Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-11-20
2004-04-06
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S425000, C524S563000
Reexamination Certificate
active
06716906
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a ready-to-use self-gauging coating compound containing about 65%-75% solids that provides a flat finely textured finish with improved abuse (abrasion) resistance properties. More specifically, the coating composition of the present invention comprises a resin binder in which there is dispersed an aggregate consisting of particles in a selected size range in a quantity sufficient to form a layer of particles on the substrate that is equal to, but not exceeding the size of the largest particles. This coating offers an enhanced wall finish that can easily be decorated with paint.
BACKGROUND
The current state of the Drywall Finishing Industry requires intensive labor to achieve a smooth final wall appearance. Even when a smooth wall has been produced using traditional finishing compounds, the walls are subject to damage from nicks, dings, scratches scrapes and dents.
The present invention provides a composition to easily achieve a flat, defect free wall surface and provide the additional advantage of dramatically improved abuse resistance. The coating composition of the present invention provides the user with a self-gauging, smoothing coating compound that can be applied to the wall with a trowel or roller and floated smooth. Alternatively, this coating may spray applied.
SUMMARY OF INVENTION
The present invention relates to a ready-to-use, self-gauging coating compound that provides a flat finely textured finish with improved abuse (abrasion) resistance properties. The coating composition of the present invention comprises a resin binder in which there is dispersed an aggregate consisting of particles in a selected size range in a quantity sufficient to form a layer of particles on the substrate that is one particle deep. Preferably, the relatively large aggregate particles in the layer are closely spaced, with the finer particles of filler taking up the interstitial space. The abuse resistance tests, as determined by ASTM D4977 (modified), show the compositions of the present invention survive from 200 to 1000 cycles, and can be extended to as many as 5000 cycles, as compared to unpainted gypsum drywall that typically fails after 20 to 30 cycles.
The coating of the present invention may be applied over newly installed commercial wallboard such as SHEETROCK® Brand Gypsum Panels, abuse resistant wallboard such as SHEETROCK® Brand Gypsum Panels, Abuse-Resistant, and gypsum/fiber board such as FIBEROCK® Brand Panels, to meet the Gypsum Association Level 5 Finish and provide improved abuse resistance. The coating can also be applied over old substrates (drywall, plaster or concrete) in a one-coat application in order to provide a surface of improved appearance with improved abuse (abrasion) resistance properties. The thickness of the installed coating and the resulting abuse-resistance varies somewhat depending upon the nature of the substrate coated.
The abuse resistant coating composition of the present invention preferably falls within the composition limits, on a dry weight percent basis, as shown in Table 1.
TABLE 1
Component
Weight Percent
Aggregate - 30-50 mesh
18 to 55
Resin
3 to 10
Filler
30 to 71
Mica
0 to 4
Talc
0.0 to 10
Attapulgus clay
0.0 to 3.0
Cellulose thickener
0.2 to 0.6
Preservative
0.05 to 0.2
The self-gauging smoothing compound of the present invention is a high-solids, high latex formulation, which contains specific sized aggregate that acts as a gauge or screed. It has been found that a self-gauging coating compound can be formed by adding an aggregate having a specially selected size particles to compositions that are similar to joint compound formulations. The self-gauging nature of the present invention provides for a uniform thickness of coating over the wall surface, improving the uniformity of appearance for the wall, and also the ability of the coating to provide abuse resistance. Application of too little or too much coating would degrade appearance and abuse resistance. Thus the screeding nature of these compositions result in a more limited skill level required to achieve an even finished appearance as well as proper function. This is especially important when using the chemically setting base to ensure that the base has sufficient thickness and water retention to chemically set. The controlled depth feature also facilitates smoothing the surface with a float, resulting in an attractive, uniform appearance, while ensuring proper coating thickness and aggregate density for dramatically enhanced abrasion resistance. In the preferred embodiment, the coating composition of the present invention comprises a resin binder in which there is dispersed aggregate particles passing a 30-mesh screen and retained on a 50-mesh screen. The preferred aggregate for the abuse resistant coating composition of the present invention is silica sand.
The coating composition may be applied either by roller, or by trowel or it may be spray applied. The coating compositions may be either a drying type (with a calcium carbonate filler) or a setting type (with a calcium sulfate hemi-hydrate base).
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Fults Therese A.
Houman Thomas G.
Kenny Timothy G.
Stevens Richard B.
Egan Donald E.
Janci David F.
Lorenzen John M.
Shosho Callie
United States Gypsum Co
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