Spinning process and multifilament yarn

Abstract

 A multifilament yarn wherein the conjugate filaments may be split into sub-filaments having substantially different deniers.
A preferred spinneret (22) has horse-shoe shaped slots (20) with recessed web regions (24). Two dissimilar polymers are fed as a sheath-core conjugate stream with polymer interface (26).

Description

[0001] The invention relates to the art of spinning conjugate filaments yielding fabrics with improved hand.

[0002] It is known to produce conjugate filaments splittable into sub-filaments, as typified by Hayashi U.S. Patent 4,051,287, the disclosure of which is incorporated herein by reference. As disclosed therein, alternating segments of polyamide and polyester are spun in side-by-side temporarily adhering relationship to form a hollow filament splittable into polyamide and polyester sub-filaments of equal deniers.

[0003] According to the invention, a more natural hand in fabrics made from such filaments or sub-filaments is achieved when the sub-filaments have substantially different deniers.

[0004] According to a first aspect of the invention there is provided a spinning process, comprising generating a plurality of molten streams from a spinneret, each of the streams being formed from axially extending continuous segments of dissimilar polymers arranged alternately in side-by-side temporarily adhering relationship; quenching the streams to form filaments; and withdrawing the filaments from the streams, the streams being selected such that some sub-filaments split from a first of the filaments have substantially different deniers than other sub-filaments split from a second of the filaments.

[0005] According to another aspect of the invention, at least one of the filaments is splittable into a different number of sub-filaments than is another of the filaments.

[0006] According to another aspect of the invention, there is provided a multi-filament yarn comprising a plurality of filaments splittable into sub-filaments of at least first and second polymers, some sub-filaments split from a first of the filaments having substantially different deniers than other sub-filaments split from a second of the filaments.

[0007] According to another aspect of the invention, the first and the second of the filaments are splittable into different numbers of sub-filaments.

[0008] According to another aspect of the invention, some sub-filaments have deniers at least 50% larger than the other sub-filaments.

[0009] According to another aspect of the invention, some sub-filaments have deniers at least 100% larger than the other sub-filaments.

[0010] Other aspects will in part appear hereinafter and will in part be obvious from the following detailed description taken in connection with the accompanying drawing, wherein:

FIGURE 1 is a bottom plan view of a spinneret for making yarns according to the invention; and

FIGURE 2 is a fragmentary perspective view of an exemplary filament according to the invention.

[0011] As shown in FIGURE 1, the preferred spinneret construction illustrated includes several groups of generally arched or horseshoe-shaped slots 20 in spinneret blank 22, those slots 20 in each group being arranged symmetrically about a central point for that group with the open end of the horseshoe shapes facing inwardly. The several slots 20 in each group constitute a combined orifice for spinning a single filament. Slots 20 extend entirely through blank 22 except for recessed web 24 at the apex of each slot 20, the webs 24 and the lands between adjacent ends of slots 20 providing support to retain the material in the center of the combined orifice.

[0012] The two dissimilar polymers are fed to the combined orifices as sheath-core supply streams, with dotted circles 26 representing the interfaces between the two polymers. Adjacent ends of adjacent slots 20 are sufficiently close that the streams issuing therefrom unite just below the spinneret. The molten spun streams are thus hollow structures composed of alternating axially extending segments of the two polymers. Surface tension and other effects tend to make the molten streams approach hollow circular cross-sections prior to solidification, as shown in FIGURE 2, which illustrates a filament formed by a combined orifice composed of eight slots 20. If the polymers differ in melt viscosity, it is ordinarily preferable to provide the polymer having the lower viscosity as the core of the stream approaching each combined orifice.

[0013] The various slot dimensions in the directions parallel to and transverse to the direction of polymer flow are selected to control the relative deniers of the combined filaments spun from the various combined orifices. Most conveniently, the various slots may be identical in their transverse dimensions, with their lengths parallel to the direction of polymer flow selected to control the relative combined filament deniers. Since the relative combined filament deniers are thus controllable, and since the number of segments or sub-filaments for each combined filament is selected by spinneret design, a very wide range of deniers in the resulting sub-filaments split from the combined filaments is possible.

[0014] Exemplary dissimilar polymers are poly(ethylene terephthalate) and nylon 66. By "dissimilar" is meant that the polymeric components in the solidified filaments can be readily separated from one another into sub-filaments.

[0015] The hand of fabrics made from yarns according to the invention can be varied widely by selection of substantially different deniers for the sub-filaments. Marked improvement in hand occurs when some sub-filaments have deniers at least 50% larger than others of the sub-filaments, with better results when the difference is at least 100%.

[0016] Yarns according to the invention can be produced by spinning followed by drawing, either in a coupled process or as separate operations, or can be produced by spinning at speeds sufficiently high as to eliminate the need for a drawing operation.

Claims

1. A spinning process, comprising:

a. generating a plurality of molten streams from a spinneret, each of said streams being formed from axially extending continuous segments of dissimilar polymers arranged alternately in side-by-side temporarily adhering relationship;

b. quenching said streams to form filaments; and

c. withdrawing said filaments from said streams, said streams being selected such that some sub-filaments split from a first of said filaments have substantially different deniers than other sub-filaments split from a second of said filaments.

2. The process defined in claim 1, wherein at least one of said filaments is splittable into a different number of sub-filaments than is another of said filaments.

3. The process defined in claim 1, wherein said some sub-filaments have deniers at least 50% larger than said other sub-filaments.

4. The process defined in claim 1, wherein said some sub-filaments have deniers at least 100% larger than said other sub-filaments.

5. A multi-filament yarn comprising a plurality of filaments splittable into sub-filaments of at least first and second polymers, some sub-filaments split from a first of said filaments having substantially different deniers than other sub-filaments split from a second of said filaments.

6. The yarn defined in claim 4, wherein said first and said second of said filaments are splittable into different numbers of sub-filaments.

7. The yarn defined in claim 5, wherein said some sub-filaments have deniers at least 50% larger than said other sub-filaments.

8. The yarn defined in claim 5, wherein said some sub-filaments have deniers at least 100% larger than said other sub-filaments.

Drawing