Patent ID: 7951883

Claim:
A multimodal, high density, homopolyethylene barrier resin having a density greater than or equal to 0.955 g/cm 3 , an melt index MI 2 less than or equal to 2.5 dg/min, and a melt flow ratio MFR less than or equal to 50; said barrier resin providing a film with a water vapor transmission rate less than 0.4 g-mil/100 in 2 /day, wherein the barrier resin is made by a process comprising (a) polymerizing ethylene in the presence of a Ziegler-Natta catalyst selected from the group consisting of titanium halides, titanium alkoxides, vanadium halides, and mixtures thereof, an organoaluminum cocatalyst, hydrogen, and an alkoxysilane modifier in a hydrogen to ethylene molar ratio in vapor space within the range of 1 to 6, to produce a homopolyethylene having a density greater than or equal to 0.96 g/cm 3 and a melt index MI 2 greater than or equal to 5 dg/min; (b) devolatilizing the reaction mixture to remove hydrogen; and (c) continuing the polymerization by adding ethylene and hydrogen to the devolatilized reaction mixture in a hydrogen to ethylene molar ratio in vapor space less than or equal to 0.8 to form the barrier resin.