Study On The Preparation Of Cathodic Electrodeposition Coating

The cathodic electrodeposition coating is a kind of novel green paint, which hassuperiority that traditional solvent-based and other types of coatings do not have.However, the cathodic electrodeposition coating are still greatly in need ofimprovement since they have been emerged. This paper mainly focuses on reductionof the temperature of cathodic electrodeposition coating. Using different curing agents,we achieve two different single-component curing agents, which synthesized twocathodic electrodeposition coatings, and this paper also explores the synthesis process,electrophoretic coating process, as well as the electrophoretic coating performance indetail.We synthesized two different single-component curing agents with caprolactam,trimethylol propane (TMP), methyl ethyl ketone oxime (MEKO) and polyether asblocking agent, closing the isocyanate radical of toluene diisocyanate. The synthesisprocess was determined by studying two single-component curing agents. Theoptimum conditions of caprolactam closing TDI(toluene diisocynate) are: n (active H)/n(-NCO) of1.2, reaction temperature of70℃, reaction time for120min and that oftrimethylolpropane closing caprolactam-TDI are: reaction temperature of80°C andreaction time of140min. The best reaction conditions of MEKO closing TDI are: n(active H)/n(-NCO) of1.2, reaction temperature of80℃, reaction time of120min,and that of polyether closing MEKO-TDI are: reaction temperature is90℃andreaction time is140min. FT-IR spectra show that MDI base of two single-component curing agent had been basically closed completely.The single-component curing agent of experimental preparation added to theorganic amine-modified epoxy resin, synthetic grinding resins for cathodicelectrodeposition coating, and get the cathodic electrodeposition coating after thegrinding process. The TG test and determination of the paint coating emulsion particlesize and zeta potential. Prepared to caprolactam as a blocking agent of cathodicelectrophoretic paint emulsion particle size of200nm, the zeta potential was+39.2mv;methyl ethyl ketone oxime as the particle size of the cathodic electrodeposition coatingemulsion sealer prepared240nm, the zeta potential was+40.5mv. This shows that thetwo cathodic electrodeposition coating emulsion with good dispersion.TG curve shows that the initial deblocking temperature of the cathodicelectrodeposition coating prepared with caprolactam as blocking agent is160°C, andthe fastest weight loss is at366.4°C, the residual amount of the coating was53.24%at891.5°C. And the initial deblocking temperature of the cathodic electrodepositioncoating prepared with MEKO as blocking agent is140°C, the fastest weight loss is at241.1°C, the residual amount of the coating was40.80℅. The above results showthat the two cathodic electrodeposition coating have good heat resistance and thermalstability, and deblocking temperature of the second cathodic electrodeposition coatingwas lower than the first one.The optimum conditions were determined by coating workpiece samples withexperimental cathodic electrodeposition, and they are as follows: temperature of30°C,bath solid content of20%, voltage is30V and electrophoresis time for4min.