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Polyvinyl alcohol with high polymerization degree and high syndiotacticity, and preparation method thereof

A technology of high degree of polymerization and polyvinyl alcohol, which is applied in the field of high degree of polymerization and high syndiotacticity polyvinyl alcohol and its preparation, can solve the problems of difficulty in obtaining fibers, small steric hindrance of side groups, and low melting point, etc. The effect of high conversion rate, simple process and easy control

Active Publication Date: 2020-12-11
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the small molecular weight of VAc, active reactivity, and small steric hindrance of side groups, the degree of polymerization and syndiotacticity of the synthesized PVA is not high. The degree of polymerization is generally 1700-3500, and the syndiotacticity is generally 48-48 51%
[0003] Due to the low degree of polymerization and syndiotacticity of PVA produced by the prior art, this will not only limit the orientation and crystallization of macromolecules during fiber formation, thereby affecting the strength and modulus of PVA fibers, as well as the acid and alkali corrosion resistance and weather resistance of the fibers. Etc performance
Moreover, because the melting point of PVA with low degree of polymerization and low syndiotacticity is not high, it is difficult to obtain a higher melting point for the prepared fiber.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030]A method for preparing polyvinyl alcohol with high degree of polymerization and high syndiotacticity adopts an emulsion polymerization method and includes the following steps:

[0031](1) The molar ratio of VBz, VAc and VPi monomers with a molar ratio of 20:39:41, initiator (ie a mixture of KPS and DMEA with a molar ratio of 5.0:2.0), the molar ratio of the total amount of monomers to the initiator 100:0.6, emulsifier (ie a mixture of SDS and OP-10 with a molar ratio of 5.0:1.0), the molar ratio of the total amount of monomer to the emulsifier is 100:1.5, put it into a three-necked flask, and nitrogen at 25℃ The reaction is carried out in an atmosphere (time is 6.5h); then excess n-hexane is used to remove the remaining monomers in the reaction product, and the product is dried at 75℃ for 16h to obtain PVBz-co-PVAc-co-PVPi prepolymer ;

[0032](2) Dissolve the PVBz-co-PVAc-co-PVPi prepolymer in methanol to obtain a PVBz-co-PVAc-co-PVPi / methanol solution with a mass concentration of ...

Embodiment 2

[0039]A method for preparing polyvinyl alcohol with high degree of polymerization and high syndiotacticity adopts an emulsion polymerization method and includes the following steps:

[0040] (1) The molar ratio of VBz, VAc and VPi monomers with a molar ratio of 20:45:35, initiator (ie a mixture of KPS and DMEA with a molar ratio of 5.0:2.5), the molar ratio of the total amount of monomers to the initiator It is 100:0.5, emulsifier (that is, the molar ratio of 5.0:1.0 is a mixture of SDS and OP-10), the molar ratio of the total amount of monomer to the emulsifier is 100:1.5, add it to a three-necked flask, and nitrogen at 30℃ The reaction is carried out in an atmosphere (time of 6.5h); then excess n-hexane is used to remove the remaining monomers in the reaction product, and dried at 80℃ for 19h to obtain PVBz-co-PVAc-co-PVPi prepolymer ;

[0041](2) Dissolve PVBz-co-PVAc-co-PVPi prepolymer in methanol to obtain a PVBz-co-PVAc-co-PVPi / methanol solution with a mass concentration of 9.0 wt%;...

Embodiment 3

[0044]A method for preparing polyvinyl alcohol with high degree of polymerization and high syndiotacticity adopts an emulsion polymerization method and includes the following steps:

[0045](1) The molar ratio of VBz, VAc and VPi monomers with a molar ratio of 20:30:50, initiator (ie a mixture of KPS and DMEA with a molar ratio of 5:3), the molar ratio of the total amount of monomers to the initiator 100:0.4, emulsifier (that is, a mixture of SDS and OP-10 with a molar ratio of 5.0:2.0), the molar ratio of the total amount of monomer to the emulsifier is 100:1.0, put it into a three-necked flask and place it in a carbon dioxide atmosphere at 20°C The reaction is carried out under pressure (8h); then excess n-hexane is used to remove the remaining monomers in the reaction product, and dried at a temperature of 68℃ for 12h to obtain PVBz-co-PVAc-co-PVPi prepolymer;

[0046](2) Dissolve PVBz-co-PVAc-co-PVPi prepolymer in methanol to obtain a PVBz-co-PVAc-co-PVPi / methanol solution with a mass...

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Abstract

The invention relates to polyvinyl alcohol with high polymerization degree and high syndiotacticity, and a preparation method thereof. The preparation method comprises the following steps: (1) carrying out emulsion polymerization on three monomers, namely VBz, VAc and VPi, and an initiator under a certain condition to obtain a prepolymer PVBz-co-PVAc-co-PVPi; wherein the initiator is a mixture ofpotassium persulfate and N,N-dimethylethanolamine, and the emulsifier in the emulsion polymerization is a mixed solution of lauryl sodium sulfate and polyoxyethylene octylphenol ether-10; (2) dissolving PVBz-co-PVAc-co-PVPi in methanol to obtain a PVBz-co-PVAc-co-PVPi / methanol solution; and (3) slowly adding a NaOH / methanol solution with a certain concentration into the PVBz-co-PVAc-co-PVPi / methanol solution, stirring while adding until a product appears, and standing for reaction to obtain the polyvinyl alcohol with high polymerization degree and high syndiotacticity, wherein the polymerization degree of the prepared polyvinyl alcohol is 9000-21000, the syndiotacticity is 54-65%, and the melting point is 237-256 DEG C. According to the invention, the method can selectively change the monomer ratio to synthesize the required polyvinyl alcohol with high polymerization degree and high syndiotacticity, and has the characteristics of simple process, easiness in control, environment friendliness and high conversion rate.

Description

Technical field[0001]The technical field of synthesis of polyvinyl alcohol (PVA) to which the present invention belongs relates to a polyvinyl alcohol with high polymerization degree and syndiotacticity and a preparation method thereof.Background technique[0002]The currently prepared high-strength and high-modulus polyvinyl alcohol (PVA) fibers mainly use ordinary PVA polymers as raw materials. This polymer is mainly synthesized with cheap and easily available vinyl acetate (VAc) as the monomer. Because the VAc monomer has a small molecular weight, The reaction properties are more active. A variety of polymerization methods can be used to prepare the PVAc of the PVA prepolymer, and then the NaOH / methanol solution can be used as a catalyst for alcoholysis to prepare the PVA polymer. However, due to the small molecular weight of VAc, active reaction properties, and low steric hindrance of the side groups, the synthesized PVA has a low degree of polymerization and syndiotacticity. The ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F218/10C08F218/08C08F8/00
CPCC08F8/00C08F218/08C08F218/10
Inventor 邹黎明王华君李文刚吴迪王艳丽孙晨凯王超何钧炜
Owner DONGHUA UNIV