Bimodal polyethylene for injection stretch blow moulding applications

Patent metadata

Field	Value
Publication number	US-10016923-B2
Application number	US-201715442893-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Nov 10, 2009
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

A polyethylene resin having a multimodal molecular weight distribution comprising at least two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a Ziegler-Natta catalyst system, the polyethylene resin having a density of from 0.950 to 0.965 g/cm 3 and a melt index MI2 of from 0.5 to 5 g/10 min.

First claim

The invention claimed is:

1. An injection stretch blow moulded container prepared with a polyethylene resin having a multimodal molecular weight distribution comprising at least two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a Ziegler-Natta catalyst system, the polyethylene resin having a density of from 0.950 to 0.965 g/cm 3 , measured following the method of standard test ASTM 1505 at a temperature of 23° C., a melt index MI2 of from 0.5 to 5 g/10 min, measured following the method of standard test ASTM D 1238 at a temperature of 190° C. and under a load of 2.16 kg, and molecular weight distribution Mw/Mn of from 5 to 20.

2. The injection stretch blow molded container according to claim 1 wherein the Ziegler-Natta catalyst system comprises a Ziegler-Natta catalyst component D and a preactivating agent, wherein the Ziegler Natta catalyst component D is obtained by
a) generating a reaction product A by contacting a magnesium dialkoxide compound with a halogenating agent;
b) contacting reaction product A with a first halogenating/titanating agent to form reaction product B;
c) contacting reaction product B with a second halogenating/titanating agent to form reaction product C; and
d) contacting reaction product C with a third halogenating/titanating agent to form catalyst component D.

3. The injection stretch blow molded container according to claim 2 wherein the preactivating agent of the Ziegler-Natta catalyst system is an organoaluminium compound.

4. The injection stretch blow molded container according to claim 1 wherein at least one of the reactors is a slurry loop reactor.

5. The injection stretch blow molded container according to claim 4 wherein the two reactors are slurry loop reactors.

6. The injection stretch blow molded container according to claim 1 wherein fraction B is produced in a first reactor of the two reactors and fraction A is produced in a second reactor of the two reactors.

7. The injection stretch blow molded container according to claim 1 wherein the polyethylene resin has an environmental stress crack resistance of at least 100 h.

8. The injection stretch blow moulded container according to claim 1 wherein the injection stretch blow moulded container weighs from 10 to 150 g per dm 3 of volume.

9. The injection stretch blow moulded container according to claim 1 wherein:
the injection stretch blow moulded container weighs from 10 to 150 g per dm 3 of volume, when the injection stretch blow moulded container has a volume of less than 300 cm 3 , or
the injection stretch blow moulded container weighs from 10 to 80 g per dm of volume, when the injection stretch blow moulded container has a volume of at least 300 cm 3 .

10. The injection stretch blow molded container according to claim 1 , wherein the Ziegler-Natta catalyst system comprises a titanium compound having at least one titanium- halogen bond.

11. The injection stretch blow molded container according to claim 1 , wherein the polyethylene resin has a bimodal molecular weight distribution.

12. The injection stretch blow molded container according to claim 1 , wherein the fraction B has a density of at least 0.908 g/cm 3 and at most 0.945 g/cm 3 , measured following the method of standard test ASTM 1505 at a temperature of 23° C.

13. The injection stretch blow molded container according to claim 1 , wherein the fraction B has a high load melt index HL275 of at least 1.5 dg/min and at most 14 dg/min.

14. The injection stretch blow molded container according to claim 1 , wherein the fraction A has a density of at least 0.953 g/cm 3 and at most 0.978 g/cm 3 , measured following the method of standard test ASTM 1505 at a temperature of 23° C.

15. The injection stretch blow molded container according to claim 1 , wherein the polyethylene resin comprises from 36 to 50 wt % of the fraction B and from 50 to 64 wt % of the fraction A.

Assignees

• Boissiere Jean Marie
• Vantomme Aurelien
• Belloir Pierre
• Van Sinoy Alain
• Total Res & Technology Feluy

Inventors

• Boissiere Jean-Marie
• Vantomme Aurélien
• Belloir Pierre
• Van Sinoy Alain

Classifications

• C08F210/16

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

• C08F2500/13

  Environmental stress cracking resistance · CPC title

• B65D1/0207

  characterised by material, e.g. composition, physical features · CPC title

• C08F2500/05

  Bimodal or multimodal molecular weight distribution · CPC title

• B65D2501/0036

  Hollow circonferential ribs · CPC title