In many cases, we often confuse wetting agents with leveling agents. Actually, wetting agents and leveling agents are two different additives. However, some leveling agents have a good wetting effect, so they are often taken for granted. D. So what exactly is the difference between the wetting agent and the leveling agent?
An auxiliary agent is used as a wetting agent. The ability to reduce the surface tension is the only index that determines the wetting ability, followed by the compatibility and other factors. The stronger the ability of the additive to reduce the surface tension, the stronger the wetting ability. The commonly used 47V500 is a common wetting agent.
According to the basic principle of paint film leveling, the final force of leveling comes from the surface tension. Although the low surface tension can provide excellent wetting ability, it sometimes has adverse effects on leveling. Usually a wetting agent with a surface tension below 22 will have an adverse effect on the leveling. In other words, a good wetting agent is not always a good leveling agent.
Generally, because of the lower surface tension of the silicone additive, it has a lower surface tension and stronger wetting ability than the acrylic leveling agent. The fluorine-modified acrylate The surface tension of the leveling agent can vary within a wide range depending on the level of fluorine content.
For the silicone additives, especially the modified silicone oil additives, the wetting ability varies greatly with the structure. The important parameters affecting the wetting agent ability are the silicon content and the type of the substituted group. In general, polyether-modified dimethyl siloxane auxiliaries, as the silicon content increases, the wetting agent capacity increases; and when the methyl group in the dimethyl siloxane is long-chain alkyl or aromatic Substitution of the base will further increase the surface tension, ie the wetting ability will be further reduced.
The role of the leveling agent is different. Generally, the role of the leveling agent is to be able to spontaneously migrate to the surface of the paint film after being added into the paint system, to provide a uniform surface tension and maintain the surface tension throughout the paint film. No major changes occur in the drying process.
The quality of a leveling agent depends on its ability to provide uniform surface tension and is not directly related to the level of surface tension. From this point of view, various leveling agents have a certain ability to reduce the surface tension of the system, that is, have a certain wetting ability.