Study On Phase Inversion Emulsification Of Epoxy Resin And Waterborne Epoxy Resin Anticorrosive Coatings

Epoxy resin with excellent adhesion to base and anticorrosive performance has been used widely in solvent base anticorrosive coatings, and it is also the most important raw material to prepare waterborne anticorrosive coatings in the current world, but now it is difficult to find epoxy resin emulsion product in our market. There are probably two main reasons: one is that we start this research lately and the other one is the technological limit to get a stable emulsion. Preparing waterborne epoxy resin is the critical technology for waterborne epoxy anticorrosive coatings, phase inversion methods(PIM) is an effective way to prepare waterborne system of high polymer. This study is to prepare epoxy resin emulsion by PIM, discuss its mechanism and develop waterborne anticorrosive coatings product.The relationship between the critical water content of phase inversion(Rf) of epoxy resin E-44 and experiment condition such as emulsification temperature, HLB value of emulsifier, emulsifier content, stirring force was researched by using compound emulsifier of Span60 and Tween20 ,and the phase inversion mechanism was also discussed. The result shows that Rf varies from 0.27 to 0.93 under different conditions, so the phase inversion process of epoxy resin E-44 is quite complex and doesn't accord with Ostwalt model. Phase inversion of epoxy resin is correlative with the absorption of emulsifier to the oil/water interface to form an interface film and the acting balance of emulsifier with water or oil. The favor factors for absorption of emulsifier and increasing its acting force with water will make phase inversion from W/O to O/W easily, while under unfavourable conditions, phase inversion may occur through increasing volume fraction of water, but the emulsion is very unstable.Emulsifier is the critical factor for preparing emulsion of epoxy resin. The experimental result shows that it is difficult to get stable epoxy resin emulsion using the compound of Span60 and Tween20 as emulsifier. According to the structure similarity principle of emulsification, special emulsifier for epoxy resin with the oleophylic group which is the same component as emulsified oil phase was synthesized by nucleophilic addition reaction between epoxy resin and PEG. The molecule structure of the emulsifier, especially the oleophylic group, has an important effect on emulsion properties, and the hydrophilic group is also influential. So it is necessary to choose the specific emulsifier for different epoxy resin.Phase inversion emulsification technology of epoxy resin was discussed and the parameters were optimized by orthogonal test with the synthesized emulsifier considering emulsion particle size and stability of emulsion as the index. Under the...