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Ink-paper interactions and effect on print quality in inkjet printing

This thesis concerns paper and ink interactions related to inkjet printing. The main purpose of this work was to gain a deeper understanding in which parameters control the flow of ink into papers and how the ink interacts with the paper surface. The overall objective was to find key parameters to optimize the print quality in inkjet printing. Characterization of paper-surfaces in terms of porosity, surface roughness and surface energy was made. Objective and subjective measurements were used for print quality evaluation. Light microscopy imaging and SEM was used to see how ink interacts with the paper surface in a printed image. A high speed camera was used to study the absorption of picolitre sized inkjet droplets into fine papers. An initial study on the effect of paper properties on print quality was made. Result indicated that there were small differences in print quality for pilot papers with different composition (in a specific parameter window) and the commercial paper COLORLOK® reproduced a noticeable high colour gamut compared to the other samples.Research was made to see how surface fixation can affect the print quality for printouts made with pigmented ink. Surface fixation promotes retention of the pigmented colorant in the outermost surface layer of the paper and has been denoted “colorant fixation” in this thesis. It was shown that applying colorant fixation onto a paper surface before printing can increase the detail reproduction in a printed image. Different concentrations of calcium chloride were applied onto the paper surface on fullscale produced non-commercial papers. Test printing was made with a SoHo (Small office/Home office) printer using pigmented ink and results showed that using calcium chloride as surface treatment can lead to aggregation of pigments at the surface resulting in a higher detail reproduction. Fast absorption of the carrier liquid into the paper and fast fixation of colourants on the surface is important in inkjet printing to avoid colour to colour bleeding. These demands will be more pronounced when the printing speed increases. It is important to understand which parameters affect the absorption process to be able to control the mechanisms and to optimize the print quality. A study of absorption of picolitre size inkjet droplets into fine paper was made in this work. Theoretical equations describing fluid absorption into capillaries were tested and compared with experimental results. The result showed that the time dependence in the Lucas-Washburn (L-W) equation fits fairly well to data whereas the L-W equation overestimates the penetration depth. The results are directly applicable to paper and printing industry and can be used as a base for future studies of absorption of picolitre sized droplets into porous materials and for studies of aggregation of colloidal particles on surfaces. / Presentationen hölls den 2011-02-25 / Next generation substrates for inkjet printing
Date January 2011
CreatorsLundberg, Anna
PublisherMittuniversitetet, Institutionen för informationsteknologi och medier, Sundsvall : Kopieringen Mittuniversitetet
Source SetsDiVA Archive at Upsalla University
Detected LanguageEnglish
TypeLicentiate thesis, comprehensive summary, info:eu-repo/semantics/masterThesis, text
RelationMid Sweden University licentiate thesis, 1652-8948 ; 57

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