LAYER

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to the field of armor and specifically to an armor component including a hard layer, such as ceramic or glass ceramic, and a non- filamentous semicrystalline polymer layer.

A sensitive object is often protected from kinetic threats by armor interposed between the sensitive object and an approaching kinetic threat and as a result the kinetic threat impacts with the armor instead of with the sensitive object. The armor is configured to neutralize the kinetic threat by one or more methods such as deflection of the kinetic threat, destruction/deformation of the kinetic threat and dissipation of the kinetic energy of the kinetic threat. In the art, known mechanisms for dissipating the kinetic energy of the kinetic threat include deformation of the kinetic threat, absorption of the kinetic energy and distribution of the kinetic energy over a large area.

Sensitive objects in many fields are increasingly subject to increasingly dangerous kinetic threats. In the past, kinetic threats in the field of sports were rare. The speed of sports such as motorcycling, automobile racing, skiing and bobsledding has increased to the point where the danger from kinetic threats resulting from collision with static objects has increased significantly. Since sport performance is adversely affected by increased weight, the use of massive armor and shielding devices is impossible, leading to the use of lightweight and comfortable but not necessarily effective protection devices. There is a need to provide lightweight but effective protection from kinetic threats for individuals involved in sports.

Modern automobiles are constructed from thin metal or plastic panels designed to minimize vehicular weight and thus increase performance and economy of fuel use. At the same time, the cruising velocity of automobiles continuously increases. Both factors together have led to an increase in traffic casualties. Although the effects of sudden deceleration cause most traffic casualties, a significant percentage of traffic casualties result from the penetration of objects into the

passenger volume of an automobile through the thin panels. In the field of personal transport, there is a need to provide lightweight protection from objects penetrating the passenger volume of personal transport vehicles such as automobiles.

Satellites and space exploration vehicles are generally not protected from kinetic threats due to the prohibitive unit weight cost of launching an object into orbit and due to the fact that the risk of catastrophic failure, for example resulting from impact with a meteorite, has been judged to be very low. However, the increasing density of debris at desired orbit altitudes ("space junk") increases the chance of such an impact occurring. In the field of aerospace, there is a need to protect satellites and other space vehicles from kinetic threats such as the impact of "space junk" with armor that weighs as little as possible so as to make launch financially feasible. Since satellites are not general reparable, it is preferred that such protection be useful for protecting against multiple kinetic threats.

In the past, non-military vehicles and installations were not often targets for attacks from kinetic threats. Fragment-projecting explosive devices, high- velocity firearms, especially automatic firearms, and large caliber firearms have become increasingly available and at the same time, the will to use these devices and firearms by both criminal and terrorist organizations against civilian and other non-military targets has increased. As a result traditionally "soft" vehicles such as civilian buses and trains, limousines, police vehicles, and civilian logistics vehicles such as fuel transport vehicles, trucks and light utility vehicles are increasingly hardened. Traditional armors are heavy. The increase in weight caused by the addition of sufficient armor reduces vehicle mobility, maneuverability, stability, requires a massive and expensive frame, and leads to greater wear and consequent increased acquisition and operating costs. In the field of civil defense and crime fighting there is a need for lightweight, simple to produce and cheap armor to neutralize kinetic threats to military, non-military and civilian vehicles and installations.

Metal armor is generally chosen for protecting combat vehicles and military aircraft from kinetic threats. Increasingly, requirements for air transport and amphibious operation requires that lighter weight armored solutions be found. Prior- art ceramic armors are effective against single kinetic threat impacts but are significantly less effective against the increasingly common multiple and serial kinetic threats posed by fragment-projecting devices, cluster weapons and automatic

weapons. There is a need for high-performance, lightweight materials for use in military armor applications with multiple-threat neutralization capabilities.

Individual armor became outmoded with the introduction of firearms. For the first half of the twentieth century it was believed that the small size and mobility of an individual person conferred sufficient defense from kinetic threats and was preferable to weighing down the individual with massive armor. With the increased availability and use of fragment-projecting explosive devices and high-velocity automatic firearms, the survivability of an individual subjected to standard kinetic threats is significantly reduced. As a result individual body armor is becoming standard equipment for high-risk individuals, police and infantry soldiers. However, current body armor materials are either too bulky, reducing the efficacy of the individual in performing standard tasks when worn, or provide insufficient protection from increasingly effective kinetic threats. Further, both fragment-projecting devices and automatic weapons produce multiple kinetic threats for which the protection afforded by currently available body armor is insufficient, hi the field of personal defense, there is a need for lightweight body armor protection capable of protecting an individual from multiple kinetic threats such as produced by fragment-projecting explosive devices and high-velocity automatic firearms.

Materials used in currently available armors can be divided into three types: metals, polymers and ceramics.

Metal armors provide excellent protection from kinetic threats, are cheap and relatively easy to produce from alloys, usually including aluminum, cobalt, titanium and iron. Metal armors protect an object by deforming or deflecting an impacting kinetic threat and by dissipating the kinetic energy of the kinetic threat both by inelastic and elastic deformation. Metal armors are effective against multiple kinetic threats since damage to the armor caused during neutralization of the kinetic threat is generally local to the area of impact. However, the weight of metal armors is such that providing sufficient protection against increasingly common kinetic threats is impractical. Polymer armors are considered lightweight, easy to produce in virtually any shape, simple to install and retrofit, and are relatively comfortable to wear as body armor. Most modern polymer armors are made of fibers made of semi-crystalline polymers.

A common semi-crystalline polymer used for producing fibers for polymer armors is a poly(arylamide) made by the condensation of terephthalic acid and 1,4- benzenediamine (see, for example, U.S. Patent 3,671,542) and marketed under the name Kevlar® (E.I. du Pont de Nemours and Company, Wilmington, Delaware, USA) or Twaron® (Teijin Twaron B. V., Arnhem, The Netherlands).

Another common highly-oriented semi-crystalline polymer used for producing fibers for polymer armors are polyethylene fibers made according to method that yields exceptionally highly-oriented high molecular weight (HOHMW) polymer chains, see for example U.S. Patent 4,413,110 and references therein. Such polyethylene fibers are marketed under the name Spectra™ (AlliedSignal Inc.,

Morristown, New Jersey, USA) or Dyneema® (Koninklijke DSM N.V., Heerlen, The

Netherlands). Such fibers are characterized as having low stretch (e.g., 4% elongation at failure for Spectra™) and high longitudinal tensile strength (e.g., 2300-3500 MPa).

For armor application, semi-crystalline polymer fibers are generally woven to make a textile and a plurality of layers of such a textile stacked and mutually attached using a resin to make a single laminated textile armor. When a kinetic threat impacts such laminated woven textile armor, the kinetic threat is caught in the web of fibers.

The fibers absorb and disperse the energy of the impact to other fibers at the crossover points of the weave. Energy is dissipated by deformation (elastic and inelastic) of many interwoven fibers and by delamination of the armor. Generally, woven textile armors are suitable for protecting against low energy threats such as shrapnel and small caliber bullets having impact velocities up to about 450 m sec ^"1 .

It has been found that weaving is detrimental to the impact resistance of polymer fibers. First, the bending and flexing of the fibers in the weave produces bottlenecks that reduce the rate and extent of energy dissipation through an individual fiber and at the same time, the fact that energy is distributed between fibers at crossover points leads to a localization rather than distribution of absorbed energy.

The localization of the absorbed energy increases the importance of delamination of the textile layers as an energy dissipating mechanism, a fact that reduces the multiple- threat neutralization capability of such armors.

Non-woven cloths of semicrystalline polymer fibers have been found to provide superior performance in armor applications see, for example, PCT patent application published as WO 95/00318. Such non-woven cloths are made by

producing a tape comprising a monolayer of tightly-packed parallel strands of polymer fiber held in place by an adhesive, for example a thermoplastic resin. Two (or more) such tapes are cross-plied and fused and/or stacked to make a unitary cloth. Due to the high sonic-velocity (e.g., 12300 m s ^"1 for strands of Spectra™ HOHMW polyethylene) along the entire non-kinked molecular axis, energy absorbed by a given fiber at any point is very quickly transferred along the entire length of the fiber. As a result, the cross ply of two monolayers of parallel fibers quickly disperses kinetic energy absorbed from an impacting kinetic threat over a very large area before there is time for a fiber to break, thus neutralizing the kinetic threat. Armors made of non- woven polymer fibers provide protection from kinetic threats that is significantly superior to the protection provided by woven polymers. As with laminated woven textile armors, laminated non-woven cloth armor sheets are known to delaminate upon impact of a kinetic threat. Non-woven cloths of semi-crysyalline polymer fibers are commercially available as SpectraShield™ (HOHMW polyethylene) and GoldShield™ (poly(arylamide)) both of AlliedSignal Inc. (Morristown, New Jersey, USA).

In U.S. Patent 6,183,834 is taught the compression molding of stacked non- woven polymer fiber cloths. Such compression molding leads to the formation of a rigid unitary structure where the crystalline nature, molecular directionalities and lamination of the original stack of cloth is preserved. The thus-produced laminated polymer has been shown to be exceptional effective in neutralizing a kinetic threat through substantially the same mechanism as the non-woven polymer fiber cloth laminates. Generally, armors of compression-molded non-woven laminated fibers are suitable for protecting against kinetic energy threats having impact velocities of up to about 850 m sec ^"1 . Such compression-molded non-woven laminated fiber armors are generally not suited for neutralizing high-velocity kinetic threats (faster than 900 m sec ^"1 ) or lower velocity armor-piercing threats (threats including a very hard "kinetic penetrator" component). Laminated polymers made by the compression molded non- woven cloths of semi-crysyalline polymer fibers are commercially available as Dyneema UD® (Koninklijke DSM N.V., Heerlen, The Netherlands).

