The silicone oil or silicone paste is strongly stirred or emulsified to make a silicone oil emulsion, which can effectively improve the dispersibility of the silicone oil in the water phase. It is widely used as a defoamer in water systems. Emulsion-type defoamers are also the most widely used and most widely used defoamers for silicone defoamers.

Emulsion-type silicone defoamers are generally formulated from dimethyl silicone oil, emulsifiers, emulsion stabilizers, and deionized water. The emulsifiers used are mainly non-ionic emulsifiers with low foaming properties, such as Span, Tween, and polyethylene glycol. The effects of mixed emulsifiers are better than single emulsifiers. The particle size of silicone oil emulsion is the most important control index of emulsion type silicone defoamer. To obtain a silicone oil emulsion with high defoaming efficiency and good storage stability, the particle size is usually less than 10 μm.

Therefore, in addition to selecting suitable emulsifiers and mixing and grinding process conditions, thickeners such as polyvinyl alcohol and methyl cellulose can be added to increase the viscosity of the continuous phase.

When using an emulsion type silicone defoamer, you should first understand the temperature, acidity and alkalinity of the foaming system, because they will affect the stability of the emulsion and even cause demulsification.

Although emulsion-type silicone defoamers have the disadvantages of being difficult to store for a long time, easy to delaminate, and easy to deteriorate, they are easy to use, widely applicable, obvious defoaming effect and moderate price. With the advancement of process technology, there will be more room for development of emulsion-type silicone defoamers.