GB994336A - Apparatus for the melt spinning of filaments - Google Patents

Abstract

Apparatus for making filaments from a plurality of sources of heat-fusible thermoplastic material comprises a plurality of melting units, each adapted to receive one such material and to provide a continuous melt thereof into a distributing system adapted to divide the molten stream from said melting unit into a plurality of sub-streams, a plurality of metering pumps, a plurality of spinneret assemblies, conduit means associated with said distributing system, metering pumps and spinneret assemblies whereby molten material from the distributing <PICT:0994336/C1/1> <PICT:0994336/C1/2> <PICT:0994336/C1/3> <PICT:0994336/C1/4> <PICT:0994336/C1/5> <PICT:0994336/C1/6> <PICT:0994336/C1/7> system for each melting unit is conveyed to a plurality of metering pumps and whereby each metering pump is connected to at least one spinneret assembly, the arrangement of said pumps and conduit means being such that each spinneret assembly receives a streamlet of molten material originating in each of said melting units, said conduit means being indidividually so shaped and proportioned as to give all the molten streamlets through correspondingly located conduits the same length of transit time, and heating means associated with said apparatus whereby to maintain the molten streamlets flowing from any particular melting unit at the same temperature at all mutually corresponding points along the path of flow of any of the materials from said melting units to the level of said plurality of spinneret <PICT:0994336/C1/8> <PICT:0994336/C1/9> assemblies. The method of supplying two melts to two spinnerets is shown diagrammatically in Fig. 4. Material A passes from melter 41 through conduit.43 to a distributer 45, where it subdivides into smaller equal streams and enters conduits 47, 49, 51 and 53 of approximately equal internal diameter and length. The stream passing through conduit 51 enters metering pump 61, where it is again subdivided and metered into passages 57 and 59 of approximately equal volume which discharge into the same relative position in spinneret assemblies 71 and 72 respectively. A second material B reaches spinneret assemblies 71 and 72 by a similar route passing through conduit 52, the other, polymer streams 47, 48, 49, 50, 53 and 54 being distributed through passages, pumps and spinnerets, not shown, the entire system of Fig. 4 supplying each of eight spinneret assemblies with metered streams of two different melts. The relative proportions of the materials being extruded may be controlled by adjusting the relative speeds of the metering pumps. Figs. 5 and 6 show a spinning assembly embodying the method of Fig. 4. The entire assembly is immersed in a constant temperature heat transfer medium 81 heated by electrical immersion heater 80, thermostatically controlled and enclosed in a body shell 10, on the upper surface of which are mounted the melters 41, 42, on the sides of which are mounted the metering pumps 61-68, the spinneret assemblies 71-78 being provided at the bottom. The melting grids 41 are heated by vapour 82 of the heat-exchange liquid supplied through pipe 39. Thus the thermal history or time-temperature curve of each streamlet is the same, provided the conduits are all of the same length and diameter. Where the distance to be reached by two streams is unequal, the pipe for the shorter path may be coiled at one or more points (Fig. 7), or the shorter pipe may be provided with a bulge (Fig. 8), so as to make the transit times for both streams equal. The apparatus may be modified to enable materials A and B to be melted at different temperatures while maintaining identical temperatures in all the pumps and spinneret assemblies, or the pumps shown may be replaced by distributers, and pumps fitted immediately above the spinneret assemblies. In the apparatus of Fig. 9, a two-stage distributer system is used including, in branch A, a distributer 85 having five outlet conduits, each of which is connected to a second distributer 87 having four outlets. Auxiliary pump 83 assures sufficient pressure for the moving melt. Branch B is similarly constructed, but each of branches A and B is enclosed in its own insulated housing 88, and each of these is individually heated by a vapour stream entering, e.g. at 97, and flowing out as condensate at 98. Pumps 61 and 62 and spinnerets 71 and 72 are enclosed in a single steel block 90, housed in insulated heating jacket 91. Conduits 57-60 of Fig. 4 are replaced by channels 93, 95, 96 and 98. The apparatus may be used to produce single-component yarns, or conjugate filaments of the sheath-core type (Fig. 2), or of the side-by-side type (Fig. 1), or a mixed yarn composed of filaments of a polymer A and a polymer B (Fig. 3). Specified materials include polyamides, e.g. poly-(e -caproamide) or polyhexamethylene alipamide, polyesters, e.g. polyethylene terephthalate or poly - (hexhydro - p - xylene terephthalate), polyolefins, e.g. polyethylene or polypropylene, and glass. Specification 533,307 and U.S.A. Specifications 2,386,173, 2,916,262 and 3,006,028 are referred to.