BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to the manufacture of stretch composite yarns and fabrics.
It specifically relates to the fabrics and methods including two sets of elastic core
fibers within one yarn.
Summary of Related Art
[0002] Stretch fabrics with elastic composite yarn have been on the markets for long time.
Fabric and garment manufacturers generally know how to make fabrics with the right
quality parameters to achieve fabrics acceptable to consumers. In current commercially
available fabrics, only one elastic fiber system exists inside yarn and fabrics. One
elastic fiber provides double functions: stretch and recovery. It is difficult to
obtain the fabrics which have easy stretch, high recovery and low shrinkage performance.
[0003] Easy stretch is one important characteristic for comfort garment. For garment with
greater comfort, the fabric can be easy stretched out when garment is put on human
body and move. They have low pressure exerted on the body by garment. The garment
can be cut to achieve a more streamlined appearance and can conform better to the
body, while still maintaining comfort for wearer in motion. Such performance can be
achieved through low fabric tensile modulus by minimizing the garment's resistance
to the body's demands in movement.
[0004] However, for the fabric with low tensile modulus, a typical quality issue is that
the fabric can't quickly recovery to original size and shape after fabrics are over
stretched out in some parts of the body, such as in knee, butt and waist, particularly
for the fabrics with high stretch level. Usually, the fabric has low recovery power
when the tensile modulus is low. Consumers see baggy and saggy issues after long time
wear.
[0005] In contrast, in order to get fabric with good recovery, extra contractive force is
needed within fabrics. Higher content or more powerful elastic fiber could be added
to fabrics. However, these fabrics have high extension modulus and higher restrict
force. Consumers complain higher garment pressures and uncomfortable restriction during
wearing and movement. In the same time, the fabric has poor dimension stability. Heatset
is a necessary processing to control the fabric shrinkage. The garment comfort and
freedom of movement are compromised by fabric shape retention and recovery function.
The fabrics having easy stretch, high recovery and low shrinkage performance are still
desired.
[0006] For many years, composite elastic yarns are well known. For example, by
US patent numbers 4470250,
4998403,
7134265,
6848151, the elastomeric fibers, such as spandex, have been covered with relatively inelastic
fibers in order to facilitate acceptable processing for knitting or weaving, and to
provide elastic composite yarns with acceptable characteristics for various end-use
fabrics. In US patent application
US 2008/0268734A1 and
US 2008/0318485A1, a rigid filament is used, together with elastic filaments, as core inside core spun
yarn.
[0007] Therefore, there is a need to produce stretch wovens, which have easy stretch, easy
process, low shrinkage, friendly garment making, and excellent recovery power and
low growth.
[0008] WO 2012/062480 relates to a stretch yarn comprising a stretchable core covered by an inelastic fibers
sheath, the stretchable core comprises first and second fibers that have elastic properties,
the first fiber is an elastomer and the second fiber is a polyester based (co)polymer.
[0009] US 2012/0244771 relates to composite yarns having a filamentary core provided with at least one elastic
performance filament and at least one inelastic control filament. A fibrous sheath,
preferably formed from spun staple fibers, surrounds the filamentary core. The at
least one elastic performance filament most preferably includes a spandex and/or lastol
filament and the at least one inelastic control filament is most preferably formed
of a textured polymer or copolymer of a polyamide, a polyester, a polyolefin and mixtures
thereof.
[0010] JP 2008/297646 relates to a core-sheath composite spun yarn in which the core is a twisted yarn
of a polyester type composite long fiber yarn and a polyurethane elastic fiber.
SUMMARY OF THE INVENTION
[0011] The present invention is as defined in the claims.
[0012] One aspect includes methods for making composite yarns with two sets of different
elastic core fibers comprising spandex, referred to as a double elastic composite
yarn, wherein at least one set of elastic core fibers is pre-covered elastic yarn.
Also included are the double elastic composite yarns and the stretch fabrics and garments
made from such yarns.
[0013] In the core spun yarn defined in the claims, two sets of different elastic core fibers
(elastic core fiber I and elastic core fiber II) and a hard fiber are covered together
to form a composite yarn, wherein at least one set of elastic core fibers is pre-covered
elastic yarn. Another set of elastic core yarn may be bare spandex or pre-covered
elastic yarn. The bare spandex yarn linear density (denier) is from 11 to 560 dtex,
and the hard fiber with a yarn count from 10 to 900 dtex. One suitable hard yarn is
cotton.
[0014] A fabric is made by using the double elastic yarn defined in the claims. The double
elastic yarn is used in at least one direction of the fabric. Any forms of fabrics
may be used, including wovens, circular knits, warp knits and narrow fabrics. Further
processing may include scouring, bleaching, dyeing, drying, sanforizing, singeing,
de-sizing, mercerizing, and any combination of such steps. The stretched fabric produced
may be formed into a garment.
BRIEF DESCRIPTION OF THE FIGURES
[0015] The detailed description will refer to the following drawings, wherein like numerals
refer to like elements and wherein:
FIG. 1 is an illustration of a core spun yarn with two elastic cores.
Fig 2 is a schematic description of a core spinning apparatus with two draft devices
for two bare elastic fibers.
Fig 3 is a schematic description of a core spinning apparatus with two draft devices
with weighted roll.
Fig 4 is a schematic description of a core spinning apparatus with two draft devices
for one bare elastic fiber and one pre-covered elastic yarn.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Elastomeric fibers are commonly used to provide stretch and elastic recovery in woven
fabrics and garments. "Elastomeric fibers" are either a continuous filament (optionally
a coalesced multifilament) or a plurality of filaments, free of diluents, which have
a break elongation in excess of 100% independent of any crimp. An elastomeric fiber
when (1) stretched to twice its length; (2) held for one minute; and (3) released,
retracts to less than 1.5 times its original length within one minute of being released.
As used in the text of this specification, "elastomeric fibers" means at least one
elastomeric fiber or filament. Such elastomeric fibers include but are not limited
to rubber filament, biconstituent filament and elastoester, lastol, and spandex.
