EXAMINATION OF THE DISTRIBUTION OF TPO ADHESION PROMOTER MATERIAL IN A PAINTED TPO SYSTEM

The adhesion of organic coatings to polyolefin substrates is strongly dependent upon the type of surface treatment the thermoplastic materia l receives prior to painting, One such treatment involves the applicat ion of a thin layer (7-14 micron) of an adhesion promoting primer that is comprised of a chlorinated polyolefin polymer, Although materials of this type are known to establish good adhesion between the thermopl astics olefin (TPO) and subsequent paint layers, the mechanism of adhe sion promotion is not unequivocally known. Current hypotheses suggest that adhesion is established through the diffusion and subsequent mole cular entanglement of the chlorinated polyolefin material into the ''t op-surface'' of the TPO. In this paper, we will report on both fluores cent microscopy and image time-of-flight secondary ion mass spectromet ry (TOF-SIMS) studies that examine the diffusion of adhesion promoter materials into the TPO substrate. The two complementary experimental t echniques have been used to relate effects of adhesion promoter molecu lar weight distribution on their diffusion into the TPO substrates and the subsequent ect of this diffusion on the adhesion robustness of th e painted system.