Preparation And Research Of Tow-component Self-emulsifying Epoxy Cathodic Electrodeposition Coating

Cathodic electrodeposition coatings was a new water-based paint,derived from1970s.Because of its Numerous advantages such as excellent anti-corrosion propertity，high levels of coating utilization, automation，CED has aroused extensive attentionand developed rapidly. In the1980s，CED has formed two types：one-componentCED coatings and two-component CED coatings. Due to the high viscosity andcomplex using process of one-component CED coatings, two-component CEDcoatings had occupied a dominant position finally.so far one-component CEDcoatings has been no longer in use,the two type CED coatings tend to be similar.Although our country’s manufacturing technology of CED coatings had madegreat progress by encouring independent research and introducing advanced foreigntechnology since1980s,but the key technology of CED coatings was not in our hand.Until now the manufacturing technology of CED coatings in our country only reachedthe1980’s level of developed countries. In addition, our country’s automobile industrydeveloped rapidly in recent years. The market demand of CED coatings was furtherexpanded, but most of this market was monopolized by developed countries.Consideration above present status, a two-component self-emulsifying epoxycathodic electrodeposition coating was prepared in this dissertation,and thepreparation and coating process were investigated in details.By Chain extension reaction of DDP，BPA with E-51and ring-opening reactionof DEA,DMAPA with epoxy resin，a self-emulsifying cationic epoxy was obtained.The reaction conditions of Chain extension reaction and ring-opening reaction werestudied. The influence of DDP：DEA：DMAPA, BPA contents, neutralization degree,co-solvent contents were also discussed. The measuring methods such as FTIR, GPC,TG, DSC, Laser particle&Zeta potential analyzer have been used.The cathodic electrophoretic emulsion was prepared by using a self-emulsifyingcationic epoxy resin and totally blocked MDI. The influence of totally blocked MDI/self-emulsifying cationic epoxy resin to Gel content of electrodeposition films was discussed. The cathodic electrophoretic emulsion could get better stability and higerfilm crosslinking level when the ratio of totally blocked MDI to self-emulsifyingcationic epoxy resin was0.7.The two-component self-emulsifying epoxy cathodic electrodeposition coatingwas prepared by mixing color paste, cathodic electrophoretic emulsion and deionizedwater. The electrophoretic coating process was systemically studied also. A nice CEDfilm which had a smooth and bright appearance,was gained when electrophoresisvoltage was120～140V, electrophoresis temperature was30℃, electrophoresis timewas90～120s, curing temperatures was180℃, curing time was30min.