The method of using leveling agent needs to be targeted and operated according to the type of coating system, construction requirements and characteristics of leveling agent. It is divided into the following points:
1. Select the type of leveling agent according to the coating system
Solvent-based coatings
Primer/mid-layer paint: acrylic leveling agents (such as medium or high molecular weight acrylic leveling agents) are preferred. When the wettability of the substrate needs to be enhanced, phosphate-modified acrylic leveling agents or silicone leveling agents can be selected.
Topcoat/clear paint: Use low molecular weight acrylic leveling agents or acrylic leveling agents containing reactive functional groups, and silicone leveling agents can be used to improve smoothness and scratch resistance; silicone leveling agents can reduce sagging when applied on vertical surfaces.
Powder coatings
The liquid leveling agent needs to be made into a masterbatch in advance or a powdered acrylic/silicone leveling agent should be selected to avoid shrinkage problems.
Water-based coatings
Water-soluble system: Use silicone or fluorocarbon leveling agents to reduce surface tension, and use acrylic leveling agents to improve flatness.
Latex system: Use rheology control agents to adjust fluidity, and acrylic leveling agents to help improve the flatness of the paint film.
2. Usage steps and operation points
Addition amount control
Excessive addition will cause shrinkage and sagging, while insufficient addition will not have a significant effect. The specific addition ratio needs to be determined based on the viscosity and leveling requirements of the coating, combined with experiments. For example: the general addition amount of mixed solvent leveling agents is 2%-7% of the total amount of the coating.
Stirring method
It is necessary to stir thoroughly until the leveling agent is evenly dispersed, and the stirring time generally does not exceed 10 minutes. Water-based coatings can use electric stirrers (200-500 rpm), and high-speed stirrers combined with pumping processes are recommended for large-area construction.
Coating method adaptation
Brushing, roller coating, spraying and other methods need to match the characteristics of the leveling agent. For example: silicone leveling agent can reduce orange peel phenomenon during spraying, but attention should be paid to the arrangement of aluminum pigments in metallic glitter paint.
III. Precautions
Compatibility verification
Before use, the compatibility of leveling agent and coating should be tested to avoid shrinkage or haze. For example: silicone leveling agent needs to be modified before use to solve the problem of recoating.
Temperature and environment
In cold environment, it is recommended to stir with warm water (≤40℃) and keep the mortar temperature ≥5℃.
Functional balance
It is necessary to combine different types of leveling agents (such as acrylic + silicone) or use defoamers to balance the leveling, defoaming, wetting and other properties.