Although expensive, armors made of plates of ceramic materials provide a high level of protection from kinetic threats and are light in weight in comparison to equivalent metal armors. The use of ceramic materials for protecting objects from

kinetic threats is discussed in, for example, Medvedovski, American Ceramic Society Bulletin (2002), 81 (3), 27-32 and U.S. Patent 3,765,600, U.S. Patent 4,953,442, U.S. Patent 4,911,061, U.S. Patent 4,138,456, U.S. Patent 5,456,156, U.S. Patent 5,469,773, U.S. Patent 5,705,764, U.S. Patent 6,112,635 and U.S. Patent 6,408,733. Ceramic materials used in armors neutralize kinetic threats by deforming the impacting kinetic threat and by dissipating absorbed kinetic energy through a combination of a pulverization energy mechanism and a fracture energy mechanism. In the pulverization energy mechanism, a comminution zone of pulverized ceramic in the shape of a conoid emerging from the impact point is produced. In the fracture energy mechanism, kinetic energy is absorbed by the ceramic plate, distributed throughout the plate and subsequently expended by the shattering of the ceramic plate through radial and circumferential cracks.

Ceramics most often used for protection of objects from kinetic threats are monolithic ceramics such as Al ₂ O ₃ , B ₄ C, SiC and AlN. Due to improved mechanical properties, ceramic-matrix composites are increasingly used instead of monolithic ceramics for protecting objects from kinetic threats. Suitable ceramic-matrix composites include fiber-reinforced materials such as Al ₂ O ₃ /SiC and Al ₂ (VC, ceramic/particulates such as TiB ₂ /B ₄ C and TiB ₂ /SiC and cermets such as SiC/ Al, TiC/N and B ₄ C/A1. Energy dissipation through the fracture energy mechanism is most efficient in ceramic materials that are stiff and have a high sonic velocity. High stiffness leads to maximal post-impact stress in the ceramic with very little elastic deformation whereas a high sonic velocity spreads the stress throughout the ceramic plate before actual shattering occurs. Ultimately, the impact energy of the kinetic threat is used to break many chemical bonds of the ceramic plate, thereby shattering the entire ceramic plate, see for example U.S. patent 5,469,773.

Very hard ceramics are preferred for use in armor application to ensure deformation of the kinetic threat in order to dissipate kinetic energy and to reduce the chance of follow-through penetration subsequent to ceramic plate shattering. The fact that ceramic materials shatter to dissipate the kinetic energy of a kinetic threat means that ceramic armor is generally useful for protecting an object only against impact from a single kinetic threat. Due to the extensive shattering of the ceramic, subsequent impacts have a statistically significant chance to impact on a

crack and penetrate with little or no resistance. Further, the shards of the ceramic armor produced by the shattering are relatively small and have little mass: the small size means that there only a few bonds are available for dissipation of energy from subsequent kinetic threat impacting on such a shard and that such a shard may be pushed through by an impacting kinetic threat into the sensitive object being protected.

In U.S. Patent application 10/928,723 published as 20050119104 of the inventor is taught the use of glass-ceramics such as those containing an Anorthite crystalline phase, for protecting objects from kinetic threats. Suitable glass-ceramics are hard enough to cause deformation of an incoming ceramic threat yet do not shatter to dissipate absorbed kinetic energy. Rather, the suitable glass-ceramics dissipate the kinetic energy of an impacting kinetic threat primarily through a pulverization energy mechanism. In the pulverization energy mechanism, the glass-ceramic is pulverized in the immediate vicinity of the impact of the kinetic threat. As pulverization necessarily requires destruction of many bonds, much kinetic energy is dissipated by destruction of only a small part of the shielding material. At the same time, damage caused by an impacting kinetic threat is localized and only a small part of the glass-ceramic is destroyed. Since the glass-ceramic does not significantly crack or shatter, the overall structural integrity of armor including a glass-ceramic component is preserved, providing such armor with exceptional efficacy against multiple kinetic threats.

As stated above, monolithic ceramic armors neutralize an impacting kinetic threat by deforming the kinetic threat and by dissipating the kinetic energy of the kinetic threat by shattering. A significant danger when using ceramic armors is that of follow-through penetration: fragments of the kinetic threat or shards of ceramic have sufficient residual kinetic energy to penetrate into and damage the object being protected by the armor. In glass-ceramics that dissipate the kinetic energy of an impacting kinetic threat through pulverization energy mechanism there is the possibility that a plug of pulverized glass-ceramic or fragments of the kinetic threat will penetrate into and damage the object being protected. To reduce the dangers of follow-through penetration armors generally include at least two layers, see Figure 1. In Figure IA, a unitary armor component 10 includes a first layer 12 of ceramic or glass-ceramic as a strike face and second layer 14 of laminated woven or non-woven cloth as a spall liner. Second layer 14 is generally

attached to first layer 12 with a resin or adhesive so as to make a unitary armor component. Since such cloths are invariably impregnated with a resin or adhesive, in some instances attachment does not include a separate adhesive layer, although in some instances a separate adhesive layer is used. Incoming kinetic threat 16 impacts with first layer 12 and is deformed thereby while first layer 12 absorbs the kinetic energy of impact, Figure IB. If the kinetic energy absorbed is sufficient to shatter 18 and/or pulverize 20 first layer 12, any fragments and shards are trapped and residual kinetic energy absorbed by second layer 14. Subsequently, Figure 1C, energy transferred to second layer 12 is dissipated by delamination at the first layer 12 / second layer 14 interface 22 and tearing and delamination 24 of the cloth layers making up second layer 14. Damage to a sensitive object being protected by unitary armor component 10 from penetrating fragments and shards is prevented. Backface deformation 26 of unitary armor component 10 may cause damage to the sensitive object being protected, but the severity of the damage is mitigated by distribution over a relatively large area.

In U.S. Patent 3,516,898 is taught an armor component 10 having a third elastomer adhesive (e.g., polysulfide) layer (not depicted) sandwiched between a second laminated cloth polymer layer 14 and a first hard layer 12. In such an armor component some kinetic energy is absorbed and dissipated by the third elastomer layer through elastic deformation.

Due to lack of suitable adhesives, unitary armor components analogous to 10 including compression-molded non-woven laminated fiber armors as a second layer are not known.

Unitary armor components such as 10 comprising a first hard layer 12 backed by a second laminated cloth layer 14 attached thereto with a resin or adhesive have a number of disadvantages. Importantly, such armor components are expensive, as both the first hard layer and the second laminated cloth layer require expensive raw materials and complex manufacturing steps to produce. A further problem results from the fact that delamination at the interface of first layer 12 with second layer 14 and delamination of second layer 14 compromise the multiple threat neutralization capability of an armor component 10. A further problem results from the fact that second layer 14 is a non-rigid cloth so that the rigidity of armor component 10 is dependent on the structural integrity of first layer 12. When first layer 12 is of a

material that dissipates energy through the fracture energy mechanism, upon impact of a kinetic threat the shape of armor component 10 is lost.

It would be advantageous to have a unitary armor component including a first hard layer as a strike face to deform an incoming threat and dissipate kinetic energy and a second layer to prevent follow-through penetration of kinetic threat fragments and shards of the first layer from affecting a protected sensitive object, where the second layer is cheaper and easier to produce than known such layers made of laminated cloths. It would be advantageous that such a unitary armor component provides protection from kinetic threats on par with or exceeding the protection provided by known armor components of comparable bulkiness and mass. It would be advantageous that such a unitary armor component provides protection from multiple kinetic threats, including multiple high-velocity kinetic threats. It would be advantageous that such a unitary armor component be rigid and not lose shape when damaged.

SUMMARY OF THE INVENTION

At least some of the objectives above are achieved by the teachings of the present invention.

The teachings of the present invention provide an armor component including a non-filamentous semicrystalline polymer layer. It is disclosed herein that the protection afforded by embodiments of such armors is similar or better than the protection afforded by comparable prior-art armor components having a laminated cloth layer.

An advantage of embodiments of an armor component of the present invention over comparable prior art armor components is the ease and low cost of production of a non-filamentous semicrystalline polymer layer.

According to the teachings of the present invention there is provided an article for protecting an object from a kinetic threat comprising: a) a first hard layer, preferably including (or substantially comprising or even consisting essentially of) a material selected from the group consisting of ceramic matrix composites (e.g., Al ₂ O ₃ /SiC, A1 ₂ O ₃ /C, TiB ₂ /B ₄ C, TiB ₂ /SiC, SiC/Al, TiC/N, B ₄ C/A1), monolithic ceramics (e.g., Al ₂ O ₃ , B ₄ C, SiC, AlN), glass-ceramics (e.g., including an Anorthite, Corderite Rutile crystalline phase), ceramics and glass; and b) a second layer,

including at least one non-filamentous semi-crystalline polymer, the second layer attached to the first layer so as to form a unitary component.

In an embodiment of the present invention the first and second layers are substantially in contiguous contact. In an embodiment of the present invention the second layer is substantially parallel to the first layer.

In an embodiment of the present invention, the second layer is substantially a plate (curved or flat).

In an embodiment of the present invention, the second layer is substantially box shaped, that is having a substantially plate-like bottom in contact with the first layer and walls extending from the bottom so as to at least partially surround the edges of the first layer.

In an embodiment of the present invention, the semi-crystalline polymer is a randomly crystallized non-filamentous semi-crystalline polymer. In an embodiment of the present invention, the second layer is not laminated.

In an embodiment of the present invention, the second layer is monolithic. In an embodiment of the present invention, the second layer is homogeneous.

In an embodiment of the present invention the second layer is substantially rigid. In an embodiment of the present invention the second layer is tough, having a room temperature notched Izod impact strength of greater than about 100 J m ^"1 , greater than about 150 J m ^"1 , greater than about 200 J m ^'1 , greater than about 400 J m ^" ', greater than about 600 J m ^"1 , greater than about 800 J m ^"L and even greater than about 1000 J m ^"1 . In an embodiment of the present invention the second layer has a room temperature notched Izod impact strength of less than about 100 J m ^'1 , less than about 80 J m ^"1 and even less than about 70 J m ^"1 .

In an embodiment of the present invention, at least one of the at least one non- filamentous semi-crystalline polymers is selected from the group consisting of acetal, liquid crystal polymers, maleic anhydride grafted polypropylene, polyamides, Nylon 4,6, Nylon 6, Nylon 6,6, Nylon 11, Nylon 12, poly (arylamide), polyethylene, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide,

polyphthalamide, polypropylene, poly(vinylidene fluoride), poly (p-phenylene-2,6- benzobisoxazole), poly (p-phenylene-2,6-benzobisthiazole) and mixtures thereof.

