FLUORESCENCE ELIMINATION OF FLUORESCENT DYE-CONTAINING OLD PAPER OR PAPERMAKING WHITE WATER

摘要

PROBLEM TO BE SOLVED: To provide a method for fluorescence elimination for old paper or papermaking white water containing a fluorescent dye, capable of obtaining a pulp having the same high quality as that of a virgin pulp or reducing water due to reuse of papermaking white water. SOLUTION: A kraft pulp is mixed with 3-50 wt.% of an old paper pulp which comprises old paper containing a fluorescent dye and is macerated, deinked or bleached at one or more parts in a chlorine-based bleaching process for a kraft pulp and subjected to fluorescence elimination treatment. Papermaking white water (A) containing a fluorescent dye is added to a chlorine-based white water (B) discharged from at least one parts in the chlorine-based bleaching process for kraft pulp in the weight ratio of the A/B of 1/1 to 1/100 is bleached and subjected to fluorescence elimination treatment.