Note: Descriptions are shown in the official language in which they were submitted.
~Y~ nol PCT/US9l/035~
2G33~1~
BA~G~QUND OF THE I~VENTIO~
1. Fiel~_of 5~L~IlY D~ion
This invention relates to ballistic resistant
composite articles. More particularly, thic invention
relates to such articles having improved ballistic
protection.
2. Prior Art
Ballistic articles such as bulletproof vests,
helmets, structural members of helicopters and other
military equipment, vehicle panels, briefcases,
raincoats, parachutes, and umbrellas containing high
strength fibers are known. Fibers conventionally used
include aramid fibers such as poly (phenylenediamine
terephthalamide), graphite fibers, nylon fibers,
ceramic fibers, glass fibers and the like. For many
applications, such as vests or parts of vests, the
fibers are used in a woven or Xnitted fabric. For many
of the applications, the fibers are encapsulated or
embedded in a matrix material.
In ~The Application of High Modulus Fibers to
Ballistic Protection", R.C. Liable et al., J. Macromol.
Sci.-Chem. A7(1), pp. 295-322, 1973, it is indicated on
p. 298 that a fourth requirement is that the textile
material have a high degree of heat resistance. In an
NTIS publication, AD-A018 958 "New Materials in
Construction for Improved Helmets", A.L. Alesi et al.,
a multilayer highly oriented polypropylene film
material (without matrix), referred to as "XP", was
evaluated against an aramid fiber (with a
phenolic/polyvinyl butyral resin matrix). The aramid - -
system was judged to have the most promising
combination of superior performance and a minimum of
problems for combat helmet development. USP 4,403,012
and USP ~, 457,985 disclose ballistic resistant
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~092/~9861 PCT/US91/035~
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composite articles comprised of networks of high
molecular weight polyethylene or polypropylene fibers,
and matrices composed of olefin polymers and
copolymers, unsaturated polyester resins, epoxy resins,
and other resins curable below the melting point of the
fiber.
A.L. Lastnik, et al., "The Effect of Resin
concentration and Laminating Pressures on XEVLAR Fabric
Bonded with Modified Phenolic Resin", Tech. Report
NATICX/TR-84/030, June 8, 1984; disclose that an
interstitial resin, which encapsulates and bDnds the
fibers of a fabric, reduces the ballistic resistance of
the resultant composite article.
US Patent Nos. 4,623,574 and 4,748,064 disclose a
simple composite structure exhibits outstanding
ballistic protection as compared to simple composites
utilizing rigid matrices, the results of which are
disclosed in the patents. Particularly effective are
weight polyethylene and polypropylene such as disclosed
in US Patent No. 4,413,110.
US Patent Nos. 4,737,402 and 4,613,535 disclose
complex rigid composite articles having improved impact
resistance which comprise a network of high strength
fibers such as the ultra-high molecular weight
polyethylene and polypropylene disclosed in US Patent
No. 4,413,110 embedded in an elastomeric matrix
material and at least one additional rigid layer on a
major surface of the fibers in the matrix. It is
disclosed that t~e composites have improved resistance
to environmental hazards, improved impact resistance
and are unexpectedly effective as ballistic resistant
articles such as armor.
U.S. Patent 3,516,890 disclosed an armor plate
composite with multiple-hit capability. US Patent No.
4,836,084 discloses an armor plate composite composed
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W092/09X6l PCT/US91/03524
209~816
of four main components, a ceramic impact layer for
blunting the tip of a projectile, a sub-layer laminate
of metal sheets alternating with fabrics impregnated
with a viscoelastic synthetic material for absorbing
the kinetic energy of the projectile by plastic
deformation and a bacXing layer consisting of a pack of
impregnated fabrics. It is disclosed that the optimum
combination of the four main components gives a high
degree of protection at a limited weight per unit of
surface area.
Ballistic resistant armor made of ceramic tiles
connected to a metal substrate exhibit certain
properties which substantially reduces the ~ultiple hit
capability of the armor. On impact of the projectile,
substantial amounts of vibrational energy are produced
in addition to the kinetic energy of the impact. This
vibrational energy can be transmitted as noise and
shock, or can be transmitted to vibration sensitive
areas of the armor such as to the ceramic impact layer
resulting in a shattering and/or loosing of tiles.
SUMMARY OF THE INVENTION
This invention relates to a multilayer complex
ballistic armor comprising:
(a) a hard impact layer comprised of one or more
ceramic bodies;
(b) a vibration isolating layer; and
(c) a backing layer comprised of a rigid
material; wherein the portion of said vibration
isolating layer at or about the surfaces thereof have
flexural modulus egual to or greater than about 0.01
msi, an elongation-to-break egual to or less than about
40% and a fracture toughness egual to or greater than
about 1 MPa.m , and wherein the portion of said
vibration isolating layer at or about the center
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~092tOg861 PCT/US91/035~
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thereof has an energy-to-break of at least about 8
joules/grams.
As used herein, "flexural modulus" is determined
by AS~ D790, "elongation to breaX" is determined by
S ASTM D638, fraction toughness i~ determined by the
method of S.T. Rolfe and J.M. Barsom, "Fracture and
Fatigue Control in Structures Applications of Fracture
MechanicsN, Prentice-Hall, Inc., New Jersey, USA 1977,
and the energy-to break is 2easured by ASTM D885.
Through use of the vibration isolating layer,
shock and vibration induced by impact of the projectile
are minimized. Moreover, the transmission of existing
shock and vibration which can damage portions of the
ceramic layer not hit by the projectile is inhibited
which substantially increases the multiple hit
capability of the armor.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood and
further advantages will become apparent when reference
is made to the following detailed description of the
invention and the accompanying drawings in which:
FIG 1 is a prospective view of an armor plate
according to this invention showing its essential
elements of a ceramic impact layer, a vibration
isolating layer and a backing layer;
FIG 2 is a view in cross-section and side
elevation of a modified embodiment of this invention
depicted in FIG 1.
FIG 3 is a view in cross-section and side
elevation of an embodiment of this invention having a
modified ceramic layer.
DETAILED DESCRIPTION OF ~ NVENTION
The present invention will be better understood by
those of skill in the art by reference to the above
figures. Referring to FIG 1, the numeral 10 indicates
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W092/09861 PCT/US91/03~
20~1 6
a ballistic resistant article 10. Article 10, as shown
in FIG 1, comprises three maintain components; a
ceramic i~pact layer 12, a vibration isolating layer
14, and a backing layer 16. In the preferred
embodiments of this invention, ceramic impact layer 12
comprises a plurality of ceramic bodies 18, in the more
preferred embodiments of the invention, ceramic impact
layer 12 comprises at least about four ceramic bodies
12 and in the most preferred embodiments of the
invention, ceramic impact layer 12 comprises at least
about nine ceramic bodies 12, with those embodiments in
which the number of bodies 12 in layer 12 is at least
about sixteen being the embodiment of choice.
Ceramic impact layer 12 i5 excellently suitable
for blunting the tip of the projectile, particularly
because the ceramic material forming layer 12 will
retain its hardness and strength despite the high
increase in temperature that will occur in the region
struck by a projectile. Ceramic impact layer 12
comprises of one or more of ceramic bodies 18.
Body 18 is formed of a ceramic material. Useful
ceramic materials may vary widely and include those
materials normally used in the fabrication of ceramic
armor which function to partially deform the initial
impact surface of a projectile or cause the projectile
to shatter. Illustrative of such metal and non-metal
ceramic materials are those described in C.F. Liable,
Ballistic Materials and Penetration Mechanics, Chapters
5-7 (1980) and include single oxides such as aluminum
oxide (Al2O3), barium oxide (BaO), beryllium oxide
(BeO), calcium oxide (CaO), cerium oxide (Ce2O3 and
CeO2), chromium oxide (Cr2O3), dysprosium oxide (Dy2O3),
erbium oxide (Er2O3), europium oxide: (EuO, Eu2O3, and
Eu2O~), (EU16O21)~ gadolinium oxide (Gd2O3), hafnium oxide
35 (HfO2), holmium oxide (Ho2O3), lanthanum oxide ~La2O3)
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W092/0986l PCT/US9l/035~
9 j~ ~6
lutetium oxide (Lu2~), magnesium oxide (MgO),
neodymium oxide (Nd2~), niobium oxide: (NbO, Nb2~,
and NbO2), (Nb20s), plutonium oxide: (PuO, Pu2~, and
Pu02), praseodymium oxide: (PrO2, Pr60~, and Pr2~),
promethium oxide tPm203), samarium oxide (SmO and
Sm2C~), scandium oxide (Sc2~), silicon dioxide (SiO2),
strontium oxide (SrO), tantalum oxide (Ta2C~), terbium
oxide (Tb2~ and Tb407), thorium oxide (ThO2), thulium
oxide (Tm2~), titaniu~ oxide: (Tio~ Ti2o~, Ti30s and
Tio2), uranium oxide (U02, U30B and U~), vanadium oxide
(VO, V2~, VO2 and V205), ytterbium oxide (Yb203),
yttrium oxide (Y203), and zirconium oxide (ZrO2). Useful
ceramic materials also include boron carbide, zirconium
carbide, beryllium carbide, aluminum beride, aluminum
carbide, boron carbide, silicon carbide, aluminum
carbide, titanium nitride, boron nitride, titanium
carbide, titanium diboride, iron carbide, iron nitride,
barium titanate, aluminum nitride, titanium niobate,
boron carbide, silicon boride, barium titanate, silicon
nitride, calcium titanate, tantalum carbide, graphites,
tungsten; the ceramic alloys which include
cordierite/NAS, lead zirconate titanate/PLZT,
alumina-titanium carbide, aluminum-zirconia,
zirconia-cordierite/ZrMAS; the fiber reinforced
ceramics and ceramic alloys; glassy ceramics; as well
as other useful materials. Preferred materials for
fabrication of ceramic body 12 are aluminum oxide and
metal and non metal nitrides, borides and carbides.
