Patent Publication Number: US-2007114812-A1

Title: Insulation Panel

Description:
BACKGROUND  
      Vehicles are often designed and manufactured for use within one environment and then used in another environment. The other environment may expose the vehicle to unanticipated extreme continuous temperatures. For example, many military vehicles and construction vehicles were designed for use within environments similar to those found within the continental United States and are then being used in desert and high temperature areas of the Middle East.  
      The internal cabin temperatures of those vehicles often border on the unbearable. Rooftop vehicle temperatures can reach 250° F. The headliner surface areas within the cabin can also reach 250° F. These temperatures are caused by solar radiation. Even when the vehicles are equipped with an air-conditioning system it is difficult to keep cabin temperatures below 85° F. The interior roof and door temperatures can become too hot to touch.  
      Some vehicles are retrofitted with armor. The doors, roof and side panels of the vehicle may be armored. The armor is typically a high strength metal. The armor acts as a heatsink. As a result, the excessive cabin temperature problem is aggravated further. To make matters worse the extra weight added to the vehicle by the armor requires additional engine power to move the vehicle. The additional engine power required to move the vehicle results in less engine power being available to power the air-conditioning system.  
      Many of the interior cabin surfaces on military and construction vehicles are unpadded metal. The unpadded metal often becomes too hot to touch in extreme environments. The unpadded metal can also cause injuries when it is contacted by the vehicle occupants during periods of vehicle turbulence.  
      It is desirable, and an object of this invention, to be able to retrofit (and initially manufacture) vehicles with interior and exterior cabin thermal insulation. The insulation will be placed upon the vehicle roof and also upon the interior cabin surfaces such as the doors of a vehicle and the interior roof surface. This cabin insulation will allow a vehicle air-conditioning system to provide enhanced cooling within the cabin, resulting in a lower passenger compartment temperature.  
      A new and improved insulation panel is needed. The insulation panel would have the following properties. It would be lightweight. It would be flame retardant and ultraviolet resistant. It would be easy to shape and to install. It should have an adhesive coating covered by a release material which would allow peel and stick application to a vehicle. It should facilitate retrofitting the cabin and roof of an existing vehicle. It should provide padded interior cabin surfaces. It should be aesthetically pleasing and facilitate color matching with the environment to assist in camouflaging the vehicle. It should be abrasion resistant and puncture resistant. It should be moisture resistant. It should be stable when continuously exposed to temperatures of up to 250° F. It should be stable and durable, whether applied to an interior cabin surface or an exterior cabin surface.  
     SUMMARY  
      The insulation panel described herein provides these features and benefits. The insulation panel is intended to be used to insulate the passenger compartment of a vehicle. The passenger compartment is comprised of exterior passenger compartment surfaces and interior passenger compartment surfaces.  
      In its simplest form the insulation panel is comprised of a section of insulation and a protective cover. The section of insulation is closed cell foam insulation. It has a top surface and a bottom surface. Preferably, the insulation is comprised of closed cell polyolefin foam. The best insulation is medium density polyethylene cross-linked closed cell foam. The foam should be cross-linked by irradiation, rather than chemically. The foam is formulated with a fire retardant additive to limit its flammability. Preferably, it is also formulated with an ultraviolet radiation resistant additive.  
      Medium density polyethylene cross-linked by irradiation closed cell foam is typically extruded into relatively thin plies during the manufacturing process. The desired foam thickness is obtained by laminating the plies together. The bottom surface of the section of insulation should be comprised of a layer of ethylene vinyl acetate (EVA) foam. EVA provides a better base for the application of release material covered adhesive. The release material is more likely to separate from the adhesive, rather than cause the adhesive to pull away from the insulation, when the release material is removed.  
      The protective cover is bonded to the top of the foam insulation. The protective cover is comprised primarily of thermoplastic polyolefin or polyurea. Preferably, the protective cover is formulated with a fire retardant additive and an ultraviolet radiation resistant additive.  
      The protective cover and the insulation should be color matched to the intended environment of vehicle use. For example, if the vehicle is intended to be used within a sandy desert environment, the protective cover and the insulation should be sand colored.  
      Additionally, a layer of adhesive and a layer of release material should be applied to the bottom of the insulation. The adhesive must be thermally stable within the environmental temperature range of expected use. It should be thermally stable at 200° F. and is preferably thermally stable at 250° F. The preferred adhesive is a pressure sensitive acrylic adhesive.  