[0017] "Spandex" is a manufactured filament in which the filament-forming substance is a
long chain synthetic polymer comprised of at least 85% by weight of segmented polyurethane.
[0018] "Elastoester" is a manufactured filament in which the fiber forming substance is
a long chain synthetic polymer composed of at least 50% by weight of aliphatic polyether
and at least 35% by weight of polyester.
[0019] "Biconstituent filament" is a continuous filament or fiber including at least two
polymers adhered to each other along the length of the filament, each polymer being
in a different generic class, for example, an elastomeric polyetheramide core and
a polyamide sheath with lobes or wings.
[0020] "Lastol" is a fiber of cross-linked synthetic polymer, with low but significant crystallinity,
composed of at least 95 percent by weight of ethylene and at least one other olefin
unit. This fiber is elastic and substantially heat resistant.
[0021] "Polyester bi-component filament" means a continuous filament comprising a pair of
polyesters intimately adhered to each other along the length of the fiber, so that
the fiber cross section is for example a side -by-side, eccentric sheath-core or other
suitable cross-section from which useful crimp can be developed. The fabric made with
this filament, such as Elasterell-p, PTT/PET bi-component fiber, has excellent recovery
characteristics.
[0022] "No-elastomeric elastic fibers" means a stretch filament without containing elastomeric
fiber. However, the recoverable stretch of such yarn must be higher than 20% as tested
by ASTM D6720 methods, such as textured PPT stretch filament, textured PET stretch
filament, bi-component stretch filament fiber, or PBT stretch filament.
[0023] A "Pre-covered elastic yarn" is one surrounded by, twisted with, or intermingled
with hard yarn before the core spun process. The pre-covered elastic yarn that includes
elastomeric fibers and hard yarns is also termed a "pre-covered yarn" in the text
of this specification. The hard-yarn covering serves to protect the elastomeric fibers
from abrasion during textile processes. Such abrasion can result in breaks in the
elastomeric fiber with consequential process interruptions and undesired fabric non-uniformities.
Further, the covering helps to stabilize the elastomeric fiber elastic behavior, so
that the elongation of pre-covered elastic yarn can be more uniformly controlled during
textile processes than would be possible with bare elastomeric fibers. The pre-covered
yarn also can increase the tensile modulus of the yarn and fabric, which is helpful
to improve the fabric recovery power and dimensional stabilities.
[0024] The pre-covered yarns include: (a) single wrapping of the elastomer fibers with a
hard yarn; (b) double wrapping of the elastomer fibers with a hard yarn; (c) continuously
covering (i.e., corespun or core-spinning) an elastomer fiber with staple fibers,
followed by twisting during winding; (d) intermingling and entangling elastomer and
hard yarns with an air jet; and (e) twisting elastomer fibers and hard yarns together.
[0025] "Double elastic composite yarn" is a composite yarn comprising two sets of elastic
core fibers with single yarn, covered with hard staple fiber sheath. The term "double
elastic yarn" is used interchangeably throughout the specification.
[0026] The stretch fabric of some embodiments includes double elastic core spun yarn in
weft direction. In some embodiments, a fabric with unexpectedly high recovery properties
was achieved, especially for high stretch fabrics. This was accomplished by the use
of core spun yarn containing two different elastic fibers with different stretch properties.
Those of skill in the art will recognize that where weft stretch is desired, the fabric
may include such core spun yarn with double elastic fibers in weft direction.
[0027] As demonstrated in Fig 1, the double elastic yarn 8 includes two elastic filament
cores: elastic core I (4, in Fig. 1) and elastic core II (6, in Fig 1). The elastic
core filaments are surrounded, preferably along the entirety of its length by a fibrous
sheath 2 comprised of spun staple fibers.
[0028] A representative core spinning apparatus 40 is shown in Fig. 2. Two separated fiber
draft devices 46 and 64 are installed on the machine. During core spinning processing,
elastic core filament I 52 and elastic core filament II 66 are put on feed roll 46
and 64 separately and are combined with a hard yarn to form a composite core spun
yarn. The core elastic filaments from tube 48 and tube 60 are unwound in the direction
of arrow 50 and 62 by the action of positively-driven feed rollers 46 and 64. The
feed rollers 46 and 64 serve as a cradle for the tube 48 and tube 60 and deliver the
elastic fiber of yarn 52 and 66 at a pre-determined speed.
[0029] The hard fiber or yarn 44 is unwound from tube 54 to meet the elastic core filament
52 and 66 at the set of front rollers 42. The combined elastic core filaments 52,
66 and hard fiber 44 are core spun together at spinning device 56.
[0030] The elastic core filament I 52 and elastic core filament II 66 are stretched (drafted)
before it enters the front rollers 42. The elastic filaments are stretched through
the speed difference between feed rollers 46 or 64 and front rollers 42. The delivery
speed of the front rollers 42 is greater than the speed of the feed rollers 46 and
64. Adjusting the speed of the feed rollers 46 and 64 gives the desired draft or stretch
ratio.
[0031] The stretch ratio is normally 1.01X times to 5.0X times (1.01X to 5.0X) compared
to the un-stretched fiber. Too low a stretch ratio will result in low quality yarns
having grin-through and an un-centered elastic filament. Too high a stretch ratio
will result in breakage of the elastic filament and core void.
[0032] Another representative core spinning apparatus 40 is shown in Fig. 3. Elastic core
I is bare elastic filaments 52, while elastic core II 68 is pre-covered elastic yarn.
The elastic core II from tube 12 is unwound in the direction of arrow 62 by the action
of positively-driven feed rollers 64. The weighted roll 66 serves to maintain stable
contact between the elastic core II and feed rollers 64 in order to deliver the elastic
core II of yarn 68 at a pre-determined speed. Other elements of Fig. 3 are as described
for Fig. 2.
