Patent ID: 9623586
Date: 2017-04-18
CPC Classifications: B28B,B32B,C04B,E04B,E04C,Y10T

Claim:
1. A method for making a fire resistant gypsum panel, the method comprising: (A) preparing a gypsum slurry having vermiculite particles dispersed therein, the vermiculite particles expandable from a first unexpanded volume to a second average expanded volume of about 300% or more of the original unexpanded volume when heated for one hour at about 1560° F.; (B) disposing the gypsum slurry between a first cover sheet and a second cover sheet to form an assembly comprising a set gypsum core with the expandable particles generally distributed throughout the gypsum core; (C) cutting the assembly into a panel of predetermined dimensions; and (D) drying the panel; such that the panel has a density (D) of about 40 pounds per cubic foot or less and a core hardness of at least about 11 pounds, a nominal panel thickness of about ⅝-inch, and a gypsum core and distribution of the expandable vermiculite particles therein effective to inhibit the transmission of heat through a single-layer assembly of said panels prepared pursuant to the procedures of UL U305, where surfaces of the panels on one side of the assembly are exposed to a heat source and surfaces of the panels on the opposite, unheated side of the assembly are provided with a plurality of temperature sensors pursuant to ASTM standard E119-09a, such that the maximum single value of the temperature sensors on the unheated side of the assembly is less than about 500° F. after about 60 minutes when the assembly is heated in accordance with the time-temperature curve of ASTM standard E119-09a.