U.S. patent application number 10/810386 was filed with the patent office on 2004-12-09 for structurally stable flame-retardant nonwoven fabric.
This patent application is currently assigned to Polymer Group, Inc.. Invention is credited to Hartgrove, Herbert, Rabon, Gregory, Tindall, Russell.
Application Number | 20040248494 10/810386 |
Document ID | / |
Family ID | 33131696 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040248494 |
Kind Code |
A1 |
Hartgrove, Herbert ; et
al. |
December 9, 2004 |
Structurally stable flame-retardant nonwoven fabric
Abstract
The present invention is directed to a hydroentangled
flame-retardant nonwoven fabric, and more specifically, to a
structurally stable flame-retardant fabric comprising at least two
layers, wherein the fibrous components of the fabric have a
synergistic relationship so as to maintain the integrity of the
flame-retardant fabric upon burning. In accordance with the present
invention, the nonwoven fabric is comprised of at least a first and
second layer. The first layer comprises a blend of lyocell fiber
and modacrylic fiber.
Inventors: |
Hartgrove, Herbert; (Dunn,
NC) ; Rabon, Gregory; (Clayton, NC) ; Tindall,
Russell; (Clemmons, NC) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Assignee: |
Polymer Group, Inc.
|
Family ID: |
33131696 |
Appl. No.: |
10/810386 |
Filed: |
March 26, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60457607 |
Mar 26, 2003 |
|
|
|
Current U.S.
Class: |
442/408 ;
442/327 |
Current CPC
Class: |
D04H 1/492 20130101;
Y10T 442/60 20150401; D04H 1/4282 20130101; D04H 1/4258 20130101;
D04H 1/498 20130101; D04H 1/495 20130101; Y10T 442/689
20150401 |
Class at
Publication: |
442/408 ;
442/327 |
International
Class: |
D04H 003/00 |
Claims
What is claimed is:
1. A method of making a structurally stable hydroentangled
flame-retardant nonwoven fabric comprising the steps of: a.
providing a first layer precursor web comprising a blend of lyocell
fiber and modacrylic fiber; b. providing a second precursor web
comprising a blend of lyocell fiber, modacrylic fiber, and
para-amid fiber; c. positioning said first precursor web atop said
second precursor web; and d. hydroentangling said first and second
precursor webs so as to form said nonwoven fabric.
2. A method of making a structurally stable hydroentangled
flame-retardant nonwoven fabric as in claim 1, wherein said first
layer comprises a blend of 60% lyocell fiber and 40% modacrylic
fiber.
3. A method of making a structurally stable hydroentangled
flame-retardant nonwoven fabric as in claim 1, wherein said second
layer comprises a blend of 42% lyocell fiber, 37% modacrylic fiber,
and 21% para-amid fiber.
4. A method of making a structurally stable three-dimensionally
imaged flame-retardant nonwoven fabric comprising the steps of: a.
providing a first layer precursor web comprising a blend of lyocell
fiber and modacrylic fiber; b. providing a second precursor web
comprising a blend of lyocell fiber, modacrylic fiber, and
para-amid fiber; c. providing a three-dimensional image transfer
device; d. positioning said first precursor web atop said second
precursor web; e. advancing said first and second precursor webs
onto said three-dimensional image transfer device; and f.
hydroentangling said first and second precursor webs so as to form
said imaged nonwoven fabric.
5. A structurally stable hydroentangled flame-retardant nonwoven
fabric comprising a first layer and a second layer, wherein said
first layer comprises a blend of lyocell fiber and modacrylic fiber
and said second layer comprises a blend or lyocell fiber,
modacrylic fiber, and para-amid fiber, whereby said first and
second layers are hydroentangled so as to form said fabric.
6. A structurally stable three-dimensionally imaged flame-retardant
nonwoven fabric comprising a first layer and a second layer,
wherein said first layer comprises a blend of lyocell fiber and
modacrylic fiber and said second layer comprises a blend or lyocell
fiber, modacrylic fiber, and para-amid fiber, whereby said first
and second layers are hydroentangled on a three-dimensional image
transfer device so as to form said fabric.
