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] 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 36A and eleven vertical fill fibers 36B 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 48A 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. 1

[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 38A and eleven vertical fill fibers 38B 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 50A and thirty vertical fill fibers 50B 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. 2

[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 40A and eleven vertical fill fibers 40B 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 52A and thirty vertical fill fibers 52B 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&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. 3

[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.