LLDPE Blown Film Resins with Low Inherent Blocking Force, 1993 Polymers, Laminations & Coatings Conference Proceedings

Seema V. Karande, Lonnie G. Hazlitt, Merrick J. Castille

The inherent film blocking force in linear low density polyethylene (LLDPE) blown films was studied using several LLDPE resins with varying density, molecular weight and molecular weight distribution. Melt elasticity, fabrication conditions and film surface morphology were found to have significant effect on inherent film blocking force in LLDPE blown films. A comprehensive mechanism for film blocking force based on the molecular weight, rheology and the morphology studies is proposed and will be discussed in this paper. It is generally known that LLDPE resins with higher density exhibit lower blocking force. However, it was also observed that at a constant density, the LLDPE resins with higher melt elasticities (slower relaxation rates) exhibited rougher film surface morphology and produced blown films with lower blocking force. These LLDPE resins with inherent low blocking force are used in grocery sack, trash bags and merchandise bag markets where bag openability is a critical performance property.