U.S. patent application number 11/726068 was filed with the patent office on 2011-08-11 for composite ballistic fabric structures.
Invention is credited to Henry G. Ardiff, Brian D. Arvidson, Ashok Bhatnagar, David A. Hurst, Lori L. Wagner.
Application Number | 20110192530 11/726068 |
Document ID | / |
Family ID | 39709279 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110192530 |
Kind Code |
A1 |
Arvidson; Brian D. ; et
al. |
August 11, 2011 |
COMPOSITE BALLISTIC FABRIC STRUCTURES
Abstract
A multilayered composite fabric which comprises (a) a first
fabric comprising non-woven unidirectionally oriented fibers in a
first resin matrix, the fibers comprising high tenacity fibers, the
first fabric comprising first and second surfaces; and (b) a second
fabric comprising multi-directionally oriented fibers optionally in
a second resin matrix, the second fabric also comprising high
tenacity fibers, the second fabric having first and second
surfaces, the first surface of the second fabric being bonded to
the second surface of the first fabric thereby forming the
composite fabric. Also described is a method of making such fabric
wherein the second fabric layer is used as a support during the
manufacturing process and is thereafter consolidated into a single
structure with the first fabric layer.
Inventors: |
Arvidson; Brian D.;
(Chester, VA) ; Ardiff; Henry G.; (Chesterfield,
VA) ; Bhatnagar; Ashok; (Richmond, VA) ;
Hurst; David A.; (Richmond, VA) ; Wagner; Lori
L.; (Richmond, VA) |
Family ID: |
39709279 |
Appl. No.: |
11/726068 |
Filed: |
March 21, 2007 |
Current U.S.
Class: |
156/241 ;
442/135; 89/36.02; 89/916 |
Current CPC
Class: |
Y10T 442/2623 20150401;
Y10T 428/24058 20150115; B32B 5/26 20130101; F41H 5/0485 20130101;
Y10T 442/2615 20150401; Y10S 428/911 20130101 |
Class at
Publication: |
156/241 ;
442/135; 89/36.02; 89/916 |
International
Class: |
B32B 3/24 20060101
B32B003/24; B32B 5/02 20060101 B32B005/02; F41H 5/00 20060101
F41H005/00 |
Claims
1. A multilayered composite fabric, said composite fabric
comprising: (a) a first fabric comprising non-woven
unidirectionally oriented fibers in a first resin matrix, the first
resin matrix surrounding the fibers, said fibers comprising high
tenacity fibers, said first fabric comprising first and second
surfaces; and (b) a second fabric comprising multi-directionally
oriented fibers optionally in a second resin matrix, said second
fabric comprising high tenacity fibers, said second fabric having
first and second surfaces, said first surface of said second fabric
being bonded to said second surface of said first fabric thereby
forming said composite fabric.
2. The composite fabric of claim 1 wherein said second fabric
comprises a fabric selected from the group consisting of woven
fabrics, knitted fabrics, braided fabrics, felted fabrics, and
paper fabrics.
3. The composite fabric of claim 1 wherein said first and second
fabrics are bonded at least by the resin of said first resin
matrix.
4. The composite fabric of claim 1 wherein said first and second
fabrics are bonded by the resins of said first resin matrix and
said second resin matrix, and the resins in said first resin matrix
and said second resin matrix are chemically the same.
5. The composite fabric of claim 1 wherein said high tenacity
fibers of said first fabric and said second fabric are selected
from the group consisting of polyolefin fibers, aramid fibers,
polybenzazole fibers, polyvinyl alcohol fibers, polyacrylonitrile
fibers, liquid crystal copolyester fibers, polyamide fibers,
polyester fibers, glass fibers, graphite fibers, carbon fibers,
basalt or other mineral fibers, rigid rod polymer fibers, and
blends thereof.
6. The composite fabric of claim 1 wherein said high tenacity
fibers of said first fabric and of said second fabric are selected
from the group consisting of high tenacity polyethylene fibers,
aramid fibers, PBO fibers, graphite fibers, and blends thereof.
7. The composite fabric of claim 1 wherein said high tenacity
fibers of said first fabric and said second fabric comprise high
tenacity polyethylene fibers and/or aramid fibers.
8. The composite fabric of claim 7 wherein said high tenacity
fibers of said first fabric are chemically the same as the high
tenacity fibers of said second fabric.
9. The composite fabric of claim 1 wherein said second fabric is in
the form of a woven fabric.
10. The composite fabric of claim 1 wherein said high tenacity
fibers of said first fabric comprise aramid fibers and said high
tenacity fibers of said second fabric comprise aramid fibers.
11. The composite fabric of claim 10 wherein said second fabric is
in the form of a woven fabric.
12. The composite fabric of claim 1 further comprising a third
fabric, said third fabric comprising non-woven unidirectionally
oriented high tenacity fibers in a third resin matrix, said third
fabric having first and second surfaces, said first surface of said
third fabric being bonded to said second surface of said second
fabric whereby second fabric is disposed between said first fabric
and said third fabric.
13. The composite fabric of claim 1 further comprising third and
fourth fabrics, said third fabric comprising multi-directionally
oriented high tenacity fibers optionally in a third resin matrix,
said third fabric having first and second surfaces, said first
surface of said third fabric being bonded to said second surface of
said second fabric, said fourth fabric comprising non-woven
unidirectionally oriented high tenacity fibers in a fourth resin
matrix, said fourth fabric having first and second surfaces, said
first surface of said fourth fabric being bonded to said second
surface of said third fabric.
14. The composite fabric of claim 1 further comprising a third
fabric comprising multi-directionally oriented high tenacity fibers
optionally in a third resin matrix, said third fabric having first
and second surfaces, said first surface of said third fabric being
bonded to said first surface of said first fabric whereby first
fabric is disposed between said second fabric and said third
fabric.
