Improvement of Adhesion on Automotive Top Coats by Corona Discharge

Abstract

A highly automated Corona Discharge treatment transforms a nonpolar, not bondattractive top coat surface into a polar, adhesively suitable substrate for structural bonding, i.e. for automotive windscreen fastening (Fig. 1). This cost-effective, secure purely physical procedure replaces the expensive, manual, wet pretreatment in applying solvent containing inflammable primers.Investigations have shown an excellent adhesion of particularly polyurethane adhesives to Corona-Discharge-treated current automotive topcoats, independent of the type and amount of many top-coat additives. Adhesion experiments and the determination of surface energy have shown an insensitive resulting performance towards changing process parameters.Scientific examinations with IR and ESCA analysis as well as electron microscopy provide valuable explanations for the efficiency of the Corona Discharge treatment.