BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to stretch nonwoven fabrics, more particularly such
fabrics comprising elastomeric fibers, a binder (especially binder fibers), and crimped
fibers.
Description of Background Art
[0002] Nonwoven fabrics have been disclosed that contain elastomeric polyurethane and polyetherester
fibers, for example United States Patent US 5238534 and Published Japanese Patent
Applications JP 43-026578, JP03-019952, and JP10-025621. However, such fabrics can
be unattractively heavy and can have poor, tacky hand. Nonwoven fabrics have also
been disclosed that contain crimped fibers, for example United States Patent US5102724
and Published Japanese Patent Applications JP02-091217 and JP05-171555, but they can
have poor, and anisotropic, stretch and recovery properties. Both these types of deficiencies
can make the nonwovens of the prior art unsatisfactory for direct contact with skin,
for example in diapers.
[0003] Cross-laid carded webs have been used to make machine- and cross-direction properties
similar, for example as disclosed in International Patent Application WO00/63478 and
in Published Japanese Patent Applications JP08-260313 and JP11-061617, but such operations
add cost, and the fabrics can be thick and can have poor hand, low flexibility, and/or
poor stretch and recovery properties.
[0004] Laminates of nonwoven webs and elastomeric materials have also been disclosed, for
example in Published Japanese Patent Application JP08-188950, but such fabrics, again,
can be unevenly thick and of low flexibility so that they do not satisfactorily hug
parts of the body.
[0005] Nonwovens comprising binder fibers have also been disclosed, for example in United
States Patent US5302443 and Published Japanese Patent Application JP2000-328416, but
such fabrics typically lack adequate stretch-and-recovery properties.
[0006] There is still a need for thin nonwovens having good hand and good stretch-and-recovery
properties.
SUMMARY OF THE INVENTION
[0007] The present invention provides a nonwoven fabric having isotropic recovery from extension
of at least about 55% and comprising a binder, about 3 to 50 weight percent bare elastomeric
staple fibers based on weight of the fabric, and crimped staple bicomponent fibers.
[0008] The invention also provides a method of manufacturing such a nonwoven fabric comprising
the steps of (a) providing staple spandex, staple latent crimp fibers which develop
crimp when heated, and binder fibers; (b) preparing a suspension of the spandex, the
latent crimp fibers and the binder fibers; (c) forming the suspension into a web by
a process selected from the group consisting of air-laid and wet-laid; (d) heating
the web to melt the binder fibers and bond the fibers; and (e) heating the web in
a relaxed state to develop crimp in the latent crimp fibers.
BRIEF DESCRIPTION OF THE FIGURES
[0009]
Figure 1 is a perspective view (Figure 1A) and a schematic detail (Figure 1B) showing
one embodiment of the nonwoven fabric of the invention.
Figure 2 shows enlarged cross-sectional schematic views taken along lines IIA-IIA
(Figure 2A) and IIB-IIB (Figure 2B) of Figure 1.
Figure 3 is a schematic view of a nonwoven fabric production apparatus.
Figure 4 schematically shows the web before heating (Figure 4A) and after heating
(Figure 4B).
DETAILED DESCRIPTION OF THE INVENTION
[0010] It has now been unexpectedly found that nonwoven fabrics comprising a binder, crimped
staple fibers, and bare elastomeric staple fibers have an unusual combination of good
hand as indicated by lack of tackiness, good recovery from extension after repeated
stretching even at low elastomeric fiber content, and low basis weight and thickness.
They are also flexible and have isotropic mechanical properties. The fabrics are well-suited
to articles having stretch properties, such as apparel interlinings, diapers, substrates
for external medications, wiping cloths, and packaging materials.
[0011] As used herein, "elastomeric fiber" means a bare (uncovered) staple fiber which,
free of diluents, has a break elongation in excess of 100% independent of any crimp
and which when stretched to twice its length, held for one minute, and then released,
retracts to less than 1.5 times its original length within one minute of being released.
