PROCESS FOR MAKING THIN, SEALANT-COATED, FIBER-REINFORCED GYPSUM PANEL AND PANEL MADE THEREBY

摘要

PROCESS FOR MAKING THIN, SEALANT-COATED FIBER-REINFORCED GYPSUM PANEL AND PANEL MADE THEREBY A process for making a thin, sealant-coated, fire and indentation resistant gypsum panel from at least 2 homogeneous layers of fiber-reinforced gypsum. A layer of a mixture of cellulosic fibers moistened with water and an additive to restrict the adhesion of cellulosic fiber to one another, is deposited on at least two separate conveyors to form a fibrous matt on each conveyor and a layer of dry calcined gypsum containing set accelerator is deposited on the fibrous matt on each conveyor. The deposits on each conveyor contain, on a dry weight basis, about 70% to about 90% by weight gypsum, about 10% to about 19% by weight cellulosic fiber and about 1% to about 9% by weight of combined additive and set accelerator. Each layer on each conveyor is directed to a mixing station to form a homogeneous layer, and the formed homogeneous layers on separate conveyors are placed atop one another on a single conveyor to form a combined homogeneous layer. The combined homogeneous layer is subjected to pressure (compressed) to form a pressed, homogeneous fiber-reinforced gypsum panel. A sufficient amount of water is added to the layer or layers to rehydrate the calcined gypsum. The pressed, homogeneous fiber-reinforced gypsum panel is dried, and the surface of the dried panel is sealed with a wax-free, water resistant sealant. Sealant-coated, fire resistant, indentation resistant gypsum panels having a thickness of about 0.25 inch and having a density of about 60 to 80 lbs./ft.3 are made from 2 homogeneous layers of fiber-reinforced gypsum.