In an embodiment of the present invention, the first layer is between about 5 mm and about 25 mm thick or even between about 5 mm and about 10 mm thick. In an embodiment of the present invention, the second layer is thicker than about 2 mm, thicker than about 5 mm and even thicker than about 7 mm.

In an embodiment of the present invention, the second layer is thinner than about 40 mm, thinner than about 30 mm and even thinner than about 25 mm.

In an embodiment of the present invention, there is c) a third adhesive layer disposed between the first layer and the second layer. Preferably the third adhesive substantially attaches the first layer to the second layer. In an embodiment of the present invention, the third adhesive layer comprises at least one material selected from the group consisting of thermosetting resins and thermoplastic resins. In an embodiment of the present invention, the third layer is thinner than about 2 mm, thinner than about 1 mm, thinner than about 0.5 mm, thinner than about 0.2 mm, or even thinner than about 0.1 mm.

In some cases it is known that it is difficult to find an adhesive that effectively adheres to a polymer. Therefore, in embodiments of the present invention the article further comprises at least one adhesion promoter. In an embodiment of the present invention the adhesion promoter is a fourth adhesion promoter layer disposed between the second polymer layer and the third adhesive layer. In an embodiment of the present invention, the second layer comprises at least one adhesion promoter. For example, in embodiments of the present invention, maleic anhydride is used as an adhesion promoter, for example to promote adhesion between a polyamide second layer and an epoxy third adhesive layer.

In some cases it is preferred that the second layer be tougher and/or less frangible than attainable with a given type of polymer. In an embodiment of the present invention, the second layer further comprises an impact modifier or comprises an impact-modified polymer. Suitable impact modifiers include, but are not limited to, impact modifiers that are dispersions, polymer blends, copolymers and graft copolymers in or with the second layer.

In an embodiment of the present invention, the second layer consists essentially of non-filamentous semi-crystalline polymers and even consists entirely of

non-filamentous semi-crystalline polymers. In an embodiment of the present invention the second layer is substantially devoid of materials that are not non- filamentous semi-crystalline polymer.

In an embodiment of the present invention, the second layer comprises at least one additional material (e.g., a particulate material or a fibrous material) trapped within the non-filamentous semi-crystalline polymer, especially dispersed, especially randomly dispersed within the non-filamentous semi-crystalline polymer. In an embodiment of the present invention the second layer comprises less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of at least one additional material. In an embodiment of the present invention the second layer comprises less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of a particulate material. In an embodiment of the present invention the second layer comprises less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of a fibrous material.

In an embodiment of the present invention, the article comprises a fifth cloth layer (e.g., a woven textile or a non- woven cloth) comprising strands of fibers (e.g., polyamide fibers, poly(arylamide) fibers, polyethylene fibers). In an embodiment of the present invention a fifth cloth layer is attached to the second polymer layer. In an embodiment of the present invention, a fifth cloth layer is impregnated with at least one adhesive material.

In an embodiment of the present invention, the article has a shape, for example of an armor plate, armor sheet, bullet-proof vest, body armor, panel, door panel, floor panel, wall panel, helmet, seat, aircraft, rotary wing aircraft, fixed wing aircraft, armored fighting vehicle, limousine and motor vehicle.

In an embodiment of the present invention, the first layer is a strike face of the article. According to the teachings of the present invention there is also provided the use of an article as described above for protecting an object from a kinetic threat.

According to the teachings of the present invention there is also provided a method of making an article suitable for protecting an object from a kinetic threat

comprising: a) providing a first hard component, the first component preferably including (or substantially comprising or even consisting essentially of) a material selected from the group consisting of ceramic matrix composites, monolithic ceramics, glass-ceramics, ceramics and glass; b) providing a second component, including at least one non-filamentous semi-crystalline polymer; and c) attaching the first component and the second component so as to form a unitary armor component of the article.

In an embodiment of the present invention, at least one of the at least one non- filamentous semi-crystalline polymers is selected from the group consisting of acetal, liquid crystal polymers, maleic anhydride grafted polypropylene, polyamides, Nylon 4,6, Nylon 6, Nylon 6,6, Nylon 11, Nylon 12, poly(arylamide), polyethylene, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polyphthalamide, polypropylene, poly(vinylidene fluoride), poly (p-phenylene-2,6- benzobisoxazole), poly (p-phenylene-2,6-benzobisthiazole) and mixtures thereof. In an embodiment of the present invention, providing the second component comprises: i) providing a semi-crystalline polymer resin (that is, a resin that is a precursor for a semi-crystalline polymer); ii) melting the semi-crystalline polymer resin to yield a molten polymer; iii) transforming the molten polymer into a semi- crystalline polymer; and iv) shaping the semi-crystalline polymer into the shape of the second component.

In an embodiment of the present invention, transforming the molten polymer into a semi-crystalline polymer includes cooling the molten polymer.

In an embodiment of the present invention, shaping the semi-crystalline polymer into the shape of the second component includes a process selected from the group consisting of molding, injection molding, compression molding and extrusion of the molten polymer, preferably injection molding.

In an embodiment of the present invention, subsequent to melting of the semi- crystalline polymer resin, the molten resin is not formed into a filament.

In an embodiment of the present invention, the non-filamentous semi- crystalline polymer is a polyamide and providing the second component includes absorbing water into a solidified polyamide. In an embodiment of the present invention absorbing water comprises soaking a solidified polyamide in water. In an embodiment of the present invention, during at least part of the soaking, the water is

maintained at a temperature of greater than about 50°C, greater than about 80 ⁰ C, or even greater than about 90 ⁰ C.

In an embodiment of the present invention, attaching the first and second components includes contacting the first component with the second component so as to cause the second component to adhere to the first component.

In an embodiment of the present invention, attaching the first and second components includes, during the transforming of the molten polymer into the semi- crystalline polymer, maintaining contact of the incipient semi-crystalline polymer making up the incipient second component with the first component. In an embodiment of the present invention, attaching the first and second components includes using at least one adhesive {e.g., a thermosetting resin or a thermoplastic resin) to adhere the first component to the second component. In an embodiment of the present invention, using an adhesive includes applying the adhesive to one or both of the two components, for example by spraying the adhesive, painting the adhesive, brushing the adhesive, depositing the adhesive, pouring the adhesive or laying a sheet of adhesive. In an embodiment of the present invention, an adhesion promoter is applied to the second component so as to increase adhesion of the adhesive to the second component.

In an embodiment of the present invention, the second component includes at least one adhesion promoter. In an embodiment of the present invention the semi- crystalline polymer resin provided includes at least one adhesion promoter. In an embodiment of the present invention, at least one adhesion promoter is added to the molten polymer.

In an embodiment of the present invention, the second component includes at least one impact modifier. In an embodiment of the present invention the semi- crystalline polymer resin provided includes at least one impact modifier. In an embodiment of the present invention, at least one impact modifier is added to the molten polymer.

In an embodiment of the present invention, the second component includes at least one additional material selected from the group consisting of particulate materials and fibrous materials (as described above). In an embodiment of the present invention the semi-crystalline polymer resin provided includes at least one additional material selected from the group consisting of particulate materials and fibrous

materials. In an embodiment of the present invention, at least one additional material selected from the group consisting of particulate materials and fibrous materials is added to the molten polymer.

In an embodiment of the present invention, the first component and the second component are integrated into the article for protecting an object from a kinetic threat.

In an embodiment of the present invention, the unitary component is integrated into the article for protecting an object from a kinetic threat.

Typical articles include but are not limited to armor plates, armor sheets, bullet-proof vests, body armor, panels, door panels, floor panels, wall panels, helmets, seats, aircraft, rotary wing aircraft, fixed wing aircraft, armored fighting vehicles, limousines and motor vehicles.

According to the teachings of the present invention, there is provided a method of protecting an object from kinetic threats comprising providing the object with armor, the armor including an article as described above. In an embodiment of the present invention, the first hard layer is positioned so as to serve as a strike-face of the armor.

According to the teachings of the present invention there is also provided a method for protecting an object from a kinetic threat comprising providing the object with armor including at least two layers, a first hard strike-face layer positioned and configured so as to absorb energy from an impacting kinetic threat and a second soft frangible layer configured to absorb the energy from the first hard strike face and to dissipate at least some of the energy by breaking into at least one (harmless) spall.

Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it

is stressed that the particulars shown are by way of example and for purposes of illustratiye discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the drawings: FIGS. IA- 1C (prior art) depict a kinetic threat impacting a unitary armor component having a ceramic strike face and a laminated cloth spall liner;

FIGS. 2A-2C depict a kinetic threat impacting a unitary armor component of the present invention having a ceramic strike face and a non-filamentous semi- crystalline polymer second layer; FIGS. 3A-3B depict a unitary armor component of the present invention comprising a box-shaped second layer;

FIGS. 4A-4C depict a kinetic threat impacting a unitary armor component of the present invention having a ceramic strike face and a frangible non-filamentous semi-crystalline polymer second layer so that kinetic energy is also dissipated by ejection of a harmless polymer spall in accordance with a method of the present invention;

FIG. 5 depicts a unitary armor component of the present invention including a first layer and a second layer comprising a non-filamentous semi-crystalline polymer sandwiching a third adhesive layer; FIG. 6 depicts a unitary armor component of the present invention including a first layer and a second layer comprising a non-filamentous semi-crystalline polymer sandwiching a third adhesive layer and a fourth adhesion promoter; and

FIG. 7 depicts a unitary armor component of the present invention including a first layer and a second layer comprising a non-filamentous semi-crystalline polymer sandwiching a third adhesive layer and a fifth cloth layer.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention is of an item including a unitary armor component with a first layer of a hard material such as a ceramic-matrix composite, monolithic ceramic, a glass-ceramic, a ceramic or a glass preferably serving as a strike-face and a second non-filamentous semicrystalline polymer layer as well as methods for manufacturing such an item. The present invention is also of the use of such an item for protecting objects from a kinetic threat. The present invention is also of methods for protecting an object from a kinetic threat. The present invention is also of a method of manufacturing an item for protecting an object from a kinetic threat. The present invention is also of an article for protecting an object from a kinetic threat.

