Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF INVENTION
LIGHT WEIGHT TRAUMA REDUCING BODY ARMOR
1. Field of the Invention
This invention relates to trauma reducing laminates particularly suitable
in ballistic resistant soft body armor and a method of their manufacture.
2. Background of the Invention
The primary objective of body armor research is to develop a low cost,
light-weight, comfortable to wear system with ballistic-impact resistance.
Body
armor standards in India require that a projectile should be stopped under
ballistic impact and that the penetration depth into a clay witness backing
the
armor during the testing should not exceed 25mm. If penetration depth
exceeds this value, a wearer can incur serious blunt trauma. Aramid and ultra-
high molecular weight polyethylene (UHMWPE) have been used as base
materials for ballistic protection. These high performance fibers are
characterized by low density, high strength, and high energy absorption.
However, to meet the protection requirements for typical ballistic threats,
approximately 20-50 layers of fabric are required depending upon the type of
fabric used. The resulting armor becomes heavy and may not meet the low
trauma requirement, e.g. 25mm or below.
In tests such as NIJ 0101.06 of July 2007: "Ballistic Resistance of
Personal Body Armor", the depth of the backface signature on a clay box
upon impact of a projectile is used as a means to quantify the severity of the
blow, or trauma, to which a hypothetical wearer would be subjected to.
There are several literature reports citing ways to manufacture ballistic
armors that diminish the blow suffered by a person upon projectile impact.
GB2232063 by Lee describes a trauma reducing protective shield
comprising two parallel layers of textile material, sandwiching a plurality of
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polypropylene (PP) fibers extending perpendicular to the plane of the two
parallel layers. Upon impact, the perpendicular fibers, this can be optionally
impregnated with resin, become crushed and absorb and dissipate the kinetic
energy of the projectile, which in turn lessens the intensity of trauma.
W02006136323 by Boettger et al. discloses a trauma reducing pack
comprising at least one panel of plastic material and at least one textile
fabric
layer affixed to the panel and consisting of yarns with fibers having a
tensile
strength of at least 900 MPa as measured according to ASTM D7269,
wherein the plastic material is a self-reinforced thermoplastic material, such
as for example PP tapes, these being in close contact to one another and
bonded to one another at elevated temperature. These structures are able to
provide a minor reduction in backface signature and additionally suffer from
flammability issues.
W02007021611 by Morin et al. discloses structures comprising high-
modulus polyolefin fibers, in particular PP tape fibers, sandwiched between
aramid fibers using an adhesive that are suitable in marine, automotive and
electronic applications. However, these structures are stiff and hard, which
can result in discomfort to the wearer.
US20120240756 by Bader et al discloses trauma reducing laminates,
comprising multiple layers of textile fabric of aramid or polyolefin bonded
together by means of a polyolefinic adhesive.
The structures reported in the art do not address their applicability in
meeting the environmental testing protocol as specified in NIJ 0101.06. Also
the structures reported do not address the specific need for low back face
signature (less than 25 mm) as desired in the Indian context. Also the
structures reported in the art do not meet the cost and low weight
requirements.
Thus, there is a strong felt need for a lighter, better performing trauma
pack that provides higher protection from blunt trauma and that increases
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survival rates when compared to the trauma packs known in the art, and are
comfortable to wear.
SUMMARY OF THE INVENTION
An aspect of the present invention is a trauma reducing pack,
comprising
(i) at least one first layer of aramid fabric comprising yarns having a
tensile strength of at least 900 MPa and having a linear density of 444 ¨ 1111
dtex, the fabric having an inner and outer surface.
(ii) at least one second layer of a thermoplastic sheet having a
tensile strength of at least 60 MPa or a thermoplastic nonwoven fabric
comprising yarns having a tensile strength of at least 900 MPa, the sheet or
nonwoven fabric having an inner and outer surface, and
(ii) a polyolefinic adhesive having a melting point of from 70-150 C,
wherein the at least one first layer and the at least one second layer
are bonded together by means of the polyolefinic adhesive.
Another aspect of the present invention is a body armor comprising the
trauma pack.
BRIEF DESCRIPTION OF DRAWINGS
This invention is illustrated in the accompanying drawings, throughout
which, like reference numerals indicate corresponding parts in the various
figures.