15. The composite of claim 1 further comprising third and fourth
fabrics, said third fabric comprising non-woven unidirectionally
oriented high tenacity fibers in a third resin matrix, said third
fabric having first and second surfaces, said first surface of said
third fabric being bonded to said second surface of said second
fabric, said fourth fabric comprising multi-directionally oriented
high tenacity fibers optionally in a fourth resin matrix, said
fourth fabric having first and second surfaces, said first surface
of said fourth fabric being bonded to said second surface of said
third fabric.
16. The composite fabric of claim 1 further comprising at least one
plastic film attached to at least one of said first and second
fabrics.
17. A ballistic article comprising the multilayered composite
fabric of claim 1.
18. In a method of forming a composite fabric structure from high
tenacity fibers, the improvement comprising: (a) forming a first
fabric comprising non-woven unidirectionally oriented fibers, said
fibers comprising high tenacity fibers; (b) supporting said first
fabric with a second fabric comprising multi-directionally oriented
fibers, said second fabric comprising high tenacity fibers; (c)
coating a first matrix resin onto said first fabric either before,
after or while said first fabric is supported by said second
fabric, such that said resin matrix extends from said first fabric
and at least into said second fabric, and wherein the resin matrix
surrounds the fibers of at least said first fabric; and (d)
consolidating said first fabric and said second fabric into a
composite fabric such that said first fabric and said second fabric
are bonded together by means of said resin matrix, whereby said
second fabric becomes an integral part of said composite
fabric.
19. The method of claim 18 wherein said second fabric comprises a
woven fabric.
20. The method of claim 19 wherein said high tenacity fibers of
said first fabric and of said second fabric comprise high tenacity
polyethylene fibers and/or aramid fibers.
21. A method of forming a composite fabric structure, said method
comprising: (a) supplying a first fabric comprising non-woven
unidirectionally oriented fibers in a first resin matrix, the first
resin matrix surrounding the fibers, said fibers comprising high
tenacity fibers, said first fabric comprising first and second
surfaces; (b) supplying a second fabric comprising
multi-directionally oriented fibers optionally in a second resin
matrix, said second fabric comprising high tenacity fibers, said
second fabric having first and second surfaces; and (c) bonding
said first surface of said second fabric to said second surface of
said first fabric to thereby form said composite fabric.
22. The method of claim 21 wherein said second fabric comprises a
woven fabric.
23. The method of claim 21 wherein said high tenacity fibers of
said first fabric and of said second fabric comprise high tenacity
polyethylene fibers and/or aramid fibers.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to composite materials which are
useful for ballistic and other applications, and to methods for
their manufacture.
[0003] 2. Description of the Related Art
[0004] Ballistic resistant products are known in the art. They may
be of the flexible or rigid type. Many of these products are based
on high tenacity fibers, and are used in such applications as body
armor, such as bullet-resistant vests.
[0005] One popular type of ballistic resistant product is made from
unidirectionally oriented high tenacity fibers, such as high
tenacity polyethylene fibers or aramid fibers. Such products have
desirable ballistic resistant properties, but require complicated
manufacturing processes. As a result, they are usually more costly
to manufacture than other types of ballistic resistant
composites.
[0006] It would be desirable to provide a ballistic resistant
product that included unidirectionally oriented fibers but could be
produced in a more economical manner, as well as a process for
making such product.
SUMMARY OF THE INVENTION
[0007] In accordance with this invention, there is provided a
multilayered composite fabric, the composite fabric comprising:
[0008] (a) a first fabric comprising non-woven unidirectionally
oriented fibers in a first resin matrix, the fibers comprising high
tenacity fibers, the first fabric comprising first and second
surfaces; and
[0009] (b) a second fabric comprising multi-directionally oriented
fibers optionally in a second resin matrix, the second fabric
comprising high tenacity fibers, the second fabric having first and
second surfaces, the first surface of the second fabric being
bonded to the second surface of the first fabric thereby forming
the composite fabric.
[0010] Further in accordance with this invention, there is provided
in a method of forming a composite fabric structure from high
tenacity fibers, the improvement comprising:
[0011] (a) forming a first fabric comprising non-woven
unidirectionally oriented fibers, the fibers comprising high
tenacity fibers;
[0012] (b) supporting the first fabric with a second fabric
comprising multi-directionally oriented fibers, the second fabric
comprising high tenacity fibers;
[0013] (c) coating a first matrix resin onto the first fabric
either before, after or while the first fabric is supported by the
second fabric, such that the matrix resin extends from the first
fabric and at least into the second fabric, and
[0014] (d) consolidating the first fabric and the second fabric
into a composite fabric such that the first fabric and the second
fabric are bonded together by means of the matrix resin, whereby
the second fabric becomes an integral part of the composite
fabric.
[0015] Further in accordance with this invention, there is provided
a method of forming a composite fabric structure, the method
comprising:
[0016] (a) supplying a first fabric comprising non-woven
unidirectionally oriented fibers in a first resin matrix, the
fibers comprising high tenacity fibers, the first fabric comprising
first and second surfaces;
[0017] (b) supplying a second fabric comprising multi-directionally
oriented fibers optionally in a second resin matrix, the second
fabric comprising high tenacity fibers, the second fabric having
first and second surfaces; and
[0018] (c) bonding the first surface of the second fabric to the
second surface of the first fabric to thereby form the composite
fabric.
[0019] In addition to the two fabric layers, other fabric or
non-fabric layers may be present. For example, there may be a three
layered structure in which both outer layers are either the
unidirectionally oriented fiber layers or the outer layers are the
multi-directionally oriented fiber layers. In addition, four layer
structures may be provided in which the outer layers are both the
unidirectionally oriented fiber layers and the inner layers are
both the multi-directionally oriented fiber layers. If the second
fabric comprises a second matrix resin, preferably it is chemically
the same as the first matrix resin for ease of manufacturability
and uniformity.