As used herein, the terms "comprising" and "including" or grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. This term encompasses the terms "consisting of and "consisting essentially of.

The phrase "consisting essentially of or grammatical variants thereof when used herein are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof but only if the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method.

As used herein, the term "process" and the term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, material, defense and ceramic arts.

As used herein, the term "fiber" or grammatical variants thereof refers to an elongate body having a length dimension significantly greater than transverse dimensions of width and thickness. The term fiber includes, but is not limited to, monofilament, filament, multifilament, ribbon, strand, strip, whisker, yarn and other forms having regular or irregular cross-sections.

As used herein, the term "rigid" refers to a structure that is capable of free standing with little or substantially no collapse or deformation.

The principles and uses of the items, components, processes and methods of the present invention may be better understood with reference to the description and examples hereinbelow.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. In Figure 2, an article for protecting an object from a kinetic threat of the present invention is depicted, the article comprising: a) a first layer 12, including (or substantially comprising or even consisting essentially of) a material selected from the group consisting of ceramic matrix composites (e.g., Al ₂ O ₃ ZSiC, Al ₂ CVC, TiB ₂ /B ₄ C, TiB ₂ /SiC, SiC/ Al, TiC/N, B ₄ C/A1), monolithic ceramics (e.g., Al ₂ O ₃ , B ₄ C, SiC, AlN), glass-ceramics (e.g., including an Anorthite, Corderite or Rutile crystalline phase), ceramics and glass; and b) a second layer 30, including at least one non-filamentous semi-crystalline polymer, the second layer attached to the first layer so as to form a unitary armor component 28.

As in prior art armor, first layer 12 is preferably a strike face of the article. A kinetic threat 16 impacts first layer 12. The impact causes kinetic threat 16 to lose a significant amount of energy, including by deformation of kinetic threat 16 itself. For effective deformation of kinetic threat 16 to occur, it is generally necessary that first layer 12 be harder than kinetic threat 16. As a result, the hardness of a first layer 12 of an article of the present invention is preferably greater than about 7 GPa [HV], greater than about 8 GPa [HV], greater than about 9 GPa [HV] and even greater than 10 GPa [HV]. Further, a significant amount of energy is absorbed and dissipated by first layer 12. As discussed hereinabove in the introduction, dissipation of the kinetic energy often involves extensive shattering 18, localized comminution 20 or both of first layer 12. Second layer 30 absorbs residual energy and catches fragments and shards of kinetic threat 16 and first layer 26.

As discussed prior art second layers 14 depicted in Figures IA- 1C analogous to second layer 30 of the present invention are laminated cloths impregnated with adhesive. Fragments and shards are caught in the web of such second layers 14 and

thus prevented from penetrating through armor component 10. Absorbed energy is dissipated by delamination of and fiber tearing in a second layer 14. Residual energy resulting in backface deformation 26 is spread over a relatively large area so as to reduce the severity of damage such as blunt trauma to a protected object. In contrast, a second layer 30 of the present invention is of at least one non- filamentous semi-crystalline polymer. Substantially, a non-filamentous semi- crystalline polymer can be considered to be strong and rigid oriented polymer crystals randomly dispersed inside a tough and flexible elastomer matrix. The mechanisms by which non-filamentous semi-crystalline polymer dissipate energy is discussed, for example, in Akkapeddi in Chapter 8 of Baker W.E., Scott, C.E.; Hu, G.-H. (editors) "Reactive Polymer Blending" (2001), Carl Hanser Verlag, Munich, Germany. The inventor further postulates that since energy dissipation properties of a second layer 30 of the present invention are dependent on localized structures of polymer crystals held within an elastomer matrix, a second layer 30 of the present invention has superior multi-threat neutralization capabilities compared to prior art filamentous second layers made of laminated cloth (such as 14) where performance is degraded with each impacting kinetic threat due to energy dissipation by delamination and filament breaking.

A second layer 30 of the present invention is entirely dissimilar to prior art armor components including compression-molded non- woven laminated cloths. In such prior art armor components, many layers of filamentous semi-crystalline polymer cloths are compressed together with substantially no adhesive to make a unitary highly oriented laminated semi-crystalline polymer armor component where the orientation of the individual polymer molecules in the original cloth is preserved in the unitary polymer armor component. Due to the high speed of sound and straight orientation of the polymer molecules, the energy of an impacting kinetic threat is distributed over a large area and over a large number of bonds before there is time to cause inelastic deformation or damage to the molecules. Although not necessarily filamentous, such prior art armor components preserve the filamentous orientation and laminated structure of the layers of filamentous semi-crystalline polymer cloths and are not-homogeneous and not monolithic due to the presence of regular interlaminar adhesion zones. A disadvantage of such prior art armor components is that, due to the molecular structure of the laminated highly oriented polymers, adhesives are

ineffective for attaching other armor components to such layers. Thus, such armor components are provided as homogenous plates or inserts held in a pouch or pocket without an additional intimately associated armor component.

In contrast, a second layer 30 of the present invention is generally a monolithic homogeneous product of a randomly crystallized semi-crystalline polymer, where polymer crystals of various sizes, shapes and orientations are formed inside an elastomer matrix. Further, the structure of a second layer 30 of the present invention generally allows adhesives to make effective adhesive contact with second layer 30 (in some embodiments a primer or adhesion promoter is required, vide infra) of the present invention, allowing formation of a unitary component 28 including a first layer 12 and a second layer 30.

Generally, a first layer 12 of the present invention is substantially a plate, whether curved, flat, comprising one or more substantially planar surfaces, or a combination thereof. So as to avoid formation of weak points, and allow substantially contiguous contact of a second layer 30 with first layer 12, second layer 30 is generally substantially a plate that is substantially parallel to first layer 12.

In an embodiment of the present invention, an armor component 32 depicted in perspective in Figure 3A and in cross section in Figure 3B, a second layer 30 is substantially box-shaped. By box-shaped is meant that in addition to having a substantially plate-like bottom 34 in contact with a first layer 12, second layer 30 has walls 36 extending from plate-like bottom 34 so as to at least partially surround edges 38 of first layer 12. Such a box-shape eases assembly and protects the corners of first layer 12 from chipping, breaking or other damage during handling and use.

It is preferred that a second layer, e.g. 30 or 34 be rigid. When a second layer 30 or 34 is rigid, the shape of a respective unitary component (e.g., 28 or 32) is not dependent on the structural integrity of a respective first layer 12. A rigid second layer 30 or 34 is exceptionally preferred for embodiments where first layer 12 dissipates energy by a fracture energy mechanism that shatters first layer 12. If a second layer is not rigid, the respective unitary component collapses, providing little protection from succeeding kinetic threats.

In general, it is preferred that a second layer of the present invention be tough and not frangible. Thus, it is generally preferred that a second layer have a room temperature notched Izod impact strength of greater than about 100 J m ^"1 , greater than

about 150 J m ^"1 , greater than about 200 J m ^'1 , greater than about 400 J m ^"1 , greater than about 600 J m ^"1 , greater than about 800 J m ^"1 and even greater than about 1000 J in ¹ .

In embodiments of the present invention, a hitherto unreported method of dissipating energy of a kinetic threat is utilized. The method is based on providing a relatively frangible second layer, that is, a second layer having a room temperature notched Izod impact strength of less than about 100 J m ^" , less than about 80 J m ^"1 and even less than about 70 J m ^"1 .

The method of dissipating energy of a kinetic threat of the present invention is schematically depicted in Figures 4 A through 4C for an armor component 40 provided with a first layer 12 as described above and a second layer 42 made of substantially a frangible non-filamentous semicrystalline polymer. Just as with other armor components of the present invention, in a first step an incoming kinetic threat 16 impacts with first layer 12. Energy is dissipated by deformation of kinetic threat 16 such as by formation of fractures 18 and comminution 20 of first layer 12. Residual impact energy not dissipated by first layer 12 is transferred to second layer 42. In addition to elastic deformation as discussed above for other embodiments of the present invention, second layer 42 delaminates from first layer 12 and breaks in the vicinity of the shock wave projected through first layer 12, dissipating energy and ejecting a harmless spall 44. The method is exceptionally useful when integrated with a first layer made of a glass-ceramic such as disclosed in U.S. Patent application 10/928,723 published as U.S. 20050119104 of the inventor that dissipates the energy of a kinetic threat by a localized pulverization energy mechanism with little or no fracturing. When such a glass-ceramic is used as a first layer 12 together with a second frangible layer 42 in accordance with the teachings of the present invention as described hereinbelow in the experimental section, a neat, localized and harmless polymer spall is ejected from the second layer with substantially no damage to the remainder of the second layer.

Thus, the teachings of the present invention also provide an innovative method for protecting an object from a kinetic threat comprising providing the object with armor including at least two layers, a first layer positioned and configured so as to absorb energy from an impacting kinetic threat and a second frangible layer

configured to absorb the energy from the first layer and to dissipate at least some of the energy by breaking to form at least one harmless spall.

Semi-crystalline polymers suitable for use as components of a second layer of the present invention include, but are not limited to acetal, liquid crystal polymers, maleic anhydride grafted polypropylene, polyamides, Nylons, Nylon 4,6, Nylon 6, Nylon 6,6, Nylon 11, Nylon 12, poly(arylamide), polyethylene, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polyphthalamide, polypropylene, poly(vinylidene fluoride), poly (p-phenylene-2,6-benzobisoxazole), poly (p-phenylene-2,6-benzobisthiazole) and mixtures thereof. The teachings of the present invention are applicable for protecting many different types of objects from many different types of kinetic threats. That said, one object of the present invention is to provide protection from multiple hits of kinetic threats up to and including rifle bullets. Therefore, the first layer is typically between about 5 mm and about 25 mm thick or even between about 5 mm and about 10 mm thick.