Fig. 1 is a sectional view of a para-aramid ¨ polycarbonate (PC)
laminate.
Fig. 2 is a sectional view of another para-aramid - PC laminate.
Fig. 3 is a sectional view of a para-aramid - para-aramid laminate.
Fig. 4 is a sectional view of a para-aramid - polyolefin laminate.
Fig. 5 is a sectional view of another para-aramid - polyolefin laminate
.Fig. 6 is a sectional view of another para-aramid - para-aramid
laminate.
1
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DETAILED DESCRIPTION
The multilayer laminated structures for a trauma pack suitable for
resisting a ballistic object contain a plurality of layers comprising at least
one
aramid fabric layer bonded together with another fabric or sheet layer with
the
help of an adhesive.
In some embodiments, the aramid fabric layer used in the ballistic
resistant multilayer laminated structures according to the present invention
is
made of continuous filament yarns which are made of fibers. For purposes
herein, the term "fiber" 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 fiber cross section can be any
shape, but is typically round. Herein, the term "filament" is used
interchangeably with the term "fiber".
By "aramid", it is meant 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 Fibers - Science and Technology,
Volume 2, Section titled Fiber-Forming Aromatic Polyamides, page 297, W.
Black et al., Interscience Publishers, 1968. Aramid fibers and their
production
are, also, disclosed in U.S. Patents 4,172,938; 3,869,429; 3,819,587;
3,673,143; 3,354,127; and 3,094,511. The preferred aramid is a para-aramid.
The preferred para-aramid is poly (p-phenylene terephthalamide) which is
called PPD-T.
The fabric may be woven, unidirectional, multidirectional, including
bidirectional, or nonwoven.
By "unidirectional (UD) fabric" is meant a fabric layer (ply) in which the
component yarns or fibers are aligned in a parallel direction within the plane
of
the fabric.
By "multidirectional fabric" is meant a fabric comprising a plurality of
unidirectional fabric layers in which the orientation of the yarns or fibers
in one
UD fabric layer is offset with respect to the orientation of yarns or fibers
in the
next layer. In one embodiment, the "multidirectional aramid" fabric of the
invention comprises two layers of unidirectional fabric of para-aramid yarns
with the yarns aligned in a +45/-45 orientation with respect to the machine
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direction of the fabric. The multidirectional fabric further comprises a
polyester
yarn binding thread stitched through the UD fabric layers in a direction
orthogonal to the plane of the UD fabric layers. The machine direction is the
long direction within the plane of the fabric, i.e. the direction in which the
fabric
is being produced by the machine. A multidirectional fabric comprising two
layers of unidirectional fabric is also known as a bidirectional fabric.
The term "nonwoven" means here a web including a multitude of
randomly oriented fibers. By "randomly oriented" is meant that the fibers have
no long range repeating structure discernable to the naked eye. The fibers
can be bonded to each other, or can be unbonded and entangled to impart
strength and integrity to the web. The fibers can be staple fibers or
continuous fibers, and can comprise a single material or a multitude of
materials, either as a combination of different fibers or as a combination of
similar fibers each comprised of different materials.
Nonwoven fabrics or webs have been formed from many processes
such as for example, melt blowing processes, spun bonding processes, and
bonded carded web processes. The basis weight of nonwoven fabrics is
usually expressed in ounces of material per square yard (osy) or grams per
square meter (gsm) and the fiber diameters useful are usually expressed in
microns.
As used herein the term " spun bond fibers" refers to small diameter
fibers which are formed by extruding molten thermoplastic material as
filaments from a plurality of fine, usually circular capillaries of a
spinneret with
the diameter of the extruded filaments then being rapidly reduced as by, for
example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No.
3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S.
Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. Nos. 3,502,763, and
U.S. Pat. No. 3,542,615 to Dobo et al. Spunbond fibers are generally
continuous and larger than 7 microns, more particularly, they are usually
between about 15 and 50 microns.
By tape is meant a highly oriented non filamentary polyolefin sheet.
Preferably the tape comprises two cross plied sheets arranged orthogonally to
each other and bonded by an adhesive film or scrim, such an arrangement
sometimes being referred to as bidirectional tape,.
