| 摘要 |
<p>Abstract The invention provides a lightweight composite gypsum board including a foamed low density set gypsum core a top non-foamed (or reduced foamed) bonding high density layer and a bottom non-foamed (or reduced-foamed) bonding high density layer, a top cover sheet bonded to the foamed low density set gypsum core by the top non-foamed (or reduced-foamed) bonding high density layer, and a bottom cover sheet bonded to the foamed low density set gypsum core by the bottom non-foamed bonding high density layer and wherein the composite board has a dry weight of about 1000 lb/MSF or less for a % inch thick board, a nail pull resistance of at least about 77 lb/MSF, and a core hardness of at least about 11 lb/MSF. The gypsum-containing slurry further comprises a naphthalenesulfonate dispersant in the form of an aqueous solution containing from about 40% to about 45% by weight naphthalenesulfonate and the aqueous solution is present in the slurry in an amount from about 0.5% to about 2.5% by weight based on the weight of stucco.</p> |
