Penetration and blast resistant composites and articles

A flexible composite of manufacture especially suitable for use as a ballistic resistant body armor. An improved penetration resistant composite of the type comprising at least one substrate layer having one or more planar bodies affixed to a surface thereof, the improvement comprising laminated planer bodies comprising at least two layers, at least one or said layers being a metal layer positioned on the impact side of said bodies exposed to said threat and at least one of said layers being a fibrous layer comprising a fiber network in a polymeric matrix.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to composites and articles fabricated therefrom. 
More particularly, this invention relates to composites and articles 
having improved blast and penetration protection. 
2. Prior Art 
Ballistic articles such as bulletproof vests, helmets, structural members 
of helicopters and other military equipment, vehicle panels, briefcases, 
raincoats and umbrellas containing high strength fibers are known. 
Illustrative of such articles are those described in U.S. Pat. Nos. 
4,623,574; 4,748,064; 4,413,110; 4,737,402; 4,613,535; 4,650,710; 
4,737,402; 4,916,000; 4,403,012, 4,457,985; 4,737,401; 4,543,286; 
4,5143,392 and 4,501,856. 
SUMMARY OF THE INVENTION 
The present invention provides a composite exhibiting resistance to 
penetration by a threat, said composite comprising at least two layers, at 
least one of said layers being a layer comprised of a metal, a 
metal/ceramic composite or a combination thereof ("metal layer") 
positioned on the impact side of said composite exposed to a said threat 
and at least one of said layers being a fibrous layer comprising a fiber 
network in a polymeric matrix position and on the non-impact side of said 
metal layer, wherein the relative weight percent of said metal layer and 
said fibrous layer are selected such that the penetration resistance of 
said composite to high and/or low length to diameter (L/D) threats at some 
angle of incidence is greater than the additive effects of said layers 
expected from the rule of mixtures. Another embodiment of this invention 
relates to an article of manufacture comprising a body all or a portion of 
which is constructed from the composite of this invention, as for example 
a helmet. Yet another aspect of this invention relates to an improved 
penetration resistant composite of the type comprising at least one 
substrate layer having one or more rigid planar "penetration resistant" 
bodies affixed to a surface thereof, the improvement comprising bodies 
comprising at least two layers, at least one of said layers being a layer 
comprising a metal, a metal/ceramic composite or a combination thereof 
positioned on the impact side of said layer and at least one of said 
layers being a fibrous layer comprising a fiber network in a polymer 
matrix, wherein the relative weight percent of said metal and fibrous 
layers are selected such that the penetration resistance of said bodies to 
high and/or low L/D threats at some angle of incidence is greater than the 
additive effects of said layers expected from the rule of mixtures, and 
articles manufactured therefrom. 
Several advantages flow from this invention. For example, the composite and 
article of this invention provides a higher degree of penetration 
resistance than composites and articles of the same areal density 
constructed solely of planar bodies constructed from the metal layer or 
the fibrous layer. As used herein, the "penetration resistance" of the 
article is the resistance to penetration by a designated threat, as for 
example, a bullet, an ice pick, shrapnel, fragments, or a knife; or the 
blast of an explosion or the like. The penetration resistance can be 
expressed as the total specific energy absorption (SEAT) which is the 
kinetic energy of the threat at its V.sub.50 value divided by the areal 
density of the composite and the higher the SEAT valve, the greater the 
resistance of the composite to the threat and, as used herein, the "areal 
density" or "ADT" is the ratio of total target weight to the area of the 
target strike face area and as used herein, "V.sub.50 " of a threat is the 
velocity at which 50% of the threats will penetrate the composite while 
50% will be stopped. As used herein, "angle of incidence of said threat" 
is the angle formed at the point at which the threat strikes the surface 
of the composite between the linear path traveled by the threat just 
before it strikes the surface and the path normal to that surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The preferred invention will be better understood by those of skill in the 
art by reference to the above figures. The preferred embodiments of this 
invention illustrated in the figures are not intended to be exhaustive or 
to limit the invention to the precise form disclosed. It is chosen to 
describe or to best explain the principles of the invention and its 
application and practical use to thereby enable others skilled in the art 
to best utilize the invention. 
Referring to FIG. 1 the numeral 10 indicates a blast and penetration 
resistant composite 10. The construction of composite 10 is critical to 
the advantages of this invention. As depicted in FIG. 1, composite 10 has 
a layered construction and has two essential layers. On the impact side of 
composite 10 is a metal layer 12 and positioned on the non-impact side is 
a fibrous layer 14 comprising a fibrous network in a polymeric matrix. In 
FIG. 1, layers 14 and 14 are laminated or bonded together. However, this 
constitutes only the preferred embodiments of the invention, since the 
only requirement is the positioning of the layers. In these preferred 
embodiments, layer 12 and layer 14 may be bonded together using any 
conventional bonding means for bonding a metal layer to a polymer 
composite. Illustrative of suitable bonding means are adhesives, bolts, 
rivets, screws, mechanical interlocks and the like. Layers 12 and 14 are 
preferably bonded together by adhesives or by bonding between metal layer 
12 and the polymer of fibrous layer 14. 
