Method for producing cellulose

Abstract

The process of the present invention for preparation of cellulose uses: chemical pulp; and a mixed solution containing 1.0% to 30.0% by weight of sulfuric acid, 0.5% to 40% by weight of hydrogen peroxide and 50.0% to 94.0% by weight of water, wherein the resulting cellulose has a polymerization degree of 350 or less and a brightness by Hunter of 90% or more.

1 . A process for preparing a cellulose, using:
 a chemical pulp; and   a mixed solution containing 1.0% to 30.0% by weight of a sulfuric acid, 0.5% to 40% by weight of a hydrogen peroxide and 50.0% to 94.0% by weight of a water,   wherein the cellulose has a polymerization degree of 350 or less and a brightness by Hunter of 90% or more.   
     
     
         2 . The process according to  claim 1 , wherein
 the mixed solution has a mix ratio of the sulfuric acid (x), the hydrogen peroxide (y) and the water (z), which is expressed by (x, y, z),   the (x, y, z) has a value present on a line or inside of a heptagon ABCDEFG, and   the heptagon ABCDEFG is formed by vertices A to G having the following (x, y, z) in a ternary diagram for the sulfuric acid (x)-hydrogen peroxide (y)-water (z):   A (3.0, 3.0, 94.0)   B (7.0, 0.5, 92.5)   C (24.0, 0.5, 75.5)   D (30.0, 3.0, 67.0)   E (30.0, 10.0, 60.0)   F (10.0, 40.0, 50.0)   G (1.0, 24.0, 75.0)   
       (wherein x, y and z each represent a ratio by weight, and x+y+z=100). 
     
     
         3 . The process according to  claim 2 , wherein the mix ratio (x, y, z) has
 a value present on a line or inside of a heptagon HICDEFG, provided that:
 the vertex A is replaced with a vertex H (3.0, 9.0, 88.0); and 
 the vertex B is replaced with a vertex I (6.0, 2.0, 92.0). 
   
     
     
         4 . The process according to  claim 2 , wherein the mix ratio (x, y, z) has
 a value present on a line or inside of a heptagon JKCDEFG, provided that:
 the vertex A is replaced with a vertex J (6.0, 9.0, 85.0); and 
 the vertex B is replaced with a vertex K (12.0, 3.0, 85.0). 
   
     
     
         5 . The process according to  claim 1 , comprising:
 mixing the sulfuric acid, the hydrogen peroxide and the water to prepare the mixed solution; and   soaking the chemical pulp in the mixed solution.   
     
     
         6 . The process according to  claim 1 , wherein a reaction temperature of the chemical pulp and the mixed solution is 60° C. to 110° C. 
     
     
         7 . The process according to  claim 5 , wherein the mixed solution is prepared by adding the sulfuric acid and the hydrogen peroxide to the water. 
     
     
         8 . The process according to  claim 5 , wherein the mixed solution is prepared by mixing the sulfuric acid, an aqueous hydrogen peroxide having a concentration of less than 50% by weight, and the water. 
     
     
         9 . The process according to  claim 1 , wherein the mixed solution contains a peroxymonosulfuric acid in a concentration of 0.01% to 25% by weight in the mixed solution. 
     
     
         10 . The process according to  claim 9 , wherein the concentration of the peroxymonosulfuric acid in the mixed solution is equal to or less than a concentration of the peroxymonosulfuric acid in an equilibrium solution containing a sulfuric acid, a hydrogen peroxide and a water. 
     
     
         11 . The process according to  claim 10 , wherein the concentration of the peroxymonosulfuric acid in the mixed solution is 0.01% to 17.1% by weight. 
     
     
         12 . Cellulose prepared by the process according to  claim 1 , having a polymerization degree of 350 or less and a brightness by Hunter of 90% or more.