Robustness of surfactant-laden latex films

Despite the growing popularity of latex inks in the inkjet printing industry, little is known about the influence of additives present in the ink mixtures on the robustness of the latex films. Here, we investigate the influence of a non-ionic surfactant, Dynol 607, on the abrasion robustness of a water-based latex film. For fixation temperature below the minimal film formation temperature (MFFT), we observe an improvement of robustness of the film with increasing surfactant concentration due to the improved film coalescence. However, for temperatures exceeding the MFFT, Dynol clearly has a negative impact on the abrasion robustness. Using AFM in the PeakForce tapping mode we have demonstrated that the surfactant forms ultra-thin surfactant layers at the top of the latex film. Force spectroscopy performed with the colloidal probes showed that these layers can increase the adhesion between the film and abrasive material leading to decreased abrasion robustness. However, other effects such as: macroscopic corrugation of the film or the surfactant layer between latex film and the substrate that may have influence on the mechanical performance of the film, were also identified. Our research showcases that mechanical robustness of latex films is affected by surfactant in various ways, which are poorly understood, even though surfactants are commonly used in latex ink formulations.