Preparation And Investigation Of Water-borne Epoxy Resin

The commonly used epoxy resin usually has high viscosity and onlydissolves in organic solvents. Organic solvents not only cause harm to theenvironment and human health, but also have higher prices. So developingwater-borne epoxy resin becomes a hotspot of the research. The technology toprepare water-borne epoxy resin is to introduce hydrophilic groups on themain chain of epoxy resin molecular, which favors for stable dispersion inwater. A novel epoxy self-emulsifying agent was prepared through chemicalmodification in this work. The process and recipe has been studied, and thenthe self-emulsifying properties of the emulsifier were preliminarily testedthrough inversion method.First, maleic anhydride and epoxy resin E828reacted to open the epoxygroup and prepared modified epoxy resin with carbon-carbon double bond inmain chain under certain temperature and proper catalyst existed.Hydrobromic acid-acetic acid and KOH-ethanol methods were employed tomonitor the change of epoxy value and acid value of the reaction system,respectively; the product structure was examined by the infrared spectracharacterization. The reaction temperature, amount of catalyst, concentration of reactants and the proportion of mixed solvent were optimized during thepreparation of modified epoxy resin. The optimum reaction temperature was80°C; the amount of catalyst was1.5wt%; reactant concentrations were1mol L^-1of epoxy resin and0.5mol L^-1of maleic anhydride, respectively;ratio of toluene and acetone mixed solvents was9:1, with total volume of50mL.Then, the product of maleic anhydride modified epoxy resin reacted withsodium hydrogen sulfite to prepare self-emulsifier under certain temperatureand proper catalyst. During the experiment, the structure of self-emulsifierwas determined by NMR spectra, GPC and elemental analysis. Also particlesize analysis and stability analysis were employed to characterize theproperties of self-emulsifier water dispersion system, including sizedistribution, placement stability and centrifugal stability. The smallest particlesize of self-emulsifier water dispersion system prepared under optimalconditions is about100nm. The system can be placed more than three monthswithout precipitation and stratification, which also can be centrifuged as thespeed of5000r/min without stratification.Finally, phase reversion method was employed to complete the emulsionreaction between self-emulsifier and epoxy resin, the prepared water epoxyresin emulsion has good stability.