U.S. patent application number 13/593813 was filed with the patent office on 2014-03-27 for fiber - resin composites and ballistic resistant armor articles containing the fiber - resin composites.
This patent application is currently assigned to E I DU PONT DE NEMOURS AND COMPANY. The applicant listed for this patent is LEOPOLDO ALEJANDRO CARBAJAL. Invention is credited to LEOPOLDO ALEJANDRO CARBAJAL.
Application Number | 20140087124 13/593813 |
Document ID | / |
Family ID | 49880920 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140087124 |
Kind Code |
A1 |
CARBAJAL; LEOPOLDO
ALEJANDRO |
March 27, 2014 |
FIBER - RESIN COMPOSITES AND BALLISTIC RESISTANT ARMOR ARTICLES
CONTAINING THE FIBER - RESIN COMPOSITES
Abstract
A fiber-resin composite useful in a ballistic resistant armor
article comprises a first nonwoven layer comprising a first
plurality of yarns arranged parallel with each other and a second
nonwoven layer comprising a second plurality of yarns arranged
parallel with each other. The first plurality of yarns have an
orientation in a direction that is different from the orientation
of the second plurality of yarns, The composite further comprises a
binding resin partially coating portions of internal surfaces of
the yarns and partially filling some space between the filaments of
the yarns so as to leave discrete areas of yarn surfaces that are
free from binder resin coating, A viscoelastic resin coats at least
portions of external surfaces of the yarns and fills in some space
between the filaments of the yarns. A binding yarn is interlaced
transversely within the first and second nonwoven layers.
Inventors: |
CARBAJAL; LEOPOLDO ALEJANDRO;
(Newark, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CARBAJAL; LEOPOLDO ALEJANDRO |
Newark |
DE |
US |
|
|
Assignee: |
E I DU PONT DE NEMOURS AND
COMPANY
Wilmington
DE
|
Family ID: |
49880920 |
Appl. No.: |
13/593813 |
Filed: |
August 24, 2012 |
Current U.S.
Class: |
428/111 ;
428/107 |
Current CPC
Class: |
Y10T 428/24074 20150115;
B32B 5/022 20130101; Y10T 428/24107 20150115; F41H 5/0478
20130101 |
Class at
Publication: |
428/111 ;
428/107 |
International
Class: |
F41H 5/04 20060101
F41H005/04 |
Claims
1. A fiber-resin fiber-resin composite useful in a ballistic
resistant soft armor article, comprising: (a) from 75.0 to 94.0
weight percent of a first nonwoven layer comprising a first
plurality of yarns having a yarn tenacity of from 10 to 65 grams
per dtex, a modulus of from 100 to 3500 grams per dtex and an
elongation at break of 3.8 to 5.0 percent, the first plurality of
yarns arranged parallel with each other, a second nonwoven layer
comprising a second plurality of yarns having a yarn tenacity of
from 10 to 65 grams per dtex, a modulus of from 100 to 3500 grams
per dtex and an elongation at break of 3.8 to 5.0 percent, the
second plurality of yarns arranged parallel with each other,
wherein the first plurality of yarns of the first nonwoven layer
have an orientation in a direction that is different from the
orientation of the second plurality of yarns in the second nonwoven
layer, (b) from 1.0 to 10.0 weight percent of a thermoset or
thermoplastic binding resin partially coating portions of internal
surfaces of the first plurality and the second plurality of yarns
and partially filling some space between the filaments in the first
plurality and the second plurality of yarns in the region of the
interface between the two nonwoven layers so as to leave discrete
areas of yarn surfaces that are free from binder resin coating, (c)
from 0.1 to 10.0 weight percent of a viscoelastic resin coating at
least portions of external surfaces of the first plurality and the
second plurality of yarns and filling some space between the
filaments in the first plurality and the second plurality of yarns,
and (d) a transverse binding yarn interlaced transversely within
the first and second nonwoven layers. wherein the weight
percentages are expressed relative to the total weight of the
fiber-resin composite.
2. The fiber-resin composite of claim 1, wherein the yarns of the
first and second pluralities of yarns have a yarn linear density of
50 to 4500 dtex and a yarn modulus of 100 to 3500 g/dtex.
3. The fiber-resin composite of claim 1, wherein the yarns of the
first and second pluralities of yarns have a yarn tenacity of 20 to
35 grams per dtex.
4. The fiber-resin composite of claim 1, wherein the yarns of the
first and second pluralities of yarns have an yarn elongation at
break of 3.8 to 4.5 percent.
5. The fiber-resin composite of claim 1, wherein the second
plurality of yarns in the second nonwoven layer are oriented
orthogonally to the first plurality of yarns in the first nonwoven
layer.
6. The fiber-resin composite of claim 1, wherein the first and the
second pluralities of yarns are present in the first and the second
nonwoven layers as substantially distinct yarns.
7. The fiber-resin composite of claim 1, wherein the first and
second nonwoven layers comprise yarns comprising filaments of
para-aramid, polyolefin, polyazole or blends thereof.
8. The fiber-resin composite of claim 1, wherein the viscoelastic
resin is polyolefin, polyvinyl alcohol, polyisoprene,
polybutadiene, polybutene, polyisobutylene, polyester,
polyacrylate, polyamide, polysulfone, polysulfide; polyurethane,
polycarbonate, polyfluorocarbon, silicone, glycol, liquid block
copolymer, polyacrylic, epoxy, phenolic, liquid rubber, styrene
copolymer or mixtures thereof.
9. The fiber-resin composite of claim 1, wherein the thermoplastic
binding resin is polyurethane, polyethylene or a blend of
elastomeric block copolymer and polyethylene copolymer.
