Accelerator comprising starch, and related board, slurries, and methods
AssigneeUnited States Gypsum Company
InventorsYijun SANG, Mark K. HEMPHILL, Yongman KIM, James W. BARBER
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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.
Claims20
An accelerator comprising particles of calcium sulfate dihydrate, and starch having a cold water solubility of at least about 25% and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92° C.
A method of preparing gypsum board comprising:
- (a) providing a first cover sheet;
- (b) mixing a slurry comprising stucco, water, and an accelerator comprising calcium sulfate dihydrate particles and starch having 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 starch slurry at 92° C.;
- (c) disposing the slurry between the first cover sheet and a second cover sheet to form an assembly;
- (d) cutting the assembly into a board;
- and
- (e) drying the board.
A slurry comprising stucco, water, and an accelerator comprising calcium sulfate dihydrate particles and starch having 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., wherein, when the slurry is used to make a gypsum core disposed between two cover sheets in a board having a density of about 35 pounds per cubic foot (560 kg/m3) or less, the board has a nail pull resistance of at least about 65 lbs-f, according to ASTM 473-10, method B.
Dependencies are inferred from the claim text.