Coating processes – Solid particles or fibers applied – Plural particulate materials applied
Reexamination Certificate
2000-11-30
2002-09-03
Cameron, Erma (Department: 1762)
Coating processes
Solid particles or fibers applied
Plural particulate materials applied
C427S355000, C524S013000
Reexamination Certificate
active
06444260
ABSTRACT:
This invention relates to solids-emulating compositions, and concerns in particular solid-particulates-containing paintable or mouldable materials for functional and/or decorative purposes.
There are many occasions when it is desirable, for either functional or purely aesthetic reasons, to give some article or one solid material a coating or appearance of another solid material. For aesthetic purposes, for instance, it might be thought attractive to provide a non-metal object—a wooden carving or a plaster moulding—with the visual appearance of real metal, such as copper, iron, brass or bronze. Similarly, it might be desirable to provide a non-mineral object with the appearance of rock or stone. For functional purposes, for example, it might be desirable to form on a substrate a layer with a high electrical impedance and with the appearance of metal. And from a practical point of view it is clearly desirable that such coatings be applicable in as easy a manner as possible—by being painted on with a brush, say—and that after application the finished surface lend itself to the kind of physical or chemical treatment that a real metal or mineral surface would allow, such as burnishing or polishing, or some sort of chemical alteration. The invention proposes one way of achieving this capability, by using a curable resin-based composition carrying dispersed therein some suitable particulate solid.
It is already known to provide settable curable resin-based metal compositions, primarily for decorative purposes such as making solid objects like busts using a mould, but those presently available tend to be rather inflexible in their mode of use (with a fairly limited number of applications), as well as being quite difficult to employ (the chemicals involved are inclined to be hazardous to health). One such composition, generally intended for making solid objects such as figurines, busts and the like, is provided in three constituent parts—the resin, the metal, and a catalyst—which the User must mix together immediately prior to use (and there is then only a limited amount of time to employ the resin before it sets). Moreover, not only is this type of resin-based substance difficult and unpleasant to use, but in general it cannot easily be applied to a surface with a brush, nor does the finished surface readily lend itself to subsequent physical or chemical treatment.
Another such composition, or group of compositions, is described in the 1978 Specification of published French Patent Application No: 2,364,256 (the corresponding German Offenlegungsschrift is No: 27 05 683). These compositions, like some of those of the present invention, are intended to be employed to provide metal (or metal-like) coatings of one sort of material on substrates of another, to give the substrate a different appearance or properties, but they, too, are provided in separate constituent parts which are mixed just before use. The compositions, too, are in reality difficult and unpleasant to use, and though they can be applied to a surface with a brush or like implement it is not easy to achieve a good finish this way (and nor do the coatings adhere well to the underlying material surface). Moreover, the formed coatings have right from the start a surface “skin” or “film” of opaque resinous material that effectively totally obscures the included metal, and this skin has to be removed after the resin has set—a process which, according to the Specification, requires considerable amounts of abrasion (using coarse abrasives, such as steel wool, abrasive brushes and abrasive powder) to remove the film-forming resin, followed by several more separate “polishing” stages (using finer abrasives or polishing disks or fabrics). This produces residual dust, which is unhealthy and environmentally unfriendly. And if the substrate surface is rough, or even merely dimpled, it is difficult, if not impossible, to remove from the surface sufficient of the skin to reveal the included metal in the depressed areas without actually taking almost all of the layer off the protruding areas.
The invention in one form suggests a novel solid-particulates-containing composition that deals with these problems—a composition that can be available ready made (rather than having to be made up immediately prior to use) but with a substantial shelf life; that can truly be applied like a conventional paint, using a simple paint brush or roller; and that gives with almost no further treatment other than a dust-free light polishing or burnishing an excellent finish which lends itself to a variety of uses and treatments as if it were the surface of an ordinary object of that solid. More specifically, the invention proposes a solid-particulates-containing composition comprising from 5% to 80% by volume of the chosen particulate solid dispersed within either a vinyl acetate polymer composition or an acrylic polymer composition—especially such a composition which contains, per 100 volume parts of the chosen polymer, some water, and particularly from 25 to 80 parts of water. To date, the best compositions seem to be those aqueous compositions that contain both vinyl acetate polymer and acrylic polymer, the amounts being such that, per 100 volume parts of vinyl acetate polymer, there are from 5 to 80 parts of acrylic polymer and from 30 to 80 parts of water. The great advantages of such a composition over those of the Art stem mainly from its aqueous nature—not only does this mean that the compositions, curing (as they do) by loss of water following application, remain usable in the pot for weeks, if not months, after being opened, but it also means that the compositions can be thinned (within limits) to adjust their consistency, applicability and spreading power simply by adding (tap) water, and that they are essentially non-toxic (the normal water-dispersible vinyl acetate polymer and acrylic resins are effectively harmless, and there are no unpleasant organic solvents/diluents or catalysts/hardeners). In addition, by selecting these particular resinous materials—a water-dispersible vinyl acetate polymer and a water-dispersible acrylic resin—there is provided a coating which, on drying, appears to have no, or substantially no, resin material in the form of a skin on top of, and obscuring, the particulate solid, so that with even the most minimal polishing or burnishing (and without the use of any real abrasives) the coating takes on the appearance, and even some of the properties, of the particulate solid.
In one aspect, therefore, the invention provides a composition usable for application as a coating to a surface, the composition being an aqueous dispersion of solid particles within a resinous carrier and comprising:
from 5% to 80% by volume of particulate solid dispersed within
either a vinyl acetate polymer composition or an acrylic polymer composition.
There are preferably from 25 to 80 volume parts of water per 100 volume parts polymer.
Though the composition of the invention is one which contains either vinyl acetate polymer or acrylic polymer, these are not exclusive, and indeed the most preferred compositions of the invention contain both (as noted above). Very preferably, therefore, the invention provides a composition for applying as a coating to a surface, the composition being an aqueous dispersion of solid particles within a resinous carrier and comprising:
from 5% to 80% by volume of particulate solid dispersed within
a vinyl acetate polymer composition containing, per 100 volume parts of vinyl acetate polymer,
from 5 to 80 parts of acrylic polymer, and
from 30 to 80 parts of water.
The invention in one form provides a composition for applying a coating to a surface. The coating is a coating of real solid—whichever solid, or combination of solids, has been employed as the particulate solids—and, depending on the physical form of the particles, and the amount thereof, may actually form an effectively continuous solid layer extending over the surface carrying the coating. Depending on the nature of the solid—if it were copper, nickel, silve
Kramer Kane N.
Thomas Christopher
Cameron Erma
Stetina Brunda Garred & Brucker
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