Patent GB-1452354-A (GB)
Title: Multifilament yarns
Inventor: FRANKFORT HANS RUDOLF EDWARD
IPC: D02G1/00
Filed: 1974-05-23
Abstract: 1452354 Crimping filaments E I DU PONT DE NEMOURS & CO 23 May 1974 23154/74 Headings D1F and D1W Latent crimp due to asymmetric shrinkage is introduced into fialements spun from a polyester, e.g. polyethylene terephthalate, by drawing the filaments to the break elongation and boil-off shrinkage desired and then passing them, at a speed of at least 900 yards per min, i.e. 822 m per min, over a crimping or texturing surface 17 which is unheated other than by contact with the filaments and a second crimp is introduced by passing the filaments into a jetted stream of compressible fluid heated to a temperature which plasticizes the filaments without causing fusion therebetween and which impinges the filaments onto a moving foraminous surface. The filaments are drawn to provide a break elongation of 15-40%, preferably 25- 35%, and a boil-off shrinkage of 5-25%, preferalbly 8-16%. Boil-off shrinkage is measured by comparing fialament length before and after 30 minutes exposure in boiling water. Tihe filaments pass over the texturing surface at a speed within the range 1000-4500 yards per minute, i.e. 915-4116 m. per min. The surface is provided by a ceramic, glass or metal pin. The jetted stream of compressible fluid has a pressure of 15 to 150 pounds per square inch, i.e. 1.05 to 10.5 kg. per sq. cm., gauge and a temperature of 150-500‹C. The foraminous surface is a screen moving at 2-300 yards per minute, i.e. 1.8 to 274 metres per min. In one embodiment, Fig. 1, filaments 10 are melt-spun from a spinneret 11, passed around feed rolls 12, through a steam draw jet 13, over a finish-applying roll 14 and around draw rolls 15 onto which they are guided by a traversing mechanism 16. The filaments pass around an unheated texturing pin 17 with a change of direction #, are tensioned by pulling rolls 18 and pass-over a post-draw finish roll 19 to a wind-up 20. The second crimp is introduced by feeding yarn 21, Fig. 2, from a package 22 over ring guides 23, through a pigtail guide 24, over feed rolls 25 in a hot chest 26 and through a jet device 27 to propel the yarn onto a screen surface of a rotating drum 28. The yarn remains on the drum until it reaches a point 29 and passes over rolls 30, 31 and through a pig-tail guide 32 to a wind-up 33. The device 27, Fig. 9, comprises a passage 12 opening into an expanding treatment chamber 14 via a throat portion 13. Fluid conduits 7, 8 intersect the passage 12 at an angle of 30‹. In another embodiment, Fig. 3, filaments are spun and drawn as in Fig. 1 and pass from the draw rolls 15 about an unheated texturing pin 40 with a change of direction #, and are tensioned by pulling rolls 41. From the rolls 41, the filaments pass through a heating jet 42 and through a bulking jet 43 supplied with heated compressed fluid to propel the filaments against a screen-surfaced drum 44 which may be connected to a suction source to remove the fluid. The filaments are removed from the drum at a point 45 and pass over pulling rolls 46 to a finish-applying roll 47 and then to a suitable windup 48. Various polyesters are specified. The textured yarn produced comprises polyethylene terephthalate Filaments of 1 to 6 denier and having a random, three-dimensional curvilinear crimp with randomly varying crampconfiguration along different filaments, a frictionally-modified minor portion which is distinguishable from the remainder of the filament cross-section by a difference in refractive index, the minor portion being substantially continuous along the filament length such that less than 5 per cent of the filament length is occupied by discontinuities longer than 2 millimetres, being generally located on the outer radius of the crimp configuration, and being marked by closely spaced, parallel ripples that extend transversely to the filament length; and in the multifilament yarn, as measured under a 0.5 milligram per denier load after a 5 minute heat treatment in air at 120‹C, an average crimp frequency per 2.54 cm. of extended filament of 30 to 70 and a crimp development of 10 to 45 per cent.