Further, the second layer is typically thicker than about 2 mm, thicker than about 5 mm and even thicker than about 7 mm but also typically thinner than about 40 mm, thinner than about 30 mm and even thinner than about 25 mm.

In embodiments of the present invention the first layer and the second layer are directly bonded so as to form a unitary component, as depicted in Figures 2A-2C, 3A-3B and 4A-4C.

In embodiments of the present invention, depicted in Figure 5, an armor component 46 of the present invention, provided with a first layer 12 as described above, a second layer 42 as described above of a non-filamentous semi-crystalline polymer and a third adhesive layer 48 disposed between first layer 12 and second layer 42, preferably substantially attaching first layer 12 to second layer 42. The thickness of third adhesive layer 48 is dependent on the nature of first layer 12, second layer 42, third adhesive layer 48 and the requirements to ensure that first layer 12 and second layer 42 be tenaciously attached. That said, third adhesive layer 48 is generally thinner than about 2 mm, thinner than about 1 mm, thinner than about 0.5 mm, thinner than about 0.2 mm, or even thinner than about 0.1 mm. In some embodiments, third layer is only a few, even one adhesive molecule thick.

Suitable adhesives include, but are not limited to, thermosetting resins and thermoplastic resins.

Typical suitable thermoplastic resins useful for implementing a third adhesive layer of the present invention include but are not limited to alkyds such as those derived from esterification of polybasic acids, as for example, phthalic anhydride, fumaric acid, maleic anhydride, isophthalic acid, terephthalic acid, trimesic acid, hemimellitic acid, succinic anyhydride, fatty acids derived from mineral or vegetable oils and the like, and polyhydric alcohols as for example glycerol, ethylene glycol, propylene glycol, pinacol, 1 ,4-butanediol, 1,3 -propanediol, sorbitol, pentaerythritol, 1,2-cyclohexanediol and the like. Other useful thermosetting resins are acrylics such as crosslinkable polyacrylics, polyacrylates, epoxydiacrylates, urethane diacrylates and the like. Still other useful thermosetting resins are amino resins derived from reaction between formaldehyde and various amino compounds such as melamine, urea, aniline, ethylene urea, sulfonamide, dicyanodiamide and the like. Other useful thermosetting resins include urethanes derived from reaction of polyisocyanates or diisocyanates such as 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, 4,4'- diphenyl-methane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and the like, and polyols such as glycerin, ethylene glycol, diethylene glycol, trimethylolpropane, 1,2,6-hexanetriol, sorbitol, pentaerythritol and the like. Still other typical suitable thermoplastic resins useful for implementing a third adhesive layer include but are not limited to unsaturated polyesters derived from reaction of dibasic acids such as maleic anhydride, fumaric acid, adipic acid, azelaic acid and the like, and dihydric alcohols such as ethylene glycol and propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, diethylene glycol, dipropylene glycols and the like; and silicones such as dimethyldichlorosilane and the like.

Yet another class of useful thermosetting resins are epoxies based on saturated or unsaturated aliphatic, cycloaliphatic, aromatic and heterocyclic epoxides. Useful epoxides include glycidyl ethers derived from epichlorohydrin adducts and polyols, particularly polyhydric phenols. Another useful epoxide is the diglycidyl ether of bisphenol A. Additional examples of useful polyepoxides are resorcinol diglycidyl ether, 3,4-epoxy-6-methylcyclohexylmethyl-9, 10-epoxystearate, 1 ,2,-bis(2,3-epoxy-2- methylpropoxy) ethane, diglycidyl ether of 2,2-(p-hydroxyphenyl) propane, butadiene dioxide, dicyclopentadiene dioxide, pentaerythritol tetrakis(3,4-

epoxycyclohexanecarboxylate), vinylcyclohexene dioxide, divinylbenzene dioxide, 1,5-pentadiol bis(3,4-epoxycyclo-hexane carboxylate), ethylene glycol bis(3,4- epoxycyclo-hexane carboxylate), 2,2-diethyl-l,3-propanediol bis(3,4- epoxycyclohexanecarboxylate), 1,6-hexanediol bis(3,4- epoxycyclohexanecarboxylate), 2-butene-l,4-diol bis(3,4-epoxy-6- methylcyclohexanecarboxylate), 1,1,1 -trimethylolpropane tris(3 ,4- epoxycyclohexanecarboxylate), 1,2,3-propanetriol tris(3,4- epoxycyclohexanecarboxylate), dipropylene glycol bis(2-ethylexyl-4,5- epoxycyclohexane-l,2-dicarboxylate), diethylene glycol bis(3,4-epoxy-6- methylcyclohexanecarboxylate), triethylene glycol bis(3,4- epoxycyclohexanecarboxylate), 3,4-epoxycyclohexyl-methyl 3,4- epoxycyclohexanecarboxylate, 3 ,4-epoxy- 1 -methy lcyclohexylmethyl 3 ,4-epoxy- 1 - methylcyclohexane-carboxylate, bis(3,4-epoxycyclohexylmethyl)pimelate, bis(3,4- epoxy-6-methylenecyclohexylmethyl) maleate, bis(3,4-epoxy-6- methylcyclohexylmethyl) succinate, bis(3,4-epoxycyclohexylmethyl)oxalate, bis(3,4- epoxy-6-methylcyclohexylmethyl) sebacate, bis(3,4-epoxy-6- methy lcyclohexylmethyl) adipate, bis(3,4-epoxycyclo-hexylmethyl) terephthalate, 2,2'-sulfonyldiethanol bis(3,4-epoxycyclohexanecarboxylate), N,N'-ethylene bis(4,5- epoxycyclohexane-l,2-dicarboximide), di(3,4-epoxycyclohexylmethyl) 1,3- tolylenedicarbamate, 3,4-epoxy-6-methylcyclohexanecarboxaldehyde acetal, 3,9- bis(3,4-epoxycyclohexyl) spirobi-(methadioxane), and the like.

Useful thermosetting resins also include phenolic resins produced by the reaction of phenols and aldehydes. Useful phenols include phenol, o-cresol, m-cresol, p-cresol, p-tertbutylphenol, p-tertoctylphenol, p-nonylphenol, 2,3-xylenol, 2,4- xylenol, 2,5-xylenol, 2,6-xylenol, 3,1-xylenol, 3,4-xylenol, resorcinol, bisphenol-A and the like. Useful aldehydes include formaldehyde, acetoldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, glyoxal, furrural and the like.

Other useful thermosetting resins are aromatic vinylesters such as the condensation product of epoxide resins and unsaturated acids usually diluted in a compound having double bond unsaturation such as vinylaromatic monomer as for example styrene and vinyltoluene, and diallyl phthalate. Illustrative of useful vinylesters are diglycidyl adipate, diglycidyl isophthalate, di(2,3-epoxybutyl)adipate, di(2,3-epoxybutyl)oxalate, di(2,3-epoxyhexyl)succinate, d(3,4-epoxybutyl)maleate,

d(2,3-epoxyoctyl)pimelate, di(2,3-epoxybutyl)phthalate, di(2,3- epoxyoctyl)tetrahydrophthalate, di(4,5-epoxy-dodecyl)maleate, di(2,3- epoxybutyl)terephthalate, di(2,3-epoxypentyl)thiodipropionate, di(5,6-epoxy- tetradecyl)diphenyldicarboxylate, di(3,4-epoxyheptyl)sulphonyldibutyrate, tri(2,3- epoxybutyl) 1,2,4 butanetricarboxylate, di(5,6-epoxypentadecyl)maleate, di(2,3- epoxybutyl)azelate, di(3,4-epoxybutyl)citrate, di(5,6-epoxyoctyl)cyclohexane-l ,3- dicarboxylate, di(4,5-epoxyoctadecyl)malonate, bisphenol-A-fumaric acid polyester and the like.

Typical suitable thermoplastic resins useful for implementing a third adhesive layer of the present invention include but are not limited to polylactones such as poly(pivalolactone), poly(ε-caprolactone) and the like; polyurethanes derived from reaction of diisocyanates such as 1,5-naphalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 2,4-toluene diisocyanate, 4,4' diphenylmethane diisocyanate, 3-3'-dimethyl-4,4'diphenyl-methane 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(ethylene adipate), poly(l,4-butylene adipate), poly(l,5-pentylene adipate), poly(l,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 -eye lohexane bis(4-phenyl)carbonate and the like; poly sulfones; polyether ether ketones; polyamides such as poly(4-amino butyric acid), poly(hexamethylene adipamide), poly(6-aminohexanoic acid), poly(m-xylylene adipamide), poly(p-xylylene sebacamide), poly(2,2,2-trimethyl hexamethylene terephthalamide), poly(metaphenyleneisophthalamide), poly(p-phenylene terephthalamide), and the like; polyesters such as poly(ethylene azelate), poly(ethylene-l,5-naphthalate), poly(l,4-cyclohexane dimethylene terephthalate), poly(ethylene oxybenzoate), poly(para-hydroxy benzoate), poly(l,4-cyclohexylidene dimethylene terephthalate), poly(l,4-cyclohexylidene dimethylene terephthalate) polyethylene terephthalate, polybutylene terephthalate and the like; poly(arylene

oxides) such as poly(2,6-dimethyl-l,4-phenylene oxide), poly(2,6-diphenyl-l,4- phenylene oxide) and the like; poly(arylene sulfides) such as poly(phenylene sulfide) and the like; polyetherimides; thermoplastic elastomers such as polyurethane elastomers, fluoroelastomers, butadiene/acrylonitrile elastomers, silicone elastomers, polybutadiene, polyisobutylene, ethylene-propylene copolymers, ethylene-propylene- diene teφolymers, polychloroprene, polysulflde 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 polystyrene-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, polyvinyl-idene 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), polyacryl-amide, 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-l-pentene) and the like; ionomers; and polyepichlorohydrins; polycarbonates and the like.

