GB368738A - Improvements in or relating to artificial textile materials and to the production thereof - Google Patents

Abstract

<PICT:0368738/IV/1> <PICT:0368738/IV/2> <PICT:0368738/IV/3> <PICT:0368738/IV/4> The process of the parent Specification is modified by passing the plastic artificial filaments under tension over a curved surface so as to obtain a unitary product of flattened cross section. The curved surface is preferably of relatively small radius and may be one or more wires, rods, or bars of round or oval cross section, or bars having a rounded edge. The filaments may be passed round one or more of such devices. They may be treated continuously with their production by wet or dry methods, and while proceeding to a twisting, winding, or other collecting device, or may be treated subsequently to production during a bobbin to bobbin or other twisting or winding operation. Before passing over the curved surface they may be treated with a solvent or softening liquid or vapour to render them soft or tacky. The liquid may be applied by spraying, or by immersing the filaments or by bringing them into contact with moistened rollers, rods, or wicks. Residual solvent in freshly produced filaments may render further softening unnecessary. Substances may be added to the spinning solution to prolong the period during which the filaments are plastic. In the case of thermoplastic filaments the wires or bars employed for flattening may be heated to render the filaments sticky. Residual stickiness in the product may be removed by treatment with lubricants. Tension may be imparted by braking the bobbin from which the filaments are taken, or by the use of a gate tension device, or differential rollers. Softening of the filaments may take place between each pair of curved surfaces where several are employed. The flattening may be assisted by the use of rollers, weights, or spring-pressed weights. The product may be passed through further pressing means such as rolls with or without further softening. The width of the product may be caused to vary by varying the softness of the filaments, the number and diameter of the curved surfaces, the arcs of contact, and the tension on the filaments. The sticky filaments may be passed in zig-zag fashion between a number of parallel rods, alternated rods being connected together. By adjusting the relative positions of each set of rods, the arcs of contact with the filaments and also the number of rods acting on the filament can be varied. The process is applicable to filaments of cellulose formate, acetate, propionate, butyrate, or nitrate, or of methyl, ethyl, or oxyalkyl ethers of cellulose, and also to other types of artificial silk. Solvents for use with organic cellulose derivatives are acetone, acetone and water, ethylene chloride and ethyl or methyl alcohol, dichlorethylene and ethyl or methyl alcohol, vinyl acetate, diacetin, triacetin, ethyl lactate, diacetone alcohol, dibutyl tartrate, tricresyl phosphate. Dyes, metallic or other coloured powder may be mixed with the solvent or softener which is applied to the filaments. Striped effects may be produced by uniting coloured filaments. Regenerated cellulose filaments may be associated with filaments of cellulose acetate to give a product capable of being cross-dyed. Thin metal wires or ribbons such as tinsel may be incorporated in the flattened product. The products are suitable for use in millinery and for electric insulation. As shown in Fig. 1 a number of threads 11 are withdrawn from the braked bobbins 12 and passed through a reed or die 15 and then to a moistening device 17 from which they emerge in a sticky condition. They are then passed over the curved edges of the bars 18, 19 in a state of tension whereby they are coalesced to a flattened unitary product. After traversing an air path sufficiently long for evaporation of solvent, the product is passed round drawing roller 21 and collected on a frictionally driven bobbin 26. As shown in Fig. 4, bundles of filaments 34 proceeding from a dry spinning cell 31 are passed round a roller 35 and through a die 15 which collects them into a single thread 16. Other threads or wires may be withdrawn from a bobbin 48 and associated with the thread 16. The associated filaments are rendered sticky by means of the device 17 and are passed in zig-zag fashion over a number of parallel rods 37, 38. The coalesced and flattened product is passed to a collecting spool 46. The flattening device may comprise three fixed rods 61, Fig. 6, mounted on a common member 62 to which are pivoted two curved rods 64, 65 which are raised and lowered by a rotating cam 66. The rods 64, 65 are at different levels so that rod 64 comes into operation first. A product of irregular width is thus produced and, if desired, lengths of unitary product may alternate with lengths of separate filaments. In the form shown in Fig. 7 for obtaining a flattened product of any desired constant width, the curved bars 64, 65 are at the same level and are adjusted with respect to the fixed bars 61 by means of a handle 71 and wing nut 72. Specification 366,585 is referred to.