The most preferred material for fabrication of ceramic
body 18 is aluminum oxide and titanium diboride.
The structure of ceramic body 18 can vary widely
depending on the use of the article. For example, body
18 can be a unitary structure composed of one ceramic
material or multilayer construction composed of layers
of the same material or different ceramic materials.
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Wos2Josx6l PCT/US9l/035~
209 ;~31 6
While in the figures ceramic body 18 is depicted
as a cubular solid, the shape of ceramic body 18 can
vary widely depending on the use of the article. For
example, ceramic body 18 can be an irregularly or a
regularly shaped body. Illustrative of a u~eful ceramic
body 18 are cubular, rectangular, cylindrlcal, and
polygonal (such as triangular, pentagonal and
hexagonal) shaped bodies. In the preferred embodiments
of the invention, ceramic body 18 is of cubular,
rectangular or cylindrical cross-section.
The size (width and height) of body 18 can also
vary widely depend~ng on the use of article 10. For
example, in those instances where article 10 is
intended for use in the fabrication of light ballistic
resistant composites for use against light armaments,
body 18 is generally smaller; conversely where article
lO is intended for use in the fabrication of heavy
ballietic resistant composites for use against heavy
armaments then body 18 is generally larger.
The cera~ic bodies 18 are attached to vibration
isolating layer 14 which isolates or substantially
isolates vibrational and shock waves resulting from the
impact of a projectile at a body 18 from other bodies
18 included in layer 12, and reduces the likelihood
that bodies 18 not at the point of projectile contact
will crack, shatter or loosen. The armor of this
invention has relatively higher efficiency of shock
absorbence. The efficiency of shock absorbence can be
measured by the number of completely undamaged (i.e.
free of cracks and flaws) ceramic bodies 18 immediately
adjacent to the body or bodies 18 at the point of
impact retained after impact. The % efficiency of
shock absorbence can be calculated from the following
equation:
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w092/0986l PCT/US91/035~
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% efficiency of shock absorbence -
100% x [1-d/t]
where "t" is the theoretical maximum number of ceramic
bodies 18 immediately adjacent to the ceramic body or
bodies 18 at the point of contact and "d" is the
difference between the theoretical max~mum number of
ceramic bodies 18 minus the Actual number of completely
undamaged ceramic bodies 18. Ceramic bodle~ 18 at the
point of contact may vary from one for as for example
for impacts at the center of a ceramic body 18 or at
the corner of a body 18 at the edge of ceramic impact
layer 12, to two for impacts at the seam of two
adjacent ceramic bodies 18 or at the corner of two
adjacent ceramic bodies 18 at the edge of impact layer
12 to four ~here the impact is at the intersecting
corner of four adjacent ceramic bodies 18. In the
preferred embodiments of the invention, % efficiency of
shock absorbence is at least about 70%, in the more
preferred embodiments of the invention, the %
efficiency of shock absorbence is at least about 95%,
and in the most preferred embodiments of the invention,
the % efficiency of shock absorbence is about 99 to
about 100%.
The amount of a surface of vibration isolating
layer 14 covered by ceramic bodies 18 may vary widely.
In general, the greater the area percent of the
surface vibration isolating layer 14 covered or loaded,
the more effective the protection, and conversely, the
lower the area percent of the surface vibration
isolating layer 14 covered the less effective the
protection. In the preferred, embodiment of the
invention, the area percent of the surface of vibration
isolating layer 14 covered by ceramic bodies 18 is
equal to or greater than about 95 area percent based on
the total surface area of vibration isolating layer 14,
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and in the more preferred embodiments of the invention
the area percent of surface covered is equal to or
greater than about 97 area percent on the
aforementioned basis. Amongst the more preferred
embodiments of the invention, most preferred are those
in which the areas percent of the surface of vibration
isolating layer 14 covered by ceramic bodies 18 is
equal to or greater than about 98 or 99 area percent
based on the total surface area of vibration isolating
layer 14.
Means for attaching ceramic bodies 18 to vibration
isolating layer 14 may vary widely and may include any
means normally used on the art to provide this
function. Illustrative of useful attaching means are
adhesive such as those described in Liable, Chapter 6,
supra, bolts, screws, mechanical interlocks adhesives
such as metal and non-metal adhesives, organic
adhesives and the like. In the preferred embodiments
of this invention attaching means is selected from the
group consisting of flexible adhesive bonding agents.
Such flexible bonding agents provide several useful
functions. For example, such agents enhance structural
performance such that the composite is capable of
withstanding severe impact loads, and they enhance the
retention of segmented tiles which are not at the point
of impact and the retention of spall/particles created
by the shattering of tiles on impact. Such adhesives
also enhance the conversion of absorbed energy into
heat. As used herein, a "flexible adhesive" is a
polymeric adhesive which exhibits a Shore A Hardness of
from about 20 to 100.
In the preferred embodiments of the invention, the
adhesive material is a low modulus, elastomeric
material which has a tensile modulus, measured at about
23C, of less than about 7,000 psi (41,300 kpa).
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~092/0986l PCT/US91/035~
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Preferably, the tensile modulus of the elastomer$c
material is less than about 5,000 psi (34,500 kpa),
more preferably is less than 1,000 psi (6900 kpa) and
most preferably is less than about 500 psi (3450 kpa)
to provide even more improved performance. The glass
transition temperature (Tg) of the elastomeric material
(as evidenced by a sudden drop in the ductility and
elasticity of the material) is less than about 0C.
Preferably, the Tg of the elastomeric material is less
than about -40C, and more preferably is less than
about -50C. The elastomeric material also has an
elongation to break of at least about 5%. Preferably,
the elongation to break of the elastomeric material is
at least about 30%. Representative examples of
suitable elastomeric materials for use as a flexible
adhesive are those which have their structures,
properties, and formulation together with cross-linking
procedures summarized in the Encyclopedia of Polymer
Science, Vol. 5 in the section Elastomers-Synthetic
(John Wiley & sons Inc., 1964) and "Handbook of
Adhesivesn, Van Nostrand Reinhold Company (1977), 2nd
Ed., Edited by Irving Skeist. Illustrative of such
materials are block copolymers of conjugated dienes
such as butadiene and isoprene, and vinyl aromatic
monomers such as styrene, vinyl toluene and t-butyl
styrene; polydienes such as polybutadiene and
polychloroprene, polyisoprene; natural rubber; -
copolymers and polymers of olefins and dienes such as
ethylene-propylene copolymers, ethylene-propylene-diene
30 terpolymers and poly(isobutylene-co-isoprene~, -
polysulfide polymers, polyurethane elastomers, ~ -
chlorosulfonated polyethylene; plasticized
polyvinylchloride using dioctyl phthate or other
plasticizers well known in the art, butadiene
acrylonitrile elastomers, polyacrylates such as
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w092/0986l PCT/US91/035~
203~8l ~
poly(acrylic acid), poly(methylcyanoacrylate),
poly(methylacrylate), poly(ethyl acrylate),
poly(propylacrylate) and the like; polyacrylics such as
poly(acrylonitrile), poly(methylacrylonitrile),
poly(acrylamide), poly(N-isopropylacrylamide) and the
like, polyesters; polyethers; ~luoroelastomers;
poly(bismaleimide); flexible epoxies; flexible
phenolics; polyurethanes; silicone elastomers;
epoxy-polyamides; poly(alXylene oxides); polysulfides;
flexible polyamides; unsaturated polyesters; vinyl
esters, polyolefins, such as polybutylene and
polyethylene; polyvinyls such as poly(vinyl formate),
poly(vinylbenzoate), poly(vinyl-
carbazole), poly(vinylmethylketone), poly(vinyl-methyl
ether), polyvinyl acetate, polyvinyl butyral, and
poly(vinyl formal); and polyolefinic elastomers.
Preferred adhesives are polydienes such as
polybutadiene, polychloroprene and polyisoprene;
olefinic and copolymers such as ethylene-propylene
copolymers, ethylene-propylene-diene copolymers,
isobutylene-isoprene copolymers, and chlorosulfonated
polyethylene; natural rubber; polysulfides;
polyurethane elastomers; polyacrylates; polyethers;
fluoroelastomer; unsaturated polyesters; vinyl esters;
alkyds; flexible epoxy; flexible polyamides;
epichlorohydrin; polyvinyls; flexible phenolics;
silcone elastomers; thermoplastic elastomers;
copolymers of ethylene, polyvinyl formal, polyvinyl
butryal; and poly(bis-maleimide). Blends of any
combination of one or more of the above-mentioned
adhesive materials. Most preferred adhesives are
polybutadiene, polyisoprene, natural rubber,
ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers, polysulfides, polyurethane elastomers,
chlorosulfonated polyethylene, polychloroprene,
w092/09x6l PCT/US91/03524
~99~
12
poly(isobutylene-co-isoprene), polyacrylates,
polyesters, polyethers, fluoroelastomers, unsaturated
polyesters, vinyl esters, flexible epoxy, flexible
nylon, silicone elastomers, copolymers of ethylene,
polyvinyl formal, polvvinyl butryal. Blends of any
combination of one or more of the above-mentioned
adhesive ~aterials.
