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Double series reactor process for preparing polyethylene

A series reactor, polyethylene technology, applied in the double series reactor process field, can solve the problems of low activity, difficult to control, high polymerization rate, and achieve the effect of simple process

Inactive Publication Date: 2010-06-16
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

And if the traditional Z-N catalyst first reactor is used to produce high molecular weight polyethylene, its activity will decrease during the first stage of polymerization in the first reactor, and when the active component enters the second stage reaction, due to the presence of relatively The relatively low activity of hydrogen and active components themselves makes the polymerization rate initially high and then gradually decreases, which makes the residence time of the second-stage reactor much higher than that of the first-stage reactor.
Means, the second-stage reaction requires a larger size, and the entire polymerization process is difficult to control

Method used

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  • Double series reactor process for preparing polyethylene
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preparation example Construction

[0037] Preparation of composite catalyst:

[0038] A: Preparation (BuCp) 2 ZrCl 2 -M-1 composite catalyst

[0039] For the preparation method of the supported Ziegler-Natta catalyst, refer to the M catalyst obtained from the patent EP688794. Under the protection of nitrogen, 3g of M catalyst was added into a stirred reaction flask. Add 30ml of styrene-acrylic acid copolymer (-COOH content in the copolymer: 3.5mmol / g polymer) in tetrahydrofuran (containing 0.025g polymer / ml solution) to the reaction flask, and stir at 0°C for 30min. Then add 50ml of isopentane into the reaction flask at a rate of 1ml per minute. After stirring was stopped to allow the solids to settle, the supernatant was removed and the residue was washed with isopentane (30ml / time) and then purged with nitrogen at 70°C until a free flowing powder was obtained. Take another mixing bottle and add 30ml (BuCp) 2 ZrCl 2 Add 8.6ml of MMAO in heptane solution (1.9mmol / ml) to n-hexane solution (3.75mmol / ml), a...

Embodiment 1-6

[0045] use as figure 1 The two-reactor setup shown,

[0046] R1 is the first reactor;

[0047] R2 is the second reactor;

[0048] L 1 It is the first reactor reaction material ethylene, comonomer feeding line;

[0049] L 2 It is the discharge line of the reaction material of the first reactor, and this discharge is directly added to the second reactor;

[0050] L 3 It is the discharge line of the second reactor;

[0051] L 4For the second reactor, the reaction materials ethylene and hydrogen enter the feed line.

[0052] Replace the Φ76×700mm adiabatic fluidized bed polymerization reactor several times with nitrogen gas, and then use ethylene gas in the industrial device to maintain the flow replacement of the reactor for more than 2 hours. Into the reactor, add 2.1Mpa of fresh ethylene gas, 3.8Mpa of butene-1 partial pressure, the initial reaction temperature is 60°C, take 0.1g of the above catalyst, and carry it into the first reactor with high-pressure nitrogen (3....

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Abstract

The invention discloses a double series reactor process for preparing polyethylene, which comprises the following steps: ethylene and alpha-alkene comonomer react in a first reactor under the effect of a composite catalyst, the material in the first reactor after reaction is directly transferred to a second reactor, and ethylene and hydrogen react in the second reactor. The composite catalyst comprises: (1) a Ziegler Natta catalyst loaded on a carrier; (2) a polymer layer covered on the Ziegler Natta catalyst loaded on the carrier; and (3) a metallocene catalyst loaded in or loaded on the polymer layer. High molecular weight low-density polyethylene is produced in the first reactor, and low-molecular weight high-density resin is produced in the second reactor. No degasser is additionally arranged in the series polymerization process. The obtained polyethylene blend product has a melt flow ratio of about 40-500 and full density polyethylene of 0.900-0.975g / cm3.

Description

technical field [0001] The invention relates to a double series reactor process for preparing polyethylene, especially suitable for preparing polyethylene with wide melt flow ratio. Background technique [0002] Polyethylene is a very important synthetic plastic. With the continuous emergence of new technologies and new products, the market has more and more requirements for polyethylene, and at the same time, the requirements for polyethylene's performance such as toughness, strength and environmental stress cracking resistance are getting higher and higher. Bimodal polyethylene has both high molecular weight part to provide mechanical strength and low molecular weight part to improve processing performance, so it is favored by people. In addition, improving the performance of polyethylene materials, optimizing the production process of polyethylene materials, and continuously developing higher-grade new polyethylene-based resins have attracted increasing attention. Exist...

Claims

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Application Information

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IPC IPC(8): C08F10/02C08F2/01
Inventor 阳永荣吴文清骆广海历伟王树芳蒋斌波王靖岱
Owner CHINA PETROLEUM & CHEM CORP
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