The relative weight percents of metal layer 12 and fibrous layer 14 may 
vary widely and are selected depending on the various needs of the user 
and depending on the whether the threat is a low or nigh length/diameter 
(L/D) threat or both of such threats. As used herein a "high L/D threat" 
is a threat in which the ratio of length to diameter is equal to or 
greater than about 4 to 1 (preferably equal to or greater than about 6 to 
1 and more preferably equal to or greater than about 7 to 1), and a "low 
L/D threat" is a threat in which the ratio of length to diameter is less 
than about 4 to 1 (preferably equal to or less than about 3 to 1). For 
example, various relative weight percents can be selected such that the 
penetration resistance of the composite for either high or low L/D threats 
is greater than that which would be expected based on the rule of 
mixtures. Similarly, various relative weight percents can be selected such 
that the penetration resistance of the composite of this invention for 
both high and low length/diameter (L/D) threats is greater than that which 
would be expected based on the rule of mixtures and that which would of 
the same areal density. In general, the relative weight percents of metal 
layer 12 and fibrous layer 14 is from about 2 wt. to about 98 wt. % based 
on the total weight of composite 10. In the preferred embodiments of the 
invention where higher penetration resistance against high L/D threats is 
desired, the weight percent of metal layer 12 is from about 20 to about 80 
and the weight percent of the fibrous layer 14 is from about 80 to about 
20; where higher penetration resistance against low L/D threats is desired 
the weight percents of metal layer 12 is from about 5 to about 140 and the 
weight percent of fibrous layer 14 is from about 40 to about 95; and where 
maximized penetration resistance against both low and high L/D threats is 
desired the weight percents of metal layer 12 is from about 15 to about 
140 and the weight percent of fibrous layer 14 is from about 40 to about 
85, based on the total weight of the composite 10. The weight percent of 
metal layer 12 is more preferably from about 30 to about 70 and weight 
percent of fibrous layer 14 is more preferably from about 30 to about 70 
based on the total weight of composite 10 where penetration resistance 
against relatively high L/D threats is desired; the weight percent of 
metal layer 12 more preferably from about 10 to about 50 and the weight 
percent of fibrous layer 14 is more preferably from about 50 to about 90 
where penetration resistance against relatively low L/D threats is 
desired; and the weight percent of metal layer 12 is more preferably from 
about 50 to about 20 and the weight percent of fibrous layer 14 is more 
preferably from about 50 to about 80 where maximum penetration resistance 
against both high and low L/D threats is desired, wherein weight percents 
are on the aforementioned basis. The weight percent of metal layer 12 is 
most preferably from about 50 to about 35 and the weight percent of 
fibrous layer 14 is most preferably from about 50 to about 145 where 
penetration resistance against high L/D threat is desired; the weight 
percent of metal layer 12 is most preferably from about 10 to about 30 and 
the weight percent of fibrous layer 14 is most preferably from about 70 to 
about 90 where penetration resistance against relatively low L/D threats 
is desired; and the weight percent of metal layer 12 is most preferably 
from about 40 to about 25 and the weight percent of fibrous layer 14 is 
most preferably from about 140 to about 75 where maximum penetration 
against both high and low L/D threats is desired on the aforementioned 
basis. 
The areal density of composite 10 is not critical and may vary widely. The 
areal density is preferably from about 3 to about 12 kg/m.sup.2, more 
preferably from about 4 to about 10 kg/m.sup.2 and most preferably from 
about 14 to about 8 kg/m.sup.2. 
Fibrous layer 14 comprises a network of fibers dispersed in a polymeric 
matrix. Fibers in fibrous layer 14 may be arranged in networks (which can 
have various configurations) which are embedded or substantially embedded 
in a polymeric matrix which preferably substantially coats each filament 
contained in the fiber bundle. The manner in which the fibers are 
dispersed or embedded in the polymeric matrix may vary widely. For 
example, a plurality of filaments can be grouped together to form a 
twisted or untwisted yarn bundles in various alignment. The fibers 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 or nonwoven fabric by 
any of a variety of conventional techniques and dispersed in the matrix 
employing any suitable technique as for example melt blending the fibers 
in a melt of the polymer, solution blending the fibers in a solution of 
the polymer followed by removal of the solvent and consolidation of the 
polymer coated fibers, polymerization of monomer in the presence of the 
fiber and the like. Among these techniques for forming fiber networks, for 
ballistic resistance applications we prefer to use those variations 
commonly employed in the preparation of aramid fabrics for 
ballistic-resistant articles. For example, the techniques described in 
U.S. Pat. No. 4,181,7148 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 invention, as depicted in FIG. 1, layer 14 is 
formed of a plurality of uniaxial layers 16 in which fibers are aligned 
substantially parallel and undirectionally such as in a prepreg, pultruded 
sheet and the like which are fabricated into a laminate fibrous layer 14 
comprised of a plurality of such uniaxial layers 16 in which polymer 
forming the matrix coats or substantially coats the filaments of 
multi-filament fibers and the coated fibers are arranged in a sheet-like 
array and aligned parallel to another along a common fiber direction. 
Successive uniaxial layers of such coated, uni-directional fibers can be 
rotated with respect to the previous layer to form a laminated fibrous 
layer 14. An example of such laminate fibrous layer 14 are composites with 
the second, third, fourth and fifth uniaxial layers are rotated 
+45.degree., -45.degree., 90.degree. and 0.degree., with respect to the 
first layer, but not necessarily in that order. Other examples include 
composites with 0.degree./90.degree. layout of fibers in adjacent uniaxial 
layers. The laminated fibrous layer 14 composed of the desired number of 
uniaxial layers 16 can be molded at a suitable temperature and pressure to 
form a layer 14 having a desired thickness which can be bonded to layer 12 
through use of a suitable bonding technique. Techniques for fabricating 
laminated layer 14 compose of a plurality of uniaxial layers and laminated 
layer 14 composed of a plurality of woven or nonwoven fabric layers are 
described in greater detail in U.S. Pat. Nos. 4,916,000; 4,650,710; 
4,681,792; 4,737,401; 4,543,286; 4,563,392; 4,501,856; 4,623,574; 
4,748,064; 4,457,985 and 4,403,012; and PCT WO/91/08895. In the preferred 
embodiments of the invention, fibrous layer 14 is composed of a plurality 
of uniaxial fibrous layers comprised of substantially parallel fibers in 
which fibers in adjacent uniaxial layers are aligned such that the fiber 
direction of fibers in adjacent layers are an angle preferably 
0.degree./90.degree.. 
