Double-layered surface decoration of flaky aluminum pigments with zinc aluminum phosphate and phytic acid–aluminum complexes for high-performance waterborne coatings

Abstract

This paper reported the double-layered surface decoration for aluminum flakes by coating a zinc aluminum phosphate passive film, followed by fabricating a phytic acid–aluminum complex sealing film. The chemical compositions and structures of surface-decorated aluminum flakes were characterized by Fourier-transform infrared, X–ray photoelectron, and energy-dispersive X–ray spectroscopy and their morphology and double-layered structure were confirmed by scanning and transmission electron microscopy. The surface-decorated aluminum flakes not only show excellent dispersibility in water due to the enhanced hydrophilicity, but also exhibit good corrosion resistance and chemical stability against water. Most of all, the double-layered surface decoration leads to an improvement in optical performance of coating surface such as glossiness, flop index and distinctness of image compared to the single-layered one when the surface-decorated aluminum flakes are applied for waterborne coatings. The surface-decorated aluminum flakes developed by this work can well serve as a good flaky aluminum pigment for high-performance waterborne coatings.