| Epoxy resin has good corrosion resistance and mechanical properties and has a wide range of applications in the field of coatings.At present,volatile organic compounds(VOCs)contained in solvent-based epoxy coatings commonly found in the market will cause great harm to human health and the environment,therefore,reducing VOCs emissions is the main task of the coating industry.Waterborne epoxy coating does not contain VOCs,and has the advantages of green environmental protection,nontoxic and harmless,however,its water resistance is slightly worse than that of solventbased epoxy coating,therefore,improving the water resistance of waterborne epoxy coating is one of the research hotspots in the field of coatings.In this study,epoxy resin,polyethylene glycol as raw materials,potassium persulfate as catalyst to synthesize emulsifier,and then it and OP-10 complex,through the reverse transformation method to get water-based epoxy resin emulsion,and prepare the film.The effects of raw material type and mole ratio on the properties of synthetic emulsifier,emulsifying process conditions on the properties of emulsion,and the effects of the amount of curing agent and compound emulsifier on the properties of coating film were investigated.The results show that under the catalysis of 0.3 wt.%potassium persulfate,the emulsifier synthesized by the molar ratio of E51 and PEG4000 is 1:1.Under the conditions of emulsification temperature of 60 ℃,rotation speed of dispersion homogenizer 5000 r/min,pre-dispersion for 10 min,deionized water drop acceleration of 160 m L/min,addition amount of EP-PEG4000 and OP-107% and 3%,respectively,the waterborne epoxy emulsion with small particle size(445.0 nm)and high solid content was prepared.Good stability.The properties of the coating prepared with 20% hardener can reach the industrial standard of solvent-based epoxy primer.In order to develop a modified water-based epoxy coating that basically meets the needs and has lower cost,the epoxy ester was prepared by esterification reaction of unsaturated fatty acid and epoxy resin,and the water-based epoxy ester emulsion was prepared by reverse transformation method,and the coating film was prepared.The effects of esterification reaction conditions on the acid value of the reaction system,emulsification process conditions on the properties of the emulsion,and the effects of raw material type and mole ratio,drying agent,emulsifier S amount on the properties of the film were investigated.The results showed that under the catalysis of 1 wt.%tetrabutylammonium bromide,the molar ratio of E20 to unsaturated fatty acid was 1:2,and the esterification reaction temperature was 140 ℃,the viscosity of epoxy ester was moderate,which was favorable for emulsification.Under the conditions of emulsification temperature 65 ℃,dispersing homogenizer speed 7000 r/min and emulsifier S content 8%,the waterborne epoxy ester emulsion with small particle size(386.1 nm),high solid content and good stability was prepared.The properties of the coatings prepared by adding 0.02% cobalt iso-octoate and 0.04% cerium iso-octoate exceed the industrial standard of solvent-based epoxy ester primer.Compared with the water-based epoxy film prepared in this study,the film has poor water resistance and hardness,but shorter drying time,better adhesion,flexibility and thermal stability,which can basically meet the performance requirements. |
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