Control of composition in ethylene copolymerizations using magnesium chloride supported Ziegler–Natta catalysts

Incorporation of a sterically hindered phenol (2,6‐di‐tert‐butyl‐4‐methylphenol) during the preparation of MgCl2‐supported titanium catalysts coupled with the use of an aluminum alkyl activator modified with the same phenol and an electron donor such as ethyl benzoate allows the systematic modification of the reactivity ratios of ethylene and 1‐olefin copolymerizations. The polymers obtained tend to be largely random with a tendency toward alternating at high comonomer incorporation. Very low density LLDPE copolymers have been prepared in stable slurry polymerizations. The same catalysts allow the preparation of copolymers with dienes.