Kaolin-based coating colors with different rheological and water retention properties : Runnability on a lab-and pilot scale

Sammanfattning: Food packaging plays a crucial role in protecting and storing food to keep the products fresh and reduce waste. There is a need to increase the number of paper packages in the food industry to meet the growing demand. Therefore, barrier coatings are an essential aspect of the paper industry since they have good resistance to grease and moisture, which protects the food. The development and improvement of these barrier coatings have the potential to contribute to the advancement of environmentally friendly food packaging. This work aims to examine the impact of rheological behavior and properties on the runnability and barrier performance of barrier coating formulations containing two different kaolin clays, Speswhite (K1) and Capim NP (K2), with the addition of nanoclay in varying amounts. Different formulations were tested as multilayer barrier coatings on lab- and pilot-scale in order to determine the effect of various nanoclay concentrations on runnability, water retention, and rheology properties. Various measurement techniques have been used to obtain a wide range of information on the rheological properties, including the viscosity, under varied shear rate ranges. Also studied are runnability, grease and moisture barrier performance, water retention, and high shear testing for rheology to determine flow behavior. The results show that the viscosity was higher on the lab scale than on the pilot scale due to the poor nanoclay dispersion at the pilot scale. As expected for this type of barrier coating, the KIT-test revealed that the grease barrier was highly effective. Measurements of water retention were good for the low amounts of nanoclay content. Lastly, the shear testing gave very similar results between all the different barrier coating formulas. It was determined that a low nanoclay content gave a good barrier coating performance. However, a higher nanoclay content resulted in decreased water resistance compared to a coating with a low nanoclay content.