Patent GB-460955-A (GB)
Title: Improvements in or relating to the manufacture of artificial filaments, yarns and similar materials
IPC: D01D5/04
Filed: 1936-09-12
Abstract: <PICT:0460955/IV/1> <PICT:0460955/IV/2> The process described in the parent Specification is modified by continuously passing through a system comprising a pump and a mixing or homogenizing device and thence towards the spinning jets a substantial excess of the spinning solution and pigment mixture over that required by the spinning jets, and continuously returning the excess of spinning solution and pigment mixture to the feed side of the system.  The spinning mixture may be pumped to one end of a header supplying a plurality of spinning jets and the excess may be continuously returned from the other end of the header.  The process is applicable to the manufacture of viscose, cuprammonium, nitrocellulose, cellulose acetate, formate, propionate, butyrate, ethyl cellulose, methyl, or benzyl cellulose filaments.  The filaments may be produced by dry or wet spinning methods and may be fine filaments, or bristles, artificial straw, or horsehair.  For subdued lustre or opacity there may be used white pigments such as tin oxide, oxide of aluminium, silicon, zinc, titanium, or antimony, sulphate of barium, calcium, or lead, tin phosphate, zinc carbonate, barium or calcium borate, silicates such as clays, talc, or mica, diacetyl benzidine or toluidine, dibenzoyl benzidine, naphthyl urea, synthetic or natural resins. For coloured products, ochre, sienna, chrome yellow, tin bronze, venetian red, red lead, vermillion, ultramarine, Prussian blue, milori blue, Guignet's green, verdigris, chrome green, raw umber, burnt umber, and vandyke brown may be used.  Lakes containing alumina or tungstic acid and lampblack or graphite may be added. For metallic effects, finely divided or colloidal metals may be used. The pigment may be added to the spinning solution as a concentrated suspension in a solution of a compound similar to or compatible with the base of the spinning solution.  It may be milled, or kneaded with a viscous solution of a cellulosic compound containing a plasticizer and a volatile solvent, the latter being allowed to evaporate during mixing.  The plastic material may be broken into chips or powdered. The chips or powder may be treated with a solvent and the suspension incorporated with the spinning solution.  As shown in Fig. 1, spinning solution from a main feed pipe 1 passes through a homogenizer 3, pipe 5 and pump 6 to a header 7 and thence through pipes 8 to a plurality of spinning jets.  The pigment suspension is supplied from a reservoir to pipe 11, pump 12, pipe 14, and the feed pipe 1.  The discharge side of the pump 6 is connected by pipe 26 to the feed pipe 1.  The homogenizer 3 has spaced baffle plates 4 each provided with a number of holes, those of one plate differing in size from those of adjacent plates.  Pump 6 is regulated to supply substantially more solution than that required by the jets.  It may supply five or more times the required quantity so that 80 per cent or more of the material passing the pumps is re-circulated.  As shown in Fig. 2, spinning solution passes from pipe 1 through pump 28 to the homogenizer 3.  Pigment suspension is supplied from pipe 11 through pump 12 to pipe 1. The mixture of solution and pigment passes through pipe 33 and pump 32 to one end of the header 7 and thence through pipes 8 to the jets.  The excess of mixture supplied by pump 32 returns from the other end of the header 7 by pipe 35 to the homogenizer.