Adhesion failure of paints on thermoplastic polyolefin substrates

摘要

This paper examines the adhesion of automotive paint to polypropylene composites that have been subjected to flame treatment. Painted samples exposed to hydrothermal stress showed a locus of paint adhesion failure between the substrate and oxidised interphase. It is shown here that paint adhesion can be improved by the addition of polyethylenimine (PEI) or PEI/glutaraldehyde (glut) adhesion promoting graft chemicals after the surface of the polymer has been oxidised by flame treatment. Paint failure for this surface treatment regime was induced using more severe hydrothermal exposure conditions, but it was shown that the locus of failure was the same as for flame treated substrates. These results suggest that the improvement in adhesion is due to the graft chemicals improving the stability of the oxidised interphase by a crosslinking mechanism.