Rigid structure UHMWPE UD and composite and the process of making
View Patent ↗Fabrication of ballistic resistant fibrous composites having improved ballistic resistance properties. More particularly, ballistic resistant fibrous composites having enhanced flexural properties, which correlates to low composite backface signature. The composites are useful for the production of hard armor articles, including helmet armor.
1. A fibrous composite comprising a plurality of adjoined fiber layers, each fiber layer comprising fibers having surfaces that are at least partially covered with a polymeric material, wherein said fibers are predominantly free of a fiber surface finish such that said polymeric material is predominantly in direct contact with the fiber surfaces; said fibrous composite having a stress at yield that is greater than the stress at yield of a comparable fibrous composite having fiber surfaces that are predominantly covered with a fiber surface finish wherein such a fiber surface finish is between the fiber surfaces and the polymeric material.
2. The fibrous composite of claim 1 , wherein the composite has a stress at yield of at least 7.50 ksi (˜51.71 MPa) as measured by ASTM D790 for a composite having an areal density of about 1.5 lb/ft 2 (7.32 kg/m 2 ) or less.
3. The fibrous composite of claim 1 wherein said composite has a stress at yield of at least about 9.0 ksi (˜62.05 MPa) as measured by ASTM D790 for a composite having an areal density of about 1.5 lb/ft 2 (7.32 kg/m 2 ) or less.
4. The fibrous composite of claim 2 wherein said composite comprises polyethylene fibers.
5. The fibrous composite of claim 4 wherein said polymeric material comprises at least one thermoplastic polymer, and wherein said composite comprises fibers having a tenacity of 20 g/denier or more.
6. The fibrous composite of claim 2 wherein said composite comprises a consolidated plurality of cross-plied, non-woven, unidirectional fiber plies, wherein said polymeric material comprises at least one thermoplastic polymeric binder, and wherein each fiber layer of the composite is impregnated with said thermoplastic polymeric binder.
7. The fibrous composite of claim 2 which composite has a V 50 value of at least about 1750 feet/sec (fps) (533.40 m/s) against a 9 mm projectile in accordance with Department of Defense Test Method Standard MIL-STD-662F.
8. The fibrous composite of claim 3 which composite has a V 50 value of at least about 1900 feet/sec (fps) (579.12 m/s) against a 9 mm projectile in accordance with Department of Defense Test Method Standard MIL-STD-662F.
9. The fibrous composite of claim 1 wherein the fiber surfaces are substantially free of a fiber surface finish between the fiber surface and the polymeric material such that said polymeric material is substantially in direct contact with the fiber surfaces, and wherein patches of residual finish are present on the fiber surfaces between the fiber surface and the polymeric material, wherein at least 90% of the fiber surface area is not covered by the residual fiber surface finish.
10. The fibrous composite of claim 1 wherein said composite comprises fibers having a fiber areal density of about 1.7 g/cm 3 or less.
11. The fibrous composite of claim 1 which composite has a V 50 value of at least about 1750 feet/sec (fps) (533.40 m/s) against a 9 mm projectile in accordance with Department of Defense Test Method Standard MIL-STD-662F.
12. The fibrous composite of claim 1 wherein said composite has a backface signature of less than about 8 mm when impacted with a 124-grain, 9 mm FMJ RN projectile fired at a velocity of from about 427 m/s to about 445 m/s (1430 feet/second (fps)±30 fps), wherein backface signature is measured for a composite having an areal density of 2.0 psf.
13. The fibrous composite of claim 12 wherein said composite has a composite areal density of from about 3,750 g/m 2 (0.75 psf) to about 12,500 g/m 2 (2.50 psf).
14. The fibrous composite of claim 12 which composite has a V 50 value of at least about 1750 feet/sec (fps) (533.40 m/s) against a 9 mm projectile in accordance with Department of Defense Test Method Standard MIL-STD-662F.
15. The fibrous composite of claim 12 wherein the fiber surfaces are substantially free of a fiber surface finish between the fiber surface and the polymeric material such that said polymeric material is substantially in direct contact with the fiber surfaces, and wherein patches of residual finish are present on the fiber surfaces between the fiber surface and the polymeric material, wherein at least 90% of the fiber surface area is not covered by the residual fiber surface finish.
16. The fibrous composite of claim 12 wherein said composite comprises polyethylene fibers.
17. A composite comprising a consolidated plurality of fiber layers, each of said fiber layers comprising a plurality of fibers having a tenacity of about 7 g/denier or more and a tensile modulus of about 150 g/denier or more, wherein each fiber layer is at least partially impregnated with a polymeric binder material, the polymeric binder material substantially coating the fibers, and said polymeric binder material comprising from about 7% to about 20% by weight of each fiber layer; said panel having a stress at yield of at least 7.50 ksi (˜51.71 MPa) as measured by ASTM D790, a composite areal density of about 1.5 lb/ft 2 (7.32 kg/m 2 ) or less and a V 50 value of at least about 1750 feet/sec (fps) (533.40 m/s) against a 9 mm projectile in accordance with Department of Defense Test Method Standard MIL-STD-662F.