Stock material or miscellaneous articles – Structurally defined web or sheet – Edge feature
Reexamination Certificate
2000-12-06
2002-10-22
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Edge feature
C428S480000, C428S703000, C427S140000, C427S154000, C427S212000, C427S215000, C427S218000, C427S220000, C427S289000, C427S290000, C427S293000, C528S293000, C528S294000, C528S295000, C106S772000, C106S783000
Reexamination Certificate
active
06468632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to a method for preventing dusting of gypsum board material from sawed edges of gypsum panels. More specifically, the invention is directed to the treatment of cut, e.g., sawed edges of gypsum panels to prevent gypsum dusting in clean rooms.
2. Brief Description of Related Technology
Gypsum wallboards are commonly used today for the construction of ceiling grid panels. The panels are often cut to nominal 2′×4′ or 2′×2′ sizes. The cut edges of these panels can be a source of contamination when the ceiling grid panels are used in clean rooms because the gypsum particles can become airborne. The level of particulates in clean rooms must meet stringent federal standards. Therefore, if the panels are to be used in a clean room, the cut edges of the gypsum ceiling grid panels need to be treated to prevent gypsum particles from contaminating the clean room. It would be desirable to have a tough, fast-drying, tack-free coating that can be applied to cut or sawed edges of gypsum panels that are used in clean rooms that would prevent dusting of gypsum particles.
SUMMARY OF THE INVENTION
In brief, the present invention is directed to a method for sealing the cut edges of a gypsum panel by coating the edges with an effective amount of a composition comprising water and a water-dispersible alkali metal sulfonate-containing polymer.
One aspect of the invention is to provide a gypsum panel wherein cut edges are coated with a water-dispersible alkali metal sulfonate-containing polymer, preferably a polyester. The polymer forms a tough, tack-free coating that prevents dusting of gypsum particles. This panel, with the coated edges, is suitable for use in clean rooms because of the extremely low levels of gypsum particles that separate from the edges of a cut gypsum panel, after coating.
Another aspect of the invention is to provide a method for coating cut edges of gypsum wallboard panels. The cut panels are coated with a water-dispersible alkali-metal sulfonate-frictional polymer, preferably an alkali metal sulfonate-containing polyester by any known coating technique, e.g., by spraying or rolling. The coating prevents dusting of gypsum particles from the cut edges of gypsum panels, thereby reducing gypsum particle contamination to levels that are compliant with federal standards for clean rooms.
Another aspect of the present invention is to provide a method of sealing cut edges of a gypsum panel with a polymeric binder dispersed in water, without the necessity of adding organic sulfonates, organic solvents or organic sequestering agents to the water/polymer composition.
Further aspects of the invention may become apparent to those skilled in the art from a review of the following detailed description, taken in conjunction with the appended claims. While the invention is susceptible of embodiments in various forms, described hereinafter are specific embodiments of the invention with the understanding that the present disclosure is intended as illustrative, and is not intended to limit the invention to the specific embodiments described herein.
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Chen Vivian
Howrey Simon Arnold & White , LLP
National Gypsum Properties LLC
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