Cultured onyx products and methods therefor

#This invention has to do with products simulative in appearance to the naturally occurring semi-precious silicas known as onyx, or to like minerals such as marble. More particularly, the invention is concerned with novel materials and methods and mineral simulative products resulting therefrom, characterized by enhanced fidelity to natural materials in appearance, in improved resistance to deterioration in their expected use environment, reduced weight for lower cost shipping, and in versatility of design configuration. Moreover the present materials, methods and products are achieved at significant reductions in manufacturing costs by virtue of the elimination of various manufacturing steps heretofore thought necessary in the cultured onyx and cultured marble industry. In the ensuing description, cultured onyx will be primarily referred to as an ideal illustrative embodiment of the practice of the invention.

#A large market exists for tubs, pullmans, tile, tub enclosures, plaques, sculptures, and other shaped products having the uniquely attractive, nearly nacreous layered translucent depth of onyx, an optical effect heightened by the presence of subtly or strongly contrasting, diffuse striations of visually differeniatable localized zones of concentration of contrastant having indistinct mergence with the surrounding matrix in three dimensions. In general, this market has been supplied with products based on a polyester resin matrix extended and optically modified with a filler comprising tiny glass particles, referred to as frit.

#In U.S. Pat. No. 3,396,067 to K. A. Schafer the simulation of naturally occurring onyx in a wide variety of useful products is taught to be achievable by blending polyester resins filled with one or another fillers, e.g. silicas and more particularly glass frit in a specific manner to interdistribute essentially alike polyester phases and thereafter simultaneously curing all the polyester to hardness with one phase frozen in another. The disadvantages of the technique taught include obtention of a nonpolishable surface and excess weight since glass is more than twice as heavy as polyester resin and so hard relative to the polyester that surface polishing produces a multiplicity of discrete islands too small to really be seen and too numerous to count but which in the aggregate appear as a surface dullness which increases with polishing rather than diminishing. Thus those in the art having only the Schafer process and product have resorted to gel coats, surface coverings of clear resin, which are polished appearing, to conceal the true surface and thus beautify the product. Unfortunately, this expedient brings its own problems, since gel coats may be rubbed through by too vigorous cleaning, which may occur in a washbasin, for example. Too they are typically water vapor pervious, and over time, in use, they permit water seepage into the underlying structure which is manifested by a separation of the gel coat from the substrate, and the resultant appearance of an air pocket or bubble behind the gel coat which is disruptive of the light reflection and spoils the product aesthetics.

#The invention will be further described as to an illustrative embodiment thereof in conjunction with the attached drawing, in which:

#FIG. 1 is a perspective view of a shaped product, namely a faucet produced in accordance with the methods of the invention, using the compositions of the invention;

#FIG. 2 is a view in horizontal section thereof; and

#The present invention uses a resin portion as filler. The resin filler is prepared by hardening a heat or catalytically curable liquid resin, such as polyester, or other resin as described below, in bulk to form a solid body of hardened resin. The degree of hardening is not narrowly critical, with typical resin bodies being not friable but trituratable by application of grinding or abrading force. Thus a body of hardened resin is triturated to a fine powder comprised of discrete particles of generally polygonal shape, by impacting at high centrifugal speed against circularly fixed teeth under temperature conditions conducive to embrittlement of the resin body so as to facilitate erosion of the body and generation of particulate. Crushing of the resin body after freezing is effective, with the resultant lumps being further refined by high speed impact with appropriately arranged teeth, also under lowered temperature conditions where resin gumming may occur. A grind to at least 50 U.S. mesh mean average particle size diameter is usually required for obtaining a cultured onyx product, although other minerals having coarser, even grainy striations may be made with coarser particulate, and grinding will not have to be so fine. A mean average particle size of 80 U.S. and below is preferred for optimum subtlety of transition from accent to background in cultured onyx. Typically the hardened resin body is coarsely divided and the coarse pieces impacted against teeth until a particulate of the desired size distribution is realized.

#The particulate filler may be the color of the resin body which in a polyester resin tends to be a water white to gray in the absence of added colorant. A colorant, i.e. a material imparting a color value other than the naturally occurring color, may be added to the resin, e.g. before hardening, for example an organic or inorganic dye and/or pigment, liquid or solid powder, may be added to a slurry of the polygonal chips in uncured resin or other vehicle prior to addition of the particulate to the matrix resin. Advantageously, a masterbatch of chips may be prepared and specific colorants added as need be from time to time for product production purposes, thus to minimize inventory of colors. The use of reactive color formers on the particulate is also practical, the color being developed in situ in the product. The color may be any tone including deepened or lightened aspects of the eventual matrix color. In this connection, it is the presence of visual distinguishability through the presence of a contrast between the phases of the product that is important, not specific color contrasts. The polyester resins for example exhibit contrast between commingled phases regardless of a colorant as an additional contrastant.

#The hardened filler is then mixed with the matrix material, suitably a further portion of the filler resin. Colorant to form localized concentrations of high contrast, e.g. striations, bursts, veins, whorls, umbras and the like, typical of onyx and marble is added. The mix is controllably agitated or not as desired to achieve the nonuniform, locally randomized, concentration pattern of distribution of colorant in the uniformly comixed filler and matrix. Swirling, agitating, adding from single or multiple points in thick or thin streams all have their effect on the final pattern. It is preferable to slowly combine a first mix of a given background color of liquid, nonhardened matrix and the hardened filler particulate with a second mix of another background color of liquid, nonhardened matrix resin and the hardened filler and to combine these different background color mixes with pigment or other pattern forming colorant, with careful definition of distribution, and then to add the combined mixes and colorant to the mold to be used to shape the product structure using more or less percentage of particulate filler to vary the viscosity of the combined mixes for application to the form and to determine the apparent concentration of pattern in the final product desired, more mixing reducing colorant concentration and less mixing maintaining an initial pattern of distribution. The substantially equivalent specific gravities of the filler and matrix in the invention preferred compositions give a high degree of control over distribution pattern not available where the filler for example is far heavier than the matrix, as in prior art systems.