Such fibers include, but are not limited to, rubber fiber, spandex, polyetherester
fiber, biconstituent fiber, and elastoester. "Spandex" means a manufactured fiber
in which the fiber-forming substance is a long chain synthetic polymer comprised of
at least 85% by weight of a segmented polyurethane. "Isotropic mechanical properties"
means that properties, such as tensile strength and recovery from extension, in the
cross-direction of the fabric are at least 80% of those in the machine-direction of
the fabric. "Biconstituent fiber" means a manufactured fiber having one component
of a first general class of polymer, for example a thermoplastic elastomer, and a
second component of a second general class of polymer, for example a thermoplastic
non-elastomer, both components being substantially continuous along the length of
the fiber; the fiber can have a concentric or eccentric sheath-core or side-by-side
construction. "Bicomponent fiber" means a fiber in which two polymers of the same
general class are in a side-by-side or eccentric sheath-core relationship and includes
both crimped fibers and fibers with latent crimp that has not yet been realized.
[0012] Referring first to Figure 1A, one embodiment of nonwoven stretch fabric 10 of the
invention is schematically illustrated. The detail in Figure 1 B reveals that the
fabric comprises elastomeric fibers 12, crimped fibers 14, and a binder 16 which bonds
elastomeric fibers 12 to crimped fibers 14, for example at points of contact 18 therebetween
so that the stretch and recovery properties of the elastomeric and the crimped fibers
are not impaired.
[0013] Referring now to Figures 2A and 2B, cross-sections of one embodiment of the nonwoven
stretch fabric of the invention are shown schematically to comprise elastomeric fibers
12, crimped fibers 14, and a binder 16 . Crimped fibers 14 are shown as side-by-side
bicomponent fibers comprising components 14x and 14y. Binder 16 is shown as a sheath-core
binder fiber comprising sheath 16x and core 16y.
[0014] The nonwoven fabric of the invention comprises about 3 to 50 weight percent, preferably
about 5 to 30 weight percent, bare elastomeric staple fibers, based on the weight
of the fabric. When the amount of elastomeric fiber is less than about 3 weight percent,
the ability of the fabric to recover from extension can be unsatisfactory, and when
the amount of elastomeric fibers is more than about 50 weight percent, the elastomeric
nonwoven fabric can have an unpleasant, sticky hand.
[0015] The fabric preferably further comprises about 40 to 80 weight percent crimped staple
fibers, more preferably about 50 to 70 weight percent, based on the weight of the
fabric. At an amount less than about 40 weight percent, the nonwoven fabric can have
decreased stretch properties, poor flexibility, and a hard hand. At an amount greater
than about 80 weight percent, the fabric can have poor mechanical strength and thus
a diminished ability to recover from extension when repeatedly stretched.
[0016] The fabric preferably also comprises about 10 to 50 weight percent of a binder, more
preferably about 20 to 40 weight percent, based on the weight of the fabric. At an
amount less than about 10 weight percent, the fabric can have poor mechanical strength,
and at more than about 50 weight percent, the stretch properties can be compromised,
and the fabric can have an unacceptably hard hand.
[0017] The fabric of the invention has a recovery from extension of at least about 55% and
can have a thickness of at least about 50 microns and less than 135 microns.
[0018] Examples of useful elastomeric fibers include spandex, polyetherester elastomeric
fibers, and polyetheramide elastomeric fibers. Natural rubber, synthetic rubber, and
semi-synthetic rubber can also be used, as can biconstituent fibers. Spandex is preferred,
and spandex comprising polyurethaneurea is more preferred. Polyurethaneureas can typically
be prepared from a polymeric glycol, a diisocyanate, and a diamine or alcoholamine
chain extender.
