For the first time, liquid toner prints in the raw material of a paper mill have caused a significant damage in a recycling paper mill. This incident confirms former lab tests that for the last ten years have pointed at a possible contamination already by small amounts of liquid toner prints.Water based inkjet ink is another challenge for the deinking process. This process has been designed to separate hydrophobic ink particles from hydrophilic cellulose fibers. Soluble dyes cannot be removed as they stay and accumulate in the circulation water. Thus additional bleaching steps have been suggested to make up for the loss in brightness. However, bleach is not an option for the majority of paper mills producing newsprint and other graphic papers from the household mix. It is neither economical nor ecological as one would have to add equipment and increase the use of chemicals as well as the chemical load of the effluent.Therefore, other solutions look more sustainable: inkjet inks that either are not water based or coagulate to form larger, hydrophobic particles on the paper surface. Promising approaches by KAO, Sepiax and Xerox have been tested whether this solution – originally intended to improve image quality – also helps to match state-of-the-art deinking technology.
Axel Fischer, "Recent developments in the Deinking of Inkjet and Liquid Toner" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP27), 2011, pp 719 - 721, https://doi.org/10.2352/ISSN.2169-4451.2011.27.1.art00080_2