In some instances it is known that it is difficult to find an adhesive that effectively adheres to a second layer. This is due to the fact that surfaces of some semi-crystalline polymers have a relatively low surface energy and are thus difficult to wet, are nonporous and resistant to most solvents. Therefore, in some embodiments an armor component of the present invention, further comprises at least one adhesion promoter. The use of adhesion promoters is known in the art as well as adhesion promoters suitable for implementing the teachings of the present invention is discussed, for example, in U.S. Patent 6,310,134 and references therein.

In embodiments of the present invention the adhesion promoter is a material that adheres to a second layer 42 and also adheres to a third adhesive layer 48 so as to provide a fourth adhesion promoter layer 50 disposed between second layer 42 and

third adhesive layer 48, Figure 6. In such an embodiment the adhesion promoter is often termed a primer. Typical such adhesion promoters include but are not limited to maleic anhydride, phthalic anhydrides such as hexahydro-4-methylphthalic anhydride (CAS 19438-60-9), silane primers (generally a mixture of one or more reactive silanes, a condensation catalyst and a solvent carrier) and chlorinated olefin adhesion promoters. Adhesion promoters are commercially available from a number of sources including, for example, Eastman Chemical Company (Kingsport, Tennessee, USA).

In embodiments of the present invention, a second layer comprises at least one adhesion promoter, that is to say that blended inside the second layer is a material that enhances the adhesion of some adhesive to that second layer. Suitable such adhesion promoters are known to one skilled in the art. For example, in embodiments of the present invention, maleic anhydride is used as an adhesion promoter that is blended with a polyamide second layer to promote adhesion of the second layer to an epoxy third adhesive layer. In embodiments of the present invention, a third layer comprises at least one adhesion promoter, that is to say that mixed inside the third layer is a material that enhances adhesion to a respective second layer. Suitable such adhesion promoters are known to one skilled in the art.

In some instances a given type of non-filamentous semi-crystalline polymer is found to be too frangible and not sufficiently tough for implementing the teachings of the present invention. In such cases it is desirable to increase the toughness of the polymer. For example, polyamides are often toughened by the absorption of water, for example by soaking the polymer in water. A more generally applicable method of reducing frangibility and toughening non-filamentous semi-crystalline polymers is by the addition of impact modifiers, including as dispersions, as polymer blends, as copolymers and as graft copolymers. The use of impact modifiers for various types of polymers is known to one skilled in the art. For example, the use of impact modifiers for polyamides is discussed by Akkapeddi in Chapter 8 of Baker W.E., Scott, C.E.; Hu, G.-H. (editors) "Reactive Polymer Blending" (2001), Carl Hanser Verlag, Munich, Germany.

In embodiments of the present invention, the second layer comprises at least one impact modifier, that is to say, the second layer includes (for example, as a dispersion, as a blend, as a copolymer, as a graft copolymer) a material that increases

the toughness of the second layer, generally by introducing an additional elastomer phase to the second layer. Typical such impact modifiers include but are not limited to polybutene polymers, methyl methacrylate/butadiene/styrene based resins (MBS), maleated ethylene-propylene rubber (EPR), ethylene-ethyl acrylate-maleic anhydride (E-EA-MA) terpolymer, ethylene-glycidyl methacrylate copolymer (E-GMA), ethylene-ethyl acrylate-glycidyl methacrylatye terpolymer (E-EA-GMA), ethylene- acrylic acid copolymers (E-AA), ethylene-ethyl acrylate (E-EA) copolymers, ethylene butyl acrylaet (E-EB) copolymers, acrylic based impact modifiers (AIMS), acrylonitrile/butadiene/styrene based graft copolymers (ABS), ethylene/vinyl acetate based graft copolymer (EVA), methylmethacrylate/acrylonitrile/butadiene/styrene based copolymers (MABS), butadiene/styrene based copolymers (BS), methacrylate/butadiene based copolymers (MB), methylmethacrylate/acrylate/acrylonitrile based copolymers (MAA), methylmethacrylate/acrylate/acrylonitrile based copolymers with zinc ionomers (MAAZn), chloropolyethylene based copolymers (CPE); block copolymers based on styrene/butadiene/rubber (SBR) and styrene/ethylene/butene/styrene block copolymers (SEBS), ethylene/propylene/diene monomer (EPDM) and butyl acrylate based polymer modifiers modified with siloxane and/or butadiene monomers in the core, and as discussed in U.S. patents 3,388,186; 3,456,059; 3,845,163; 3,963,799; 3,976,720; 4,305,865; 4,339,555; 4,427,832; 4,174,358; 4,305,865; 4,404,325; 4,594,386 and 4,537,929.

In an embodiment of the present invention, the second layer consists essentially (and even consists entirely) of non-filamentous semi-crystalline polymers. In an embodiment of the present invention the second layer is substantially devoid of materials that are not non-filamentous semi-crystalline polymer.

In an embodiment of the present invention, the second layer comprises at least one additional material (e.g., particulate or fibrous) trapped within the non- filamentous semi-crystalline polymer, especially dispersed, especially randomly dispersed within the non-filamentous semi-crystalline polymer so as to be homogeneous (as opposed to a distinct layer of oriented fibrous material, e.g., a cloth layer). Such additional materials are known to change various physical properties of polymers. It is important to note that since it is generally desired that the second layer be tough and not frangible, and it is generally preferred that the second layer be as

light as possible, the second polymer layer generally comprises less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of the at least one additional material. Specifically, in embodiments of the present invention the second layer includes less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of a particulate material trapped therein.

In an embodiment of the present invention, at least one of the at least one additional materials is fibrous. Specifically, in embodiments of the present invention the second layer includes less than about 30% by weight, less than about 20% by weight, less than about 10% by weight, less than about 5% by weight and even less than about 2% by weight of a fibrous material trapped therein. Typical fibrous materials useful in implementing the teachings of the present invention include but are not limited to filaments of non-alkaline aluminoborosilicate, alumina fibers which include "saffil" fiber in ε, δ, and θ phase form, asbestos, non-alkaline barium boroalumina, boron, cadmium borate, carbon nanotubes, ceramic fibers, glass fibers, inorganic fibers, non-alkaline iron aluminosilicate, non-alkaline lead boroalumina, lead silicate, magnesia alumuninosilicate fibers, metal fibers, nylon fibers, polymer fibers, polyacrylonitrile, poly(arylamide), polyethylene, polypropylene, polyvinyl alcohol, potassium titanate whisker, quartz fibers, semimetallic, silicon carbide, soda borosilicate, soda lime-aluminosilicate, soda silicate, stainless steel, non-alkaline zinc boroalumina, as well as graphite and carbon fibers, including such as those derived from the carbonization of polyethylene, polyvinylalcohol, saran, aramid, polyamide, polybenzimidazole, polyoxadiazole, polyphenylene, PPR, petroleum and coal pitches (isotropic), mesophase pitch, cellulose and polyacrylonitrile,

In an embodiment of the present invention, the at least one additional material is particulate. Typical useful particulate materials include but are not limited to particles of bucky-balls, carbonates (e.g., calcium carbonate, magnesium carbonate, dolomite), ceramic-type materials (e.g., borides, carbides, nitrides, aluminum boride, silicon boride, titanium diboride, aluminum carbide, beryllium carbide, boron carbide, iron carbide, silicon carbide, tantalum carbide, titanium carbide, zirconium carbide, aluminum nitride, boron nitride, iron nitride, silicon nitride, titanium nitride, titanium niobate, barium titanate, calcium titanate, cordierite/MAS, lead zirconate titanate /

PLZT, alumina-titanium carbide, alumina-zirconia, zirconia-cordierite / ZrMAS), crystalline materials, glass, glass beads, glass flakes, graphite, metals (e.g., aluminum, iron, tungsten, cobalt), metal oxides (e.g., alumina, barium oxides, beryllium oxides, calcium oxides, cerium oxides, chromium oxides, dysprosium oxides, erbium oxides, europium oxide, gadolinium oxide, hafnium oxide, holmium oxide, lanthanum oxide, lutetium oxide, magnesium oxide, neodymium oxide, niobium oxides, praseodymium oxides, promethium oxide, samarium oxides, scandium oxide, silicon dioxide, strontium oxide, tantalum oxide, terbium oxides, thorium oxide, thulium oxide, titanium oxides, uranium oxides, vanadium oxides, ytterbium oxides, yttrium oxides, and zirconium oxide), minerals (e.g., alumina silicate, asbestos, bentonite, clay, kaolin, mica, sericite, silicates, talc, wollastonite), organic fibers (e.g., poly(arylamide)), sulfates (e.g., calcium sulfate and barium sulfate) and other particulate fillers such as those described in CF. Liable, Ballistic Materials and Penetration Mechanics, Chapters 5-7 (1980) ) In an embodiment of an armor component of the present invention, the armor component comprises a fifth cloth layer (e.g., a woven textile or a non-woven cloth) including strands of fibers (e.g., polyamide fibers, poly(arylamide) fibers, polyethylene fibers). Preferably, the fifth cloth layer is attached to the second layer, preferably on the side of the second layer opposed to the side through which the second layer is attached to the first layer. In an embodiment of the present invention, the fifth cloth layer is impregnated with at least one adhesive material so as to allow adhesion to the armor component, especially to the second layer. In embodiments of the present invention, the fifth cloth layer is attached to the second layer by being attached to, or pressed into, or encased in, or embedded in the second layer, proximately to or at the side of the second layer opposed to the side through which the second layer is attached to the first layer. In Figure 7 is depicted an armor component of the present invention, provided with a first layer 12 as described above, a second layer 30 as described above of a non-filamentous semi-crystalline polymer, a third adhesive layer 48 disposed between first layer 12 and second layer 30 and a fifth cloth layer 52. v

Generally, an article of the present invention incorporating an armor component of the present invention is fashioned in a useful shape that is determined by the expected use, for example as an armor plate, an armor sheet, a bullet-proof

vest, body armor, a panel, a door panel, a floor panel, a wall panel, a helmet, a seat, an aircraft, a rotary wing aircraft, a fixed wing aircraft, an armored fighting vehicle, a limousine and a motor vehicle.

An article of the present invention as described above is useful for protecting an object from a kinetic threat. The method of protecting an object from a kinetic threats comprising providing the object with armor, the armor including an article or an armor component as described above. Preferably, the first layer is positioned so as to serve as a strike-face of the armor.