10. The fiber-resin composite of claim 1 wherein the area of yarn
surface in the region of the interface between the nonwoven layers
that is free from binding resin is from 40 to 95 percent of the
total surface area of the yarn surfaces in the region of the
interface between the nonwoven layers.
11. The fiber-resin composite of claim 1, wherein the transverse
yarn comprises a plurality of filaments wherein the filaments are
polyester filaments, polyethylene filaments, polyamide filaments,
aramid filaments, polyareneazole filaments, polypyridazole
filaments, polybenzazole filaments, or mixtures thereof.
12. The fiber-resin composite of claim 8, wherein the viscoelastic
resin is polybutene or polyisobutylene.
13. A fiber-resin fiber-resin composite useful in a ballistic
resistant soft armor article, comprising: (a) from 75.0 to 94.0
weight percent of a first nonwoven layer comprising a first
plurality of yarns having a yarn tenacity of from 10 to 65 grams
per dtex, a modulus of from 100 to 3500 grams per dtex and an
elongation at break of 3.8 to 5.0 percent, the first plurality of
yarns arranged parallel with each other, a second nonwoven layer
comprising a second plurality of yarns having a yarn tenacity of
from 10 to 65 grams per dtex, a modulus of from 100 to 3500 grams
per dtex and an elongation at break of 3.8 to 5.0 percent, the
second plurality of yarns arranged parallel with each other, a
third nonwoven layer comprising a third plurality of yarns having a
yarn tenacity of from 10 to 65 grams per dtex, a modulus of from
100 to 3500 grams per dtex and an elongation at break of 3.8 to 5.0
percent, the third plurality of yarns arranged parallel with each
other, a fourth nonwoven layer comprising a fourth plurality of
yarns having a yarn tenacity of from 10 to 65 grams per dtex, a
modulus of from 100 to 3500 grams per dtex and an elongation at
break of 3.8 to 5.0 percent, the fourth plurality of yarns arranged
parallel with each other, wherein the second plurality of yarns of
the second nonwoven layer have an orientation in a direction that
is different from the orientation of the first plurality of yarns
in the first nonwoven layer and the third plurality of yarns in the
third nonwoven layer, and the fourth plurality of yarns of the
fourth nonwoven layer have an orientation in a direction that is
different from the orientation of the third plurality of yarns in
the third nonwoven layer, (b) from 1.0 to 10.0 weight percent of a
thermoset or thermoplastic binding resin partially coating portions
of internal surfaces of the first, second, third and fourth
pluralities of yarns and partially filling some space between the
filaments of the first, second, third and fourth pluralities of
yarns in the region of the interfaces between the nonwoven yarn
layers so as to leave discrete areas of yarn surfaces that are free
from binder resin coating, and (c) from 0.1 to 10.0 weight percent
of a viscoelastic resin coating at least portions of external
surfaces of the first plurality and the fourth plurality of yarns
and filling some space between the filaments in the first plurality
and the fourth plurality of yarns, and (d)) a transverse binding
yarn interlaced transversely within the first and fourth nonwoven
layers. wherein the weight percentages are expressed relative to
the total weight of the fiber-resin composite.
14. A ballistic resistant armor article comprising a plurality of
the fiber-resin fiber-resin composites of claim 1.
15. A ballistic resistant armor article comprising a plurality of
the fiber-resin fiber-resin composites of claim 13.
16. A ballistic resistant armor article of claim 14 comprising a
plurality of the fiber-resin fiber-resin composites of claim 1 as a
strike face.
17. A ballistic resistant armor article of claim 15, comprising a
plurality of the fiber-resin fiber-resin composites of claim 13 as
a strike face.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to fiber-resin composites and
ballistic resistant armor articles containing the fiber-resin
composites. The fiber-resin composites comprise layers of yarns
such as yarns of para-aramid or polyethylene filaments.
[0003] 2. Description of Related Art
[0004] U.S. Pat. No. 6,990,886 to Citterio discloses an unfinished
multilayer structure used to produce a finished multilayer
anti-ballistic fiber-resin composite. The unfinished multilayer
structure includes a first layer of threads parallel with each
other, superimposed, with the interpositioning of a binding layer
on at least a second layer of threads which are parallel with each
other. The threads of the first layer are set in various directions
with respect to the threads of the second layer. The two layers are
also joined by binding threads made of a thermoplastic or
thermosetting material or of a material which is water-soluble or
soluble in a suitable solvent.
[0005] There is an ongoing need to provide multilayer structures
having a lower resistance to axial movement between the layers that
will provide a more flexible soft body armor article with enhanced
ballistic performance at a similar or lower weight.
BRIEF SUMMARY OF THE INVENTION
[0006] This invention is directed to a fiber-resin composite useful
in a ballistic resistant armor article, comprising:
[0007] (a) from 75.0 to 94.0 weight percent of
[0008] a first nonwoven layer comprising a first plurality of yarns
having a yarn tenacity of from 10 to 65 grams per dtex, a modulus
of from 100 to 3500 grams per dtex and an elongation at break of
3.8 to 5.0 percent, the first plurality of yarns arranged parallel
with each other,
[0009] a second nonwoven layer comprising a second plurality of
yarns having a yarn tenacity of from 10 to 65 grams per dtex, a
modulus of from 100 to 3500 grams per dtex and an elongation at
break of 3.8 to 5.0 percent, the second plurality of yarns arranged
parallel with each other,
[0010] wherein the first plurality of yarns of the first nonwoven
layer have an orientation in a direction that is different from the
orientation of the second plurality of yarns in the second nonwoven
layer,
[0011] (b) from 1.0 to 10.0 weight percent of a thermoset or
thermoplastic binding resin partially coating portions of internal
surfaces of the first plurality and the second plurality of yarns
and partially filling some space between the filaments in the first
plurality and the second plurality of yarns in the region of the
interface between the two nonwoven layers so as to leave discrete
areas of yarn surfaces that are free from binder resin coating,
[0012] (c) from 0.1 to 10.0 weight percent of a viscoelastic resin
coating at least portions of external surfaces of the first
plurality and the second plurality of yarns and filling some space
between the filaments in the first plurality and the second
plurality of yarns, and
[0013] (d) a transverse binding yarn interlaced transversely within
the first and second nonwoven layers.
