Improved performance of aluminum pigments encapsulated in hybrid inorganic–organic films

Abstract

An organic silane acrylate resin (PMBK) was synthesized by free-radical solution polymerization using methyl methacrylate, butyl acrylate and (3-methacryloxypropyl)trimethoxysilane as monomers. Aluminum (Al) particles were then encapsulated in inorganic–organic hybrid films that were prepared by hydrolysis and condensation of PMBK and tetraethyl orthosilicate (TEOS) on the surface of Al pigments. Characterization results showed that PMBK and TEOS could simultaneously hydrolyze and condense with hydroxyl groups on the surface of the Al particles to form composite Al particles coated with inorganic–organic hybrid films. Compared with raw Al particles, the corrosion resistance and adhesive properties of paint films containing the composite Al particles were improved greatly, while the glossiness of the paint films decreased slightly, from 48.6° to 47.0°. In alkaline media (pH 11), the volume of evolved H2 of composite Al particles was only 3.5mL, whereas that of raw Al was 83.5mL. The glossiness of paint films containing composite Al particles decreased by 1.66% after immersion in alkaline media for 24h, whereas that of raw Al decreased by 14.82%. Peel-off tests of the paint films showed that the composite particles moved slightly away from the paint films. In contrast, the raw Al particles were seriously desquamated, suggesting encapsulation of hybrid films can greatly improve the adhesive properties of Al particles in paint films.