A multilobal fiber with projections on each lobe for carpet yarns and spinnerette plate for their manufacture

Abstract: Described is a synthetic fiber for use in carpets, having a multilobal cross section, each lobe of said multilobal cross section having two ends, one end being connected to the other lobes, the other end of said lobes radiating outwardly, each lobe having a plurality of projections, alternating along the contour of each lobe. Described is a spinnerette plate for the manufacture of multilobal fibers comprising at least one opening having a plurality of lobes, each lobe having two ends, one end being connected to the other lobes, the other end of each said lobes radiating outwardly and each lobe having a plurality of projections alternating along the contour of each lobe.

Description: The present invention is directed to a multilobal fiber with projections alternating along the contour of each lobe for use on carpet yarns. Another embodiment of the present invention is directed to a spinnerette plate for the manufacture of a multilobal fiber with at least one opening having a plurality of lobes radiating outwardly and each lobe having a plurality of projections alternating along the contour of each lobe, such spinnerette being suitable for the manufacture of the fiber according to the present invention. Multilobal, in particular trilobal fibers and filaments and spinnerettes for their manufacture are known in the art and have been widely used, especially for carpet yarns. Such fibers show superior properties in bulk and covering power over fibers having round cross sections. U.S. Pat. No. 3,109,195 discloses filaments having multi-lobed transverse cross-sections. U.S. Pat. No. 3,194,002 discloses a multifilament yarn having a non-regular Y-shaped cross section. U.S. Pat. No. 4,648,830 discloses a spinnerette for producing hollow trilobal cross-section filaments. U.S. Pat. No. 5,108,838 discloses the trilobal and tetralobal filaments exhibiting low glitter and high bulk. The filaments having substantial convex curves. Disadvantage of the filaments of the prior art are the high luster and high sparkles. One object of the present invention was to provide a fiber with a simple cross section, which exhibits good bulk, subdued luster, uneven surface, and good soil hiding properties. Another object of the present invention was to provide a spinnerette plate with a simple geometry, which is easy to produce and which allows the manufacture of a fiber which exhibits good bulk, subdued luster, uneven surface and good soil hiding properties. Still another object was to provide a carpet with subdued luster and good soil hiding properties. The objects of the present invention could be achieved by a synthetic fiber, having a multilobal cross section, each lobe of said multilobal cross section having two ends, one end being connected to the other lobes, the other end of said lobes radiating outwardly, each lobe having a plurality or projections, alternating along the contour of each lobe and by a spinnerette plate for the manufacture of such fibers comprising at least one opening having a plurality of lobes, each lobe having two ends, one end being connected to the other end of each of said lobes radiating outwardly and each lobe having a plurality of projections alternating along the contour of each lobe. Figure 1 is a front view of a trilobal spinnerette capillary of the prior art. Figure 1a is a cross-sectional view of a fiber spun by a spinnerette shown in Fig. 1. Figure 2 is a front view of a trilobal spinnerette capillary of the present invention comprising three alternating projections along the contour of each lobe. These projections may be of a specific shape such as a rectangular, square, triangular or round shape. Figure 2a is a cross-sectional view of a fiber of the present invention spun by a spinnerette shown in Fig. 2. Figure 3 is a front view of a tetralobal spinnerette capillary of the present invention comprising three alternating projections along the contour of each lobe. Figure 3a is a cross-sectional view of a fiber of the present invention spun by a spinnerette shown in Fig. 3. The synthetic fibers of the present invention are generally prepared by melt spinning of a fiber forming polymer through a spinnerette of the present invention. Suitable polymers for the production of the fibers of the present invention are all fiber forming thermoplastic materials especially polyamides, polyesters, and polyolefins. Suitable polyamides are nylon 6, nylon 6/6, nylon 6/9, nylon 6/10, nylon 6/12, nylon 12, copolymers thereof and mixtures thereof. Preferred polyamides are nylon 6 and nylon 6/6. Preferred polyesters