The present invention is directed to coated metal articles and methods of forming such coated metal. Particularly, the invention is directed to colored and coated metal sheet material which may be suitable for, but not limited to, household low temperature appliance applications, as well as in architectural, industrial food service and/or electronic equipment enclosures.
Many household appliances, such as ovens, ranges, refrigerators, dishwashers and the like, are manufactured utilizing “polished” stainless steel sheet material, the surface of which is abraded by one or more belts. The polished stainless steel offers important rust and corrosion resistance characteristics, and additionally affords a unique surface appearance which has been found to be highly desirable. However, stainless steel is rather expensive and may have other significant disadvantages. For example, some stainless steels are non-magnetic, which may be disadvantageous in certain applications. Also, stainless steel may have poor resistance to fingerprints, stains and/or scratches. Stainless steel may be relatively difficult to clean, and typically requires specialized tooling different from that required for other steels in order to form/stamp parts for manufacturing. The specialized tooling is at times needed due to the mechanical properties of stainless steel vs. standard cold rolled steels.
It is known to utilize other steel materials, such as cold rolled steel, which are less expensive than stainless steel, and to use treatments, such as galvanizing, to provide adequate rust/corrosion resistance. However, heretofore, it has not been possible, utilizing metals other than stainless steel, to achieve the desirable surface appearance of polished stainless steel.
One attempt to simulate the desirable surface appearance of polished stainless steel is disclosed in U.S. Pat. No. 6,440,582, which utilizes an aluminum-zinc alloy-coated steel of the type sold under the tradename Galvalume®, wherein the alloy coating is brushed and includes a particulate compound. But that product does not provide corrosion resistance comparable to that of stainless steel and the hot dip process of applying the alloy coating results in a spangle, which requires the particulate compound to counteract. Also, the product of the '582 patent, as disclosed, may not meet the visual and aesthetic requirements of most appliance manufacturers.
Another issue not addressed by prior materials is the use of color. Consumer color choices in stainless steel appliances have typically been limited. Not just tints and shades, but actual vibrant color schemes. One reason is that the addition of a color layer may hide or otherwise obscure the brushed stainless steel appearance. Another issue with such color layers is their apparent lack of suitable heat resistance for more widespread use, limiting the color-layered metal materials to cool and ambient temperature surfaces.
Thus, there is a need, generally, for a material which provides important rust and corrosion resistance characteristics of stainless steel and affords the unique surface appearance of stainless steel which has been found to be highly desirable, while avoiding the significant disadvantages of stainless steel, such as cost, non-magnetism, and poor resistance to fingerprints, stains and/or scratches. Further, a need exists for a method which permits coloring of a faux stainless steel material without detracting from or hiding the desired stainless steel appearance, and while providing at the same time a low-heat resistant material.
There is disclosed herein an improved coated metal article and method of making same which avoids the disadvantages of prior articles and processes, while affording additional structural and operating advantages.
In particular, there is disclosed a coated metal article comprising a ferrous metal substrate, an abraded metallic coating on the substrate wherein the abraded metallic coating has a substantially uniform patterned appearance which simulates the surface appearance of polished stainless steel, and an acrylic polymer coating overlying the abraded metallic coating on one side of the substrate.
In an embodiment, the article may include an abraded electro-galvanized steel substrate, including a pre-treatment coating underlying the polymer coating.
These and other aspects of the invention can be more readily understood when considered in the conjunction with the following description of the invention and the appended drawings.
For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated.
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated.
Referring generally to
The article 10 has a metal substrate 11 (
Both sides of the substrate 11 are provided with a metallic coating 13, which is preferably a galvanizing coating which is predominantly Zinc, and is most preferably a Zinc alloy including a percentage of Nickel. The amount of Nickel in the alloy is preferably in the range of about 7% to about 15%, with about 11% Nickel being the most preferred composition.
The outer surfaces of the metallic coatings 13 are abraded, as with polishing belts, to a predetermined substantially uniform patterned appearance having a low roughness finish. The preferred roughness (Ra) is less than 20 μin, and most preferably is in the range of from about 5 μin to about 10 μin. The polished outer surfaces of the metallic coatings 13 may have applied thereto a pre-treatment layer 14 which provides a clean surface for the chemical bonding of adjacent layers as well as providing additional corrosion protection. To the pre-treatment layer 14, there is applied, on the obverse or main side of the article 10, a primer coating 15, which is preferably an acrylic-based primer. Finally, to the primer coated strip, a polymeric top coating 17, which is in the form of an acrylic polymer layer, is applied. The acrylic polymer is colored in a manner which provides a vibrant colored surface. The acrylic polymer layer, preferably applied by roll coating, has a preferred thickness in the range of from about 0.2 to about 0.3 mil so as to more effectively control the final color of the product and also to greatly enhance the corrosion and chemical resistance of the article 10.
Acrylic polymer is derived from the monomer methyl methacrylate (MMA) and has many desirable characteristics. For example, acrylic is resistant to a wide range of chemicals including salts, bases, aliphatic hydrocarbons, fats and oils, most common gases and inorganic chemicals, dilute mineral and organic acids, and dilute and concentrated solutions of most alkalis.
