# US 11,897,976 B2 · Process for producing polyethylene

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- Number: US 11,897,976 B2
- Document ID: US11897976B2
- Status: Granted
- Kind: B2
- Application number: 17/702,957
- Filed: 2022-03-24
- Published: 2022-10-13
- Granted: 2024-02-13
- Earliest claimed: 2021-03-31
- Assignees: Sumitomo Chemical Company, Limited
- Applicants: Sumitomo Chemical Company, Limited
- Inventors: Kensuke Naraki; Toshihiko Manami
- Web page: https://patentgrep.com/patent/US11897976B2

## CPC

- C08F 2/01: characterised by special features of the polymerisation apparatus used
- C08F 10/02: Ethene
- C08F 110/02: Ethene
- C08F 2400/02: Control or adjustment of polymerization parameters
- C08F 2400/04: High pressure, i.e. P > 50 MPa, 500 bars or 7250 psi
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS

## Abstract

A process or apparatus for producing polyethylene with improved film thinning and handleability involves polymerizing high-pressure ethylene using an autoclave-type reactor in the presence of a polymerization initiator. The reaction zone of the reactor has at least two different temperature sections; the polymerization initiator and the ethylene are supplied to the upstream temperature section in the reaction zone and the ethylene is polymerized to generate polyethylene; unreacted ethylene and the polyethylene generated at the upstream temperature section in the reactor flow into the downstream temperature section in communication with the upstream temperature section, so that additional polyethylene is generated at the downstream temperature section. A difference (ΔT [° C.]) between a temperature (T1 [° C.]) of the temperature section positioned upstream and a temperature (T2 [° C.]) of the temperature section positioned downstream in the reaction zone that receives the polymerization initiator and is in the autoclave-type reactor is 2.1° C. to 8.4° C.

## Claims

### Claim 1

A process for producing polyethylene, comprising
subjecting high-pressure ethylene to polymerization using an autoclave-type reactor in presence of a polymerization initiator, wherein
the autoclave-type reactor has a reaction zone with at least two different temperature sections;
the polymerization initiator and the ethylene are supplied to the temperature section positioned upstream in the reaction zone of the autoclave-type reactor and the ethylene is polymerized to generate polyethylene;
unreacted ethylene and the polyethylene generated at the upstream temperature section in the autoclave-type reactor flow into the temperature section positioned downstream and in communication with the upstream temperature section in the reaction zone of the reactor, so that additional polyethylene is generated at the downstream temperature section; and
a difference (ΔT [° C.]) between a temperature (T1 [° C.]) of the temperature section positioned upstream and a temperature (T2 [° C.]) of the temperature section positioned downstream in the reaction zone that receives the polymerization initiator and is in the autoclave-type reactor is 2.1° C. or more and 8.4° C. or less.

### Claim 2 (depends on 1)

The production process according to claim 1, wherein two or more reaction zones are present.

### Claim 3 (depends on 1)

The production process according to claim 1, wherein ΔT [° C.]=T2 [° C.]−T1 [° C.].

### Claim 4 (depends on 1)

The production process according to claim 1, wherein the polyethylene to be produced is the following polyethylene:
having a ratio (WLog 10M>5.25/RLS) of a weight fraction (WLog 10M>5.25: represented in wt %) of a component with Log10 M of more than 5.25 in an integral distribution curve of polyethylene evaluated by gel permeation chromatography, where M represents a molecular weight in terms of polyethylene, to
a light scattering area ratio (RLS) of 5.7 or more and 6.7 or less, the light scattering area ratio represented by the following formula 1:
RLS=LS/LS′ (formula 1)
wherein LS denotes a light scattering area of a solution prepared by dissolving 40 mg of the polyethylene into 20 mL of o-dichlorobenzene, and
LS′ denotes a light scattering area of a solution prepared by dissolving 40 mg of standard polystyrene with a number average molecular weight of 1000 into 20 mL of o-dichlorobenzene.