What is adhesion?
Adhesion is the strong paint and varnish material clutch applied to the surface. This materials property is due to the physical and chemical interactions of the active groups of the binder with the active centers of the painted product.
In case of low index the coating will be very easy to remove or fall away on its own. Such a coating is short-lived and does not protect the product from anything.
Adhesion of different materials
Different materials have different degrees of adhesion. First Of all, it depends on the atomic volume of the metal when adhesion occurs between the metal and the film. The higher the index is the worse the hitch. In this regard aluminum, zinc, tin and lead “work” well, in contradistinction to iron and all kinds of alloys which are based on it.
In some cases, poor adhesion may be due to an oxide film on the metal surface.
In order for the adhesion to be the maximum possible, the paint and varnish material should flow as much as possible into all pores, microcracks and surface depressions.
The painted material can be phosphated or oxidized before spraying for improving these indicators.
They have special molecules: one side of them binds to this polymer, and the other to the substrate. This is how oriented adsorption layer forms.
If two identical polymers come into contact, they can stick together. This is called autohesion. And the strength of their adhesion will constantly increase.
Powder Coating Adhesion
Adhesion has a significant effect on impact resistance, weathering, corrosion and flexibility of the painted product.
In powder coating, preparation of the painted surface to application plays a huge role in adhesion improvement. It is necessary to clean the surface thoroughly from any dirt and scale before applying coatings. And also it must be degreased.
Adhesion check
It is not very difficult to check the degree of adhesion. For example, if you took out a painted product from the polymerization oven and you can easily remove the coating with your fingers, then it is clear that the adhesion is extremely poor. But it also happens that the adhesion is insufficient, but you can not indicate that visually.
For determining adhesion cover level to the metal you can run an express test. Make several cuts with a lattice on the coating (you can use a special device – an adhesion meter) and visually estimate the condition of the coating. If the coating holds up well, then everything is fine. But if it is erased then the adhesion is not good enough.
