Gypsum composition comprising uncooked starch having mid-range viscosity, and methods and products related thereto
(22) 18.07.2018
(43) 20.02.2020
(57) Disclosed is a gypsum board comprising a set gypsum core disposed between two cover sheets, the core formed from a slurry comprising stucco, water, and at least one uncooked starch having a) a hot water viscosity of 20 - 300 Brabender Units when the viscosity is measured by the HWVA method and/or b) a peak viscosity of 120 - 1000 Brabender Units when the viscosity is measured by putting the starch in a slurry with water at a starch concentration of 15% solids, and using a Viscograph-E instrument set at 75 rpm and 700 cmg, where the starch is heated from 25 °C to 95 °C at a rate of 3 °C/minute, the slurry is held at 95 °C for ten minutes, and the starch is cooled to 50 °C at a rate of -3 °C/minute and/or c) a cold water viscosity at 10% of solids of 5 - 50 centipoise when the viscosity is measured by a Brookfield viscometer method at 25° C. Further disclosed is a method of preparing gypsum board comprising: (a) mixing a slurry comprising stucco, water, and at least one uncooked starch a) or b) (b) disposing the slurry between a first cover sheet and a second cover sheet to form a wet assembly; (c) cutting the wet assembly into a board; and (d) drying the board, the dried board having a density of about 35 pcf (560 kg/m).
(71) United States Gypsum Company (US)