[0014] wherein the weight percentages are expressed relative to the
total weight of the fiber-resin composite.
[0015] The invention is further directed to a fiber-resin composite
of the aforesaid character comprising four nonwoven layers wherein
the yarns in any one layer have an orientation that is different
from the yarns in an adjacent layer.
BRIEF SUMMARY OF THE DRAWINGS
[0016] FIG. 1 shows a plan view in perspective of a fiber-resin
composite used to produce a ballistic resistant armor article.
[0017] FIG. 2 shows a sectional view taken at 2-2 in FIG. 1.
[0018] FIG. 3 shows a sectional view of another embodiment
comprising four nonwoven layers.
[0019] FIGS. 4A to 4D show various arrangements of the fiber-resin
composite in a ballistic resistant soft armor article.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention is directed to a fiber-resin composite
useful in a ballistic resistant soft armor article. The fiber-resin
composite comprises a plurality of nonwoven fibrous layers, a
viscoelastic resin, a thermoset or thermoplastic binding resin and
binding yarns.
The Nonwoven Layers
[0021] In one embodiment the fiber-resin composite comprises two
layers of nonwoven fabric and in a further embodiment it comprises
four layers of nonwoven fabric. A fiber-resin composite comprising
a number of layers other than two or four is also possible. By
"nonwoven" we mean a fabric that does not have interlacing or
interwoven yarns. Further a nonwoven is not a fabric comprising
filaments that are oriented in random orientations within a
layer.
[0022] The first nonwoven layer comprises a first plurality of
first yarns. The first plurality of first yarns are arranged
parallel with each other.
[0023] The second nonwoven layer comprises a second plurality of
second yarns. The second plurality of second yarns are arranged
parallel with each other.
[0024] The third nonwoven layer comprises a third plurality of
third yarns. The third plurality of third yarns are arranged
parallel with each other.
[0025] The fourth nonwoven layer comprises a fourth plurality of
fourth yarns. The fourth plurality of fourth yarns are arranged
parallel with each other.
[0026] The orientation of yarns in one layer of the fiber-resin
composite is different from the orientation of yarns in an adjacent
layer.
[0027] FIG. 1 shows generally at 10, a fiber-resin composite
comprising two nonwoven layers 11a and 11b of reinforcement yarns
12a and 12b. The orientation of the first plurality of yarns 12a in
the first layer 11a of the fiber-resin composite is different from
the orientation of the second plurality of yarns 12b in the second
layer 11b. As an example, the orientation of yarns in a first layer
may be at zero degrees i.e. in the machine direction while the
yarns in a second layer may be oriented at an angle of 90 degrees
with respect to the orientation of yarns in the first layer. The
machine direction is the long direction within the plane of the
fiber-resin composite, that is, the direction in which the
fiber-resin composite is produced. Examples of other yarn
orientation angles are +45 degrees and -45 degrees with respect to
the machine direction. In a preferred embodiment the yarns in
successive layers of the nonwoven fiber-resin composite are
oriented at zero degrees and 90 degrees with respect to each other.
In a four layer fiber-resin composite, the yarns may be oriented at
angles of zero degrees, 90 degrees, zero degrees, 90 degrees
respectively. FIG. 2 shows a sectional view taken at 2-2 in FIG.
1.
[0028] In a further embodiment the yarns in the first and second
layers although being orthogonal to each other are arranged at an
angle of +45 degrees and -45 degrees relative to the machine
direction. Other embodiments include other angles between the yarns
in adjacent layers. In some of these embodiments the yarns in
adjacent layers need not be orthogonal to each other.
[0029] FIG. 3 shows generally at 30 a sectional view of a
fiber-resin composite comprising four nonwoven layers of
reinforcement yarns. The orientation of yarns 32a and 32c in the
first and third layers respectively are in the same direction. The
orientation of yarns 32b and 32d in the second and fourth layers
respectively are in the same direction. The orientation of the
yarns in the first and third layers is orthogonal to the
orientation of yarns in the second and fourth layers.
[0030] In some embodiments, the fiber-resin composite comprises
nonwoven layers having yarns all of the same polymer. In some other
embodiments of the fiber-resin composite, the yarns in different
nonwoven layers may comprise different polymers. In yet some other
embodiments the yarns within a nonwoven layer may comprise
different polymers.
The Yarns
[0031] Each of the first yarns comprises a first plurality of first
filaments. Each of the second yarns comprises a second plurality of
second filaments. Each of the third yarns comprises a third
plurality of third filaments. Each of the fourth yarns comprises a
fourth plurality of fourth filaments. The first, second, third and
fourth filaments may be of para-aramid, polyolefin or polyazole. In
a preferred embodiment, the filaments are para-aramid.
[0032] The first, second, third and fourth yarns preferably have a
yarn tenacity of from 10 to 65 grams per dtex. In some embodiments
the yarn tenacity is from 15 to 40 grams per dtex and in yet other
embodiments the yarn tenacity is from 20 to 35 grams per dtex. The
first, second, third and fourth yarns preferably have a yarn
modulus of from 100 to 3500 grams per dtex. In some embodiments the
yarn modulus is from 150 to 2700 grams per dtex. The first, second,
third and fourth yarns preferably have a linear density of from 50
to 4,500 dtex. In some embodiments the yarn linear density is from
100 to 3500 dtex and in yet other embodiments the linear density is
from 300 to 1800 dtex. The first, second, third and fourth yarns
preferably have an elongation to break of from 3.8 to 5.0 percent.
