Removal of solvent-based ink from printed surface of high-density polyethylene bottles by alkyltrimethylammonium bromides: Effects of pH, temperature, and salinity

The effects of pH, temperature, and salinity on the removal of solvent-based ink from high-density polyethylene (HDPE) surfaces were investigated using three alkyltrimethylammonium bromides (i.e., dodecyl-, tetradecyl-, and hexadecyl-trimethylammonium bromide or DTAB, TTAB, and CTAB, respectively). Ink removal increases with increasing concentration, increasing pH, decreasing temperature, and increasing salinity of the CnTAB solutions. The zeta potential of ink becomes more positively charged with increasing pH as well as concentration and alkyl chain length of CnTAB, indicating that adsorption of CnTAB on ink pigment occurred more readily with an increase in any of those parameters. The solubilization of epoxy ink binder was found to increase with increasing surfactant concentration, decreasing temperature, and increasing salinity of the CnTAB solutions. Adsorption of cationic surfactant onto the ink pigment particles and solubilization of ink binder molecules into surfactant micelles are important mechanisms causing ink removal from the plastic surface.