The structure of vibrating isolating layer 14 is
critical to the multiple hit capability of ballistic
resistant article 10. As depicted in FIG. 1, vibration
isolating layer 14 includes three distinct regions or
layers; center region or layer 20 and surface regions
or layers 22 and 24 which sandwich region or layer 20.
Regions or layer 20, 22 and 24 have properties which
allow them to interact to provide a multi-hit
capability. Region or layer 20 functions to absorb the
shock of the projectile's impact and can be formed of
any material which performs this function. The shock
absorbing capability of a material can be expressed in
terms of ~ts energy-to-break. In general, region or
layer 20 is formed of a material which has an
energy-to-break equal to or greater than about 8
joules/grams. Preferred materials for fabrication of
layer or region 20 are those which have an
energy-to-break equal to or greater than about 20
joules/grams, more preferred materials are those which
have an energy-to-break equal to or greater than about
30 joules/gram and most preferred materials are those
having an energy-to-break equal to or greater than
about 35 joules/grams. In the practice of this
invention ~aterials of choice for use in the
fabrication of region or layer 20 are those having an
energy-to-break of ~0 joules/grams.
In the preferred embodiments of the invention,
3S layer 20 comprises a net work of polymeric fibers
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~'0 92tO9X61 P(~/l,'S91/03524
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having a tsnacity of at least about 7 grams/denier as
measured by ASTM D885, and a tensile modulus of 160
grams/denier as measured by ASTM D885 (pulling a 10
inc. (25.4cm) ~lber length clamped in barrel clamps at
s a rate of lOin/min (25.4cm/min) on an Instron Tensile
TestQr) and an energy-to-break of at least about 8
~oules/gram also as mea~ured by ASTM D885. Preferred
fibers for u~e in the practice of this invention are
those having a tenacity equal to or greater than about
10 g/d, a tensile modulus equal to or greater than
about 150 g/d, and an energy-to-break egual to or
greater than about 8 joulestgrams. Particularly
preferred fibers are those having a tenacity egual to
or greater than about 20 g/d, a tensile modulus equal
to or greater than about 500 g/d and energy-to-break
equal to or greater than about 30 joules/grams.
Amongst these particularly preferred embodiments, most
preferred are those embodiments in which the tenacity
of the fibers are equal to or greater than about 25
g/d, and energy-to-break is equal to or greater than
about 35 joules/gram. In the practice of this
invention, fibers of choice have a tenacity equal to or
greater than about 30 g/d and the energy-to-break is
egual to or greater than about 40 joules/gram.
The type of fibers used in the fabrication of
layer or region 20 of the preferred embodiments of the
invention may vary widely and can be metallic fibers,
semi-metallic fibers, inorganic fibers and/or organic
fibers. Illustrative of useful organic fibers are those
composed of polyesters, polyolefins, polyetheramides,
fluoropolymers, polyethers, celluloses, phenolics,
polyesteramides, polyurethanes, epoxies, amimoplastics,
silicones, polysulfones, polyetherketones,
polyetherether-ketones, polyesterimides, polyphenylene
sulfides, polyether acryl ketones, poly(amideimides),
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WO 92/09861 PCr/US91/03524
~ ~ 9 ~
and polyi~ides. Illustrative of other useful organic
filaments are those composed of aramids (aromatic
polyamides), such as poly(m-xylylene adipamide),
poly(p-xylylene sebacamide), poly 2,2,2-trimethyl-
5 hexamethylene terephthalamide), poly (piperazine J
sebacamide), poly (metaphenylene isophthalamide)
(Nomex) and poly (p-phenylene terephthalamide)
(Kevlar); aliphatic and cycloaliphatic polyamides, such
as the copolyamide of 30% hexamethylene diammonium
lO isophthalate and 70% hexamethylene diammonium adipate,
the copolyamide of up to 30~ `
bis-(-amidocyclohexyl)methylene, terephthalic acid and
caprolactam, polyhexamethylene adipamide (nylon 66),
poly(butyrolactam) (nylon 4), poly (9-aminonoanoic
15 acid) (nylon 9), poly(enantholactam) (nylon 7),
poly(capryllactam) (nylon 8), polycaprolactam (nylon
6), poly ~p-phenylene terephthalamide), -
polyhexamethylene sebacamide (nylon 6,10),
polyaminoundecanamide (nylon 11), polydodeconolactam
20 (nylon 12), polyhexamethylene isophthalamide,
polyhexamethylene terephthalamide, polycaproamide,
poly(nonamethylene azelamide) (nylon 9,9), : '
poly(decamethylene azelamide) (nylon 10,9),
poly(decamethylene sebacamide) (nylon 10,10),
25 poly[bis-(4-aminocyclothexyl) methane 1,10-
decanedicarboxamide~ (Qiana) (trans), or combination
thereof; and aliphatic, cycloaliphatic and aromatic
polyesters such as poly(l,4-cyclohexlidene dimethyl
eneterephathalate) cis and trans, poly(ethylene-1,
30 5-naphthalate), poly(ethylene-2,6-naphthalate), poly(1,
4-cyclohexane dimethylene terephthalate) (trans),
poly(decamethylene terephthalate), poly(ethylene
terephthalate), poly(ethylene isophthalate),
poly(ethylene oxybenozoate), poly(para-hydroxy
35 benzoate), poly(dimethylpropiolactone),
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Wo92/09#~1 PCT/US91/035~
2 0 ~ 6
poly(decamethylene adipate), poly(ethylene succinate),
poly(ethylene azelate), poly(decamethylene sebacate),
poly(a,a-dimethyl-propiolactone), and the like.
Also illustrative of useful organic fibers are
those of liguid crystalline polymers such as lyotropic
liquid crystalline polymers which include polypeptides
such as poly (g-benzyl L-glutamate) and the llke;
aromatic polyamides such as poly(l,4-benzamide),
poly(chloro-1,4-phenylene terephthalamide),
poly(l,4-phenylene fumaramide),
poly(chloro-1,4-phenylene fumaramide), .
poly(4,4'-benzanilide trans, trans-muconamide),
poly(l,4-phenylene mesaconamide), poly(l,4-phenylene)
(trans-1,4-cyclohexylene amide), poly(chloro-1,4-
phenylene) (trans-1,4-cyclohexylene amide), poly(l,4-
phenylene 1,4-dimethyl-trans-1,4-cyclohexylene amide),
poly(l,4-phenylene 2.5-pyridine amide),
poly(chloro-1,4-phenylene 2.5-pyridine amide),
poly(3,3'-dimethyl-4,4'-biphenylene 2.5 pyridine
amide), poly(l,4-phenylene 4,4'-stilbene amide),
poly(chloro-1,4-phenylene 4,4'-stilbene amide),
poly(l,4-phenylene 4,4'-azobenzene amide),
poly(4,4'-azobenzene 4,4'-azobenzene amide),
poly(1,4-phenylene 4,4'-azoxybenzene amide), poly(4,4'-
azobenzene 4,4'-azoxybenzene amide), poly(l,4-
cyclohexylene 4,4'-azobenzene amide),
poly(4,4'-azobenzene terephthal amide),
poly(3,8-phenanthridinone terephthal amide),
poly(4,4'-biphenylene terephthal amide),
poly(4,4'-biphenylene 4,4'-bibenzo amide), poly(l,4-
phenylene 4,4'-bibenzo amide), poly(l,4-phenylene
4,4'-terephenylene amide), poly(l,4-phenylene
2,6-naphthal amide), poly(1,5-naphthylene terephthal
amide), poly(3,3'-dimethyl-4,4-biphenylene terephthal
amide)~ poly(3,3'-dimethoxy-4,4'-biphenylene terephthal
."" : . , , . - .;
' , ' ~ .
