Patent GB-592592-A (GB)
Title: Process for the production of a highly crimped textile material permanently resistant to swelling
IPC: D02G1/02
Filed: 1944-11-01
Abstract: A textile yarn is highly twisted and while in this condition it is rendered permanently resistant to swelling, without being rendered water-repellent, by treatment with a reagent which modifies the chemical nature of the substance of the yarn, and it is then back-twisted.  The chemical treatment also tends to set the twist so that after the back-twisting the yarn has a permanent crimp.  A temporary high twist may be imparted to the yarn by means of a false-twisting device.  The back-twisting may be carried beyond the zero point.  The yarn may be an artificial silk yarn of regenerated cellulose or cellulose hydrate or it may be a staple fibre yarn of regenerated or natural cellulose such as cotton or linen.  It may be composed of albuminous fibres such as silk.  The yarn may contain mixed fibres.  The high twisting and the back-twisting may be performed on bobbins.  The high-twisting, chemical treatment and back-twisting may be carried out in a continuous working operation. Two staple-fibre yarns may be treated together either side by side or in the form of a twist. When a false twisting device is used, a continuous yarn or metal wire may be associated with a staple-fibre yarn in order that the back-twisting may be carried beyond the zero point.  The chemical treatment may be a treatment with formaldehyde, or a condensation product of formamide and formaldehyde, hexamethylene-1,6-diethyleneurea or an ethylene-urea derivative together with ammonium polyacrylate, or an aliphatic or aromatic di-isocyanate such as hexamethylene - 1,6 - di - iso - cyanate, preferably in presence of a catalyst.  After impregnation the yarn may be pre-dried prior to effecting the reaction or condensation by heating, e.g. at 100 DEG  C. or higher.  Hot air or infra-red rays may be used for heating the yarn.  The treated yarn may be cut to form staple fibres.  Other chemical reagents which may be used are quaternary salts of chloro- or bromo-methyl ethers or esters of low-molecular aliphatic or aromatic monohydric or polyhydric alcohols or carboxylic acids with tertiary bases.  There may also be used quaternary salts of phenols and of halogen-methyl compounds such as the chloro-methyl amides and secondary or tertiary chloromethyl amines.  In an example, viscose artificial silk yarn is passed through a bath of formaldehyde, aluminium thiocyanate and water.  The surplus liquid is squeezed out and the yarn is pre-dried at 60-70 DEG C.  The yarn is given a temporary high twist in a false-twisting device, and is heated to 150 DEG  C. in the twisted section between the feed rollers and the twisting spindle.  After leaving the false-twisting device, the yarn is reeled and steamed.  In another example, cuprammonium yarn is impregnated with a formamide-formaldehyde condensation product and aluminium chloride and pre-dried.  It is highly twisted in a ring frame and heated at 110 DEG  C.  It is then twisted in reverse.  In another example, a viscose staple fibre yarn is doubled with a continuous filament viscose yarn.  The doubled yarn is impregnated with formaldehyde, zinc chloride and potassium alum, and then pre-dried, given a high temporary twist by two false-twisting devices, heated and then allowed to untwist.  A doubled cotton yarn is treated with caustic soda solution and allowed to shrink. The solution is replaced with water and then alcohol and the alcohol is replaced with trichlorethylene.  The yarn is immersed in tetramethylene-diisocyanate in trichlorethylene.  The yarn is dried, highly twisted, heated at 100 DEG  C., and then twisted in reverse. The yarn is crimped and it has an increased affinity for substantive dyestuffs.  In other examples, the yarns are treated with ethyl hydroxymethyl-pyridinium chloride, or a quaternary ammonium salt obtained from the trichloromethyl ether of glycerine and pyridine, or with acetamidomethyl - pyridinium chloride. Specifications 475,170 and 548,079 are referred to. Reference has been directed by the Comptroller to Specification 455,022.