Advantages and disadvantages of silicone defoamer

2022-03-11   Pageview:58

Advantages of silicone defoamer:

1) Wide application range: Due to the special chemical structure of silicone oil, it is neither compatible with water or substances containing polar groups, nor is it compatible with hydrocarbons or organic substances containing hydrocarbon groups. Due to the insolubility of silicone oil to various substances, it has a wide range of applications, not only for defoaming in water systems, but also in oil systems.

 

2) Small surface tension: The surface capacity of silicone oil is generally 20-21 dynes/cm, which is smaller than that of water (72 dynes/cm) and general foaming liquids, and the defoaming effect is good.

3) Good thermal stability: Take the commonly used dimethicone as an example, it can withstand 150 °C for a long time, and can withstand more than 300 °C in a short time, and its Si-O bond does not decompose. This ensures that the silicone defoamer can be used in a wide temperature range.

4) Good chemical stability: Because the Si-O bond is relatively stable, the chemical stability of silicone oil is very high, and it is difficult to chemically react with other substances. Therefore, as long as the preparation is reasonable, the silicone defoamer is allowed to be used in the system containing acid, alkali and salt.

5) Physiological inertness: Silicone oil has been proven to be non-toxic to humans and animals, and its half-lethal dose is greater than 34 g/kg. Therefore, silicone defoamer (with suitable non-toxic emulsifier, etc.) can be safely used in food, medical, pharmaceutical and cosmetic industries.

6) Strong defoaming power: Silicone defoamer can not only effectively break the foam that has been formed, but also can significantly inhibit the foam and prevent the formation of foam. It is used in a small amount, as long as one millionth (1ppm) of the weight of the foaming medium is added, it can produce a defoaming effect. Its usual range is 1 to 100 ppm. Not only is the cost low, but also does not contaminate the defoamed material.

Disadvantages of silicone defoamers:

1) It is difficult to disperse polysiloxane: polysiloxane is insoluble in water, which hinders its dispersion in the water system. It is necessary to add a dispersant. If too much dispersant is added, the emulsion will be stabilized and the defoaming effect will change. Poor, it is necessary to use less emulsifier to make the defoaming effect good and the emulsion stable.

2) Silicone is oil-soluble, which reduces its defoaming effect in oil systems.

3) Long-term high temperature resistance and poor alkali resistance

Nanjing tianswax produces silicone wax emulsion for textiles, welcome to inquiry.

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