Na-Bentonite and MgO Mixture as a Thickening Agent for Water-Based Paints

Rheology plays a major role both in production and application stages of paints. Na-Bentonite, clay based thickening agent, is generally used to modify the viscosity of paints, since it is more economical and environmentally friendly compared to polymer based thickening agents. In solvent based systems bentonite is generally modified with quaternary ammonium salt to obtain appropriate polarity. However it is necessary to improve its thickening character to obtain optimum performance in water based paints. It has been reported that its flow behavior and stability can be improved by additives like MgO and LiCl for use in water based system. In this paper, Na-Bentonite and MgO mixture was evaluated as an additive in water-borne paints. Standard paint tests such as viscosity, density, opacity, gloss, and Bucholz hardness were conducted to characterize the paint quality. It is determined that the bentonite – MgO mixture can perform as well, or better than other thickening agents tested in this study.