High pressure free radical polymerization process with flexible control of molecular weight distribution

Patent metadata

Field	Value
Publication number	US-10501561-B2
Application number	US-201615738064-A
Country	US
Kind code	B2
Filing date	Jun 24, 2016
Priority date	Jun 25, 2015
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

Ethylene-based polymer, LDPE, is made in a high pressure polymerization process to comprising at least the step of polymerizing a reaction mixture comprising ethylene, using a reactor configuration comprising (A) at least two reaction zones, a first reaction zone (reaction zone 1) and an i reaction zone (reaction zone i where i>2), (B) at least two ethylene feed streams, each feed stream comprising a percentage of the total make-up ethylene fed to the polymerization process, in which a first ethylene feed stream is sent to reaction zone 1 and a second ethylene feed stream is sent to reaction zone i, and (C) a control system to control the percentage of the total make-up ethylene in the ethylene feed stream sent to reaction zone 1 and the percentage of the total make-up ethylene in the ethylene feed stream sent to reaction zone i.

First claim

The invention claimed is:

1. A high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following step:
polymerizing a reaction mixture comprising ethylene, using a reactor configuration comprising (A) at least two reaction zones, a first reaction zone (reaction zone 1) and an i reaction zone (reaction zone i where i≥2), (B) at least two ethylene feed streams, each feed stream comprising a percentage of the total make-up ethylene fed to the polymerization process, in which a first ethylene feed stream is sent to reaction zone 1 and a second ethylene feed stream is sent to reaction zone i, and (C) a control system to control the percentage of the total make-up ethylene in the ethylene feed stream sent to reaction zone 1 and the percentage of the total make-up ethylene in the ethylene feed stream sent to reaction zone i,
wherein the reactor configuration further comprises at least one analyzer for detecting a component of a stream of the reactor configuration or determining a property of the ethylene-based polymer produced by the high pressure polymerization process,
wherein the analyzer and a valve of the control system are connected through a feedback loop.

2. The process of claim 1 , wherein the control system comprises a valve on a line through which an ethylene feed stream is delivered to a reaction zone.

3. The process of claim 2 , wherein the valve is a three-port valve.

4. The process of claim 1 , wherein the analyzer is at least one of a gas chromatograph or an infrared spectrometer.

5. The process of claim 1 , wherein the measured property of the ethylene-based polymer is at least one of a rheological property or an optical property.

6. The process of claim 5 , wherein the rheological property is at least one of melt strength and melt elasticity.

7. The process of claim 1 , wherein the percentage of make-up ethylene in each of the first and second ethylene feed streams is from 1 to 99%.

8. The process of claim 1 , wherein each of the first and second ethylene feed streams further comprises a percentage of the total of at least one CTA make-up system fed to the high pressure polymerization process.

9. The process of claim 1 , wherein Z1 is a ratio of moles of CTA to moles of ethylene in reaction zone 1 and Zi is a ratio of moles of CTA to moles of ethylene in reaction zone i, Z1 and Zi reported in units of parts per million (ppm).

10. The process of claim 9 , wherein a ratio Z1/Zi is controlled to be from 0.2 to 2.0.

Assignees

• Dow Global Technologies Llc

Inventors

• Berbee Otto J
• Hosman Cornelis J F
• Goncalves Sergio E
• Hinrichs Stefan

Classifications

• C08F210/02 Primary

  Ethene · CPC title

• C08F2/34 Primary

  Polymerisation in gaseous state · CPC title

• B05C17/00569

  with a pump in the hand tool · CPC title

• C08F2/00

  Processes of polymerisation · CPC title

• A46B11/06

  connected to supply pipe {or to other external supply means (A46B11/0003 and A46B11/0006 take precedence)} · CPC title