Abstract: A cooling apparatus of a high speed false texturing machine in which a so-called surging phenomenon is prevented, yarn breakages are not increased, unevenness in yarn dyeing does not occur, and deterioration of crimp characteristics in obtained textured yarn is prevented. A false texturing machine includes a false twisting device (6) for imparting twists to a yarn (2), a heating apparatus (3), disposed upstream from the false twisting device (6), for heat setting twists that run back along the yarn (2), and a cooling apparatus (4, 5), disposed between the heating apparatus (3) and the false twisting device (5), for cooling the yarn. The cooling apparatus (4) has a plurality of partial cooling plates (8). A yarn pressing member (9) serves to insert the yarn (2) into a space between the adjacent partial cooling plates (8) beyond a common contacting line of the adjacent partial cooling plates (8).

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.