GB833032A - Process for melt spinning synthetic filaments - Google Patents

Abstract

The process of Specification 661,999 (wherein a melt of filament-forming material is extruded through a multi-hole spinneret into a cooling stream of inert gas passing through a spinning cell to form a number of fine filaments, which are collected into a yarn by means of a convergence guide as soon as the filaments become non-tacky), is modified (the filaments being extruded vertically downwards) by the provision of one or more convergence guides which lie in a substantially horizontal plane below the spinneret face and in that the extruded filaments pass over the convergence guide in the form of a single bundle when only one convergence guide is provided, or in the form of two or more smaller bundles when two or more convergence guides are provided, the bundle or bundles of filaments then travelling from the convergence guide or guides to a further guide located above the wind-up means, the relative position of the convergence guide or guides and the guide above the wind-up means being such that the angle of deflection between the axis of each bundle of filaments travelling from the spinneret to each convergence guide, and the path of the yarn from the convergence guide or guides to the guide located above the wind-up means, is not less than 5 degrees or greater than 90 degrees, and is preferably 30 to 60 degrees, the deflection at each convergence guide (when there is more than one such guide) being substantially the same. The filament-contacting surfaces of the guide or guides are preferably of such a nature that the coefficient of friction between them and the filaments is low, e.g. the guides are made of ceramics with low friction surfaces or have surfaces of sand-blasted matt chromium-plated metal. The guides may be of tubular construction and cooled internally. They may be fixed or capable of rotation by the running filaments, e.g. they may be light-weight freely-rotatable rollers having fine circumferential grooves which separate the individual filaments as they pass over the roller and thereby cool them more easily and uniformly. The guides may be so positioned that the birefringence of the filaments leaving the guides is increased by about 20% over the birefringence when the guides are removed. Substantially equal fractions (preferably not exceeding one quarter of the total number of filaments coming from the spinneret) may each pass around a separate convergence guide, these guides being equally spaced around the periphery of a horizontal rigid ring located between the spinneret and the wind-up means, the filaments from each of these guides being brought together at a guide located a short distance above the wind-up means.