Recovery of Electrodeposition Paints
Electrodeposition of paint has proved to be an important breakthrough in the industrial painting of metallic surfaces, particularly for automobiles and for large household appliances. Electrodeposition has a number of distinct advantages compared to alternative paint-coating processes. Electrocoating provides an extraordinarily uniform defect-free coating of the metal surface, even on sharp edges and in recessed areas, due to the self-limiting character of the electrodeposition process. Membrane fouling is a critical issue in the design of an ultrafiltration (UF) system for electropaint recovery. The chapter considers the design of a hollow fiber system for recovery of a cathodic electropaint used for primer-coating automobile bodies. The initial rinses are performed using the diluted paint solution, while the last major rinse uses the UF permeate. In order to avoid upsetting the physicochemical properties of the paint dispersion, the ultrafiltration module must be operated with a very low permeate yield.