Molded gypsum product and process for preparing the same

Claim 1

A process for preparing a molded gypsum product containing from 0.1 to 5 wt. % of glass fiber and from 1 to 9 wt.% of asbestos fiber and having an apparent bulk density of from 0.3 to 0.9 g/cc, which comprises the steps of (1) mixing a hydraulic gypsum, water and reinforcing fibers of at least glass fiber and asbestos fiber to obtain a slurry, (2) charging said slurry in a mold of a compression-molding machine, (3) compression molding said slurry under a pressure of from 0.05 to 20 kg/cm 2 G to remove the excess water from the upper and lower surfaces of the mold to form a molded product having a preselected weight ratio of water to hydraulic gypsum, and (4) setting and drying said molded material to form a three-layered structure composed of three continuous layers consisting of two outer layers of higher density having an apparent bulk density of from 0.4 to 1.5 g/cc and one middle layer of lower density having an apparent bulk density of from 0.2 to 0.7 g/cc, wherein the difference in apparent bulk densities of said higher and lower density layers is not less than 0.1 g/cc.