BALLISTIC COMPOSITE CONTAINING A THERMOPLASTIC OVERLAY
Ballistic composite articles comprising a fabric section, an overlay section disposed on the strikeface of the composite article and comprising a thermoplastic resin, and optionally an adhesive layer disposed between the fabric section and the overlay section are described. The ballistic composite articles can provide comparable or improved protection against projectile threats relative to conventional ballistic composites consisting only of a same-type fabric section having comparable area density, as evidenced by comparable V50 values and/lower backface deformation values when tested under the same conditions.
This application claims priority under 35 U.S.C. §119(e) from, and claims the benefit of, U.S. Provisional Application No. 61/604,763 filed Feb. 29, 2012 and U.S. Provisional Application No. 61/604,741 filed Feb. 29, 2012; both of which are by this reference incorporated in their entirety as a part hereof for all purposes.
FIELD OF THE INVENTIONRigid armor composite structures comprising a fabric section and an overlay section comprising a thermoplastic resin are provided.
BACKGROUNDBallistic articles such as bulletproof vests, helmets, tactical plates, structural members of helicopters, vehicle armor, and other military equipment containing high strength fibers are known. Fibers conventionally used include aramid fibers such as poly(phenylenediamine terephthalamide), glass fibers, nylon fibers, ceramic fibers, and the like. For many applications, such as vests, or parts of vests, the fibers are used in a woven or knitted fabric. For hard armor applications the fibers may be encapsulated or embedded in a matrix material. Phenolic or modified polyester resin can also be added to these high strain ballistic fabrics in order to form composites in which the resin does little more than keep out water.
Published Patent Application GB 2,124,887 discloses a protective shield to be used in front of a person's body to protect the person from injury by a bullet or other missile comprising at least one layer of plastics sheet material and a plurality of layers of woven fabric formed from aramid fibers, in which use of the plastics sheet material is on that side of the aramid fabric layers which faces away from the person's body. The sheet plastics can be of high impact absorbing plastics, for example rigid poly vinyl chloride, acrylonitrile butadiene styrene, or polycarbonate.
U.S. Pat. No. 7,608,322 discloses a composite for resisting impact from an oncoming projectile having a front strike face and a back wear face comprising: an elastomer; and an impact resistive substrate wherein at least a portion of the impact resistive substrate is coated by the elastomer to provide the composite having a front strike face coating and a back wear face coating and wherein a ratio of weight of front strike face coating to back wear face coating ranges from 1:1.2 to 1:100.
There is a continuing need for ballistic composites and articles comprising such composites which provide comparable or improved protection against projectile threats while being more cost effective than conventional ballistic composites.
SUMMARYDescribed herein are ballistic composite articles having a strike face, the composite articles comprising: a fabric section, an overlay section comprising one or more layers, and an optional adhesive layer disposed between the fabric section and the overlay section. The fabric section comprises two or more fibrous fabric layers. The overlay section comprises a thermoplastic resin and is disposed on the strikeface of the composite article. The composite articles provide ballistic performance, with regard to V50 values as determined under test conditions specified herein, comparable to or greater than the ballistic performance of an article consisting only of a same-type fabric section and having an areal density equal to, or about the same as, the areal density of the composite article. The composite articles provide reduced back face deformation as determined under test conditions specified herein, compared to that of an article consisting only of a same-type fabric section and having an areal density equal to, or about the same as, the areal density of the composite article.
In one embodiment, a ballistic composite article having a strikeface and a backface is disclosed, the ballistic composite article comprising:
a) a fabric section comprising two or more fibrous fabric layers;
b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising a thermoplastic resin, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50%; and
c) an optional first adhesive layer disposed between the fabric section and the overlay section;
whereby the composite article, when tested according to MIL-STD-662-F using a 16 grain right circular cylinder fragment-simulating projectile, has a V50 value comparable to or greater than that of an article consisting only of a same-type fabric section having an areal density equal to, or about the same as, the areal density of the composite article.
In one embodiment, a ballistic composite article having a strikeface and a backface is disclosed, the ballistic composite article comprising:
a) a fabric section comprising two or more fibrous fabric layers;
b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface and comprising a thermoplastic resin, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50%; and
c) an optional first adhesive layer disposed between the fabric section and the overlay section;
whereby the composite article, when tested according to HP White HPW-TP-0401.01B using a 9 mm Full Metal Jacket projectile, has a back face deformation value lower than that of an article consisting only of a same-type fabric section having an areal density equal to, or about the same as, the areal density of the composite article.
By “equal to, or about the same as” it is meant that the areal densities of articles being compared are intended to be about the same for purposes of meaningful comparison, not necessarily equal,
The ballistic composite articles described herein are described with reference to the following figures.
The ballistic composite articles disclosed herein are described with reference to the following terms.
As used herein, where the indefinite article “a” or “an” is used with respect to a statement or description of the presence of a step in a process of this invention, it is to be understood, unless the statement or description explicitly provides to the contrary, that the use of such indefinite article does not limit the presence of the step in the process to one in number.
As used herein, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.
The term “composite article”, as used herein, refers to an article that comprises at least two components (i.e. a fabric section and an overlay section) with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure. By “composite article” is meant any type of construction, such as a panel, whether flat or otherwise, and formed or molded products, such as a helmet. The term “composite article” also includes but is not limited to laminates, multilayer structures, matrices, or variants thereof.
The term “strike face” as used herein refers to the surface of the armor that faces the ballistic threat or is otherwise intended to be struck first by a projectile.
The term “back face” as used herein refers to the surface of the armor that is worn toward the body or property to be protected.
The term “back face deformation” as used herein refers to the amount of rearward deformation the armor receives when struck abruptly by a non-penetrating projectile. Back face deformation, abbreviated herein as “BFD”, is also known as “back face signature”. Although the projectile may not penetrate the armor, the part of the body or property to be protected which is directly behind the point of impact usually receives a “hammer-like” blow as a result of the deformation of the armor from the impact of the projectile. This blow can produce not only bruises and lacerations to the surface of the skin, but can produce damage to internal organs. Thus a reduction in the back face deformation of armor can correspond to reduced trauma to the body directly behind the point of projectile impact.
The terms “fibrous fabric” and “fabric”, as used herein, are synonymous and refer to a multilayer construction of fibers.
The term “fiber” as used herein refers to an elongate body the length dimension of which is much greater than the transverse dimensions of width and thickness. Accordingly, the term fiber includes monofilament fiber, multifilament fiber, ribbon, strip, a plurality of any one or combinations thereof and the like having regular or irregular cross-section.
The term “thermoplastic” as used herein refers to polymers that undergo a transition from solid state to fluid state when heated and freeze to a glass or semi-crystalline state when cooled sufficiently. Thermoplastic polymers can be re-melted and re-molded.
The term “comparable” as used herein refers to numerical values which are within about 20% or alternatively within about 10% of each other.
Disclosed herein is an impact-resistant ballistic composite article comprising a fabric section and an overlay section which, when tested under the conditions specified herein, provides ballistic performance comparable to or greater than that of a comparison article consisting of only the fabric section and having an equal areal density. The overlay section comprises a thermoplastic resin comprising polycarbonate, polyester, thermoplastic elastomeric polyester, polyamide, polyolefin, polysulfone, polyimide, or combinations thereof. The overlay section can comprise one or more layers. Optionally, an adhesive layer is disposed between the fabric section and the overlay section. In one embodiment, the overlay section is disposed on the strikeface of the composite article. In one embodiment, the overlay section encapsulates the fabric section.
The fabric section of the ballistic composite article comprises two or more fibrous fabric layers. The fibrous layers may comprise bundles of fibers that are assembled to form a fibrous layer. The fiber type is determined by the ballistic properties required of the composite article. The fabric section of the ballistic composite comprises fiber that can be woven or nonwoven and can further comprise an aramid, even poly(p-phenylene terephthalamide), or ultra-high molecular weight polyethylene (UHMWPE). By nonwoven it is meant that in some embodiments the fabric layer can be a unidirectionally oriented structure, such as a cross ply or tape structure, a multi-axial fabric, or a three-dimensional fabric, each of these provided with or without binder. The multi-axial fabric can have layers of yarn oriented at an angle with respect to adjacent layer(s), and these layers can comprise unidirectional arrays of yarns. The three-dimensional fabrics can also comprise unidirectional arrays of yarns. In one embodiment, one or more of the fibrous fabric layers comprises a woven fabric. In one embodiment, one or more of the fibrous fabric layers comprises a non-woven fabric. In one embodiment, the non-woven fabric comprises a unidirectionally oriented tape structure.
The composite ballistic articles can comprise a fabric section comprising a fiber network, the fiber network comprising highly oriented ultra-high molecular weight polyethylene fiber or tape (UHMWPE), highly oriented ultra-high molecular weight polypropylene fiber or tape (UHMWPP), aramid fiber, polyvinyl alcohol fiber, polyazole fiber or combinations or blends, including mixtures of fibers made of different materials or blends of different polymers in one fiber. U.S. Pat. No. 4,457,985 generally discusses oriented ultra-high molecular weight polyethylene and polypropylene fibers, the disclosure of which is hereby incorporated by reference to the extent not inconsistent herewith. In the case of polyethylene, suitable fibers are those highly oriented fibers of weight average molecular weight of at least about 500,000, preferably at least about one million and more preferably between about two million and about six million. Known as extended chain polyethylene (ECPE) fibers, such fibers may be produced from polyethylene solution spinning processes described, for example, in U.S. Pat. No. 4,137,394 to Meihuzen et al. or U.S. Pat. No. 4,356,138 to Kavesh et al., or spun from a solution to form a gel structure as described in German Off. No. 3,004,699, GB No. 2051667, and especially as described in application Ser. No. 259,266 of Kavesh et al. filed Apr. 30, 1981 and application Ser. No. 359,019 (continuation-in-part of Ser. No. 259,266) (see EPA No. 64,167, published Nov. 10, 1982).
