Polyethylene for rotomoulding

Patent metadata

Field	Value
Publication number	US-9273168-B2
Application number	US-201013390919-A
Country	US
Kind code	B2
Filing date	Aug 20, 2010
Priority date	Aug 21, 2009
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

A novel polyethylene is devised which polyethylene is particularly advantageous for manufacturing rotomoulded articles.

First claim

The invention claimed is:

1. A polyethylene homo- and/or copolymer, wherein the copolymer is a copolymer of ethylene with C 3 -C 20 -alkene, the polyethylene having a composition distribution breadth index from 20 to 50%, a molar mass distribution width Mw/Mn from 7 to 15, a density from 0.938 to 0.942 g/cm 3 , a weight average molar mass Mw from 20,000 g/mol to 500,000 g/mol, a melt index from 4 to 5.5 g/10 min, measured at 190° C. with a load of 2.16 kg, and a high load melt index between 125 and 230 g/10 min, measured at 190° C. with a load of 21.6 kg.

2. The polyethylene according to claim 1 , wherein the polyethylene comprises homopolymeric and copolymeric subfractions, and wherein said polyethylene taken as a whole has from 0.7 to 20 CH 3 /1000 carbon atoms as determined by NMR.

3. The polyethylene according to claim 1 , wherein said polyethylene comprises at least one C 3 -C 20 -alkene monomer species in an amount of >3% based on the total weight of said polyethylene.

4. The polyethylene according to claim 3 , wherein the C 3 -C 20 -alkene is a C 3 -C 20 -1-alkene.

5. The polyethylene according to 4 wherein the C 3 -C 20 -alkene is a C 3 -C 12 -1-alkene.

6. The polyethylene according to claim 1 , wherein the polyethylene has a vinyl group content of at least 0.6 vinyl groups/1000 C atoms.

7. The polyethylene of claim 6 having a vinyl group content of at least 0.9 vinyl groups/1000 C atoms.

8. The polyethylene of claim 7 wherein the amount of the polyethylene with a molar mass below 1 million g/mol, as determined by GPC, is above 95.5%.

9. The polyethylene according to claim 1 , wherein the η(vis) value is 0.3 to 7 dl/g.

10. The polyethylene according to claim 1 , wherein the polyethylene has been prepared in one polymerization step in a single reactor by a mixed catalyst system comprising at least one metallocene.

11. The polyethylene according to claim 1 , wherein the polyethylene is obtained by polymerization in the presence of a catalyst composition comprising at least two different single-site polymerization catalysts.

12. The polyethylene according to claim 11 , wherein the polyethylene is obtained by copolymerizing ethylene with at least one 1-alkene of formula R 1 CH═CH 2 , wherein R 1 is hydrogen or an alkyl radical with 1 to 10 carbons, at a temperature from 20 to 200° C. and at a pressure from 0.05 to 1 MPa.

13. The polyethylene according to claim 11 wherein the at least two different single-site polymerization catalysts, comprise a single-site catalyst A) based on a hafnocene and a single-site catalyst B) based on an iron component having a tridentate ligand bearing at least two aryl radicals.

14. The polyethylene of claim 13 wherein each of the aryl radicals bear a halogen or tert-alkyl substituent in the ortho-position.

15. The polyethylene according to claim 1 , further comprising non-polymeric additives selected from lubricants, antioxidant, stabilizers, or mixtures thereof.

16. The polyethylene according to claim 1 , being devoid of densification aids.

17. The polyethylene according to claim 16 being devoid of polymeric densification aids.

18. The polyethylene of claim 1 wherein the melt flow rate is from 4 to 5 g/10 min.

19. A rotomoulded article or object, comprising a polyethylene homo- and/or copolymer, wherein the copolymer is a copolymer of ethylene with C 3 -C 20 -alkene, the polyethylene having a composition distribution breadth index from 20 to 50%, a molar mass distribution width Mw/Mn from 7 to 15, a density from 0.938 to 0.942 g/cm 3 , a weight average molar mass Mw from 20,000 g/mol to 500,000 g/mol, a melt index from 4 to 5.5 g/10 min, measured at 190° C. with a load of 2.16 kg, and a high load melt index between 125 and 230 g/10 min, measured at 190° C. with a load of 21.6 kg.

20. The rotomoulded article according to claim 19 , comprising no densification additive.

21. The rotomoulded article according to claim 20 , comprising no polymeric densification additive, and being free from bubbles.

22. The rotomoulded article according to claim 19 , which is a tank of at least 100 L volume, container of at least 100 L volume, or drum of at least 100 L volume.

23. The rotomoulded article according to claim 19 , which comprises said polyethylene or a mixture of said polyethylenes as the only polymeric constituent.

Assignees

• Mannebach Gerd
• Vogt Heinz
• Fantinel Fabiana
• Mihan Shahram
• Bisson Peter
• Besems Cees
• Meier Gerhardus
• Schüller Ulf
• Gall Barbara
• Vittorias Iakovos
• Hecker Manfred
• Olmscheid Michael
• Basell Polyolefine Gmbh

Inventors

• Mannebach Gerd
• Vogt Heinz
• Fantinel Fabiana
• Mihan Shahram
• Bisson Peter
• Besems Cees
• Meier Gerhardus
• Schüller Ulf
• Gall Barbara
• Vittorias Iakovos
• Hecker Manfred
• Olmscheid Michael

Classifications

• C08F4/65912

  in combination with an organoaluminium compound · CPC title

• B29K2023/0641

  MDPE, i.e. medium density polyethylene · CPC title

• B29K2995/0088

  Molecular weight · CPC title

• B29K2105/0094

  having particular viscosity · CPC title

• C08F210/16 Primary

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title