[0001] The invention relates to novel processes for making from a yarn consisting of essentially
continuous filaments a yarn simulating one spun from staple fibers.
[0002] It is known to treat certain types of continuous filament yarns by various processes
to produce yarns which simulate to some degree yarns spun from staple fibers. Typical
prior art processes which break the filaments so as to leave the broken ends protruding
from the yarn bundle are Heinrich U.S. patent 3,857,232; Cardinal U.S. patent 3,857,233;
and Yasuzuka U.S. patent 3,967,441, the disclosures of which are incorporated herein
by reference. Fairley British Specification 971,573 discloses a similar process -
wherein the broken filament ends are stated to be entangled within the yarn bundle,
rather than protruding from the bundle. In each of these and other known processes
wherein filaments are broken, the breakable filaments are substantially uniform from
end to end. That is, there is made no provision for preferred locations of breakage
along the breakable filaments, and hence, less control of breakage than might be desired.
[0003] According to the present invention, this and other difficulties in the prior art
are avoided by using a feed yarn having preferred locations for breakage along the
breakable filaments.
[0004] According to a first major aspect of the invention, there is provided a process for
making a spun-like yarn comprising drawing a feed yarn, the feed yarn comprising a
plurality of continuous filaments, each of this plurality of filaments having a cross-sectional
area which varies repetitively from small values in thin regions to large values in
thick regions along its length, the large values being at least 25% greater than the
small values, the thick and thin regions being out of phase from filament to filament
along the length of the yarn, the filaments being repeatedly broken to provide broken
ends primarily in the thin regions, the broken ends protruding from the bundle.
[0005] According to another aspect of the invention, the yarn is false-twisted while being
drawn.
[0006] According to another aspect of the invention, the yarn is false-twisted and heat-set
while being drawn.
[0007] According to another aspect of the invention, the average distance between consecutive
thick portions along each of the filaments is between 2 centimeters and 20 meters,
and preferably between 20 centimeters and 5 meters.
[0008] According to another aspect of the invention, the large area values are at least
100% greater than the small area values, and preferably are between 300% and 500%
of the small area values.
[0009] Other aspects of the invention are in part set forth below and will in part be obvious
from the following description taken in connection with the accompanying DRAWINGS
wherein:
FIGURE 1 is a vertical sectional view of the preferred embodiment of a spinneret usable
to make the feed yarns according to the invention;
FIGURE 2 is a bottom plan view of the FIGURE 1 spinneret, looking up;
FIGURE 3 is a cross-sectional view of a filament according to certain aspects of the
invention;
FIGURE 4 is a side elevation view of the molten streams issuing from the FIGURE 1
spinneret according to certain aspects of the invention;
FIGURE 5 is a graph illustrating the variation in denier along a representative filament
according to certain aspects of the invention; and
FIGURE 6 is a graph illustrating the distribution of the fluctuations illustrated
in FIGURE 4 for a representative multiple orifice spinneret according to certain aspects
of the invention.
Preparation of Exemplary Feed Yarn
[0010] The feed yarn for the process invention will be specifically exemplified using polyester
polymer, it being understood that certain aspects of the invention are applicable
to the class of melt-spinnable polymers generally. "Polyester" as used herein means
fiber-forming polymers at least 85% by weight of which is formable by reacting a dihydric
alcohol with terephthalic acid. Polyester typically is formed either by direct esterification
of ethylene glycol with terephthalic acid, or by ester interchange between ethylene
glycol and dimethylterephthalate.
[0011] FIGURES 1 and 2 illustrate the preferred embodiment of a spinneret design which can
be employed for obtaining all aspects of the invention. The spinneret includes a large
counterbore 20 formed in the upper surface 21 of spinneret plate 22. Small counterbore
24 is formed in the bottom of and at one side of large counterbore 20. A large capillary
26 extends from the bottom of large counterbore 20 at the side opposite small counterbore
24, and connects the bottom of large counterbore 20 with the lower surface 28 of plate
22. Small capillary 30 connects the bottom of counterbore 24 with surface 28. Capillaries
26 and 30 are each inclined four degrees from the vertical, and thus have an included
angle of eight degrees. Counterbore 20 has a diameter of 0.113 inch (2.87 mm.), while
counterbore 24 has a diameter of 0.052 inch (1.32 mm.). Capillary 26 has a diameter
of 0.016 inch (0.396 mm.) and a length of 0.146 inch (3.81 mm.), while capillary 30
has a diameter of 0.009 inch (0.229 mm.) and a length of 0.032 inch (0.813 mm.). Land
32 separates capillaries 26 and 30 as they emerge at surface 28, and has a width of
0.0043 inch (0.108 mm.). Plate 22 has a thickness of 0.554 inch (14.07 mm.). Capillaries
26 and 30 together with counterbore 20 and 24 constitute a combined orifice for spinning
various novel and useful filaments according to the invention, as will be more particularly
described hereinafter.
[0012] As a specific example, molten polyester polymer of normal textile molecular weight
is metered at a temperature of 290°C. through a spinneret having 34 combined orifices
as above specifically disclosed. The polymer throughput is adjusted to produce filaments
of 8 average denier per filament at a spinning speed of 3400 yards per minute, the
molten streams being conventionally quenched into filaments by transversely directed
quenching air.
