Effect of Corona and Flame Treatments on Extrusion Coating Performance Properties, 1993 Polymers, Laminations & Coatings Conference Proceedings

Michael W. Potts, M. Holly Hansen, Beth T. Kuettel, J. D. Goins

Various levels of corona and flame treatments were applied to aluminum foil surfaces and then extrusion coated with LDPE. The changes in extrusion coating performance (adhesion, hot tack, and heat seal) as a function of treatment type and level were monitored. Overall, the adhesive strength between the LDPE and aluminum foil interface improved with treatments, flame and corona. Hot tack and heat seal performance were not significantly impacted as a result of surface treating the aluminum foil surfaces.

The role of acid-base interactions in LDPE/aluminum foil adhesion has been previously explored. Higher adhesive strengths can be obtained between these two materials by maximizing the basic sites on one surface and acid sites on the other.

A relatively simple technique has been developed using contact angle of acid and basic solutions on the foil surface to predict the acid-base character of the substrate. For the work presented here, flame and corona surface treatment increased the basic characteristics of the foils. This increase in surface basicity correlated to increased adhesion.

This method of measuring the relative surface acidity and basicity of foil surfaces can also be used to predict package performance for LDPE/aluminum foil structures.