U.S. patent application number 09/253810 was filed with the patent office on 2002-07-11 for composite elastomeric yarns and fabric.
Invention is credited to BRUNER, JEFFREY W..
Application Number | 20020088501 09/253810 |
Document ID | / |
Family ID | 26756863 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020088501 |
Kind Code |
A1 |
BRUNER, JEFFREY W. |
July 11, 2002 |
COMPOSITE ELASTOMERIC YARNS AND FABRIC
Abstract
The present invention relates to composite elastomeric yarns and
fabrics, to methods of making same, and to articles in which such
yarns and fabrics are used. The composite yarns of the present
invention comprise a elastomeric core, an elastomeric thermoplastic
sheath disposed about the core and, preferably, fibers mechanically
anchored in the sheath. The composite fabrics of the present
invention comprise the composite yarns of the present invention and
conventional fibers arranged to form a fabric.
Inventors: |
BRUNER, JEFFREY W.;
(GREENSBORO, NC) |
Correspondence
Address: |
JOSHUA R SLAVITT ESQ
SYNNESTVEDT & LECHNER LLP
2600 ARAMARK TOWER
1101 MARKET STREET
PHILADELPHIA
PA
19107
|
Family ID: |
26756863 |
Appl. No.: |
09/253810 |
Filed: |
February 19, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09253810 |
Feb 19, 1999 |
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08775610 |
Dec 31, 1996 |
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60075439 |
Feb 20, 1998 |
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Current U.S.
Class: |
139/2 ; 139/3;
139/391; 139/395; 139/399; 428/93; 428/95; 428/96 |
Current CPC
Class: |
D03D 27/00 20130101;
Y10T 428/23986 20150401; Y10T 428/23979 20150401; D02G 3/32
20130101; D02G 3/408 20130101; Y10T 428/23964 20150401 |
Class at
Publication: |
139/2 ; 428/95;
428/96; 428/93; 139/3; 139/391; 139/395; 139/399 |
International
Class: |
D05C 017/00; D03D
027/00; D03D 027/18 |
Claims
I claim:
1. A composite fabric, comprising an arrangement of fibers and
composite yarns wherein the composite yarns each comprise an
elastomeric core and an elastomeric thermoplastic sheath disposed
about the core wherein the melting point temperature of the sheath
is at least about 10.degree. C. lower than the melting point
temperature of the core, and wherein the fibers are anchored in the
sheath of the composite yarns.
2. The composite fabric of claim 1 wherein the fabric comprises
ground warp yarns, filling yarns and pile.
3. The composite fabric of claim 2 wherein the ground warp yarns
comprise composite yarns.
4. The composite fabric of claim 2 wherein the filling yarns
comprise composite yarns.
5. The composite fabric of claim 2 wherein the ground warp yarns
and the filling yarns comprise composite yarns.
6. The composite fabric of claim 2 wherein the pile comprises
conventional yarns.
7. The composite fabric of claim 2 wherein the ground warp yarns
consist essentially of composite yarns.
8. The composite fabric of claim 2 wherein the filling yarns
consist essentially of composite yarns.
9. The composite fabric of claim 2 wherein the ground warp yarns
and the filling yarns consist essentially of composite yarns.
10. The composite fabric of claim 6 wherein the conventional yarns
are interlaced with respect to the ground warp yarns or filling
yarns or both in a "V" or "W" configuration wherein the
conventional yarns are wrapped around either one or three composite
yarns of the ground warp yarns or the filling yarns or both.
11. A composite pile fabric, comprising an arrangement of composite
yarns as ground warp yarns and filling yarns and conventional yarns
as pile wherein the composite yarns each comprise an elastomeric
core and an elastomeric thermoplastic sheath disposed about the
core wherein the melting point temperature of the sheath is at
least about 50.degree. C. to about 75.degree. C. lower than the
melting point temperature of the core, and wherein the conventional
yarns are anchored in the sheath of the composite yarns.
12. A method of making a composite fabric comprising the steps of:
forming an arrangement of fibers and composite yarns wherein the
composite yarns comprise an elastomeric core and an elastomeric
thermoplastic sheath disposed about the core wherein the melting
point temperature of the sheath is at least about 10.degree. C.
lower than the melting point temperature of the core; heating the
arrangement of fibers and composite yarns to a temperature above
that of the melting point temperature of the sheath of the
composite yarns but below that of the melting point temperature of
the core of the composite yarns; and cooling the composite
fabric.
13. The method of claim 12 wherein the melting point temperature of
the sheath is at least about 50.degree. C. to about 75.degree. C.
lower than the melting point temperature of the core.
