Why does The Powder Coating Blister?

The appearance information of the defoaming agent does not specifically determine the quality of the defoaming agent, but it still has a certain influence on the defoaming agent. The color, viscosity and odor of the defoaming agent are complementary to the performance of the defoaming agent.

Defoamer for paint

The formation of pinholes in powder coatings is closely related to its unique melt-solidification process. Therefore, to study the formation mechanism of pinholes in powder coatings, it is necessary to clarify the melt-solidification process of powder coatings.

Powder coating, as its name suggests, is a powder coating that is first applied by electrostatic spraying to a surface of the substrate in a loose structure. After the spraying is completed, the workpiece enters the hot drying tunnel, the substrate and the coating are heated and melted, and the original loose structure or accumulation mode is destroyed by the melt flow of the powder particles. It is important to mention that a local eddy current effect caused by liquid flow during film formation is called the Bernard vortex. The essence of the Bernard vortex is the change of surface tension caused by the viscosity change accompanying the melt-solidification of the powder coating, so that the fluid with high viscosity and low surface tension sinks to the middle of the vortex (recess), and the low viscosity is high. The fluid of the surface tension rises to the periphery (convex) of the vortex until the curing is completed. During this process, the gas (air) in the original loosely accumulated voids after coating will accumulate during the process of powder melt collapse to form foam, and small molecules of gas from the inside of the coating or the substrate will also aggregate to form foam. And was discharged. As the viscosity of the system increases with solidification, the foam trapped in the Bernard vortex eventually form pinholes during the discharge process. Therefore, to prevent and eliminate pinholes in powder coatings, it is necessary to analyze the root causes of small molecules (foam) in the coating, and then prescribe the right medicine to prevent and solve the pinhole defects of the coating film.

Zilibon is a manufacturer with 16 years of application experience. It has far more defoaming technology than other antifoaming agents in the market. From the above cases, we prove the strength of our Zilibon defoamer. We have a group of excellent defoaming engineers, and An independent laboratory that facilitates defoaming experiments with foam that are difficult for customers to solve. If you want to know more about defoaming agent products, you can call our hotline: +86 13929201380.