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

2023-04-24

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dispersant

unstable

Most surfactants used in coatings tend to be functionally incompatible with paint 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.

Baking temperature

anti-scratch

Alkyl modified organosiloxane
As mentioned earlier, polyether modified polysiloxanes have some shortcomings; Alkyl modified polysiloxanes have precisely these advantages.
This series of polysiloxane products also belong to the comb structure. The molecular weight of this type of product is relatively small, around 10000, and n+m is about 30-50. The main purpose of modifying with alkyl is to improve thermal stability, compatibility, and unstable foaming, and even to have defoaming functions. However, as the modified alkyl chain increases, its ability to reduce surface tension also decreases

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.