[0019] The linear density of the staple elastomeric fibers can be about 0.5 to 40 decitex,
typically about 1 to 30 decitex. At less than about 0.5 decitex, the fibers can have
too low mechanical strength, and at more than about 40 decitex, the number of elastomeric
fibers making up the web per unit surface area is reduced; outside of such a range,
the fabric can have a reduced recovery from extension. The staple elastomeric fibers
can have a length of about 3 to 50 mm, typically about 5 to 30 mm. At a length of
less than about 3 mm, the fabric can have low mechanical strength, and at a length
greater than about 50 mm, it can be difficult to achieve a uniform distribution of
the fibers in the fabric web. No particular limitation is imposed on the cross-sectional
shape of the elastomeric fibers, which can have a round cross-section as shown in
Figure 2 or a modified cross-section, for example triangular or flattened.
[0020] Useful crimped staple fibers can be polyester fibers, polyolefin fibers, acrylic
fibers, and polyamide fibers. Crimp can be developed in such fibers from the corresponding
latent crimp fibers by heat treatment under relaxed conditions after the elastomeric
fibers, latent crimp fibers, and binder have been mixed, and preferably after a web
has been formed therefrom. The latent crimp and corresponding crimped fibers have
a bicomponent construction, in which useful polymer pairs include polyethylene terephthalate
and poly(ethylene terephthalate-co-isophthalate); poly(ethylene terephthalate) and
poly(trimethylene terephthalate); poly(ethylene terephthalate-co-isophthalate) and
poly(trimethylene terepthalate); poly(ethylene terephthalate) and poly(tetramethylene
terephthalate); poly(hexamethylene adipamide) and poly(hexamethylene-co-2-methyl-1,5-diaminopentamethylene
adipamide); and the like.
[0021] The latent crimp fibers can have a crimp development temperature which is lower than
the softening temperature of the elastomeric fibers. If the crimp development temperature
of the latent crimp fibers is higher than the softening temperature of the elastomeric
fibers, the ability of the elastomeric fibers to recover from extension can be compromised
during crimp development.
[0022] The crimped fibers can have a linear density of about 0.2 to 20 decitex per filament,
typically about 0.5 to 10 decitex per filament. If the crimped fibers have a linear
density of less than about 0.2 decitex per filament, the stretch properties of the
fabric can be inadequate. At a linear density of more than about 20 decitex per filament,
the fabric can be stiff and have a poor hand. As with the elastomeric fibers, the
crimped fibers can have a length of about 3 to 50 mm, typically about 5 to 30 mm.
No particular limitation is imposed on the cross-section of the crimped fibers, and
they can have a round cross-section as shown in Figure 2, or a triangular, flattened,
or a 'snowman' cross-section.
[0023] The binder can be a thermoplastic resin such as polyester, polyolefin, acrylic or
polyamide. When heated and melted, then cooled and solidified, it bonds the fibers
of the web (precursor to the fabric of the invention) together. The melting temperature
of the binder can be lower than the softening temperature of the elastomeric fibers
so that the ability of the elastomeric fibers to recover from extension is not compromised
when the precursor web is heated to melt the binder. There is no particular limitation
on the shape of the binder, and it can be a liquid, a powder, or a fiber as shown
in Figure 1 and 2. A fiber shape is preferred, for example having a concentric or
eccentric sheath-core construction in which the thermoplastic sheath melts at a lower
temperature than the core. Examples of such fibers include those in which the sheath
is poly(ethylene terephthalate-co-isophthalate) and the core is poly(ethylene terephthalate).
As with the elastomeric fibers, the binder fibers can have a length of about 3 to
50 mm, typically about 5 to 30 mm.
[0024] The polymers of which the fibers are comprised can be copolymers, comprising additional
monomers that improve their preparation, functionality, or processing, for example
for improved dyeability (for example 5-sodium-sulfoisophthalate in polyesters), optimized
crimp levels, melt viscosity, adhesion, resistance to environmental degradation, and
the like, provided the benefits of the invention are not compromised. Similarly, the
fibers can contain additives such as ultraviolet light absorbers, antioxidants, anti-tack
agents, lubricants, hindered phenolic stabilizers, hindered amine stabilizers, inorganic
pigments such as titanium oxide, zinc oxide, carbon black and the like, antimicrobial
agents containing silver, zinc, or compounds thereof, deodorants, fragrances, and
anti-static agents such as poly(ethylene oxide), as long as the benefits of the invention
are not adversely affected.
