Patent GB-548794-A (GB)
Title: Process for improving the tensile strength of yarns, threads, cords and the like
IPC: D06M15/39
Filed: 1940-11-04
Abstract: 548,794. Finishing yarns and threads. POTTS, H. E. (Copeman Laboratories Co.) Nov. 4, 1940. Nos. 16055 and 16203. [Class 120 (iii)] [Also in Groups IV, III, VIII and XXV] The tensile strength of yarns, threads, or the like, is increased by stretching them to just below the breaking point, so as to place the individual elements making up each yarn under substantially uniform tension, and permanently setting the yarns in this position by means of a water-insoluble resinous bonding agent which is applied in the form of a thin solution or dispersion, preferably an aqueous dispersion of a solution of a natural or artificial resin in an organic solvent. As shown in Fig. 1, a thread 2 e.g. a shoe thread is drawn through a tank containing a solution or dispersion of resin. It passes round submerged roller 5 and then through pairs of squeeze rolls 6, 7 which facilitate penetration of the liquid. Surplus liquid is removed by squeeze rolls 8. A roller 9 is driven at a higher peripheral speed than roller 5 in order to tension the thread and positively stretch it. The thread passes through a heating zone 10 and then through a cooling zone 12 in order to set and harden the resinous binder. As shown in Fig. 2, the thread passes through two baths 14, 15, of resinous bonding material. The winding roller 17 is rotated at a greater peripheral speed than the squeeze rolls 16 in order to stretch the thread. The tension is nearly as high as the breaking tension. It may be maintained at a constant value by passing the thread round the suspended and weighted roller 20. If desired several threads may be treated in the same apparatus and separate weighted rollers 20 may be used for each thread or one roller may serve for several threads. The thread passes through a heating zone 21 and cooling zone 22. The yarns or threads may be twisted during the stretching operation. The yarn or thread may be made of animal or vegetable fibres e.g. cotton or wool. The treatment sets the twist as well as improving the tensile strength and wear resistance. In an example, liquid ester gum is mixed with linseed oil which has been polymerised by a heat treatment and then oleic acid is added. The mixture sets on cooling. This is dissolved in benzine and carbon tetrachloride. The solution is added slowly and with stirring to water containing ammonia. A white emulsion is obtained and this may be used as the bonding composition for the stretched yarns or the like. In another example, a solution of gum shellac in alcohol containing castor oil is vigourously stirred into water to produce an emulsion. A solution of ester gum in acetone containing castor oil or other softener is stirred into water to give an emulsion. The synthetic resin "Amberol" is melted and then butyl stearate and castor oil are added. The mixture is cooled and then dissolved in carbon tetrachloride. The solution is stirred into water to give an emulsion. Treatment of the yarns or the like with these compositions also renders them resistant to chemicals, water, and vermin, and gives them a glossy appearance. Specification 470,331, [Group IV], is referred to.