Abstract: Hollow polyacrylonitrile fibers having a uniform closed cavity structure are obtained by dry-spinning filament-forming acrylonitrile polymers from a solution through a spinning jet comprising annular jet bores of the type shown in FIG. 1, the solution having a viscosity of at least 120 falling-ball seconds, as measured at 80.degree. C. or of at least 75 falling-ball seconds, as measured at 100.degree. C., the ring of the annular jet bores consisting of three, preferably equally large, ring segments at a distance from one another of at most 0.2 mm, the surface area of the jet bores of the profile jet amounting to less than 0.2 mm.sup.2 and the side width of the ring segments amounting to at most 0.1 mm, the spinning air acting on the filaments transversely of the direction in which they are taken off relative to the center of the spinning jet.

Abstract: The invention relates to a process for the continuous production of synthetic non-discolored filaments and fibers from a filament forming synthetic polymer being difficultly soluble in an organic polar solvent particularly polyacrylonitrile polymers which process comprises preparing a suspension of said polymer and said solvent at room temperature and subsequently heating the suspension thus formed for at least 3 minutes to at least 130.degree. C., and filtering the clear spinning solution formed without intermediate cooling, homogenizing and spinning it immediately afterwards into filaments.

Abstract: Dry-spun synthetic fibers and filaments having an individual as-spun denier of 3 dtex are obtained by dry-spinning a viscosity-stable spinning solution with a draft of at least 20.

Abstract: The invention relates to a process for the production of hydrophilic filaments and fibres from a filament-forming synthetic polymer by a wet- or dry-spinning process which comprises introducing into the spinning solvent from 5 to 50% by weight of a substance with special properties defined herein and from 0.05 to 5% by weight of at least one surface-active compound as well as to hydrophilic filaments and fibres produced by such process.

Abstract: The invention relates to hygroscopic filaments and fibres of synthetic high polymers. The improved hygroscopicity compared with known synthetic fibres is due to the fact, that in a conventional dry-spun process a liquid is added to the spinning solvent which liquid has a higher boiling point than the spinning solvent used, which liquid is readily miscible both with the spinning solvent and water and which represents a non-solvent for the polymer to be spun.

Abstract: The invention relates to dry-spun hydrophilic core-jacket filaments or fibres of a hydrophobic filament forming synthetic polymer. The filaments or fibres having a porosity of at least 50%, a water-retention capacity of at least 100% and a mercury density of at most 0.7 g/cm.sup.3. The invention also relates to a process for the production of these fibres and filaments.

Abstract: Dry-spun hydrophilic core-jacket filaments and fibres of polycarbonates having a porosity and a water retention capacity of at least 10%, a mercury density of less than 1.0 g/cc, a strength of at least 1.5 cN/dtex and a second order transition temperature of at least 125.degree. C. and a method for producing said filament and fibres by a dry-spinning process, wherein, immediately on leaving the spinnerette but before solidifying, the filaments are brought into contact with steam.

Abstract: The invention relates to a process for the production of hydrophilic filaments or fibres having a sheath/core structure, a porosity of at least 10% and a water retention capacity of at least 10% and having a fibre swelling factor which is lower than the water retention capacity. The process is carried out by spinning a solution of a fibre forming synthetic polymer, especially an acrylonitrile polymer by the dry jet wet-spinning method wherein immediately on leaving the spinning jet and prior to coagulation in the precipitation bath the filaments or fibres are contacted with steam or with the vapor of another liquid which coagulates the filaments.

Abstract: The invention relates to a process for the production of hydrophilic filaments and fibers from filament-forming synthetic polymers by spinning a solution which, in addition to a suitable solvent, contains from 5 to 50% by weight, based on the solvent and solids, of a substance which is essentially a non-solvent for the polymer, has a higher boiling point than the solvent used and is readily miscible with the spinning solvent and with a liquid suitable as a washing liquid for the filaments, and subsequently washing this substance out of the filaments, wherein a suspension is initially prepared at room temperature from the solvent, the polymer and the substance, the suspension thus prepared is subsequently heated, left for at least one minute and at most 15 minutes at a temperature of at least 30.degree. C. and of at most 60.degree. C.

