초록 ▼

A process is described for making a gypsum board having improved water resistance. The resulting gypsum board products are also described. The process comprises adding an aqueous siloxane emulsion to an aqueous slurry of a calcium sulfate material and host particles, where the siloxane emulsion is s

A process is described for making a gypsum board having improved water resistance. The resulting gypsum board products are also described. The process comprises adding an aqueous siloxane emulsion to an aqueous slurry of a calcium sulfate material and host particles, where the siloxane emulsion is stable under the condition in which the slurry is maintained. The process further includes passing said siloxane containing slurry onto a flat porous forming surface to form a filter cake; removing a substantial portion of the water from the filter cake through the porous surface; pressing the filter cake to form a board and remove additional water; and drying the board to remove the remaining free water and to cause the core of the board to reach a temperature sufficient to cure the siloxane.

대표청구항 ▼

[ I claim:] [1.] A process for making a gypsum board product having improved water resistance which comprises:adding an aqueous siloxane emulsion to an aqueous slurry of a calcium sulfate material and host particles, while said slurry is at a temperature at which calcium sulfate hemihydrate crystals

[ I claim:] [1.] A process for making a gypsum board product having improved water resistance which comprises:adding an aqueous siloxane emulsion to an aqueous slurry of a calcium sulfate material and host particles, while said slurry is at a temperature at which calcium sulfate hemihydrate crystals are maintained, said siloxane emulsion comprises at least one hydrogen modified siloxane, said siloxane emulsion being stable under the conditions in which the calcium sulfate hemihydrate crystals are maintained;passing said siloxane-containing slurry onto a flat porous forming surface to form a filter cake before the temperature of said filter cake falls below the temperature at which the calcium sulfate hemihydrate rehydrates to calcium sulfate dihydrate;removing a substantial portion of the water from said filter cake through said porous surface and cooling said filter cake to a temperature at which rehydration begins,pressing said filter cake to form a board and remove additional water whereby the calcium sulfate hemihydrate crystals about said host particles rehydrate in situ to calcium sulfate dihydrate crystals; anddrying said board to remove the remaining free water and to cause the core of said board to reach a temperature sufficient to cure said siloxane.