GB1356652A - Method for producing a crimped yarn and the yarn produced thereby - Google Patents

Abstract

1356652 Crimping yarns FIBER INDUSTRIES INC 20 May 1971 [20 May 1970] 16004/ 71 Headings D1F and D1W A process for producing a crimped yarn having latent bulking characteristics comprises drawing a multi-filament yarn, heating the yam to between 80 and 160‹C, crimping the yarn, withdrawing the yarn from the crimping zone under constant tension and at uniform speed, cooling the yarn, increasing yarn tension to a constant tension between 0.003 and 0.5 grams per denier to reduce crimp amplitude, and compacting the yarn. The yarn may be heated by a draw roll, preferably being wrapped a number of times around the roll. The yarn may be stretched between drawing and crimping by 0.01 to 10 per cent. The yarn is preferably crimped by a stuffer box crimper which extrudes the yarn under a tension of 0 to 0.05 grams per denier. The yarn may alternatively be crimped by knife edge, false twist or gear crimping. The yarn may be cooled by a gas jet which also tensions the' yarn to 0.004 to 0.07 grams per denier. The yarn may be compacted, to facilitate further processing by entanglement by gas jets, by twisting or by the application of adhesive. The yarn produced may comprise continuous, synthetic, polymeric filaments each. having 5 to 32 crimps per inch, an uncrimped frequency of 4 to 16, and a per cent crimp of 22 to 50, and may have a total shrinkage of 20 to 50 per cent. The yarn crimp configuration may be sinusoidal, with 22 to 45 per cent crimp, or helical, with 22 to 50 per cent crimp, or saw tooth with 25 to 32 per cent crimp. The yarn may have a denier per filament of 8 to 40, a total denier of 500 to 5,000, and may be made of a polyamide. The uncrimped frequency is defined as the number of crimps in a crimped length divided by the extended length of the same crimped length. The per cent crimp is calculated by measuring the difference in filament length under loads of 0.07 and 0.0001 grams per denier, and expressing the difference as a percentage of the length under the larger load. The total yarn shrinkage is calculated by measuring the difference in length of a loaded yarn before and after steaming and drying, and expressing the difference as a percentage of the first measured length.