CA1274751A - Ballistic-resistant fine weave fabric article - Google Patents
Ballistic-resistant fine weave fabric articleInfo
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- CA1274751A CA1274751A CA000502594A CA502594A CA1274751A CA 1274751 A CA1274751 A CA 1274751A CA 000502594 A CA000502594 A CA 000502594A CA 502594 A CA502594 A CA 502594A CA 1274751 A CA1274751 A CA 1274751A
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Abstract
ABSTRACT
The present invention provides an improved article of manufacture which comprises at least one network of high strength, extended chain fiber or yarn selected from the group consisting of extended chain polyethylene (ECPE) extended chain polypropylene (ECPP) fibers, extended chain polyvinyl alcohol (PVA) fiber and extended chain polyacrylonitrile (PAN) fiber. The fibers and yarn have a denier of not more than about 500 and a tensile modulus of at least about 200 g/denier.
The fibers and yarn preferably have a tensile modulus of at least about 500 grams/denier and an energy-to-break of at least about 22 Joules/gram. Optionally, a low modulus elastomeric material, which has a tensile modulus of less than about 6,000 psi, measured at about 23°C, substantially coats the fiber and yarn of the network.
The present invention provides an improved article of manufacture which comprises at least one network of high strength, extended chain fiber or yarn selected from the group consisting of extended chain polyethylene (ECPE) extended chain polypropylene (ECPP) fibers, extended chain polyvinyl alcohol (PVA) fiber and extended chain polyacrylonitrile (PAN) fiber. The fibers and yarn have a denier of not more than about 500 and a tensile modulus of at least about 200 g/denier.
The fibers and yarn preferably have a tensile modulus of at least about 500 grams/denier and an energy-to-break of at least about 22 Joules/gram. Optionally, a low modulus elastomeric material, which has a tensile modulus of less than about 6,000 psi, measured at about 23°C, substantially coats the fiber and yarn of the network.
Description
7~
B ISTIC-RESISTANT FINE WEAVE FABRIC ARI'ICLE
DESCRIPTION
BACKGROUND OF THE INVENTION
_ Ballistic resistant articles such as bulletproof 5 vests, curtains, mats, raincoats and umbrellas con-taining high strength fibers are known. Fibers conventionally used include aramid fibers such as poly(phenylenediamine terephthalamide), nylon fibers, glass fibers and the like. For many applications, such 10 as vests or parts of vests, the fibers are used in a woven or knitted fabric.
In "The Application of High Modulus Fibers to Ballistic Protection", R. C. Laible, et al., J.
Macromol. Sci.-Chem. A7(1), pp. 295-322 1973, it is indicated on p. 298 that an important requirement is that the textile material have a high degree of heat resistance; for example, a polyamide material with a melting point of 255C appears to possess better impact properties ballistically than does a polyolefin fiber with equivalent tensile properties but a lower melting point.
R. C. Laible; "Fibrous armor," Ballistic Materials and Penetration Mechanics, Elsevier Scientific Pub-lishing Co~, 1980; provides an overview of the ballistic resistance performance of various fabrics. Liable discloses that among different silk fabrics, a fabric having a lower areal density would exhibit a small increase in ballistic resistance to .22 caliber frag-ments. See in particular, pp. 73-90 thereof. J. W. S.
Hearle, et al.; "Ballistic Impact Resi5tance of Multi-Layer Textile Fabrics," NTIS Acquisition No. AD A127641, (1981); disclose that among nylon abrics, those having greater areal density exhibited increased ballistic resistance. The findings of R. Sarson, et al.; 11th Commonwealth Defense Conference on Operational Clothing and Combat Equipment, India ~1975); were in agreement with the findings of Hearle, et al. Weiner, et al.;
"Materials Evaluation Report No. 2781," ~.S. Army Natick 47~.
B ISTIC-RESISTANT FINE WEAVE FABRIC ARI'ICLE
DESCRIPTION
BACKGROUND OF THE INVENTION
_ Ballistic resistant articles such as bulletproof 5 vests, curtains, mats, raincoats and umbrellas con-taining high strength fibers are known. Fibers conventionally used include aramid fibers such as poly(phenylenediamine terephthalamide), nylon fibers, glass fibers and the like. For many applications, such 10 as vests or parts of vests, the fibers are used in a woven or knitted fabric.
In "The Application of High Modulus Fibers to Ballistic Protection", R. C. Laible, et al., J.
Macromol. Sci.-Chem. A7(1), pp. 295-322 1973, it is indicated on p. 298 that an important requirement is that the textile material have a high degree of heat resistance; for example, a polyamide material with a melting point of 255C appears to possess better impact properties ballistically than does a polyolefin fiber with equivalent tensile properties but a lower melting point.
R. C. Laible; "Fibrous armor," Ballistic Materials and Penetration Mechanics, Elsevier Scientific Pub-lishing Co~, 1980; provides an overview of the ballistic resistance performance of various fabrics. Liable discloses that among different silk fabrics, a fabric having a lower areal density would exhibit a small increase in ballistic resistance to .22 caliber frag-ments. See in particular, pp. 73-90 thereof. J. W. S.
Hearle, et al.; "Ballistic Impact Resi5tance of Multi-Layer Textile Fabrics," NTIS Acquisition No. AD A127641, (1981); disclose that among nylon abrics, those having greater areal density exhibited increased ballistic resistance. The findings of R. Sarson, et al.; 11th Commonwealth Defense Conference on Operational Clothing and Combat Equipment, India ~1975); were in agreement with the findings of Hearle, et al. Weiner, et al.;
"Materials Evaluation Report No. 2781," ~.S. Army Natick 47~.
-2- ~
RSD Command Ma. ~1950); found no significant effect of fabric areal density on balli5tic resistancQ, Figucia;
"En~rgy Absorption o~ Kevla~ Fabrics under ~alli~tic Impact" NTIS Acguisition No. AD A090390, (1980); dis-5 closes a limited study ~mploying Kevla~ fabric in which balli tic resistance increased with a decrease in fabric areal den~ity. However, thes~ reqult3 are not readily interpreted becauc~ the type of fabric weavs was no~
held constant.
It is, thereforo, appar~nt that there i~ no gen-erally applicabl0 relationship b~tween fabric areal den ity and b~lli3tic re~istanc~O
~RIEF DESCRIPT~ON OF THE INVENTION
__ _ _ _ =
The pre ent invention provides an improved, flexi-15 ble, ballistic-r~-Ri3tant ~ot~ fabric armor. The fabric i3 compri~ed of ~t lea~t on~ network layer o~
high ~trength, ext~nded chain polyolefin ~ECP~ fibers ~elected ~rom the group consist~ng of ~xt~nded chain polyethylen~ ~CPE3 and ext~nded chain polypropylene t~CPP) flbers, extanded chain polyvinyl alcohol (PVA) fiber, and e%~ended chain polyacrylonitrile fiber. The fibers may be employe~ as such or arranged and con-figured ~o form y~rn, th~ d~n~er of the fiber or yarn being no more than about 500 and h~ving a tQn~ile modu-lus of at 1~3t ~bout 200 g/d~nior. Th~ fiber or y~rnof the i3 ~mployod to fonm the fabric. Th~ fiber or yarn o~ tho ~ab~lc arfl optionally coated with a low modulu~ el~tomorlc mat0rl~1 which ha3 a ten~ile modulus of le~s than about 6,000 p~i ~41,300 kPa).
Compared ~o conventionsl balli~tic-resistant fabric structures, th~ fabric of th~ present invention can advanta~eou31y provido a sel~ct~d l~vel o~ ballistic protection whil~ employing a reduced weight o~ pro~ec-tive material. Alternatively, the fabri~ o~ the pre~ent 3r invention can provid0 incr~a~ed ballistic protoction when the ar~icl~ h~ a weight equal to the wei~h~ ef a conventionally constructed piece of flexible fabric-type, soft armor.
*Indicates Trademark DETAILED DESCRIPTION OF THE INVENTION
For the purposes of the present invention, a fiber is an elongate body the length dimension of which is much greater than the transverse dimensions of width and 5 thickness~ Accordingly, the term fiber includes mono-filament and multifilament fiber, ribbon, strip, and the like having regular or irregular cross-section.
A ballistic resistant fabric of the present inven-tion includes at least one network comprised of a high 10 strength, ultra-high molecular weight, extended chain polyolefin (ECP) fiber, extended chain polyvinyl alcohol (PVA) fiber, and extended chain polyacrylonitrile ~PAN) fiber. The fiber may be arranged and configured to form a yarn, provided the yarn denier is not more than about 500 and has a tensile modulus of at least about 200 g/denier. This yarn can be employed to form the fabric.
To further improve the ballistic resistance of the fabric, the fiber and yarn preferably have a denier of less than about 300, and more preferably have a denier f less than about 250. In addition, the fiber and yarn have a tensile modulus which preferably is at least about 1200 g/den, and more preferably is at least about 1800 g/den.
In another aspect of the invention, the fiber or yarn of the network is coated with a low modulus elasto-meric material comprising an elastomer to provide improved ballistic resistance. This elastomeric material has a tensile modulus oE less than about 6,000 psi (41,300 kPa), measured at about 23C. Preferably, - 30 the tensile modulus of the elastomeric material is less than about S,000 psi t34,500 kPa), more preferably, i5 less than 1,000 psi (6900 kPa) and most preferably is less than about 500 psi ~3,450 kPa) to provide even more improved performance. The glass transition temperature (Tg) of the elastomer of the elastomeric material (as evidenced by a sudden drop in the ductility and elasticity of the material) i5 less than about 0C.
Preferably, the Tg of the elastomer is less than about ~X747~1 -~ooc, and more preferably is less than about -50C.
The elastomer also has an elongation to breals (measured at about 23C) of at least about 50%. Preferably, the elongation to break is at least about 100%, and more preferably, ;t is about 300% for improved pecformance.
USP 4,457,9~5 generally di6cusses the high streng~h, high molecular weight, extended chain polyole-fin fibers, employed in the present inven-tion, and the disclosure of this patent is hereby incorporated by ref-erence to the extent that it is not inconsistent here-with. More particularly, suitable polyethylene fibers are those having a molecular weight of at least 500,000, preferably at least one million and more preferably between two million and five million. Such extended chain polyethylene (ECPE) fibers may be grown in solution such as described in U.S. Patent No. 4,137,39 ~o Meihuzen et al., or U.S. Patent No. 4,356,138 of Kavesh et al., issued October 26, 1982, or a fiber spun from a solution to form a gel structure, as described in Germany Off. 3,004,699 and GB 2051667, and especially as described in U.S. Patent No. 4,551,296 issued Nov.5, 1985 of Kavesh (see EP~, 64,167, published Nov. 10, 1982). Depending upon the formation technique, the draw ratio and temperatures, and other conditions, a variety of properties can be imparted to these fibers.