[0033] Another representative core spinning apparatus 40 is shown in Fig. 4. Elastic core
I is bare elastic filaments 52, while elastic core II is pre-covered elastic yarn.
The elastic core II from tube 12 is taken off from end and then passes through a tension
control device and a guide bar. The tension device serves to keep the yarn tension
stable at a pre-determined level. The stretch ratio for bare elastic fiber is normally
1.01X times to 5.0X times (1.01X to 5.0X) compared to the un-stretched fiber. Other
elements of Fig. 4 are as described for Fig. 2.
[0034] According to some embodiments of the method, two elastic fibers with different properties
and a hard fiber are covered together to form a composite yarn, wherein the two elastic
fibers are stretched to different drafts of its original length during yarn covering
process. The draft of two elastic fibers can be selected between drafts 1.01X times
to 5.0X times. For the two core elastic fibers with different deniers or different
filament numbers, the stretch ratio of core elastic I and elastic core II could be
different from each other, depending the elastic fiber performances and requirement
of fabric quality. In many cases, one core is drafted more to provide high stretch
performance, while another core is stretched less to provide the fabrics with low
shrinkage and high recovery power.
[0035] In conventional fabrics, if heat setting is not used to "set" the spandex, the fabric
may have high shrinkage, excessive fabric weight, and excessive elongation, which
may result in a negative experience for the consumer. Excessive shrinkage during the
fabric finish process may result in crease marks on the fabric surface during processing
and household washing. Creases that develop in this manner are frequently very difficult
to remove by ironing.
[0036] By using low draft in one of elastic core fiber, the high-temperature heat setting
step in the process can be avoided. This new process may reduce heat damage to certain
fibers (i.e. cotton) and thus may improve the handle of the finished fabric. The fabrics
of some embodiments may be prepared in the absence of a heat setting step including
where the fabrics will be prepared into garments. As a further benefit, heat sensitive
hard yarns can be used in the new process to make shirting, elastic fabrics, thus
increasing the possibilities for different and improved products. In addition, the
shorter process has productivity benefits to the fabric manufacturer.
[0037] It was unexpectedly found that the core spun yarn with two different elastic core
fibers has higher stretch and recovery power than the core spun yarn made from single
core elastic filament with the same denier. For example, the core spun yarn with two
cores of 30D/3filament spandex plus 40D/4filament spandex, has more recovery power
than a core spun made from single core of 70D/5filament yarn under the same draft.
So, we can make the core spun yarn with higher stretch and higher recovery power by
using the same content of spandex.
[0038] Two elastic fibers with different properties could be used and are covered together
with hard fiber sheath to form a composite yarn, wherein the two elastic fibers could
have different polymer compositions and with different stress-strain behaviors. One
example is to use two spandex fibers with different heatset efficiency together within
one core spun yarn, such as normal LYCRA
® spandex fiber T162C and easy set LYCRA
® fiber T562B. The fabric can be heatset at the temperature higher than easy set LYCRA
® fiber heatset temperature, but lower than normal LYCRA
® fiber heatset temperature. So, the fabrics just get partial heatset which provide
acceptable fabric shrinkage while good stretch and growth.
[0039] Another example is the core spun containing elastic core I with high tension modulus
and elastic core II with low tension modulus. Elastic core I provides the fabric with
high recovery power and low fabric growth, while elastic core II with low modulus
gives the fabric with easy stretch, lower shrinkage, resulting in the fabric with
easy stretch, high holding force and high dimension stability. The elastic fibers
with different chemical composition also can be combined together with one core spun
yarn, such as polyolefin elastic fiber Lastol and spandex (not falling within the
scope of the claims). Spandex fibers offer the high recovery power while Lastol fibers
contribute the good heat resistance and lower shrinkage performance.
[0040] The combination of elastic core I and elastic core II could be elastic bare fiber
plus elastic bare fiber (not falling within the scope of the claims); or elastic bare
fiber plus pre-covered elastic yarn (as defined in the claims), or pre-covered elastic
yarn plus pre-covered elastic yarn (as defined in the claims). The bare elastic fiber
may be from about 11 dtex to about 444 dtex (denier - about 10D to about 400D), including
11 dtex to about 180 dtex (denier 10D to about 162D).
[0041] The pre-covered elastic yarn includes various types, such as single wrapping of the
elastomer fibers with a hard yarn; double wrapping of the elastomer fibers with a
hard yarn; continuously covering (i.e., core-spinning) an elastomer fiber with staple
fibers, followed by twisting during winding; intermingling and entangling elastomer
and hard yarns with an air jet; and twisting elastomer fibers and hard yarns together.
The preferred pre-covered elastic yarns are spandex airjet covered yarns with textured
polyester and nylon filaments, such as 40D or 70D spandex with 50D to 150D polyester
air covered yarn. The pre-covered elastic yarn is made in a separated machine before
the core spun yarn process.
[0042] The pre-covered elastic yarn can be present in any desired amount, for example from
about 5 to about 35% weight percent based on total double elastic yarn weight. The
linear density of the pre-covered yarn ranges from about 15 denier (16.5 dtex) to
about 900 denier (990 dtex), including from about 30 denier to 300 denier (33dtex
to 330 dtex). When the ratio of yarn denier between pre-covered yarn and total double
elastic yarn is lower than 35%, the fabric has no substantial grin through. After
the finishing process, two elastic core fibers, including in pre-covered yarn, are
invisible and untouchable.
[0043] The linear density (denier) of bare elastic fiber (prior to covering to form pre-covered
yarn) may be from about 11 dtex to about 444 dtex (denier - about 10D to about 400D),
including 11dtex to about 180 dtex (denier 10D to about 162D). During the pre-covering
process, the elastic fiber is drafted between 1.1X to 6X its original length. In pre-covering,
the elastic fiber is pre-covered with one or more hard yarns, with hard yarn linear
density (denier) from 11dtex to 667 dtex (10 to 600 denier).
