COATED ARTICLE WITH METALLIC
CROSS REFERENCE TO RELATED 5
The present application is a division of my co-pending application Ser. No. 07/219,073 filed July 14, 1988.
BACKGROUND OF THE INVENTION io
The present invention relates to decorative and protective coatings for articles and which provide a desirable metallic appearance.
Decorative and protective coatings are widely employed on various articles and may be applied by vari- 15 ous techniques. On metal articles, electroplating has been extensively utilized to provide chromium, zinc and brass plated surfaces which provide coatings which are both protective and decorative. In some instances, these electroplated coatings are chemically treated to en- 20 hance their corrosion and/or chemical resistance and/or to provide decorative finishes. In other instances, a clear lacquer or resin coating is applied. In some applications, colored organic coatings are applied directly to the substrate. 25
With synthetic resin articles, electroplating cannot be employed without first developing a conductive surface. Thus, chemical or electroless plating and vacuum metallizing are widely employed; however, development of a deposit of sufficient thickness to provide good 30 protective coating is slow and expensive so that electroplating is frequently employed as a second step. Metalfilled organic resin coatings also are sometimes employed to provide a metallic appearance.
The techniques for applying organic coatings are 35 varied, but spray applications predominate in usage. Such spray techniques can be quite inefficient because a substantial portion of the sprayed composition will not deposit on the article or will deposit unevenly. With articles having a conductive surface, electrostatic spray 40 techniques greatly improve the efficiency of the coating operation.
It is an object of the present invention to provide a novel articles provided with coatings exhibiting a highly desirable metallic appearance and in which the 45 coating is provided at relatively low cost.
Another object is to provide such articles in which the coating exhibits good wear resistance and substantive uniformity of coloration.
SUMMARY OF THE INVENTION 50
It has now been found that the foregoing and related objects and advantages may be readily attained in a method for producing decorative and protective coatings on articles in which a surface of the article is sub- 55 jected to a process of dry vacuum metallization to develop a thin metallic deposit thereon of about 100-500 Angstroms in thickness, and electrostatically sprayed onto this metallic deposit is a base coating of a substantially transparent resin formulation. This coating is 60 cured to form a substantially transparent layer of about 0.0005-0.0015 inch in thickness.
The surface of the transparent layer is then subjected to a process of dry vacuum metallization to develop a thin decorative metallic layer thereon of about 65 100-5000 Angstroms in thickness. A top coating of a substantially transparent resin formulation is applied onto the decorative metal layer, and this top coating is
cured to provide a substantially transparent layer having of a thickness of about 0.0005-0.0020 inch. The metallic deposit and several layers produce a composite coating providing a decorative metallic appearance for the article and affording high resistance to corrosion, chemical attack and abrasion.
Generally, the articles utilized in this process are fabricated from synthetic resin although metallic articles and ceramic articles may also be employed.
Desirably, the surface of the article is initially subjected to a cleaning step, and the coatings are provided by resins selected from the group consisting of urethanes, acrylics, urethane-modified acrylics and acrylicmodified urethanes, and copolymers and mixtures thereof. Preferably, the base and top coatings are subjected to ultraviolet radiation to effect curing, and desirably they are initially subjected to infrared radiation to flash off volatiles prior to exposure to ultraviolet radiation. In the preferred process, the top coating is applied by electrostatic spraying to effect a substantially uniform thickness in the top layer.
Normally, the article is one having a multiplicity of surfaces extending at angles to each other and intersecting, and the composite coating is of substantially uniform thickness and coloration over the multiplicity of surfaces and the intersections thereof.
Most desirably, the process of vacuum dry metallizing is effected by sputter coating, and the metal is the same in both the metallic deposit and the metallic layer.
When the article is fabricated from synthetic resin, it is, as coated, free from thermal distortion. When the metal of the metallic deposit is the same as that of the metallic layer, the metallic deposit is visible through both of the coatings and, in the event of a discontinuity in the metallic layer, it maintains the uniformity of the metallic appearance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary diagrammatic view of an article employing a coating produced in accordance with the present invention and drawn to an enlarged scale; and
FIG. 2 is a diagrammatic illustration of the steps in a process embodying the present invention.
DETAILED DESCRIPTION OF THE
Turning in detail first to FIG. 1 of the attached drawing, therein diagrammatically illustrated is a portion of an article generally indicated by the numeral 10 having surfaces 12 and 14 which extend at angles to each other and intersect along an edge. Disposed upon the surfaces 12 and 14 is a composite coating embodying the present invention which includes a thin metallic deposit 16 directly upon the surfaces of the article 10, and a base coat 18 of a transparent resin formulation thereon. Superimposed upon the base coat 18 is a decorative metallic layer 20 which is generally of greater thickness than the metallic deposit 16, and the top coat 22 of a substantially transparent synthetic resin formulation is disposed thereon to complete the composite coating. The thicknesses of the metallic layers are exaggerated relative to the thickness of the resin coatings for clarity of illustration.
Turning now to FIG. 2, therein illustrated diagrammatically are the several steps of the process for producing the composite coatings of the present invention.