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As used in this application, the term "high modulus" refers to materials
having a modulus greater than 1,000 grams per denier (gpd).
The multilayer structure used in the method according to the present
invention is a pre-assembled structure of at least one aramid layer and at
least one other layer comprising either a thermoplastic sheet or a nonwoven
fabric. The layers are laminated together using an adhesive and a
thermopressing process. Preferably, the thermoplastic sheet has a tensile
strength of at least 60 MPa when measured according to ASTM
D885/D885M-10a (2014). The thermoplastic sheet can be chosen among
polycarbonate (PC), acrylonitrile butadiene styrene (ABS), ethylene-
methacrylic acid copolymers (sold under the trade name of Surlyn
bidirectional polyolefinic tape and mixtures thereof. Preferably, the
thermoplastic sheet is made of polycarbonate of thickness ranging from 0.2 to
2.0 mm. More preferably, the thermoplastic sheet is made of multidirectional
polyolefinic tape .The thermoplastic nonwoven layer can be chosen among a
wide variety of nonwoven materials chosen among polyethylene, polyesters,
polypropylene etc. Preferably, the thermoplastic nonwoven fabric comprises
yarns having a tensile strength of at least 900 MPa when measured according
to ASTM D885/D885M-10a (2014).
A suitable polyolefinic adhesive according to the present invention may
be chosen from polyolefin, such as for example polyethylene's, ethylene
copolymers, polypropylenes, propylene copolymers, and/or combinations
thereof, having a melting point of from 70 C to 150 C. when measured
according to ASTM D1238-13, and having melt flow viscosity of from 0.2 g/10
min to 10 g/10 min when measured according to ASTM1238 at 190 C using a
weight of 2.16 kg.
The polyolefinic adhesive may be grafted. Suitable grafting agents may
be chosen among ethylenically unsaturated organic acids and their esters,
half-esters and anhydrides such as for example maleic anhydride, alkyl
hydrogen maleate, maleic acid, fumaric acid, alkyl hydrogen fumarate, and/or
combinations thereof.
In the case where the polyolefins are grafted, the grafting agent is
present of from 0.1 weight percent to 3.5 weight percent, based on the total
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weight of the polyolefin. Suitable polyethylenes may be chosen among very
low density polyethylenes (VLDPE), linear low density polyethylenes (LLDPE),
low density polyethylenes (LDPE), metallocene polyethylenes (mPE), high
density polyethylenes (HDPE), ultra-high molecular weight polyethylenes
(UHMWPE) and/or combinations thereof. Preferably, the polyethylene is a
linear low density polyethylene (LLDPE).
Suitable ethylene copolymers may be chosen among ethylene vinyl
acetate, ethylene (meth) acrylate copolymers, ethylene (meth) acrylic acid
copolymers and their corresponding ionomers, ethylene vinyl alcohol, and/or
combinations thereof. The polyolefinic adhesive may be suitably applied to the
assembly of polyolefinic textile fabric in various ways, such as for example
by
placing the adhesive in between the layers of polyolefinic fabric and/or on
both sides of the assembly.
Suitable adhesives according to the present invention may be chosen
from are ethylenic copolymers of polyolefins or grafted polyolefins having
functional groups such as vinyl acetate (VA) or methacrylic acid (MAA). The
acid groups are neutralized fully or partially with neutralizing agents such
as
sodium, potassium, zinc, magnesium, lithium and combinations thereof.
Suitable adhesives for use in the present invention are commercially available
under the trademark Surlyn from E. I. du Pont de Nemours and Company,
Wilmington, Delaware, USA.
A trauma pack is made of at least one aramid fabric layer and at least
one thermoplastic sheet or a thermoplastic nonwoven fabric layer, said layers
being bonded to each other using a polyolefinic adhesive. The different layers
of the trauma pack are simultaneously heated in a press during a time and at
a pressure and temperature sufficient to ensure that the adhesive softens,
flows and coats the fibers of the fabric layers without substantially altering
the
chemical and physical properties of the individual layers.
