Selection of defoamers in powder coatings

How to effectively eliminate bubbles generated during the preparation process of powder coatings? What should be noted when choosing defoamers? 

Benzoin is the most effective defoamer and defoamer for high gloss powder coatings, which can effectively eliminate native pinholes under normal film thickness (60-90 μ m). Benzoin also has a certain synergistic effect on pinholes caused by other reasons, but its effect is often limited. Excessive use of benzoin can also lead to yellowing of the coating, and benzoin itself is also a substance that decomposes and sublimates upon heating. Excessive use can have negative effects.

Defoamers containing amide and hydroxyl groups can effectively improve the wetting performance of coatings on substrates, as well as improve the wetting performance of resins on pigments, especially inorganic pigments and fillers, reduce the melt viscosity of coatings, and effectively eliminate bubbles caused by various reasons. Of course, it is also necessary to choose resins with low viscosity and gelation time to prevent serious problems with foam formation.

Transparent powder defoamer:As a special type of powder coating, the principle and defoaming method of pinholes in transparent powder are the same as those in ordinary powder coatings. One special point is that transparent powder is a highly transparent system, and the entire system is optically isotropic without severe phase separation. Therefore, in the process of defoaming, the defoaming and degassing agent added must be completely compatible with the system. In this sense, such defoamers need to be carefully selected.