Abstract: High-strength filaments of dry-spun polyacrylonitrile are obtained by a process in which tension-reduced spun filaments are continuously stretched hydrothermally in one or more stages: where it involves several stages, stretching is carried out at a temperature of the stretching medium gradually increasing from stage to stage up to .theta.=.theta..sub.n and, in the final (n-th) stage, to a degree of at least 50% of the maximum degree of stretching; where it is carried out in a single stage, stretching is carried out at the optimal stretching temperature .theta..sub.n, after which the material is further treated in the conventional way, optionally with fixing of the stretched material to a pre-determined extent.

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 a process for the stabilization of a spinning solution of an acrylonitrile polymer and a solvent which comprises adding from 0.005 to 0.5% based on the quantity of polymer of at least one stabilizer selected from a polyfunctional phosphonic acid, a phosphonocarboxylic acid or a polymer containing phosphonic acid and/or carboxyl groups to the spinning solution as well as to such stabilized spinning solutions.

Abstract: The invention relates to gloss-stable modacrylic fibres and filaments comprising 50 to 84% of acrylonitrile, 15 to 48% of vinylidene chloride and 2 to 5% of an olefinically unsaturated sulphonic acid or salt thereof, all percentages being by weight, having a shrinkage in boiling water of at most 0.3%, a reduction in density on treatment with boiling water of no more than 0.015 g/cc and a scattered light component after boiling of at most 35 units compared with a BaSO.sub.4 standard of 1000 units, the increase brought about by treatment with boiling water amounting to no more than 30 units as well as to a process for their production.

Abstract: The invention relates to a process for continuously removing residual solvent from filaments of dry-spun acrylonitrile polymers to values of below 2% by weight of solvent by a multi-stage hot-wash with low quantities of water.

Abstract: The invention relates to a process for the production of bifilar fibres and filaments consisting of only one acrylonitrile polymer. The polymer is dissolved in a usual solvent and the resulting solution is divided up into two solution streams. After these solution streams have been brought to different temperatures they are spun by a conventional bifilar spinning technique.

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 a process for the production of high-shrinkage wet-spun acrylic fibres having good fibre strength and high densities by fixing the unstretched fibres with saturated steam and then stretching in a ratio of from 1:3,5 to 1:5.

Abstract: The invention relates to a process for the production of bulk yarns from chemically different acrylonitrile polymers.

Abstract: The invention relates to a process for the continuous uniform and penetrative dyeing with high fastnesses of slivers or filaments of acrylonitrile polymers which have been produced by a standard wet-spinning process wherein the slivers or filaments prior to dyeing are subjected to a combined washing, pressing and drying pretreatment.

Abstract: The invention relates to a process for the production of polyacrylonitrile tows containing from 7 - 15 % by weight, preferably from 10 - 12 % by weight, of comonomer components from which it is possible to produce yarns having low boiling-induced shrinkage values and yarns and dimensionally stable made-up articles with improved textile properties which comprises reducing the tow-shrinkage emanating from the spinning and stretching process by 80 - 95 % of the original tow shrinkage by heat-fixing and eliminating subsequently the residual shrinkage by fixing with saturated steam.