GB1419921A - Method for treating with liquid ammonia fabrics made of yarns - Google Patents

Abstract

1419921 Open-end spinning; mercerising fabrics, CLUETT PEABODY & CO INC 12 March 1974 [31 Aug 1973] 10946/74 Addition to 1365706 Headings DID and D1P Yarns obtained by open-end spinning of cellulose fibres are formed into a fabric (e.g. a woven or knitted fabric) and the fabric is mercerised by impregnation of the continuously moving fabric with liquid ammonia followed by its rapid removal to give a reaction time of 0.6 to 9 seconds. Open-end spinning. Fibres deposited upon a delivery cylinder 11 of a carding engine are removed by suction device 12 and conveyed through duct 13 into nozzle shaped spinner 14. A ball 17 may be present in upper rotating chamber 18. The centrifugal force acting upon the ball presses the fibres against the chamber wall so that they rotate with the chamber. The lower chamber 19 of the spinner rotates either in the same direction as 18 but at a lower speed or rotates in the opposite direction. Thus having started by drawing a thread up through 19 to the upper edge of chamber 18 the fibres are spun into a thread which is twisted at a rate equal to the difference in rotational speeds between 18 and 19. A passage 21 for the thread has a lateral outlet opening 22 running obliquely to the axis of rotation. This ensures that the thread rotates with chamber 19. An electromagnetically operated rotary valve 23 is provided to cut off the fibre supply. Impregnating fabrics; mercerising. A fabric web 28 formed from open-end spun cellulosic yarn is fed through inlet seal 37, bath 41 of liquid ammonia and the nip of padder rollers 33, over tension controller 34, around delay means 35 then pressed against heated drying drum 77 by endless blanket 76 and finally exits via seal 63. The seals 37, 63 comprise resilient members 64, stationary members 65 and evacuation ducts 66, 67. A float 42 controls valve 46 to maintain the liquid ammonia level. The time between impregnation of the web with liquid ammonia and the commencement of its removal by the dryer, 0.6 to 9 seconds, is controlled by the speed of the web and by its travelling distance between bath 41 and drum 77. The distance is varied by the movement of rollers 73, 74. Small automatic movements of rollers 73, 74 also maintain a constant tension in the web 28, its pressure on roller 69 being used to control a motor (M, Fig. 3, not shown) which rotates screw threaded shafts (83) to move supports (82) for rollers 73, 74, The ammonia vapour/air mixture in the chamber 29 comprises over 90% by volume of ammonia. A spray may replace the ammonia bath. The brief ammonia treatment causes the fibres to swell radially and avoids significant subsequent shrinkage. The strength, extensibility and affinity to dyes, flame retardants and resins is improved as is resistance to abrasion, shrinking and wrinkling.