Composition

Abstract

A composition provides a high-bulk cellulose fiber-containing sheet, in which the water-retaining ability of the cellulose fibers is sufficiently high, and the water-absorbing rate is large. The composition contains cellulose fibers having phosphoric acid groups or phosphoric acid group-derived substituents. In at least a part of the cellulose fibers, the phosphoric acid groups or the phosphoric acid group-derived substituents are crosslinked. The number of crosslinking points in the cellulose fibers, which is calculated according to the following Equation (1), is 0.20 mmol/g or more, and the water content is 50% by mass or less, with respect to the total mass of the composition: Number of crosslinking points=(amount of strongly acidic groups contained in cellulose fibers−amount of weakly acidic groups contained in cellulose fibers)/2 . . . Equation (1).

1 . A composition comprising cellulose fibers having phosphoric acid groups or phosphoric acid group-derived substituents, wherein
 in at least a part of the cellulose fibers, the phosphoric acid groups or the phosphoric acid group-derived substituents are crosslinked,   the number of crosslinking points in the cellulose fibers, which is calculated according to the following Equation (1), is 0.20 mmol/g or more, and   the water content is 50% by mass or less, with respect to the total mass of the composition:
   Number of crosslinking points=(amount of strongly acidic groups contained in cellulose fibers−amount of weakly acidic groups contained in cellulose fibers)/2  Equation (1).
 
   
     
     
         2 . The composition according to  claim 1 , which is a non-woven fabric. 
     
     
         3 . The composition according to  claim 1 , wherein when the composition is processed into a rectangular sample having a width of 5 mm and a length of 50 mm, then, an edge region ranging from the end of the rectangular sample in the longitudinal direction to 5 mm from the end is immersed in ion exchange water (electrical conductivity: 2 μS/cm or less), and then, the time required for the ion exchange water to reach from the end of the longitudinal direction to a distance of 45 mm in the longitudinal direction is measured, a water-absorbing rate (mm/sec), which is calculated according to the following Equation (2), is 2.5 mm/sec or more and 100 mm/sec or less:
   Water-absorbing rate (mm/sec)=40 (mm)/ t  (sec)  Equation (2)
 
 wherein t represents the time (sec) required for the ion exchange water to reach from the end of the rectangular sample in the longitudinal direction to a distance of 45 mm in the longitudinal direction. 
 
     
     
         4 . The composition according to  claim 1 , wherein the amount of the strongly acidic groups contained in the cellulose fibers is 1.60 mmol/g or more. 
     
     
         5 . The composition according to  claim 1 , wherein the water retention capacity (%) of the cellulose fibers, which is calculated according to the following equation, is 150% or more:
   Water retention capacity (%)=(weight of cellulose fibers after centrifugation treatment−absolute dry weight of cellulose fibers)/absolute dry weight of cellulose fibers×100,
   wherein, in the above equation, the water retention capacity is measured in accordance with SCAN-C 62:00, and conditions for the centrifugation treatment are determined to be 20° C. and weight acceleration upon the centrifugation of 3950 g, and 15 minutes.