Method for producing cellulose fine fiber

Abstract

A method of producing cellulose fine fibers that are nanosized, that have a high crystallinity degree, and that are less vulnerable to fiber shape damage, the method including impregnating cellulose with a fibrillation solution containing formic acid to fibrillate the cellulose without vigorous mechanical crushing. The method of producing cellulose fine fibers including impregnating the cellulose with formic acid, a high-concentration formic acid aqueous solution, or a solution containing, in an aprotic solvent having a donor number of 26 or more, formic acid or a high-concentration formic acid aqueous solution serving as a fibrillation solution to fibrillate the cellulose. In addition, a method of producing surface-modified cellulose fine fibers including impregnating the cellulose with the fibrillation solution to modify the surfaces of cellulose fine fibers while fibrillating the cellulose.

1 . A method of producing cellulose fine fibers, comprising impregnating cellulose with formic acid or a high-concentration formic acid aqueous solution to fibrillate the cellulose. 
     
     
         2 . A method of producing cellulose fine fibers, comprising impregnating cellulose with a fibrillation solution containing an aprotic solvent having a donor number of 26 or more and formic acid or a high-concentration formic acid aqueous solution to fibrillate the cellulose. 
     
     
         3 . A method of producing surface-modified cellulose fine fibers, comprising impregnating cellulose with a modification-reactive fibrillation solution, which is obtained by adding a cellulose modification reaction agent to formic acid, a high-concentration formic acid aqueous solution, or the fibrillation solution of  claim 2 , to fibrillate the cellulose. 
     
     
         4 . The production method according to  claim 3 , wherein the cellulose modification reaction agent comprises at least one kind selected from a carboxylic acid halide, a carboxylic acid anhydride, a carboxylic acid, an isocyanate, and an epoxy. 
     
     
         5 . The production method according to  claim 1 , wherein a weight ratio of the cellulose to the formic acid or the high-concentration formic acid aqueous solution is from 0.5/99.5 to 25/75. 
     
     
         6 . The production method according to  claim 2 , wherein a weight ratio of the cellulose to the fibrillation solution is from 0.5/99.5 to 25/75. 
     
     
         7 . The production method according to  claim 3 , wherein a weight ratio the cellulose to the modification-reactive fibrillation solution is from 0.5/99.5 to 25/75. 
     
     
         8 . The production method according to  claim 4 , wherein a weight ratio of the cellulose to the modification-reactive fibrillation solution is from 0.5/99.5 to 25/75.