Rigid structural and low back face signature ballistic UD/articles and method of making
View Patent ↗Fabrication of ballistic resistant fibrous composites having improved ballistic resistance properties. More particularly, ballistic resistant fibrous composites having enhanced a dynamic storage modulus, which correlates to low composite backface signature.
1. A method of forming a fibrous composite comprising at least two 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 composite having a dynamic storage modulus of at least 8.0×10 9 dyn/cm 2 as measured at 25° C. (77° F.), the method comprising:
a) providing a plurality of polymeric fibers having surfaces that are predominantly free of a fiber surface finish;
b) optionally treating the fiber surfaces to enhance adsorbability, bonding or adhesion of a subsequently applied polymeric material to the fiber surfaces;
c) after step b), applying a polymeric material onto at least a portion of said fibers, thereby adsorbing, bonding or adhering the polymeric material on or to the fiber surfaces;
d) after step c), producing a plurality of fiber plies from said fibers either before or after applying said polymeric material to said fibers; and
e) after step d), consolidating said plurality of fiber plies to produce a fibrous composite.
2. The method of claim 1 wherein said optional step of treating the fiber surfaces to enhance the surface adsorbability, bonding or adhesion of a subsequently applied polymeric material to the fiber surfaces is conducted.
3. The method of claim 1 wherein step b) is conducted and wherein said treating comprises a plasma treatment or a corona treatment.
4. The method of claim 1 wherein said fibers as provided in step a) are washed to at least partially remove a fiber surface finish prior to step a).
5. The method of claim 4 wherein said pre-existing fiber surface finish is removed by washing the fibers with water.
6. The method of claim 1 wherein patches of residual fiber surface finish are present on the fiber surfaces between the fiber surfaces and the polymeric material, wherein at least 90% of the fiber surfaces of each fiber are not covered by the residual fiber surface finish.
7. The method of claim 1 wherein at least one of said fiber layers is formed by weaving a plurality of said fibers into a woven fabric.
8. The method of claim 1 wherein at least one of said fiber layers is formed by arranging a plurality of said fibers into a non-woven fabric.
9. A method of forming a fibrous composite comprising at least two 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; the method comprising:
a) providing a plurality of polymeric fibers having surfaces that are predominantly free of a fiber surface finish;
b) optionally treating the fiber surfaces to enhance adsorbability, bonding or adhesion of a subsequently applied polymeric material to the fiber surfaces;
c) after step b), applying a polymeric material onto at least a portion of said fibers, thereby adsorbing, bonding or adhering the polymeric material on or to the fiber surfaces;
d) after step c), producing a plurality of fiber plies from said fibers either before or after applying said polymeric material to said fibers; and
e) after step d), consolidating said plurality of fiber plies to produce a fibrous composite, said fibrous composite having a dynamic storage modulus that is greater than the dynamic storage modulus 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.
10. The method of claim 9 wherein said optional step of treating the fiber surfaces to enhance the bonding and/or adhesion of a subsequently applied material to the fiber surfaces is conducted.
11. The method of claim 10 wherein step b) is conducted and wherein said treating comprises a plasma treatment or a corona treatment.
12. The method of claim 9 wherein said fibers comprise polyethylene fibers having a tenacity of 20 g/denier or more.
13. The method of claim 9 wherein at least one of said fiber layers is formed by weaving a plurality of said fibers into a woven fabric.
14. The method of claim 9 wherein at least one of said fiber layers is formed by arranging a plurality of said fibers into a non-woven fabric.