WO 92/09~61 PCT/US91/03524
20~
16
amide), pGly(3,3'-dimethoxy-4,4-biphenylene
4,4'-bibenzo amide) and the like; polyoxamides such as
those derived from 2,2'dimethyl-4,4'diamino biphenyl
and chloro-1,4-phenylene diamine; polyhydrazides such
as poly chloroterephthalic hydrazide, 2,5-pyridine
dicarboxylic acid hydrazide) poly(terephthalic
hydrazide), poly(terephthalic- chloroterephthalic
hydrazide) and the like; poly(amide-hydrazideQ) such as
poly(terephthaloyl 1,4 amino-benzhydrazide) and those
prepared from 4-amino-benzhydrazide, oxalic
dihydrazide, terephthalicdihydrazide and para-aromatic
diacid chlorides; polyesters such as those of the
compositions include poly(oxy-trans-
1,4-cyclohexyleneoxycarbonyl-trans-1,4-cyclohexylenecar
bonyl-~-oxy-1,4-phenyl-eneoxyterephthaloyl) and
poly(oxy-cis-1,4-cyclohexyleneoxycarbonyl-trans-1,4-cyc
lohexylenecarbonyl-~-oxy-1,4-phenyleneoxyterephthaloyl)
in methylene chloride-o-cresol
poly[(oxy-trans-1~4-cyclohexylene-
oxycarbonyl-trans-1,4-cyclohexylenecarbonyl-~-oxy-(2-me
thyl- 1,4-phenylene)oxy-terephthaloyl)] in
1,1,2,2-tetrachloro-ethane-o-chlorophenol-phenol
(60:25:15 vol/vol/vol),
polytoxy-trans-1,4-cyclohexyleneoxycarbonyl-trans-1,4-
cyclohexylenecarbonyl-~-oxy(2-methyl-1,3-phenylene)oxy-
tsrephthaloyl] in o-chlorophenol and the like;
polyazomethines such as those prepared from
4,4'-diaminobenzanilide and terephthalaldephide,
methyl-1,4-phenylenediamine and terephthalaldelyde and
the like; polyisocyanides such as poly(-phenyl ethyl
isocyanide), poly(n-octyl isocyanide) and the like;
polyisocyanates such as poly(n-alkyl isocyanates) as
Sor example polyln-butyl isocyanate), poly(n-hexyl
isocyanate) and the liXe; lyotropic crystalline
polymers with heterocylic units such as
,, , ,,, , ~, .
WO g2/09X61 PCr/~'S91/03~24
2 0 ~ s
17
poly(l,4-phenylene-2,6-benzobisthiazole)(PBT),
poly(1,4-phenylene-2,6-benzobisoxazole)(PB0),
poly(1,4-phenylene-1,3,4-oxadiazole),
poly(1,4-phenylene-2,6-benzobisimidazole),
poly[2,5(6~-benzimidazole] (A~-PBI), poly~2,6-(1,4-
phneylene)-4-phenylquinoline], poly~1,1'-(4,4'-
biphenylene)-6,6'-bis(4-phenylguinoline)] and the like;
polyor~anophosphazines such as polyphosphazine,
polybisphenoxyphosphazine, poly[bis(2,2,2'
trifluoroethyelene) phosphazine~ and the like; metal
polymers such as those derived by condensation of
trans-bis(tri-n-butylphosphine)platinum dichloride with
a bisacetylene or
trans-bis(tri-n-butylphosphine)bis(1,4-
butadinynyl)platinum and similar combinations in thepresence of cuprous iodine and an amide; cellulose and
cellose derivatives such as esters of cellulose as for
example triacetate cellulose, acetate cellulose,
acetate-butyrate cellulose, nitrate cellulose, and
20 sulfate cellulose, ethers of cellulose as for example, ~ .
ethyl ether cellulose, hydroxymethyl ether cellulose,
hydroxypropyl ether cellulose, carboxymethyl ether
celulose, ethyl hydroxyethyl ether cellulose,
cyanoethylethyl ether cellulose, ether-esters of
cellulose as for example acetoxyethyl ether cellulose
and benzoyloxypropyl ether cellulose, and urethane
cellulose as for example phenyl urethane cellulose;
thermotropic liquid crystalline polymers such as
celluloses and their derivatives as for example
hydroxypropyl cellulose, ethyl cellulose
propionoxypropyl cellulose; thermotropic copolyesters
as for example copolymers of 6-hydroxy-2-naphthoic acid
and p-hydroxy benzoic acid, copolymers of 6-hydroxy-2-
naphthoic acid, terephthalic acid and hydroquinone and
copolymers of poly(ethylene terephthalate) and
'
,
' ~ "
wos2/nsx6~ PCT/US91/035~
2 ~ 1 6
p-hydroxybenzoic acid; and thermotropic polyamides and
thermotropic copoly(amide-esters).
Also illustrative of useful organic fibers for use
in the fabrication o region or layer 20 of vibration
isolating layer 14 are those composed of extended chain
polymers formed by polymerization of ~ unsaturated
monomers of the formula:
R~ R2-C = CH2
wherein:
Rl and R2 are the same or different and are
hydrogen,hydroxy, halogen, alkylcarbonyl, carboxy,
alkoxycarbonyl, heterocycle or alkyl or aryl either
unsubstituted or substituted with one or more
substituents selected from the group consisting of
alkoxy, cyano, hydroxy, alkyl and aryl. Illustrative
of ~uch polymers of ~,~-unsaturated monomers are
polymers including polystyrene, polyethylene,
polypropylene, poly(l-octadecene), polyisobutylene,
poly~l-pentene), poly(2-methylstyrene),
poly(4-methylstyrene), poly(l-hexene), poly(l-pentene),
poly(4-methoxystrene), poly(5-methyl-1-hexene),
poly(4-methylpentene), poly (l-butene), polyvinyl
chloride, polybutylene, polyacrylonitrile, poly(methyl
pentene-l), poly(vinyl alcohol), poly(vinylacetate),
poly(vinyl butyral), poly(vinyl chloride),
poly(vinylidene chloride), vinyl chloride-vinyl acetate
chloride copolymer, poly(vinylidene fluoride),
poly(methyl acrylate, poly(methyl methacrylate),
poly(methacrylo-nitrile), poly(acrylamide), poly(vinyl
fluoride), poly(vinyl formal), poly(3-methyl-
l-butene), poly(l-pentene), poly(4-methyl-1-butene),
poly(l-pentene), poly(4-methyl-1-pentence,
poly(l-hexane), poly(5-methyl-1-hexene), poly(vinyl-
cyclopentane), poly(vinylcyclothexane), poly(a-vinyl-
naphthalene), poly(vinyl methyl ether), poly(vinyl-
,
:, :
,
W092/09X6l PCr/~S91/035~
2 0 ~ ~ 8 1 ~
19
ethylether), poly(vinyl propylether), poly(vinyl
carbazole), poly(vinyl pyrrolidone),
poly(2-chlorostyrene), poly(4-chlorostyrene),
poly(vinyl formate), poly(vinyl butyl ether),
poly(vinyl octyl ether), poly(vinyl msthyl ketone),
poly(methylisopropenyl ketone), poly(4-phenylstyrene)
and the like.
Illustrative of useful inorganic fibers for use in
the fabrication of layer 20 of vibration isolating
layer 14 are glass fibers such as fibers formed from
quartz, magnesia aluminosilicate, non-alkaline
aluminoborosilicate, soda borosilicate, soda silicate,
soda lime-aluminosilicate, lead silicate, non-alkaline
lead boroalumina, non-alkaline barium boroalumina,
non-alkaline zinc boroalumina, non-alkaline iron
aluminosilicate, cadmium borate, alumina fibers which
include "saffil" fiber in eta, delta, and theta phase
form, asbestos, boron, silicone carbide, graphite and
carbon such as those derived from the carbonization of
polyethylene, polyvinylalcohol, saras, polyamide -
(NomexO) type, nylon, polybenzimidazole,
polyoxadiazole, polyphenylene, PPR, petroleum and coal
pitches (isotropic), mesophase pitch, cellulose and
polyacrylonitrile, ceramic fibers such as those of the
ceramic materials discussed earlier for the use in the
fabrication of ceramic body 18, metal fibers as for
example steel, aluminum metal alloys, and the like.
In the preferred embodiments of the invention,
layer 20 is fabricated from a fiber network, which may
include a high molecular weight polyethylene fiber, a
high molecular weight polypropylene fiber, an aramid
fiber, a high molecular weight polyvinyl alcohol fiber,
a high molecular weight polyacrylonitrile fiber or
mixtures thereof. Highly oriented polypropylene and
polyethylene fibers of molecular weight at least
'' ~ .
,
,,
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WO 92/09861 PCr/~ 'S91/03524
2~
200,000, preferably at least one million and more
preferably at least two million may be used in the
fabrication of layer or region 20. Such high ~olecular
weight polyethylene and polypropylene may be formed
into reasonably well oriented f$bers by the technigues
prescribed in the various references referred to above,
and especially by the technique of US Patent Nos.
4,413,110, 4,457,985 and 4,663,101 and preferable US
Patent No. 4,784,820. Since polypropylene is a much
less crystalline material than polyethylene and
contains pendant ~ethyl groups, tenacity values
achievable with polypropylene are generally
substantially lower than the corresponding values for
polyethylene. Accordingly, a suitable tenacity is at
least about 8 grams/denier,with a preferred tenacity
being at least about 11 grams/denier. The tensile
modulus for polypropylene is at least about 160
grams/denier, preferably at least about 200
grams/denier.
High molecular weight polyvinyl alcohol fibers
having high tensile modulus preferred for use in the
fabrication of layer 20 are described in USP 4,440,711
whieh is hereby incorporated by reference to the extent
it is not inconsistent herewith. In the case of
polyvinyl alcohol (PV-OH), PV-OH fiber of molecular
weight of at least about 200,000. Particularly useful
PV-OB fiber should have a ~odulus of at least about 300
g/denier, a tenacity of at least about 7 g/denier
tpreferably at least about 10 g/denier, more preferably
at about 14 g/denier, and most preferably at least
about 17 g/denier), and an energy to break of at least
about 8 joules/g. P(V-OH) fibers having a weight
a~erage ~olecular weight of at least about 200,000, a
tenacity of at least about 10 g/denier, a modulus of at
least about 300 g/denier, and an energy to break of
.... . . . . .
