Flow and leveling agents are the most important additives in coating formulation. It reduces the surface tension of the carrier liquid and makes the liquid flow more easily.
The leveling of the coating material depends on its flow characteristics, surface tension, application parameters and drying conditions. If the flow is insufficient, surface defects like distinct textures, voids, carters and pinholes will appear on the surface of the clear silicone coating. On the contrary, when a coating with good flow is applied to a suitable substrate, it can produce a perfect glossy surface with good gloss no defects.
In order to achieve good flow, the surface tension must be kept uniform during the drying process. During the drying process of solvent borne coating, the solvent on the surface will evaporate, resulting in differences in temperature, surface tension, solvent concentration and density in the film. There are defects in the formation of films, such as fish eyes and orange peels, as well as Benard cells. The key parameter for the formation of these defects is the local surface tension gradient, which physically forms the defects and retains them as the film dries.
In most cases, excellent surface performance cannot be achieved without adding surface control silicone additives that adjust the surface performance of the coating. SiSiB flow and leveling agents adjust the surface tension of drying coatings to a uniform, low level and eliminate the differences in surface tension. Polyether modified Polydimethylsiloxane based materials lower surface tension to the range of 20 mN/m and perfluoroalkyl surfactants to the range of 15-20 mN/m.
This minimizes the flow of the material from the low surface tension area to the high surface tension area, thereby suppresses eddy formation. The solvent evaporates evenly from the whole surface, making the film dry very homogeneously and exhibiting better leveling. Controlled surface tension improves wetting, flow, and leveling of the surface and prevents problems such as orange peel, craters, overspray, flooding and floating.
SiSiB products are used throughout the industrial coatings market, providing original, alternative and reliable solutions to appearance-related problems.