The factors affecting the level of powder coating mainly include three aspects:
One is leveling additives, add appropriate leveling additives in the formula of powder coating. When powder coating melting, these additives can quickly reduce the surface tension of the coating, promote the rapid flow of coating before curing film, eliminate or reduce the surface defects such as orange peel, brush marks, ripples, shrinkage holes;
the second is the melt viscosity of powder coating, for thermosetting powder coating, in the melting flow process, accompanied by crosslinking curing reaction, the higher the temperature, the faster the curing reaction, the faster the system viscosity rises, the flow time is shortened, the leveling is restricted.
Therefore, the melt viscosity of powder coating cannot accurately reflect the final leveling property of the coating. The influence of baking process, heating rate and crosslinking curing temperature on the leveling property of the coating must be considered at the same time.
The third is the baking process of powder coating powder manufacturer.
There is a heating process during baking of powder coating, and the speed of heating has a considerable influence on the leveling of coating.
The trend of dynamic viscosity changes with temperature is basically the same, that is, the viscosity decreases with the increase of temperature at the beginning, reaches the minimum value, and then increases with the increase of temperature, which is caused by the cross-linking reaction.
More importantly, the faster the heating rate, the smaller the minimum value of viscosity, and the higher the corresponding temperature is more conducive to the curing of the film, the better the leveling of the film.
The leveling property of powder coating is restricted by leveling auxiliaries, the structure of film forming resin and curing mechanism.
Using appropriate leveling additives, choosing a resin system with low melt viscosity and matching curing process (UV curing), the film with excellent leveling performance can be obtained.