The type of fibers used in the fabrication of layer 14 may vary widely and 
can be inorganic or organic fibers. For purposes of the present invention, 
fiber is defined as an elongated body, the length dimension of which is 
much greater than the dimensions of width and thickness. Accordingly, the 
term fiber as used herein includes a monofilament elongated body, a 
multifilament elongated body, ribbon, strip, and the like having regular 
or irregular cross sections. The term fibers includes a plurality of any 
one or combination of the above. Preferred fibers for use in the practice 
of this invention are those having a tenacity equal to or greater than 
about 7 g/d, (as measured by an Instron Tensile Testing Machine) a tensile 
modulus equal to or greater than about 40 g/d (as measured by an Instron 
Tensile Testing Machine) and an energy-to-break equal to or greater than 
about 8 joules/gram. All tensile properties are evaluated by pulling a 10 
in (25.4 cm) fiber length clamped in barrel clamps at a rate of 10 in/min 
(25.4 cm/min) on an Instron Tensile Tester. Particularly preferred fibers 
are those having a tenacity equal to or greater than about 10 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 20 g/d, the 
tensile modulus is equal to or greater than about 1000 g/d, and the 
energy-to-break is equal to or greater than about 35 joules/grams. In the 
practice of this invention, fibers of choice have a tenacity equal to or 
greater than about 25 g/d, the tensile modulus is equal to or greater than 
about 1300 g/d and the energy-to-break is equal to or greater than about 
40 joules/grams. 
The denier of the fiber may vary widely. In general, fiber denier is equal 
to or less than about 4000. In the preferred embodiments of the invention, 
fiber denier is from about 10 to about 4000, the more preferred 
embodiments of the invention fiber denier is from about 10 to about 1000 
and in the most preferred embodiments of the invention, fiber denier is 
from about 10 to about 400. 
The cross-section of fibers for use in this invention may vary widely. 
Useful fibers may have a circular cross-section, oblong cross-section or 
irregular or regular multi-lobal cross-section having one or more regular 
or irregular lobes projecting from the linear or longitudinal axis of the 
fibers. In the particularly preferred embodiments of the invention, the 
fibers are of substantially circular or oblong cross-section and in the 
most preferred embodiments are of circular or substantially circular 
cross-section. 
Useful inorganic fibers include S-glass fibers, E-glass fibers, carbon 
fibers, boron fibers, alumina fibers, zirconia silica fibers, 
alumina-silicate fibers and the like. 
Illustrative of useful organic filaments are those composed of aramids 
(aromatic polyamides), such as poly (metaphenylene isophthalamide) (Nomex) 
and poly (p-phenylene terephthalamide) (Kevlar); aliphatic and 
cycloaliphatic polyamides, such as the copolyamide of 30% hexamethylene 
diammonium isophthalate and 70% hexamethylene diammonium adipate, the 
copolyamide of up to 30% bis-(-amidocyclohexyl)methylene, terephthalic 
acid and caprolactam, poly(hexamethylene adipamide) (nylon 6,6), 
poly(butyrolactam) (nylon 4), poly (9-aminononanoic acid) (nylon 9), 
poly(enantholactam) (nylon 7), poly(capryllactam) (nylon 8), 
polycaprolactam (nylon 14), poly(hexamethylene sebacamide) (nylon 14,10), 
poly(aminoundecanamide) (nylon 11), poly[bis-(4-aminocyclothexyl) methane 
1,10-decanedicarboxamide] (Qiana) (trans), or combination thereof; and 
aliphatic, cycloaliphatic and aromatic polyesters such as 
poly(1,4-cyclohexlidene dimethyl eneterephathalate) cis and trans, 
poly(ethylene-1, 5-naphthalate), poly(ethylene-2,14-naphthalate), 
poly(ethylene terephthalate), poly(ethylene isophthalate), poly(ethylene 
oxybenzoate), poly(para-hydroxy benzoate). Also illustrative of useful 
organic fibers are those of liquid crystalline polymers such as lyotropic 
liquid crystalline polymers which include polypeptides such as 
poly-g-benzyl L-glutamate and the like; aromatic polyamides such as 
poly(1,4-benzamide), poly(chloro-1,4-phenylene terephthalamide), 
poly(1,4-phenylene fumaramide), poly(chloro-1,4-phenylene fumaramide), 
poly (4,4'-benzanilide trans, trans-muconamide), poly(1,4-phenylene 
mesaconamide), poly(1,4-phenylene) (trans-1,4-cyclohexylene amide), 
poly(1,4-phenylene 1,4-dimethyl-trans-1,4-cyclohexylene amide), 
poly(chloro-1,4-phenylene 2,5-pyridine amide), poly(chloro-1,4-phenylene 
4,4'-stilbene amide), poly(1,4-phenylene 4,4'-azobenzene amide), 
poly(4,4'-azobenzene 4,4'-azobenzene amide), poly(1,4-phenylene 
4,4'-azoxybenzene amide), poly(1,4-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(1,4-phenylene 4,4'-bibenzo 
amide), poly(1,4-phenylene 4,4'-terephenylene amide), poly(1,4-phenylene 
