Ballistic laminate structure, and method for manufacturing a ballistic laminate structure
A ballistic laminate structure in sheet form includes first and second pre-annealed nonwoven fabric layers. Each fabric layer is constructed of a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers. The layers are joined together at an angle to form a dimensionally stable cross-plied fabric.
1. A ballistic laminate structure in sheet form, comprising:
a first pre-annealed fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers;
a second pre-annealed fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers; and
means for joining said first and second pre-annealed fabric layers together at an angle to form a dimensionally stable cross-plied fabric.
2. A ballistic laminate structure according to claim 1 , wherein said first pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer in a machine direction.
3. A ballistic laminate structure according to claim 2 , wherein said first pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer at least 1.5% in a machine direction.
4. A ballistic laminate structure according to claim 1 , wherein said second pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer in a machine direction.
5. A ballistic laminate structure according to claim 4 , wherein said second pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer at least 1.5% in a machine direction.
6. A ballistic laminate structure according to claim 1 , and comprising a thermoplastic layer residing outside of at least one of said first and second pre-annealed fabric layers.
7. A ballistic laminate structure according to claim 1 , and comprising a thermoplastic layer residing between said first and second pre-annealed fabric layers.
8. A ballistic laminate structure according to claim 1 , and comprising a thermoplastic layer residing adjacent at least one of said first and second pre-annealed fabric layers, said thermoplastic layer comprising a nonwoven fibrous heat-activated resin selected from a group consisting of polyethylene and ethylene-vinyl-acetate.
9. A ballistic laminate structure according to claim 1 , wherein said first pre-annealed fabric layer is cross-plied at an angle of 90 degrees to said second pre-annealed fabric layer.
10. A ballistic laminate structure according to claim 1 , wherein a percentage by weight of the high performance fibers in said ballistic laminate structure is at least 80 percent of a total weight of said ballistic laminate structure.
11. A ballistic laminate structure according to claim 1 , wherein the fibers of said first and second pre-annealed fabric layers are chosen from a group consisting of aramid fiber, polyolefin, vinylon, and liquid crystal polymer-based fiber.
12. A ballistic laminate structure according to claim 1 , wherein the fibers of said first and second pre-annealed fabric layers are chosen from a group consisting of extended chain ultra-high molecular weight polyethylene (UHMWPE), poly{p-phenylene-2,6-benzobisoxazole} (PBO), and poly{diimidazo pyridinylene(dihydroxy)phenylene} (M5).
13. A ballistic article comprising a stacked assembly of ballistic laminate structures, each ballistic laminate structure comprising:
a first pre-annealed fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers;
a second pre-annealed fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers; and
means for joining said first and second pre-annealed fabric layers together at an angle to form a dimensionally stable cross-plied fabric.
14. A ballistic article according to claim 13 , wherein said ballistic article comprises a small arms protective insert (SAPI).
15. A ballistic article according to claim 14 , wherein said small arms protective insert comprises a ceramic facing.
16. A ballistic laminate structure according to claim 13 , wherein said first pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer in a machine direction.
17. A ballistic laminate structure according to claim 13 , wherein said second pre-annealed fabric layer comprises high performance fibers annealed at a temperature sufficient to shrink said fabric layer in a machine direction.
18. A method for manufacturing a ballistic laminate structure in sheet form, said method comprising:
pre-annealing a first fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers;
pre-annealing a second fabric layer comprising a loosely assembled array of unidirectionally-oriented, untwisted, high performance fibers; and
after pre-annealing the first and second fabric layers, joining the first and second fabric layers at an angle to form a dimensionally stable cross-plied fabric.
19. A method according to claim 18 , wherein pre-annealing the first fabric layer comprises heating the fibers at a temperature sufficient to shrink the fabric layer in a machine direction.
20. A method according to claim 18 , wherein pre-annealing the second fabric layer comprises heating the fibers at a temperature sufficient to shrink the fabric layer in a machine direction.