Studies On Complex Cathodic Electrodeposition Coating And Its Self-stratification Character

Electrophoretic finishing was a new type of technology, derived from 1960s. Because of its unique properties, electrophoretic finishing was applied widely, such as large project of car body, little of badge or glasses frame. Electrodeposition coating had high technological content, which study and produce were regarded most difficult coating, especially its requirements of use and management were stricter than that of traditional coatings. At present, products of electrodeposition coatings manufactured independently in our country were few and the manufacture of the products mostly depended on foreign techniques or joint ventures. Therefor, the research and development of electrodeposition coating are great significance.Consideration above present status and trends of cathodic electrodeposition coating, in this dissertation, synthesis of complex cathodic electrodeposition coating (CED) with self-stratification characterization was present, and theories involved process of synthesis, finishing and curing were investigated in details.The research results showed that during curing process, complex CED which consists of cationic epoxy and acrylic resins with different surface tension could self-stratify to form a coating film, namely: the upper layer was rich in acrylic resin, and the lower layer was mainly comprised of epoxy resin. The coating film possesses excellent properties in weather and corrosion resistance, which reached the aim of the bottom and top combined electrophoretic finishing. Moreover, because resins concentration profile presented gradient distribution in coating film, adhesion failure that occurred in several coated finishing was avoidedDynamic mechanic torsion braid analysis (TBA) was used to investigate coating film curing process and IR was used to determine the composition of resins in different film thickness. The results showed that disparity of surface tension, molecular weight, concentration of resin and curing condition coming into being a great effect on self-stratification morphology of coating film.