Anionically surface treated inkjet and flexographic inks and their deinkability

Abstract

Prerecycling of water-based flexographic ink and water-based thermal inkjet inks was explored. Model laboratory formulated water-based flexographic and commercial water-based thermal inkjet inks were used in experiments using solely wet or dry inks. The goal was to optimize ink detachment during repulping and at the same time assure its minimal ink redeposition. Ink’s behavior was examined under a wide pH range. An alkaline environment is desirable for complete ink detachment from the printed substrate, whereas the benefit of an acid environment is the agglomeration of the pigment in water-based ink. Deinking would be most efficient if executed in two steps: first, alkaline to detach most of the alkaline water-based ink and second, acidic to maintain detached ink coagulated. Acidic pH has the ability to agglomerate the pigment, once it is detached and present in deinking waters. However, such a recycling protocol is likely not achievable in current recycling plants.