Comparison of Gravure Inks Properties for Printing on Biodegradable Plastic Film

The purposes of this project were 1) to determine the adhesion properties of gravure inks; solvent-base, alcohol-base, and water-base, on biodegradable plastic films, 2) to study the resistance properties to heat, cool and oil environment, and 3) to compare the optical print density between printed inks on the film of polylactic acid (PLA) and high-density polyethylene (HDPE). There were 5 types of gravure printing inks with different formular to applied for the surface treated and non-treated film. The results showed that all printing ink types had good printability on the PLA. The adhesion tested by tape test method follow ASTM D3395 showed that 2 types of solvent-based ink had slightly better adhesion on the non-treated PLA than did the alcohol-based inks, but the water-based ink had poorer adhesion. All ink films on PLA had good resistance to the heated plate around 60-65°C for 15 minutes. For the cool resistance tested in a freezer around -6°C for 24 hours, the solvent-based inks and the alcohol-based ink for non-treated film had the same good adhesion while the water-based ink film was peeled off especially from the non-treated film. The oil resistance tested by dipping in vegetable oils for 24 hours indicated that the solvent-based ink film and the water-based ink film was not peeled off while the alcohol-based ink film was removed or not resistance to oil. The average optical print density of alcohol-based inks on the PLA were not significantly different from that on the HDPE. Therefore, the alcohol-based ink made for non-treated film should be alternatively applied with the PLA due to more eco-friendly than the solvent-based ink and the surface treatment will be not necessary. However, the water-based ink can also be applied only with the surface-treated PLA.