[0020] The present invention provides a multilayered composite
material that has excellent ballistic properties. In addition, this
material can be made by using as the supporting structure for the
unidirectionally oriented fiber a layer of or layers of
multi-directionally oriented fabric, such as a woven fabric. The
latter fabric becomes an integral part of the composite material
and therefore reduce the cost of manufacture since there is less
waste. Additionally, the quality of the material is enhanced by
having the supporting layer become an integral part of the
composite material.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention comprises a multilayered composite
fabric which is formed from at least a first fabric layer and a
second fabric layer. The fibers in both of the first and second
fabric layers comprise high tenacity fibers, and the layers are
bonded together.
[0022] For the purposes of the present invention, a fiber is an
elongate body the length dimension of which is much greater that
the transverse dimensions of width and thickness. Accordingly, the
term "fiber" includes monofilament, multifilament, ribbon, strip,
staple and other forms of chopped, cut or discontinuous fiber and
the like having regular or irregular cross-sections. The term
"fiber" includes a plurality of any of the foregoing or a
combination thereof. A yarn is a continuous strand comprised of
many fibers or filaments. Fibers may also be in the form of split
film or tape.
[0023] The cross-sections of fibers useful herein may vary widely.
They may be circular, flat or oblong in cross-section. They may
also be of irregular or regular multi-lobal cross-section having
one or more regular or irregular lobes projecting from the linear
or longitudinal axis of the fibers. It is preferred that the fibers
be of substantially circular, flat or oblong cross-section, most
preferably circular.
[0024] As used herein, the term "high tenacity fibers" means fibers
which have tenacities equal to or greater than about 7 g/d.
Preferably, these fibers have initial tensile moduli of at least
about 150 g/d and energies-to-break of at least about 8 J/g as
measured by ASTM D2256. As used herein, the terms "initial tensile
modulus", "tensile modulus" and "modulus" mean the modulus of
elasticity as measured by ASTM 2256 for a yarn and by ASTM D638 for
an elastomer or matrix material.
[0025] Preferably, the high tenacity fibers have tenacities equal
to or greater than about 10 g/d, more preferably equal to or
greater than about 16 g/d, even more preferably equal to or greater
than about 22 g/d, and most preferably equal to or greater than
about 28 g/d.
[0026] High strength fibers useful in the yarns and fabrics of the
invention include highly oriented high molecular weight polyolefin
fibers, particularly high modulus (or high tenacity) polyethylene
fibers and polypropylene fibers, aramid fibers, polybenzazole
fibers such as polybenzoxazole (PBO) and polybenzothiazole (PBT),
polyvinyl alcohol fibers, polyacrylonitrile fibers, liquid crystal
copolyester fibers, polyamide fibers, polyester fibers, glass
fibers, graphite fibers, carbon fibers, basalt or other mineral
fibers, rigid rod polymer fibers, and mixtures and blends thereof.
Preferred high strength fibers useful in this invention include
polyolefin fibers (more preferably high tenacity polyethylene
fibers), aramid fibers, polybenzazole fibers, graphite fibers, and
mixtures and blends thereof. Most preferred are high tenacity
polyethylene fibers and/or aramid fibers.
[0027] U.S. Pat. No. 4,457,985 generally discusses such high
molecular weight polyethylene and polypropylene fibers, and the
disclosure of this patent is hereby incorporated by reference to
the extent that it is not inconsistent herewith. In the case of
polyethylene, suitable fibers are those of weight average molecular
weight of at least about 150,000, preferably at least about one
million and more preferably between about two million and about
five million. Such high molecular weight polyethylene fibers may be
spun in solution (see U.S. Pat. No. 4,137,394 and U.S. Pat. No.
4,356,138), or a filament spun from a solution to form a gel
structure (see U.S. Pat. No. 4,413,110, German Off. No. 3,004, 699
and GB Patent No. 2051667), or the polyethylene fibers may be
produced by a rolling and drawing process (see U.S. Pat. No.
5,702,657). As used herein, the term polyethylene means a
predominantly linear polyethylene material that may contain minor
amounts of chain branching or comonomers not exceeding about 5
modifying units per 100 main chain carbon atoms, and that may also
contain admixed therewith not more than about 50 weight percent of
one or more polymeric additives such as alkene-l-polymers, in
particular low density polyethylene, polypropylene or polybutylene,
copolymers containing mono-olefins as primary monomers, oxidized
polyolefins, graft polyolefin copolymers and polyoxymethylenes, or
low molecular weight additives such as antioxidants, lubricants,
ultraviolet screening agents, colorants and the like which are
commonly incorporated.
[0028] High tenacity polyethylene fibers (also referred to as
extended chain or high molecular weight polyethylene fibers) are
preferred and are available, for example, under the trademark
SPECTRA.RTM. fibers and yarns from Honeywell International Inc. of
Morristown, N.J., U.S.A.
[0029] Depending upon the formation technique, the draw ratio and
temperatures, and other conditions, a variety of properties can be
imparted to these fibers. The tenacity of the polyethylene fibers
are at least about 7 g/d, preferably at least about 15 g/d, more
preferably at least about 20 g/d, still more preferably at least
about 25 g/d and most preferably at least about 30 g/d. Similarly,
the initial tensile modulus of the fibers, as measured by an
Instron tensile testing machine, is preferably at least about 300
g/d, more preferably at least about 500 g/d, still more preferably
at least about 1,000 g/d and most preferably at least about 1,200
g/d. These highest values for initial tensile modulus and tenacity
are generally obtainable only by employing solution grown or gel
spinning processes. Many of the filaments have melting points
higher than the melting point of the polymer from which they were
formed. Thus, for example, high molecular weight polyethylene of
about 150,000, about one million and about two million molecular
weight generally have melting points in the bulk of 138.degree. C.
The highly oriented polyethylene filaments made of these materials
have melting points of from about 7.degree. C. to about 13.degree.
