Patent GB-997489-A (GB)
Title: Method and apparatus for wet spinning elastomeric polymers
IPC: D01D5/06
Filed: 1963-04-05
Abstract: 997,489. Wet-spun polyurethane filaments. J. V. WORTHINGTON. April 5, 1963, No. 13548/63. Heading B5B. [Also in Division D1] A solution of an isocyanate-modified dihydroxy elastomeric polymer is wet-spun, the filaments gathered together and sufficient pressure applied to them while they are in contact with the coagulating bath liquid and while they are in the state of semi-plastic flow, to consolidate them into a fused multi-filament fibre, and a twisting action is subsequently imparted to the multifilament fibre while it is in contact with the coagulating bath liquid and while it is in the state of semi-plastic flow, to complete consolidation of the filaments and to impart a roundness to the fused fibre. The twisting action may be accomplished by rolling the multi-filament fibre over a smooth surface. In the apparatus of Fig. 1, the spinning solution is spun through a spinneret 1, into a coagulating bath 2, to form a plurality of filaments 3 which are passed over roll 4 and under roll 5 (Fig. 2), within the V-shaped grooves 6 and 7. of each roll, roll 5 being beneath roll 4 and parallel thereto, so consolidating the filaments into a fused multi-filament fibre 8. Fibre 8 is then passed over roll 9 and under roll 10, within the V-shaped grooves 11 and 12 of each roll, rolls 9 and 10 being laterally displaced with respect to rolls 4 and 5 so that a twisted fibre 13 is formed. Suitably a displacement such that the multifilament fibre leaves roll 5 at an inclined angle of about 75 degrees with respect to the axis of rotation of the roll 5 is used. The sides of the V-shaped grooves may be concave or convex if desired. In an alternative method, not shown, the filaments are led through a suitable restricted area to press them together to form the fused multifilament fibre. In the apparatus of Fig. 4 the rolls 9 and 10 are placed at an angle to the rolls 4 and 5, suitably 15 degrees, so that the multifilament fibre will be subjected to a twisting action as it passes within the V-shaped grooves 11 and 12 of rolls 9 and 10. Fig. 6 illustrates an elastic urethane fibre so made, composed of a plurality of individual filaments intimately fused together into substantially a single fibre unit having substantially no voids therebetween, the filaments retaining their individual filament structure and being spirally arranged to form a substantially rounded fibre. The elastomeric polymers used are made by reacting a difunctional hydroxyl terminated polymer with a molar excess of an organic diisocyanate to produce a low molecular weight isocyanate terminated prepolymer, which is then reacted with a compound containing at least two active hydrogens, e.g. a diamine in the presence of a solvent to form a solution containing the resultant elastomeric polymer. Difunctional hydroxy-terminated polymers which may be used include polyether glycols and polyester glycols. Aromatic, aliphatic and cycloaliphatic diisocyanates may be used to react with the difunctional hydroxy polymers to form the prepolymer, which is then reacted with the diamine in a suitable solvent to form the elastomeric polymer. Many suitable polyether glycols, polyester glycols, isocyanates and diamines are listed. Spinning solvents include dimethyl formamide, dimethyl sulphoxide, and dimethyl acetamide. Water is generally used as the coagulant, and extrusion speeds of 150 feet per min. or higher, using a coagulating bath 6 feet in length, are specified. Specifications 672,923, 796,041, 796,044, 849,154, 849,156, and U.S.A. Specifications 2,948,691 and 2,917,489 are referred to.