Process for the preparation of multimodal high density polyethylene

Patent metadata

Field	Value
Publication number	US-12012504-B2
Application number	US-201917056855-A
Country	US
Kind code	B2
Filing date	May 30, 2019
Priority date	May 30, 2018
Publication date	Jun 18, 2024
Grant date	Jun 18, 2024

Abstract

The invention provides a process for the preparation of a multimodal high density polyethylene (HDPE) having a melt flow rate (MFR2) of 0.1 to 4.0 g/10 min, said process comprising: (i) polymerising ethylene in a first polymerisation stage in the presence of a Ziegler-Natta catalyst to prepare a first ethylene homopolymer having a MFR2 from 10 to 500 g/10 min; (ii) polymerising ethylene in a second polymerisation stage in the presence of said catalyst and said first ethylene homopolymer to prepare an ethylene homopolymer mixture comprising said first ethylene homopolymer and a second ethylene homopolymer, said mixture having a MFR2 from 50 to 1000 g/10 min; and (iii) polymerising ethylene and at least one alpha-olefin comonomer in a third polymerisation stage in the presence of said catalyst and said ethylene homopolymer mixture to prepare said multimodal HDPE.

First claim

The invention claimed is:

1. A process for the preparation of a multimodal high density polyethylene (HDPE) having a melt flow rate (MFR 2 ) of 0.1 to 4.0 g/10 min and a MFR 5 of 2.5 to 12 g/10 min, wherein the multimodal HDPE has a FNCT (6 MPa, 50° C.) of at least 30 hours, said process comprising:
(i) polymerising ethylene in a first polymerisation stage in the presence of a Ziegler-Natta catalyst to prepare a first ethylene homopolymer having a MFR 2 from 10 to 500 g/10 min;
(ii) polymerising ethylene in a second polymerisation stage in the presence of said catalyst and said first ethylene homopolymer to prepare an ethylene homopolymer mixture comprising said first ethylene homopolymer and a second ethylene homopolymer, said mixture having a MFR 2 from 50 to 1000 g/10 min; and
(iii) polymerising ethylene and at least one alpha-olefin comonomer in a third polymerisation stage in the presence of said catalyst and said ethylene homopolymer mixture to prepare said multimodal HDPE.

2. The process as claimed in claim 1 , wherein said first polymerisation stage and/or said second polymerisation stage are carried out in a slurry loop reactor.

3. The process as claimed in claim 1 , wherein said third polymerisation stage is carried out in a gas phase reactor.

4. The process as claimed in claim 1 , wherein said at least one alpha-olefin has 3 to 12 carbon atoms.

5. The process as claimed in claim 4 , wherein said at least one alpha-olefin is selected from the group consisting of 1-butene, 1-hexene and 1-octene.

6. The process as claimed in claim 4 , wherein said at least one alpha-olefin is 1-butene.

7. The process as claimed in claim 1 , wherein the multimodal HDPE has a density of 950 to 960 kg/m 3 .

8. The process as claimed in claim 1 , wherein the multimodal HDPE has a MFR 2 of 0.5 to 1.5 g/10 min.

9. The process as claimed in claim 1 , wherein the multimodal HDPE has a tensile modulus of at least 850 MPa, more preferably at least 900 MPa.

10. A multimodal high density polyethylene (HDPE) having a melt flow rate (MFR 2 ) of 0.1 to 4.0 g/10 min obtained by a process as defined in claim 1 .

11. A multimodal high density polyethylene (HDPE) having a density of 940 to 970 kg/m 3 and a melt flow rate (MFR 2 ) of 0.1 to 4.0 g/10 min, a MFR 5 of 2.5 to 12 g/10 min, wherein said multimodal HDPE comprises a low molecular weight ethylene homopolymer component and a high molecular weight ethylene copolymer component and wherein said multimodal HDPE has a Mz/Mn of at least 95 and/or Mz of at least 680000;
wherein said low molecular weight ethylene homopolymer component is an ethylene homopolymer mixture comprising a first ethylene homopolymer and a second ethylene homopolymer; and
wherein the multimodal HDPE has a FNCT (6 MPa, 50° C.) of at least 30 hours.

12. An injection or compression molded article, comprising the multimodal HDPE as defined in claim 11 .

13. The injection or compression molded article of claim 12 , wherein the injection or compression molded article is a cap or a closure.

14. A cap or closure comprising the multimodal HDPE as defined in claim 11 .

15. A process for the manufacture of an injection or compression molded moulded article, said process comprising preparing the multimodal HDPE as defined in claim 11 ;
optionally pelletizing the multimodal HDPE to form pellets; and
injection or compression moulding the formed pellets or HDPE to form said article.

16. A process for a manufacture an injection or compression molded cap or closure comprising:
injection or compression molding of the multimodal HDPE of claim 11 .

Assignees

• Borealis Ag

Inventors

• Tran Anh Tuan
• Albunia Alexandra Romina
• Cheng Joy Jie
• Thorman Joseph
• Jamieson John
• Tupe Ravindra

Classifications

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F210/16

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

• C08F2500/17

  Viscosity · CPC title

• C08L2314/02

  Ziegler natta catalyst · CPC title

• C08L2207/062

  HDPE · CPC title