The tenacity of the fibers should be at least 15 grams/
denier, preferably at least 20 grams/denier, more pref-erab].y at least 25 grams/ denier and most preferably at least 30 grams/denier. Similarly, the tensile modulus of the fibers, as measured by an Instron*tensile testing machine, is at least 300 grams/denier, preferably at least 500 grams/denier and more preferably at least 1,000 grams/denier and most preferably at least 1,500 grams/denier. These highest values for tensile modulus and tenacity are generally obtainable only by employing solution grown or gel fiber processes. Many of the fibers have melting points higher than the melting point of the polymer from which they were formed. Thus, for *Indicates Trademark 7~
example, ultra-high molecular ~eight polyethylenes of 500,000, one millio~ and two million generally have melting points in the bulk of 138C. The highly oriented polyethylene fibers made of these materials 5 have melting points 7 - 13C higher. Thus, a slight increase in melting point reflects the crystalline per-fection of the fiber~O Nevertheless, the melting points of ~hese fibers remain substantially below nylon; and the efficacy of these fibers for ballistic resistant 10 articles is contrary to the various teachings cited above which indicate temperature resistance as a criti-cal factor in selecting ballistic materials.
Similarly, highly oriented, extended chain poly-propylene (ECPP) fibers of molecular weight at least 750,000, preferably at least one million and mor~ pref-erably at least two million may be used. Such ultra high molecular weight polypropylene may be formed into reasonably well oriented fibers by the techniques pre-scribed in ths various references referred to above, and especially be the technique of U.S. Patent No. 4,551,296 filed January 20, 1984, of ~avesh et al. and commonly as~igned. Since polypropylene is a much less crystal line material than polyethylene and contains pendant methyl group~ tenacity values achievable with poly-propylene ara g~nerally subctantially lswer than thecorresponding values for polyethylene. Accordingly, a suitable tenacity is at least 8 yrams/denier, with a preferred tenacity being at least 11 grams/denier. The ten ile modulus for polypropylene i~ at least 160 grams/denier, preferably at least 200 grams/denier. The melting point of the polypropylene i5 generally raised several degrees by the orientation proces3, such that the polypropylene fiber preferably has a main melting point o~ a~ least 168C, more preerably at least 170C. The particularly preferred ranges for the above-described parameters can advantageously provide improved performance in the final article.
B
~L~7~75~
~ s used herein, the terms polyethylene and poly--propylene mean predominantly linea~ polyethylene and polypropylene materials that may contain minor amounts oE chain b~anching or comonomees not exceeding 5 modi-fying units per lOO main chain carbon atom~, an-l that may also contain admixed therewi~h not more than about 25 wt% of one or more polymeric additives such as alkene-l-polymers: in particular, low density polyethy-lene, polypeopylene or polybu~y]ene, copolymers con-taining mono-olefins as primary monomers, oxidized polyole-Eins, graft polyolefin copolymers and polyoxy-methylenes, or low molecular weight additives such as anti-oxidants, lubricants, ultra-violet screening agents, colorants and the like which are commonl~ incor-porated therewith.
In the case of polyvinyl alcohol (PV-O~I), PV-OH
fiber of molecular weight of at least about 500,000, preferably at least about 750,000 more preferably between about l,OOO,OOO 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. Particularly useful PV-OH fibec should have a modulus of at least about 300 g/denier, a tenacity of at least about 7 g/denier (preferably at least about lO g/denier, more preferably at about 14 g/denier, and mo~t preeerably at least about 17 g/denier), and an eneegy to break oE at least about 22 joules/g. PV--OH fibers having a weight average molecular weight of at least about 500,000 a tenacity of at least about 300 g/denier, a modulus of at least about 10 g/denieL, and an energy to break of about Z2 joll].es/g are more useEul in producing a ballistic resistant article. PV-OH fiber having such properties can be produced, f OL e~ample, by the process disclosed in U.S. Patent No. ~,599,267, filed January ll, L9~4 issued July 8, 19~6 to Kwon et al. and commonly assigned.
In the case of polyacrylonitrile (PAN), PAN fiber of molecular weight of at least about ~OO,000, and preferably at least l,OOO,OO0 may be employed.
.~
~7~7S~
Particularly useful PAN fiber should have a tenacity o~
at least about 10 g/denier and an energy to break o at least about 22 joule/g. PAN fiber having a mol~cular weight of at leas~ about 400,000, a tenacity oS at least 5 about 15-20 g/denier and an energy to break of at least about 22 joule/g is most useful in producing ballistic resistant articles; and such fibers are disclosed, for example, in U.S. 4,535,027.
For improved ballistic resistance of the fabric 10 article, the fiber has a tensile modulus which pref-erably is at least about 500 g/den, more preferably is at least about 1000 g/den and mo5t preferably is at least about 1300 g/den. Additionally, the ECP fiber has an energy-to-break which preferably is at least about ~2 15 J/9~ more preferably is at least about 50 J/g and most preferably is at least about 55 J/g.
In the fabric of the invention, the fiber network can have various configurations. For example, a plurality of fibers can be grouped together to form a twisted or untwist~d yarn. The fibers or yarn may be formed a~ a felt, knitted or woven ~plain, basket, satin and crow ~eet weaves~ etc.) into a network~ or ~ormed into a network by any of a variety of conventional tech-nique~. For example, the fiber~ may be formed into 25 wo~en or nonwoven cloth layers by conventional tech-niques.
A preferred embodiment of the present invention includes multiple laycrs of ~lastomeric material coated fiber networks. The l~yer~ individually retain the hi~h flexibility char~cteristic of textile fabrics and remain separate ~rom each other. The multilayer article exhi-~its the flexibility o~ plied fabric~, and is readily dis~inguishable from the compositc structure6 de-ccribed in co-pending U.S. Patent No. 4,623,574 of Harpell, et al. and entitled "Ballistic Resistant Composite Article~ ~Attorney Docket No. 82-2334). Vests and other articles of clothing comprised of multiple layers o fabric constructed in accordance with the pre~
~ ;~7D~75~
sent invention have good flexibility and comfort coupled with excellent ballistic protection.
The flexibility of the ballistic resistant fabric structures of the present invention is demonstrated by 5 the following test: A 30 cm square fabric sample com-prised o~ multiple fabric layers having a total areal density of 2 kg/m2, when clamped in a horizontal orien-tation along one side edge, will drape so that the oppo-site side edge is at least 21 cm below the level of the 10 clamped side.
The multiple layers of fabric may be stitched together to provide a desired level of ballistic pro-tection; for example, as against multiple ballistic impacts. However, stitching can reduce the flexibility Coated fibers may be arranged (in the same fashion as uncoated fibers) into woven, non-woven or knitted fabrics. The fabric layers may be arranged in parallel arrays and/or incorporated into multilayer fabric arti-cles. Furthermore, the fibers, used either alone orwith coatings, may be wound or connected in a conven-¦ tional fashion.
The proportion of coating in the fabric may varyfrom relatively small amounts (e.g. 0.1~ by weight of fibers) to relatively large amounts (e.g. 60% by weight of fibers), depending upon whether the coating material has any ballistic-resistant properties of its own (which is generally not the case) and upon the rigidity, shape, heat resistance, wear resistance, flammability resis-tance and other properties desired for the fabric. Ingeneral, ballistic-resistant fabrics of the present invention containing coated fibers should have a rela-tively minor proportion of coating (e.g. 0.1-30%, by weight of fibers), since the ballistic-resistant proper-ties are almost entirely attributable to the fiber.Nevertheless, coated fabrics with higher coating con-tents may be employedl ~7~751 _g The coating 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 li~uid, a sticky solid or particles 5 in suspension or as a fluidized bed. Alternatively, the coating may be applied as a solution or emulsion in a suitable solvent which does not adversely affect the properties of the Eiber at the temperature of applica-tion. While any liquid capable of dissolving or dis-10 persing the coating polymer may be used, preferredgroups of solvents include water, paraffin oils, aromatic solvents or hydrocarbon solvents, with illus-trative specific solvents including paraffin oil, xylene, toluene and octane. The techniques used to 15 dissolve or disperse the coating polymers in the sol-vents will be those conventionally used for the coating of similar elastomeric materials on a variety of sub-strates.
j Other techniques for applying the coating to the i 20 fibers may be used, including coating of the high modu-lus precursor (gel fiber) before the high temperature stretching operation, either before or after removal of the solvent from the fiber. The fiber may then be stretched at elevated temperatures to produce the coated fibers. The gel fiber may be passed through a solution of the appropriate coating polymer (solvent may be paraffin oil, aromatic or aliphatic solvent) under conditions to attain the desired coating~ Crystalliza-tion of the high molecular weight polyethylene in the ~ 30 gel fiber may or may not have taken place before the fiber passes into the cooling solution. Alternatively, the fiber may be extruded into a fluidized bed of the appropriate polymeric powder.
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 contempIated that the coating may be applied to the prec~rsor material. In this embodiment, the desired and preferred tenacity, modulu~ and other propertie~ o~ the fiber should be judged by continuing the manipulative process on tha fib~r precur~or in a manner corr~ponding to ~hat employed on the coated fiber precur~or. Thus, 5 for example, if the coating i~ applied to the xorog~l fiber described in U.S.Patent No. 4,623,574 of Kave~h et al,, and th~ coated xerogel fiber i9 then stretched under d~fined temp~rature and ~tretch ratio condition~, th~ applicable fib~r tena~ity and fiber 10 modulu~ value~ would b~ the m~ured values of ~n uncoated xorogel ~ib~r which i3 ~imilarly strQtched.
A preferr~d co~ting t~chnique i~ to fonm a n~twork layer and thon dip tho n~t~ork into a bath of ~ ~olution containing th~ 1GW modulu~ ~la~tomeric co~ting 15 mat~rial. Evaporation of the ~olv2nt produce~ an ela~tomeric materlal coae~d f~bric. Th~ dip~ing pro-cedure ~ay b~ rop~at~d a~ r~quired to plac~ a d~3ired amount of ol~tom~ric coAting on th~ fibor~.
A wide vari~ty of ~la~tomeric materials and formulation~ ~ay b~ utiliz~d in this inv~ntion. The e ~ential r0quircm~nt i~ th~t th~ elastomeric material havo th~ ~propr~aSoly low ~odulu~. Repr~ntative ex~mple~ o ~u~t~bl~ ela~to~0r~ of tho olautom~ric mat~ri~l h~v~ th~ir ~tructur~ rop~rti~ ormulations tog~th~r with ~ro~linking procedur~ ~u~marized ~n th2 ~ 9~L __ ~ , Volumo 5 in the ~ction ~lA~o~r~-Syn~hQtic~ (Jolln ~ y ~ Son~ Inc., 1964).
