Abstract: Disclosure describes ball-like structures formed from bundled, crimped fibers rounded around a central portion thereof as a core, the core being formed with a molten-fused structure and having the following stipulations:(a) a density of the molten-fused structure is not less than 75% based on a density of the crimped fibers forming the ball-like structures.(b) a length of the molten-fused structure is 5 to 50% based on a diameter of the ball-like structures, and(c) a withdrawing strength of a crimped fiber strand connected with the molten-fused structure is not less than 50% based on a linear strength of the crimped fiber strand itself used for the ball-like structures.

Abstract: Core materials for strings for musical instruments of a twist of two or more multifilaments composed of a vinylidene fluoride resin. The multifilament core has a diameter of 0.1 to 5 mm, an elongation of 10 to 50%, a tensile strength of at least 30 kg/mm.sup.2, a creep elongation of at most 15% and a Young's modulus of at least 200 kg/mm.sup.2. The multifilament is made of monofilaments each having a diameter of 1 to 300 .mu.m, a dispersion diameter of at most 20%/m, a specific gravity of at least 1.6, an inherent viscosity of 0.85 to 1.6 dl/g, an apparent viscosity of 12,000 to 100,000 poise and a birefringence of 30.times.10.sup.-3. Strings for violins, cellos and the like are made by tightly wrapping the core with a metal string.

Abstract: A string for a musical instrument consisting of a monofilament made of a resin of vinylidene fluoride and having the following characteristics which give good clearness of sound, good sharpness of sound and good spread of sound:(1) the diameter of the monolfilament is in the range of 0.4 to 1.5 mm .phi.;(2) the unevenness of the diameter of the monofilament is less than 5% per meter of the monofilament length;(3) the circularity of the section of the monofilament is more than 95%;(4) the specific gravity is more than 1.6;(5) the inherent viscosity is in the range of 1.1 to 1.6 dl/g;(6) the apparent viscosity with the shear rate of 1/100 at 260.degree. C. is in the range of 8000 to 20000 poises;(7) the index of double refraction is in the range of 30.times.10.sup.-3 to 40.times.10.sup.-3 ;(8) the tensile strength is more than 50 kg/mm.sup.

Abstract: Disclosed herein is a contact material for treating sewage, comprising a braid which is made of synthetic fibers and has loop piles, the weight of the synthetic fibers forming the loop piles being from 40 to 90% by weight of the synthetic fibers of the whole body of the braid.

Abstract: A process for manufacturing a string construction having a core thread and a network thread around them by extruding thread-like molten resin streams from an extruding apparatus in which an inner spinneret formed with grooves at the outer circumferential surface is rotatably mounted to an outer spinneret formed with grooves at the inner circumferential surface, and the outer circumferential surface and the inner circumferential surface are slidingly contacted to each other.

Abstract: A gut having a novel structure made of a thermoplastic resin and a method of producing the same.

Abstract: A string construction for athletic rackets which can be frictionally engaged with a tennis ball or a badminton shuttlecock very well upon hitting it and which can be uniformly stretched on the athletic racket frame without being twisted, comprises a string-like core made of thermoplastic resin material and a tubular netlike structure made of thermoplastic resin material, the tubular netlike structure netting over and being secured to an outer circumference of the core, wherein the netlike structure includes a plurality of thread-like members forming a plurality of nodes at intersections thereof, all the thread-like members forming each node being integral with each other at each node, and projecting from the outer circumference of the core to a height substantially equal to each other at each node.

Abstract: A gut having a novel structure made of a thermoplastic resin and a method of producing the same.