Ordnance – Shields – Body
Reexamination Certificate
1998-08-18
2001-08-21
Johnson, Stephen M. (Department: 3641)
Ordnance
Shields
Body
C089S036020, C002S002500
Reexamination Certificate
active
06276255
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of soft body armor and in particular soft body armor having protective elements incorporating aramid fiber cloth such as KEVLAR™ 129 aramid fiber woven cloth or SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix.
BACKGROUND OF THE INVENTION
Body armor typically comprises a jacket or vest which serves to hold sheets of typically KEVLAR™ 129 aramid fiber woven cloth, manufactured by E. I. DuPont de Nemours and Company, or other aramid fiber cloth, or SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix, manufactured by Allied Signal, close to the body so as to provide bullet-resistant soft body armor. Conventionally, many sheets of either aramid fiber cloth or SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix, sometimes as many as 55 sheets, are overlaid and held as packets in pocket-like compartments within the jacket or vest. SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix, being overlaid synthetic fiber strands held within a resin binder, is stiffer than aramid fiber cloth which is a woven material of synthetic aramid fibers. SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix material is sufficiently stiff that a stack or packet of sheets may be inserted into pocket-like compartments in a jacket or vest without having to be sewn together. Aramid fiber cloth on the other hand is typically sewn together in the manner of quilting.
Previously, soft body armor bas relied on individual packets of multiple plies of SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix and individual packets of multiple plies of aramid fiber cloth, the packets each stacked one on top of the other so as to intersperse packets of one between packets of the other. The packets arc held vertically oriented within a pocket or like vertical compartment in the body armor. Applicant is aware of “POINT BLANK BODY ARMOR” of Amity, N.Y., U.S.A. which markets soft body armor having interspersed packets of aramid fiber cloth and packets of SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix, and in particular having within a single vertical compartment front and back packets of solely aramid fiber cloth and, sandwiched in-between, a middle packet of solely SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix sleets. The front and back packets of aramid fiber cloth are quilted.
Applicant is aware of U.S. Pat. No. 5,179,244 which issued on Jan. 12, 1993 to T. Tyler Zufle for an invention entitled “Reinforced Soft and Hard Body Armor”, U.S. Pat. No. 5,180,880 which issued on Jan. 19, 1993 to T. Tyler Zufle for an invention entitled “Soft Body Armor”, and U.S. Pat. No. 5,306,557 which issued on Apr. 26, 1994 to Thomas J. Madison for an invention entitled “Composite Tactical Hard Body Armor”.
Zufle '224 discloses body armor comprised of alternating multiple packets of aramid fiber cloth and SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix. Zufle '880 discloses body armor comprised of aramid fiber cloth outer single plies
48
and
50
, eight plies of SPECTRA SHIELD™ high molecular weight polyethylene filament in a flexible resin matrix
52
and
54
and ten plies of aramid fiber cloth
56
. Madison discloses body armor which includes SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix layers
4
,
7
and
9
and non-woven aramid fiber layers
3
and
6
.
The object of the present invention is to provide soft body armor which combines the attributes of KEVLAR™ aramid fiber woven cloth or like aramid fiber cloth (hereinafter also referred to by the letter “A”) and SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix (hereinafter also referred to by the letter “S”) in an interleaved sandwich as opposed to a sandwich of packets of solely aramid fiber cloth and solely SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix; and in particular interleaved so as to alternate one and two sheets of aramid fiber cloth between two sheets of SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix; for example in the ratio of 2 sheets of SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix: 2 sheets of aramid fiber cloth: 2 sheets of Spectra: 1 sheet of aramid fiber cloth and so on in a 2:1 (S:A) ratio, repeated for a total of 18 sheets of SPECTRA™ high molecular weight polyethylene filaments in a flexible resin matrix and 9 sheets of aramid fiber cloth. It has been found that this interleaved layering exhibits many improved characteristics over stacks of solely aramid fiber cloth or solely SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix.
SUMMARY OF THE INVENTION
It has been found that interleaving single plies of woven fiber cloth, as inhereafter defined, between sheets of cross plied unidirectional tape, as hereinafter defined and alternatively referred to by its acronym “CPUT”, in a 2:1 (CPUT:woven fiber) ratio reduces the overall number of sheets required to provide the level of protection equivalent to threat level IIA, II or IIIA prior art soft body armor incorporating a greater number of sheets. As compared to prior art soft body armor, a typical result of the soft body armor according to the present invention is a 20% decease in weight as indicated by a decrease in areal density, a decrease in bulk, an increase in flexibility of the armor due to the interleaving of sheets of woven fiber cloth which provide friction reducing surfaces between sheets of cross plied unidirectional tape (which otherwise tend to stick to one another), a decrease in cost of manufacturing of the armor due to the decreased areal density, a removal of the requirement for quilting of the woven fiber sheets in that the cross plied unidirectional tape sheets lend sufficient structural rigidity to resist billowing and bunching, a decrease in the level of blunt trauma over purely aramid fiber body armor, an increase in ballistic resistance performance over purely aramid fiber body armor for bullets entering at an angle of for example 30 degrees, an increase in performance under wet conditions over purely aramid fiber body armor which typically loses 40 percent of its ballistic capability when wet, and an increase in performance over purely SPECTRA SHIELD™ high molecular weight polyethylene filaments in a flexible resin matrix body armor when soft body armor according to the present invention is heated such as by fire.
Soft body armor incorporating the present invention has a ballistic panel of a multiple interleaved, generally vertical sandwich construction of woven fiber (“WF”) sheets between sheets of cross plied unidirectional tape (“CPUT”) The interleaved construction may be summarized as interleaved sheets or plies interleaved in an interleave ratio within each of a plurality of layers, the layers forming a non-quilted array between the front and back faces of the ballistic panel. Each layer will always have an interleave ratio between 1:1 (CPUT:WF) and 4:4 (CPUT:WF). The interleave ratio may be between 1:1 and 3:3, or may be between 1:1 and 2:2. In these ratio ranges the ratio of plies of cross plied unidirectional tape to plies of woven fiber cloth may vary but the total number of plies of cross plied unidirectional tape will always be equal to or greater than the total number of plies of woven fiber cloth. The ratio of the interleaving may change from the front to the back of the ballistic panel, for example, 2:2:2:1 (CPUT:WF:CPUT:WF) . . . 2:1:2 (CPUT:WF:CPUT), ic., initially 2:2:2:1 (CPUT:WF:CPUT:WF) then repeating layers of 2:1 (CPUT:WF), with a final backing layer of 2 sheets of cross plied unidirectional tape. The interleave ratio ranges within
Field Bradley J.
Soar Roger
Bishop & Company
Edwards Antony C.
Johnson Stephen M.
Pacific Safety Products Inc.
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