Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Reexamination Certificate
2000-02-11
2002-11-05
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
C264S513000, C264S547000, C264S553000, C264S255000, C264S257000, C264S267000, C264S296000, C425S127000, C425S129100, C425S387100, C425S388000
Reexamination Certificate
active
06475423
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to molding processes and articles molded thereby and, more particularly to an improved molding process in which decorative films are formed with the forming of the article to enhance the cosmetic appearance thereof.
Injection molding is used widely to produce numerous articles. These articles range from articles with simple configuration such as plates, light switches and the like to more complex molded shapes, such as wire less telephone housings. These molded articles often need to be decorated to enhance their visual appeal and their saleability. Some such articles may be decorated in the simplest sense of the term, by either adding pigments to the pellets of plastic used in the injection molding process or by using colored pellets to mold the article. Although these two methods are effective for coloring the molded article, they result in solid coloring of the article and are ineffective in forming any complex decorative appearance to the molded article.
Some other processes are known in the injection molding art for decorating molded products. One such process involves the use of stamping or otherwise applying a foil layer to the exterior of the molded product. In this process, the foil is applied to the molded article after the article is molded and ejected from the molding machine. This metal foil is thin and is prone to breakage on sharp corners and complex curves of the molded article. Registration problems are also encountered with this process.
Another process for decorating molded articles involves the use of “pad” printing in which colors or designs are applied to the molded article after molding, by way of one or some more printing pads. These pads are formed of foam rubber or other pliable material and have one or more inks deposited on their exterior surfaces, which are subsequently applied to the molded article. Problems exist in that the pad may not contact all the intended surfaces of the article and thus may not accurately apply the ink(s) to all surfaces, especially complex surfaces of the molded article. Similarly, the exterior surface of a molded article may serve to frustrate the use of screen printing the molded article. Hydrographics, the use of floating a decal in water and then applying it to the molded article, has its own limitations in that the decals are prone to tearing and there exist great difficulties in accurately registering the decals in place on a complex molded article.
In-mold decorating is yet another process that has been used to decorate injection molded articles. This process involves introducing a decorative film into the mold cavity. However, the film is delicate and fragile. It also has registration problems with complex molded articles inasmuch as the film inserted into the mold cavity is die cut. The walls and surfaces of the mold cavity are used for registration of the film in the mold cavity, and the mold cavity may not be modified to create any registration means. As such, this process is effectively limited to application to flat surfaces in the mold and on the final molded article, such as label recesses. It also cannot provide any details along the z-axis of the mold cavity or along the sides of the finished molded article.
A still further process involves the use of a decorative “preform”, where an outer, decorative shell is formed complying to the configuration of the final molded article and it is inserted into the mold cavity prior to the injection of liquid plastic or other molding material into the mold cavity. The shape of this preform must conform accurately to the final configuration of the molded article. Where openings are molded into the article during the molding process, registration between the preform and the mold cavity must be critically maintained. Thin wall portions of the preform may result in leakage of the injected melt and problems with the finished article, leading to high rejection rates.
The process cannot accommodate the application of a fabric to a molded surface. A need therefore exists for an improved molding process for decorating the surfaces of a molded article that complements the usual operational parameters of the molding process and which overcomes the aforementioned disadvantages of the prior art. The present invention provides an improved injection molding process in which fabric may be applied to a molded article during the injection cycle of the molding process.
SUMMARY OF THE INVENTION
The present invention is therefore directed to a molding process in which a decorative film is applied to the exterior surface of a molded article.
Accordingly, it is a general object of the present invention to provide an improved molding process in which a decorative film is formed onto the exterior surface of a molded article during the actual molding thereof.
Another object of the present invention is to provide a hybrid injection molding process in which a decorative film is first prepared and subsequently intimately attached to a molded article by drawing the decorative film into a mold cavity, injecting a liquid melt into the mold cavity so that an intimate attachment results between the molded article and its associated decorative film.
Still another object of the present invention is to provide an improved molding process in which a film sheet is decorated with a preselected decorative pattern is applied in registration with a mold cavity, the film sheet is heated and drawn into the mold cavity by negative air pressure so that the film sheet is in contact with substantially all of the mold cavity interior surfaces, and a liquid melt, typically a liquid plastic, is injected into the mold cavity so that it entirely fills the mold cavity and contacts the film sheet so that when the liquid melt is cooled and the article is ejected from the mold cavity, the film sheet is intimately attached to the molded article.
Yet another object of the present invention is to provide a molding process for forming decorative molded articles that includes the following steps: modifying a mold cavity, preferably the core side, to include registration means for maintaining a decorative film sheet in registration with the mold core cavity; applying the decorative film sheet to the mold core cavity; softening the decorative film sheet; applying negative air pressure to at least a portion of the mold core cavity to drawn the decorative film into the mold core cavity and at least into partial contact with the surfaces of the mold core cavity; bringing an opposing mold detail member into engagement with the mold core to form a final mold cavity; and, injecting a liquid molding compound into the mold cavity under pressure to form a molded article, the decorative film sheet being bonded to the molded article along substantially all of the exterior surfaces of the molded article.
A still further object of the present invention is to provide a molding machine for performing a hybrid molding process in which a decorative film sheet is drawn into one of two coacting mold blocks in order to contact the interior surface of the one mold block, and a heated molding compound is injected under pressure into the mold cavity so that the decorative film sheet becomes bonded to the molded article, the molding machine having means for holding the film in place over one of the two mold blocks and in registration with the mold cavity of the one mold block, the machine further having means for drawing the decorative film sheet into the one mold block through the cavity of the one mold block and means for maintaining the film sheet in place during injection of molding material into the mold cavity.
A yet still further object of the present invention is to provide a unique molded article having a body portion and an exterior decorative portion, the two portions of the molded article being intimately attached to each other.
Yet a further object of the present invention is to provide a decorative sheet for insertion into a mold cavity and subsequent attachment thereof to
Masterson Vincent
Matecki Mark
Lee Edmund H.
Silbaugh Jan H.
Slipmate Company
Vedder Price Kaufman & Kammholz
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