The growth today in waterborne and radiation-cured coatings and inks far exceeds that of its solventborne equivalents. The need for lower VOCs, “greener” materials, improved food safety and reduced economics (inventory reduction and faster production speeds) all contribute to this growth, and this in turn increases the need for superwetters. Why? As formulators transition from solventborne coatings and inks to create healthier, safer and more eco-friendly systems, performance requirements bring to light issues and disadvantages associated with waterborne and radiation-curable systems. In particular, many of the surfactant packages utilized have the negative effect of stabilizing foam from air incorporation during coatings production and application. In addition, in waterborne coatings specifically, the inherent high surface tension of water creates the potential to cause surface defects such as craters and poor wetting on substrates.
With the growth of waterborne and radiation-curable coatings and inks comes the development of more binder systems, and formulators find they require a wider portfolio of wetting additives to choose from when developing new formulations. No one, universal solution is suitable across a wide range of formulations and substrates because inconsistent performance; lack of regulatory compliance; poor pH stability; poor performance in demanding, high-speed applications; and cost all bring the formulator problems. In the coating and ink industries, silicone materials have been developed and used for many years to improve the surface appearance and properties of many systems, including wetting, but this technology has also suffered from inconsistent performance. Dow Corning has recently launched four 100% silicone polyether co-polymers with good compatibility in waterborne and radiation-curable systems to provide good substrate wetting consistently over a wide range of formulations, pH ranges and substrates.
This article describes an application study comparing the performance of these four unique silicone polyether co-polymer superwetters to commercially available surfactants on the market (acetylenic diols and silicone polyether copolymers, including Gemini surfactants) (Table 1).