Abstract:
The present invention provides a door panel insert having an integral cover skin material. The door panel insert comprises a first layer or the decorating layer, a second layer, a recylate layer and a fourth layer. The recylate layer is sandwiched between the second layer and the fourth layer. The first layer is tacked on to the second layer before the molding process such that during compression and heating of the trim panel the first layer is chemically bonded to the second layer.

Description:
TECHNICAL FIELD  
         [0001]    This patent discloses and claims a useful, novel, and unobvious invention for a trim panel for use in motor vehicles. More specifically a trim panel formed from natural fiber mat and a method of making such trim panel is disclosed in the present application.  
         BACKGROUND  
         [0002]    It is known to provide a trim panel assembly for an automotive vehicle to present an aesthetically pleasing appearance in an occupant compartment of the automotive vehicle. Trim panels have typically been used in headliners, instrument panels and doors. The current automotive interior styling trend is toward a softer, wrap-around styling vision which places special emphasis on the tactile feel of the interior, as well as the visual impression. The hard plastic substrates and surfaces of car interiors in past years are being replaced by the trend toward padded or cushioned surfaces, covered by either vinyl or textile materials. The automotive interior surfaces typically comprise a structural substrate of aluminum, plastic or which is relatively rigid. A layer of padding and a trim panel may cover the interior surface of the substrate. The surface of the trim panel which is exposed to the passenger are typically leather, vinyl or textile materials, including cloth or carpet. In addition a layer of foam is inserted between the substrate and the surface that is exposed to give the trim panel a tactile feel.  
           [0003]    Current interior trim suppliers are using a variety of methods to apply the layer of exposed surface and padding to the substrates of various interior trim systems. The most common and least technologically advanced method is hand applying the coverings to the substrate. The layers are hand laid over a finished substrate and then pushed, pulled, tucked and pinched into the contour of the substrate. The layers are secured with adhesives and/or mechanical fasteners such as staples or the like. Obviously hand applied trim panels have high labor costs. Yet another method is vacuum forming and low-pressure molding (LPM). In LPM the trim panel is attached concurrently with the molding of the rigid substrate.  
           [0004]    However, it is desirable to provide a trim panel assembly with reduced mass, tooling and equipment per vehicle. Therefore, there is a need in the art to provide an improved method of making a trim panel assembly for an automotive vehicle that has an integral cover skin and desired coloring for the trim panel.  
         SUMMARY  
         [0005]    In one aspect of the present invention, a door panel installed in an interior of a motor vehicle comprises a first layer formed of a first material, a second layer formed of a second material, a third layer formed of a third material and a fourth layer formed of the same material as the second layer. The second and the forth layer are adaptable to be molded such that they form the substrate of the door panel.  
           [0006]    In yet another aspect of the present invention, a method of forming a door panel for an interior of a motor vehicle is disclosed. The method comprises forming the second layer and the fourth layer. Sandwiching the third layer between the second layer and the fourth layer. The first layer is then tacked on top of the second layer. The pre-formed layers are then inserted inside a molding tool and heated such that the first layer is integrally attached to the second layer. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]    [0007]FIG. 1 is a perspective view of a door panel insert, according to the preferred embodiment of the present invention; and  
         [0008]    [0008]FIG. 2 is a cross-sectional view of a portion of the door panel insert, showing the layers of the trim panel thereof in accordance with the preferred embodiment of the present invention; and 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0009]    The following description of the preferred embodiments is merely exemplary in nature, and is in no way intended to limit the invention or its application or uses.  
         [0010]    Referring in particular to FIGS. 1 and 2, a door panel insert installed in the interior of a motor vehicle in accordance with the teachings of the present invention is generally designated by reference numeral  10 . Although not shown in the drawings the door panel inset  10  is a part of a door of the motor vehicle. The door panel insert  10  defines an exterior surface  14  and is attached to a door panel substrate  18 . Alternatively, the door panel insert  10  may be directly attached to a substrate such as an interior metallic sheet made of aluminum or a hard plastic substrate. The exterior surface  14  is exposed to the interior of the motor vehicle and is also known as a Class A surface.  
         [0011]    It should be understood that the door panel insert  10  is only illustrated as an example. The insert formed by the method of this invention may be mounted to other panels of the motor vehicle such as instrument panels, headliners, arm rests, center consoles, seating, head rests, A, B or C pillars.  
         [0012]    The door panel insert  10  in accordance with the teachings of the present invention is preferably attached to a door panel substrate  18 . The door panel substrate  18  is relatively rigid than the door panel insert  10 . This method of forming the door panel insert  10  can also be used to form the door panel substrate  18 . The door panel insert  10  is attached to the door panel substrate  18  with the help of heat stacking process. Alternatively, the door panel insert  10  can be attached to the door panel substrate  18  with the help adhesives. Preferably, the adhesive used is a thermosetting adhesive such as cross linking urethane such that on heating it bonds the door panel insert  10  to the substrate  18 .  
         [0013]    The door panel insert  10  comprises a first layer or an outer decorative layer  20 , a second layer  22 , a third layer  24  and a fourth layer  26 . The first layer  20  of the door panel insert  10  forms the exterior surface  14  or the class A surface. As will be explained later, the class A surface or the exterior surface  14  of the door panel insert is simultaneously formed with the formation of the substrate portion  22  and  26  of the door panel insert  10 . As discussed above, first layer  20  is exposed to a passenger of the motor vehicle. The fourth layer  26  is attached to the door panel substrate  18 . Preferably, the second layer  22  and the third layer  24  are sandwiched between the first layer  20  and the fourth layer  26 . Alternatively, it is possible that the trim panel assembly  10  is formed with fever than four layers. For example, the trim panel assembly may be formed only of the first layer  20 , the second layer  22 .  
