METAL WORKING, STEEL, PLATING, AND AUTOMOTIVE
Today, electrophoretic coating has been accepted worldwide as the state-of-the-art technology for priming metal products, such as car bodies, automobile parts, appliances or office furniture. The electrocoating process involves the electrophoretic deposition of charged paint particles in a water-based dispersion onto a conductive (metal) substrate. The process is favored universally because of its extremely uniform, consistent, and defect-free coating results, even on targets with sharp edges and recessed areas. After deposition, excess dragout paint from the dip paint tank must be rinsed off. The diluted paint cannot be returned directly to the tank due to the surplus of water. The water work-up is done by an ultrafiltration unit incorporated into a closed-loop, multi-stage (counter current) rinse system. Thus, a UF unit significantly affects the operating costs of a electrodeposition paint system by reducing the deionized water use (for rinsing purposes) and thus lowering paint costs. Moreover, under optimized running conditions, the process generates no waste water at all, i.e., runs in a complete cycle. With ever-increasing waste water treatment cost, the electrocoating/ultrafiltration process has become even more attractive for all metal finishing applications.
Celanese claims that permanently hydrophilic NADIR® membranes, incorporated into flow-optimized and service-friendly SPIRA-CELL® spirally wound modules are ideally suited for electrocoat paint filtration. High flux and long lifetimes make SPIRA-CEL® modules a most economical solution for electrocoat paint ultrafiltration needs. Due to their high hydrophilicity paired with an uncharged membrane surface, NADIR® membranes are equally superior in the filtration of cathodic (e.g., car bodies) as well as anodic (e.g., appliances) electrocoat paint.