Application of leveling agents in coatings
1. Leveling agent is divided into two kinds, one is organic leveling agent, the other is non-silicone leveling agent, organic leveling agent is divided into three kinds, polyether modified silicone leveling agent, polyester modified silicone leveling agent, reactive silicone leveling agent. Non-silicone leveling agent is divided into polyacrylate leveling agent, fluorocarbon modified polyacrylate and fluorosurfactant.
2. The role of different leveling agents in the coating system
2.1 Explanation of related terms
Foam stabilization.
Additive added in the coating system, the foaming situation and defoaming speed after oscillation.
Compatibility.
Excellent compatibility is often shown by the addition of additives in the resin, no turbidity and delamination phenomenon.
Static surface tension.
Static surface tension is a measure of the ability of the coating additive to wet and spread on the solid surface under equilibrium surface tension conditions. The smaller the static surface tension value, the stronger the wetting and spreading ability.
Dynamic Surface Tension.
Dynamic surface tension (DST) is measured by bubble tension meter, and this parameter index is more representative in coating applications (e.g. spraying, roller coating). It is a measure of the surface activity of the coating additive during the coating process, i.e. the diffusion ability of the coating additive from the solution to the interface. The smaller the dynamic surface tension value, the faster the leveling of the coating under the same time conditions is indicated.
Long and short waves.
① Long wave: long wave:1-30mm size ripple, can be clearly observed at a distance of 3m, the lower the value, the better the long wave leveling.
② Short wave: 0.1-1mm size ripple, can be recognized only at a closer distance below 3m, the lower the value, the better the short wave leveling.
Fresh reflectivity.
Reflect the reflection of the image clarity indicators, the higher the value is the better the freshness of the reflection, the higher the clarity.
Gloss.
For high gloss products, the higher the data of gloss, the better the visual perception.
Dynamic friction coefficient.
Smoothness is expressed by the size of the coefficient of dynamic friction (μd), the lower the value, the better the smoothness, the better the feel. Excellent slip will result in good scratch resistance and improved adhesion resistance.
Adhesion.
It refers to how firmly the paint film is bonded to the surface of the painted object.
2.2 Effects of adding different types of leveling agents to paint systems on their main properties
2.2.1 Effect on reducing the static surface tension of the system
2.2.2 The effect on reducing the dynamic surface tension of the system
2.2.3 Leveling speed
2.2.4 Action on long and short waves
2.2.5 The effect on fresh reflectivity, gloss
2.2.6 Effect on reducing the coefficient of dynamic friction on the surface of the paint film
2.2.7 Summary of the performance of different types of levelling agents
| Name | Static surface tension | Dynamic surface tension | Leveling speed | Short-wave leveling | Long-wave leveling | Freshness | Gloss | Smoothness |
| Blank sample | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Polyacrylate leveling agent | 1 | 2 | 1 | 1 | 5 | 2 | 0 | 0 |
| Fluorocarbon modified polyacrylate leveling agent | 3 | 3 | 3 | 1 | 5 | 2 | 0 | 0 |
| Fluorocarbon surfactant | 4 | 4 | 4 | 1 | 5 | 2 | 0 | 0 |
| Silicone leveling agent | 5 | 5 | 5 | 5 | 1 | 3 | 5 | 5 |
0=invalid 5=excellent
From the above we can conclude: different types of leveling agents have their own characteristics, according to the specific requirements to be recommended, such as primer and recoatability in consideration, generally recommended with a certain effect of anti-cratering non-silicone leveling agent, while in the top coat or gloss varnish need mirror leveling effect, a single leveling agent has been difficult to meet the requirements, can be considered silicone and non-silicone products with reasonable, synergistic synergistic effect.