GB1350948A - Preparation of polyurethane filaments - Google Patents

Abstract

1350948 Polyurethane filaments TEIJIN Ltd 14 Oct 1971 [15 Oct 1970] 47930/71 Heading B5B [Also in Division D1] Coalesced spandex (Registered Trade Mark) multifilaments are made by extruding a melt or a solution of the spandex polymer through a spinneret having a plurality of orifices to form separate filaments and then passing these filaments into a first zone where they are given a false twist and so urged together by the rotating action of a fluid moving in a vortex. The twist extends back up the filaments to the print where they are sufficiently tacky to coalesce. After leaving the first vortical zone the filament bundle is then passed through a second vortical zone where a fluid, moving in the opposite direction to the fluid in the first zone, substantially removes the false twist. The pattern of vortical flow may be such that it helps to advance the movement of the filaments. In Fig. 1 the filaments are dry-spun into cell 2 where the solvent is evaporated off to give filaments Y. First jet-twister 5 is disposed below the spinning cell and the twist T imparted by it extends back into the cell, where the still tacky filaments are consequently coalesced. The twist is removed by second twister 6. The fluid used in the twisters may be either a liquid or a gas; preferably, water is used in the first zone and air in the second. Each zone may consist of more than one twister; the Examples describe the use of two in each zone. The polymers used in the exemplified processes are obtained by reaction between polytetramethylene glycol (molecular weight 2000) with 4,41-diphenylmethane diisocyanate or by reaction of this diisocyanate with a mixture of polytetramethylene glycol (molecular weight 1600) with polyethylene propylene adipate (molecular weight 1100).