Typically, the trauma pack is pressed at a pressure between 2 and 100
bars and more preferably between 10 and 70 bars. The temperature is
typically at least about 30 C beyond the melting point of the thermoplastic
sheet or nonwoven fabric to enable proper flow of the adhesive. The
thermopressing time is preferably between 10 and 60 minutes and depends
on the number of different layers of the pile. The impregnated composite
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structure is cooled, typically to 50 C, while keeping constant the pressure
and
then is cooled to room temperature under ambient conditions.
An aspect of the present invention is a trauma reducing pack,
comprising
a. At least one first layer of aramid fabric comprising yarns having a
tensile strength of at least 900 MPa and having a linear density of 444-1111
dtex (400-1000 denier )having an inner and outer surface.
b. At least one second layer of a thermoplastic sheet having a tensile
strength of at least 60 MPa or a thermoplastic nonwoven fabric comprising
yarns having a tensile strength of at least 900 MPa, the sheet or nonwoven
fabric having an inner and outer surface, and
c. a polyolefinic adhesive having a melting point of from 70-150 C.,
wherein at least one first layer and at least one second layer are bonded
together by means of the polyolefinic adhesive.
In one embodiment of the present invention, the polyolefinic adhesive
in the trauma reducing pack is an ethylene copolymer.
In another embodiment of the present invention, the polyolefinic
adhesive in the trauma reducing pack is a grafted polyolefin.
In still another embodiment of the present invention, the fibers in the
aramid fabric are woven, nonwoven, unidirectional or multidirectional.
In yet another embodiment of the present invention, the thermoplastic
sheet is selected from polycarbonates, acrylonitrile butadiene styrene,
ethyl ene-methacrylic acid copolymers, bidirectional polyolefinic tape or
combinations thereof
In another embodiment of the present invention, the thermoplastic
nonwoven fabric is a spunbond nonwoven of polyolefin.
In another embodiment of the present invention, the polyolefin is a
polyethylene, polypropylene, polybutene, or a blend or copolymer thereof.
In another embodiment of the present invention, the multidirectional
polyolefinic tape is a cross-plied non-fibrous ultra-high molecular weight
polyethylene (UHMWPE) tape.
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In still another embodiment of the present invention, the trauma pack
has an areal density of less than 1000 g/m2.
In yet another embodiment of the present invention, the trauma pack
comprises from 1 to 4 layers of para-aramid fabric, from 1 to 5 layers of
thermoplastic sheet, from 1 to 3 layers of nonwoven fabric and from 1 to 4
layers of polyolefinic adhesive.
Another aspect of the present invention is a body armor comprising at
least one trauma pack.
DETAILED DESCRIPTION OF FIGURES
Figure 1 is a sectional view of a para-aramid - polycarbonate laminate
comprising:
1. Para-aramid fabric
2. Polyolefinic adhesive
3. Polycarbonate sheet
Figure 2 is a sectional view of another para-aramid - polycarbonate
laminate comprising:
1A. First layer of para-aramid fabric
2A. First layer of polyolefinic adhesive film
3. Polycarbonate sheet
2B. Second layer of polyolefinic adhesive film
1B. Second layer of para-aramid fabric
Figure 3 is a sectional view of a para-aramid - para-aramid laminate
comprising:
1A. First layer of 1000 denier para-aramid fabric
2A. First layer of polyolefinic adhesive film
3A. First layer of 600 denier para-aramid fabric
2B. Second layer of polyolefinic adhesive film
3B. Second layer of 600 denier para-aramid fabric
2C. Third layer of polyolefinic adhesive film
1B. Second layer of 1000 denier para-aramid fabric
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Figure 4 is a sectional view of another para-aramid - para-aramid
laminate comprising:
1. Para-aramid fabric
2. Polyolefinic adhesive
3. A plurality of polyolefin sheet layers
Figure 5 is a sectional view of another para-aramid - polyolefin
laminate:
1A. First layer of 1000 denier para-aramid fabric
2A. First layer of polyolefinic adhesive film
3A. First layer of spun bonded polyethylene nonwoven fabrics
2B. Second layer of polyolefinic adhesive film
3B. Second layer of spun bonded polyethylene nonwoven
fabrics
20. Third layer of polyolefinic adhesive film
30. Third layer of spun bonded polyethylene nonwoven
fabrics
2D. Fourth layer of polyolefinic adhesive film
1B. Second layer of 1000 denier para-aramid fabric
Figure 6 is a sectional view of a para-aramid - polyolefin laminate
comprising:
1A. First layer of 3300 denier para-aramid fabric
2. A layer of polyolefinic adhesive film
1B. Second layer of 3300 denier para-aramid fabric
TEST METHODS
Temperature: All temperatures were measured in degrees Celsius
( C).
