A false-twisted polyester yarn of good dyeing and mechanical properties is produced by a process wherein a yarn consisting of an as-spun polyester fiber having a mean birefrigence index (.DELTA.n) of from 15.times.10.sup.-3 to 150.times.10.sup.-3 is heat-treated and continuously, subjected to a false twisting treatment or draw-false twisting treatment. A preferred apparatus used comprises a feed yarn creel, a false twisting heater and an optional stabilizing heater, a false twisting element and a winder, wherein a heat-treating heater of the non-contact type is arranged upstream of the false twisting heater and between the false twisting heater and the feed yarn creel, at a height substantially equal to the height of the feed yarn creel so that the heat-treating heater confronts the false twisting heater; and a yarn cooling zone is provided between the heat-treating heater and the false twisting heater.
A method of manufacturing a composite yarn and composite yarn produced thereby in which a spandex yarn is fed to an air entangling or covering jet while being pre-elongated. Simultaneously, a multifilament partially oriented thermoplastic yarn is fed to the yarn entangling or covering jet while being partially or completely drawn to orient further or completely the thermoplastic yarn. The thermoplastic and spandex yarns are fed through the yarn jet while the filaments of the thermoplastic yarn are entangled to produce a composite yarn with the spandex yarn as the core and the thermoplastic yarn as a covering therefor. The composite yarn is then fed through a false twister and false twisted with the false twist being heat set in the thermoplastic yarn at a temperature which does not adversely affect the spandex core to produce an air entangled false twist texturized composite yarn. If not completely oriented when false twisted, the thermoplastic yarn is further drawn to complete its orientation while being false twisted.
A yarn heating apparatus which is adapted for use in a yarn false twisting machine. The heating apparatus includes an elongate heating surface, and a plurality of yarn guide members mounted in a longitudinally spaced-apart arrangement along the length of the heating surface, for guiding an advancing yarn therealong in a laterally zigzagged path of travel which is adjacent but spaced from the heating surface.
The invention provides heat-resistant crimped yarn, of which the constituent heat-resistant high-functional fibers are prevented as much as possible from being deteriorated under heat in the process of producing the yarn. Not losing excellent properties of heat resistance and flame retardancy intrinsic to the heat-resistant high-functional fibers, the crimped yarn has a good elongation percentage in stretch, a good stretch modulus of elasticity and a good appearance, and it fluffs little and releases little dust. The heat-resistant crimped yarn comprises heat-resistant high-functional fibers, and is characterized in that it does not deteriorate under heat, and that its elongation percentage in stretch is at least 6%, its stretch modulus of elasticity is at least 40%, and its tenacity falls between 0.15 and 3.5 N/tex.
The invention provides heat-resistant crimped yarn, of which the constituent heat-resistant high-functional fibers are prevented as much as possible from being deteriorated under heat in the process of producing the yarn. Not losing excellent properties of heat resistance and flame retardancy intrinsic to the heat-resistant high-functional fibers, the crimped yarn has a good elongation percentage in stretch, a good stretch modulus of elasticity and a good appearance, and it fluffs little and releases little dust. The heat-resistant crimped yarn comprises heat-resistant high-functional fibers, and is characterized in that it does not deteriorate under heat, and that its elongation percentage in stretch is at least 6%, its stretch modulus of elasticity is at least 40%, and its tenacity falls between 0.15 and 3.5 N/tex.
A method of manufacturing autohesion thread such that a smooth surface is offered, the cutting thereof is easy, filaments composing thread are not frayed in cutting, drainability is superior, and plural kinds of filaments can be combined. A method of manufacturing a line of fusion thread, wherein plural filaments comprising thermoplastic resin are paralleled, twisted and/or braided if desired, subsequently drawn under heat at a draw ratio of less than 1.0 to thereby substantially fuse the adjacent filaments, and thereafter drawn under heat at a draw ratio of more than 1.0.