[0025] In the process of the invention, a suspension of staple elastomeric fibers (preferably
spandex), staple latent crimp fibers, and a binder (preferably binder fibers) is prepared.
Optionally, a dispersing agent and/or a thickener can be added to the suspension.
The suspension is formed into a web by a wet-lay method or an air-lay method, and
the web is heated to melt the binder and to crimp the latent crimp fibers. The heating
step is preferably carried out with little or no pressure or tension (that is, with
the web in a relaxed state) so that the latent crimp fibers are not prevented from
crimping, and at a temperature lower than the softening temperature of the elastomeric
fibers. The heating step can be carried out in two steps, one for bonding the fibers
and one for developing crimp in the latent crimp fibers, or it can be carried out
in a single step to accomplish both bonding and crimping.
[0026] One embodiment of the process of the invention is described below using the apparatus
illustrated schematically in Figure 3. In this particular embodiment, latent crimp
fibers and a fibrous binder are used.
[0027] First, in a fiber suspension preparation step ("A" in Figure 3), the elastomeric
fibers, the latent crimp fibers, and the binder fiber can be added to water and mixed
in a rotary device 20 such as a pulper to disaggregate the fibers and make a suspension
of fibers in the water so that the suspension has a fiber concentration of about 0.1
to 3 wt%. The suspension can be delivered by pumps ("P") to mixing tank 22 and then
to machine tank 24. Optionally, to aid in dispersing the fibers in the suspension
preparation step, a dispersing agent, for example a nonionic polyether-based dispersing
agent, a weakly cationic polyester/polyether dispersing agent, or the like, can be
added for example in an amount of 0.01 to 10% by weight based on the total fiber weight.
Optionally, a watersoluble thickener can also be added, for example in an amount of
5 to 50 ppm (thickener solids basis) based on the weight of the water.
[0028] Next, in a web-forming step ("B" in Figure 3), the suspension from machine tank 24
can be fed by a pump ("P") to wire conveyor belt 26a of short-screen papermaking machine
26 and dewatered on wire conveyor belt 26a to form a web on the belt. At this step,
Figure 4A schematically illustrates one embodiment of the web, which comprises elastomeric
fibers 12, latent crimp fibers 14, and binder fibers 16. The web on wire conveyor
belt 26a can then be transferred onto felt 28, which can have a smoother surface than
wire conveyor belt 26a.
[0029] Then, in a bonding step ("C" in Figure 3), the web on felt 28 can be transferred
onto cylinder-type dryer 30, which can have a smoother surface than felt 28, and where
the web can be heated to a predetermined temperature sufficient to melt sheath 16x
of binder fiber 16 within the web. The web can then be pulled away from cylinder-type
dryer 30 and cooled to solidify the melted binder so that fibers 12 and 14 are bonded
together, for example at points 18 (see Figure 1B), and a nonwoven fabric is formed.
[0030] In a crimp development step ("D" in Figure 3), the fabric can be fed by feed rolls
31 to heating oven 32 which can supply heat for example as infrared or far-infrared
radiation. The temperature within heating oven 32 can be lower than the softening
temperature of elastomeric fibers 12 but high enough to make fibers 14 develop crimp.
To allow crimp to develop, it is preferable for the fabric in heated oven 32 to be
in a relaxed state. Accordingly, the peripheral velocities of feed rolls 31 and take-off
rolls 34 can be adjusted so as not to apply tension to the fabric. Figure 4B schematically
illustrates one embodiment of the fabric at this step, in which the fibers are indicating
according to the numbering system used for Figure 4A.
[0031] Finally, the fabric can be wound up on winder 36 ("E" in Figure 3).
