Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
1998-09-11
2001-06-05
Cameron, Erma (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S514000, C427S195000, C427S201000, C427S202000, C427S385500, C427S407100, C427S421100
Reexamination Certificate
active
06242056
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the addition of microbeads to enhance the light emission, refraction or diffusion properties of heat-cured paint coatings. The invention relates to improved heat-curable paint compositions containing microbeads for producing painted surfaces, such as automobile bodies, having enhanced light-emission, light-refraction or light-diffusion properties, such as enhanced reflection, coloration, luminescence, phosphorescence and scattered light reflectability properties.
2. Description of Related Art
Microbeads and microspheres of glass, plastics and other materials, including those coated with conductive and reflective surface layers, are commercially-available for a variety of purposes, including use as light reflective fillers in paint and related coating compositions.
Reference is made to U.S. Pat. No. 5,650,213 for its disclosure of retroreflective coating compositions, such as for screen printing onto fabrics, containing hemispherically-metallized microsphere beads of 20 to 200 micron size, and transparent pigment particles of less than 2 micron size, having a color corresponding to the color of the substrate or desired image, to provide an attractive daytime image and daytime unnoticability. The coatings contain an aqueous matrix or binder material and have a final thickness of matrix which is less than one-half the diameter of the reflective beads.
It is known to add light-reflective glass beads, including hemispherically-metallized glass beads to opaque paint compositions such as for highway signs in order to provide dried paint surfaces, at or above which the beads are exposed. Light directed thereat, such as from automobile headlights, is retroreflected or reflected directly back at the source by the metallic bead coating or by brightly-colored pigments or an aluminum flake layer underlying the beads, which function as transverse lenses.
Reference is made to U.S. Pat. Nos. 2,879,171; 2,963,378; 2,997,403 and 3,251,704 for their disclosures of opaque, low solids paint compositions containing film-forming binder materials which dry by solvent evaporation, glass beads and opaque pigments. In U.S. Pat. No. 2,879,171 the coating particles exceed 50 to 2,500 micron size and the coating physically retains the 3 to 10 mil (75 to 250 microns) glass beads exposed at the outer surface of the dried paint to act as light reflectors. In U.S. Pat. No. 2,963,378 the low solids paint composition contains a major amount by weight of volatile organic solvents, 35 weight percent of reflectorized glass beads of 10 to 500 micron diameter and solvent-drying, film-forming binder materials to provide reflex-reflecting, non-diffusing coatings. The reflectorized glass beads may be mixtures of glasses having different refractive indexes, and their surfaces may be coated with transparent pigment or dye to retro-reflect in color. The coatings have glass bead protrusions and are covered with a top coating of transparent varnish, which may be colored, to provide a flat glossy surface.
U.S. Pat. No. 2,997,403 also discloses solvent lacquer spray compositions containing 25 to 40% by volume of glass beads of 0.0017 to 0.0024″ (42.5 to 60&mgr;) diameter for application over painted surfaces to provide retroreflective surface coatings.
U.S. Pat. No. 3,251,704 discloses low solids spray paint compositions containing hemispherically-metallized glass beads of different refractive indexes and sized between about 15 and 75 microns, and opaque pigment particles which do not interfere with the required reflex-reflection properties. The dried composition contains exposed glass beads as reflex-reflective lens elements.
SUMMARY OF THE INVENTION
The present invention is based upon the discovery that the overall visual appearance, richness or depth of color and aesthetic properties of paint compositions, such as for spray-painting automobiles, boats, aircraft and home appliances, are substantially improved by formulating such paint compositions as high solids content, heat-curable, transparent or translucent compositions containing embedded or encapsulated light-refractive colorless and/or tinted transparent glass beads, preferably between about 10 to 20 microns diameter, and one or more color-enhancing agents such as pigments, dyes aluminum flakes, colored aluminum flakes, mica, metallized mica, holographic flakes, phosphorescent glass beads and similar light-enhancing agents. Alternatively, some of the color enhancing agents may be present in a colored base coating over which the translucent light-refractive glass bead-embedded composition is applied, to cause light reflected by the base coat to be refracted and dissipated across the translucent glass bead layer, whereby the intensity and richness of the color or appearance of the combined layers is substantially enhanced.
While the present paint compositions may contain some beads which are opaque and/or retroreflective, such as hemispherically- or fully-metallized glass beads, or phosphorescent-coated beads, it is essential that a substantial content of the beads comprises light-refractive, clear or tinted glass beads which function as light diffusers within the light-transmissive or semi-opaque translucent paint layer to scatter direct and indirect light, including colored light, in all directions across the paint layer. The scattered light may have the color of a reflective base layer, or may become colored or enhanced by absorption and/or reflection by a color-enhancing ingredient also embedded within the beaded paint layer, such as metal flakes, mica, pigment, metallized beads or glass beads containing color, pigment, luminescent or phosphorescent coatings, holographic flakes or similar color enhancing additives. The most critical feature of the present light-refractive paint layers is that they scatter light across the paint layer, depending upon their degree of transluceny, due to the content of fully-embedded transparent or translucent beads, and do not merely retro-reflect or focus applied light directly back to the source. To the contrary the translucent glass beads refract direct and indirect light in all directions through the paint layer, to enhance the depth and richness of the color(s) of the paint layer or the underlying base layer.
The present bead-containing refractive paint compositions may be based upon volatile organic solvents, water or may be solvent-free spray powder compositions.
In the case of volatile organic solvent compositions, the solids content is maintained high, above about 60% solids, which is facilitated by the content of the inert, solid glass beads, pigment, aluminum flakes, mica, etc., and the film-forming binder material comprises a heat-curable resin system such as a polyester, acrylic, polyurethane or epoxy resin system including a cross-linking agent.
The present paint compositions may be water-borne or aqueous compositions comprising a water soluble heat-curable, cross-linking binder material such as an acrylic acid ester resin, a methacrylic acid ester resin, a polyurethane polymer, or the like, a microbead mixture comprising clear or translucent refractive beads and color enhancers such as pigmented, dyed, phosphorescent or luminescent reflective beads, pigments, metal flakes, mica, holographic flakes, etc.
In another embodiment of the invention the present compositions contain volatile organic solvent or vehicle, but are prepared as high solids compositions containing the refractive glass beads, color enhancers and a minor amount of resinous binder material and solvent or vehicle.
In yet another embodiment of the invention the present compositions do not contain any volatile organic solvent or aqueous vehicle, but are prepared as heat-fusible powder spray compositions containing the refractive glass beads, color enhancers and a fusible resinous binder material.
DETAILED DESCRIPTION
The most critical component of the present light-transmissive compositions is the mixture of color-enhancers and microbeads which comprises (a) translu
Andrews John W.
Spencer Andrew B.
Tucker, II Gary D.
Cameron Erma
Innovative Concepts Unlimited, LLC
Perman & Green LLP
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