Description
TECHNICAL FIELD
[0001] The present invention generally relates a hydroentangled
flame-retardant nonwoven fabric, and more specifically, to a
structurally stable flame-retardant fabric comprising at least two
layers, wherein the fibrous components of the fabric have a
synergistic relationship so as to maintain the integrity of the
flame-retardant fabric upon burning.
BACKGROUND OF THE INVENTION
[0002] The production of conventional textile fabrics is known to
be a complex, multi-step process. The production of fabrics from
staple fibers begins with the carding process where the fibers are
opened and aligned into a feed stock known as sliver. Several
strands of sliver are then drawn multiple times on a drawing frames
to further align the fibers, blend, improve uniformity as well as
reduce the sliver's diameter. The drawn sliver is then fed into a
roving frame to produce roving by further reducing its diameter as
well as imparting a slight false twist. The roving is then fed into
the spinning frame where it is spun into yarn. The yarns are next
placed onto a winder where they are transferred into larger
packages. The yarn is then ready to be used to create a fabric.
[0003] For a woven fabric, the yarns are designated for specific
use as warp or fill yarns. The fill yarns (which run on the y-axis
and are known as picks) are taken straight to the loom for weaving.
The warp yarns (which run on the x-axis and are known as ends) must
be further processed. The large packages of yarns are placed onto a
warper frame and are wound onto a section beam were they are
aligned parallel to each other. The section beam is then fed into a
slasher where a size is applied to the yarns to make them stiffer
and more abrasion resistant, which is required to withstand the
weaving process. The yarns are wound onto a loom beam as they exit
the slasher, which is then mounted onto the back of the loom. The
warp yarns are threaded through the needles of the loom, which
raises and lowers the individual yarns as the filling yarns are
interested perpendicular in an interlacing pattern thus weaving the
yarns into a fabric. Once the fabric has been woven, it is
necessary for it to go through a scouring process to remove the
size from the warp yarns before it can be dyed or finished.
Currently, commercial high speed looms operate at a speed of 1000
to 1500 picks per minute, where a pick is the insertion of the
filling yarn across the entire width of the fabric. Sheeting and
bedding fabrics are typically counts of 80.times.80 to
200.times.200, being the ends per inch and picks per inch,
respectively. The speed of weaving is determined by how quickly the
filling yarns are interlaced into the warp yarns, therefore looms
creating bedding fabrics are generally capable of production speeds
of 5 inches to 18.75 inches per minute.
[0004] In contrast, the production of nonwoven fabrics from staple
fibers is known to be more efficient than traditional textile
processes as the fabrics are produced directly from the carding
process.
[0005] Nonwoven fabrics are suitable for use in a wide variety of
applications where the efficiency with which the fabrics can be
manufactured provides a significant economic advantage for these
fabrics versus traditional textiles. However, nonwoven fabrics have
commonly been disadvantaged when fabric properties are compared,
particularly in terms of surface abrasion, pilling and durability
in multiple-use applications. Hydroentangled fabrics have been
developed with improved properties which are a result of the
entanglement of the fibers or filaments in the fabric providing
improved fabric integrity. Subsequent to entanglement, fabric
durability can be further enhanced by the application of binder
compositions and/or by thermal stabilization of the entangled
fibrous matrix.
[0006] U.S. Pat. No. 3,485,706, to Evans, hereby incorporated by
reference, discloses processes for effecting hydroentanglement of
nonwoven fabrics. More recently, hydroentanglement techniques have
been developed which impart images or patterns to the entangled
fabric by effecting hydroentanglement on three-dimensional image
transfer devices. Such three-dimensional image transfer devices are
disclosed in U.S. Pat. No. 5,098,764, hereby incorporated by
reference, with the use of such image transfer devices being
desirable for providing a fabric with enhanced physical properties
as well as an aesthetically pleasing appearance.
