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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

2.10. Surface properties and UV ink-jet printability of recycled polyolefins

Diana Gregor-Svetec, Tadeja Muck, Gorazd Golob

University of Ljubljana, Faculty of Natural Sciences and Engineering
Snežniška 5, SI-1000 Ljubljana, Slovenia
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
The goal of the research was the investigation of printability of thin plastic plates, produced from the 100% recycled polypropylene (PP), 100% recycled low-density polyethylene (LDPE) and 100% recycled high-density polyethylene (HDPE) chips, made from the separatelly colected waste packaging in Slovenia. Surface roughness, coefficient of friction, surface energy and chemical composition of polymeric plate surface were analysed. Polymeric plates were printed with the UV inks on the large format digital UV inkjet printers TeckSmart and Arizona. Optical density, colour of plates and quality of prints were determined. The results have shown that the lowest optical density has the PP, the highest HDPE, which has also the darkest grey colour and that the uniformity of the surface colour is higher at the PP than at LDPE and HDPE. Prints on the PP are more uniform, and the colour saturation is the highest. The best printability was obtained for polypropylene, as PP has the most uniform surface, the lowest contact angle and the highest surface energy with the prevailing part of the polar component resulting in better wetability of surface.

Keywords: Polyolefins, printability, recycling, UV inkjet printing
 

2.11. Insight into IJ-ink/paper interaction using drop spreading model

Marie Kaplanová(1), Lenka Otáhalová(1), Tadeja Muck(2)

(1) University of Pardubice, FCHT, Department of Graphic Arts and Photophysics
Pardubice, Czech Republic
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

(2) University of Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Slovenia

Abstract
In non-impact printing the interaction of ink drop with substrate after impacting the paper surface is important process that determines the print quality. Theories that describe the initial stage of wetting usually assumes ideal solid surface that are far from real surfaces encountered in the printing industry and thus leaving some questions concerning the interaction between inks and substrates opened.

The primary interest of this investigation is to study the behaviour of the liquid-paper interaction in the event of ink drop impaction on a sized paper surfaces. Relation of rate constant and surface tension on surface roughness using both the standard liquids and the IJ inks were observed and an alternated model for description of drop spreading of liquids was proposed and verified on a range of coated papers.

Correlation of spreading rate and imbibition and characteristics of drops formed by inkjet printer were further evaluated. UV-curable inks showed almost no absorption process on tested papers. So the drop characteristics are mainly determined by the spreading to equilibrium, unless the print-to-cure time is short enough the freeze the moving droplet.

Keywords: Contact angle measurement, coated paper, inkjet ink, ink/paper interaction, surface tension, UV inks
 

2.12. Theoretical investigation into pigment-resin binding energies conformations associated with the magenta bodying reaction of water-based inks

Scott Williams

Rochester Institute of Technology, School of Print Media
69 Lomb Memorial Drive, Rochester, NY 14623 (USA)
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Abstract
A MNDO/PM3 semi-empirical method for computing the enthalpy of association, dipole moment, and preferred conformation between model ink resin oligomers and the aromatic surface face of 2,9-dimethylquinacridone (C.I. Pigment Red 122) was performed. We earlier reported that inks prepared with this pigment and styrene-acrylic polymer resin systems would undergo rapid viscosity thickening, or bodying, greatly decreasing the useful shelf-life of this ink. The pigment aromatic surface was modeled using known x-ray crystallographic coordinates, and further optimized using an Amber geometry optimization protocol. Two resin oligomer models, diacrylic acid and styrene-triacrylic acid, were also modeled and geometry optimized for this study. Whereas interaction between the negatively charged acrylic acid subunit and the pigment surface was found to be very weak, the addition of a single styrene subunit substantially increased the ability of the styrene-triacrylic resin oligomer to stably complex with the pigment surface. Strong   -   dispersive interactions were found to drive this complexation reaction over dipolar or hydrogen bonding mechanisms.

Keywords: CI Pigment Red 122, intermolecular interactions, MNDO/PM3, styrene-acrylic resin
 
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