1. Mineral oil defoamer

It consists of 75 -- 80% carrier oil, 10 -- 15% hydrophobic particles and 5 -- 10% emulsifier or developing agent. This kind of defoamer is easy to cause oil separation, loss of light and other defects.

2. Silicone defoamer

Silicone defoamant is generally divided into two substances: one is mainly polydimethylsiloxane, in some cases, can also be ethyl and part of hydroxyl, phenyl, cyanide, trifluoropropyl and other siloxane; The other is polyether or organic modified polydimethylsiloxane.

Due to the low surface tension of organosilicon compounds and the incompatibility with most coating systems, organosilicon defoamer is widely used in the coating industry. At the same time, due to the above characteristics, most of the silicone defoamer often need only a small amount of addition can play an excellent defoamer effect, and when enough defoamer effect is achieved, the amount of addition is often not enough to cause significant changes in compatibility, so the silicone defoamer is often used in high transparent system. Similarly, due to the very low surface tension of silicone defoamer, it tends to be distributed on the surface in the system, and its defoamer is mainly based on surface defoamer, which is also the main difference between silicone defoamer and non-silicon defoamer in application performance.

Similarly, due to the low surface tension of silicone defoamer, in the coating system, substances incompatible with the system and with very low surface tension are often the main cause of paint film defects, so silicone defoamer needs special attention in the use of safety. Many times due to the addition of a small amount of compatibility does not cause problems, paint film defects may also appear. Therefore, when selecting some silicone defoamer with high defoamer capacity, special attention should be paid to its safety in the test system.

Silicone defoamer is mainly used in top coat system.

3, non-silicon defoaming agent

Non-silicon defoamer is usually some relatively low polarity resins, such as polyolefin, polyvinyl ether, polyacrylate, polyester and so on.

Non-silicon defoamer also relies on incompatibility with the system and lower surface tension than the system resin to achieve defoamer effect.

Compared with silicone defoamer, non-silicon defoamer has relatively high surface tension, and its migration tendency is generally weaker than that of silicone defoamer, so non-silicon defoamer can be more distributed in the system, so as to help bubble out from the system to the surface of the paint film, and its performance is mainly defoamer.

Since the surface tension of non-silicon defoamer is higher than that of silicone defoamer, greater incompatibility is often required to achieve the same defoamer effect. These limit the use of non - silicon defoamer in some HD systems.

To sum up, silicone defoamer focuses on surface defoamer, while non-silicon defoamer focuses on defoamer. In systems with high requirements for defoamer and defoamer, it is generally recommended to use silicone defoamer together with non-silicon defoamer. The defoamer's defoamer depends on surface tension and compatibility, and its safety is also related to compatibility. What we have to do is to balance all aspects of performance, find the best combination of defoaming effect, compatibility, additives and safety.