Method for Producing Lignocellulose Nanofibrils From Phosphorylated Fibers

Abstract

A method for producing lignocellulose nanofibrils from phosphorylated fibers. The method includes hydrolyzing an amount of phosphorylated fibers in which the phosphorylated fibers include a phosphorylated lignocellulose of Formula I: in which i) lignocellulose is selected from the group consisting of: lignin; hemicelluloses; and cellulose; and ii) n is greater than 0 but less than 8000 mmoles/kg. The phosphorylated fibers are dispersed in an aqueous medium at a first temperature to produce an aqueous dispersion having a consistency. The phosphorylated fibers are dispersed for a predetermined time so as to enhance/increase water accessibility to the fiber wall, thereby causing fiber swelling.

What is claimed is: 
     
         1 . A method for producing lignocellulose nanofibrils from phosphorylated fibers, the method comprising:
 hydrolyzing an amount of phosphorylated fibers in which the phosphorylated fibers include a phosphorylated lignocellulose of Formula I:   
       
         
           
           
               
               
           
         
         in which
 i) lignocellulose is selected from the group consisting of: lignin; hemicelluloses; and cellulose; and 
 ii) n is greater than 0 but less than 8000 mmoles/kg, 
 
         the phosphorylated fibers being dispersed in an aqueous medium at a first temperature to produce an aqueous dispersion having a consistency, the phosphorylated fibers being dispersed for a predetermined time so as to enhance/increase water accessibility to the fiber wall, thereby causing fiber swelling. 
       
     
     
         2 . The method, according to  claim 1 , in which the predetermined time is from under 10 minutes up to about 120 minutes. 
     
     
         3 . The method, according to  claim 1 , in which the consistency is from less than 1% to 10% or more. 
     
     
         4 . The method, according to  claim 1 , further includes: applying a mechanical shear force to the previously treated fibers, in a second aqueous suspension having a pH of between about pH 3.0 to about pH 10.0, thereby isolating the lignocellulose nanofibrils as hydrogel. 
     
     
         5 . The method according to  claim 1 , in which the first temperature is from about 50 degrees Celsius to about 150 degrees Celsius. 
     
     
         6 . The method, according to  claim 1 , in which the hydrolyzing is a self-hydrolysis conducted in an open vessel at atmospheric pressure or in a pressure vessel either at atmospheric pressure or above atmospheric pressure. 
     
     
         7 . The method, according to  claim 1 , in which the self-hydrolysis can be performed at a consistency (grams of dry phosphorylated fibers/100 grams mixture of fibers and water) % range from less than 1% to 10% or more. 
     
     
         8 . The method, according to  claim 1 , in which the phosphorylated lignocellulose fibers have an equivalent charge density from less than 500 mmoles/kg up to about 8000 mmoles/kg. 
     
     
         9 . The method, according to  claim 1 , in which the self-hydrolysis is performed for a period from under 10 min to about 120 min. 
     
     
         10 . The method, according to  claim 1 , in which the phosphorylated fibers are selected from a group consisting of: sulfite, soda or Kraft pulps, regardless the fiber source, bleachability or refining status; thermomechanical pulp (TMP), old corrugated cardboard (OCC), and dissolving pulp (alpha cellulose). 
     
     
         11 . The method, according to  claim 1 , in which the lignocellulose is present in one or more of lignin, hemicelluloses and cellulose, and any combination thereof. 
     
     
         12 . The method, according to  claim 11 , in which the lignocellulose includes lignin present at from 0 to 30%, m/m. 
     
     
         13 . The method, according to  claim 11 , in which the lignocellulose includes hemicelluloses present at from 0 to 35%, m/m. 
     
     
         14 . The method, according to  claim 11 , in which the lignocellulose includes cellulose present at from 35 to 95%, m/m. 
     
     
         15 . The method, according to  claim 1 , in which n is an integer from 0 up to 8000 mmoles/kg wherein the concentration is calculated based on mmoles of equivalent phosphate charges contained in 1 kg of phosphorylated lignocellulose fibers. 
     
     
         16 . The method, according to  claim 1 , in which the nanofibrils are isolated in water as hydrogel through mechanical action with a device capable of generating a high shear stress. 
     
     
         17 . The method, according to  claim 16 , in which the device includes mixers, homogenizers, microfluidizers or a combination thereof, the device operating at an independent operating pressure.