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/D1907M-12 and D885/D885M-10a (2014).
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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).
Tensile Properties: The fibers to be tested were conditioned and then
tensile tested based on the procedures described in ASTM D885/D885M-10a
(2014). Tenacity (breaking tenacity), modulus of elasticity, force to break
and
elongation to break are determined by breaking test fibers on an Instron
universal test machine.
Areal Density: The areal density of the fabric layer was determined by
measuring the weight of one square meter of fabric i.e., lm x lm. The areal
density of a composite structure was determined by the sum of the areal
densities of the individual layers.
Melt flow index was measured as per ASTM D 1238-13.
The environmental conditioning protocol consisted of exposing body
armor to environmental conditioning inside a chamber wherein the
temperature and relative humidity are maintained at 65 2 C and 80 5%
respectively for 10 days. Conditioned soft body armor was tested in a
ballistic
test for backface signature. The value of backface signature of soft body
armor should be less than 25mm before and after conditioning.
Trauma Test Method (Back Face Deformation or BFD)
The body armor containing a ballistic pack and trauma pack was
fastened to a clay box of Roma No 1 clay, with the ballistic pack facing away
from the clay and then subjected to a ballistic impact by a 9 x 19 mm bullet
(OFB, India) traveling at a speed of 400 15 m/s, shot from a distance of 5
meters. Back face deformation is also known as Back Face Signature.
After the bullet hit the pack, the depth of crater created on the clay was
measured and recorded as the back face signature (or trauma); For each test
sample, the test was average of 3 panels with 4 shots each.
DESCRIPTION OF LAYERS
Fabric layers and adhesive films of the following description were used
for preparing the multilayer laminated composite trauma pack;
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KL-1 was a textile fabric having a plain weave and having areal density
of 190 g/m2, consisting of poly (p-phenylene terephthalamide) yarns having a
linear density of 1000 denier and 8.5 x 8.5 ends per centimeter available from
E. I. du Pont de Nemours and Company, Wilmington, Delaware, USA
(hereinafter DuPont) under the trade name of Kevlar0 para-aramid and was
cut into 400 x 400 mm sheets.
KL-2 was a multidirectional textile fabric having areal density of 300
g/m2, consisting of poly (p-phenylene terephthalamide) having a linear density
of 400 denier available from DuPont under the trade name of Kevlar0
XPS300 and was cut into 400 x 400 mm sheet.
KL-3 was a multidirectional textile fabric having areal density of 510
g/m2, consisting of poly(p-phenylene terephthalamide) having a linear density
of 1000 denier available from DuPont under the trade name of Kevlar0
XPS102 and was cut into 400 x 400 mm sheet.
KL-4 was a textile fabric having a plain weave and having areal density
of 165 g/m2, consisting of poly (p-phenylene terephthalamide) yarns having a
linear density of 600 denier and 8.5 x 8.5 ends per centimeter available from
DuPont under the trade name of Kevlar0 para-aramid and was cut into 400 x
400 mm sheet.
KL-5 was a textile fabric having a plain weave and having areal density
of 440 g/m2, consisting of poly (p-phenylene terephthalamide) yarns having a
linear density of 3300 denier and 6.5 x 6.5 ends per centimeter available from
E. I. du Pont de Nemours and Company, Wilmington, Delaware, USA
(hereinafter DuPont) under the trade name of Kevlar0 para-aramid and was
cut into 400 x 400 mm sheets.
IC 600D was a commercially available Kevlar 0 composite fabric having an
areal density of 900 g/m2 available from DuPont.
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PE-1 was a bidirectional tape made of ultra-high molecular weight
polyethylene having areal density of 111 g/m2 available from DuPont
Company under the trade name of Tensylon TM HSBD 30A.
PE-2 was a spun bonded polyethylene nonwoven fabrics having areal
density of 73 g/m2 available from DuPont under the trade name of Tyvek0.
