Application of molecular structure and action mechanism of leveling agent in coatings
Leveling agent is a common coating additive, which can promote the formation of a flat, smooth and uniform coating film during the drying process. The flatness of the coating film is called leveling. There are many types of leveling agents, and different types of leveling agents are used for different coatings.
After coating, the paint film will undergo extremely complex physical and chemical changes in the drying process. These phenomena include flow and level. Flow is a movement, and leveling is the purpose of movement - smoothing or leveling. These changes and the nature of the coating itself will significantly affect the flow and leveling of the coating. Due to poor leveling performance, there are brush marks when brushing, roll marks when rolling, orange peel when spraying, shrinkage, pinholes, sagging and other phenomena when drying, it is called poor leveling performance. These phenomena reduce the decorative and protective functions of the coating.
Application of molecular structure and action mechanism of leveling agent in coatings (Fig. 1)
1. Action mechanism of leveling agent
As a leveling agent, the following two points are generally required:
(1) It has certain compatibility with the system.
(2) The surface tension needs to be lower than the system.
These two factors affect the migration of leveling agent. Only when the leveling agent spontaneously migrates to the surface of the paint film, it is called leveling.
Action mechanism of leveling agent migration mechanism: the migration orientation of leveling agent follows the "principle of minimum energy" in physics, that is, it flows spontaneously from places with high energy to places with low energy.