[0032] The foregoing steps and apparatus were used in the Examples, but they illustrate
only one embodiment of the invention and can be modified in a number of ways. For
example, the tanks which hold the suspension (mixing tank 22 and machine tank 24)
may instead consist of one tank, or three or more tanks. In the web-forming step,
instead of a short-screen papermaking machines, other types of papermaking machines
may be used, such as a Fourdrinier machine or a cylinder machine. In the fiber suspension
preparation step and the web-forming step, other liquids such as ethanol may be used
as the medium instead of water. Moreover, the length and number of felts which carry
the web may be varied, or one or more rolls may be used instead of the felt. In addition,
a pressing step in which the web is squeezed under applied pressure may be separately
provided between the web-forming step and the bonding step. In the bonding step, other
types of heaters (e.g., air dryer, air through-circulation dryer, infrared dryer,
suction dryer) may be used instead of a cylinder-type dryer. The bonding step and
the crimp development step may be carried out at separate times or places, or these
steps may be integrated so as to accomplish bonding and crimp development at the same
time.
[0033] A step to adjust the hand or surface properties of the nonwoven stretch fabric by
passing the fabric between calender rolls (optionally with an embossing surface) (not
shown) can be provided between the crimp development step and the wind-up step. In
the fiber suspension preparation step and the web-forming step, an air-lay step can
be employed instead of a wet-lay step. In an air-lay process, the fibers can be disaggregated
and dispersed with an opening machine (not shown) in the fiber suspension preparation
step, and a mixed suspension of the fibers can be prepared with a fiber blending machine
(not shown). In the web-forming step, a random carding machine can be used to improve
the randomness of the fiber orientations.
[0034] In the Examples, fabric properties were measured by the following methods. Basis
weight and thickness were measured in accordance with Japanese Industrial Standards
test number JIS L-1096, and tensile strength was measured in accordance with JIS P-8113.
The recovery from extension was measured by determining the length of a test specimen
before testing (L
o), subjecting the specimen to five 15% extension-and-recovery cycles on an Instron
tester, determining the length of the specimen at the fifth extension (L
e), and after the fifth recovery (L
f). Percent recovery from extension (R
e) was calculated from the following equation:
[0035] In Table I, "Comp." means Comparison, and tensile strength is reported in kiloNewtons
per meter.
EXAMPLE 1
[0036] The elastomeric fibers used were spandex (Lycra® T-127C, a registered trademark of
DuPont-Toray Co., Ltd.) having a linear density of 7 decitex per filament, a fiber
length of 6 mm, and a softening temperature of about 180°C. The latent crimp fibers
were poly(ethylene terephthalate) + poly(ethylene terephthalate) copolymer bicomponent
fibers (T81, made by Unitika Fiber Co., Ltd.) having a linear density of 1.7 decitex
per filament, a fiber length of 5 mm, and a crimp development temperature of at least
about 140°C. The binder was sheath-core binder fibers of poly(ethylene terephthalate)
and poly(ethylene terephthalate-co-isophthalate) (30% isophthalate) ("Melty" 4080,
manufactured by Unitika Fiber Co., Ltd.) having a linear density of 1.1 decitex per
filament, a fiber length of 3 mm, and a sheath melting temperature of about 110°C.
[0037] Five weight percent of the spandex, 65 wt % of the latent crimp polyester fibers,
and 30 wt % of the polyester sheath-core binder fibers were dispersed in water using
a pulper. Next, 10 ppm (thickener solids, based on the weight of the water) of polyacrylamide
thickener ("Myresin" R10L, manufactured by Mitsui-Cytec, Ltd., 40% emulsion) and 1
wt % (based on total fiber weight) of a modified nonionic polyesterether dispersant
(MDP-002, made by Takemoto Yushi KK) were added, giving a suspension having a fiber
concentration of about 0.5 wt %.
[0038] The resulting suspension was wet-laid with a short-screen papermaking machine so
that the fibers were substantially randomly oriented, then heated in a cylinder-type
dryer having a surface temperature of 120°C to give a web having a basis weight of
22 g/m
2. The web was then passed in a relaxed state through an infrared heater set to 160°C
to develop crimp in the latent crimp fiber. Next, the web was pressed with a cylindrical
roll at a pressure of 10 kgf/cm, yielding the nonwoven fabric whose properties are
shown in Table 1.
