Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
2000-11-06
2004-06-15
Kiliman, Leszek B. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of metal
C428S423100, C428S425500, C428S425800, C427S330000, C427S348000, C427S352000, C427S353000, C427S356000, C427S358000, C427S368000, C427S363000, C427S377000, C427S378000, C427S409000, C427S410000
Reexamination Certificate
active
06749946
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for depositing a polymer film on a metal surface, and more particularly to a process for applying a durable urethane film to a metal surface.
BACKGROUND OF THE INVENTION
Traditional chrome plating creates a smooth, bright chrome finish. It has long been desired to have other finishes, such as black chrome, gold-tinted chrome, and other tinted or colored metallic finishes for decorative purposes. More specifically, there is a desire for clear polymeric decorative coatings that allow the brightness and luster of chrome plating to be seen, while modifying the appearance by imparting a color or tint to the chrome plating.
Several methods have been used in an attempt to achieve colored metallic finishes. One method involves electroplating, wherein black chrome and bronze finishes can be created. A problem with the electroplating methods is that it is very difficult to consistently obtain a desired colored metallic finish. Another disadvantage with the electroplating techniques is that they are generally limited to black and bronze colors or combinations thereof.
Another method that has been used for obtaining colored metallic finishes involves physical vapor deposition (PVD). This method offers a wider variety of colors than the electroplating method. However, physical vapor deposition is very expensive, and therefore, its use for achieving a desired colored finish is extremely limited. Another problem with physical vapor deposition is that it is difficult to control the gloss of the finishes.
Another method that has been attempted for obtaining colored metallic finishes involves applying transparent organic polymer coating containing a dye, pigment or other colorant on a chrome-plated substrate. This method is convenient, and offers a very wide variety of color finishes. However, the use of organic coatings on chrome-plated substrates has been extremely limited due to poor adhesion between the organic coating and the chrome surface, especially after prolonged exposure to extreme temperature and/or humidity. Even organic polymer coating compositions which initially exhibit good adhesion have not exhibited adequate adhesive durability for most product applications. As a result, this technique has not been applied to automotive, electronic, or other durable consumer goods.
A process for adhering a relatively thick layer, e.g., 5 millimeters, of polyurethane elastomer to a metal, such as steel, iron or aluminum, is disclosed in U.S. Pat. No. 4,542,070. The process involves coating the surface of the metal with a primer composition containing a polyepoxy compound and a polyamine compound, further coating the surface with a composition containing an isocyanate compound having an isocyanate group concentration of 15-50% by weight, and casting a layer of polyurethane elastomer onto the double coated surface of the metal followed by hardening the whole system. A silane-coupling agent may be added to the primer composition to improve adhesive properties and water resistance. Disclosed examples of silane-coupling agents include gamma-glycidoxypropyltrimethoxysilane and gamma-aminopropyltriethoxysilane. Color pigments may be added to the composition. Solvents that may be used for the primer composition are those which dissolve both the polyamine compound and the polyepoxy compound, with examples including toluene, xylene, ethylbenzene, methylethylketone, methylcellosolve, ethylcellosolve and acetate esters of a cellosolve compound. The polyurethane elastomer is used to improve the durability of steel, iron and aluminum surfaces of metal articles.
SUMMARY OF THE INVENTION
In the present invention, a clear polyurethane film is adhered to a bright metal surface using a primer containing a silane-coupling agent. The polymer film may contain a coloring or tinting agent that modifies the perceived color of the underlying chrome surface.
The invention offers a process of creating unique surface finishes on chrome-plated substrates. More specifically, the process provides an economical way of creating surface finishes similar to black chrome, PVD finishes, and other colored metallic finishes, such as blue, red, green, yellow, etc. The colors and the gloss level can be varied as desired. The process employs an adhesion enhancer that can be applied as a primer or as an additive to a polyurethane composition. The adhesion performance between the chrome surface and the film is improved so that both the film and the adhesion between the film and the chrome plating are durable enough for practical applications such as in the automotive industry and in electronic devices such as cellular phones.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with a preferred embodiment of the invention, a clear, hard polyurethane polymer film is deposited on a chrome plating by first applying an aqueous primer composition to the chrome plating, and applying a two part urethane composition over the primer composition. The primer composition is comprised, and more preferably consists essentially of, water, methanol, and a silane-coupling agent. The primer composition may be applied to a bright metal surface by spraying, dipping or wiping techniques. Preferably, the bright metal surface is cleaned prior to application of the primer composition. The applied primer composition is allowed to dry. After the primer composition has dried, a liquid urethane composition is applied over the dried primer composition, and is allowed to cure. The urethane composition can be applied by any of various techniques, including spraying, dipping or wiping techniques, with spraying being preferred. A suitable thermal cure can be achieved in about 60 minutes at 180° F. (about 82° C.).
The polyurethane films of this invention generally have a thickness of from about 5-200 microns, more typically from 10-100 microns, and preferably from 20-50 microns.
Although a desirable aesthetic finish can be achieved without pigments or dyes, the two-part urethane composition preferably includes a dye, pigment or other colorant or a mixture of colorants to create a desired tinted film.
The urethane composition may be either a one-component urethane system, or preferably a two-component urethane system. A two-component urethane system is a urethane system in which the isocyanate and polyol components are kept separate from one another until just prior to use at which time those components are mixed together and applied to a surface. Upon mixing the two components, a full urethane polymerization reaction occurs. Generally, any of a variety of two-component polyurethane systems that are suitable for forming continuous films may be used in this invention. However, preferred polyurethane systems include those comprising, as the polyol component, alpha,omega-polymethacrylate polyols. Suitable alpha,omega-polymethacrylate polyols are commercially available, or can be obtained by reacting terminally hydroxy-functional polymethacrylates, obtained by free-radical polymerization in the presence of a hydroxy-functional molecular weigh regulator, with polyols, with the addition of non-basic transesterification catalysts, in a molar ratio of polymethacrylate to polyol of from 1:1 to 1:10. Examples of monomers that may be used for forming the polymethacrylate sequence of the terminally hydroxy-functional polymethacrylate polyols include diols such as methylmethacrylate, ethylmethacrylate, propylmethacrylate, n-butylmethacrylate, isobutylmethacrylate, tert-butylmethacrylate, n-pentylmethacrylate, amylmethacrylate, n-hexylmethacrylate, n-octylmethacrylate, 2-ethylhexylmethacrylate, n-decylmethacrylate, cyclopentylmethacrylate, cyclohexylmethacrylate, 4-tert-butylcyclohexylmethacrylate, cyclooctylmethacrylate, phenylmethacrylate, isobornylmethacrylate or other acrylates or methacrylates. Examples
Kiliman Leszek B.
Lacks Enterprises, Inc.
Price Heneveld Cooper DeWitt & Litton
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