A solution polymerization process using a phosphinimine catalyst and a boron activator is conducted at a temperature of about 170° C. or greater in the presence of trialkyl aluminum to produce polyethylene having a comparatively broad molecular weight distribution. The polyethylene product produced by the process of this invention is desirable because it can provide enhanced “processability” in comparison to polyethylene having a narrow molecular weight distribution. The process of this invention is advantageous in comparison to prior art processes for the preparation of “broad” polyethylene which use two polymerization reactors and/or more than one polymerization catalyst. The polymers produced by the process of this invention are potentially suitable for the preparation of plastic film. For example, a polyethylene according to this invention and having a density of about 0.93 grams per cubic centimeter and a melt index I
(according to ASTM D 1238) of about 2 may be advantageously used to prepare cast film. In addition the present polyethylenes may be used for the manufacture of a wide variety of other goods including blow molded parts (such as tanks, drums and containers for gasoline or other liquids); extruded goods (such as profiles or hoses); and injection molded goods such as food containers.