Silanes in high-solids and waterborne coatings

Silanes have been used effectively in solvent-based or waterborne coatings to crosslink binder resins, increase pigment dispersion and improve end use properties, such as mar and solvent resistance and durability. A series of silylated styrene acrylic clearcoats have been prepared and studied in order to understand the chemical and physical parameters that influence the mar resistance and weathering properties of the cured coatings. It was found that the silane content affects the indentation hardness, coefficient of friction, modulus, and toughness of the cured coatings. A relationship between these coating characteristics and mar resistance is demonstrated. In water dispersed and emulsion polymer systems, silanes maximize properties, such as adhesion and solvent resistance. Silanes are incorporated into these systems via copolymerization or post addition. Recent advances in waterborne silane technologies are discussed, including methods of improving formulation stability.