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Bohlin, Erik
Publications (10 of 14) Show all publications
Christophliemk, H., Bohlin, E., Emilsson, P. & Järnström, L. (2023). Surface Analyses of Thin Multiple Layer Barrier Coatings of Poly(vinyl alcohol) for Paperboard. Coatings, 13(9), Article ID 1489.
Open this publication in new window or tab >>Surface Analyses of Thin Multiple Layer Barrier Coatings of Poly(vinyl alcohol) for Paperboard
2023 (English)In: Coatings, ISSN 2079-6412, Vol. 13, no 9, article id 1489Article in journal (Refereed) Published
Abstract [en]

The hypothesis of the present study is that thin multiple layer coatings on paperboard from the aqueous solutions of poly(vinyl alcohol) (PVOH) at high machine speeds is more effective in terms of barrier properties than one or two thick layers. The objectives included attempts to use surface roughness parameters to understand the coating process and mechanisms behind coating defects. The present study is focused on pilot-scaled PVOH coating onto uncoated paperboard at machine speeds of 400 m/min. The multiple coating operation was carried out in six passes with a dry coat weight of about 1 g/m2 in each layer. The concept of thin multiple coatings resulted in coated surfaces without detected pinholes and with Kit rating 12 after only two thin layers. However, the oxygen transmission rates were still fairly high (100 & PLUSMN; 89 cm3/m2 day atm) after six layers, and some coating defects (such as craters and cracks) could be identified. The analyses of surface structure indicated that the surface properties are affected by water uptake during the coating processes. The compression of paperboard beneath the metering element seemed to be required to achieve homogeneous thin layers. However, an analysis of defects revealed flaws and inhomogeneities near objects protruding from the surface, such as surface fibers and craters, caused by blistering. For rough paperboard substrates, the desired barrier properties may require a careful balance between sufficient compression for fiber coverage and gentle compression in order to avoid defects near craters and surface fibers.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
paper coating, polyvinyl alcohol, barrier properties, multilayer coating, topographic analysis, morphological analysis
National Category
Paper, Pulp and Fiber Technology
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-97098 (URN)10.3390/coatings13091489 (DOI)001073385500001 ()2-s2.0-85172788749 (Scopus ID)
Available from: 2023-10-19 Created: 2023-10-19 Last updated: 2023-10-20Bibliographically approved
Bohlin, E., Johansson, C. & Lestelius, M. (2016). Flexographic ink-coating interactions: Effects of latex variations in coating layers. TAPPI Journal, 15(4), 253-262
Open this publication in new window or tab >>Flexographic ink-coating interactions: Effects of latex variations in coating layers
2016 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 15, no 4, p. 253-262Article in journal (Refereed) Published
Place, publisher, year, edition, pages
TAPPI Press, 2016
National Category
Chemical Sciences
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-30027 (URN)000382526700003 ()
Available from: 2013-11-15 Created: 2013-11-15 Last updated: 2019-07-09Bibliographically approved
Johansson, C., Bohlin, E. & Lestelius, M. (2016). Impact of coating composition and structure on print quality of flexographic printed paperboard. In: 14th TAPPI Advanced coating symposium proceedings: . Paper presented at 14th TAPPI Advanced coating symposium 4-6 Oct Stockholm Sweden (pp. 14-17). Peachtree Corners, GA: TAPPI Press
Open this publication in new window or tab >>Impact of coating composition and structure on print quality of flexographic printed paperboard
2016 (English)In: 14th TAPPI Advanced coating symposium proceedings, Peachtree Corners, GA: TAPPI Press, 2016, p. 14-17Conference paper, Oral presentation with published abstract (Other academic)
Place, publisher, year, edition, pages
Peachtree Corners, GA: TAPPI Press, 2016
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-46461 (URN)
Conference
14th TAPPI Advanced coating symposium 4-6 Oct Stockholm Sweden
Available from: 2016-10-13 Created: 2016-10-13 Last updated: 2020-07-02Bibliographically approved
Bohlin, E., Johansson, C. & Lestelius, M. (2014). Flexographic ink-coating interactions: effects of kaolin clay/GCCblends in coating layers. In: : . Paper presented at 41st International Research Conference of IARIGAI on Advances in Printing and Media Technology, September 7-10, Swansea, UK, 2014.
Open this publication in new window or tab >>Flexographic ink-coating interactions: effects of kaolin clay/GCCblends in coating layers
2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-34298 (URN)
Conference
41st International Research Conference of IARIGAI on Advances in Printing and Media Technology, September 7-10, Swansea, UK, 2014
Available from: 2014-10-13 Created: 2014-10-13 Last updated: 2019-07-09Bibliographically approved
Bohlin, E., Lestelius, M. & Johansson, C. (2013). Flexographic Ink-Coating Interactions: Effects of Porous Structure Variations of Coated Paperboard. Nordic Pulp & Paper Research Journal, 28(4)
Open this publication in new window or tab >>Flexographic Ink-Coating Interactions: Effects of Porous Structure Variations of Coated Paperboard
2013 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 4Article in journal (Refereed) Published
Abstract [en]

