March 2020

A letter from the Editor
Gorazd Golob

Editor-in-chief

The first issue of 9th volume of the Journal comes at a time when the Covid-19 pandemic was proclaimed in the world, and most of us work at home, keeping a close eye on what is happening and hoping that we, our loved ones, friends and colleagues will bypass the disease and normalize our daily lives as soon as possible. The pandemic also influenced the work of the authors, reviewers, and editors of the present issue, but the final result definitely reflects the quality and committed work of all involved.
In the first original scientific paper, the authors present a new, relatively simple but effective method of determining the contact area of paper under surface load, which is also a measure of other significant surface properties of paper. Added value to the article is the derivation of the mathematical model for determining the contact area, the modulus, and the stress–strain characteristic of the paper.

The following research paper considers the aerosol jet deposition technique as an alternative to established printing techniques, for printing with conductive silver ink. By optimizing the process and the print parameters, the resolution and quality of the prints were achieved, proving it also suitable for applications in printed electronics.

The final research paper presented is devoted to comparing infrared and Raman microscopic methods for the analysis of offset ink absorption in the paper. The advantage of Raman microscopy is demonstrated, including for the analysis of the penetration of mineral oil from printing ink into paper.
There are some changes to the Topicalities published this time. The Editor Markéta Držková (marketa.drzkova@jpmtr.org), has for the first time included a more extensive critical book review, written by Patrick Gane, a renowned expert and long-time contributor to the Journal. I hope that publishing critical reviews of important publications in the fields covered by the Journal will become an ongoing practice.

As usual, Topicalities has published news, this time dedicated mainly to patents in the field of electrically conductive inks, which also include inks and toners used in electrography, listed in the same subcategory according to international patent classification. The support from many companies in the field helping to tackle the impact of current situation is also briefly presented. A related thought of Patrick Gane was that “for those seeking access to software and systems at this extraordinary time the message is it is worth researching what is available.” I would just like to add that this statement is true also on many other occasions in our life. In addition to the aforementioned review of the book Wetting and Spreading Dynamics, in the Bookshelf some other newer books are presented in the Bookshelf, this time mainly from the fields of colorimetry, design, textiles, lithography (for chip-making), nanomaterials and technologies, and 3D printing.

Among the authors of the presented theses, there are two who have already co-authored contributions to the International Research Conference of iarigai and in the Journal.

Arash Hakimi Tehrani successfully defended his thesis in indirect gravure print-ing at the Technical University of Darmstadt, Germany. The research focused on the characterization and optimization of rubber pads when printing to 3D objects and the automation of the process itself.
Araz Rajabi Abhari completed his doctoral study at Seoul National University, South Korea. He has researched coating color formulations and their influence on the final surface and mechanical properties of coated papers.

Also, Felipe Clement Fernandes completed his thesis at the Technical University of Darmstadt, Germany. He has researched security elements and forms of stochastic printed patterns, counterfeiting technology, and further identification, analysis, and validation of samples by means of image processing.

The final overview of Events is shorter than usual. Many forums, conferences, seminars, and other events have been canceled or postponed, however, some organizers have opted for online or virtual events, including ePoster sessions with online chats and discussions. Also, the 47th International Research Conference of iarigai at Clemson University in Greenville, SC, USA, planned for September 2020 was postponed, unfortunately. The authors who already submit-ted their extended abstracts and all other members of our community are invited to present and publish the results of their research work as original scientific or research papers in the Journal. Since 2020, the Journal is a fully open-access publication. Every submitted paper will be double-blind reviewed and edited before publication, with no charge to the authors; these aspects remain unchanged.

Many of us are now working from home to help avoid the virus and prevent Covid-19 pandemic, but it is also an opportunity to stay active as authors, reviewers, and collaborators to the Journal. Stay healthy and be active from home or from your institution if your presence there is allowed by the authorities and is safe for you.

Ljubljana, March/April 2020

Compressive stress–strain behavior of paper material affected by the actual contact area

Jian Chen1, Edgar Dörsam2, Jann Neumann3 and Simon Weißenseel2

E-mails: chenjian.tud@hotmail.com; doersam@idd.tu-darmstadt.de; neumann@perfecta.de; Simon.Weissenseel@alcon.com

1 School of Mechanical Engineering, Yangzhou University,
Huayang Weststr. 196, 225127 Yangzhou, China

2 Institute of Printing Science and Technology,
Darmstadt University of Technology,
Magdalenenstr. 2, 64289 Darmstadt, Germany

