Patent GB-477428-A (GB)
Title: A process for the production of crimped artificial textile fibres and like materials
IPC: D02G1/14
Filed: 1936-10-13
Abstract: <PICT:0477428/IV/1> <PICT:0477428/IV/2> Artificial textile fibres, films, or like materials are subjected before complete coagulation to a crimping operation, during which they are stretched beyond their limit of elasticity and the micelles are permanently orientated in conformity with the crimp, and coagulation is then allowed or caused to proceed to completion.  Alternatively, finished fibres are subjected to a softening process, then simultaneously crimped and stretched, and then re-set.  Completion of coagulation, after the crimping operation, is preferably carried out in the absence of tension. For carrying out the process there may be used toothed crimping rollers constructed so that they hold the thread bundle, before it reaches the deeper gripping positions, so firmly in the undulatory position between the less deeply engaging teeth, that the thread is stretched while being crimped.  As shown in Fig. 1, the spaces between the teeth of the rollers 1, 2, are wider than the teeth 3, 4, and cannot be filled by the teeth as in normal gearing. The roller profiles intermesh so that on disengagement of the teeth the distance at any point is not substantially less than the minimum distance of the teeth at the point of greatest depth of engagement. The rollers may be heated.  Periodically meshing plates or discs may be used instead of toothed rollers, provided that they effect stretching during the crimping.  When a pair of rollers are used, one may be driven by a pair of belts passing through the gap between the rollers, and the second roller may be driven by the first through a series of toothed wheels.  A false twist may be imparted to the fibre bundle before its passage between the crimping rollers.  As shown in Fig. 5, the threads 16 are passed through the annular space between two oppositely rotating conical surfaces 30, 31.  As shown in Fig. 6, the threads 16 pass between two belts 39, 40 moving in opposite directions where they contact with the threads.  The arm 42 is periodically lifted against the pull of spring 43 by a cam 45 so that at each lift the twist can uncoil.  Crimping is carried out preferably at an optimum point of coagulation of the thread, the distance of which from the nozzles may be adjusted if necessary by altering the strength of the precipitating bath, or by using a two bath process, e.g. a solution of ammonium sulphate followed by a solution of acid.  Unmatured viscose may be used for forming the spinning solution.  Urea-formaldehyde or other artificial resins may be added to the solutions.  When only one crimping device for a plurality of spinning points is used, spinning baths graduated as regards temperature and concentration may be used so that each thread bundle reaches the optimum condition on arriving at the crimping device.  The crimped threads may be heated and then passed through an acid conversion bath.  As shown in Fig. 4, the crimped threads 16 are passed through compression rollers 28 and laterally spread out in the bath 29 by the non-circular motion of the elliptical rollers 26, 27. The crimped threads are preferably cut immediately after crimping under as little tension as possible.  Wrapping of the threads round the crimping rollers may be prevented by providing a pair of rapidly rotating smooth rollers beneath the crimping rollers, the threads normally passing freely through the smooth rollers, but contacting with one of them whenever there is a tendency to adhere to the crimping rollers.  Mixtures or pre-condensates of synthetic resin forming substances such as urea, formaldehyde, phenol, vinyl and styrol derivatives may be added to the spinning solutions.  Double resins obtained by adding further quantities of aldehydes and urea to dissolved phenolform-aldehyde condensates, and subjecting to further condensation may be used.  If desired, the crimped threads may be treated with synthetic resin components or pre-condensates. The process is applicable to cellulose or cellulose derivative threads, fibres, bands, films, and hair, made by dry or wet spinning methods. Examples describe the production of resinous condensation products for addition to the spinning solutions. Phenol and paraformaldehyde with ammonia are heated under reflux at reduced pressure.  A mixture of paraformaldehyde, urea, and acetic acid or ammonia is added to the pre-condensate, and the mixture is heated under reduced pressure.  In another example, phenol, water, ammonia, and formaldehyde are heated together to the A stage of condensation.  The product is dissolved in alcohol and glycerine.  Phthalic acid is added.  Further condensation is effected by heating with paraformaldehyde, urea, ammonium chloride, and water.  The solution is diluted with alcohol.  The condensation products are added to spinning solutions, and are hardened in the threads produced by the action of the precipitating liquid.  In another example, the finished crimped threads are treated with a solution of urea, paraformaldehyde, acetic acid, and water, condensation being effected by heating under reduced pressure.  The threads are then dried at raised temperature or treated with dilute acid to effect hardening of the resin.