Antifoaming agent

Abstract

The control or elimination of the foam that occurs in many industrial processes is a vital factor in their efficient operation. Additives for this purpose are the largest single category of process aids used in the chemical industry (1). They are used in low concentration to achieve this effect and are known variously as defoamers, antifoaming agents, foam inhibitors, foam suppressants, air release agents, and foam control agents. Defoaming implies breaking a preexisting foam, whereas antifoaming or foam inhibition indicates prevention of the formation of that foam. Such distinctions call for different product features. A defoamer is expected to exhibit rapid knockdown of a foam, whereas longevity of action might be the key requirement in many antifoam applications. Despite these varying performance features, many applications require both preventive and control functions, and in practice the same types of materials are used for both antifoaming and defoaming. For this reason, the general term defoamers, as used in this article, is meant to encompass all product types and degrees of action encountered with such process aids. The topic is sometimes known as chemical or physicochemical foam control as opposed to thermal and mechanical foam control approaches, such as centrifuging or spraying of the foam or the use of ultrasound, which are not covered here. Many industries rely on the efficient and economical use of defoamers both as a process aid in product manufacture and to increase the quality of the finished product in its subsequent application. The most obvious use of defoamers