Ink transfer and ink penetration into a coated surface, and variations thereof, influences the print density, mottling and dot gain, which affects the achievable print quality and visual appearance. The pressure in the printing nip and the porosity of the substrate are conditions and properties that will regulate the amount of ink that penetrates into a porous coating structure. The purpose of this study was to relate print quality aspects to ink penetration of water-based flexographic ink into calcium carbonate based coatings of differently engineered structures. Pilot-coated paper-boards with different coating porosities were printed in a laboratory flexographic printer. Results indicate that ink transfer distribution is strongly affected by the roughness and the porosity of the substrate. A coating layer of broad pigment particle size distribution resulted in a lower print density, compared to coatings of narrowly distributed particle sizes. A structure characterized by larger pore volume and greater dominating pore radius, showed a higher amount of z-directional ink penetration, which was supported by estimating the penetration using a physical model accounting for both capillary- and pressure driven penetration. A coating with narrow particle size distribution also showed a lower dot gain.

Place, publisher, year, edition, pages
AB Svensk papperstidning, 2013
Keywords
Coating, Pigment, Calendering, Porosity, Flexographic Printing, Print quality
National Category
Chemical Sciences Materials Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-30026 (URN)000328642400012 ()
Available from: 2013-11-15 Created: 2013-11-15 Last updated: 2020-04-03Bibliographically approved
Bohlin, E. (2013). Surface and porous structure of pigment coatings: Interactions with flexographic ink and effects on print quality. (Doctoral dissertation). Karlstad: Karlstads universitet
Open this publication in new window or tab >>Surface and porous structure of pigment coatings: Interactions with flexographic ink and effects on print quality
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Each day, we are confronted with a large amount of more or less important information that we have to consider, and even in our digital society we need paper for communication, documentation and education. Much of the paper we use or are confronted by in our daily life, such as newspapers, books and packages, contains printed images or texts, and the appearance of both the print and the supporting surface is important. A good contrast between a printed text and the paper makes it easier to read, a detailed print of an illustration makes it more informative, and clear and evenly distributed colours on a package or on a poster make it more appealing. All of these qualities depend on the optical properties of the paper product and the the behavior of light illuminating the different materials.

The aim of the work described in this thesis is to characterize the structure of coatings and prints, and to validate models for the optical response and interaction of ink and coating based on optical measurements of physical samples. It is the interactions between the printing ink and the porous structure of the coating layers that are subject to investigation. Experiments have been employed to relate the physical conditions in a flexographic printing nip to the ink setting, affected by the physical and chemical properties of the coating, to the resulting optical response of the printed paperboard.

Abstract [en]

The aim of the work described in this thesis is to characterize the structure of coatings and prints, and to validate models for the optical response and interaction of ink and coating based on optical measurements of physical samples. It is the interactions between the printing ink and the porous structure of the coating layers that are subject to investigation. Experiments have been employed to relate the physical conditions in a flexographic printing nip to the ink setting and the resulting optical response.

By comparing simulated and measured results, it was shown that modifications of the surface properties account for the brightness decrease when substrates are calendered. Light scattering simulations, taking into account the surface micro-roughness and the increase in the effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease, whereas the bulk light scattering and light absorption coefficients were not affected by calendering.