2,14-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 amide), poly( 
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-hydrazides) such as poly(terephthaloyl 
1,4 amino-benzhydrazide) and those prepared from 4-amino-benzhydrazide, 
oxalic dihydrazide, terephthalic dihydrazide and para-aromatic diacid 
chlorides; polyesters such as those of the compositions include 
poly(oxy-trans-1,4-cyclohexyleneoxycarbonyl-trans-1,4-cyclohexylenecarbony 
l-.beta.-oxy-1,4-phenyl-eneoxyterephthaloyl) and 
poly(oxy-cis-1,4-cyclohexyleneoxycarbonyl-trans-1,4-cyclohexylenecarbonyl- 
.beta.-oxy-1,4-phenyleneoxyterephthaloyl) in methylene chloride-o-cresol 
poly[(oxy-trans-1,4-cyclohexylene-oxycarbonyl-trans 
-1,4-cyclohexylenecarbonyl-.beta.-oxy-(2-methyl-1,4-phenylene)oxy-terephth 
aloyl)] in 1,1,2,2-tetrachloro-ethane-o-chlorophenol-phenol (140:25:15 
vol/vol/vol), 
poly[oxy-trans-1,4-cyclohexyleneoxycarbonyl-trans-1,4-cyclohexylenecarbony 
l-.beta.-oxy(2-methyl-1,3-phenylene)oxyterephthaloyl] in o-chlorophenol and 
the like: polyazomethines such as those prepared from 
4,4'-diaminobenzanilide and terephthaldehyde, methyl-1,4-phenylenediamine 
and terephthaldehyde 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 for example poly(n-butyl isocyanate), 
poly(n-hexyl isocyanate) and the like; lyotropic crystalline polymers with 
heterocyclic units such as poly(1,4-phenylene-2,14-benzobisthiazole) 
(PBT), poly(1,4-phenylene-2,14-benzobisoxazole) (PBO), 
poly(1,4-phenylene-1, 3,4-oxadiazole), poly(1,4-phenylene-2, 
14-benzobisimidazole), poly[2,5(14)-benzimidazole] (AB-PBI), poly 
[2,14-(1,4-phenylene)-4-phenylquinoline], 
poly[1,1'-(4,4'-biphenylene)-14,14'-bis(4-phenylquinoline)] and the like; 
polyorganophosphazines such as polyphosphazine, polybisphenoxyphosphazine, 
poly[bis(2,2,2' trifluoroethylene) 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 the presence of cuprous iodine and an amide; cellulose and 
cellulose derivatives such as esters of cellulose as for example 
triacetate cellulose, acetate cellulose, acetate-butyrate cellulose, 
nitrate cellulose, and sulfate cellulose, ethers of cellulose as for 
example, ethyl ether cellulose, hydroxymethyl ether cellulose, 
hydroxypropyl ether cellulose, carboxymethyl ether cellulose, 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 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 
14-hydroxy-2-naphthoic acid and p-hydroxy benzoic acid, copolymers of 
14-hydroxy-2-naphthoic acid, terephthalic acid and p-amino phenol, 
copolymers of 14-hydroxy-2-naphthoic acid, terephthalic acid and 
hydroquinone, copolymers of 14-hydroxy-2-naphtoic acid, p-hydroxy benzoic 
acid, hydroquinone and terephthalic acid, copolymers of 2,14-naphthalene 
dicarboxylic acid, terephthalic acid, isophthalic acid and hydroquinone, 
copolymers of 2,14-naphthalene dicarboxylic acid and terephthalic acid, 
copolymers of p-hydroxybenzoic acid, terephthalic acid and 
4,4'-dihydoxydiphenyl, copolymers of p-hydroxybenzoic acid, terephthalic 
acid, isophthalic acid and 4,4'-dihydroxydiphenyl, p-hydroxybenzoic acid, 
isophthalic acid, hydroquinone and 4,4'-dihydroxybenzophenone, copolymers 
of phenylterephthalic acid and hydroquinone, copolymers of 
chlorohydroquinone, terephthalic acid and p-acetoxy cinnamic acid, 
copolymers of chlorohydroquinone, terephthalic acid and ethylene 
dioxy-4,4'-dibenzoic acid, copolymers of hydroquinone, methylhydroquinone, 
p-hydroxybenzoic acid and isophthalic acid, copolymers of 
(1-phenylethyl)hydroquinone, terephthalic acid and hydroquinone, and 
copolymers of poly(ethylene terephthalate) and p-hydroxybenzoic acid; and 
thermotropic polyamides and thermotropic copoly(amide-esters). 
Also illustrative of useful organic fibers for use in the fabrication of 
layer 14 are those composed of extended chain polymers formed by 
polymerization of .alpha.,.beta.-unsaturated monomers such as polystyrene, 
polyethylene, polypropylene, polyacrylonitrile, poly(vinyl alcohol), and 
the like. 
In the most preferred embodiments of the invention, layer 14 includes a 
fibrous substrate network, which may include polyethylene fibers, 
polyester (e.g. poly(ethylene terephthalate) fibers, polyamide (e.g. nylon 
6, nylon 6,6, nylon 6,10 and nylon 11) fibers, aramid fibers, or mixtures 
thereof. U.S. Pat. No. 4,457,985 generally discusses such high molecular 
weight polyethylene and the disclosure of this patent is hereby 
incorporated by reference to the extent that it is not inconsistent 
herewith. In the case of polyethylene, suitable fibers are those of 
molecular weight of at least 150,000, preferably at least one million and 
more preferably between two million and five million. Such extended chain 
polyethylene (ECPE) fibers may be grown in solution as described in U.S. 