In still some other embodiments, the elongation to break is from
3.8 to 4.5 percent.
[0033] A finished yarn may also be made by assembling or roving
together two precursor yarns of lower linear density. For example
two precursor yarns each having a linear density of 850 dtex can be
assembled into a finished yarn having a linear density of 1700
dtex.
[0034] Each nonwoven layer has a basis weight of from 30 to 800
g/m.sup.2. In some preferred embodiments the basis weight of each
layer is from 45 to 500 g/m.sup.2. In some other embodiments the
basis weight of each layer is from 55 to 300 g/m.sup.2. In yet some
other embodiments, the layers of the fiber-resin composite all have
a similar weight.
[0035] Untwisted yarns are preferred because they offer higher
ballistic resistance than twisted yarns and because they spread to
a wider aspect ratio than twisted yarns. They enable more
consistent fiber coverage across the layer.
[0036] The layers comprise a plurality of yarns having a plurality
of continuous filaments.
[0037] In one embodiment, the yarns used in the nonwoven layers
form a substantially flattened array of filaments wherein
individual yarn bundles are difficult to detect. In such an
embodiment, the filaments are uniformly arranged in the layer,
meaning there is less than a 20 percent difference in the thickness
of the flattened array. The filaments from one yarn shift and fit
next to adjacent yarns, forming a continuous array of filaments
across the layer. In an alternative embodiment, the yarns can be
positioned such that small gaps are present between the flattened
yarn bundles, or the yarns may be positioned such that the yarn
bundles butt up against other bundles, while retaining an obvious
yarn structure. In other embodiments, the yarns are present in
layers as substantially distinct yarns.
[0038] It is believed the use of yarns having an elongation at
break of from 3.8 to 5.0 percent allows for the use of thicker
layers in the fiber-resin composite without an appreciable loss in
ballistic performance.
[0039] In some embodiments, the fiber-resin composite comprises at
least two nonwoven layers having a ratio of the thickness of any
one layer to the equivalent diameter of the filaments comprising
the layer of at least 13. In some other embodiments of the
fiber-resin composite, the ratio of the thickness of any layer to
the equivalent diameter of the filaments comprising the layer is at
least 13, more preferably at least 16 and most preferably at least
19. By "equivalent diameter" of a filament we mean the diameter of
a circle having a cross-sectional area equal to the average
cross-sectional area of the filaments comprising the layer. The
ratio is calculated by first determining the thickness of a layer
in the fiber-resin composite, typically by measuring the average
thickness of the final fiber-resin composite and dividing by the
number of layers, and then dividing by the equivalent diameter of a
filament used in a layer. Typically, all of the layers are of the
same basis weight and all of the layers have the same filaments. If
resin is present between the successive yarn layers, the thickness
of a layer is calculated by first determining the overall thickness
of the fiber-resin composite and dividing that thickness by the
number of yarn layers in the fiber-resin composite.
[0040] The yarns comprise from 75.0 to 94.0 weight percent based on
the total weight of the fiber-resin composite. In some embodiments
the yarn comprises 85 or 90 weight percent based on the total
weight of the fiber-resin composite.
The Filaments
[0041] For purposes herein, the term "filament" is defined as a
relatively flexible, macroscopically homogeneous body having a high
ratio of length to width across its cross-sectional area
perpendicular to its length. The filament cross section can be any
shape, but is typically round or bean shaped. The yarns may also be
round, bean shaped or oval in cross section. The filaments can be
any length. Preferably the filaments are continuous. Multifilament
yarn spun onto a bobbin in a package contains a plurality of
continuous filaments. The filaments are solid, that is they are not
hollow.
[0042] The yarns of the present invention are made with filaments
comprising polymer of para-aramid, polyolefin or polyazole. Yarns
of different polymer may be used in a nonwoven layer.
[0043] As used herein, the term para-aramid filaments means
filaments made of para-aramid polymer. The term aramid means a
polyamide wherein at least 85% of the amide (--CONH--) linkages are
attached directly to two aromatic rings. Suitable aramid fibers are
described in Man-Made Fibres--Science and Technology, Volume 2, in
the section titled Fibre-Forming Aromatic Polyamides, page 297, W.
Black et al., Interscience Publishers, 1968. Aramid fibers and
their production are, also, disclosed in U.S. Pat. Nos. 3,767,756;
4,172,938; 3,869,429; 3,869,430; 3,819,587; 3,673,143; 3,354,127;
and 3,094,511.
[0044] The preferred para-aramid is poly (p-phenylene
terephthalamide) which is called PPD-T. By PPD-T is meant the
homopolymer resulting from mole-for-mole polymerization of
p-phenylene diamine and terephthaloyl chloride and, also,
copolymers resulting from incorporation of small amounts of other
diamines with the p-phenylene diamine and of small amounts of other
diacid chlorides with the terephthaloyl chloride. As a general
rule, other diamines and other diacid chlorides can be used in
amounts up to as much as about 10 mole percent of the p-phenylene
diamine or the terephthaloyl chloride, or perhaps slightly higher,
provided only that the other diamines and diacid chlorides have no
reactive groups which interfere with the polymerization reaction.
PPD-T, also, means copolymers resulting from incorporation of other
aromatic diamines and other aromatic diacid chlorides such as, for
example, 2, 6-naphthaloyl chloride or chloro- or
dichloroterephthaloyl chloride or 3, 4'-diaminodiphenylether. In
some preferred embodiments, the yarns of the fiber-resin composite
consist solely of PPD-T filaments; in some preferred embodiments,
the layers in the fiber-resin composite consist solely of PPD-T
yarns; in other words, in some preferred embodiments all filaments
in the fiber-resin composite are PPD-T filaments.
