Effects of propylene-ethylene copolymer on gravure printing of corona-treated BOPP film

Abstract

In this study, the BOPP film samples were prepared using the 3-layers co-extruder, with 1.0 µm thickness of skin layer. The skin layer of BOPP film was modified by adding propylene-ethylene copolymer at various amount of 3-6% by weight. The film surface was subjected to corona treatment which was in line of production after the film was completely biaxially oriented. The contact angle of these BOPP films was subsequently measured and their surface free energy (SFE) was calculated. In addition, the effect of antistatic agent and slip agent in the major layer of BOPP film to SFE were also investigated. The results exhibited that the SFE of BOPP films was higher with the increasing content of propylene-ethylene copolymer and the presence of the antistatic agent. At 6% of propylene-ethylene copolymer in the skin layer, the SFE of BOPP film was approximately 20% higher than the original BOPP film. Its FTIR spectrum of BOPP film at 6% showed the carbonyl absorption band with highest intensity compare to the others. The printability of BOPP films was also investigated using Gravure proof machine with magenta and cyan inks. The printing images of BOPP films were visually observed with a microscope. It was found that exhibited the best printing image due to the least disappearance of the unit cell on the dot screen.