The effect of viscosity and surface tension on inkjet printed picoliter dots |
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Authors: | Sarah Krainer Chris Smit Ulrich Hirn |
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Affiliation: | Institute of Paper, Pulp and Fiber Technology, TU Graz, Inffeldgasse 23, 8010 Graz Austria, +43 316 87330753 ; CD Laboratory for Fiber Swelling and Paper Performance, Inffeldgasse 23, 8010 Graz Austria ; Océ, Van der Grintenstraat 1, 5914 HH Venlo Netherlands |
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Abstract: | In this study, we investigated the effect of liquid viscosity and surface tension for inkjet printing on porous cellulose sheets. We used five model liquids, representing the operational field of an industrial high speed inkjet printer, as specified by Ohnesorge- and Reynolds number. Drops with 30 pl and 120 pl drop size were jetted with a commercial HSI printhead. We printed on four uncoated papers representing the most relevant grades on the market in terms of hydrophobisation and surface treatment. We are presenting a quantitative analysis of viscosity and surface tension on the print outcome, evaluating dot size, liquid penetration (print through) and surface coverage of the printed dots. The most important finding is that for liquids within the jetting window the variation of the liquid viscosity typically has a 2–3 times higher impact on the print outcome than variation of the liquid surface tension. Increased viscosity in all cases reduces dot area, liquid penetration and liquid surface coverage. Surface tension plays a smaller role for liquid spreading and penetration, except for hydrophobised substrates, where both are reduced for higher surface tension. Interestingly, higher surface tension consistently increases liquid surface coverage for all papers and drop sizes. A detailed analysis on the competing effect of dot spreading and liquid penetration is presented, in terms of viscosity, surface tension and surface coverage of the liquid.In this study, we investigated the effect of liquid viscosity and surface tension for inkjet printing on porous cellulose sheets. |
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