US 3650659 A
Spinning nozzle and the production of profiled filaments, threads, bristles or the like in the melt-spinning of a synthetic thermoplastic high molecular weight fiber-forming linear polymer by means of an H-shaped spinning orifice or opening wherein the crossbar flanks are parallel to and the inner flanks of the legbars are perpendicular to the axis of symmetry, the outer flanks of the legbars of the H-shaped orifice being at an angle of at least 5 DEG up to 45 DEG to the corresponding inner flanks.
Claims available in
Description (OCR text may contain errors)
United States Patent Stapp 1 SPINNING DIE  Inventor: Hans Stapp, Momlingen, Germany  Assignee: Akzona Incorporated, Asheville, NC.
 Filed: Mar. 31, 1970 211 App]. No.2 24,094
 Foreign Application Priority Data Apr. 5, 1969 Germany ..G 6913 818  US. Cl ..425/461, 264/177 F  ...D0ld 3/00, B28h 21/54  Field of Search ..264/177 F; 18/8 SS  References Cited UNITED STATES PATENTS 2,373,892 4/1945 Hickey ..264/177F 3,103,264 9/1963 Katan ..264/177F Shaw et a1. ..264/177 F Holden ..264/177 F FOREIGN PATENTS OR APPLICATIONS 1,170,552 11/1969 Great Britain ..264/177 F Primary Examiner-Jay H. Woo Atwrney.lohnston, Root, OKeefe, Keil, Thompson and Shurtleff 57] ABSTRACT Spinning nozzle and the production of profiled filaments, threads, bristles or the like in the melt-spinning of a synthetic thermoplastic high molecular weight fiber-forming linear polymer by means of an H-shaped spinning orifice or opening wherein the crossbar flanks are parallel to and the inner flanks of the legbars are perpendicular to the axis of symmetry, the outer flanks of the legbars of the H-shaped orifice being at an angle of at least 5 up to 45 to the corresponding inner flanks.
9 Claims, 1 Drawing Figure Patented March 21, 1972 3,650,659
INVEN'I'OR: H A N 5 STA P P 0%?? I ATT'YS SPINNING DIE For the production of profiled filaments, bristles and the like, a number of profiled spinning Openings have been proposed which are more or less similar to the shape of an H. Such H-profiled orifices or openings are sometimes desired as a double-T profile or, if the crossbar or crossmember is very strongly pronounced in comparison to the height of the profile, as I-profiles. 1
Thus, in FIG. 1 of Pat. No. 42,973 of the Office of Invention and Patent Matters of the German Democratic Republic, there is illustrated a shaping or forming nozzle for the continuous drawing of glass-fiber-reinforced synthetic resin elements in which the nozzle has a double-T profile. The crossbar flanks or edges of the profiled opening run parallel to the axis of symmetry which is parallel and midway between these flanks The inner flanks or edges formed by the legs or legbars projecting from the crossbar (designated by A and C) run perpendicular to the axis of symmetry. The outer flanks or edges of these projecting legs run parallel to the inner flanks, i.e., so as to be also perpendicular to the axis of symmetry through the crossbar.
The inner and outer leg flanks of the I-I-profiled opening shown in FIG. 11 of Pat. No. 32,870 of the Office of Invention and Patent Matters of the German Democratic Republic likewise run parallel to one another. At the points of intersection between the inner leg flanks and the crossbar blanks, bores or enlarged openings are provided in order to assure a better connection between the individual bands of the molten polymer, the bores providing-an increased feed of the melt at each point of intersection. A similar construction is followed in the spinning openings according to FIGS. 5 and 6 of Pat. No. 23,616 of the Office of Invention and Patent Matters of the German Democratic Republic.
French Pat. No. 1,358,092 likewise illustrates in FIG. 2 an H-shaped profiled opening in which the inner and outer flanks of the legbar projections run parallel. The crossbar flanks in this case extend laterally beyond the outer legbar flanks. The filament cross sections, achieved by means of a spinning nozzle profiled in this manner are multi-lobed and are strongly dependent on the viscosity of the melt. Even with a shortening of the crossbar flanks, the extruded filaments exhibit no great similarity to an I i-shape once they are spun and drawn. A similar conclusion can. be applied to the I-I-profile represented in FIG. 21 of Italian Pat. No. 269,130, as well as for the lprofiles of FIGS. l to V of US. Pat. No. 2,945,739, the use of which leads to bandor ribbonlike products without any precisely definedcross-sectional shape.
With the various known H,-, l or double T-types of profiles noted above, it is not possible to spin filaments, bands, bristles or the like from melts of synthetic fiber-forming linear polymers, such as polyamides, polyesters or the like, with adequate precision or with any assurance that the products will be uniformly I i-shaped in cross section.
