Abstract: Highly coherent and rigid synthetic multifilamentary yarn of improved functional properties having a novel and unique configuration composed of multiple, retained, successive and alternate twist regions is manufactured by twisting thermoplastic fibers by a false-twisting means and at a high temperature selected with reference to the combined properties of the degree of the double refraction and the density of the material fiber.

Abstract: A synthetic multifilament textured yarn provided with randomly formed compact portions and bulky portions formed between two adjacent compact portions. The compact portions are provided with a certain twist and the bulky portions consist of a plurality of individual filaments, each having random crimps. Each of said individual filaments are separated from each other, and the twist direction of each of said bulky portions is opposite from that of two adjacent compact portions. This textured yarn can be produced by a conventional false-twist operation under a processing temperature between a softening point and a melting point of the material yarn.

Abstract: A method for manufacturing a textured synthetic multifilament yarn having alternately grouped S and Z twists. The textured yarn is produced by a conventional false-twist operation under a processing temperature between a softening point and a melting point of the material yarn in a first step and then the above-mentioned yarn is subjected to a process for separating individual filaments in each of the compact portions under tension.