Polymer composition
View Patent ↗The invention relates to novel multimodal polyethylene polymers comprising a low molecular weight fraction and a high molecular weight fraction, and having a MFR 5 of greater than 0.10 g/10 min and less than or equal to 0.22 g/10 min, and a density of greater than equal to 952 kg/m 3 . The invention also relates to uses of the novel polymers in the production of polymeric articles, especially pipes.
1. A multimodal polyethylene polymer comprising a low molecular weight ethylene homo-polymer fraction and a high molecular weight ethylene copolymer fraction, wherein:
the low molecular weight fraction is present in an amount of 47 to 52% by weight;
the high molecular weight fraction is present in an amount of 48 to 53% by weight;
the multimodal polymer has a MFR 5 of greater than 0.10 g/10 min; and less than or equal to 0.22 g/10 min; and
the multimodal polymer has a density of greater than or equal to 952 kg/m 3 .
2. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a density of greater than or equal to 953 kg/m 3 .
3. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a dynamic viscosity, at a shear stress of 2.7 kPa, of at least 300,000 Pa·s.
4. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a shear thinning index of 70 or greater.
5. A multimodal polyethylene polymer according to claim 1 wherein the co-monomer of the high molecular weight ethylene copolymer is a C 6 to C 12 alpha-olefin.
6. A multimodal polyethylene polymer according to claim 5 wherein the co-monomer is a C 8 to C 10 alpha-olefin.
7. A multimodal polyethylene polymer according to claim 1 , wherein the ethylene homo-polymer has a MFR 2 of about 300 to 2000 g/10 min.
8. In the method of forming a pipe or conduit from a polymeric material, the improvement comprising forming said pipe or conduit from the polymer composition of claim 1 .
9. Pipe or conduit formed from the composition of claim 1 .
10. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a density of greater than or equal to 953 kg/m 3 .
11. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a dynamic viscosity, at a shear stress of 2.7 kPa, of at least 300,000 Pa·s.
12. A multimodal polyethylene polymer according to claim 2 wherein the polymer has a dynamic viscosity, at a shear stress of 2.7 kPa, of at least 300,000 Pa·s.
13. A multimodal polyethylene polymer according to claim 1 wherein the polymer has a shear thinning index of 70 or greater.
14. A multimodal polyethylene polymer according to claim 2 wherein the polymer has a shear thinning index of 70 or greater.
15. A multimodal polyethylene polymer according to claim 3 wherein the polymer has a shear thinning index of 70 or greater.
16. A multimodal polyethylene polymer according to claim 1 wherein said shear thinning index is 100 or greater.
17. A multimodal polyethylene polymer according to claim 1 wherein the co-monomer of the high molecular weight ethylene copolymer is a C 6 to C 12 alpha-olefin.
18. A multimodal polyethylene polymer according to claim 2 wherein the co-monomer of the high molecular weight ethylene copolymer is a C 6 to C 12 alpha-olefin.
19. A multimodal polyethylene polymer according to claim 3 wherein the co-monomer of the high molecular weight ethylene copolymer is a C 6 to C 12 alpha-olefin.
20. A multimodal polyethylene polymer comprising a low molecular weight ethylene homo-polymer fraction and a high molecular weight ethylene copolymer fraction, wherein:
(a) the low molecular weight fraction is present in an amount of 47 to 52% by weight, and has a weight average molecular weight of from about 5,000 to about 50,000 g/mol;
(b) the high molecular weight fraction is present in an amount of 48 to 53% by weight, and has a weight average molecular weight of from about 300,000 to 900,000 g/mol;
(c) the multimodal polymer has a MFR 5 of greater than 0.10 g/10 min and less than or equal to 0.22 g/10 min; and
(d) the multimodal polymer has a density of greater than or equal to 952 kg/m 3 .