Disintegration of Waste Office Paper by Kerosene for Improving Toner-Ink Liberation

Abstract

In waste office paper photocopied and printed by laser printers, toner ink is used as the printing medium and it cannot be decomposed in alkali by saponification different from the case of conventional oil ink. Therefore, to achieve a high degree of liberation, waste office paper has conventionally been comminuted to fine particles by strong agitation. However, this method not only makes toner so fine that separation becomes even more difficult but also makes it difficult to make high quality regenerated paper because the paper fibers are cut. In this study, a toner disintegration method by a relatively soft agitation force with the use of kerosene as a softening agent for toner ink has been investigated. The liberation degree of toner was 3.8 % by the conventional method using only NaOH and increased to 98.1 % by using undiluted kerosene and to 80.1 % by using 1 % kerosene suspension. As the remained toner parts were connected to only one or few paper fibers in these kerosene treatments, the liberation degree would become 100 % if these kinds of toner were also counted. The use of surfactants as dispersion agents for kerosene decreases the liberation degree because it interferes the softening of toner. It was also confirmed that an NaOH treatment in advance of the kerosene treatment is important to increase the liberation degree of toner.