Fo~ ~xampl~, any of tho ollowlng ~a~eri~l~ m~y be employads polybut~dl~n~, polyi~opren~, natur~l rubber, sthyl~n~-pro~yl~n~ copolym~r~, e~hyl~n~-propylene-diene terpolymor~, poly3ulfid~ polym~rs, ~olyur~than~ ol~to-mar~, chloro~ulfonated polye~hylen~, polychloropr0ne, plaeticized polyvinylchlorido u~ing dioctyl phtha~ or oth~r pla~ic~r~ w~ll known in tho art, but~di~ne ~crylonitril~ ola~tomer~, poly(l~obutyl~n~-co-is0pr~no), polyacrylat~3, polyo3~rs, poly~th~r~, ~luoro~la~tom~r5, ~ilicone ~la~tom~rs, thQrmopla3~ic ~ tom~r~, copoly-m~rs o~ ethyl~n~.
4~5~L
Particularly u~ful ela~tomers ar~ block copolym~rs o~ con~ugat~d di~ne~ and vinyl aromatic ~onomers.
Butadien~ ~nd isopren~ ar~ prQ~rred conJugated dl~n~
ela~tomers. 5tyr~ne, vinyl toluene and t~bu~yl ~tyrene 5 are preferr~d conjugate~ aromatic monomer~. alock copolym~r~ lncorporating polyi~oprene may b~ hydrogena-t~d to produc~ th~rmopla~tic ~la~tomer~ having saturated hydsocarbon ~la~tomor s~g~a~t~. Th~ polymers may be simpl~ tri~block copolymer~ o the type A-~-A, multi-10 block copolym~r~ of the typ~ ~AB)n(n~2-10) or radial configuration copolymers of th~ typ~ R-(~A)x(x~3-150);
wh~rcin A i~ a block from a polyvinyl aromatic monomer ~nd ~ i~ a block from a conjugatsd di~n~ ~la~tomer.
M~ny o tho~ polym~rs ~o produc~d commerci~lly by the 15 Shell Ch~mlc~l CoO and d~crib~d $n th~ bull~tin ~Rraton*
Th~rmopl~tic Rubbor~, SC 68~
Mo~t pref~rably, th~ ~la3to~sric mat~rial consi~ts o at l~aRt ono o~ ths abov~ m~ntion~d ela~tomer~. Th~
low modulus ~1~ to~oric ~at~rial m~y ~l~o include fil-lar~ such as ca~bon black, ~ilica, et~. and m~y b~ext~nd~d with oil~ and vulc~nl2~d by ~ulfur, peroxide, m~tal oxid~, or radiation curo ~y$tom~ u~ing msthod~
w~ll known to rubbor t~chnologi~t~ nd~ of differ~n~
ela~tomeric matorial~ m~y b~ u~d tog~ther or on~ or 25 mor~ ~lA~to~r ~at~ri~l~ ~ay b~ bl~ndod with on~ or ~ore th0r~0~1a~tlc~. High d~n~ity, low d~n~ity, and linaar low don~ity polyothylon~ ~ay bo ~ros~-llnk~d to obtain a ~atrlx mat~rial o~ appropri~t~ prcport~o~, ~ith~r alone or a~ bl~nd~. In ~ry ~n~tanco, th~ ~odulu~ o~ the co~tin~ 3hould not ~xc~d ~bout 6000 p~i (41,300 kPa), pr~f~rably i~ s than about 5000 p~i (34,500 kPa), more preferably 1~ than 100 p~i ~6900 kP~) and mo~t pref~rably i~ l~ss than abou~ 500 p~i (3~50 kPa).
A coatod yarn can b2 produc0d by pulling a group of fibers through th~ ~olution o low modulu~ olastomoric mat~ri~l to ~u~t~nti~lly coat ~ch of tho lndi~idual fib~r~, and then ~v~por~ting t~ ~olv~nt to form th~
coat~d yarn. Th~ yarn can th~n ~ employ~d to form *Indicates Trademark 75~
coated fabric layers which in turn, can be used to form desired multilayer fabric structures.
Multilayer fabric articles may be constructed and arranged in a variety of forms. It is convenient to 5 characterize the geometries of such multilayer fabrics by the geometries of the fibers and then to indicate that substantially no matri~x material, elastomeric or otherwise, occupies the region between fabric layers.
One such suitable arrangement is a plurality of layers 10 in which each layer is comprised of coated fabric fibers arranged in a sheet-like array and successive layers of such fabrics are rotated with respect to the previous layer. An example of such multilayer fabric structures is a five layered structure in which the second, third, fourth and fifth layers are rotated +45~, -45, 90 and o, with respect to the first layer, but not necessarily in that order. Other exarnples include multilayer fab-rics with alternating fabric layers rotated 90 with respect to each other.
In various forms of the fabric of the invention, I the fiber network occupies different proportions of the total volume of the fabric layer. Preferably, however, the fiber network comprises at least about 50 volume percent of the fabric layer, more preferably between about 70 volume percent, and most preferably at least j about 90 volume percent. Similarly, the volume percent I of low modulus elastomeric material in a fabric layer is preferably less than about 15 Vol %, more preferably is less than about 10 Vol %, and most preferably is less than about 5 Vol %.
The specific weight of the fabric layer is expressed in terms of the areal density (AD)o This areal density corresponds to the weight per unit area of the fabric layer. Preferably, the fabric layer areal density is less than about 0.3 kg/m2; more preferably the areal density is less than about 0.2 kg/m2 and most preferably, the areal density is less than about 0.1 kg/m2 -75~
It has been discovered that coated fabric comprised of strip or ribbon tfiber with an aspect ratio, ratio of fiber width to thickness, of at least about 5) can be even more effective than other forms of fiber or yarn 5 when producing ballistic resistant articles. In particular embodiments of the invention the aspect ratio of the strip is at least 50, preferably is at least 100 and more preferably is at least 150 for improved performance~ Surprisingly, even though an ECPE
10 strip material had significantly lower tensile proper-ties than an ECPE yarn material of the same denier but generally circular cross section, the ballistic resis-tance of the coated fabric ccnstructed from ECPE strip was significantly higher than the ballistic resistance 15 of the coated fabric constructed from the ECPE yarn.
Most screening studies of ballistic composites ; employ a .22 caliber, non-deforming steel fragment of specified weight, (19 grains) hardness and dimensions ! (Mil-Spec. MIL-P-46593A(ORD)). Limited studies were 20 made employing .22 caliber lead bullet weighing 40 grains. The protective power of a structure is normally expressed by citing the impacting velocity at which 50%
of the projectiles are stopped, and is designated the V50 value.
Usually, a flexible fabric, "soft" armor is a multiple layer structure. The specific weight of the multilayer fabric article is similarly expressed in terms of the areal density (AD). This areal density corresponds to the weight per unit area of the multiple layer structure.
To compare structures having different V50 values and different areal densities, the following examples state the ratios of (a) the kinetic energy tJoules) of the projectile at the V50 velocity, to (b) the areal density of the fabric tkg/m2). This ratio is designated as the Specific Energy Absorption tSEA).
The following examples are presented to provide a more complete understanding of the invention. The ~7~
~,pecific technique~, conditions, materials, proportion~
and reported data ~et forth to illustrate the principles of the invention ar~ exemplary and should not be con-strued a~ limiting the ~cope of th~ invention, EX~MPLE F-l A low areal den ity (0.1354 kg~m~) pl~in weave fabric having 70 end~/inch (28 end3/cm) in both the warp and fill direetion was pr~pared from untwisted yarn si2~d with low mol~cular weight polyvinyl~lcohol on a 10 Crompton and Rnowl~ *box loom. After weaving, the sizing was removed by washing in hot water (60 72~C).
The yarn used for ~abri~ preparation had 1~ filaments, yarn denier of 203, modulu~ of 1304 g~denier, tenacity of 28,4 g/denier, alongation of 3.1~ and energy~o-break 15 f 47 J/9. A multilayer fabric targct F-l wa compri ed of 13 layer3 o f~bric and had a total areal density (AD) o~ 1.76 kg/m2O All yarn tcn~ile properti~ wera me~sured on an In~tron te~ter using tire cord b~rrel clamp~, gauge lsngth of 10 inch~ (25.4 cm), and cross-head speed of 10 inches/~inute (25.4 cm/min).XAMPLE F-2 Fabric wa~ woven in a manner similar to that u3ed for pr~paration o fabric F~ xc~pt that a higher deni~r yarn (de3ignat0d SY-l) having 118 filament~ and approxim~tely 1200 d~niar, 1250 9 denier modulu~, 30 9 denier tenacity, and 60 J/g ener~y-to-break) wa~ used to produce ~ pl~in wea~e ~abric having areal den~ity of approximately 0.3 kg/m2 and 28 end~/inch (11 ends/cm).
Slx layer~ of this fabric were a3semblad to prepare a balli~tic targot F-2.
* Indicates Trademark ~, ~
~.~'7~'75~
A 2 x 2 basket weave fabric was prepared from our standard yarn (SY-l) having 34 ends/inch (13.4 ends/cm)~ The yarn had approximately 1 turnJinch and 5 was woven without sizing. The fabric areal density was 0,434 kg/m2 t and a target F-3 comprised of 12 fabric layers had an ar~al density of 5.21 kg/m2.
This fabric was prepared in an identical manner to 10 that of Example F-l except that the yarn used had the following properties- denier 270~ 118 filaments, modulus 700 g/denier, tenacity 20 g/denier and energy-to-break 52 J/9O The fabric had an areal density of 0.1722 kg/m2~ ~ target F-4 was comprised of 11 layers of this fabric.
Yarn SY-l wa~ used to prepare a high denier non-crimped fabric in the following manner. Four yarns were combined to form single yarnQ of approximately 6000 denier and these yarns were used to form a nvn-crimped fabric having 2B ends~inch in both the warp and fill ~irection. Yarn SY 1, having yarn denier of 1200 was used to knit together a multilayer structure. Fabric areal density was OL705 kg/m2. A ballistic target F-5 25 wa~ compri~ed of seven layers of this fabric.
Eight one-foot-square pieces of Kcvla~ 29 ballistic fabric, manufactured by Clark Schwebel, were assembled to produce a target F-6 having an areal den~ity of 2.32 kg/m2, The fabric waR designated Style 713 and was a plain weave fabric comprised of 31 ends per inch of untwisted 1000 denier yarn in both the warp and fill direction.
This sample was substantially identical to sample F-6, except that ~ix layers of ~evla~ 29 were used to produce a target F-7 having a total target areal density of 1.74 kg/m2.
*Indica-tes Trademark ~L~7~75~
Ballistic Results Against .22 Caliber Fragments Fabric targets one-foot-square (30.5 cm) and comprised of multiple layers of fabric were tested against .22 caliber fragments to obtain a V50 value.
Fabric properties are shown in Table lA and ballistic results are shown in Table lB.