[0044] Also described is a combination of elastic core fiber I and elastic core fiber II
including one set of elastic bare fiber plus another set of no-elastomeric elastic
fibers (not within the scope of the claims). The no-elastomeric elastic fibers can
be textured PET stretch filament, textured PPT stretch filament, bi-component fiber,
or PBT stretch fiber. It was a surprise to find that when the no-elastomeric elastic
fiber with recoverable stretch higher than 20% were used as one of the elastic core
fibers, the performance of the core spun yarn and the fabric change dramatically.
The fabrics have high stretch and high recovery power. The linear density of the no-elastomeric
elastic fibers can range from about 15 denier (16.5 dtex) to about 450 denier (495
dtex), including from about 30 denier to 150 denier (33dtex to 165 dtex). When the
denier is too high, the fabric could have substantial grin through.
[0045] The elastomer fiber content with double elastic core spun yarns is between about
0.1% to about 20%, including from about 0.5% to about 15%, and about 5% to about 10%
based on the weight of the yarn. Elastomeric fiber content within the fabric may be
from about 0.01% to about 10% by weight based on the total fabric weight, including
from about 0.5% to about 5%.
[0046] The staple sheath fibers in the double elastic yarn can be nature fibers, such as,
cotton, wool or linen. They also can be the staple man made or synthetic fibers of
mono component polyethylene terephthalate) and poly(trimthylene terephthalate) fiber,
polycaprolactam fiber, poly(hexamethylene adipamide) fibers acrylic fibers, modacrylic,
acetate fibers, Rayon fibers, Nylon and combinations thereof.
[0047] Such double elastic yarns can be used for making a stretch fabric where various weave
patterns can be applied, including plain, poplin, twill, oxford, dobby, sateen, satin
and combinations thereof. The fabrics of some embodiments may have an elongation from
about 10% to about 45% in the warp or/and weft direction. The fabrics may have shrinkage
of about 15% or less after washing. The stretch woven fabric may have an excellent
cotton hand feel. Garments may be prepared from the fabrics described herein.
[0048] The warp yarn can be the same as, or different from, the weft yarns. The fabric can
be weft-stretch only, or it can be bi-stretch, in which useful stretch and recovery
properties are exhibited in both the warp and weft directions.
[0049] Air jet loom, rapier loom, projectile loom, water jet loom and shuttle loom can be
used.
[0050] Dyeing and finishing process are important in producing a satisfactory fabric. The
fabric can be finished in continuous range processes and the piece dye jet processes.
Conventional equipment found in a continuous finishing plant and piece dye factories
are usually adequate for processing. The normal finishing process sequences include
preparation, dyeing and finishing. In preparation and dyeing process, including in
singing, desizing, scouring, bleaching, mercerizing and dyeing, normal processing
methods for elastic wovens are usually satisfactory.
ANALYTICAL METHODS:
Yarn Recoverable Stretch
[0051] The recoverable stretch of elastic fibers used in the Examples was measured as follows.
Each yarn sample was formed into a skein of 5000 +/-5 total denier (5550 dtex) with
a skein reel at a tension of about 0.1 gpd (0.09 dN/tex). The skein was conditioned
at 70 °F (+/-2 °F) (21 ° +/-1 °C.) and 65% (+/-2%) relative humidity for a minimum
of 16 hours. The skein was hung substantially vertically from a stand, a 6 mg/den
(5.4 mg/dtex) weight (e.g. 30 grams for a 5550 dtex skein) was hung on the bottom
of the skein, the weighted skein was allowed to come to an equilibrium length, and
the length of the skein was measured to within 1 mm and recorded as "C
b". The 5.4 mg/dtex weight was left on the skein for the duration of the test. Next,
a 1030 gram weight (206 mg/d; 185.4 mg/dtex) was hung from the bottom of the skein,
and the length of the skein was measured to within 1 mm and recorded as "L
b".
[0052] The 1030 g weight was removed, and the skein was then immersed into boiling water
for 10 minutes at 100
0C degree water, after which the skein were removed from the water and conditioned
as above for 16 hours. This step is designed to simulate commercial fabric relaxation
process, which is one way to develop the fabric stretch. The length of the skein was
measured as above, and its length was recorded as "C
a". The 1030-gram weight was again hung from the skein, and the skein length was measured
as above and recorded as "L
a". The after relaxation Yarn recoverable stretch (percent), "CC
a", was calculated according to the formula CC
a=100×(L
a-C
a)/L
a. Yarn shrinkage was calculated according to formula Cs (%) = 100 × (L
b-L
a)/L
b.
Woven Fabric Elongation (Stretch)
[0053] Fabrics are evaluated for % elongation under a specified load (
i.e., force) in the fabric stretch direction(s), which is the direction of the composite
yarns (
i.e., weft, warp, or weft and warp). Three samples of dimensions 60 cm × 6.5 cm were cut
from the fabric. The long dimension (60 cm) corresponds to the stretch direction.
The samples are partially unraveled to reduce the sample widths to 5.0 cm. The samples
are then conditioned for at least 16 hours at 20°C +/- 2°C and 65% relatively humidity,
+/- 2%.
[0054] A first benchmark was made across the width of each sample, at 6.5 cm from a sample
end. A second benchmark was made across the sample width at 50.0 cm from the first
benchmark. The excess fabric from the second benchmark to the other end of the sample
was used to form and stitch a loop into which a metal pin could be inserted. A notch
was then cut into the loop so that weights could be attached to the metal pin.
[0055] The sample non-loop end was clamped and the fabric sample was hung vertically. A
17.8 Newton (N) weight (4 lb) is attached to the metal pin through the hanging fabric
loop, so that the fabric sample is stretched by the weight. The sample was "exercised"
by allowing it to be stretched by the weight for three seconds, and then manually
relieving the force by lifting the weight. This cycle was carried out three times.
