Home » Novel Silicone Surfactants for Waterborne Wood Coatings
Aqueous coating systems not only play a key role in the reduction of volatile organic components in DIY applications, they are also becoming increasingly important to industrial coating processes as an alternative to classic solvent-based coating systems. In the context of industrial wood coating applications, current estimates indicate that ~40% of the produced coating volume in North America comprises aqueous coating systems – and this ratio is rising significantly. Alongside physically drying one-component systems, aqueous two-component polyurethane and radiation-curable systems are increasing in use. The formulation of such aqueous wood coating systems can at times seem very challenging, since wood, as a natural, porous and absorbent substrate, can place considerable demands on the formulator, especially in terms of substrate wetting and leveling. The varied use of aqueous wood coating systems, particularly in the building products, furniture and hardwood flooring industries, has resulted in very differing application methods (e.g. spraying, rolling, vacuum or curtain application). Additionally, the effects of these higher shear application systems can present major challenges with regard to foam stabilization within these aqueous coating systems. The high polarity and surface tension of water makes it necessary to use specific surface additives, so-called silicone surfactants, to ensure a sufficient wetting of the wood surfaces by the aqueous coating systems. Conventional silicone surfactants are characterized, in part, by a very strong reduction in the static surface tension, resulting in a highly effective substrate wetting. However, they have restrictions in terms of improving leveling, and at times have a tendency to stabilize foam during coating production and application. This article presents a class of new silicone surfactants that offer sufficiently good substrate wetting, with considerably improved leveling properties and only a slight tendency to stabilize foam.
Our May issue features Part 2 of our two-part series on icephobic coatings. We also showcase a new overspray-free paint system that AUDI AG is using, as well as an article from Hockmeyer on vacuum milling, and a feature from X-Rite on how to select the right tolerancing method when controlling color.