Cellulose fiber-containing material and method for producing cellulose fiber-containing material

Abstract

It is an object of the present invention to provide an ultrafine cellulose fiber-containing material having favorable re-dispersibility, which can exhibit excellent thickening properties after it has been re-dispersed, even after long-term storage. The present invention relates to a cellulose fiber-containing material comprising cellulose fibers having a fiber width of 1000 nm or less and a di- or more-valent metal component, wherein the content of the cellulose fibers is 5% by mass or more with respect to the total mass of the cellulose fiber-containing material, the content of the metal component is 0.5% by mass or less with respect to the total mass of the cellulose fiber-containing material, and when the cellulose fiber-containing material is processed into a slurry having a solid concentration of 0.5% by mass, the pH of the slurry is 4 or more.

1 . A cellulose fiber-containing material comprising cellulose fibers having a fiber width of 1000 nm or less and a di- or more-valent metal component, wherein
 the content of the cellulose fibers is 5% by mass or more with respect to the total mass of the cellulose fiber-containing material,   the content of the metal component is 0.5% by mass or less with respect to the total mass of the cellulose fiber-containing material, and   when the cellulose fiber-containing material is processed into a slurry having a solid concentration of 0.5% by mass, the pH of the slurry is 4 or more.   
     
     
         2 . The cellulose fiber-containing material according to  claim 1 , which further comprises a surfactant. 
     
     
         3 . The cellulose fiber-containing material according to  claim 2 , wherein the surfactant is a nonionic surfactant. 
     
     
         4 . The cellulose fiber-containing material according to  claim 1 , which further comprises a water-soluble organic compound. 
     
     
         5 . The cellulose fiber-containing material according to  claim 1 , which is a solid. 
     
     
         6 . The cellulose fiber-containing material according to  claim 1 , having a viscosity retention percentage of 10% or more, wherein the viscosity retention percentage is defined according to the following equation:
   Viscosity retention percentage (%)=slurry viscosity of sample after being left at rest at 23° C. for 240 hours/initial slurry viscosity of sample before storage x 100,
   provided that the slurry viscosity of the sample after being left at rest at 23° C. for 240 hours is a slurry viscosity obtained by leaving the cellulose fiber-containing material at 23° C. for 240 hours, then processing the cellulose fiber-containing material into a slurry having a solid concentration of 0.4% by mass, and then measuring the viscosity under conditions of 25° C. and a rotation number of 3 rpm, whereas the initial slurry viscosity of the sample before storage is a slurry viscosity obtained by processing the cellulose fiber-containing material into a slurry having a solid concentration of 0.4% by mass, and then measuring the viscosity under conditions of 25° C. and a rotation number of 3 rpm.   
     
     
         7 . A method for producing a cellulose fiber-containing material, comprising, in the following order,
 obtaining a dispersion comprising cellulose fibers having a fiber width of 1000 nm or less,   adding a di- or more-valent metal component to the dispersion,   adding an acid, and   adjusting pH, wherein   the adjusting pH is performing adjustment pH, so that when the cellulose fiber-containing material is processed into a slurry having a solid concentration of 0.5% by mass, the pH of the slurry can be 4 or more.   
     
     
         8 . The method for producing a cellulose fiber-containing material according to  claim 7 , wherein
 the adding a di- or more-valent metal component further comprises a filtering after completion of the addition of the di- or more-valent metal component, and   the adding an acid further comprises a filtering after completion of the addition of an acid.   
     
     
         9 . The method for producing a cellulose fiber-containing material according to  claim 7 , which further comprises a pulverization after completion of the adding an acid.