Method and apparatus for the production of large threads of synthetic material of the class of the polyamides

摘要

Voluminous yarn is made from an oriented normally smooth continuous nylon filament yarn by continuously passing said yarn through a zone to a point where a false twist is applied thereto, said false twist running backwardly along the yarn against the direction of its travel from the twist-applying point, an aqueous formic acid solution of 65-75% by weight concentration being applied to the yarn rearward of said twist-applying point while the PICT:0901069/IV(a)/1 PICT:0901069/IV(a)/2 yarn is twisted, the temperature of the solution being at most 95 DEG C., whereupon the twist is chemically set, and then extracting the formic acid from the yarn by passing the yarn through a bath containing an extractant for the formic acid before the point where the false twist is effected. The yarn so treated may initially have a slight twist or may be twistless, i.e. a tow, and specified materials include nylon 6-6, nylon 4, nylon 6, nylon 6-10, and copolymers, e.g. nylon 6/6 -6, nylon 6/6 -a10/6 -6, and nylon 6- 6/6 -10. The formic acid may be extracted from the yarn with water, e.g. hot water at 50 DEG -100 DEG C. Apparatus as shown comprises a source of nylon continuous filament yarn 11, a first twist stop device, e.g. rolls 13, and a second twist stop device, e.g. rolls 32, a rotatable member adapted to produce a false twist in the yarn mounted between the false twist devices (28, 30), and driving means therefor 31, means for treating the yarn with the formic acid mounted between the first twist stop device and the rotatable member, and means for washing the yarn substantially free of the formic acid mounted between the treating means and the rotatable member, the yarn-treating and yarn-washing means being adapted to permit the twist imparted to the yarn to run back unimpeded to the first twist stop device. The yarn-treating means may comprise a vessel 15 containing the formic acid 14 and a liquid absorbent means extending into the vessel for applying the formic acid solution to the yarn. The liquid absorbent means may be a roll 16 carrying a liquid absorbent material 17 on its periphery rotatably mounted in the vessel and partically submerged in the liquid therein, or may be a wick 33 supported on a rod 34 and immersed in the liquid, additional formic acid being supplied to the yarn if necessary by spray 35. The washing means may comprise a vessel 20 containing hot water 18 adapted to extract formic acid from the yarn by the establishment of both a countercurrent and a concurrent flow of wash water, with respect to the directional movement of the yarn. As shown water is sprayed on to the yarn from spray 22, and overflows from the vessel 20 at points 23 and 24.ALSO:PICT:0901069/IV (b)/1 PICT:0901069/IV (b)/2 Voluminous yarn is made from an oriented normally smooth continuous nylon filament yarn by continuously passing said yarn through a zone to a point where a false twist is applied thereto, said false twist running backwardly along the yarn against the direction of its travel from the twist-applying point, an aqueous formic acid solution of 65-75% by weight concentration being applied to the yarn rearward of said twist-applying point while the yarn is twisted, the temperature of the solution being at most 95 DEG C., whereupon the twist is chemically set, and then extracting the formic acid from the yarn by passing the yarn through a bath containing an extractant for the formic acid before the point where the false twist is effected. The yarn so treated may initially have a slight twist or may be twistless, i.e. a tow, and specified materials include nylon 6-6, nylon 4, nylon 6, nylon 6-10, and copolymers, e.g. nylon 6/6-6, nylon 6/6-10/6-6, and nylon 6-6/6-10. The formic acid may be extracted from the yarn with water, e.g. hot water at 50-100 DEG C. Apparatus as shown comprises a source of nylon continuous filament yarn 11, a first twist stop device, e.g. rolls 13, and a second twist stop device, e.g. rolls 32, a rotatable member adapted to produce a false twist in the yarn mounted between the false twist devices (28, 30), and driving means therefor 31, means for treating the yarn with the formic acid mounted between the first twist stop device and the rotatable member, and means for washing the yarn substantially free of the formic acid mounted between the treating means and the rotatable member, the yarn-treating and yarn-washing means being adapted to permit the twist imparted to the yarn to run back unimpeded to the first twist stop device The yarn treating means may comprise a vessel 15 containing the formic acid 14 and a liquid absorbent means extending into the vessel for applying the formic acid solution to the yarn. The liquid absorbent means may be a roll 16 carrying a liquid absorbent material 17 on its periphery rotatably mounted in the vessel and partially submerged in the liquid therein, or may be a wick 33 supported on a rod 34 and immersed in the liquid, additional formic acid being supplied to the yarn if necessary by spray 35. The washing means may comprise a vessel 20 containing hot water 18 adapted to extract formic acid from the yarn by the establishment of both a countercurrent and a concurrent flow of wash water, with respect to the directional movement of the yarn. As shown, water is sprayed on to the yarn from spray 22, and overflows from the vessel 20 at points 23 and 24.