Patent GB-1043566-A (GB)
Title: Improvements in or relating to artificial crimped fibres
IPC: D01D5/28
Filed: 1964-01-31
Abstract: 1,043,566. Crimped artificial fibres. MITSUBISHI RAYON CO. Ltd., and MITSUBISHI VONNEL CO. Ltd. Jan. 31, 1964 [Feb. 20, 1963; July 2, 1963; Aug. 19, 1963], No. 4194/64. Heading B5B. Crimped artificial fibres are made by dividing up at least two different spinning solutions, filaments formed from which differ in shrinkability, into a number of parallel contiguous composite streams by means of a flow divider in each of which stream the solutions substantially preserve their separate identity and only intermingle to a limited degree at the boundaries between them and extruding the streams through the orifices of a spinneret into a coagulating medium to form filaments, the number of orifices in the spinneret exceeding the number of holes in the flow divider, extrusion from the spinneret being in such a manner as to form a small mixed bundle of extruded streams some of which are composite filaments consisting of at least two solutions arranged in side-by-side relationship and the remainder of which are homogeneous and consist solely of one or other of the solutions. The filaments thus formed are stretched and then relaxed to develop crimps. As illustrated in Fig. 1 (not shown), which is a longitudinal section of a spinning head which may be used in the production of the filaments, a first spinning solution A is introduced into the spinneret housing 1 through the conduit 12 and after flowing through the chamber 13 in the conical sleeve 2 screwed into the housing 1, flows uniformly through all the holes 3-3 in the conical depressions 3-2 of a plate 3-1 which constitutes one wall of the chamber 13. The spinning solution then flows across a space 3-7 between the plate 3-1 and the plate 3-4 and through the holes 3-6 in the conical depressions of the plate 3-4, each hole 3-3 being coaxial with a corresponding hole 3-6. A second spinning solution B is introduced into the spinneret housing 1 through the conduit 14 and flows through the passageway 15 between the conical inner surface of the housing 1 and the outer surface of the conical sleeve 2 the passageway 16 and the annular passageway 17 encircling the spacer ring 3-8 between the perforated plates 3-1 and 3-4. Solution B then flows through a circle of spaced-apart holes 3-10 in the spacer ring 3-8 into the spaces 3-9 between the plates 3-1 and 3-4. As a result composite streams of spinning solution each consisting of a " core " consisting of solution A and a " sheath consisting of solution B are caused to flow from all the holes 3-6 of the plate 3-4 through the chamber 18 towards the spinneret 9. The composite streams are contiguous but only intermingle at their mutual boundaries to a limited extent. The orifices 10 of the spinneret 9 are uniformly distributed over nearly tho whole of the spinneret face and are much more numerous than the holes 3-6 and 3-3 uniformly distributed over the plates 3-4 and 3-1. Each composite stream of spinning solutions A and B is therefore extruded through a number of spinneret orifices to form extruded streams of much smaller cross-section, some of which aro also composite, consisting of solutions A and B and the remainder homogeneous consisting of either solution A or solution B. The filaments may be stretched at a stretch ratio of 4 to 10 at a temperature of 70‹ to 180‹ C. This may be shrunk by heating them in a relaxed state at 80‹ to 250‹ C., preferably in steam at superatmospheric pressure and at a temperature of 110‹ to 150‹ C. The spinning solutions may be solutions of copolymers of a major proportion of acrylonitrile and minor proportions of vinyl acetate dissolved in dimethyl acetamide. The coagulating bath may be a mixture of dimethyl acetamide and water.