,:
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wo 92/09861 PCr/l 'S91/03524
2 0 ~ r ~
21
about 8 joules/g are more useful in producing a
ballistic resistant article. P(V-OH) fiber having such
properties can be produced, for example, by the process
disclosed in US Patent No. 4,599,267.
In the case of polyacrylonitrile (PAN), PAN fiber
for use in the fabrication of layer or region 20 are of
molecular weight of at least about 4000,000.
Particularly useful PAN fiber should have a tenacity of
at least about 10 g/denier and an energy-to-break of at
least about 8 joule/g. PAN fiber having a molecular
weight of at least about 4000,000, a tenacity of at
least about 15 to about 20 g/denier and an
energy-to-break of at least about 8 joule/g is most
useful in producing ballistics resistant articles; and
such fibers are disclosed, for example, in US
4,535,027.
In the case of aramid fibers, suitable aramid
fibers for use in the fabrication of layer or region 20
are those formed principally from aromatic polyamide
are described in US Patent No. 3,671,542, which is
hereby incorporated by reference. Preferred aramid
fiber will have a tenacity of at least about 20 g/d, a
tensile modulus of at least about 400 g/d and an
energy-to-break at least about 8 joules/gram, and
particularly preferred aramid fibers will have a
tenacity of at least about 20 g/d, a modulus of at
least about 480 g/d and an energy to break of at least
about 20 joules/gram. Most preferred aramid fibers
will have a tenacity of at least about 20 g/denier, a
modulus of at least about 900 g/denier and an
energy-to-break of at least about 30 joules/gram. For
example, poly(phenylenediamine terephalamide) fibers
produced commercially by Dupont Corporation under the
trade name of Kevlar~ 29, 49, 129 and 149 and having
moderately high moduli and tenacity values are
- . : , . ,
,, , j., ~ , ,
''~
,
w092/0986l PCT/US91/035~
~ 9 ~ 3 ~ 6
particularly u~eful i~ forming ballistic re~stant
compositss. Also useful in the practice of this
invention is poly(metaphenylene isophthalamide) fibers
produced commercially by Dupont under the trade name
Nomexs.
In the more preferred embodiments of this
invention, region or layer 20 of vibration isolating
layer 14 is formed of fibQrs arranged in a networ~
which can have various configurations. For example, a
plurality of filaments can be grouped together to form
a twisted or untwisted yarn bundles in various
alignment. The fibers or any may be formed as a felt,
knitted or woven (plain, basket, satin and crow feet
weaves, etc.) into a network, fabricated into non-woven
fabric, arranged in parallel array, layered, or formed
into a woven fabric by any of a variety of conventional
techniques. Among these techniques, for ballistic
resistance applications we prefer to use those
variations commonly employed in the preparation or
aramid ~abrics for ballistic-resistant articles. For
example, the techniques described in U.S. Patent No.
4,181,768 and in M.R. Silyquist et al., J. Macromol
Sci. Chem., A7(1), pp. 203 et. seq. (1973) are
particularly suitable. In preferred embodiments of the
2S invention, the filaments are aligned substantially
parallel and undirectionally to form a uniaxial layer.
Two or more of these layers can be used to form a layer
20 with multiple layers of coated undirectional
filaments in which each layer is rotated with respect
to its ad~acent layers. An example is a with the
second, third, fourth and fifth layers rotated +45, .-
-45, 90 and 0 with respect to the first layer, but
not necessarily in that order. Other examples include
a layer 20 with a 0/90 layout of yarn or filaments.
In the most preferred embodiments of this
,- , . ~ .
.:, ' '~ :, . ' : '
WO 92/0986 I PC~/ ~S9l/035~
2 0 ~ 6
23
invention, layer 20 is composed by one or more layers
of continuous fibers embedded in a continuous phase of
an elastomeric matrix material which pre~erably
substantially coats each fiber contained in the bundle
of fibers. The manner in which the fibers are
dispersQd may vary widely. The fibers may be aligned
in a substantially parallel, unidirectional ~ashion, or
fibers may be aligned in a multidirectional fashion, or
with fibers at varying angles with each other. In
preferred embodiments of this invention, fibers in each
layer forming layer 20 are aligned in a substantially
parallel, unidirectional fashion such as in a prepreg,
pultruded sheet and the like.
Wetting and adhesion of fibers in the polymer or
matrices, is enhanced by prior treatment of the surface
of the fibers. The method of surface treatment may be
chemical, physical or a combination of chemical and
physical actions. Examples of purely chemical
treatments are used of S03 or chlorosulfonic acid.
Examples of combined chemical and physical treatments
are corona discharge treatment or plasma treatment
using one of several commonly available machines.
The matrix material is a low modulus elastomeric
material. A wide variety of elastomeric materials and
formulation may be utilized in the preferred
e~bodiments of this invention. Representative examples
of suitable elastomeric materials for use in the
forma~ion of the matrix are those which have their
structures, properties, and formulation together with
cross-linking procedures summarized in the Encyclopedia
of Polymer Science, Volume 5 in the section
Elastomers-Synthetic (John Wiley & Sons Inc., 1964).
For example, any of the following elastomeric materials
may be employed: polybutadiane, polyisoprene, natural
rubber, ethylene-propylene copolymers,
,. . .
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' . ' ' " ' , ' :. ,
WO92/~)9X6l PCT/US91/03
Q9~ ~6 24
ethylene-propylene-dien terpolymers, polysulflde
polymers, polyurethane elastomers, chlorosulfonated
polyethylene, polychloroprene, plasticized
polyvinylchloride using dioctyl phthate or other
plasticers well known in the art, butadiene
acrylonitrile elastomers,
poly(i~obutylene-co-isoprene), polyacrylates,
polyesters, unsaturated polyesters, vinyl esters,
polyethers, fluoroelastomers, silicone elastomers,
thermoplastic elastomers, and copolymers of ethylene.
Particularly useful elastomers are polysulfide
polymers, polyurethane elastomers, unsaturated
polyesters vinyl esters; and block copolymers of
conjugated dienes such as butadiene and isoprene are
vinyl aromatic monomers such as styrene, vinyl toluene
and t-butyl styrene are preferred con~ugated aromatic
monomers. Block copolymers incorporating polyisoprene
may be hydrogenated to produce thermoplastic elastomers
having saturated hydrocarbon elastomer segments. The
polymeræ may be simple tri-block copolymers of the type
A-B-A, multiblock copolymers of the type (AB)n (n-2-10)
or radial configuration copolymers of the type R-(BA)x
(x-3-150); wherein A is 8 block from a polyvinyl
aromatic monomer and B is a block from a conjugated
dien elastomer. Many of these polymers are produced
commercially by the Shell Chemical Co. and described in
the bulletin "Kraton Thermoplastic Rubber", SC-68-81.
Most preferably, the elastomeric matrix material
consists essentially of at least one of the
above-mentioned elastomers. The low modulus
elastomeric matrixes may also include fillers such as
carbon black, glass microballons, and the like up to an
amount preferably not to exceed about 250% by volume of
the elastomeric material, more preferably not to exceed
about 100% by weight and most preferably not to exceed
, . . .
''
wos2/osx6l PCT/US91/03~
2 0 ~
about 50% by volume. The matrix material may be
extended with oils, may include fire retardants such as
halogenated parafins, and vulcanized by sulfur,
peroxide, metal oxide, or radiation cure ~ystems using
methods well ~nown to rubber technologists. Blends of
different elastomeric materials may be blended with one
or more thermoplastics. High density, low density, and
linear low density polyethylene may be cross-linked to
obtain a matrix material of appropriate properties,
either alone or as blends. In every instance, the
modulus of the elastomeric matrix material should not
exceed about 6,000 psi (41,300 kpa), preferably is less
than about 5,000 psi (34,500 kpa), more preferably is
less than 500 psi (3450 kpa).
In the preferred embodiments of the invention, the
matrix material is a low modulus, elastomeric material
has a tensile modulus, measured at about 23C, of less
than about 7,000 psi (41,300 kpa). Preferably, the
tensile modulus of the elastomeric material is less
than about 5,000 psi (34,500 kpa), more preferably, is
less than 1,000 psi (6900 kpa) and most preferably is
less tban about 500 psi (3,450 kpa) to provide even
more improved performance. The glass transition
temperature (Tg) of the elastomeric material (as
evidenced by a sudden drop in the ductility and
elasticity of the material) is less tban about 0C.
Preferable, tbe Tg of the elastomeric material is less
than about -40C, and more preferably is less than
about -50C. The elastomeric material also has an
elongation to break of at least about 50%. Preferably,
the elongation to break of the elastomeric material is
at least about 300%
The proportions of matrix to fiber in layer 20 may
vary widely depending on a number of factors including,
whether the matrix material has any ballis~ic-resistant
,...... . . . . .
. .
, . . . .
