engleski

Digital offset prints in the newsprint paper production

The use of waste paper as a source of raw material for the re-use of cellulose fibers plays an increasing role in the production of printing paper. Newsprint paper is partly produced from used fibers obtained from waste newsprints. One of the key procedures in the recycling process is the deinking flotation by means of which the printing ink particles are removed from defibrated pulp. Recycling changes the properties of cellulose fibers: they become harder, more brittle, breakable, less flexible and their swelling capacity is reduced. In consequence, the contact surface between the fibers is reduced and hydrogen bonds between them grow weaker. Therefore, the mechanical properties of paper from recycled fibers are inferior to those produced from primary fibers. The improvement of mechanical properties is one of the reasons for the inclusion of prints on paper from primary fibers in the production of newsprint paper. This study focused on the mechanical properties of laboratory handsheets obtained by recycling standard and digital offset prints on different substrates. The chemical deinking flotation was used. The proportion of conventional and digital offset prints in the mixture, both coated and uncoated, was varied for each study batch. The obtained results show that the tensile, tear and burst indices of such handsheets continuously fall with the increase of the share of digital offset prints in the recycling mixture. At the same time, there is an increase in the number of visible particle residues of ElectroInk from digital offset prints.The reduction of mechanical properties is explained by the presence of fillers and ink particles which did not separate from the pulp in flotation.

Recycled fibers; Conventional offset printing; Digital offset printing

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