U.S. patent application number 15/114273 was filed with the patent office on 2017-01-12 for light weight trauma reducing body armor.
The applicant listed for this patent is E. I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to Atanu ACHARYA, Nivedita SANGAJ, Ravi SRIRAMAN.
Application Number | 20170010072 15/114273 |
Document ID | / |
Family ID | 52450639 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170010072 |
Kind Code |
A1 |
SRIRAMAN; Ravi ; et
al. |
January 12, 2017 |
LIGHT WEIGHT TRAUMA REDUCING BODY ARMOR
Abstract
A multilayer laminated structure particularly useful as soft
body armor has layers of aramid fabric, thermoplastic sheet or
polyolefinic fabric bonded together using a polyolefinic adhesive.
The stack of layers is consolidated under heat and pressure to
provide trauma packs having low weight and low trauma as required
by Indian body armor standards.
Inventors: |
SRIRAMAN; Ravi;
(Periyakulam, IN) ; SANGAJ; Nivedita; (Kolhapur,
IN) ; ACHARYA; Atanu; (Howrah, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E. I. DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Family ID: |
52450639 |
Appl. No.: |
15/114273 |
Filed: |
January 23, 2015 |
PCT Filed: |
January 23, 2015 |
PCT NO: |
PCT/US15/12684 |
371 Date: |
July 26, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F41H 5/0478 20130101;
F41H 5/0485 20130101 |
International
Class: |
F41H 5/04 20060101
F41H005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2014 |
IN |
232/DEL/2014 |
Claims
1. 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.degree.
C., wherein the at least one first layer and the at least one
second layer are bonded together by means of the polyolefinic
adhesive.
2. The trauma reducing pack of claim 1, wherein the polyolefinic
adhesive is an ethylene copolymer or a grafted polyolefin.
3. The trauma reducing pack of claim 1, wherein the fabric is
woven, nonwoven, unidirectional or multidirectional.
4. The trauma reducing pack of claim 1, wherein the thermoplastic
sheet is polycarbonate, acrylonitrile butadiene styrene copolymer,
ethylene-methacrylic acid copolymer, bidirectional polyolefinic
tape or combinations thereof.
5. The trauma pack of claim 1, wherein the thermoplastic nonwoven
fabric is a spunbond nonwoven of polyolefin.
6. The trauma pack of claim 5, wherein the polyolefin is a
polyethylene, polypropylene, polybutene, or a blend or copolymer
thereof.
7. The trauma pack of claim 4, wherein the multidirectional
polyolefinic tape is a cross-plied non-fibrous ultra-high molecular
weight polyethylene (UHMWPE) tape.
8. The trauma pack of claim 1 having an aerial density of less than
1000 g/m.sup.2.
9. The trauma pack of claim 1 comprising: (i) from 1 to 4 layers of
aramid fabric, (ii) from 1 to 5 layers of thermoplastic sheet,
(iii) from 1 to 3 layers of nonwoven fabric, and (iv) from 1 to 4
layers of polyolefinic adhesive.
10. A body armor comprising at least one trauma pack according to
claim 1.
Description
1. FIELD OF THE INVENTION
[0001] 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
[0002] 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 25 mm. 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. 25 mm or below.
[0003] 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.
[0004] There are several literature reports citing ways to
manufacture ballistic armors that diminish the blow suffered by a
person upon projectile impact.
[0005] GB2232063 by Lee describes a trauma reducing protective
shield comprising two parallel layers of textile material,
sandwiching a plurality of 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.
[0006] WO2006136323 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.
[0007] WO2007021611 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.
[0008] 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.
[0009] 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.
[0010] Thus, there is a strong felt need for a lighter, better
performing trauma pack that provides higher protection from blunt
trauma and that increases survival rates when compared to the
trauma packs known in the art, and are comfortable to wear.
SUMMARY OF THE INVENTION
[0011] An aspect of the present invention is a trauma reducing
pack, comprising
[0012] (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.
[0013] (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
[0014] (ii) a polyolefinic adhesive having a melting point of from
70-150.degree. C.,
[0015] wherein the at least one first layer and the at least one
second layer are bonded together by means of the polyolefinic
adhesive.
[0016] Another aspect of the present invention is a body armor
comprising the trauma pack.
BRIEF DESCRIPTION OF DRAWINGS
[0017] This invention is illustrated in the accompanying drawings,
throughout which, like reference numerals indicate corresponding
parts in the various figures.
[0018] FIG. 1 is a sectional view of a para-aramid-polycarbonate
(PC) laminate.
[0019] FIG. 2 is a sectional view of another para-aramid-PC
laminate.
