Polymeric dispersing agent in paint applications
Industrial coatings (automotive refinish and plastic paints) Wood coatings Solvent inks
Thickeners will make it difficult to defoam high-viscosity coatings, so thick paste coatings have their special defoamers. High solids or thick coatings are difficult to achieve complete defoaming.
The coating method also has a great influence on the choice of defoamer. Generally speaking, the defoaming of airless spraying is more difficult than that of air spraying, so it is necessary to mix and use foam inhibitors and defoamers. Flow coating construction requires more foam than dip coating construction. Flow coating construction will not only have bubbles on the surface of the coating, but also foam between the metal surface wax dispersion process and the coating, which needs to be removed with different defoamers. It is difficult to break bubbles during the curtain coating process, so the paint and construction parts themselves must be as bubble-free as possible, so that foam inhibitors need to be used in the coating; after the surface is coated and painted, the bubbles need to be eliminated as soon as possible, so the bubble must also be broken Agent. Compared with the same direction roller coating and the reverse roller coating, the defoaming of the reverse roller coating is more difficult.
The drying time of the coating film has a great bearing on the choice of defoamer. For coatings with short drying time, the coating fixes quickly and the wet film has less time to flow. The defoamer will complete almost instantly. Even if the bubbles burst, there is no flow for a certain period of time, leaving voids. Therefore, the drying time of the wet film is an important parameter that needs to be considered when choosing a defoamer. For shorter drying time, you need to choose a defoamer with strong defoaming power.
The defoamer for coatings always has a suitable range and a certain degree of specificity. However, the defoaming performance of most defoamers is always good when it is alkaline, but with a jet lag when it is acidic. When the water-soluble paint is thermally cured, due to the volatilization of the solubilizing amine, the pH value will also change, from alkaline to acid, then the defoaming performance will be affected, or it means that another type of defoamer needs to be used.
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