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Method for preparing low-crystal point polyethylene under high pressure by tube process, and low-crystal point polyethylene

A polyethylene and high-pressure technology, applied in the field of polyethylene preparation, can solve the problems of high scrap rate of film blowing, high-end film production, and complicated solutions, and achieve the effect of improving printing quality, reducing film breaking rate and increasing sales price.

Active Publication Date: 2019-09-06
CHINA SHENHUA COAL TO LIQUID & CHEM CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] At present, the existing technology is to improve the polyolefin additive or catalyst configuration equipment, so as to produce polyethylene products with excellent performance, and mainly for linear polyethylene products, and through the reaction of high-pressure low-density polyethylene by tubular method, etc. There is no systematic report on the improvement of the operation method and thus the improvement of the crystallization point of the product
In addition, due to many reasons for the high crystal point of polyethylene products, difficult analysis, and complicated solutions, etc., the high crystal point of tubular high-pressure low-density polyethylene products has always been high, resulting in a high waste rate of blown film and cannot be used for high-end products. The problem of film material production has always existed

Method used

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  • Method for preparing low-crystal point polyethylene under high pressure by tube process, and low-crystal point polyethylene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] This embodiment is to illustrate the low crystal point polyethylene prepared by the method of the present invention.

[0055] (1) The ethylene monomer is compressed through a compressor; wherein, the filtration accuracy of the pipeline for transporting the ethylene is 1 μm, the content of alkyne in the ethylene monomer is 5 ppm, and the single-cylinder lubricating oil injection amount of the compressor is 2.5 liters / day;

[0056] (2) In the presence of an initiator, the compressed ethylene monomer after step (1) is subjected to an addition polymerization reaction in a reactor; wherein, the initiator is a peroxide, and in the peroxide The content of tert-butyl hydroperoxide is 100ppm; the reaction temperature of the first reaction zone in the reactor is 302°C, and the reaction temperature of the fourth reaction zone is 295°C; the addition polymerization reaction is carried out in the tubular reactor To carry out, the discharge of the tubular reactor is controlled by a p...

Embodiment 2

[0061] This embodiment is to illustrate the low crystal point polyethylene prepared by the method of the present invention.

[0062] (1) Compress ethylene monomer through compressor; Wherein, the filtration precision of the pipeline that transports described ethylene is 1 μm, and the content of alkyne in described ethylene monomer is 5ppm; Compressor single cylinder lubricating oil injection rate is 3 L / day;

[0063] (2) In the presence of an initiator, the compressed ethylene monomer obtained in step (1) is subjected to an addition polymerization reaction in a reactor; wherein, the initiator is a peroxide, and in the peroxide The content of tert-butyl hydroperoxide is 100ppm; increase the reaction temperature of the first reaction zone, be controlled at 305°C, reduce the reaction temperature of the fourth reaction zone, be controlled at 290°C; the addition polymerization reaction is carried out in a tubular reactor The discharge of the tubular reactor is controlled by a puls...

Embodiment 3

[0068] This embodiment is to illustrate the low crystal point polyethylene prepared by the method of the present invention.

[0069] The polyethylene product was prepared in the same manner as in Example 2, except that the reaction pulse level was adjusted to 10, and the reaction pulse period was adjusted to 90 seconds.

[0070] The properties of the prepared polyethylene products are shown in Table 1.

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Abstract

The invention relates to the technical field of polyethylene preparation, and discloses a method for preparing low-crystal point polyethylene under a high pressure by a tube process, and the low-crystal point polyethylene. The method comprises the following steps: (1) compressing an ethylene monomer through a compressor; wherein the filter fineness of a pipeline filter through which the ethylene monomer flows is equal to or less than 1 [mu]m, and the content of alkynes in the ethylene monomer is equal to or less than 10 ppm; (2) carrying out an addition polymerization reaction on the compressed ethylene monomer obtained in step (1) in the presence of an initiator, wherein the initiator is a peroxide, and the content of tert-butyl hydroperoxide in the peroxide is equal to or less than 200 ppm; (3) separating a product obtained in step (2); and (4) carrying out extrusion granulation on the separated molten polyethylene to obtain polyethylene particles. The crystal point of the polyethylene prepared by the method of the invention is controlled to improve the mechanical properties of a polyethylene film, improve the film blowing and forming rate and reduce the film rupture rate.

Description

technical field [0001] The invention relates to the technical field of polyethylene preparation, in particular to a method for preparing low-crystal point polyethylene under high pressure in a tubular method and the low-crystal point polyethylene. Background technique [0002] The production of high-pressure low-density polyethylene generally has two production processes: the tubular method and the kettle method. Among them, the tubular method has the characteristics of large processing capacity, low energy consumption, low equipment failure rate and long operation period. widely used by everyone. [0003] Due to the process characteristics of the tubular high-pressure low-density polyethylene device, the products prepared are mainly used for the production of film materials (greenhouse film, mulch film and shrink film, etc.), and the production of film materials is the most concerned and has the greatest impact on product quality. It is the crystal point of the raw materia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F110/02C08F2/00
CPCC08F110/02C08F2/00
Inventor 黄起中徐海波马雷孙爱光姜兴剑孙浩
Owner CHINA SHENHUA COAL TO LIQUID & CHEM CO LTD