Surface adhesion of inkjet printing on HDPE/LDPE and LDPE/PET multilayer packaging.

Many companies that manufacture multilayer packaging frequently report failures in continuous inkjet (CIJ) coding, resulting in environmental and economic impacts. This study evaluated the parameters influencing the adhesion of three commonly used CIJ inks, considering the wettability, surface morphology, and chemical composition of the packaging surfaces. Three substrates were investigated: a poly(ethylene terephthalate) (PET) and polyethylene (PE) blend, both with and without corona treatment. The packaging materials were characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle measurements, and surface tension analysis. Ink adhesion was evaluated using the tape peel test in accordance with the FINAT FTM21 standard. The results indicate that PET exhibited favorable surface properties, including higher surface tension (37.4 dynes/cm) and a lower water contact angle (76.8°), resulting in adhesion grade 1 (no ink removal). In contrast, the PE blend showed only a slight increase in surface oxygen content after corona treatment (from 0.46 to 0.80 at%), a modest increase in surface tension (from 29.9 to 31.9 dynes/cm), and a small reduction in water contact angle (from 99.6° to 91.8°). These changes were insufficient to ensure effective ink anchoring, and PE blend samples, both treated and untreated, exhibited severe ink removal (>60%), corresponding to adhesion grade 5. This behavior may be associated with the inefficiency of the corona treatment process employed. [ABSTRACT FROM AUTHOR]