Anion-modified cellulose nanofiber dispersion liquid and composition

Abstract

The present invention provides a dispersion liquid of anion-modified cellulose nanofibers and a composition of anion-modified cellulose nanofibers that are not colored when heated. Specifically, the dispersion liquid contains anion-modified cellulose nanofibers; an anti-coloring agent selected from the group consisting of borate salts and sulfite salts, or combinations thereof in an amount of 1 to 30 mass % based on an absolute dry mass of the anion-modified cellulose nanofibers; and a solvent.

1 - 11 . (canceled) 
     
     
         12 . A dispersion of anion-modified cellulose nanofibers comprising:
 anion-modified cellulose nanofibers;   an anti-coloring agent selected from sulfite salts in an amount of 1 to 30 mass % based on an absolute dry mass of the anion-modified cellulose nanofibers; and   a solvent.   
     
     
         13 . The dispersion according to  claim 12 , wherein the anti-coloring agent comprises one or more compounds selected from sodium hydrogensulfite, potassium hydrogensulfite, ammonium hydrogensulfite, sodium sulfite, potassium sulfite, ammonium sulfite, sodium hyposulfite, potassium hyposulfite, calcium hyposulfite, sodium pyrosulfite, potassium pyrosulfite, magnesium pyrosulfite, or calcium pyrosulfite. 
     
     
         14 . The dispersion according to  claim 12 , wherein the anti-coloring agent comprises sodium hydrogensulfite. 
     
     
         15 . The dispersion according to  claim 12 , wherein the amount of the anti-coloring agent is 1 to 15 mass % based on an absolute dry mass of the anion-modified cellulose nanofibers. 
     
     
         16 . The dispersion according to  claim 12  having a pH of 6.5 to 10. 
     
     
         17 . The dispersion according to  claim 12 , wherein the anion-modified cellulose nanofibers have carboxyl groups in an amount of 0.5 to 2.0 mmol/g based on an absolute dry mass of anion-modified cellulose nanofibers. 
     
     
         18 . The dispersion according to  claim 12 , wherein the anion-modified cellulose nanofibers are carboxymethylated cellulose nanofibers having a degree of carboxymethyl substitution of 0.01 to 0.50 per a glucose unit of anion-modified cellulose nanofibers. 
     
     
         19 . The dispersion according to  claim 12 , wherein the anion-modified cellulose nanofibers are reduced by a reducing agent. 
     
     
         20 . The dispersion according to  claim 12 , wherein the anion-modified cellulose nanofibers have an average fiber length of 50 to 2000 nm, and an average fiber diameter of 2 to 50 nm. 
     
     
         21 . A composition of anion-modified cellulose nanofibers obtained by removing a solvent from the dispersion of anion-modified cellulose nanofibers according to  claim 12 . 
     
     
         22 . A method of manufacturing the dispersion according to  claim 12 , the method comprising:
 (i) oxidizing a cellulose material in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromides and iodides, or mixtures thereof to prepare oxidized cellulose;   (ii) defibrating the oxidized cellulose to obtain a dispersion of oxidized cellulose nanofibers; and   (iii) adding an anti-coloring agent selected from sulfite salts to the oxidized cellulose obtained in (i) or the dispersion of oxidized cellulose nanofibers obtained in (ii).   
     
     
         23 . A method of manufacturing the composition according to  claim 21  comprising:
 (i) oxidizing a cellulose material in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromides and iodides, or mixtures thereof to prepare oxidized cellulose; 
 (ii) defibrating the oxidized cellulose to obtain a dispersion liquid of oxidized cellulose nanofibers; 
 (iii) adding an anti-coloring agent selected from sulfite salts to the oxidized cellulose obtained in (i) or the dispersion of oxidized cellulose nanofibers obtained in (ii); and 
 (iv) removing the water from the dispersion of oxidized cellulose nanofibers. 
 
     
     
         24 . A sheet containing the composition according to  claim 21 .