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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

2.07. Ink transfer during flexographic printing to paper

Timothy C. Claypole, David G. Beynon, Simon M. Hamblyn

Welsh Centre for Printing and Coating, School of Engineering, University of Wales Swansea
Singleton Park, Swansea SA2 8PP, UK
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Abstract
As part of an on going study of the process physics of flexographic printing, a comprehensive study has been undertaken of the effect of ink viscosity, engagement, line ruling and anilox volume on the ink transfer to paper. The viscosity of the ink was varied in two manners, one by dilution with solvent thus reducing pigment concentration as well as the viscosity and the other reducing the viscosity at constant ink strength. The anilox volume was found to have the greatest effect on the ink transfer in the solid coverage areas. However, an interaction was found between the coverage, the line ruling and the anilox cell size. This can be attributed to the deformation of the half tone areas of the plate into the anilox cells and in part explain the inconsistency found by previous researchers in highlight regions on the plate. The engagement was found to increase the ink transfer as more ink was impressed into the substrate.

Keywords: Flexography, ink transfer, paper

 

2.08. Evaluation of the ink transfers of prints using low-angle shaving system

Yasushi Ozaki, Naoko Fujisawa, Eiji Kawamura

Research Institute, National Printing Bureau of Japan
6-4-20 Sakawa, Odawara-shi, Kanagawa 256-0816 Japan
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Abstract
In order to estimate ink transfers of multicolor offset and flexo printing, Surface and Interface Cutting Analysis System (SAICAS) was used to make slopes of ink layers by ultra-low-angle shaving. The slopes of the ink layers obtained were observed with optical microscope (OM), scanning electron microscope (SEM) and scanning probe microscope (SPM), and the ink transfers were characterized using Raman spectroscopy.

Ink transfers of multicolor printing using the low-angle shaving technique of SAICAS could be observed with OM and SEM. Raman spectroscopy could also be applied to the low-angle shaving slope because we were able to expand the thickness of the ink layer using SAICAS. In the case of prints in which each colored ink layer overlaps the previous each ink layer before it has cured, each color ink was not formed as a separate ink layer, instead mixed together. In addition, ink layers of commercial offset and flexo prints could be observed from the slope of prints obtained by SAICAS.

Keywords: Flexo ink, ink transfer, offset ink, SAICAS, shaving technique

 

2.09. The effects of surface treatment on digital print quality of extrusion coated paperboard

Johanna Lahti, Mikko Tuominen, Jurkka Kuusipalo

Tampere University of Technology, Paper Converting Technology
P.O.Box 541, FI-33101 Tampere, Finland
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Abstract
The most important function of a packaging material is to shield the product inside the package. Extrusion coated paperboard is generally used in food, medical and cosmetic packages. Extrusion coatings give a barrier against water, water vapour, aroma, grease, oxygen, etc. In addition to barrier properties, heat sealability and printability are important properties in packaging applications. From point of view of printing, the dense and impervious structure of extrusion coatings is challenging: printing inks and toners do not penetrate into the coatings. The durability of the printed image is significant, because the image must withstand various converting operations when the package is constructed. The most common method for obtaining good ink adhesion is to oxidise the surface. Surface treatments are used to change the chemical composition, increase the surface energy, modify the crystalline morphology and surface topography, or remove the contaminants and weak boundary layers. Two widely used methods are electrical corona discharge treatment and flame treatment. These processes generally cause physical or chemical changes in a thin surface layer without affecting the bulk properties. Treatments will increase surface energy and also provide polar molecular groups necessary for good bonds between ink and polymer molecules. In addition to these two methods, a lot of research work has focused on atmospheric plasma treatment. This paper compares these different surface treatments and presents their effects on surface properties of extrusion coating and furthermore, on digital print quality.

Keywords: Adhesion, atmospheric plasma treatment, corona treatment, digital printing, electrophotography, extrusion coating, flame treatment, packaging, paperboard, surface energy

 
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