Pat. No. 4,137,394, or U.S. Pat. No. 4,3514,138, or fiber spun from a 
solution to form a gel structure, as described in German Off. 3,004,699 
and GB 2051667, and especially described in U.S. Pat. No. 4,551,296 (see 
EPA 144,1147, published Nov. 10, 1982). As used herein, the term 
polyethylene shall mean a predominantly linear polyethylene material that 
may contain minor amounts of chain branching or comonomers not exceeding 5 
modifying units per 100 main chain carbon atoms, and that may also contain 
admixed therewith not more than about 50 wt % of one or more polymeric 
additives such as alkene-1-polymers, in particular low density 
polyethylene, polypropylene or polybutylene, copolymers containing 
mono-olefins as primary monomers, oxidized polyolefins, graft polyolefin 
copolymers and polyoxymethylenes, or low molecular weight additives such 
as anti-oxidants, lubricants, ultra-violet screening agents, colorants and 
the like which are commonly incorporated by reference. Depending upon the 
formation technique, the draw ratio and temperatures, and other 
conditions, a variety of properties can be imparted to these fibers. The 
tenacity of the filaments should be at least 15 grams/denier (as measured 
by an Instron Testing Machine) preferably at least 20 grams/denier, more 
preferably at least 25 grams/denier and most preferably at least 30 
grams/denier. Similarly, the tensile modulus of the filaments, as measured 
by an Instron tensile testing machine, is at least 300 grams/denier, 
preferably at least 500 grams/denier and more preferably at least 1,000 
grams/denier and most preferably at least 1,200 grams/denier. These 
highest values for tensile modulus and tenacity are generally obtainable 
only by employing solution grown or gel fiber processes. 
In the case of aramid fibers, suitable aramid fibers formed principally 
from aromatic polyamide are described in U.S. Pat. No. 3,671,542, which is 
hereby incorporated by reference. Preferred aramid fiber will have a 
tenacity of at least about 20 g/d (as measured by an Instron Tensile 
Testing Machine), a tensile modulus of at least about 400 g/d (as measured 
by an Instron Tensile Testing Machine) 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(phenylene terephthalamide) fibers produced 
commercially by Dupont Corporation under the trade name of Kevlar 29, 49, 
129 and 129 having moderately high moduli and tenacity values are 
particularly useful in forming ballistic resistant composites. Also useful 
in the practice of this invention is poly(metaphenylene isophthalamide) 
fibers produced commercially by Dupont under the tradename Nomex. 
In the case of liquid crystal copolyesters, suitable fibers are disclosed, 
for example, in U.S. Pat. Nos. 3,975,487; 4,118,372; and 4,161,470, hereby 
incorporated by reference. Tenacities of about 15 to about 30 g/d (as 
measured by an Instron Tensile Testing Machine) and preferably about 20 to 
about 25 g/d, and tensile modulus of about 500 to 1500 g/d (as measured by 
an Instron Tensile Testing Machine) and preferably about 1000 to about 
1200 g/d, are particularly desirable. 
Layer 12 is formed of a metal or a metal composite. The metal and metal 
composites employed in the fabrication of layer 12 may vary widely. Useful 
metals include 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 
10140 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 steel, and cobalt 
steels; hot-die steels; low-alloy steels; low-expansion alloys; 
mold-steel; nitriding steels for example those composed of low-and 
medium-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, chromium-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 chromium-nickel austenitic 
stainless steels, and chromium-manganese steel. Useful materials also 
include alloys such a manganese alloys, such as manganese aluminum alloy, 
manganese bronze alloy; nickel alloys such as, nickel bronze, nickel cast 
iron alloy nickel-chromium alloys, nickel-chromium steel alloys, nickel 
copper alloys, nickel-molybdenum 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 alloys of aluminum alloy 300 series, 
aluminum-magnesium-manganese alloys, aluminum-magnesium alloys, 
aluminum-copper alloys, aluminum-silicon-magnesium alloys of 14000 series, 
aluminum-copper-chromium of 7000 series, aluminum casting alloys; aluminum 
brass alloys and aluminum bronze alloys. 
Useful metal composites include composites in which one of the 
aforementioned metals form the continuous matrix having dispersed therein 
one or more ceramic materials in any form as for example as short or 
continuous fibers or as low aspect ratio domains. Useful ceramic materials 
include metal and non-metal borides, carbides and nitrides such as silicon 
carbide, titanium carbide, iron carbide, silicon nitride and the like. 
In the preferred embodiments of this invention layer 12 is formed from a 
metal. Layer 12 is more preferably formed from titanium, steel and alloys 
thereof, aluminum and alloys thereof and combinations thereof and is most 
preferably form from titanium. 
Layers 12 and 14 can be bonded together by any suitable method known to 
those of skill in the art to bond a metal surface to a surface of a 
fibrous layer. Illustrative of useful bonding means are adhesives such as 
those described in R C Liable, "Ballistic Materials and Penetration 
Mechanics", Elsevier Scientific Publishing Co. (1980). Illustrative of 
other useful bonding means are bolts, screws, staples, mechanical 
interlocks, stitching or a combination thereof. In the preferred 
embodiments of the invention, layers 12 and 14 are bonded together by 
adhesives (especially polymeric adhesives) or by a polymer as for example 
the matrix polymer of layer 14. 
The composites of this invention can be used for conventional purposes. For 
example, such composites can be used in the fabrication of penetration 
resistant articles and the like using conventional methods. Such 
penetration resistant articles include meat cutter aprons, protective 
gloves, boots, tents, fishing gear and the like. 
The articles are particularly useful as a "bulletproof" vest material or 
ballistic resistant articles such as "bulletproof" lining for example, or 
a raincoat because of the flexibility of the article and its enhanced 
ballistic resistance. An example of such bullet proof vests is depicted in 
FIGS. 2 to 4. Referring to FIGS. 2 to 4, the numeral 18 indicates a blast 
and penetration resistant article fabricated in part from the composite of 
this invention, which in this preferred embodiments of the invention is 
ballistic resistant body armor. As depicted in FIGS. 3 and 4, article 18 
is comprised of one or more interior penetration resistant layers 20, one 
or more frontal layers 22 and one or more backing layers 24. At least one 
of layers 20 is comprised of a substrate layer 214 having a plurality of 
penetration resistant planar bodies 28 formed from the composite of this 
invention affixed to a surface thereof. 