14. The method of claim 12 wherein the forming step comprises
weaving.
15. The method of claim 12 wherein the forming step comprises pile
weaving whereby ground warp yarns and filling yarns comprising the
composite yarns are interlaced with a pile of conventional
fibers.
16. The method of claim 15 wherein the pile is interlaced in a "V"
or "W" configuration so the pile are wrapped around either one or
three composite yarns of the ground warp yarns or the filling yarns
or both.
17. A method of making a composite pile fabric comprising the steps
of: forming an arrangement of composite yarns as ground warp yarns
and filling yarns and conventional yarns as pile wherein the
composite yarns each comprise an elastomeric core and an
elastomeric thermoplastic sheath disposed about the core wherein
the melting point temperature of the sheath is at least about
50.degree. C. to about 75.degree. C. lower than the melting point
temperature of the core; heating the arrangement of fibers and
composite yarns to a temperature above that of the melting point
temperature of the sheath of the composite yarns but below that of
the melting point temperature of the core of the composite yarns;
and cooling the composite fabric.
Description
BACKGROUND OF THE INVENTION
[0001] In the past, elastomeric yarns used to produce fabrics
having elastomeric properties have typically included rubber and
elastomeric polyurethanes, such as spandex, which possess high
coefficients of friction. As a result, they are difficult to handle
in typical textile yarn and fabric manufacturing processes and are
uncomfortable when in direct contact with the human body.
Accordingly, it has been necessary to cover, coat or in some other
manner conceal the rubber or polyurethanes in the yarn or fabric
structure to provide the desired aesthetic, design, comfort, wear
and durability characteristics when used in most apparel, home
furnishings, medical, automotive, air and marine craft
applications, as well as other industrial fabric applications.
[0002] In automotive, air and marine craft applications,
elastomeric yarns have been incorporated in fabrics used to cover
vehicle seats. Vehicle seats found in the various forms of ground,
air and marine transportation have often been constructed from
varying combinations of bulky polyurethane stuffing material or
molded foam cushioning which is then mounted on wire frames or
stamped metal pans and covered with fabric. The fabric is typically
cut and sewn to size to contain and protect the materials contained
within the seat as well as provide a comfortable, durable and
attractive finish suitable for the interior design scheme of the
vehicle. Depending on the combination of materials chosen, springs
or elastic straps are also often used in the seat to provide a
vehicle seating assembly with greater static and dynamic support
characteristics, as well as passenger comfort. In such seating
assemblies, however, the extensive use of foam cushioning, stuffing
material and springs or elastic straps adds significantly to the
weight of the finished product which is undesired in vehicle
applications where fuel economy is often a goal. Further, the use
of varying combinations of these separate components results in
seat assemblies having higher costs of materials and, because of
complicated assembly procedures, greater labor costs as well.
[0003] While thin profile seats have been developed, they have not
provided the aesthetic qualities that are desired in many furniture
fabrics. An example of such thin profile seats is found in Stumpf,
et al. (PCT Application No. PCT/US93/05731), which is incorporated
herein by reference, wherein an office chair is disclosed.
[0004] It is therefore an object of the present invention to
provide a composite yarn having elastomeric characteristics.
[0005] It is another object of the present invention to provide a
composite elastomeric yarn suitable for use in fabrics which offers
support and comfort while allowing for significant reduction in the
need for foam materials, springs or elastic straps.
[0006] It is still another object of the present invention to
provide a composite elastomeric yarn which can accommodate a wide
variety of surface textures and fiber densities.
[0007] It is yet another object of the present invention to provide
a method of forming composite elastomeric yarns which are suitable
for use in supportive and comfortable fabrics which can accommodate
a wide variety of surface textures and fiber densities.
[0008] It is still a further object of the present invention to
provide a method of forming composite elastomeric yarns which are
suitable for use in vehicle seat fabrics.
[0009] It is yet a further object of the present invention to
provide a method of forming a composite elastomeric fabric which is
suitable for use in vehicle seats.
SUMMARY OF THE INVENTION
[0010] The present invention relates to composite elastomeric yarns
and fabrics, to methods of making same, and to articles in which
such yarns and fabrics are used. The composite yarns of the present
invention comprise a elastomeric core, an elastomeric thermoplastic
sheath disposed about the core. The composite yarns also preferably
include fibers mechanically anchored in the sheath. An important
aspect of certain embodiments of the present invention is the
requirement that the polymeric core is a thermoplastic polymeric
core and that the melting point temperature of the material
comprising the sheath is at least about 10.degree. C., and
preferably from about 50.degree. C. to about 75.degree. C., lower
than the melting point temperature of the material comprising the
core.
