Environmentally Friendly Plating Pretreatment for ABS Plastic Using Electrolyzed Sulfuric Acid

Abstract

High adhesion strength between Acrylonitrile Butadiene Styrene (ABS) plastic and plated metal has been conventionally obtained by chromic acid etching in manufacturing industry. However, in recent years, hexavalent chromium becomes the target as an environmental regulatory substances. Thus, the establishment of a chromium-free pretreatment method is expected. Electrolyzed sulfuric acid (ESA) is a unique oxidizer alternative to the chromic acid. Therefore, we have been trying to apply ESA to treat the surface of ABS plastic. Depending on the sulfuric acid concentration in ESA solution, modification effects such as changing the surface morphology and introducing the functional groups were different. The ESA in which the concentration of sulfuric acid is 75 wt% and 80 wt% can change ABS resin surface in quality to be hydrophilic from hydrophobic. Also, adhesion strength between plating metal film and the plastic was obtained maximum 1.2 kN/m. Mechanism of high adhesion was anchor effect with cohesion failure. Therefore, this environmentally friendly surface modification method is expected in industrial use.