,: .: - , ', : ,
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w092/0986l PCT/~S91tO3~24
~,~9~16
26
properties of its own (which is generally not the case)
and upon the rigidity, shape, heat resistance, wear
resistance, flammability resistance and other
properties desired for layer 20. In general, the
proportion of matrix to fiber in layer 20 may vary from
relatively small amounts where the amount of matrix is
about 10% by volume of the fibers to relativQly large
amount where the amount of matrix iB Up to about 90% by
volume of the fibers. In the preferred embodiments of
this invention, matrix amounts of from about 15 to
about 80% by volume are employed. All volume percents
are based on the total volume of layer 20. ~n the
particularly preferred embodiments of the invention,
ballistic-resistant articles of the present invention,
layer 20 contains a relatively minor proportion of the
matrix (e.g., about 10 to about 30% by volume of
composite), since the ballistic-resistant properties
are almost entirely attributable to the fibers, and in
the particularly preferred embodiments of the
invention, the proportion of the matrix in layer 14 is
from about 10 to about 30% by weight of fibers.
Layer 20 can be fabricated using conventional
procedures. For example, in those embodiments of the
invention in which layer 20 is a woven fabric, layer 20
can be fabricated using conventional fabric weaving
techniques of the type commonly employed for ballistic
purposes such as a plain weave or a Panama weave. In
those embodiments of the invention in which layer 20 is
a network of fibers in a matrix, layer 20 is formed by
continuing the combination of fibers and matrix
material in the desired configurations and amounts, and
then subjecting the combination to heat and pressure.
For extended chain polyethylene fibers, molding
temperatures range from about 20 to about 150C,
preferably from about 80 to about 145C, more
- ' . ~ ,
.
w092/0986l PCT/US91~035~
2O9J81 6
27
preferably from about loo to about 135C, ~nd more
preferably from about 110 to about 130C. The pressure
may range from About lo psi (69 kpa to about lo,Ooo psi
(69,000 kpa). A pressure between about 10 psi (69 kpa)
and about loo psi (690 kpa), when combined with
temperatures below about 100 C for a period of ti~e
1QSS than about 1.0 min., may be used simply to cause
adjacent fibers to stick together. Pressures from
about 100 psi to about 10,000 psi (69,000 kpa), when
coupied with temperatures in the range of about 100 to
about 155C for a time of between about 1 to about 5
min., may cause the fibers to deform and to compress
together (generally in a film-like shape). Pressures
from about 100 psi (690 kpa) to about 10,000 psi
15 (69,000 kpa), when coupled with temperatures in the
range of about 150 to about 155C for a time of between
1 to about 5 min., may cause the film to become
translucent or transparent. For polypropylene fibers,
the upper limitation of the temperature range would be
about 10 to about 20-C higher than for extended chain
polyethylene fiber.
In the preferred embodiments of the invention, the
fibers (pre-molded if desired) are pre-coated with the
desired matrix material prior to being arranged in a
network and molded into layer 20 as described above.
The coating may be applied to the fibers in a variety
of ways and any method known to those of skill in the
art for coating fibers may be used. For example, one
method is to apply the matrix material to the stretched
high modulus fibers either as a liquid, a sticky solid
or particles in suspension, or as fluidized bed.
Alternatively, the matrix material may be applied as a
solution or emulsion in a suitable solvent which does
not adversely affect the properties of the fiber at the
temperature of application. In these illustrative
. .
. . .!.,,
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wos2/oss61 PCT/US91/035~
2 0~ ~a ~
28
embodiments, any liquid may be used. However, in the
preferred embodiments of the invention in which the
matrix material is an elastomeric material, preferred
groups of solvents include water, pararfin oils,
ketones, alcohols, aromatic solvents or hydrocarbon
solvents or mixtures thereof, with illustrative
specific solvents including paraffin oil, xylene,
toluene and octane. The techniques used to dissolve or
disperse the matrix in the solvents will be
those conventionally used for the coating of similar
elastomeric materials on a variety of substrates.
Other techniques for applying the coating to the fibers
may be used, including coating of the high ~odulus
precursor (gel fiber) before the high temperature
stretching operation, either before or after removal of
the solvent from the fiber. The fiber may then be
stretched at elevated temperatures to produce the
coated fibers. The gel fiber may be passed through a
solution of the appropriate matrix material, as for
example an elastomeric material dissolved in paraffin
oil, or an aromatic oraliphatic solvent, under
conditions to attain the desired coating.
Crystallization of the polymer in the gel fiber may or
may not have taken place before the fiber passes into
the cooling ~olution. Alternatively, the fiber may be
extruded into a fluidized bed of the appropriate matrix
material in powder form.
The proportion of coating on the coated fibers or
fabrics in layer 20 may vary from relatively small
amounts of (e.g. 1% by volume of fibers) to relatively
large amounts (e.g. 150% by volume of fibers),
depending upon whether the coating material has any
impact or ballistic-resistant properties of its own
(which is generally not the case) and upon the
rigidity, shape, heat resistance, wear resistance,
.
.
: . .: ::
' .
Wo92/098hl PCT/US91/035~
2~781 6
flammability resistance and other properties desired
for the complex composite article. In general, layer
20 containing coated fibers should hsve a relatively
minor proportion of coating (e.g. about 10 to about 30
percent by volume of fibers), since the
ballistic-resistant properties of layer 20 are almost
entirely attributable to the fiber. Nevertheless,
coated fibers with higher coating contents may be
employed. Generally, however, when the coating
constitutes greater than about 60% (by volume of
fiber), the coated fiber are consolidated with similar
coated fibers to form a fiber layer without tXe use of
additional matrix material.
Furthermore, if the fiber achieves its final
properties only after a stretching operation or other
manipulative process, e.g. solvent exchanging, drying
or the like, it is contemplated that the coating may be
applied to a precursor material of the final fiber. IN
such cases, the desired and preferred tenacity, modulus
and other properties of the fiber should be judged by
continuing the manipulative process on the fiber
precursor in a manner corresponding to that employed on
the coated fiber precursor. Thus, for example, if the
coating is applied to the xerogel fiber described in US
25 No. 4,537,296 and the coated xerogel fiber is then
stretched under defined temperature and stretch ratio
conditions, then the fiber tenacity and fiber modulus
values would be measured on uncoated xerogel fiber
which is similarly stretched.
It is a preferred aspect of the invention that
each fiber be substantially coated with the matrix
material for the production of layer 20. A fiber is
substantially coated by using any of the coating
processes described above or can be substantially
coated by employing any other process capable of
.
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,
,
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w092/0986l PCT/US91/035~
2~9~8~6
producing a fiber coated essentially to the ~a~e degree
as a flber coated by the processes described heretofore
(e.g., by employing known high pressure molding
techniques).
The fibQr~ and networks produced therefrom are
formed into "simple composites" as the prQcursor to
preparing the complex composite articles of the prQsent
invention. The term, "simple composite", a8 u~ed
herein is intended to mean composites made up of one or
more layers, each of the layers containing fibers as
describsd above with a single major matrix material,
which material may include minor proportions of other
materials such as fillers, lubricants or the like as
noted heretofore.
T~e proportion of elastomeric matrix material to
fiber is variable for the simple composites, with
matrix material amounts of from about 5% to about 150
vol %, by volume of the fiber, representing the broad
general range. Within this range, it i8 preferred to
use compositQs having a relatively high fiber content,
such as composites having only about lO to about 50 vol
% matrix material, by volume of the composite, and more
preferably from about 10 to about 30 vol S matrix
material by volume of the composite.
Stated another way, the fiber network occupies
different proportions of the total volume of the simple
composite. Preferably, however, the fiber network
comprises at least about 20 volume percent of the
simple composite. For ballistic protection, the fiber
network comprises at least about 50 volume percent,
more preferably about 70 volume percent, and most
preferably at least about 95 volume percent, with the
matrix occupying the remaining volume.
A particularly effective technique for preparing a
preferred composite of this invention comprised of
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. .
W O 92/09861 P ~ /~'S91/03524
209~1 6
31
substantially parallel, undirectionally aligned fibers
includes the 6teps of pulling a fiber through a bath
containing a solution of a matrix material preferably,
an elastomeric matrix material, and circumferentially
winding this fiber into a single sheet-like layer
around and along a fiber the length of a ~uitable form,
such as a cylinder. The solvent is then evaporated
leaving a sheet-like layer of fibers embedded ~n a
matrix that can be removed from the cylindrical form.
Alternatively, a plurality of fibers can be
simultaneously pulled through the bath containing a
solution or dispersion of a matrix material and laid
down in closely positioned, substantially parallel
relation to one another on a suitable surface.
Evaporation of the solvent leaves a sheet-like layer
comprised of fibers which are coated with the matrix
material and which are substantially parallel and
aligned along a common fiber direction. The sheet is
suitable for subsequent processing such as laminating
to another sheet to form composites containing more
than one layer.
Similarly, a yarn-type simple composite can be
produced by pulling a group of fiber bundles through a
dispersion or solution of the matrix material to
substantially coat each of the individual fiber in the
fiber, and then evaporating the solvent to form the
coated yarn. The yarn can then, for example, be
employed to form fabrics, which in turn, can be used to
form more complex composite structures. Moreover, the
coated yarn can also be processed into a simple
composite by employing conventional filament winding
techniques; for example, the simple composite can have
coated yarn formed into overlapping fiber layers.
The number of layers of fibers included in layer
20 may vary widely. In general, the greater the number
.
