Method for producing recycled pulp fibers, and recycled pulp fibers

Abstract

The purpose of the present invention is to provide a method for producing recycled pulp fibers such that articles using the recycled pulp fibers can easily achieve a uniform whiteness and users are not prone to feel psychological resistance to articles using the recycled pulp fibers. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port () to a treatment tank (), a mixed solution () which contains superabsorbent polymers and pulp fibers derived from multiple types of used sanitary products; a step for supplying an ozone-containing gas () from an ozone-containing gas supply port () to a treatment solution () inside of the treatment tank (); a step in which, by raising the ozone-containing gas () while lowering the superabsorbent polymers and pulp fibers in the treatment tank (), the ozone-containing gas () is brought into contact with the superabsorbent polymers and the pulp fibers, and the pulp fibers are bleached to form recycled pulp fibers; and a step for discharging the treatment solution () from a treatment solution discharge port (), wherein the recycled pulp fibers have a-ΔYI with respect to a standard white plate.