ES293791A1 - Spinnerets - Google Patents

Abstract

A spinneret adapted for producing composite filaments comprises guide passages for separately guiding fibre-forming liquids, and relatively constricted flow passages disposed downstream of said guide passages and upstream of the spinneret orifices to limit the flow of said fibreforming liquids therethrough, wherein the relation between the pressure loss [alpha] g at said fibre-forming liquid guide passages and the pressure loss [alpha] s at said relatively constricted flow passages is selected to satisfy the formula Preferably, the relatively constricted flow passages are in the form of bores, the spinneret has more than 5000 orifices and the orifice density is higher than 1À2 orifices per sq. mm. In Fig. 1, fibre-forming liquids A and B are contained in reservoirs 6 and 7 (Fig. 2) and flow through guide ports 11 and 12 into guide passages 4 and 5, and hence through the relatively constricted flow passages or channels 2-1, 2-2, . . . 2-n and 3-1, 3-2, . . . 3-n. Orifices 1-1, 1-2, . . . 1-n are bored so that the orifice 1-1 corresponds to the channels 2-1 and 3-1, orifice 1-2 to the channels 2-2 and 3-2, and orifice 1-n to the channels 2-n and 3-n, so effecting the extrusion of the composite material. In Figs. 3 and 4, fibre-forming liquids A and B are contained in reservoirs 26 and 27, separated by a partition wall 34 in the distribution plate 30, and flow through guide ports 31 and 32 to guide passages 24 and 25 respectively, and hence through the narrow gaps 22 and 23 defined by the nozzle plate 28 and the projections 33 of the back-plate 29 to the orifices 21-1 . . . 21-n. In examples, component A is a copolymer comprising 91À5% acrylonitrile, 8% methyl acrylate and 0À5% methallyl sulphonate. Component B is a 6 : 4 mixture of said polymer and polyacrylonitrile The spinning solution is made by dissolving components A and B separately in 70% by weight nitric acid to a concentration of 27 gms. per 100 gms. solvent at - 5 C., and spinning into 33% by weight aqueous nitric acid at - 3 C. The coagulated filaments are washed and stretched to 7 times in hot water, and are thereafter treated with steam at 120 C. for 10 mins. to develop the crimp.