[0007] Heretofore, nonwoven fabrics have been advantageously
employed for manufacture of flame-retardant fabrics, as described
in U.S. Pat. No. 6,489,256, to Kent, et al., which is hereby
incorporated by reference. Typically, nonwoven fabrics employed for
this type of application have been entangled and integrated by
needle-punching, sometimes referred to as needle-felting, which
entails insertion and withdrawal of barbed needles through a
fibrous web structure. While this type of processing acts to
integrate the fibrous structure and lend integrity thereto, the
barbed needles inevitably shear large numbers of the constituent
fibers, and undesirably create perforations in the fibrous
structure. Needle-punching can also be detrimental to the strength
of the resultant fabric, requiring that a fabric have a relatively
high basis weight in order to exhibit sufficient strength.
[0008] A need exists for a more cost effective flame-retardant
nonwoven fabric that is structurally stable, soft, as well as
strong and suitable for end-use applications including, but not
limited to bedding components, such as mattress covers and other
home uses, protective apparel applications, and other industrial
end-use applications.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to a hydroentangled
flame-retardant nonwoven fabric, and more specifically, to a
structurally stable flame-retardant fabric comprising at least two
layers, wherein the fibrous components of the fabric have a
synergistic relationship so as to maintain the integrity of the
flame-retardant fabric upon burning.
[0010] In accordance with the present invention, the nonwoven
fabric is comprised of at least a first and second layer. The first
layer comprises a blend of lyocell fiber and modacrylic fiber. The
fibrous components of the first layer provide the fabric with
exceptional strength, in addition to a soft hand. Further, the
modacrylic fiber and lyocell fiber form a char rather than melt
when burned.
[0011] Positioned beneath the first layer is a second layer,
comprising a blend of lyocell fiber, modacrylic fiber, and
para-amid fiber. As described in the first layer, the lyocell fiber
and modacrylic fiber provide the resultant fabric with strength, a
soft hand, and form a char as opposed to melting. In addition, the
second layer incorporates para-amid fiber, which provides the
fabric with structural integrity by maintaining the fibrous
structure of the fabric, as well as reducing any thermal shrinkage.
Not meaning to be bound by theory, it is believed that the fibrous
components of the flame-retardant fabric have a synergistic
relationship to provide a cost effective fabric with exceptional
strength, softness, and flame retardancy, wherein upon burning, the
lyocell fiber forms a char due to the presence of the modacrylic
fiber, which also chars, yet the integrity of the fabric remains
structurally stable upon the incorporation of the para-amid
fiber.
[0012] Further, it has been found that the addition of the
para-amid fiber in the second layer lends to a discoloration of the
fabric, wherein the fabric takes on a yellow hue. The lack of
para-amid fiber in the first layer, which is positioned atop the
second layer, masks the discoloration of the second layer,
improving the aesthetic quality of the fabric.
[0013] The first and second layers of the flame-retardant nonwoven
fabric are hydroentangled to form a composite fabric comprising the
aforementioned fibrous components. Optionally, the nonwoven fabric
may be hydroentangled on a three-dimensional image transfer device
so as to impart a three-dimensional image or pattern into the
fabric, suitably enhancing the aesthetic quality of the fabric for
a particular end-use application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagrammatic view of apparatus utilized in
accordance with the present invention so as to manufacture the
flame-retardant nonwoven fabric.
DETAILED DESCRIPTION
[0015] While the present invention is susceptible of embodiment in
various forms, there is shown in the drawings, and will hereinafter
be described, a presently preferred embodiment, with the
understanding that the present disclosure is to be considered as an
exemplification of the invention, and is not intended to limit the
invention to the specific embodiment illustrated.
[0016] The flame-retardant nonwoven fabric of the present invention
structurally stable, soft, as well as strong and suitable for
end-use applications including, but not limited to bedding
components, such as mattress covers and other home uses, protective
apparel applications, and other industrial end-use
applications.
