Surface Modified and Rheologically Improved Organic Pigments
In colored paints, the pigments make the greatest contribution to the viscosity of the liquid system. Acceptable and stable viscosity is a prerequisite to a stabilized system that will deliver the required aesthetics to the ultimate automotive finish. Any pigment modification that provides system rheological improvements is desirable. Lowered viscosity allows an increase in pigment concentration and, therefore, a reduction of emissions to the atmosphere.
Reduction of solvent levels in coatings manufacture is an attractive, effective and necessary concept. A large reduction in binder viscosity was accomplished many years ago when a significant part of the U.S. automotive industry moved from lacquers to enamels. Lowering the molecular weight of binders and introducing appropriate compounds for subsequent crosslinking made a contribution toward lowering viscosity. In addition, surface modification of pigments and the use of compatible polymeric dispersants have made2 an important contribution toward lowering paint viscosities.