As a defoamer for coatings, it usually needs to have a lower surface tension than the application system, and at the same time be incompatible with the application system. Due to its low polar structure, silicone is not compatible with most paint resin systems, so it is widely used as a raw material for paint defoamers.

Usually, polydimethylsiloxane with a relatively large molecular weight (10 000 to 100 000) can be used as a paint defoamer. At present, 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 a synergistic component. In addition, due to the high defoaming efficiency of silicone, it has a good effect at a very low dosage. In order to facilitate the addition, the silicone defoamer is usually made into a lower concentration solution to adapt to the actual production. need.
In solvent-based coating systems, in order to enhance the defoaming ability of coatings, fluorocarbons are used to modify silicones. By introducing fluorocarbon segments with lower compatibility and surface tension into the main chain of silicones, the coatings and coatings are further reduced. The compatibility of the system greatly improves the defoaming effect. Usually, the longer the fluorocarbon chain introduced, the better the defoaming effect. This type of defoamer is usually a high-end variety of silicone defoamers.

In water-based coating systems, due to the high polarity of water-based resins, conventional polydimethylsiloxane has limited compatibility with the system, and it is difficult to be directly used as a defoamer. It is often necessary to modify polydimethylsiloxane with polyether, especially for applications in high-gloss systems. Generally, the higher the degree of polyether modification, the better the compatibility, but the defoaming effect will also decrease. Generally, it is necessary to select the appropriate modification ratio according to the difficulty of defoaming the system, and to satisfy the defoaming ability. Under certain conditions, the lower the silicon content, the better.

Water-based silicone defoamers are divided into two categories: concentrated type and emulsion type according to their own state. The agent is obtained by emulsification of concentrated defoamer. Through emulsification, the convenience of use is greatly improved, and it can be introduced into the system with simple stirring.