Multi-stage process for producing a C2 to C8 olefin polymer composition

Patent metadata

Field	Value
Publication number	US-11897975-B2
Application number	US-201917273325-A
Country	US
Kind code	B2
Filing date	Sep 19, 2019
Priority date	Sep 28, 2018
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

The present invention relates to a multi-stage process for producing a C 2 to C 8 olefin polymer composition in a process comprising at least two reactors, wherein a pre-polymerized solid Ziegler-Natta catalyst is prepared by carrying out an off-line pre-polymerization of a solid Ziegler-Natta catalyst component with a C 2 to C 4 olefin monomer before feeding to the polymerization process.

First claim

The invention claimed is:

1. A continuous multi-stage process for producing a C 2 to C 8 olefin polymer composition in at least two reactors, the continuous multi-stage process comprising the steps of:
a) introducing a stream of a pre-polymerized solid Ziegler-Natta catalyst and a monomer of C 2 to C 8 olefin into a first polymerization reactor, thereby producing in a first polymerization a first C 2 to C 8 olefin polymer;
b) withdrawing a stream comprising the first C 2 to C 8 olefin polymer from the first polymerization reactor and passing it into a second polymerization reactor;
c) introducing a stream of a monomer of C 2 to C 8 olefin into the second polymerization reactor, thereby producing in a second polymerization a first polymer mixture comprising the first C 2 to C 8 olefin polymer and a second C 2 to C 8 olefin polymer produced in the second polymerization reactor; and
d) withdrawing a stream comprising the first polymer mixture from the second polymerization reactor, thereby obtaining the C 2 to C 8 olefin polymer composition;
wherein the pre-polymerized solid Ziegler-Natta catalyst is prepared by off-line pre-polymerization of a solid Ziegler-Natta catalyst component with a C 2 to C 4 olefin monomer before feeding to the continuous multi-stage process, and wherein the pre-polymerized solid Ziegler-Natta catalyst has a particle size distribution span ((d 90 -d 10 )/d 50 ) of below 1.5.

2. The continuous multi-stage process according to claim 1 , wherein the solid Ziegler-Natta catalyst component comprises:
(a1) a compound of a transition metal (TM), which transition metal is selected from one of the groups 4 to 6 of the periodic table (IUPAC),
(a2) a compound of a metal (M) which metal is selected from one of the groups 1 to 3 of the periodic table (IUPAC),
(a3) optionally an internal donor (ID) and
(a4) optionally a compound of a group 13 metal of the periodic table (IUPAC).

3. The continuous multi-stage process according to claim 1 , wherein the solid Ziegler-Natta catalyst component is in the form of particles having a mean particle size ranging from 3 to 200 μm.

4. The continuous multi-stage process according to claim 1 , wherein the off-line pre-polymerization is carried out in the presence of a co-catalyst (Co) and optionally in the presence of an external electron donor (ED); and/or
wherein the off-line pre-polymerization is carried out with a total residence time of 5 to 55 minutes.

5. The continuous multi-stage process according to claim 1 , wherein the off-line pre-polymerization degree is from 0.1 to 50 g polymer /g cat .

6. The continuous multi-stage process according to claim 1 , wherein the off-line pre-polymerization is carried out in a medium, wherein the medium is an oil or a hydrocarbon solvent.

7. The continuous multi-stage process according to claim 1 , wherein the off-line pre-polymerization is carried out at a temperature in a range from 0 to 50° C.

8. The continuous multi-stage process according to claim 1 , wherein pre-polymerized solid Ziegler-Natta catalyst has a particle size distribution span ((d 90 -d 10 )/d 50 ) of below 1.2.

9. The continuous multi-stage process according to claim 1 , wherein the first polymerization reactor in step a) is a loop reactor.

10. The continuous multi-stage process according to claim 1 , wherein the process comprises at least one gas phase reactor.

11. The continuous multi-stage process according to claim 1 , wherein the process comprises a further step e) of introducing the stream of step d) and a stream of a monomer of C 2 to C 8 olefin into a third polymerization reactor, thereby producing a second polymer mixture.

12. The continuous multi-stage process according to claim 11 , wherein the process further comprises a step f) of withdrawing a stream comprising the second polymer mixture from the third polymerization reactor.

13. The continuous multi-stage process according to claim 11 , wherein the process comprises two loop reactors and one gas phase reactor.

14. The continuous multi-stage process according to claim 11 , wherein the process comprises one loop reactor and two gas phase reactors.

15. The continuous multi-stage process according to claim 12 , wherein the process further comprises a step g) of introducing the second polymer mixture into a fourth polymerization reactor together with additional monomers selected from C 2 to C 8 olefins, thereby producing a third polymer mixture.

Assignees

• Borealis Ag

Inventors

• Nyfors Klaus
• Kanellopoulos Vasileios
• Elovainio Erno
• Tupe Ravindra
• Sumerin Victor

Classifications

• C08F2/001 Primary

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title

• C08F2/34

  Polymerisation in gaseous state · CPC title

• C08F4/022

  Magnesium halide as support anhydrous or hydrated or complexed by means of a Lewis base for Ziegler-type catalysts · CPC title

• C08F4/64

  Titanium, zirconium, hafnium or compounds thereof · CPC title

• C08F210/02

  Ethene · CPC title