PE-3 was a spun bonded polyethylene nonwoven fabric having areal
density of 105 g/m2 available from DuPont under the trade name of Tyvek0 .
PC-1 was a Polycarbonate sheet of 0.8mm thicknesses having aerial
density of 1000g/m2 available from SABIC Innovative Plastics under the trade
name of Lexan0.
PC-2: was a Polycarbonate sheet of 0.3mm thicknesses having aerial
density of 475 g/m2 available from SABIC Innovative Plastics under the trade
name of Lexan0.
Adhesive Film 1 was a maleic anhydride modified linear low density
polyethylene having maleic anhydride content in the range of 0.05 to 1.5%;
having melting points in the range of 85 to 120 C; melt flow index in the
range
of 2 to 9 g/10min and having aerial density of 50 g/m2 available from DuPont
under the trade name of Byne10.
Adhesive Film 2 was an ethylene copolymer having functional groups
such as vinyl acetate; having melting points in the range of 115 to 130 C;
melt
flow index in the range of 3 to 8 g/10min and having aerial density of 50 g/m2
available from Nolax0 AG under the trade name of Nolax 0.
Adhesive Film 3 was a ethylene copolymer having functional groups
such as methacrylic acid with partial neutralization with zinc or sodium metal
ions; having melting points in the range of 80 to 100 C; melt flow index in
the
range of 3 to 8 g/10min and having aerial density of 50 g/m2 available from
DuPont under the trade name of Surlyn0.
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EXAMPLES
Examples prepared according to the process or processes of the
current invention are indicated by numerical values. Control or Comparative
Examples are indicated by letters. With the exception of Control A, all
Examples and Comparative Examples were tested in a final assembly
comprising a ballistic pack and a trauma pack. The assembly configurations
are described in the following text and tables. Data and test results relating
to
the Comparative and Inventive Examples are shown in Tables 1- 3.
EXAMPLE A
A commercially available Kevlar 0 composite fabric having an areal
density of 900 g/m2 available from E. I. du Pont de Nemours and Company
under the trade name of IC 600D was used as the trauma pack. The ballistic
pack comprised 11 layers of KL2.
CONTROL A
A stack of 15 layers of multidirectional woven fabric KL2 made of 400
denier Kevlar0 yarn and having areal density of 300 g/m2 was used as the
ballistic pack without any trauma pack.
EXAMPLE B
A trauma pack was formed by stacking one layer of textile fabric KL1, a
layer of PC1 and another layer of KL1 (KL1-PC1-KL1). The stack was used
without any consolidation and this stack has areal density of 1380 g/m2. The
ballistic pack comprised 9 layers of KL2.
EXAMPLE C
A trauma pack was formed by superimposing in order in a stack, a first
layer of textile fabric KL1, a first layer of adhesive Film 1, a first layer
of textile
fabric KL4, a second layer of adhesive Film 1, second layer of textile fabric
KL4, a third layer of adhesive Film 1 and a second layer of textile fabric of
KL1
(KL1-Film1-KL4-Film1-KL4-Film1-KL1). The stack was consolidated in an
industrial hydraulic press having heating and cooling capability as described
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in example 1, except that the preheating temperature was 115 C. The stack
was heated to 125 Cfor 10 minutes and 60 ton which was then cooled to room
temperature to yield a laminate/trauma reducing pack having an aerial density
of 860 g/m2. The ballistic pack comprised 11 layers of KL2.
EXAMPLE D
A trauma pack was formed by superimposing in order in a stack, a first
layer of textile fabric KL5, a first layer of adhesive Film 1 and a second
layer
of textile fabric KL5,. The stack was consolidated in an industrial hydraulic
press having heating and cooling capability as described in example 1, except
that the preheating temperature was 115 C. The stack was heated to 125 C
for 10 minutes and 60 ton which was then cooled to room temperature to yield
a laminate/trauma reducing pack having an aerial density of 930 g/m2. The
ballistic pack comprised 11 layers of KL2.
