The influence of reactive diluents on the properties of isocyanate based 2K formulations

 
The quest for low VOC paint formulations has led to different options investigated throughout the years. In the polyurethane industry, several approaches have been developed to reduce the amount of volatile organic compounds, like high solids and low viscosity solvent-free products, UV-curing systems or water-borne formulations, to name a few. Reactive diluents are also an interesting alternative. Whatever the technology, there are two conditions a reactive diluent should fulfil. The first one is the ability to lower the viscosity of the paint formulation and thus reduce the amount of solvent needed to reach the required viscosity for application. On the other side, being reactive ensures that the diluent will be integrally incorporated to the network and will not deteriorate the film properties due to a plasticizing effect. Additional benefits can also be expected, like the control of properties such as hardness or elongation. In this paper, we will present a comparison of several polyisocyanates structures which can be used as reactive diluents in 2K polyurethane or polyaspartic formulations. Their impact on films properties will also be discussed.