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Presentations 2015, 2016

iarigai Toronto 2016
iarigai, VIGC, IS&T at drupa 2016

iarigai VIGC, Brussels
Evolutions in food packaging printing

You are here: Conferences & Events * 2008 Valencia * Abstracts * 2. Printing and printing materials

2. Printing and printing materials

2.13. Toner spreading during the fixing stage

Elina Hakola(1), Pirkko Oittinen(2), Jorma Koskinen(1), Ulla Forsström(1)

(1) Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL)
P.O.Box 70, FI-02151 Espoo, Finland
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

(2) Helsinki University of Technology (TKK)
P.O.Box 5500, 02015 TKK, Finland

Abstract
Toner spreading is studied using a fixing simulator where the toner layer is fixed by means of both heat and pressure. The fixing temperature and pressure of the instrument can be individually adjusted. Toner starts to spread as soon as the toner particles have coalesced. The initial spreading is very fast after which the spreading rate slows down. Finally, an equilibrium state is achieved. The increase in the fixing pressure accelerates the spreading of toner since toner is pushed more effectively against the paper and squeezed. This leads to better wetting and spreading. However, the penetration of toner into the pores of the substrate prevents the spreading of toner to some extent. A low viscosity enables faster and easier spreading but it can also accelerate toner penetration. In addition, thick toner layers and the use of polyester resins increase the amount of spreading.

Keywords: Electrophotography, toner fixing, toner spreading
 

2.14. Curing of UV ink and product safety

Merja Kariniemi, Anu Ilmonen, Eija Kenttä, Satu Sundqvist, Birgit Aurela

KCL, Oy Keskuslaboratorio - Centrallaboratorium Ab
PL 70, 02151 Espoo, Finland
e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
Two methods to measure the curing degree of UV inks were developed in this study. The surface curing method, based on ATR-IR, measured the curing only in a thin layer of the surface of the printed sample. The total curing method, based on NIR, measured the curing degree also from the ink that has penetrated deeper into the substrate. Studying the total curing degree is useful from the product safety aspect.

Based on the novel curing degree measurement techniques applied in this study, a concept for studying paper/board in combination with the ink system was established. The concept (including ink analyses, curing methods and product safety analyses) was applied to different substrates. Both offset and flexo trials were carried out at full-scale.

On the basis of this study, it became clear that the surface properties and structure of paper have a significant influence on the total curing degree obtained for the studied paper and ink systems. This result has not been evident in earlier studies on UV printing. The migration tests done to the printed samples seemed to correlate with total curing results, which now can be measured in a quantitative way.

Keywords: Curing, full scale printing, product safety, spectroscopy, UV inks

 

2.15. In situ monitoring of the photo polymerization of UV curable acrylate coatings

Elena-Magdalena Casagrande(1,2), Andreas Hörner(2), Achim Wixforth(2)

(1) manroland Duckmaschinen AG
Augsburg, Germany
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

(2) Chair for Experimental Physics I, University of Augsburg, Germany

Abstract
Employing a surface acoustic wave sensor and real time FTIR spectroscopy, we investigate the photo polymerization kinetics in UV curable multifunctional acrylate clear coating systems. Being sensitive to changes of the viscoelastic properties of the coating, the changes in the amplitude of the surface wave and the monomer conversion in the Acryl ate Systems during the irradiation time yields the polymerization rate and cure extent in real time. The onset of the polymerization was observed not to occur instantaneously after UV irradiation but rather after a certain time interval. The time delay between onset of the polymerization and the changes in the acoustic wave transmission parameters is attributed to the introduction of the crosslinking, leading to a gel state.

Keywords: Acoustic wave transmission, FTIR spectroscopy, photo polymerization

 
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