TABLE lA
FABRIC PROPERTIES
10 E~m~le Yarn Yarn Yarn W~ave Denier Modulus Energy-(g/den) to-break (J/g) F-l 203 1304 47 Plain F-4 270 700 52 Plain 15 F-2 1200 1250 60 Plain F-3 1200 1250 60 2x2 Lasket F-5 6000 1250 60 non-cr~ed TABLE lB
Ballistic Results Against .22 Caliber Fra~ments ~le Fabric AD Target ~D V50 SEA
No. (kg/m2) _ (kg/m ) _ (ft/sec) (J/m2 F-l 0.1354 1.76 1318 50.5 F-4 0.1722 1.89 951 24.4 25 E`-2 0.316 1.90 1165 36.9 F-3 0.434 5.21 1318 17.1 F-5 0.705 4.95 1333 18.0 Sample F-l gave the best ballistic results, sug-gesting that a combination of high modulus yarns and ~ 30 fine weave fabric comprised of low denier yarn has par-ticular merit.
Example FB-2 Ballistic Results A2~1n .22 Caliber Lead Bullets Sample targets were evaluated against .22 caliber lead bullets, and the striking and exit velocities of the bullets were individually recorded. ~abric proper-ties are shown in Table 2A, and ballistic results are shown in Tables 2B and 2C.
~ ~7~75~
~17~
Table 2A
Properties o Plain Weave Fabric~
Example Yarn TypeD~nier Mbdulus Energy~to-Bre~k (g/den.) _(J/~?
F~l ECPE 203 1304 47 F 6 Kevlar*29 1000 700 29 F-7 Kevla~ 29 1000 700 29 Table 2B
Ballistic Results Against .22 Caliber Bullets ~xample Fabric AD Target AD V(in~ V(out) SEA
( kQhn ) _ _( ks~ (Jm2/kg 15 F-l 0.1354 1.76 1212 0 100.5 1198 9~2 32.2 1194 838 ~9.5 1193 958 34.6 11~1 0 93.8 7 0.29 1.741175 0 95.8 11~6 760 57.5 120~ 1040 25.5 1176 963 31.6 1216 9~6 43.1 F-6 0.29 2.231198 0 74.6 1214 721 49.6 1181 0 72.5 1200 589 56.9 1181 0 72.5 F-4 0.1722 1.89 1200 1100 14.6 1184 1091 13.5 1225 1137 13.2 1144 1037 14.8 *Indicates Trademark '~.
~.Z74~5~
Sample A~erage SEA 96 Bullets __ ( iC~m2 ) _ Sto 2ped F-l 66 .8 50 5F-7 50 . 0 20 F-6 65 . 2 60 F-4 14.0 0 A eomparison of the ballistic results of examples F-l and F-4 indicates that higher modulus yarns are much 10 superior for ballistic protection against .22 caliber bull~ts when woven into a fine weave fabric comprised of low denier yarn. These data also indicate that the F-l f~bric is ~uperior to Kevla~ ballistic fabric (F-7) in current use, with respect to both the percen of bullets 15 stopped and the average SEAo EXAMPLE C-l The individual fabric layers of the target des-cribed in Example F-l, after ballistic testing against both 22 caliber fragments and .22 caliber bullets, was 20 soaked overnight in a toluene ~olution o~ Kraton*D1107 (50 g/litre). ~rato~ D1107, a commercial product of the Shell Chemical Company, is a triblock copolymer of the polystyrene~polyisoprene-polystyrene having about 14 wt % styrene, a tensile modulus of about 200 p~i (measured 25 at 23C~ and having a Tg o~ approximately -60C. The fabric layers w~re removed from the solvent and hung in a fume hood to allow the solvcnt to cvaporate. A target C-l, contalning 6 wt ~ elastomer, was reassembled with 13 fabrlc layer~ for additional ballistic testing.
EXAMPLE C-2A and C-2B
Six one~foot-square fabric layers of the type describad in example F-2 were assembled together and designated sample C-2A.
Six fabr1c layers identical to thos2 o~ example C-2A, were immersed in a toluene solution of Xraton*G1650 (35 g/litre) for three days and were hung in a fume hood to allow solvent evaporation. Xraton*G1650, a triblock thermoplastic elastomer produced by Shell Chemical Co, .~ *Indlcates Trademark 7S~
--lg--has the structure polystrene-polyethylenebutylene-poly-styrene and has about 29 wt ~ styrene. Its tensile modulus is about 2000 psi ~measured at 23C), and its Tg is approximately -60C. The panel layers each had an 5 areal density of 1.9 kg/m2 and contained 1 wt % rub-ber. The layers were assembled together for ballistic testing and were designated sample C-2B.
EXAMPLES C4 ~C10 Each target in this series was comprised of six 10 one-foot-square layers of the same fabric, which had been prepared as described in example F-2. The f iber areal density of these targets was 1.90 kg/m2.
Sample C-~ was compri~ed of untreated fabric.
Sample C-5 was eomprised of fabric coated with 5.7 15 wt % Krato* G1550. The fabric layers wsre soaked in a toluene solution of the Krato~*1650 ~65 g/litre) and ~hen assembled after the solvent had besn evaporated.
Sample C-6 was prepared in a similar manner to sample C-5 except that after the sampla had been dipped and dried, it was redipped to produce a target having 11.0 wt % coating.
Sample C-7 was prepared by sequentially dipping the fabric squares in three ~olutionq of ~raton*
D1107/dichloromethane to produce a target having 10.8 wt 25 % coating. Fabric layers were dried between succe~sive coating~. Concantration~ of the Kraton*D1107 thermo-plastic, low modulus elastomers in the three coating solutions were 15 g/L, 75 g/L and 15 g~L, in that order, Sample C-8 was prepared by dipping fabric layers into a colloidal silica solution, prepared by adding three volume parts of de-ionized water to one volume part of Ludo~AM, a product of DuPont Corporation which i9 an aqueou3 colloidal ~ilica dispersion having 30 wt silica of average particle ~ize 12 nm and surface area of 230 m2/~.
Sample C-9 was prepared from electron beam irradi-ated fabric irradiated under a nitrogen atmosphere to 1 Mrad using an Electracurtain*apparatus manufactured by *Indicates Trademark ~7~
Energy Sciences Corporation. The fabric squares were dipped into a Eudox~AM solution diluted with an equal volume of deionized water.
Sample C10 was prepared in a ~imilar manner to 5 ~xample C-9, except that the fabric was irradiated to 2 Mrads and was subsequently dipped into undiluted Ludox*
AMo Thi~ level of irradiation had no significant effect on yarn tensile poroperties.
EXAMPLE C-ll A plain weave ribbon fabric was pr2pared from poly-ethylen2 ribbon 0.64 cm in width, having modulus of 865 g~denier and energy-to-break of 46 J/g. Fabric panels ~layers) one-foot-square (30.5 cm) were soaked in dich-loromethane solution of Kraton~D1107 (lOg/litre) for 24 15 hour~ and then removed and driedO The 37 panels, having a total ribbon areal density of 1.99 kg/m2 and 6 wt ~
rubber coating were as~embled into a multilayer target sample C-ll for balliQtic testing.
EXAMPLE CB-l As shown below, the damaged target C-l stopp~d all .22 caliber bullets fired into it. TheRe results were superior to those obtained for the same fabric before it was rubb~r coated and much superior to the Revla~ bal-listic fabrics. (See Example FB-2,) 25 V(in) V~out) SEA
~ft/sec)(ft~sec) ~Jm2 1218 0 101.5 1182 0 95.6 1172 0 94.0 1159 0 91.9 Although this fabric wa~ highly damaged, a .22 calib2r fragment wa3 ~ired into thc target at an impacting v210city of 1381 ft/sec and was stopped, corresponding to an SEA of 55,5 Jm2/kg. This result indicates that th~ low modulus rubber coating also improves ballistic rssistance against .22 caliber fragment~. The VS0 value or the uncoated fabric *Indicates Trademark 75~L
(example F-l) was 1318 ft/sec, corresponding to an SEA
of 50.5 Jm2/kg. The highest partial penetration velocity for Example F-l was 1333 ft/sec, corresponding to an SEA of 51.7 Jm2~kg.
~inally, thi~ highly damaged sample was ballisti-cally tested against .38 caliber bullets according to test procedure NILECJ-5TD-0101.01. Three .38 caliber bullets having impacting velocities of 780, 803 and 831 ft/sec, respectively, were stopped by the target, and 10 the bullet îndentations into the clay backing were less than 1~2 inchesO The target sample easily me~ the spacification. Even though this target had an areal density of only 1.76 kg~m2, it met or exceeded the U.S.
Military specifications for Type 1 and Type lA Kevla~ 29 15 target~ having a greater areal density of 2.24 kg/m2 ~Specification MIL-C-44050). This wae accomplished in spite of the fact that the total number of ballistic impacts on this single target greatly exceeded reguire-ments. It is, therefore, quite apparent that the fabric 2~ articles of the present invention can provide required levels of ballistic protection while employing a lighter weight of material.
Targets C-2A and C-2B were marked with a felt pen to divide it ~nto two, 6in X 12in rectangles. The V50 value~ for each target wa~ determined against .22 cali ber fragments using only one of tha rectangles (one half of the target). Each target was immersed in watar for ten minutes, and the hung for three minutes before determination of a VS0 value using the undamaged rec-tangle. Data shown below clearly indicate that the small ammount of rubber coating ha~ a beneficial effect on the balli~tic performance of the fabric tar~et when wet.
*Indicates Trademark ~4~5~
V50 (~t/s~c) Target C-2A Target C-2B
(untreated) _ (lwt ~ Elastomer) (Ballis~ic Studies uQing 28X28 plain weave, coated fabrics) Ballistic testing usin~ .22 caliber fragments 10 against six-layer fabric targets having fiber areal den sity of 1.90 kg~m2 showed that elastomeric coatings improved ballistic performance, but silica coatings were inefective.
15 Sample CoatingV50 SEA
(ft/sec)(~m2/k~) C-4 none 1165 36.9 C-5 Kraton*G1650 1228 41.0 (5,7 wt %) 20 C-6 Rrato~ G1650 1293 45.4 (11 wt %) C-7 Krato~* D1107 1259 43.1 110.8 wt %) C-8 Silica1182 38.0 (3.4 wt ~
C-9 Silica1150 3600 (7.2 wt %) C-10 Silica1147 35.8 (17 wt ~) Sample C-ll was tested ballistically and exhibited a V50 value of 1156 ft/sec determined against .22 caliber fragments. This corresponded to a SEA value of 34.4 Jm2/kg. This target exhibited good ballistic properties in spite of the fact that ribbon ~tress-strain properties were inferior to those of most of ~he ECPE yarns used in this studyO
*Indicates Trademark a '. ~ ~
;-:~I.X~747~3 A V50 value of 1170 ft/sec against .22 caliber bullets was obtained for sample C-ll, whereas samples C-5, C-6 and C-7 allowed bullets having a striking velocity of approximately 1150 ft/sec to pass through 5 the target with a velocity loss of less than 250 ft/sec. This indicates that the ribbon fabric is par~
ticularly effective against .22 caliber lead bullets~
Having thus described the invention in rather full detail, it will be understood that these details need 10 not be strictly adhered to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.
