Multilobal fiber with projections on each lobe for carpet yarns

Described is a synthetic fiber for use in carpets, having a multilobal cross section, each lobe of said multilobal cross section having a first end and a second end and one side and an opposite side, the first end of each of said lobes being connected to the first end of the other lobes, the second end of each of said lobes radiating outwardly, each lobe having a plurality of projections, alternating along a contour of each lobe, each projection of each lobe having no direct counterpart on the opposite side of said lobe, the fiber having a modification ratio of from about 2.5 to about 7.

FIELD OF THE INVENTION 
The present invention is directed to a multilobal fiber with projections 
alternating along the contour of each lobe for use on carpet yarns. 
BACKGROUND OF THE INVENTION 
Multilobal, in particular trilobal fibers and filaments are known in the 
art and have been widely used, especially for carpet yarns. They 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 high luster and high 
sparkles. 
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 was to provide a spinnerette plate with a simple geometry, 
which is easy to produce and which allows the manufacture of these fibers. 
Still another object was to provide a carpet with subdued luster and good 
soil hiding properties. 
SUMMARY OF THE INVENTION 
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 a first end and a second end and one side and an 
opposite side, the first end of each of said lobes being connected to the 
first end of the other lobes, the second end of each of said lobes 
radiating outwardly, each lobe having a plurality of projections 
alternating along a contour of each lobe, each projection on one side of 
each lobe having no direct counterpart on the opposite side of said lobe, 
the fiber having a modification ratio of from about 2.5 to about 7.

