A letter from the Editor
The first three months of this year, among other things, were marked by the new iarigai website <http://iarigai.com/publications/journals/> where all the published issues of the Journal are available, including the last one you are reading now. The new website is also adapted to modern mobile devices, and it was designed in accordance with the requirements and expectations of the Board of iarigai. As with any such operation, of course, some technical issues also occur, but we are continually removing them. The publishing policy and rules for accessing the password protected pdf files of the Journal remain unchanged, the archival copies are available to everyone free of charge, and the last two issues are accessible only for iarigai members and subscribers. According to the first responses and established trends, additional options will be offered, especially separate access to individual papers, of course under the conditions mentioned above. It is too early to talk about other changes, but it is our common interest that the Journal is a well-seen and accessible communication channel for publishing scientific and research papers in the field of graphic arts and media technology.
The first of the three papers in this issue deals with the impact of the uneven absorption of the printing ink in flexography on the print quality. Extensive and in-depth research includes mainly the analysis of the influence of roughness, porosity, and absorbency on the formation of mottling as one of the key quality parameters in the printing on coated cardboard. The extensive set of methods used to characterize the properties of materials and final imprints, and above all their comprehensive evaluation, gives added value to this publication.
The second paper is the research report of the study on the possibility of introducing a new biopolymeric material based on glucomannan. Various possibilities of preparing samples and some basic properties of the potential barrier material for food packaging are presented, in particular, the vapor transmission rate, moisture properties, surface properties, and solubility.
In the third paper, the authors discuss the case of the influence of various factors in the process of lamination of plastic films, which are used primarily as printed packaging materials. The Fuzzy Logic method is briefly presented and some examples of its application are given for individual factors that influence the quality of the laminating process.
In the current Topicalities section, edited by Associate Editor Markéta Držková (firstname.lastname@example.org), an excerpt of interesting patents awarded to well-known printing presses manufacturers is presented, together with market reports from Smithers Pira and new printing solutions presented by Saralon. Interesting is the review of new books in a wide range from mathematics to typography, including manuals for the production of a conference poster and for the writing and publication of a scientific paper. The latter can be used as extensive Guidelines for authors for future contributions to the Journal.
The three Theses presented are substantively as well as geographically quite different. The doctoral degree in the field of researching new business models for digital news publishing was successfully defended by K. Lindskow at the Copenhagen Business School; at the University of São Paulo, I. Ribeiro Aragão received a doctoral degree for her study of Brazilian typographic history; while S. Holúbková completed doctoral thesis on the paper deacidification process evaluation at the Institute of Natural and Synthetic Polymers in Bratislava.
The large number of announced conferences, fairs, workshops and other events, and in particular their scope and the expected number of participants, shows that the scientific research, as well as the business activity covered by the Journal is in good shape and, of course, very interesting for all researchers and experts. For those of them who deal with classical printing business of books and periodicals and the media, the most interesting topics are covered by the London Book Fair and WAN-IFRA events. For the others, there is an overview of events from the areas of printed electronics, industrial and functional printing, packaging, photonics, colors and light, etc.
From all above-mentioned areas, we received several papers for publication in the following issues of the Journal. An additional incentive for the authors and all other participants in the publishing process is also the confirmation that from this year the Journal is indexed by Scopus, however, it will appear on the indexed journal list at the next update. This is good news for all authors and other colleagues from academic and research institutions, where the quality and quantity
of published papers are an important measure of their impact and weight. The Journal of Print and Media Technology Research, published by iarigai, is now listed among serious periodical publications and will gain the real impact and status by regularly publishing and quotes in comparable reputable journals. For now, we are on the right track, and again we would like to invite authors to send us quality papers for publication.
