GB1295733A - - Google Patents

Abstract

1295733 Heat-setting crimped tow POLYMER PROCESSING RESEARCH INSTITUTE Ltd 4 June 1970 [4 June 1969 7 June 1969] 27056/70 Heading D1F A method of heat-setting crimps in artificial fibres gathered into a tow and mechanically crimped comprises enveloping the crimped tow in a wrapping whilst feeding the tow and wrapping longitudinally, the tow being fed at a higher rate than the wrapping, increasing the density of the crimped tow in the wrapping by mechanical compression, and passing the wrapped tow longitudinally through a pressurized zone containing saturated steam at the annealing temperature of the fibre, the wrapping being guided over surfaces in the zone under tension so as to apply lateral pressure to the tow. In a preferred embodiment, a tow 1 of filaments, fibres or yarns, is passed vertically through a steam chamber 4 and then passed via guide rollers 6, 7, 8 to a stuffer-box crimper 10, an adjustable pressure being applied to the bottom wall of the crimper 10. The crimped tow 11 is then passed into a temporary storage container 12 from which it is overfed to a conduit 14. A wrapping 15, which may be a woven or knitted fabric is applied under tension around the crimped tow 11 at the entrance to the conduit 14, the wrapping being such that it extends one and a half times round the tow. The conduit 14 has a cross-section which decreases in area whereby the wrapped tow is compressed as it passes through the conduit. The compressed wrapped tow 19 is then passed via pressure seals 21 into a steam chamber 23 where it is fed several times round spaced rollers 24, 25, the axes of which are slightly skewed. The heat treated tow is drawn out of the steam chamber and the wrapping is removed for reuse after ironing. In a further embodiment, the wrapped tow follows a zigzag course about a vertical series of rollers in the steam chamber. The filaments of the tow may be temporarily straightened and cut to staple length. The fibres exhibit an enhanced permanence of crimp. Various examples of the annealing temperature ranges for certain synthetic polymers and artificial fibres are listed.