GB1014778A - Process and apparatus for producing branched artificial filaments - Google Patents

Abstract

1,014,778. Producing branched artificial filaments. ERNEST SCRAGG & SONS Ltd. Oct. 19, 1962 [Oct. 20, 1961], No. 39675/62. Divided out of 37642/61. Heading B5B. A " branched " filament consisting of a continuous main or trunk portion and short branch portions extending at intervals from the trunk and integral therewith is made by extruding a synthetic organic thermoplastic linear polymeric material in the form of a tube having at least one spiral fin and subsequently slitting the tube along a line which is at an angle to the line of the fin or fins. The thusformed filament may be drawn. The spiral fin may be in the form of a multi-start helix and may be located on the external surface of the tube. As shown in Figs. 1 and 2, an apparatus for producing branched filaments as above comprises an extrusion head 11 into which the filament-forming material is fed under pressure through the inlet 12 and urged by a ram 13 towards an outlet 14 provided with a coaxial rotated ring 15 having a number of radially extending slits 16 in the periphery of its inner surface. A cylindrical core 17 is mounted concentrically in the aperture 14 and extends through to the outer face of the ring 15. The diameter of the core 17 is slightly less than that of the aperture 14 and the internal diameter of the ring 15 so that the clearance between the core 17 and the ring 15 constitutes an annular extrusion orifice through which the polymeric material is extruded to form a thin-walled tube 18 (Fig. 3) having circumferential and radially extending spiral fins 19. The tube may be slit longitudinally as it emerges from the die or after it has passed through a bath of a liquid coolant into a number of narrow strips constituting the branched filaments. Alternatively the extruded tube may be slit once, spread out to form a flat sheet and then slit into narrow strips in a direction which is at an angle with the spiral fins.