[0020] FIG. 3 is a sectional view of a para-aramid-para-aramid
laminate.
[0021] FIG. 4 is a sectional view of a para-aramid-polyolefin
laminate.
[0022] FIG. 5 is a sectional view of another para-aramid-polyolefin
laminate
[0023] FIG. 6 is a sectional view of another
para-aramid-para-aramid laminate.
DETAILED DESCRIPTION
[0024] 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.
[0025] 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".
[0026] 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. Pat. Nos. 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.
[0027] The preferred para-aramid is poly (p-phenylene
terephthalamide) which is called PPD-T.
[0028] The fabric may be woven, unidirectional, multidirectional,
including bidirectional, or nonwoven.
[0029] 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.
[0030] 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.degree.
orientation with respect to the machine 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.
[0031] 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.
[0032] 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.
[0033] As used herein the term "spunbond 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. No.
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.
[0034] 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.
[0035] As used in this application, the term "high modulus" refers
to materials having a modulus greater than 1,000 grams per denier
(gpd).
[0036] 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.RTM.),
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).
[0037] 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.degree. C. to 150.degree. 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.degree.
C. using a weight of 2.16 kg.
[0038] 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.
[0039] 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 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).
[0040] 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.
[0041] 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.RTM. from E. I. du Pont de Nemours and Company,
Wilmington, Del., USA.
[0042] 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.
[0043] 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.degree. 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 structure
is cooled, typically to 50.degree. C., while keeping constant the
pressure and then is cooled to room temperature under ambient
conditions.
[0044] An aspect of the present invention is a trauma reducing
pack, comprising
[0045] 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.
[0046] 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
[0047] c. a polyolefinic adhesive having a melting point of from
70-150.degree. C.,
[0048] wherein at least one first layer and at least one second
layer are bonded together by means of the polyolefinic
adhesive.
[0049] In one embodiment of the present invention, the polyolefinic
adhesive in the trauma reducing pack is an ethylene copolymer.
[0050] In another embodiment of the present invention, the
polyolefinic adhesive in the trauma reducing pack is a grafted
polyolefin.
[0051] In still another embodiment of the present invention, the
fibers in the aramid fabric are woven, nonwoven, unidirectional or
multidirectional.
[0052] In yet another embodiment of the present invention, the
thermoplastic sheet is selected from polycarbonates, acrylonitrile
butadiene styrene, ethylene-methacrylic acid copolymers,
bidirectional polyolefinic tape or combinations thereof
[0053] In another embodiment of the present invention, the
thermoplastic nonwoven fabric is a spunbond nonwoven of
polyolefin.
[0054] In another embodiment of the present invention, the
polyolefin is a polyethylene, polypropylene, polybutene, or a blend
or copolymer thereof.
[0055] In another embodiment of the present invention, the
multidirectional polyolefinic tape is a cross-plied non-fibrous
ultra-high molecular weight polyethylene (UHMWPE) tape.
[0056] In still another embodiment of the present invention, the
trauma pack has an areal density of less than 1000 g/m2.
[0057] 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.
[0058] Another aspect of the present invention is a body armor
comprising at least one trauma pack.
DETAILED DESCRIPTION OF FIGURES
[0059] FIG. 1 is a sectional view of a para-aramid-polycarbonate
laminate comprising: [0060] 1. Para-aramid fabric [0061] 2.
Polyolefinic adhesive [0062] 3. Polycarbonate sheet
[0063] FIG. 2 is a sectional view of another
para-aramid-polycarbonate laminate comprising: [0064] 1A. First
layer of para-aramid fabric [0065] 2A. First layer of polyolefinic
adhesive film [0066] 3. Polycarbonate sheet [0067] 2B. Second layer
of polyolefinic adhesive film [0068] 1B. Second layer of
para-aramid fabric
[0069] FIG. 3 is a sectional view of a para-aramid-para-aramid
laminate comprising: [0070] 1A. First layer of 1000 denier
para-aramid fabric [0071] 2A. First layer of polyolefinic adhesive
film [0072] 3A. First layer of 600 denier para-aramid fabric [0073]
2B. Second layer of polyolefinic adhesive film [0074] 3B. Second
layer of 600 denier para-aramid fabric [0075] 2C. Third layer of
polyolefinic adhesive film [0076] 1B. Second layer of 1000 denier
para-aramid fabric
[0077] FIG. 4 is a sectional view of another
para-aramid-para-aramid laminate comprising: [0078] 1. Para-aramid
fabric [0079] 2. Polyolefinic adhesive [0080] 3. A plurality of
polyolefin sheet layers
[0081] FIG. 5 is a sectional view of another para-aramid-polyolefin
laminate: [0082] 1A. First layer of 1000 denier para-aramid fabric
[0083] 2A. First layer of polyolefinic adhesive film [0084] 3A.
