Unipol II LLDPE Polyethylene Blown Film Resin for Extrusion on HP-LDPE Equipment, 1997 Polymers, Laminations & Coatings Conference Proceedings

A large segment of the polyethylene blown film extrusion market has continued to use LDPE produced by the high pressure process for extruding liner grade films on equipment incapable of extruding LLDPE counterparts satisfactorily. A new class of linear polyethylene resins with a much broader molecular weight distribution has been developed using the UNIPOL TM II process which allow the use of present day HP-LDPE extrusion equipment to make films with superior strength and stiffness, like standard narrow molecular weight LLDPE counterparts. This provides significant opportunities for downgauging or equivalent gauge strength improvements. The basic molecular changes made to accomplish this new balance of extrudability and strength are explained. The viscoelastic and solid state properties are compared with present day liner grade HP-LDPE resins. The improved film toughness properties are contrasted with 100% HP-LDPE films as well as with blends of HP-LDPE with LLDPE. Finally, the performance of films extruded from these new resins in conversion operations is also described.