ATR-IR spectroscopy for dynamically measuring the effect of drying on binder migration, 2012 Advanced Coating Fundamentals Symposium

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Latex binder is an expensive component of a coating layer and therefore, its effective use is critical in the production of coated paper. Here we present a simple method to monitor the concentration of latex relative to pigments during and after the drying event. Coatings are applied to a crystal surface and Attenuated Total Reflection Infrared absorption spectra (ATR-IR) are collected during the drying event. Surface concentrations of coatings at the end of drying and bulk measurements are also obtained.

By monitoring the change in intensity IR bands of specific components as a function of time, the concentration of water, latex, kaolin or calcium carbonate is measured during drying. Latex is found to migrate relative to the pigment particles even after the first critical concentration. It is shown that the migration of latex relative to the pigments is less at higher drying temperature and faster drying times and this is the same trend found for coatings applied on paper substrates. Latex is found to move in the direction of water motion, either towards the base paper due to absorption or to the top surface due to drying.