First layer of spun bonded polyethylene nonwoven fabrics [0085] 2B.
Second layer of polyolefinic adhesive film [0086] 3B. Second layer
of spun bonded polyethylene nonwoven fabrics [0087] 2C. Third layer
of polyolefinic adhesive film [0088] 3C. Third layer of spun bonded
polyethylene nonwoven fabrics [0089] 2D. Fourth layer of
polyolefinic adhesive film [0090] 1B. Second layer of 1000 denier
para-aramid fabric
[0091] FIG. 6 is a sectional view of a para-aramid-polyolefin
laminate comprising: [0092] 1A. First layer of 3300 denier
para-aramid fabric [0093] 2. A layer of polyolefinic adhesive film
[0094] 1B. Second layer of 3300 denier para-aramid fabric
TEST METHODS
[0095] Temperature: All temperatures were measured in degrees
Celsius (.degree. C.).
[0096] 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). 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).
[0097] 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.
[0098] Areal Density: The areal density of the fabric layer was
determined by measuring the weight of one square meter of fabric
i.e., 1 m.times.1 m. The areal density of a composite structure was
determined by the sum of the areal densities of the individual
layers.
[0099] Melt flow index was measured as per ASTM D 1238-13.
[0100] 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.degree. 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 25 mm before and after conditioning.
Trauma Test Method (Back Face Deformation or BFD)
[0101] 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.times.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
[0102] Fabric layers and adhesive films of the following
description were used for preparing the multilayer laminated
composite trauma pack;
[0103] 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.times.8.5 ends per centimeter available from E. I. du Pont de
Nemours and Company, Wilmington, Del., USA (hereinafter DuPont)
under the trade name of Kevlar.RTM. para-aramid and was cut into
400.times.400 mm sheets.
[0104] 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 Kevlar.RTM. XPS300 and was cut
into 400.times.400 mm sheet.
[0105] 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 Kevlar.RTM. XPS102 and was cut
into 400.times.400 mm sheet.
[0106] 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.times.8.5 ends per centimeter available from DuPont under the
trade name of Kevlar.RTM. para-aramid and was cut into
400.times.400 mm sheet.
[0107] 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.times.6.5 ends per centimeter available from E. I. du Pont de
Nemours and Company, Wilmington, Del., USA (hereinafter DuPont)
under the trade name of Kevlar.RTM. para-aramid and was cut into
400.times.400 mm sheets.
IC 600D was a commercially available Kevlar.RTM. composite fabric
having an areal density of 900 g/m2 available from DuPont.
[0108] PE-1 was a bidirectional tape made of ultra-high molecular
weight polyethylene having areal density of 111 g/m.sup.2 available
from DuPont Company under the trade name of Tensylon.TM. HSBD
30A.
[0109] PE-2 was a spun bonded polyethylene nonwoven fabrics having
areal density of 73 g/m.sup.2 available from DuPont under the trade
name of Tyvek.RTM..
[0110] PE-3 was a spun bonded polyethylene nonwoven fabric having
areal density of 105 g/m.sup.2 available from DuPont under the
trade name of Tyvek.RTM..
[0111] PC-1 was a Polycarbonate sheet of 0.8 mm thicknesses having
aerial density of 1000 g/m.sup.2 available from SABIC Innovative
Plastics under the trade name of Lexan.RTM..
[0112] PC-2: was a Polycarbonate sheet of 0.3 mm thicknesses having
aerial density of 475 g/m.sup.2 available from SABIC Innovative
Plastics under the trade name of Lexan.RTM..
[0113] 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.degree. C.; melt flow index in the range of 2 to 9 g/10 min and
having aerial density of 50 g/m.sup.2 available from DuPont under
the trade name of Bynel.RTM..
[0114] Adhesive Film 2 was an ethylene copolymer having functional
groups such as vinyl acetate; having melting points in the range of
115 to 130.degree. C.; melt flow index in the range of 3 to 8 g/10
min and having aerial density of 50 g/m.sup.2 available from
Nolax.RTM. AG under the trade name of Nolax.RTM..
[0115] 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.degree. C.; melt flow index in the range of 3 to 8 g/10 min
and having aerial density of 50 g/m.sup.2 available from DuPont
under the trade name of Surlyn.RTM..
EXAMPLES
[0116] 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
[0117] A commercially available Kevlar.RTM. composite fabric having
an areal density of 900 g/m.sup.2 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
[0118] A stack of 15 layers of multidirectional woven fabric KL2
made of 400 denier Kevlar.RTM. yarn and having areal density of 300
g/m.sup.2 was used as the ballistic pack without any trauma
pack.
