Patent ID: 8409391
Filing Date: 2013-04-02
Classification: B28B,B32B,Y10T

Abstract:
1. A method for the manufacture of composite building boards formed from first and second mats of non-woven, randomly aligned glass fibers and an intermediate gypsum core, the method comprising the following steps: adhering a Polyvinyl Alcohol (“PVOH”) film to a lower surface of the first mat, the PVOH film being completely dissolvable in the presence of heat and water; pouring a layer of gypsum slurry over an upper surface of the first mat, the slurry penetrating the first mat but being retained by the PVOH film; applying the second mat to the gypsum slurry layer, the first and second mats and intermediate gypsum slurry forming a composite panel; passing the composite panel along a forming belt, wherein the PVOH film functions as a containment envelope to prevent the accumulation of gypsum slurry on the forming belt; cutting the composite panel into composite building boards of desired lengths; flipping the composite building board, whereby PVOH film is exposed and the second mat faces the forming belt; heating the composite building boards in a series of dryers to cure the gypsum slurry, wherein during the curing process entrained water within the gypsum slurry is vaporized and passes through the exposed PVOH film; dissolving the PVOH film via heat from the dryers and the vaporized water, the dissolved film flowing over and adhering to the fibers of the first mat to thereby enhance the physical properties of the composite building boards.