PUSHING THE LIMITS ON VOCS: High Performance Waterborne Acrylic Direct-To-Metal Coatings Below 50 g/L

摘要

One of the new norms of coating development and reformulation efforts is the drive to lower levels of volatile organic compounds (VOCs), often to meet increasingly strict regulations and specifications. Pushing VOCs to lower levels and performance to higher levels can also offer a more sustainable coatings solution for the end user. Lowering VOC while maintaining (or improving upon) high performance is often the goal when developing a new formulation, but the two objectives can be at odds with each other. For waterborne acrylic direct-to-metal (DTM) finishes and primers, a key challenge is to lower VOC while maintaining film hardness and good film formation. Hardness affects film properties such as block, tack, and dirt pickup resistance, while film formation is critical for latex DTM coatings because it strongly influences barrier properties, i.e., corrosion resistance. The industry is currently looking for acrylic resins which can be formulated below 50 g/L VOC, and yet have excellent hardness, corrosion resistance, and durability properties. The development of a new waterborne binder that offers this unique balance of properties in coatings for the protection of steel and other metals is described. Application testing results demonstrate how the unique composition and morphology of the latex polymer and proper formulating techniques are keys to gaining the desired performance balance. An evaluation of corrosion-resistant DTM finishes with VOC levels under 50 g/L is provided, including comparisons with currently available commercial technologies ranging in VOC levels from 200 g/L to under 50 g/L.