[0045] Additives can be used with the aramid and it has been found
that up to as much as 10 percent or more, by weight, of other
polymeric material can be blended with the aramid. Copolymers can
be used having as much as 10 percent or more of other diamine
substituted for the diamine of the aramid or as much as 10 percent
or more of other diacid chloride substituted for the diacid
chloride or the aramid.
[0046] When the polymer is polyolefin, polyethylene or
polypropylene is preferred. The term "polyethylene" means a
predominantly linear polyethylene material of preferably more than
one million molecular weight that may contain minor amounts of
chain branching or comonomers not exceeding 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-1-polymers, in particular low
density polyethylene, propylene, and the like, or low molecular
weight additives such as anti-oxidants, lubricants, ultra-violet
screening agents, colorants and the like which are commonly
incorporated. Such is commonly known as extended chain polyethylene
(ECPE) or ultra high molecular weight polyethylene (UHMWPE
[0047] Yarns may also comprise polyazole filaments. In some
embodiments, the polyazoles are polyarenazoles such as
polybenzazoles and polypyridazoles. Suitable polyazoles include
homopolymers and, also, copolymers. Additives can be used with the
polyazoles and up to as much as 10 percent, by weight, of other
polymeric material can be blended with the polyazoles. Also
copolymers can be used having as much as 10 percent or more of
other monomer substituted for a monomer of the polyazoles. Suitable
polyazole homopolymers and copolymers can be made by known
procedures.
[0048] Preferred polybenzazoles are polybenzimidazoles,
polybenzothiazoles, and polybenzoxazoles and more preferably such
polymers that can form fibers having yarn tenacities of 30 gpd or
greater. If the polybenzazole is a polybenzothioazole, preferably
it is poly(p-phenylene benzobisthiazole). If the polybenzazole is a
polybenzoxazole, preferably it is poly(p-phenylene benzobisoxazole)
and more preferably poly(p-phenylene-2,6-benzobisoxazole) called
PBO.
[0049] Preferred polypyridazoles are polypyridimidazoles,
polypyridothiazoles, and polypyridoxazoles and more preferably such
polymers that can form fibers having yarn tenacities of 30 gpd or
greater. In some embodiments, the preferred polypyridazole is a
polypyridobisazole. A preferred poly(pyridobisozazole) is
poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d']bisimidazole
which is called PIPD. Suitable polypyridazoles, including
polypyridobisazoles, can be made by known procedures.
[0050] Other yarns based on polymers or copolymers capable of
making yarns having a yarn tenacity of about 30 to about 40 grams
per dtex are also suitable for use in the fiber-resin
composite.
The Thermoset or Thermoplastic Binding Resin
[0051] The fiber-resin composite has a resin rich binding layer
(binder) in the region of the interface between the respective
nonwoven layers. In a two layer fiber-resin composite the binder is
in the interface region between the first nonwoven layer and the
second nonwoven layer. In a three layer fiber-resin composite, the
binder preferably is in the interface regions between the first
nonwoven layer and the second nonwoven layer and between the second
nonwoven layer and the third nonwoven layer. In a four layer
fiber-resin composite, the binder preferably is in the interface
regions between the first nonwoven layer and the second nonwoven
layer, between the second nonwoven layer and the third nonwoven
layer and between the third nonwoven layer and the fourth nonwoven
layer. The binder layer is shown at 13 in FIGS. 1 and 2 and at 33
in FIG. 3. Preferably, the binding layer does not fully impregnate
into the yarn bundle but penetrates into at least portions of the
internal surfaces of the yarns in each layer in the interface
region and fills some space between the filaments in each layer.
Preferably, the binding layer is discontinuous so as to provide for
discrete areas of yarn surfaces in the region of the interface
between the nonwoven layers that are free from binding layer
coating. Such binder free areas are shown at 25 in FIG. 2 and at 35
in FIG. 3. In some embodiments the binding layer is a resin. The
resin may be a thermoset or thermoplastic material. A suitable
binding resin comprises a blend of elastomeric block copolymers and
polyethylene copolymers. In one embodiment of this resin blend,
polyethylene copolymers comprise from 50 to 75 weight percent and
elastomeric block copolymers comprise from 25 to 50 weight percent
of the blend.
[0052] In some embodiments, the binding layer is in the form of a
film. Suitable materials for the binding layer include polyolefinic
films, thermoplastic elastomeric films, polyester films, polyamide
films, polyurethane films and mixtures thereof. Useful polyolefinic
films include low density polyethylene films, high density
polyethylene films and linear low density polyethylene films. The
films may be perforated by any suitable means to provide resin free
areas. As an alternative to a binding layer, the binder may be in
the form of a scrim, mesh, grid, resin or powder deposition or some
other suitable form capable of providing discrete areas of yarn
surfaces that are free from binder resin coating. By scrim or mesh
is meant a lightweight fabric characterized by open spaces between
the yarns. The scrim may be woven, knit, lace, net, crochet or
other suitable style. Preferably a grid comprises polymeric or
elastomeric strips or yarns. The strips or yarns may be chemically
or mechanically bonded.
[0053] In some other embodiments, the binding layer is in the form
of a porous (open) polymeric nonwoven web. Suitable polymers for
the nonwoven web include polyethylene, polypropylene,
polyetheretherketone (PEEK) and polyetherketoneketone (PEKK). In
some embodiments, the weight of the nonwoven web is from 3 to 60
grams per square meter (gsm). In other embodiments, the weight of
the nonwoven web is from 5 to 40 gsm.
[0054] In an alternative embodiment, the binding layer may be in
the form of a low areal weight film that is attached at various
contact points to the surface of the nonwoven layers so as to leave
discrete areas of a nonwoven layer not attached to the film. Such a
film may be continuous or discontinuous and preferably has an areal
weight of less than 60 gsm. One means of forming the contact points
between a nonwoven layer and a film is by localized melting of the
film.