As used herein, the term “polyethylene” refers to a predominantly linear polyethylene material that may contain minor amounts of chain branching or comonomers not exceeding 5 modifying units per 100 main chain carbon atoms, and that may also contain admixed therewith not more than about 25 wt % of one or more polymeric additives such as alkene-1-polymers, in particular low density polyethylene, polypropylene or polybutylene, copolymers containing mono-olefins as primary monomers, oxidized polyolefins, graft polyolefin copolymers and polyoxymethylenes, or low molecular weight additives such as anti-oxidants, lubricants, ultra-violet screening agents, colorants and the like which are commonly incorporated therewith.
Depending upon the fiber-forming technique, the draw ratio and temperatures, and other conditions, a variety of properties can be imparted to these fibers. The tenacity of the fibers is ordinarily at least about 15 grams/denier, preferably at least about 20 grams/denier, more preferably at least about 30 grams/denier and most preferably at least about 40 grams/denier. Similarly, the tensile modulus of the fibers, as measured by an Instron tensile testing machine, is ordinarily at least about 300 grams/denier, preferably at least about 500 grams/denier, more preferably at least about 1,000 grams/denier and most preferably at least about 1,500 grams/denier. These highest values for tensile modulus and tenacity are generally obtainable only by employing solution spun or gel fiber processes. In addition, many ECPE fibers have melting points higher than the melting point of the polymer from which they were formed. Thus, for example, whereas ultra-high molecular weight polyethylenes of 500,000, one million and two million generally have melting points in the bulk of 134° C., the ECPE fibers made of these materials have melting points of 145° C. or higher. The increase in melting point reflects a higher crystalline orientation of the fibers as compared to the bulk polymer.
Improved ballistic resistant articles are formed when polyethylene fibers having a weight average molecular weight of at least about 500,000, a modulus of at least about 500 and a tenacity of at least about 15 g/denier are employed. Cf. John V. E. Hansen and Roy C. Laible in “Flexible Body Armor Materials,” Fiber Frontiers ACS Conference, Jun. 10-12, 1974 (ballistically resistant high strength fibers must exhibit high melting point and high resistance to cutting or shearing); Roy C. Laible, Ballistic Materials and Penetration Mechanics, 1980 (noting that nylon and polyester may be limited in their ballistic effectiveness due to the lower melting point); and “The Application of High Modulus Fibers to Ballistic Protection”, R. C. Laible, et al., J. Macromel. Sci. Chem., A7(1), pp. 295-322, 1973 (the importance of a high degree of heat resistance is again discussed).
In the case of polypropylene, highly oriented polypropylene fibers of weight average molecular weight at least about 750,000, preferably at least about one million and more preferably at least about two million may be used. Ultra high molecular weight polypropylene may be formed into reasonably highly oriented fibers by the techniques prescribed in the various references referred to above, and especially by the technique of U.S. Ser. No. 259,266, filed Apr. 30, 1981, and the continuations-in-part thereof, both to Kavesh et al. Since polypropylene is a much less crystalline material than polyethylene and contains pendant methyl groups, tenacity values achievable with polypropylene are generally substantially lower than the corresponding values for polyethylene. Accordingly, a suitable tenacity is at least about 8 grams/denier, with a preferred tenacity being at least about 11 grams/denier. The tensile modulus for polypropylene is at least about 160 grams/denier, preferably at least about 200 grams/denier. The melting point of the polypropylene is generally raised several degrees by the orientation process, such that the polypropylene fiber preferably has a main melting point of at least about 168° C., more preferably at least about 170° C. Employing fibers having a weight average molecular weight of at least about 750,000 coupled with the preferred ranges for the above-described parameters (modulus and tenacity) can provide advantageously improved performance in the final article especially in ballistic resistant articles. C. f. Laible, Ballistic Materials and Penetration Mechanics, supra, at p. 81 (no successful treatment has been developed to bring the ballistic resistance of polypropylene up to levels predicated from the yarn stress-strain properties); and the relative effectiveness of NTIS publication ADA018 958, “New Materials in Construction for Improved Helmets”, A. L. Alesi et al. [wherein a multilayer highly oriented polypropylene film material (without matrix), referred to as “XP”, was evaluated against an aramid fiber (with a phenolic/polyvinyl butyral resin matrix); the aramid system was judged to have the most promising combination of superior performance and a minimum of problems for combat helmet development].
Aramid fiber is formed principally from aromatic polyamide. Aromatic polyamide fibers having a modulus of at least about 400 g/denier and tenacity of at least about 18 g/denier are particularly useful for incorporation into composites of this invention. For example, poly(phenylenediamine terephthalamide) fibers produced commercially by E. I. du Pont de Nemours & Company under the trade names of Kevlar® 29 and Kevlar® 49 and having moderately high moduli and tenacity values are particularly useful in forming ballistic resistant composites. (Kevlar® 29 has 500 g/denier and 22 g/denier and Kevlar® 49 has 1000 g/denier and 22 g/denier as values of modulus and tenacity, respectively). Also useful in forming ballistic resistant composites is Kevlar® KM2.
In the case of polyvinyl alcohol (PV-OH), PV-OH fibers having a weight average molecular weight of at least about 500,000, preferably at least about 750,000, more preferably between about 1,000,000 and about 4,000,000 and most preferably between about 1,500,000 and about 2,500,000 may be employed in the present invention. Usable fibers should have a modulus of at least about 160 g/denier, preferably at least about 200 g/denier, more preferably at least about 300 g/denier, and a tenacity of at least about 7 g/denier, preferably at least about 10 g/denier and more preferably at least about 14 g/denier and most preferably at least about 17 g/denier. PV-OH fibers having a weight average molecular weight of at least about 500,000, a tenacity of at least about 200 g/denier and a modulus of at least about 10 g/denier are particularly useful in producing ballistic resistant composites. PV-OH fibers having such properties can be produced, for example, by the process disclosed in U.S. patent application Ser. No. 569,818, filed Jan. 11, 1984, to Kwon et al. and commonly assigned.
In the case of polyazoles, some preferred embodiments of polyazoles are polyarenazoles such as polybenzazoles and polypyridazoles. Suitable polyazoles include homopolymers and also copolymers. Additives can be used with the polyazoles and up to as much as 10 percent, by weight, of other polymeric material can be blended with the polyazoles. Also copolymers can be used having as much as 10 percent or more of other monomer substituted for a monomer of the polyazoles. Suitable polyazole homopolymers and copolymers can be made by known procedures.
Preferred polybenzazoles are polybenzimidazoles, polybenzothiazoles, and polybenzoxazoles and more preferably such polymers that can form fibers having yarn tenacities of 30 gpd or greater. If the polybenzazole is a polybenzothioazole, preferably it is poly(p-phenylene benzobisthiazole). If the polybenzazole is a polybenzoxazole, preferably it is poly(p-phenylene benzobisoxazole) and more preferably poly(p-phenylene-2,6-benzobisoxazole).
Preferred polypyridazoles are polypyridimidazoles, polypyridothiazoles, and polypyridoxazoles and more preferably such polymers that can form fibers having yarn tenacities of 30 gpd or greater. In some embodiments, the preferred polypyridazole is a polypyridobisazole. A preferred poly(pyridobisozazole) is poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole which is called PIPD. Suitable polypyridazoles, including polypyridobisazoles, can be made by known procedures.
The aramid fabric or aramid fiber can optionally be finished with a repellent material. As used herein, the term “repellent material” refers to a hydrophobic material that resists wetting by aqueous media, an agent comprising fluorine and carbon atoms being preferred. In one embodiment, the fluorinated material comprises fluorinated methacrylate polymers or copolymers, for example as in Zonyl® D fabric fluoridizer, or Zonyl® 8300 fabric protector, or OLEOPHOBOL SM® available from Ciba Spezialitatenchemie Pfersee GmbH, Langweid, Germany. Optionally, the water-repellent agent may in addition contain an antistatic agent, such LEOMIN AN® from CLARIANT GmbH, Textile Leather Products Division, Textile Chemicals BU, Frankfurt Main, Germany. The aramid fabric or aramid fiber can be completely or partially coated with the fluorinated repellant material. The treatment of fabrics or fibers with such fluorinated polymers and oligomers is common in the trade and is not limited to these chemicals. One skilled in the art will be able to choose a suitable treatment.
The finish may be applied to the fiber in a variety of ways. One method is to apply the neat resin of the coating material to the stretched high modulus fibers either as a liquid, a sticky solid or particles in suspension or as a fluidized bed. Alternatively, the finish may be applied as a solution or emulsion in a suitable solvent which does not adversely affect the properties of the fiber at the temperature of application. While any liquid capable of dissolving or dispersing the coating polymer may be used, preferred groups of solvents include water, paraffin oils, aromatic solvents or hydrocarbon solvents, with illustrative specific solvents including paraffin oil, xylene, toluene and octane. If the fiber achieves its final properties only after a stretching operation or other manipulative process, e.g. solvent exchanging, drying or the like, it is contemplated that the finish may be applied to the precursor material. In this embodiment, the desired and preferred tenacity, modulus and other properties of the fiber should be judged by continuing the manipulative process on the fiber precursor in a manner corresponding to that employed on the finished fiber precursor. Thus, for example, if the coating is applied to the xerogel fiber described in U.S. application Ser. No. 572,607 of Kavesh at al., and the coated xerogel fiber is then stretched under defined temperature and stretch ratio conditions, the applicable fiber tenacity and fiber modulus values would be the measured values of an uncoated xerogel fiber which is similarly stretched.
For application of the water-repellent finish to an aramid fiber, any method is suitable in principle that allows the water-repellent agent in the chosen formulation to be distributed on the surface of the fiber. For example, the water-repellent agent formulation can be applied as a thin film on a roller and the aramid fiber passed through the film. Alternatively, the water-repellent agent formulation can be sprayed on to the aramid fiber. The water-repellent agent formulation can also be applied to the fiber using a pump and a pin, slit or block applicator. In another application method, the aramid fibers or aramid fabric can be dipped into a bath of a solution containing the water-repellent finish. Evaporation of the solvent produces a finished fiber or fabric. The dipping procedure may be repeated as required to obtain a desired amount of water-repellent coating on the aramid fibers or aramid fabric.
