Abstract:
A ballistic resistant panel for use in protective garments. The ballistic resistant panel comprises at least two layers of multiple plies of a woven fibrous material wherein the plies of each layer are loosely stitched together within the respective layer and the layers are fastened together at the periphery of the panel. The loose construction yields a panel that is light-weight and more economic to manufacture.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/408,631 filed Jan. 5, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to protective body armor that meets NIJ Standard-0101.04 for Type IIIA, II and IIA ballistic threats. More particularly, this invention relates to ballistic resistant panels used in such protective garments.  
         BACKGROUND OF THE INVENTION  
         [0003]    Protective garments like personal body armor are constructed with inserts of ballistic resistant panels, which protect the wearer from the impact forces of a fired projectile. Personal body armors are classified into several types by the level of protection they provide. The National Institute of Justice (NIJ) has defined minimum performance requirements for the ballistic resistance of personal body armor according to the type of ballistic threat. According to NIJ Standard-0101.04, which is herein incorporated by reference, ballistic resistant body armor suitable for full-time wear throughout an entire duty shift are classified as Types I, IIA, II, and IIIA. Of these, Type IIIA protects against the greatest ballistic threat followed by Type II, Type IIA, and Type I in decreasing order of ballistic protection. Body armor which provides protection against a greater ballistic threat would also meet the requirements for protection against the lesser ballistic threats under the NIJ classifications. For example, body armor which protects against a Type III ballistic threat also protects against Types II, IIA, and I threat levels. In addition to the level of ballistic protection, it is important that the body armor be comfortable to wear so that that the persons it is intended to protect are more inclined to wear it and may wear it without difficulty over extended periods of time.  
           [0004]    Conventional ballistic resistant panels are constructed of multiple woven plies of high-tensile-strength fibers such as aramid fibers. Examples of ballistic resistant fibers which are commercially available include Kevlar® which is manufactured by E. I. DuPont de Nemours &amp; Company of Wilmington, Del. and Twaron® T-2000 which is manufactured by AKZO NOBEL, Inc. Typically, the woven plies in the ballistic resistant panels are held together with tight stitches sewn through multiple plies. This results in compacted layers which form a more or less solid ballistic panel. In order to protect the wearer of the garment, substantial numbers of compacted layers are used which tends to make the protective garment bulky, heavy and uneconomical. It would be advantageous to have ballistic resistant panels which provide the same protection level as prior art panels but with a lesser number of plies.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the invention to obviate the disadvantages of the prior art.  
           [0006]    It is another object of the invention to provide a ballistic resistant panel for use in protective garments which is light-weight and economical to manufacture.  
           [0007]    It is a further object of the invention to provide a ballistic resistant panel which meets NIJ Standard-0101.04 for Type IIIA, Type II and Type IIA ballistic threats.  
           [0008]    In accordance with an object of the invention, there is provided a ballistic resistant panel comprising at least two layers, the layers having multiple plies of a woven fibrous material, the multiple plies of each layer being loosely stitched together within the respective layer, the layers being fastened together at the periphery of the panel.  
           [0009]    In accordance with another object of the invention, the ballistic resistant panel has three layers, the plies of the first and third layers being loosely stitched together in a square pattern, the second layer being disposed between the first and third layers, and the plies of the second layer being loosely stitched together in a crossed-diagonal pattern.  
           [0010]    In accordance with another object of the invention, the ballistic resistant panel has two layers, the plies of the first layer being loosely stitched together in a square pattern, and the plies of the second layer being loosely stitched together in a crossed-diagonal pattern. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a cross-sectional view of an embodiment of the ballistic resistant panel of this invention which meets NIJ Standard-0101.04 for a Type IIIA ballistic threat.  
         [0012]    [0012]FIG. 2 is a cross-sectional view of an embodiment of the ballistic resistant panel of this invention which meets NIJ Standard-0101.04 for a Type II ballistic threat.  
         [0013]    [0013]FIG. 3 is a cross-sectional view of an embodiment of the ballistic resistant panel of this invention which meets NIJ Standard-0101.04 for a Type IIA ballistic threat.  
         [0014]    [0014]FIG. 4 is a view illustrating a square stitching pattern of the present invention.  
