In the coatings industry, pigment dispersants have become an indispensable chemical player due to their unique properties and functions. These magical chemicals are not only lipophilic but also hydrophilic. Like the balance masters in paint, they dominate the dispersion state of pigments in liquids, prevent the precipitation and agglomeration of pigment particles, and create a stable suspension.
Variety of Pigment Dispersants
The diversity of pigment dispersants is reflected in the richness of their types, which mainly include nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. The choice of these dispersants depends on the nature and use of the coating, with different types of coatings requiring different types of dispersants.
Anionic surfactants: Anionic surfactants, such as sodium hexametaphosphate, sodium oleate and sodium alkyl sulfate, are commonly used in solvent-based coatings and water-based coatings. They effectively improve pigment dispersion and provide good stability to coatings.
Cationic surfactants: Cationic surfactants, such as octadecylamine acetate and alkyl quaternary ammonium salts, are primarily used in non-aqueous dispersible coatings. They assist in better dispersion of pigments in solvents, improving the overall stability of the paint.
Nonionic surfactants: Nonionic surfactants, including fatty acid polyoxyethylene esters and alkylphenol polyoxyethylene ethers, are commonly found in water-soluble coatings. This type of dispersant has excellent dispersing and wetting properties and plays a key role in pigment dispersion.
Amphoteric surfactants: Amphoteric surfactants, such as soy lecithin, form a bilayer structure by adsorbing on the surface of pigments, increasing the wettability of particles and improving dispersion. This has a positive effect on the stability and dispersion of the coating.
How pigment dispersants work
The working principle of pigment dispersants is based on the principles of adsorption and surface activity. By adsorbing to the surface of the pigment particles, the pigment dispersant changes the surface properties and energy state of the particles, and Young's theorem is used to explain this change.
The polymer pigment dispersant forms an adsorption layer on the particle surface, which increases the charge on the particle surface and increases the reaction force between particles. This prevents electrostatic attraction between particles, keeping them dispersed and preventing sedimentation and agglomeration.
In addition, pigment dispersants can form a bilayer structure, and the polar end of the outer layer has a strong affinity for water. This increases the wettability of the solid particles to water, creating electrostatic repulsion that pulls the particles away from each other. This ensures uniformity and stability of the dispersion system.
Common pigment dispersants
There are many types of pigment dispersants, including methylcellulose, silica sol, polyacrylic acid, polyacrylic acid sodium salt and trisodium phosphate, etc. Polyethylene glycol dispersants are also widely used in water-based coatings. They have good water solubility and help reduce surface tension and improve wettability. These dispersants not only adsorb on the surface of the pigment, creating a steric effect, but also prevent contact between pigment particles, prevent harmful flocculation, and keep the dispersion system stable.
Application of pigment dispersants
Overall, pigment dispersants play an integral role in the coatings industry. Pigment dispersants ensure the performance and quality of paints by improving pigment dispersion. From construction to automotive coatings to industrial coatings, coatings in different fields are inseparable from these seemingly small but crucial dispersants. Their application allows pigments to work better, ensuring uniformity and stability of coatings, giving a variety of coatings a high-quality appearance and long-lasting performance.
In the future, with the continuous development of science and technology and the pursuit of environmental protection performance, the research and innovation of pigment dispersants will continue to promote the advancement of the coating industry. As a master of balance, pigment dispersants will continue to provide more choices and solutions for the coatings industry, helping the industry move to a higher level of development.
