Composite panels

Abstract

A composite panel consisting of outer skins and an inner core consisting of a foamed polymer, wherein the structure or properties of the inner core are anisotropic. The composite panel can be made by applying external heat and pressure to melt a skin of thermoplastic composite and an initial thickness of a thermoplastic core which has anisotropic properties causing the skin and core to fuse together followed by cooling the fused structure. The composite panel can be made by applying external heat and pressure to melt layers of a thermoplastic adhesive positioned between the outer skins and an inner core consisting of a foamed polymer, wherein the structure or properties of the inner core are anisotropic, so that the skins are bonded to the core by the melted layers of the thermoplastic adhesive followed by cooling the bonded structure.

1 . A sandwich panel, comprising: outer skins of a rigid material and an inner core comprising a foamed polymer, wherein the cells of the foamed polymer are anisotropic in structure. 
   
   
       2 . The sandwich panel of  claim 1 , wherein the outer skins comprise a rigid sheet material selected from the group consisting of a composite sheet material incorporating reinforcing fibers and a matrix of thermoset or thermoplastic resin, an extruded thermoplastic sheet, a co-extruded thermoplastic sheet, a sheet of wood, a sheet of fiberboard, a sheet of chipboard, a sheet of plywood, a sheet of laminated veneer lumber, a sheet of metal and a sheet of glass. 
   
   
       3 . The sandwich panel of  claim 1 , wherein the cells of the foamed polymer core comprise elongated or ovaloid bubbles oriented perpendicularly to the faces of the panel. 
   
   
       4 . The sandwich panel of  claim 1 , wherein the density of the foamed polymer core decreases toward the center of the core. 
   
   
       5 . The sandwich panel of  claim 1 , wherein the foamed polymer core contains geometric shapes of denser material oriented perpendicularly to the faces of the panel. 
   
   
       6 . The sandwich panel of  claim 1  in which the core and skins are bonded together by an intermediate layer of thermoplastic material which is compatible with both the skins and the core materials. 
   
   
       7 . The sandwich panel of  claim 1 , wherein the material of the foamed polymer core is selected from the group consisting of polystyrene, high impact polystyrene, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, polyvinylchloride, polyethylene-teraphthalate, polyethylene and polypropylene. 
   
   
       8 . The sandwich panel of  claim 1  where the core is manufactured by extrusion. 
   
   
       9 . The sandwich panel of  claim 2  where the rigid sheet material of the outer skins is a composite which has a thermoplastic matrix and is manufactured by a process selected from the group consisting of pultrusion, the consolidation of woven or aligned thermoplastic composite tapes and the consolidation of co-mingled fibers. 
   
   
       10 . The sandwich panel of  claim 2  where the rigid sheet material of the outer skin is a composite which has a thermoset matrix and is manufactured by a process selected from the group of pultrusion and a belt press process. 
   
   
       11 . The sandwich panel of  claim 1  encapsulated with a layer of thermoplastic polymer. 
   
   
       12 . A truck box, a deck plank, a scaffolding plank, a table, an article of furniture, a desktop, a concrete formwork panel, a boat hull, a blast panel a building structure, a sunroof, a headliner, a door panel, a parcel shelf, a load floor, a visor, a seat component, or an automobile part comprising the sandwich panel of  claim 1 . 
   
   
       13 . A process for the manufacture of the sandwich panel of  claim 1  comprising the step of bonding the skins to the core 
   
   
       14 . The process of  claim 13  where the bonding is achieved using a thermoplastic adhesive layer. 
   
   
       15 . The process of  claim 14  where the bonding is achieved using a thermoset adhesive layer. 
   
   
       16 . A process for the manufacture of the sandwich panel of  claim 1  comprising the steps of: (a) applying external heat and pressure to melt layers of a thermoplastic adhesive positioned between the outer skins of a composite material comprising fibers in a polymer matrix and an inner core comprising the foamed polymer so that the skins are bonded to the core by the melted layers of the thermoplastic adhesive; and (b) cooling the bonded structure. 
   
   
       17 . The process of  claim 13 , further comprising the step of overextruding an outer layer of thermoplastic around the sandwich panel.