are polyalkyleneterephthalates and polyalkylenenaphthalates, a particularly preferred polyester is polyethylene terephthalate. Suitable polyolefins are polymers of C 2 -C 10α -olefins, in particular polyethylene, polypropylene and their copolymers. Various additives may be added to the respective polymer. These include, but are not limited to, lubricants, nucleating agents, antioxidants, ultraviolet light stabilizers, pigments, dyes, antistatic agents, soil resists, stain resists, antimicrobial agents, and flame retardants. The polymer usually is fed into an extruder in form of chips or granules, (indirect) melted and directed via jacketed heated polymer distribution lines (Dowtherm®, Dow Chemical, Midland Michigan) to the spinning head. The polymer melt is then usually metered by a high efficiency gear pump to spin pack assembly and extruded through a spinnerette with capillaries described below. The spinnerette plate of the present invention has in general at least one multilobal opening, like tris-, tetra-, penta- or hexalobal capillary, preferably tri- and tetralobal capillary. The capillary of the spinnerette plate of the present invention is described with reference to Fig. 2 for a trilobal opening: Lobes (1), (2) and (3) have two ends each, (4), (5); (4), (6) and (4), (7). On one end (4) the lobes are connected to each other end. The angles between the lobes (1), (2) and (3) are from about 100° to about 140°, preferably about 120°. The projections (8), (9), (10); (11, (12), (13); (14), (15) and (16) alternate along the contour of each lobe. The number of projections per lobe is usually in the range of from 2 to 6, preferably from 2 to 4 and particularly preferably 3. The projections may be different in each lobe and may have different types of shapes like rectangular, square, triangular or round. Preferred is one type of shape, preferably rectangular or square shape in the spinnerette. The tetralobal opening (capillary) in the spinnerette plate according to Fig. 3 has four lobes (33), (34), (35 and (36). On one end (37) the lobes are connected to each other, the other end of each lobe (38), (39), (40) and (41) radiating outwardly. The angles between the lobes (38), (39), (40) and (41) are from about 80° to 100°, preferably about 90°. The projections (42), (43), (44); (45), (46), (47); (48), (49), (50) and (51), (52) and (53) alternate along the contour of each lobe. The number of projections is usually in the range of from 2 to 6, preferably of from 2 to 4 and particularly preferred 3. The dimensions of the different parts and their relationship to each other of the capillary of the spinnerette plate of the present invention are as follows: A is the width of the lobe B is the width of the projection C is the length of the projection D is the length of the lobe The dimensions A, B, C and D usually satisfy the following mathematic relationships: 1.4 ≤ ((1.73 D) / A) 1/2 ≤ 49; preferably 6.3 ≤ ((1.73 D) / A) ≤ 30.3; 0.5A ≤ B ≤ 2A; and 0.5A ≤ C ≤ 2A. The length in mm of A and B usually satisfies the following relationship: 0.04 mm ≤ A ≤ 0.15 mm, preferably 0.06 mm ≤ A ≤ 0.12 mm and 0.06 mm ≤ D ≤ 3 mm, preferably 0.08 mm ≤ D ≤ 2.7 mm. The angle zeta between the lobes of the trilobal capillary is usually from 70° to 140°, preferably from 110 to 130°, most preferred 115 to 125°, in particular 120°. The angle zeta between the lobes of the tetralobal capillary is usually from 70° to 140°, preferably form 80° to 100° most preferred 85 to 95°, in particular 90°. The disclosed dimensions are dependent from for example polymer type, spinning temperature, melt viscosity of the polymer and quench medium. The desired "modification ratio" for the resulting filaments is also an important factor. By the term "modification ratio" (MR) it is meant the ratio of the radius of a circle which circumscribes the filament cross-section to the radius of the largest circle which can be inscribed within the filament cross-section. The two circles are shown as dotted lines in Fig. 2a and Fig. 3a. The dimensions in the capillaries of the spinnerette plate are preferably such, that the MR for the cross-section of the resulting fiber is from 1.2 to 7, preferably from 2.5 to 5. The respective polymer is extruded through the capillary of the spinnerette plate described in Fig. 2 or Fig. 3 to form a fiber having a cross-section described in Fig. 2a or Fig. 3a. The trilobal cross-section of the fiber according to Fig. 2a has three lobes (17), (18) and (19) with two ends each (20), (21); (20), (22); and (20), (23). On one end (20) the lobes are connected to each other, the other end of each lobe (21), (22) and (23) radiating outwardly. The projections (24), (25), (26); (27), (28), (29) and (30), (31), (32) alternate along the contour of each lobe. According to the shape of the projections in the spinnerette, the projections ) of the cross section of the fiber differ slightly. The tetra lobal cross-section of the fiber according to Fig. 3(a) has four lobes (54), (55), (56) and (57) with two ends each (58), (59); (58), (60); (58), (61) and (58), (62). On one end (58) the lobes are connected to each other and radiating outwardly to the other end of each lobe (59), (60), (61) and (62). The projections (63), (64), (65); (66), (67), (68); (69), (70), (71); and (72), (73), (74) alternate along the contour of each lobe. According to the shape of the projections in the spinnerette, the projections of the cross section of the fiber differ slightly. The lobes and diameters of the fiber of the present invention usually satisfy the following mathematical relationships: L1 is the narrowest width of the lobe; L2 is the widest width of the lobe; R1 is the inner fiber diameter; and R2 is the outer fiber diameter The dimensions L1, L2, R1 and R2 preferably satisfy the following relationship: 1.2 ≤ R2/R1 ≤ 7.0 more preferably 2.5 ≤ R2/R1 ≤ 5.0; 1.1 L1 ≤ L2 ≤ 5 L1 more preferably 1.3 ≤ 1 ≤ L2 ≤ 4L1, and L1 ≤ L2 ≤ R1. The spinnerette plate of the present invention has preferably from 5 to 300 openings in form of the capillaries, described above, preferably from 10 to 200 openings. After being extruded, the fibers are usually quenched for example with air in order to solidify the fibers, thereafter treated with a finish comprising a lubricating oil or mixture of soils and antistatic agents and then combined to form a yarn bundle which is then wound on a suitable package. In a subsequent step, the yarn can be drawn and texturized to form a bulked continuous filament (BCF) yarn suitable for tufting into carpets. A more preferred technique involves combining the extruder or as-spun filaments into a yarn, then drawing, texturizing and winding a package, all in a single step. This one-step method of making BCF is referred to in the trade as spin-draw-texturing. From here, the BCF yarns can go through various processing steps well known to those skilled in the art. The fibers of this invention are particularly useful in the manufacture of carpets for floor covering applications. Nylon fibers or filaments for the purpose of carpet manufacturing generally have deniers (denier - weight in grams of a single filament with a length of 9000 meters) in the range of about 3 to 75 denier/filament (dpf). A more preferred range for carpet fibers is from about 6 to 35 dpf. To produce carpets for floor covering applications, the BCF yarns are generally tufted into a pliable primary backing. Primary backing materials are generally selected from the group comprising conventional woven jute, woven polypropylene, cellulosic nonwovens and nonwovens of nylon, polyester, and polypropylene. The primary backing is then coated with a suitable latex material such as conventional styrene-butadiene latex, vinylidene chloride polymer, or vinyl chloride-vinylidene chloride copolymers. It is common practice to use fillers such as calcium carbonate to reduce latex costs. The final step is to apply a secondary backing, generally a woven jute or woven synthetic such as polypropylene. Examples 1 Nylon 6 filaments were spun using three of the modified cross-section spinnerettes. Each spinnerette had 12 capillaries of a specific design of such as that in Fig. 2A with the following dimensions: A = 0.08 mm B = 0.08 mm C = 0.08 mm D = 0.96 mm The angle zeta was 120°. The nylon 6 polymer (rel. viscosity RV - 2.7) used was a bright polymer and did not contain any delusterant. The polymer temperature was controlled at the pump block at about 265°C ± 1° and the spinning throughput was 66.75 g/min per spinnerette. The molten fibers were quenched in a chimney using 80 ft/min air for cooling the fibers. The filaments were pulled by feed roll rotating at a surface speed of 865 m/min through the quench zone and coated with a lubricant for drawing and crimping. The yarns were combined and drawn at 1600 m/min and crimped by a process similar to that described in U.S. Pat. No. 4,095,317 to form 1100 denier 60 filament yarn. The spun, drawn, and crimped yarns (BCF) were cable-twisted to a 3.5 turns per inch (1.4 turns per cm) (tpi) on a cable twister and heat-set on a Superba heat-setting machine at the standard conditions for nylon 6 BCF yarns. The test yarns were then tufted into 32 oz/sq. yd. (1081.6 g/m 2 ), 3/16 gauge (4.76 mm) cut pile constructions. The test carpets were compared with carpets made from production running nylon 6 BCF carpet yarns in a one-step