Process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators

Patent metadata

Field	Value
Publication number	US-9243082-B2
Application number	US-201214355512-A
Country	US
Kind code	B2
Filing date	Nov 1, 2012
Priority date	Nov 3, 2011
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

Process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at pressures in the range of from 110 MPa to 500 MPa and temperatures in the range of from 100° C. to 350° C. in a continuously operated polymerization apparatus, wherein the reaction gas composition is compressed to the polymerization pressure by at least two sequentially operating compressors in which a low-pressure compressor first compresses the reaction gas composition to a pressure of from 10 MPa to 50 MPa and a high-pressure compressor then further compresses the reaction gas composition to the polymerization pressure wherein the high-pressure compressor is operated with a polyalkylene glycol based synthetic lubricant and oxygen is introduced into the fresh gas feed or into the polymerization apparatus in an amount that the gas composition to be compressed in the high-pressure compressor has an oxygen content in the range of from 0.01 ppm to 0.9 ppm.

First claim

What is claimed is:

1. A process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at pressures in the range of from 110 MPa to 500 MPa and temperatures in the range of from 100° C. to 350° C. in a continuously operated polymerization apparatus, wherein the reaction gas composition is compressed to the polymerization pressure by at least two sequentially operating compressors in which a low-pressure compressor first compresses the reaction gas composition to a pressure of from 10 MPa to 50 MPa and a high-pressure compressor then further compresses the reaction gas composition to the polymerization pressure wherein the high-pressure compressor is operated with a polyalkylene glycol based synthetic lubricant and oxygen is introduced into the process in an amount such that the gas composition to be compressed in the high-pressure compressor has an oxygen content in the range of from 0.01 ppm to 0.9 ppm.

2. A process according to claim 1 , wherein all compressors are operated with a polyalkylene glycol based synthetic lubricant.

3. A process according to claim 1 , wherein the low-pressure compressor and the high-pressure compressor are multistage compressors.

4. A process according to claim 1 , wherein the polymerization apparatus comprises a polymerization reactor, a high-pressure gas recycle line for recycling gas separated in a high-pressure separator from the reaction mixture and a low-pressure gas recycle line for recycling gas separated in a low-pressure separator from the reaction mixture and the gas recycled in the high-pressure gas recycle line is fed to the high-pressure compressor and the gas recycled in the low-pressure gas recycle line is fed to the low-pressure compressor.

5. A process according to claim 4 , wherein the low-pressure compressor is a multistage compressor and the pressure of the recycled gas fed from the low-pressure gas recycle line to the low-pressure compressor is lower than the pressure of a fresh gas feed of ethylenically unsaturated monomers and the recycled gas coming from the low-pressure gas recycle line is fed to the foremost of one or more first stages of the low-pressure compressors, which compress it to the pressure of the fresh feed of ethylenically unsaturated monomers, thereafter combined with the fresh feed of ethylenically unsaturated monomers and further compressed by one or more further stages of the low-pressure compressors to the pressure of from 10 MPa to 50 MPa.

6. A process according to claim 1 , wherein the polymerization apparatus comprises a tubular polymerization reactor or an autoclave as polymerization reactor.

7. A process according to claim 1 , wherein the free-radical polymerization initiators are organic peroxides or azo compounds or mixtures of such compounds.

8. A process according to claim 1 , wherein ethylene is polymerized or copolymerized with one or more other monomers for preparing ethylene homopolymers or ethylene copolymers.

9. A process for operating a compressor for pressurizing ethylenically unsaturated monomers to a pressure of from 5 MPa to 500 MPa in which the compressor is lubricated with a polyalkylene glycol based synthetic lubricant and the gas composition to be pressurized has an oxygen content in the range of from 0.01 ppm to 0.9 ppm.

10. A process according to claim 9 , wherein ethylene is pressurized.

11. A process according to claim 1 , wherein the oxygen is introduced into the process as pure oxygen or in the form of air.

12. A process according to claim 1 , wherein the oxygen is introduced into the process in an amount such that the gas composition to be compressed in the high-pressure compressor has an oxygen content in the range of from 0.1 ppm to 0.4 ppm.

13. A process for polymerizing or copolymerizing ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at pressures in the range of from 110 MPa to 500 MPa and temperatures in the range of from 100° C. to 350° C. in a continuously operated polymerization apparatus, wherein the reaction gas composition is compressed to the polymerization pressure by at least two sequentially operating compressors in which a low-pressure compressor first compresses the reaction gas composition to a pressure of from 10 MPa to 50 MPa and a high-pressure compressor then further compresses the reaction gas composition to the polymerization pressure wherein the high-pressure compressor is operated with a polyalkylene glycol based synthetic lubricant and oxygen is independently introduced into the process in an amount such that the gas composition to be compressed in the high-pressure compressor has an oxygen content in the range of from 0.01 ppm to 0.9 ppm.

Assignees

• Basell Polyolefine Gmbh

Inventors

• Berhalter Klaus
• Gonioukh Andrei
• Herrmann Thomas
• Finotto David
• Rieu Gilles
• Hautier Laurent
• Treis Christoph

Classifications

• C08F2/34 Primary

  Polymerisation in gaseous state · CPC title

• C08F4/34 Primary

  Per-compounds with one peroxy-radical · CPC title

• C08F4/04

  Azo-compounds · CPC title

• C08F10/00 Primary

  Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title