Thin-layer lignocellulose composites and methods of making the same

Abstract

In one aspect, the present invention is a thin-layer lignocellulose composite having increased resistance to moisture. The thin-layer lignocellulosic composite includes a mixture of no more than about 95% by weight of a lignocellulosic fiber and at least about 5% by weight of an organic isocyanate resin. The mixture further includes short fibers and a release agent that does not interfere with subsequent processing of the thin-layer lignocellulosic composite. The mixture is pressed between two dies at an elevated temperature and pressure and for a sufficient time to form a thin-layer composite of predetermined thickness, and to allow the isocyanate resin to interact with the lignocellulosic fiber and short fibers such that the resultant thin-layer composite has a predetermined resistance to moisture.

1 . A method to produce a thin-layer lignocellulosic composite, comprising:
 forming a lignocellulosic composite mixture including no more than about 95% by weight of at least one type of lignocellulosic fiber, at least about 5% by weight of an isocyanate resin, and at least about 2% by weight of fiberglass; and   pressing the mixture between two dies at an elevated temperature and pressure and for a sufficient time to form the thin-layer composite with a thickness which ranges from about 0.050 inches (about 1.27 mm) to about 0.625 inches (about 15.88 mm).   
     
     
         2 . The method of  claim 1 , further comprising:
 pre-pressing the mixture into a loose mat.   
     
     
         3 . The method of  claim 2 , wherein forming a lignocellulosic composite mixture comprises mixing a release agent with the lignocellulosic fiber, isocyanate and fiberglass. 
     
     
         4 . The method of  claim 3 , wherein the release agent comprises an emulsion of surfactants and polymers. 
     
     
         5 . The method of  claim 3 , wherein the release agent is added directly to the mixture prior to pre-pressing the mixture into a loose mat. 
     
     
         6 . The method of  claim 3 , wherein the amount of release agent added to the mixture ranges from about 0.10% to about 5% by weight. 
     
     
         7 . The method of  claim 3 , further comprising:
 spraying additional release agent onto at least one surface of the loose mat.   
     
     
         8 . The method of  claim 7 , wherein the amount of release agent sprayed onto the mat surface comprises from about 0.1 to about 8.0 grams per square foot (about 1.1 to about 86.1 grams per square meter) of mat surface. 
     
     
         9 . The method of  claim 1 , further comprising:
 coating at least one die surface with an anti-bonding agent.   
     
     
         10 . The method of  claim 9 , wherein the step of coating at least one die surface comprises baking the anti-bonding agent onto the die surface. 
     
     
         11 . The method of  claim 1 , wherein the lignocellulosic mixture comprises about 60% to about 95% by weight fiber. 
     
     
         12 . The method of  claim 1 , wherein the isocyanate comprises diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI). 
     
     
         13 . The method of  claim 1 , wherein fiberglass is present in the composite mixture in an amount from about 2% to about 10% by weight. 
     
     
         14 . The method of  claim 1 , wherein fiberglass is present in the composite mixture in an amount from about 5% to about 8% by weight. 
     
     
         15 . The method of  claim 1 , wherein the fiberglass comprises fibers with an average length from about 0.03 inches to about 2.0 inches. 
     
     
         16 . The method of  claim 1 , wherein at least about 90% by weight of the fiberglass fibers have a length less than about 1.5 inches. 
     
     
         17 . The method of  claim 1 , wherein at least about 99% by weight of the fiberglass fibers have a length less than about 1.5 inches. 
     
     
         18 . The method of  claim 2 , wherein the temperature used to press the mat into a thin layer ranges from about 250° F. (about 121° C.) to about 400° F. (about 204° C.). 
     
     
         19 . The method of  claim 2 , wherein the pressure used to press the mat into a thin layer ranges from about 2500 psi (about 176 kg/cm 2 ) to about 150 psi (about 10.5 kg/cm 2 ). 
     
     
         20 . The method of  claim 1 , wherein the thin-layer composite comprises a thickness swelling of less than about 10% after being immersed for about 24 hours in water at about 70° F. (about 21° C.).