Displacement washing deinking of water-based inks

The displacement of ink by water from pads prepared from aqueous mixtures of bleached kraft fibres and colloidally dispersed flexographic ink was investigated as a function of the concentration of calcium ion and sodium oleate. Washing efficiency was assessed from breakthrough curves based on filtrate analyses and on measurement of pad brightness after washing. During thickening, water-based ink retention in the pad was promoted by the presence …