Impact resistant LLDPE composition and films made thereof

Patent metadata

Field	Value
Publication number	US-8957158-B2
Application number	US-200913119697-A
Country	US
Kind code	B2
Filing date	Sep 22, 2009
Priority date	Sep 25, 2008
Publication date	Feb 17, 2015
Grant date	Feb 17, 2015

Abstract

A novel PE material is devised showing excellent mechanical/optical properties and process ability, e.g. for film extrusion. The polyethylene of the invention is produced in one single e.g. gas phase reactor.

First claim

The invention claimed is:

1. A polyethylene composition comprising:
i. 70% to 95% by weight based on the total weight of the polyethylene composition, of a first polymeric fraction comprising a copolymer of ethylene and 5 to 15% by weight of at least one C 3 -C 20 -α-olefin-comonomer wherein the copolymer has a molecular weight distribution from 2 to 4, a composition distribution breadth index greater than 60%, a density from 0.88 to 0.93 g/cm 3 , and a high load melt index from 20 to 60 g/10 min, and
ii. 5 to 30% by weight based on the total weight of the polyethylene composition, of a second polymeric fraction comprising an ethylene polymer wherein the ethylene polymer comprises less than 5% by weight of a C 3 -C 20 -α-olefin-comonomer, and has a molecular weight distribution from 10 to 20, a composition distribution breadth index greater than 80%, a density from 0.95 to 0.98 g/cm 3 , and a high load melt index from 1.0 to 10 g/10 min,
wherein the polyethylene composition has a multimodal molecular weight distribution, a density of from 0.90 to 0.935 g/cm 3 , a high load melt index from 20 to 50 g/10 min, and a Mw/Mn more than 3.0 to 5.0.

2. The polyethylene composition according to claim 1 , having a weight average molecular weight Mw of from 50,000 up to 500,000 g/mol and/or a Mz/Mw>1.5.

3. The polyethylene composition according to claim 2 wherein the α-olefine is selected from the group consisting or 1-alkene and non-conjugated 1-alkadiene.

4. The polyethylene composition according to claim 3 wherein the α-olefine is 1-alkene.

5. The polyethylene composition according to claim 1 , wherein the first polymeric fraction has a composition distribution breadth index greater than 70%.

6. The polyethylene composition according to claim 5 , wherein the first polymeric fraction has a composition distribution breadth index greater than 80%.

7. The polyethylene composition according to claim 1 , wherein the first polymeric fraction has a density of from 0.890 to 0.930 g/cm 3 .

8. The polyethylene composition according to claim 1 , wherein the second polymeric fraction has a composition distribution breadth index greater than 90%.

9. The polyethylene composition according to claim 1 , wherein the polyethylene composition has a dart drop impact value, as measured by ASTM D 17092005 Method A on 25 μm blown films, of at least 1200 g.

10. The polyethylene composition according to claim 9 , wherein the polyethylene composition has a dart drop impact value, as measured by ASTM D 109:2005 Method A on 25 μm blown films, of at least 1600 g.

11. The polyethylene composition according to claim 1 , wherein the first polymeric fraction is produced by a metallocene catalyst.

12. The polyethylene composition according to claim 1 obtained by a polymerization reaction carried out with a mixed catalyst system in a single reactor.

13. The polyethylene composition according to claim 12 , wherein the polyethylene composition is in the form of a powder having a mixing quality of less than 2.5, wherein the powder is chloride-free for enhancing thermal and/or storage stability of the polyethylene composition.

14. The polyethylene composition according to claim 12 wherein the mixed catalyst system is immobilized on a common support material comprising a granulated support material and wherein the at least two catalysts are mixed on a single grain of the support material.

15. The polyethylene composition according to claim 12 wherein the polymerization reaction is carried out with the mixed catalyst system comprising a first catalyst and a second catalyst wherein the first catalyst is a transition metal complex catalyst and the second catalyst is transition metal complex catalyst.

16. The polyethylene composition according to claim 15 , wherein the first catalyst is a metallocene catalyst.

17. The polyethylene composition according to claim 15 wherein the two transition metal complex catalysts are immobilized on a common support material.

18. The polyethylene composition according to claim 1 wherein the second polymeric fraction, as analyzed by Differential Scanning Calorimetry peaks at a crystalline melting temperature of from 120 to 124.5° C.

19. The polyethylene composition according to claim 1 wherein the first polymeric fraction, as analyzed by Differential Scanning Calorimetry, peaks at a crystalline melting temperature of from 101 to 107° C.

20. The polyethylene composition according to claim 1 , wherein the polyethylene composition has a branching of from 0.01 to 20 CH 3 /1000 carbon atoms based on the total methyl group contents.

21. A polymer blend comprising the polyethylene composition of claim 1 .

22. The blend according to claim 21 , wherein the blend comprises or from 20% to 99% by weight or a first polymer which is the polyethylene composition according to claim 1 and of from 1 to 80% by weight of a second polymer which is different from said first polymer, and wherein the percentages by weight are based on the total mass of the blend.

23. A process to produce the polyethylene composition according to claim 1 , the process comprising polymerizing ethylene and at least one C 3 -C 20 -α-olefin-comonomer with a catalytic system comprising at least two transition metal complex catalysts in a single reactor.

24. The process according to claim 23 , wherein the catalytic system does not comprise a Ziegler catalyst and/or wherein a first catalyst A) is a single site catalyst which provides for the first polymeric fraction which is the first polymeric component of said polyethylene composition.

25. The process according to claim 24 , the first catalyst is a metallocene catalyst.

26. The process according to claim 23 , wherein a second catalyst B) is a non-metallocene, transition metal complex catalyst and wherein said second catalyst provides for the second polymeric fraction of said polyethylene composition.

27. The process according to claim 26 , wherein the second catalyst B) is an iron complex catalyst component B1) having a tridentate ligand bearing at least two aryl radicals.

28. The process according to claim 27 , wherein each of said two aryl radicals bears a halogen and/or an alkyl substituent in the ortho-position.

29. A process for producing an article comprising the step of extrudating the polyethylene composition according to claim 1 which is free or substantially free from polymer processing additive, in the continued absence of such processing additive, wherein the article is a film, fiber or molding.

30. The process according to claim 29 , wherein the film or moulding is free or is substantially free from melt fracture or shark-skin roughnesses on its surface and/or is gel-free, indicative of the slabe mixing of the polymeric components of the polyethylene composition.

31. The process of claim 29 , wherein the polyethylene composition is extrudated at a processing velocity greater than or equal to 40 kg/h.

32. The process according to claim 29 wherein the article is a blown film or blow molding.

33. An article manufactured from the polyethylene composition of claim 1 , wherein the article is selected from the group consisting of a film, fiber and moulding.

34. The article of claim 33 , wherein the article is the film having a dart drop impact gre

Assignees

• Fantinel Fabiana
• Mannebach Gerd
• Mihan Shahram
• Meier Gerhardus
• Vittorias Iakovos
• Basell Polyolefine Gmbh

Inventors

• Fantinel Fabiana
• Mannebach Gerd
• Mihan Shahram
• Meier Gerhardus
• Vittorias Iakovos

Classifications

• C08L23/04 Primary

  Homopolymers or copolymers of ethene · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08F10/02

  Ethene · CPC title

• C08J2323/08

  Copolymers of ethene (C08J2323/16 takes precedence) · CPC title

• C08L2314/02

  Ziegler natta catalyst · CPC title