Improving Aluminum Adhesion and Heat Seal Performance of LDPE and LLDPE Extrusion Coating Resins, 1990 Polymers, Laminations & Coatings Conference Proceedings

Increasing demands are being placed on resin suppliers and converters to produce cost-effective flexible packaging structures while maintaining the required performance properties. Aluminum foil remains one of the premier cost effective barrier materials in flexible packaging structures. This study was conducted with the goal of improving aluminum adhesion and heat seal performance in flexible packaging structures which are required to perform at higher levels. Two types of extrusion coating grade polymers were studied: low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

Extrusion coating fabrication parameters including air gap, back pressure, and extruder output were studied to understand their effect on seal strength and aluminum adhesion. Polymer physical and intrinsic properties, such as melt index, chloroform extractables, and rheology were also investigated to determine their effects on the results.

Recommendations are made for extrusion coating conditions based on the overall design of the resin.