Simple dimethyl silicone oil has no defoaming effect, so it needs to be emulsified before it has defoaming effect. After emulsification, the surface tension of silicone is rapidly reduced, and the use of less amount can achieve strong foaming 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 silicone oil itself is lipophilic, silicone defoamer has a very good effect on oil soluble solution. But in the use of silicone defoamer need to pay attention to these 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 fluid viscosity is lower, usually choose the higher viscosity of silicone defoamer, on the other hand, the higher the foaming fluid viscosity, choose the lower viscosity of silicone defoamer.
③ The molecular weight of the oil type 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 defoaming performance is poor, and emulsification is difficult, but solubility is poor, persistence is good.