Method for hydrolyzing polyvinyl acetate to prepare polyvinyl alcohol in high-temperature liquid water under catalysis of organic acid

A technology of polyvinyl acetate and high-temperature liquid water is applied in the field of polyvinyl acetate hydrolysis to prepare polyvinyl alcohol under the catalysis of organic acid in high-temperature liquid water, which can solve the problems of product molecular weight drop, weak catalytic effect, long reaction time, etc. The effect of increasing reaction speed, reducing depolymerization and improving quality

Inactive Publication Date: 2010-05-26
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although high-temperature liquid water has a certain acid-base catalytic ability, its catalytic effect is weak. If the reaction is carried out under medium and non-catalytic conditi

Method used

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  • Method for hydrolyzing polyvinyl acetate to prepare polyvinyl alcohol in high-temperature liquid water under catalysis of organic acid
  • Method for hydrolyzing polyvinyl acetate to prepare polyvinyl alcohol in high-temperature liquid water under catalysis of organic acid

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0032] Example 1

[0033] Add 300g acetic acid aqueous solution and 7.5g polyvinyl acetate into a 500mL batch-type high pressure reactor. The mass concentration of acetic acid in the acetic acid aqueous solution is 50g / L, the weight average molecular weight of the raw material polyvinyl acetate is 38,000, the acetic acid aqueous solution and polyvinyl acetate The mass ratio of esters is 40:1. Turn on the stirring, heat up to boiling under normal pressure, open the exhaust valve for 2 minutes, use steam to remove the air in the kettle; heat up to 200 ℃ to hydrolyze for 600 minutes; cool the hydrolyzate, release the pressure, and evaporate water and acetic acid under reduced pressure After vacuum drying, 3.7 g of polyvinyl alcohol solid product is obtained. The product was analyzed, and the degree of hydrolysis was 97.9%, the weight average molecular weight was 37,500, and the distribution width was 2.7.

Example Embodiment

[0034] Example 2

[0035] Add 300g of acetic acid aqueous solution and 15g of polyvinyl acetate into a 500mL batch-type autoclave. The mass concentration of acetic acid in the acetic acid solution is 35g / L, the weight average molecular weight of the raw material polyvinyl acetate is 38,000, and the acetic acid aqueous solution and polyvinyl acetate The mass ratio is 20:1. Turn on the stirring, heat up to boiling under normal pressure, open the exhaust valve for 3 minutes, use steam to remove the air in the kettle; heat up to 210°C and hydrolyze for 480 minutes; cool the hydrolyzate, release the pressure, and evaporate water and acetic acid under reduced pressure After vacuum drying, 7.5 g of polyvinyl alcohol solid product is obtained. The product was analyzed, the degree of hydrolysis was 98.8%, the weight average molecular weight was 36,900, and the distribution width was 2.7.

Example Embodiment

[0036] Example 3

[0037] Add 300g of acetic acid aqueous solution and 10g of polyvinyl acetate into a 500mL batch-type autoclave. The mass concentration of acetic acid in the acetic acid solution is 45g / L. The weight average molecular weight of the raw material polyvinyl acetate is 38,000. The acetic acid aqueous solution and polyvinyl acetate The mass ratio is 30:1. Turn on the stirring, heat up to boiling under normal pressure, open the exhaust valve for 4 minutes, use steam to remove the air in the kettle; heat up to 220 ℃ to hydrolyze for 340 minutes; cool the hydrolyzate, release the pressure, and evaporate the water and acetic acid under reduced pressure After vacuum drying, 5 g of polyvinyl alcohol solid product is obtained. The product was analyzed, and the degree of hydrolysis was 99%, the weight average molecular weight was 34,800, and the distribution width was 2.7.

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Abstract

The invention discloses a method for hydrolyzing polyvinyl acetate to prepare polyvinyl alcohol in high-temperature liquid water under the catalysis of organic acid. The method comprises the following steps of: (1) adding an organic acid aqueous solution and polyvinyl acetate into a high-pressure reaction kettle, stirring, raising temperature to boiling under normal pressure and keeping a vent valve open for 2-4 minutes; (2) raising the temperature to 200-300 DEG C and hydrolyzing for 0.2-10 hours; and (3) cooling hydrolysis liquid and decompressing, steaming off water and organic acid under decompression, and then vacuum drying to obtain a solid polyvinyl alcohol product. The organic acid in the method is a green catalyst, and the addition of the organic acid can greatly improve the reaction velocity and reduce the polymer depolymerization so as to improve the quality of the product. Hydrolysis products can be used as fiber products such as civil clothing materials, industrial cord threads, filter screens, and the like, textile size, coatings, adhesive, paper making processing aids, packaging films, emulsifying agents, dispersing agents, oil drilling coagulant, soil improvement agents, medicine, cosmetics, and the like.

Description

technical field [0001] The invention relates to a method for preparing polyvinyl alcohol by hydrolyzing polyvinyl acetate under organic acid catalysis in high-temperature liquid water. Background technique [0002] Polyvinyl acetate (PVAC) is also known as polyvinyl acetate. The molecular structure is (CH 2 -CH(OOCCH 3 )) n , an amorphous polymer obtained by polymerization of vinyl acetate, which belongs to thermoplastic resin. Depending on the polymerization method, colorless latex or colorless transparent bead-like solid can be obtained. Soluble in aromatic hydrocarbons, ketones, alcohols, esters and chloroform. Initiated by vinyl acetate with a free radical initiator, it can be produced by emulsion, suspension, bulk and solution polymerization. It is mainly used as coating, adhesive, paper, chewing gum base and fabric finishing agent. It can also be used as a raw material for polyvinyl alcohol and polyvinyl acetal. [0003] Polyvinyl alcohol (PVA) is a colorless, ...

Claims

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Application Information

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IPC IPC(8): C08F116/06C08F118/08C08F8/12
Inventor 吕秀阳张建飞刘体锋
Owner ZHEJIANG UNIV
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