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替换城市 Principle and influencing factors of special UV curing defoamer agents for paints(3)

2023-05-22

Most surfactants used in coatings tend to be functionally incompatible with UV curing defoamer. In particular, emulsifiers, wetting and dispersing agents, leveling agents, thickeners, etc. can have an impact on the effectiveness of defoamers. Therefore, when coordinating various additives, it is necessary to pay attention to the relationship between different additives and select a good balance point.

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Baking temperature

Defoaming mechanism of hydrophobic solid particles
Hydrophobic solid particles in the foam system will first attract the hydrophobic end of the surfactant, making the hydrophobic solid particles become hydrophilic, thus reducing the concentration of surfactant in the foam film and promoting the foam to burst. This defoaming mechanism cannot explain the action mechanism of other defoaming agents, which is too one-sided. [4] Other reasons for the bursting of foam are the impact caused by the expansion of defoamer, the solubilization of surfactant and the collapse of electrolyte, and the bursting of electric double layer on the liquid film surface. [4] It can be seen from the above defoaming mechanisms that each defoamer has different emphasis on different foam systems, but defoaming is achieved by destroying the stability factors of foam

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When the paint is baked at high temperature at room temperature, its viscosity will drop at the beginning, and bubbles can move to the surface. However, because of the volatilization of solvent, the curing of paint, and the increase of surface viscosity, the foam will become more stable and retain on the surface, resulting in shrinkage and pinholes. Therefore, the baking temperature, fixing speed, and solvent volatilization rate also have an impact on the effect of defoamer.