Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Utility Patent
1998-02-17
2001-01-02
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S267000, C264S269000, C264S275000, C425S127000, C425S129100
Utility Patent
active
06168742
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to an improved method of insert molding of a laminated film or the like over a plastic substrate to produce a part such as a bumper, chin spoiler or rocker panel for an automobile or truck.
BACKGROUND OF THE INVENTION
A variety of injection molded parts have been made and used for auto or truck body and trim parts. For example, bumpers, body panels, doors, filler panels, wheel covers, dashboards, arm rests and other parts have been made via injection molding techniques. Additionally, with regard to automobile exteriors, body side moldings, beltline moldings, roof moldings and window moldings are made via injection molding of thermoplastic olefin (“TPO”) or acrylonitrile-butadiene-styrene copolymer (“ABS”) or from other thermoplastic materials.
In order to provide a painted surface for these parts, film lamination techniques have been successfully employed. In accordance with these processes a paint film laminate is insert molded with the desired thermoplastic to fuse the film over the injection molded part. The resulting injection molded part is ready for assembly without subsequent painting.
The paint film laminate used in these insert molding techniques may comprise a backing sheet of about 0.020″ in thickness to which paint layers are adhered. 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 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, including base coat, clear coat and print or design, if desired, may range from about 0.5-4 mil. in thickness.
The laminated paint films are available, for example, from Avery Dennison, Decorative Films Division, Schererville, Ind., or Rexham Decorative Products, Charlotte, N.C. The 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. In some instances, the preform 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 occurs. Injection molds used for these processes are rear or edge gated so that the molten resin is directed along the backside of the film. The process leads to a finished plastic part with the paint film fused over the underlying plastic substrate. The painted or decorative side of the paint film laminate is exposed over the surface of the substrate to exhibit the desired aesthetic appearance.
It has become increasingly popular to insert or co-mold bumper, rocker panel, and chin spoiler parts for autos and trucks. Conventionally employed co-molding techniques however often result in the unsightly disposition of one of the paint film laminate edges over the substrate plastic in such manner that the laminate edge is exposed on the surface of the part and presents an uneven or non-uniform border with the plastic substrate material. This not only detracts from the physical appearance of the edge, but the exposed edge then serves as a site for peeling back and eventual separation of the film laminate from the underlying substrate.
Furthermore, the border between the film laminate and plastic substrate may have a wavy or uneven appearance. This may be caused by non-uniform dimensions or shrinkage of the paint film laminate during molding.
Accordingly, there is a need for a method for co-molding bumper, rocker panel, and chin spoiler parts wherein a uniform border is provided between the film laminate and plastic substrate. There is a more specific need for a method in which the paint film edge is located in a recess or relief area so that it can not be readily peeled back from the underlying substrate. Additionally, there is a need for a manufacturing process that will place the laminate-plastic border on the far or remote side of a raised area of the plastic part so that it will be hidden from sight and not normally seen from the vantage point of an ordinary observer.
SUMMARY OF THE INVENTION
These and other objects of the invention are met by the instant methods and fused film-plastic parts made thereby.
Briefly, improvement in traditional insert molding techniques is provided so as to provide for bumper, chin spoiler or rocker panel-type parts having Class A show surfaces. A specifically configured mold cavity structure is provided to facilitate formation of a uniform sight edge in the paint film laminate adjacent the boundary between the paint film laminate edge portion and the underlying plastic substrate. This results from provision of a surface discontinuity in the mold and corresponding part.
In one form of the invention, this discontinuity comprises a ramped or inclined concave cavity surface portion along a mold cavity surface for which the formation of the uniform sight edge is provided. The film edge is positioned along the ramp, short of the nadir of the concavity. Upon molding, the film edge is positioned in the recessed part portion formed, in the mold, adjacent the concavity.
In a preferred form of the invention, the film laminate edge is positioned over the apex of a convex ramp formed in the mold cavity. Upon molding, the film edge is formed in the part adjacent the convex ramp of the mold cavity. The paint film edge is positioned over the apex of the ramp remote from the viewer's vantage point. In this way, the viewer will see only the film covered ramp side facing him or her.
The invention will be further described in conjunction with the appended drawings and detailed description.
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patent
Biebel & French
Green Tokai Co. Ltd.
Lee Edmund H.
Vargot Mathieu D.
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