Example 2
[0039] A nonwoven fabric was produced under the same conditions as in Example 1 except that
the proportion of spandex was 10 wt % and the proportion of latent crimp polyester
fibers was 60 wt %. The properties of the resulting fabric are shown in Table 1.
Example 3
[0040] A nonwoven fabric was produced under the same conditions as in Example 1 except that
the proportion of spandex was 20 wt % and the proportion of latent crimp polyester
fibers was 50 wt %. The properties of the resulting fabric are shown in Table 1.
Comparison Example 1
[0041] A nonwoven sfabric was obtained in the same manner as in Example 1 except that no
spandex used. The properties of the resulting fabric are shown in Table 1.
Table 1
|
Example 1 |
Example 2 |
Example 3 |
Comp. Example 1 |
Fiber proportions (wt %) |
|
|
|
|
Spandex |
5 |
10 |
20 |
0 |
Crimped polyester bicomponent fibers |
65 |
60 |
50 |
70 |
Polyester binder fibers |
30 |
30 |
30 |
30 |
Fabric properties |
|
|
|
|
Basis weight (g/m2) |
42 |
40 |
38 |
44 |
Thickness (microns) |
119 |
132 |
124 |
137 |
Tensile strength, MD (kN/m) |
1.1 |
1.0 |
0.9 |
1.1 |
Tensile strength, CD (kN/m) |
1.0 |
0.9 |
0.8 |
1.0 |
Recovery from extension, MD (%) |
69 |
73 |
86 |
50 |
Recovery from extension, CD (%) |
63 |
67 |
79 |
46 |
[0042] The data in Table 1 show that the nonwoven stretch fabrics obtained in Examples 1,
2 and 3 had isotropic recovery from extension which was also very high, compared to
the fabric obtained in the Comparison Example 1, which was unsuitable as a stretch
fabric. The fabrics of the invention also had good hand (low tackiness) and good flexibility.
1. A nonwoven fabric having isotropic recovery from extension of at least 55% and comprising
a binder, 3 to 50 weight percent bare elastomeric staple fibers based on weight of
the fabric, and crimped staple bicomponent fibers comprising polymers in a relationship
selected from the group consisting of side-by-side and eccentric sheath-core.
2. The fabric of claim 1 comprising 5 to 30 weight percent bare elastomeric fiber, based
on weight of the fabric.
3. The fabric of claim 1 wherein the crimped fibers comprise polymer pairs selected from
the group consisting of:
poly(ethylene terephthalate) and poly(trimethylene terephthalate), and
poly(ethylene terephthalate) and poly(ethylene terephthalate-co-isophthalate),
and wherein the binder is a binder fiber present at 10 to 50 weight percent, based
on weight of the fabric and having a melting temperature lower than a softening temperature
of the elastomeric fibers.
4. The abric of claim 1 wherein the elastomeric fibers are spandex and the crimped fibers
are present at 40 to 80 weight percent, based on weight of fabric.
5. The abric of claim 1 wherein the bare elastomeric fibers are polyurethaneurea spandex
and the fabric has a thickness of at least 50 microns and less than 135 microns.
6. The fabric of claim 1 wherein the elastomeric fibers have a linear density of 0.5
to 40 decitex per filament, the binder is a fiber, and the elastomeric fibers, the
crimped fibers, and the binder fibers have a length of 3 to 50 mm.
7. A method of manufacturing the nonwoven fabric of claim 1 comprising the steps of:
(a) providing staple spandex, staple latent crimp fibers which develop crimp when
heated, and binder fibers;
(b) preparing a suspension of the spandex, the latent crimp fibers, and the binder
fibers;
(c) forming the suspension into a web by a process selected from the group consisting
of air-lay and wet-lay;
(d) heating the web to melt the binder fiber and bond the fibers; and
(e) heating the web in a relaxed state to develop crimp in the latent crimp fibers.
