Patent ID: 7048882

Claim:
A process for coating a substrate, comprising producing a bimodal polyethylene composition by subjecting ethylene, optionally with hydrogen and/or comonomers to polymerization or copolymerization reactions in a multistage polymerization sequence of successive polymerization stages; carrying out the polymerization reactions in the presence of a single site catalyst capable of forming a composition comprising a low molecular weight component with an MFR 2 of 20 g/10 min or more and a density higher than the density of the composition, and a high molecular weight component, said composition having a melt flow rate MFR 2 of 10–20g/10 min and a density of 915–960 kg/m 3 ; and extruding said composition on the substrate as such or by adding 10 wt % or less, calculated from the total weight of the coating, of high pressure PE-LD by blending into the extrusion composition or by co-extrusion wherein the active complex of said single site catalyst has the general formula (X 1 )(X 2 )Hf(Cp-R 1 )(Cp-R 2 ), where X 1 and X 2 are thee same or different and selected from the group comprising halogen, methyl, benzyl, and hydrogen; Hf is hafnium; Cp is cyclopentadienyl group; and R 1 and R 2 are same or different and stand for linear and branched hydrocarbyl groups containing 1–10 carbon atoms.