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Preparation method of polyvinyl alcohol

A polyvinyl alcohol and polyvinyl acetate technology, which is applied in the field of polyvinyl alcohol preparation, can solve the problems that the process technology and equipment cannot meet the requirements, the quality and output are unsatisfactory, and the low-viscosity PVA is difficult to form, etc. Polymerization residence time, good molding, and the effect of improving product polymerization rate and output

Active Publication Date: 2014-12-03
CHINA PETROCHEMICAL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The process of VAC polymerizing PVAc is quite fast and very difficult to control
When vinyl acetate is polymerized in the prior art, the minimum degree of polymerization of PVA products can only reach about 400. When the degree of polymerization is lower, the existing process technology and equipment cannot meet the requirements, and the production efficiency is low, which seriously restricts the production of products with a low degree of polymerization. to develop
[0003] General polyvinyl alcohol polymerization production technology, low polymerization rate, unsatisfactory quality and output
Especially in the production of low-polymerization and low-viscosity PVA products, when the polymerization rate exceeds 80%, the initiator addition rate is high, and the high initiator addition rate causes low-viscosity PVA products to be poor in quality and yellow in color, which seriously affects the product. Quality; and low-viscosity PVA is difficult to form, and causes frequent failures in pressure feeding

Method used

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  • Preparation method of polyvinyl alcohol
  • Preparation method of polyvinyl alcohol
  • Preparation method of polyvinyl alcohol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The preparation method of the PVA product of embodiment 1 degree of polymerization 300

[0019] 1. Specific operation steps

[0020] Add tert-butyl peroxypivalate to the solvent methanol at -5°C; preheat vinyl acetate, methanol and initiator methanol solution to 60°C, and the preheated material enters a 22.8 cubic meter agitator And the first-stage reaction kettle of the reflux condenser, the reaction temperature is 66°C, the materials are continuously added, and the residence time is 2.5h. Then enter the second-stage reactor to continue polymerization, the average residence time of the material in the second-stage reactor is about 2.5h, and then pass into the third-stage reactor. After the reaction, unreacted monomers are blown out with methanol steam, and the polyvinyl acetate after demonomerization is diluted with methanol and sent to the alcoholysis process. Send the obtained polyvinyl acetate methanol solution into the alcoholysis machine, and add alkali methanol...

Embodiment 2

[0023] The preparation method of the PVA product of embodiment 2 degree of polymerization 400

[0024] 1. Specific operation steps

[0025] Add tert-butyl peroxypivalate to the solvent methanol at -5°C; preheat vinyl acetate, methanol and initiator methanol solution to 60°C, and the preheated material enters a 22.8 cubic meter agitator And the first-stage reaction kettle of the reflux condenser, the reaction temperature is 65°C, the materials are continuously added, and the residence time is 2h. Then enter the second-stage reactor to continue polymerization. The average residence time of the materials in the second-stage reactor is about 2 hours, and then pass into the third-stage reactor. After the reaction, unreacted monomers are blown out with methanol steam, and the polyvinyl acetate after demonomerization is diluted with methanol and sent to the alcoholysis process. Send the obtained polyvinyl acetate methanol solution into the alcoholysis machine, and add alkali methan...

Embodiment 3

[0028] The preparation method of the PVA product of embodiment 3 degree of polymerization 500

[0029] 1. Specific operation steps

[0030] Add tert-butyl peroxypivalate to the solvent methanol at -5°C; preheat vinyl acetate, methanol and initiator methanol solution to 60°C, and the preheated material enters a 22.8 cubic meter agitator And the first-stage reaction kettle of the reflux condenser, the reaction temperature is 65°C, the materials are continuously added, and the residence time is 1.5h. Then enter the second-stage reactor to continue polymerization, the average residence time of the material in the second-stage reactor is about 1.5h, and then pass into the third-stage reactor. After the reaction, unreacted monomers are blown out with methanol steam, and the polyvinyl acetate after demonomerization is diluted with methanol and sent to the alcoholysis process. Send the obtained polyvinyl acetate methanol solution into the alcoholysis machine, and add alkali methanol...

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Abstract

The invention provides a preparation method of polyvinyl alcohol; through control of polymerization process parameters of polyvinyl alcohol and reasonable matching of the methanol amount, the initiator amount and the reaction time, the polymerization reaction speed and course are effectively controlled, the addition amount of a catalyst is greatly reduced, resources and costs are saved, the polymerization residence time is prolonged, the reaction is more thorough and complete, and the product polymerization rate and yield are improved.

Description

technical field [0001] The present invention relates to the preparation method of polyvinyl alcohol. Background technique [0002] Vinyl acetate (VAC) is a commonly used chemical intermediate. Its molecule contains vinyl groups and can be polymerized. The polymerized product polyvinyl acetate (PVAC) is the raw material for the preparation of polyvinyl alcohol (PVA). In the current process of industrialized production of PVAC, the polymerization method of PVAC is to adopt monomer VAC to carry out free radical solution polymerization in a solvent, including the preparation of initiator, the polymerization of monomer, the separation and rectification of polymerization liquid, and the described batching is Using methanol as a solvent, add the monomer VAC, solvent, initiator, etc. measured according to the ratio into the polymerization tank to carry out polymerization reaction. After the polymerization is completed, the PVAC-methanol solution obtained from the polymerization is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F118/08C08F8/00
Inventor 秦庆伟张仁文张志红黄勇贺华嘉
Owner CHINA PETROCHEMICAL CORP
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