Production method of high-purity polyvinyl alcohol

A production method and technology of polyvinyl alcohol, applied in the production field of high-purity polyvinyl alcohol, can solve the problems of increased use cost, solvent residue, raw material loss, etc., and achieve the effects of easy implementation, small material loss, and reduced use cost

Active Publication Date: 2014-02-05
安徽皖维先进功能膜材料研究院有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At the same time, the secondary purification process will cause loss of raw m

Method used

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  • Production method of high-purity polyvinyl alcohol
  • Production method of high-purity polyvinyl alcohol
  • Production method of high-purity polyvinyl alcohol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Prepare low alcoholysis degree polyvinyl alcohol semi-finished products 17-88 from the production line (polymerization degree 1700±50, alcoholysis degree 88±2%), add it to the secondary alcoholysis kettle, and the mass ratio of input amount to alkali aqueous solution is 1:5 , the concentration of alkali aqueous solution is 25g / L, the temperature is 10°C, after reacting for 0.5 hours, add a small amount of acetic acid to neutralize. After overflow washing with desalinated water for 1 hour, it is sent to a centrifuge for separation, and the solid phase enters a vacuum dryer at a temperature of 0.05MPa-0.02MPa and 60-120°C for 1-2 hours. The finished product of polyvinyl alcohol was obtained and tested: the degree of alcoholysis was 99.7%, the content of sodium acetate was 0.25%, and the volatile matter was 0.39%.

[0030] Table 1 Example 1 data comparison

[0031] Test items

Embodiment 2

[0033] Prepare low alcoholysis degree polyvinyl alcohol semi-finished products 17-88 from the production line (polymerization degree 1700±50, alcoholysis degree 88±2%), add it to the secondary alcoholysis kettle, and the mass ratio of input amount to alkali aqueous solution is 1:5 , the concentration of the alkali aqueous solution is 12g / L, the temperature is 10°C, after reacting for 0.5 hours, add a small amount of acetic acid for neutralization. After overflow washing with desalinated water for 1 hour, it is sent to a centrifuge for separation, and the solid phase enters a vacuum dryer at a temperature of 0.05MPa-0.02MPa and 60-120°C for 1-2 hours. The finished product of polyvinyl alcohol was obtained and tested: the degree of alcoholysis was 92.9%, the content of sodium acetate was 0.26%, and the volatile matter was 0.42%.

[0034] Table 2 Example 2 data comparison

[0035] Test items

Embodiment 3

[0037] Prepare low alcoholysis degree polyvinyl alcohol semi-finished product 17-92 from the production line (polymerization degree 1700±50, alcoholysis degree 92±2%), put it into the secondary alcoholysis kettle, and the mass ratio of the input amount to the alkali aqueous solution is 1:5 , the concentration of the alkali aqueous solution is 15g / L, the temperature is 10°C, after reacting for 0.5 hours, add a small amount of acetic acid for neutralization. After overflow washing with desalinated water for 1 hour, it is sent to a centrifuge for separation, and the solid phase enters a vacuum dryer at a temperature of 0.05MPa-0.02MPa and 60-120°C for 1-2 hours. The finished product of polyvinyl alcohol was obtained and tested: the degree of alcoholysis was 99.5%, the content of sodium acetate was 0.31%, and the volatile matter was 0.33%.

[0038] Table 3 Example 3 data comparison

[0039] Test items

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Abstract

The invention discloses a production method of high-purity polyvinyl alcohol. The production method adopts polyvinyl acetate as the material, comprises alcoholysis reaction, saponification reaction as well as neutralizing, washing, separating and drying; the production method is characterized in that the saponification reaction is carried out in the following steps of adding a semi-finished product with alcoholysis degree of 80%-92% and grain size of 1mm-10mm, which is prepared by the alcoholysis reaction, into sodium hydroxide liquor with concentration of 4g/L-60g/L to stir and react for 0.5 hour under 0 DEG C-20 DEG C, wherein a batching mass ratio of the semi-finished product to alkali liquor is (1:2)-(1:7); residual alkaline is neutralized by using acetic acid after the reaction is ended, and then washed by using desalted water; and solid-liquid separation is carried out after washing, and solid is vacuum-dried to obtain the high-purity polyvinyl alcohol with alcoholysis degree greater than 92%. The product has sodium acetate content lower than 0.3%, and volatile component lower than 0.5%, can be directly applied to high-quality industries such as medicines and optical films without being re-processed, and is convenient for downstream manufacturers to use, so that using cost is lowered.

Description

1. Technical field [0001] The invention relates to a method for preparing polyvinyl alcohol (PVA for short), in particular to a method for producing high-purity polyvinyl alcohol. 2. Background technology [0002] Polyvinyl alcohol is a water-soluble polymer material, mainly used in textile, medicine, fiber, film, adhesive and other industries. Its molecular structure is simple, easy to modify, and its application range is showing a trend of continuous expansion. [0003] The starting material for polyvinyl alcohol production is acetylene. At present, my country has three raw material processing routes of calcium carbide acetylene, natural gas acetylene and petroleum ethylene. Acetylene reacts with acetic acid to produce vinyl acetate, which is then polymerized into polyvinyl acetate by solution polymerization. Polyvinyl acetate and sodium hydroxide methanol solution are mixed at high speed and then enter the belt alcoholysis machine for alcoholysis at 50°C. After alcohol...

Claims

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Application Information

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IPC IPC(8): C08F16/06C08F8/00
Inventor 吴福胜许献智向学毅王平林
Owner 安徽皖维先进功能膜材料研究院有限公司
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