Abstract:
A headliner ( 10 ) for use with a motor vehicle including a combination of a chopped fiber roving ( 22 ) bonded between a non-woven film layer and a urethane core ( 14 ) to eliminate warpage in the headliner ( 10 ) after the molding and forming process is complete. The combination of stiffness and mechanical bond provides this effect. The combination may also include a polypropylene non-woven material ( 18 ) combined with a polyethylene film ( 20 ) to form a laminate top ( 12 ) and bottom layer ( 16 ). The chopped fiber roving ( 22 ) is randomly disposed between the laminate ( 21 ) and a urethane matrix ( 44 ) used to form a core ( 14 ) of the headliner ( 10 ) to provide the shape stability to the headliner ( 1 ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a headliner for use with a motor vehicle and, more particularly, to a headliner formed of multiple layers to provide shape stability and a method of manufacturing the same.  
           [0003]    2. Description of the Related Art  
           [0004]    Headliners are used with motor vehicles to provide a pleasing finish to the interior of a vehicle compartment. Headliners also provide for sound absorption and insulation and accordingly increase the quality of environment in the vehicle compartment.  
           [0005]    Headliners typically include a number of different layers of material. Typically, they are formed of a foam or urethane core sprayed between two reinforcing layers. The layers of material are assembled and then molded into the desired shape, normally the shape of the vehicle ceiling. Current urethane headliners tend to warp shortly after demolding and often retain the distorted shape permanently.  
           [0006]    Therefore, it is desirable to provide a multi-layer headliner, and method of manufacturing same, such that the headliner will retain its molded shaped and not warp after being removed from the mold.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a headliner and method of making the same that overcomes the problem of permanent warpage normally occurring shortly after demold. According to one aspect of the invention a headliner is formed of top and bottom layers having a urethane matrix sprayed between the layers to form the core. The headliner includes a separate scrim layer, a film layer, and a chopped fiber material randomly distributed between the film layer and the urethane core. In some instances, a binder material may be used to increase adherence of the chopped fiber material to the film layer. The film layer is perforated to allow for degassing of the urethane matrix.  
           [0008]    According to another aspect of the invention a method is provided for forming a headliner for an automotive vehicle. The method includes the steps of providing a top layer and bottom layer of laminated non-woven polypropylene scrim and polyethylene film, providing a layer of fiberglass mat between the top and bottom layers, dispensing a urethane matrix onto the layer of fiberglass mat between the top and bottom layers, and randomly dispersing a chopped fiber material between at least one of the top and bottom layers and the urethane matrix to provide internal structural rigidity to the headliner.  
           [0009]    Accordingly, the combination of the chopped fiber material and a nonwoven film provide a synergistic effect that eliminates headliner warpage. The combination of stiffness and mechanical bond between the film layer and chopped fiber material randomly distributed between the film layer and urethane core provides this effect. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Other features and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description when considered in connection with the accompanying drawings wherein:  
         [0011]    [0011]FIG. 1 is a top view of an automotive headliner according to the present invention;  
         [0012]    [0012]FIG. 2 is an enlarged partial cross-sectional view of the headliner of FIG. 1 taken along line  2 - 2  of FIG. 1;  
         [0013]    [0013]FIG. 3 is a schematic side view of an apparatus using a method of forming the headliner of the present invention with the press shown in the open position; and  
         [0014]    [0014]FIG. 4 is a schematic side view of an alternative embodiment of an apparatus using a method of forming the headliner of the present invention with the press shown in the open position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    Referring to FIG. 1, there is illustrated a headliner  10  of the present invention. The headliner  10  conforms and fits to the ceiling of the passenger compartment of a motor vehicle. The headliner  10  is formed as a laminate including a top layer  12 , a urethane core  14  and a bottom layer  16 .  
         [0016]    As shown in FIG. 2, each of the top and bottom layers  12 ,  16  include a nonwoven polypropylene scrim  18  and a polyethylene film  20  combined to form a laminate  21 . The non-woven polypropylene scrim  18  is preferably supplied by weight, specifically, 0.1 to 2.0 ounces per square yard, while the polyethylene film  20  is preferably 0.0005 to 0.003 inches thick.  
         [0017]    The scrim  18  and film  20  are laminated by a combination of heat and pressure through nip rolls. Nip rolls are a pair of opposed rollers having a small gap therebetween. The rollers are heated to a temperature of about 160 degrees Fahrenheit and the scrim  18  and film  20  are run through the heated rollers to create a bond and laminate the scrim  18  and film  20 . The laminate  21  is then perforated. Perforation of the laminate  21  allows air and gas to permeate through the laminate  21  during the step of forming the core  14 .  
