The pure dimethyl silicon oil has no defoaming effect, so it needs to be emulsified before it has defoaming effect. The surface tension of silicone after emulsification decreases rapidly, and a small amount of it can achieve a strong defoaming and anti-foaming effect. When mixed with certain proportion in silicone oil treated by the hydrophobic silica fertilizer, oil can be formed composite defoaming agent, the silica as filler, is because of its surface has a lot of hydroxyl helps to enhance the capacity of silicone oil dispersed in the foaming system, increase the stability of the emulsion, can significantly improve the silicone antifoam antifoaming performance.
Because the silicon oil itself has the lipophilic, so the organic silicon defoaming agent to the oil solution defoaming effect is very good. But in the use of silicone defoaming agents need to pay attention to the following points:
(1) low viscosity silicone defoaming agent defoaming effect is good, but poor persistence; High viscosity silicone defoaming agent defoaming effect is slow, but good persistence.
(2) if the foaming liquid viscosity is lower, usually choose a higher viscosity silicone defoaming agent, on the contrary, the foaming liquid viscosity is higher, choose a lower viscosity silicone defoaming agent.
(3) the molecular weight of oily silicone defoaming agent has a certain effect on its defoaming effect.
(4) small molecular weight, easy to disperse and dissolve, but lack of persistence; On the contrary, high molecular weight has poor defoaming performance, difficult emulsification, poor solubility and good persistence.