Abstract: A gypsum slurry includes water, a hydraulic component including stucco and a polycarboxylate dispersant. The dispersant has two repeating units wherein the first repeating unit is an olefinic unsaturated mono-carboxylic acid repeating unit or an ester or salt, and the second repeating unit is a vinyl or allyl group bound to a polyether by an ether linkage. The slurry can be made into a gypsum panel.

Abstract: A gypsum slurry is described that includes water, a hydraulic component comprising at least 50% calcined gypsum by weight based on the dry weight of the hydraulic component, foam, a defoamer and a polycarboxylate dispersant. In some embodiments of the invention, the defoamer is combined with the dispersant prior to being added to the gypsum slurry. The defoamer and dispersant can be added as a physical mixture, wherein the defoamer is attached onto the dispersant polymer, or a combination thereof. In some embodiments, a gypsum building panel is made from the gypsum slurry.

Abstract: A gypsum slurry includes calcium sulfate hemihydrate, water and calcium sulfate dihydrate is coated with a hydrophilic, dispersible coating. The coating is less soluble than the calcium sulfate hemihydrate to delay exposure of the landplaster to the remainder of the slurry, preventing premature crystallization and the early stiffening that accompanies it. Another embodiment is a gypsum slurry that includes calcium sulfate hemihydrate, a polycarboxylate dispersant, water and coated calcium sulfate dihydrate. In this case, the hydrophilic, dispersible coating is selected to serve as a modifier to enhance the ability of the dispersant to fluidize the gypsum slurry.

Abstract: A gypsum slurry includes calcium sulfate hemihydrate, water and calcium sulfate dihydrate is coated with a hydrophilic, dispersible coating. The coating is less soluble than the calcium sulfate hemihydrate to delay exposure of the landplaster to the remainder of the slurry, preventing premature crystallization and the early stiffening that accompanies it. Another embodiment is a gypsum slurry that includes calcium sulfate hemihydrate, a polycarboxylate dispersant, water and coated calcium sulfate dihydrate. In this case, the hydrophilic, dispersible coating is selected to serve as a modifier to enhance the ability of the dispersant to fluidize the gypsum slurry.

Abstract: In a method of making a gypsum slurry, a polycarboxylate dispersant, a modifier and a hydraulic material comprising stucco are selected for use in the slurry. These components are then combined with water to form a slurry, where the modifier is added to the slurry prior to formation of a slurry phase by the water, the stucco and the dispersant. The modifier has been shown to be less effective when added after the dispersant and stucco have been contacted in an aqueous slurry. In a preferred embodiment, an amount of stucco is obtained and the modifier and dispersant are selected. A predissolved solution of a dispersant and modifier is prepared in water to form a solution prior to the addition of the stucco. After mixing the solution, the stucco is added to form the slurry. Optionally, the slurry is then shaped into a product and allowed to set.

Abstract: The invention generally provides gypsum-containing slurries including stucco, trimetaphosphate salt, and naphthalenesulfonate dispersant, wherein the trimetaphosphate salt is present in an amount of at least about 0.12% by weight based on the weight of stucco. Other slurry additives can include accelerators, binders, starch, and paper fiber, glass fiber, and other known ingredients. The invention also comprises the gypsum-containing products made with such slurries, for example, gypsum wallboard, and a method of making gypsum wallboard.

Abstract: Effective use of dispersants in wallboard containing foam results from a method where stucco is mixed with a first dispersant and a first quantity of water to form a gypsum slurry. A soap is blended with a second dispersant and a second quantity of water to make a foam. Subsequently, the foam is combined with the slurry. Choice of different first and second dispersants and their relative amounts allows control of the size distribution of the foam bubbles in the slurry and the resulting voids in the gypsum core. Use of the same dispersant in both the mixer and the foam water provides a boost in efficacy of the dispersant.

Abstract: An improved gypsum slurry that includes water, calcium sulfate hemihydrate, a polycarboxylate dispersant and a modifier. The modifier is chemically configured to improve the efficacy of the polycarboxylate dispersant. Preferred modifiers include cement, lime, slaked lime, soda ash, carbonates, silicates and phosphates.

Abstract: In a method of making a gypsum slurry, a polycarboxylate dispersant, a modifier and a hydraulic material comprising stucco are selected for use in the slurry. These components are then combined with water to form a slurry, where the modifier is added to the slurry prior to formation of a slurry phase by the water, the stucco and the dispersant. The modifier has been shown to be less effective when added after the dispersant and stucco have been contacted in an aqueous slurry. In a preferred embodiment, an amount of stucco is obtained and the modifier and dispersant are selected. A predissolved solution of a dispersant and modifier is prepared in water to form a solution prior to the addition of the stucco. After mixing the solution, the stucco is added to form the slurry. Optionally, the slurry is then shaped into a product and allowed to set.

Abstract: A gypsum slurry includes water, a hydraulic component including stucco and a polycarboxylate dispersant. The dispersant has two repeating units wherein the first repeating unit is an olefinic unsaturated mono-carboxylic acid repeating unit or an ester or salt, and the second repeating unit is a vinyl or allyl group bound to a polyether by an ether linkage. The slurry can be made into a gypsum panel.

Abstract: A slurry is made including water, at least 50% by weight calcium sulfate hemihydrate, and a specific polycarboxylate dispersant prepared using at least three repeating units. A first repeating unit is a vinyl ether-type repeating unit. A second repeating unit includes a maleic acid-type repeating unit. A third repeating unit includes an acrylic acid-type repeating unit. The polymer dispersant has a molecular weight of from about 20,000 to about 80,000 Daltons. The slurry made from this composition can be made at reduced water levels to speed drying and reduce drying costs.

Abstract: Effective use of dispersants in wallboard containing foam results from a method where stucco is mixed with a first dispersant and a first quantity of water to form a gypsum slurry. A soap is blended with a second dispersant and a second quantity of water to make a foam. Subsequently, the foam is combined with the slurry. Choice of different first and second dispersants and their relative amounts allows control of the size distribution of the foam bubbles in the slurry and the resulting voids in the gypsum core. Use of the same dispersant in both the mixer and the foam water provides a boost in efficacy of the dispersant.

Abstract: An improved gypsum slurry that includes water, calcium sulfate hemihydrate, a polycarboxylate dispersant and a modifier. The modifier is chemically configured to improve the efficacy of the polycarboxylate dispersant. Preferred modifiers include cement, lime, slaked lime, soda ash, carbonates, silicates and phosphates.