The effect of coating thickness on coating quality

Three points of paint, seven points of coating. It is well known that the final effect of coating depends on coating to a greater extent. In the process of coating, there are different spraying equipment, the process is changing, spraying methods, different techniques and many other effects
China
. But there are always aspects that have a greater, qualitatively denatured effect on the final effect of coating. The thickness of the coating film is one of them.
how should we control the thickness of the coating film more reasonably to ensure the quality of the coating film? Here we discuss from different aspects - single-group, double-part, high viscosity, low viscosity, flat spray, three-dimensional spraying.
single-component coating:
single-component coating film-forming process is a physical change, with the paint system moisture, film-forming additives volatile film. In this process, we only need to consider the escape of the micro-bubbles mixed inside the coating film and the leveling of the surface.
For coatings with high viscosity, the coating film is too thin, then poor leveling is prone to dry roughness, the coating film is too thick, it is not possible to ensure that the surface loses fluidity before the micro-bubble escape, thus forming dark bubbles, tweezers and other ills. For low-viscosity coatings, the coating film is thin, the problem is not big, there may be a lack of fullness, but the coating film is too thick, it may appear shrink edges, frames and other ills.
two-part coating:
two-part coating film-forming process is a chemical change, with the paint system moisture, film-forming additives volatile, the main agent and curing agent cross-linked into a membrane. This process is more complex, not only to consider similar to the escape of microfoules in a single-group coating and surface leveling, but also to consider the reaction law of the coating itself - in the film-forming process, the curing agent
-NCO
and
H2O
reaction produced
CO2
.
how to let the bubbles produced by the reaction float to the surface before the table dry, or complete the film-forming process before the side reaction occurs, will be the key to the formation of a good coating film. Although different coatings in the reaction schedule, dry time, mobility and other aspects have certain differences, but we are not difficult to imagine, as far as possible thin coating film, low viscosity is the key to a good film.
the above, thin coating film refers to the thickness of the coating film <
125um
or even lower, low viscosity refers to the thin coating film on the basis of ensuring good wetting and leveling. Of course, this will certainly affect the film plumpness and other decorative effects, so we should try to choose their own plumpness of good two-part paint, or through the primer to improve the light, multi-channel spraying and other ways to improve the deficiency.
three-dimensional spraying:
above on the single and double-part discussion are based on flat spraying. In the facade spraying or modeling spraying and other aspects of more difficult to control, we take facade spraying as an example.
surface spraying, the most important thing is the balance between leveling and hanging. As we all know: reducing the thickness of the paint film is conducive to preventing the flow hanging but not conducive to the leveling; Therefore, the coating process should be in the thickness of the coating film to do a good job of leveling and hanging balance.
the other side needs to solve the problem of deblistering, flat spray, mixed with the paint film bubbles under the buoyant force to reach the surface bubble. In facade spraying, it is difficult for the mixed bubbles to escape the surface bubbles under buoyant force. The thicker the paint film, the higher the viscosity, the more difficult it is to deblister, so the facade spray as low as possible in the film thickness, low viscosity spray.