To provide regenerated pulp using magnetic recording waste paper as a raw material, capable of being used as raw material pulp for magnetic recording paper, and given by using the magnetic recording waste paper as the raw material, without subjecting the waste paper to bleaching treatment, but to deinking treatment, nor to color control required as the magnetic recording paper.
This regenerated pulp using the magnetic recording waste paper as the raw material is produced by subjecting the waste paper to maceration treatment in an alkaline aqueous solution without being subjected to the bleaching treatment so as to give pulp slurry, subjecting the pulp slurry to kneading treatment in a pulp concentration of 20-40 wt.%, then subjecting the kneaded product to floatation separation and washing treatment, and repeating once or more a series of operations comprising the kneading treatment, the floatation separation, and the washing treatment, so as to produce the regenerated pulp, wherein the regenerated pulp has a freeness of ≥450 ml and an iron content of <50 ppm (based on the pulp), and base paper given by subjecting the regenerated pulp to papermaking has an area of black spots caused by ink and magnetic materials of <500 mm2/m2 and a color difference (ΔE) of <0.5.
WO/1996/016223 | DEINKING PROCESSES AND NOVEL POLYMERS FOR USE IN THESE |
HARA SHINICHI
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