C. higher. Thus, a slight increase in melting point reflects the
crystalline perfection and higher crystalline orientation of the
filaments as compared to the bulk polymer.
[0030] Preferably the polyethylene employed is a polyethylene
having fewer than about one methyl group per thousand carbon atoms,
more preferably fewer than about 0.5 methyl groups per thousand
carbon atoms, and less than about 1 weight percent of other
constituents.
[0031] Similarly, highly oriented high molecular weight
polypropylene fibers of weight average molecular weight at least
about 200,000, preferably at least about one million and more
preferably at least about two million may be used. Such extended
chain polypropylene may be formed into reasonably well oriented
filaments by the techniques prescribed in the various references
referred to above, and especially by the technique of U.S. Pat. No.
4,413,110. Since polypropylene is a much less crystalline material
than polyethylene and contains pendant methyl groups, tenacity
values achievable with polypropylene are generally substantially
lower than the corresponding values for polyethylene. Accordingly,
a suitable tenacity is preferably at least about 8 g/d, more
preferably at least about 11 g/d. The initial tensile modulus for
polypropylene is preferably at least about 160 g/d, more preferably
at least about 200 g/d. The melting point of the polypropylene is
generally raised several degrees by the orientation process, such
that the polypropylene filament preferably has a main melting point
of at least 168.degree. C., more preferably at least 170.degree. C.
The particularly preferred ranges for the above described
parameters can advantageously provide improved performance in the
final article. Employing fibers having a weight average molecular
weight of at least is about 200,000 coupled with the preferred
ranges for the above-described parameters (modulus and tenacity)
can provide advantageously improved performance in the final
article.
[0032] In the case of extended chain polyethylene fibers,
preparation and drawing of gel-spun polyethylene fibers are
described in various publications, including U.S. Pat. Nos.
4,413,110; 4,430,383; 4,436,689; 4,536,536; 4,545,950; 4,551,296;
4,612,148; 4,617,233; 4,663,101; 5,032,338; 5,246,657; 5,286,435;
5,342,567; 5,578,374; 5,736,244; 5,741,451; 5,958,582; 5,972,498;
6,448,359; 6,969,553 and U.S. patent application publication
2005/0093200, the disclosures of which are expressly incorporated
herein by reference to the extent not inconsistent herewith.
[0033] In the case of aramid fibers, suitable fibers formed from
aromatic polyamides are described, for example, in U.S. Pat. No.
3,671,542, which is incorporated herein by reference to the extent
not inconsistent herewith. Preferred aramid fibers will have a
tenacity of at least about 20 g/d, an initial tensile modulus of at
least about 400 g/d and an energy-to-break at least about 8 J/g,
and particularly preferred aramid fibers will have a tenacity of at
least about 20 g/d and an energy-to-break of at least about 20 J/g.
Most preferred aramid fibers will have a tenacity of at least about
23 g/d, a modulus of at least about 500 g/d and an energy-to-break
of at least about 30 J/g. For example, poly(p-phenylene
terephthalamide) filaments which have moderately high moduli and
tenacity values are particularly useful in forming ballistic
resistant composites. Examples are Twaron.RTM. T2000 from Teijin
which has a denier of 1000. Other examples are Kevlar.RTM. 29 which
has 500 g/d and 22 g/d as values of initial tensile modulus and
tenacity, respectively, as well as Kevlar.RTM. 129 and KM2 which
are available in 400, 640 and 840 deniers from du Pont. Aramid
fibers from other manufacturers can also be used in this invention.
Copolymers of poly(p-phenylene terephthalamide) may also be used,
such as co-poly(p-phenylene terephthalamide 3,4' oxydiphenylene
terephthalamide). Also useful in the practice of this invention are
poly(m-phenylene isophthalamide) fibers sold by du Pont under the
trade name Nomex.RTM..
[0034] High molecular weight polyvinyl alcohol (PV-OH) fibers
having high tensile modulus are described in U.S. Pat. No.
4,440,711 to Kwon et al., the disclosure of which is hereby
incorporated by reference to the extent it is not inconsistent
herewith. High molecular weight PV-OH fibers should have a weight
average molecular weight of at least about 200,000. Particularly
useful PV-OH fibers should have a modulus of at least about 300
g/d, a tenacity preferably at least about 10 g/d, more preferably
at least about 14 g/d and most preferably at least about 17 g/d,
and an energy to break of at least about 8 J/g. PV-OH fiber having
such properties can be produced, for example, by the process
disclosed in U.S. Pat. No. 4,599,267.
[0035] In the case of polyacrylonitrile (PAN), the PAN fiber should
have a weight average molecular weight of at least about 400,000.
Particularly useful PAN fiber should have a tenacity of preferably
at least about 10 g/d and an energy to break of at least about 8
J/g. PAN fiber having a molecular weight of at least about 400,000,
a tenacity of at least about 15 to 20 g/d and an energy to break of
at least about 8 J/g is most useful; and such fibers are disclosed,
for example, in U.S. Pat. No. 4,535,027.
[0036] Suitable liquid crystal copolyester fibers for the practice
of this invention are disclosed, for example, in U.S. Pat. Nos.
3,975,487; 4,118,372 and 4,161,470. Liquid crystal copolyester
fibers are available under the designation Vectran.RTM. fibers from
Kuraray America Inc.
[0037] Suitable polybenzazole fibers for the practice of this
invention are disclosed, for example, in U.S. Pat. Nos. 5,286,833,
5,296,185, 5,356,584, 5,534,205 and 6,040,050. Polybenzazole fibers
are available under the designation Zylon.RTM. fibers from Toyobo
Co.
[0038] Rigid rod fibers are disclosed, for example, in U.S. Pat.
Nos. 5,674,969, 5,939,553, 5,945,537 and 6,040,478. Such fibers are
available under the designation M5.RTM. fibers from Magellan
Systems International.