EXAMPLE 1
A trauma pack was formed by superimposing in order in a stack, a
first textile fabric of KL1, a layer of adhesive Film 2 and a layer of
polycarbonate sheet PC1 (KL1-Film2-PC1). The stack was consolidated in an
industrial hydraulic press (mold preheated to 125 C ) having heating and
cooling capability for 10 minutes at 140 C and 60 ton and then cooled to room
temperature to yield a laminate/trauma reducing pack having an aerial density
of 1240 g/m2. The ballistic pack comprised 10 layers of KL2.
EXAMPLE 2
A trauma pack was formed as described in example 1, except that
lamination with KL1 and Film2 was done on both sides of PC sheet. The
construction of the laminate was KL1- Film2-PC1-Film2-KL1 and the aerial
density of resultant pack was 1480 g/m2. The ballistic pack comprised 9 layers
of KL2.
1
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EXAMPLE 3
A trauma pack was formed as described in example 1, except that P02
was used in place of PC1. The construction of the laminate was KL1- Film2-
P02 and the aerial density of resultant pack was 715 g/m2. The ballistic pack
comprised 11 layers of KL2.
EXAMPLE 4
A trauma pack was formed as described in example 2, except that P02
was used in place of PC1. The construction of the laminate was KL1- Film2-
P02-Film2-KL1 and the aerial density of resultant pack was 955 g/m2. The
ballistic pack comprised 8 layers of KL2.
EXAMPLE 5
A trauma pack was formed by superimposing, in a stack, a first layer of
textile fabric KL1, a first layer of adhesive Film 1, a first layer of
spunbonded
polyethylene PE2, a second layer of adhesive Film 1, second layer of
spunbonded polyethylene PE2, a third layer of adhesive Film 1 and a second
layer of textile fabric of KL1 (KL1-Film1-PE2-Film1-PE2-Film1-PE2-Film1-
KL1). The stack was consolidated in an industrial hydraulic press as
described in example 1, except that the preheating temperature and molding
temperatures were 115 C and 125 C respectively to yield a laminate/trauma
reducing pack having an aerial density of 800 g/m2. The ballistic pack
comprised 11 layers of KL2.
EXAMPLE 6
A trauma pack was formed as described in example 5, except that
Film 2 was used instead of film 1 (KL1-Film2-PE2-Film2-PE2-Film2-PE2-
Film2-KL1) to yield a laminate/trauma reducing pack having an aerial density
of 800 g/m2. The ballistic pack comprised 11 layers of KL2.
EXAMPLE 7
A trauma pack was formed as described in example 5, except that
Film 3 was used instead of film 1 (KL1-Film3-PE2-Film3-PE2-Film3-PE2-
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Film3-KL1) to yield a laminate/trauma reducing pack having an aerial density
of 800 g/m2. The ballistic pack comprised 11 layers of KL2.
EXAMPLE 8
A trauma pack was formed as described in example 5, except that
PE3 was used instead of PE2 (KL1-Film1-PE3-Film1-PE3-Film1-PE3-Film1-
KL1) to yield a laminate/trauma reducing pack having an aerial density of 895
g/m2. The ballistic pack comprised 11 layers of KL2.
EXAMPLE 9
A trauma pack was formed by superimposing, in order in a stack, a
first layer of textile fabric KL2, a layer of adhesive Film 1, and five layers
of
bidirectional UHMWPE tape PE1 (KL2-Film1-PE1-PE1-PE1-PE1-PE1). The
stack was consolidated in an industrial hydraulic press as described in
example 1, except that the preheating temperature and molding temperatures
were 115 C and 125 C respectively to yield a laminate/trauma reducing pack
having an areal density of 900 g/m2. The ballistic pack comprised 11 layers of
KL2.
Ballistic Trauma Test
For examples 1, 2, 5-9, only one layer of test samples was placed
behind a ballistic pack consisting of multiple layers of KL2, and two layers
of
non-ballistic foam XLPE based on cross-linked polyethylene having an areal
density of 100 g/m2 and a thickness of 4 millimeters each in order to form a
stack.
For examples 3 and 4, two layers of test samples were placed behind a
ballistic pack consisting of multiple layers of KL2, and two layers of non-
ballistic foam XLPE based on cross-linked polyethylene having an areal
density of 100 g/m2 and a thickness of 4 millimeters each in order to form a
stack.
The inventive test sample consisted of a trauma reducing pack
according to Examples 1-9.