[0055] The area of yarn surface in the region of the interface
between the nonwoven layers that is free from binding material is
at least 40 percent of the total surface area of the yarn surfaces
in the region of the interface between the nonwoven layers. In some
embodiments the binder free area on the yarn surface is at least 65
percent or at least 90 percent or even up to 95 percent. If the
amount of binding resin is too low, the yarns can move and escape
from the path of the projectile leading to poor anti-ballistic
performance. The minimum amount of binding resin must therefore be
sufficient to prevent such yarn movement. If the amount of binding
resin is too high, then the flexibility of the anti-ballistic
article is impaired.
[0056] The shape of the resin free areas can take any convenient
form. Exemplary examples of shapes include squares, rectangles,
triangles, diamonds, chevrons, circles and ovals. In one
embodiment, there is a distance between adjacent resin free areas
of no greater than 89 mm (3.5''). In another embodiment, there is a
distance between adjacent resin free areas of no greater than 38 mm
(1.5''). In yet another embodiment, there is a distance between
adjacent resin free areas of no greater than 15 mm (0.6'').
[0057] It is believed that the resin free areas between the yarn
layers reduce the resistance to axial movement of adjacent
layers.
[0058] Preferably the binding layer is present in the fiber-resin
composite in an amount from 1.0 to 10.0 or even 1.0 to 7.0 weight
percent based on the total weight of the fiber-resin composite.
[0059] The binding layer is applied by the steps of (i) forming a
first nonwoven layer comprising a first plurality of yarns
comprising a first plurality of filaments, the first plurality of
yarns arranged parallel with each other (ii) positioning the first
surface of the resin binding layer on one surface of the first
nonwoven layer (iii) forming a second nonwoven layer comprising a
second plurality of yarns comprising a second plurality of
filaments, the second plurality of yarns arranged parallel with
each other, (iv) positioning the second nonwoven layer onto the
second surface of the resin binding layer such that the yarn
orientation in one layer is different from the yarn orientation in
an adjacent layer and (v) repeating steps (i) to (iv) as required
to add additional nonwoven layers to the fiber-resin composite.
The Viscoelastic Resin
[0060] The yarns of the outer surfaces of the two outer layers of
the fiber-resin composite are coated with a resin solution
comprising a viscoelastic resin and a solvent. The coating also
fills some space between the filaments in the yarns in the region
of the outer surfaces of the two outer nonwoven layers of the
fiber-resin composite. This resin is shown at 14 in FIGS. 1 and 2
and at 34 in FIG. 3. The viscoelastic resin may be thermoplastic or
thermoset. Suitable materials include polymers or resins in the
form of a viscous or viscoelastic liquid. Preferred materials are
polyolefins, in particular polyalpha-olefins or modified
polyolefins, polyvinyl alcohol derivatives, polyisoprenes,
polybutadienes, polybutenes, polyisobutylenes, polyesters,
polyacrylates, polyamides, polysulfones, polysulfides,
polyurethanes, polycarbonates, polyfluoro-carbons, silicones,
glycols, liquid block copolymers,
polystyrene-polybutadiene-polystyrene, ethylene co-polypropylene,
polyacrylics, epoxies, phenolics and liquid rubbers. Preferred
polyolefins are polyethylene and polypropylene. Preferred glycols
are polypropylene glycol and polyethylene glycol. A preferred
copolymer is polybutadiene-co-acrylonitrile. Copolymers based on
styrene may also be used. Such styrene copolymers are available
under the tradename Kraton and include styrene-butadiene (SBS),
styrene-isoprene (SIS), styrene-ethylene/butylene-styrene (SEBS)
and styrene-ethylene/propylene-styrene (SEPS). Another suitable
copolymer is based on styrene-isoprene-styrene (SIS) block
copolymer and is available under the tradename PRINLIN.
Polyisobutylene is a suitable rubber based coating material. In a
preferred embodiment, the resin coating does not fully impregnate
the yarns.
[0061] Preferably the visco-elastic resin is present in the
fiber-resin composite in an amount from 0.1 to 10.0 weight percent
and more preferably from 4.0 to 8.0 weight percent based on the
total weight of the fiber-resin composite.
[0062] The solvent of the visco-elastic resin may be aliphatic,
aromatic, cyclic or based on halogenated hydrocarbons. More
preferably the solvent is non-polar. Suitable solvents include
n-heptane and cyclohexane. Solvent-free resins may also be
used.
[0063] A typical process to coat or impregnate the yarns of the
fiber-resin composite with visco-elastic resin comprises the steps
of bringing the fiber-resin composite into contact with the resin.
The resin can be in the form of a solution, emulsion, melt or film.
When the resin is a solution, emulsion or melt, the fiber-resin
composite can be immersed in the resin and surplus resin removed
off with a doctor blade or coating roll. The resin may also be
deposited onto the surface of the fiber-resin composite as it
passes beneath a resin bath in a blade over roll coating process.
The next step is to consolidate the resin impregnated fiber-resin
composite by drying to remove the solvent or cooling to solidify
the melt followed by a calendering step. The coated or impregnated
fiber-resin composite is then rewound and cut for use in accordance
with the present invention. When the visco-elastic resin is in the
form of a film, the resin film is placed onto one or both surfaces
of the fiber-resin composite and consolidated onto or into the
fiber-resin composite by heat and pressure in a calender. The
degree of resin impregnation into the fibers is controlled by the
calendering conditions. The specific values for heat and pressure
need to be determined for each material combination. Typically, the
temperature is in the range of from 80 to 300 degrees C.,
preferably from 100 to 200 degrees C. and the pressure in the range
of from 1 to 100 bar, preferably from 5 to 80 bar. The heat and
pressure from this process also causes the binding layer resin to
melt and flow to form the resin rich interface region between the
respective layers of the fiber-resin composite. All the processes
described here are well known to those skilled in the art and are
further detailed in chapter 2.9 of "Manufacturing Processes for
Advanced Fiber-resin composites" by F.C. Campbell, Elsevier,
2004.
