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Method for maintaining melt flow index of polyethylene polymer product

A technology for polyethylene polymer and melt flow index, which is applied in the field of maintaining the melt flow index of polyethylene polymer products, and can solve problems such as difficulty in maintaining

Active Publication Date: 2022-07-01
UNIVATION TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Regardless of the cause, changes in reactor temperature may cause difficulties in maintaining the MI of the polyethylene polymer product at the target value due to changes in the reaction rate and hydrogen to ethylene gas ratio inside the reactor

Method used

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  • Method for maintaining melt flow index of polyethylene polymer product

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[0060] Some embodiments of the present disclosure will now be described in the following examples. All parts, ratios and percentages are by weight unless otherwise indicated.

[0061] Melt Flow Index (I 2 ). Density is measured according to ASTM D-105. Melt flow ratio (MFR) is measured according to ASTM D1238.

[0062]A pilot plant test was conducted to evaluate the effect of reactor temperature on H2 / C2 gas and H2 / C2 feed ratios. The polymerization reaction is carried out in a fluidized bed gas phase reactor. The fluidized bed consists of polymer particles. A gaseous feed stream of ethylene and hydrogen is introduced into the recycle gas line with liquid comonomer below the reactor bed. Hexene was used as comonomer. The individual flow rates of ethylene, hydrogen and comonomer were controlled to maintain fixed composition targets. The concentrations of all gases were measured by on-line gas chromatography to ensure relatively constant composition in the recycle gas st...

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Abstract

The present disclosure provides a method of maintaining a target value of melt flow index for a polyethylene polymer product synthesized in a fluidized bed gas phase reactor using a metallocene catalyst. The process comprises producing a polyethylene polymer product at a target value of melt flow index with a metallocene catalyst in a steady state fluidized bed gas phase reactor in which the fluidized bed gas phase reactor is in the first step. A feed of hydrogen and ethylene is received at a reactor temperature and at a hydrogen to ethylene feed ratio at the first ratio. When a change in reactor temperature is detected, the hydrogen to ethylene feed ratio is changed from the first ratio to the second ratio in order to maintain the melt flow index value of the polyethylene polymer product at the target value.

Description

technical field [0001] Embodiments of the present disclosure are directed to polyethylene polymer product production, and more specifically, to methods of maintaining the melt flow index of a polyethylene polymer product during changes in reactor temperature. Background technique [0002] Polyolefins, such as polyethylene polymers, are typically produced in low pressure reactors using, for example, solution, slurry or gas phase polymerization processes. The polymerization is carried out in the presence of a catalyst system, such as a Ziegler-Natta catalyst, a chromium-based catalyst, a metallocene catalyst, or a combination thereof. [0003] During its production, different process control models are used for real-time control of polyethylene polymer product production. These control models use polymer properties that are explicitly or analytically measurable over relatively short periods of time. The two most common properties that meet these requirements are density and ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F2/34C08F10/02
CPCC08F2/34C08F10/02C08F4/6592C08F2/24
Inventor B·J·赛华佗斯凯R·E·佩克诺B·C·洛克利尔J·法利
Owner UNIVATION TECH LLC