Abstract: Disclosed is a composite gypsum board comprising a board core comprising set gypsum sandwiched between face and back cover sheets. The composite gypsum board also comprises an intermediate sheet between the board core and the face cover sheet, with a thin, dense gypsum layer disposed between the intermediate sheet and the face cover sheet. Optionally, a second dense gypsum layer can be disposed between a first major side of the board core and the back cover sheet. Also disclosed is a method of preparing a composite gypsum board in which an intermediate sheet is applied over a dense gypsum layer disposed on a face cover sheet. A back cover sheet is applied to the other major side of the board core, with a second dense gypsum layer optionally disposed therebetween.

Abstract: A modified gypsum set accelerator and a method of preparing the same is provided, which includes dry loose finely ground particles of a mixture of ground dry calcium sulfate dihydrate and a grinding aid selected from one or more of beta-naphthalene sulfonate formaldehyde condensate, trimetaphosphate phosphate salt, tripolyphosphate salt, tetra-pyrophosphate salt, and pregelatinized starch.

Abstract: Disclosed are product (e.g., panels), slurry, and methods relating to a pregelatinized starch having a mid-range viscosity (i.e., from about 20 centipoise to about 700 centipoise).

Abstract: Disclosed is a composite gypsum board comprising a board core and a concentrated layer, as well as related methods of preparing board and slurries. The board core and the concentrated layer both are formed from water and stucco. The concentrated layer is designed to have higher density and/or nail pull than the core. The concentrated layer is further formed from one or more of starch thickener, cellulose, and/or copolymer containing polyacrylamide and acrylic acid. In some embodiments, the concentrated layer is formed from an enhancing additive to enhance strength therein, while the core is formed without using enhancing additive or less enhancing additive than used in forming the board core.

Abstract: A layered gypsum wallboard can include: a gypsum board having opposing front and back faces, wherein the gypsum board comprises a first cover sheet material at the front face, a second cover sheet material at the back face, and a gypsum core layer comprising gypsum; an adhesive layer on the second cover sheet material of the gypsum board, the adhesive including a polymer having a glass transition temperature (Tg) of ?10° C. to 30° C.; an intermediate gypsum layer including gypsum on the adhesive layer such that the adhesive layer is between the second cover sheet material and the intermediate gypsum layer, wherein the adhesive layer and the intermediate gypsum layer have a combined thickness of 0.09 inches to 0.25 inches; and a third cover sheet material, wherein the intermediate gypsum layer is between and in contact with the adhesive layer and the third cover sheet material.

Abstract: Disclosed are product (e.g., panels), slurry, and methods relating to a pregelatinized starch having a mid-range viscosity (i.e., from about 20 centipoise to about 700 centipoise), and an extruded pregelatinized starch.

Abstract: An accelerator for accelerating the rate of hydration of calcined gypsum is disclosed. The accelerator comprises calcium sulfate dihydrate particles and a starch. The starch has a cold water solubility of at least about 25% (e.g., at least about 35%) and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92° C. Also disclosed are a method of preparing an accelerator, method of hydrating stucco to form set gypsum, slurry, and method of making gypsum board.

Abstract: Disclosed is a composite gypsum board comprising a hoard core and a concentrated layer of substantial thickness (e.g., at least about 0.02 inches). The concentrated layer includes a higher weight percentage of an enhancing additive than the board core. The board core has a thickness greater than the thickness of the concentrated layer and forms the bulk of the board volume. The concentrated layer has a higher density (e.g., at least about 1.1 times greater) than the density of the board core. Also disclosed is a method of preparing a composite gypsum board.

Abstract: Disclosed is a composite gypsum board comprising a board core and a concentrated layer of substantial thickness (e.g., at least about 0.02 inches). The concentrated layer includes a higher weight percentage of an enhancing additive than the board core. The board core has a thickness greater than the thickness of the concentrated layer and forms the bulk of the board volume. The concentrated layer has a higher density (e.g., at least about 1.1 times greater) than the density of the board core. Also disclosed is a method of preparing a composite gypsum board.

