The adhesion of the paint film is caused by the mutual gravitational force between the water-based paint and the polar group on the surface of the coated substrate, and the mutual gravitation between the polar groups is premised on the good wetting of the surface of the coated substrate with an aqueous coating. Since the wetting condition of the coating on the surface of the coated substrate depends on the surface tension of the paint, the surface tension of the coating can be reduced to improve the wetting efficiency and enhance the adhesion of the waterborne paint film to the substrate surface.

The wetting of the aqueous coating to the substrate is achieved by the flow of the coating. The paint must be in the application of a good flow, even if the powder coating must also reach the flow state; only through the flow of paint to wet the coated surface, in order to achieve the purpose of good adhesion of the film on the substrate. In general, the paint is not wet, the interface is small, the adhesion is poor; the other hand, the paint is so moist, the interface is large, the adhesion is good.

When low molecular weight substances or adjuvants (such as stearates, plasticizers, etc.) are present in aqueous coatings, they create a weak interfacial layer between the coating and the coating, affecting the effect of the paint on the substrate Wetting, reducing adhesion. In addition, the substrate surface adhesion of water, dust, acid, alkali and other impurities, it will cause the film and the substrate between the weak interface layer, the role of paint on the substrate wetting effect, reduce the polar point , Resulting in decreased adhesion of the paint film.