Cellulose microfibers and method for manufacturing the same

Abstract

A method is for manufacturing cellulose microfibers in which a problem of yellowing of cellulose microfibers to be obtained was solved, and cellulose microfibers. As to a method for manufacturing cellulose microfibers, cellulose fibers are added with an additive (A) consisting of at least one of a phosphorous acid and a metal phosphite and an additive (B) consisting of at least one of urea and a urea derivative, heated and washed, then fibrillated. Also, as to cellulose microfibers, the fiber width is 1 to 1000 nm, and a part of hydroxy groups of cellulose fibers is substituted with a functional group represented by a predetermined structural formula to introduce an ester of phosphorous acid.

1 . A method for manufacturing cellulose microfibers comprising:
 adding an additive (A) consisting of at least one of a phosphorous acid and a metal phosphite and an additive (B) consisting of at least one of urea and a urea derivative to cellulose fibers;   heating and washing; and   fibrillating the cellulose fibers to obtain cellulose microfibers, wherein   the B-type viscosity when the concentration of cellulose microfibers is 1% by mass (w/w) measured on a dispersion in accordance with JIS-Z8803 (2011) is 10 to 300,000 cps.   
     
     
         2 . The method for manufacturing cellulose microfibers according to  claim 1 , wherein
 a carbamate is introduced to a part of hydroxy groups of the cellulose fibers until a degree of substitution ranges from 0.01 to 0.50.   
     
     
         3 . The method for manufacturing cellulose microfibers according to  claim 1 , wherein
 the axial ratio (fiber length/fiber width) of the cellulose microfibers is 3 to 1,000,000 by the fibrillation.   
     
     
         4 . The method for manufacturing cellulose microfibers according to  claim 1 , wherein
 the heating is performed at 100 to 210° C.   
     
     
         5 . The method for manufacturing cellulose microfibers according to  claim 1 , wherein
 the transparency (transmittance of 350 to 880 nm light) of a 0.2% (w/v) cellulose microfiber dispersion is 40.0% or more.   
     
     
         6 . The method for manufacturing cellulose microfibers according to  claim 1 , wherein
 the additive (A) consists of sodium hydrogen phosphite.   
     
     
         7 . Cellulose microfibers, wherein
 a fiber width is 1 to 1000 nm, and   a part of hydroxy groups of cellulose fibers is substituted with a functional group represented by the following structural formula (1) to introduce an ester of phosphorous acid and to introduce a carbamate to a part of hydroxy groups of the cellulose fibers until a degree of substitution ranges from 0.01 to 0.50:   
       
         
           
           
               
               
           
         
         where α is any of none, R, and NHR, R is any of a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group, an aromatic group, and derivative groups thereof, and β is a cation consisting of an organic substance or an inorganic substance. 
       
     
     
         8 . The cellulose microfibers according to  claim 7 , wherein
 the β is sodium ion, and   sodium salt of a phosphorous acid ester is introduced.