替换城市 Principle and influencing factors of special paint defoamer agents for paints(4)

viscosity-reducing

dispersant

viscosity-reducing

wetting

Polyether polyester modified organosiloxane
An organic polysiloxane with a comb like structure. N+m is about 50-250, and the molecular weight is controlled between 1000-150000. Its compatibility is adjusted by polyethers and polyesters, and the longer the chain, the better the phase compatibility. Polyether modifications are the most common in this category, typically using ethylene oxide and propylene oxide. With the increase of the content of ethoxy groups, their compatibility with water also improves, so it is also possible to synthesize water-soluble siloxane type leveling agents. Ethylene oxide and propylene oxide can be used alone or mixed to control hydrophilicity and lipophilicity. If both ethoxy and propoxy groups are contained, a silicone based leveling agent for both water and oil use is prepared,

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.

Solid content, viscosity, elasticity of paint

替换城市  High solid thick film, high viscosity and high elasticity coatings are very difficult to defoamer. In these coatings, defoamer diffusion is difficult, microbubbles become larger slowly, foam migration ability decreases, foam viscoelasticity is large and many other adverse defoamer factors. Foam in these coatings is very difficult to eliminate, so defoamer and defoamer should be used together.