[0013] Under these spinning conditions a remarkable phenomenon occurs, as illustrated in
FIGURE 4. Due to the geometry of the spinneret construction, the polymer flowing through
the smaller capillaries 30 has a higher velocity than that flowing through the larger
capillaries. The speeds and momenta of the paired streams issuing from each combined
orifice and the angle at which the streams converge outside the spinneret are such
that the slower streams 34 travel in substantially straight lines after the points
at which the paired streams first touch and attach, while each of the smaller and
faster of the streams 36 forms sinuous loops back and forth between successive points
of attachment 38 with its associated larger streams. This action can be readily observed
using a stroboscopic light directed onto the streams immediately below the spinneret
face 28. As the molten streams accelerate away from the spinneret, the slower stream
attenuates between the points of attachment 38 and the loops of the faster stream
become straightened until the faster stream is brought into continuous contact with
the slower stream. The slower stream attenuates more between the points of first attachment
than at the points of first attachment so that the resulting combined stream has a
cross- section which is larger at the points of first attachment than in the regions
between these points. The resulting combined stream is then further attenuated somewhat
until it is solidified into a filament 40 by the transverse quench air.
[0014] Each solidified filament 40 has non-round cross-sectional areas which vary repetitively
along its length. As illustrated qualitatively in FIGURE 5, when using the above spinning
conditions, the filament cross-sectional area repetitively varies at a repetition
rate of about one per meter, although this can be varied by modifying the spinning
conditions and the geometry of the spinneret passages.
[0015] Due to minor differences between combined orifices, temperature gradations across
the spinneret, and other like deviations from exactly the same treatment for each
pair of streams, a multiple orifice spinneret will typically provide somewhat different
repetition rates among the several resulting streams and filaments. An example of
this is qualitatively shown in FIGURE 6, wherein is shown that various orifices produce
somewhat different repetition rates as determined by stroboscopic examination of the
combined streams just below the spinneret face. The repetition rate is proportional
to the stroboscope frequency bringing about apparent cessation (or freezing) of movement
of the thick and thin regions of.the filament. A number of such frequencies are plotted
along the horizontal axis of Figure 6, and on the vertical axis are plotted the number
of orifices giving filaments wherein such freezing was observed, at each given stroboscope
frequency. In the resulting multifilament yarn, each filament has a cross-sectional
area which varies repetitively from small values in thin regions to large values in
thick regions along its length, the large values being at least 25% greater than the
small values. Improved spun-like effects in the ultimate textured yarn are obtained
when the large values are at least 100% greater than the small values, with optimum
results when the large values are between 300% and 500% of the small values.
An Exemplary Process of the Invention
[0016] The above feed yarn is simultaneously draw-textured on a Barmag FK-4 texturing machine,
using as the false-twist device a friction aggregate of the type disclosed in Yu U.S.
patent 3,973,383, the disclosure of which is incorporated herein by reference. The
draw ratio is set at 1.60 with a winding speed of 385 ypm (about 350 meters per minute).
Both heaters are set at.200°C., with an overfeed to the second heater of 10.47% and
an overfeed to the winder of 6.79%. The aggregate speed is set such that the yarn
tensions just before and just after the aggregate are equal.
[0017] The resulting yarn has numerous filament breaks primarily in the thin regions, the
broken ends protruding from the yarn bundle. The filaments are broken with considerably
more control than those in the patents referred to above, and, because of the variable
denier, fabrics made from the. resulting yarns have a much more soft and luxurious
hand than those made from prior art yarns with the same average denier per filament.
This softness of hand is particularly evident when the cross-sectional areas of the
thick portions of the filaments are at least 100% greater than those of the thin portions,
and values between 300% and 500% greater are particularly preferred.
1. A yarn bundle characterized by a plurality of quasi-continuous filaments, each
of said plurality of filaments having a cross-sectional area which varies repetitively
from small values in thin regions to large values in thick regions along its length,
said large values, being at least 25% greater than said amall values, said thick and'thin
regions being out of phase from filament to filament along the length of said yard,
said filaments being repeatedly broken to provide broken ends primarily in said thin
regions, said broken ends protruding from said bundle.
2. The yarn bundle of claim 1, characterized in that said filaments have alternating
S and Z helical crimp along their lengths.
3.. The yarn bundle of either claim 1 or claim 2, in that the average distance between
consecutive thick regions along each of said filaments is between 2 centimeters and
20 meters.
4. The yarn bundle of claim 3, characterized in that said average distance is between
20 centimeters and 5 meters.
5. The yarn bundle of any of the preceding claims, characterized in that said large
values are at least 100% greater than said small values.
6. The yarn bundle of any of the preceding claims, characterized in that said large
values-are between 300% and 500% of said small values.
7. A process for making a spun-like yarn, characterized by drawing a feed yarn, said
feed yarn comprising a plurality of continuous filaments, each of said plurality of
filaments having a cross-sectional area which varies repetitively from small values
in thin regions to large values in thick regions along its length, said large values
being at least 25% greater than said small values, said drawing being at a draw ratio
selected to break a plurality of said filaments in said thin regions.
8. The process of claim 7, characterized in that said yarn is false-twisted while
said yarn is being drawn.
9. The process of claim 7, characterized in that said yarn is false-twiste and heat-set
while said yarn is being drawn.
10. The process of any of claims 7 to 9, characterized in that said large values are
at least 100% greater than said small values.
11. The process of claim 10, characterized in that. said large values are between
300% and 500% of said small values.