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

Emulsion type silicone defoamers are generally formulated with 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. 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 defoamers. To obtain silicone oil emulsion with high defoaming efficiency and good storage stability, the particle size is usually required to be less than 10μm.

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 defoamers, 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 difficult long-term storage, easy delamination, and easy deterioration, they are easy to use, widely applicable, obvious defoaming effects and moderate prices. All are still welcomed by users, and With the advancement of process technology, emulsion-type silicone defoamers will have greater room for development.