Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1999-06-04
2001-08-07
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S070000, C428S701000, C428S921000, C052S232000, C052S381000, C052S383000, C052S784110, C052S787110
Reexamination Certificate
active
06270915
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to ceiling boards and ceilings with fire-resistive barriers and, in particular, to ceiling boards and ceilings which are made of gypsum boards with a layer of an intumescent material, containing expandable particulate graphite and a corrosion inhibitor, applied to a major surface of the gypsum boards to form a fire-resistive barrier.
Ceilings for many commercial and residential structures are typically made with gypsum boards that are secured to wood or metal framing with metal screws or nails. Several types of gypsum boards are used for these ceiling applications. The first type of gypsum board is a regular gypsum board, such as that marketed by GP Gypsum Corporation as regular gypsum board under the trademark “GyProc” for use in wall and ceiling applications. The regular gypsum boards have non-combustible, dimensionally stable non-reinforced gypsum cores. The second type of gypsum board is a ceiling gypsum board, such as that marketed by GP Gypsum Corporation as a ceiling board under the trademarks “GyProc” “CD Ceiling Board” for use in ceiling applications. For comparable thicknesses, the ceiling gypsum boards are heavier than the regular gypsum boards and have non-combustible, dimensionally stable gypsum cores that are reinforced, e.g. with inorganic glass fibers. The third type of gypsum board is a gypsum board with a fire-resistive rating, such as that marketed by GP Gypsum Corporation under the trademarks “GyProc” “Fireguard” and “Fireguard” C gypsum board for use in wall and ceiling applications. For comparable thicknesses, the fire-resistive rated gypsum boards are heavier than either the regular gypsum boards or the ceiling gypsum boards and have non-combustible, dimensionally stable gypsum cores that are reinforced, e.g. with inorganic glass fibers. While all of these gypsum boards have cores made of non-combustible materials, the cores of these gypsum boards are all heat degradable and, after various periods of time, fail from an exposure to the heat from a fire.
Since the time lapse prior to failure from the heat of a fire progressively increases from the regular gypsum boards to the ceiling gypsum boards to the fire-resistive rated gypsum boards, for many applications, the ceiling gypsum boards are specified or required for a particular application rather than the regular gypsum boards and, for still other applications, the fire-resistive rated gypsum boards are specified or required rather than the regular or the ceiling gypsum boards. During construction, contractors sometimes install the wrong type of gypsum board and thus, the ceiling, as constructed, does not meet the requirements for that particular application. Currently, when this occurs, the contractor must remove the ceiling and replace it with a ceiling using the correct type of gypsum boards. This can be quite a costly procedure in materials, time and labor. However, currently, there are no other acceptable alternatives.
Intumescent materials, such as those disclosed in U.S. Pat. No. 3,574,644; issued Apr. 13, 1971; Franciszek Olstowski et al (hereinafter “the '644 patent), can be applied (as stated in column
3
, lines
1
-
5
of the '644 patent) in the form of a coating to “normally combustible or heat degradable materials such as wood, fiber-board, plastics, insulative ceilings or wall panels, other cellulosic building materials, or the like” to increase the flame resistance of such normally combustible or heat degradable materials. These intumescent materials form passive fire protection systems which remain inactive until subjected to heat and temperatures such as those encountered from the flames of a fire. When these passive fire protection systems are subjected to heat and temperatures, such as those encountered in a fire, these intumescent materials react, grow and expand forming a char (many times the original thickness of the coating applied) to insulate the surface to which the material is applied from the damaging effects of the heat generated by the fire.
While these materials can be quite effective as fire barriers, these intumescent materials can be corrosive to steel, stainless steel, copper, aluminum and other metals or metal alloys, such as those commonly used in the construction industry. Thus, in applications, where these intumescent materials come in contact with metal components, e.g. metal fasteners such as screws or nails used to secure gypsum board to framing members, metal framing members and other metal structural members or utilities such as piping and the like, the use of these intumescent materials can cause corrosion problems and although the disclosure of the '644 patent has been available to the construction industry for over twenty five years, gypsum boards for ceiling applications and ceilings are still constructed using standard or fiber reinforced gypsum board without any fire-resistive barrier.
SUMMARY OF THE INVENTION
The gypsum board/intumescent material ceiling boards and ceilings of the present invention provide a solution to the need to replace a ceiling when the wrong type of gypsum boards are used for a particular application and can be used to further enhance the fire-resistive properties of ceilings using the type of gypsum boards normally specified or required for particular applications. The gypsum board/intumescent material ceiling boards of the present invention and forming the ceilings of the present invention each include a gypsum board and a fire-resistive barrier. A first major surface of the gypsum board is an upper side for abutting framing and a second major surface of the gypsum board is an underside for facing a room interior. The fire-resistive barrier is a layer of intumescent coating material applied to and coextensive with the first and/or second major surface of the gypsum board. The intumescent coating material contains expandable graphite and a corrosion inhibitor in sufficient quantities to provide a corrosion inhibiting layer on metal surfaces, such as the surfaces of metal fasteners, with which the intumescent coating material comes in contact. In addition, the intumescent coating material has a pH greater than 7.0 to reduce corrosive properties of the intumescent material and provide a chemical environment conducive to the forming of the corrosion inhibiting layer by the corrosion inhibitor.
The fire-resistive barrier can be applied to the first or second major surface of a gypsum board or to both major surfaces of the gypsum board prior to installing the ceiling board (e.g. by spraying or otherwise coating the major surface or surfaces of the gypsum board with the intumescent coating material in the same process where the gypsum board is produced or at a job shop) or the fire-resistive barrier can be applied to the second major surface of a gypsum board after the installation of the gypsum board in a ceiling structure (e.g. by spraying, brushing or otherwise applying the intumescent coating material to the second major surface of the gypsum board).
REFERENCES:
patent: Re. 34951 (1995-05-01), Slosberg et al.
patent: 3574644 (1971-04-01), Olstowski et al.
patent: 3642531 (1972-02-01), Peterson
patent: 3945962 (1976-03-01), Clark
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patent: 4563491 (1986-01-01), Comune
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patent: 5057367 (1991-10-01), Morii et al.
patent: 5132054 (1992-07-01), Stahl
patent: 5175197 (1992-12-01), Gestner et al.
patent: 5232976 (1993-08-01), Horacek et al.
patent: 5338349 (1994-08-01), Farrar
patent: 5481834 (1996-01-01), Kowalczyk et al.
patent: 5498466 (1996-03-01), Navarro et al.
patent: 6102995 (2000-08-01), Hutchings et al.
Beitel, III Jesse J.
Shumate Monroe W.
Turpin Kenneth A.
Johns Manville International Inc.
Jones Deborah
Lister John
McNeil Jennifer
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