Distinguishing between defoaming and defoaming agents in the use of defoamers

The main function of defoamer is to eliminate foam. When using defoamer, many people do not understand the difference between defoaming and defoaming. So how to distinguish defoaming or defoaming when using defoamer? Next, the editor of Jianyi Chemical will introduce it to everyone!

At present, the theory of foam formation is different from defoaming and defoaming. The function of water-based paint defoamers is to trap air at the interface. The function of defoamer is to quickly raise the tiny air (microbubbles) dispersed in the coating film to the surface during and after the coating process. However, in practical applications, it is often difficult to make this distinction clearly. Defoamers can also eliminate microbubbles to some extent. The following discusses the defoaming mechanism of defoamers in water-based coatings and inks.

To demonstrate its effectiveness, defoamers must meet certain requirements. One of them is that they must be able to destroy the above foam stabilization mechanism. Therefore, defoamers need to have a certain degree of immiscibility in the system and be able to migrate to the air interface. Of course, serious side effects such as shrinkage caused by the use of defoamers should not occur.

Adding fine hydrophobic particles, such as silica, to defoamers can effectively enhance their defoaming ability. Their mechanism of action can be explained as a process of anti wetting. A stable surfactant bilayer membrane cannot wet hydrophobic solid particles, causing unstable surface tension in local areas and leading to the rupture of the bilayer membrane.

In order to defoamer, the defoamer emulsified into tiny droplets in the paint defoamer must combine with the surfactant layer of the stable foam and penetrate into the bimolecular film of the foam. Next, the water-based ink defoamer must quickly spread through the cracked surfactant layer. At this point, the elasticity of the thin film has significantly decreased compared to the surfactant film of the previously stable interlayer. Finally, this instability leads to the rupture of the bilayer membrane layer, thereby achieving the effect of defoaming. Therefore, immiscibility, high spreading ability, and low surface tension are important properties that every defoamer must possess.