Most of the additives used in the coating are surfactants, which achieve leveling, defoaming, dispersing and improving adhesion by reducing the surface tension of the gas-liquid, liquid-solid or gas-solid interface. Organosilicon compounds have low surface tension and high surface activity, which are widely used in coating system and are important varieties of coating additives.

When the leveling agent needs to be used in a high temperature system (such as baking paint), due to the low decomposition temperature of polyether, it is easy to decompose in the process of use, resulting in some paint film surface defects, such as poor recoating, shrinkage holes, etc., then it is necessary to select modified silicone oil containing high temperature resistant groups (such as alkyl modified silicone oil, phenyl modified silicone oil and polyester modified silicone oil, etc.). In addition to providing leveling effect, alkyl modified silicone oil also has a good defoaming effect, but its compatibility is not good, usually not suitable for use in varnish. The compatibility of phenyl silicone oil and polyester modified silicone oil is better, suitable for use in high temperature varnish system, while providing excellent compatibility and high temperature resistance. With the development of technology, there have been some leveling agents combining silicone and acrylic ester, which combine the advantages of both at the same time, and have excellent early leveling and late leveling effect. According to their different chemical structures, they can be divided into acrylate modified silicone leveling agents (silicone as the main chain, acrylic as the side chain) and silicone modified acrylate as a coating defoamer usually need to have a lower surface tension than the application system, and are incompatible with the application system. Because of its low polarity structure, silicone is incompatible with most coating resin systems, so it is widely used as the raw material of coating defoamer. Generally, polydimethylsiloxane with a relatively large molecular weight (10 000 ~ 100 000) can be used as a coating defoamer, and at present, this type of defoamer is widely used in heavy anti-corrosion systems. In order to improve the defoaming efficiency, some white carbon black can also be added as a synergistic component. In addition, due to the high defoaming efficiency of silicone, it has a good effect under a very low amount of addition, in order to facilitate the addition, the silicone defoaming agent is usually made into a lower concentration solution to meet the needs of actual production.

In the solvent-based coating system, in order to enhance the defoaming ability of the coating, fluorocarbon will be used to modify silicone. By introducing fluorocarbon chain segments with lower compatibility and surface tension into the main chain of silicone, the compatibility between the coating and the system will be further reduced, and the defoaming effect will be greatly improved. Generally, the longer the fluorocarbon chain is introduced, the better the defoaming effect will be. This type of defoamer is usually the high-end variety of silicone defoamer. Due to the high polarity of the water-based resin, the conventional polydimethicone has limited compatibility with the water-based coating system and is difficult to be used as a defoamer directly. It is usually necessary to modify polydimethylsiloxane with polyether, especially in the application of high-light systems. Generally, the higher the degree of polyether modification, the better the compatibility, but the defoaming effect will also decline, generally need to choose the appropriate modification ratio according to the difficulty of the system defoaming, under the condition of meeting the defoaming ability, the lower the silicon content, the better.