and two-step process. The carpet properties were assessed by a panel of experts and the results are shown in table 1. yarns cross-section luster bulk 1. control, two-step 3.2 MR trilobal high medium-high 2. control, one step 3.2 MR trilobal high medium 3. Example 1 5.0 MR trilobal low medium-high MR: modification ratio Example 2 Nylon 6 (RV= 2.7) filaments were spun using three of the modified cross-section spinnerettes using the above-described process for the main extruder and with a sidearm extruder attached to the main extruder. The sidearm extruder was fed with a nylon 6 polymer blended with color concentrates to produce yarns of red, blue and green colors. The polymer temperature was controlled at the pumpblock at about 265°C ± 1° and the spinning throughput was 55.0 g/min per spinnerette. The filaments were drawn on a drawtwister at a draw ratio of 3:10 to a final denier of 220/12 filament and combined on an air texturing machine. A yarn with a denier of 200/35 filament was used as the core yarn and the green, red and blue yarns were used as accent yarns and textured to give a space-dye look in carpet. The carpets were 25 oz (708.75 g) level loop and were compared to carpets made by the same process using the same blends of colors. The comparative carpets were using a trilobal cross-section yarn drawn to a final denier of 220/14 filament. Results are shown in table 2. yarns cross-section texture 1. Control round fair 2. Control 2.6 MR trilobal good 3. Example 2 4.6 MR trilobal good MR: modification ratio

Claims: A synthetic fiber, having a multilobal cross section, each lobe of said multilobal cross section having one end and another end, one end being connected to an other lobe, the other end of each of said lobes radiating outwardly, each lobe having a plurality of projections, alternating along a contour of each lobe, each projection radiating outwardly from a central portion of each lobe and having no counterpart on the opposite side of said lobe at said central portion. The fiber according to claim 1, wherein the dimensions of said fiber and said lobes satisfy the following mathematic relationship: 1.2 ≤ R2/R1 ≤ 7.0 1.1 L1 ≤ L2 ≤ 5 L1; and L1 ≤ L2 ≤ R1; wherein L1 is the narrowest width of the lobe; L2 is the widest width of the lobe; R1 is the inner fiber diameter; and R2 is the outer fiber diameter The fiber according to claim 1 or 2, wherein the cross section is trilobal or tetralobal. The fiber according to any of the preceding claims having three projections per lobe, alternating along the contour of each lobe. The fiber according to any of the preceding claims, wherein the projections are rectangular, square, triangular and/or round shaped. The fiber according to any of the preceding claims, comprising a polymer selected form the group consisting of polyamide, polyester and polyolefin. The fiber according to claim 1, having a ratio of the radius of a circle which circumscribes the filament cross-section to the ratius of the largest circle which can be inscribed within the filament cross-section (modification ratio) of about 1.2 to 7. A carpet comprising a fiber according to any of the preceding claims. A spinnerette plate for the manufacture of multilobal fibers comprising at least one opening having a plurality of lobes, each lobe having two ends, one end being connected to the other lobes, the other end of each of said lobes radiating outwardly and each lobe having a plurality of projections alternating along the contour of each lobe, each projection radiating outwardly from a central portion of each lobe and having no counterpart on the opposite side of said lobe at said central portion. The spinnerette plate according to claim 9, wherein said opening has three or four lobes. The spinnerette plate according to claim 9 or 10, wherein the dimensions of said capillary opening satisfy the following mathematical relationship: 1.4 ≤ ((1.73 D) / A) 1/2 ≤ 49; 0.5A ≤ B ≤ 2A; 0.5A ≤ C ≤ 2A; wherein A is the width of the lobe; B is the width of the projection; C is the length of the projection; and D is the length of the lobe. The spinnerette plate according to any of claims 9 to 11, wherein an angle zeta between two respective lobes is from about 70° to about 140°. The spinnerette plate according to any of the claims 9 to 12, having three projections per lobe alternating along the contour of each lobe. The spinnerette plate according to any of the claims 9 to 13, wherein the projections are rectangular, square, triangular and/or round shaped.

Inventors: WARREN ELBERT K, WARREN, ELBERT K.
Applicants: BASF CORP, BASF CORPORATION
Application year: 1993
Main classification: D01D5
IPC codes: D01D5, D01F6, D01D4, D02G3