What are the applications of surfactants in coatings?

Surfactants are a class of compounds with unique molecular structures that can align at interfaces or surfaces, significantly altering surface tension or interfacial properties. In the coatings industry, surfactants play a crucial role in various applications, including emulsification, wetting, dispersion, defoaming, leveling, antistatic effects, and more, thereby enhancing the stability, application performance, and final quality of coatings.

1.Emulsification​

In emulsion-based coatings (such as waterborne coatings), emulsifiers are essential. They reduce the interfacial tension between oil and water phases, enabling the formation of stable emulsions from immiscible components. Common emulsifiers include anionic surfactants (e.g., sodium dodecylbenzene sulfonate) and nonionic surfactants (e.g., polyoxyethylene ethers).

2.Pigment Wetting and Dispersion​

The uniform dispersion of pigments in coatings directly affects opacity, stability, and color performance. Wetting and dispersing agents reduce interfacial tension between pigments and binders, promoting uniform wetting and stable dispersion while preventing agglomeration and settling.

3.Defoaming and Foam Control​

During production and application, coatings tend to generate bubbles, which can compromise film appearance and performance. Defoamers (e.g., silicone-based or mineral oil-based) destabilize foam structures, minimizing bubble formation and ensuring a smooth, defect-free coating surface.

4.Leveling Improvement​

The leveling property of coatings determines the smoothness and appearance of the dried film. Leveling agents function through two primary mechanisms:

•​ Reducing surface tension: Ensures even spreading on substrates, minimizing defects like orange peel or cratering.

• ​Modulating solvent evaporation: Extends flow time, allowing the coating to level adequately before curing.

5.Antistatic Functionality​

In electronics, packaging, and other fields, coatings may accumulate static charges due to friction, posing safety risks. Antistatic agents (e.g., cationic surfactants) adsorb ambient moisture to form a conductive layer on the coating surface, facilitating charge dissipation and mitigating electrostatic hazards.

6.Antimicrobial and Fungicidal Protection​

In humid environments, coatings are prone to microbial growth, leading to film degradation. Antimicrobial and fungicidal agents (e.g., quaternary ammonium compounds) inhibit microbial proliferation, extending the shelf life and service durability of coatings.

7.Gloss Enhancement and Slip Improvement​

Certain coatings require high gloss or smooth surfaces (e.g., furniture or industrial coatings). Gloss enhancers and slip additives (e.g., waxes or silicones) improve film reflectivity and reduce surface friction, enhancing wear resistance and tactile properties.

Surfactants serve multiple roles in the coatings industry, from optimizing processing performance to elevating the final film properties, all leveraging their unique interfacial regulation capabilities. With the advancement of eco-friendly and high-performance coatings, novel, efficient, and low-toxicity surfactants will remain a key focus in future coatings technology research.