Transverse Binding Yarns
[0064] In some embodiments, binding threads or yarns may be
present. These binding yarns, shown at 15 in FIG. 1, are stitched
or knitted transversely through the nonwoven layers of the
fiber-resin composite in a direction orthogonal to the plane of the
layers. This is also known as z-directional stitching. Any suitable
binding yarn may be used with polyester fiber, polyethylene fiber,
polyamide fiber, aramid fiber, polyareneazole fiber, polypyridazole
fiber, polybenzazole fiber, and mixtures thereof being particularly
suited. The spacing between rows of stitches may vary depending on
design requirements. The stitches may be between yarns or through
yarns. In one embodiment the rows are spaced 5 mm apart. The
transverse yarns provide further mechanical support to the
fiber-resin composite.
Uses of the Fiber-Resin Composite
[0065] A ballistic resistant soft armor article can be produced by
combining a plurality of fiber-resin composites as described in the
above embodiments. Examples of soft armor include protective
apparel such as vests or jackets that protect body parts from
projectiles. It is preferable that the fiber-resin composites are
positioned in the article in such a way as to maintain the offset
yarn alignment throughout the finished assembly. For example, in an
article comprising two fiber-resin composites, the second
fiber-resin composite of the article is placed on top of the first
fiber-resin composite in such a way that the orientation of the
yarns comprising the bottom layer of the second fiber-resin
composite is offset with respect to the orientation of the yarns
comprising the adjacent top layer of the first fiber-resin
composite.
[0066] The actual number of fiber-resin composites used will vary
according to the design needs of each article being made. An armor
article may comprise only the fiber-resin composites of this
invention or the fiber-resin composites may be combined with other
fabric structures. In FIGS. 4A to 4D, a plurality of fiber-resin
composites of this invention is indicated by 42 and a plurality of
fabric structures different from this invention (other fabric
structures) is indicated by 43. Examples of other fabric structures
are woven fabrics, multiaxial fabrics or nonwoven fabrics
comprising no resin or binder components. FIG. 4A shows a plurality
of fiber-resin composites 42 facing the projectile (strike
direction) 41 and a plurality of other fabric structures 43 facing
the body or non-strike direction.
[0067] Another embodiment covers, as in FIG. 4B, an arrangement of
alternating assemblies of pluralities of fiber-resin composites 42
and other fabric structures 43. A plurality of fiber-resin
composites is facing the strike direction 41.
[0068] A further embodiment is one of a plurality of fiber-resin
composites 42 located on either side of a core of other structures
43. One of the plurality of fiber-resin composites is facing the
strike direction 41. This is depicted in FIG. 4C.
[0069] In yet another embodiment, a plurality of other fabric
structures is located on either side of a core of a plurality of
fiber-resin composites. One of the plurality of other fabric
structures is facing the strike direction 41. This is shown in FIG.
4D.
[0070] Combinations of materials other than those described in the
drawings 4A to 4D are also useful.
[0071] An assembly comprising a fiber-resin composite and other
fabric structures for an antiballistic vest pack typically has a
total areal density of between 3.5 to 7.0 kg/m.sup.2. Thus the
number of fiber-resin composites will be selected to meet this
weight target with the number typically being from 5 to 25. Other
components such as foam or a felt may also be incorporated into the
armor article.
Test Methods
[0072] The following test methods were used in the following
Examples.
[0073] Linear Density The linear density of a yarn or fiber was
determined by weighing a known length of the yarn or fiber based on
the procedures described in ASTM D1907-97 and D885-98. Decitex or
"dtex" is defined as the weight, in grams, of 10,000 meters of the
yarn or fiber. Denier (d) is 9/10 times the decitex (dtex).
[0074] Yarn Mechanical Properties: The yarns to be tested were
conditioned and then tensile tested based on the procedures
described in ASTM D885-98. Tenacity (breaking tenacity), modulus of
elasticity and elongation to break were determined by breaking
yarns on an Instron.RTM. universal test machine.
[0075] Areal Density: The areal density of a nonwoven layer was
determined by measuring the weight of a 10 cm.times.10 cm sample of
the layer. The areal density of the final article was the weight of
a 10 cm.times.10 cm sample of the article.
[0076] Ballistic Performance: Ballistic tests of the multi-sheet
panels were conducted in accordance with standard procedures such
as those described in procurement document FQ/PD 07-05B (Body
Armor, Multiple Threat/Interceptor Improved Outer Tactical Vest)
and MIL STD-662F (V50 Ballistic Test for Armor). Four targets were
tested for most examples and between six to nine shots, at zero
degree obliquity, fired at each dry target. The reported V50 values
are average values for the number of shots fired for each example.
Ballistic resistance values are reported as V50 which is a
statistical measure that identifies the average velocity at which a
bullet or a fragment penetrates the armor equipment in 50% of the
shots, versus non penetration of the other 50%. The parameter
measured is V50 at zero degrees where the degree angle refers to
the obliquity of the projectile to the target. The reported values
are average values for the number of shots fired for each example.
Projectiles used were 16 grain, 17 grain and 64 grain.
[0077] Layer Thickness and Equivalent Filament Diameter can be
determined by standard electron microscopy techniques.
