As the core additive in coating formulation, silicone surface additive leveling agent significantly improves the leveling, wettability and durability of coating by regulating surface tension gradient. Its core mechanism of action is derived from the low surface tension characteristics of silicone segments, which spontaneously migrate to the coating surface during film formation to form a monomolecular film layer, thereby eliminating defects such as orange peel and shrinkage caused by surface tension differences.
In solvent-based coating systems, polyether-modified silicone leveling agents have become the mainstream choice because of their dual-use properties of water and oil. For example, a certain type of leveling agent can accurately control its hydrophilic/lipophilic balance by adjusting the segment ratio of ethylene oxide and propylene oxide, achieving excellent interlayer adhesion and anti-blocking properties in wood paint and coil coatings. In the field of water-based coatings, low molecular weight polyether-modified silicone oil (molecular weight <5000) can reduce the surface tension of the system to 20-21mN/m by virtue of its rapid migration characteristics, ensuring complete wetting of low-energy substrates such as polytetrafluoroethylene, while giving the coating anti-scratch properties.
For special process requirements, composite modification technology has further expanded the application boundaries. Acrylate-modified silicone leveling agent achieves the synergistic effect of early rapid leveling and later cross-linking strengthening in UV-curing coatings through double bond copolymerization reaction. The hardness of the cured coating is 30% higher than that of traditional products. In the field of automotive baking paint, alkyl-polyether co-modified silicone oil effectively solves the problem of poor recoating caused by the decomposition of the leveling agent during high-temperature baking due to its thermal stability of 200-220℃.
Three points should be noted in practical applications: First, the amount of addition should be strictly controlled in the range of 0.1%-1.0%. Excessive use will lead to an aggravated foam stabilization effect; second, a heat-resistant leveling agent should be selected for high-temperature curing systems to avoid gloss decay in the coating; third, products with good mobility should be preferred during interlayer coating to prevent the formation of a weak boundary layer at the interface between layers. As environmental regulations become stricter, silicone leveling agents are accelerating their development towards non-fluorinated and low-VOC directions, and will show greater application potential in high-end manufacturing fields such as 3C electronics and new energy vehicles in the future.