Abstract:
A method for insert-molding a plural color film laminate part and part made by the method. The method comprises preforming a film laminate and subsequently insert-molding a plastic substrate against the preformed film laminate. An improvement in traditional insert molding techniques is provided by use of a specific mold cavity structure which facilitates positioning of the film laminate transition line(s) between colors within longitudinally extending groove(s) in the part show face. According to one embodiment, the film laminate is preformed with a re-entrant edge portion which is positioned within the mold cavity such that the edge of the plastic substrate will be substantially covered. The insert molding step involves positioning the preformed film laminate in a specially configured mold cavity, closing the mold and injecting molten resin into the mold cavity against the film laminate. The part includes a show surface having the paint film laminate superposed over a portion of the underlying substrate with a portion of the substrate exposed to provide a plural color or plural component aesthetic effect. The boundary between the paint film laminate and substrate, on the show surface, is defined by a channel into which an edge of the film laminate is tucked.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a divisional of U.S. patent application Ser. No. 10/225,791 filed on Aug. 22, 2002, which claims the priority benefit of U.S. Provisional Patent Application No. 60/325,597 filed Sep. 28, 2001. The disclosures of the above applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention pertains to improved methods of insert molding a film laminate, or the like, over a portion of a plastic substrate and to the parts made thereby.  
         [0003]     A variety of film laminate injection molded parts have been made and used for automobile body and trim parts. For example, bumpers, body panels, doors, filler panels, wheel covers, dashboards, armrests and other parts have been made via injection molding techniques. Additionally, with regard to automobile exteriors, bodyside trim moldings, beltline moldings, roof moldings and window moldings are made via injection molding of polyvinylchloride (PVC) or other thermoplastic materials.  
         [0004]     In order to provide a painted surface for these parts, film lamination techniques are commonly employed. In accordance with these processes, a paint film laminate is insert molded with the desired thermoplastic to fuse the film laminate over the injection molded part. The resulting injection molded part is ready for assembly without subsequent painting.  
         [0005]     The paint film laminate used in these insert molding techniques may comprise a backing sheet to which paint layers are adhered to form a colored side of the laminate. Typically, the backing sheet comprises an extruded thermoplastic sheet. In such paint film laminates, a paint film, comprising a cast dried continuous paint coating, is provided over the backing sheet. The paint film laminate may consist of a monocoat, a clear coat over a base coat, or a clear coat and a base coat with interposed print or design. The paint film laminate, including base coat, clear coat and print or design, if desired, may, for example, range from about 0.5-4 mil. in thickness.  
         [0006]     The laminated paint films are typically provided in a roll, unwound, then trimmed to a proper “preform” size and shape, ready for insertion into the injection mold. The preform is usually placed along the cavity side of the mold with the painted side thereof facing the mold cavity surface.  
         [0007]     In some instances, the pre-sized paint film laminate may be placed along the core side of the mold. The mold is then clamped and the desired molten resin is injected into the mold cavity. Heat and pressure conditions in the mold partially melt the backing sheet and a melt bonding or fusion of the injected resin and film laminate occur. Injection molds used for these processes are commonly rear or edge gated so that the molten resin is directed along the backside of the film laminate, pressing the show face side of the film laminate against the surface of the mold cavity. Techniques utilized to insert mold plastic parts covered by such paint film laminates are disclosed, for example, in U.S. Pat. Nos. 5,599,608; 5,783,287; 5,746,962 and 6,168,742 of common assignment herewith. The subject matter of these disclosures is incorporated by reference herein.  
         [0008]     It has become increasingly popular to insert or co-mold bumper, rocker panel, side trim, and chin spoiler parts for autos and trucks which incorporate a paint film laminate over only a portion of the show surface of the part with the remainder of the underlying plastic substrate being exposed so as to present a plural color or plural component show surface appearance.  
         [0009]     Conventionally employed insert molding techniques for manufacturing such plural colored film laminate parts often result in an unsightly appearance wherein the border between the paint film and the exposed substrate presents an uneven or wavy appearance on the show surface that stands in sharp contrast to the desired straight line or clean edge appearance that is intended and which must be achieved if the part is to be classified as a Class “A” show part. This undesirable appearance may be caused, for example, by shrinkage of the paint film laminate during the insert molding process.  
