Construction of functional epoxy resin coatings based on acid-doping polyaniline coated APP: Preparation, characterization and properties

Waterborne epoxy resin (WER) coatings have attracted more and more attention because of their excellent physical and chemical properties, however, WER's flammability and high insulation limit its application. In this paper, polyaniline (PANI) doped with four different acids (sulfuric acid, phosphoric acid, citric acid and amino trimethylene phosphonic acid) was used as the shell material to coat ammonium polyphosphate (APP), and a series of multifunctional WER fillers (PANI acids /APP) integrating flame retardant, smoke suppression and antistatic properties were prepared. Then, the PANI acids /APP was compounded with WER to prepare a functional WER coating. The structures and morphologies of the PANI acids /APP fillers were characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), the results showed that acids doping could promote the formation of polyaniline coating on the surface of APP , and the PANI acids /APP filler doped by amino trimethylene phosphonic acid (ATMP) exhibits the best coating effect. Furthermore, the effects of PANI acids /APP fillers on the flame retardant property, smoke suppression property, electrical property and adhesion property of waterborne epoxy resins were explored. The results indicated that the carbon residue of WER coatings with PANI acids /APP fillers at 800 °C could reach 24.1 %-29.6 %, among which ATMP doping group has a residual carbon of 27.3 %. Also, the WER coating containing PANI ATMP /APP filler possesses the best comprehensive performance, the coating has a limiting oxygen index of 31.7 % and passed V-0 level in the vertical burning test (UL-94). Compared with pure EP coating, the peak heat release rate of the PANI ATMP /APP modified coating decreased by 78.1 % and the total heat release decreased by 37.8 %. Additionally, the surface resistance and adhesive force of the PANI ATMP /APP modified coating reached 3.14×10 6 Ω and 11.8 MPa, respectively, which could meet the usage needs of anti-static application of the WER coatings.