         [0018]    The core  14  is formed from a layer of a fiberglass mat  42  embedded in a urethane matrix of foam  44 .  
         [0019]    A chopped fiberglass roving  22  is randomly distributed between the film  20  of the top layer  12  and the core  14 . In one embodiment of the invention, the chopped fiberglass roving  22  is randomly distributed on the film  20 . When the chopped fiberglass roving  22  is distributed on the film  20  prior to forming the substrate; i.e. when the laminate  21  includes the chopped fiberglass roving  22 , a binder material  24  is also distributed on the film  20  and operates to adhere the chopped fiberglass roving  22  to the film  20 . The binder material  24  may be distributed on the film  20  along with the chopped fiberglass roving  22 . The binder material  24  is a polyester powder adhesive that can be purchased from Bostick of Middleton, Mass. When used, the binder material  24  is applied by weight, specifically, 1 to 20 percent, by means of a shaker box that distributes at random a specific amount of the adhesive. The weight of the chopped fiberglass roving  22  determines the amount of binder  24  required; e.g., 40 grams per square meter requires 5 grams of powder adhesive or approximately 12 percent by weight. The fiberglass roving  22  is formed of fiberglass strands having a diameter of 0.03 inches chopped into two-inch lengths. As set forth above, the chopped fiberglass is randomly distributed on either the polyethylene film  20  or the urethane core  14  at a density of 5 to 150 grams per square meter. It should be appreciate that the fiberglass roving  22  may alternatively be randomly distributed between the polyethylene film  20  of the bottom layer  16  and the core  14  or between both the top and bottom layers  12 ,  16  and the core  14 .  
         [0020]    Turning now to FIG. 3, there is shown an apparatus for use with the method for forming the headliner panel  10 . The apparatus includes a forming tool or die  30  shown with an upper platen  32  attached to a press head  34  and a lower platen  36  attached to a press bed  38 . The laminate  21  forms both the top  12  and bottom  16  layers of the headliner  10  and is supplied as a rolled good from supply rollers  40 ,  41 . The fiberglass mat  42  is supplied as a rolled good from supply roller  48 . During the manufacturing process, as the glass mat  42  is rolled or pulled into the forming tool  30 , the urethane matrix  44  is sprayed onto the glass mat  42  by a urethane spray head  46 . Next, the chopped fiberglass roving  22  is distributed from a hopper  50  onto the urethane matrix  44 , after which the entire assembly including the top layer  12 , chopped fiberglass roving  22 , urethane matrix  44 , glass mat  42 , and bottom layer  16  are placed in the forming tool  30  which operates, through a molding cycle, to form the headliner  10 . In this method or process, no binder  24  is used. If required, additional glass or other fibers can be added as rolled goods prior to spraying the urethane matrix  44 . Also, additional chopped fiber materials such as jute, sisal, or hemp may be used in place of the chopped fiberglass roving  22 .  
         [0021]    Turning now to FIG. 4, an alternative embodiment of an apparatus and method for manufacturing a headliner  10  is shown. Again, a forming tool or die  30  receives the headliner  10  components from a plurality of supply rollers. The lower or bottom layer  16  is the laminate  21  supplied as a rolled good drawn from supply roller  40 . A fiberglass mat  42  is also supplied from a supply roll  48 . Once again, prior to the molding process, a urethane matrix  44  is deposited on the fiberglass mat  42  by a urethane spray head  46 . The top layer  12  includes the laminate  21  with the chopped fiberglass roving  22  already secured thereto by a binder material  24 . The top layer  12  is supplied as a rolled good from a supply roller  52 .  
         [0022]    Accordingly, the chopped fiberglass roving  22  gives internal structure to the headliner  10  as the urethane matrix  44  adheres to the chopped fiberglass roving  22  to prevent the headliner  10  from warping after shaping and molding in the forming tool  30 . It should be understood that the film  20 , while perforated to allow the air and gas to escape therethrough, provides a barrier that prevents the urethane matrix  44  from leaking through to the outer surface of the headliner  10 . Finally, the scrim  18  provides an anti-squeak and smooth surface quality to the outer surface of the headliner  10 .  
         [0023]    Pursuant to the present invention, the chopped fiber material combines with the polypropylene non-woven material and polyethylene film to prevent warpage in headliners and similar products. As disclosed herein, various chopped fiber materials may be used. The invention teaches inline random distribution of the chopped fiber material during introduction directly onto the urethane matrix. Alternatively, the chopped fiber material is randomly distributed on and attached to the polypropylene non-woven material and polyethylene film laminate by a binder material prior to layering with the urethane matrix.  
         [0024]    The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.  
         [0025]    Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.