Types of Organosilicon Defoamers

What is defoamer?

Defoamers are composed of active ingredients, emulsifiers, carriers, and emulsifying agents. The active ingredient is the core part of the defoamer, which plays a role in breaking bubbles and reducing surface tension. Emulsifiers disperse active molecules into small particles that are better dispersed into oil and water, and are carriers that can exert better defoaming effects, accounting for a large proportion in defoamers. In addition, the surface tension of emulsifier is not high, and it mainly plays the role of medium, which is conducive to inhibiting foam and achieving better defoaming effect, thus reducing production costs.

Organic silicon defoamer and inorganic silicon defoamer

There are many types of defoamers, including organic silicon defoamers and inorganic silicon defoamers. So, which one is better, organic silicon defoamers or inorganic silicon defoamers? Which products are suitable for using organic silicon defoamers, and which products use inorganic silicon defoamers?

Organosilicon defoamers belong to defoamers with strong defoaming ability, but their anti foaming ability is poor. They are prone to shrinkage when used in water-based adhesives, water-based coatings and other products, and are currently widely used in the water treatment industry.

Silicon free defoamer does not contain any organic silicon components, so it will not cause silicon spots to remain on the groove wall and is easy to clean the equipment. It is important that adding it to water-based adhesives, water-based coatings, water-based inks, and other products will not cause shrinkage or fish eyes. But the defoaming performance is relatively weak compared to organic silicon defoamers.

silicone defoamer

Organic silicon defoamer (English name: organic silicon defoamer) is mainly composed of silicone oil and organic silicon components. Silicone oil is a non-volatile oily liquid at room temperature, insoluble or with low solubility in water, animal and vegetable oils, and mineral oils. It can withstand both high and low temperatures. Chemical inertness, stable physical properties, and no biological activity.

Advantages of Organic Silicon Defoamer

(1) Widely applicable: Due to the special chemical structure of silicone oil, it is not soluble in water or substances containing polar groups, nor is it soluble in hydrocarbons or organic compounds containing hydrocarbon groups. Due to the insolubility of silicone oil to various substances, it has a wide range of applications, both in water systems for defoaming and in oil systems.

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

(3) Good thermal stability: Taking commonly used dimethyl silicone oil as an example, it can withstand 150 ℃ for a long time and above 300 ℃ for a short time, and its Si-O bond does not decompose. This ensures that the silicone defoamer can be used over a wide temperature range.

(4) Good chemical stability: Due to the stability of Si-O bonds, silicone oil has high chemical stability and is difficult to react with other substances. Therefore, as long as the formulation is reasonable, organic silicon defoamers are allowed to be used in systems containing acids, bases, and salts.

(5) Physiological inertness: Silicone oil has been proven to be non-toxic to humans and animals, with a median lethal dose greater than 34 grams per kilogram. Therefore, organosilicon defoamers (when combined with suitable non-toxic emulsifiers) can be safely used in industries such as food, medical, pharmaceutical, and cosmetics. (6) Strong defoaming power: silicone defoamer can not only effectively break the generated foam, but also significantly inhibit foam and prevent the formation of foam. Its usage is very small, as long as one millionth (1ppm) of the weight of the foaming medium is added, it can produce defoaming effect. Its commonly used range is 1 to 100ppm. Not only is the cost low, but it also does not pollute the material being defoamed.