The application of finish is effected preferably by passing the aramid fiber over a roller immersed in a bath containing the aqueous emulsion of the water-repellent agent, the emulsion preferably having a temperature in the range 15-35° C.
The drying of the aramid fiber after application of finish is performed within ranges of temperature and of drying time that suffice to ensure that the aramid fiber does not agglutinate in the subsequent winding up. The parameter ranges for temperature and drying time are also determined by the requirements of the selected application method. If the water-repellent agent is applied on the aramid fiber in the aramid fiber spinning process, for example, after the fiber has left the wash bath, the ranges of temperature and drying time will be determined by the spinning speed and the structural features of the spinning facility. In one embodiment, the finish-treated aramid fiber is dried at a temperature in the range of 130-210° C. and for a period in the range of 5-15 seconds.
The finished fabric layer is heat treated, preferably until the water absorption of the fabric is reduced. The ranges of duration and temperature required for the heat treatment are determined essentially by the water-repellent agent applied in the coating step. In many cases a temperature in the range of 120-200° C. with a duration of 30-120 seconds is adequate for heat treatment.
A proportion of water-repellent agent in the range of 0.001-0.02 g of water-repellent agent per g of fabric, for example 0.006-0.015 g of water-repellent agent per g of fabric, can result in particularly high hydrophobic efficiency coupled with high antiballistic efficiency in the dry and wet states.
The fabric section can further comprise a polymeric resin disposed between at least two of the fibrous fabric layers. The polymer of the polymeric resin can be any polymer that provides the required level of adhesion with the fabric. Polymeric resins suitable for use between at least two of the fibrous fabric layers include polyvinyl butyral phenolic, polyesters, polyolefins (polyethylene, polypropylene, polybutylene and copolymers and blends of these), polyetheramides, fluoropolymers, polyethers, celluloses, phenolics, polyesteramides, polyurethanes, epoxies, aminoplastics, silicones, polysulfones, polyetherketones, polyetheretherketones, polyesterimides, polyphenylene sulfides, polyether acryl ketones, poly(amideimides), polyimides, polystyrene copolymers, polyamides, vinylesters, and blends thereof. In one embodiment, the polymeric resin comprises either a thermoplastic resin or a blend thereof, or a thermosetting resin, or a blend thereof, but not both a thermoplastic and a thermosetting resin together as disclosed in published patent application US 2001/0113534, which is incorporated herein by reference. In one embodiment, the polymeric resin can comprise an acid ethylene copolymer disposed between at least two of the fibrous fabric layers, wherein the ethylene copolymers are neutralized with an ion as disclosed in published patent application US 2001/0113534. In one embodiment, the polymeric resin comprises a pvb-phenolic thermosetting matrix resin. In one embodiment, one portion of the fabric section contains a thermoplastic resin and one portion of the fabric section contains a thermosetting resin.
Useful ethylene copolymers are those that can be neutralized with an ion selected from the group consisting of sodium, potassium, lithium, silver, mercury, copper and the like and mixtures thereof. Useful divalent metallic ions include, but are not limited to, ions of beryllium, magnesium, calcium, strontium, barium, copper, cadmium, mercury, tin, lead, iron, cobalt, nickel, zinc and the like and mixtures therefrom. Useful trivalent metallic ions include, but are not limited to, ions of aluminum, scandium, iron, yttrium and the like and mixtures therefrom. Useful multivalent metallic ions include, but are not limited to, ions of titanium, zirconium, hafnium, vanadium, tantalum, tungsten, chromium, cerium, iron and the like and mixtures therefrom. It is noted that when the metallic ion is multivalent, complexing agents, such as stearate, oleate, salicylate, and phenolate radicals may be included, as disclosed within U.S. Pat. No. 3,404,134. The metallic ions used herein are preferably monovalent or divalent metallic ions. More preferably, the metallic ions used herein are selected from the group consisting of ions of sodium, lithium, magnesium, zinc and mixtures therefrom. Yet more preferably, the metallic ions used herein are selected from the group consisting of ions of sodium, zinc and mixtures therefrom. The parent acid copolymers of the invention may be neutralized as disclosed in U.S. Pat. No. 3,404,134.
By “degree of neutralization” is meant the mole percentage of acid groups on the ethylene copolymer that have a counterion. The ethylene acid copolymer utilized in the present invention is neutralized to a level of about 70% to slightly greater than 100% with one or more metal ions selected from the group consisting of potassium, sodium, lithium, magnesium, zinc, and mixtures of two or more thereof, based on the total carboxylic acid content of the acid copolymer.
The fabric section may also contain one or more layers of high strength, polyolefin fiber composites such as the cross-plied unidirectional polyethylene fiber composite Dyneema® HB26 from DSM Co. (Netherlands) or tapes such as Tensylon® previously available from BAE or Dyneema® BT10.
In one embodiment, the fabric section may comprise hybrid yarns. As used herein, the term “hybrid yarns” refers to two or more multifilament yarns, the filaments of which have been intermixed with each other without adding twist or otherwise disturbing the parallel relationship of the combined filaments. Examples of suitable hybrid yarns include those containing aramid and carbon; aramid and glass; aramid, carbon and glass; and carbon, glass, and extended chain polyethylene. Other suitable hybrid fibers may also be used. Hybridization of the fibers not only reduces costs, but in many instances improves the performance in armor structures. It is known that aramid fiber and carbon are significantly lighter than glass fiber. The specific modulus of elasticity of aramid is nearly twice that of glass, while a typical high tensile strength-grade of carbon fiber is more than three times as stiff as glass in a composite. However, aramid fiber has a lower compressive strength than either carbon or glass, while carbon is not as impact resistant as aramid. Therefore, a hybrid of the two materials results in a composite that is (1) lighter than a comparable glass fiber-reinforced plastic; (2) higher in modulus, compressive strength and flexural strength than an all-aramid composite; and (3) higher in impact resistance and fracture toughness than an all-carbon composite.
The overlay section of the ballistic composite article comprises a thermoplastic resin. Thermoplastic resins suitable for use in the overlay section can include polycarbonate, polyester, thermoplastic elastomeric polyester, polyacetal, polyamide, polyolefin, polysulfone, polyimide, a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, or combinations thereof. In one embodiment, the thermoplastic resin comprises polycarbonate, a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(alkylene ether)glycol blocks, polybutylene terephthalate, a polyacetal, a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, or combinations thereof. The thermoplastic resins can be unfilled or filled, for example by inclusion of glass or mineral particles or fibers. Optionally, the thermoplastic resins can be toughened as well. Generally, suitable thermoplastic resins have sufficient molecular weight to provide optimized strength and toughness, and exhibit flow at temperatures greater than 75° C. In one embodiment, the polymeric resin of the overlay section and the polymeric resin disposed between at least two of the fibrous fabric layers of the fabric section comprise the same thermoplastic resin. In one embodiment, the polymeric resin of the overlay section is continuous.
In one embodiment, the thermoplastic resin comprises polycarbonate. Polycarbonate refers to any polymer in which the structural units are linked by carbonate ester groups, including 2,2-bis(4-hydroxyphenol)propane (also known as bisphenol A) and diphenyl carbonate. Polycarbonates are characterized by high-impact strength, light weight, and flexibility and can be prepared by the reaction of an aromatic difunctional phenol with either phosgene or an aromatic or aliphatic carbonate, as is well known in the art. Suitable polycarbonates are also commercially available.
In one embodiment, the thermoplastic resin comprises polyester. In one embodiment, the thermoplastic resin comprises polybutylene terephthalate, for example as Crastin® polymer commercially available from E.I. du Pont de Nemours and Company (DuPont). In one embodiment, the thermoplastic resin comprises polytrimethylene terephthalate, for example as SORONA® polymer commercially available from DuPont. In one embodiment, the thermoplastic resin comprises polyethylene terephthalate.
In one embodiment, the thermoplastic resin comprises a thermoplastic elastomeric polyester. In one embodiment, the thermoplastic resin comprises a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(alkylene ether)glycol blocks. In one embodiment, the thermoplastic resin comprises a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks, for example as Hytrel® polymer, commercially available from DuPont.
As used herein, the term “polyester” means a polymer in which more than 50% of the linking groups are ester groups. Other linking groups, such as amide or/or imide may also be present. The polyester is selected from the group consisting of: at least one polyester homopolymer; at least one polyester copolymer; a polymeric blend comprising at least one polyester homopolymer or copolymer; and mixtures of these.
Polyesters which have mostly or all ester linking groups are normally derived from one or more dicarboxylic acids and one or more diols; they can also be produced from polymerizable polyester monomers or from macrocyclic polyester oligomers as disclosed in U.S. Pat. No. 8,071,677, which is incorporated by reference herein.
Suitable polyesters can comprise isotropic thermoplastic polyester homopolymers and copolymers (both block and random). Examples include without limitation: poly(ethylene terephthalate), poly(1,3-propylene terephthalate), poly(1,4-butylene terephthalate), a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks, poly(1,4-cylohexyldimethylene terephthalate), and polylactic acid.
