Patent GB-679543-A (GB)
Title: A method and an apparatus for the continuous production of artificial fiber materials
IPC: D01D10/04
Filed: 1948-12-18
Abstract: The filaments or filament bundles produced by extrusion of viscose through adjacent spinnerets into a coagulating bath are commonly and positively drawn by successive multi-roller units through a plurality of consecutive coagulation and after-treating baths, the roller units each comprising at least three rollers and being located above the baths and between the same, and the filaments during their passage through the baths are maintained in an unsupported, freely suspended, substantially horizontal position and under positive tension and are stretched, or stretched and shrunk, by the multi-roller units during their passage through the same.  The finished filaments may be converted continuously into staple fibres if desired.  The viscose preferably contains 10-20 per cent cellulose, and the coagulating liquid is preferably fed in counter-current to the filaments.  The coagulating bath has preferably a specific gravity of 23 DEG  B<\>ae, a temperature of about 50 DEG  C. and a length of at least 100 centimetres.  The filaments may, if desired, be impregnated by passage through a suspension of rubber latex or resins if they are to be used in the production of tyre cords or belting, and in this case 2 to 3 per cent of a substance, e.g. a soluble barium salt, which forms an insoluble salt by reaction with the bath liquid may be added to the spinning solution.  The continuous filaments may also be mechanically crimped.  As shown (Fig. 1), the spinning machine comprises a table 1, transversely extending the entire operating width of the machine, inside an enclosure 2 to which access is made by openings 120 closed by slides 121.  Vapours are drawn off via the dome 122, and waste spinning solution collects in grooves formed in the table.  Candle filters 4 are mounted on the table and connect with spinnerets 6 in the coagulating baths 7-9.  The extruded filaments are received in compartments formed by movable partitions 16 (Fig. 2).  If desired, double sets of filters and spinnerets may be installed, and the partitions 16 removed to form wider troughs. The filaments pass under a guide roller 20 and to the first roller unit 21-23, the rollers of which extend through the entire operating width of the machine. The positions of the roller units are adjustable longitudinally. The first roller of each unit is rotated at a slightly greater circumferential speed relative to the last roller of the preceding unit, thus drawing the filaments through the treatment baths under positive tension.  Variation of the speeds of the other rollers will cause stretching or shrinking.  If desired the conveyer rollers may be grooved to prevent tangling of the filaments. False twisters, each comprising two staggered rods 26, 27 mounted on a beam 39 extending throughout the width of the machine may be located in the travelling path of the filaments.  The length of the first coagulating bath may be adjusted by the movable partition 115. After leaving roller unit 21-23, the filaments are led through bath 8 and withdrawn by roller unit 28-30. Roller 28 acts solely as transport means; roller 28a, co-operating with 28, removes excessive bath liquid.  Rollers 29 and 30 may be driven at varying speeds to shrink or stretch the filaments. Roller 31 co-operates with roller 30, and both may be formed with projections or teeth to produce surface irregularities on the <PICT:0679543/IV (a)/1> <PICT:0679543/IV (a)/2> <PICT:0679543/IV (a)/3> <PICT:0679543/IV (a)/4> <PICT:0679543/IV (a)/5> <PICT:0679543/IV (a)/6> <PICT:0679543/IV (a)/7> incompletely solidified filaments.  Supply tubes 34 for coagulating liquid are mounted near the rear end of the troughs, and the overflow passes into funnels 37 and thence to discharge pipes 38.  The filaments leaving the coagulation zone may be wound on to drums if desired.  In a modified arrangement a plurality of superposed racks of candle filters and coagulation baths may be provided, as in Fig. 4.  The filaments are drawn by driven rollers 48 in a dripping trough and are then combined and passed through other coagulation baths.  Desulphurising (2 per cent sodium sulphite at 60-65 DEG  C.), bleaching, impregnating, sizing, washing and other treatments may be applied to the filaments in continuous manner by provision of a series of baths, each extending transversely throughout the entire operating width of the machine.  After drying (as, for example, on heated rollers 57) the filaments may be passed through a bath of oil in a trough 66 provided with a jacketed wall 67.  They then pass through heated nip rollers 77, 78 formed with teeth or projections which impart a crimp to the filaments.  They are then cut or weakened by passing first over a spreader bar 82 and then over a knife 85 and finally drawn into staple fibre in the drawing frame 80.  The knife may be formed with two inclined edges to produce shaped cuts in the band of filaments, thus producing overlapping of the cut ends.  The roving is then passed by transport rollers 91, 91a to a twisting device such as a flyer 92.  If desired, two cutting mechanisms may be provided, arranged in vertically superposed relationship, the cutters being mounted to cut in diagonally opposed directions, and by combining the resultant rovings a yarn of staple fibres may be obtained (Fig. 10).  In this modification, the lengths of the staple fibres produced in each cutting device may be different. Also one or more bands of continuous filaments may be combined with one or more rovings of staple fibres to form a yarn. To prevent lifting of the filaments instead of cutting or weakening a presser device 124 having a bifurcated base 125 may be provided. In spinning monofils, capillary tubes may be used in place of the conventional spinnerets, the resultant monofils being transported and treated continuously in the same manner as the filament bundles.  The dried monofils are led through the teeth of a comb-like device and thence over a cutting or weakening device as shown in Fig. 12.  This comprises a fixed knife guide 104 extending throughout the width of the machine, which bears passages 105, one for each knife to be installed.  A rod 103 fits loosely into each passage and is provided with a spring 108 beneath the guide to ensure that it is pulled down until the cam 110 lifts the rod against the spring to bring the knife-blade 102 at the upper end of the rod into contact with the filament 100. p  At the lower end of the rod a spherical contact is provided. Beneath the row of rods a rotatable cylinder 109 is located, which is formed with rows of bores into which pins 113 with cam-shaped heads 110 may be screwed.  By adjustment of the pins the knife-blades may be caused to cut the filaments or weaken them, in this latter case the separation being effected by the drawing frame. The spacing of the pins governs the length of the staple formed.  By omitting certain pins a combination yarn of continuous filaments and staple fibre may be obtained.  The blades may be replaced by a heated electric wire, or a drop of liquid (e.g. water) may be squeezed into contact with the filament to weaken it.