Patent GB-689742-A (GB)
Title: Improvements in or relating to the production of synthetic fibres from polymers and copolymers of acrylonitrile
IPC: D01F6/18
Filed: 1949-11-02
Abstract: <PICT:0689742/IV (a)/1> <PICT:0689742/IV (a)/2> <PICT:0689742/IV (a)/3> A solution of an acrylonitrile polymer or copolymer is extruded into an aqueous coagulating bath which is at a temperature not exceeding +10 DEG  C., preferably within the range of - 15 DEG C. to +5 DEG  C.; the filaments so formed are stretched while in the gel state and in the presence of moisture at 70-110 DEG  C.; a liquid composition containing an antistatic agent is applied to the stretched filaments and these are dried in a continuous manner while they are moving in a helical path.  As solvent for the acrylonitrile polymer there may be used a concentrated aqueous solution of a salt, e.g. zinc chloride, cadmium bromide, sodium thiocyanate, calcium perchlorate, or calcium nitrate, or a concentrated aqueous solution of guanidine thiocyanate or an alkyl-substituted guanidine thiocyanate.  As shown in Fig. 1, the acrylonitrile polymer solution is extruded through a spinneret 14 into bath 24.  The spinneret may be heated electrically or otherwise.  The temperature of the bath is kept at 10 DEG  C. or lower by cooling means.  The coagulated filaments are washed substantially free from salt by the coagulating liquid. Preferably an extended travel through the liquid is effected by means of rollers 32, 34, 36.  The filaments then travel to a stretching device which comprises rollers 38, 44, and a trough 42 through which hot water is caused to flow.  The trough 42 may be constructed as described in Specification 689,770.  The arrangement of the trough is such that the filaments do not come into contact with any solid part of the device during their travel between rollers 38 and 44.  The filaments pass to bobbin 50.  As shown in Fig. 2, bobbin 50 is subsequently immersed in a trough 74 containing a liquid preparation for rendering the filaments antistatic and the filaments are unwound and passed in helical turns over mutually inclined drying rollers 86, 88, and thence to a winding and twisting device.  If desired the apparatus may be arranged so that the filaments pass continuously from the stretching device to the device for impregnating them with an antistatic preparation, then to the drying rollers, and finally to the winding device.  If desired, the antistatic substance may be incorporated in the hot water used in the stretching treatment.  As shown in Fig. 8, the filaments 26 pass from roll 36 to godet 102 and auxiliary roll 104 and are carried down into a hot aqueous medium 40 in vessel 106.  They pass from roller 108 to the cylindrical rollers 110 and 112 about which they are wrapped in helical fashion.  The filaments are stretched between rolls 102 and 110.  Sections 118 and 120 of the cylindrical rollers are unheated and they are separated from the heated sections 122, 124, by insulating sections 114, 116.  Liquid containing an antistatic agent is sprayed on to the filaments from jets 126.  The filaments are dried while passing along sections 122, 124, and they are finally passed to the winding device 146.  The acrylonitrile polymer used may have a molecular weight of 35,000-300,000.  In an example, a solution of polyacrylonitrile in calcium thiocyanate solution is extruded into a coagulating bath consisting of water, cooled to 1-2 DEG  C.  The filaments obtained are passed back and forth between rollers submerged in the coagulating bath.  After this extended travel in the bath, the filaments are led out of the bath to stretching rollers between which they travel through a trough containing water at 98 DEG C.  The filaments are stretched 600 per cent and then led to a take-up bobbin.  The bobbin of wet-gel yarn is then suspended in a trough containing an aqueous dispersion of 1 per cent of guanidine octadecyl hydrogen sulphate and 0.5 per cent of butyl stearate at 40-50 DEG  C.  The yarn is passed in helical turns over a pair of electrically - heated drying - rollers.  Specifications 594,999 and 689,744 are referred to.ALSO:Acrylonitrile polymer yarns are treated with an anti-static preparation which may be an aqueous solution or dispersion of a guanylurea or guanidine salt of an aliphatic ester of sulphuric acid, e.g. guanidine octadecyl hydrogen sulphate, or which may be an aqueous solution or dispersion of octadecoxy propionitrile or an octadecyl guanamine reaction product with ethylene oxide. Mineral, vegetable, or animal oils, or other textile lubricants or wetting agents may be incorporated in the anti-static preparation. The treatment is applied to the yarn while the component filaments are still in the wet-gel state following their production by a wet-spinning process (see Group IV (a)). Specifications 594,999 and 689,744, [Group IV (a)], are referred to.