Abstract: A deep-dyeable polyester fiber of soft hand comprising recurring units consisting mainly of ethylene terephthalate and --SO.sub.3 M groups in which M is an alkali metal, and having a degree of crystallinity .chi..sub..rho. of from 30 to 55%, a degree of orientation .DELTA.n of from 0.06 to 0.12 and .chi..sub..rho. /.DELTA.n of from 350 to 550. The fiber can be produced by heat treating a melt spun, slightly oriented filament under relaxation and then drawing the heat treated filament at a low temperature.

Abstract: Disclosed is a textured composite yarn composed of a first multifilament yarn having a lower extensibility and a second multifilament yarn having a higher extensibility, as well as a process for manufacturing such textured composite yarn. The first multifilament yarn forms a core yarn, while the second multifilament yarn is wrapped at least partially around the core yarn. Some individual filaments of the second multifilament yarn are entangled and interlaced with some filaments of the first multifilament yarn in the boundary region between the core yarn and the wrapping yarn.

Abstract: After a polyester tow having a total denier of 5000 de is drafted at a ratio of between 10 and 20 and stretch broken, the obtained fiber bundle of staple fibers is subjected to a false twisting operation by means of a fluid jet nozzle, and then the false twisted fiber bundle is wound several turns around a hot roller heated at a temperature of 220.degree. C. and located in a detwisting region downstream from the false twisting nozzle. The surface fibers, which extend outwards because of the centrifugal force generated by the rotation of the fiber bundle during the detwisting thereof, suddenly stopped rotation when the fiber bundle contacts the hot roller, and the surface fibers wrap around the body portion of the fiber bundle to form a plurality of individual wrapping portions, in each of which the surface fibers are interlaced each other. Thus a spun-like yarn is obtained.

Abstract: Disclosed is a novel bulkable filamentary yarn of a flat yarn-like smooth appearance, said bulkable filamentary yarn is composed essentially of a bulkable portion and an interlaced portion existing alternately along the yarn length. Upon scouring, for example, said yarn develops its latent bulkiness similar to the fullness of silk, thus a silk-like appearance as well as a silk-like hand are provided in a fabric. The yarn itself can be obtained by heat-shrinking arc-like loops protruding on the yarn surface into a straightened state parallel to the yarn while the yarn is being tensioned along its length.

Abstract: Novel polyester filamentary yarn is provided having (a) a fineness of 0.9 denier per filament or less, (b) an amorphous orientation in the range of 30% to 70% and (c) a negative .epsilon..sub.0.2 where said .epsilon..sub.0.2 is a structural integrity parameter. The yarn possesses ameliorated properties regarding a heat-setting property, a raising property, a dimensional stability and a twist resistance. The yarn finds its wide range of usage, for example, silky fabrics with an excellent fullness, pliability and liveliness, raised fabrics with thermally stabilized fluffs protruding straight-forwardly and an extremely soft hand, and uniformly creped fabrics with an improved surface contour are obtained therefrom.

Abstract: A method for converting a multifilament bundle of a synthetic material into a sliver and an apparatus for effecting the method. The apparatus comprises: a feed roller device for feeding the bundle; a draft roller device consisting of a pair of draft rollers, the peripheral speed of which draft roller device is higher than that of the feed roller device, for stretch breaking the filaments in the bundle between the feed roller device and the draft roller device; and an apron belt, belted between one roller of the draft roller device and the intermediate portion of the feed roller device and the draft roller device, which is wound around the other draft roller. The broken filaments are smoothed between the apron belt and the other draft roller so that the evenness of the sliver thickness is improved and the uniformity in quality of the spun yarn obtained from the sliver is also improved.

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.

Abstract: A multifilament yarn of improved bulkiness is provided. The yarn is composed of two portions, i.e., a relatively dense portion and a blooming, relatively sparse portion, alternately occurring along the length of the yarn. The relatively dense portion is in a partially twisted state and individual filaments in this portion are irregularly entangled and cohere to a greater extent than in the relatively sparse portion. The relatively dense portion has protruding filament ends on the yarn surface in a larger number than the relative sparse portion.The yarn is prepared by first passing a multifilament yarn through a high velocity fluid jet nozzle and then subjecting it to a combination of the steps of false twisting and frictional contact.