KR101596277B1 - Polymerization of Fluorinated Monomers Containing Fluorinated Emulsifier and Fluorinated Polymers Thereby - Google Patents

Abstract

[상기 화학식 1에서,
R₁은 수소 또는 메틸이고,
R₂는 직쇄 또는 분쇄의 알킬(C₁-C₁₂)이며, 알킬은 헤테로시클로알킬 또는 아미노기로 더 치환될 수 있고,
n은 1 내지 5의 정수이며,
x는 몰분율로 0.05 ≤

≤ 0.99이고,
y는 몰분율로 0.01 ≤

≤ 0.60이고,
z는 몰분율로 0.01 ≤

≤0.50이다.]The present invention relates to a method of polymerizing a fluorine-based monomer containing a fluorine-based emulsifier and a fluorine-based polymer produced thereby. More particularly, the present invention relates to a method for producing a fluorinated polymer by polymerizing a fluorinated monomer, and more particularly to a water-dispersion emulsion polymerization method using a fluorinated emulsifier represented by the following formula (1).
[Chemical Formula 1]

[In the above formula (1)
R < ₁ > is hydrogen or methyl,
R ₂ is linear or branched alkyl (C ₁ -C ₁₂ ), alkyl may be further substituted with heterocycloalkyl or amino group,
n is an integer of 1 to 5,
x is a molar fraction of 0.05 <

Lt; = 0.99,
y is a molar fraction of 0.01 ≤

Lt; = 0.60,
z is the mole fraction, 0.01 ≤

≤0.50.]

Description

[0001] The present invention relates to a method for polymerizing a fluorinated monomer containing a fluorinated emulsifier, and a method for polymerizing a fluorinated polymer,

The present invention relates to a method of polymerizing a fluorine-based monomer containing a fluorine-based emulsifier and a fluorine-based polymer produced thereby. More specifically, the present invention relates to a method for producing a fluorinated polymer by using a fluorinated emulsifier containing a perfluorinated alkyl group.

The fluorine-based polymer has good physical properties such as thermal stability, chemical resistance, weather resistance, and UV stability and has been used for various industrial applications.

As the method for producing the fluorinated polymer, there are various methods such as suspension polymerization, water dispersion emulsion polymerization, solution polymerization, supercritical CO ₂ use polymerization, gas phase polymerization and the like. Among them, suspension polymerization and water dispersion emulsion polymerization are the most widely adopted polymerization methods at present.

The water-dispersion emulsion polymerization is carried out in the presence of a fluorine-based surfactant used for the purpose of stabilizing the formed polymer particles, and conventionally, perfluoroalkanoic acids or salts thereof (PFOA) . By using such a fluorine-based surfactant, a high polymerization rate, good copolymerization property with a comonomer of a fluorine-based olefin, a small particle size of a dispersion, a high polymerization yield and good dispersion stability can be obtained in the production of a fluorine-based polymer.

However, the perfluoroalkanoic acid or its salt fluorine surfactant conventionally used accumulates in the human body, causing environmental problems, and has a problem of a high price. Therefore, it is an urgent problem to develop a surfactant capable of replacing the conventional fluorine surfactant such as perfluoroalkanoic acid or a salt thereof. In particular, a new environmentally friendly surfactant having low toxicity and no accumulation of human body is required.

Alternative surfactants should have good chemical and thermal stability under a wide range of temperature and pressure conditions, and should provide a high polymerization rate, good dispersion stability, good yield and copolymer properties.

In order to achieve the above object, studies on emulsion polymerization techniques for replacing PFOA fluorine surfactants have been actively conducted.

For example, US Pat. No. 5,804,650 discloses a technique in which a fluorine-based surfactant having a double bond is used as a reactive surfactant and a monomer serves as a surfactant, but there is a problem that particles agglomerate.

In addition, US 6,878,772 discloses the use of perfluoropolyether (Bifunctional) having both substituents at both ends of a carboxylic acid substituent and a carboxylic salt substituent as surfactants, There is a problem in that the stability of the step is insufficient and it is not environmentally friendly.

Therefore, in the emulsion polymerization of a fluorine-based monomer, development of a new polymerization system using a new emulsifier that is environmentally friendly in terms of polymerization stability and environment is required.

An object of the present invention is to provide a method for polymerizing a fluorine-based monomer having excellent chemical and thermal stability, having a high polymerization rate in emulsion polymerization, excellent dispersion stability and yield, and a fluorine-based emulsifier which is easy to control the molecular weight and particle size of the fluorine- And a fluorine-based polymer produced thereby.

Another object of the present invention is to provide a method for polymerizing a fluorine-based monomer containing a novel environmentally friendly fluorine-based emulsifier having low toxicity and no accumulation of human body in the production of a fluorine-based polymer and a fluorine- will be.

Another object of the present invention is to provide a process for polymerizing an environmentally friendly fluorine-based monomer capable of easily recovering the fluorine-based emulsifier of the present invention from an aqueous solution which is a reaction medium after polymerization of a fluorine-based monomer, .

The present invention relates to a method of polymerizing a fluorine-based monomer containing a fluorine-based emulsifier and a fluorine-based polymer produced thereby.

Hereinafter, the polymerization method of the fluorine-based monomer containing the fluorine-based emulsifier of the present invention will be described in more detail.

The present invention relates to a method for polymerizing a fluorine-based monomer comprising a fluorine-based emulsifier represented by the following general formula (1).

[Chemical Formula 1]

[In the above formula (1)

R < ₁ > is hydrogen or methyl,

R ₂ is linear or branched alkyl (C ₁ -C ₁₂ ), alkyl may be further substituted with heterocycloalkyl or amino group,

n is an integer of 1 to 5,

≤ 0.99이고,x is a molar fraction of 0.05 <

Lt; = 0.99,

≤ 0.60이고,y is a molar fraction of 0.01 ≤

Lt; = 0.60,

≤0.50이다.]z is the mole fraction, 0.01 ≤

≤0.50.]

