Deinking of inkjet prints

Abstract

The study investigates the deinkability of inkjet printed products and shows the influence of printing paper and inkjet ink on deinkability. Test prints were produced on high-volume inkjet printing systems using different papers but the same image and print settings. Tests included a standard laboratory deinking procedure for ink removal (INGEDE Method II) as well as a VOITH test method of pulp bleaching, applying standard bleaching agents and chemical concentrations. Assessment of deinking results was based on the deinking scorecard promoted by the European Recovered Paper Council. The tests showed good deinkability for 70% of the test prints with pigment-based inkjet inks and their deinkability was clearly influenced by the printing paper. In contrast, deinking of dyebased inkjet prints was strongly influenced by both the type of paper and iniget ink (only 20% of the test prints showed good deinkability). All dyes, however, were capable of being bleached by common reductive bleaching agents. It was further shown that the deinkability of a recovered paper mix containing inkjet prints depends on the type and proportion of inkjet print products. The study also identified paper properties (surface tension, paper components) that are responsible for good or poor deinkability. ©2013; Society for Imaging Science and Technology.