Ballistic resistant composite material

Abstract

The present disclosure relates to a ballistic resistant composite 20 including a bimodal binder, the composite formable in a manner in which it is exposed to low pressure for a short duration of time and at a controlled temperature. More particularly, the bimodal binder of composite 20 allows the composite to be formed with a flat-bed laminator, for example, which may be less expensive than other processing methods, such as a steel belt press.

What is claimed is: 
     
         1 . A ballistic resistant composite comprising:
 a plurality of fibers; and   a bimodal binder applied to the plurality of fibers, the binder having a crystalline component with a melting temperature and an amorphous component with a softening temperature, the crystalline component and the amorphous component having at least one of the following properties relative to one another:
 (1) the melting temperature of the crystalline component is less than the softening temperature of the amorphous component; 
 (2) at a temperature above the melting temperature of the crystalline component, a viscosity of the crystalline component is less than a viscosity of the amorphous component; and 
 (3) at a temperature above the melting temperature of the crystalline component, a surface energy of the crystalline component is less than a surface energy of the amorphous component. 
   
     
     
         2 . The ballistic resistant composite of  claim 1  wherein the melting temperature of the crystalline component is less than the softening temperature of the amorphous component. 
     
     
         3 . The ballistic resistant composite of  claim 1  wherein at a temperature above the melting temperature of the crystalline component, a viscosity of the crystalline component is less than a viscosity of the amorphous component 
     
     
         4 . The ballistic resistant composite of  claim 1  wherein at a temperature above the melting temperature of the crystalline component, a surface energy of the crystalline component is less than a surface energy of the amorphous component. 
     
     
         5 . The ballistic resistant composite of  claim 1 , wherein the crystalline component is a wax material selected from the group consisting of carnauba wax, stearamide wax, polyethylene wax, paraffin wax, polyolefin wax, and microcrystalline wax. 
     
     
         6 . The ballistic resistant composite of  claim 1 , wherein the amorphous component is comprised of at least one of a polymeric material selected from the group consisting of acrylic, polyurethane, nitrile rubber, acrylonitrile butadiene copolymer, and fluorocarbon. 
     
     
         7 . The ballistic resistant composite of  claim 1 , wherein the plurality of fibers defines at least a first fiber ply and a second fiber ply, wherein the fibers of the second fiber ply are oriented at an angle of about 90 degrees relative to the fibers of the first fiber ply. 
     
     
         8 . The ballistic resistant composite of  claim 1 , wherein the amorphous component comprises from 60 to 95 wt. % of the bimodal binder and the crystalline component comprises from 5 to 40 wt. % of the bimodal binder. 
     
     
         9 . The ballistic resistant composite of  claim 1 , wherein the melting temperature of the crystalline component is from 50° C. to 140° C. 
     
     
         10 . The ballistic resistant composite of  claim 1 , wherein the ballistic resistant composite experiences a pressure at a temperature above the melting temperature of the crystalline component for about 0.02 seconds to about 5 seconds. 
     
     
         11 . A method of forming a ballistic resistant composite comprising:
 providing a first fiber ply comprising a plurality of unidirectionally oriented first fibers, wherein said first fibers are coated with a first bimodal binder that comprises an amorphous component and a crystalline component;   providing a second fiber ply comprising a plurality of unidirectionally oriented second fibers, wherein said second fibers are coated with a second bimodal binder that comprises an amorphous component and a crystalline component;   positioning the first fiber ply and second fiber ply in a stacked arrangement, heating the first fiber ply and the second fiber ply to a temperature within a melting temperature range of the crystalline component;   applying a pressure of less than one bar to the first fiber ply and to the second fiber ply when said plies are at a temperature within the melting temperature range of the crystalline component, whereby the first fiber ply and second fiber ply are attached to each other and thereby form a ballistic resistant composite; and   cooling the first fiber ply and the second fiber ply.   
     
     
         12 . The method of  claim 11 , wherein the step of applying pressure to the first fiber ply and to the second fiber ply is conducted using a flat-bed laminator. 
     
     
         13 . The method of  claim 11 , wherein the step of applying pressure to the first fiber ply and to the second fiber ply includes applying a first pressure of less than 0.5 psi to the stacked plies during said heating step and applying a second pressure of from 10 psi to 300 psi to the stacked plies when the plies are at the temperature within the melting point range of the crystalline component. 
     
     
         14 . The method of  claim 11 , wherein said cooling step occurs for a time duration between about 0.025 seconds and about 3.0 minutes. 
     
     
         15 . The method of  claim 11 , wherein said heating step occurs for a time duration between about 0.025 seconds and about 3.0 minutes. 
     
     
         16 . The method of  claim 11 , wherein the amorphous component comprises an acrylic polymer, polyurethane, nitrile rubber, an acrylonitrile butadiene copolymer, a fluorocarbon polymer or a combination thereof. 
     
     
         17 . The method of  claim 11 , wherein the crystalline component comprises carnauba wax, stearamide wax, polyethylene wax, paraffin wax, polyolefin wax, microcrystalline wax or a combination thereof. 
     
     
         18 . The method of  claim 11 , wherein the melting temperature of the crystalline component is less than about 140° C. 
     
     
         19 . The method of  claim 11 , wherein said step of applying a pressure occurs for a time duration between about 0.02 seconds and about 5 seconds while the plies are at the temperature within the melting point range of the crystalline component. 
     
     
         20 . A method of forming a ballistic resistant composite comprising:
 providing a first plurality of fibers in a unidirectional orientation;   providing a second plurality of fibers in a unidirectional orientation;   providing a binder having an amorphous component and a crystalline component;   coating the first plurality of fibers with the binder;   coating the second plurality of fibers with the binder;   positioning the first plurality of fibers at a 90 degree angle to the second plurality of fibers;   heating the first and second pluralities of fibers to a temperature within a melting temperature range of the crystalline component;   applying a pressure of less than one bar to the first and second pluralities of fibers when at a temperature within the melting point range of the crystalline component; and   cooling the first and second pluralities of fibers.