The silicone oil or silicone paste is made into silicone oil emulsion under the action of strong stirring or emulsifier, which can effectively improve the dispersibility of silicone oil in the water phase. Therefore, it is widely used as a defoamer in water systems. Emulsion-type defoamer is also the most widely used and most widely used defoamer of silicone defoamer.

Emulsion-type silicone defoamer is generally prepared from dimethyl silicone oil, emulsifier, emulsion stabilizer and deionized water. The emulsifiers used are mainly non-ionic emulsifiers with low foaming properties, such as Span, Tween and polyethylene glycol, etc. The effect of mixed emulsifiers is better than that of single emulsifiers. The particle size of silicone oil emulsion is the most important control index for emulsion type silicone defoamer. In order to obtain a silicone oil emulsion with high defoaming efficiency and good storage stability, the particle size is usually required to be 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 also be added to increase the viscosity of the continuous phase.

When using 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 lead to demulsification.

Although the emulsion type silicone defoamer has the disadvantages of being difficult to store for a long time, easy to delaminate and easy to deteriorate, it has the characteristics of convenient use, wide application, obvious defoaming effect and moderate price. With the advancement of technology, emulsion-type silicone defoamer will still have a large space for development.