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Preparation method of dispersing agent of chemically modified polyvinyl alcohol

A polyvinyl alcohol, chemical modification technology, applied in the field of preparation of chemically modified polyvinyl alcohol dispersants, can solve the problems of quality reduction, wide molecular weight distribution of polyvinyl chloride resin, uneven distribution of polyvinyl alcohol double bonds, etc. Achieve high absorption value and maintain stability

Active Publication Date: 2011-09-07
TIANJIN SUNNYMER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, the double bond distribution of polyvinyl alcohol obtained by this method is uneven, which will cause the molecular weight distribution of polyvinyl chloride resin to be wide and the quality to decline.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Add 100 parts by weight of vinyl acetate, 80 parts by weight of methanol, 1.5 parts by weight of acetaldehyde and 1wt% azobisisoheptanonitrile based on vinyl acetate, feed nitrogen to replace the air, heat the reactor, and heat up React at 40°C for 10 minutes, then heat up to 65°C for polymerization, and then inject a 1% methanol solution containing 0.5wt% azobisisoheptanonitrile equivalent to vinyl acetate monomer through a syringe pump. The injection time is 6 hours, and the total The reaction time was terminated after 12h. After the polymerization, the temperature is raised to evaporate and recover methanol and residual monomers.

[0030] Add methanol to the reaction mixture to adjust the content to 20wt%, then add 4.5% mmol of sodium hydroxide in methanol per mole of vinyl acetate, then add white oil equivalent to 80wt% of the reaction mixture, and alcoholyze at 40°C After 2.8 hours, polyvinyl alcohol (degree of alcoholysis 72.48 mol%, viscosity of 4% solution at 2...

example 2

[0033] Add 60 parts by weight of vinyl acetate monomers and 0.8 parts by weight of benzaldehyde in the polymerization kettle, then add azobisisobutyronitrile equivalent to 1wt% of the added monomers, feed nitrogen, replace the air, and then heat up to React at 40°C for 10 minutes and then heat up to 62°C for polymerization. When the polymerization temperature is reached, inject 40 parts by weight of vinyl acetate monomer containing an injection amount of 1.5wt% azobisisobutyronitrile through a syringe pump. The injection time is 6 hours. The reaction time is 12h. After the polymerization is completed, the temperature is raised to evaporate and recover the residual monomer.

[0034] Add methanol to the reaction mixture to adjust the content to 20wt%, then add 10.5% mmol of sodium hydroxide in methanol per mole of vinyl acetate, then add heptane equivalent to 100wt% of the reaction mixture, and alcoholyze at 40°C for 2.8 h to obtain polyvinyl alcohol (degree of alcoholysis 77.2...

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Abstract

The invention discloses a preparation method of a dispersing agent of chemically modified polyvinyl alcohol, which comprises the following: a) polyvinyl acetate preparing process with a bulk method or a-1) a solution method, b) special alcoholysis process and c) drying process. The preparation method is characterized in that in the polyvinyl acetate preparing process with the bulk method and the solution method, a molecular weight regulator for controlling polymer is added, and the molecular weight regulator is acetaldehyde, butyraldehyde, paraldehyde or benzaldehyde or mixture of the above; oil is adopted as suspending agent in the alcoholysis process, and the suspending agent is isododecane, n-heptane, liquid paraffin, white oil or n-alkane of more than C15; and an end group structure of a molecular chain of the polyvinyl alcohol includes more double bonds to be used as the dispersing agent which has the excellent property of protecting the vinyl chloride monomer. The apparent of the dispersing agent of the polyvinyl alcohol is light yellow spherical powder. The preparation method of the invention has economical production cost, and excellent product performance, and the product is specially used as the dispersing agent of a suspension polymerization process of the vinyl chloride and also can be used for a hot water feeding process of vinyl chloride suspension polymerization.

Description

technical field [0001] The invention relates to a preparation method of a chemically modified polyvinyl alcohol dispersant, in particular to a preparation method of a chemically modified polyvinyl alcohol dispersant used for vinyl chloride suspension polymerization. Background technique [0002] In the suspension polymerization of vinyl chloride, the most common are cellulose ethers and polyvinyl alcohol with an alcoholysis degree of more than 80 mol%. The polyvinyl chloride resin produced by this type of dispersant has a high density, but the absorption of plasticizer Low, the shape of the resin particles is not very good, and the particle shape of the resin seriously affects the processing performance. There is a need for a dispersant that achieves a balance between cold plasticizer absorption and apparent density to produce high quality PVC. The latest hot-feed process for vinyl chloride suspension polymerization also requires the use of polyvinyl alcohol with more doubl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F116/06C08F14/06C08F2/20
Inventor 卢金永卢宪
Owner TIANJIN SUNNYMER
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