The role of coating defoamer
1, The defoamer can be added in the stage of foam formation or after the formation of the defoamer, after adding the defoamer, the uniformly dispersed defoamer will penetrate into the foam elastic film and distribute in the foam film, reducing the surface tension leading to the rupture of the foam.
2, Uniformly dispersed defoamer penetrates into the foam thin layer and forms a single molecule film, which reduces its adhesion and makes it easy for the thin layer to break.
3, The hydrophobic particles contained in the defoamer reach the surface of the thin layer and start to adsorb the surfactant at the top of the thin layer. And the foam will break due to the gradual disappearance of surfactant.
Bubble generation and bubble stabilization principle: In the production of coatings, air will be involved in the formation of bubbles, and the raw materials such as surfactants and dispersants agent will make the bubbles stable.
During the construction of the paint, bubbles will also be generated, which mainly depends on the construction method of the paint. For example, curtain coating can continuously involve air in the paint, airless spraying is also easy to involve air, and spraying under relatively low humidity conditions or under high temperature conditions can easily generate bubbles.
Principle of bubble stabilization.
Marangoni effect (surfactant causes can liquid to produce reflux, which can counteract the effect of gravity)
Electrostatic effect: the electrostatic repulsion of the surfactant thickens the liquid layer film of the bubble, thus stabilizing the bubble.
Leave a message
We’ll get back to you soon