         [0015]    [0015]FIG. 5 is a view illustrating a crossed-diagonal stitching pattern of the present invention.  
         [0016]    [0016]FIG. 6 illustrates the weave of the first and third layers of woven lyotropic liquid crystal polymer fibers of a first embodiment.  
         [0017]    [0017]FIG. 7 illustrates the weave of the first and third layers of woven lyotropic liquid crystal polymer fibers of a second embodiment.  
         [0018]    [0018]FIG. 8 illustrates the weave of the first layer of woven lyotropic liquid crystal polymer fibers of a third embodiment.  
         [0019]    [0019]FIG. 9 illustrates the weave of the second layer of woven lyotropic liquid crystal polymer fibers of a first embodiment.  
         [0020]    [0020]FIG. 10 illustrates the weave of the second layer of woven lyotropic liquid crystal polymer fibers of a second embodiment.  
         [0021]    [0021]FIG. 11 illustrates the weave of the second layer of woven lyotropic liquid crystal polymer fibers of a third embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    The ballistic resistant panel of this invention is constructed of at least two layers of multiple plies of high-tensile-strength fibrous materials. Preferably, the fibrous material is comprised of lyotropic liquid crystal polymer fibers. An example of which is ZYLON® manufactured by Toyobo Co., Ltd. of Osaka, Japan. ZYLON® is a high-tensile-strength fiber which consists of rigid-rod chain molecules of poly(p-phenylene-2,6-benzobisoxazole)(PBO). The lyotropic liquid crystal polymer fibrous material within the embodiments described herein is preferably constructed of fibers that have a denier of 500 and a thickness of 0.037 in.  
         [0023]    As described above, prior art panels typically are held together with tight stitches sewn through multiples plies of ballistic resistant material. The tight stitching tends to compact the layers of the panel, yielding a more or less a solid panel. Unlike the prior art, loose stitching is used to join the multiple plies within the layers of the panel of this invention. This allows for some movement within each layer of the panel. The layers are then fastened together at the periphery of the panel which further provides for a generally loose panel construction. Since the layers are held together only at the periphery of the panel, the layers are allowed to have independent movement as they come into contact with the projectile.  
         [0024]    The discovery that loosely connected plies of material react much better in absorbing ballistic impact forces was unexpected and contrary to conventional thinking. While not wishing to be bound by theory, it is believed that loosely stitched layers react similar to someone hitting a ball into a pillow. Each layer is independently deformed in the direction of the impact force and progressively diminishes the energy of the projectile. Since the ballistic resistant panels of present invention absorb the energy of a fired projectile much better than the tightly stitched prior art panels, fewer plies of ballistic resistant material can be used to achieve the same level of protection. This makes the panels much lighter in weight and less expensive to manufacture.  
         [0025]    [0025]FIG. 1 is a cross-sectional view of a first embodiment of the ballistic resistant panel of this invention which meets NIJ Standard-0101.04 for a Type IIIA ballistic threat. The panel  10  is constructed of three layers. The first layer  12 , the second layer  14  and the third layer  16  each contain of four plies of a woven lyotropic liquid crystal polymer fibrous material. The four plies of the first  12  and the third  16  layers are loosely stitched together in a square pattern within the respective layer. The four plies of the second layer  14  are loosely stitched together in a crossed-diagonal pattern.  
         [0026]    Referring to FIG. 4, the square stitching pattern of the first and third layers  12 ,  16  is shown with stitches  32  running in lines perpendicular and parallel to each other. The stitches  32  are positioned to reduce the amount of backface when placed against the body of a wearer. Backface is defined as the amount of blunt trauma the body of a wearer would feel when a fired projectile hits the panel. The stitches  32  are preferably a one-inch diamond stitch, 3½ stitches per inch, and sewn through the four plies of each of the first  12  and third  16  layers of panel  10 . Preferably, the stitches  32  are comprised of aramid threads. In FIG. 5 there is shown the crossed-diagonal stitching pattern of the second layer  14 . The stitches  34  run in diagonal lines from corner to corner, crossing in the center of the layer. The stitches  34  are preferably a one-inch diamond stitch, 3½ stitches per inch, and sewn through the four plies of the second layer  14 . Again, the stitching is preferably comprised of aramid threads. The three layers of panel  10  are fastened at the periphery of the panel to hold the layers together while still preserving independent movement. Preferably, the layers are stitched together at the corners of the panel.  