      The release material releasably covers the adhesive. It provides a nonstick surface at the bottom of the foam insulation. It may be pulled away from the adhesive to expose the adhesive.  
      In order to retrofit a vehicle with an insulation panel the insulation panel must be shaped to fit a passenger compartment surface of the vehicle. If the insulation panel is to be used upon the exterior roof surface of a vehicle, one or more panels should be cut to fit the roof surface. If the insulation panel is to be used upon an interior door surface, it should be cut to fit that door surface. Typically, this would involve shaping the perimeter of the insulation panel to fit the perimeter of the interior surface of the door and cutting out any necessary openings, such as a window opening.  
      Shaped insulation panels may be provided to a user as a kit of panels. Each panel is shaped to fit an exterior or interior passenger compartment surface. The panels provided would cover the roof and the interior passenger compartment surfaces. 
    
    
     DRAWINGS  
      These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:  
       FIG. 1  is a perspective view of a vehicle with a roof covered by an insulation panel.  
       FIG. 2  is a perspective view of an insulation panel having a thermoplastic polyolefin cover.  
       FIG. 3  is a cross-sectional elevation view of the insulation panel having a thermoplastic polyolefin cover of  FIG. 2 .  
       FIG. 4  is a perspective view of the interior of the vehicle of  FIG. 1  showing interior passenger compartment surfaces covered by insulation panels.  
       FIG. 5  is a perspective view of an insulation panel having a polyurea cover.  
       FIG. 6  is a cross-sectional elevation view of the insulation panel having a polyurea cover of  FIG. 5 .  
       FIG. 7  is a perspective view of a vehicle having a differently configured roof, wherein the roof is covered by four insulation panels.  
       FIG. 8  is a perspective view of a kit of insulation panels shaped to fit the exterior passenger compartment surface and the interior passenger compartment surfaces of the vehicle of  FIG. 7 . 
    
    
     DESCRIPTION  
      The preferred embodiment of an insulation panel  20  is comprised of a section of insulation  30 , a layer of adhesive  40 , a layer of release material  42  and a protective cover  44 . The insulation panels  20  described herein are useful for insulating the passenger compartment  24  of a vehicle  22 . The vehicle  22  may be a military vehicle, such as a Humvee, or a construction vehicle. The vehicle  22  is likely to be used within a hot environment. Therefore, it will be desirable to insulate the passenger compartment  24  of the vehicle  22  in order to enhance the cooling capacity of the vehicle&#39;s  22  air-conditioning system. The passenger compartment  24  is made up of exterior passenger compartment surfaces  26  and interior passenger compartment surfaces  28 . Typical exterior passenger compartment surfaces  26  and interior passenger compartment surfaces  28  are illustrated in  FIG. 1  and  FIG. 4 . The exterior roof of the vehicle  22  is an exterior passenger compartment surface  26 . The interior door surface areas, the interior roof/headliner area and other vehicle body structural surfaces are interior passenger compartment surfaces  28  and surround the passenger compartment  24 . One of the objects of this invention is to provide an insulation panel  20  which is useful for insulating the exterior passenger compartment surfaces  26  and the interior passenger compartment surfaces  28  of a vehicle  22 . A vehicle  22  so insulated will have a lower passenger compartment  24  temperature than an uninsulated vehicle when the vehicle  22  is air-conditioned by a vehicle air-conditioning system while the vehicle is within a hot environment, such as a desert in the Middle East during the summer season.  
      The section of insulation  30  is comprised of closed cell foam. The section of insulation  30  has a top surface  32  and a bottom surface  34 . Preferably, the section of insulation  30  is comprised of medium density polyethylene closed cell foam which has been cross-linked by irradiation. This material has a density of approximately 2 pounds per cubic foot. It is comprised of many small cells  38 . It should be manufactured with a foaming agent which produces nitrogen encapsulated cells. This will avoid the emission of toxic or noxious fumes when the cells within the foam outgas. The closed cells of the foam provide rigidity and resist the absorption of water and other contaminants.  
