Waterborne metal coatings face challenging performance requirements, but as water-based technologies improve they are replacing an increasing number of solventborne coating systems. A growing sub-segment of the metal coatings market is direct-to-metal (DTM) coatings, which aim to meet the same performance criteria of a multi-coat system while reducing the application time, complexity and cost with a single coating. All waterborne metal coatings need to use the highest performing raw materials in their most effective manner to achieve their performance goals. In the case of a DTM coating, properties such as corrosion resistance and outdoor durability are critically important but must also be balanced with aesthetic requirements for high gloss and opacity. Here we demonstrate how to maximize the performance of waterborne acrylic metal coatings using amino alcohols as highly efficient dispersants for pigments.
The unique properties of ANGUS amino alcohols offer a multitude of benefits to waterborne formulations, including efficient pH control and enhanced formulation stability.1 The amino alcohol studied in this work, 2-amino-2-methyl-1-propanol (AMP), has a relatively low molecular weight and high pKa, making it a highly efficient pH control additive (Table 1). AMP is also VOC exempt by the U.S. EPA and by the Governments of Canada and South Korea, and can therefore be used to make waterborne industrial coatings that meet low- and zero-VOC regulations.2 However, one of the critical chemical interactions that these materials have with ingredients in waterborne coatings is their strong interaction with pigment surfaces, which makes them highly efficient and effective dispersants for pigments. The amino functional group of AMP can have strong interactions with negative surface charges on pigment surfaces, such as titanium dioxide, clays and talcs, among other extenders and colored pigments.3