One object of the present invention is to provide a spinning nozzle capable of yielding a profiled filamentary synthetic thermoplastic polymer product under otherwise conventional spinning conditions such that the profile or cross section of the spun product has a definite and uniform H-shape, i.e., with a clearly defined crossbar andfour projecting legs or legbars extending approximately perpendicular to the crossbar at either end thereof. Another object of the invention is to provide a spinning nozzle which can be used to achieve useful I-I- profiled filaments, bristles or the like of melt-spun and drawn fiber-forming linear polymers. In this respect, the invention has as an object the process of melt-spinning with the precisely shaped spinning orifice and the resulting product of this process. Otherv objects and advantages of the invention are explained more fully hereinafter.
In accordance with the invention, it has now been found that one can achieve a uniformly H-shaped filament of the usual fiber-forming thermoplastic polymers by employing in the spinning die a spinning nozzle with a flanked opening defining an H-shapedaextrusion orifice having a horizontal axis of symmetry through the crossbar of the H, said crossbar being formed by flanks of the opening running parallel to said axis of symmetry and each projecting legbar of the H being formed by an inner flank running perpendicular to said axis of symmetry and an outer flank positioned at an angle a to said inner flank of at least 5 and not more than 45, the smallest distance between said inner flank and outer flank of each legbar being approximately equal to the spacing between the parallel flanks of said crossbar.
The invention is more fully illustrated in connection with the accompanying drawing which provides a highly enlarged plan view of a cutaway portion of the face of a nozzle plate or die containing the H-shaped orifice or spinning opening therein.
The exact shape or configuration of the spinning nozzle of the invention is quite critical in achieving precisely H-shaped filamentary products, but otherwise it is possible to employ conventional melt-spinning and drawing apparatus and processing conditions which are well known in the art of synthetic filaments or similar extrusion products. This criticality arises due to previous difficulties experienced in attempting to produce relatively fine or thin profiled filaments which are subject to considerably distortion and reduction in size or shape during the spinning and drawing operations. Nevertheless,-in order to achieve a linearly oriented filamentary product, these distorting influences cannot be avoided, and the particular shape of the spinning orifice has been found to be of very special importance in achieving a uniformly H- shaped product.
All synthetic fiber-forming linear polymers are generally suitable as melt-spinnable substances for purposes of the invention, and especially desirable products are obtained when using conventional polyamides or nylons such as polyhexamethylene adipamide or polycaprolactam and also linear saturated polyesters such as polyethylene terephthalate. Other thermoplastic fiber-forming polymers such as polyacrylonitrile or polyolefins such as polypropylene may also be used. In spite of the fact that such polymers must be spun as a highly viscous melt, very uniform H-profiled filaments are obtained with a precisely defined cross section.
Referring now to the drawing, the spinning nozzle of the invention is contained in the usual nozzle plate or die through which the polymer melt is extruded. Each die normally is furnished with a larger number of spinning opening or orifices, depending on the size of the extruded filaments and capacity of the spinning head, but for convenience only one of such openings or orifices has been illustrated.
The H-shaped opening has four projecting legs or legbars as defined by the inner flanks or edges 1 and the outer flanks or edges 2 connected by the crossbar or crossmember of the H as defined by the parallel flanks or edges 3,3. The l-l-shaped opening has a horizontal axis of symmetry 4 extending through the middle of the crossbar and parallel to the crossbar flanks 3,3 so that the upper and lower portions of the H-shaped profile are substantially identical. It is likewise preferable to employ an orifice which is symmetrical about a vertical axis positioned midway between the oppositely disposed inner flanks 1 of the legbars.
The inner flanks 1 of the legbars are perpendicular to the crossbar flanks 3,3, i.e., so that the legbars intersect at a right angle to the crossbar. The outer flanks 2 of the legbars, on the other hand, must form the angle a with each corresponding inner flank 1 such that 5 a 45. In this respect, it will be noted that the outer flanks 2 of the pair of legbars on each side of the I-l-shaped opening will taper inwardly to intersect at the horizontal axis of symmetry and form an angle of intersection of 2a. The opening or orifice is finally closed or completed by the end flanks or edges 5 which are preferably in a position perpendicular to a line 6 bisecting the flank angle at, Le, a line at the angle 11/2 midway between the flanks l and 2. This position of flanks 5 favors the formation of a true H- profile of the melt-spun polymer. The smallest distance or spacing b between the inner flank l and outer flank 2 of each legbar should be approximately equal to the spacing a between the crossbar flanks 3,3. With this special arrangement or positioning of the inner and outer flanks with respect to each other in each legbar and with reference to the crossbar, it is possible to extend or impart the desired H-profile to the filamentary product as it is spun and drawn into a final product. Without this precise configuration of the spinning nozzle or orifice, a favorable effect is not achieved in the formation of an H-profiled product.
It should further be noted that the spacing or distance c between oppositely disposed inner flanks l of the legbars and also the length d of these inner flanks are of some importance in achieving an H-profiled structure. Thus, in order to make certain that the spinning nozzle forms a single definite H- profile structure rather than a number of relatively shapeless or nonuniform protruding bands or legs, while on the other hand also preventing the melt from fusing into a structure without any clear hollow space between the inner leg flanks and crossbar flanks, it is desirable to space the crossbar flanks 3 and 3' at a distance a of at least about 0.05 mm. and to also space the opposite inner leg flanks at a distance of at least about 0.15 mm. The spacing b always remains approximately equal to the spacing a. Finally, it has been recognized as being especially advantageous in accordance with the invention if the length d of the inner flanks 1 corresponds to about one to two times the spacing c between oppositely disposed inner flanks. Once these dimensions or limitations are exceeded, especially when extruding viscous molten polymers, it becomes considerably more difficult if not impossible to achieve a uniformly and precisely defined H-shaped structure in the final product.
