The main goal in coating metal is, of course, to protect the substrate from corrosion. Traditionally, solventborne formulations are used in this application, although waterborne coatings have several important benefits. Lower VOC emissions are the main reason for stricter regulations worldwide that push the use of waterborne solutions. In addition, waterborne coatings are less hazardous in the application as they do not emit hazardous fumes and odors, are not flammable, and equipment is safely cleaned up. Moreover, while specifically 1-pack waterborne latex formulations are easy to apply, their performance in light- and medium-duty applications is good, with excellent durability.
The film formation process of 1K waterborne formulations does not involve a chemical crosslinking step. The application of a dense film therefore, sometimes demands more attention compared to solventborne coatings. This might be complicated by the generally shorter open time of waterborne metal coatings. Due to the hydrophilic components in the formulation – like surfactants, salts and pigments – they are more vulnerable against water and humidity.
We have shown earlier,1,2 that a nanoparticle-based additive called Oxylink™ increases the crosslink density of waterborne coatings. In this paper we investigate and discuss the effect of Oxylink on two different metal protection systems. The additive is a formulated dispersion containing nanoparticles in water. It has a low viscosity at a solid content of ca. 40 wt.% and a shelf life of at least one year when stored between 5 °C and 40 °C.