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A method for high-pressure olefin polymerization

An olefin polymerization, high-pressure technology, applied in the field of high-pressure olefin polymerization, can solve problems such as pipeline ethylene decomposition, high ethylene conversion rate, and blockage of outlet pipelines, so as to ensure sufficient decomposition and avoid the risk of ethylene decomposition.

Active Publication Date: 2021-09-07
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In addition, for the experimental small-scale polymerization reactor, it is necessary to strictly control the average residence time of the reactor for the ultra-high pressure ethylene polymerization method, so as to avoid excessive residual undecomposed initiator in the outlet material caused by too short residence time, which will lead to subsequent pipe failures. If the reaction continues in the road, the outlet pipe will be blocked or the pipe will be overheated to cause ethylene decomposition; if the residence time is too long, the ethylene conversion rate in the reactor will be too high, causing the polymer to stick to the wall and affecting the heat exchange of the reactor. The present invention aims to solve this problem. Provide a safe and stable operating environment for experimental small polymerization reactors

Method used

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  • A method for high-pressure olefin polymerization
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  • A method for high-pressure olefin polymerization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-5

[0030] Ethylene and ethane are uniformly mixed in the gas distribution tank with a mass flow ratio of 0.98:0.02. The mixed gas is pressurized to 2000bar by a multi-stage compressor, and vinyl acetate is injected into the 50°C premix tank through a diaphragm metering pump. At the same time, TBPB is Isododecane is configured as a solvent to form an initiator solution with a mass concentration of 25%, which is introduced into the premix tank through a syringe pump, and the mass fraction of effective oxygen content in the reaction system is controlled to be 2.5×10 -5 . The reaction kettle has a volume of 0.1 L, and the reaction is carried out at a temperature of 250° C. and a pressure of 2000 bar, and the reaction time is 1 h. The feed flow rate of each component adopts the conditions shown in Table 1 below.

[0031] Under the experimental conditions of this example, the density of ethylene is about 500kg / m 3 , the density of vinyl acetate is about 1000kg / m 3 , The specific hea...

Embodiment 1

[0036] Taking Example 1 as an example,

[0037] Calculated according to the experimental conditions of this embodiment, the range of the average residence time needs to be kept at 11.2<τ<60s.

[0038] (according to 10·t 1 / 2 Available )

Embodiment 2

[0039] In Example 2 and Example 4, during the reaction process of 1 hour, polyethylene and its copolymer were successfully prepared, and no abnormal phenomenon occurred. In Example 1, during the reaction process of 1 hour, after the reaction was carried out for 30 minutes, an abnormal temperature rise was detected in the kettle. After the reaction was stopped, the situation in the kettle was checked, and it was found that there were some polymers sticking to the wall. During the reaction process of Example 3 and Example 5, an abnormal temperature rise was detected at the pipeline from the outlet to the storage tank at the initial stage of the reaction. The reason was that the residual amount of the initiator in the outlet material was too high, and there was still a reaction in the pipeline. Keep exothermic.

[0040] By strictly controlling the average residence time of the reactor, the present invention avoids excessive residual undecomposed initiator in the outlet material c...

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Abstract

The invention discloses a method for high-pressure olefin polymerization. Free radical polymerization reaction initiated by ethylene or ethylene and its comonomer under the conditions of pressure range 100MPa-400MPa and temperature range 100-400℃, in the presence of a free radical initiator in the reaction system. The average residence time of the control reactor is not less than 10 times the half-life of the initiator used under the reaction conditions to ensure that the initiator is fully decomposed, and the content of the initiator in the outlet material should be less than one thousandth; to ensure that the reaction equipment does not Adhesion will occur. The average residence time is not greater than V·ρ·(Cp· Δ T‑1 / 10· Δ H) and the ratio of the average heat transfer Q of the jacket under the reaction conditions, so as to ensure that the content of the polymerized product is lower than 10%, so as to ensure that the reaction equipment does not stick to the wall during continuous production.

Description

technical field [0001] The invention belongs to the field of ethylene polymerization equipment and polymerization technology, in particular to a method for high-pressure olefin polymerization. Background technique [0002] Ethylene copolymers or low density polyethylenes with polar comonomers can be produced by free radical polymerization of ethylene and comonomers at high temperature (100°C-300°C) and ultra-high pressure (1000bar-3000bar). High-pressure low-density polyethylene and its copolymers have always been the focus of the polyolefin industry due to their extremely harsh production conditions and excellent transparency and processability. They are mainly used in the manufacture of films, coating materials for wires and cables, pipes, coatings layered products, etc. In addition, LDPE products have no initiator residue, high purity, and can produce various copolymer products such as ethylene-vinyl acetate, ethylene-propyl acrylate, ethylene-methyl methacrylate, etc., ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F210/02C08F218/08C08F2/01C08F2/34
CPCC08F2/01C08F2/34C08F210/02C08F218/08
Inventor 蒋斌波陈湛旻任聪静阳永荣王靖岱廖祖维黄正梁孙婧元杨遥马玉龙
Owner ZHEJIANG UNIV
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