The shape of planar bodies 28 may vary widely. For example, planar bodies 
28 may be of regular shapes such as hexagonal, triangular, square, 
octagonal, trapizoidal, parallelogram and the like, or may be irregular 
shaped bodies of any shape or form. In the preferred embodiments of this 
invention, planar bodies 14 are regular shaped bodies, irregularly shaped 
bodies or combination thereof which completely of substantially completely 
(at least 90% area) cover the surface of substrate layer 214. In the more 
preferred embodiments of the invention, planar bodies 28 are of regular 
shape (preferably having truncated edges), and in the most preferred 
embodiments of the invention planar bodies 28 are triangular shaped bodies 
(preferably right angle triangles, equilateral triangles or a combination 
thereof and more preferably equilateral triangles) or a combination of 
triangular shaped bodies and hexagon shaped bodies, which provide for 
relative improved flexibility relative to ballistic articles having planar 
bodies 28 of other shapes of equal area. 
The number of layers 20 included in article 18 of this invention may vary 
widely depending on the uses of the composite, for example, for those uses 
where article 18 would be used as ballistic and/or blast protection, the 
number of layers 20 would depend on a number of factors including the 
degree of ballistic and/or blast protection desired and other factors 
known to those of skill in the ballistic and/or blast protection art. In 
general for this application, the greater the degree of protection desired 
the greater the number of layers 20 included in article 18 for a given 
weight of the article Conversely, the lesser the degree of ballistic 
and/or blast protection required, the lesser the number of layers 20 
required for a given weight of article 18. 
As depicted in the FIGS. 2 to 4, article 18 preferably includes at least 
two layers 20 in which each layer 20 is composed of a substrate layer 26 
which is partially covered with planar bodies 28, preferably forming an 
alternating pattern of covered areas 30 covered with a planar body 28 and 
uncovered areas 32. These layers are positioned in article 18 such that 
uncovered areas 32 of one layer 20 are aligned with covered areas 30 of 
another layer 20 (preferably an adjacent layer) providing for partial or 
complete coverage of uncovered areas 32 of one layer 20 by covered areas 
30 of another layer 20 and vice versa. The layers 20 can be secured 
together by some suitable arrangement to maintain areas 30 and 32 in 
alignment. Alternatively, another preferred embodiment (not depicted) 
includes a layer 20 in which each side of the layer is partially covered 
with bodies 28 where the bodies are positioned such that covered areas 30 
on one side of layer 26 are aligned with uncovered areas 32 on the other 
side of layer 20. In the preferred embodiments of the invention the 
surface of layer 20 covered with planar body 28 such that the bodies are 
uniformly larger than uncovered mated areas 32 of the other layer 20 
providing for complete overlap. This is preferably accomplished by 
truncation of the edges of the bodies 28 or otherwise modification of such 
edges to allow for close placement of the bodies on the surface such that 
a covered area is larger than the complimentary uncovered area. 
The degree of overlap may vary widely. In general, the degree of overlap is 
such that preferably more than about 90 area %, more preferably more than 
about 95 area % and most preferably more than about 99 area % of the 
uncovered areas 30 on an outer surface of the plurality of layers 20 are 
covered by its corresponding planar body 28 on the other outer surface of 
the plurality of layers 20. 
The article 18 of this invention may be fabricated through use of 
conventional techniques. For example, bodies 28 may be sewn to layer 20 
using conventional sewing techniques, preferably at one or more points of 
body 28, more preferably a distance from the edge of a body 28. By sewing 
a distance from the edge of body 28 flexibility is enhanced. To prevent 
extensive disalignment between various layers 20 adjacent layers can be 
stitched together. 
Means for attaching planar bodies 28 to substrate layer 26 may vary widely 
and may include any means normally used in the art to provide this 
function. Illustrative of useful attaching means are adhesives such as 
those discussed in R.C. Liable, Ballistic Materials and Penetration 
Mechanics, Elsevier Scientific Publishing Co. (1980). Illustrative of 
other useful attaching means are bolts, screws, staples mechanical 
interlocks, stitching, or a combination of any of these conventional 
methods. In the preferred embodiments of the invention planar bodies 28 
are stitched to the surface of layer 26. Optionally, the stitching may be 
supplemented by adhesive. 
The thread used to stitch bodies 28 to substrate layers 214 can vary 
widely, but is preferably a relatively high modulus (equal to or greater 
than about 200 grams/denier) and a relatively high tenacity (equal to or 
greater than about 15 grams/denier) fiber. All tensile properties are 
evaluated by pulling a 10 in. (25.4 cm) fiber length clamped in barrel 
clamps at 10 in/min (25.4 cm/min) on an Instron Tensile Tester. In the 
preferred embodiments of the invention, the modulus of the fiber is from 
about 400 to about 3000 grams/denier and the tenacity is from about 20 to 
about 50 grams/denier, more preferably the modulus is from about 1000 to 
about 3000 grams/denier and the tenacity is from about 25 to about 50 
grams/denier; and most preferably the modulus is from about 1500 to 3000 
grams/denier and the tenacity is from about 30 to about 50 grams/denier. 
Useful threads and fibers may vary widely and include those described 
herein above in the discussion of fiber for use in the fabrication of 
substrate layers 20. However, the thread or fiber used in stitching means 
is preferably an aramid fiber or thread (as for example Kevlar.RTM. 29, 
49, 129 and 141 aramid fiber), an extended chain polyethylene thread fiber 
(as for example Spectra.RTM. 900 fiber and Spectra.RTM. 1000 polyethylene 
fiber) or a mixture thereof. 