         [0010]     Accordingly, there remains a need in the art to improve upon the existing methods for insert molding of film laminates over plastic substrates in such manner that the border area of the laminate that is disposed on the show face of the part provides for a sharp, linear distinction between the film laminate surface and the exposed substrate surface.  
       SUMMARY OF THE INVENTION  
       [0011]     These and other objects of the invention are met by the instant methods and fused film laminate plastic parts made thereby.  
         [0012]     In accordance with the present invention, a film laminate part is insert molded utilizing a specifically configured mold cavity. The method includes the steps of providing a film laminate and subsequently insert molding a plastic substrate against the non-show-face side of the preformed film laminate. A film laminate preforming step may be used and involves shaping an unformed film laminate in a specially configured vacuum mold and subsequently trimming the shaped film laminate to obtain the preformed film laminate, with insert or edge portions, to be insert molded. The insert molding step involves positioning the preformed film laminate in a specially configured mold cavity such that the insert or edge portion thereof, to be disposed on the show face, is located adjacent a groove forming member within the mold cavity, closing the mold and injecting molten thermoplastic or thermosetting resin into the mold cavity against the non-show face side of the film laminate.  
         [0013]     Improvement in traditional insert molding techniques is provided by utilization of a specific mold cavity structure with a ridge-like groove forming member(s) therein which facilitates disposition of each paint film laminate insert or edge portion to be disposed on the show face of the part, within a separate groove which extends along the show face side of the resulting part. The mold cavity is equipped with a groove forming member(s) which align with the insert or edge portion(s) of the paint film laminate to be disposed on the show face of this part. Each groove forming member is configured with a predetermined depth to width ratio which results in the film laminate edges being disposed within the groove(s) such that the viewer will see only the film laminate at the point where it crests the entrance to the resulting groove and not the actual edge line located near the nadir of the groove.  
         [0014]     In one embodiment of the present invention, the film laminate covers at least one edge of the underlying substrate. In this case, the film laminate may be preformed with a re-entrant longitudinal edge portion, in accordance with the &#39;287 patent to Yamamoto and the like, such that the re-entrant longitudinal edge portion of the film laminate covers the associated longitudinal edge of the plastic substrate.  
         [0015]     The invention will be further described in conjunction with the appended drawings and following detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a plan view of the show surface of a paint film laminate part in accordance with the invention;  
         [0017]      FIG. 2  is a partially cut-away perspective view of the paint film laminate part shown in  FIG. 1 ;  
         [0018]      FIG. 3  is a cross-sectional view of a mold to be used in accordance with the invention to make a part such as that shown in  FIG. 1 ;  
         [0019]      FIG. 4  is a cross-sectional view of the mold depicted in  FIG. 3  with the film laminate and plastic in place;  
         [0020]      FIG. 5  is a partially cut-away perspective view of a second embodiment of a paint film covered part in accordance with the invention;  
         [0021]      FIG. 6  is a cross-sectional view of a mold utilized to make the part shown in  FIG. 5 ;  
         [0022]      FIG. 7  is an exploded sectional view of a portion of the mold shown in  FIG. 6 ;  
         [0023]      FIG. 8  is a perspective view of another embodiment of a paint film laminate that may be used to form a paint film laminate part in accordance with the invention;  
         [0024]      FIG. 9  is a partially cut-away perspective view of a part made by insert molding of the paint film laminate shown in  FIG. 8  over the underlying substrate;  
         [0025]      FIG. 10  is a partially cut-away view of another embodiment of a part made in accordance with the invention;  
         [0026]      FIG. 11  is a cross-sectional view of a mold cavity with paint film and plastic disposed therein similar to that shown in  FIG. 4  with the exception that a wider film has been placed in the mold cavity, thereby embedding the edges of the laminate deeply into the plastic substrate;  
         [0027]      FIG. 12  is a cross-sectional view of a mold cavity with paint film laminate positioned therein, similar to  FIG. 11 , but showing another embodiment of the invention;  
         [0028]      FIG. 13  is a magnified portion of the view shown in  FIG. 12  clearly depicting the cross-sectional shape of the ridge-like projection  28  depending from the mold cavity surface and the congruent channel formed in the part;  
         [0029]      FIG. 14  is a view similar to  FIG. 13  but showing another embodiment of the ridge-like projection  28  and contiguous paint film arrangement;  
         [0030]      FIG. 15  is a view similar to  FIG. 13  but showing yet another embodiment of the ridge-like projections and continguous paint film;  
         [0031]      FIG. 16  is a view similar to  FIG. 13  but showing yet another embodiment of the ridge-like projections and contiguous paint film; and  
         [0032]      FIG. 17  is a view similar to  FIG. 13  but showing yet another embodiment of the ridge-like projections and contiguous paint film. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]     Turning now to  FIG. 1 , there is shown an automotive part  2  in accordance with the invention. Here, the show surface of the part is depicted. The show surface comprises one color imparting member  4 , namely a paint film laminate overlying an exposed portion  6  of the substrate plastic material. Separating the paint film laminate  4  from the exposed substrate  6  are boundary members  8 ,  10 , and  15 . These members are formed as channels in the substrate, and edge portions of the paint film laminate  4  are disposed in these channels.  
