Study On The Preparation Of Room Temperature Curing Waterborne Epoxy Coating Used For Spaying

In this thesis, a kind of emulsifier which can make epoxy resin self emulsifying was synthesized. The preparation process was obtained by real-time monitoring the change of epoxy value. The emulsifier structure was characterized by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Then the emulsifier was added into the epoxy resin in certain proportion, and methyl diphenylmethane diisocyanate (MDI) monomer was introduced for grafting reaction. Finally the waterborne epoxy resin emulsion which had uniform particle size distribution and good stability was preparation after dispersed in water and processed high pressure homogenizer treatment. The results from latex particle size analysis show that the average particle size of emulsion is about 596.7nm and very equal.Second, diethylene triamine (DETA) was terminated, and was modified by adding epoxy emulsifier and epoxy resin. The uniform, stable and 60% solid-content epoxy-modified polyamine curing agent emulsion was obtained, and the average particle size of emulsion is about 413.7nm. The curing agent emulsion was characterized by FTIR and GPC. The influences on the properties of the emulsion of different end-capping agent, polyethylene glycol (PEG) molecular weight, and the kind and amount of co-solvent were investigated.Finally, the varnish coating based on the system of waterborne epoxy emulsion–curing agent emulsion (coating film A) and the system of waterborne epoxy emulsion–soluble curing agent (coating film B) was prepared on the substrate by means of spraying at the room temperature, and then carried out FTIR analysis of its structure. Their thermal properties were analyzed and compared by differential scanning type calorimeter (DSC) and thermal gravimetric (TG); scanning electron microscopy (SEM) was used to observe the surface morphology of the films. The results indicated that the system of waterborne epoxy emulsion–curing agent emulsion has fast curing rate at room temperature curing, can be sprayed better, and greater crosslink density of the coating film leading to better physical performances.