Defoamer booster: Hydrophobic AEROSIL® and SIPERNAT® grades increase the efficiency of defoamer formulations

Hydrophobic SIPERNAT® specialty silica and AEROSIL® fumed silica increase the efficiency of oil-based defoamers, foam inhibitors, foam regulators, and deareators. The well-dispersed silica particles prevent the formation of air bubbles, destabilize existing bubbles, and make them coalesce.

Foam can be a major disturbance. Foam bubbles can, for example, create defects in coatings, impede machine washing, reduce the strength of concrete, complicate the handling of liquids, reduce the filling level of containers, and lead to costly production downtimes. Defoamers are frequently used to control the undesired foam. These are often based on oils like silicone oil, mineral oil or vegetable oil, which form the main component. Oil alone, however, is usually not efficient enough. Only with the addition of finely dispersed hydrophobic silica does the defoamer have a prompt and long-lasting effect. In this way, hydrophobic SIPERNAT® and AEROSIL® grades help to produce highly efficient defoamers. The end user benefits from the reliability of the defoamer in producing the desired effect and can improve the quality of their products and/or processes.


Defoamers work by means of oil droplets that penetrate the water/air interface in a foam lamella, spread there, and disrupt the foam lamella. A hydrophobic silica dispersed in the oil accelerates the penetration of the oil droplet into the foam lamella. This increases the efficiency of the defoamer.


The hydrophobic silica needs to be dispersed very well in the defoamer oil. This can be achieved with a rotor-stator system or a dissolver disk, for example. Next, the resulting compound can be blended with further additives in the final defoamer formulation. For this process it is possible to use a hydrophobic specialty silica such as SIPERNAT® D 10 or SIPERNAT® D 17 as well as hydrophobic fumed silicas such as AEROSIL® R 202, AEROSIL® R 812, AEROSIL® R 812 S, AEROSIL® R 8200, AEROSIL® R 972 or AEROSIL® R 974.
Another option is to start with a hydrophilic specialty silica and hydrophobize it in a so-called “in-situ process” or with the “dry-roast process.” SIPERNAT® 383 DS or SIPERNAT® 35 are especially recommended for this option. These grades are pretreated in a way that means no alkaline catalyst is necessary. 


AEROSIL® and SIPERNAT® products are used in numerous defoamer formulations, for example in the paper industry, in paints and coatings, in construction materials, in oil production, in wastewater treatment, and in many more fields of application.


For more detailed information we recommend the following brochures: TI 1313, TI 1381, TI 1382 and TI 1391.