Development of a Waterborne, Zero-VOC DTM with Excellent Corrosion Resistance
A well-formed hydrophobic film that is impervious to water and salts is required to prevent corrosion of painted metal surfaces. One of the most effective ways to ensure that the film is well formed is through the use of coalescing solvents. The ability of a coating to form a protective film becomes more difficult as the amount of coalescent in the coating formulation decreases. At the same time, coatings manufacturers are interested in reducing the amount of volatile organic compounds (VOCs) in their coatings. This trend is driven both by regulation as well as consumer preference.
One way to reduce the amount of coalescent in the coatings is to reduce the minimum film formation temperature (MFFT) of the polymer. The most obvious way to accomplish this is to reduce the glass transition temperature (Tg) of the polymer. Unfortunately, this will also reduce the hardness and dirt pickup resistance of the coatings. Through the use of designed particle morphology and process conditions we have developed a latex that can be formulated into a coating without the use of coalescing solvents that gives excellent corrosion resistance, adhesion to steel, and still is hard enough to give good block resistance and dirt pickup resistance.