The dicarboxylic acid component is selected from unsubstituted and substituted aromatic, aliphatic, unsaturated, and alicyclic dicarboxylic acids and the lower alkyl esters of dicarboxylic acids preferably having from 2 carbons to 36 carbons. Specific examples of suitable dicarboxylic acid components include without limitation terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-napthalene dicarboxylic acid, dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid, dimethyl-2,7-naphthalate, 3,4′-diphenyl ether dicarboxylic acid, dimethyl-3,4′diphenyl ether dicarboxylate, 4,4′-diphenyl ether dicarboxylic acid, dimethyl-4,4′-diphenyl ether dicarboxylate, 3,4′-diphenyl sulfide dicarboxylic acid, dimethyl-3,4′-diphenyl sulfide dicarboxylate, 4,4′-diphenyl sulfide dicarboxylic acid, dimethyl-4,4′-diphenyl sulfide dicarboxylate, 3,4′-diphenyl sulfone dicarboxylic acid, dimethyl-3,4′-diphenyl sulfone dicarboxylate, 4,4′-diphenyl sulfone dicarboxylic acid, dimethyl-4,4′-diphenyl sulfone dicarboxylate, 3,4′-benzophenonedicarboxylic acid, dimethyl-3,4′-benzophenonedicarboxylate, 4,4′-benzophenonedicarboxylic acid, dimethyl-4,4′-benzophenonedicarboxylate, 1,4-naphthalene dicarboxylic acid, dimethyl-1,4-naphthalate, 4,4′-methylene bis(benzoic acid), dimethyl-4,4′-methylenebis(benzoate), oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinic acid, glutaric acid, dimethyl glutarate, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, dimethyl adipate, 3-methyladipic acid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, dimer acid, 1,4-cyclohexanedicarboxylic acid, dimethyl-1,4-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylic acid, dimethyl-1,3-cyclohexanedicarboxylate, 1,1-cyclohexanediacetic acid, metal salts of 5-sulfo-dimethylisophalate, fumaric acid, maleic anhydride, maleic acid, hexahydrophthalic acid phthalic acid and the like and mixtures derived there from. Other dicarboxylic acids suitable for use in forming the monofilaments will be apparent to those skilled in the art. Preferred dicarboxylic acids include terephthalic acid, dimethyl terephthalate, isophthalic acid, and dimethyl isophthalate.
The diol component is selected from unsubstituted, substituted, straight chain, branched, cyclic aliphatic, aliphatic-aromatic or aromatic diols having from 2 carbon atoms to 36 carbon atoms and poly(alkylene ether)glycols with molecular weights between about 250 to 4,000. Specific examples of the desirable diol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, dimer diol, 4,8-bis(hydroxymethyl)-tricyclo[5.2.1.0/2.6]decane, 1,4-cyclohexanedimethanol (both cis and trans structures), di(ethylene glycol), tri(ethylene glycol), polyethylene ether)glycols with molecular weights between 250 and 4000, poly(1,2-propylene ether)glycols with molecular weights between 250 and 4000, block poly(ethylene-co-propylene-co-ethylene ether)glycols with molecular weights between 250 and 4000, poly(1,3-propylene ether)glycols with molecular weights between 250 and 4000, polybutylene ether)glycols with molecular weights between 250 and 4000 and the like and mixtures derived there from.
A polyfunctional branching agent may be present as well, i.e., any material with three or more carboxylic acid functional groups, hydroxyl functional groups or a mixture thereof. Essentially any polyfunctional material that includes three or more carboxylic acid or hydroxyl functions can be used, and such materials will be apparent to those skilled in the art. Examples of polyfunctional branching agent components include without limitation: 1,2,4-benzenetricarboxylic acid, (trimellitic acid), trimethyl-1,2,4-benzenetricarboxylate, tris(2-hydroxyethyl)-1,2,4-benzenetricarboxylate, trimethyl-1,2,4-benzenetricarboxylate, 1,2,4-benzenetricarboxylic anhydride, (trimellitic anhydride), and mixtures thereof.
In one embodiment, the thermoplastic resin comprises a polyacetal. Polyacetal, also known as polyoxymethylene and polyformaldehyde, is an engineering thermoplastic useful in applications requiring high stiffness, low friction, and excellent dimensional stability. Polyacetals are characterized by high strength, hardness and rigidity to about 40° C. Polyacetals can be prepared, for example, by reaction of aqueous formaldehyde with an alcohol to generate a hemiformal, followed by dehydration of the hemiformal/water mixture via extraction or distillation and heating to generate formaldehyde, which is then polymerized by anionic catalysis. The resulting polymer is stabilized by reaction with acetic anhydride. Suitable polyacetals are commercially available.
In one embodiment, the thermoplastic resin comprises a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, which is commonly referred to as “ionomer”. See, for example, US 201210264342 and U.S. Pat. No. 5,700,890. The total percent neutralization can be from 5 to 90 percent, and the metal ions can be any metal on of group I or group II or the periodic table, for example sodium, zinc, lithium, magnesium, calcium, or a mixture of any of these. The partially neutralized ethylene/α,α-unsaturated C3-C8 carboxylic acid copolymers can be prepared by standard neutralization techniques, as disclosed in U.S. Pat. No. 3,264,272. The ionomers can be prepared by free-radical copolymerization methods, using high pressure, operating in a continuous manner known in the art, as described in U.S. Pat. No. 4,351,931, U.S. Pat. No. 5,028,674, U.S. Pat. No. 5,057,593, U.S. Pat. No. 5,859,137. The polyamide can be aliphatic and/or semi-aromatic, crystalline, semi-crystalline, amorphous, and/or combinations thereof, and can be prepared by methods known in the art or obtained commercially.
The weight percent of the overlay section relative to the composite article is generally between about 1% and about 50%, for example between about 1% and about 45%, or between about 1% and about 40%, or between about 1% and about 35%, or between about 1% and about 30%, or between about 1% and about 25%, or between about 1% and about 20%, or between about 1% and about 15%, or between about 1% and about 10%, or between about 20% and about 30%, or between about 20% and about 40%, or between about 20% and about 45%, or between about 20% and about 50%. Within these disclosed ranges, a higher weight percent of overlay is generally desired as, for a given areal density of a composite article comprising a fabric section and an overlay section, a higher weight percentage of overlay can provide a composite article having comparable or greater ballistic protection at lower cost than a comparison ballistic article of equal areal density but consisting of only the fabric section. However, composite articles in which the weight percent overlay section is greater than about 50% can also be prepared and may provide adequate ballistic performance under some conditions. The maximum useful weight percent of the overlay section depends on the thermoplastic resin selected and the type of ballistic threat faced.
In one embodiment, the weight percent of the overlay section is between about 1% and about 40%, and the thermoplastic resin comprises polycarbonate, a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(alkylene ether)glycol blocks, polybutylene terephthalate, a polyacetal, a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, or combinations thereof.
The overlay section of the ballistic composite article can comprise one or more layers of thermoplastic resin. In one embodiment, the overlay section comprises one layer of thermoplastic resin. In one embodiment, the overlay section comprises two or more layers. The layers can comprise the same or different thermoplastic resins. The layers can have the same or different thicknesses. Optionally, one or more adhesive layers can be disposed between the layers of thermoplastic resin, and the adhesive layers can comprise the same or different adhesives. The thickness of the overlay section will generally depend on the weight percent of the overlay section relative to the composite article and to the areal density of the composite article.
The ballistic composite article can have an areal density between about 2.5 lbs/ft2 (12.2 kg/m2) and about 1.0 lbs/ft2 (4.88 kg/m2), or between about 2.5 lbs/ft2 and about 1.5 lbs/ft2 (7.32 kg/m2), or between about 2.0 lbs/ft2 (9.76 kg/m2) and about 1.0 lbs/ft2 (4.88 kg/m2). The areal density of the composite article refers to the sum of the areal densities of the fabric section and the overlay section, and includes that of any adhesive layers present.
Optionally, an adhesive layer is disposed between the fabric section and the overlay section to join the sections together. Adhesives suitable for use between the fabric section and the overlay section, and/or between two or more layers of the overlay section, can comprise a plant-based glue, a solvent-type glue, a synthetic monomer glue, a synthetic polymer glue, or combinations thereof. Examples of plant-based glues include methyl cellulose, mucilage, resorcinol resin, and starch. Examples of solvent-type glues include polystyrene with butanone (methylethylketone), and dichloromethane. Examples of synthetic monomer glues include acrylonitrile, cyanoacrylate (e.g. “Superglue” and “Krazy Glue”), and acrylic. Synthetic polymer glues include urea-formaldehyde resins, epoxy resins, epoxy putty, ethylene-vinyl acetate (a hot-melt glue), phenol formaldehyde resin, polyamide, polyester resins, polyethylene (a hot-melt glue), polypropylene, polysulfides, polyurethane (e.g. Gorilla Glue), polyvinyl acetate including white glue (e.g., Elmer's Glue) and yellow carpenter's glue (e.g. Titebond® and Lepage® aliphatic resin glues), polyvinyl alcohol, polyvinyl chloride, polyvinyl chloride emulsion, polyvinylpyrrolidone, rubber cement, silicones, and styrene acrylic copolymer. In one embodiment, an adhesive layer is disposed between the fabric section and the overlay section, and the adhesive layer comprises a plant-based glue, a solvent-type glue, a synthetic monomer glue, a synthetic polymer glue, an epoxy resin, a polyurethane, or combinations thereof. In one embodiment, an adhesive layer is disposed between the fabric section and the overlay section, and the adhesive layer comprises an epoxy resin, a polyurethane, or combinations thereof. In one embodiment, an adhesive layer is disposed between the fabric section and the overlay section, the fabric section further comprises a polymeric resin disposed between at least two of the fibrous fabric layers, and the adhesive layer and the polymeric resin comprise the same polymer,
When an optional adhesive layer is to be used, the adhesive layer is preferably spread uniformly onto the entire surface of the fabric section to be bonded to the overlay section, the overlay section placed on top of the adhesive layer, and then minimal force applied to keep the fabric section and overlay sections in contact with the adhesive layer while the adhesive layer dries or cures. In the case of a flat panel, force can be applied by weights placed on top of the composite article. In the case of a helmet, force can be applied by maintaining the components in a mold and keeping the mold closed. The fabric section and overlay section should be kept in close contact overnight, or for a sufficient time under conditions recommended by the supplier to produce a durable bond.
The overlay section is disposed on the strikeface of the ballistic composite article. As used herein, the term “disposed on the strikeface” means that the overlay section completely and uniformly covers the strikeface of the ballistic composite. In one embodiment, the overlay section is additionally disposed on the backface of the ballistic composite article, and optionally on at least a portion of at least one edge of the composite article, with the proviso that the majority of the overlay section is disposed on the strikeface. In one embodiment, the overlay section encapsulates the fabric section, and the majority of the overlay section is disposed on the strikeface of the composite article. By “encapsulates” is meant that the overlay section is disposed on the strikeface, on all the edges, and on all of the backface of the composite article such that the fabric section is completely covered by the overlay section. In the case where the overlay section encapsulates the fabric section, the ballistic composite article may optionally further comprise at least one adhesive layer disposed between at least a portion of the fabric section and the overlay section, for example on the face of the fabric section which is oriented toward the strikeface of the composite article, on the face of the fabric section which is oriented toward the backface of the composite article, or on both faces of the fabric section. By “majority” is meant at least 51%, or at least 55%, or at least 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the overlay section by weight.
