News-Details

Analyze the effect and influencing factors of leveling agent

First. Overview of leveling

After the coating is applied, there is a process of flowing and drying to form a film, and then gradually form a flat, smooth and uniform coating film. Whether the coating film can achieve smooth and smooth characteristics is called leveling. In the actual coating process, the coating film defects that often appear are orange peel, fish eyes, shrinkage cavity, pinhole, edge shrinkage, Bernard swirl, sensitive air flow and brush marks when brushing due to poor leveling , The roller marks produced during roller coating are called poor leveling, and the occurrence of these phenomena reduces the decorative and protective functions of the coating. There are many factors that affect the leveling of coatings, such as the volatilization gradient and solubility of solvents, the surface tension of coatings, wet film thickness and surface tension gradients, rheology of coatings, construction technology and environment, etc. The most important factor is the surface of coatings. Tension, the surface tension gradient generated by the wet film during film formation, and the surface tension homogenization ability of the wet film surface. To improve the leveling property of the coating, it is necessary to consider adjusting the formula and adding suitable additives, so that the coating has a suitable surface tension and the ability to reduce the surface tension gradient.

Second. The role of leveling agent

After the paint wets the substrate, the additive that controls its flow to the final leveling is called a leveling agent. The leveling agent can solve the following problems:

Third, the main influencing factors of leveling agent

1. Surface tension gradient------liquid------gas interface

● Surface tension gradients between inner and outer layers cause turbulent flow

● Elimination of surface tension gradient is the key to obtain a flat surface

2. Surface tension------liquid------solid interface

The surface tension is lower than that of the substrate, so that the coating has better substrate wetting power

● Reducing the surface tension of the coating reduces the attraction between molecules on the surface, thereby promoting better leveling performance.

Forth. Influencing factors of leveling speed

● The greater the viscosity, the slower the leveling

● The thicker the coating film, the faster the leveling

● The greater the surface tension, the faster the leveling