Foam is often produced in water-based metalworking fluids by the use of epoxidation emulsifiers and other surfactants. Generally, there are three types of defoaming agents added to metal processing fluids:There is an oil defoamerSilicone oil defoaming agentOrganically-modified siloxane defoaming agentOil defoaming agents are known for their high compatibility with the corresponding organic particles in the dispersion system. But because of their high surface tension, these products are only moderately efficient. In contrast, silicon defoamers have low surface energy and thus high efficiency, but have the disadvantage of incompatibility with organic matter in polymer dispersions. The defoaming agent based on organic modified siloxane has special advantages due to its organic structure unit. On the one hand, it has much higher compatibility with organic polymer than silicone oil; on the other hand, it has high defoaming efficiency due to its main siloxane chain.