Method of making an article of the present invention

The teachings of the present invention also provide a method of making an article suitable for protecting an object from a kinetic threat comprising: a) providing a first component, the first component including (or substantially comprising or even consisting essentially of) a material selected from the group consisting of ceramic matrix composites, monolithic ceramics, glass-ceramics, ceramics and glass; b) providing a second component, including at least one non-filamentous semi-crystalline polymer; and c) attaching the first component to the second component so as to form a unitary armor component of the article.

As stated above, suitable non-filamentous semi-crystalline polymers include but are not limited to acetal, liquid crystal polymers, maleic anhydride grafted polypropylene, polyamides, Nylons, Nylon 4,6, Nylon 6, Nylon 6,6, Nylon 11, Nylon 12, poly(arylamide), polyethylene, polybutylene terephthalate, polyethylene terephthalate, polyphenylene . sulfide, polyphthalamide, polypropylene, poly(vinylidene fluoride), poly (p-phenylene-2,6-benzobisoxazole), poly (p- phenylene-2,6-benzobisthiazole) and mixtures thereof.

Generally, the second component is provided by: i) providing a semi- crystalline polymer resin (that is, a resin that is a precursor for a semi-crystalline polymer); ii) melting the semi-crystalline polymer resin to yield a molten polymer; iii) transforming the molten polymer into a semi-crystalline polymer; and iv) shaping the semi-crystalline polymer into the shape of the second component. It is important to

note that in some cases at least part of step (iii) and at least part of step (iv) occur substantially simultaneously, vide infra.

Generally, transforming the molten polymer into a semi-crystalline polymer includes cooling the molten polymer, so that the desired structure of polymer crystals trapped in an elastomer matrix is formed.

Preferred methods for shaping the semi-crystalline polymer into the shape of the second component include methods known in the art of polymers such as molding, injection molding, compression molding and extrusion of the molten polymer, preferably injection molding. It is important to note, for example, that in injection molding both the shaping of the second component and the transformation of the molten polymer into a semi-crystalline polymer occur, at least in part, substantially simultaneously.

It is important to note that unlike prior art methods of making armor and armor components including semi-crystalline polymers, in the method of the present invention, subsequent to melting of the semi-crystalline polymer resin, the molten resin is generally not formed into a filament.

It is known that polyamide polymers, such as Nylons, absorb moisture subsequent to molding. Water absorbed by polyamides acts as a plasticizer, toughening the polymer. Thus in an embodiment of the present invention, when the non-filamentous semi-crystalline polymer is a polyamide such as Nylon, providing the second component includes, absorbing water, for example by soaking the solidified polyamide in water. Generally, during at least part of the soaking, the water is maintained at a temperature of greater than about 50 ⁰ C, greater than about 80 ⁰ C, or even greater than about 90 ⁰ C. In an embodiment of the present invention, attaching the first and second components includes contacting the first component with the second component so as to cause the second component to adhere to the first component. Such an embodiment is useful when the two components are mutually adherent, or for example, when localized melting of only the contact surface of the second layer yields a sufficiently tenacious attachment of the two components to yield a unitary armor component.

In an embodiment of the present invention, attaching the first and second components includes, during the transforming of the molten polymer into the semi- crystalline polymer, maintaining contact of the incipient semi-crystalline polymer

making up the incipient second component with the first component. Generally such an embodiment is useful when the first component is placed inside a mold wherein the molten polymer is placed for molding, or when the first component substantially serves as one section of a mold. Such an embodiment is most useful when the coefficients of thermal expansion of the first component and of the second component are substantially similar.

In an embodiment of the present invention, attaching the first component and the second component includes using at least one adhesive (e.g., a thermosetting resin or a thermoplastic resin as discussed hereinabove) to attach the first component to the second component. In an embodiment of the present invention, using an adhesive includes applying the adhesive, for example by spraying the adhesive, painting the adhesive, brushing the adhesive, depositing the adhesive, pouring the adhesive or laying a sheet of adhesive onto one or both of the two components. Generally the two components are subsequently brought together and held tightly in place, often with heating, until the adhesive sets. In an embodiment of the present invention, an adhesion promoter is applied to the contact surface of the second component so as to increase the tenacity of adhesion of the adhesive to the second component.

In an embodiment of the present invention, the second component includes at least one adhesion promoter. In an embodiment of the present invention the semi- crystalline polymer resin provided includes the at least one adhesion promoter. In an embodiment of the present invention, at least one adhesion promoter is added to the molten polymer. In an embodiment of the present invention, at least one adhesion promoter is added to the adhesive.

In an embodiment of the present invention, the second component includes at least one impact modifier. In an embodiment of the present invention the semi- crystalline polymer resin provided includes at least one impact modifier. In an embodiment of the present invention, at least one impact modifier is added to the molten polymer. Examples of suitable impact modifiers include those listed hereinabove. In an embodiment of the present invention, the second component includes at least one additional material selected from the group consisting of particulate materials and fibrous materials. In an embodiment of the present invention the semi- crystalline polymer resin provided includes at least one additional material selected

from the group consisting of particulate materials and fibrous materials. In an embodiment of the present invention, at least one additional material selected from the group consisting of particulate materials and fibrous materials is added to the molten polymer. Examples of suitable particulate materials and fibrous materials include those listed hereinabove.

Generally, the first component and the second component are integrated into an article for protecting an object from a kinetic threat. Preferably, the two components are integrated into an article for protecting an object from a kinetic threat as the unitary armor component. Typical articles in which the components are integrated include but are not limited to armor plates, armor sheets, bullet-proof vests, body armor, panels, door panels, floor panels, wall panels, helmets, seats, aircraft, rotary wing aircrafts, fixed wing aircrafts, armored fighting vehicles, limousines and motor vehicles.

Proof of Concept

To confirm that the teachings of the present invention provide protection from kinetic threats, unitary armor plates comprising a 1 cm thick first layer of an Anorthite

/ TiO ₂ glass-ceramic and various second layers used as inserts in conjunction with level 3A-type vests were tested for ballistic penetration and backface deformation of a plasticine block.

Four types of unitary armor plates, each type having a different second layer were tested: a prior art poly(arylamide) spall liner, an impact modified Nylon 6

(maleic anhydride grafted, ethylene-propylene rubber) second layer of the present invention, an acetal second layer of the present invention and a polyethylene terephthalate (PET) second layer of the present invention.

Each test involved firing six consecutive kinetic threats at the tested plates. In the first test, the kinetic threats were NATO ball M80 bullets. In the second test, the kinetic threats were SS109 5.56mm AP bullets. In the third test the kinetic threats were AK47 1943 7N23 AP bullets. The results of the three tests are described hereinbelow and in Table 1.

In the first test, six NATO ball M80 rounds were fired at one of each of the four types of armor plate impacting at about 850 m sec ^"1 . Of the three tests, the impact of the M80 bullets is the most energetic. In all cases, the bullets penetrated into the

glass-ceramic first layer and caused complete comminution of the glass-ceramic in a 1 cm radius about the impact point. All three unitary armor plates of the present invention provided protection superior to that of the prior art armor plate. In the armor plate with the impact modified Nylon 6 second layer all six bullets produced a backface deformation of less than 10 mm, in the armor plates with the PET and acetal second layers all six bullets had no backface deformation while in the armor plate with the prior art spall liner all six bullets had a backface deformation of up to about 40 mm. One penetration occurred through the armor plate with the prior art spall liner. No penetration of any hard fragments occurred through any of the three unitary armor plates of the present invention.

Interestingly, impact of the M80 bullets on the armor plates with the PET and acetal second layer caused ejection of a 1 cm substantially cylindrical relatively smooth edged spall from the second layer, as schematically depicted in Figure 4C. The edge of the spall was substantially a mirror image of the terminal end of the glass-ceramic comminution zone. The spall was captured by the vest in which the armor plate was inserted.

In the second test, SS- 109 rounds (5.56 mm with a tungsten carbide armor- penetrating core) were fired at the armor plates having an impact modified Nylon 6 second layer and the prior art spall liner, impacting at about 1000 m sec ^"1 . In all cases, the bullets penetrated into the glass-ceramic first layer and caused complete comminution of the glass-ceramic in a 1 cm radius about the impact point. No hard fragments passed through either of the second layers nor contacted the clay. The armor plate of the present invention provided protection superior to that of the prior art armor plate. In the armor plate of the present invention with the impact modified Nylon 6 second layer all six bullets had no backface deformation, whereas the armor plate with the prior art spall liner had a backface deformation of less than 20 mm.

In a third test, six AK47 1943 7N23 AP rounds (7.62 mm armor piercing) were fired at the armor plates having the impact modified Nylon 6 second layer and the prior art spall liners impacting at about 740 m sec ^"1 . In all cases, the bullets penetrated into the glass-ceramic first layer and caused complete comminution of the glass-ceramic in a 1 cm radius about the impact point. The armor plate of the present invention provided protection superior to that of the prior art armor plate. In the armor plate of the present invention all six bullets caused no backface deformation. In the

armor plate with the prior art spall liner five bullets caused a backface deformation of greater than 20 mm with the last bullet penetrating into the clay.

Table 1: Comparative backface deformation of armor plates of the present invention showing trauma depth of six impacts in mm

As is seen from the results, an armor plate made in accordance with the teachings of the present invention provides superior protection from kinetic threats than does a comparable prior art armor plate. The superior protection is achieved despite the fact that the price of the raw materials for producing a prior art spall liner is significantly higher than the price of the raw materials for producing a second layer of the present invention. Further, the method of producing a prior art spall liner and attaching the spall liner to a ceramic plate to make a unitary armor plate is significantly more complex than the same using a second layer of the present invention.