[0011] The fabrics of the present invention comprise the composite
yarns of the present invention, preferably in combination with
conventional yarns or fibers, arranged to form a composite fabric.
The composite fabric of the present invention may be in any of a
variety of forms well known in the art including woven, knit,
braided or felted. Preferably, the composite fabric will be a woven
pile fabric in which the ground warp and the filling yarn comprise
composite yarns and the pile, whether a warp or a filling pile,
comprises conventional yarns or fibers. An important aspect of the
composite fabrics of the present invention is that the conventional
yarns or fibers are not only arranged together with the composite
yarns but are also mechanically anchored in the composite yarns. As
used herein, the term "conventional yarns or fibers" means yarns or
fibers which provide the fabric with the desired texture and/or
aesthetic qualities, and is invented to include not only fibers and
yarns known and used for this purpose, but also fibers and yarns of
the present invention adopted for this purpose.
[0012] The method of forming the composite yarns comprises the
steps of:
[0013] providing a composite elastomeric yarn comprising an
elastomeric core and an elastomeric thermoplastic sheath disposed
about the core wherein the melting point temperature of the sheath
is at least about 10.degree. C. lower than the melting point
temperature of the core;
[0014] heating the composite elastomeric yarn to a temperature at
or above about the melting point temperature of the sheath but
below the melting point temperature of the core; disposing fibers
in intimate mechanical contact with the sheath; and cooling the
composite elastomeric yarn to mechanically anchor said fibers in
said sheath. In certain preferred embodiments, the methods further
comprise stretching the composite elastomeric yarn from about 10%
to about 500% beyond the relaxed state prior to the step of
disposing said fibers. This preferred method enhances the ability
of the manufacturer to vary the fiber density and/or bulk of the
resulting composite yarn.
[0015] The method of forming the composite fabrics comprises the
steps of: forming a fabric of conventional yarns or fibers and
composite yarns comprising an elastomeric core and an elastomeric
thermoplastic sheath disposed about the core wherein the melting
point temperature of the sheath is at least about 10.degree. C.
lower than the melting point temperature of the core and;
[0016] heating the composite fabric to a temperature at or above
about the melting point temperature of the sheath but below the
melting point temperature of the core; and cooling the composite
fabric to mechanically anchor said conventional yarns or fibers in
said composite yarns.
[0017] The articles of the present invention relate to furniture
fabrics, and particularly to seating fabrics, comprising composite
elastomeric yarns and composite fabrics for use in seats and backs
of chairs, benches and sofas used in office and/or residential
environments or installed in various forms of ground transportation
such as automobiles, motorcycles, trucks, buses, trains, etc., as
well as various aircraft and marine craft. By using fabrics
comprising the composite elastomeric yarns in vehicle seating
assemblies, and preferably the composite fabrics of the present
invention, a fabric possessing strength, comfort, breathability and
elasticity can be achieved in combination with superior aesthetic
qualities. Thin profile vehicle seating assemblies can thus be
constructed with fabrics comprising the composite elastomeric
yarns, and preferably the composite fabrics of the present
invention, without the need for bulky foam cushions, stuffing
material, springs or rubber straps while maintaining a desirable
combination of support, comfort and appearance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a partially cross-sectional, partially angled view
of a composite elastomeric yarn according to a first embodiment of
the present invention having a monofilament core.
[0019] FIG. 2 is partially cross-sectional, partially angled view
of a composite elastomeric yarn according to a second embodiment of
the present invention having a multifilament core.
[0020] FIG. 3 is the first view in a sequence of three profile
views showing a segment of the composite yarn prior to the
disposition of fibers on the surface of the sheath.
[0021] FIG. 4 is the second view in a sequence of three profile
views showing the disposition of fibers on the surface of the
sheath of the segment of FIG. 3 after the composite yarn has been
stretched.
[0022] FIG. 5 is the third view in a sequence of three profile
views showing the segment of FIG. 3 after the composite yarn has
been relaxed from a stretched state in which fibers have been
disposed on and anchored in the surface of the sheath.
[0023] FIG. 6 is a schematic view of an embodiment of a "WI"
configuration woven pile weave pattern which may be employed in the
formation of the composite fabric of the present invention.
[0024] FIG. 7 is a schematic view of an embodiment of a "V"
configuration woven pile weave pattern which may be employed in the
formation of the composite fabric of the present invention.
[0025] FIGS. 8 through 13 are schematic views of alternative woven
pile weave patterns which may be employed in the formation of the
composite fabric of the present invention wherein the two rows of
dots represent profile views of filling yarns, the parallel
sinusoidal lines about each row of dots represents ground warps,
and the sinusoidal lines alternating between rows of dots
represents warp pile.
