Лако-красочные материалы — производство

The term flow and leveling in coatings is associated with smoothe — ning of a coating film after application and during curing that leads to evenness of the coating surface. Though flow and leveling has no influence on a coating’s performance properties, it plays a vital role in aesthetics. The term leveling can be defined as the ability of a liquid coating to form a level surface even though an uneven surface or surface defects result during or after application. Flow and leveling agents are the additives used in a paint formulation to enhance a film’s flow and leveling to eliminate surface defects such as brush marks, orange peel and craters.

Important factors influencing flow and leveling of coatings include viscosity, surface tension and wet film thickness. Due to surface ten­sion, the liquid film tends to minimize its surface area, which drives flow, reduces unevenness and creates an even surface (because an uneven film has greater surface area than a smooth film). Viscous resistance is the obvious factor countering the leveling influence of surface tension. Thus, lower viscosity after application of the wet coating promotes better flow and leveling but it will also lead to the problem of sagging. Generally, a more Newtonian rheology is desirable for better leveling. Deflocculated and well-dispersed systems provide more Newtonian flow, and therefore, good wetting and dispersing agents have a side effect of being leveling agents.