Patent GB-1206376-A (GB)
Title: An improved acrylonitrile fiber and a method for producing the same
IPC: D01F8/08
Filed: 1968-05-28
Abstract: 1,206,376. Acrylonitrile polymer filaments. MITSUBISHI RAYON CO. Ltd. 28 May, 1968 [22 June, 1967], No. 25586/68. Heading B5B. An acrylonitrile polymer filament containing at least 50% by weight of acrylonitrile has an orientation measured by the iodine method lower than 3À5 and a knot elongation from 10 to 45%. Preferably, the iodine orientation is lower than 3À0 and the knot elongation is preferably from 15 to 40%. The acrylonitrile polymer filament is suitably a copolymer containing more than 85% by weight of acrylonitrile and up to 15% by weight of at least one other mono-ethylenically unsaturated monomer copolymerizable therewith, especially methylacrylate, methyl-methacrylate or vinyl acetate, or a mixture of at least two thereof or acrylamide, methacrylamide, acrylic acid, methacrylic acid, styrene, vinyl chloride, vinylidene chloride, vinyl bromide, methacrylonitrile, vinyl pyrrolidone, allyl sulphonic acid, methallyl sulphonic acid, vinyl-benzene-sulphonic acid, methallyl - oxybenzene - sulphonic acid, salts of the above-described sulphonic acids, or mixtures of two or more thereof to improve dyeability. The filament may be treated by embossing to provide numerous fine nodules upon the surface of the filament. Filaments having the above-described properties may be made by dissolving said polymer with dimethylacetamide, to form a spinning solution; extruding said solution into an aqueous coagulating bath containing dimethylacetamide to form filaments; taking up said filaments at a jet-drawing ratio (J) from 0À35 to 0À8; and stretching said filaments 2À0 times. The wet spinning method is preferred, using a coagulating bath composed of water and the solvent used for dissolving the aorylonitrile polymer or composed of a mixture of such solvents with a lower aliphatic alcohol. Alternatively, dry spinning may be used as may also a wet spinning method in which an organic solvent is used for dissolving the polymer and a highly concentrated aqueous solution of inorganic salt is used as the coagulant. Following the stretching, the filaments may be heat treated either while fixed or while free to relax. The filaments may further be embossed, suitably by pressing the filaments on a roller, on the circular surface of which numerous fine unsymmetrical nodules are formed, heated at a temperature between 180‹ and 300‹ C. by a rubber press roller at a temperature from 6 to 50 kg. per sq. cm. In this way an embossed filament is obtained, a felting effect, optical effect, and improvement in spinnability of the yarn due to an increase in cohesiveness of the filaments. Filaments so made have an elegant lustre, pleasing hand feel, and are as pliable and slick as Merino wool fibres, with a smooth surface, and good resistance against film formation and fibrillation. Example 1 relates to the production of such filaments by wet spinning from dimethylacetamide solution using an aqueous coagulating bath containing 50% by weight of dimethylacetamide; in Example 2, the same spinning solution is used, but spun into an aqueous coagulating bath containing 40% by weight of calcium chloride; in Example 3, the same spinning solution is used but spinning. is effected by the dry jet wet-spinning method, using a 5 mm, gap and an aqueous coagulating bath containing 50% by weight of dimethylacetamide; in Example 4, a 30% by weight spinning solution containing an acrylonitrile polymer composed of 93% by weight acrylonitrile and 7% by weight of methylacrylate dissolved in dimethylformamide is dry spun using a cabinet temperature of 200‹ to 220‹ C., and the filaments, after drying, are stretched in hot air at 160‹ C.; and Example 5 relates to the treatment of the filament of Example 1 by embossing.