[0026] FIG. 14 is a schematic view of an embodiment of a loom
configuration for making a woven fabric.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The Composite Yarns
[0028] As disclosed herein, the preferred composite yarns of the
present invention have improved properties both in high
elongation/low modulus embodiments as well as low elongation/high
modulus embodiments. More specifically, the composite yarns of the
present invention provide an aesthetically pleasing outer surface
in both elongated and relaxed form, improved adherence of surface
fibers to the elastomeric core, and improved abrasion resistance.
Further, the preferred composite yarns of the present invention are
able to lock in and hide electro-conductive yarns in the interior
thereof as well as cover flammable elastomers with non-flammable or
fire resistant fibers to produce elastic yarns which minimize or
eliminate burn or the propagation of flame spread.
[0029] From an aesthetic perspective, composite yarns of the
present invention can be produced with varying degrees of bulk and
a wide variety of moduli depending on, at least in part, the
desired application, and can be brushed in yarn or fabric form
resulting in minimal fiber loss as the surface fibers are
mechanically anchored into the body of the yarn. When used in
fabrics for vehicle seats in automotive, air and marine craft
applications, the combination of properties of the yarns of the
present invention provides the necessary support, comfort and
appearance previously achieved by means of the combination of foam
cushioning, stuffing material, springs, elastic straps and the
like.
[0030] The composite yarns of the present invention preferably
comprise an elastomeric core, a elastomeric thermoplastic sheath
disposed about the core, and fibers disposed about and mechanically
anchored in the sheath. FIG. 1 shows generally a segment of a
preferred composite yarn of the present invention 1. As further
shown in FIG. 1, the yarns comprise a core 2, a sheath 3, and
fibers 4 disposed about and mechanically anchored into the sheath.
Although the anchored fibers are illustrated in the figures as
short, individual strands of fibers, it should be appreciated that
in certain embodiments the fiber component may be part of or
incorporated into a yarn disposed about the sheath. In certain
embodiments, the core comprises a elastomeric monofilament as shown
in FIG. 1, while in other embodiments, as shown in FIG. 2, the core
comprises a plurality of elastomeric filaments 5 which can be
configured in a number of alternative forms well known to the art
(i.e., bundled, twisted, braided, etc.).
[0031] The material comprising the core, whether a monofilament or
multifilament, preferably comprises a polymer which exhibits a
relatively high melting point temperature. It is preferred that the
melting point temperature of the material comprising the core be in
the range of from about 185.degree. C. to about 240.degree. C., and
preferably from about 200.degree. C. to about 230.degree. C. By
comparison, the material comprising the sheath component preferably
comprises a polymer which exhibits a melting point temperature at
least 10.degree. C. lower, preferably from about 50.degree. C. to
about 75.degree. C., lower than the melting point temperature of
the core material. It is preferred that the melting point
temperature of the material comprising the sheath be in the range
of from about 100.degree. C. to about 200.degree. C., and
preferably from about 160.degree. C. to about 190.degree. C.
[0032] Provided that the relative melting points of the core
material and the sheath material differ by at least about
10.degree. C., the materials comprising the core and the sheath can
be selected from a wide variety of readily available polymers which
exhibit thermoplastic properties. It is preferred, however, that
the materials comprising the core and the sheath be selected so
that the melting point temperature differential between them be
from up to about 50.degree. C. to up to about 75.degree. C. to
allow for greater flexibility in subsequent manufacturing
processes. By using materials having different melting points, the
sheath component can be heated to a temperature which results in at
least the softening and/or tackifying of the sheath material while
the core component remains in substantially solid and oriented
form.
[0033] For high modulus/low elongation yarns, the hardness of the
core component of the present invention, as measured on the Shore D
hardness scale, is preferably from about 38 to about 82, more
preferably from about 45 to about 74, and even more preferably from
about 55 to about 74. Although it is contemplated that numerous
polymers may be used as the core component of the present
invention, polymers which exhibit elastomeric properties are
preferred, with elastomeric polyesters being especially preferred.
It will be appreciated by those skilled in the art that the term
"polyester" as used herein is intended to include polymers which
include polyester components, such as co-polymers of polyesters and
other polymeric components, including graft and block
co-polymers.