         [0014]    The first layer  20 , as explained above is generally the layer that is exposed to the passenger of the motor vehicle. The first layer  20  is formed of a first material. Preferably, the first material used to form the first layer  20  is extruded polypropylene. The process of obtaining an extruded polypropylene is well known in the art and is not explained in details. Alternatively, the first layer  20  could also be formed of a spun bond polypropylene. As will be explained later in either case, the first layer  20  is bonded to the upper surface  28  of the second layer  22 . The thickness of the first layer  20  is determined by the density of the second layer  22 . In order to manufacture a trim panel assembly  10  with the desired color, color may be added to polypropylene material. Alternatively, it is also possible to add more than one color to the first layer  20  such that the trim panel assembly  10  has more than one color. Additionally, it is also possible to add or control the grain size of the first layer  20 .  
         [0015]    The second layer  22  of the trim panel assembly  10  acts as a padding between the door panel substrate  18  and the first layer  20 . Additionally, the second layer  22  also serves to impart structural integrality to the trim panel assembly  10 . Preferably, the second layer  22  is formed of natural fiber composites. The natural fibers are derived from plants such as kenaf, hemp, flax, jute and sisal. These natural fibers are mixed with polypropylene and/or PET to form the natural fibers composites used in the present invention.  
         [0016]    The third layer  24 , in accordance with the teaching of the present invention is made of a recyclate material. In this invention by recylate material it is meant any material that can typically be recycled into the environment when the trim panel assembly  10  is removed from the motor vehicle. The process of adding the recylate material to the trim panel assembly  10  is explained in detail later. The third layer  24 , is sandwiched between the second layer  22  and the fourth layer  26 . Preferable the materials that are used to form the third layer  24  are selected from a group comprising of vinyl offal, or natural fiber offal.  
         [0017]    The upper surface  30  of the fourth layer  26 , is preferably attached to the third layer  24  and the lower surface  32  is preferably attached to the substrate  18 . Suitable materials that are used to form the fourth layer  26  are preferably the same that are used to form second layer  22 . Alternatively, different material may be used to form the second layer  24  and the fourth layer  26 . It is also possible that the density of the second layer  22  is different from the density of the forth layer  26 . However, it is preferable that the second layer  22  and the fourth layer  26  have the same thermoformable temperature. In the preferred embodiments the materials used to form the fourth layer  26  of the trim panel assembly is natural fiber mat or alternatively may be a mixture of natural fiber and polypropylene fiber.  
         [0018]    As shown in FIG. 2, the cross section of the door panel insert  10  comprises a first layer  20  formed of extruded polypropylene or spun bond polypropylene, and a second layer  22  formed of a natural mat that is adaptable to be molded into a substrate. Additionally, the door panel insert  10  comprises a third layer  24  formed of a recyclate material and a fourth layer  26  formed of the same material as the second layer. Both the second layer  24  and the fourth layer  26  are adaptable of being molded such that a need for a separate substrate is substantially eliminated.  
         [0019]    The method of forming the door panel insert  10  comprises forming a pre-form wherein the first layer  20 , second layer  22 , third layer  24  and the fourth layer  26  are individually formed. Additionally, the second layer  22  and the fourth layer  26  are molded into a hard substrate during the compression molding process such that the door panel insert  10  can be attached to the door panel substrate  18 . The first step of forming the pre-form of the door panel insert  10  comprises forming the second layer  22  and the fourth layer  26 . The process of forming the second layer  22  and the fourth layer  26  from natural fiber mat composites is well known in the art and not explained in details. Briefly stated, the fibers from natural sources such as hemp is mixed with polypropylene fibers with the help of a binder material. Typically, the fibers are chopped to a desired size and mixed with the polypropylene fibers. The binding material is then added to the mixture of natural fiber and the polypropylene fibers and heated such that mat having the desired thickness is formed. The recyclate material forming the third layer  24  is obtained in a granular form. The granular form of the third material is heated and dropped on the top surface  30  of the fourth layer  26 . The second layer  22  is then tacked on top of the third layer  24 , such that the third layer  24  is sandwiched between the second layer  22  and the fourth layer  26 . Finally, the first layer  20  is added on the top surface of the second layer  22 .  
         [0020]    After the pre-form comprising the individual layers are formed, the door panel insert  10  is inserted inside a molding tool. The molding tool is well known in the art and is not described in detail. The door panel insert  10  is then subjected to compression molding and heating such that a chemical bond is formed between the polypropylene fibers in the natural mat of the second layer  22  and the polypropylene fibers in the first layer  20 . After undergoing the heating and compression the door panel insert  10  is taken out of the molding tool and attached to the door panel substrate  18  by the heat staking. Alternatively, adhesives may be used to attach the door panel insert  10  to the door panel substrate  18 .  
         [0021]    In this invention, the introduction of the third layer  24  formed of a recylate material allows for the door panel insert  10  to be recylated once the door panel insert  10  is removed from the motor vehicle. Additionally, it also allows for a door panel insert  10  or a door panel  18  having greater strength and the elimination to add a separate coverskin material to form the class A surface. As explained above, this process may be used to form the door panel  18 .  
         [0022]    As any person skilled in the art will recognize from the previous description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of the invention.