Introduction

The antifoam effect

Foams appear as an integral part of various technological applications, such as ore and mineral flotation, tertiary oil recovery, production of porous insulating materials, fire fighting and many others. Foams are also encountered in certain types of consumer products, e.g. the mousses and ice-creams as food products, and shaving and styling foams in cosmetics. It has been known for many years that the presence of oil droplets and/or hydrophobic solid particles in the aqueous foaming solutions can strongly reduce the foaminess and foam stability, which might be a problem in various applications. For example, the fat particles in food products and the droplets of silicone oil used in personal care products (such as shampoos and hair/skin conditioners) have a strong antifoam effect, which should be suppressed to achieve an acceptable product quality from a consumer viewpoint.

On the other hand, excessive foaming might create serious problems in many industrial processes. Typical examples are during fermentation in drug and food manufacturing, the processing of drug emulsions and suspensions, pulp and paper production, industrial water purification, beverage production and packaging, textile dyeing, oil rectification and many others. That is why special additives called “antifoams” or “defoamers” are widely used in these and other industrial applications to suppress foam formation or to destroy already formed foam.