Pure dimethyl silicone oil does not have a defoaming effect, so it needs to be emulsified before it has a defoaming effect. The surface tension of the emulsified silicone decreases rapidly, and a relatively small amount can achieve a strong defoaming and foam suppressing effect. When a certain proportion of hydrophobically treated silica auxiliary is mixed in silicone oil, an oil-based defoamer can be formed. Silica is used as a filler because the surface has a large number of hydroxyl groups that help to strengthen the The dispersing ability in the foaming system increases the stability of the emulsion and can significantly improve the defoaming performance of the silicone defoamer.


        Because silicone oil itself is lipophilic, the defoaming effect of silicone defoamers on oil-soluble solutions is very good. But when using silicone defoamer, you need to pay attention to these points:


        ① The low-viscosity silicone defoamer has good defoaming effect, but the durability is poor; the high-viscosity silicone defoamer has slow defoaming effect, but the durability is good.


        ② If the viscosity of the foaming liquid is lower, a silicone antifoaming agent with a higher viscosity is usually selected. Conversely, the viscosity of the foaming liquid is higher, and a silicone antifoaming agent with a lower viscosity is selected.


        ③ The molecular weight of the oily silicone defoamer has a certain effect on its defoaming effect.


        ④ Small molecular weight, easy to disperse and dissolve, but lacks durability; conversely, large molecular weight has poor defoaming performance and difficulty in emulsification, but poor solubility and good durability