         [0034]     In this way, the color boundary existing between the paint film laminate  4  and exposed substrate  6  presents an even, aesthetically pleasing appearance on the show side of the part. In contrast to the situation wherein a laminate is directly laid over the substrate with no boundary channels, the part of the present invention provides for a sharper, more distinctive color boundary interface. As shown in  FIG. 1 , channels  8  and  10  are substantially parallel and are connected to each other by the provision of a generally semi-elliptical or semi-circular configured connecting channel  15 .  
         [0035]     Turning now to  FIG. 2 , a cut-away perspective view of a portion of the part shown in  FIG. 1  is depicted. Here, the longitudinal edge portions of the paint film  4 , namely edges  12  and  14 , are clearly disposed within the channel members  8  and  10 , respectively. Thus, the boundary existing between the paint film  4  and exposed substrate  6  again provides an aesthetically pleasing appearance since the edges  12 ,  14  are tucked or disposed within the channels along the color interface borders. A core  400  is centrally located in the part and extends along most of the length of the part. The core may be formed in conjunction with normal gas assisted molding techniques. For instance, after the plastic has been injected into the mold in the insert molding technique, a shot of pressurized gas may be admitted through the sprue or other entry means to hollow or “core-out” the part. The artisan may review U.S. Pat. No. 5,639,405, incorporated by reference herein, to glean details pertaining to optimized methods for forming the hollowed-out sections or cores.  
         [0036]      FIG. 3  shows a mold apparatus  16  of the type that may be utilized to make the part shown in  FIG. 2 . Here, mold apparatus  16  comprises a mold cavity  24  that is defined by male mold member  22  and female mold member  18 . As shown, the mold cavity opens along parting line  26 . Depending from the surface of the male mold member  22  are a pair of ridge-like projections  28 ,  30 , extending into the mold cavity from the male mold surface. These projections are necessary in order to make the boundary channels  8 ,  10  in the substrate upon the insert molding step. Gate  20  is provided for entry of thermoplastic or thermoset material into the mold cavity.  
         [0037]      FIG. 4  shows the mold cavity of  FIG. 3  in the insert molding stage wherein the mold cavity is supplied with thermoplastic or thermoset substrate material  6 , and the paint film laminate  4  is disposed over the substrate on the show side of the part. Here, it can be seen that the longitudinally extending edges  12 ,  14 , of the paint film laminate are placed securely in between projections  8  and  10  of the male mold cavity. In this way, the paint film  4  is held snugly in place during the molding process and, upon ejection of the part from the mold, these edge portions are disposed in the respective boundary channels  8 ,  10  that are found in the part (see  FIG. 2 ).  
