Preparation and failure behavior of fluorine-containing acrylic polyurethane coating

摘要

A kind of fluorine-containing acrylic copolymer was synthesized via a two steps of fluorine modification route. A hydrophobic fluorine-containing acrylic polyurethane coating was prepared with the synthesized fluorine-containing acrylic copolymer and trimer of hexamethylene diisocyanate curing agent. The fluorine-containing acrylic polyurethane coating was employed as the topcoat, while a kind of epoxy coating was used as the primer. The failure behavior of the acrylic polyurethane and epoxy composite coatings in 3.5 wt.% NaCl aqueous solution and 5 wt.% salt spray environments were studied. Chemical structure of the copolymer was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (F-19 NMR). Glass-transition temperature (Tg) of the copolymer was determined with differential scanning calorimetry (DSC). The surface and cross-section morphologies of the coatings before and after failure test were explored via digital microscopy and field emission scanning electron microscopy (FESEM). The electrochemical impedance spectroscopy (EIS) was employed to analyze the coating corrosion resistance during the failure process. X-ray photoelectron spectroscopy (XPS) was used to provide insights into the chemical compositions of the coating surface. The results showed that the fluorine-containing copolymer and the corresponding coating were prepared as expected. The fluorine-containing acrylic polyurethane and epoxy composite coatings failed much faster in the salt spray environment than that in the NaCl aqueous solution. The different environment resulted in different surface chemical compositions. (C) 2015 Elsevier B.V. All rights reserved.