Blow molding Polyethylene Resins

A continuous gas-phase polymerization process for making a high strength, high density polyethylene copolymer, comprising:

• contacting monomers that include ethylene and optionally at least one non-ethylene olefin with fluidized catalyst particles in a gas-phase fluidized-bed reactor in the presence of hydrogen gas at an ethylene partial pressure of 100 psi or more, to produce a polyethylene copolymer having a density of from 0.945 to 0.960 g/cc and an ESCR Index of 1.2 or more, wherein:
• (a) the catalyst particles include a silica support that is porous and has a surface area of less than 400 square meters per gram;
• (b) the catalyst particles have been prepared by contacting the silica support with a combination consisting of a chromium compound and a titanium compound in a vessel;
• raising the internal temperature of the vessel containing the dried particles and dry air to a final activation temperature of 650° C. or below;
• to form activated catalyst particles;
• lowering the internal temperature of the vessel containing the activated catalyst particles;
• removing air from the vessel using dry nitrogen;
• and
• (c) the polyethylene resin is formed with a bulk density of 20 lb/ft3 or more;
• (d) the polyethylene resin has an ESCR Index of 1.2 or more;
• (e) the polyethylene resin has a density of from 0.945 to 0.960 g/cc;
• (f) the polyethylene resin has a Molecular Weight Distribution of from 15 to 30, wherein the catalyst does not include an aluminum alkyl modifier.