Preparation method of EVOH (ethylene-vinyl alcohol) copolymer

A vinyl alcohol copolymer and ethylene technology, applied in the field of preparation of ethylene-vinyl alcohol copolymer, can solve the problems of low reaction efficiency, difficult control of reaction speed, unstable production, etc., and achieves good transparency, controllable reaction rate, polymerization The effect of high reaction efficiency

Inactive Publication Date: 2016-11-23
CHINA PETROCHEMICAL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the process of copolymerization of ethylene and vinyl acetate, there are generally technical ...

Method used

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  • Preparation method of EVOH (ethylene-vinyl alcohol) copolymer
  • Preparation method of EVOH (ethylene-vinyl alcohol) copolymer

Examples

Experimental program
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Effect test

Embodiment 1

[0030] A preparation method of ethylene-vinyl alcohol copolymer, using methanol / tert-butanol mixed solvent, vinyl acetate monomer, popenyl peroxyneodecanoate initiator and ethylene monomer as raw materials, deoxidizing the raw materials, and Internal replacement, initial feeding, polymerization reaction, blowing out residual sheet and saponification steps to prepare ethylene-vinyl alcohol copolymer; the deoxygenation of the raw materials is to add vinyl acetate monomer, solvent and initiator into the mixing tank and stir, while stirring Nitrogen is mixed evenly and replaced so that the oxygen content in the system is less than 1.0*10 -3 mol / L; The polymerization reaction efficiency is greatly improved by adopting the above raw material deoxygenation steps, and the conversion rate reaches more than 60%.

Embodiment 2

[0032] A preparation method of ethylene-vinyl alcohol copolymer, which uses ethanol / ethylene glycol mixed solvent, vinyl acetate monomer, azobisisobutyronitrile initiator and ethylene monomer as raw materials, deoxidizes the raw materials, and replaces them in a kettle , initial feeding, polymerization reaction, blowing out residual single and saponification steps to prepare ethylene-vinyl alcohol copolymer; said raw material deoxygenation is to add vinyl acetate monomer, solvent and initiator to the mixing tank and stir, and feed nitrogen gas while stirring Uniform, replacement, so that the oxygen content in the system is less than 1.0*10 -3 mol / L; the replacement in the kettle uses 5-10bar N 2 The reactor was replaced twice, and then replaced twice with 5-10 bar ethylene, and each time the replacement lasted for 5-9 minutes respectively.

Embodiment 3

[0034] A preparation method of ethylene-vinyl alcohol copolymer, as follows:

[0035] 1) Deoxidation of raw materials

[0036] Add the vinyl acetate monomer, the above-mentioned solvent and the initiator into the mixing tank, start the stirring, pass in nitrogen gas while stirring, mix evenly, and fully replace, so that the oxygen content in the system is less than 1.0*10 -3 mol / L;

[0037] 2), replacement in the kettle

[0038] Use 5~10bar N 2 Replace the reactor twice, and then replace it twice with 5-10 bar ethylene, each time for 5-9 minutes;

[0039] 3), initial feeding

[0040] Add the above-mentioned vinyl acetate, methanol / ethanol mixed solvent and azobisisobutyronitrile initiator deoxygenated from raw materials into the reaction kettle through a pump, and stir at room temperature at 60-180rpm for 5-10min;

[0041] 4), polymerization reaction

[0042] Feed ethylene monomer, control the pressure at 10-60bar, start timing when the temperature in the kettle is 40-80...

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Abstract

A preparation method of an EVOH (ethylene-vinyl alcohol) copolymer comprises steps as follows: a solvent, vinyl acetate monomers, an initiator and vinyl monomers are used as raw materials, and the EVOH copolymer is prepared through steps including replacement in a kettle, initial addition, a polymerization reaction, blowing out of residual monomers and saponification; the step of oxygen removal of the raw materials is implemented before replacement in the kettle and is implemented as follows: the vinyl acetate monomers, the solvent and the initiator are added to a mixing tank to be stirred, nitrogen is introduced while stirring to be evenly mixed, replacement is performed, and the content of oxygen in a system is smaller than 1.0*10<-3> mol/L. With the preparation method, the efficiency of the polymerization reaction is high, the conversion ratio of the polymerization reaction is 60% or above and can reach 85%, and the reaction speed is controllable. The obtained EVOH product has the good quality as follows: the chromaticity ranges from 1.0 degree to 3.0 degrees, the transparency is good, and the product is crystal clear, has the high barrier property, has the oxygen permeability being 1.0-1.2 cm<3>/(m<2>.24h.0.1 Mpa) and the water vapor permeability being 3.0-3.2 g/(m<2>.24h) and has the good processability.

Description

technical field [0001] The invention relates to the preparation of ethylene-vinyl alcohol copolymers, in particular to a preparation method of ethylene-vinyl alcohol copolymers with high conversion rate. Background technique [0002] Ethylene-vinyl alcohol copolymer (EVOH), due to its excellent gas barrier properties, transparency, processability, solvent resistance and antistatic properties, has been widely used in automotive fuel tanks, packaging materials, oxygen barrier floor heating pipes and other fields application. Generally, it can be prepared by saponification of ethylene and vinyl acetate through conventional methods such as emulsion polymerization, solution polymerization or suspension polymerization. In the process of copolymerization of ethylene and vinyl acetate, there are generally technical problems such as low reaction efficiency, difficult control of reaction speed, and unstable production. Contents of the invention [0003] The object of the present i...

Claims

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Application Information

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IPC IPC(8): C08F218/08C08F210/02C08F8/12
Inventor 任文革窦玉芹胡腊梅吴永忠郭永松
Owner CHINA PETROCHEMICAL CORP
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