[0039] Preferably, the fibers in the first fabric layer are
selected from the group of high tenacity polyolefin fibers (more
preferably high tenacity polyethylene fibers), aramid fibers, PBO
fibers, graphite fibers and blends thereof. Likewise, the fibers in
the second fabric layer are selected from the same group of
fibers.
[0040] The fabric layers of this invention are preferably formed
from all or substantially all high tenacity fibers. Alternatively,
at least about 50% by weight of the fibers in the fabric layers are
high tenacity fibers and more preferably at least about 75% by
weight of the fibers in the fabric layers are high tenacity
fibers.
[0041] The first fabric is in the form of a non-woven fabric of
high tenacity unidirectionally oriented fibers. As is known, in
such an arrangement the unidirectionally oriented fibers are
aligned parallel to one another along a common fiber direction. The
unidirectionally oriented fabric may include a minor amount of a
material which provides some cross-directional stability to the
product; such material may be in the form of fibers, yarns or
adhesive yarns all of which are not high tenacity materials, or
resins, adhesives, films and the like that may be spaced along the
length of the unidirectionally oriented fabric but extend at an
angle thereto. Such materials, if present, may comprise up to about
10%, more preferably up to about 5%, by weight of the total weight
of the first fabric.
[0042] The first fabric layer may be constructed via a variety of
methods. Preferably, yarn bundles of the high tenacity filaments
are supplied from a creel and led through guides and into a
collimating comb. The collimating comb aligns the filaments
coplanarly and in a substantially unidirectional fashion. The
fibers may then be led into one or more spreader bars which may be
included in the coating apparatus, or may be located before or
after the coating apparatus.
[0043] The high tenacity fiber network of unidirectionally oriented
fibers forming the first fabric is coated with a matrix resin
composition. As used herein, the term "coating" is used in a broad
sense to describe a fiber network wherein the individual fibers
either have a continuous layer of the matrix composition
surrounding the fibers or a discontinuous layer of the matrix
composition on the surfaced of the fibers. In the former case, it
can be said that the fibers are fully embedded in the matrix
composition. The terms coating and impregnating are interchangeably
used herein.
[0044] Heretofore, in forming such unidirectionally oriented fabric
either before or after coating with the resin matrix the
unidirectional fabric was supported by a carrier web, such as a
release paper or a film substrate. Such previous methods are
described, for example, in U.S. Pat. Nos. 5,552,208 and 6,642,159,
the disclosures of which are expressly incorporated herein by
reference to the extent not inconsistent herewith. In such a
process, the carrier web is eventually stripped away from the
unidirectionally oriented fabric and is discarded.
[0045] In accordance with the present invention, preferably after
coating the unidirectionally oriented fibers with the matrix resin,
the first fabric is supported by means of the second fabric which
may be in roll form; alternatively, the first fabric may be
supported prior to or during the coating step. The second fabric
may be fed beneath the first fabric such that one surface of the
second fabric comes in contact with one surface of the first
fabric, in a manner shown, for example, in the aforementioned U.S.
Pat. No. 6,642,159 except that the carrier web is the second fabric
material. That is, the second fabric layer is attached to the first
fabric layer after coating of the first fabric layer.
Alternatively, the second fabric layer may be in contact with
and/or support the first fabric layer before the coating step and
both fabric layers are then coated in the coating step, such as
shown, for example, in the aforementioned U.S. Pat. No.
5,552,208.
[0046] In one embodiment of the process of this invention, the
unidirectionally oriented fibers of the first fabric are first
coated with the desired matrix resin. After coating, preferably the
excess matrix resin in the first fabric layer is squeezed out, such
as by means of a pair of rollers. Thereafter, the coated first
fabric is placed on the second fabric. Both fabrics are then
consolidated and are either allowed to cool or are heated, whereby
matrix resin from the first fabric bonds at least the contacting
surface of the second fabric to the first fabric to thereby form a
unitary structure. By passing the combined fabric structure into an
oven, the fabrics are dried.
[0047] It is preferred that the second fabric layer does not
include a resin matrix prior to its contact with the coated first
fabric such that the second fabric is at least partially penetrated
by the matrix resin of the first fabric layer. Alternatively, the
second fabric may be precoated with another matrix resin,
preferably of the same or similar chemical structure, prior to
contacting and supporting the first fabric layer. The layers are
then laminated together, using heat and/or pressure. In this case,
more preferably the same resin that is used as the matrix resin for
the first fabric is also used for the second fabric.
[0048] Alternatively, either fabric layer may be totally
impregnated with the matrix resin and then combined with the other
fabric web, which could become saturated or just bonded at the
surface, depending on the amount and viscosity of the resin.
[0049] The matrix resin composition may be applied as a solution,
dispersion or emulsion, or the like, onto the fiber network that
forms the first fabric layer. The matrix resin may be applied by
any desired technique, such as by spraying, dipping, roller
coating, hot melt coating, or the like. As mentioned above, the
coated fabric layers may then be passed through an oven for drying
in which they are subjected to sufficient heat to evaporate the
water or other solvent in the matrix resin composition.
[0050] The second fabric layer is also formed from high tenacity
fibers, but the fibers are oriented in multiple directions in the
fabric. That is, the fibers in the second fabric are
multi-directionally oriented. This means that there are sufficient
fibers which extend in a second direction from the major direction
of the fabric to provide some degree of cross direction strength to
the fabric. The term "multi-directionally oriented fibers" is
distinct from "unidirectionally oriented fibers".
[0051] The second fabric may be in the form of a woven fabric, a
knitted fabric, a braided fabric, a felted fabric, a paper fabric,
and the like. Preferably the second fabric is in the form of a
woven fabric. This second fabric layer may be referred to as a
ballistic textile product.
[0052] As mentioned above, the high tenacity fibers in the second
fabric layer are chosen from the same group of fibers mentioned
above with respect to the first fabric layer. Preferably, the
fibers in the second fabric layer are also selected from the group
of high tenacity polyolefin fibers (more preferably high tenacity
polyethylene fibers), aramid fibers, PBO fibers, graphite fibers
and blends thereof. Most preferably, such fibers are high tenacity
polyethylene fibers and/or aramid fibers.
[0053] If a woven fabric is employed, it may be of any weave
pattern, including plain weave, basket weave, twill, satin, three
dimensional woven fabrics, and any of their several variations.
Plain and basket weave fabrics are preferred and more preferred are
such fabrics having an equal warp and weft count. In one embodiment
as mentioned above, the woven fabric does not include a resin
matrix. In another embodiment, the woven fabric may include a resin
matrix prior to bonding to the first fabric.
[0054] The yarns of the woven fabric may be twisted, over-wrapped
or entangled. The second fabric be woven with yarns having
different fibers in the warp and weft directions, or in other
directions. For example, a woven fabric may be formed with aramid
fibers in the warp direction and high tenacity polyethylene fibers
in the weft direction, or vice versa.
[0055] As mentioned above, the second fabric may alternatively be
in the form of a knitted fabric. Knit structures are constructions
composed of intermeshing loops, with the four major types being
tricot, raschel, net and oriented structures. Due to the nature of
the loop structure, knits of the first three categories are not as
suitable as they do not take full advantage of the strength of a
fiber. Oriented knitted structures, however, use straight inlaid
yarns held in place by fine denier knitted stitches. The yarns are
absolutely straight without the crimp effect found in woven fabrics
due to the interlacing effect on the yarns. These laid in yarns can
be oriented in a monoaxial, biaxial or multiaxial direction
depending on the engineered requirements. It is preferred that the
specific knit equipment used in laying in the load bearing yarns is
such that the yarns are not pierced through.
[0056] The second fabric may alternatively be formed from a
non-woven fabric such as a fabric in the form of a felt, such as
needle punched felts. A felt is a non-woven network of randomly
oriented fibers, preferably at least one of which is a
discontinuous fiber, preferably a staple fiber having a length
ranging from about 0.25 inch (0.64 cm) to about 10 inches (25 cm).
These felts may be formed by several techniques known in the art,
such as by carding or fluid laying, melt blowing and spin laying.
The network of fibers is consolidated mechanically such as by
needle punching, stitch-bonding, hydro-entanglement, air
entanglement, spun bond, spun lace or the like, chemically such as
with an adhesive, or thermally with a fiber to point bond or a
blended fiber with a lower melting point.
[0057] Alternatively, the second fabric may be in the form of a
paper fabric that may be formed, for example, by pulping a liquid
containing the high tenacity fibers.
[0058] In another embodiment, the second fabric may be in the form
of a multilayer composite fabric, such as a fabric that includes a
third layer which may be a unidirectionally oriented fabric or a
multi-directionally oriented fabric. The third layer is also
preferably formed from high tenacity fibers.
[0059] The yarns useful in the various fibrous layers may be of any
suitable denier, and may be of the same or different deniers in
each layer. For example, the yarns may have a denier of from about
50 to about 3000. The selection is governed by considerations of
ballistic effectiveness, other desired properties, and cost. For
woven fabrics, finer yarns are more costly to manufacture and to
weave, but can produce greater ballistic effectiveness per unit
weight. The yarns are preferably from about 200 denier to about
3000 denier. More preferably, the yarns are from about 400 denier
to about 2000 denier. Most preferably, the yarns are from about 500
denier to about 1600 denier.
[0060] The resin matrix for the fiber plies may be formed from a
wide variety of thermoplastic, thermosetting or elastomeric
materials having desired characteristics. In one embodiment, the
elastomeric materials used in such matrix possess initial tensile
modulus (modulus of elasticity) equal to or less than about 6,000
psi (41.4 MPa) as measured by ASTM D638. More preferably, the
elastomer has initial tensile modulus equal to or less than about
2,400 psi (16.5 MPa). Most preferably, the elastomeric material has
initial tensile modulus equal to or less than about 1,200 psi (8.23
MPa). These resinous materials are typically thermoplastic in
nature.
[0061] Alternatively, the resin matrix may be selected to have a
high tensile modulus when cured, as at least about 1.times.10.sup.5
psi (690 MPa). Examples of such materials are disclosed, for
example, in U.S. Pat. No. 6,642,159, the disclosure of which is
expressly incorporated herein by reference to the extent not
inconsistent herewith.
[0062] The proportion of the resin matrix material to fiber in the
composite layers may vary widely depending upon the end use. The
resin matrix material preferably forms about 1 to about 98 percent
by weight, more preferably from about 5 to about 95 percent by
weight, and still more preferably from about 5 to about 40 percent
by weight, and most preferably from about 10 to about 25 percent by
weight, based on the total weight of the fibers and resin
matrix.
[0063] A wide variety of elastomeric materials may be utilized as
the resin matrix. For example, any of the following materials may
be employed: polybutadiene, polyisoprene, natural rubber,
ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers, polysulfide polymers, polyurethane elastomers,
chlorosulfonated polyethylene, polychloroprene, plasticized
polyvinylchloride using dioctyl phthalate or other plasticizers
well known in the art, butadiene acrylonitrile elastomers, poly
(isobutylene-co-isoprene), polyacrylates, polyesters, polyethers,
fluoroelastomers, silicone elastomers, thermoplastic elastomers,
and copolymers of ethylene. Examples of thermosetting resins
include those which are soluble in carbon-carbon saturated solvents
such as methyl ethyl ketone, acetone, ethanol, methanol, isopropyl
alcohol, cyclohexane, ethyl acetone, and combinations thereof.
Among the thermosetting resins are vinyl esters, styrene-butadiene
block copolymers, diallyl phthalate, phenol formaldehyde, polyvinyl
butyral and mixtures thereof, as disclosed in the aforementioned
U.S. Pat. No. 6,642,159. Preferred thermosetting resins for
polyethylene fiber fabrics include at least one vinyl ester,
diallyl phthalate, and optionally a catalyst for curing the vinyl
ester resin.
[0064] One preferred group of materials for polyethylene fiber
fabrics are block copolymers of conjugated dienes and vinyl
aromatic copolymers. Butadiene and isoprene are preferred
conjugated diene elastomers. Styrene, vinyl toluene and t-butyl
styrene are preferred conjugated aromatic monomers. Block
copolymers incorporating polyisoprene and/or polybutadiene may be
hydrogenated to produce thermoplastic elastomers having saturated
hydrocarbon elastomer segments. The polymers may be simple
tri-block copolymers of the type R-(BA).sub.x (x=3-150); wherein A
is a block from a polyvinyl aromatic monomer and B is a block from
a conjugated diene elastomer, or an A-B-A type of elastomer. A
preferred resin matrix is an styrene-isoprene-styrene block
copolymer, such as Kraton.RTM. D1107 styrene-isoprene-styrene block
copolymer available from Kraton Polymer LLC.
[0065] One preferred matrix resin for aramid fibers is a
polyurethane resin, such as a water based polyurethane resin.
[0066] In one preferred embodiment, the matrix resin is chosen such
that the composite fabric is flexible, and is useful in such
applications as soft armor products and the like.
[0067] Following bonding of the first fabric and second fabrics
together, they are preferably wound up in a roll. A separator sheet
may be employed to keep the layers from sticking together during
winding.
[0068] As mentioned above, additional layers may be incorporated in
the composite fabric of the invention. For example, a three layered
structure may be formed by incorporating another unidirectionally
oriented fabric of high tenacity fibers. This additional layer is
bonded to the opposite surface of the second layer from the surface
which is bonded to the first layer. The additional unidirectionally
oriented fabric may be combined with the other fabric layers at the
same time that the other fabric layers are combined, or this third
fabric layer may be preattached to the second fabric layer or
combined therewith after bonding of the first and second fabric
layers. For example, after forming a structure of the first and
second fabrics, the composite structure can again be used to
support another unidirectionally oriented fabric of high tenacity
fibers, with the second fabric layer supporting the second
unidirectionally oriented fabric layer. As an example, the first
formed composite fabric can be positioned beneath the second
unidirectionally oriented fabric with the multi-directionally
oriented fabric being adjacent to a surface of the second
unidirectionally oriented fabric, and the matrix resin of the
second unidirectionally oriented fabric can be pressed against or
into the multi-directionally oriented fabric. The resultant
structure includes the second multi-directionally oriented fabrics
sandwiched between two unidirectionally oriented fabrics.
[0069] Likewise, another multi-directionally oriented fabric (e.g.,
a woven fabric) may be combined with the first and second fabrics
such that it is bonded to the surface of the unidirectionally
oriented first fabric that is not attached to the second fabric. In
this manner, the first unidirectionally oriented fabric layer is
sandwiched between two multi-directionally oriented fabrics.
[0070] In each of these three layered structures, the high tenacity
fibers of each fabric may be the same or different from the fibers
in the other fabric layers. Also, the matrix resin, when present,
in each of the fabric layers is preferably the same or
substantially the same chemically. Alternatively, the matrix resins
of different fabric layers may be different but should be
compatible so that the desired bonding of the layers can be
achieved.
[0071] In another embodiment of the invention, a four layer fabric
construction may be formed from two unidirectionally oriented
fabric layers and two multi-directionally oriented fabric layers.
For example, two woven fabric layers may be bonded together and
form the internal fabric layers of the composite structure, with
two unidirectionally oriented fabric layers forming the outer
layers of the structure.
[0072] Alternatively, a four layer structure may be provided by
suitably bonding two composite fabric structures each formed from a
first and second fabric as described above, with the structures
being bonded such that either the two of the same type of fabric
layers are bonded together or two different types of fabric layers
are bonded together.
[0073] Regardless of the number of fabric layers in the composite
fabric structure, the composite fabric is formed by consolidation
of the various layers. By "consolidating" is meant that the matrix
material and the fibers are combined into a unitary layer.
Consolidation can occur by means of drying, cooling, heating,
pressure or a combination thereof.
[0074] An article may be formed from a number of layers of the
composite fabric structure (whether it be a two layer structure, a
three layer structure, a four layer structure, or a structure with
additional layers). The number of layers of the composite fabric
structure that are present in such an article depends upon a
variety of factors, including the type of application, desired
weight, etc. For example, in a ballistic resistant article such as
a vest, the number of layers of the two fabric composite structure
may range from about 2 to about 60, more preferably from about 8 to
about 50, and most preferably from about 10 to about 40. Such
layers may be combined without bonding the several layers together
in a conventional manner, such as by stitching only along the edge.
To form such an article, the composite fabric can be cut into the
desired shape.
[0075] When several layers of the composite fabrics containing
unidirectionally oriented fibers are employed, the unidirectionally
oriented fabrics are preferably disposed at an angle with respect
to each other (e.g., cross-plied). Such angles may be about
0.degree./90.degree., or any other desired angle.
[0076] Various configurations of the composite fabric can be made
based on the desired application, ballistic threat and desirable
properties such as flame retardancy, durability and water
repellency, among others. For example, one can use aramid materials
for both the supporting multi-directionally oriented fabric layer
and the unidirectional fabric layer, or high tenacity polyethylene
fibers for both such fabric layers. Alternatively, the high
tenacity polyethylene fibers and aramid fibers may be combined in
any desired combination, such as the first fabric being an aramid
fabric and the second fabric being a high tenacity polyethylene
fabric, or the first fabric being a high tenacity polyethylene
fabric and the second fabric being an aramid fabric. In another
embodiment, a graphite unidirectionally oriented fabric may be
attached to a high tenacity polyethylene fiber woven fabric, or a
PBO unidirectional fabric may be attached to an aramid woven
fabric. These materials could arranged in any desired
configuration.
[0077] One or more plastic films can be included in the composite
to permit different composite layers to slide over each other, such
as for ease of forming into a body shape and ease of wearing, or
for other reasons. These plastic films may typically be adhered to
one or both surfaces of the composite fabric. Any suitable plastic
film may be employed, such as films made of polyolefins. Examples
of such films are linear low density polyethylene (LLDPE) films,
ultrahigh molecular weight polyethylene (UHMWPE) films, polyester
films, nylon films, polycarbonate films and the like. These films
may be of any desirable thickness. Typical thicknesses is range
from about 0.1 to about 1.2 mils (2.5 to 30 .mu.m), more preferably
from about 0.2 to about 1 mil (5 to 25 .mu.m), and most preferably
from about 0.2 to about 0.5 mils (5 to 12.5 .mu.m). Most preferred
are films of LLDPE.
[0078] Non-limiting embodiments of the invention include: a
unidirectional non-woven fabric of high tenacity polyethylene yarns
attached to a woven fabric of high tenacity polyethylene yarns; a
unidirectional non-woven fabric of aramid yarns attached to a woven
fabric of aramid yarns; a unidirectional non-woven fabric of high
tenacity polyethylene yarns attached to a woven fabric of aramid
yarns; a unidirectional non-woven fabric of aramid yarns attached
to a woven fabric of high tenacity polyethylene yarns; and other
structures with the same or different high tenacity fibers.
[0079] The composite fabrics of this invention can be used in a
wide variety of applications, such as ballistic products,
structural products, components in the automotive and aerospace
industries, etc. Preferred applications are soft or hard armor
products, such as bullet resistant body armor (vests and the like),
vehicle panels, etc.
[0080] The following non-limiting examples are presented to provide
a more complete understanding of the invention. The specific
techniques, conditions, materials, proportions and reported data
set forth to illustrate the principles of the invention are
exemplary and should not be construed as limiting the scope of the
invention.
EXAMPLES
Example 1
[0081] A composite is formed from layers of unidirectionally
oriented aramid fibers and an aramid woven fabric. Aramid yarns of
1000 denier is fed from a creel and passes through a combing
station to form a unidirectional fiber network. The unidirectional
fabric weighs 45 g/m.sup.2 before coating. The yarns pass into a
tank containing a solution of a polyurethane matrix resin which
impregnates into the unidirectional fabric. The coated
unidirectional fabric next passes through a pair of rollers to
squeeze out excess matrix resin solution and spread the matrix
solution substantially uniformly among and between the filaments.
The resin pick up is about 16 weight percent, based on the total
weight of the coated fabric.
[0082] The coated unidirectional fabric is then placed on a dry
aramid woven fabric (containing no matrix resin) that is fed from a
separate roll. The woven fabric is a plain weave scoured fabric of
840 denier aramid yarns weighing 7 oz/square yard (237.4
g/m.sup.2). The woven fabric is fed onto the bottom of the
unidirectional fabric layer and acts as a support therefor. The
combined structure is fed into a pair of nip rolls which controls
the thickness of the composite fabric and causes the matrix resin
from the unidirectional non-woven fabric to at least contact the
adjacent surface of the woven fabric. The combined structure is
then passed into a drying oven where the matrix resin solvent
volatilizes. The consolidated composite fabric is wound up into a
continuous roll.
[0083] Samples of the composite fabric measuring 18.times.18 inches
(45.7.times.45.7 cm) are tested for ballistic resistance with a
shoot pack weighing 1.00 psf (4.88 kg/m.sup.2) against both 9 mm
full metal jacket (FMJ) 124 grain bullets and 17 grain, 22 caliber,
FSP hardened fragment simulators. It is found that the ballistic
properties of the material are acceptable for ballistic resistant
articles.
Example 2
[0084] Example 1 is repeated except that the unidirectional
non-woven fabric is formed from 1300 denier high tenacity
polyethylene yarns (Spectra.RTM. 1000 from Honeywell International
Inc.), with the unidirectional fiber matrix weighing 53 g/m.sup.2
(before coating). The matrix resin is a styrene-isoprene-styrene
elastomer (Kraton.RTM. D1107). The woven fabric is a plain weave
fabric of high tenacity polyethylene yarns (375 denier yarns of
Spectra.RTM. 1000 fiber from Honeywell International Inc.). The
resin pick up is about 16 weight percent, based on the total weight
of the coated fabric.
[0085] When samples are tested as in Example 1, similar results are
noted.
[0086] The process of the present invention is in contrast to
current manufacturing processes wherein unidirectional tapes are
produced mainly by using a substrate for providing the
cross-directional strength during processing, for keeping the resin
with the unidirectional fibers and for keeping the integrity of the
unidirectional fibers during winding. In such method, the substrate
is subsequently discarded and not used as an integral part of the
finished product. This invention employs a second fabric in the
form of a multi-directionally oriented fabric, such as a ballistic
textile product, which has some level of cross-directional
strength, to replace the discarded substrate with a product that
will provide ballistic properties for the finished article. The
product of this invention can be produced by a process which
reduces the cost of manufacture of the material and the product has
acceptable if not improved ballistic performance.
[0087] With this invention it is possible to reduce the amount of
resin in the composite structure, which can result in higher
ballistic performance per unit weight of the ballistic structure,
such as a vest. The cost of the composite material can be lower and
the number of layers required to produce armor products and the
like can also be reduced.
[0088] Having thus described the invention in rather full detail,
it will be understood that such detail need not be strictly adhered
to but that further changes and modifications may suggest
themselves to one skilled in the art, all falling within the scope
of the invention as defined by the subjoined claims.
* * * * *