Interestingly it is seen that different types of semi-crystalline polymers dissipate the impact energy of a kinetic threat in different ways. The relatively flexible but tough impact modified Nylon 6 (room temperature notched Izod impact strength ~2000 J m ^" ) dissipates the energy as anticipated by absorbing and dissipating energy by elastic deformation, apparently in the amorphous phase. In contrast, the relatively rigid PET (room temperature notched Izod impact strength 35 J m ^"1 ) and acetal (room temperature notched Izod impact strength 80 J m ^"1 ) dissipated the energy by elastic deformation and also by the breaking of chemical bonds of the polymer and ejection of a harmless polymer spall. This surprising behavior provides a heretofore- undisclosed energy dissipating mechanism for neutralizing kinetic threats of the present invention.

In conclusion, it has been demonstrated that an armor plate of the present invention is cheaper, easier to make and yet provides protection from kinetic threats that is superior to the protection provided by an armor plate having a comparable prior art spall liner.

EXAMPLES

Reference is now made to the following example that, together with the above description, illustrate the invention in a non-limiting fashion.

MA TERIALSAND EXPERIMENTAL METHODS

Materials:

Impact modified Nylon 6 resin (including 22% by weight ethylene propylene copolymer and 5% by weight maleic anhydride) producing impact modified Nylon 6 (PB890BK10) having a room temperature notched Izod impact strength of 1100 J m ^"1 (before absorption of water) was purchased from Polyram (Moshav Ram On, Israel).

Ultraform® acetal copolymer resin producing an acetal copolymer having a room temperature notched Izod impact strength of 80 J m ^"1 was purchased from BASF AG (Ludwigshafen, Germany).

Valox® PET resin producing a PET polymer having a room temperature notched Izod impact strength of 35 J m ^"1 was purchased from GE Plastics (Fairfield, CT, USA).

Coal ash was obtained from the Rutenberg Power Plant (Ashkelon, Israel), the plant burning coal supplied by TotalFinaElf S. A., South Africa. The composition of the coal ash was SiO ₂ (46.5 % by weight), Fe ₂ O ₃ (3.7 % by weight), Al ₂ O ₃ (30.1% by weight), TiO ₂ (1.6 % by weight), CaO (10 % by weight), MgO (1.9 % by weight), SO ₃ (2.3 % by weight), Na ₂ O (0.2 by weight), P ₂ O ₅ (2.2 by weight), and K ₂ O (0.4 % by weight).

Rutile sand was obtained from Richards Bay Iron and Titanium (PTY) Ltd. (Richards Bay, Republic of South Africa). The composition of the Rutile sand was TiO ₂

(89 % by weight), Fe ₂ O ₃ (2.5 % by weight), ZrO ₂ (2 % by weight), P (0.04% by weight),

S (0.008% by weight), SiO ₂ (3% by weight), Al ₂ O ₃ (0.88% by weight), CaO (0.25 % by

weight), MgO (0.08 % by weight), Cr ₂ O ₃ (0.14 % by weight), V ₂ O ₅ (0.45 % by weight), MnO (0.03 % by weight) and Nb ₂ O ₅ (0.35 % by weight).

CaCO ₃ was obtained from Negev Industrial Minerals, Ltd. (Omer, Israel).

Preparation of Anorthite/TiO2 glass-ceramic:

79 kg coal ash, 8 kg Rutile sand and 13 kg CaCO ₃ were comminuted and mixed together to make an oxide mixture.

100 kg of the oxide mixture was heated from 1350 ⁰ C to 1520 ⁰ C at a rate of between 50 °C hour ^'1 and 100 °C hour ^"1 in a MG-300 gas-fired glass-melting furnace (Falorni Glass Furnaces, Empoli, Italy). The melt was maintained at 1520 °C for 120 minutes to ensure thorough melting, convective mixing and the conversion of CaCO ₃ to

CaO.

The mixture was cooled to 1450 °C at a rate of 100 °C hour ^'1 and poured into a plurality of press molds to form 10 mm thick curved plates of 300mm x 250 mm and a curvature equivalent to that of a 400mm cylinder. The molten glass was allowed to crystallize for four hours during cooling from 1020 °C to 950 °C at a rate of 30 ⁰ C hour ^'

'. The density of the glass-ceramic plates thus produced was roughly 2.7 kg I ^"1 .

The glass-ceramic plates were subsequently chemically hardened by first etching with a 40% (v/v) HF solution to a depth of between about 100 and 200 microns followed by ion exchange using a 80% KNO ₃ / 20% K ₂ SO ₄ mixture (w/w) at between 500°C and 600°C for four hours.

As detailed in U.S. Patent application 10/928,723 published as U.S. 20050119104 of the inventor, the thus-produced Anorthite / TiO ₂ glass-ceramic plates had a density of 2.7 kg I ^'1 , a thermal coefficient of linear expansion of 52 x 10 ^{'7 0} C ^'1 , a bending strength of 300 MPa, a compressive strength of 1 GPa, an HV hardness of between 9.3 and 10 GPa, a Young's modulus of 100 GPa and a calculated sonic velocity of 6 km sec ^"1 .

Preparation of prior-art unitary armor plate For each prior art armor plate made, a flexible sheet of polyolefϊn adhesive

(catalogue number ADP-422-X from Polyon-Barkai Industries Ltd., Kibbutz Barkai, Israel) was placed on the concave face of a glass-ceramic plate.

A total of twenty sheets of woven poly(arylamide) textile (Twaron® CT microfilaments, Teijin Twaron B.V., Arnhem, The Netherlands) (5 sheets of 2000 denier (190 gram m ² ), 10 sheets of 4000 denier (440 gram m ² ), 5 sheets 2000 denier (190 gram m ² )) each sheet of textile separated from the previous with a flexible sheet of adhesive was prepared. The total thickness of the thus produced textile spall liner was 10 mm. Adhesion to form a unitary component was achieved by placing the entire stack of glass- ceramic, textile and adhesive in a vacuum bag and heating to between about 150 °C and 170 ⁰ C for 1 hour under vacuum. Subsequent to vacuum adhesion, the thickness of the spall layer was reduced to about 8 mm.

Preparation of Nylon opiate

Impact modified Nylon 6 resin was injection molded at a pressure of 120 MPa in the usual way to produce 10 mm thick plates. The size, shape and the curvature of the plates were such that upon cooling and moisture absorption, the impact modified Nylon 6 plates made contiguous contact with the glass-ceramic tiles produced as described above. After cooling, the impact modified Nylon 6 plates were immersed in a water bath maintained at 100°C for a period of 24 hours and again allowed to cool. The waybill indicated that the room temperature notched Izod impact strength of the polymer was between 756 and 794 J m ^"1 . It is estimated that subsequent to immersion in the water bath the notched Izod impact strength of the polymer rose to 1500 - 1600 J m- ¹ .

Preparation of Acetal plate

Acetal resin was injection molded at a pressure of 100 MPa in the usual way to produce 10 mm thick plates. The size, shape and the curvature of the acetal plates were such that upon cooling, the plates made contiguous contact with the glass- ceramic tiles produced as described above.

Preparation of PET plate PET resin was injection molded at a pressure of 100 MPa in the usual way to produce 10 mm thick plates. The size, shape and the curvature of the plates were such that upon cooling, the plates made contiguous contact with the glass-ceramic tiles produced as described above.

Preparation of unitary armor plates of the present invention

For each armor plate, a 1 mm thick layer of maleic anhydride grafted linear low- density polyethylene adhesive (Bondyram 4001, Polyram Ltd., Moshav Ram-On, Israel) was sandwiched between the concave face of a glass-ceramic plate and the convex face of a desired polymer plate of the present invention. Adhesion to form a unitary armor component was achieved by placing the entire sandwich in a vacuum bag and heating to 200 °C under vacuum.

Neutralization of kinetic threats

The various armor plates prepared as described above were tested for ballistic penetration and backface signature when used as an insert in conjunction with a level 3A-type vest against three different kinetic threats according to the procedure described in the NIJ standard-0101.04 (National Institute of Justice, Department of Justice, United States), a procedure involving measuring the deformation of a mass of oil-based modeling clay protected by an armor as a result of the impact of a kinetic threat. In each test, six consecutive kinetic threats impacted a given type of armor plate perpendicularly, each kinetic threat impacting at least 5 cm from other impact points and at least 7.6 cm from the side of the given armor plate. The results of the three tests are also discussed hereinabove and summarized in Table 1.

NATO Ball M80

In a first test, six NATO ball M80 rounds were fired at one of each type of armor plate, impacting at about 850 m sec ^"1 . In all cases, the bullets penetrated into the glass-ceramic and caused comminution of the glass-ceramic plate in a 1 cm radius about the impact point.

In the armor plate with a prior art spall liner, all six rounds produced a backface signature of no more than about 40 mm. Fragments of one of the sixth rounds penetrated through the armor plate.

In the armor plate with an impact modified Nylon 6 second layer, all six bullets produced a backface signature of no more than about 10 mm. No fragments passed through the second layer.

In the armor plates with a PET second layer and an acetal second layer, a 1 cm radius substantially cylindrical relatively smooth edged spall of the respective polymer was ejected from the second layer. All six bullets produced no backface signature.

SS-109

In a second test, six SS-109 rounds (5.56 mm with a tungsten carbide armor- penetrator) were fired at armor plates having a prior art spall liner and an impact modified Nylon 6 second layer, impacting at about 1000 m sec ^"1 . In all cases, the bullets penetrated into the glass-ceramic and caused comminution of the glass- ceramic plate in a 1 cm radius about the impact point.

In the armor plate with the prior art spall liner, all six bullets produced a backface signature of no more than about 20 mm. No fragments passed through the spall liner. In the armor plate with the impact modified Nylon 6 second layer, all six bullets produced no backface signature. No fragments passed through the second layer.

AK-47 AP In a third test, six AK-47 1943 7N23 AP rounds (7.62 mm armor piercing) were fired at armor plates having a prior art spall liner and an impact modified Nylon

6 second layer, impacting at about 740 m sec ^"1 . In all cases, the bullets penetrated into the glass-ceramic and caused comminution of the glass-ceramic plate in a 1 cm radius about the impact point. In the armor plate with the prior art spall liner, the six bullets produced a backface signature of up to about 20 mm.

In the armor plate with the impact modified Nylon 6 second layer, all six bullets produced no backface signature. No fragments passed through the second layer.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention,

which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.