Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2003-09-25
2004-12-14
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S373000, C428S374000, C428S397000
Reexamination Certificate
active
06830809
ABSTRACT:
BACKGROUND
The present invention relates to splittable fibers, yarns or filaments, a method and a device for production of same.
Japanese Patent JP 07/026,454 and U.S. Pat. No. 5,899,785 describe splittable fibers, yarns, or filaments composed of at least two types polymers that tend to mutual phase separation Polyamides and polyesters are preferred.
In addition, European Patent EU 413 688, U.S. Pat. No. 5,562,930 and French Patent FR 2,647,815 describe methods and devices for producing splittable fibers, yarns, or filaments by a melt-spinning operation using two mutually incompatible polymers. The individual polymer melt streams are passed through distribution plates within a spinning head, so that each fiber coming out of the spinning head is made up of a plurality of elementary fibers of the particular polymer, which are arranged in alternation as viewed in the cross section of the fiber.
In particular the use of nylon 6.6 as one of the polymers is associated with a high cost for the starting material. This starting material also necessitates drying of the raw material, causes an electrostatic charge buildup during the spinning operation, and tends to yellow under the influence of light and heat. To achieve a very good color fastness, splittable fibers, yarns, or filaments produced using these starting materials must be dyed in a second step. Therefore there is a need for greatly reducing the amount of a polymer component, in particular the nylon component in the splittable fibers, yarns or filaments. However, the weight ratio of the polymers to one another may be varied only in a ratio of 30:70 to 70:30 with the known methods of producing them, since otherwise no separate polymer segments are obtained which makes splitting into microfibers or microfilaments impossible. In the wake of increasing demands regarding the flexibility of the production process for splittable fibers, yarns or filaments, there is a demand for those which are easily manufactured from the standpoint of the percentage composition of the polymers used and the denier of the elementary fibers contained in them and which are easily handled with regard to the changes required in the device.
SUMMARY OF THE INVENTION
The present invention provides splittable fibers, yarns, or filaments composed of at least two elementary fibers of a polymer A, every second elementary fiber being at least partially sheathed with polymer B so that the surface of the splittable yarn, fiber or filament has alternating sections of polymers A and B. The splittable fibers, yarns, or filaments according to the present invention permit a reduction in the amount of polymer B to 5 wt % to 25 wt % and thus make it possible to manufacture a product having extensive polymer uniformity. This yields advantages with regard to the mechanical properties, the recyclability and reduction in cost of materials. The splittable fibers, yarns, or filaments according to the present invention are suitable in particular for producing textile knits, woven or nonwoven fabrics.
According to the present invention, this object is achieved by splittable fibers, yarns, or filaments composed of at least two elementary fibers of a polymer A, every second elementary fiber being at least partially sheathed with polymer B so that the surface of the splittable yarn, fiber or filament has alternating sections of polymers A and B. The splittable fibers, yarns, or filaments according to the present invention permit a reduction in the amount of polymer B to 5 wt % to 25 wt % and thus make it possible to manufacture a product having extensive polymer uniformity. This yields advantages with regard to the mechanical properties, the recyclability and reduction in cost of materials. The splittable fibers, yarns, or filaments according to the present invention are suitable in particular for producing textile knits, woven or nonwoven fabrics.
The remaining elementary fibers are preferably sheathed with a pigment-dyed mass of polymer A, thus yielding colorfast products which show only minor changes in mechanical properties in comparison with the undyed products, because only 1 wt % to 15 wt %, preferably 2 wt % to 12 wt % of the elementary fibers is used as dyed sheath component (master batch).
They preferably have a round, oval, flat, tubular, or cross-shaped cross section so that they can meet different requirements.
The method according to the present invention for producing the splittable fibers, yarns, or filaments is implemented in such a manner that polymers A and B are introduced in molten form into a spinning head, where they are distributed in groups of elementary fibers, every second elementary fiber being sheathed with polymer B, combined in spinnerets to form the splittable fibers, yarns, or filaments and then drawn. The remaining elementary fibers are preferably sheathed with a pigment-dyed mass of polymer A. Then the groups of elementary fibers are pressed through spinnerets having round, oval, rectangular, ring-segment-shaped or cross-shaped outlet openings. The splittable fibers, yarns, or filaments are drawn in a pneumatic drawing operation. As alternative methods, the known mechanical drawing operations such as godet roller drawing are possible.
The splittable fibers, yarns, or filaments are produced in the device according to the present invention by a melt-spinning process using at least two mutually incompatible polymers by introducing them into a spinning head having a modular design composed of a first distribution plate having alternating distribution channels and openings to a second distribution plate, the alternating distribution channels of the second distribution plate forming an angle of approximately 90° to the distribution channels of the first distribution plate which has openings which supply polymer to a third distribution plate and represent the connection between the second distribution plate and a first outlet plate for the elementary fibers, the third distribution plate having subdistribution channels which extend over its entire thickness and the ends of which correspond to the number of outlet openings for elementary fibers, and then there follows a fourth distribution plate in which the subdistribution channels likewise extend over its entire thickness and permit at least a partial sheath to be formed on every second elementary fiber; this is followed by a second outlet plate in which the outlet openings for the elementary fibers are configured in groups in which the distances between the adjacent outlet openings for polymer A and for polymer A sheathed with B are approximately the same size and each is connected to a plate having spinnerets out of which the polymers are discharged and drawn to form splittable fibers, yarns, or filaments by a downstream drawing device.
By replacing the distribution plates and/or the outlet plates, it is easily possible to vary the spinning head having a modular design according to the present invention with regard to the number, i.e., quantity, of elementary fibers contained in the splittable fibers, yarns or filaments. In particular, it is possible to produce a fiber, filament or yarn that is almost uniform with regard to the polymers and is nevertheless splittable because polymer B which is incompatible with polymer A and is necessary for this purpose only surrounds every second elementary fiber of polymer A as a separator sheath. Due to asymmetrical sheathing, i.e., an irregular wall thickness of the sheathing or incomplete sheathing, a tendency to crimping of the split filaments may also be produced.
In addition, the subdistribution channels extending over the total thickness of the distribution plate ensure a good throughput of the polymer through the spinning head and simplified cleaning.
The device according to the present invention is advantageously one in which a fifth distribution plate is situated between the fourth distribution plate and the second outlet plate, its subdistribution channels extending uniformly over its total thickness and allowing a sheath to be formed on the remaining ele
Groten Robert
Leiner Helmut
Loecher Engelbert
Riboulet Georges
Carl Freudenberg KG
Davidson Davidson & Kappel LLC
Edwards N.
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