.1
RSD Command Ma. ~1950); found no significant effect of fabric areal density on balli5tic resistancQ, Figucia;
"En~rgy Absorption o~ Kevla~ Fabrics under ~alli~tic Impact" NTIS Acguisition No. AD A090390, (1980); dis-5 closes a limited study ~mploying Kevla~ fabric in which balli tic resistance increased with a decrease in fabric areal den~ity. However, thes~ reqult3 are not readily interpreted becauc~ the type of fabric weavs was no~
held constant.
It is, thereforo, appar~nt that there i~ no gen-erally applicabl0 relationship b~tween fabric areal den ity and b~lli3tic re~istanc~O
~RIEF DESCRIPT~ON OF THE INVENTION
__ _ _ _ =
The pre ent invention provides an improved, flexi-15 ble, ballistic-r~-Ri3tant ~ot~ fabric armor. The fabric i3 compri~ed of ~t lea~t on~ network layer o~
high ~trength, ext~nded chain polyolefin ~ECP~ fibers ~elected ~rom the group consist~ng of ~xt~nded chain polyethylen~ ~CPE3 and ext~nded chain polypropylene t~CPP) flbers, extanded chain polyvinyl alcohol (PVA) fiber, and e%~ended chain polyacrylonitrile fiber. The fibers may be employe~ as such or arranged and con-figured ~o form y~rn, th~ d~n~er of the fiber or yarn being no more than about 500 and h~ving a tQn~ile modu-lus of at 1~3t ~bout 200 g/d~nior. Th~ fiber or y~rnof the i3 ~mployod to fonm the fabric. Th~ fiber or yarn o~ tho ~ab~lc arfl optionally coated with a low modulu~ el~tomorlc mat0rl~1 which ha3 a ten~ile modulus of le~s than about 6,000 p~i ~41,300 kPa).
Compared ~o conventionsl balli~tic-resistant fabric structures, th~ fabric of th~ present invention can advanta~eou31y provido a sel~ct~d l~vel o~ ballistic protection whil~ employing a reduced weight o~ pro~ec-tive material. Alternatively, the fabri~ o~ the pre~ent 3r invention can provid0 incr~a~ed ballistic protoction when the ar~icl~ h~ a weight equal to the wei~h~ ef a conventionally constructed piece of flexible fabric-type, soft armor.
*Indicates Trademark DETAILED DESCRIPTION OF THE INVENTION
For the purposes of the present invention, a fiber is an elongate body the length dimension of which is much greater than the transverse dimensions of width and 5 thickness~ Accordingly, the term fiber includes mono-filament and multifilament fiber, ribbon, strip, and the like having regular or irregular cross-section.
A ballistic resistant fabric of the present inven-tion includes at least one network comprised of a high 10 strength, ultra-high molecular weight, extended chain polyolefin (ECP) fiber, extended chain polyvinyl alcohol (PVA) fiber, and extended chain polyacrylonitrile ~PAN) fiber. The fiber may be arranged and configured to form a yarn, provided the yarn denier is not more than about 500 and has a tensile modulus of at least about 200 g/denier. This yarn can be employed to form the fabric.
To further improve the ballistic resistance of the fabric, the fiber and yarn preferably have a denier of less than about 300, and more preferably have a denier f less than about 250. In addition, the fiber and yarn have a tensile modulus which preferably is at least about 1200 g/den, and more preferably is at least about 1800 g/den.
In another aspect of the invention, the fiber or yarn of the network is coated with a low modulus elasto-meric material comprising an elastomer to provide improved ballistic resistance. This elastomeric material has a tensile modulus oE less than about 6,000 psi (41,300 kPa), measured at about 23C. Preferably, - 30 the tensile modulus of the elastomeric material is less than about S,000 psi t34,500 kPa), more preferably, i5 less than 1,000 psi (6900 kPa) and most preferably is less than about 500 psi ~3,450 kPa) to provide even more improved performance. The glass transition temperature (Tg) of the elastomer of the elastomeric material (as evidenced by a sudden drop in the ductility and elasticity of the material) i5 less than about 0C.
Preferably, the Tg of the elastomer is less than about ~X747~1 -~ooc, and more preferably is less than about -50C.
The elastomer also has an elongation to breals (measured at about 23C) of at least about 50%. Preferably, the elongation to break is at least about 100%, and more preferably, ;t is about 300% for improved pecformance.
USP 4,457,9~5 generally di6cusses the high streng~h, high molecular weight, extended chain polyole-fin fibers, employed in the present inven-tion, and the disclosure of this patent is hereby incorporated by ref-erence to the extent that it is not inconsistent here-with. More particularly, suitable polyethylene fibers are those having a molecular weight of at least 500,000, preferably at least one million and more preferably between two million and five million. Such extended chain polyethylene (ECPE) fibers may be grown in solution such as described in U.S. Patent No. 4,137,39 ~o Meihuzen et al., or U.S. Patent No. 4,356,138 of Kavesh et al., issued October 26, 1982, or a fiber spun from a solution to form a gel structure, as described in Germany Off. 3,004,699 and GB 2051667, and especially as described in U.S. Patent No. 4,551,296 issued Nov.5, 1985 of Kavesh (see EP~, 64,167, published Nov. 10, 1982). Depending upon the formation technique, the draw ratio and temperatures, and other conditions, a variety of properties can be imparted to these fibers.
The tenacity of the fibers should be at least 15 grams/
denier, preferably at least 20 grams/denier, more pref-erab].y at least 25 grams/ denier and most preferably at least 30 grams/denier. Similarly, the tensile modulus of the fibers, as measured by an Instron*tensile testing machine, is at least 300 grams/denier, preferably at least 500 grams/denier and more preferably at least 1,000 grams/denier and most preferably at least 1,500 grams/denier. These highest values for tensile modulus and tenacity are generally obtainable only by employing solution grown or gel fiber processes. Many of the fibers have melting points higher than the melting point of the polymer from which they were formed. Thus, for *Indicates Trademark 7~
example, ultra-high molecular ~eight polyethylenes of 500,000, one millio~ and two million generally have melting points in the bulk of 138C. The highly oriented polyethylene fibers made of these materials 5 have melting points 7 - 13C higher. Thus, a slight increase in melting point reflects the crystalline per-fection of the fiber~O Nevertheless, the melting points of ~hese fibers remain substantially below nylon; and the efficacy of these fibers for ballistic resistant 10 articles is contrary to the various teachings cited above which indicate temperature resistance as a criti-cal factor in selecting ballistic materials.
Similarly, highly oriented, extended chain poly-propylene (ECPP) fibers of molecular weight at least 750,000, preferably at least one million and mor~ pref-erably at least two million may be used. Such ultra high molecular weight polypropylene may be formed into reasonably well oriented fibers by the techniques pre-scribed in ths various references referred to above, and especially be the technique of U.S. Patent No. 4,551,296 filed January 20, 1984, of ~avesh et al. and commonly as~igned. Since polypropylene is a much less crystal line material than polyethylene and contains pendant methyl group~ tenacity values achievable with poly-propylene ara g~nerally subctantially lswer than thecorresponding values for polyethylene. Accordingly, a suitable tenacity is at least 8 yrams/denier, with a preferred tenacity being at least 11 grams/denier. The ten ile modulus for polypropylene i~ at least 160 grams/denier, preferably at least 200 grams/denier. The melting point of the polypropylene i5 generally raised several degrees by the orientation proces3, such that the polypropylene fiber preferably has a main melting point o~ a~ least 168C, more preerably at least 170C. The particularly preferred ranges for the above-described parameters can advantageously provide improved performance in the final article.
B
~L~7~75~
~ s used herein, the terms polyethylene and poly--propylene mean predominantly linea~ polyethylene and polypropylene materials that may contain minor amounts oE chain b~anching or comonomees not exceeding 5 modi-fying units per lOO main chain carbon atom~, an-l that may also contain admixed therewi~h not more than about 25 wt% of one or more polymeric additives such as alkene-l-polymers: in particular, low density polyethy-lene, polypeopylene or polybu~y]ene, copolymers con-taining mono-olefins as primary monomers, oxidized polyole-Eins, graft polyolefin copolymers and polyoxy-methylenes, or low molecular weight additives such as anti-oxidants, lubricants, ultra-violet screening agents, colorants and the like which are commonl~ incor-porated therewith.
In the case of polyvinyl alcohol (PV-O~I), PV-OH
fiber of molecular weight of at least about 500,000, preferably at least about 750,000 more preferably between about l,OOO,OOO 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. Particularly useful PV-OH fibec should have a modulus of at least about 300 g/denier, a tenacity of at least about 7 g/denier (preferably at least about lO g/denier, more preferably at about 14 g/denier, and mo~t preeerably at least about 17 g/denier), and an eneegy to break oE at least about 22 joules/g. PV--OH fibers having a weight average molecular weight of at least about 500,000 a tenacity of at least about 300 g/denier, a modulus of at least about 10 g/denieL, and an energy to break of about Z2 joll].es/g are more useEul in producing a ballistic resistant article. PV-OH fiber having such properties can be produced, f OL e~ample, by the process disclosed in U.S. Patent No. ~,599,267, filed January ll, L9~4 issued July 8, 19~6 to Kwon et al. and commonly assigned.
In the case of polyacrylonitrile (PAN), PAN fiber of molecular weight of at least about ~OO,000, and preferably at least l,OOO,OO0 may be employed.
.~
~7~7S~
Particularly useful PAN fiber should have a tenacity o~
at least about 10 g/denier and an energy to break o at least about 22 joule/g. PAN fiber having a mol~cular weight of at leas~ about 400,000, a tenacity oS at least 5 about 15-20 g/denier and an energy to break of at least about 22 joule/g is most useful in producing ballistic resistant articles; and such fibers are disclosed, for example, in U.S. 4,535,027.
For improved ballistic resistance of the fabric 10 article, the fiber has a tensile modulus which pref-erably is at least about 500 g/den, more preferably is at least about 1000 g/den and mo5t preferably is at least about 1300 g/den. Additionally, the ECP fiber has an energy-to-break which preferably is at least about ~2 15 J/9~ more preferably is at least about 50 J/g and most preferably is at least about 55 J/g.
In the fabric of the invention, the fiber network can have various configurations. For example, a plurality of fibers can be grouped together to form a twisted or untwist~d yarn. The fibers or yarn may be formed a~ a felt, knitted or woven ~plain, basket, satin and crow ~eet weaves~ etc.) into a network~ or ~ormed into a network by any of a variety of conventional tech-nique~. For example, the fiber~ may be formed into 25 wo~en or nonwoven cloth layers by conventional tech-niques.
A preferred embodiment of the present invention includes multiple laycrs of ~lastomeric material coated fiber networks. The l~yer~ individually retain the hi~h flexibility char~cteristic of textile fabrics and remain separate ~rom each other. The multilayer article exhi-~its the flexibility o~ plied fabric~, and is readily dis~inguishable from the compositc structure6 de-ccribed in co-pending U.S. Patent No. 4,623,574 of Harpell, et al. and entitled "Ballistic Resistant Composite Article~ ~Attorney Docket No. 82-2334). Vests and other articles of clothing comprised of multiple layers o fabric constructed in accordance with the pre~
~ ;~7D~75~
sent invention have good flexibility and comfort coupled with excellent ballistic protection.