Referring to the figures,
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising polyp-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising polybutylene terephthalate, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50%; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising polyp-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising polycarbonate, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 40%; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising poly(p-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 30%; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising polyp-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section encapsulating the fabric section and comprising polybutylene terephthalate, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50% and a majority of the overlay section is disposed on the strikeface of the composite article; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising poly(p-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section encapsulating the fabric section and comprising polycarbonate wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 40% and a majority of the overlay section is disposed on the strikeface of the composite article; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising polyp-phenylene terephthalamide); b) an overlay section comprising one or more layers, the overlay section encapsulating the fabric section and comprising a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 30% and a majority of the overlay section is disposed on the strikeface of the composite article; and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising unidirectionally oriented ultra high molecular weight polyethylene tape; b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 30% and c) an optional adhesive layer disposed between the fabric section and the overlay section.
In one embodiment, the ballistic composite article comprises a) a fabric section comprising two or more fibrous fabric layers comprising unidirectionally oriented ultra high molecular weight polyethylene tape; b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface of the composite article and comprising polycarbonate, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 30% and c) an optional adhesive layer disposed between the fabric section and the overlay section.
A ballistic composite article as disclosed herein in which the overlay is disposed on the strikeface of the composite article can be made by preparing a consolidated fabric section, applying adhesive to one face of the fabric section, placing the overlay section in contact with the adhesive layer, and allowing the overlay and fabric sections to be bonded together through the adhesive layer. In some embodiments the overlay section can be placed directly in contact with the fabric layer and sufficient heat provided to bond the overlay section to the fabric section.
A ballistic composite article as disclosed herein in which the overlay section completely encapsulates the fabric section can be made by a process in which a consolidated fabric section is placed in an injection mold. The fabric section is then overmolded with the desired thermoplastic resin using the process of injection molding, which is well known in the art. The distribution of the overlay can be controlled in the injection molding process so that a majority of the overlay section is disposed on the strikeface of the composite article. Helmets and flat ballistic panels in which the overlay section fully encapsulates the fabric section can be made this way. Optionally, additional functional features can be added to the ballistic composite via the injection molding process, as is known in the art.
The ballistic composite articles disclosed herein can provide comparable or improved protection against projectile threats relative to conventional ballistic composites consisting only of a same-type fabric section having an equal area density. “Same-type” as used herein refers to the fabric section of a comparable composite, as described above, wherein the fabric section is the same as the fibrous fabric layers used in the inventive composite. The comparable or improved protection is evidenced by comparable V50 values and/or lower BFD values for the ballistic composite articles disclosed herein, when compared to those values for corresponding conventional ballistic composites without an overlay section disposed on the strikeface and tested under the same conditions. Advantageously, the ballistic composite articles disclosed herein can be made at reduced cost since a portion of the higher cost ballistic fabric section is replaced by the lower cost thermoplastic overlay. The composite articles disclosed herein are rigid and can be used to provide comparable or superior protection to the body or to property. Panels comprising the disclosed composite articles can be used in rigid armor applications such as helmets, tactical plates, structural members of helicopters, vehicles, walls, shelters, and other military equipment.
EXAMPLESThe ballistic composite articles described herein are illustrated in the following examples. From the above discussion and these examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various uses and conditions.
All commercial materials were used as received unless otherwise indicated.
The following abbreviations are used: “° C.” is degrees Celsius, “° F.” is degrees Fahrenheit, “gn” is grain, “m” is meter, “s” is second, “psf” is pounds per square foot, “lbs/ft2” is also pounds per square foot, “fps” is feet per second”, “ft/s” is also feet per second, “cm” is centimeter, “mm” is millimeter, “g” is gram, “kg” is kilogram, “gpd” is grams per denier, “AD” is area density, “wt” is weight, “wt %” means weight percent, “Comp. Ex.” is Comparative Example, “PVB” means polyvinyl butyral.
Analytical Methods:Ballistic Penetration Performance:
Ballistic tests of the composite articles of Comparative Examples A and B, and Examples 1-20 were conducted in accordance with standard procedure MIL-STD-662-F (V50 Ballistic Test for Armor) with the exception that 16 Grain Right Circular Cylinder (RCC) fragment-simulating projectiles were used. For each Example, one composite article was used as the target with up to seven shots fired at it, at zero degree obliquity. The composite articles of Examples 1-20 were oriented with the overlay section facing the projectile, that is, with the overlay section on the strikeface of the composite article.
Ballistic tests of the composite articles of Comparative Examples E, F, and G and Examples 21-25 were conducted in accordance with standard procedure MIL-STD-662-F (V50 Ballistic Test for Armor) with the exception that 9 mm Full Metal Jacketed bullet rounds with a nominal mass of 8.0 g (124 gn) were used as the projectile. For each Example, one composite article was used as the target with up to seven shots fired at it, at zero degree obliquity. The composite articles of Examples 21-25 were oriented with the overlay section facing the projectile, that is, with the overlay section on the strikeface of the composite article.
The reported V50 values are average values for the number of pairs of partial and complete penetrations achieved for each example. V50 is a statistical measure that identifies the average velocity at which a bullet or a fragment penetrates the target or armor equipment in 50% of the shots, versus non-penetration of the other 50%. The parameter measured is V50 at zero degrees where the degree angle refers to the obliquity of the projectile to the target. For a given set of test conditions and projectile, higher V50 values indicate better resistance to ballistic penetration.
Back Face Deformation (BFD) Performance:
Ballistic tests of the composite articles of Comparative Examples E, F, and G and Examples 21-25 were conducted using a modified version of the HP White HPW-TP-0401.01B standard test procedure for bullet resistant helmet deformation. The same conditioning, testing, and measurement protocols were used, with the modification being only that these example panels were flat and not helmet shaped. The threat used was the 9 mm Full Metal Jacket round, as described above weighing nominally 8.0 g (124 gn), and the velocity used was within the 1400-1450 (427-442 m/s) range, both as described in the document for NIJ Level IIIA protection. For each Example, one composite article was used as the target with up to two shots fired at it, at zero degree obliquity. The composite articles of Examples 21-25 were oriented with the overlay section facing the projectile, that is, with the overlay section on the strikeface of the composite article. The reported BFD values are the individual values for either the one or the two fair shots achieved for each example. BFD values were taken using standard clay measurement techniques developed in the industry, where a lower back face deformation value for a given set of test conditions and projectile corresponds to better panel performance. After one or two fair shots were obtained and BFD values were recorded, the remaining unshot area of the panels of Comparative Examples E, F, and G and Examples 21-25 were then tested for V50 type ballistic testing using the same 9 mm projectile described above.
Area density is reported as weight per unit area and was determined by weighing 12 inch×12 inch panels (30.5 cm×30.5 cm) of material. In some cases, 15 inch×15 inch (38.1 cm×38.1 cm) fabric sections were manually cut down to 12 inch×12 inch panels, then weighed.
Materials and Processing:
Kevlar® XP™ H170:
Comparative Examples A and B and Examples 1-17 used plies of Kevlar® XP™ H170 prepreg, commercially available from E.I. DuPont de Nemours and Company (Wilmington, Del.) (DuPont). This material has a nominal areal weight of 170 g/m2 and comprises (a) a plain weave woven fabric of 600 denier (660 dtex) poly(p-phenylene terephthalamide) yarn having a nominal yarn tenacity of 27.5 grams per denier (gpd) and a nominal yarn modulus of 630 gpd (which is also available from DuPont under the trade name of Kevlar® para-aramid brand KM2 yarn) which was woven at 11.4×11.4 ends per centimeter (29×29 ends per inch) and (b) a thermoplastic matrix resin consisting of a highly neutralized ionomer that had essentially no melt flow which was coated at nominally 10-13 weight percent based on the total weight of the fabric plus the matrix resin as an aqueous colloid of the ionomer on one side of the Kevlar® fabric and dried, as described in detail in published patent application US 2011/0117351(M), which is incorporated herein by reference.
General Procedure for Consolidation of Kevlar® XP™ H170 Plies:
In Comparative Examples A and B and Examples 1-17, the Kevlar® XP™ H170 plies were processed identically to produce fabric sections using the following procedure. The desired number of plies were cut to a size of either nominally 12 inches×12 inches (30.5 cm×30.5 cm) or 15 inches×15 inches (38.1 cm×38.1 cm). Cut plies were laid up such that the one-sided resin matrix coating was always facing the same direction, thus the coated side of one ply was always in direct contact with the dry or un-coated side of an adjacent ply, and vice versa. The layup was placed in a compression molding press to undergo a consolidation procedure in which the plies were consolidated into a fabric section. Consolidation took place at a temperature of 160° C. (320° F.), under a pressure of 31 MPa (4500 psi), for a time of 15 minutes under heat, prior to cooling down to a temperature below 38° C. (100° F.). The 31 MPa (4500 psi) pressure was maintained on the layup during the entire process including the cooling phase. The fabric section was then removed from the mold and analyzed. In the cases where the fabric section was nominally 15 inches×15 inches (38.1 cm×38.1 cm), it was cut down to a size of nominally 12 inches×12 inches (30.5 cm×30.5 cm) with a secondary operation using a band saw.
Tensylon™ HSBD-30A:
Comparative Examples C and D and Examples 18-20 used plies of Tensylon™ HSBD-30A bi-directional polyethylene laminate coated with resin, commercially available from DuPont. This material has a nominal areal weight of 110 g/m2 and comprises (a) a cross-plied set of orthogonal unidirectionally oriented ultra high molecular weight polyethylene (UHMWPE) tape layers and (b) a linear low density polyethylene (LLDPE) thermoplastic matrix resin which was inserted at nominally 10 weight percent based on the total weight of the fabric plus the matrix resin as a film layer both in between the cross-plied unidirectionally oriented tape layers and on the outside of one of the layers as well.
