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A kind of aqueous emulsion polymerization method for preparing fusible fluorine-containing polymer

A polymerization method and water-emulsion technology, applied in the field of fluorine-containing polymer synthesis, can solve the problems of large dosage, poor water solubility, low activity, etc., and achieve the effect of no discoloration of volatile content and low volatile content

Active Publication Date: 2017-09-22
ZHEJIANG XINGTENG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this type of hydrofluorocarbon chain transfer agent has very poor water solubility, so the activity is quite low, the dosage is relatively large, and the industrial application value is low

Method used

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  • A kind of aqueous emulsion polymerization method for preparing fusible fluorine-containing polymer

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 3.8 L of deionized water and 12 ml of 40% perfluorooctanoic acid ammonium salt (PFOA) were added to a polymerization kettle with a total volume of 6.0 L and equipped with an impeller agitator system. Then the reactor was evacuated and replaced until the oxygen content was less than 28ppm. Then, 600 g of TFE and FEP mixed monomers were initially put into the reactor, wherein the mass proportion of TFE was 25%. Raise the temperature of the reactor to 98-100°C, inject 30ml of ammonium persulfate with a concentration of 2.5% at a rate of 2.3ml / min as an initial initiator, and inject a mixture of 0.01 % concentration perfluorohexyl ammonium acetate chain transfer agent ammonium persulfate initiator, and additional reaction monomer, control the pressure in the reactor to about 3.5mpa. After feeding 1.3kg of TFE monomer, stop the feeding of initiator and chain transfer agent. Maintain the pressure of the reactor and add additional reaction monomers, stop the reaction after 4...

Embodiment 2-4

[0032] In embodiment 2,3 and 4, polymer is prepared according to the method of embodiment 1, difference is to change the amount of perfluorohexyl ammonium acetate chain transfer agent, polymer is analyzed in the same way as embodiment 1, the result Listed in Table 1

[0033] Table 1

[0034]

[0035] According to the above chart, it can be seen that increasing the amount of chain transfer agent increases the chain transfer efficiency and affects the polymerization reaction speed, and the low molecular weight directly leads to a sharp increase in the melt index, and also reduces the mechanical strength of the polymer to a certain extent. , Therefore, generally preferred chain transfer agent dosage is 0.5 ~ 2g / kg polymer.

Embodiment 5

[0037] 3.8 L of deionized water was added to a polymerization tank with a total volume of 6.0 L and equipped with an impeller agitator system, and 12 ml of 40% perfluorooctanoic acid ammonium salt (PFOA) was added, and then the reactor was evacuated and replaced until the oxygen content was less than 28 ppm. . Add 50ml of PPVE and 1g of perfluorohexyl ammonium acetate, raise the temperature to 65°C, then put TFE monomer into the reactor to 0.5MPa, then pump 30ml of ammonium persulfate with a concentration of 2.5% at a speed of 2.3ml / min As the initial initiator, the polymerization starts the reaction. During the reaction period, add TFE monomer, control the pressure in the reactor to about 0.5-0.6MPa, and continue to add ammonium persulfate initiator at a speed of 1.5ml / min. After the additional polymerization is completed, the stirring is stopped, and the remaining monomers in the kettle are recovered. After the reaction kettle was under normal pressure, 3.1 kg of PFA dispe...

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Abstract

The invention discloses a water emulsion polymerization method for preparing a meltable fluorine-containing polymer. The method includes: using all-fluorine alkyl acetate as a chain transfer agent to adjust polymerization, wherein a general formula of all-fluorine alkyl acetate is CF3(CF2)nCH2COOX, n is an integer between 0 and 6, X is metal or nonmetal ion, and the chain transfer reaction process is CF3(CF2)nCH2COO-+R-CF2-CF2 to R-CF2-CF2H+CF3(CF2)nCH COO-.The meltable fluorine-containing polymer prepared by the method is excellent in mechanical performance and molecular weight distribution and has the advantages of low volatile and no color change.

Description

technical field [0001] The invention relates to the technical field of synthesis of fluorine-containing polymers, in particular to using specific perfluoroalkyl acetates as chain transfer agents in aqueous emulsion polymerization to prepare fusible fluorine-containing polymers with improved properties. Background technique [0002] Fluoropolymers have long been known and have been used in various fields due to their various desirable properties such as heat resistance, weather resistance, corrosion resistance, UV stability, and the like. The present invention mainly studies fusible fluoropolymers, including PTFE, FEP, ETFE, PVDF, and PFA. [0003] Most of the molecular weight of fusible fluoropolymers is difficult to control. At present, it is generally controlled by adding chain transfer agents. It is reported that R32, hydrogen and other gases are used as chain transfer agents to control the molecular weight of polymers. However, this type of chain Because the transfer ag...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F2/38C08F2/26C08F214/26C08F214/28C08F114/26
CPCC08F2/26C08F2/38C08F114/26C08F214/26C08F214/28
Inventor 龚元庞叶红亮鲁红玉赵景平洪海江吴宏俊张璐
Owner ZHEJIANG XINGTENG CHEM
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