[0034] In certain preferred embodiments, the core component
comprises a polyether ester or a polyester ester, more preferably a
polyether ester block copolymer sold under the trademark
HYTREL.RTM. by E. I. Du Pont de Nemours & Co., Inc. or a
polyether ester block copolymer sold under the trademark
ARNITEL.RTM. by D. S. M. Polymers, and even more preferably
HYTREL.RTM. grades 5556, 6356 or 7246, or ARNITEL.RTM. grades EM
550, EM 630 and EM 740. According to preferred embodiments, the
sheath component consists essentially of a polyether ester or a
polyester ester, and more preferably a polyether ester block
copolymer sold under the trademark HYTREL.RTM. by E. I. Du Pont de
Nemours & Co., Inc. or a polyether ester block copolymer sold
under the trademark ARNITEL.RTM. by D. S. M. Polymers, and even
more preferably HYTREL.RTM. 4056 or ARNITEL.RTM. EM 400.
[0035] The percent elongation of the core at the breaking point is
preferably from about 50% to about 150% beyond its relaxed state,
more preferably from about 80% to about 130% beyond its relaxed
state, and even more preferably from about 100% to about 110%
beyond its relaxed state. The denier range of the core component of
the composite yarn is preferably from about 500 to about 2500 and
even more preferably from about 800 to about 2000.
[0036] The material comprising the sheath component of the
composite yarn of the present invention is preferably compatible
with the material comprising the core component in order to
establish appropriate bonding to and adherence with the core
component. The hardness of the sheath component of the composite
yarn, as measured on the Shore D hardness scale, is preferably from
about 30 to about 45, and even more preferably from about 35 to
about 45.
[0037] According to preferred embodiments, the composite yarn
preferably comprises a core having a hardness of about 55 to about
74 on the Shore D hardness scale and comprising a poly ether ester
block copolymer, and a sheath of a softer, lower melting point
polyether ester block copolymer having a hardness of about 35 to
about 45 on the Shore D hardness scale.
[0038] In certain preferred embodiments, additives can be included
in the polymeric material used to form the sheath and core
components in order to enhance various processing properties
thereof including lowering the melting points and/or increasing the
melt flow properties, as well as the resultant fabric properties
such as toughness, durability, lightfastness, and flammability. The
selection of such additives will depend, at least in part, on the
requirements of the application to which the fabric will be put.
Such additives include, but are not limited to, hydrolytic
stabilizers, UV light stabilizers, heat stabilizers, color
additives and fixing agents, flame retardants, as well as
electrically conductive materials for dissipation of static
charges.
[0039] The fibers which are disposed about the surface of the
sheath generally comprise conventional non-elastic materials which
are often used in apparel, home furnishings, automotive, aircraft
and marine applications, as well as other industrial and medical
applications. It will be appreciated by those skilled in the art
that the fibers which may be utilized in accordance with the
present invention may vary widely depending on the particular
characteristics desired for and requirements imposed by the end
product. The fibers of the present invention are preferably
selected from the group consisting of cotton, carbon, wool,
man-made cellulosics (including cellulose acetate and regenerated
cellulose), polyamides, polyesters, fluorocarbon polymers,
polybenzimidazoles, polyolefins (including polyethylene and
polypropylene), polysulfides, polyacrylonitriles, polymetaphenylene
isophthalamide, polymetaphenylene diamine manufactured by E. I. Du
Pont de Nemours & Co., Inc. under the trademark NOMEX.RTM.,
polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride and
other flaccid textile materials, as well as non-flaccid fibers such
as polyparaphenylene terephthalamide manufactured by E. I. Du Pont
de Nemours & Co., Inc. under the trademark KEVLAR.RTM.,
fiberglass, metallic and ultra high strength polyethylenes and high
tenacity polyesters, nylons and poly(vinyl alcohols). Suitable
fibers for use in the present invention can also be characterized
by type, i.e., spun (ring, friction, wrap, etc.), chenille, and
filament (flat, false twist, airjet, stuffer box, etc.). It will be
understood that as used herein fibers can include both single,
individual fibers, such as chopped strands, or fibers which are
spun, twisted or otherwise bound together to form a yarn.
[0040] The fibers are preferably disposed about the surface of the
sheath by means of the various methods set forth below wherein the
fibers are anchored in the sheath. So disposed, the fibers are
mechanically bonded to the sheath so that the resulting composite
yarn exhibits durability and wear resistance while also providing a
wide range of textures and fiber densities depending on the fibers
used and the particular method of application employed.
