Patent GB-705101-A (GB)
Title: Improvements in or relating to the treatment of synthetic fibers with steam
Inventor: SCHAEFER RODGER LEWIS
IPC: D02J13/00
Filed: 1951-10-16
Abstract: <PICT:0705101/IV (a)/1> A thermoplastic synthetic fibre is treated with steam by passing it into a counter-current of steam with a linear pressure gradient to a point of substantial pressure where the steam atmosphere is heated externally, and then through a co-current of steam with a linear pressure gradient to a point where the pressure is substantially that of the external atmosphere.  The treatment may be carried out in apparatus comprising a capillary tube through which the fibre may be passed in continuous manner, a heating element surrounding the tube, and a branch conduit for introducing steam into the tube at a point intermediate of the ends of the heating element.  The fibre entering the tube at nearly atmospheric pressure is gradually heated by the steam moving in counter-current. The steam may be dried by the action of the heating element and the fibre may be dried by the steam.  The steam treatment may be used to facilitate a stretching operation, or alternatively a heat-shrinking operation.  The treatment may be effected on fibres directly after their production by a dry or wet spinning process.  As shown, the fibre 1 is passed through a capillary tube 2 provided with a side-tube 3 which is connected to a source of steam under pressure. The tube 2 is enclosed for the greater part of its length by a steam-jacket 4.  A conduit 7 is provided for the introduction of high pressure steam, and a conduit 8 is provided for withdrawal of condensate or exhaust steam.  Heat insulating material 9 surrounds the jacket.  Instead of using a steam-jacket, the capillary tube may be heated by electrical resistance coils, inductance coils, or high frequency electrostatic fields, or by hot air or hot combustion gases.  The softening or swelling of the fibre in presence of the steam may be increased by adding small proportions of solvents, e.g. in the case of fibre of a copolymer of acrylonitrile and vinyl acetate the softening or swelling assistant may be alcohol, acetone, N.N-dimethylacetamide or dioxane.  The temperature gradient within the treating tube may be regulated if desired by providing a series of steam jackets along the tube, each being supplied with steam at a different temperature and pressure.ALSO:<PICT:0705101/IV(c)/1> Apparatus for treating a continuously moving synthetic fibre with steam comprises a capillary tube through which the fibre may be passed, a heating element enclosing the tube, and a branch conduit for introducing steam into the tube at a point between the ends of the heating element.  The apparatus enables a travelling fibre to be treated with steam in such manner that it first meets a counter-current of steam under a pressure which increases in the direction of travel of the thread up to a point of substantial pressure where the steam is heated externally, and then travels through a body of steam moving in the same direction as itself under a pressure which decreases in the direction of travel to a point of substantially atmospheric pressure.  The fibre may be subjected to stretching or allowed to shrink while it is under the softening influence of the steam.  As shown the fibre 1 passes through a capillary tube 2 provided with a branch tube 3 which is connected to a source of steam under pressure.  Tube 2 is enclosed for most of its length by a steam-jacket 4.  A conduit 7 is provided for the introduction of high pressure steam, and a conduit 8 for the withdrawal of steam and condensate.  Instead of the steam-jacket, electrical resistance coils, inductance coils, high frequency electrostatic fields, hot air, or hot combustion gases may be used for heating the capillary tube.  The temperature gradient within the treating tube may be regulated if desired by providing a series of steam jackets along the tube, each being supplied with steam at a different temperature and pressure.