Borealis Technology Oy

Eija Lappi

Kalle Kallio

Hilkka R Knuuttila

Ole Jan Myhre

Harri Hokkanen

Merete Skar

Janne Maaranen

Arja Lehtinen

Marina Surakka

Esa Kinnunen

A process for the polymerisation of ethylene and optionally at least one Calpha olefin comonomer in the slurry or solution phase in a reactor having a polymer outlet stream, a procatalyst or catalyst feed stream and a hydrogen feed stream, said polymerisation being effected in the presence of a metallocene catalyst, a diluent and hydrogen, wherein said diluent is recycled from said outlet stream to said hydrogen feed stream, said procatalyst or catalyst feed stream is free of hydrogen, said hydrogen feed stream is free of procatalyst or catalyst and said procatalyst or catalyst feed stream does not comprise recycled diluent.

Polymerization process

This invention concerns process for producing polyethylene compositions, films prepared thereof and process for the preparation of the films. The process comprises subjecting ethylene, optionally hydrogen and comonomers to polymerization or copolymerization reactions in a multistage polymerization. At least one polymerization stage is conducted essentially in the absence of hydrogen. The polymerization reactions are carried out in the presence of a single-site catalyst capable of forming a composition comprising a low molecular weight component with MFR of at least 10 g/10 min and a density higher than the density of the composition and a high molecular weight component. The melt flow rate of the composition is in the range MFR &equals;0.1-5.0 g/10 min and the density of the composition is 915-960 kg/m . The invention makes it possible to produce polyethylene compositions for manufacturing films with a good balance between optical and mechanical properties.

Polymer composition, a process for the production thereof and films prepared thereof

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Porvoo, Finland

Eija Lappi