Coating processes – With post-treatment of coating or coating material – Solid treating member or material contacts coating
Reexamination Certificate
2001-04-06
2004-08-03
Chen, Bret (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Solid treating member or material contacts coating
C427S256000, C264S129000
Reexamination Certificate
active
06770324
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to coatings, and more particularly to protective coatings and methods of forming such coatings.
BACKGROUND OF THE INVENTION
A large number of coatings exist for protecting surfaces on a wide variety of industrial and commercial products, many of which present challenges to a satisfactory coated end product. A problem that is common to many applications arises as a result of the flexure or deformation of a coated surface. A protective coating on a surface that is flexible or is subjected to deformation is generally more likely to fail, whether by losing adherence, peeling, cracking, or otherwise exposing some or all of the underlying surface, by wrinkling or buckling, by developing coating areas that are stressed or weakened, and the like. A number of these problems can occur in the relatively new technology of in-mold decoration (IMD). Generally speaking, IMD is the application of text, a pattern, or graphics to a molded part as part of the molding process.
A popular type of IMD process employs the use of insert molding in which a formable film is layered with a protective coating on one side (referred to as the “first” side or surface), and is printed with text, a pattern, or graphics on an opposite side (referred to as the “second” side or surface). With reference to
FIG. 1
, which illustrates a conventional IMD process in flowchart form, the film is first printed or “decorated” with the text, pattern, or graphics in a conventional manner, such as by silk-screening or other types of printing. The film can be decorated on both first and second surfaces, but is commonly decorated on only the surface that is not exposed to wear and the environment (the second surface in many cases). The fact that the text, pattern, or graphics is printed on the opposite (second) side of the film also protects the text, pattern, or graphics from such potentially damaging exposure. Because the film is typically light-transmissive, second-surface decorations will be visible through the film after the product is completed. The first surface is exposed to wear and the environment, and so may need protection from scratches, abrasion, fluids, and the like. Therefore, the first surface is coated with the protective coating. The hardcoat is left uncured so that it can be formed with the film later in the process.
With continued reference to
FIG. 1
, after the decorations and protective coating have been applied to the surfaces of the film as just described, the film is formed into a desired shape in one of several conventional manners. For example, the film can be vacuum thermoformed, pressure formed, hydroformed, matched metal formed, etc. Considerations in the type of forming operation selected include the amount of film shaping to be performed (referred to as the amount of “draw” needed for the desired final shape, such as a deep draw or shallow draw), and the extent to which the forming operation will damage or affect the protective coating. It is this latter consideration that presents significant problems in conventional IMD processes. Specifically, conventional protective coatings typically need to be cured to achieve their strong and wear-resistant properties. However, once cured, these same properties largely limit the ability of these protective coatings to be stretched, bent, compressed, or otherwise formed without damage. While this is not normally a problem with protective coatings upon a final product, it is a significant problem in the film forming operation described above. Therefore, protective coatings are typically left uncured in conventional IMD processes until after the film forming process.
Although the uncured protective coating can be easily shaped without sustaining damage, it is relatively delicate and susceptible to scratching, marring, impressions, and the like. By way of example only, such damage can occur as the film is being taken out of the printing and coating machinery, when the film is stacked upon other films for transport or otherwise, during movement and handling of the film from the printing and coating machinery to the molding machinery, when the film is inserted into the molding machinery, during the molding operation, when the film is removed from the molding machinery, and during movement and handling of the film from the molding machinery to a location where the protective coating is cured.
In order to protect the uncured protective coatings from damage, special procedures are commonly used, such as restrictions on the amount of film stacking, protection of the film from exposure to light and heat (many protective coatings are cured by exposure to ultraviolet light and/or heat), procedures for particular care in handling the films, and the like. In addition, the ability of many forming operations and machinery to damage the uncured protective coating limits the types of operations and machinery that can be used. The special handling procedures and the inability to employ many types of machinery and processing operations just described represent significant limitations of conventional protective coatings and affects the entire IMD process. These limitations inevitably increase the inefficiency and cost of production of the IMD process and therefore of the end product.
Even with special handling procedures and the use of specific machinery to avoid protective coating damage, the delicate uncured protective coatings inevitably increase the scrap rate of films and the products made with such films. In some cases, even a small number of scrapped films can significantly impact production costs.
Yet another limitation of conventional protective coatings is related to their resulting appearance and performance, and is independent of whether the surface provided with the protective coating is later molded or otherwise shaped. In this regard, it should be noted that conventional protective coatings are commonly applied to a number of different surfaces that are not later molded or otherwise shaped. Although a number of conventional protective coatings are strong and wear resistant, the ability of a manufacturer to control the appearance of the final coated product can often be quite limited. Protective coatings that can be opaque or transparent and that can have a range of glossy, matte, and textured finishes are highly desirable, but are normally not available in one conventional protective coating.
In light of the problems and limitations of the prior art described above, a need exists for a protective coating that can be employed in IMD processes, is strong and wear-resistant, can be cured prior to forming operations of the underlying substrate, is sufficiently flexible and formable after curing to withstand such forming operations without damage, enables the use of a wider variety of molding machinery to form the underlying substrate, reduces the chances of coating damage during substrate printing, handling, transport, and molding processes, reduces scrap rates and production costs, can be transparent or can be partially or fully opaque, and can have a range of finishes (from glossy to matte and a range of textures). Each preferred embodiment of the present invention achieves one or more of these results.
SUMMARY OF THE INVENTION
In some preferred embodiments of the present invention, a protective coating is preferably formed as a plurality of dots on a substrate or object which is desired to be protected. As described in greater detail below, the dots can be any shape, can have the same or different shapes, and can be in any density and in any pattern (or no pattern) on the substrate or object. Preferably, the dots are isolated or substantially isolated from one another by uncoated surfaces of the substrate or object, thereby not only providing the substrate or object and the coating with significantly increased cured flexibility and formability, but also with a wide range of possible surface finishes and textures.
Due to the increased flexibility and formability of some embodiments of the protective coating
Chen Bret
Fletcher, III William Phillip
Kennedy Acquisition, Inc.
Price Heneveld Cooper DeWitt & Litton LLP
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