Comparative Study of the Performances of Al(OH)3 and BaSO4 in Ultrafine Powder Coatings

Abstract

Ultrafine powder coatings are one of the development directions in the powder coating industry, as they can achieve thin coatings with good leveling and high surface smoothness comparable to liquid coatings. Compared to regular coatings, they experience a higher sensitivity to any incompatibilities, e.g., filler from coating components. The properties of fillers play a great role in the performance of coating films. Aluminum trihydrate (Al(OH)3) is a well-known filler in solvent-based coatings and other polymer industries. To study and evaluate the performances of Al(OH)3 in ultrafine powder coatings, a popular filler, barium sulfate (BaSO4) is used for comparison. Both fillers are added in ultrafine powder coatings based on two of the most commonly used resin systems (polyester-epoxy and polyester). The differences of physical and chemical properties between both fillers have significant influences on several properties of powder paints and coating films. The polar groups (hydrogen bond) in Al(OH)3 result in the strong interaction between inorganic filler and organic polymer matrix, thus decreasing the molecular network mobility and influencing the chain formation, which is verified by differential scanning calorimetric (DSC). The bed expansion ratio (BERs) of powder paints incorporated with Al(OH)3 are much higher than those with BaSO4, which indicate more uniform gas-solid contact during the spraying process. Samples with Al(OH)3 exhibit much lower specular gloss at 60°, which are expected to achieve remarkable matting effects. Superior corrosion resistances can be observed for almost all the coated panels incorporated with Al(OH)3 in contrast to those with BaSO4. Other aspects are slightly influenced by the difference between the two fillers, such as the angle of repose values (AORs) of powder paints, the impact resistance and flexibility of coating films.

Investigation of the Performance of Fumed Silica as Flow Additive in Polyester Powder Coatings

“…The angle of repose (AOR) is defined as the angle between the surface of the pile (formed by raining down the powder to a flat surface) and the flat surface [30][31][32]. A lower angle of repose indicates a better flowability.…”

Synergistic Effect of Nanoclay and Barium Sulfate Fillers on the Corrosion Resistance of Polyester Powder Coatings

“…In coating formulations, fillers or extenders are common additives alongside resin, curing agents, pigments, and other components [10,11]. Fillers contribute to reduced material costs and enhanced mechanical strength [3,[12][13][14]. While talc and barium sulfate are known fillers for coatings, their combined use with other additives, such as montmorillonite, has demonstrated enhanced anti-corrosive performance [3,[15][16][17][18].…”

A Comparative Study on the Anti-Corrosive Performance of Zinc Phosphate in Powder Coatings

“…The addition of fillers (also called extenders) into powder coating is common in the industry. The filler can lower the cost of the product and enhance the mechanical properties of the produced coating films [28,29]. These solid particles can also contribute to the barrier effect of the coating films by increasing their tortuosity [29,30].…”

“…The filler can lower the cost of the product and enhance the mechanical properties of the produced coating films [28,29]. These solid particles can also contribute to the barrier effect of the coating films by increasing their tortuosity [29,30]. However, the interactions amongst these components and their combined effects have not been extensively investigated.…”