GB1222717A - Process and apparatus for melt spinning thermoplastic yarn - Google Patents

Abstract

1,222,717. Melt-spun fibres with improved uniformity. FMC CORP. 19 Sept., 1968 [4 Jan., 1968], No. 44630/68. Heading B5B. Melt-spun fibres and filaments are made by extruding a plurality of molten synthetic polymer filaments from a multi-orifice, preferably circular, spinneret assembly downwardly into a cooling gaseous medium, preferably directed radially inwardly and horizontally across the filaments over an arc of about 180 degrees, thus substantially solidifying the filaments; directing a cushion of a steady current of a gaseous medium against the substantially solidified filaments, the current emanating from a relatively narrow source positioned in the filaments' path, substantially perpendicular thereto, and having sufficient force to prevent contact of the filaments with the current source; and forwarding the filaments, the path of which may change direction at the gaseous cushion. At least one other cushion of gas may be directed against the filaments at a position no farther upstream of the filament path than the first-mentioned gaseous cushion. The front wall of the preferred enclosure for the cooling gaseous medium, which has inlet means for a supply of the cooling gas, has a longitudinally concave foraminous surface extending into the enclosure, the other walls having edges substantially coextensive with the concave surface, whereby the gaseous cooling means co-operates with the spinneret assembly and partially surrounds the extruded molten filaments. Filament steadying means are provided which may comprise a closed tube having means to receive pressurized gas, preferably a straight metallic tube closed at one end and adapted to receive pressurized gas at the other end, at least a portion of which comprises a microporous section from which the cushion of gas emanates. Figs. 1, 2 and 3 (2 and 3 not shown) show schematic side views of three embodiments of the invention, Fig. 4 (not shown) shows quenching apparatus and Figs. 5 and 6 (Fig. 6, not shown) show two suitable gas cushion supply means. Polypropylene filaments are exemplified; suitable polymers are polyester resins (e.g. polyethylene terephthalate) isotactic polypropylene resin, polyamide resin (e.g. polyhexamethylene adipamide and polycaprolactam), polyvinyl chloride resin, polycarbonate resin, and polyphenylene oxide resins, as well as mixtures of these resins.