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The comparative test sample consisted of trauma reducing packs
according to Control A and Examples A-C, in order to achieve a comparable
areal density to the inventive sample of Examples 1- 9.
Each stack was fastened to a clay box of Roma No 1 clay, with the
ballistic pack facing away from the clay and then subjected to a ballistic
impact by a 9 x 19 mm bullet (OFB, India) traveling at a speed of 400 15 m/s,
shot from a distance of 5 meters.
After the bullet hit the stack, the depth of crater created on the clay was
measured and recorded as the back face signature (or trauma); the results
are shown in Table 1 to Table 3. For each test sample, the test was average
of 3 panels with 4 shots each.
Table 1
Backface
Aerial
Ballistic Trauma Signature
Pack Pack mean
Density Std Dev
(g/m2) (mm)
L KL2 Control A NA 18.4 2.8
9 L KL2 Example 1380 29.2 4.3
B
10 L KL2 Example 1240 10.6 0.9
1
9 L KL2 Example 1480 13.4 1.3
2
11 L KL2 Example 715 14.1 0.6
3
8 L KL2 Example 955 14.1 1.1
4
Among the aramid-PC laminates using aramid-PC laminates containing
aramid layer on both sides did not help much. But such aramid-PC structures
were better in performance compared to aramid only structures (example B).
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Table 2
Backface
Ballistic Trauma AerialSignature
Pack Pack
Density mean Std Dev
(g/m2) (mm)
11 L KL2 Example A 900 15.5 2.1
11 L KL2 Example C 860 19.9 1.5
11 L KL2 Example D 930 20.2 1.4
11 L KL2 Example 5 800 18.5 2.0
11 L KL2 Example 6 800 17.9 2.3
11 L KL2 Example 7 800 14.9 2.9
11 L KL2 Example 8 895 18.7 1.3
Table 3
A l Backface
eria
Ballistic Trauma Signature
Density Std Dev
Pack Pack mean
(g/m2) (mm)
11 L KL2 Example A 900 15.5 2.1
15 L KL2 Control A NA 18.4 2.8
11L KL2 Example 9 900 12.4 1.1
Among the aramid-polyolefin laminates, a change in adhesive film from
a grafted to a straight chain ethylene copolymer (examples 5- example7)
significantly improved the backface signature, also change of polyethylene
(example7 and example 8) from a lower to higher areal density did not
improve the backface signature.. .
On the other hand, a stack of multiple layers of bidirectional UHMWPE
tape (TensylonTm) joined with KL2 layer with adhesive film showed further
reduced backface signature.. Also separate adhesive layer was not required
between layers for this structure as TensylonTm had adhesive layer on one
side.
Environmental Conditioning Test Results
Each trauma pack was subjected to the temperature of 65 2 C and
relative humidity of 80 5% for 10 days. The environmentally conditioned pack
was then placed behind a ballistic pack of multiple layers of KL2 and before
two layers of non-ballistic foam XLPE based on cross linked polyethylene
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having an area density of 100 g/m2 and a thickness of 4 millimeters for
testing
backface signature according to the following method.
The stack was fastened to a clay box of Roma No 1 clay, with the
ballistic pack facing away from the clay box and then subjected to a ballistic
impact of a 9 x 19 mm bullet (OFB, India) traveling at a speed of 400 15 m/s,
shot from a distance of 5 meters.
After the bullet hit the stack, the depth of the back face signature was
measured and recorded; the results are shown in Table 4. For each pack, the
test was average of 3 panels with 4 shots each.
Soft body armor containing trauma pack as described above showed
backface signature before and after environmental conditioning as shown in
Table 4 below;
Table 4
Backface Signature (mm)
Before After
Trauma Pack Conditioning Conditioning
Std Std
Average Average
Dev Dev
Example A 15.5 2.1 14.2 2.2
Example D 20.2 1.4 21.2 0.8
Example 1 10.6 0.9 16.3 3.4
Example 2 13.4 1.3 14.9 0.7
Example 5 18.5 2.0 16.5 2.2
Example 8 18.7 1.3 21.2 0.4
Example 9 12.4 1.1 13.9 2.0
All trauma packs even after environmental conditioning showed
backface signature less than 25mm.
