Preparation and properties of phosphorus-containing waterborne epoxy compound

Epoxy resins were inherently brittle and flammable. 9, 10-Dihydro-9-oxa-10-phosphaphenanthren-10-oxide(DOPO) is efficient flame retardant. While the prospect of using it in the waterborne epoxy coatings is limited because it is insoluble in water and incompatible with epoxy resins. Accordingly, a novel phosphorus-containing waterborne epoxy compound was prepared as follows. Firstly, with the initial mole ratio between the epoxy group of phenolic epoxy resin (F-51) and DOPO of 3:2, F-51 reacted with DOPO in butyl glycol ether using triphenylphosphine as catalyst to synthesis F-51-DOPO addut. Secondly, with the mole ratio between the epoxy group of F-51-DOPO addut and monoethanolamine(MEA) of 1:1, F-51-DOPO addut reacted dropwise with MEA in propylene glycol methyl ether (PM) under the conditions of reaction temperature(70℃), reaction time(8 h) to synthesize F-51-DOPO-MEA adduct. Finally, in order to incorporate the hydrophilic and soft polyglycol segment, F-51-DOPO-MEA adduct reacted dropwise with diglycidyl ether of polyglycol (PEGGE) in PM under the condition of mole ratio between F-51-DOPO-MEA and the epoxy group of PEGGE (1:2), reaction temperature(65℃), reaction time(5 h) to synthesize F-51-DOPO-MEA-PEGGE adduct. The synthesized DOPO-based epoxy compound is soluble in water and compatible with epoxy resins when used in the waterborne epoxy resin coatings. The effects of the content of the synthesized adduct on the film property were discussed. The results indicate that it can improve mechanical performance of the films, heat resistance and char yield within 450~800℃ remarkably. And the incorporation of it into waterborne epoxy resin materials could improve the limiting oxygen index (LOI) and flame retardancy of cured materials obviously. © 2016, Editorial Board of Polymer Materials Science & Engineering. All right reserved.