         [0027]    As shown in FIG. 6, the weave  36  for the first  12  and third  16  layers of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of 11 by 28 fibers per inch. There are twenty-eight horizontal warp fibers  36 A and eleven vertical fill fibers  36 B per inch for each ply of woven lyotropic liquid crystal polymer fibrous material. Referring FIG. 9, the weave  48  for the second layer  14  of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of  30  by  30  fibers per inch. There are thirty horizontal warp fibers  48 A and thirty vertical fill fibers  48  per inch for each ply of woven lyotropic liquid crystal polymer fibrous material.  
         [0028]    Preferably, panel  10  has a thickness of about 0.15 inches and an areal density of not more than about 0.84 pounds per square foot (PSF) while providing protection from a Type IIIA ballistic threat. A test panel was constructed according to this first embodiment and tested for compliance with NIJ Standard-0101.04 for a Type IIIA ballistic threat. According to the NIJ Standard, a Type IIIA body armor will protect against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less, and 44 Magnum Jacketed Hollow Point (JHP) bullets, with nominal masses of 15.6 g (240 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less. It also provides protection against threat level Types I, IIA and II as defined in the NIJ Standard. The test data for the panel are presented in Table 1 below.  
                                                                                   TABLE 1                           TYPE IIIA Ballistic Panel                        0-30       Bullet   Ve-   Pen-       Sam-   Sample   Wet   deg.       Wt. (gr)   locity   etration       ple   Weight   Dry   Angle   Caliber   &amp; type   (Fps)   BFS (mm)                    1-1   4.25   Wet   0   44 Mag   240 SJHP   1431   36       1-2   4.25   Wet   30   44 Mag   240 SJHP   1429   38       1-3   4.25   Wet   0   44 Mag   240 SJHP   1438   36       1-4   4.25   Wet   30   44 Mag   240 SJHP   1432   37       1-5   4.25   Wet   0   44 Mag   240 SJHP   1445   37       1-6   4.25   Wet   30   44 Mag   240 SJHP   1420   39       1-7   4.25   Wet   0   44 Mag   240 SJHP   1445   29       1-8   4.25   Wet   30   44 Mag   240 SJHP   1428   29                  
 
         [0029]    A second embodiment of the present invention for NIJ Standard-0101.04 Type II ballistic threats is shown in cross-section in FIG. 2. The first layer  20  and the third layer  24  of panel  18  are constructed of multiple plies of woven lyotropic liquid crystal polymer fibrous material with the second layer  22  constructed of at least one ply of woven lyotropic liquid crystal polymer fibrous material. Preferably, the first layer  20  and the third layer  24  each have three plies of woven lyotropic liquid crystal polymer fibrous material. The second layer  22  preferably consists of four plies of woven lyotropic liquid crystal polymer fibrous material. The three plies of the first  20  and third  24  layers of panel  18  are loosely stitched together within their respective layers using the square pattern shown in FIG. 4. The four plies of the second layer  22  are loosely stitched together in the crossed-diagonal pattern shown in FIG. 5. The loose stitching is preferably a one-inch diamond stitch at 3½ stitches per inch and comprised of aramid threads. The three layers are held together with stitches sewn through the layers at the corners of panel  18 .  
         [0030]    As shown in FIG. 7, the weave  38  for the first and third layers of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of 11 by 28 fibers per inch. There are twenty-eight horizontal warp fibers  38 A and eleven vertical fill fibers  38 B per inch for each ply of woven lyotropic liquid crystal polymer fibrous material. As shown in FIG. 10, the weave  50  for the second layer of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of 30 by 30 fibers per inch. There are thirty horizontal warp fibers  50 A and thirty vertical fill fibers  50 B per inch for each ply of woven lyotropic liquid crystal polymer fibrous material.  
         [0031]    Preferably, panel  18  has a thickness of about 0.13 inches and an areal density of not more than about 0.66 PSF while providing effective protection for a Type II ballistic threat. According to NIJ Standard-0101.04, Type II body armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 358 m/s (1175 ft/s) or less, and 357 Magnum Jacketed Soft Point (JSP) bullets, with nominal masses of 10.2 g (158 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less. It also provides protection against Type I and IIA ballistic threats. Test data for a panel constructed according to the second embodiment are shown in Table 2 below.  