[0041] The Composite Fabrics
[0042] As disclosed herein, the preferred composite fabrics of the
present invention, like the preferred composite yarns of the
present invention, have improved properties both in high
elongation/low modulus embodiments as well as low elongation/high
modulus embodiments. More specifically, the composite fabrics of
the present invention provide an aesthetically pleasing surface in
both elongated and relaxed form as well as improved wear and
abrasion resistance. In those embodiments in which the composite
fabric is of woven pile construction, the composite fabric also
provides improved adherence of the pile fibers to the ground warp
and/or filling yarn without having to apply coating compositions or
additional layers of fabric or other materials to the backside
thereof. Among the advantages which are realized by the avoidance
of such additional components in the composite fabric of the
present invention are a reduction in thickness and weight, improved
elasticity and breathability, and the elimination of additional
material, labor and disposal costs.
[0043] The composite fabrics of the present invention preferably
comprise the composite yarns of the present invention and
conventional fibers arranged to form a fabric. Preferably, the
composite yarns used in the composite fabrics of the present
invention comprise an elastomeric core and a thermoplastic
elastomeric sheath disposed about the core wherein the melting
point temperature of the sheath is at least about 10.degree. C.
lower than the melting point temperature of the core. The
conventional fibers suitable for use in the composite fabrics of
the present invention are those which a capable of being combined
with and anchored in the sheath component of the composite yarns,
and include all of the fibers and fiber types recited above in
connection with the composite yarns of the present invention.
[0044] The formation of a fabric from composite yarns and
conventional fibers may be accomplished by any of the methods well
known in the art including weaving, knitting, braiding, felting and
other such methods. In certain preferred embodiments, the composite
fabric will be in the form of a woven pile fabric. In such
embodiments, at least some portion of the ground warp yarns, or
some portion of the filling yarn, comprise composite yarns, and the
pile, either warp or filling, will preferably comprise conventional
fibers. According to preferred embodiments, the ground warp yarns
or the filling yarns, and even more preferably both yarns, consist
essentially of the composite yarn of the present invention.
Conventional fibers used in the present invention are preferably
spun, twisted, textured or otherwise bound together to some portion
of both the ground warp and the filling yarn, and are preferably
interlaced with respect to the ground warp or filling yarn in a "V"
or "WI" configuration wherein segments of the conventional fibers
are wrapped around either one ("V" ) or three ("W") composite yarns
of the ground warp and/or filling yarn.
[0045] As disposed in the composite fabric as the warp or filling
pile, the conventional fibers may or may not then be cut depending
on whether a cut pile or a loop pile is desired for the end use
application. Regardless of whether in the form of a cut or loop
pile, or indeed in the form of a woven pile, an important aspect of
the composite fabrics of the present invention is that the
conventional yarns or fibers are not only arranged in the fabric
with the composite yarns in accordance with the selected method of
construction but are also mechanically anchored in the composite
yarns.
[0046] The Methods
[0047] The methods of the present invention relate to the formation
of composite elastomeric yarns and composite fabric.
[0048] A. The Composite Yarns
[0049] With respect to the formation of composite elastomeric
yarns, the methods preferably comprise the steps of:
[0050] providing a sheath-core component comprising an elastomeric
core and a thermoplastic elastomeric sheath disposed about the core
wherein the melting point temperature of the sheath is at least
about 10.degree. C. lower than the melting point temperature of the
core;
[0051] heating the sheath-core component to a temperature above the
melting point of the sheath but below the melting point of the
core;
[0052] disposing fibers in intimate mechanical contact about the
sheath;
[0053] and cooling the composite elastomeric yarn thus formed to
mechanically anchor the fibers to the sheath.
[0054] The above description in which the heating step is described
prior to the cooling step should not be understood as limiting the
sequence of the steps used according to the present invention.
According certain preferred embodiments, for example, the step of
disposing the fibers in intimate contact with the sheath occurs
prior to heating of the sheath-component. In certain other
preferred embodiments, the step of disposing the fibers in intimate
contact with the sheath occurs subsequent to heating of the
sheath-component. In certain preferred embodiments, as shown in the
sequence of FIG. 3 to FIG. 5, the sheath-core component will be
stretched from about 10% to about 500% beyond its relaxed length
prior to the disposition of fibers about the sheath.
[0055] The initial step of providing the sheath-core component can
be accomplished in a variety of ways including forming the
sheath-core component by methods well known to the art or obtaining
certain pre-made sheath-core components from other sources. The
methods of forming the sheath-core component include the
pulltrusion technique of forming the core component and then
drawing the core component through a molten bath of the sheath
material at a temperature above that of the melting point
temperature of the sheath material but below that of the melting
point temperature of the core material. Alternatively, the core
component can be simultaneously co-extruded with the sheath
component at a temperature appropriate for such simultaneous
co-extrusion in a manner such that the extrudate comprises a core
comprising the higher melting point material and a sheath
comprising the lower melting point material as disclosed by
Himmelreich, Jr. (U.S. Pat No. 4,469,738) which is incorporated
herein by reference. Another alternative for providing a
sheath-core component according to the present invention is a
crosshead technique in which the core is preformed and is fed
through the center of a crosshead extrusion die wherein the sheath
material is extruded as an outer jacket or covering over the
preformed core material. It will be understood that certain
embodiments of the methods of the present invention will employ a
monofilament core, while in other embodiments of the methods of the
present invention the core comprises a plurality of filaments.
