Deinking Agent for Waste Paper

Abstract

Waste papers are recycled by deinking. All over the world, the flotation method is the mainstream as the deinking method because of the advantages such as higher pulp yield, less use of water, less area for installation and less total reagent cost. The flotation method is mainly consisted of pulping and flotation processes, the former for ink separation from cellulose, the latter for ink rejecting out from the system. Function to assist the mechanical separation of printing ink from cellulose is required for the deinking agent in the pulping process. In the flotation process, there are three particles, namely, ink, cellulose and bubble, and main four interaction between them in the flotation cell. The following relationship must be held to reject out the ink particles effectively. Vr0<Vr1<<Vr2<Vr3 where Vr0, Vr1, Vr2 and Vr3 are the repulsive energy between ink and ink, ink and bubble, ink and cellulose and cellulose and bubble, respectively. The deinking agent in the flotation process must be that to control the repulsive energy following the relationship as mentioned above. The deinking agent which possesses the above-mentioned function can be designed from viewpoint of surface science.