General Procedure for Consolidation of Tensylon™ HSBD-30A Plies:
In Comparative Examples C and D and Examples 18-20, the Tensylon™ HSBD-30A plies were processed identically to produce fabric sections using the following procedure. The desired number of plies were cut to a size of either nominally 12 inches×12 inches (30.5 cm×30.5 cm) or 15 inches×15 inches (38.1 cm×38.1 cm). Cut plies were laid up such that the one-sided resin matrix coating was always facing the same direction, thus the coated side of one ply was always in direct contact with the dry or un-coated side of an adjacent ply, and vice versa. Cut plies were also laid up such that the directionality of one layer of tape was always perpendicular to any adjacent tape layer(s) in direct contact with it, and vice versa. The layup was placed in a compression molding press to undergo a consolidation procedure in which the plies were consolidated into a fabric section. Consolidation took place at a temperature of 132° C. (270° F.), under a pressure of 31 MPa (4500 psi), for a time of 30 minutes under heat, prior to cooling down to a temperature below 38° C. (100° F.). The 31 MPa (4500 psi) pressure was maintained on the layup during the entire process including the cooling phase. The fabric section was then removed from the mold and analyzed. In the cases where the fabric section was nominally 15 inches×15 inches (38.1 cm×38.1 cm), it was cut down to a size of nominally 12 inches×12 inches (30.5 cm×30.5 cm) with a secondary operation using a band saw. In Comparative Examples C and D, where the fabric section was nominally 15 inches×15 inches (38.1 cm×38.1 cm) and no overlay section was used, the panels were left as 15 inches×15 inches (38.1×38.1 cm) for ballistic testing.
Kevlar® S705, PVB-Phenolic:
Comparative Examples E, F, and G and Examples 21-25 used plies of Kevlar® S705 fabric impregnated with resin, commercially available from Sioux Manufacturing Corporation (Fort Totten, N. Dak.). This material has a nominal areal weight of 270 g/m2 and comprises (a) a plain weave woven fabric of 850 denier (944 dtex) poly(p-phenylene terephthalamide) yarn having a nominal yarn tenacity of 27.5 gpd and a nominal yarn modulus of 630 gpd (which is available from DuPont under the trade name of Kevlar® para-aramid brand KM2 yarn) which was woven at 12.2×12.2 ends per centimeter (31×31 ends per inch) and (b) a PVB/phenolic thermosetting matrix resin which was impregnated at nominally 10-13 weight percent based on the total weight of the fabric plus matrix resin into and throughout both sides of the Kevlar® fabric.
General Procedure for Consolidation of Kevlar® S705, PVB-Phenolic Plies:
In Comparative Examples E, F, and G and Examples 21-25, the Kevlar® S705, PVB-Phenolic plies were processed identically to produce fabric sections using the following procedure. The desired number of plies were cut to a size of nominally 12 inches×12 inches (30.5 cm×30.5 cm). The layup was placed in a compression molding press to undergo a consolidation procedure in which the plies were consolidated into a fabric section. Consolidation took place at a temperature of 160° C. (320° F.), under a pressure of 14 MPa (2000 psi), for a time of 15 minutes under heat, after four one-minute bump cycles at the beginning of the cycle. No cooling cycle was used for processing these materials. The 14 MPa (2000 psi) pressure was maintained on the layup during the entire process. The fabric section was then removed from the mold “hot”, allowed to cool to ambient conditions, and then analyzed,
Comparative Example ASixty-three plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 10.722 kg/m2 (2.196 psf). No overlay material was used on the strike face of this fabric section, and no adhesive layer. The final ballistic composite had an area density of 10.722 kg/m2 (2.196 psf) and contained only a fabric section. Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 896 m/s (2940 fps). Results are summarized in Table I.
Comparative Example A was used as the control for Comparative Example B and Examples 1-17.
Comparative Example BForty-six plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.783 kg/m2 (1.594 psf). No overlay material was used on the strike face of this fabric section, and no adhesive layer. The final ballistic composite had an area density of 7.783 kg/m2 (1.594 psf) and contained only a fabric section. Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 722 m/s (2369 fps). Thus a ballistic article was made having about 81% of the V50 performance of the control panel while using only about 72% of the ballistic composite material in the fabric section and with no overlay section. Results are summarized in Table I.
Example 1Fifty-seven plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.755 kg/m2 (1.998 psf). An overlay section of 0.820 kg/m2 (0.168 psf) of Hytrel® polymer grade 4069, which is a low modulus grade thermoplastic polyester elastomer available from DuPont, was adhered to the fabric section. Hytrel® 4069 has nominal hardness of 40D and contains non-discoloring stabilizer; it can be processed by many conventional thermoplastic processing techniques such as injection molding and extrusion. The overlay section was of the same size length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was a 2-part epoxy available from West System, Inc. (Bay City, Mich.), where part one is their part number 105 Epoxy Resin and part two is their part number 206 Slow Hardener. The final ballistic composite had an areal density of 10.663 kg/m2 (2.184 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 927 m/s (3041 fps). Thus a ballistic article was made having about 103% of the V50 performance of the control panel while using about 91% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 2Fifty-six plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.745 kg/m2 (1.996 psf). An overlay section of 1.008 kg/m2 (0.206 psf) of Delrin® polymer grade 100ST, which is a super tough, high viscosity acetal homopolymer grade thermoplastic polyacetal resin available from DuPont, was adhered to the fabric section. Delrin® 100ST has superior impact resistance and is designed for highly stressed parts where outstanding toughness is essential. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was Gorilla Glue from Gorilla Glue, Inc. (Cincinnati, Ohio), and available at most hardware stores. For this and subsequent examples where Gorilla Glue was used as the adhesive, the adhesive was spread uniformly over one face of the fabric section and the overlay section was placed on top of it, and the composite article was placed under approximately 20 lbs (44 kg) of uniformly distributed weight for a number of hours, usually overnight, while the adhesive dried. The final ballistic composite had an areal density of 10.663 kg/m2 (2.184 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 885 m/s (2903 fps). Thus a ballistic article was made having about 99% of the V50 performance of the control panel while using about 91% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 3Fifty-seven plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.692 kg/m2 (1.985 psf). An overlay section of 0.928 kg/m2 (0.190 psf) of Hytrel® polymer grade 8238, a thermoplastic polyester elastomer available from DuPont, was adhered to the fabric section. Hytrel® grade 8238 has high modulus, with nominal hardness of 82D and containing non-discoloring stabilizer. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.826 kg/m2 (2.217 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 875 m/s (2870 fps). Thus a ballistic article was made having about 98% of the V50 performance of the control panel while using about 90% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 4Fifty-six plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.516 kg/m2 (1.949 psf). An overlay section of 1.191 kg/m2 (0.244 psf) of Crastin® polymer grade ST820, which is a thermoplastic polyester available from DuPont, was adhered to the fabric section. Crastin® grade ST820 is an unreinforced, super tough, polybutylene terephthalate resin useful for injection molding. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.590 kg/m2 (2.169 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 889 m/s (2918 fps). Thus a ballistic article was made having about 99% of the V50 performance of the control panel while using about 90% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 5Fifty-six plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.628 kg/m2 (1.972 psf). An overlay section of 1.113 kg/m2 (0.228 psf) of Hytrel® polymer grade G3548L, a low modulus material with nominal durometer hardness of 35D available from DuPont, was adhered to the fabric section. This material contains nondiscoloring stabilizer and can be processed by many conventional thermoplastic processing techniques like injection molding and extrusion. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.878 kg/m2 (2.228 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain ROC threat of 914 m/s (2998 fps). Thus a ballistic article was made having about 102% of the V50 performance of the control panel while using about 89% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 6Fifty-seven plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.589 kg/m2 (1.964 psf). An overlay section of 0.928 kg/m2 (0.190 psf) of Hytrel® polymer grade 8238 was adhered to the fabric section. This grade of Hytrel® is described in Example 3. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.780 kg/m2 (2.208 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain ROC threat of 926 m/s (3038 fps). Thus a ballistic article was made having about 103% of the V50 performance of the control panel while using about 89% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 7Fifty-six plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.516 kg/m2 (1.949 psf). An overlay section of 1.123 kg/m2 (0.230 psf) of Hytrel® polymer grade G3548L, was adhered to the fabric section. This grade of Hytrel® is described in Example 5. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.683 kg/m2 (2.188 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 872 m/s (2861 fps). Thus a ballistic article was made having about 97% of the V50 performance of the control panel while using about 89% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 8Fifty-three plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 9.018 kg/m2 (1.847 psf). An overlay section of 1.699 kg/m2 (0.348 psf) of Hytrel® polymer grade 4069 was adhered to the fabric section. This grade of Hytrel® is described in Example 1. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.946 kg/m2 (2.242 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 871 m/s (2856 fps). Thus a ballistic article was made having about 97% of the V50 performance of the control panel while using about 82% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 9Fifty plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 8.700 kg/m2 (1.782 psf). An overlay section of 1.943 kg/m2 (0.398 psf) of polycarbonate sheet, available as part number 8574K24 from McMaster-Carr (Princeton, N.J.), was adhered to the fabric section. The polycarbonate is an unfilled, impact-resistant material comparable to Lexan®, Hyzod®, Tuffak®, and Makrolon®. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.702 kg/m2 (2.192 psf). Ballistic testing was performed as described above and gave a 1-pair V50 versus the 16 grain RCC threat of 920 m/s (3018 fps). Thus a ballistic article was made having about 103% of the V50 performance of the control panel while using about 81% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 10Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.783 kg/m2 (1.594 psf). An overlay section of 2.941 kg/m2 (0.602 psf) of Crastin® polymer grade SO653, a thermoplastic polyester available from DuPont, was adhered to the fabric section. Crastin® grade SO653 is a 20% glass bead filled polybutylene terephthalate resin for injection molding. It has isotropic properties and low warpage characteristics. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.380 kg/m2 (2.126 psf). Ballistic testing was performed as described above and gave a 3-pair V50 versus the 16 grain RCC threat of 855 m/s (2805 fps). Thus a ballistic article was made having about 95% of the V50 performance of the control panel while using about 75% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 11Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.812 kg/m2 (1.600 psf). An overlay section of 2.883 kg/m2 (0.590 psf) of Delrin® polymer grade 100ST was adhered to the fabric section. This grade of Delrin® is described in Example 2. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.351 kg/m2 (2.120 psi). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 841 m/s (2759 fps). Thus a ballistic article was made having about 94% of the V50 performance of the control panel while using about 75% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 12Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.792 kg/m2 (1.596 psf). An overlay section of 2.927 kg/m2 (0.599 psf) of a thermoplastic blend of Nylon 12 and a zinc ionomer of an ethylene/methacrylic acid copolymer was adhered to the fabric section. The blend consisted of 55% Nylon 12 by weight having a melting point of 180° C., commercially available from Arkema under the trademark Rilsan AESNO, and of 45% by weight of zinc ionomer having a melting point of 95° C., having a neutralization percentage of 60% and composed of ethylene (83% by weight), methacrylic acid (11% by weight) and maleic acid monoethyl ester (6% by weight), based on the weight of the ionomer. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.790 kg/m2 (2.210 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain ROC threat of 803 m/s (2634 fps). Thus a ballistic article was made having about 90% of the V50 performance of the control panel while using about 72% of the ballistic composite material in the fabric section, and also using an overlay section. It should be noted that testing of this panel resulted in an unusually high Zone of Mixed Results (ZMR) of 73 m/s (240 fps). Results are summarized in Table I.
