Plastic Coated Composite Building Boards and Method of Making Same

A composite structural panel comprising:

• first and second gypsum slurry layers, wherein the second slurry layer has a higher density than the first layer;
• a porous mat comprising a series of individual fibers held together by a hot melt thermoplastic binder, the mat embedded within second slurry layer, whereby an exterior surface of the mat is substantially covered with gypsum slurry, thereby creating a gypsum boundary layer;
• a surface layer of hot melt thermoplastic overlying the boundary layer;
• a silane coupling agent that facilitates bonding between the individual fibers, the individual fibers and the thermoplastic binder, the individual fibers and the first and second slurry layers, the surface layer and the boundary layer, and the surface layer and the first and second slurry layers.

A composite structural panel comprising:

• a porous mat having interior and exterior surfaces;
• a dense cementitious slurry layer penetrating the porous mat and substantially covering the exterior surface;
• a boundary layer formed by the slurry, the boundary layer substantially covering the exterior surface of the porous mat;
• a core slurry layer formed on the interior surface of the porous mat;
• a non-curing thermoplastic coating adhered to the boundary layer while in a molten state, the thermoplastic coating forming a polymer matrix within the composite structural panel.

A composite, multi-layered structural panel comprising:

• coplanar opposed upper and lower mats formed from non-woven, randomly aligned inorganic fibers held together by a binder, the mats being porous and each having an interior essentially planar surface proximate the opposed mat and an essentially exterior planar surface distal from the opposed mat;
• upper and lower dense slurry layers providing a coating and penetrating the upper and lower mats, whereby the exterior surface of each essentially planar mat is substantially covered by slurry, a slurry boundary layer defined by the slurry covering the exterior essentially planar surface of each mat, the boundary layer having a thickness of between approximately 0.01 to 2.0 mm, each of the upper and lower dense slurry layers including a polymeric additive;
• a core slurry layer extending between and bonded to the upper and lower dense slurry layers, the core slurry layer having a density that is less than the density of the upper and lower dense slurry layers;
• a hot melt non-curing thermoplastic coating disposed adjacent the slurry boundary layer of at least one of the boundary layers, the hot melt non-curing thermoplastic coating having a melting point temperature of between approximately 100° to 500° F., and when cooled, the hot melt non-curing thermoplastic coating mechanically adhering to the slurry boundary layer and being chemically bonded to the thermoplastic by cross-linking thereof with the polymeric additive of the upper, lower and core slurry layers to form a composite polymer matrix, the thermoplastic coating having a thickness of between 0.01 to 500 mils.