.
w092/0986l PCT/US91/035~
20~3~
32
of layers the greater the degree of ballistic
protection provided and conversely, the lesser the
number of layers the lesser the degree o~ ballistic
protection provided.
s one preferred configuration of layer 20 is a
laminate in which one or more layers of fibers coated
with matrix material (pre-molded if desired) are
arranged in a sheet~ e array and aligned parallel to
one another along a common fiber direction. Successive
layers of such coated unidirectional fibers can be
rotated with respect to the previous layer after which
the laminate can be molded under heat and pressure to
form the laminate. An example of such a layered
vibration isolating layer is the layered structure in
which the second, third, fourth and fifth layar are
rotated 45, 45, 90 and 0 with respect to the first
layer, but not necessarily in that order. Similarly,
another example of such a layered layer 20 is a
layered structure in which the various unidirectional
layers forming layer 20 are aligned such that the
common fiber axis is adjacent layers is 0, 90.
As depicted in FIG. 1, vibrating isolating layer
14 includes two surfaces regions or layers 22 and 24
which, in the embodiments of FIG. 1, are adjacent
impact layer 12 and bac~ing layer 16, respectively, and
which sandwich layer 20. Layers or regions 22 and 24
function to improve the overall performance of
vibration isolating layer 14 by improving the surface
characteristics of vibrating isolating layer 14;
providing a surface on which ceramic bodies 18 can be
attached; and retaining dimensional stability (i.e.
flatness and straightness) of the surface of vibration
isolating layer 14 when subjected to severe impact
deformation. The construction of regions 22 and 24 and
the materials used in such construction are such that
.
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,
WO 92/09~61 PCr/US91/03~24
203~
the regions have a flexural modulus equal to or greater
than about 0.01 msi, an elongation at break equal to or
less than about 40S and a fracture toughness equal to
or greater thar. about lMPa.m~2. As a result of these
5 properties, undue deformation of the surface geometry
of vibration isolating layer 14 does not occur during
impact. In the preferred embodiments of the invention,
the flexural modulus of regions or layers 22 and 24 are
from about O.OS to about 100 msi, elongation at break
10 is equal to or less than about 30% and the fracture
toughness is equal to or qreater than about 5 MPa.m~/2.
In the more preferred embodiments of t~e invention, the
flexural modulus of regions or layers 22 and 24 are
from about 0.1 to about 80 msi, the elongation at break
15 is less than about 20% and the fracture toughness is
equal to or greater than about lOMPa.m~/2; and in the
most preferred embodiments of the invention the
flexural modulus is from about O.S to about 50 msi, the
elongation at break is equal to or less than about 10%
20 and the fracture toughness is equal to or greater than
about 15MPa.m1/2.
Any material which can provide the desired
flexural modulus, elongation-to-break and fracture
toughness can be used in the fabrication of layers or
25 regions 22 and 24. The materials used in the s
construction of layers 22 and 24 may vary widely and
may be metallic, semi-metallic material an organic
material and/or an inorganic material. Illustrative of
such materials are those described in G.S. Brady and
H.R. Clauser, Materials Handbook, 12th edition (1986).
Materials useful for fabrication of layers 22 and 24
include high modulus thermoplastic polymeric materials
such as polyamides as for example aramids, nylon-66,
nylon-6 and the like; polyesters such as polyethylene
terephthalate polytutylene terephthalate, and the like,
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.
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~092/09X6l PCT/~S91/03524
~, o 9 ~ 6
34
polyacrylates, acetalo; polysulfones;
polyethersulfones; polyacrylates; polydienes,
acrylonitrile/butadiene/styrene copolymers;
poly(amide-amide); polycarbonates; polyarylates,
polyphenylenesulfides; polydienes, polyurethanes,
polyphenyleneoxides; polyestercarbonates;
polyesterimides; polyamides; and polyetheretherketone;
thermosetting material such as epoxy resins; phenolic
resins; vinyl ester resins; modified phenolic resins;
polyimides; unsaturated polyester; allylic resins,
alkyd resins; melamine and urea resins; allylic resins;
alkyd resins; melamine and urea resins; polymer alloys
and blends of thermoplastics and/or thermosets; and
interpertrating polymer networks such as those of a
thermosetting resin as for example polycyanate ester of
a polyol such as the dicyanoester of bisphenol-A and a
thermoplastic such as a polysulfone. These materials
may be reinforced by high strength filaments described
above for use in the fabrication of region or layer 20,
such as aramid fibers, boron fibers, S-glass fibers,
ceramic fibers, E-glass fibers, carbon and graphite
fibers, silicone carbide fibers, zirconia-silica
fibers, alumina-silica fibers and the like. Other
useful materials for the fabrication of layers 22 and
24 include non-shattering glass such as bullet proof
glass, and hardwood panels.
In the preferred embodiments of the invention,
layers 22 and 24 are formed from thermosetting resins
or blends of thermosetting resins and thermoplastic
resins preferably filled with inorganic, non-metallic
fibers such as carbon, boron, graphite, 52-glass,
-E-glass, S-glass and the like.
At their contact points, constituent layers 20, 22
and 24 are bonded together with a suitable agent such
as an adhesive described above for attachment of
~"
w(>s2/0986l PCT/US91/03~
20 ~31 ~
ceramic bodies 12 to vibrating isolating layer 14 as
for example a polysulfide or an epoxy.
In t~e composite 10, backing layer 16 is of double
layers construction, layers 26 and 28. However, it
should be appreciated that the number of individual
layers forming layer 16 is not critical and any number
of layers can be employed to provide the desired
results.
Backing layer 16 is comprised of a rigid ballistic
material which may vary widely depending on the uses of
article 10, and may offer additional ballistic
protection. The term "rigid" as used in the present
specification and claims is intended to include
semi-flexible and semi-rigid structures that are not
capable of being free standing, without collapsing.
The backing material employed may vary widely and may
be metallic, semi-metallic material, an organic
material and/or an inorganic material. Illustrative of
such materials are those described in G.S. Brady and
H.R. Clauser, Materials Handbook, 12th edition (1986).
Materials useful for fabrication of backing layer 16
include high modulus polymeric materials such as
polyamides as for example Aramids, nylon-66, nylon-6
and the like; polyesters such as polyethylene
terephthalate polybutylene terephthalate, and the like,
acetalo; poylsulfones; polyethersulfones;
polyacrylates; acrylonitrilelbutadienejstyrene
copolymers; poly(amide-imide); polycarbonates;
polyphenylenesulfides; polyurethanes,
polyphenyleneoxides; polyester carbonates;
polyesterimides; polyimides; polyetheretherketone;
epoxy resins; phenolic resins; polysulfides; silicones;
polyacrylates; polyacrylics; polydienes; vinyl ester
resins; modified phenolic resins; unsaturated
polyester; allylic resins; alkyd resins; melamine and
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.
W092/~)9~6l PcT/~ssl/o3s24
2 0 ~ 6
36
urea resins; polymer alloys and blends of
thermoplastics and/or thermosets of the materials
described above; and interpenetrating polymer networks
such as those of polycyanate ester of a polyol such as
the dicyanoester of bisphenol-A and a thermoplastic
such as a polysulfone. These materials may be
reinforced by high strength fibers describsd above for
use in the fabrication of vibration isolating layer 14,
such as aramid fibers, Spectra~ polyethylene fibers,
boron fibers, glass fibers, ceramic fibers, carbon and
graphite fibers, and the like.
Useful backing materials also include metals such
as nickel, manganese, tungsten, magnesium, titanium,
aluminum and steel plate. Illustrative of useful
steels are carbon steels which include mild steels of
grades AISI 1005 to AISI 1030, medium-carbon steels of
grades AISI 1030 to AISI 1055, high-carbon steels of
the grades AISI 1060 to AISI 1095, free-machining
steels, low-temperature carbon steels, rail steel, and
superplastic steels; high-speed steels such as tungsten
steels, molybdenum steels, chromium steels, vanadium
steels, and cobalt steels; hot-die steels; low-alloy
steels; low-expansion alloys; mold-steel; nitriding
steels for example those composed of low-and
~edium-carbon steels in combination with chromium and
aluminum, or nickel, chromium, and aluminum; silicon
steel such as transformer steel and silicon-manganese
steel; ultrahigh-strength steels such as medium-carbon
low alloy steels, chrominum-molybdenum steel,
chromium-nickel-molybdenum steel, iron-chromium-
molybdenum-cobalt steel, quenched-and-tempered steels,
cold-worked high-carbon steel; and stainless steels
such as iron-chromium alloys austenitic steels, and
choromium-nickel austenitic stainless steels, and
chromium-manganese steel. Useful materials also
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~'092/09X6l PCT/~S91/03524
2 ~ 6
37
include alloys such as manganese alloys, such as
manganese aluminum alloy, manganese bronze alloy;
nic~el alloys such as, nickel bronze, nickel cast iron
alloy, nic~el-chromium alloys, nickel-chromium steel
alloys, nickel copper alloys, nickel-molydenum iron
alloys, nickel-molybdenum steel alloys, nickel-silver
alloys, nickel-steel alloys;
iron-chromium-molybdenum-cobalt steel alloys; magnesium
alloys; aluminum alloys such as those of aluminum alloy
1000 series of commercially pure aluminum,
aluminum-manganese 8110ys of aluminum alloy 300 series,
aluminum-magnesium-manganese alloys, aluminum-
magnesium alloys, aluminum-copper alloys,
aluminum-silicon-magnesium alloys of 6000 series,
aluminum-copper-chromium of 7000 series, aluminum
casting alloys; aluminum brass alloys and aluminum
bronze alloys. Still other materials useful in the
fabrication of backing layer 16 are the fiber
composites used in the fabrication of vibration
isolating layer 14 which comprises fibrous network in a
rigid matrix. Yet, other materials useful in the
fabrication of backing layer 16 are non-shattering -
glass such as bulletproof glass.
