HOW DO CHLORINATED POLY(OLEFINS) PROMOTE ADHESION OF COATINGS TO POLY(PROPYLENE)

The mechanism by which chlorinated poly(olefin) (CPO) primer coatings promote adhesion of paints to poly(propylene) and thermoplastic poly(o lefins) (TPO) has been examined by surface characterization techniques including electron spectroscopy for chemical analysis (ESCA), time-of -flight secondary ion mass spectrometry (ToFSIMS) and transmission ele ctron microscopy (TEM). The coatings, their interfacial failures, and taper-cut cross sections were studied, using both waterborne and solve ntborne CPO primers. The results were then correlated with peel streng th and crosshatch adhesion tests. CPO primers do not penetrate deeply into the poly(olefin) substrates, but are quite mobile following appli cation of the topcoat. Solventborne CPO's generally showed adhesive fa ilure at the CPO/poly(olefin) interface when dried at ambient temperat ures. Test results are also reported for waterborne CPO adhesion promo ters.