The additives used in coatings are mostly surfactants, which reduce the surface tension of gas-liquid, liquid-solid, or gas-solid interfaces to achieve leveling, defoaming, dispersion, and improve adhesion. Organosilicon compounds have low surface tension and high surface activity, and are widely used in coating systems. They are important varieties of coating additives.

When leveling agents need to be used in high-temperature systems (such as baking paint), due to the low decomposition temperature of polyether, it is easy to decompose during use, causing some surface defects of the paint film, such as poor repainting, shrinkage, etc. In this case, it is necessary to choose silicone oil modified with high-temperature resistant groups (such as alkyl modified silicone oil, phenyl modified silicone oil, and polyester modified silicone oil). Relatively speaking, alkyl modified silicone oil can not only provide leveling effect, but also, It also has a good defoaming effect, but its compatibility is poor and is usually not suitable for use in varnish. Both phenyl silicone oil and polyester modified silicone oil have good compatibility and are suitable for use in high-temperature varnish systems, while providing excellent compatibility and high-temperature resistance. With the development of technology, some leveling agents combining organic silicon and acrylic esters have emerged recently. These leveling agents combine the advantages of both and have excellent early and late leveling effects. According to their different chemical structures, they can be divided into acrylic modified silicone leveling agents (with silicone as the main chain and acrylic as the side chain) and silicone modified acrylic as defoamers for coatings, which usually require lower surface tension than the application system and are incompatible with the application system. Organic silicon is widely used as a raw material for defoamers in coatings due to its low polarity structure and incompatibility with most coating resin systems. Usually, polydimethylsiloxane with a relatively high molecular weight (10000~100000) can be used as a defoamer for coatings. Currently, this type of defoamer is widely used in heavy-duty anti-corrosion systems. In order to improve the defoaming efficiency, some white carbon black can also be added as an enhancing component. In addition, due to the high defoaming efficiency of organic silicon, it has a good effect at extremely low addition amounts. In order to facilitate addition, organic silicon defoamers are usually made into solutions with lower concentrations to meet the needs of actual production.

In solvent based coating systems, in order to enhance the defoaming ability of coatings, fluorocarbon modified organosilicon is used. By introducing fluorocarbon chains with lower compatibility and surface tension into the main chain of organosilicon, the compatibility between the coating and the system is further reduced, greatly improving the defoaming effect. The longer the fluorocarbon chains commonly introduced, the better the defoaming effect. This type of defoamer is usually a high-end variety of organosilicon defoamers. In water-based coating systems, due to the high polarity of waterborne resins, conventional polydimethylsiloxane has limited compatibility with the system and is difficult to be directly used as a defoamer. It is usually necessary to modify polydimethylsiloxane with polyether, especially in applications in high gloss systems. Usually, the higher the degree of polyether modification, the better the compatibility, but the defoaming effect will also decrease. Generally, it is necessary to choose the appropriate modification ratio based on the difficulty of defoaming in the system. Under the condition of meeting the defoaming ability, the lower the silicon content, the better.