Defoamer is an additive to remove foam. In the production and application process of coating, textile, medicine, fermentation, paper making, water treatment and petrochemical industry, a large number of foams will be produced, which will affect the product quality and production process. Based on the suppression and elimination of foam, a specific amount of defoamer is usually added to the production.

The main components of defoamer are active ingredient, emulsifier, carrier and emulsifying agent, among which the active ingredient is the most important core part, playing a role of breaking bubbles and reducing surface tension. Emulsifiers disperse active ingredients into small particles for better dispersion into oil or water, resulting in better defoaming effects. The carrier occupies a large proportion in the defoamer, and its surface tension is not high, which mainly plays the role of supporting medium. It is beneficial for defoaming, and can reduce the cost. Emulsifying agent makes the emulsifying effect better.

There are many methods for classifying defoamers according to different classification standards. For example,according to the form, it can be divided into solid particle, emulsion, dispersion, oil and paste type. According to the application of defoamers in different industrial production, it can be divided into textile industry defoamer, paper industry defoamer, coating industry defoamer, food industry defoamer and petroleum industry defoamer, etc. According to the chemical structure and composition of defoamer, it can be divided into mineral oil, alcohols, fatty acids and fatty acid esters, amides, phosphate esters, silicone, polyether, polyether modified polysiloxane defoamer.

Non-silicon defoamer mainly includes alcohols, fatty acids, fatty acid esters, phosphate esters, mineral oils, amides and other organic compounds. In the amides, monoamide, bisamide are usually used. In addition, there are nitrogen-containing compounds such as trialkylmelamine,cyanuramide chloride melamine and aliphatic amine. Phosphates include monoalkyl, dialkyl phosphates and fluorinated alkyl phosphates, which are often used for defoaming of detergent products. Carboxylates include three types of substances: fatty acids such as lauric acid and palmitic acid. Fatty acid esters include fatty acid glycerides, animal and vegetable oils, etc. Fatty acid soaps include calcium, aluminum, and magnesium soaps of stearic acid and palmitic acid. Fatty alcohols and ethers include linear and branched chain alcohols and ethers.

Polyether defoamer is a copolymer of ethylene oxide and propylene oxide, which mainly uses its solubility and different characteristics at different temperatures to achieve defoaming effect. At low temperature, polyether is dispersed into water,and when the temperature continues to rise, the hydrophilicity of polyether gradually decreases until the turbidity point, so that the polyether becomes an insoluble state to play the defoaming role. By adjusting the type of polyether and the proportion of raw materials during the preparation process, its cloud point can be changed, which can be applied in different industries.