The flexibility of the ballistic resistant fabric structures of the present invention is demonstrated by 5 the following test: A 30 cm square fabric sample com-prised o~ multiple fabric layers having a total areal density of 2 kg/m2, when clamped in a horizontal orien-tation along one side edge, will drape so that the oppo-site side edge is at least 21 cm below the level of the 10 clamped side.
The multiple layers of fabric may be stitched together to provide a desired level of ballistic pro-tection; for example, as against multiple ballistic impacts. However, stitching can reduce the flexibility Coated fibers may be arranged (in the same fashion as uncoated fibers) into woven, non-woven or knitted fabrics. The fabric layers may be arranged in parallel arrays and/or incorporated into multilayer fabric arti-cles. Furthermore, the fibers, used either alone orwith coatings, may be wound or connected in a conven-¦ tional fashion.
The proportion of coating in the fabric may varyfrom relatively small amounts (e.g. 0.1~ by weight of fibers) to relatively large amounts (e.g. 60% by weight of fibers), depending upon whether the coating material has any ballistic-resistant properties of its own (which is generally not the case) and upon the rigidity, shape, heat resistance, wear resistance, flammability resis-tance and other properties desired for the fabric. Ingeneral, ballistic-resistant fabrics of the present invention containing coated fibers should have a rela-tively minor proportion of coating (e.g. 0.1-30%, by weight of fibers), since the ballistic-resistant proper-ties are almost entirely attributable to the fiber.Nevertheless, coated fabrics with higher coating con-tents may be employedl ~7~751 _g The coating 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 li~uid, a sticky solid or particles 5 in suspension or as a fluidized bed. Alternatively, the coating may be applied as a solution or emulsion in a suitable solvent which does not adversely affect the properties of the Eiber at the temperature of applica-tion. While any liquid capable of dissolving or dis-10 persing the coating polymer may be used, preferredgroups of solvents include water, paraffin oils, aromatic solvents or hydrocarbon solvents, with illus-trative specific solvents including paraffin oil, xylene, toluene and octane. The techniques used to 15 dissolve or disperse the coating polymers in the sol-vents will be those conventionally used for the coating of similar elastomeric materials on a variety of sub-strates.
j Other techniques for applying the coating to the i 20 fibers may be used, including coating of the high modu-lus precursor (gel fiber) before the high temperature stretching operation, either before or after removal of the solvent from the fiber. The fiber may then be stretched at elevated temperatures to produce the coated fibers. The gel fiber may be passed through a solution of the appropriate coating polymer (solvent may be paraffin oil, aromatic or aliphatic solvent) under conditions to attain the desired coating~ Crystalliza-tion of the high molecular weight polyethylene in the ~ 30 gel fiber may or may not have taken place before the fiber passes into the cooling solution. Alternatively, the fiber may be extruded into a fluidized bed of the appropriate polymeric powder.
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 contempIated that the coating may be applied to the prec~rsor material. In this embodiment, the desired and preferred tenacity, modulu~ and other propertie~ o~ the fiber should be judged by continuing the manipulative process on tha fib~r precur~or in a manner corr~ponding to ~hat employed on the coated fiber precur~or. Thus, 5 for example, if the coating i~ applied to the xorog~l fiber described in U.S.Patent No. 4,623,574 of Kave~h et al,, and th~ coated xerogel fiber i9 then stretched under d~fined temp~rature and ~tretch ratio condition~, th~ applicable fib~r tena~ity and fiber 10 modulu~ value~ would b~ the m~ured values of ~n uncoated xorogel ~ib~r which i3 ~imilarly strQtched.
A preferr~d co~ting t~chnique i~ to fonm a n~twork layer and thon dip tho n~t~ork into a bath of ~ ~olution containing th~ 1GW modulu~ ~la~tomeric co~ting 15 mat~rial. Evaporation of the ~olv2nt produce~ an ela~tomeric materlal coae~d f~bric. Th~ dip~ing pro-cedure ~ay b~ rop~at~d a~ r~quired to plac~ a d~3ired amount of ol~tom~ric coAting on th~ fibor~.
A wide vari~ty of ~la~tomeric materials and formulation~ ~ay b~ utiliz~d in this inv~ntion. The e ~ential r0quircm~nt i~ th~t th~ elastomeric material havo th~ ~propr~aSoly low ~odulu~. Repr~ntative ex~mple~ o ~u~t~bl~ ela~to~0r~ of tho olautom~ric mat~ri~l h~v~ th~ir ~tructur~ rop~rti~ ormulations tog~th~r with ~ro~linking procedur~ ~u~marized ~n th2 ~ 9~L __ ~ , Volumo 5 in the ~ction ~lA~o~r~-Syn~hQtic~ (Jolln ~ y ~ Son~ Inc., 1964).
Fo~ ~xampl~, any of tho ollowlng ~a~eri~l~ m~y be employads polybut~dl~n~, polyi~opren~, natur~l rubber, sthyl~n~-pro~yl~n~ copolym~r~, e~hyl~n~-propylene-diene terpolymor~, poly3ulfid~ polym~rs, ~olyur~than~ ol~to-mar~, chloro~ulfonated polye~hylen~, polychloropr0ne, plaeticized polyvinylchlorido u~ing dioctyl phtha~ or oth~r pla~ic~r~ w~ll known in tho art, but~di~ne ~crylonitril~ ola~tomer~, poly(l~obutyl~n~-co-is0pr~no), polyacrylat~3, polyo3~rs, poly~th~r~, ~luoro~la~tom~r5, ~ilicone ~la~tom~rs, thQrmopla3~ic ~ tom~r~, copoly-m~rs o~ ethyl~n~.
4~5~L
Particularly u~ful ela~tomers ar~ block copolym~rs o~ con~ugat~d di~ne~ and vinyl aromatic ~onomers.
Butadien~ ~nd isopren~ ar~ prQ~rred conJugated dl~n~
ela~tomers. 5tyr~ne, vinyl toluene and t~bu~yl ~tyrene 5 are preferr~d conjugate~ aromatic monomer~. alock copolym~r~ lncorporating polyi~oprene may b~ hydrogena-t~d to produc~ th~rmopla~tic ~la~tomer~ having saturated hydsocarbon ~la~tomor s~g~a~t~. Th~ polymers may be simpl~ tri~block copolymer~ o the type A-~-A, multi-10 block copolym~r~ of the typ~ ~AB)n(n~2-10) or radial configuration copolymers of th~ typ~ R-(~A)x(x~3-150);
wh~rcin A i~ a block from a polyvinyl aromatic monomer ~nd ~ i~ a block from a conjugatsd di~n~ ~la~tomer.
M~ny o tho~ polym~rs ~o produc~d commerci~lly by the 15 Shell Ch~mlc~l CoO and d~crib~d $n th~ bull~tin ~Rraton*
Th~rmopl~tic Rubbor~, SC 68~
Mo~t pref~rably, th~ ~la3to~sric mat~rial consi~ts o at l~aRt ono o~ ths abov~ m~ntion~d ela~tomer~. Th~
low modulus ~1~ to~oric ~at~rial m~y ~l~o include fil-lar~ such as ca~bon black, ~ilica, et~. and m~y b~ext~nd~d with oil~ and vulc~nl2~d by ~ulfur, peroxide, m~tal oxid~, or radiation curo ~y$tom~ u~ing msthod~
w~ll known to rubbor t~chnologi~t~ nd~ of differ~n~
ela~tomeric matorial~ m~y b~ u~d tog~ther or on~ or 25 mor~ ~lA~to~r ~at~ri~l~ ~ay b~ bl~ndod with on~ or ~ore th0r~0~1a~tlc~. High d~n~ity, low d~n~ity, and linaar low don~ity polyothylon~ ~ay bo ~ros~-llnk~d to obtain a ~atrlx mat~rial o~ appropri~t~ prcport~o~, ~ith~r alone or a~ bl~nd~. In ~ry ~n~tanco, th~ ~odulu~ o~ the co~tin~ 3hould not ~xc~d ~bout 6000 p~i (41,300 kPa), pr~f~rably i~ s than about 5000 p~i (34,500 kPa), more preferably 1~ than 100 p~i ~6900 kP~) and mo~t pref~rably i~ l~ss than abou~ 500 p~i (3~50 kPa).
A coatod yarn can b2 produc0d by pulling a group of fibers through th~ ~olution o low modulu~ olastomoric mat~ri~l to ~u~t~nti~lly coat ~ch of tho lndi~idual fib~r~, and then ~v~por~ting t~ ~olv~nt to form th~
coat~d yarn. Th~ yarn can th~n ~ employ~d to form *Indicates Trademark 75~
coated fabric layers which in turn, can be used to form desired multilayer fabric structures.
Multilayer fabric articles may be constructed and arranged in a variety of forms. It is convenient to 5 characterize the geometries of such multilayer fabrics by the geometries of the fibers and then to indicate that substantially no matri~x material, elastomeric or otherwise, occupies the region between fabric layers.
One such suitable arrangement is a plurality of layers 10 in which each layer is comprised of coated fabric fibers arranged in a sheet-like array and successive layers of such fabrics are rotated with respect to the previous layer. An example of such multilayer fabric structures is a five layered structure in which the second, third, fourth and fifth layers are rotated +45~, -45, 90 and o, with respect to the first layer, but not necessarily in that order. Other exarnples include multilayer fab-rics with alternating fabric layers rotated 90 with respect to each other.
In various forms of the fabric of the invention, I the fiber network occupies different proportions of the total volume of the fabric layer. Preferably, however, the fiber network comprises at least about 50 volume percent of the fabric layer, more preferably between about 70 volume percent, and most preferably at least j about 90 volume percent. Similarly, the volume percent I of low modulus elastomeric material in a fabric layer is preferably less than about 15 Vol %, more preferably is less than about 10 Vol %, and most preferably is less than about 5 Vol %.
The specific weight of the fabric layer is expressed in terms of the areal density (AD)o This areal density corresponds to the weight per unit area of the fabric layer. Preferably, the fabric layer areal density is less than about 0.3 kg/m2; more preferably the areal density is less than about 0.2 kg/m2 and most preferably, the areal density is less than about 0.1 kg/m2 -75~
It has been discovered that coated fabric comprised of strip or ribbon tfiber with an aspect ratio, ratio of fiber width to thickness, of at least about 5) can be even more effective than other forms of fiber or yarn 5 when producing ballistic resistant articles. In particular embodiments of the invention the aspect ratio of the strip is at least 50, preferably is at least 100 and more preferably is at least 150 for improved performance~ Surprisingly, even though an ECPE
10 strip material had significantly lower tensile proper-ties than an ECPE yarn material of the same denier but generally circular cross section, the ballistic resis-tance of the coated fabric ccnstructed from ECPE strip was significantly higher than the ballistic resistance 15 of the coated fabric constructed from the ECPE yarn.
