Foamed core composite plate for use in trailer walls and doors

Abstract

A novel composite plate is used to form a wall or a door of a vehicle, such as a trailer or van. Each composite plate used in the trailer is formed from a pair of metal skins, such as aluminum or steel, having a foamed thermal plastic core member sandwiched therebetween. The skins are bonded to the core member by a known flexible adhesive. The foamed thermal plastic core member is resilient and may be made from foamed high density or foamed low density thermal plastic. The foaming of the core member in the present invention reduces the weight of the composite plate versus prior art solid plastic core composite plates and provides for an increased the peel strength of the composite plate versus prior art solid plastic core composite plates. Furthermore, foaming of the thermal plastic core member in the present invention reduces the shear stress of the skin to core bond layer so as to reduce the potential of delamination of the metal skins from the thermal plastic core member under changing temperatures which has been found to be a problem with solid core composite plates.

The invention claimed is:  
     
         1 . A trailer comprising: a floor and at least one upstanding member extending upwardly from said floor, said upstanding member including a pair of skins having a foamed thermal plastic core member sandwiched therebetween.  
     
     
         2 . A trailer as defined in    claim 1   , wherein said foamed thermal plastic core member is resilient.  
     
     
         3 . A trailer as defined in    claim 1   , wherein said foamed thermal plastic core member is made from foamed high density thermal plastic.  
     
     
         4 . A trailer as defined in    claim 3   , wherein said foamed high density thermal plastic is foamed high density polyethylene or high density polypropylene.  
     
     
         5 . A trailer as defined in    claim 1   , wherein said foamed plastic core member is made from foamed low thermal plastic.  
     
     
         6 . A trailer as defined in    claim 5   , wherein said foamed low density thermal plastic is foamed low density polyethylene or low density polypropylene.  
     
     
         7 . A trailer as defined in    claim 1   , wherein said upstanding member is a side wall or a front wall of said trailer.  
     
     
         8 . A trailer as defined in    claim 1   , wherein said upstanding member is a door of said trailer.  
     
     
         9 . A trailer as defined in    claim 1   , wherein said skins are formed from metal.  
     
     
         10 . A trailer as defined in    claim 1   , wherein said skins are bonded to said core member by a flexible adhesive.  
     
     
         11 . A trailer as defined in    claim 1   , wherein said upstanding member is formed by mixing thermal plastic resin pellets and gas pellets; applying heat to said mixed pellets and extruding said heated mixture.  
     
     
         12 . A trailer as defined in    claim 1   , wherein said upstanding member is formed by applying heat to thermal plastic resin pellets in a heating chamber; injecting nitrogen into said heating chamber, thereby forming a foamed mixture; and extruding said foamed mixture from said heating chamber.  
     
     
         13 . A trailer as defined in    claim 1   , wherein said upstanding member is formed by mixing thermal plastic resin pellets and gas pellets; applying heat to said mixed pellets in a heating chamber; injecting nitrogen into said heating chamber, thereby forming a foamed mixture; and extruding said foamed mixture from said heating chamber.  
     
     
         14 . A trailer as defined in    claim 1   , wherein said thermal plastic core member has a thickness of one half of an inch or less.  
     
     
         15 . A method of forming a wall or a door of a trailer comprising the steps of: mixing thermal plastic resin pellets and gas pellets together; applying heat to said mixed pellets; extruding said heated mixture into a core member; and bonding skins to opposite sides of said core member.  
     
     
         16 . A method as defined in    claim 15   , further including the step of applying a flexible adhesive to inner surfaces of said skins or to opposite sides of said core member prior to bonding said skins to said opposite sides of said core member.  
     
     
         17 . A method of forming a wall or a door of a trailer comprising the steps of: applying heat to thermal plastic resin pellets in a heating chamber; injecting nitrogen into said heating chamber, thereby forming a foamed mixture; extruding said foamed mixture from said heating chamber into a core member; and bonding skins to opposite sides of said core member.  
     
     
         18 . A method as defined in    claim 17   , further including the step of applying a flexible adhesive to inner surfaces of said skins or to opposite sides of said core member prior to bonding said skins to said opposite sides of said core member.  
     
     
         19 . A method of forming a wall or a door of a trailer comprising the steps of: mixing thermal plastic resin pellets and gas pellets together; applying heat to said mixed pellets in a heating chamber; injecting nitrogen into said heating chamber, thereby forming a foamed mixture; extruding said foamed mixture from said heating chamber into a core member; and bonding skins to opposite sides of said core member.  
     
     
         20 . A method as defined in    claim 19   , further including the step of applying a flexible adhesive to inner surfaces of said skins or to opposite sides of said core member prior to bonding said skins to said opposite sides of said core member.  
     
     
         21 . A wall for use in a trailer comprising: a member including a pair of skins having a foamed thermal plastic core member sandwiched therebetween.  
     
     
         22 . A wall as defined in    claim 21   , wherein said foamed thermal plastic core member is made from foamed high density thermal plastic.  
     
     
         23 . A wall as defined in    claim 22   , wherein said foamed high density thermal plastic is foamed high density polyethylene or high density polypropylene.  
     
     
         24 . A wall as defined in    claim 21   , wherein said foamed thermal plastic core member is made from foamed low density thermal plastic.  
     
     
         25 . A wall as defined in    claim 24   , wherein said foamed low density thermal plastic is foamed low density polyethylene or low density polypropylene.  
     
     
         26 . A wall as defined in    claim 21   , wherein said skins are formed from metal.  
     
     
         27 . A wall as defined in    claim 21   , wherein said skins are bonded to said core member by a flexible adhesive.  
     
     
         28 . A wall as defined in    claim 21   , wherein said thermal plastic core member has a thickness of one half of an inch or less.  
     
     
         29 . A door for use in a trailer comprising: a member including a pair of skins having a foamed thermal plastic core member sandwiched therebetween.  
     
     
         30 . A door as defined in    claim 29   , wherein said foamed thermal plastic core member is made from foamed high density thermal plastic.  
     
     
         31 . A door as defined in    claim 30   , wherein said foamed high density thermal plastic is foamed high density polyethylene or high density polypropylene.  
     
     
         32 . A door as defined in    claim 29   , wherein said foamed thermal plastic core member is made from foamed low density thermal plastic.  
     
     
         33 . A door as defined in    claim 32   , wherein said foamed low density thermal plastic is foamed low density polyethylene or low density polypropylene.  
     
     
         34 . A door as defined in    claim 29   , wherein said skins are formed from metal.  
     
     
         35 . A door as defined in    claim 29   , wherein said skins are bonded to said core member by a flexible adhesive.  
     
     
         36 . A door as defined in    claim 1   , wherein said thermal plastic core member has a thickness of one half of an inch or less.