Multimodal polyethylene polymers and methods of making and using the same

1. A multimodal polyethylene polymer having an MFR 2 of 0.1 to 2 g/10 min, a density of 940 kg/m 3 or more, a tensile modulus of 900 MPa or more and wherein

M z /M w ≦0.29( M w /M n )+0.8.

2. A multimodal polyethylene polymer as claimed in claim 1 wherein

M

w

2

M

n

⁢

M

z

≥

2.8

.

3. A multimodal polyethylene polymer as claimed in claim 1 having a density of 950 to 960 kg/m 3 .

4. A multimodal polyethylene polymer as claimed in claim 1 having tensile modulus 910 MPa or more.

5. A multimodal polyethylene polymer as claimed in claim 1 wherein Mz is in the range of 400 kD to 700 kD.

6. A multimodal polyethylene polymer as claimed in claim 1 having FNCT more than 50 h.

7. A multimodal polyethylene polymer as claimed in claim 1 having 0.1 to 1 mol % comonomer.

8. A multimodal polyethylene polymer as claimed in claim 1 wherein said polymer is a copolymer with the comonomer 1-butene.

9. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight component and a higher molecular weight copolymer component wherein said lower molecular weight component is a homopolymer or a copolymer with a comonomer content of less than 0.2 mol %.

10. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight component and a higher molecular weight copolymer component wherein said lower molecular weight component is a homopolymer or a copolymer with a comonomer content of less than 0.1 mol %.

11. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight component and a higher molecular weight copolymer component wherein said lower molecular weight component is a homopolymer or a copolymer with a comonomer content of less than 0.05 mol %.

12. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight (LMW) homopolymer component and a higher molecular weight (HMW) ethylene copolymer component.

13. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight (LMW) homopolymer component and a higher molecular weight (HMW) ethylene copolymer component, wherein said HMW copolymer component comprises at least one C3-12 alpha olefin.

14. A multimodal polyethylene polymer as claimed in claim 1 having a lower molecular weight (LMW) homopolymer component and a higher molecular weight (HMW) ethylene copolymer component, wherein said HMW copolymer component comprises but-1-ene, hex-1-ene or oct-1-ene.

15. A multimodal polyethylene polymer as claimed in claim 1 having 48 to 55 wt % of a HMW component (B) and 52 to 45 wt % LMW component (A).

16. An injection or compression moulded article comprising a polymer as claimed in claim 1 .

17. An injection or compression moulded article of claim 16 , wherein the article is a cap or closure.

18. A process for the preparation of a polyethylene as claimed in claim 1 comprising;

polymerising ethylene and optionally at least one C3-10 alpha olefin comonomer so as to form a lower molecular weight component (A); and subsequently

polymerising ethylene and optionally at least one C3-10 alpha olefin comonomer in the presence of component (A) so as to form a higher molecular weight component (B).

19. A multimodal polyethylene copolymer derived from the comonomer 1-butene, wherein the copolymer has MFR 2 of 0.05 to 10.0 g/10 min, a density of 940 kg/m 3 or more, a tensile modulus of 900 MPa or more and wherein

M z /M w ≦0.29( M w /M n )+0.8.

20. A multimodal polyethylene polymer having MFR 2 of 0.05 to 10.0 g/10 min, an Mz in the range of 400 kD to 700 kD, a density of 940 kg/m 3 or more, a tensile modulus of 900 MPa or more and wherein

M z /M w ≦0.29( M w /M n )+0.8.

21. A multimodal polyethylene polymer as claimed in claim 20 wherein Mz is in the range of 450 kD to 600 kD.

22. An injection or compression moulded article comprising a cap having a high tip of less than 0.5 mm or having no high tip at all, wherein the cap comprises a multimodal polyethylene polymer having an MFR 2 of 0.05 to 10.0 g/10 min, a density of 940 kg/m 3 or more, a tensile modulus of 900 MPa or more and wherein

M z /M w ≦0.29( M w /M n )+0.8.