Ljubljana, March 2018
The impact of non-uniform ink absorption on flexographic print mottle
Sofia Thorman1,2, Li Yang1, Anni Hagberg1and Göran Ström1
E-mails: email@example.com; firstname.lastname@example.org; email@example.com; firstname.lastname@example.org
1 RISE Bioeconomy, Box 5604, 114 86 Stockholm, Sweden
2 Karlstad University, Department of Engineering and Chemical Sciences, 651 88 Karlstad, Sweden
Absorption non-uniformity and surface roughness of coated packaging boards are believed to have an impact on flexographic print mottle. Yet, their respective contributions are not well recognised due to their co-existence. Therefore, we propose a method that can solely study the effects of absorption non-uniformity on print mottle. This is achieved by artificially introducing uneven absorption, through well-controlled barrier patterns. The barrier patterns were added onto board surfaces using flexographic printing. By applying barrier patterns of several area coverages on board substrates of different intrinsic surface roughness it is possible to create a property-matrix, absorption non-uniformity versus for example surface roughness. With this matrix, the impact on print mottle from either of the properties can be studied independently. The results showed that surface roughness had a dominant effect on the print mottle, but mainly when comparing samples that spanned a broad roughness range. On the other hand, within a limited range of surface roughness, uneven ink absorption governed print mottle instead. This may explain why printing problems are sometimes encountered despite smooth board surfaces. Although the impact of absorption non-uniformity on print mottle differed from one board to another, the results indicated that a change towards more uneven absorption will have a negative impact on the print quality for most of the coated boards. The results give a better understanding of flexographic print quality and thereby can enable more reliable print mottle predictions.
Keywords: liquid packaging board, coated board, surface free energy, surface roughness, image analysis
JPMTR 104 | 1804 Original scientific paper
Biopolymer films from glucomannan: the effects of citric acid crosslinking on barrier properties
Glucomannan extracted from konjac root is used to form biodegradable films with gas and grease barrier properties for food packaging application. Nano-fibrillated cellulose (NFC) and plasticizers were used to improve the strength properties of the films. Citric acid and sodium hypophosphite (SHP) were used as crosslinking agent and catalyst, respectively, to improve the barrier property of the films against moisture. The film samples were prepared from glucomannan and NFC using a dispersion-casting method. The moisture barrier properties were characterized by the moisture vapor transmission rates (MVTR) and showed a significant decrease of 49.7 % (with 0.35 g citric acid in formulation, cured; marked as CA35-C). The crosslinked glucomannan films were calibrated with increasing mean tensile strength, modulus and elongation.
Keywords: packaging material, composite film, nano-fibrillated cellulose, air permeability, mechanical property
JPMTR 105 | 1802 Research paper
Analysis of the relationship of quality factors in the solventless lamination process
Vyacheslav Repeta, Yurii Kukura and Valentyna Kukura
E-mails: email@example.com; firstname.lastname@example.org
Faculty of Publishing and Printing Information Technology, Ukrainian Academy of Printing, 19, Pidholosko St., Lviv, 79020, Ukraine
The paper presents the necessity of establishing the priority ranking of factors which influence the solventless lamination process. The quality factors in the lamination process have been determined through the questionnaire survey of specialists experienced in the lamination of flexographic prints. To establish the priority of the quality factors in the flexographic prints lamination process, a ranking methodology was used which is based on the fact that the importance of the factor is determined by numerical indicators related to the number of influences and dependencies between the factors and their respective weight coefficients. The interconnections between the factors in the lamination process have been established and the model of the importance of quality factors in the solventless lamination process of flexographic prints was constructed with the help of the ranking method. In accordance with the obtained results, the following factors are of the highest priority: the construction of the section for adhesive supply, the type of adhesive, the complexity of the printed image, the type of material, web width, and the temperature. By the set terms, the fuzzy knowledge base of parameters in the solventless lamination process with the performance of the condition “if–then” has been formed. Based on this knowledge base, fuzzy logic equations for the calculation of the quality factors in the lamination process options have been built and defuzzification by the “center of gravity” method to get the quantitative quality parameters of the lamination technological process and to optimize the process.
Keywords: flexible packaging, factor analysis, process parameters, fuzzy logic
JPMTR 106 | 1806 Case study