METHOD FOR MANUFACTURING PULP FIBER FOR MAKING CELLULOSE NANOFIBER

PROBLEM TO BE SOLVED: To provide a method for manufacturing pulp fibers for making cellulose nanofibers， from pulp fibers contained in a used sanitary material. SOLUTION: There is provided a method for manufacturing pulp fibers for making cellulose nanofibers， from pulp fibers contained in a used sanitary material. The method includes a formation step of the pulp fibers for making cellulose nanofibers， in which the pulp fibers for making cellulose nanofibers having a lignin content rate of 0.1 mass% or less are formed from pulp fibers by supplying ozone-containing gas into a treatment tank 31 containing process liquid including pulp fiber inclusions 51 containing a super absorbent polymer and pulp fibers derived from the used sanitary material. SELECTED DRAWING: Figure 2