[0056] Another step in the methods of the present invention
comprises heating the sheath-core component to a temperature above
that of the melting point temperature of the sheath material but
below that of the melting point temperature of the core material.
In so doing, the sheath material is softened or at least tackified
to permit mechanical bonding with the fibers which may be
subsequently applied or which may have already been applied. In
certain preferred embodiments, the heating step will occur during
manufacture of the composite yarn but prior to its incorporation
into a fabric. In other embodiments, however, the partially-formed
yarn of the present invention, that is, the sheath-core component,
is first incorporated into a fabric manufacturing process so that
the resulting fabric comprising strands of the sheath-core
component of the present invention will be the article that is
heated.
[0057] In certain preferred embodiments, the sheath-core component
is stretched beyond its relaxed state but within its elastic range
prior to the application of fibers as shown in the sequence of FIG.
3 to FIG. 5. Such stretching allows the resulting composite yarn to
take on varying degrees of bulk and/or density. More specifically,
FIG. 3 shows a segment of the sheath-core component comprising a
core 2A and sheath 3A prior to stretching. FIG. 4 shows the
subsequent view of the segment shown in FIG. 3 in which the segment
of the sheath-core component has been stretched and fibers 4A have
been disposed about the surface of sheath 3B. Sheath 3B and core 2B
are shown having a thinner profile as a result of the stretched
state depicted in FIG. 4. FIG. 5 shows a view subsequent to the
view shown in FIG. 4 in which core 2C and sheath 3C have returned
to their original relaxed, i.e. unstretched, state, and fibers 4B
exhibit a greater density than fibers 4A exhibit in FIG. 4. As
shown by the sequence of FIGS. 3 to 5, when the sheath-core
component is stretched, any given interval of the sheath-core
component in the relaxed form presents a greater surface area in
stretched form on which to accommodate the application of fibers.
Thus, when the sheath-core component is then relaxed to an
unstretched state, the density of fibers within any given interval
is greater than if such fibers were applied without stretching. As
a result, the greater degree to which the sheath-core component is
stretched within its elastic range prior to the application of
fibers, the greater the bulk and fiber density of the resulting
composite fiber.
[0058] In certain preferred embodiments, the methods of the present
invention further comprise the step of stretching the sheath-core
component from about 10% to about 500% beyond its relaxed length
prior to the application of fibers. The optimal degree of
stretching will depend upon the materials used in forming the
sheath-core component as well as the intended end use of the
composite yarn. By way of example, for high modulus thermoplastic
polyether-ester block copolymer elastomers such as HYTREL.RTM., the
degree of stretching beyond its relaxed length would be from about
10% to about 40%, and preferably from about 12% to about 18%. For
lower modulus elastomers such as LYCRA.RTM. spandex manufactured by
E. I. Du Pont de Nemours & Co., Inc., the degree of stretching
would typically be from about 300% to about 500%, and preferably
from about 350% to about 425%. In certain preferred embodiments, by
stretching the sheath-core component prior to application of the
fibers, the resulting composite yarn when used in fabric
manufacturing processes (i.e., weaving, knitting, etc.) will be
capable of stretching and recovering freely without significant
restrictions imposed by fibers anchored at more than one site in
the composite yarn surface. It will be understood that, depending
on the desired manufacturing process and end use, for those
embodiments in which a stretching step is a part, the stretching
step can occur when the sheath-core component is in yarn form or
when it has already been processed or partially processed into a
fabric.
[0059] Another step in the methods of the present invention
comprises disposing fibers in intimate mechanical contact about the
sheath-core component. As stated above, in certain preferred
embodiments, the disposition of fibers will occur while the
sheath-core component is in yarn form. In other embodiments,
however, the sheath-core component will have already been used in a
fabric manufacturing process so that the application of fibers will
be upon the surface or surfaces of the fabric. It will be
understood that the fibers disposed about the sheath-core component
can be in the form of free fibers or in the form of yarn or a
combination thereof. Depending on the fibers to be applied, the
desired bulkiness, and the desired end use, the form of the fibers
so disposed will vary and the process by which the fibers may be
disposed includes wrapping, spinning, twisting, flocking, or any
number of other procedures well known to the art provided, however,
that by so disposing the fibers about the sheath-core component
said fibers are able to penetrate into at least a portion of the
sheath component so as to achieve a mechanical bond thereto.