Abstract: The invention relates to a process for the production of hygroscopic filaments or fibers by dry-spinning a polymer solution wherein immediately they issue from the spinning jet or at the latest at a time when their solidification is still not complete, the filaments are brought into contact with water-vapour or with the vapour of another liquid which coagulates filaments.

Abstract: The invention relates to a process for the production of hydrophilic filaments and fibers which comprises wet- or dry-spinning a fibre-forming synthetic polymer from a spinning solvent containing from 5 to 50% of a substance which has a higher melting or boiling point than the spinning solvent which is miscible with the spinning solvent and with a liquid suitable for use as a washing liquid and which is a non-solvent for the polymer to be spun and from 0,1 to 20% by weight of at least one substance which decomposes into a gas under heating.

Abstract: The invention relates to hydrophilic fibers and filaments with good coloring response to dyes from filament-forming hydrophobic synthetic polymers having a sheath-core structure with a highly microporous core and a substantially compact sheath and having a water retention capacity of at least 10% wherein the pores in the core have an average pore diameter measured in the direction of the cross-section of the fiber, of at most 4000 A. The invention relates also to a process for the production of those filaments and fibers according to a dry-spinning process wherein a spinning solution is spun below the boiling point of the spinning solvent used.

Abstract: The wearing comfort of textiles produced from synthetic fibers which are normally hydrophobic, e.g., polyacrylonitrile, is improved by modifications in the spinning process whereby hygroscopic fibers having a sheath/core structure and a microporous core are obtained, which fibers are capable of absorbing considerably more water than conventionally dry spun fibers of the same synthetic polymer not having a sheath/core structure. Several suitable dry spinning processes for producing the improved fibers are disclosed.

Abstract: The invention relates to a bi-component filament or fibre of a fibre-forming synthetic polymer having a core/sheath structure in at least one component and having a moisture absorption of at least 1.5% at 65% relative atmospheric humidity and at a temperature of 21.degree. C. and a moisture absorption of at least 5% at 90% relative atmospheric humidity and 21.degree. C. and a water-retention-power of at least 10% as well as to a process for the production thereof.

Abstract: The invention relates to a process for the production of filaments and fibres having a moisture absorption of at least 7% and a water retention capacity of at least 25% by dry-spinning an acrylonitrile copolymer, containing more than 50 mval of carboxyl groups from a solvent, which contains 5 to 50% by weight of a compound with properties defined herein, washing the compound added to the solvent out of the freshly spun filaments and fibres and partly or completely converting the carboxyl groups into the salt form. The invention further relates to dry-spun filaments and fibres having a core and sheath structure, comprising a fibre-forming acrylonitrile copolymer having more than 50 mval of carboxyl and carboxylate groups and having a moisture absorption capacity of at least 7% and a water retention capacity of at least 25%.

Abstract: The invention relates to dry-spun acrylic fibers and filaments having deniers of from 20 to 80 dtex and a strength of at least 1.5 cN/dtex; as well as to a process for their production.

Abstract: The invention relates to a process for the production of crosslinked fibres or filaments by spinning an acrylonitrile copolymer containing at least 20 mVal of carboxyl groups per kg of polymer together with a polyoxazoline in a polar organic solvent and thereafter crosslinking at temperatures of from 120 to 190.degree. C.The invention also relates to crosslinked acrylonitrile fibres and filaments obtainable by this process.

Abstract: The invention relates to highly shrinkable fibres or filaments of acrylonitrile polymers or copolymers which have a shrinkability of at least 35% and a fibre strength of at least 2 p/dtex.The invention relates further to a process for the production of these fibres or filaments.

Abstract: The invention relates to cross-linkable or cross-linked filaments or fibers of a copolymer comprising at least 65% by weight of acrylonitrile and from 0.5 to 10% by weight of at least one copolymerised N-methylol compound of an unsaturated mono- or bis-urethane or an alkyl ether thereof and, optionally, at least one other copolymerisable monomer.

Abstract: This invention relates to a process for the production of dyed filaments or fibres of acrylonitrile polymers, wherein carbon black pigments are added to the polymer before the spinning process and the filament containing carbon black pigments are dyed. By this process it is possible to save considerable amounts of dye-stuff.