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Preparation method of ethylene-vinyl alcohol copolymer

A technology of vinyl alcohol copolymer and ethylene, which is applied in the field of copolymers, can solve the problems of easy yellowing of resin at high temperature, etc., and achieve the effects of improving heat resistance, improving alcoholysis efficiency, and increasing alcoholysis degree

Active Publication Date: 2021-07-02
CHINA PETROCHEMICAL CORP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In industrial production, high temperature and high pressure alcoholysis process is usually adopted. The higher the alcoholysis reaction temperature, the higher the alcoholysis reaction efficiency. However, due to the influence of high temperature and easy yellowing of the resin, the alcoholysis temperature can only be kept within a certain range, so the tower In alcoholysis, the improvement of alcoholysis efficiency can only seek other methods

Method used

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  • Preparation method of ethylene-vinyl alcohol copolymer

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The preparation method of ethylene-vinyl alcohol copolymer specifically carries out according to the following steps:

[0032] A. Copolymerization

[0033] 20 parts of methanol, 150 parts of vinyl acetate, 0.005 parts of azobisisobutyronitrile and ethylene are used as raw materials to carry out copolymerization reaction, the pressure in the kettle feeding ethylene is controlled at 6 MPa, the temperature of the copolymerization reaction is 40 °C, and the pressure is 6.5 MPa. The reaction time is 2.0 hours;

[0034] B. Alcoholysis

[0035] Add sodium hydroxide to the solution obtained in step A twice to carry out the alcoholysis reaction, the ratio of the amount of sodium hydroxide in the first time period to the amount of sodium hydroxide in the second time period is 2:1, the first time period and the second time period The ratio of the segment is 0.5:1, and the molar ratio of sodium hydroxide to the ethylene-vinyl acetate copolymer obtained by copolymerization is 0.3:...

Embodiment 2

[0042] The preparation method of ethylene-vinyl alcohol copolymer specifically carries out according to the following steps:

[0043] A. Copolymerization

[0044] Copolymerize with 100 parts of ethanol, 60 parts of vinyl acetate, 1 part of azobisisoheptanonitrile and ethylene as raw materials, control the pressure in the kettle feeding ethylene to 2.5 MPa, the temperature of the copolymerization reaction is 40 ° C, and the pressure is 2.0 MPa , the reaction time is 8.0 hours;

[0045] B. Alcoholysis

[0046] Add potassium hydroxide to the solution obtained in step A twice to carry out the alcoholysis reaction, the ratio of the amount of potassium hydroxide in the first time period to the amount of potassium hydroxide in the second time period is 0.8:1, the first time period and the second time period The ratio of segment is 1.5:1, and the molar ratio of potassium hydroxide and the ethylene-vinyl acetate copolymer obtained by copolymerization is 0.01:1;

[0047] C. Post-proc...

Embodiment 3

[0053] The preparation method of ethylene-vinyl alcohol copolymer specifically carries out according to the following steps:

[0054] A. Copolymerization

[0055]Use 40 parts of n-propanol, 90 parts of vinyl acetate, 0.05 parts of dimethyl azobisisobutyrate and ethylene as raw materials to carry out copolymerization reaction, control the pressure in the kettle feeding ethylene to 4.2 MPa, and the temperature of the copolymerization reaction to be 50 °C , the pressure is 4.5MPa, and the reaction time is 6.0 hours;

[0056] B. Alcoholysis

[0057] Add sodium methylate to the solution that step A obtains twice and carry out alcoholysis reaction, the sodium methylate consumption of the first time period and the sodium methylate consumption ratio of the second time period are 1.2:1, the initial time of alcoholysis and the late time ratio of alcoholysis are 1:1, the molar ratio of sodium methoxide to the ethylene-vinyl acetate copolymer obtained by copolymerization is 0.05:1;

[...

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Abstract

The invention belongs to the technical field of a copolymer containing only one carbon-carbon double bond of a monomer containing 4 carbon atoms, and specifically relates to a preparation method of an ethylene-vinyl alcohol copolymer, which includes the steps of copolymerization and alcoholysis, adding alkali twice The catalyst undergoes an alcoholysis reaction, the ratio of the amount of alkali catalyst used in the first time period to that in the second time period is 0.8:1-2:1, and the ratio between the first time period and the second time period is 1:1-1.5:1. The invention improves the alcoholysis efficiency and alcoholysis degree by controlling the alkali catalyst addition process; the ethylene-vinyl alcohol copolymer prepared in the invention has low coloring degree, smooth appearance, whiter hue, no white skin wrapping, and good heat resistance Excellent, yellowness index YI is 8‑11, alcoholysis degree is 99.3‑99.7%.

Description

technical field [0001] The invention belongs to the technical field of copolymers containing monomers with 4 carbon atoms and only one carbon-carbon double bond, and specifically relates to a preparation method of ethylene-vinyl alcohol copolymers. Background technique [0002] Ethylene-vinyl alcohol copolymer (EVOH), especially ethylene-vinyl alcohol copolymer with an ethylene content of 20-50% (mole percent), has excellent gas barrier properties, which are about 10,000 times that of ordinary polyethylene, plus its Transparency, processability, solvent resistance and antistatic properties make it widely used in packaging materials, automobile fuel tanks, oxygen-resistant floor heating pipes, textile materials and medical materials and other fields. Ethylene-vinyl alcohol copolymer is obtained by alcoholysis of ethylene-vinyl acetate copolymer. The high gas barrier property of ethylene-vinyl alcohol copolymer is directly related to the degree of alcoholysis. Under the same e...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F218/08C08F210/02C08F8/12C08L29/04C08K5/092C08K5/09C08K3/38
CPCC08F8/12C08F218/08C08K3/38C08K5/09C08K5/092C08K2003/387C08F210/02C08L29/04
Inventor 窦玉芹汪清泉胡腊梅黎园彭达平
Owner CHINA PETROCHEMICAL CORP
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