                                                                                   TABLE 2                           TYPE II Ballistic Panel                        0-30       Bullet   Ve-   Pen-       Sam-   Sample   Wet   deg.       Wt. (gr)   locity   etration       ple   Weight   Dry   Angle   Caliber   &amp; type   (Fps)   BFS (mm)                    2-1   3.67   Wet   0   357 Mag   158 JSP   1439   28       2-2   3.67   Wet   30   357 Mag   158 JSP   1439   28       2-3   3.67   Wet   0   357 Mag   158 JSP   1459   29       2-4   3.67   Wet   30   357 Mag   158 JSP   1451   30       2-5   3.67   Wet   0   357 Mag   158 JSP   1438   42       2-6   3.67   Wet   30   357 Mag   158 JSP   1438   29       2-7   3.67   Wet   0   357 Mag   158 JSP   1464   27       2-8   3.67   Wet   30   357 Mag   158 JSP   1462   30                  
 
         [0032]    A third embodiment of the present invention for NIJ Standard-0101.04 Type IIA ballistic threats is shown in cross-section in FIG. 3. The first layer  44  of panel  42  is constructed of multiple plies of woven lyotropic liquid crystal polymer fibrous material with the second layer  46  constructed of at least one ply of woven lyotropic liquid crystal polymer fibrous material. Preferably, the first  44  and second  46  layers are comprised of four plies each of woven lyotropic liquid crystal polymer fibrous material. The plies of the first layer  44  are loosely stitched together in a square pattern as shown in FIG. 4. The plies of the second layer  46  are loosely stitched together in a crossed-diagonal pattern as shown in FIG. 5. The stitches are preferably a one-inch diamond stitch at 3½ stitches per inch and comprised of aramid threads.  
         [0033]    As shown in FIG. 8, the weave  40  for the first layer  44  of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of 11 by 28 fibers per inch. There are twenty-eight horizontal warp fibers  40 A and eleven vertical fill fibers  40 B per inch. As shown in FIG. 11, the weave  52  for the second layer  46  of woven lyotropic liquid crystal polymer fibrous material has a warp to fill ratio of 30 by 30 fibers per inch. There are thirty horizontal warp fibers  52 A and thirty vertical fill fibers  52 B per inch.  
         [0034]    Preferably, panel  42  has a thickness of about 0.10 inches and an areal density of not more than about 0.51 PSF while providing effective protection against Type IIA ballistic threats. According to NIJ Standard-0101.04, Type ITA body armor will protect against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 332 m/s (1090 ft/s) or less, and 40 S&amp;W caliber Full Metal Jacketed (FMJ) bullets, with nominal masses of 11.7 g (180 gr) impacting at a minimum velocity of 312 m/s (1025 ft/s) or less. It also provides protection Type I ballistic threats. Test data for a panel constructed in accordance with the third embodiment is presented in Table 3 below.  
                                                                                   TABLE 3                           TYPE IIA Ballistic Panel                                        Pen-                   0-30       Bullet   Ve-   etration       Sam-   Sample   Wet   deg.       Wt. (gr)   locity   BFS       ple   Weight   Dry   Angle   Caliber   &amp; type   (Fps)   (mm)                    3-1   3.00   Wet   0   40 S&amp;W   180 FMJ   1054   27       3-2   3.00   Wet   30   40 S&amp;W   180 FMJ   1050   26       3-3   3.00   Wet   0   40 S&amp;W   180 FMJ   1051   27       3-4   3.00   Wet   30   40 S&amp;W   180 FMJ   1057   25       3-5   3.00   Wet   0   40 S&amp;W   180 FMJ   1048   27       3-6   3.00   Wet   30   40 S&amp;W   180 FMJ   1047   27       3-7   3.00   Wet   0   40 S&amp;W   180 FMJ   1052   25       3-8   3.00   Wet   30   40 S&amp;W   180 FMJ   1046   28                  
 
         [0035]    While there have been provided several embodiments of the invention, there are many other variations of the invention which may be made without departing from the scope of the invention as set forth in the appended claims.