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: 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: 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: A coating for preparing a floor underlayment to receive an adhesive includes a water-soluble, latex polymer, a defoamer and a dual-function surface enhancing agent. The surface enhancing agent includes a set accelerator that also functions to cross link the adhesive, hardening the surface of the underlayment using at least two mechanisms. One embodiment of the invention is a dry mixture that forms a coating when added to water. The dry mixture includes from about 10% to about 50% of the redispersible polymerby weight based on the mixture, from about 50% to about 90% of the surface enhancing agent and from about 0.15% to about 0.25% of the defoamerby weight based on the mixture. Other embodiments describe a liquid coating formed by adding from about 1 to about 8 parts water to 1 part of the dry mixture by volume based on the mixture.

Abstract: A coating for preparing a floor underlayment to receive an adhesive, where the coating includes a water-soluble, latex polymer, a defoamer and a dual-function surface enhancing agent. The surface enhancing agent includes a set accelerator that also functions to cross link the adhesive, hardening the surface of the underlayment using at least two mechanisms. One embodiment of the invention is a dry mixture that forms a coating when added to water. The dry mixture includes from about 10% to about 50% of the redispersible polymer on a dry weight basis, from about 50% to about 90% of the surface enhancing agent and from about 0.15% to about 0.25% of the defoamer on a dry weight basis. Other embodiments describe a liquid coating formed by adding from about 1 to about 8 parts water to 1 part of the dry mixture on a volume basis.

Abstract: A composition and method for treating a set gypsum-containing material are disclosed. The composition is formed from at least water at least one trimetaphosphate salt, at least one monobasic phosphate salt, and at least one acyclic polyphosphate salt having at least three phosphate units. The method comprises applying to a set gypsum material at least two of the following inorganic phosphates: at least one monobasic phosphate salt, at least one trimetaphosphate salt, and at least one acyclic polyphosphate salt having at least three phosphate units. The method can be for inhibiting re-calcination of a set gypsum containing material, and/or for enhancing the strength, surface hardness, paintability, abrasion resistance, and/or water erosion resistance of a set gypsum-containing material. Also disclosed is a method of making a set gypsum-containing material.

Abstract: A ready-mixed composition, which sets when mixed with an activator for the reaction of calcined gypsum with water to form set gypsum, is disclosed. The composition comprises water and calcined gypsum in a weight ratio of water to calcined gypsum of from about 0.15 to about 0.5, as well as a set preventer comprising a polyacrylic acid and/or a salt thereof. The composition has a viscosity of from about 5,000 centipoise to about 48,000 centipoise. Also disclosed is a kit that comprises separately packaged components. One of the components is a composition comprising calcined gypsum and a polyacrylic acid and/or a salt thereof, and, optionally, water. Another component of the kit comprises an activator which, when mixed with the composition, permits the composition to set.

Abstract: A ready-mixed composition, which sets when mixed with an activator for the reaction of calcined gypsum with water to form set gypsum, is disclosed. The composition comprises water and calcined gypsum in a weight ratio of water to calcined gypsum of from about 0.15 to about 0.5, as well as a set preventer comprising a polyacrylic acid and/or a salt thereof. The composition has a viscosity of from about 5,000 centipoise to about 48,000 centipoise. Also disclosed is a kit that comprises separately packaged components. One of the components is a composition comprising calcined gypsum and a polyacrylic acid and/or a salt thereof, and, optionally, water. Another component of the kit comprises an activator which, when mixed with the composition, permits the composition to set.

Abstract: A composition and method for treating a set gypsum-containing material are disclosed. The composition is formed from at least water at least one trimetaphosphate salt, at least one monobasic phosphate salt, and at least one acyclic polyphosphate salt having at least three phosphate units. The method comprises applying to a set gypsum material at least two of the following inorganic phosphates: at least one monobasic phosphate salt, at least one trimetaphosphate salt, and at least one acyclic polyphosphate salt having at least three phosphate units. The method can be for inhibiting re-calcination of a set gypsum containing material, and/or for enhancing the strength, surface hardness, paintability, abrasion resistance, and/or water erosion resistance of a set gypsum-containing material. Also disclosed is a method of making a set gypsum-containing material.