         [0038]     Turning now to  FIG. 5 , there is shown another embodiment of the invention wherein the show surface of the automotive part  102  comprises a bi-component or two-color combination. Here, one of the components is the paint film  104  with the exposed substrate  106  being shown on the far show side of the part as appears in  FIG. 5 . Note here that one of the longitudinally extending edges  112  of the paint film laminate is disposed in the longitudinally extending border channel  108 , which channel extends longitudinally along the substrate material. The other longitudinally extending edge  113  of the laminate covers the corresponding longitudinal edge  115  of the part in accordance with the procedures described in U.S. Pat. Nos. 5,746,962; 5,599,608 and 5,783,287.  
         [0039]      FIGS. 6 and 7  show cross-sectional views of the mold cavity utilized to make the part shown in  FIG. 5 . Here, it can be seen that a ridge-like projection  121  is provided in the male mold cavity so as to form, upon molding, the border channel  108  shown in the part of  FIG. 5 . As shown, edge  112  of the part is disposed within this border channel  108  that extends longitudinally along the axis of the part.  
         [0040]      FIG. 8  shows another embodiment of a paint film laminate that may be utilized in accordance with the invention to provide a plural color arrangement over the exposed substrate area of the part. Here, the paint film laminate  200  comprises a first color section  202  located intermediate additional color sections  204 ,  206 . It can be well understood that individual colors could be imparted for each of the sections  202 ,  204 ,  206 , or, as presently preferred, the portion  202  has a first main color with the smaller area sections  204 ,  206  being supplied with a second color.  
         [0041]     The techniques employed to form the part shown in  FIG. 2  are then employed in conjunction with the paint film laminate  200  to provide the part shown in  FIG. 9 . That is, the mold cavities depicted in  FIGS. 3 and 4  are simply utilized in conjunction with the second paint film laminate embodiment of  FIG. 8  to make the part shown in  FIG. 9 . The additional color sections  204 ,  206  are provided with intermediate color section  202 ; all of which are disposed on top of the substrate  216 . Accordingly, the colors presented by this part include the substrate color  216 , the first color  202  and its bordering colors  204 ,  206 . As mentioned previously, it is presently preferred that the colors  204 ,  206  match. Here again, the sections  204 ,  206  of the paint film laminate are tucked within the corresponding boundary channels  208 ,  210  formed in the part.  
         [0042]      FIG. 10  shows another embodiment similar to that shown in  FIGS. 2 and 9 . Here, a single color paint film laminate  304  may be provided with the longitudinally extending ends  312  and  314  thereof disposed in channel boundary  308 ,  310 . Additionally, so as to impart a different appearance or different color pattern, colored rope-like strands or extrusions  322 ,  324  are also disposed snugly or wedged within the boundary channels  308 ,  310 . The use of the strands  322 ,  324  not only serves the purpose of providing additional aesthetic enhancement for the show surface of the part, but the resilient nature of the strands helps to hold the laminate  304  firmly in place. These strands may comprise, for example, circular or oblong cross-sectional extrusions, or textile filaments and the like adapted for snug reception in the grooves or channels.  
         [0043]     In  FIG. 11 , there is a variation of the part depicted in  FIG. 2 . Here, in the molding process, the paint film laminate itself is wider than that shown in  FIG. 4 . This results in the ends  12 ,  14  of the laminate being embedded deeply within the plastic matrix  6 . Stated differently, the ends  12 ,  14  extend below the ridge-like projections  28 ,  30  formed in the male mold surface so that these ends are embedded in the plastic matrix beneath the nadirs of the channels  8 ,  10 . As shown, the edge extends along the inboard wall of the channels and is buried in the plastic matrix at a location beneath the nadirs of the channels.  
         [0044]     Similarly, in the embodiment shown in  FIG. 12 , the paint film laminate is wider than that shown in  FIG. 4 , but here the ends  12 ,  14  of the laminate extend below the projections  28 ,  30  and are upwardly curved to wrap around these projections. In order to provide this structure, it is desired to preform the paint film so as to have the upwardly curled edges in a vacuum preforming operation.  
         [0045]     The embodiment in  FIG. 12  provides an aesthetically pleasing appearance for the part. At the same time, the edges of the laminate in the molded part will be secure in position as they pass around or are wrapped around the nadir of the channels  8  and  10  and are embedded in the upstanding outboard wall of the generally two-walled or U cross-sectioned channels.  