3 Perfecta Cutting Systems GmbH, Schäfferstr. 44, 02625 Bautzen, Germany

Abstract

The surface topography plays a very important role in the mechanical behavior of paper materials, especially for the compressive properties of thin sheet. When the surface of the cylindrical indenter is very smooth, the actual contact area under force is usually much smaller than the nominal contact area because of the surface roughness of the paper. This paper shows a method for measuring the actual contact area; with the aid of a microscope, a new approach based on image processing technique is presented to calculate the relationship between force and actual contact area. With the help of this method, the actual pressure–deformation relation and the actual modulus of paper could also be calculated. The calculation results show that there is an obvious difference between the results calculated by actual and nominal contact area. The varied trend and the values of the actual modulus are also obtained; at the beginning of the loading the actual modulus is decreasing and then close to a constant value. The universal testing machine Zwick Z050 and the optical surface topography measuring machine Sensofar Plu Neox were employed to determine not only the strength and deformation performance but also the surface roughness of specimen. Based on the obtained results the influence of carbon paper on the compressive behavior of copy paper is further discussed from different standpoints. The numerical results demonstrate the feasibility and effectiveness of the new method.

Keywords: carbon paper, copy paper, stress–strain curve, compression modulus, surface topography

JPMTR 129 | 1911 Original scientific paper
DOI 10.14622/JPMTR-1911
UDC 676.2:621.5:531.2(182)

Received: 2019-10-28
Accepted: 2020-03-25

Optimisation of aerosol jet deposition for high-resolution selective patterning of silver tracks

Ben Clifford, Chris Phillips and Davide Deganello

E-mails: b.r.clifford@swansea.ac.uk; c.o.phillips@swansea.ac.uk; deganello@swansea.ac.uk

Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Fabian Way, Swansea, SA1 8EN, UK

Abstract

Aerosol jet deposition is a digital direct­write additive manufacturing technique capable of producing high resolution and highly customisable electronic and biological functional devices on both two- and three-dimensional substrates. This technology offers important market opportunities in the production of consumer electronics, semiconductor packaging, display technology, aerospace and defence, automotive and life sciences. However, for these opportunities to be realised there is a necessity for greater understanding of how deposition process parameters influence deposition quality. This study has explored the effects of a number of these parameters and their influence on the geometry of printed features. The results of this work outline the operating windows for several deposition parameters including carrier gas flow rate, stage speed working distance and stage temperature. Additionally, a number of relationships have been identified linking deposition parameters to the geometry of printed features.

Keywords: printed electronics, high­resolution printing, metal printing, parameter optimisation, surface topography

JPMTR 130 | 1914 Research paper
DOI 10.14622/JPMTR-1914
UDC 651.5:546.57|7.048

Received: 2019-12-25
Accepted: 2020-03-26

The use of infrared and Raman microscopy to characterise the absorption of offset ink in paper

Alexandra Hodes1,2, Simon Hamblyn1,2, Matthias Schmidt3, Ulrike Käppeler1,2, Andrea Berlich4, Andrea Prager5 and Lutz Engisch1

E-mails: alexandra.hodes@htwk-leipzig.de; simon.hamblyn@htwk-leipzig.de; matthias.schmidt@ufz.de; ulrike.kaeppeler@htwk-leipzig.de; andrea.berlich@htwk-leipzig.de; andrea.prager@iom-leipzig.de; lutz.engisch@htwk-leipzig.de

1 Leipzig University of Applied Sciences (HTWK Leipzig),
Faculty of Computer Science and Media, Germany

2 iP³ Leipzig – Institute for Printing, Processing
and Packaging Leipzig at HTWK Leipzig, Germany

3 ProVIS – Centre for Chemical Microscopy at Helmholtz
Centre for Environmental Research GmbH – UFZ / Department of Isotope Biogeochemistry, Germany

4 Leipzig University of Applied Sciences (HTWK Leipzig),
Mathematical-scientific center, Germany

5 The Leibniz Institute of Surface Engineering (IOM), Germany

Abstract

Previous studies have detected traces of mineral oils in food packaged in paperboard packaging, with the migration of the ink oil used on the outside of the packaging identified as a potential source of this contamination. This study exam-ined the use of both infrared (IR) microscopy and Raman microscopy to evaluate their use in the detection of mineral oil migration from an offset printing ink through a bespoke set of laboratory made paper hand sheet samples. The IR microscopy was found to be largely unsuitable for this type of investigation due to the low IR reflectance of the mate-rials used in the paper and the ink. Raman microscopy was able to clearly distinguish between the different ink and paper components and therefore characterise the migration within the paper samples. The initial results showed that the use of calcium carbonate pigments as a filler reduced the migration of mineral oil through the paper. For the coated papers, the majority of the mineral oil was detected within same region as the coating. This was in agreement with other studies that have examined the absorption of ink oils into the pore network of calcium carbonate paper coatings.

Keywords: food packaging, migration, mineral oil, paper filler, paper coating

JPMTR 2002 Research paper
DOI 10.14622/JPMTR-2002
UDC 535.3|53.086-028.25

Received: 2020-03-23
Accepted: 2020-03-31