Substrate layer 26 may vary widely. For example, substrate layer 26 may be 
a flexible polymeric or elastomeric is film formed from a thermoplastic or 
elastomeric resin. Such thermoplastic and elastomeric resins for use in 
the practice of this invention may vary widely. Illustrative of useful 
thermoplastic resins are polylactones such as poly(pivalolactone), 
poly(e-caprolactone) and the like; polyurethanes derived from reaction of 
diisocyanates such as 1,5-naphthalene diisocyanate, p-phenylene 
diisocyanate, m-phenylene diisocyante, 2,4-toluene diisocyanate, 4-4' 
diphenylmethane diisocyanate, 3-3'dimethyl-4,4'biphenyl diisocyanate, 
4,4'diphenylisopropylidiene diisocyanate, 3,3'-dimethyl-4,4'diphenyl 
diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 
3,3-dimethoxy-4,4'-biphenyl diisocyanate, dianisidine diisocyanate, 
tolidine diisocyanate, hexamethylene diisocyanate, 
4,4'-diisocyananodiphenylmethane and the like and linear long-chain diols 
such as poly(tetramethylene) adipate), poly(1,5-pentylene adipate), 
poly(1,3 butylene adipate), poly(ethylene succinate), poly(2,3-butylene 
succinate), polyether diols and the like; polycarbonates such as 
poly[methane bis (4-phenyl) carbonate], poly[1,1-ether bis(4-phenyl) 
carbonate], poly[diphenylmethane bis (4-phenyl carbonate], 
poly[1,1-cyclohexane bis[4-phenyl) carbonate] and the like; poly sulfones; 
polyether ether ketones; polyamides such as poly(4-amino butyric acid), 
poly(hexamethylene adipamide), poly(14-aminohexanoic acid), 
poly(m-xylylene adipamide), poly(p-xylylene sebacamide), poly 
[2,2,2-trimethyl hexamethylene terephthalamide), 
poly(metaphenyleneisophthalamide) (Nomex), poly(p-phenylene 
terephthalamide) (Kevlar), and the like; polyesters such as poly(ethylene 
azelate), poly(ethylene-1,5-naphthalate), poly(1,4-cyclohexane dimethylene 
terephthalate), poly(ethylene oxybenzoate) (A-Tell), poly(para-hydroxy 
benzoate) (Ekonol),(poly(1,4-cyclohexylidene dimethylene terephathalate) 
(Kodel) (as), poly(1,4-cyclohexylidene dimethylene terephthalate) (Kodel) 
(trans), polyethylene terephthalate, polybutylene terephthalate and the 
like; poly(arylene oxides) such as poly(2,14-dimethyl-1,4-phenylene 
oxide), poly(2,14-diphenyl-1,4-phenylene oxide), and the like; 
poly(arylene sulfides) such as poly(phenylene sulfide) and the like; 
polyetherimides; thermoplastic elastomers such as polyurethane elastomer, 
fluoroelastomers, butadiene/acrylonitrile elastomers, silicone elastomers, 
polybutadiene, polyisobutylene, ethylene-propylene copolymers, 
ethylene-propylene-diene terpolymers, polychloroprene, polysulfide 
elastomers, block copolymers, made up of segments of glassy or crystalline 
blocks such as polystyrene, poly(vinyl-toluene), poly(t-butyl styrene), 
polyester and the like and the elastomeric blocks such as polybutadiene, 
polyisoprene, ethylene-propylene copolymers, ethylene-butylene copolymers, 
polyether ester and the like as for example the copolymers in 
polystrene-polybutadiene-polystyrene block copolymer manufactured by Shell 
Chemical Company under the trade name of Kraton; vinyl polymers and their 
copolymers such as polyvinyl acetate, polyvinyl alcohol, polyvinyl 
chloride, polyvinyl butyral, polyvinylidene chloride, ethylene-vinyl 
acetate copolymers, and the like; polyacrylics, polyacrylate and their 
copolymers such as polyethyl acrylate, poly(n-butyl acrylate), polymethyl 
methacrylate, polyethyl methacrylate, poly(n-butyl methacrylate), 
poly(n-propyl methacrylate), polyacrylamide, polyacrylonitrile, 
polyacrylic acid, ethylene-acrylic acid copolymers, methyl 
methacrylate-styrene copolymers, ethylene-ethyl acrylate copolymers, 
methacrylated budadiene-styrene copolymers and the like; polyolefins such 
as low density polyethylene, polypropylene, chlorinated low density 
polyethylene, poly(4-methyl-1-pentene) and the like; ionomers; and 
polyepichlorohydrins; polycarbonates and the like. 
Substrate layer 26 may also be formed from fibers alone in some suitable 
form. Illustrative of suitable fibers are those described above for use in 
the fabrication of layer 14. The fibers in substrate layer 214 may be 
arranged in networks having various configurations. For example, a 
plurality of filaments can be grouped together to form twisted or 
untwisted yarn bundles in various alignments. The filaments or yarn 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 of aramid fabrics for ballistic-resistant 
articles. For example, the techniques described in U.S. Pat. No. 
4,181,7148 and in M. R. Silyquist et al., J. Macromol Sci. Chem., A7(1), 
pp. 203 et. seq. (1973) are particularly suitable. 
Layers 26 may also be formed from fibers coated with a suitable polymer, as 
for example, a polyolefin, polyamide, polyester, polydiene such as a 
polybutadiene, urethanes, diene/olefin copolymers, such as 
poly(styrene-butadiene-styrene) block copolymers, and a wide variety of 
elastomers. Fibrous layer 12 may also comprise a network of a fibers 
dispersed in a polymeric matrix as for example a matrix of one or more of 
the above referenced polymers to form a flexible fabric or uniaxial 
composite as described in more detail in U.S. Pat. Nos. 4,623,574; 
4,748,064; 4,737,402; 4,916,000; 4,403,012; 4,457,985; 4,650,710; 
4,681,792; 4,737,401; 4,543,286; 4,563,392; and 4,501,856. In the 
preferred embodiments of the invention, layer 12 is formed of a uniaxial 
composite in which the fibers are aramid fiber, polyethylene fiber or a 
combination thereof as described in U.S. Pat. No. 4,916,000. 