Most screening studies of ballistic composites ; employ a .22 caliber, non-deforming steel fragment of specified weight, (19 grains) hardness and dimensions ! (Mil-Spec. MIL-P-46593A(ORD)). Limited studies were 20 made employing .22 caliber lead bullet weighing 40 grains. The protective power of a structure is normally expressed by citing the impacting velocity at which 50%
of the projectiles are stopped, and is designated the V50 value.
Usually, a flexible fabric, "soft" armor is a multiple layer structure. The specific weight of the multilayer fabric article is similarly expressed in terms of the areal density (AD). This areal density corresponds to the weight per unit area of the multiple layer structure.
To compare structures having different V50 values and different areal densities, the following examples state the ratios of (a) the kinetic energy tJoules) of the projectile at the V50 velocity, to (b) the areal density of the fabric tkg/m2). This ratio is designated as the Specific Energy Absorption tSEA).
The following examples are presented to provide a more complete understanding of the invention. The ~7~
~,pecific technique~, conditions, materials, proportion~
and reported data ~et forth to illustrate the principles of the invention ar~ exemplary and should not be con-strued a~ limiting the ~cope of th~ invention, EX~MPLE F-l A low areal den ity (0.1354 kg~m~) pl~in weave fabric having 70 end~/inch (28 end3/cm) in both the warp and fill direetion was pr~pared from untwisted yarn si2~d with low mol~cular weight polyvinyl~lcohol on a 10 Crompton and Rnowl~ *box loom. After weaving, the sizing was removed by washing in hot water (60 72~C).
The yarn used for ~abri~ preparation had 1~ filaments, yarn denier of 203, modulu~ of 1304 g~denier, tenacity of 28,4 g/denier, alongation of 3.1~ and energy~o-break 15 f 47 J/9. A multilayer fabric targct F-l wa compri ed of 13 layer3 o f~bric and had a total areal density (AD) o~ 1.76 kg/m2O All yarn tcn~ile properti~ wera me~sured on an In~tron te~ter using tire cord b~rrel clamp~, gauge lsngth of 10 inch~ (25.4 cm), and cross-head speed of 10 inches/~inute (25.4 cm/min).XAMPLE F-2 Fabric wa~ woven in a manner similar to that u3ed for pr~paration o fabric F~ xc~pt that a higher deni~r yarn (de3ignat0d SY-l) having 118 filament~ and approxim~tely 1200 d~niar, 1250 9 denier modulu~, 30 9 denier tenacity, and 60 J/g ener~y-to-break) wa~ used to produce ~ pl~in wea~e ~abric having areal den~ity of approximately 0.3 kg/m2 and 28 end~/inch (11 ends/cm).
Slx layer~ of this fabric were a3semblad to prepare a balli~tic targot F-2.
* Indicates Trademark ~, ~
~.~'7~'75~
A 2 x 2 basket weave fabric was prepared from our standard yarn (SY-l) having 34 ends/inch (13.4 ends/cm)~ The yarn had approximately 1 turnJinch and 5 was woven without sizing. The fabric areal density was 0,434 kg/m2 t and a target F-3 comprised of 12 fabric layers had an ar~al density of 5.21 kg/m2.
This fabric was prepared in an identical manner to 10 that of Example F-l except that the yarn used had the following properties- denier 270~ 118 filaments, modulus 700 g/denier, tenacity 20 g/denier and energy-to-break 52 J/9O The fabric had an areal density of 0.1722 kg/m2~ ~ target F-4 was comprised of 11 layers of this fabric.
Yarn SY-l wa~ used to prepare a high denier non-crimped fabric in the following manner. Four yarns were combined to form single yarnQ of approximately 6000 denier and these yarns were used to form a nvn-crimped fabric having 2B ends~inch in both the warp and fill ~irection. Yarn SY 1, having yarn denier of 1200 was used to knit together a multilayer structure. Fabric areal density was OL705 kg/m2. A ballistic target F-5 25 wa~ compri~ed of seven layers of this fabric.
Eight one-foot-square pieces of Kcvla~ 29 ballistic fabric, manufactured by Clark Schwebel, were assembled to produce a target F-6 having an areal den~ity of 2.32 kg/m2, The fabric waR designated Style 713 and was a plain weave fabric comprised of 31 ends per inch of untwisted 1000 denier yarn in both the warp and fill direction.
This sample was substantially identical to sample F-6, except that ~ix layers of ~evla~ 29 were used to produce a target F-7 having a total target areal density of 1.74 kg/m2.
*Indica-tes Trademark ~L~7~75~
Ballistic Results Against .22 Caliber Fragments Fabric targets one-foot-square (30.5 cm) and comprised of multiple layers of fabric were tested against .22 caliber fragments to obtain a V50 value.
Fabric properties are shown in Table lA and ballistic results are shown in Table lB.
TABLE lA
FABRIC PROPERTIES
10 E~m~le Yarn Yarn Yarn W~ave Denier Modulus Energy-(g/den) to-break (J/g) F-l 203 1304 47 Plain F-4 270 700 52 Plain 15 F-2 1200 1250 60 Plain F-3 1200 1250 60 2x2 Lasket F-5 6000 1250 60 non-cr~ed TABLE lB
Ballistic Results Against .22 Caliber Fra~ments ~le Fabric AD Target ~D V50 SEA
No. (kg/m2) _ (kg/m ) _ (ft/sec) (J/m2 F-l 0.1354 1.76 1318 50.5 F-4 0.1722 1.89 951 24.4 25 E`-2 0.316 1.90 1165 36.9 F-3 0.434 5.21 1318 17.1 F-5 0.705 4.95 1333 18.0 Sample F-l gave the best ballistic results, sug-gesting that a combination of high modulus yarns and ~ 30 fine weave fabric comprised of low denier yarn has par-ticular merit.
Example FB-2 Ballistic Results A2~1n .22 Caliber Lead Bullets Sample targets were evaluated against .22 caliber lead bullets, and the striking and exit velocities of the bullets were individually recorded. ~abric proper-ties are shown in Table 2A, and ballistic results are shown in Tables 2B and 2C.
~ ~7~75~
~17~
Table 2A
Properties o Plain Weave Fabric~
Example Yarn TypeD~nier Mbdulus Energy~to-Bre~k (g/den.) _(J/~?
F~l ECPE 203 1304 47 F 6 Kevlar*29 1000 700 29 F-7 Kevla~ 29 1000 700 29 Table 2B
Ballistic Results Against .22 Caliber Bullets ~xample Fabric AD Target AD V(in~ V(out) SEA
( kQhn ) _ _( ks~ (Jm2/kg 15 F-l 0.1354 1.76 1212 0 100.5 1198 9~2 32.2 1194 838 ~9.5 1193 958 34.6 11~1 0 93.8 7 0.29 1.741175 0 95.8 11~6 760 57.5 120~ 1040 25.5 1176 963 31.6 1216 9~6 43.1 F-6 0.29 2.231198 0 74.6 1214 721 49.6 1181 0 72.5 1200 589 56.9 1181 0 72.5 F-4 0.1722 1.89 1200 1100 14.6 1184 1091 13.5 1225 1137 13.2 1144 1037 14.8 *Indicates Trademark '~.
~.Z74~5~
Sample A~erage SEA 96 Bullets __ ( iC~m2 ) _ Sto 2ped F-l 66 .8 50 5F-7 50 . 0 20 F-6 65 . 2 60 F-4 14.0 0 A eomparison of the ballistic results of examples F-l and F-4 indicates that higher modulus yarns are much 10 superior for ballistic protection against .22 caliber bull~ts when woven into a fine weave fabric comprised of low denier yarn. These data also indicate that the F-l f~bric is ~uperior to Kevla~ ballistic fabric (F-7) in current use, with respect to both the percen of bullets 15 stopped and the average SEAo EXAMPLE C-l The individual fabric layers of the target des-cribed in Example F-l, after ballistic testing against both 22 caliber fragments and .22 caliber bullets, was 20 soaked overnight in a toluene ~olution o~ Kraton*D1107 (50 g/litre). ~rato~ D1107, a commercial product of the Shell Chemical Company, is a triblock copolymer of the polystyrene~polyisoprene-polystyrene having about 14 wt % styrene, a tensile modulus of about 200 p~i (measured 25 at 23C~ and having a Tg o~ approximately -60C. The fabric layers w~re removed from the solvent and hung in a fume hood to allow the solvcnt to cvaporate. A target C-l, contalning 6 wt ~ elastomer, was reassembled with 13 fabrlc layer~ for additional ballistic testing.
EXAMPLE C-2A and C-2B
Six one~foot-square fabric layers of the type describad in example F-2 were assembled together and designated sample C-2A.
Six fabr1c layers identical to thos2 o~ example C-2A, were immersed in a toluene solution of Xraton*G1650 (35 g/litre) for three days and were hung in a fume hood to allow solvent evaporation. Xraton*G1650, a triblock thermoplastic elastomer produced by Shell Chemical Co, .~ *Indlcates Trademark 7S~
--lg--has the structure polystrene-polyethylenebutylene-poly-styrene and has about 29 wt ~ styrene. Its tensile modulus is about 2000 psi ~measured at 23C), and its Tg is approximately -60C. The panel layers each had an 5 areal density of 1.9 kg/m2 and contained 1 wt % rub-ber. The layers were assembled together for ballistic testing and were designated sample C-2B.
EXAMPLES C4 ~C10 Each target in this series was comprised of six 10 one-foot-square layers of the same fabric, which had been prepared as described in example F-2. The f iber areal density of these targets was 1.90 kg/m2.
Sample C-~ was compri~ed of untreated fabric.
Sample C-5 was eomprised of fabric coated with 5.7 15 wt % Krato* G1550. The fabric layers wsre soaked in a toluene solution of the Krato~*1650 ~65 g/litre) and ~hen assembled after the solvent had besn evaporated.
Sample C-6 was prepared in a similar manner to sample C-5 except that after the sampla had been dipped and dried, it was redipped to produce a target having 11.0 wt % coating.
Sample C-7 was prepared by sequentially dipping the fabric squares in three ~olutionq of ~raton*
D1107/dichloromethane to produce a target having 10.8 wt 25 % coating. Fabric layers were dried between succe~sive coating~. Concantration~ of the Kraton*D1107 thermo-plastic, low modulus elastomers in the three coating solutions were 15 g/L, 75 g/L and 15 g~L, in that order, Sample C-8 was prepared by dipping fabric layers into a colloidal silica solution, prepared by adding three volume parts of de-ionized water to one volume part of Ludo~AM, a product of DuPont Corporation which i9 an aqueou3 colloidal ~ilica dispersion having 30 wt silica of average particle ~ize 12 nm and surface area of 230 m2/~.
Sample C-9 was prepared from electron beam irradi-ated fabric irradiated under a nitrogen atmosphere to 1 Mrad using an Electracurtain*apparatus manufactured by *Indicates Trademark ~7~
Energy Sciences Corporation. The fabric squares were dipped into a Eudox~AM solution diluted with an equal volume of deionized water.