EXAMPLES
[0078] The following examples are given to illustrate the invention
and should not be interpreted as limiting it in any way. In all the
Examples and Comparative Examples the nonwoven fiber-resin
composite comprised first and second layers of para-aramid yarns
aligned unidirectionally in an orthogonal configuration relative to
each other and at +45.degree./-45.degree. relative to the machine
direction. The first yarn layer comprised a first plurality of
yarns and the second yarn layer comprised a second plurality of
yarns. A thermoplastic binding layer coated at least portions of
the internal surfaces of the first plurality and the second
plurality of yarns and filled some space between the filaments in
the first plurality and the second plurality of yarns in the center
region of the fiber-resin composite. Polyester 140 denier threads
were used for z-direction stitching through the plane of the first
and second layers. The nonwoven fiber-resin composite further
comprised a viscoelastic resin coating at least portions of
external surfaces of the first plurality and the second plurality
of yarns and filling some space between the filaments in the first
plurality and the second plurality of yarns. The viscoelastic resin
coated the first and second layers in regions remote from the
interface of the two layers of the fiber-resin composite. The
nonwoven fiber-resin composite had a nominal weight of 300
g/m.sup.2.
Comparative Example A
[0079] Ten 380.times.380 mm sheets of nonwoven fiber-resin
composite were held together by stitches located at the four
corners of the sheets (corner stitch. The yarn used in the nonwoven
fabric construction was 440 dtex Kevlar.RTM. 129, available from
E.I. du Pont de Nemours and Company, Wilmington, Del. The yarn had
a nominal tenacity of 24.5 g/dtex, a modulus of 565 grams/dtex and
an elongation at break of 3.85 percent. The binding layer material
was a 0.025 mm thick layer of polyurethane that coated the entire
surface of yarns in the region of the interface between the two
nonwoven layers. The viscoelastic coating resin was polyisobutene.
The corner stitching thread was Tex 70 spun Kevlar.RTM. available
from Saunders Thread Company, Gastonia, N.C. No other fabric
structures were built into the article. The total weight of
fiber-resin composite was 5.0 kg/m.sup.2. Ballistic testing was
conducted using 16, 17 and 64 grain projectiles. Results of the
ballistic tests over two rounds of shots are summarized in Table 1.
The test results from flexural evaluation of the fabric are in
Table 2.
Comparative Example B
[0080] Seventeen 380.times.380 mm sheets of nonwoven fiber-resin
composite made of Kevlar.RTM. were held together by stitches
located at the four corners of the sheets (corner stitch). The yarn
used in the nonwoven fabric construction was 440 dtex Kevlar.RTM.
129, available from E.I. du Pont de Nemours and Company,
Wilmington, Del. The yarn had a nominal tenacity of 24.5 g/dtex, a
modulus of 565 grams/dtex and an elongation at break of 3.85
percent. The binding layer material was a 0.0125 mm thick layer of
polyurethane that coated the entire surface of yarns in the region
of the interface between the two nonwoven layers. The viscoelastic
coating resin was polyisobutene. The corner stitching thread was
Tex 70 spun Kevlar.RTM. available from Saunders Thread Company,
Gastonia, N.C. No other fabric structures were built into the
article. The total weight of fiber-resin composite was 5.1
kg/m.sup.2. Ballistic testing was conducted using 16, 17 and 64
grain projectiles against targets supported on a Roma Plastina
number 1 clay backing medium. Results of the ballistic tests over
two rounds of shots are summarized in Table 1. The test results
from flexural evaluation of the fabric are in Table 2.
Example 1
[0081] Twenty one 380.times.380 mm sheets of nonwoven were held
together by stitches located at the four corners of the sheets
(corner stitch). The yarn used in the nonwoven fabric construction
was 666 dtex (600 denier) KM2 Kevlar.RTM., available from E.I. du
Pont de Nemours and Company, Wilmington, Del. The yarn had a
nominal tenacity of 25.5 g/dtex, a modulus of 622 grams/dtex and an
elongation at break of 3.9 percent. The binding layer material was
a 0.0125 mm thick perforated film layer of a blend of elastomeric
block copolymers and polyethylene copolymers available from Scott
Materials Group Inc., Sioux Falls, S. Dak. that partially coated
the surface of yarns in the region of the interface between the two
nonwoven layers. The binding layer had resin free areas in the
region the interface between the two nonwoven layers of about 50
percent. The viscoelastic coating resin was
styrene-isoprene-styrene block copolymer. The corner stitching
thread was Tex 70 spun Kevlar.RTM. available from Saunders Thread
Company, Gastonia, N.C. No other fabric structures were built into
the article. The total weight of fiber-resin composite was 4.9
kg/m.sup.2. Ballistic testing was conducted using 16, 17 and 64
grain projectiles. Results of the ballistic tests over two rounds
of shots are summarized in Table 1. The test results from flexural
evaluation of the fabric are in Table 2.
TABLE-US-00001 TABLE 1 Areal Density Bullet V50 Bullet V50 Bullet
V50 Reference (kg/m2) Type (m/s) Type (m/s) Type (m/s) Comparative
5.1 16 grain 583 17 grain 522 64 grain 408 Example A Comparative
5.0 16 grain 609 17 grain 569 64 grain 461 Example B 5.2 16 grain
620 17 grain 573 64 grain 501 Example 1 4.9 16 grain 627 17 grain
590 64 grain 512 5.2 16 grain 666 17 grain 604 64 grain 544
[0082] Comparison of the above results shows that examples
comprising a binding layer having discrete areas of yarn surfaces
that are free from binder resin coating in the region of the
interface between the nonwoven layers had a significantly better
V50 performance when compared with examples of similar areal weight
comprising a binding layer in the region of the interface between
the two nonwoven layers that was continuous in nature so as to have
no discrete areas of yarn surfaces that were free from binder resin
coating. The flexural testing of the fabrics also demonstrates that
fabrics of the invention have improved flexibility, and hence
enhanced wearer comfort, when compared with the comparative
examples.
* * * * *