Acrylic polymers can be prepared having suitable heat-resistance characteristics as well. Such polymers, known to those skilled in the art, have exhibited good stability in tests after 300 hours at 275° F. This heat test qualifies such polymer-coated material to be used on low heat surfaces, such as oven sides and modified oven doors.
Also, compared with other polymers, acrylic is relatively easy to process. It can be molded with little or no residual stress and is available in formulations specifically designed for injection molding or extrusion in a wide range of melt-flow rates. These characteristics make acrylic an ideal top-coating for the article 10.
The color is created using materials suitable for such purposes, all of which are known to those skilled in the art. Many color choices are suitable for coloring the acrylic polymer layer.
Preferably, on the reverse side of the article 10, there is applied to the optional pre-treatment layer 14 a clear or tinted backer coating 19, which is preferably a polyester clear coat or other polymer as required to perform functionally or aesthetically, depending upon the end product.
Referring now to FIGS. 2 and 3A-3E, there is illustrated a process for producing the colored and coated metal article 10 of
In forming the coated metal article 10 of
This electro-galvanized CRS substrate is then passed through an abrading step 22. Referring to
The abrading or polishing, in addition to achieving a desired surface appearance, also tends to remove material from the metallic coating 12, resulting in the abraded metallic coating 13, as seen in
The foregoing parameters are those desired for applications in certain appliances such as, for example, oven sides and doors. However, there may be applications which have less demanding specifications, either because they do not require as accurate a simulation of the appearance of polished stainless steel or perhaps do not require the same level of corrosion protection. For such applications, it may be possible to perform the abrading step 22 utilizing brushes 35 (
After the abrading step 22, the abraded metallic coated substrate of
The strip may also undergo a back coating step 25, in which there may be applied to the reverse surface of the strip a clear or tinted backer coating 19 (
After the back coating step 25, if used, the strip undergoes a top coating step 26. In this step, there is applied to the obverse face of the strip a colored acrylic polymer coating 17 (
If desired, the coated metal article 10 may undergo post processing, as at 28, which may include any of a number of different processing steps, such as supplying a protective strippable liner to the obverse surface of the strip, slitting of the strip, re-rolling of the strip, cutting into discrete sheets, and final shipment to a customer.
While, in the metal coating step 21, a Zinc-Nickel alloy is preferably applied, as described above, it may be possible, for certain applications, to galvanize the substrate 11 utilizing a Zinc-only coating. The use of the Zinc Nickel coating is preferred because it gives somewhat improved corrosion protection as well as increased hardness. However, because of the additional corrosion protection afforded by the acrylic polymer coating 17, the use of Nickel may not be necessary. This would improve economy, since a Zinc-only coating would be slightly less expensive. The Zinc-only galvanized material also has a slightly different appearance, and could be used in simulating the appearance of different stainless steels. For example, a Zinc only coating could be used in simulating a 400-series stainless steel, while a Zinc-Nickel coating could be used to simulate a 300-series stainless steel.
While electro-deposition of a Zinc-Nickel coating is preferred, it may also be possible to use aluminized or hot dip galvanized substrates, depending upon the application. However, the aluminized coating has a different appearance from a Zinc galvanizing coating, which may be undesirable. The use of a hot dip process for applying a Zinc galvanizing coating may be somewhat less expensive than electro-deposition, but tends to result in a surface spangle, which must either be removed, or an operation must be performed to mask the spangle.
In the pre-treatment of step 23, the pre-treatment may be applied by a roll-on technique to produce good corrosion and color results. It is also possible to use a dip tank treatment or to pre-treat the strip with either a chrome-containing treatment or, in certain applications, a non-chrome containing treatment.
There could also be applied to the pre-treatment layer 14 on the obverse side of the strip a polymeric top coat in the form of a tinted polyester clear coat, which may be applied to a dry film thickness in the range of from about 0.5 mil to about 0.6 mil. While this thin polyester top coat may have a higher pencil hardness, which might be desirable in certain applications, it does not provide the same level of corrosion protection as the acrylic polymer coating and may make it more difficult to control color. Alternatively, the thin polymeric top coat could be an epoxy or acrylic coating.
Four colored acrylic polymer coated metal substrates (Gray, Orange, Red and Blue) were prepared as set forth in TABLE I. The same sample substrates were run through various physical tests, the test method, standards and results of which are set forth in TABLE II below.
From the foregoing, it can be seen that there has been provided an improved colored acrylic polymer coated metal article and method of making same which effectively simulates the surface appearance of polished stainless steel while affording important advantages over stainless steel.
The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants' contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on preceding description and any prior art.
The present application is being filed as a continuation-in-part of and with a claim of priority to co-pending U.S. patent application Ser. No. 11/205,689 to Tullis et al. filed Aug. 17, 2005, which is a divisional application of U.S. application Ser. No. 11/074,113 to Tullis et al., now U.S. Pat. No. 7,125,613, issued Oct. 24, 2006, the disclosure of both references being hereby incorporated by reference.
Number | Date | Country | |
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Parent | 11074113 | Mar 2005 | US |
Child | 11205689 | US |
Number | Date | Country | |
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Parent | 11205689 | Aug 2005 | US |
Child | 12288105 | US |