GB1006830A - Spinnerets for artificial filament manufacture - Google Patents

Abstract

1,006,830. Spinnerets. CELANESE CORPORATION OF AMERICA. Nov. 22, 1961 [Dec. 1, 1960], No. 41758/61. Heading B5B. A spinneret has one or more orifices each having its axis normal to the spinneret face and having, in axial cross section, a rectilinear portion, the walls of which run from the outlet face of the spinneret parallel to its axis and join another section having walls diverging toward the inlet face of the spinneret, the meeting angle of the diverging walls being less than 60 degrees for a distance from the inner end of the rectlinear portion of the orifice at least equal to 0À5 times the width of said portion and thereafter being at least 20 degrees larger for a distance of from 50 to 90% of the thickness of the spinneret face. The rectilinear portion is preferably cylindrical, but may alternatively be of square or triangular cross-section. A preferred form (Fig. 5), has two successive frusto-conical portions 15, 14 of which are joins, the inner end of the cylindrical portion 16 the widest part of the frusto-conical portions being towards the inlet face. In this case the meeting angle of each frusto-conical portion of the orifice is the angle which would be formed by continuing the walls of each frusto-conical portion until they meet. The diverging walls may also be hyperbolic in form (Fig. 6). In these cases the meeting angle at a given distance from the inner end of the rectilinear portion of the orifice is defined as the angle α formed by continuing tangents to the curved diverging walls, at points spaced the same distance from the inner end A of the rectilinear portion, until they meet. Preferably the meeting angle is 35 degrees or less, for a distance from the inner end of the rectilinear portion of the orifice to at least as far as a point spaced therefrom by a distance equal to the width of said rectilinear portion. Thus, as in Fig. 5, the inner end of the cylindrical portion 16 joins a frusto-conical portion 15 having a meeting angle of 35 degrees or less and the portion 15 joins a further frusto-conical portion 14 the meeting angle of which is from 50-60 degrees. The outlet face of the spinneret may be less than 1000 microns thick and the rectilinear portion of each orifice may have an area of less than 0À02 sq. mm. and a length of from 0À5-1À5 times its width. Such spinnerets are useful in the dry-spinning of cellulose triacetate from solvents consisting wholly or mainly of methylene chloride.