Impact resistant underbody shield materials and articles and methods of using them

Abstract

Underbody shield materials that can provide an underbody shield with high impact resistance are described. In some configurations, an underbody shield composition comprises a porous core layer comprising a plurality of reinforcing fibers, a lofting agent and a thermoplastic material. In some instances, the underbody shield composition may also comprise a film such that an underbody shield produced from the composition can withstand at least 50 individual impacts as tested using a SAE J400 protocol.

1 . An underbody shield composition comprising:
 a thermoplastic core layer comprising a web of open celled structures defined by random crossing over of reinforcing fibers held together by a thermoplastic polymer, the thermoplastic core layer further comprising a lofting agent effective to increase a thickness of the core layer upon exposure to heat to provide a post lofted core layer;   a film disposed on a first surface of the core layer,   
       in which the post lofted core layer and film together provide an underbody shield article that can withstand at least 50 individual impacts according to a SAE J400 protocol without damage to the film. 
     
     
         2 . The underbody shield composition of  claim 1 , in which the film is a homopolymer or copolymer film. 
     
     
         3 . The underbody shield composition of  claim 2 , in which the homopolymer is a polyolefin. 
     
     
         4 . The underbody shield composition of  claim 1 , in which the thermoplastic polymer is present at 50 weight percent or more in the core layer. 
     
     
         5 . The underbody shield composition of  claim 4 , in which the film is at least 10 mils thick. 
     
     
         6 . The underbody shield composition of  claim 5 , in which the lofting agent is present at 4 percent by weight or more in the core layer. 
     
     
         7 . The underbody shield composition of  claim 6 , in which the reinforcing fibers are selected from the group consisting of glass fibers, carbon fibers, graphite fibers, synthetic organic fibers, inorganic fibers, natural fibers, mineral fibers, metal fibers, metalized inorganic fibers, metalized synthetic fibers, ceramic fibers, and combinations thereof. 
     
     
         8 . The underbody shield composition of  claim 7 , in which the thermoplastic polymer is a polymer resin that is selected from the group consisting of a polyolefin resin, a thermoplastic polyolefin blend resin, a polyvinyl polymer resin, a butadiene polymer resin, an acrylic polymer resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyestercarbonate resin, a polystyrene resin, an acrylonitrylstyrene polymer resin, an acrylonitrile-butylacrylate-styrene polymer resin, a polyether imide resin, a polyphenylene ether resin, a polyphenylene oxide resin, a polyphenylenesulphide resin, a polyether resin, a polyetherketone resin, a polyacetal resin, a polyurethane resin, a polybenzimidazole resin, and copolymers and mixtures thereof. 
     
     
         9 . The underbody shield composition of  claim 1 , in which the thermoplastic core layer comprises polypropylene, glass fibers and microsphere lofting agents, and in which the film is a polypropylene homopolymer film. 
     
     
         10 . The underbody shield composition of  claim 9 , in which the film is directly disposed on the first surface of the core layer without any intervening layer or material. 
     
     
         11 . The underbody shield composition of  claim 1 , further comprising a scrim disposed on a second surface of the core layer opposite the first surface of the core layer. 
     
     
         12 . The underbody shield composition of  claim 11 , in which the scrim comprises glass fibers, aramid fibers, graphite fibers, carbon fibers, inorganic mineral fibers, metal fibers, metalized synthetic fibers, and metalized inorganic fibers. 
     
     
         13 . The underbody shield composition of  claim 11 , further comprising an additional skin layer disposed on the scrim. 
     
     
         14 . The underbody shield composition of  claim 11 , in which the thermoplastic core layer comprises polypropylene, glass fibers and microsphere lofting agents, in which the film is a polypropylene homopolymer film and the scrim is polyester nonwoven scrim. 
     
     
         15 . The underbody shield composition of  claim 14 , in which the film is directly disposed on the first surface of the core layer without any intervening layer or material and the scrim is directly disposed on the second surface of the core layer without any intervening layer or material. 
     
     
         16 . The underbody shield composition of  claim 11 , in which the scrim is disposed as one or more strips on the second surface of the core layer. 
     
     
         17 . The underbody shield composition of  claim 1 , further comprising an additional core layer coupled to the core layer, the additional core layer comprising a web of open celled structures defined by random crossing over of reinforcing fibers held together by a thermoplastic polymer. 
     
     
         18 . The underbody shield composition of  claim 17 , in which the additional core layer further comprises a lofting agent effective to increase a thickness of the additional core layer. 
     
     
         19 . The underbody shield composition of  claim 17 , in which the additional core layer comprises a lower weight percentage of thermoplastic material than an amount of thermoplastic material present in the core layer. 
     
     
         20 . The underbody shield composition of  claim 1 , in which the film is configured to withstand more impacts as a thickness of the core layer is decreased. 
     
     
         21 - 110 . (canceled)