      Cross-linking is the joining of polymers by the creation of covalent bonds. Cross-linking by irradiation involves directing an electron beam or electromagnetic radiation at the foam, or the raw materials used to produce the foam, during the manufacturing process. Cross-linking by irradiation produces superior cell properties compared to cross-linking chemically. The cells are stiffer and more thermally stable (i.e. withstand a higher temperature). The foam also tends to be self extinguishing.  
      In the preferred embodiment the foam is formulated with a fire retardant additive and an ultraviolet radiation resistant additive. These properties can be obtained by brominating the resin used to manufacture the foam, or brominating the foam while it is being extruded during the manufacturing process. Other halogens may also be used. Other fire retardant additives and ultraviolet radiation resistant additives, and processes for enhancing the fire retardant and ultraviolet radiation resistant properties of foam, both proprietary and nonproprietary, known to those skilled in the art of foam fabrication, are within the scope of this invention. An irradiation cross-linked polyethylene foam with a continuous smooth surface, fine cell structure, and improved fire retardant properties is currently being sold under the trade name “VOLARA TYPE MF” by Voltek, LLC. “VOLARA TYPE MF” exceeds the United States federal Motor Vehicle Safety Standard 302 horizontal flame retardant test.  
      Irradiation cross-linked polyethylene foam is typically extruded into relatively thin sheets or plies  36  at the time of manufacture. Larger thicknesses can be obtained by laminating the plies  36  together. The plies  36  are heated to the point of being tacky and then compressed to form a laminated bond. Optimal foam thickness for use within the passenger compartment  24  of a vehicle  22  has been found to be approximately 1 inch. The optimal foam thickness for use on the exterior passenger compartment surfaces  26  has been found to be approximately 0.44 inches. However, the scope of this invention is not limited by the foam thickness of an insulation panel  20 .  
      A layer of adhesive  40  is applied to the bottom of the section of insulation  30 . The adhesive  40  must be thermally stable at temperatures up to 200° F. Preferably, the adhesive  40  is thermally stable up to a temperature of approximately 250° F. The adhesive  40  should be a pressure sensitive acrylic adhesive. This will allow an insulation panel  20  to be pressed onto an interior roof surface of a vehicle and immediately bonded such that it will not fall. Acrylic adhesives  40  are known to be thermally stable at temperatures up to 250° F. Acrylic adhesives  40  can also be pressure sensitive such that a bond is formed when two parts are compressed around the adhesive.  
      A layer of release material  42  covers the adhesive  40 . The release material  42  is adapted to releasably cover the adhesive  40  such that a nonstick surface is formed at the bottom of the foam insulation  30 . Because the release material  42  is adapted to releasably cover the adhesive  40  the insulation panel  20  is provided with a peel and stick feature, as shown in  FIG. 2  and  FIG. 5 . The insulation panel  20  can be stored without fear that it will bond to another material because the adhesive  40  is covered by the release material  42 . The release material  42  may be kraft paper. When it is desired to apply the insulation panel  20  to a vehicle  22  the release material  42  is pulled away from the adhesive  40 .  
      An adhesive  40  satisfying the criteria set forth is currently being sold by 3M as “ADHESIVE TRANSFER TAPE 6035PC” and “ADHESIVE TRANSFER TAPE 6035PL.” These are pressure sensitive adhesive transfer tapes. The adhesive  40  and the release material  42  are combined into a tape and sold in rolls. This adhesive tape can be applied to the section of insulation  30  by sending the section of insulation  30  and the tape through a pinch roller while the adhesive  40  of the tape is in contact with the bottom of the section of insulation  30 .  
      It has been discovered that, at times, the adhesive  40  may be pulled away from the section of insulation  30  when it is desired to only pull away the release material  42  from the adhesive  40  and leave the adhesive adhered to the section of insulation  30 . This problem may be solved by providing the section of insulation  30  with a bottom surface comprised of a 1/16″ layer or ply  36  of ethylene vinyl acetate (EVA) foam. This is accomplished by laminating a layer or ply  36  of ethylene vinyl acetate (EVA) foam to the bottom of the section of insulation  30 . The adhesive  40  does not pull away from the ethylene vinyl acetate (EVA) foam when the release material  42  is pulled away from the adhesive  40 . Ethylene vinyl acetate (EVA) foam suitable for this use is currently being sold under the trade name “VOLARA TYPE EO” by Voltek, LLC.  
