engleski

Deinkability of Office Print-Outs

In Croatia, in the production of white top liner boards, the white ply is often made by deinking the offset printed wood-free paper grades. The prints that are used don't have high ink coverage in order to achieve as white deinked pulp as possible and clean visual appearance. Offset printed papers are generally highly deinkable, meaning that by conducting the deinking flotation process on those papers, it is possible to obtain desired visual properties of deinked pulp. On the other hand, certain types of digitally printed papers are not easily deinked using conventional deinking methods. Many studies that have been conducted proved that ink jet printed papers can not be successfully deinked. In the case of dye based ink jet inks, the dyes stain the fibers, resulting in lower luminosity of deinked pulp. Pigment based ink jet inks are also poorly deinkable. The insufficiently removed pigments and dyes can influence the visual appearance of deinked pulp, resulting in specs, low brightness and pronounced color shade. On the other hand, dry toners which are present in laser printers or copy machines can be deinked with satisfactory results. In this work the chemical deinking flotation was performed on several types of office print-outs printed by using digital printing techniques. By performing the laboratory deinking process on the chosen papers, the suitability of office paper grades as an alternative fiber supply in the production of white top linerboards was researched. The cleanliness of deinked pulp was evaluated by measuring the optical characteristics of obtained handsheets and by image analysis of ink particles in deinked pulp.

office print-outs; deinking flotation; digital printing

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