AU672755C - Granite-like coating - Google Patents

Description

"GRANITE-LIKS COATING"

Background of the Invention

The present invention relates generally to a method of forming a synthetic surface material simulating various natural substances such as stone, granite and the like and more particularly, to a method of creating and manufacturing a synthetic material capable of being sprayed onto a surface or mold which, when cured, simulates various natural substances such as granite.

Processes currently exist for forming synthetic materials and surfaces which give the appearance of or simulate various natural substances such as stone, marble and the like. Such materials are commonly used in the manufacture of floor and other types of tiles, countertops, sinks, architectural facings, ornamental objects, and generally for any other purpose that marble, stone or the like are used.

One example is a process utilizing a laminated sheet of material marketed under the trademark FORMICA. Such material is formed in large sheets and then cut and applied to the desired surface by adhesive or the like. Such sheets can be manufactured in solid colors or in various patterns, some of which simulate various stone or other textured material. Another example is a process for preparing a material which is commonly referred to as "cultured marble". "Cultured marble" is formed by first creating a mold of a desired shape, spraying the internal mold surface with a gel coat and then filling the mold with a conventional casting resin. Pigments are added to the resin to give it the desired color or pattern. After the resins have set, the mold is removed with the surface facing the mold forming the outer surface of the finished product.

Although many of the prior art methods for creating synthetic surfaces simulating stone and the like are generally acceptable, there is a continuing effort to develop new and more desirable or pleasing patterns as well as patterns which more closely simulate the various natural materials such as stone, granite and the like. Accordingly, there is a continuing need and desire to improve upon existing methods.

The subject invention provides a spray granular coating that mimics the look of granite. The invention is particularly useful in that it can be either sprayed directly onto a surface as a final over-spray or can be sprayed on the inside surface of a mold and then backed with a fiberglass or resin-type substrate.

Summarv of the Invention

The material generated by the present method displays a number of desirable aesthetic and physical properties which have not previously been achieved with sprayable materials. Materials formed in accordance with the present invention more closely simulate synthetic granite or the like while at the same time provide a surface which is very pleasing and one which is extremely durable, repairable and capable of relatively high heat resistance.

The desirable aesthetic properties of the material formed by the method of the present invention are created by utilizing unique granules or compositions in conjunction with a gel coat resin system. A pigment/filler composition may also be utilized in the present invention. All three components (granules, gel coat and pigment/filler) have approximately the same specific gravities.

Detailed Description of the Invention

The subject invention is a sprayable coating which mimics the appearance of granite. The coating is comprised of three components. First, is the gel coat. Most gel coats known in the art are suitable for the practice of the invention, however, a clear isophthalic resin is preferred. The present invention contemplates the use of a conventional gel coats, including polyester or NPG, and other isophthalic resins. Such resins or resin blends are available through a variety of sources and are generally known in the art. Suitable polyester resins are those prepared from polymerizable unsaturated polyesters such as those prepared from ethylenically unsaturated polycarboxcylic acids and polyhydric alcohols. Preferably the resin, when fully cured, provides desirable heat, chemical and moisture resistance. A preferred polyester resin is a styrated isophthalic resin. The resin may also incorporate neopentyl glycol; chlorinated, phosphated, or brominated compounds; or methyl methacr late monomer.

Although the preferred resin system is comprised of an isophthalic resin, it is contemplated that an orthophthalic resin can be utilized as well. It is also contemplated that various other resins could be utilized. Possible other polymeric resins include ethylmethacrylate and epoxy resin systems. Further, it is possible that the primary resin could be comprised of a blend or mixture of different resin components, provided that the various resin components are compatible with one another.

The second component, the granules, are mixed into the gel coat. The granules are premade from the same isophthalic resin as the gel coat, or from an acrylic resin or other resin compatible with the gel coat. The granules have similar properties as the gel coat, i.e., the same resistancy, specific gravity, etc. By having similar properties, the granules remain evenly dispersed and suspended in the gel coat. It may be necessary during the formation of the granules to mix the base resin of the granules with a filler in order to obtain finished granules possessing similar properties as the gel coat.

Although the granules provide a "granite-like" stone appearance, they do not change the overall transparent characteristic of the gel coat. Accordingly, the third component is an optional pigment/filler. Typically this comprises aluminum trihydrate (ATH) . The pigment/filler is added to mask the colorations of the surface to be sprayed, or in the case of a mold application, the coloration of the backing material in the mold. Although any pigmented filler having a specific gravity close to that of the granules used is acceptable, it has been found for the size granule currently preferred, i.e., 20 microns average grain granule diameter, ATH provides the best specific gravity match and also provides a good white color. In accordance with the present invention, the inventor has found that up to 50% by weight, and preferably between about 25% and 50% by weight, of alumina trihydrate may be added to the resin.

The resin system also may include other tinting pigments, fillers and/or other components for the purpose of providing background colorant to the material and/or providing certain properties and characteristics to the resin system during formation and after it has cured. For example, titanium dioxide or any one of various other pigments can be added for additional color. Certain materials may be added for the purpose of reducing the coefficient of thermal expansion of the cured system or providing such system with various other desired properties. One embodiment of the present method contemplates the addition of a filler such as alumina trihydrate to provide fire retardancy to the end product.

It is also contemplated that certain components can also be added to the resin system to control the viscosity and/or the thixotropy of the resin system or matrix.

The coating produced in accordance with the present invention is essentially a transparent coating having a sufficient amount of aluminum trihydrate therein to mask the color of the object being coated. Moreover, the coa ng o e present nvent on s more stable at temperatures at which normal gel coats break down. It is contemplated that this increased stability is due to the thermal conductivity and thermal dissipation provided by the aluminum trihydrate within the coating. Additionally, the subject coating has a higher impact strength than those coatings currently available on the market. In testing done to date, the subject coating has been shown to be approximately two times as strong in impact strength as currently available coatings. The coating also produces a hardness which is greater than that obtained using conventional coatings.

The subject composition of matter is mixed and then sprayed through a conventional spraying apparatus in conjunction with a hardener. Such spraying mechanisms are not described here in detail but are commonly known to those skilled in the coating art.

Upon reading the subject application, various embodiments will become obvious to those skilled in the art. These variations are to be considered within the scope and spirit of the subject invention. Moreover, the examples and text set forth above are to be considered as representative of the subjeer invention, but are not to be construed as limiting. The subject application is to be only limited by the claims which follow and their equivalents.

Claims (13)

What Is Claimed Is:

1. A composition of matter useful in forming a granular-like coating, which comprises: a) a clear gel coat; and b) granules made from the same material as the gel coating and having a density isopycnic with that of the gel coating.

2. A composition of claim 1 further comprising a filler.

3. A composition of claim 1, wherein the gel coat is formed from a clear resin.

4. A composition of claim 3, wherein the clear resin is an NPG resin.

5. A composition of claim 1, wherein the granules are made from a NPG resin.

6. A composition of claim 2, wherein the filler is pigmented.

7. A composition of claim 2, wherein the filler comprises aluminum.

8. A composition of claim 7, wherein the aluminum is present as aluminum trihydrate.

9. A composition of claim 1, wherein the gel coat and the granules have substantially the same specific gravity.

10. A composition of claim 2 , wherein the gel coat, granules and filler have substantially the same specific gravity.

11. A composition of claim 1, wherein a solid coating is formed when contacted with a hardener.

12. A compos t on of c a m 1 urt er compr s ng a hardener.

13. A composition of claim 1, wherein the granules are about 20 microns in average diameter.