Preparation Of Epoxy-amine Adduct Self-emulsifying Curing Agent By One-pot Method

Epoxy-amine adduct self-emulsifying curing agent is widely applied in waterborne epoxy resin, acting as emulsifier and curing agent. The common method to synthesize epoxy-amine adduct self-emulsifying curing agent is as follows:primary amine-terminated epoxy-amine adduct was obtained by epoxy reacted with excess polyethylene polyamine; after removing organic solvent and polyethylene polyamine by vacuum distillation, reactive diluent was added to cap primary amine hydrogen; lastly, the product was salted by acetic acid and diluted to a suitable viscosity. In the above process, the organic solvent was overused, which leads to the increasing of the production cost and the environmental pollution. The strong side reaction, the crisis to gel, and the difficulty in completely removing polyethylene polyamine in the first step can affect the product’s properties greatly. In order to solve these problems, this paper empoly one-pot method for preparation of self-emulsifying curing agent. The reaction conditions are optimized and the properties of the product are systematically studied in this paper.The process of one-pot sysnthesis is as follows. Firstly, TETA-501with only one primary amine group is obtained by adding butyl glycidyl ether into triethylene tetraminea(TETA) in equal mole ratio. Secondly, TETA-501-EP is obtained by adding epoxy resin into TETA-501in a mole ratio of1:2. At last, acetic acid is used to neutralize TETA-501-EP and diluted the product to a suitable viscosity. The results indicate that:the optimal conversion rate of TETA-501is89.3%under reacting at70℃for4.0hours, the optional conversion rate of TETA-501-EP is92.1%, under reacting at80℃for4.0hours, epoxy-amine adduct self-emulsifying curing agent has the optimal emulsifying and curing performance at the neutralization value of20%; and the optimal solid content is50%.Compared with the common method, a large amount of raw materials can be saved in the one-pot method, with organic solvent(PM)37.2%, TETA26.4%,, epoxy resin19.0%, respectively. The product prepared by one-pot method shows a critical micelle concentration (CMC) is1.664g/L, D(3,2)=2.198μm and U=0.4953, while CMC of the product prepared by common way of3.033g/L, D(3,2)=2.962μm and U=1.105, which means that the emulsifying capacity of the product prepared by one-pot method is better than common method. When using the self-emulsifying curing agent synthetized by one-pot method and common method to cure epoxy resin, the pencil hardness, the compression strength and the adhesive force of the two different cured epoxy resins are similarly.The research results of this paper can be used to guide the further research and industrial production of epoxy-amine addut self-emulsifying curing agent.