Patent ID: 8222356

Claim:
A process for preparing ethylene copolymers having a molar mass distribution width M w /M n of from 5 to 30, a density of from 0.92 to 0.955 g/cm 3 , a weight average molar mass M w of from 50,000 g/mol to 500,000 g/mol and has from 0.01 to 20 branches/1000 carbon atoms, a z-average molecular weight M z of less than 1 million g/mol, wherein 5-50% by weight of the polyethylene having the lowest molar masses has a degree of branching of less than 12 branches/1000 carbon atoms and 5-50% by weight of the polyethylene having the highest molar masses has a degree of branching of more than 1 branch/1000 carbon atoms, the process comprising polymerizing ethylene in the presence of 1-alkenes with 3 to 12 carbon atoms in the presence of a catalyst composition comprising at least two different polymerization catalysts, wherein A) is at least one polymerization catalyst based on a hafnocene (A), and B) is at least one polymerization catalyst based on an iron component having a tridentate ligand bearing at least two aryl radicals with each bearing a halogen or tertiary alkyl substituent in the ortho-position (B).