[0017] U.S. Pat. No. 3,485,706, to Evans, hereby incorporated by
reference, discloses processes for effecting hydroentanglement of
nonwoven fabrics. With reference to FIG. 1, therein is illustrated
an apparatus for practicing the present method for forming a
nonwoven fabric. The fibrous components are preferably carded and
cross-lapped to form first precursor web, designated P and a second
precursor web, designated P', which are hydraulically united to
form a composite nonwoven flame-retardant fabric.
[0018] In one embodiment, a first precursor web is formed
comprising staple length lyocell fibers and modacrylic fibers,
wherein the modacrylic fibers have an independent level of
flame-resistance. Also, a second precursor web is formed comprising
staple length fibers of lyocell fibers, modacrylic fibers, and
para-amid fibers, wherein the modacrylic fibers, as well as the
para-amid fibers have an independent level of flame-resistance. It
is also in the purview of the present invention, that other
flame-retardant fibers be incorporated in either one or both of the
precursor webs, these fibers include, but are not limited to
phenolic fibers, such as Kynol.TM. fiber from American Kynol, Inc.,
pre-oxidized polyacrylonitrile fibers, such as Panox.RTM. fiber, a
registered trademark to R.K. Textiles Composite Fibers Limited.
[0019] Further, FIG. 1 illustrates a hydroentangling apparatus,
whereby the apparatus includes a foraminous forming surface in the
form of belt 12 upon which the precursor webs P and P' are
positioned for entangling or pre-entangling by manifold 14.
[0020] The entangling apparatus of FIG. 1 may optionally include an
imaging and patterning drum 18 comprising a three-dimensional image
transfer device for effecting imaging and patterning of the lightly
entangled precursor web. The image transfer device includes a
moveable imaging surface which moves relative to a plurality of
entangling manifolds 22 which act in cooperation with
three-dimensional elements defined by the imaging surface of the
image transfer device to effect imaging and patterning of the
fabric being formed.
[0021] In addition to the first and second layers of the
flame-retardant nonwoven fabric, it is also contemplated that one
or more supplemental layers be added, wherein such layers may
include a spunbond fabric. In general, the formation of continuous
filament precursor webs involves the practice of the "spunbond"
process. A spunbond process involves supplying a molten polymer,
which is then extruded under pressure through a large number of
orifices in a plate known as a spinneret or die. The resulting
continuous filaments are quenched and drawn by any of a number of
methods, such as slot draw systems, attenuator guns, or Godet
rolls. The continuous filaments are collected as a loose web upon a
moving foraminous surface, such as a wire mesh conveyor belt. When
more than one spinneret is used in line for the purpose of forming
a multi-layered fabric, the subsequent webs are collected upon the
uppermost surface of the previously formed web. Further, the
addition of a continuous filament fabric may include those fabrics
formed from filaments having a nano-denier, as taught in U.S. Pat.
No. 5,679,379 and No. 6,114,017, both incorporated herein by
reference. Further still, the continuous filament fabric may be
formed from an intermingling of conventional and nano-denier
filaments.
[0022] It has been contemplated that the nonwoven fabric of the
present invention incorporate a meltblown layer. The meltblown
process is a related means to the spunbond process for forming a
layer of a nonwoven fabric is the meltblown process. Again, a
molten polymer is extruded under pressure through orifices in a
spinneret or die. High velocity air impinges upon and entrains the
filaments as they exit the die. The energy of this step is such
that the formed filaments are greatly reduced in diameter and are
fractured so that microfibers of finite length are produced. This
differs from the spunbond process whereby the continuity of the
filaments is preserved. The process to form either a single layer
or a multiple-layer fabric is continuous, that is, the process
steps are uninterrupted from extrusion of the filaments to form the
first layer until the bonded web is wound into a roll. Methods for
producing these types of fabrics are described in U.S. Pat. No.
4,041,203. The meltblown process, as well as the cross-sectional
profile of the meltblown microfiber, is not a critical limitation
to the practice of the present invention.
