Surface Chemistry of Deinking Process : Correlation between Surface Free Energy of Ink and Deinking Agent on Office Waste Deinking

摘要

The surface properties of four types of inks (toner ink, inkjet ink, offset newsprint ink and heat-off-set ink) and their effects on office waste deinking were investigated with regard to the surface tension of deinking agents. The surface free energy of those inks was determined from the measured contact angles and surface tensions of probe liquids using the Lifshitz-van der Waals/acid-base approach. All of the tested inks were characterized as having low-energy surfaces and the major contribution was derived from the Lifshitz-van der Waals component. Among them the toner ink had the lowest surface energy whereas the inke=jet ink had the highest energy. The contact angles of deinking agents on the ink decreased as the surface tension of deinking agents decreased. On the other hand, the deinking experiments indicated that detachment efficiency of the inks from the newspaper and copy paper became highest when the surface tension of deinking agent was similar to the Lifshitz-van der Waals surface energy component of the inks. Furthermore, the hairy toner/clean toner ratio, which was calculated by visual microscopic observation, showed that the deinking agents, which gave better toner ink detachment, facilitated toner ink break down. It was concluded that the surface energy is an important parameter in office waste deinking.