Example 13Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.783 kg/m2 (1.594 psf). An overlay section of 2.920 kg/m2 (0.598 psf) of polycarbonate sheet, available as part number 8574K25 from McMaster-Carr (Princeton, N.J.), was adhered to the fabric section. This polycarbonate is described in Example 9. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.741 kg/m2 (2.200 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 877 m/s (2878 fps). Thus a ballistic article was made having about 98% of the V50 performance of the control panel while using about 72% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 14Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.626 kg/m2 (1.562 psf). An overlay section of 2.959 kg/m2 (0.606 psf) of Crastin® polymer grade ST820, was adhered to the fabric section. This grade of Crastin® is described in Example 4. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.580 kg/m2 (2.167 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 829 m/s (2719 fps). Thus a ballistic article was made having about 92% of the V50 performance of the control panel while using about 72% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 15Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.753 kg/m2 (1.588 psf). An overlay section of 2.998 kg/m2 (0.614 psf) of Zytel® polymer grade HTN51G35, available from DuPont, was adhered to the fabric section. This Zytel® is a 35% glass reinforced, heat stabilized, lubricated high performance thermoplastic polyamide resin. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10,898 kg/m (2.232 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 888 m/s (2914 fps). Thus a ballistic article was made having about 99% of the V50 performance of the control panel while using about 71% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 16Forty-five plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.636 kg/m2 (1.564 psf). An overlay section comprised of 2.978 kg/m2 (0.610 psf) of Crastin® polymer grade ST820 was adhered to the fabric section. This grade of Crastin® is described in Example 14. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the West System 2-part epoxy described in Example 1. The final ballistic composite had an areal density of 10.693 kg/m2 (2.190 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 835 m/s (2741 fps). Thus a ballistic article was made having about 93% of the V50 performance of the control panel while using about 71% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Example 17Forty-four plies of Kevlar® XP™ H170 were consolidated as described above to provide a fabric section having an areal density of 7.665 kg/m2 (1.570 psf). An overlay section of 3.095 kg/m2 (0.634 psi) of Minlon® polymer grade 10B40, available from DuPont, was adhered to the fabric section. Minlon® grade 10B40 is a 40% mineral reinforced polyamide 66 resin for injection molding. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.995 kg/m2 (2.252 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 851 m/s (2792 fps). Thus a ballistic article was made having about 95% of the V50 performance of the control panel while using about 70% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table I.
Comparative Example CEighty-nine plies of Tensylon™ HSBD-30A were consolidated as described above to provide a fabric section having an areal density of 9.805 kg/m2 (2.008 psf). No overlay material was used on the strike face of this fabric section and no adhesive layer. The final ballistic composite had an areal density of 9.805 kg/m2 (2.008 psf) and contained only a fabric section. Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 909 m/s (2981 fps). Results are summarized in Table II.
Comparative Example C was used as the control for Comparative Example D and Examples 18-20.
Comparative Example DSixty-six plies of Tensylon™ HSBD-30A were consolidated as described above to provide a fabric section having an areal density of 7.318 kg/m2 (1.499 psf). No overlay material was used on the strike face of this fabric section and no adhesive layer. The final ballistic composite had an areal density of 7.318 kg/m2 (1.499 psf). Ballistic testing was performed as described above and gave a 3-pair V50 versus the 16 grain RCC threat of 735 m/s (2412 fps). Thus a ballistic article was made having about 81% of the V50 performance of the control panel while using about 75% of the ballistic composite material in the fabric section, using only a fabric section. Results are summarized in Table II.
Example 18Sixty-nine plies of Tensylon™ HSBD-30A were consolidated as described above to provide a fabric section having an areal density of 7.919 kg/m2 (1.622 psf). An overlay section of 2.002 kg/m2 (0.410 psf) of Hytrel® polymer grade 4069 was adhered to the fabric section. This grade of Hytrel® is described in Example 1. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 10.009 kg/m2 (2.050 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 835 m/s (2741 fps). Thus a ballistic article was made having about 92% of the V50 performance of the control panel while using about 79% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table II.
Example 19Sixty-nine plies of Tensylon™ HSBD-30A were consolidated as described above to provide a fabric section having an areal density of 7.870 kg/m2 (1.612 psf). An overlay section of 1.953 kg/m2 (0.400 psf) of polycarbonate sheet, available from McMaster-Carr (Princeton, N.J.), machined down to the desired weight/areal density, was adhered to the fabric section. Polycarbonate is described in Example 9. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 9.911 kg/m2 (2.030 psf). Ballistic testing was performed as described above and gave a 1-pair V50 versus the 16 grain RCC threat of 828 m/s (2715 fps). Thus a ballistic article was made having about 91% of the V50 performance of the control panel while using about 79% of the ballistic composite material in the fabric section, and also using an overlay section. Results are summarized in Table II.
Example 20Seventy-seven plies of Tensylon™ HSBD-30A were consolidated as described above to provide a fabric section having an areal density of 8.964 kg/m2 (1.836 psf). An overlay section of 0.898 kg/m2 (0.184 psf) of polycarbonate sheet, available from McMaster-Carr (Princeton, N.J.), machined down to the desired weight/areal density, was adhered to the fabric section. Polycarbonate is described in Example 9. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 9.999 kg/m2 (2.048 psf). Ballistic testing was performed as described above and gave a 2-pair V50 versus the 16 grain RCC threat of 810 m/s (2658 fps). Thus a ballistic article was made having about 89% of the V50 performance of the control panel while using about 90% of the ballistic composite material in the fabric section, and also using an overlay section. It should be noted that the ballistic test reports indicate that there was some de-lamination that occurred between the fabric section and the overlay section as the testing progressed, which is believed to have caused a lower than otherwise anticipated V50 value for this panel. Results are summarized in Table II.
Comparative Example EThirty-five plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of 9.394 kg/m2 (1.924 psf). No overlay material was used on the strike face of this fabric section and no adhesive layer. The final ballistic composite had an areal density of 9.394 kg/m2 (1.924 psf) and contained only a fabric section. BFD Testing was first performed as described above and gave BFD values of 33 mm and 33 mm on two fair shots on the panel. Ballistic testing was then performed as described above and gave a 2-pair V50 versus the 9 mm FMJ threat of 591 m/s (1940 fps). Results are summarized in Table III.
Comparative Example E was used as the control for Comparative Examples F and G and Examples 21-25.
Comparative Example FTwenty-eight plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of 7.285 kg/m2 (1.492 psf). No overlay material was used on the strike face of this fabric section and no adhesive layer. The final ballistic composite had an areal density of 7.285 kg/m2 (1.492 psf). BFD Testing was first performed as described above and gave a BFD value of 30 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave a 3-pair V50 versus the 9 mm FMJ threat of 518 m/s (1700 fps). Thus a ballistic article was made having about 88% of the V50 performance of the control panel while using about 75% of the ballistic composite material in the fabric section, using only a fabric section. Results are summarized in Table III.
Comparative Example GTwenty-one plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of 5.459 kg/m2 (1.118 psf). No overlay material was used on the strike face of this fabric section and no adhesive layer. The final ballistic composite had an areal density of 5.459 kg/m2 (1.118 psf). BFD Testing was first performed as described above and gave a BFD value of 34 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave a 2-pair V50 versus the 9 mm FMJ threat of 477 m/s (1566 fps). Thus a ballistic article was made having about 81% of the V50 performance of the control panel while using about 56% of the ballistic composite material in the fabric section, using only a fabric section. Results are summarized in Table III.
Example 21Twenty plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an area density of 5.498 kg/m (1.126 psf). An overlay section of 4.121 kg/m2 (0.844 psf) of Zytel® polymer grade HTN51G35 was adhered to the fabric section. This grade of Zytel® is described in Example 15. The overlay section was of the same size (length and width) as the fabric section. No adhesive was used to adhere the overlay section to the fabric section. Instead, the overlay section was co-molded with the fabric section, and resulted in a direct bond to the Kevlar® S705, PVB-Phenolic fabric section. The final ballistic composite had an areal density of 9.570 kg/m2 (1.960 psf). BFD Testing was first performed as described above and gave a BFD value of 27 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave a 1-pair V50 versus the 9 mm FMJ threat of 479 m/s (1572 fps). Thus a ballistic article was made having about 81% of the V50 performance of the control panel while using about 57% of the ballistic composite material in the fabric section, and also using an overlay section. In addition, this panel resulted in a BFD reduction of 7 mm relative to a comparative panel made at approximately the same fabric section content and using only a fabric section. Results are summarized in Table III.
