Regulations reducing the allowable levels of volatile organic compounds (VOCs) in coatings have challenged formulators for decades. Those screws continue to tighten. Requirements are changing from “low-VOC” to “zero-VOC.” Even if VOC is allowed, water-based coatings formulators are tasked to create coatings with performance matching that of traditional, solvent-based coatings without alkylphenol ethoxylate (APEO) surfactants, or the odor associated with traditional coalescing solvents. Along with these externally driven changes, paint companies are seeking to streamline inventory costs by product line rationalization and qualification of multipurpose, broad-utility components. As coatings evolve, traditional problem-solving technologies such as mineral oil defoamers are found to be less effective. This issue is especially pronounced in low-pigment volume concentration (PVC), high-gloss coatings. In response, formulators are turning to alternative technologies, such as polymeric siloxane defoamers to strike a new balance of miscibility and foam control.
This article looks at the factors impacting the design and selection of foam-control agents for compliant coating formulations.