Study On Kinetics Of Film Growth And Technical Parameters Of Cathodic Electro-Deposition Coatings Based On Epoxy Resin

The electrophoretic coatings (EC) have been widely used for the surface treatment of metals as its features of high efficiency of coating utilization, easy operation and automation to paint, less pollution to environment, uniform thickness of coating film, strong ability of against corrosion, an object with any shape can be painted and so on. Epoxy resin electrophoretic paint is always used for priming and antiseptic paint as its strong adhesion and outstanding performance in corrosion resistence. In this paper, the technical parameters and coating growth kinetics of epoxy resin cathodic electrophoretic paint coated with the surface of architectural aluminium have been investgated.The kinetic equation of epoxy resin film growth has been obtained based on the orthogonal experiment method. The computational results derived from the equation were fairly matched with the experimental datum. The optimum technical parameters, solid content is 17%~19%, voltage is 75 V~80 V, pH value is 6.2~6.4, temperature is at 28℃~32℃and time is 120 s～150 s, have also been determined. The effects of pH value, solid content, temperature, voltage and time on the appearance and performance of epoxy resin film have been studied respectively.In the initial time of electrodeposition process, film growth velocity increases and the current density decrease rapidly. With the deposition time exceeding 150 s, the film thickness and current density keep being constant. The technical parameters of epoxy resin electrophoresis dying and electrophoresis colour have been obtained.The mechanical properties of epoxy resin film have been tested by pencil test, cross-hatch tape test and mandrel bend test. The results show that the hardness is 3H, adhesion is the first level, flexibility is excellent. The corrosion resistence of epoxy resin film immersed in 3.5% NaCl solution has been testedby electrochemical impedence spectroscopy. The corrosion resistence is good with the high valve of impedence. In the epoxy resin electrophoresis colour, the corrosion resistence of pigment dying film is better than that of coloring agent film.