WATER-REDUCIBLE ADHESION PROMOTERS FOR COATINGS ON POLYPROPYLENE-BASED SUBSTRATES

The application of coatings onto polypropylene-based substrates is dif ficult because of poor adhesion to most coating systems. Several techn iques are used to overcome this problem, including the use Of chlorina ted polyolefins as adhesion promoters. Chlorinated polyolefin primers are typically applied at low solids in an organic solvent. The develop ment of water-reducible adhesion promoters based on emulsions and disp ersions of chlorinated polyolefins is described. Formulation parameter s such as particle size, storage stability, and solvent content are al so discussed. Data is presented on adhesion-promoting properties of va rious coatings on polypropylene-based substrates before and after expo sure to humidity. Electron spectroscopy for chemical analysis (ESCA) i s used to determine mode of adhesion failure.