Sample C10 was prepared in a ~imilar manner to 5 ~xample C-9, except that the fabric was irradiated to 2 Mrads and was subsequently dipped into undiluted Ludox*
AMo Thi~ level of irradiation had no significant effect on yarn tensile poroperties.
EXAMPLE C-ll A plain weave ribbon fabric was pr2pared from poly-ethylen2 ribbon 0.64 cm in width, having modulus of 865 g~denier and energy-to-break of 46 J/g. Fabric panels ~layers) one-foot-square (30.5 cm) were soaked in dich-loromethane solution of Kraton~D1107 (lOg/litre) for 24 15 hour~ and then removed and driedO The 37 panels, having a total ribbon areal density of 1.99 kg/m2 and 6 wt ~
rubber coating were as~embled into a multilayer target sample C-ll for balliQtic testing.
EXAMPLE CB-l As shown below, the damaged target C-l stopp~d all .22 caliber bullets fired into it. TheRe results were superior to those obtained for the same fabric before it was rubb~r coated and much superior to the Revla~ bal-listic fabrics. (See Example FB-2,) 25 V(in) V~out) SEA
~ft/sec)(ft~sec) ~Jm2 1218 0 101.5 1182 0 95.6 1172 0 94.0 1159 0 91.9 Although this fabric wa~ highly damaged, a .22 calib2r fragment wa3 ~ired into thc target at an impacting v210city of 1381 ft/sec and was stopped, corresponding to an SEA of 55,5 Jm2/kg. This result indicates that th~ low modulus rubber coating also improves ballistic rssistance against .22 caliber fragment~. The VS0 value or the uncoated fabric *Indicates Trademark 75~L
(example F-l) was 1318 ft/sec, corresponding to an SEA
of 50.5 Jm2/kg. The highest partial penetration velocity for Example F-l was 1333 ft/sec, corresponding to an SEA of 51.7 Jm2~kg.
~inally, thi~ highly damaged sample was ballisti-cally tested against .38 caliber bullets according to test procedure NILECJ-5TD-0101.01. Three .38 caliber bullets having impacting velocities of 780, 803 and 831 ft/sec, respectively, were stopped by the target, and 10 the bullet îndentations into the clay backing were less than 1~2 inchesO The target sample easily me~ the spacification. Even though this target had an areal density of only 1.76 kg~m2, it met or exceeded the U.S.
Military specifications for Type 1 and Type lA Kevla~ 29 15 target~ having a greater areal density of 2.24 kg/m2 ~Specification MIL-C-44050). This wae accomplished in spite of the fact that the total number of ballistic impacts on this single target greatly exceeded reguire-ments. It is, therefore, quite apparent that the fabric 2~ articles of the present invention can provide required levels of ballistic protection while employing a lighter weight of material.
Targets C-2A and C-2B were marked with a felt pen to divide it ~nto two, 6in X 12in rectangles. The V50 value~ for each target wa~ determined against .22 cali ber fragments using only one of tha rectangles (one half of the target). Each target was immersed in watar for ten minutes, and the hung for three minutes before determination of a VS0 value using the undamaged rec-tangle. Data shown below clearly indicate that the small ammount of rubber coating ha~ a beneficial effect on the balli~tic performance of the fabric tar~et when wet.
*Indicates Trademark ~4~5~
V50 (~t/s~c) Target C-2A Target C-2B
(untreated) _ (lwt ~ Elastomer) (Ballis~ic Studies uQing 28X28 plain weave, coated fabrics) Ballistic testing usin~ .22 caliber fragments 10 against six-layer fabric targets having fiber areal den sity of 1.90 kg~m2 showed that elastomeric coatings improved ballistic performance, but silica coatings were inefective.
15 Sample CoatingV50 SEA
(ft/sec)(~m2/k~) C-4 none 1165 36.9 C-5 Kraton*G1650 1228 41.0 (5,7 wt %) 20 C-6 Rrato~ G1650 1293 45.4 (11 wt %) C-7 Krato~* D1107 1259 43.1 110.8 wt %) C-8 Silica1182 38.0 (3.4 wt ~
C-9 Silica1150 3600 (7.2 wt %) C-10 Silica1147 35.8 (17 wt ~) Sample C-ll was tested ballistically and exhibited a V50 value of 1156 ft/sec determined against .22 caliber fragments. This corresponded to a SEA value of 34.4 Jm2/kg. This target exhibited good ballistic properties in spite of the fact that ribbon ~tress-strain properties were inferior to those of most of ~he ECPE yarns used in this studyO
*Indicates Trademark a '. ~ ~
;-:~I.X~747~3 A V50 value of 1170 ft/sec against .22 caliber bullets was obtained for sample C-ll, whereas samples C-5, C-6 and C-7 allowed bullets having a striking velocity of approximately 1150 ft/sec to pass through 5 the target with a velocity loss of less than 250 ft/sec. This indicates that the ribbon fabric is par~
ticularly effective against .22 caliber lead bullets~
Having thus described the invention in rather full detail, it will be understood that these details need 10 not be strictly adhered to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.
.1
Claims (23)
1. An article of manufacture comprising:
at least one network comprising fiber or yarn selected from the group of extended chain polyethylene and extended chain polypropylene fibers, extended chain polyvinyl alcohol fiber and extended chain polyacryloni-trile fiber wherein said fiber and yarn have a denier of not more than about 500 and a tensile modulus of at least about 200 g/denier.
at least one network comprising fiber or yarn selected from the group of extended chain polyethylene and extended chain polypropylene fibers, extended chain polyvinyl alcohol fiber and extended chain polyacryloni-trile fiber wherein said fiber and yarn have a denier of not more than about 500 and a tensile modulus of at least about 200 g/denier.
2. An article as recited in claim 1, wherein said fiber and yarn are polypropylene fiber and yarn having a tensile modulus of at least about 200 g/den.
3. An article as recited in claim 1, wherein said polyolefin fiber and yarn are polyethylene fiber and yarn having a tensile modulus of at least about 500 g/den.
4. An article as recited in claim 1, wherein said fiber and yarn have a tensile modulus of at least about 500 g/denier and an energy-to-break of at least about 22 J/g.
5. An article as recited in claim 1, wherein said fiber and yarn have a tensile modulus of at least about 1000 g/denier and an energy-to-break of at least 50 J/g.
6. An article as recited in claim 1 wherein said fiber and yarn have a tensile modulus of at least about 1300 g/denier and an energy-to-break of at least about 55 J/g.
7. An article as recited in claim 1, wherein said fiber and yarn have a denier of not more than about 300.
8. An article as recited in claim 1, wherein said fiber and yarn have a denier of not more than about 250.
9. An article as recited in claim 1, wherein said fiber and yarn has a tensile modulus of at least about 1300 g/den.
10. An article as recited in claim 1, wherein said network comprises yarn having a tensile modulus of at least about 1800 g/den.
11. An article as recited in claim 1, wherein said network has a plain weave pattern.
12. An article as recited in claim 1 further com-prising:
a low modulus elastomeric material, which coats the fiber or yarn of said network and has a tensile modulus of less than about 6,000 psi (41,300 kPa).
a low modulus elastomeric material, which coats the fiber or yarn of said network and has a tensile modulus of less than about 6,000 psi (41,300 kPa).
13. An article as recited in claim 12, wherein said elastomeric material has tensile modulus of less than about 5,000 psi.
14. An article as recited in claim 12, wherein said elastomeric material has a tensile modulus of less than about 1,000 psi.
15. An article as recited in claim 12, wherein said elastomeric material has a tensile modulus of less than about 500 psi.
16. An article as recited in claim 12 comprising a plurality of network arranged as multiple layers, the fiber or yarn of each of said layers being individually coated with said low modulus elastomeric material.
17. An article as recited in claim 16, wherein said layers have an arrangement in which the fiber alignment directions in selected layers are rotated with respect to the alignment direction of another layer.
18. An article as recited in claim 12 wherein said network has a plain weave pattern.
19. An article as recited in claim 12, wherein said low modulus elastomeric material comprises less than about 10 vol % of said layer.
20. An article as recited in claim 12, wherein said elastomeric material consists essentially of a polystyrene-polyisoprene-polystyrene, tri-block copolymer.
21. An article as recited in claim 12, wherein said elastomeric material consists essentially of a polystyrene-polyethylene/butylene-polystyrene tri-block copolymer.
22. An article as recited in claim 12, wherein the network comprises yarn having a denier of less than about 250, the fiber of said yarn having a modulus of at least about 1200 g/den, the areal density of said yarn of the network is less than about 0.18 kg/m2, and the network has a plain weave pattern.
23. An article as recited in claim 22, wherein the yarn of the network has about 5 wt% coating of said elastomeric material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US71034085A | 1985-03-11 | 1985-03-11 | |
| US710,340 | 1985-03-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1274751A true CA1274751A (en) | 1990-10-02 |
Family
ID=24853625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000502594A Expired CA1274751A (en) | 1985-03-11 | 1986-02-25 | Ballistic-resistant fine weave fabric article |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH0645218B2 (en) |
| CA (1) | CA1274751A (en) |
| IL (1) | IL78064A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06174396A (en) * | 1992-12-01 | 1994-06-24 | Kuraray Co Ltd | Protective clothes |
| KR101261072B1 (en) * | 2004-06-21 | 2013-05-06 | 이 아이 듀폰 디 네모아 앤드 캄파니 | Fibrous structures with enhanced ballistic performance |
| US8008217B2 (en) * | 2005-06-21 | 2011-08-30 | E.I. Du Pont De Nemours And Company | Fabrics with strain-responsive viscous liquid polymers |
| US7994075B1 (en) * | 2008-02-26 | 2011-08-09 | Honeywell International, Inc. | Low weight and high durability soft body armor composite using topical wax coatings |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7605370A (en) * | 1976-05-20 | 1977-11-22 | Stamicarbon | PROCESS FOR THE CONTINUOUS MANUFACTURE OF FIBER POLYMER CRYSTALS. |
| US4356138A (en) * | 1981-01-15 | 1982-10-26 | Allied Corporation | Production of high strength polyethylene filaments |
| US4457985A (en) * | 1982-03-19 | 1984-07-03 | Allied Corporation | Ballistic-resistant article |
| JPS59199809A (en) * | 1983-04-20 | 1984-11-13 | Japan Exlan Co Ltd | Polyacrylonitrile yarn having high strength and its preparation |
-
1986
- 1986-02-25 CA CA000502594A patent/CA1274751A/en not_active Expired
- 1986-03-06 IL IL78064A patent/IL78064A/en unknown
- 1986-03-11 JP JP61053515A patent/JPH0645218B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62135358A (en) | 1987-06-18 |
| IL78064A0 (en) | 1986-07-31 |
| IL78064A (en) | 1990-09-17 |
| JPH0645218B2 (en) | 1994-06-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |