Patent ID: 8557931

Claim:
A slurry process for preparing an ethylene polymer comprising: a first polymerization stage comprising the step of: polymerizing ethylene in the presence of a solid catalyst system and a molecular weight regulator wherein the molecular weight regulator is present in a first molecular weight regulator concentration; and, a second polymerization stage comprising the step of: polymerizing ethylene in the presence of the solid catalyst system and the molecular weight regulator wherein the molecular weight regulator is present in a second molecular weight regulator concentration, wherein the first polymerization stage and the second polymerization stage are carried out (a) at a temperature in the range of from 60 to 120° C., and (b) the solid catalyst system comprises the product obtained by contacting: (A) a solid catalyst component comprising Ti, Mg, halogen, and (B) an organoaluminum compound wherein the solid catalyst system has: (i) a porosity (P F ) of at least 0.3 cm 3 /g; and, (ii) a surface area lower than 100 m 2 /g as determined by BET method, and wherein the first molecular weight regulator concentration is different from the second molecular weight regulator concentration, and wherein the resulting ethylene polymer has a melt flow ratio F/P, according to ASTM 1238, of higher than 25.