The weight was allowed then to hang freely, thus stretching the fabric sample. The
distance in millimeters between the two benchmarks was measured while the fabric was
under load, and this distance is designated ML. The original distance between benchmarks
(i.e., unstretched distance) was designated GL. The % fabric elongation for each individual
sample as calculated as follows:
![](https://data.epo.org/publication-server/image?imagePath=2024/09/DOC/EPNWB1/EP21191383NWB1/imgb0001)
[0056] The three elongation results were averaged for the final result.
Woven Fabric Growth (Unrecovered Stretch)
[0057] After stretching, a fabric with no growth would recover exactly to its original length
before stretching. Typically, however, stretch fabrics will not fully recover and
will be slightly longer after extended stretching. This slight increase in length
is termed "growth."
[0058] The above fabric elongation test must be completed before the growth test. Only the
stretch direction of the fabric was tested. For two-way stretch fabric both directions
were tested. Three samples, each 55.0 cm × 6.0 cm, were cut from the fabric. These
were different samples from those used in the elongation test. The 55.0 cm direction
should correspond to the stretch direction. The samples were partially unraveled to
reduce the sample widths to 5.0 cm. The samples were conditioned at temperature and
humidity as in the above elongation test. Two benchmarks exactly 50 cm apart were
drawn across the width of the samples.
[0059] The known elongation % (E%) from the elongation test was used to calculate a length
of the samples at 80% of this known elongation. This was calculated as
![](https://data.epo.org/publication-server/image?imagePath=2024/09/DOC/EPNWB1/EP21191383NWB1/imgb0002)
where L was the original length between the benchmarks (i.e., 50.0 cm). Both ends
of a sample were clamped and the sample was stretched until the length between benchmarks
equaled L + E (length) as calculated above. This stretch was maintained for 30 minutes,
after which time the stretching force was released and the sample was allowed to hang
freely and relax. After 60 minutes the % growth was measured as
![](https://data.epo.org/publication-server/image?imagePath=2024/09/DOC/EPNWB1/EP21191383NWB1/imgb0003)
where L2 was the increase in length between the sample benchmarks after relaxation
and L was the original length between benchmarks. This % growth was measured for each
sample and the results averaged to determine the growth number.
Woven Fabric Shrinkage
[0060] Fabric shrinkage was measured after laundering. The fabric was first conditioned
at temperature and humidity as in the elongation and growth tests. Two samples (60
cm × 60 cm) were then cut from the fabric. The samples were taken at least 15 cm away
from the selvage. A box of four sides of 40 cm × 40 cm was marked on the fabric samples.
[0061] The samples were laundered in a washing machine with the samples and a loading fabric.
The total washing machine load was 2 kg of air-dried material, and not more than half
the wash consisted of test samples. The laundry was gently washed at a water temperature
of 40°C and spun. A detergent amount of 1g /l to 3 g/l was used, depending on water
hardness. The samples were laid on a flat surface until dry, and then they were conditioned
for 16 hours at 20°C +/- 2°C and 65% relative humidity +/- 2% rh.
[0062] Fabric sample shrinkage was then measured in the warp and weft directions by measuring
the distances between markings. The shrinkage after laundering, C%, was calculated
as
![](https://data.epo.org/publication-server/image?imagePath=2024/09/DOC/EPNWB1/EP21191383NWB1/imgb0004)
where L1 was the original distance between markings (40 cm) and L2 is the distance
after drying. The results are averaged for the samples and reported for both weft
and warp directions. Negative shrinkage numbers reflect expansion, which was possible
in some cases because of the hard yarn behavior.
Fabric Weight
[0063] Woven fabric samples were die-punched with a 10cm diameter die. Each cut-out woven
fabric sample was weighed in grams. The "fabric weight" was then calculated as grams/square
meters.
Examples:
[0064] The following examples demonstrate the present invention and its capability for use
in manufacturing a variety of fabrics. The examples are to be regarded as illustrative
in nature and not as restrictive.
[0065] For each of the following denim fabric examples, 100 % cotton open end spun yarn
or ring spun was used as warp yarn. For denim fabrics, they included two count yarns:
7.0 Ne (843.6 dtex) OE yarn and 8.5 Ne (702.98 dtex) OE yarn with irregular arrangement
pattern. The yarns were indigo dyed in rope form before beaming. Then, they were sized
and made the weaving beam. For bottom weight fabrics, the warp yarn are 20Ne (295.25
dtex) 100% cotton ring spun yarn. They were sized and made the weaving beam.
[0066] Table 1 lists four examples of core spun yarn with traditional one elastic core filament
and yarn containing two sets of elastic cores (not falling within the scope of the
claims).
[0067] Several core spun yarns with double elastic core fibers were used as weft yarn. Various
elastic core fibers, including bare spandex, pre-covered polyester/LYCRAO spandex
fiber or pre-covered nylon/spandex yarn were used as in the core. Table 2 lists the
materials and process ways that were used to make the core spun yarn for each example.
Table 3 shows the detail fabric structure and performance summary for each fabric.
Lycra
® spandex are available from Invista, s. á. r. L., Wichita, KS. For example, in the
column headed spandex 40D means 40 denier (44.44 dtex); 3.5X means the draft of the
Lycra
® imposed by the core spinning machine (machine draft). In the column headed 'Rigid
sheath Yarn', 20's is the linear density of the spun yarn as measured by the English
Cotton Count System. The rest of the items in Table 1 and Table 2 are clearly labeled.
[0068] Stretch woven fabrics were subsequently made, using the core spun yarn of each example
in Table 2. Table 3 summarizes the yarns used in the fabrics, the weave pattern, and
the quality characteristics of the fabrics. Some additional comments for each of the
examples are given below. Unless otherwise noted, the fabrics were woven on a Dornier
air-jet or rapier loom. Loom speed was 500 picks/minute. The widths of the fabric
were about 193.04 cm and about 182.88 cm (about 76 and about 72 inches) in the loom
and greige state respectively. The loom has double weaving beam capacity.