8. The method of claim 7 wherein suspension preparation step (b) is carried out so that
the latent crimp fibers are present at a level corresponding to 40 to 80 weight percent
based on weight of the fabric, and heating steps (d) and (e) are carried out as a
single step.
9. The method of claim 7 wherein heating steps (d) and (e) are carried out at temperatures
lower than the softening temperature of the spandex.
10. An article comprising the fabric of claim 1 made by the method of claim 7 and selected
from the group consisting of apparel interlinings, diapers, substrates for external
medications, wiping cloths, and packaging materials.
1. Vliesstoff mit isotroper Dehnungserholung von mindestens 55% und aufweisend ein Bindemittel,
3% bis 50 Gew.% bezogen auf das Gewicht des textilen Flächengebildes nicht umsponnene
elastomere Stapelfasern und gekräuselte Bikomponentenstapelfasern, die Polymere in
einer Beziehung aufweisen, ausgewählt aus der Gruppe, bestehend aus Seite-an-Seite
und exzentrischen Mantel-Kern.
2. Textiles Flächengebilde nach Anspruch 1, aufweisend 5% bis 30 Gew.% bezogen auf das
Gewicht des textilen Flächengebildes nicht umsponnene elastomere Faser.
3. Textiles Flächengebilde nach Anspruch 1, worin die gekräuselten Fasern Polymer-Paare
aufweisen, die ausgewählt sind aus der Gruppe, bestehend aus:
Poly(ethylenterephthalat) und Poly(trimethylenterephthalat) sowie
Poly(ethylenterephthalat) und Poly(ethylenterephthalat-co-isophthalat),
und worin das Bindemittel eine Binderfaser ist und bezogen auf das Gewicht des
textilen Flächengebildes mit 10% bis 50 Gew.% vorliegt und eine Schmelztemperatur
hat, die kleiner ist als die Erweichungstemperatur der elastomeren Fasern.
4. Textiles Flächengebilde nach Anspruch 1, worin die elastomeren Fasern Spandex sind
und die gekräuselten Fasern bezogen auf das Gewicht des textilen Flächengebildes mit
40% bis 80 Gew.% vorliegen.
5. Textiles Flächengebilde nach Anspruch 1, worin die nicht umsponnenen elastomeren Fasern
Polyurethanhamstoff-Spandex sind und das textile Flächengebilde eine Dicke von mindestens
etwa 50 Mikrometer und weniger als 135 Mikrometer hat.
6. Textiles Flächengebilde nach Anspruch 1, worin die elastomeren Fasern eine längenbezogene
Masse von 0,5 bis 40 Decitex pro Filament haben, das Bindemittel eine Faser ist und
die elastomeren Fasern, die gekräuselten Fasern und die Binderfasern eine Länge von
3 bis 50 mm haben.
7. Verfahren zum Herstellen des Vliesstoffes nach Anspruch 1, umfassend die Schritte:
(a) Stapel-Spandex, Stapelfasern mit latenter Kräuselung, die die Kräuselung beim
Erhitzen entwickeln, sowie Binderfasern;
(b) Herstellen einer Suspension aus dem Spandex, den Fasern mit latenter Kräuselung
und den Binderfasern;
(c) Formen der Suspension zu einer Bahn mit Hilfe eines Prozesses, der ausgewählt
ist aus der Gruppe, bestehend aus dem Luftauflegen und dem Nassauflegen;
(d) Erhitzen der Bahn zum Schmelzen der Binderfaser und Binden der Fasern;
(e) Erhitzen der Bahn in einem erholten Zustand, um in den Fasern mit latenter Kräuselung
die Kräuselung zu entwickeln.
8. Verfahren nach Anspruch 7, worin der Schritt (b) zur Herstellung einer Suspension
so ausgeführt wird, dass die Fasern mit latenter Kräuselung in einer Menge vorliegen,
die bezogen auf das Gewicht des textilen Flächengebildes 40% bis 80 Gew.% entspricht,
und die Schritte (d) und (e) des Erhitzens als ein einziger Schritt ausgeführt werden.
