1. Solvent based coating system
Acrylic leveling agents are commonly used in primer and intermediate coat formulations. If degassing and substrate wetting are required, it is advisable to choose medium molecular weight and high molecular weight acrylic leveling agents. In primer, if stronger substrate wetting is required, it is recommended to use organic silicon leveling agents and modified acrylic leveling agents that can significantly reduce surface tension. If organic silicon leveling agents and fluorine modified acrylic leveling agents have auxiliary effects such as foam stabilization and affecting interlayer adhesion, sulfuric acid ester modified acrylic leveling agents should be used.
In the formulation of topcoat and transparent paint, the requirements for the appearance of the paint film are relatively high. Generally, low-molecular-weight acrylic leveling agents can be used to achieve good leveling performance and prevent fogging in the paint film. In the crosslinking curing agent system, the use of acrylic leveling agents containing reactive functional groups often results in better leveling performance and improves the physical and chemical properties of the paint film. If better fluidity or smoothness and scratch resistance are required for the paint film, silicone leveling agent is necessary. In this case, it is best to use a combination of silicone leveling agent and acrylic leveling agent. It should be pointed out that during vertical surface construction, silicone leveling agents provide leveling performance while effectively reducing the tendency of coating sagging. In addition, silicone leveling agents should be used with caution in metal glitter paint formulations, as they may cause uneven arrangement of flake aluminum pigments and result in uneven paint film color.
2. Powder coating system
The leveling process of powder coating is divided into two stages. The first stage is the melting of powder particles, and the second stage is when the powder particles melt and flow into a smooth paint film. Powder coatings do not contain solvents and do not generate surface tension gradients during film formation. Leveling is more related to substrate wetting.
Powder coatings often use acrylic leveling agents. If the leveling agent is in liquid form, it usually needs to be pre made into a masterbatch before use. There are also acrylic leveling agents made into powders, specifically used for powder coatings. These products adsorb liquid acrylic leveling agents onto carbon dioxide powder, while some low-grade leveling agents use carbonic acid adsorption.
If powder coatings require smoothness and scratch resistance, organic silicon leveling agents should be used. There are already specialized organic silicon leveling agents for powder coatings. Be careful to avoid the formation of shrinkage when using organic silicon leveling agents.
3. Water based coating system
The water-based coating system is divided into water-soluble system and latex system.
In water-soluble systems, it is necessary to strongly reduce the surface tension of the system. The most commonly used leveling agents are organosilicon leveling agents and fluorocarbon leveling agents, which have the same effect as their application in solvent based coating systems. Of course, if a truly smooth surface is required, acrylic leveling agents for water-based systems are necessary.
For latex systems, the film-forming mechanism is completely different, and viscosity does not vary with solvent evaporation. The use of leveling agents in the formula may affect the substrate wettability of the draft coating. Acrylic leveling agents can improve the smoothness of the paint film, but the main flowability of the coating is mainly controlled and adjusted by adding rheological control agents.
