Fiberboards, uses and methods of preparation thereof

Abstract

There is provided a fiberboard, such as a MDF fiberboard or a HDF fiberboard, comprising wood fibers, a binder, and a sludge such as a pulp and a paper sludge. The sludge can be, for example, chosen from a primary pulp and paper sludge, a secondary pulp and paper sludge, a de-inking sludge, and mixtures thereof.

1 . A fiberboard comprising:
 wood fibers;   a binder; and   a pulp and paper sludge,   
     wherein said fiberboard is a medium density fiberboard or a high density fiberboard. 
   
   
       2 . The fiberboard of  claim 1 , wherein said wood fibers are virgin wood fibers, post-consumption wood fibers, or a mixture thereof. 
   
   
       3 . The fiberboard of  claim 1 , wherein said sludge is present in said fiberboard in an amount of at least 1% by weight, based on the total dry weight of the fiberboard. 
   
   
       4 . The fiberboard of  claim 1 , wherein said sludge is present in said fiberboard in an amount of at least 5% by weight, based on the total dry weight of the fiberboard. 
   
   
       5 . The fiberboard of  claim 1 , wherein said sludge is present in said fiberboard in an amount of at least 10% by weight, based on the total dry weight of the fiberboard. 
   
   
       6 . The fiberboard of  claim 1 , wherein said sludge is present in said fiberboard in an amount of about 1% to about 40%, based on the total dry weight of the fiberboard. 
   
   
       7 . The fiberboard of  claim 1 , wherein said sludge is present in said fiberboard in an amount of about 4% to about 15%, based on the total dry weight of the fiberboard. 
   
   
       8 . The fiberboard of  claim 1 , wherein said fiberboard has substantially the same properties than a conventional fiberboard. 
   
   
       9 . The fiberboard of  claim 1 , wherein said sludge is chosen from a primary pulp and paper sludge, a secondary pulp and paper sludge, a de-inking sludge, and mixtures thereof, 
   
   
       10 . The fiberboard of  claim 3 , wherein said sludge is a primary pulp and paper sludge. 
   
   
       11 . The fiberboard of  claim 3 , wherein said sludge is a mixture of primary pulp and paper sludge and a secondary pulp and paper sludge. 
   
   
       12 . The fiberboard of  claim 1 , wherein said sludge is a substantially untreated primary sludge taken from a paper mill. 
   
   
       13 . The fiberboard of  claim 1 , wherein said fiberboard has an internal bond strength of at least 1.30 kN/mm 2 . 
   
   
       14 . The fiberboard of  claim 9 , wherein said fiberboard has an internal bond strength of at least 1.40 kN/mm 2 . 
   
   
       15 . The fiberboard of  claim 1 , wherein said fiberboard has an internal bond strength of at least 1.70 kN/mm 2 . 
   
   
       16 . The fiberboard of  claim 1 , wherein said fiberboard has an internal bond strength of at least 1.90 kN/mm 2 . 
   
   
       17 . The fiberboard of  claim 7 , wherein said fiberboard has an internal bond strength of about 1.3 kN/mm 2  to about 1.98 kN/mm 2 . 
   
   
       18 . (canceled) 
   
   
       19 . The fiberboard of  claim 17 , wherein said fiberboard is a high density fiberboard having a density of at least 800 kg/m 3 . 
   
   
       20 . The fiberboard of  claim 1 , wherein said fiberboard is a high density fiberboard having a density of at least 900 kg/m 3 . 
   
   
       21 . The fiberboard of  claim 3 , wherein said fiberboard is a high density fiberboard having a density of about 800 kg/m 3  to about 950 kg/m 3 . 
   
   
       22 . The fiberboard of  claim 1 , wherein said binder is chosen from formaldehyde-based resins, isocyanate-based resins, and mixtures thereof. 
   
   
       23 . In a medium density fiberboard or a high density fiberboard comprising wood fibers and a resin, the improvement wherein at least a portion of the wood fibers are replaced with recycled fibers obtained from a sludge chosen from a primary pulp and paper sludge, a secondary pulp and paper sludge, a de-inking sludge, and mixtures thereof. 
   
   
       24 . A fiberboard obtained by pressing a mixture comprising
 wood fibers;   a binder; and   as a pulp and paper sludge.   
   
   
       25 . A process for treating sludge, said process comprising screening a pulp and paper sludge having a dryness of about 0.5% to about 10%, through a screen of 160 μm or coarser, in order to at least partially reduce the amount of ashes contained in said sludge. 
   
   
       26 . The process of  claim 25 , further comprising mixing the treated sludge with wood fibers and a binder so as to obtain a composition, drying said composition, and pressing said dried composition so as to obtain a medium density fiber board or a high density fiberboard.