[0069] Each greige fabric in the examples was finished by a jiggle dye machine. Each woven
fabric was pre-scoured with 3.0 weight % Lubit
®64 (Sybron Inc.) at 49°C for 10 minutes. Afterwards it was de-sized with 6.0 weight
% Synthazyme
® (Dooley Chemicals. LLC Inc.) and 2.0 weight % Merpol
® LFH (E. I. DuPont Co.) for 30 minutes at 71°C and then scoured with 3.0 weight %
Lubit
® 64, 0.5 weight % Merpol
® LFH and 0.5 weight % trisodium phosphate at 82°C for 30 minutes. Fabric finishing
was followed by dry in a tenter frame at 160 °C for 1 minute.
TABLE 1: Reference Examples of yarns with double elastic core fibers
Example |
Rigid sheath yarn |
Elastic Core I fiber types |
Elastic Core I fiber deniers |
Elastic Core I fiber draft |
Elastic Core II fiber types |
Elastic Core II fiber denier |
Elastic Core II fiber draft |
Yarn Twist level, twisters per inch |
Cotton Roving draft |
Core spun yarn recoverable Stretch, % |
Core spun yarn Shrinkage, % |
Yarn A |
16' cotton |
T162B LYCRA® fiber |
44/3f dtex (40D) |
3.5X |
No |
No |
No |
18 |
22X |
17.71 |
2.1 |
Yarn 8 |
16' cotton |
T162B LYCRA® fiber |
22/2f dtex (20D) |
3.5X |
T162B LYCRA® fiber |
22/2f dtex (20D) |
3.5X |
18 |
22X |
20.63 |
2.4 |
Yarn C |
16' cotton |
T162B LYCRA® fiber |
77/5f dtex (70D) |
3.8X |
No |
No |
No |
18 |
22X |
38.71 |
2.28 |
Yarn D |
16' cotton |
T162B LYCRA® fiber |
44/3 dtex (40D) |
3.8X |
T162B LYCRA® fiber |
33/3f dtex (30D) |
3.8X |
18 |
22X |
40.88 |
2.33 |
TABLE 2: Weft yarn description
Example |
Rigid sheath yarn |
Elastic Core I fiber types |
Elastic Core I fiber deniers |
Elastic Core I fiber draft |
Elastic Core II fiber types |
Elastic fiber draft in Core II |
Yarn Twist level, twisters per inch |
Cotton Roving draft |
Core spun yarn recoverable Stretch |
Core spun yarn Shrinkage |
1 (reference) |
20' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
No |
No |
18 |
22 |
17.24 |
1.79 |
2 (reference) |
20' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
40D T162B LYCRA® fiber |
1.8X |
18 |
22 |
47.22 |
1.25 |
3 (reference) |
20' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
40D T562B Easy Set LYCRA® fiber |
3.5X |
18 |
22 |
62.24 |
1.68 |
4 (reference) |
16' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
40D polyolefin elastic fiber |
3.6X |
18 |
22 |
36.6 |
1.2 |
5 |
20' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
1.8X |
Pre-covered 40D T162C LYCRA® fiber with 40D/34F Nylon |
3.2X |
18 |
22 |
44.2 |
2.07 |
6 |
20' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
Pre-covered 40D T162C LYCRA® fiber with 40D/34F Nylon |
3.2X |
18 |
22 |
58.04 |
2.01 |
7 |
16' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
Pre-covered 40D T162C LYCRA® fiber with 50D/24F polyester |
1.8X |
16 |
16 |
36.29 |
2.63 |
8 |
16' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
Pre-covered 40D T162C LYCRA® fiber with 50D/24F polyester |
2.6X |
16 |
16 |
49.3 |
2.5 |
9 (reference) |
16' cotton |
T162B LYCRA® fiber |
44 dtex (40D) |
3.5X |
PBT Stretch polyester |
1.15X |
16 |
16 |
24.6 |
2.7 |
TABLE 3: Fabric Example List
Example |
Weft yarn |
Warp yarn |
Base weaving pattern |
Fabric on loom (warp EPI X weft PPI) |
Width on loom |
Finished fabric width, inch |
Fabric weight OZ/Y∧2 |
Fabric Stretch, % |
Fabric Growth, % |
Fabric Shrinkage, % (warp X weft) |
1 |
20s cotton+3.5X LYCRA® fiber |
20s cotton |
3/1 RHT |
96X56 |
76 |
50.5 |
8.95 |
37.6 |
8.7 |
-0.91 X -0.91 |
2 |
20s cotton+3.5X LYCRA® fiber+1.8X LYCRA® fiber |
20s cotton |
3/1 RHT |
96X56 |
76 |
50.5 |
8.88 |
35.4 |
6.4 |
-1.57X-0.13 |
3 |
20s cotton+3.5X LYCRA® fiber+3.5X LYCRA® fiber |
20s cotton |
3/1 RHT |
96X56 |
76 |
50.2 |
9.19 |
38.4 |
7.9 |
-1.31 X -0.65 |
4 |
16s cotton+3.5X LYCRA® fiber+40D polyolefin elastic fiber |
7.0' OE + 8.4' OE cotton indigo |
3/1 RHT |
64X54 |
72 |
55.5 |
11.39 |
47.8 |
6.5 |
-2.21 X -0.91 |
5 |
16s cotton+1.8X LYCRA® fiber+3.2X pre-covered 40D LYCRA® fiber |
20s cotton |
3/1 RHT |
96X56 |
76 |
50.5 |
8.79 |
35.9 |
5.3 |
-1.31 X -0.65 |
6 |
16s cotton+3.5X LYCRA® fiber+3.2X pre-covered 40D LYCRA® fiber |
20s cotton |
3/1 RHT |
96X56 |
76 |
50.5 |
8.96 |
37.8 |
5.9 |
0 X -1.96 |
7 |
16s cotton+3.5X LYCRA® fiber+1.8X pre-covered 40D |
7.0' OE + 8.4' OE cotton indigo |
3/1 RHT |
64X54 |
72 |
56 |
12.80 |
35.3 |
3.5 |
-1.31 X -0.65 |
8 |
LYCRA® fiber 16s cotton+3.5X LYCRA® fiber+2.6X pre-covered 40D LYCRA® fiber |
7.0' OE + 8.4' OE cotton indigo |
3/1 RHT |
64X54 |
72 |
54.7 |
13.27 |
40.4 |
3.9 |
-1.31 X -0.65 |
9 |
16s cotton+3.5X LYCRA® fiber+1.15X PBT fiber |
7.0' OE + 8.4' OE cotton indigo |
3/1 RHT |
64X54 |
72 |
55.2 |
10.79 |
40.7 |
6 |
-2.10 X -0.85 |
Reference Example Yarn A: Typical core spun yarn with one elastic core fiber.
