AQUEOUS COATING COMPOSITIONS INCLUDING ANIONIC SPECIES SCAVENGING SYSTEM

摘要

Aqueous coating compositions forming coatings having improved water resistance include an anionic species scavenging system. The scavenging system includes volatile base and an aqueous dispersion of water-insoluble, weak base-functional polymer particles. The particles are polymerized from monomer including a weak base-fonctional monomer such as 2-(diethylamino)ethyl methacrylate or 2-(t-butylamino)ethyl methacrylate. In one embodiment, a two stage process is employed to prepare the particles and 2-(dimethylamino)ethyl methacrylate is included only in the initial stage. In a second embodiment, a single stage process uses 2-(t-butylamino) methacrylate. The volatile base maintains the pH of the coating composition above the pKa of the weak base prior to and during application of the coating composition. As the volatile base is lost, the weak base is protonated and forms ion pairs with anionic species such as anionic surfactant.