Patent GB-1377657-A (GB)
Title: Process for producing crimped fibres by continuous wet heat setting and apparatus therefor
IPC: D02G1/12
Filed: 1971-11-24
Abstract: 1377657 Stuffer crimped fibres; steam treatment POLYMER PROCESSING RESEARCH INSTITUTE Ltd 24 Nov 1971 [25 Nov 1970] 54674/71 Headings D1F and D1L In a process for producing stuffer-box crimped fibres, the fibre material, which may be tow, filament yarns or slivers, on leaving a stuffer-box crimper 5 is wrapped with at least one cloth belt 7 while maintaining the height and width of the material substantially the same as the height and width of the material as it leaves the crimper, the wrapped material is fed to a pressure-sealed zone 15 containing pressurised saturated steam and is guided in a straight line through the zone 15 while maintaining its width constant, the wrapped material is removed from the zone 15 while maintaining constant width, and the fibre material is taken up at a speed sufficient to straighten the folds in the material and simultaneously, the cloth belt is peeled off and returned to the inlet side for reuse. In the preferred process, the fibre material I is fed through a pre-treatment steam chamber 2 and then via nip rolls 4, 4' to a stuffer-box crimper 5. The fibre material may be wrapped at the exit of the crimper 5, but it is preferred that a guide conduit 6, of rectangular section substantially the same as the crimper, is attached to the crimper, the cloth belt 7 being guided round the conduit 6 to wrap the material as it leaves the conduit. The wrapped material is then fed through nip rolls 9, 9', having width retaining plates 10, which rolls feed the material into the inlet pressure-sealing means 12. The sealing means 12 includes a rectangular section conduit 11 for maintaining the width of the wrapped material constant, the upper wall 13 of the conduit being movable to vary the pressure on the material. The pressure-sealing means 12 is maintained at a pressure lower than that prevailing in the pressurised saturated steam zone 15. The wrapped material is passed into the zone 15 and is guided therethrough in a rectangular section conduit 16 which is permeable to steam. The downstream end of the conduit is preferably provided with a movable upper wall 19 or, the downstream end of the conduit may be reduced in height whereby pressure is exerted on the material to produce acute crimps in the material. The wrapped material leaves the zone 15 and passes through an outlet pressuresealing means 12 of the same construction as the inlet sealing means 12. The wrapped material is withdrawn from the sealing means 12 by nip rolls 23, 23' having side plates 24 to maintain the width of the wrapped material constant. The fibre material is withdrawn by nip rolls 25, 25' which straighten the bends in the material and the cloth belt is peeled off and returned via ironing cylinders 28, 28' to the inlet for reuse. The fibre material is takenup on a beam 30. In the case of filament yarns or slivers, the individual yarns or slivers are separated by a comb 31 before being taken up on the beam. To facilitate such separation, the yarns or slivers may be dusted with talc powder prior to crimping. The fibre material may also be padded with dyestuff prior to crimping. The crimp may be developed by heat treatment before or after the fibre material is made up into cloth. In the process of the invention, the inlet and outlet pressure-sealing means may comprise pairs of nip rolls which have their peripheries sealed with elastomeric material. In an alternative arrangement, the downstream end of the conduit within the pressurised saturated steam zone 15 may be replaced by pairs of nip rolls. Various forms of construction for the conduits within the sealing means 12 and pressure zone 15 are given. In the apparatus according to the invention, a further open-top conduit with a movable upper cover is positioned downstream of the wrapping means and upstream of the feed rollers 9, 9'. Such further guide conduits may also be positioned adjacent the inlet to the first sealing means 12 and adjacent the outlet of the outlet sealing means 12. The pressure-sealing means may comprise a flat, thin-walled tube, with upper and lower pinch plates to vary the section of the tube and packing material in the form of elongate parallel fibres in the tube along its sides. In an alternative embodiment the pressure-sealing means is in the form of a gate-valve, or comprises upper and lower pinch rolls and hermetic sealing wallssurrounding the outside of the rolls.