DETAILED DESCRIPTION OF THE INVENTION 
The synthetic fibers of the present invention are generally prepared by 
melt spinning of a fiber forming polymer through a spinnerette. 
Suitable polymers for the production of the fibers of the present invention 
are all 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 11, nylon 12, copolymers thereof and mixtures 
thereof. 
Preferred polyamides are nylon 6 and nylon 6/6. A suitable polyester is 
polyethylene terephthalate. 
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 is fed into an extruder in form of chips or granules, 
(indirect) melted and directed via jacketed Dowtherm.RTM. (Dow Chemical, 
Midland, Mich.) heated polymer distribution lines to the spinning head. 
The polymer melt is then 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 and The angles 
between the lobes (1), (2) and (3) are from about 100.degree. to about 
140.degree., preferably about 120.degree.. 
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 are from about 2 to about 4, 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 in one spinnerette and is the rectangular or square shape. 
The tetralobal opening 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), (40) and (41) 
are from about 80.degree. to 100.degree., preferably about 90.degree.. 
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 are from about 2 to about 4, preferably 3. 
The dimensions of the different parts and their relationship to each other 
of the capillary 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 satisfy the following mathematic relationship: 
1.4.ltoreq.((1.73 D)/A).sup.1/2 .ltoreq.49; preferably 6.3.ltoreq.((1.73 
D)/A).ltoreq.30.3; 
0.5A.ltoreq.B.ltoreq.2A; and 0.5A.ltoreq.C.ltoreq.2A. 
The length in mm of A and B may be: 
0.04 mm.ltoreq.A.ltoreq.0.15 mm, and 
0.06 mm.ltoreq.D&lt;3 mm. 
The angle zeta between the lobes of the trilobal capillary are from about 
70.degree. to about 140.degree., preferably from about 110.degree. to 
about 130.degree.. 
The angle zeta between the lobes of the tetralobal capillary are from about 
70.degree. to about 140.degree., preferably from about 80.degree. to about 
100.degree.. 
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 shown, that the 
MR for the cross-section of the resulting fiber is from about 1.2 to about 
7, preferably from about 2.5 to about 5. 
Another preferred MR is from about 2.5 to about 7.0. Preferred is also a MR 
of from about 4.5 to about 7.0 and most preferred is from about 4.5 to 
about 5.0. 
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). 
Lobe (17) has a first end (20) and a second end (21), lobe (18) has a first 
end (20) and a second end (22) and a lobe (19) has a first end (20) and a 
second end (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 first end of each lobe is connected to the first end of the other 
lobes. The first end of the other lobes. The first end (20) of lobe (17) 
is connected to the first end (20) of lobe (18) and to the first end (20) 
of lobe (19). The second end of each lobe is radiating outwardly. The 
second end (21) of lobe (17), the second end (22) of lobe (18) and the 
second end (23) of lobe (19) are 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 projections alternate along the contour of each lobe, which means that 
the projections alternate successively from one side of the lobe to the 
opposite side of the lobe along the contour of the lobe, thereby having no 
direct counterpart on the opposite side of the lobe. Following in FIG. 2a 
the contour of lobe (17) from the first end (20) to the second end (21), 
projection (24) on the left side of lobe (17) alternates with projection 
(25) on the right side of lobe (17) which alternates with projection (26) 
on the left side of lobe (17). Projection (24) has no direct counterpart 
on the opposite side which is the right side of the lobe (17). Projection 
(25) has no direct counterpart on the opposite side which is the left side 
of lobe (17) and projection (26) has no direct counterpart of the opposite 
side which is the right side of lobe (17). The alternation of projections 
results in an unsymmetrical lobe (17). Following the contour of lobe (18) 
from the first end (20) to the second end (22), projection (27) on the 
right side of lobe (18) alternates with projection (28) on the left side, 
which alternates with projection (29) on the right side of lobe (18). None 
of the projections (27), (28) and (29) has a direct counterpart on the 
respective opposite side of lobe (18). The alternation of projections 
(27), (28) and (29) results in an unsymmetrical lobe (18). 
Following the contour of lobe (19) from the first end (20) to the second 
end (23), projection (30) on the right side of lobe (19) alternates with 
projection (31) on the left side of lobe (19) which alternates with 
projection (32) on the right side of lobe (19). None of the projections 
(30), (31) and (32) has a direct counterpart on the respective opposite 
side of lobe (19). The alternation of projections (30), (31) and (32) 
results in an unsymmetrical lobe (19). 
The tetralobal cross-section of the fiber according to FIG. 3a has four 
lobes (54), (55), (56) and (57) with two ends each (58), (59); (58), (60); 
(58) (61) and (58), (62). 
Lobe (54) has a first end (58) and a second end (59), lobe (55) has a first 
end (58) and a second end (60), lobe (56) has a first end (58) and a 
second end (61) and lobe (57) has a first end (58) and a second end (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 first end of each lobe is connected to the first end of the other 
lobes. The first end (58) of lobe (54) is connected to the first end (58) 
of lobe (55), to the first end (58) of lobe (56) and to the first end (58) 
of lobe (57). The second end of each lobe is radiating outwardly. The 
second end (59) of lobe (54), the second end (60) of lobe (55), the second 
end (61) of lobe (56) and the second end (62) of lobe (57) are radiating 
outwardly. 
The projections alternate along the contour of each lobe, which means that 
the projections alternate successively from one side of the lobe to the 
opposite side of the lobe along the contour of the lobe thereby having no 
direct counterpart on the opposite side of the lobe. Following in FIG. 3a 
the contour of lobe (54) from the first end (58) to the second end (59), 
projection (63) on the left side of lobe (59) alternates with projection 
(64) on the right side of lobe (59), which alternates with projection (65) 
on the left side of lobe (59). Projection (63) has no direct counterpart 
on the opposite side, which is the right side, projection (64) has no 
direct counterpart on the opposite side of lobe (59), which is the left 
side and projection (65) has no direct counterpart on the opposite side of 
lobe (59), which is the left side and projection (65) has no direct 
counterpart on the opposite side of lobe (59) which is the right side. The 
alternation of projections (63), (64) and (65) results in an unsymmetrical 
lobe (54). 
Following the contour of lobe (55) from the first end (58) to the second 
end (60), projection (66) on the top side alternates with projection (67) 
on the bottom side, which alternates with projection (68) on the top side 
of lobe (55). Projection (66) has no direct counterpart on the opposite 
side of lobe (55), which is the bottom side, projection (67) has no direct 
counterpart on the opposite side of lobe (55), which is the tops side and 
projection (68) has no direct counterpart on the opposite side of lobe 
(55), which is the bottom side. The alternation of projections (66), (67) 
and (68) results in an unsymmetrical lobe (55). 
Following the contour of lobe (56) from the first end (58) to the second 
end (61), projection (69) on the right side of lobe (56) alternates with 
projection (70) on the left side of lobe (56), which alternates with 
projection (71) on the right side of lobe (56). Projection (69) has no 
direct counterpart on the opposite side of lobe (56), which is the left 
side, projection (70) has no direct counterpart on the opposite side of 
lobe (56), which is the right side and projection (71) has no direct 
counterpart on the opposite side of lobe (56), which is the left side of 
lobe (56). The alternation of projections (69), (70) and (71) results in 
an unsymmetrical lobe (56). 
Following the contour of lobe (57) from the first end (58) to the second 
end (62), projection (72) on the bottom side of lobe (57) alternates with 
projection (73) on the top side of lobe (57) which alternates with 
projection (74) on the bottom side of lobe (57). Projection (72) has no 
direct counterpart on the opposite side of lobe (57), which is the top 
side. Projection (73) has no direct counterpart on the opposite side of 
lobe (57) which is the bottom side and projection (74) has no direct 
counterpart on the opposite side of lobe (57) which is the top side. The 
alternation of projections (72), (73) and (74) results in an unsymmetrical 
lobe (57). 
The lobes and diameters of the fiber of the present invention 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 satisfy the following relationship: 
1.2.ltoreq.R2/R1.ltoreq.7.0; preferably 2.5.ltoreq.R2/R1.ltoreq.5.0; 
1.1 L1.ltoreq.L2.ltoreq.5 L1; and 
L1.ltoreq.L2.ltoreq.R1. 
The spinnerette plate of the present invention has from about 5 to about 
300 openings in form of the capillaries, described above, preferably from 
about 10 to about 200. 
The extruded fibers are quenched for example with air in order to solidify 
the fibers. The fibers are then treated with a finish comprising a 
lubricating oil or mixture of oils and antistatic agents. The fibers are 
then combined to form a yarn bundle which is then wound on a suitable 
package. 
In a subsequent step, the yarn is drawn and texturized to form a bulked 
continuous filament (BCF) yarn suitable for tufting into carpets. A more 
preferred technique involves combining the extruded 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. 
Nylon fibers or filaments for the purpose of carpet manufacturing 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. 
From here, the BCF yarns can go through various processing steps well know 
to those skilled in the art. The fibers of this invention are particularly 
useful in the manufacture of carpets for floor covering applications. 
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-butadien 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.degree.. 
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.degree. C..+-.1.degree. 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 a 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 (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., 3/16 gauge cut pile 
constructions. The test carpets were compared with carpets made from 
production machines 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. 
TABLE 1 
______________________________________ 
yarns cross-section 
luster bulk 
______________________________________ 
1. control, 3.2 MR trilobal 
high medium-high 
two-step 
2. control, 3.2 MR trilobal 
high medium 
one step 
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.degree. C..+-.1.degree. 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 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. 
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