| 摘要 |
1,245,522. Polyester yarns. SOC. RHODIACETA. 18 Feb., 1969 [19 Feb., 1968], No. 8860/69. Heading B5B. [Also in Divisions D1-D2] A textile article as described and claimed in copending Specification 1,245,361 is further characterized in that all the zones in each filament have a positive degree of crystallinity. A process for making a textile article as above comprises, as the sole stretching operation, partially stretching the yarn in contact with a crack-promoting agent e.g. hydroxylated compound in an aqueous solution or an aqueous lower alcohol, and subjecting the stretched yarn to a relaxation treatment in at least two stages, at least the last of which is accompanied by a heat treatment. In a preferred embodiment yarn 3 is fed from a bobbin 2 on a creel 1 by means of feed rollers 4, 5 and passed through a vat 7 containing the crack-promoting agent. During passage through the vat the yarn is stretched by means of rollers 8, 9 rotating at a faster peripheral speed than the rollers 4, 5. From the rollers 8, 9 the stretched yarn passes a heater 12 and a first set of relaxation rollers 10, 11, before passing to a second heater 13 and a second set of relaxation rollers 14, 15 and being wound at 16. Each relaxation stage is preferably accompanied by a heat treatment, the last such heat treatment preferably being a shock heat treatment. At some stage after the stretching the yarn may be dyed. In a preferred embodiment, a polyethylene terephthalate multifilament yarn is stretched in an aqueous bath containing 25% ethanol at ambient temperature and is then relaxed to various degrees at various temperatures of the plate 12. The yarn is thereafter heat treated in a completely relaxed state by immersing it in water at 40‹ C., progressively raising the temperature of the water to 100‹ C. and keeping the yarn at this temperature for 5 minutes. The yarn is then dried without tension while freely exposed to the air and then heated in an oven for 5 minutes at 180‹ C. |
