In modern industrial production, foam is everywhere. Foam causes various problems in industrial production. In order to prevent foam from overflowing, the feeding coefficient is forced to be lowered by 30%-50%; foam overflow leads to waste of raw materials; foam occupies space and affects reaction speed, so the production cycle is forced to be extended. 



Foam can affect product quality. To address the foam problem, the most direct solution is to use a defoamer. 



A defoamer is a type of additive that is used to eliminate foam that forms during the production process. Organic silicone defoamers are composed primarily of silicone oil, an organic silicon component. Silicone oil is an oil-like liquid that does not evaporate at room temperature and is insoluble in water, animal and plant oils, and mineral oil, or has very low solubility. It can withstand high temperatures as well as low temperatures. Its chemical properties are inactive, and its physical properties are stable, with no biological activity. 







The Mechanism of Action of Organosilicone Foam Inhibitors 



Organosilicone defoamers primarily work by the action of surface tension to eliminate foam. When added, organosilicone compounds dissolve in water to form a water solution, which forms a layer of hydrophobic surfactant solution in water. 




Because of the amphipathic properties of hydrophobic surfactant molecules, the solution of this surfactant has a certain degree of strong interfacial tension, which prevents the surface tension of the foam liquid. Additionally, due to the strong adsorption of hydrophobic surfactant molecules to water, hydrogen bonds are formed between water molecules and hydrophobic groups, thus preventing the surface tension of the foam liquid. 


Advantages of Organic Silicone Defoamers 


01 Wide range of applications 


Because of the special chemical structure of silicone oil, it is neither soluble in water or substances containing polar groups, nor soluble in hydrocarbons or organic compounds containing hydrocarbon groups. Due to its insolubility to various substances, silicone oil has a wide range of applications, both in water-based systems for foam control and in oil-based systems. 


02 Low surface tension. 


The surface tension of silicone oil is generally 20-21 dynes/cm, which is lower than that of water (72 dynes/cm) and most other foaming liquids, making it an effective defoamer. 


03 Good thermal stability 


For example, common dimethicone can withstand temperatures up to 150℃ for an extended period of time and 300℃ or more for short periods of time, and its Si-O bonds do not break down. This ensures that organosilicone defoamers can be used over a wide temperature range. 


04 Good chemical stability 


Because Si-O bonds are relatively stable, silicone oil has high chemical stability and is difficult to react chemically with other substances. Therefore, as long as the formulation is reasonable, organic silicone defoamers can be used in systems containing acids, bases, and salts. 


05 Physiological Inertia 


Silicone oil has been proven to be non-toxic to both humans and animals, with a half-lethal dose greater than 34 grams per kilogram. Therefore, organosilicon defoamers (in suitable combinations with non-toxic emulsifiers, etc.) can be safely used in the food, medical, pharmaceutical, and cosmetics industries. 


06 Strong foam-dispersing ability 


Silicone defoamers not only effectively break down existing foam, but also significantly suppress foam and prevent its formation. They are used in very low concentrations, typically only one part per million (1 ppm) of the foaming medium, yet they are effective in producing defoaming effects. The common range of use is 1 to 100 ppm. Not only are they cost-effective, but they also do not contaminate the substances being defoamed. 



Method of Using Silicone Defoamers 



Silicone defoamers have excellent defoaming and foam-suppressing properties and can be added after foam formation or as a foam-suppressing component in the product. Depending on the specific use system, the recommended addition amount of defoamer is 10 to 1,000 ppm. The addition amount should be determined based on specific circumstances. 



The organosilicone defoamer products can be used directly or diluted before use. If it can be fully dispersed and stirred in the foaming system, it can be directly added without dilution. If dilution is required, dilution method should be followed. Diluting the product directly with water is not advisable, as it may cause layering, emulsification failure, etc., thus affecting product quality.