[0070] This is not an innovative yarn. This core spun yarn is 16Ne (369.06 dtex) with one
40D (44.44 dtex) LYCRA
® spandex fiber covered by cotton sheath. The draft of the LYCRA
® fiber is 3.5X during covering process. The cotton twist level TM is 18 twisters per
inch. This yarn has 17.71 % recoverable stretch after boil off.
Reference Example Yarn B: Core spun yarn with two core elastic fibers
[0071] The core spun yarn is 16Ne (369.06 dtex) with two sets of LYCRA
® spandex fiber covered by cotton sheath. Elastic core I fiber is 20D (22.22 dtex)
T162B and Elastic core II fiber is 20D (22.22 dtex) T162B as well. The total denier
of the elastic fibre is 40 denier (44.44 dtex). The draft of the LYCRA
® fiber is 3.5X during covering process. The cotton twist level TM is 18 twisters per
inch. Therefore, this core spun yarn has the same structure with Example Yarn A, including
in yarn count, LYCRA
® fiber denier and yarn twist level, except with 2 sets of core elastic filaments instead
of one end of core spun yarn. The recoverable stretch of this yarn is 20.63%, which
has 2.92 unit percent higher than yarn in sample A. That means the yarn with two sets
of filaments core has high recoverable stretch than the yarn with one set of filament
core under the same content of spandex. In this way, the innovative yarn can provide
high stretch and high recovery power for the fabrics by using the same amount of elastic
fibers.
Reference Example Yarn C: Typical core spun yarn with one elastic core fiber.
[0072] This is not an innovative yarn. The core spun yarn is 16Ne (369.06 dtex) with one
70D (77.77 dtex) LYCRA
® spandex fiber covered by cotton sheath. The draft of the LYCRA
® fiber is 3.8X during covering process. The cotton twist level TM is 18 twisters per
inch. This yarn has 38.71 % recoverable stretch after boil off and the yarn has 2.28
shrinkage.
Reference Example Yarn D: Core spun yarn with two core elastic fibers
[0073] The core spun yarn is 16Ne (369.06 dtex) with two sets of LYCRA
® spandex fibers covered by cotton sheath. The elastic core II ffiber is 30D (33.33
dtex) T162B and elastic core I fiber is 40D (44.44 dtex) T162B. The total denier of
the elastic fiber is 70 denier (77.77 dtex). The draft of both LYCRA
® fiber is 3.8X during covering process. The cotton twist level TM is 18 twisters per
inch. Therefore, this core spun yarn has the same structure with Example Yarn C, except
with 2 sets of core elastic filaments instead of one set of core spun yarn. The recoverable
stretch of this yarn is 40.88%, which has 2.17 unit percent higher than yarn sample
C. That shows that the yarn with two sets of filament core has high recoverable stretch
than the yarn with one set of filament core under the same content of spandex. In
this way, the innovative yarn can provide high stretch and high recovery power for
the fabrics by using the same amount of elastic fibers.
Reference Example 1: Typical stretch woven bottom weight fabric
[0074] This is a comparison example, not according to the invention. The warp yarn was 40/2
Ne (40 Ne = 147.62 dtex) count of ring spun yarn. The weft yarn was 20 Ne (295.25
dtex) cotton with 40D (44.44 dtex) Lycra
® core spun yarn. Lycra
® draft is 3.5X. This weft yarn was a typical stretch yarn used in typical stretch
woven khakis fabrics. Loom speed was 500 picks per minute at a pick level 56 Picks
per inch. Table 3 summarizes the test results. The test results show that after finishing,
this fabric had weight (8.95 g/m
2), stretch ( 37.6 %), width (128.27cm, i.e. 50.5 inch), weft wash shrinkage (0.91
%) and fabric growth (8.7%). The data indicate that this combination of stretch yarns
and fabric construction caused high fabric growth.
Reference Example 2: Stretch Fabric with double elastic fibers
[0075] This sample had the same fabric structure as in example 1. The only difference was
the use of 20s weft yarn containing double core elastic fibers: 40D (44.44 dtex) LYCRA
® fiber with 3.5X draft and 40D (44.44 dtex) LYCRA
® fiber with 1.8X draft. The warp yarn was 40/2 Ne (40 Ne = 147.62 dtex) ring spun
cotton. The loom speed was 500 picks/minute at 56 picks per inch.
[0076] Table 3 summarizes the test results. It is clearly shown that this sample has similar
stretch but lower fabric growth level (6.4%). Therefore, by using two different drafts
of elastic core fibers within the same yarn, the covered yarn and the fabric can achieve
different characters. For example, the high draft in elastic core I fiber give the
fabric with high stretch, while the lower draft in elastic core II fibers give the
fabric with low growth, high recover but not increase the fabric shrinkage. In this
way, the fabrics with high stretch, high recovery and low shrinkage can be produced.
Reference Example 3: Stretch Fabric containing double elastic fibers
[0077] This sample had the same fabric structure as in example 1. The only difference was
the use of core spun yarns in weft: 40D (44.44 dtex) T162B LYCRA
® fiber with 3.5X draft and 40D (44.44 dtex) Easyset LYCRA
® fiber with 3.5X draft. The warp yarn was 20 Ne (295.25 dtex) 100% cotton ring spun
yarn. 3/1 twill weaving pattern was applied. The finished fabric had weight (9.19g/m
2), 38.4.0 % stretch and 7.9 % growth in the weft direction. It is clearly shown, Easyset
LYCRA
® fiber in elastic core II maintains the fabrics stretch level while reducing the fabric
growth from 8.7% in example 1 to 7.9%.
