Comparison of Gravure Inks Properties for Printing on Biodegradable Plastic Film

The purposes of this project were 1) to determine the adhesion properties of solvent-based, alcohol-based, and water-based inks on biodegradable plastic films, 2) to study the physical properties in resistance to heat, cool and oil, and 3) to compare the print density and color difference between inks printed on biodegradable plastic film and polyethylene film. There were 5 types of gravure printing inks to applied by bar coater on the treated and non-treated polylactic acid (PLA) film. The results showed that all printing ink types had a printability on the PLA film with the same print density as the polyethylene film, especially for solvent-based and alcohol-based ink. The adhesion levels were tested by the tape test method as ASTM D 3395, found that the solvent-based inks had the best adhesion, the alcohol-based ink had the same property, and the water-based ink was good for the treated film. The thermal resistance of ink film was tested by placing on the plate heated around 60-65°C for 15 minutes. The results showed that all types of printing inks had the same good adhesion levels. After cool resistance testing in a freezer at temperature around -6°C for 24 hours, the solvent-based ink for treated film and alcohol-based ink for non-treated film had the best adhesion. The water-based inks had poorer adhesion or ink peel off especially for non-treated film. For the oil resistance tested in vegetable oils for 24 hours, the solvent-based ink and the water-based ink on treated film was not peeled off but the alcohol-based ink was peeled off. Therefore, the alcohol-based ink could be applied on the non-treated PLA film for more eco-friendly with an acceptable color difference (ΔE_ab=3.76) compared to the printed polyethylene film. However, the water-based ink could be applied to print on the treated PLA film with enough adhesion level.