Abstract: Disclosed are product (e.g., panels), slurry, and methods relating to a pregelatinized starch having a mid-range viscosity (i.e., from about 20 centipoise to about 700 centipoise).

Abstract: Disclosed is gypsum board formed from stucco, water, and at least one migrating starch having a cold-water solubility of at least about 25%. Generally, the starch has a viscosity of less than about 20 centipoise (e.g., from about 1 centipoise to about 20 centipoise), as determined according to the VMA method. Also disclosed are related slurries and methods of preparing gypsum board.

Abstract: Disclosed is gypsum board with good strength, as well as gypsum slurries, methods, and cover sheets. Board is formed using one or more of starch, electrolyte, and/or hydrophilic material. These strength ingredients can be applied onto a cover sheet before contacting a gypsum slurry used in forming a gypsum layer in the board, and/or can be incorporated into the gypsum slurry used for forming one or more gypsum layers in the board, e.g., the board core and/or a concentrated gypsum layer between the core and one or both cover sheets.

Abstract: Disclosed are product (e.g., panels), slurry, and methods relating to an uncooked starch having a mid-range peak viscosity (i.e., from about 120 Brabender Units to about 900 Brabender Units).

Abstract: Disclosed are product (e.g., board), slurry, and methods relating to an uncooked starch that can be used to enhance strength in one or more gypsum layers in the board. The uncooked starch has a hot water viscosity of from about 20 BU to about 300 BU according to the HWVA method, and/or a mid-range peak viscosity of from about 120 Brabender Units to about 1000 Brabender Units.

Abstract: Provided herein is a joint compound having a composition to allow tools to easily clean up, comprising water, at least one inert filler, and a binder comprising a sulfonated starch, and a method of preparing the joint compound.

Abstract: Disclosed are product (e.g., panels), slurry, and methods relating to a pregelatinized starch having a mid-range viscosity (i.e., from about 20 centipoise to about 700 centipoise), and an extruded pregelatinized starch.

Abstract: A modified gypsum set accelerator and a method of preparing the same is provided, which includes dry loose finely ground particles of a mixture of ground dry calcium sulfate dihydrate and a grinding aid selected from one or more of beta-naphthalene sulfonate formaldehyde condensate, trimetaphosphate phosphate salt, tripolyphosphate salt, tetra-pyrophosphate salt, and pregelatinized starch.

Abstract: A wallboard panel is provided, including a sheet of face paper, a first layer of gypsum composition having a first density, a web of mesh associated with the first layer of gypsum composition, a second layer of gypsum composition having a second density, the second density being lower than the first density, and a layer of backing paper. An associated method includes providing a sheet of face paper and laying same upon a moving conveyor belt, applying a first layer of gypsum composition slurry upon the sheet of face paper, applying a web of mesh upon the first layer of gypsum composition slurry, applying a second layer of gypsum composition slurry upon the web of mesh, and applying a sheet of backing paper upon the second layer of gypsum composition slurry.

Abstract: Disclosed are methods relating to an extruded pregelatinized, partially hydrolyzed starch prepared by mixing at least water, non-pregelatinized starch, and acid to form a starch precursor. The acid can be a weak acid that substantially avoids chelating calcium ions or a strong acid in a small amount. In the method, pregelatinization and acid-modification of the starch precursor occurs in one step in an extruder. Also disclosed are methods of preparing board using the starch prepared according to the methods, as well as starches and boards prepared by various methods of the invention.

Abstract: Disclosed is a gypsum board comprising a set gypsum core disposed between two cover sheets. The set gypsum core is formed from a slurry comprising stucco, water, and at least one pregelatinized starch having a viscosity of from about 20 cP to about 300 cP as measured according to the VMA method described herein. The starch is present in an amount of greater than 10% by weight of the stucco. In preferred embodiments, the board has good strength properties even at lower densities, such as about 31 pcf or less. Also disclosed are a related method of making a gypsum wallboard and a slurry.