Process for the preparation of a multimodal polyethylene

A process for the preparation of a multimodal polyethylene polymer comprising:

• (I) contacting a solid support with a solution of a cocatalyst comprising a compound of a group 13 element and a racemic metallocene complex of formula (Ix)
• wherein
• each X is a sigma donor ligand;
• each Het is independently a monocyclic or multicyclic heteroaromatic or heterocyclic group containing at least one heteroatom selected from O, N or S;
• L is a carbon, silicon or germanium based divalent bridge in which one or two backbone atoms link the ligands;
• M is Ti, Zr or Hf;
• each R1 is the same or different and is a linear C1-10 alkyl group, or linear C1-10 alkoxy,
• each n is 0 to 3;
• each R2 is the same or different and is a C1-10 alkyl group, C1-10 alkoxy group or —Si(R)3 group;
• each R is C1-10 alkyl or phenyl group optionally substituted by 1 to 3 C1-6 alkyl groups;
• and
• each p is 0 to 3;
• so as to form a supported catalyst;
• (II) polymerising ethylene and optionally at least one C4-10 alpha olefin comonomer in a first stage in the presence of said supported catalyst so as to form a first polyethylene component;
• (III) polymerising ethylene and optionally at least one C4-10 alpha olefin comonomer in a second stage in the presence of the product of step (I) so as to form a second polyethylene component.

A process for the preparation of a multimodal polyethylene polymer comprising:

• (I) contacting a solid support with a solution of a cocatalyst comprising a compound of a group 13 element;
• so as to form a cocatalyst impregnated support;
• (II) contacting said cocatalyst impregnated support with a racemic metallocene complex of formula (Ix)
• wherein
• each X is a sigma donor ligand;
• each Het is independently a monocyclic or multicyclic heteroaromatic or heterocyclic group containing at least one heteroatom selected from O, N or S;
• L is a carbon, silicon or germanium based divalent bridge in which one or two backbone atoms link the ligands;
• M is Ti, Zr or Hf;
• each R1 is the same or different and is a linear C1-10 alkyl group, or linear C1-10 alkoxy,
• each n is 0 to 3;
• each R2 is the same or different and is a C1-10 alkyl group, C1-10 alkoxy group or —Si(R)3 group;
• each R is the same or different and is C1-10 alkyl or phenyl group optionally substituted by 1 to 3 C1-6 alkyl groups;
• and
• each p is 0 to 3;
• so as to form a supported catalyst;
• (III) polymerising ethylene and optionally at least one C4-10 alpha olefin comonomer in a first stage in the presence of said supported catalyst so as to form a first polyethylene component;
• (IV) polymerising ethylene and optionally at least one C4-10 alpha olefin comonomer in a second stage in the presence of the product of step (I) so as to form a second polyethylene component.