Improvement of abrasion resistance by over-varnishing in the case of water-based flexographic printing

Abstract

The objective of the research was to analyse the abrasion resistance in flexographic printing with water-based inks, covered with different water-based varnishes. Print rub-off tests in the Ink Rub Tester were performed for one water-based ink and three different water-based varnishes used in flexographic printing. The rub-off resistance was evaluated by spectrophotometric methods and visual observations. The ΔE*_ab parameter was used in evaluation. The 3D optical microscope was used to analyse the obtained test results. It was observed that the varnishing process significantly improves the abrasion resistance of the prints. The type of the varnish used in the research does not have such an influence on improvement of abrasion resistance as that of the varnishing process itself. Considering the average surface roughness it could be deduced that the varnishing process increases the surface roughness for both the paper base and for the polyethylene foil. The greater the surface roughness the better is the resistance to abrasion.