In an especially preferred embodiment of the invention, the spinning nozzle or orifice is employed wherein the flank angle 0 lies between about and By working within these sizes of the flank angle, i.e., the angle between the inner flank l and outer flank 2 of each legbar, the resulting melt-spun structures have a profile or cross section which is most comparable to the letter H. Each leg of the H is clearly defined as an approximately perpendicular projection extending from the end of'the crossbar and blending smoothly and uniformly with the adjacent leg at the same end of the crossbar, all of the legs being substantially uniform in shape and size as bandlike protrusions or extensions on a uniform bandlike crossbar.
The term filaments" is employed herein as including threads, bristles or even ribbonlike profiled structures composed of a fiber-forming polymer, such products being especially useful in brushes or similar articles requiring relatively flexible but durable filamentary parts with fingerlike or leglike extensions.
ln referring to a horizontal or vertical" axis of symmetry of the spinning orifice and the melt-spun filaments formed thereby, it will be recognized that the orifice as well as the products can assume any position or spatial orientation and that these terms are merely used with reference to the normally observed position of the letter H, i.e., where the legs are vertical and the crossbar is horizontal. Thus, the orifices can be placed in any position in the nozzle plate of the spinning apparatus, and although filaments are usually continuously spun in a vertical direction, this is not essential for purposes of the invention.
Once the filaments are spun and solidified with conventional spinning equipment other than the special nozzle or extrusion orifice, they are preferably immediately drawn for molecular orientation in accordance with known principles. They can then be collected on a winding spool or cut to suitable lengths.
ln producing profiled filaments with the spinning nozzle of the invention, excellent results have been achieved with the orifice illustrated in the drawing, especially when melt a= 0.060 mm.
b= 0.060 mm.
d= 0.270 mm.
The resulting filamentary products exhibited a highly uniform H-profile over a long continuous spinning run and maintained this profile within normal spinning and drawing conditions.
In general, the spinning nozzle of the present invention is especially adapted to the production of profiled filaments having a relatively small overall dimension. In terms of individual filament size, the final profiled products are preferably those with a size of about 1.0 to 20.0 denier, preferably 2.0 to 5.0 denier, these sizes being a measure of the weight per unit length as is conventional in the art of synthetic filaments and textiles. Relatively thick or heavy filaments are especially useful as bristles for heavy duty brushes or brooms, while finer filaments can be used in softer brushes or may also be used in producing special textile products.
The invention is hereby claimed as follows:
1. In a spinning die for the production of at least one profiled melt-spun filament of a synthetic thermoplastic high molecular weight fiber-forming linear polymer, the improvement which comprises a spinning nozzle with a flanked opening defining an H-shaped extrusion orifice having a horizontal axis of symmetry through the crossbar of the H, said crossbar being formed by flanks of the opening running parallel to said axis of symmetry and each projecting legbar of the H being formed by an inner flank running perpendicular to said axis of symmetry and an outer flank positioned at an angle a to said inner flank of at least 5 and not more than 45, the smallest distance between said inner flank and outer flank of each legbar being approximately equal to the spacing between the parallel flanks of said cross bar.
2. A spinning die as claimed in claim 1 wherein said angle of the outer flank to the inner flank of each legbar lies between about 10 and 20.
3. A spinning die as claimed in claim 1 wherein the parallel flanks of the crossbar are spaced at a distance of more than 0.05 mm. and the oppositely disposed inner flanks of each pair oflegbars are spaced at a distance ofat least about 0.15 mm.
4. A spinning die as claimed in claim 1 wherein the end flank joining the inner and outer flanks of each legbar is perpendicular to a line bisecting the flank angle a.
5. A spinning die as claimed in claim 1 wherein the length of the inner flanks of said legbars is about one to two times the 7 distance between each pair of oppositely disposed inner flanks.
6. A spinning die as claimed in claim 2 wherein the parallel flanks of the cross bar are spaced at a distance of more than 0.05 mm. and the oppositely disposed inner flanks of each pair oflegbars are spaced at a distance ofat least about 0.15 mm.
7. A spinning die as claimed in claim 6 wherein the length of the inner flanks of said legbars is about one to two times the distance between each pair of oppositely disposed inner flanks.
8. A spinning die as claimed in claim 1 wherein the overall dimensions of said extrusion orifice are adapted to produce a melt-spun and drawn thermoplastic, fiber-forming linear polymer having a size ofabout 1.0 to 20.0 denier.
9. A spinning die as claimed in claim 2 wherein the overall dimensions of said extrusion orifice are adapted to produce a melt-spun and drawn thermoplastic, fiber-forming linear polymer having a size of about 2.0 to 5.0 denier.