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Flexographic print quality of pilot coated paperboards
Karlstad University, Faculty of Technology and Science.
Karlstad University, Faculty of Technology and Science.
Karlstad University, Faculty of Technology and Science.
(English)Manuscript (Other academic)
Identifiers
URN: urn:nbn:se:kau:diva-1928OAI: oai:DiVA.org:kau-1928DiVA: diva2:5046
Available from: 2007-10-19 Created: 2007-10-19 Last updated: 2010-08-31Bibliographically approved
In thesis
1. Some aspects on flexographic ink-paper and paperboard coating interaction
Open this publication in new window or tab >>Some aspects on flexographic ink-paper and paperboard coating interaction
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Flexographic printing is a process that employs a flexible printing form and low viscous ink, often water-based. The flexible printing form is favourable for printing on rough surfaces, but the high surface tension of the ink may cause printability problems.

This work has focused on the interaction between paper/paperboard coating and water-based flexographic ink, aimed at increasing the knowledge about the printing process in form of physical/chemical parameters that are important for ink setting. The effects of printing conditions on print quality, such as printing pressure and temperature, have also been in focus.

The work has shown that fluids of different polarities, i.e. different dipole moments, behave differently when being absorbed by a coating layer. Due to their chemical compatibility to the coating layer, fluids with large dipole moment fill the pore matrix of the coating to a lesser extent but penetrate further into the coating than fluids with small dipole moments. On the other hand, polarity of the coating layer also affects the print. When printing on coatings with different polarities, higher print densities was obtained on the more polar substrates. As a tentative explanation, it is proposed that the ink builds different layer structures during drying depending on the coating polarity.

Print gloss is related to the ink setting which, in turn, is affected by the solvent retaining capacity of the ink. Large water holding capacity allows the ink components to smoothen out before the structure is set, resulting in a higher print gloss. The rheology of inks is affected by temperature; at a higher temperature the viscosity is reduced. The reduction in ink viscosity at higher temperature has been shown to affect the print quality, e.g., print density and dot gain. It is suggested that a thicker layer is immobilised during impression due to the lower viscosity and that it is an explanation of the higher print density at a higher printing temperature.

The influence of impression pressure on dot gain has been experimentally evaluated and mathematically modelled with good agreement. The dot gain is shown to respond non-linearly to the applied printing pressure.

Studies based on pilot coated and printed paperboards is also reported, and it is shown that the print quality, e.g. print density, print gloss and dot gain, is largely dependent on the type of ink chosen and on the coating characteristics. Higher clay content in the coating resulted in increased dot gain and a decreased mottling.

Place, publisher, year, edition, pages
Fakulteten för teknik- och naturvetenskap, 2007
Series
Karlstad University Studies, ISSN 1403-8099 ; 2007:23
Keyword
Flexography; Ink; Coating; Paperboard; Printing
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-1218 (URN)978-91-7063-126-9 (ISBN)
Public defence
2007-11-09, Sjöströmsalen, 1B 309, Karlstad, 09:00
Opponent
Supervisors
Available from: 2007-10-19 Created: 2007-10-19 Last updated: 2015-10-13

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
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Output format
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  • text
  • asciidoc
  • rtf