Energy absorbent laminate

Abstract

This invention provides multi-layered composites, laminates and composite joints in which at least one resin-impregnated, fiber-containing layer is joined or laminated to a core layer having a lower flexural modulus or higher elongation at break, higher toughness, or a combination of all or some of these properties. The multi-layer composite produced by laminating or joining these materials together has improved shearout, impact and cutting resistance, since stresses caused by outside forces can be more widely distributed throughout the composite.

1 - 11 . (canceled)  
     
     
         12 . An energy absorbent laminate comprising: 
 (a) a pair of composite layers containing a resin-impregnated glass fabric or mat having a first toughness;    (b) a core layer laminated between said pair of composite layers having a second toughness which is greater than said first toughness, said core layer having a greater elongation at break than said first layer;    said core layer comprising poorly wetted or weakly bonded high modulus fibers which help to at least distribute loads due to shear, cutting and impact forces exerted on said composite by at least a portion of said core layer delaminating from said pair of composite layers or by bunching during said delamination in response to said shear, cutting and impact forces.    
     
     
         13 . The composite of  claim 12  wherein said pair of composite layers comprise a woven or non-woven fabric or mat made of high tensile modulus fiber, and said core layer comprises fibers, roving, yarn, woven fabric, non-woven fabric, tow or combination thereof.  
     
     
         14 . The composite of  claim 12  wherein said core layer comprises low modulus polymeric filaments and filaments of at least one high modulus reinforcing fiber selected from the group comprising: glass fiber, carbon fiber, boron fiber, aramid fiber or a combination thereof.  
     
     
         15 - 17 . (canceled)  
     
     
         18 . A multi-layered composite laminate, comprising: 
 (a) a pair of resin-impregnated, fiber-containing layers having a first flexural modulus and a first toughness;    (b) a fiber-containing core layer having a second, lower flexural modulus than said first flexural modulus and a second higher toughness than said first toughness, said fiber-containing core layer sandwiched between said pair of resin-impregnated, fiber-containing layers to form an integral composite;    (c) at least a portion of said fiber-containing core layer configured to delaminate from said pair of resin-impregnated, fiber containing layers when subjected to shear, cutting or impact forces, or to bunch during said delamination, to provide improved shearout resistance over a composite of approximately the same thickness made entirely from said resin-impregnated, fiber-containing layers having a first flexural modulus.    
     
     
         19 . The composite of  claim 18 , wherein said pair of resin-impregnated, fiber-containing layers and said fiber-containing core layer comprise substantially similar fiber compositions, resin compositions, or both, for improved recyclability.  
     
     
         20 . A multi-layered composite having improved energy absorbing properties comprising: 
 (a) a pair of resin-impregnated, fabric layers including high strength fibers;    (b) a core layer for absorbing energy directed to said composite by externally applied forces, said core layer comprising polymeric fibers having greater toughness than said high strength fibers, said core layer laminated between said pair of resin-impregnated glass fabric layers so as to allow at least a portion of the core layer to delaminate from the resin-impregnated, fabric layers, in response to said externally applied forces, or to bunch during said delamination; said core layer laminated under heat, pressure, or both, to form an integral composite.    
     
     
         21 . The multi-layered composite of  claim 20 , wherein said core layer is only partially melted by said lamination.  
     
     
         22 . A ballistic and explosion-resistant panel, comprising: 
 (a) a pair of resin impregnated, fiber-containing layers, having a first toughness;    (b) an aramid fiber-containing core layer having a second, greater toughness than said first toughness, said core layer sandwiched between said pair of resin impregnated, fiber-containing layers and joined to said resin impregnated, fiber-containing layers using an adhesive web to allow at least a portion of the core layer to delaminate from the resin impregnated, fiber-containing layers, in response to an externally applied force;    said multi-layered composite having improved resistance to ballistic impacts.    
     
     
         23 . The panel of  claim 22  wherein said aramid fiber-containing core layer comprises a woven or knit fabric.  
     
     
         24 . The panel of  claim 22  wherein said aramid fiber-containing core layer comprises a woven or non-woven fabric having a basis weight of at least 300-6,000 g/m 2 .  
     
     
         25 . A multi-layered composite, comprising: 
 (a) a pair of resin impregnated, fiber-containing layers;    (b) a fiber-containing core layer sandwiched between said pair of resin impregnated, fiber-containing layers;    said core layer comprising poorly wetted or weakly bonded high modulus fibers such that said core layer can absorb high amounts of energy by at least a portion of said fibers delaminating from said pair of resin impregnated, fiber-containing layers, or by bunching during said delamination.    
     
     
         26 . The multi-layered composite of  claim 25 , wherein the fiber-containing core layer has a second, greater toughness than said first toughness.  
     
     
         27 . The multi-layered composite of  claim 25 , wherein the fibers of said fiber-containing core layer comprise yarn, roving, two, woven fabric, non-woven fabric, or combinations thereof.  
     
     
         28 . The multi-layered composite of  claim 25 , further comprising a polypropylene copolymer wax to substantially eliminate air voids in the laminate structure and render the composite translucent.  
     
     
         29 . The multi-layered composite of  claim 25 , wherein the pair of resin impregnated, fiber-containing layers have a first toughness, and the fiber-containing core layer has a second toughness, said first and second toughnesses being unequal.  
     
     
         30 . The multi-layered composite of  claim 29 , wherein said fiber-containing core layer comprises aramid fibers.  
     
     
         31 . The multi-layered composite of  claim 25 , wherein the fibers of said resin impregnated, fiber-containing layers have the same composition as the fibers of said fiber-containing core layer, and wherein the fibers of said fiber-containing core layer comprise a fabric having a lower basis weight as compared to that of the resin impregnated, fiber-containing layers.  
     
     
         32 . The multi-layered composite of  claim 25 , wherein the fiber-containing core layer comprises aramid fibers, the core layer joined to said resin impregnated, fiber-containing layers using adhesive webs.  
     
     
         33 . The multi-layered composite of  claim 25 , wherein the fiber-containing core layer comprises aramid fibers and is joined to said resin impregnated, fiber-containing layers by heating and pressing the layers together.  
     
     
         34 . The multi-layered composite laminate of  claim 18 , wherein said fiber-containing core layer comprises poorly wetted or weakly bonded high modulus fibers.