Abstract:
A window trim molding having improved adhesion between the edges of the window and the window-gripping portions of the molding. This is accomplished by co-extruding with the principal molding material, a second material which is a thermoplastic polyurethane, on the window-gripping portions of the molding. A conventional adhesive is applied to the window edges, and the second elastomeric material acts as an adhesive promoter compatible with the adhesive.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a window trim molding, also known as a “reveal molding” or “lace”, for gripping and retaining the outer periphery of a fixed window, such as a windshield, rear window or fixed side windows of an automotive vehicle. The molding conceals the space between the edge of the window and an adjacent body pane 
     PRIOR ART STATEMENT 
     It is standard procedure to promote the gripping of the edges of the windows by molding members, utilizing adhesives. Normally this is accomplished by applying a bead of an adhesive material to the edges of the upper and lower planar surfaces of the window glass, or to the vertical edge of the glass which extends between the planar surfaces, then applying a liquid primer material to part of the window-gripping portions of the molding. The primer is usually a blend of methyl ethyl ketone, toluene, and methyl methacrylate. 
     SUMMARY OF THE INVENTION 
     The present invention provides for an improved molding in which the adhesion between the molding and the window edge is greatly improved and overcomes certain drawbacks of the above-described system which uses a liquid primer material; for instance: 
     1. The prior art primer is composed of materials which may be hazardous because of their toxicity and potential fire hazards. 
     2. The application of this material to the surfaces of the flexible molding creates difficult handling problems, leading to inconsistency in application, whether by brushing, wiping, or similar processes. 
     3. The primer material is affected by aging and by evaporation of some of the components, thus affecting the viscosity and effectiveness of the material. 
     4. It is necessary to provide special equipment for controlling the fumes of the primer, and for drying it after the application to the surfaces of the molding. 
     5. When inspecting the molding for quality control after the primer is applied, it is difficult to detect the primer coating. 
     6. The shelf life of the primer is very short, usually a maximum of 90 days, so that moldings which have been stored for future application, particularly for after-market use, may lose their effectiveness. 
     7. Because of the difficulty in handling referred to above, some of the primer material may overflow the gripping surfaces of the molding and stain the outer visible surface, leading to an unsightly appearance or a high scrap rate. 
     All of the above problems are eliminated by the present invention; rather than applying a liquid primer during extrusion or after fabrication, as in the prior art, an adhesion promoter is co-extruded with the molding and provides superior results. By using a thermoplastic polyurethane as a co-extruded material on the inner window edge-contacting surfaces, the typical problems are eliminated and a better but less expensive product results. The handling of hazardous materials and the short shelf life problems are eliminated. In addition the promoter may be colored to make its presence more easily detected. 
     Therefore it is a principal object of the invention to provide an automotive window molding which has improved window gripping features. 
     It is an additional object to provide a molding that is more consistent in its construction. 
     It is another object to provide a molding having an increased shelf life. 
     It is a further object to provide such a molding by a simplified process which is safer and less costly. 
     These and other objects and features will become apparent from the embodiments described and shown herewith. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a typical automotive vehicle illustrating various locations of the novel molding. 
     FIG. 2 is an enlarged sectional view taken along line  2 — 2  of FIG. 1 illustrating a typical installation of the molding on the window. 
     FIG. 3 is an enlarged detail of a portion of the novel molding and a portion of an associated window, prior to installation on the window and the vehicle. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIG. 1, the automobile  11  is typical of a motor vehicle which contains, among other parts, a fixed rear window  12 , fixed side windows  13 , and the windshield  14 . The novel molding  15  is manufactured as a continuous strip and extends around the entire periphery of the rear and side windows, as well as the upper and side portions of the windshield. As shown in FIG. 2, the rear window  12  is typical of all the fixed windows, and is attached to the adjacent body panel  16  by means of an adhesive  17 , or by other means known in the art, such as referred to in U.S. Pat. No. 5,338,087, issued to Gross et. al. (of common assignment). The molding  15  is principally composed of an elastomeric material such as polyvinyl chloride, having a hardness of about 80 to 90 Shore “A”, which is the material commonly used in the manufacture of moldings, and which may contain filler material. The main body  18  extends over the body panel and the edge of the outer planar surface of the window and thus conceals the space between the body panel and the edge of the window. The outer surface  19  of the body  18  is visible from the exterior of the vehicle. The body  18  comprises an outer leg or segment  20  and an inner leg  21 ; these legs cooperate to grip the outer edge of the window. The term “edge” collectively consists of the outer portion of the upper planar surface  22 , the outer portion of lower planar surface  23 , and the vertical surface  24  which extends between the upper and lower planar surfaces. The body  18  further comprises a stem section  25  which contacts the surface  26  of the body panel. In order to adhere the molding to the window edge, a bead  27  of thermoset polyurethane, approximately 0.025 to 0.050 inch thick is applied to the vertical surface  24  of the window edge, as shown in FIG.  3 . But instead of applying a liquid primer as an adhesion promoter to the inner surfaces of the legs  20  and  21  as in the prior art, the promoter is applied in the form of a second elastomeric material  28  which is co-extruded with the principal material as a layer on the window edge-contacting portions of the legs  20  and  21  and the stem section  25 . This co-extrusion is done in a manner well known in the art, as shown for example in U.S. Pat. No. 5,311,711 issued to Desir, Sr. 
     The second elastomeric material  28  is a thermoplastic polyurethane (TPU), which is well-known in the industry, and is sold under various trade names. This material has a thickness between 0.005 and 0.020 inch, and becomes unitary with the primary material so that the entire molding is monolithic. The juncture of the principal material and the second material is shown in dash lines. The second elastomeric material extends along the inner surface of the leg  20  and has a window edge-gripping surface  29  which contacts the upper planar surface  22  of the window edge; the second elastomeric material  28  also extends along the inner surface of leg  21  to form window gripping-surface  30  to contact lower planar surface  23  of the window edge; and the second elastomeric material  28  extends along the inner surface of the stem section  25  to form a window contacting surface  31  that contacts the vertical surface  24  of the window edge. The legs  20  and  21  and stem section  25  thus form a channel which is placed over the window edge. Pressure of the channel causes thermoset polyurethane bead  27  to spread around the window edge to the position show in FIG. 2 to form a layer of about 0.010 to 0.020 inch thick. It should be understood that the extent of the spreading of the thermoset polyurethane material may depend on the amount of material which is applied. It is also understood that optional methods of applying the thermoset polyurethane include caulking, pumping, or wiping a thin coating along any portion of the edge, whether planar surfaces or vertical surface thereof; or applying directly to the molding itself. It is also possible to limit the extent of the second elastomeric material to a portion only of the inner surfaces of the legs or the stem section. Whichever method is used, at least some of the window gripping surfaces  29 ,  30  and  31  of the material  28  will promote adhesive contact with the thermoset polyurethane material  27  to create improved adhesion of the molding to the window edge. The resulting product provides the many advantages set forth under the summary of the invention. 
     The above embodiment is exemplary but other modifications thereof are within the scope of the invention.