FIG 2 shows a variant of the embodiment of FIG 1,
which is indicated at 30, corresponding parts being
referred to by like numerals. In composite 30, ceramic
impact layer 10 is covered with cover layer 32 which .
functions as an anti-spall layer to retain spall or
particles resulting from the shattering of ceramic
bodies 18 by the striking projectile, and which
functions to maintain ceramic bodies 18 which are not
hit by the projectile in position. In FIG 2, cover
layer 32 consists of top cover 36 and release layer 38.
Top cover 36 is formed from a rigid material as for
example the metals and non-metals described above for
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w092/os861 pc~/~ss1/o3s24
,Q~6 38
use in the fabrication of bac~ing layer 16 and is
preferably composed of a metal such as steel, titanium
and aluminum alloys, or of a rigid high strength
polymeric composite such as a thermoplastic resin such
as a polyurethane, polyester or polyamide, a
thermosetting resin such as epoxy, phenolic or
vinylester resin or a mixture thereof reinforced with
polymeric filaments such as aramid or extended chain
polyethylene or inorganic filaments such as S-glass
fibers, silicon carbide fibers, E-glass fibers, carbon
fibers, boron fibers and the like. Release layer 38 is
formed from materials similar to those used to form
vibration isolating layer 14 and functions to eliminate
or to substantially reduce the strain on unhit ceramic
bodies 18 in the deformation of the composites from
impact by the projectile. The construction of
vibration isolating layer 14 and backing layer 16 in
composite 30 and their materials of construction are
the same as in composite 10 of FIG 1.
FIG 3 depicts composite 40, which is a variation
of the embodiment of FIG 1, corresponding parts being
referred to by like numerals. Composite 40 includes
ceramic body retaining means 42 between individual
ceramic bodies 18 and peripheral impact layer retaining
means 44. Ceramic body retaining means 42 reduces the
differences in performance of segmented ceramic impact
layer 12 at the seams formed by adjacent ceramic bodies
18 which is usually a weak area, and at t~e center of
ceramic body 18 which is usually a strong area.
Ceramic body retaining means 42 also allows maximum
loading of ceramic bodies 18 in segmented ceramic
impact layer 12, provides optimized spacing between
adjacent ceramic bodies 18 retains unhit ceramic bodies
18 in place upon severe impact deformation, and
35 transmitts and distributes the impact shock to the --
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'
WO 92t09~61 PCr/US91/03524
209~81 ~
39
entire co~posite 40 upon impact. Peripheral impact
layer retaining means 44 minimizes the differences in
the performance at the edges of the composite armor
(which because o~ the segmented nature of the ceramic
impact layer 14 tends to be a relatively weaX area) and
at the center of the ceramic which tends to be a
rolatively strong area.
Ceramic body retaining means 42 and per~pheral
impact layer retaining means 44 are composed of an
"elastic" material which may vary widely and be
metallic, semi-metallic material, an organic material
and/or an inorganic material. The term "elastic" as
used in the present specification and claims is
intended to include materials inherently capable of
free standing without collapsing. Illustrative of such
materials are those describQd in G.S. Brady and H.R.
Clauser, Materials Handbook, 12th Edition (1986). Also
illustrative useful materials suitable for use in the
fabrication of ceramic body retaining means 42 and
peripheral impact layer retaining means 44 are those
materials described herein abovefor use in the
fabricaton of the backing layer 16 and cover layer 34. -
ThesQ materials include in the embodiments of FIGs. 1,
2 and 3 high modulus polymeric materials with or
without fibrous fillers such as a thermo~etting or
thermoplastic resin such as a polycarbonate or epoxy
which is optionally reinforced by high strength
filaments ouch as aramid filament, Spectra extended
chain polyethylene filaments, boron filament, gla~s
Silaments, ceramic filaments, carbon and graphite
fila~ent, and the like; metals and metal alloys such as
nickel, manganese, tungsten, magnesium, titanium,
aluminum, steel, manganese alloy~, nickel alloys,
magnesium alloys, and aluminum alloys with or without
creramic fillers such as silicone carbide; and
WO 92/~)9861 PCI/l,iS91/03;2~
non-shattering glass such as bulletproo~ glas~described
above. The construction of vibration isol~ting layer
14 and backing layer 16 in composite 40 and their
mateials of construction are the same as in composite
20 of FIG 2.
Complex ballistic articles of this invention have
many uses. For example, such composites may be
incorporated into more complex composites to provide a
rigid complex composite article suitable, for example,
as structural ballistic-resistant components, such as
helmets, structural members of aircra~t, and vehicle
panels.
The following examples are presented to provide a
more complete understanding of the invention. The
specific techniques, conditions, materials,proportions
and reported data set $orth to illustrate the
principles of the invention are exemplary and should
not be construed as limiting the scope of the
invention.
~X~MPLE I
Eight layers of 16" (40.6 cm) x 16" (40.6 cm)
Spectra Fabric (of the style 952 plain 65 d~ stitched
together with a Spectra~ 1000 polyethylene fiber were
placed between two pieces of 1/32" (0.08 cm) thin glass
reinforced epoxy plastic sheet (sold by Ryerson
Plastics under the trade name GP0-2Grade PEF 2002).
The sandwich is placed in a mold. A mixture (100
grams) of a vinyl ester resin tVE 8520 sold by
Interplastics), a peroxide (Benzoate Peroxide) sold by
Lucidol under the tradename Luperco AFR-400) and a
promoter (N,N-dimethyl aniline) was poured in the mold
until the sandwich surface was completely covered. The
composition of the mixture of vinyl ester
resin/peroxide/promoter is 10/0.1/0.006. The material
was cured for two hours at room temperature under
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wos2/osx6l PCT/US91/03524
20~J81 ~
41
pressure. The thickness of the cured material was
about 1/8" (0.32 cm).
Exam~le 2
A panel consisting of a 4 by 24 checker board with
square cells of dimensions of 4" (10.2cm) by 4"
(10.2cm) by 1/2" (1.3 cm) depth was constructed. The
cells of panel were filled with marbl2 tiles. The
panel was constructed on a Spectra~ composite of
Example l. The checker board was placed into a 16"
(40.6 cm) by 16" (40.6 cm) by l/2" (1.3 cm) aluminum
frame, and was covered with a piece of l/8" (0.32 cm)
thick polycarbonate. The whole unit was mounted on a
1/4" (0.64 cm) thick steel plate (A~ 400 sold by
Ryerson Aluminum and Steel Company), and the entire
arrangement was consolidated into a single unit with
the thermosetting vinyl ester resin mixture used in
Example 1. After the first shot at the center of tile,
9 neighboring tiles at the point of impact remained
undamaged. Thus, the efficiency was 100%. After 5
bullets were shot at a speed of 3100 ft/sec (944.9
m/sec) at the center of the tiles, ll tiles were
retained. Among these, 9 were undamaged and 2 were
slightly cracked. However, 9 out of 9 of these
undamaged tiles were neighboring tiles. Therefore, the
efficiency remained 100% after 5 hits. Furthermore,
the somposite remained flat and straight even though
the steal backing plate had buckled after 5 hits.
Commarative ExamDle 1
A panel was constructed using the same procedure
described in Example 2 with the exception that the
Spectra composite was not included. The panel was
tested under the same conditions. After the first shot
at the center of tile, no neighboring tiles at the
point of impact remained undamaged. Thus, the
efficiency is 0%. After 5 hits, all tiles had
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WO 92/0986 1 ~CI /US91 /03524
2 n (~ r~
shattered. The efficiency remained OS after 5 hits.
Comparative Example 2
A panel was constructed using the same procedure
described in Example 2 except that a known vibration
and shock isolation material - fèlt replaced the
Spectra composite sandwich. ~he felt used w~s a 1/8"
(0.32 cm) think 100% dense wool pad (sold by
McMaster-Carr under the trade name of 8757K1 with a
weight of 1.53 lbs/sq.yd). The s~mple was tested under
the same conditions described in Example 2. After the
first shot at the center of tile, 2 out of 9
meighboring tiles at the point of impact remained
undamaged. Thus, the efficiency was 22%. After 5
hits, S tiles were retained but they were slightly
cracked. Therefore, the efficiency was 0% after 5 hits.
The other tiles were all shattered. The piece of felt
used was torn into pieces after 5 shots.
Comparative Example 3
A panel was constructed using the same procedure
as Example 2 except that a 1/8" (0.32 cm) thick glass
reinforced epoxy composite (GRP) replaced the Spectra
composite. This GRP is sold by Ryerson Plastics under
the trade name Ryertex G-10 PHPP4008. The sample was
tested under the same conditions as described in
Example 2. After the first shot at the center of tile,
1 out of 9 neighboring tiles at the point of impact
remained undamaged. Thus the efficiency was 10%.
After 5 hits, 2 tiles were retained but were damaged.
The remaining tiles were shattered. Therefore, the
efficiency was 0% after 5 hits. The GRP was badly
damaged after 5 shots.
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