Example 22Twenty-six plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of 7.167 kg/m2 (1.468 psf). An overlay section of 2.490 kg/m2 (0.510 psf) of Zytel® polymer grade HTN51G35 was adhered to the fabric section. This grade of Zytel® is described in Example 15. The overlay section was of the same size (length and width) as the fabric section. No adhesive was used to adhere the overlay section to the fabric section. Instead, the overlay section was co-molded with the fabric section, and resulted in a direct bond to the Kevlar® S705, PVB-Phenolic fabric section. The final ballistic composite had an areal density of 9.550 kg/m2 (1.956 psf). BFD Testing was first performed as described above and gave a BFD value of 26 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave a 2-pair V50 versus the 9 mm FMJ threat of 532 m/s (1745 fps). Thus a ballistic article was made having about 90% of the V50 performance of the control panel while using about 75% of the ballistic composite material in the fabric section, and also using an overlay section. In addition, this panel resulted in a BFD reduction of 4 mm relative to a comparative panel made at approximately the same fabric section content and using only a fabric section. Results are summarized in Table III.
Example 23Twenty-seven plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of T353 kg/m2 (1.506 psf). An overlay section of 2.265 kg/m2 (0.464 psf) of Rynite® polymer grade 415HP, available from DuPont, was adhered to the fabric section. Rynite® grade 415HP is a 15% glass reinforced modified polyethylene terephthalate with improved processing over a broad molding range and excellent balance of strength, stiffness, and temperature resistance. The overlay section was of the same size (length and width) as the fabric section. No adhesive was used to adhere the overlay section to the fabric section. Instead, the overlay section was co-molded with the fabric section, and resulted in a direct bond to the Kevlar® S705, PVB-Phenolic fabric section. The final ballistic composite had an areal density of 9.501 kg/m2 (1.946 psf). BFD Testing was first performed as described above and gave BFD values of 21 mm and 25 mm on two fair shots on the panel. Ballistic testing was then performed as described above and gave a 1-pair V50 versus the 9 mm FMJ threat of 528 m/s (1732 fps). Thus a ballistic article was made having about 89% of the V50 performance of the control panel while using about 77% of the ballistic composite material in the fabric section, and also using an overlay section. In addition, this panel resulted in a BFD reduction of 9 mm and 5 mm on different shots relative to a comparative panel made at approximately the same fabric section content and using only a fabric section. Results are summarized in Table III.
Example 24Twenty-eight plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an areal density of 7.275 kg/m2 (1.490 psf). An overlay section of 2.441 kg/m2 (0.500 psf) of polycarbonate sheet, available from McMaster-Carr (Princeton, N.J.), machined down to the desired weight/area density, was adhered to the fabric section. This polycarbonate is described in Example 9. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an area density of 9.814 kg/m2 (2.010 psf). BFD Testing was first performed as described above and gave a BFD value of 29 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave only a High Partial (HP) penetration velocity versus the 9 mm FMJ threat of 553 m/s (1815 fps). No complete penetration was obtained on this sample, and so therefore, no V50 value was obtained either, but the V50 is typically anticipated to be equal to or greater than the High Partial velocity. Thus a ballistic article was made having about at least 94% of the V50 performance of the control panel while using about 74% of the ballistic composite material in the fabric section, and also using an overlay section. In addition, this panel resulted in a BFD reduction of 1 mm relative to a comparative panel made at approximately the same fabric section content and using only a fabric section. Results are summarized in Table III.
Example 25Twenty-eight plies of Kevlar® S705, PVB-Phenolic prepreg were consolidated as described above to provide a fabric section having an area density of 7.304 kg/m2 (1.496 psf). An overlay section of 2.521 kg/m2 (0.516 psf) of thermoplastic blend of Nylon 12 and a zinc ionomer of an ethylene/methacrylic acid copolymer, was adhered to the fabric section. The blend consisted of 55% Nylon 12 by weight having a melting point of 180° C., commercially available from Arkema under the trademark Rilsan AESNO, and of 45% by weight of zinc ionomer having a melting point of 95° C., having a neutralization percentage of 60% and composed of ethylene (83% by weight), methacrylic acid (11% by weight) and maleic acid monoethyl ester (6% by weight), based on the weight of the ionomer. The overlay section was of the same size (length and width) as the fabric section. The adhesive used to adhere the overlay section to the fabric section was the Gorilla Glue described in Example 2. The final ballistic composite had an areal density of 9.814 kg/m2 (2.010 psf). BFD testing was first performed as described above and gave a BFD value of 27 mm on one fair shot on the panel. Ballistic testing was then performed as described above and gave a 1-pair V50 versus the 9 mm FMJ threat of 541 m/s (1776 fps). Thus a ballistic article was made having about 92% of the V50 performance of the control panel while using about 74% of the ballistic composite material in the fabric section, and also using an overlay section. In addition, this panel resulted in a BFD reduction of 3 mm relative to a comparative panel made at approximately the same fabric section content and using only a fabric section. Results are summarized in Table III.
It can be seen from the data in Tables I, II, and III that the composites containing an overlay section and a fabric section typically had V50 and/or BFD values comparable to or better than those for the composites having about the same final areal density and containing only a fabric section. In Table I, panels with a fabric section of between about 70 and about 92 percent by weight of the composite article and an overlay section between about 8 and about 30 percent by weight of the composite article (Examples 1-17) demonstrated V50 values equal to or in excess of about 90% of that of the comparable panel having the full areal density and containing only a fabric section (Comparative Example A). In Table II, panels with a fabric section of between 79 and 90 percent by weight of the composite article and an overlay section between about 10 and 21 percent by weight of the composite article (Examples 18-20) demonstrated V50 values equal to or in excess of about 89% of that of the comparable panel having the full areal density and containing only a fabric section (Comparative Example C). In Table III, panels with a fabric section of between about 57 and about 77 percent by weight of the composite article and an overlay section between about 23 and about 43 percent by weight of the composite article (Examples 21-25) demonstrated ballistic performance with a combination of V50 values equal to or in excess of about 90% of and/or a BFD reduction of from about 1 mm to about 9 mm lower than that of the comparable panel having the full areal density and containing only a fabric section (Comparative Example E for the V50 and BFD values, respectively).
Claims
1. A ballistic composite article having a strikeface and a backface, the ballistic composite article comprising:
- a) a fabric section comprising two or more fibrous fabric layers;
- b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface and comprising a thermoplastic resin, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50%; and
- c) an optional first adhesive layer disposed between the fabric section and the overlay section;
- whereby the composite article, when tested according to MIL-STD-662-F using a 16 grain right circular cylinder fragment-simulating projectile, has a V50 value comparable to or greater than that of an article consisting only of a same-type fabric section having an area density that is about the same as the area density of the composite article.
2. The composite article of claim 1, wherein the overlay section is additionally disposed on the backface of the composite article, and optionally on at least a portion of at least one edge of the composite article, with the proviso that the majority of the overlay section is disposed on the strikeface.
3. The composite article of claim 1, wherein the thermoplastic resin comprises polycarbonate, a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(alkylene ether)glycol blocks, polybutylene terephthalate, a polyacetal, a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, or combinations thereof.
4. The composite article of claim 1, wherein the weight percent of the overlay section is between about 1% and about 40%.
5. The composite article of claim 1, wherein the first adhesive layer is present and comprises a plant-based glue, a solvent-type glue, a synthetic monomer glue, a synthetic polymer glue, an epoxy resin, a polyurethane, or combinations thereof.
6. The composite article of claim 1, wherein one or more of the fibrous fabric layers comprises a woven fabric.
7. The composite article of claim 1, wherein one or more of the fibrous fabric layers comprises a non-woven fabric.
8. The composite article of claim 7, wherein the non-woven fabric comprises a unidirectionally oriented tape structure.
9. The composite article of claim 1, wherein the fabric layers comprise a polymer selected from the group consisting of aramid, ultra-high molecular weight polyethylene, ultra-high molecular weight polypropylene, polyvinyl alcohol, polyazole, polybenzoxazole, polybenzothiazole, and combinations or blends thereof.
10. The composite article of claim 1, wherein the fabric section further comprises a polymeric resin disposed between at least two of the fibrous fabric layers, and the polymeric resin and the overlay section comprise the same thermoplastic resin.
11. The composite article of claim 1, wherein the areal density is between about 2.5 lbs/ft2 and 1.0 lbs/ft2.
12. A panel comprising the composite article of claim 11.
13. A helmet comprising the composite article of claim 11.
14. A ballistic composite article having a strikeface and a backface, the ballistic composite article comprising:
- a) a fabric section comprising two or more fibrous fabric layers;
- b) an overlay section comprising one or more layers, the overlay section being disposed on the strikeface and comprising a thermoplastic resin, wherein the weight percent of the overlay section relative to the composite article is between about 1% and about 50%; and
- c) an optional first adhesive layer disposed between the fabric section and the overlay section;
- whereby the composite article, when tested according to HP White HPW-TP-0401.01B using a 9 mm Full Metal Jacket projectile, has a back face deformation value lower than that of an article consisting only of a same-type fabric section having an areal density about the same as the areal density of the composite article.
15. The composite article of claim 14, wherein the weight percent of the overlay section is between about 1% and about 40%, and wherein the thermoplastic resin comprises polycarbonate, a thermoplastic elastomeric polyester having poly(1,4-butylene terephthalate) and poly(alkylene ether)glycol blocks, polybutylene terephthalate, a polyacetal, a blend of polyamide and an ethylene/α,β-unsaturated C3-C8 carboxylic acid copolymer partially neutralized with metal ions, or combinations thereof.
Type: Application
Filed: Feb 28, 2013
Publication Date: Feb 5, 2015
Inventors: Thomas D. Boyer (Smyrna, DE), Carmen A. Covelli (Chadds Ford, PA), Bryce Vanarsdalen (Cherry Hill, NJ)
Application Number: 14/379,812
International Classification: F41H 5/04 (20060101); F41H 1/04 (20060101);
