US 4,086,751 AGranted

Process for producing a fused false twisted continuous filament yarn having crispness characteristics of hard high-twist yarn

AssigneeTeijin Limited

InventorsHajime Hino, Yoshiyuki Sasaki, Toshio Sekiguthi, Masaaki Yao

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Abstract

False-twisted yarn uniformly fused in alternate s- and z-twisted state, and having crispness characteristic of hard twist yarns is provided from partially oriented polyester filament yarn by subjecting the said polyester filament yarn to simultaneous draw false-twisting process employing lower draw ratio, lower number of false twists and higher heat setting temperature. The partially oriented polyester filament yarn used as a feed yarn has birefringence value of 0.03 - 0.10 and break elongation of 70 - 200%. General range of processing conditions is such that draw ratio of 0.7 R.sub.o - 0.95 R.sub.o wherein R.sub.o is an apparent draw ratio to impart a drawn yarn break elongation of 30% when a feed yarn is drawn at such draw ratio (R.sub.o), false twist per meter of 15000/.sqroot.De - 28000/.sqroot.De wherein De stands for a denier of the yarn passed a false twisting mean, and heat setting temperature of 225.degree. - 255.degree. C. These three conditions are also interrelated each other for stable operation of simultaneous draw false-twisting for obtaining uniformyly fused yarn.

Claims7

Dependent claims

A process for producing a fused false-twisted continuous filament yarn having crispness characteristic of hard twist yarns, which comprises

a. forwarding a polyester continuous filament yarn as a feed yarn having both birefringence value of 0.03 - 0.10 and break elongation of 70 - 200% to simultaneous draw-false twisting zone comprising a feed roll assembly, a heater, a false twisting mean and draw roll assembly in sequence,
b. false twisting the same at a number of turns permmeter expressed by a .alpha. .times. 1000/.sqroot.De wherein .alpha. is a twist coefficient of 15 - 28, and De means a denier of the yarn which has passed the false twisting means,
c. heating the same twisted yarn to a temperature of 225.degree. - 255.degree. C and simultaneously drawing the yarn at a draw ratio of R.sub.1 .times. R.sub.0 wherein R.sub.1 is a draw coefficient of 0.7 - 0.95, and R.sub.0 is an apparent draw ratio to impart a drawn yarn break elongation of 30% when the feed yarn is drawn at such draw ratio (R.sub.0),
d. maintaining the following relation exists between .alpha. and R.sub.1
(- .alpha./260) + 0.99 .gtoreq. R.sub.1 .gtoreq. (- .alpha./160) + 0.95
wherein .alpha. and R.sub.1 is same as hereinbefore defined,
e. untwisting the heat-set and drawn yarn and consequently withdrawing the resulting yarn.

4 more elements

Dependencies are inferred from the claim text.