Example B
[0119] 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/m.sup.2. The ballistic pack comprised 9
layers of KL2.
Example C
[0120] 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 in example 1, except that the
preheating temperature was 115.degree. C. The stack was heated to
125.degree. 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 860 g/m.sup.2. The ballistic pack comprised 11
layers of KL2.
Example D
[0121] 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.degree. C. The stack was heated to
125.degree. 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/m.sup.2. The ballistic pack comprised 11
layers of KL2.
Example 1
[0122] 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.degree. C.) having heating and cooling capability for 10
minutes at 140.degree. C. and 60 ton and then cooled to room
temperature to yield a laminate/trauma reducing pack having an
aerial density of 1240 g/m.sup.2. The ballistic pack comprised 10
layers of KL2.
Example 2
[0123] 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/m.sup.2. The
ballistic pack comprised 9 layers of KL2.
Example 3
[0124] A trauma pack was formed as described in example 1, except
that PC2 was used in place of PC1. The construction of the laminate
was KL1-Film2-PC2 and the aerial density of resultant pack was 715
g/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Example 4
[0125] A trauma pack was formed as described in example 2, except
that PC2 was used in place of PC1. The construction of the laminate
was KL1-Film2-PC2-Film2-KL1 and the aerial density of resultant
pack was 955 g/m.sup.2. The ballistic pack comprised 8 layers of
KL2.
Example 5
[0126] 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.degree. C. and 125.degree. C. respectively to
yield a laminate/trauma reducing pack having an aerial density of
800 g/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Example 6
[0127] 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/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Example 7
[0128] 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-Film3-KL1) to yield a
laminate/trauma reducing pack having an aerial density of 800
g/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Example 8
[0129] 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/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Example 9
[0130] 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.degree. C. and 125.degree. C. respectively to yield a
laminate/trauma reducing pack having an areal density of 900
g/m.sup.2. The ballistic pack comprised 11 layers of KL2.
Ballistic Trauma Test
[0131] 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/m.sup.2
and a thickness of 4 millimeters each in order to form a stack.
[0132] 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/m.sup.2 and a
thickness of 4 millimeters each in order to form a stack.
[0133] The inventive test sample consisted of a trauma reducing
pack according to Examples 1-9.
[0134] 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.
[0135] 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.times.19 mm bullet (OFB,
India) traveling at a speed of 400.+-.15 m/s, shot from a distance
of 5 meters.
[0136] 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-US-00001 TABLE 1 Aerial Backface Ballistic Trauma Density
Signature mean Std Pack Pack (g/m.sup.2) (mm) Dev 15 L KL2 Control
A NA 18.4 2.8 9 L KL2 Example B 1380 29.2 4.3 10 L KL2 Example 1
1240 10.6 0.9 9 L KL2 Example 2 1480 13.4 1.3 11 L KL2 Example 3
715 14.1 0.6 8 L KL2 Example 4 955 14.1 1.1
[0137] 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).
TABLE-US-00002 TABLE 2 Aerial Backface Ballistic Trauma Density
Signature mean Std Pack Pack (g/m.sup.2) (mm) Dev 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-US-00003 TABLE 3 Aerial Backface Ballistic Trauma Density
Signature mean Std Pack Pack (g/m.sup.2) (mm) Dev 11 L KL2 Example
A 900 15.5 2.1 15 L KL2 Control A NA 18.4 2.8 11 L KL2 Example 9
900 12.4 1.1
[0138] Among the aramid-polyolefin laminates, a change in adhesive
film from a grafted to a straight chain ethylene copolymer
(examples 5-example 7) significantly improved the backface
signature, also change of polyethylene (example 7 and example 8)
from a lower to higher areal density did not improve the backface
signature.
[0139] On the other hand, a stack of multiple layers of
bidirectional UHMWPE tape (Tensylon.TM.) 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 Tensylon.TM. had adhesive layer on one side.
Environmental Conditioning Test Results
[0140] Each trauma pack was subjected to the temperature of
65.+-.2.degree. 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 having
an area density of 100 g/m.sup.2 and a thickness of 4 millimeters
for testing backface signature according to the following
method.
[0141] 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.times.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.
[0142] Soft body armor containing trauma pack as described above
showed backface signature before and after environmental
conditioning as shown in Table 4 below;
TABLE-US-00004 TABLE 4 Backface Signature (mm) Before After Trauma
Conditioning Conditioning Pack Average Std Dev Average Std 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
[0143] All trauma packs even after environmental conditioning
showed backface signature less than 25 mm.
* * * * *