         [0046]     Although the paint films herein described have been noted as having colored sections, the use of metallic flake containing films having aluminum or gold or often metallic appearances can also be used to provide class “A” show parts. One popular film provides a chrome-like appearance and may also be used in accordance with the invention as the member  4 . Thus, such metallic-type finishes are to be construed as within the ambit of the invention, and the phrases “paint film,” “paint film laminates,” “film laminate,” and “film” are used interchangeably and also include these metallic finishes within their intended construction.  
         [0047]     Turning now to  FIG. 13 , it can be seen that the ridge-like projection  28  and congruent channel member  8  have a cross-sectional configuration in the form of a substantially “U” shape. Laterally opposed upstanding sides of the channel are shown as  602 ,  604  with these outboard and inboard sides interconnected at the bottom or nadir of the channel by a radiused connected leg  606 . As shown, the end  12  of the film, in this embodiment, extends downwardly along one of the laterally opposing walls or sides of the channel, covering the entire nadir of the channel juxtaposed along the connecting leg of the projection and then turns upwardly along the outboard upstanding wall of the channel.  
         [0048]     In the embodiment shown in  FIG. 14 , the projection and congruent groove are in the shape of a squared channel wherein laterally opposed upstanding sides  602 ,  604  are substantially parallel to each other, with each joined to the connecting leg  606  at a normal angle. Here, the end  12  of the film is wrapped around the squared legs of the groove and extends upwardly along the upstanding outboard leg  602  of the groove that is along the outboard groove side.  
         [0049]      FIG. 15  shows yet another embodiment wherein legs  602 ,  604  are positioned in the form of two sides of a triangle, converging at the channel or vertex  608 . The film here extends along the inboard edge of the groove, dips into the vertex, and then the end  12  terminates upwardly along the outboard upstanding leg  602 .  
         [0050]     The artisan will appreciate that a myriad of possible cross-sectional configurations for the ridge-like projections and congruent channels formed in the part may exist.  
         [0051]     Another embodiment is shown in  FIG. 16  wherein the end  12  of the film terminates at the bottom or nadir of the channel. In contrast, in  FIG. 17 , the end  12  of the film passes around the nadir and extends laterally along a substantially linear tangent generally parallel to the nadir and at a substantially normal angle to the longitudinal axis of the ridge  28 .  
         [0052]     It is apparent that the methods herein referred to result in the provision of an automotive part which includes a plastic substrate having a show surface with a paint film laminate disposed over a portion of the show surface of the part to reveal a portion of the substrate on the show surface. In order to manufacture such a part, a mold cavity is provided that has a surface area thereof interrupted by a ridge-like protrusion. The paint film laminate is positioned in the mold so that an edge of the paint film laminate is disposed alongside of the ridge-like protrusion in the mold cavity. Upon injection of the molten thermoplastic or thermoset into the mold cavity and behind the paint laminate, the molten plastic extends under the paint film alongside the ridge-like protrusion. This ridge-like protrusion upon contact with the paint film laminate and the molten plastic forms a channel in the molten plastic with the edge of the paint film laminate tucked into this channel. If desired, the part may be “cored-out” or provided with a hollowed cross section by injection of pressurized gas into the cavity, normally at a time after the plastic melt has been injected.  
         [0053]     In the preferred method, the mold cavity comprises a surface area that is interrupted by a first and second ridge member with those ridge members being separated by a space extending along the mold cavity surface. The paint film laminate comprising a pair of edge portions is positioned in that space with each of the opposing edges of the paint film laminate disposed adjacent one of the ridge members. Upon injection of the molten plastic or thermoset into the mold cavity and behind the paint film laminate, the molten plastic extends under the paint film laminate along the space and the ridge members. These ridge members, upon contact with the molten plastic and the paint film laminate, form a pair of channels in the molten plastic with each of the respective edge portions of the paint film laminate tucked into one of these channels.  
         [0054]     Although the instant invention emphasizes use of a single paint film piece, the skilled artisan will readily appreciate that a plurality of separately colored plastic strips or the like may also be employed with the associated insert portions extending longitudinally along each said strip firmly anchored in the plastic substrate in a groove or channel member similar to the groove  8  shown in  FIG. 1 .  
         [0055]     Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the appended claims.