      The protective cover  44  is bonded to the top of the section of foam insulation  30 . This invention encompasses two types of protective covers  44 . The first is primarily thermoplastic polyolefin. The second is primarily polyurea. When the insulation panel  20  is used to cover an exterior passenger compartment surface  26 , such as an exterior roof surface, a 0.44 inch (approximate) thick section of insulation foam  30  should be used with a polyurea protective cover  44 . When the insulation panel  20  is used to cover an interior passenger compartment surface  28 , such as an interior door panel, a 1 inch thick (approximate) section of insulation foam  30  should be used with a thermoplastic polyolefin protective cover  44 . This invention is not limited to these two foam thicknesses.  
      Preferably, both the thermoplastic polyolefin protective cover  44  and the polyurea protective cover  44  have been formulated with a fire retardant additive and an ultraviolet radiation resistant additive. Fire retardant and UV resistant properties can be obtained by brominating the protective cover  44  during the manufacturing process. Other halogens may also be used. Other fire retardant additives and ultraviolet radiation resistant additives, and processes for enhancing the fire retardant and ultraviolet radiation resistant properties of thermoplastic polyolefin and polyurea, both proprietary and nonproprietary, known to those skilled in the art of thermoplastic polyolefin coating and polyurea coating fabrication, are within the scope of this invention.  
      The thermoplastic polyolefin protective cover  44  should preferably be between 0.003 inches and 0.050 inches thick. It is typically extruded during the manufacturing process. The extruded thermoplastic polyolefin protective cover  44  is heat fused to the top ply  36  or top surface  32  of the section of insulation  30 . The thermoplastic polyolefin protective cover  44  should be of the soft polypropylene type. By covering the section of insulation  30  with a thermoplastic polyolefin protective cover  44 , the insulation panel is made more durable, more abrasion resistant, more puncture resistant, more aesthetically pleasing and better insulating. A leather grain texture may also be embossed upon the thermoplastic polyolefin protective cover  44  to make the protective cover more aesthetically pleasing and comfortable to touch.  
      The polyurea protective cover  44  is sprayed onto the top of the section of insulation  30 . It encapsulates the foam  30  and provides a durable hard finish which is ultraviolet radiation resistant. The polyurea protective cover  44  provides excellent chip, scratch and impact resistance. It provides enhanced blast mitigation. It is self extinguishing. It does not give off volatile vapors. It provides excellent adhesion for CARC (Chemical Agent Resistant Coating) paint used on military vehicles. It is easy to repair. A polyurea coating sold by PPG under the trade name “MIL-TOUGH” currently provides the most preferred properties for a polyurea protective cover  44  for the section of insulation  30 .  
      In the preferred embodiment the protective cover and the section of foam  30  are color matched to the intended environment of vehicle  22  use. For example, if the vehicle  22  is intended to be used within a sandy desert environment, the protective cover  44  and the section of insulation  30  should be sand colored.  
      In order to use one or more insulation panels  20  to insulate a vehicle  22 , each insulation panel  20  is shaped to fit a passenger compartment  24  surface of the vehicle  22 . For example, insulation panels  20  to be used to cover a vehicle  22  roof are shaped to conform to the roof shape, as shown in  FIG. 7  and  FIG. 8 . Similarly, insulation panels  20  to be used to cover an interior door surface  28 , or other interior passenger compartment surface  28 , are shaped to conform to those surfaces, as also shown in  FIG. 7  and  FIG. 8 . The insulation panels  20  may be provided in a kit form. Each insulation panel  20  of the kit is shaped to fit a separate passenger compartment  24  surface of the vehicle  22 , as shown in  FIG. 8 . In order to secure a properly shaped insulation panel  20  to the vehicle  22 , the release material  42  is peeled away from the adhesive  40  on the section of insulation  30 . The insulation panel  20  is then pressed into place resulting in an insulated vehicle  22 , as shown in  FIG. 1 ,  FIG. 4  and  FIG. 7 . The insulated vehicle  22  will have a much reduced passenger compartment  24  temperature when the vehicle  22  air-conditioning system operates within a hot environment.  
      Although the invention has been shown and described with reference to certain preferred embodiments, those skilled in the art undoubtedly will find alternative embodiments obvious after reading this disclosure. With this in mind, the following claims are intended to define the scope of protection to be afforded the inventor, and those claims shall be deemed to include equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.