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Type of Antifoamers II

I. Natural Oil (i.e. Soybean Oil, Corn Oil, etc.)
II. High Carbon Alcohol
III. Polyether Antifoamers
IV. Polyether Modified Silicone
...previous Chapter for details.
V. Organic Silicon Antifoamer
Polydimethylsiloxane, also known as silicone oil, is the main component of silicone defoamer. Compared with water and common oil, its surface tension is smaller, which is suitable for both water-based foaming system and oil-based foaming system. Silicone oil has high activity, low solubility, stable chemical properties, light application range, low volatility, non-toxic, and prominent defoaming ability. The disadvantage is poor foam inhibition performance.

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1. Solid Antifoamer
Solid Antifoamer has the characteristics of good stability, simple process, convenient transportation and easy use. It is suitable for both oil phase and water phase, and the medium dispersion type is also prominent. It is widely used in the field of low foam or non foam washing powder.

2. Emulsion Antifoamer
The silicone oil in emulsion defoamer has greater tension, and the emulsification coefficient is too large. Once the emulsifier is selected unproperly, it will cause defoaming agent to be layered and metamorphic in a short time. The stability of emulsion is very critical to the quality of defoaming agent. Therefore, the preparation of emulsion type silicone defoamer focuses on the choice of emulsifier. At the same time, the emulsion defoamer has the largest dosage in silicone defoamer with the characteristics of low price, wide application scope, obvious defoaming effect, and so on. With the progress of formulation technology, emulsion defoamer will develop greatly.

3. Solution Antifoamer
It is a solution made by dissolving silicone oil in solvent. Its defoaming principle is that silicone oil components are carried by solvent and dispersed in foaming solution. In this process, silicone oil will gradually condense into droplets to complete defoaming. Silicone oil dissolved in non-aqueous organic solution system, such as polychloroethane, toluene, etc., can be used as oil solution defoaming.

4. Oil Antifoamer
The main component of oil defoamer is dimethyl silicone oil. Pure dimethyl silicone oil has no defoaming effect and needs to be emulsified. The surface tension of emulsified silicone decreases rapidly, and a small amount can achieve strong foam breaking and inhibition. When silicone oil is mixed with a certain proportion of hydrophobically treated silica assistants, an oil compound defoamer can be formed. Silicon dioxide is used as a filler, because a large amount of hydroxyl groups on its surface can enhance the dispersing power of silicone oil in the foaming system, increase the stability of the emulsion, and obviously improve the defoaming property of the silicone defoamer.

Because silicone oil is lipophilic, silicone defoamer has a very good defoaming effect on oil-soluble solution. However, these points should be paid attention to when using silicone defoamer:

● Low viscosity silicone defoamer has good defoaming effect, but its persistence is poor; High viscosity silicone defoamer has slow defoaming effect but good persistence.
● If the viscosity of the foaming solution is lower, it's better to select the silicone defoamer with higher viscosity. On the contrary, the higher the viscosity of the foaming solution is, it's better to select the silicone defoamer with lower viscosity.
● The molecular weight of oily silicone defoamer has a certain influence on its defoaming effect.
● The defoamer with low molecular weight is easy to disperse and dissolve, but lack of persistence. On the contrary, the defoaming performance of high molecular weight defoamer is poor, and the emulsification is difficult, but the solubility is poor and the durability is good.


Post time: Nov-19-2021