[0060] The heating step for locking the exterior textile fibers to
the sheath component way occur either prior or subsequent to the
disposition of fibers about the sheath-core component. In certain
preferred embodiments, the heating step takes place directly after
the disposition of the fibers around the sheath-core component
while the sheath-core component is in yarn form. In certain other
preferred embodiments, the heating step takes place while the
sheath-core component is in fabric form.
[0061] The final step in the methods of forming the composite yarn
of the present invention comprises cooling the composite yarn so as
to effect the anchoring of the fibers in the sheath component.
[0062] B. The Composite Fabric
[0063] With respect to the formation of composite fabric, the
methods preferably comprise the steps of:
[0064] forming a fabric of conventional yarns or fibers and
composite yarns comprising an elastomeric core and an elastomeric
thermoplastic sheath disposed about the core wherein the melting
point temperature of the sheath is at least about 10.degree. C.,
preferably about 50.degree. C. to about 75.degree. C., lower than
the melting point temperature of the core and;
[0065] heating the composite fabric to a temperature at or above
about the melting point temperature of the sheath but below the
melting point temperature of the core;
[0066] and cooling the composite fabric to mechanically anchor said
conventional yarns or fibers in said composite yarns. The initial
step of forming a fabric of conventional yarns or fibers and
composite yarns can be accomplished in a variety of methods well
known to the art. These methods include, but are not limited to,
weaving, knitting, braiding or felting. An schematic illustrating
one weaving method for making a woven pile fabric is shown
generally in FIG. 14. Preferably, the step of forming a fabric will
be by means of weaving and, more preferably, by means of pile
weaving whereby a ground warp and filling yarn comprising the
composite yarns of the present invention are interlaced with a warp
or filling pile of conventional fibers. In such embodiments, the
warp or filling pile may be interlaced with respect to the ground
warp or filling yarns in any of a variety of configurations known
to the art. Preferably, the warp or filling pile will be interlaced
in a "V" or "W" configuration wherein segments of the warp or
filling pile are wrapped around either one ("V") or three ("W")
composite yarns of the ground warp or filling yarns. Various
embodiments of such weaving patterns are shown in FIGS. 6 through
13.
[0067] Another step in the methods of the present invention
comprises heating the composite fabric to a temperature above that
of the melting point temperature of the sheath material of the
composite yarns but below that of the melting point temperature of
the core material thereof. In so doing, the sheath material is
softened or at least tackified to permit mechanical bonding with
the conventional fibers interlaced therewith. While the selection
of the temperature to which the composite fabric is heated is
determined, at least in part, by the selection of materials
comprising the composite yarns, consideration must also be given to
the limitations imposed by the fiber materials selected so that
such materials are not degraded during the heating step.
[0068] The final step in the methods of forming the composite
fabric of the present invention comprises cooling the composite
fabric so as to effect the anchoring of the fibers in the sheath
component of the composite yarns.
[0069] The Articles
[0070] The resulting composite elastomeric yarns and composite
fabrics of the present invention can be used in manufacturing
processes for the formation of fabric articles having a desirable
combination of properties well suited for use in vehicle seats in
automotive, air and marine craft applications as well as in
commercial and residential furniture for use in indoor and outdoor
settings. Because of the superior elasticity, durability and wear
resistance of fabrics made from composite elastomeric yarns of the
present invention, and particularly the composite fabrics of the
present invention, as well as the wide range of textures and fiber
densities which can be achieved, vehicle seats for use in
automotive, air and marine craft applications, as well as
commercial and residential furniture, can be constructed without
the need for the additional use of foam cushioning, stuffing
material, springs, elastic straps or combinations thereof. Such
thin profile vehicle seats as described in Abu-Isa, et al. (U.S.
Pat. No. 5,013,089), Abu-Isa, et al. (U.S. Pat. No. 4,869,554) and
Abu-Isa, et al. (U.S. Pat. No. 4,545,614) all of which are
incorporated herein by reference, are examples of preferred
articles which can be constructed from fabrics comprising composite
elastomeric yarns of the present invention as well as the composite
fabrics of the present invention. More particularly, such articles
include a seat assembly, having a seat frame and a low profile seat
suspension stretched across and attached to the frame. The seat
suspension of such seat assembly comprises a fabric comprising the
composite yarns or the composite fabric of the present
invention.
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