plate 9, heated by internal steam generating means and 3.25 feet long, is maintained at about 230C. False twist spindle 11, being of the tube type having a centrally-located sapphire pin about which the yarn is wrapped once, is rotated by means not shown at about 370,000 rotations per minute. Yarn speed around the draw roll is about 440 feet per minute, so that about tpi (turns per inch) of twist is put into the yarn upstream of spindle 11 while the same amount of twist is taken out of the yarn downstream of the spindle, in accordance with conventional false twisting principles. The 70 tpi runs back from the spindle, along the yarn as it passes across the heater to the draw point, which is located about 2.5 inches below the top of the heater plate 9, thus setting the yarn in the twisted configuration. The draw point is precisely located without the use of external means such as a draw pin by the dynamic conditions of the draw texturing process. Because of the change in yarn denier at the draw point, tpi above the draw point is no more than about 15 to 20 and gradually dissipates as it runs back toward the feed roll 5. From the draw texturing zone, the yarn, now about /36, passes immediately and sequentially into a 3 foot long hot air chamber 13 maintained at about C at a 16 percent overfeed as measured between draw roll 7 and relax roll 17. In the re laxation zone, the drawn, crimped, torque lively yarn is stabilized for subsequent use in knit and woven fabric constructions requiring dimensional stability, stitch definition and the like properties not obtainable with stretch yarns&#34; that have not been stabilized. The yarn is then fed to package at about 7 percent underfeed to form a firm package construction suitable as a feed package for knitting and weaving processes.  
 What is claimed is:  
  1. In a process for simultaneously drawing and texturing by false twist crimping a synthetic multifilament yarn wherein undrawn or partially drawn yarn is fed into a simultaneous drawing and false twist crimping zone comprising a heated zone and false twist spindle positioned between a yarn feed means and a yarn draw means and wherein the false twist backs upstream into the heated zone and wherein the yarn necks at a draw point between the feed means and the false twist spindle, the improvement to reduce threadline tension along the longitudinal axis of the yarn between the false twist spindle and the draw means and thereby prevent or reduce filamentation caused by too high a threadline tension between said spindle and said drawing means when said yarn would be false twist crimped at the draw ratio and false twist insertion level used to conventionally flat draw said undrawn or partially drawn yarn at its optimum draw ratio and then false twist crimp said drawn yarn, which comprises reducing the draw ratio, as determined by the peripheral speeds of the feed means and draw means, to a value allowing draw, false twist crimping production of a yarn of acceptable tenacity and dyeability, and then increasing the turns per inch of false twist inserted into said yarn to reduce said threadline tension until filamentation is reduced to an acceptable level.  
  2. In a process for simultaneously drawing and texturing by false twist crimping a synthetic multifilament yarn wherein undrawn or partially drawn yarn is fed into a simultaneous drawing and false twist crimping zone comprising a heated zone and false twist spindle positioned between a yarn feed means and a yarn draw means and wherein the false twist backs upstream into the heated zone and wherein the yarn necks at a draw point between the feed means and the false twist spindle, the improvement to reduce threadline tension along the longitudinal axis of the yarn between the false twist spindle and the draw means and thereby prevent or reduce filamentation caused by too high a threadline tension between said spindle and said drawing means when said yarn would be false twist crimped at the draw ratio and false twist insertion level used to conventionally flat draw said undrawn or partially drawn yarn at its optimum draw ratio and then false twist crimp said drawn yarn, which comprises increasing the turns of false twist inserted into said yarn to reduce said threadline tension.  
  3. The process of claim 1 wherein the yarn is a polyester yarn and the yarn necks at a draw point in the heated zone without the presence of yarn snubbing means.  
  4. The process of claim 2 wherein the yarn is a polyester yarn and the yarn necks at a draw point in the heated zone without the presence of yarn snubbing means.  
  5. The method of claim 1 wherein the yarn is a polyethylene terephthalate yarn of to denier.  
  6. The process of claim 1 wherein about 60 to 80 turns per inch of false twist are inserted into the yarn while drawing the yarn about 3.40 to 3.55 times to produce a yarn having a tenacity of at least 3.0 grams per