Patent ID: 7862687
Filing Date: 2011-01-04
Classification: C03C,C04B,D21H,D21J,E04B,Y02W

Abstract:
1. A process of making an acoustical ceiling panel with an open structure and improved acoustical absorption properties comprising; providing a aqueous slurry mixture comprising mineral wool, at least one member of the group consisting of thermoplastic binder, starch and mixtures of thermoplastic binder and starch, and optional additives, wherein the aqueous slurry has a solids concentration of 3.0 to 6.0 wt. %; distributing the slurry on a porous carrier; dewatering the slurry on the porous carrier by gravity drainage over at least one gravity drainage box to form a gravity drained base mat, wherein the slurry is dewatered to a water concentration of 74 to 84 wt. %; vacuum draining to remove water by applying a first vacuum to the gravity drained base mat for about 2-20 seconds to remove about 18% to 34% of the water in the gravity drained base mat and then applying a second vacuum to the compressed base mat to remove an additional 10% to 52% of the water from the base mat after it is subjected to the first vacuum application, wherein the second application of vacuum removes additional water from the base mat without compressing the thickness of the base mat through static pressure by more than 10% from the thickness of the gravity drained base mat; and wherein the vacuum drained base mat has a density of about 10.9 to about 15.0 pounds per cubic foot on a dry basis, and a noise reduction coefficient (NRC) of about 0.80 to about 0.95.