[0023] In accordance with the present invention, the hydroentangled
flame-retardant fabric may comprise a film layer. The formation of
finite thickness films from thermoplastic polymers, suitable as a
strong and durable carrier substrate layer, is a well-known
practice. Thermoplastic polymer films can be formed by either
dispersion of a quantity of molten polymer into a mold having the
dimensions of the desired end product, known as a cast film, or by
continuously forcing the molten polymer through a die, known as an
extruded film. Extruded thermoplastic polymer films can either be
formed such that the film is cooled then wound as a completed
material, or dispensed directly onto a secondary substrate material
to form a composite material having performance of both the
substrate and the film layers.
[0024] Extruded films can be formed in accordance with the
following representative direct extrusion film process. Blending
and dosing storage comprising at least one hopper loader for
thermoplastic polymer chip and, optionally, one for pelletized
additive in thermoplastic carrier resin, feed into variable speed
augers. The variable speed augers transfer predetermined amounts of
polymer chip and additive pellet into a mixing hopper. The mixing
hopper contains a mixing propeller to further the homogeneity of
the mixture. Basic volumetric systems such as that described are a
minimum requirement for accurately blending the additive into the
thermoplastic polymer. The polymer chip and additive pellet blend
feeds into a multi-zone extruder. Upon mixing and extrusion from
the multi-zone extruder, the polymer compound is conveyed via
heated polymer piping through a screen changer, wherein breaker
plates having different screen meshes are employed to retain solid
or semi-molten polymer chips and other macroscopic debris. The
mixed polymer is then fed into a melt pump, and then to a combining
block. The combining block allows for multiple film layers to be
extruded, the film layers being of either the same composition or
fed from different systems as described above. The combining block
is connected to an extrusion die, which is positioned in an
overhead orientation such that molten film extrusion is deposited
at a nip between a nip roll and a cast roll.
[0025] In addition, breathable films can be used in conjunction
with the disclosed continuous filament laminate. Monolithic films,
as taught in U.S. Pat. No. 6,191,211, and microporous films, as
taught in U.S. Pat. No. 6,264,864, both patents herein incorporated
by reference, represent the mechanisms of forming such breathable
films.
[0026] In accordance with the present invention, Sample A comprises
a first layer of 60% staple length Tencel.RTM. lyocell fibers,
Tencel is a registered trademark of Courtaulds Fibres (Holdings)
Limited, and 40% PBX.RTM. modacrylic fibers, PBX.RTM. is a
registered trademark to Kaneka, with a basis weight of about 2.0
oz/yd.sup.2 and a second layer comprising a blend of 42%
Tencel.RTM. lyocell fibers, 37% PBX.RTM. modacrylic fibers, and 21%
Twaron.RTM. para-amid fibers, Twaron is a registered trademark of
Enka B. V. Corporation, with a basis weight of about 4.0
oz/yd.sup.2. The layers were consolidated into a composite
flame-retardant nonwoven composite fabric by way of
hydroentangling. Subsequently, the composite fabric was advanced
onto a three-dimensional image transfer device so as to impart a
three-dimensional pattern into the fabric. Table 1 shows the
physical test results of the aforementioned fabric.
1TABLE 1 Composition Sample A ITD Tricot Weight 4.6 oz./yd.sup.2
Bulk 44 mils Tensile MD-Peak (ASTM D-5035) 80 g/cm Tensile CD-Peak
48 g/cm MD Elong. 29.2% CD Elong. 94.4% Elmendorf Tear-MD (ASTM
D-5734) 3178 g Elmendorf Tear-CD 2087 g Air Permeability (ASTM
D-737) 147 cfm Absorbency 7 sec Thermal Shrinkage, MD
(FNA-LB-WI-GL-136) -1.0 Thermal Shrinkage, CD -1.0 Modified Vert.
Burn BFT Flame test 17.1
[0027] From the foregoing, it will be observed that numerous
modifications and variations can be affected without departing from
the true spirit and scope of the novel concept of the present
invention. It is to be understood that no limitation with respect
to the specific embodiments illustrated herein is intended or
should be inferred. The disclosure is intended to cover, by the
appended claims, all such modifications as fall within the scope of
the claims.
* * * * *