[0078] Easyset LYCRA
® fiber can be heatset at about 170°C degree, which is about 20°C lower than the heatset
temperature of T162B LYCRA
® fiber. Therefore, when the fabrics are heatset in a temperature between 170°C and
190°C, the fabric got partially heatset. Only Easyset LYCRA
® fiber is set and T162B is not set. In this way, the fabric keeps better stretch and
recovery while the shrinkage keeps under certain level.
Reference Example 4: Stretch fabric with spandex and elastic polyolefin fiber
[0079] The warp yarn was 7.0 Ne (843.6 dtex) count and 8.4 Ne (702.98 dtex) count mixed
open end yarn. The warp yarn was indigo dyed before beaming. The weft yarn is 16Ne
(369.06 dtex) core spun yarn with 40D (44.44 dtex) T162B Lycra
® spandex and 40D (44.44 dtex) elastic polyolefin fiber. The Lycra
® fiber and elastic polyester fiber were drafted 3.5X during covering process. Table
3 lists the fabric properties. The fabric made from such yarns exhibited good cotton
hand, good stretch (47.8%) and good recovery (6.5% growth). All test results indicate
that the combination of spandex and elastic polyolefin filaments can produce good
fabric stretch and growth. Fabric has no grin through. Elastic filaments can't be
seen from both fabric surface and fabric back.
[0080] As compared with spandex, elastic polyolefin fiber or Lastol fiber has lower recovery
power, but better heat resistance, better chemical resistance, low fabric shrinkage
and good cotton hand touch feeling. The fabrics contained with both spandex and elastic
polyolefin can provide good stretch and good recovery with better heat resistance,
lower shrinkage and better chemical resistance, such as chlorine resistance in swimming
pool and denim bleaching processes.
Example 5: Stretch Fabric containing spandex and pre-covered elastic yarn
[0081] This sample had the same fabric structure as example 1. The difference was the core
spun yarn in weft direction, which containing one bare 40D (44.44 dtex) LYCRA
® fiber and one pre-covered elastic yarn (40D/34f Nylon/40D Lycra
® air covered yarn) in the core of the yarn. The draft of bare 40D LYCRA
® fiber is 1.8X and the draft of LYCRA
® fiber in pre-covered elastic yarn is 3.2X. This fabric used the same warp and structure
as Example 1. Also, the weaving and finishing process were the same as Example 1.
Table 3 summarizes the test results. We can see that this sample had good stretch
(35.9 %), good weft direction wash shrinkage (0.65 %) and good fabric growth (5.3%).
The fabric appearance and handle was excellent. After adding pre-covered elastic yarn
(40D/34f Nylon/40D Lycra
® fiber AJY yarn), the fabric growth remarkably reduced.
Example 6: Stretch fabric containing spandex and pre-covered elastic yarn
[0082] This sample had the same fabric structure as in example 5. The only difference was
the draft of 40D (44.44 dtex) bare LYCRA
® fiber during covering process. The bare LYCRA
® fiber draft is 3.5X while it was 1.8X in Example 5. The fabric weight was 8.96 oz/yd
2 (303.8 g/m
2), and the weft elongation was 37.8 %. The Fabric had very low growth (5.9%) in weft.
This sample further confirms that adding additional elastic composite yarn can produce
high performance stretch fabrics with low growth. Double elastic yarn makes the fabric
growth to 5.9% from 8.7% in Example 1. As compared with Example 5, the draft increase
also results in higher weight and stretch.
Example 7: Stretch denim containing spandex and pre-covered elastic yarn
[0083] This example had the same warp yarn and same fabric structure as Example 4. The warp
yarn was 7.0 Ne (843.6 dtex) count and 8.4 Ne (702.98 dtex) count mixed open end yarn.
The warp yarn was indigo dyed before beaming. The weft yarn is 16Ne (369.06 dtex)
core spun yarn with 40D (44.44 dtex) Lycra
® spandex and 50D/24f (50D = 55.55 dtex) polyester 40D LYCRA
® fiber air jet covered yarn. Lycra
® draft is 3.5X and 1.8X in bare and composite core. This sample is an innovation fabric.
Loom speed was 500 picks per minute at a pick level 44 Picks per inch. Table 3 summarizes
the test results. The test results show that after washing, this fabric had weight
(12.80 oz/yd
2 or 434 g/m
2), 35.3% weft stretch and 3.5% growth in weft.
Example 8: Stretch denim containing spandex and pre-covered elastic yarn
[0084] This example had the same warp yarn and same fabric structure as Example 7, except
the LYCRA
® fiber draft in pre-covered elastic yarn (2.6X draft in Example 8 vs.1.8X draft in
example 7). Table 3 summarizes the test results. It is clear that this sample had
good stretch (weft 40.4%) as compared with sample 7.
Reference Example 9: Stretch fabric with spandex and PBT stretch fiber
[0085] This example had the same warp yarn and same fabric structure as Example 7 and 8,
except using 50D/26f (50 D = 55.55 dtex) PBT stretch fiber as elastic core II fiber.
This bare 50D/26f PBT fiber has 40.23% recoverable stretch and 3.44% shrinkage tested
with ASTM D6720 Method. The elastic core I Lycra
® fiber was drafted 3.5X during covering process. Table 3 lists the fabric properties.
The fabric made from such yarns exhibited good cotton hand, good stretch (40.7%) and
good recovery (6.0% growth). All test results indicate that the combination of spandex
and no-elastomeric stretch filaments can produce good fabric stretch and growth. Fabric
has no grin through; elastic filaments can't be seen from both fabric surface and
fabric back.