Patent GB-426330-A (GB)
Title: Improvements in the production of artificial filaments, ribbons and like materials
IPC: D01F2/30
Filed: 1933-08-02
Abstract: Artificial filaments, ribbons, and like materials are obtained by downward extrusion into an evaporative atmosphere, the rate of flow of which is controlled over a part of the path of the filaments extending for a short distance from the nozzles, in which part setting of the materials is initiated, while the remaining and greater part of the path, wherein setting is completed, lies in the open air or in large chambers such that the materials are readily accessible.  The filament-forming substance may be cellulose acetate or other cellulose ester or ether.  The evaporative atmosphere is preferably heated.  Separate streams of air in the region of each nozzle or each pair of nozzles may be effected by arranging suction or injector devices adjacent each nozzle or pair of nozzles and the flow is controlled by valves, iris diaphragms, or other devices together with flow meters.  The flow of air may be in any direction with respect to the filaments. The suction or injector device may be arranged above or at the side of the nozzle or in the case of orifices arranged in ring formation, it may be at the centre.  The air may be heated by steam pipes or other devices adjacent the spinning nozzles or surrounding the supply ducts.  High air temperature leads to the production of hollow filaments, but for lustrous filaments of round cross-section the spinning solution should be hotter than the air.  Each spinning nozzle may be surrounded by a sleeve which may be adjustable along the filter-candle or pipe carrying the solution to the nozzle.  The sleeve may be telescopic and may be heated.  The temperature of the air of the spinning room may be raised.  The <PICT:0426330/IV/1> <PICT:0426330/IV/2> <PICT:0426330/IV/3> <PICT:0426330/IV/4> spinning room should be efficiently ventilate in view of the large quantities of solvent evaporating therein.  The filaments, after travelling through the air of the room, are received on bobbins, or swifts, and may be twisted by ring or cap spinners.  They may be stretched during the open air travel, if desired after the application of softening agents, and the tension may be restricted to the plastic zone.  The filaments may be caused to adhere so as to form artificial horse-hair or straw.  The spinning solution may have a high or low proportion of the cellulose ester or ether and may contain diluents, pigments, and other additions.  As shown in Fig. 1, filaments 11 extruded from jets 8, pass for a short distance through a space 9 through which evaporative medium is caused to flow at controlled velocity.  The space 9 is shielded from the surrounding atmosphere, and heated by fluid circulating in jackets 12.  Flow of air is effected by means of a central suction conduit 13 with connection to the space around the filters 7 and jets 8 by apertured diaphragms 16.  The air is provided from the open air at the bottom of the zones 9 or it may be admitted through nozzles 17 or 20.  The filaments pass from the zones 9 and travel over a long path in the open air to complete their setting and evaporation of solvent.  They may then be passed over stretching bars and rollers and collected on cap spinning devices. As shown in Fig. 2, the filters 37 are mounted in a casing 38 incorporating a duct 39 and heating jacket 40.  Around each spinning jet 41 is a hood 42 enlarged at its lower end 44.  Air is supplied at constant pressure to the conduit 39 and discharged through a diaphragm 45.  Heated air escaping from the hood 42 is carried away by means of a hood 47 connected to a suction conduit 48.  The filaments pass on through the open air and are collected, if desired after being lubricated, on a ring spinning device.  As shown in Fig. 4, the filter casing consists of a tubular member 57 of a heating unit comprising jackets 58.  The lower end of the tube 57 is closed by a cap 63 carrying the jet 64. The spinning zone comprises a hood 65 provided with heating pipes 66. A flow of air through the hood is maintained by a suction conduit 67 common to a number of hoods and connected to each by a pipe and diaphragm 69.  The filaments are given a long air path during which they are stretched by passing round rollers 70, 71 rotating at different speeds.  They may be stretched between the jet and the first roller as well as between the rollers.  They are wound on a bobbin 72.  As shown in Fig. 5, an upward current of air towards the jet is produced by a suction conduit 74.  The pipe 78 is connected to the centre of an annular jet.  A casing 81 with heating jacket 82 is provided near the jet.  Air is also supplied through a perforated ring pipe 83.