替换城市 Principle and influencing factors of special ink defoamer agents for paints(2)

Good paint defoamers not only have a good defoaming effect in paint systems, but also maintain defoaming ability at room temperature and under heating environments. In addition, it cannot be compatible with foam system. If the compatibility is good, it will help to produce foam. While the paint ink defoamer has good dispersibility in the foaming system, specifically refers to the uniform and smooth diffusion of the defoamer on the surface, which can cover the foam to achieve the elimination effect. Its working principle is to reduce the surface tension of the liquid around the foam, so that small foam can gather into large foam, and finally foam will burst.

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There is no unified understanding of the mechanism of defoaming agents. According to the mechanism of defoaming agents proposed by predecessors, there are generally the following types: [4]
General defoaming mechanism
Typical defoaming mechanisms with a broad overview are the Robinson defoaming mechanism and the Ross hypothesis. Among them, Robinson mechanism is the basis of Ross hypothesis, which mainly emphasizes the liquid drainage of defoamer destroying foam and Marangoni effect to realize defoaming; The Ross hypothesis is based on the fact that the defoamer particles are insoluble droplets, while some defoamers actually produce defoaming effects in a dissolved state, so the defoaming mechanism of the Ross hypothesis is not comprehensive

Leveling principle
The compatibility of acrylic leveling agents is an important indicator of their ability to control the surface state of the coating film. The compatibility is too good to dissolve in the coating film, which will not form a new interface on the surface of the coating film and provide no leveling effect; Due to poor compatibility, it is impossible to uniformly distribute on the surface of the coating film, which can gather together and easily cause shrinkage defects. It can reduce the gloss of the coating film and produce adverse side effects such as fog and shadow. Only with ideal controlled compatibility can a new interfacial layer be formed on the surface of the coating film, playing a leveling role

Influencing factors of special defoaming agents for paints:

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surface tension

替换城市  The level of coating surface tension has a significant impact on defoaming agents. The surface tension of defoaming agents is lower than that of coatings, otherwise they cannot have defoaming and antifoaming effects. The surface tension of a coating is a variable factor, so when selecting defoamers, it is necessary to maintain a constant surface tension, taking into account the surface tension variation factor.

powder

unstable

Effects of other additives

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