9. Verfahren nach Anspruch 7, worin die Schritte des Erhitzens (d) und (e) bei Temperaturen
unterhalb der Erweichungstemperatur des Spandex ausgeführt werden.
10. Artikel, aufweisend das textile Flächengebilde nach Anspruch 1, das mit Hilfe des
Verfahrens nach Anspruch 7 hergestellt ist, und ausgewählt ist aus der Gruppe, bestehend
aus Bekleidungsfutterstoffen, Windeln, Substraten für äußere Arzneimittelanwendungen,
Wischtüchern und Verpackungsmaterialien.
1. Tissu non tissé présentant une récupération isotrope à partir d'une extension d'au
moins 55% et comprenant un liant, de 3 à 50 pour-cent en poids de fibres courtes élastomères
nues sur la base du poids du tissu, et des fibres à deux composants courtes frisées
comprenant des polymères en une relation choisie dans le groupe constitué de côte
à côte et d'enveloppe-âme excentrique.
2. Tissu suivant la revendication 1, comprenant de 5 à 30 pour-cent en poids de fibre
élastomère nue, sur la base du poids du tissu.
3. Tissu suivant la revendication 1, dans lequel les fibres frisées comprennent des paires
de polymères choisies dans le groupe constitué:
de poly(éthylène téréphtalate) et de poly(triméthylène téréphtalate), et
de poly(éthylène téréphtalate) et de poly(éthylène téréphtalate-co-isophtalate),
et dans lequel le liant est une fibre liante présente à 10 à 50 pour-cent en poids,
sur la base du poids du tissu et avec une température de fusion inférieure à la température
de ramollissement des fibres élastomères.
4. Tissu suivant la revendication 1, dans lequel les fibres élastomères sont un spandex
et les fibres frisées sont présentes à 40 à 80 pour-cent en poids, sur la base du
poids du tissu.
5. Tissu suivant la revendication 1, dans lequel les fibres élastomères nues sont un
spandex de polyuréthane-urée et le tissu possède une épaisseur d'au moins 50 microns
et inférieure à 135 microns.
6. Tissu suivant la revendication 1, dans lequel les fibres élastomères présentent une
densité linéaire de 0,5 à 40 décitex par filament, le liant est une fibre et les fibres
élastomères, les fibres frisées et les fibres liantes possèdent une longueur de 3
à 50 mm.
7. Procédé pour la fabrication du tissu non tissé suivant la revendication 1, comprenant
les étapes:
(a) de fourniture d'un spandex court, de fibres à frisure latente courtes qui développent
une frisure lorsqu'elles sont chauffées, et de fibres liantes;
(b) de préparation d'une suspension du spandex, des fibres à frisure latente et des
fibres liantes;
(c) de transformation de la suspension en une bande par un procédé choisi dans le
groupe constitué de dépôt à l'air et de dépôt humide;
(d) de chauffage de la bande pour fondre la fibre liante et lier les fibres; et
(e) de chauffage de la bande dans un état relâché pour développer une frisure dans
les fibres à frisure latente.
8. Procédé suivant la revendication 7, dans lequel l'étape de préparation d'une suspension
(b) est réalisée de sorte que les fibres à frisure latente sont présentes à un niveau
correspondant à 40 à 80 pour-cent en poids sur la base du poids du tissu et les étapes
de chauffage (d) et (e) sont réalisées sous forme d'une étape unique.
9. Procédé suivant la revendication 7, dans lequel les étapes de chauffage (d) et (e)
sont réalisées à des températures inférieures à la température de ramollissement du
spandex.
10. Article comprenant le tissu suivant la revendication 1, fabriqué par le procédé suivant
la revendication 7 et choisi dans le groupe constitué de doublures intermédiaires
d'habillement, de langes, de substrats pour des médications externes, d'étoffes d'essuyage
et de matériaux d'emballage.