Synthesis Of Waterborne Epoxy Acrylate Miniemulsions And Its Application In Coatings

Epoxy acrylate（EP/PA）composite emulsion combines the advantages of epoxy resin and acrylic resin,and has a good application prospect.However,the content of the epoxy resin in the composite emulsion prepared by the conventional emulsion polymerization is low.It can not satisfy the water-based paint’s request of the adhesiveness,water resistance and salt spray resistance.Therefore,to meet the requirements of the field of water-based industrial anti-corrosion coatings,an EP/PA composite latex with high EP content was prepared via miniemulsion polymerization.The effect factors of droplet stability of the miniemulsion were investigated.It shows that high-epoxy low molecular weight E-51 was selected as the research object,and the ultrasonic time was determined to be 15 minutes and the ultrasonic power was 500 W.The effect factors of the miniemulsion polymerization process of the EP/PA were fully studied.The results show that when the reaction time was 5 h,the reaction temperature was 60 °C,KPS and Na HSO₃ redox initiator amount was 0.5%,and the ratio of emulsifier PS-630 and SDBS was 2:1,the monomer conversion was the highest and the composite emulsion system was stable.FT-IR results show that the epoxy resin and acrylate were successfully compounded together.TEM results show that the composite latex particles had a regular spherical structure with an average particle size of 130-199 nm.With the increase of the epoxy resin content,the particle size distribution became wider and secondary nucleation might occur.The prepared EP/PA composite latex was used as the matrix resin to study the film formation properties of the composite coating.The cross-linking reaction between epoxy and amine groups during curing was confirmed by FT-IR.The DSC and TGA curves show that the thermal stability of the composite coating increases as the amount of epoxy resin increases.The influence of different epoxy resin and phosphate ester emulsifier content on the corrosion resistance of the composite coating was investigated by Tafel polarization test and neutral salt spray resistance test.The influence of different epoxy resin content and phosphate ester emulsifier content on the corrosion resistance of the composite coating was investigated by Tafel polarization test and neutral salt spray resistance test.The results show that the cross-linking reaction between the epoxy group and the amine group during the curing process makes the barrier performance of the coating significantly improved.In addition,the phosphate ester emulsifier can not only emulsify the monomer,but also the phosphate group can form a dense phosphate protective film with the substrate metal,thereby inhibiting further corrosion of the metal.When the epoxy content is 30%,the corrosion rate of the coating is 1.253 μm/year.The EP/PA composite latex was applied to a water-based metal anti-corrosion coating.The adhesion of the film was measured to be 1,the impact resistance was 50 Kg·cm,the water resistance was 240 hours,and the salt spray resistance was 480 hours.Therefore,the prepared composite emulsion has a broad application prospect in the field of metal anti-corrosion coating materials.