Ink penetration affects the print density, mottling and dot gain. Results show that ink distribution is strongly affected by surface roughness, differences in pore size and pore size distribution. For samples having different latex amounts and different latex particle sizes, a higher print force did not increase the depth of penetrated ink to any great extent, but rather allowed the wetting to act more efficiently with a more evenly distributed ink film, a higher print density and fewer uncovered areas as a result. Uncovered areas could be linked both to local roughness variations and to local wettability variations on the surface. Samples with different ratios of calcium carbonate/kaolin clay pigment showed an increased porosity and an increase in print density with increasing amount of kaolin in the coating layer.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2013. p. 81
Series
Karlstad University Studies, ISSN 1403-8099 ; 2013:49
Keywords
Coating, Pigment, Calendering, Porosity, Flexographic Printing, Print quality
National Category
Paper, Pulp and Fiber Technology
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-30030 (URN)978-91-7063-528-1 (ISBN)
Public defence
2013-12-20, Rejmersalen 9C 204, Karlstads universitet, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2013-11-28 Created: 2013-11-15 Last updated: 2022-05-02Bibliographically approved
Bohlin, E., Johansson, C. & Lestelius, M. (2012). Evaluation of ink penetration in porous coatings. In: : . Paper presented at 8th International Paper and Coatings Chemistry Symposium 2012, Stockholm, Sweden, 10-14 June 2012 (pp. 321-324).
Open this publication in new window or tab >>Evaluation of ink penetration in porous coatings
2012 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Other Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-27158 (URN)
Conference
8th International Paper and Coatings Chemistry Symposium 2012, Stockholm, Sweden, 10-14 June 2012
Available from: 2013-05-03 Created: 2013-05-03 Last updated: 2019-07-09Bibliographically approved
Bohlin, E., Johansson, C. & Lestelius, M. (2012). Flexographic Ink-Coating Interactions, Effects of Porous Structure Variation of Coated Paperboard. In: : . Paper presented at 8th International Paper and Coatings Chemistry Symposium 2012, Stockholm, Sweden, 10-14 June (pp. 189-192).
Open this publication in new window or tab >>Flexographic Ink-Coating Interactions, Effects of Porous Structure Variation of Coated Paperboard
2012 (English)Conference paper, Published paper (Refereed)
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-6831 (URN)
Conference
8th International Paper and Coatings Chemistry Symposium 2012, Stockholm, Sweden, 10-14 June
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2017-12-06Bibliographically approved
Johansson, C., Bohlin, E., Coppel, L. & Edström, P. (2011). Modelling of coating brightness: Impact of micro-roughness and effective refractive index. Paper presented at ROND 2011 Digital Printing - Inkjet for industrial applications. Örnsköldsvik, Sweden, March 1, 2011. Paper presented at ROND 2011 Digital Printing - Inkjet for industrial applications. Örnsköldsvik, Sweden, March 1, 2011.
Open this publication in new window or tab >>Modelling of coating brightness: Impact of micro-roughness and effective refractive index
2011 (English)Conference paper, Published paper (Other (popular science, discussion, etc.))
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-10460 (URN)
Conference
ROND 2011 Digital Printing - Inkjet for industrial applications. Örnsköldsvik, Sweden, March 1, 2011
Available from: 2012-02-08 Created: 2012-02-08 Last updated: 2014-10-27Bibliographically approved
Bohlin, E., Coppel, L., Johansson, C. & Edström, P. (2010). Modelling of Brightness Decrease of Coated Cartonboard as an Effect on Calendering: Microroughness and Effective Refractive Index Aspects. In: TAPPI 11th Advanced Coating Fundamentals Symposium, Munich, Germany, 2010: Symposium Proceedings. Paper presented at TAPPI 11th Advanced Coating Fundamentals Symposium, Munich, Germany, 11-13 October 2010 (pp. 51-65). Norcross, GA, USA: TAPPI Press
Open this publication in new window or tab >>Modelling of Brightness Decrease of Coated Cartonboard as an Effect on Calendering: Microroughness and Effective Refractive Index Aspects
2010 (English)In: TAPPI 11th Advanced Coating Fundamentals Symposium, Munich, Germany, 2010: Symposium Proceedings, Norcross, GA, USA: TAPPI Press, 2010, p. 51-65Conference paper, Published paper (Refereed)
Abstract [en]

Calendering of coated paper leads to a brightness decrease. The mechanism for this is not clear, although it has been discussed in the past. One common explanation is that the porosity of the coating layer decreases and hence scattering. By comparing simulated and measured results this paper shows that modifications of the surface properties account for the brightness decrease of GCC coated substrates with calendering. The effect of a deformable cartonboard substrate is investigated here and compared to a less deformable plastic film substrate. From simulations based on a two-layer Kubelka-Munk model, it is shown that the brightness decrease of the cartonboard due to calendering has a negligible contribution to the brightness decrease of the coated cartonboard. The brightness decrease was similar for coated plastic film and coated cartonboard. The thickness of GCC coated plastic films was not affected by calendering irrespectively of the pigment and latex size distribution. Monte Carlo light scattering simulations, taking into account the measured decrease of surface microroughness and increased effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease of the GCC coated substrate, whereas the bulk scattering and absorption coefficients were not affected by calendering. It is also shown that the scattering coefficient is significantly dependent on the coat weight whereas the physical absorption coefficient is not.

Place, publisher, year, edition, pages
Norcross, GA, USA: TAPPI Press, 2010
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-6830 (URN)1-59510-203-5 (ISBN)
Conference
TAPPI 11th Advanced Coating Fundamentals Symposium, Munich, Germany, 11-13 October 2010
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2014-10-27Bibliographically approved
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