Fiberboard manufactured with cellulose nanofibrils as a binder and method of making same

Abstract

Fiberboard sheet materials containing cellulosic fibers ae disclosed in which cellulose nanofibrils are used as a binder for adhering the cellulosic fibers together. The cellulose nanofibrils are present in an amount of 0.5% to 7.5% by weight on a dry weight basis of the fiberboard sheet. The fiberboard sheet materials have strength properties that meet or exceed the requirements in ASTM C208, and are useful for structural sheathing and roofing board applications. A process for manufacturing the fiberboard sheet is also disclosed.

What is claimed is: 
     
         1 . A fiberboard sheet comprising:
 (a) cellulosic fibers in an amount of 81.0-99.0% by weight on a dry weight basis of the fiberboard sheet;   (b) a binder comprising cellulose nanofibrils, wherein the cellulose nanofibrils have a fiber diameter in the range of 0.01 to 0.3 micrometers, and are present in the fiberboard sheet in an amount of about 0.5% to about 7.5% by weight, on a dry weight basis of the fiberboard sheet.   
     
     
         2 . The fiberboard sheet of  claim 1 , wherein the fiberboard further comprises one or more additional components selected from the group consisting of starches, waxes, alum, fillers, drainage aids, and combinations thereof. 
     
     
         3 . The fiberboard sheet of  claim 2 , wherein the additional component is vegetable starch in an amount of 0.5-9.0% by dry weight. 
     
     
         4 . The fiberboard sheet of  claim 2 , wherein the additional component is paraffin wax in an amount of 0.5-5.0% by dry weight. 
     
     
         5 . The fiberboard sheet of  claim 2 , wherein the additional component is aluminum sulfate in an amount of 0.1-1.5% by dry weight. 
     
     
         6 . The fiberboard sheet of  claim 2 , wherein the additional component is sodium aluminate in an amount of 0.1-1.0% by dry weight. 
     
     
         7 . The fiberboard sheet of  claim 1 , wherein the fiberboard sheet is a structural sheathing product or a roofing insulation panel. 
     
     
         8 . The fiberboard sheet of  claim 1 , wherein the fiberboard sheet has a transverse strength and/or a modulus of rupture (MOR) that meets or exceeds ASTM C208 Type IV Grade 2. 
     
     
         9 . The fiberboard sheet of  claim 1 , wherein the fiberboard sheet has a racking strength that meets or exceeds ASTM C208 Type IV Grade 2. 
     
     
         10 . The fiberboard sheet of  claim 1 , wherein the fiberboard sheet has a wind uplift resistance of at least 330 lb/ft 2  determined in accordance with ANSI/FM4474, FM4450, FM4470. 
     
     
         11 . The fiberboard sheet of  claim 1 , wherein the fiberboard sheet has a resistance to very severe hail damage, as determined in accordance with FM Approval standards. 
     
     
         12 . A fiberboard material comprising:
 (a) cellulosic fibers in an amount of 81.0-99.0% by dry weight,   (b) a binder comprising cellulose nanofibrils, wherein the cellulose nanofibrils have a fiber diameter in the range of 0.01 to 0.3 micrometers and are present in an amount of about 0.5% to about 7.5% by weight based on dry weight of the cellulosic fibers and cellulose nanofibrils; and   (c) water.   
     
     
         13 . A process for manufacturing fiberboard comprising the steps of:
 (a) preparing a fiber slurry comprising cellulosic fibers and water;   (b) adding cellulose nanofibrils having a fiber diameter in the range of about 0.01 to about 0.3 micrometers to the fiber slurry in an amount of about 0.5% to about 7.5% by weight based on dry weight of the cellulosic fibers and cellulose nanofibrils;   (c) dewatering the fiber slurry to form a wet mat comprising the cellulosic fibers and cellulose nanofibrils; and   (d) drying the wet mat to thereby form the fiberboard.   
     
     
         14 . The process of  claim 13 , wherein prior to step (b), the cellulose nanofibrils are diluted in water to form a homogenous liquid. 
     
     
         15 . The process of  claim 14 , wherein the homogenous liquid containing the cellulose nanofibrils is added to the fiber slurry by injecting the liquid into the fiber slurry. 
     
     
         16 . The process of  claim 15 , wherein the homogenous liquid is injected at a pressure greater than the pressure of the fiber slurry at the point of addition. 
     
     
         17 . The process of  claim 13  wherein the process further comprises adding additives to the fiber slurry. 
     
     
         18 . The process of  claim 17 , wherein the additive comprises starch. 
     
     
         19 . The process of  claim 17 , wherein the additive comprises a wax. 
     
     
         20 . The process of  claim 19 , wherein the wax is mixed with the cellulose nanofibrils prior to adding the cellulose nanofibrils to the fiber slurry.