Frontal layers 22 and 24 may be constructed of the same materials as 
substrate layer 26 in the same preferences. For example, frontal layers 22 
and 24 are preferably formed form a fibrous network either alone such as a 
non-woven or woven fabric or a uniaxial layer of an array of parallel or 
substantially parallel fibers, or dispersed or embedded in a polymeric 
matrix such as those structures described in U.S. Pat. Nos. 4,916,000 and 
4,737,402. 
In ballistic studies, the specific weight of the shells and plates can be 
expressed in terms of the areal density (ADT). This areal density 
corresponds to the weight per unit area of the ballistic resistant armor. 
In the case of filament reinforced composites, the ballistic resistance of 
which depends mostly on filaments, another useful weight characteristic is 
the filament areal density of the composite. This term corresponds to the 
weight of the filament reinforcement per unit area of the composite (AD). 
The following examples are presented to provide a more complete 
understanding of the invention and are not to be construed as limitations 
thereon. 
EXAMPLE 1 
A number of panels, 13" (33 cm).times.13" (33 cm), were prepared having an 
overall areal density of 7.6 kg/m.sup.2 and varying thicknesses of 
titanium strike-face laminated to a backing of a fibrous layer formed of 
layers of a composite of polyethylene fibers in a polymeric matrix in a 
polymeric matrix marketed by Allied-Signal inc. under the trade name 
SPECTRA.RTM. SHIELD composite, as summarized in the following Table 1. 
TABLE 1 
______________________________________ 
TITANIUM - SPECTRA .RTM. SHIELD COMPOSITE 
% TITANIUM PLATE 
SPECTRA .RTM. SHIELD 
THICKNESS 
TARGET COMPOSITE (IN.) (CM.) 
______________________________________ 
4 100 0.0 (0.0) 
9 82 0.012 (0.0305) 
14 62 0.025 (0.0635) 
7 39 0.040 (0.102) 
10 24 0.050 (0.127) 
100 0 0.063 (0.160) 
______________________________________ 
NOTE: 
ALL TARGETS ADT = 7.6 kg/m.sub.2 - 
The SPECTRA.RTM. SHIELD composite was molded from commercial SPECTRA.RTM. 
SHIELD composite (consisting of a continuous roll of 0.degree./90.degree. 
SPECTRA.RTM. SHIELD fiber in a matrix of Kraton.RTM. D1107 and having an 
ADT of 0.132 kg/m.sup.2 for a single 0.degree./90.degree. layer). The 
SPECTRA.RTM. SHIELD layers were plied together and molded for 30 minutes 
in a hydraulic press using a total force of 35 tons (31,780 kg) with a 
platen temperature of 125.degree. C. 
Ballistic testing was carried out against two low L/D threats identified as 
threats 1 and 2 and a high L/D threat identified as threat 3. V.sub.50 
values were obtained using these threats against a range of targets. A 
measure of ballistic efficiency, SEAT, was determined by calculating the 
ratio of the kinetic energy of the projectile at its V.sub.50 value to the 
areal density of the target. In these experiments, the areal density of 
the targets was held constant and the effect of changes in composition of 
the target on ballistic performance is shown in terms of relative SEAT 
values. 
Comparison of threat 1 ballistic performance as a function of composite are 
shown in FIG. 5, clearly illustrates that improved performance is achieved 
by the complex composite. Ballistic performance of the simple SPECTRA.RTM. 
SHIELD composite is shown as 100 wt. % SPECTRA.RTM. SHIELD composite and 
is clearly much superior to that of the titanium plate, shown as 0 wt. % 
SPECTRA.RTM. SHIELD composite. Considering impacts normal to the target 
surface, the line, MS, joining these two points indicates the performance 
expected from the complex composites as a function of composition if the 
rule of mixtures is followed. As can be seen from FIG. 5, over the 
composition range 67 to 99 wt. % SPECTRA.RTM. SHIELD composite (AREA A) 
the ballistic performance of the complex composite not only exceeds the 
performance expected from the rule of mixtures, but is ballistically 
superior to the simple composite composed of 100% SPECTRA.RTM. SHIELD 
composite. Over the composition range 40 to 67 wt. % SPECTRA.RTM. SHIELD 
composite (AREA B), the performance of the complex composites exceeds 
performance expected from the rule of mixtures. It is also clear from FIG. 
5 that the same trend in performance is obtained when the target is 
impacted at an angle of incidence of 45 degrees. As shown in FIG. 6, the 
ballistic results indicate that the same trends observed for the threat 1 
hold for threat 2. 
Ballistic data generated against threat 3, shown in FIG. 7, indicate that 
at an impact angle of 45 degrees the performance of the complex composites 
is significantly better than expected from the rule of mixtures. As can be 
seen from FIG. 7, over the composition range 1 to 70 wt. % SPECTRA.RTM. 
SHIELD composite, the complex composite is ballistically more effective 
that the titanium plate, which is markedly superior to simple composite 
against threat 3. In addition to this composition range of absolute 
superiority of the complex composite (illustrated as AREA A in FIG. 7), 
the complex composite additionally deviates positively from the rule of 
mixtures from 70 to 85 wt. % SPECTRA.RTM. SHIELD composite, shown as AREA 
B in FIG. 7. (Compare experimental points with the line M2S2, which 
represents the results anticipated from the rule of mixtures.) 
It is clear that a complex composite having approximately 70 wt. % 
SPECTRA.RTM. SHIELD composite will provide much superior protection 
against both high and low L/D threats as compared to either the simple 
SPECTRA.RTM. SHIELD composite or the titanium plate when used alone. 
The optimum composition of the complex composite will vary with the nature 
of the threats and the overall areal density of the target.