GB1304408A - - Google Patents

Abstract

1304408 Non-circular acrylic filaments JAPAN EXLAN CO Ltd 12 May 1970 [12 May 1969] 23031/70 Heading B5B An acrylic filament of non-circular crosssection is made by extruding a spinning solution of an acrylic polymer consisting of polyacrylonitrile or an acrylonitrile copolymer containing at least 70% by weight of acrylo. nitrile units and at least one other ethylenically unsaturated monomer copolymerizable with acrylonitrile through a spinneret orifice into air or into an inert gaseous medium which does not coagulate the spinning solution and then into a coagulating bath, said spinneret orifice comprising one rectangular slot or a plurality of rectangular slots connected to each other about a common point and extending radially therefrom. Fig. 2 shows suitable spinnerets. Desirably, the viscosity of the spinnirg solution at the time of the extrusion, the ratio of the major and minor axes of the rectangular slots, and the distance between the lower surface of the spinneret and the upper surface of the coagulating bath are selected within the three dimensional range having peripheries defined by the points a to u shown in Fig. 1. Conventional spinning solvents and coagulating baths are used; the use of sodium thiocyanate solutions is exemplified. In Fig. 3, the spinning solution is extruded through spinneret 1, having orifices as in Fig. 2, and passes through an inert gas or air gap into coagulating bath 3. The gel filament 10 is removed by godet roller 4, washed with water at rollers 5, subjected to primary thermal stretching in bath 6 and dried on drying roller 7. The filament so obtained is subjected to secondary stretching in chamber 8, into which steam is introduced, and heat-treated under dry heat with roller 9. Fig. 4 shows a flowing bath type spinning system, which enables spinning velocity to be increased, facilitating the production of filaments of low denier. Coagulating solution is fed through feed pipe 14, near the bottom of the jacket 15, so that the level of the coagulating bath remains constant. Spinning solution extruded through spinneret 1 passes through the inert gas or air gap into the funnel 12 of the coagulating bath and the formed filament is moved downwardly together with the coagulating solution through the tube 13 and into the coagulating tank 16. The filament 19 is removed from the tank by godet roller 17, and is then washed and treated as above. Excess coagulant is removed through discharge pipe 18 and recovered.