Multilayered polyethylene material and ballistic resistant articles manufactured therefrom
The present invention relates to polyethylene material that has a plurality of unidirectionally oriented polyethylene monolayers cross-plied and compressed at an angle to one another, each polyethylene monolayer composed of ultra high molecular weight polyethylene and essentially devoid of resins. The present invention further relates to ballistic resistant articles that include or incorporate the inventive polyethylene material and to methods of preparing the material and articles incorporating same.
1. A multilayered material comprising a plurality of unidirectional monolayers, said monolayers comprising polyethylene with the direction of each unidirectional monolayer being positioned at an angle with respect to the direction of an adjacent unidirectional monolayer, and wherein the polyethylene in each of the unidirectional monolayers is in the form of unidirectionally drawn film strips, wherein each strip in each monolayer is partially overlapped and aligned in the same direction in one plane with adjacent film strips in the monolayer, wherein the partially overlapped adjacent film strips in each monolayer are compression-laminated to one another, and wherein the film strips are elongated bodies having a length, a width and thickness with the length and width being substantially larger than the thickness.
2. The material of claim 1 , comprising two unidirectional monolayers.
3. The material of claim 1 , wherein the direction of each unidirectional monolayer is positioned at an angle between 20 to 160 degrees to each adjacent monolayer.
4. The material of claim 1 , wherein each unidirectional monolayer has a tensile strength within the range of 8-40 cN/dTex.
5. The material of claim 1 , wherein each unidirectional monolayer has a thickness of about 30-120 μm.
6. The material of claim 1 , wherein each unidirectional monolayer has an areal density of 60 to 200 g/m 2 .
7. The material of claim 1 , wherein each unidirectional monolayer has an elongation modulus of 2-6%.
8. The material of claim 1 , wherein each unidirectional monolayer has an elastic modulus of 400 to 1,200 cN/dTex.
9. The material of claim 1 , wherein each unidirectional monolayer has a maximal displacement of 2-12 mm per 200 mm.
10. An article comprising the material of claim 1 in combination with an additional material selected from the group consisting of: ceramic, steel, aluminum, titanium, glass and graphite.
11. A ballistic resistant article comprising the multilayer material of claim 1 .
12. The ballistic resistant article of claim 11 , having between 70 to 280 unidirectional monolayers, each optionally containing an additional material selected from the group consisting of: ceramic, steel, aluminum, titanium, glass and graphite.
13. A fabric envelope containing the ballistic resistant article of claim 11 .
14. A supporting structure for being worn on a body part containing the ballistic resistant article of claim 11 .
15. The supporting structure of claim 14 in the form of a body garment.
16. The material of claim 1 , wherein the polyethylene is ultra high molecular weight polyethylene (UHMWPE).
17. The material of claim 1 , wherein the unidirectional monolayers consist essentially of ultra high molecular weight polyethylene (UHMWPE) and are essentially devoid of bonding matrices.
18. The material of claim 1 , comprising two monolayers which are compressed to one another.
19. The material of claim 1 , wherein the material is essentially devoid of bonding matrices.