# US 11,440,983 B2 · Phase-stabilized ethylene alpha olefin copolymerization process

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- Number: US 11,440,983 B2
- Document ID: US11440983B2
- Status: Granted
- Kind: B2
- Application number: 16/761,917
- Filed: 2018-05-22
- Published: 2020-10-15
- Granted: 2022-09-13
- Earliest claimed: 2018-01-10
- Assignees: Borealis AG
- Applicants: Borealis AG
- Inventors: Mohammad Al-Haj Ali; Henry Sleijster
- Web page: https://patentgrep.com/patent/US11440983B2

## CPC

- C08F 210/02: Ethene
- C08F 210/16: Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
- C08F 2/01: characterised by special features of the polymerisation apparatus used
- C08F 2/04: Polymerisation in solution (C08F2/32 takes precedence)
- C08F 2/06: Organic solvent
- C08F 6/06: Treatment of polymer solutions {(C08F6/001, C08F6/006, C08F6/008, C08F6/02, C08F6/04 take precedence)}
- C08F 2420/00: Metallocene catalysts
- Y02P 20/54: using solvents, e.g. supercritical solvents or ionic liquids
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process for copolymerizing ethylene and at least one C3 to C8 alpha olefin to obtain an ethylene-C3 to C8 alpha olefin copolymer, the process comprising a) copolymerizing ethylene and at least one C3 to C8 alpha olefin in a solvent in a solution polymerization reactor to obtain an intermediate polymer solution, b) discharging an effluent stream from the intermediate polymer solution into a heat exchanger, c) setting the temperature of the effluent stream in the heat exchanger to obtain a heated effluent stream, d) feeding the heated effluent stream to a flash separation, e) separating at least a part of the ethylene-C3 to C8 alpha olefin copolymer in the flash separation, characterized by feeding an inert hydrocarbon fulfilling 90° C.<T(BP)<130° C. to the solution polymerization reactor; and/or accumulating an inert hydrocarbon fulfilling 90° C.<T(BP)<130° C. during the polymerization reaction; and/or feeding an inert hydrocarbon fulfilling 90° C.<T(BP)<130° C. to the discharged effluent stream of step b).

## Claims

### Claim 1

Process for copolymerizing ethylene and at least one C3 to C8 alpha olefin to obtain an ethylene-C3 to C8 alpha olefin copolymer, the process comprising
a) copolymerizing ethylene and at least one C3 to C8 alpha olefin in a solvent in a solution polymerization reactor (1) to obtain an intermediate polymer solution,
b) discharging an effluent stream from the intermediate polymer solution into a heat exchanger (2),
c) setting a temperature of the effluent stream in the heat exchanger (2) to obtain a heated effluent stream,
d) feeding the heated effluent stream to a first flash separation (3),
e) separating at least a part of the ethylene-C3 to C8 alpha olefin copolymer in the first flash separation (3),
wherein the process further comprises the steps of:
feeding an inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. to the solution polymerization reactor (1);
and/or
accumulating an inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. during the polymerization reaction;
and/or
feeding an inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. to the discharged effluent stream of step b), wherein the intermediate polymer solution in the solution polymerization reactor (1) comprises between 0.05 and 30 wt % inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C., based on a total weight of the intermediate polymer solution.

### Claim 2 (depends on 1)

Process according to claim 1, whereby the inert hydrocarbon fulfilling 90° C.<T(BP)<130° C. is a paraffinic hydrocarbon having 7 or 8 carbon atoms, an olefin having 7 or 8 carbon atoms, or mixtures thereof.

### Claim 3 (depends on 1)

Process according to claim 1, whereby the inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. comprises iso-octene, 4-methyl-3-heptene, 3-ethyl-2-hexene, 3-methyl-3-heptene, 2,3-dimethyl-2-hexene, 3-methyl-2-heptene, 3,4-dimethyl-trans-3-hexene, 2-methyl-2-heptene, or mixtures thereof.

### Claim 4 (depends on 1)

Process according to claim 1, wherein copolymerization of ethylene and the at least one C3 to C8 alpha olefin in solution in step a) takes place at a temperature of at least 140° C.

### Claim 5 (depends on 1)

Process according to claim 1, wherein in step c) the temperature of the effluent stream is set to a temperature within 200 to 280° C.

### Claim 6 (depends on 1)

Process according to claim 1, wherein the pressure in the solution polymerization reactor (1) and/or in the heat exchanger (2) is from 80 to 150 bar.

### Claim 7 (depends on 1)

Process according to claim 1, wherein the ethylene-C3 to C8 alpha olefin copolymer separated in step e) is directed into a second flash separation downstream of the first flash separation (3).

### Claim 8 (depends on 1)

Process according to claim 1, wherein accumulating the inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. during the polymerization reaction is done by
recovering the inert hydrocarbon from the first flash separation (3) and/or from a second flash separation downstream of the first flash separation (3), and
recycling the recovered inert hydrocarbon back to the solution polymerisation reactor (1).

### Claim 9 (depends on 1)

Process according to claim 1, wherein the obtained ethylene-C3 to C8 alpha olefin copolymer has a weight average molecular weight (Mw) of between 50,000 and 180,000 g/mol, determined according to ISO 16014-4:2012.

### Claim 10 (depends on 1)

Process according to claim 1, wherein the obtained ethylene-C3 to C8 alpha olefin copolymer has a melt flow rate MFR2 (2.16 kg, 190° C.) of equal or below 100 g/10 min, determined according to ISO 1133-1.

### Claim 11 (depends on 1)

Process according to claim 1, wherein the at least one C3 to C8 alpha olefin is selected from the group of propene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene, or combinations thereof.

### Claim 12 (depends on 1)

Process according to claim 1, wherein the catalyst used in the solution polymerization is a metallocene catalyst or a Ziegler-Natta catalyst.

### Claim 13

A method for maintaining an intermediate polymer solution in a solution polymerization reactor (1) in a single phase or for maintaining an effluent stream originating from the solution polymerization reactor in a single phase, comprising:
feeding an inert hydrocarbon to the solution polymerization reactor (1);
wherein the intermediate polymer solution is obtained by copolymerizing ethylene and at least one C3 to C8 alpha olefin copolymer in the solution polymerization reactor (1); and
wherein the intermediate polymer solution comprises between 0.05 and 30 wt. % of the inert hydrocarbon, based on a total weight of the intermediate polymer solution; and
wherein the inert hydrocarbon has a boiling point T(BP) that fullfills an inequality 90° C.<T(BP)<130° C.

### Claim 14

A method for maintaining a heated effluent stream heated in a heat exchanger (2) in a single phase, comprising:
copolymerizing ethylene and at least one C3 to C8 alpha olefin in a solvent in a solution polymerization reactor (1) to obtain an intermediate polymer solution;
discharging an effluent stream from the intermediate polymer solution into a heat exchanger (2);
feeding an inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C. to the effluent stream discharged from the solution polymerization reactor (1) into the heat exchanger (2); and
setting a temperature of the effluent stream in the heat exchanger (2) to obtain the heated effluent stream;
wherein the intermediate polymer solution comprises between 0.05 and 30 wt. % of the inert hydrocarbon having a boiling point T(BP) fulfilling 90° C.<T(BP)<130° C., based on a total weight of the intermediate polymer solution.