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Method for preparing polyethylene-vinyl acetate-vinyl alcohol terpolymer by hydrolyzing polyethylene and vinyl acetate in near-critical water without catalyst

A technology of polyethylene vinyl acetate and vinyl alcohol terpolymer, applied in the field of non-catalytic hydrolysis of polyethylene vinyl acetate in near critical water to prepare polyethylene-vinyl acetate-vinyl alcohol terpolymer, which can solve the problem of hydrolysis speed Slow, alkaline neutralization pollution, solvent recovery energy consumption and other problems, to achieve the effect of controllable degree of hydrolysis, fast speed, simple reaction process

Inactive Publication Date: 2010-12-29
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This hydrolysis reaction has the following disadvantages: on the one hand, the degree of hydrolysis of the hydrolyzate cannot be controlled, and it can only be deeply hydrolyzed, that is, directly hydrolyzed into polyethylene-vinyl alcohol copolymer; Alkali neutralization and serious pollution problems

Method used

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  • Method for preparing polyethylene-vinyl acetate-vinyl alcohol terpolymer by hydrolyzing polyethylene and vinyl acetate in near-critical water without catalyst
  • Method for preparing polyethylene-vinyl acetate-vinyl alcohol terpolymer by hydrolyzing polyethylene and vinyl acetate in near-critical water without catalyst
  • Method for preparing polyethylene-vinyl acetate-vinyl alcohol terpolymer by hydrolyzing polyethylene and vinyl acetate in near-critical water without catalyst

Examples

Experimental program
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Effect test

Embodiment 1

[0031] Add 300 g of deionized water and 7.5 g of EVA (VA-18%) into a 500 mL batch type autoclave, and the mass ratio of deionized water to polyethylene vinyl acetate is 40:1. Turn on stirring, heat up to boiling under normal pressure, open the exhaust valve for 2 minutes, and use water vapor to remove the air in the kettle; close the exhaust valve, continue to heat up to 200°C for 20 hours of hydrolysis; the hydrolyzate is cooled, depressurized, and filtered to obtain Solid product; The solid product obtains polyethylene-vinyl acetate-vinyl alcohol terpolymer 5.8g after washing with deionized water and vacuum drying. After analysis, the vinyl acetate content is 9.6%, and the vinyl alcohol content is 8.4%. The average molecular weight is 8.2×10 4 , with a distribution width of 3.1.

Embodiment 2

[0033]Add 300 g of deionized water and 10 g of EVA (VA-33%) into a 500 mL batch type autoclave, and the mass ratio of deionized water to polyethylene vinyl acetate is 30:1. Start stirring, heat up to boiling under normal pressure, open the exhaust valve for 3 minutes, and use water vapor to remove the air in the kettle; close the exhaust valve, continue to heat up to 220°C for 20 hours of hydrolysis; the hydrolyzate is cooled, depressurized, and filtered to obtain Solid product; The solid product obtains polyethylene-vinyl acetate-vinyl alcohol terpolymer 7.58g after washing with deionized water and vacuum drying. After analysis, the vinyl acetate content is 8.2%, and the vinyl alcohol content is 24.8%. The average molecular weight is 12.2×10 4 , with a distribution width of 3.1.

Embodiment 3

[0035] Add 300 g of deionized water and 15 g of EVA (VA-42%) in a 500 mL batch type autoclave, and the mass ratio of deionized water to polyethylene vinyl acetate is 20:1. Start stirring, heat up to boiling under normal pressure, open the exhaust valve for 4 minutes, and use water vapor to remove the air in the kettle; close the exhaust valve, continue to heat up to 240°C for 10 hours of hydrolysis; the hydrolyzate is cooled, depressurized, and filtered to obtain Solid product; The solid product obtains polyethylene-vinyl acetate-vinyl alcohol terpolymer 11.48g after washing with deionized water and vacuum drying. After analysis, the vinyl acetate content is 14.9%, and the vinyl alcohol content is 27.1%. The average molecular weight is 16.5×10 4 , with a distribution width of 3.1.

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Abstract

The invention discloses a method for preparing a polyethylene-vinyl acetate-vinyl alcohol terpolymer by hydrolyzing polyethylene and vinyl acetate in near-critical water without a catalyst, comprising the following steps: 1) adding deionized water, polyethylene and vinyl acetate with mass ratio of 1:1-40:1 to a high-pressure reactor, stirring the mixture, heating the mixture under normal pressure until the mixture boils and opening an exhaust valve for 2-5min; 2) raising the temperature to 200-290 DEG C and carrying out hydrolysis for 0.5-20h; 3) cooling the hydrolysate, releasing pressure from the cooled hydrolysate and filtering the hydrolysate; and 4) washing the product with the deionized water and vacuum-drying the product to obtain the polyethylene-vinyl acetate-vinyl alcohol terpolymer. The method dispenses with any catalyst during hydrolysis, solves the difficult problem of environmental pollution caused by acid and alkali catalytic hydrolysis and is simple in reaction process, controllable in degree of hydrolysis and environment-friendly. The hydrolysate can be used for packaging coating, food and drugs and carry out blending modification with other resins, etc.

Description

technical field [0001] The invention relates to a method for preparing polyethylene-vinyl acetate-vinyl alcohol terpolymer by non-catalytic hydrolysis of polyethylene vinyl acetate in near-critical water. Background technique [0002] Polyethylene-vinyl acetate-vinyl alcohol copolymer [P(E-VA-VOH)] is a highly crystalline thermoplastic resin obtained by hydrolysis of polyethylene vinyl acetate (EVA), with a chemical structure of [0003] [0004] Where m, x, n-x are the degrees of aggregation. Due to the introduction of highly polar and highly reactive hydroxyl groups on the EVA molecular chain, its performance has been greatly improved (such as high barrier performance, affinity for polar materials, etc.), and its broadened application range. On the one hand, a series of products with different ethylene, vinyl alcohol and vinyl acetate contents and their sequence distribution can be prepared by hydrolysis. The P(E-VA-VOH) products prepared have different properties due...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F210/02C08F218/08C08F8/12C08F216/06
Inventor 吕秀阳刘体锋张建飞
Owner ZHEJIANG UNIV
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