Binderless panel made from wood particles and cellulosic fibers

Abstract

The present invention relates to pressed fiberboard articles made using a binderless wet process from a combination of fibers and particles. A mixture of particles (e.g., wood particles) and cellulosic fibers is formed into a panel using only water, heat and pressure. The present invention is further directed to fiberboard articles having uniform density cores or higher density cores.

1 . A method of forming a pressed article, comprising:
 i) combining particles with cellulosic fibers in an aqueous medium to form a particle-fiber/water mixture;   ii) distributing said mixture in a form, wherein said form is configured for removal of water from said mixture;   iii) removing water from said mixture to produce an article having a surface and a core;   iv) pressing said article at an initial pressure, under conditions wherein a fiber matrix is dewatered on a surface of said article; and   v) pressing said article at a final pressure under conditions wherein a fiber matrix in said core of said article is cured.   
     
     
         2 . The method of  claim 1 , wherein step iii comprises applying a vacuum to said form to remove water from said mixture. 
     
     
         3 . The method of  claim 1 , wherein the ratio of particles to cellulosic fibers is between about 25:75 to 75:25 (weight to weight). 
     
     
         4 . The method of  claim 1 , wherein said particles comprise wood particles and/or charcoal particles. 
     
     
         5 . The method of  claim 1 , wherein said cellulosic fibers comprise paper fibers and/or agricultural fibers. 
     
     
         6 . The method of  claim 1 , wherein said cellulosic fibers comprise long fibers and/or short fibers. 
     
     
         7 . The method of  claim 1 , wherein said first pressure is higher than said final pressure. 
     
     
         8 . The method of  claim 1 , wherein said first pressure is about 75 and 500 psi board pressure. 
     
     
         9 . The method of  claim 1 , wherein said final pressure is between 10 and 50 psi board pressure. 
     
     
         10 . The method of  claim 1 , wherein said pressing at said first pressure is done at a temperature not to exceed 212° F. 
     
     
         11 . The method of  claim 1 , wherein said pressing at said final pressure is done at a temperature between 350 and 400° F. 
     
     
         12 . The method of  claim 1 , further comprising pressing at a second pressure after pressing at said first pressure, wherein said second pressure is lower than said first pressure or said final pressure. 
     
     
         13 . The method of  claim 12 , wherein said first pressure is between about 75 and 500 psi board pressure; said second pressure is between about 10 and 50 psi board pressure; and/or said final pressure is between about 75 and 500 psi board pressure. 
     
     
         14 . The method of  claim 12 , wherein said pressing at said first pressure is done at a temperature not to exceed 212° F. 
     
     
         15 . The method of  claim 12 , wherein said pressing at said second pressure is done at 350 and 400° F. 
     
     
         16 . The method of  claim 12 , wherein said pressing at said final pressure is done at a temperature between 350 and 400° F. 
     
     
         17 . The method of  claim 1 , wherein said article is a panel. 
     
     
         18 . The method of  claim 17 , wherein said panel is a flat panel or a curved panel. 
     
     
         19 . A composition comprising a binderless panel comprising wood particles and cellulosic fibers, wherein said panel is at least 0.125 inches to 1.0 inch thick or greater, and wherein said panel has uniform density through the thickness of the panel. 
     
     
         20 . A composition comprising a binderless panel comprising wood particles and cellulosic fibers, wherein said panel is at least 0.125 inches thick, and wherein said panel has core portion disposed between a first outer portion and a second outer portion, wherein said core portion has higher density than said first outer portion and said second outer portion.