More specifically, the present invention relates to a process for preparing a fluorinated polymer, comprising at least one fluorinated emulsifier represented by the above formula (1) and subjecting at least one fluorinated monomer to water-dispersion emulsion polymerization.

The present invention relates to a fluorine-containing polymer having a high polymerization rate and excellent chemical, thermal stability and dispersion stability by using a fluorine-based emulsifier containing a perfluoro-containing monomer represented by the general formula (1) Molecular weight and particle size can be easily controlled.

Further, it is characterized by being capable of providing a fluorine-based polymer having low toxicity, no accumulation of human body, and being environmentally friendly.

Further, since the solubility of the fluorine-based emulsifier provided in the present invention is easily controlled according to the pH (pH) of the aqueous solution, the fluorine-based emulsifier can be easily recovered from the aqueous solution in which the fluorine- .

In the process for producing the fluorine-based polymer according to the present invention, the water-dispersed emulsion polymerization of the fluorine-containing monomer is initiated in the presence of the fluorine-based emulsifier according to the present invention. At this time, the fluorinated emulsifier may be commercially available or may be synthesized by a method commonly used in the art.

The fluoroelastomer according to the present invention may be a random copolymer or a block copolymer. The fluoroelastomer may be polymerized by any one of emulsion polymerization, suspension polymerization, bulk polymerization or solution polymerization, Can be used as a polymer emulsifier, and it is preferable because the additive can be removed easily by drying and washing with water.

The method for polymerizing a fluorine-based monomer containing a fluorine-based emulsifier of the present invention can produce a fluorine-based polymer including a fluorine-based monomer, a fluorine-based emulsifier represented by the following formula (1), a chain transfer agent, and an initiator.

The fluorine-based monomer that can be polymerized using the fluorine-based emulsifier according to the present invention may be at least one selected from the group consisting of tetrafluoroethylene (TFE), hexafluoropropylene (TFP), chlorotrifluoroethylene (CTFE), vinyl fluoride Perfluoroethyl vinyl ether (PPVE), perfluoroethyl vinyl ether (PEVE), perfluoromethyl vinyl ether (PMVE), purple (PDD) and perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD) selected from the group consisting of perfluoro-2,2-dimethyl-1,3-dioxole And the copolymerization of ethylene with one of the fluorine-based monomers is also possible.

The fluorinated emulsifier may be represented by the following formula (1).

[Chemical Formula 1]

[In the above formula (1)

R < ₁ > is hydrogen or methyl,

R ₂ is linear or branched alkyl (C ₁ -C ₁₂ ), alkyl may be further substituted with heterocycloalkyl or amino group,

n is an integer of 1 to 5,

≤ 0.99이고,x is a molar fraction of 0.05 <

Lt; = 0.99,

≤ 0.60이고,y is a molar fraction of 0.01 ≤

Lt; = 0.60,

≤0.50이다.]z is the mole fraction, 0.01 ≤

≤0.50.]

The fluorinated emulsifier represented by Formula 1 is a polymer of a monomer containing a hydrophilic monomer, a hydrophobic monomer, and a perfluorinated alkyl group.

The hydrophilic monomer may be, for example, acrylic acid or methacrylic acid. The content of the hydrophilic monomer may be 0.05 to 0.99, more preferably 0.20 to 0.80, in terms of the mole fraction of the entire polymer emulsifier.

Specific examples of the hydrophobic monomer include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, octadecyl methacrylate, lauryl methacrylate, dimethylaminoethyl methacrylate, Glycidyl acrylate, glycidyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 1-decyl acrylate, 1-ethylhexyl methacrylate, (Meth) acrylate monomers having a linear or branched hydrocarbon alkyl group such as 1-decyl methacrylate, lauryl acrylate or lauryl methacrylate, and may be selected from among (meth) acrylate monomers including trifluoroethyl ) Acrylate and (meth) acrylate monomers containing a linear partially fluorinated alkyl group such as W can be used, but are not necessarily limited. The content thereof may be 0.01 to 0.60, more preferably 0.01 to 0.30, in terms of the mole fraction with respect to the hull polymer emulsifier.

As the perfluoroalkyl group, for example, a (meth) acrylate monomer containing CF ₃ (CF ₂ ) _n (n = an integer of 1 to 5) group may be used, Preferably 0.01 to 0.80, more preferably 0.01 to 0.50.

The fluorinated emulsifier preferably has a weight average molecular weight of 5,000 to 500,000 g / mol in order to improve the stability of the particles and the yield of the fluorinated polymer and to facilitate recovery from the reaction medium. Further, when a fluorinated emulsifier having a too large molecular weight is used, it may not be economical because there is no additional advantage. Therefore, it is preferable to use the fluorinated emulsifier within the above range.

The content of the fluorinated emulsifier varies depending on the required properties such as the solid content and the particle size of the fluoropolymer produced, but the content of the fluorinated emulsifier varies depending on the polymerization rate and dispersion stability, the molecular weight of the polymer polymer for achieving the object of the present invention, It is preferable to use 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the fluorine-based monomer. When the fluorine-based emulsifier is added in an excess amount, the size of the produced fluorine-based polymer particles becomes finer and the viscosity of the reaction medium becomes high, so that the separation and recovery are not easy and there is no additional advantage and it may not be economical. Do.

The solubility of the fluorinated emulsifier in the reaction medium may depend on the pH during the polymerization. For example, in the case of the fluorinated emulsifier, the solubility in water used as the reaction medium in the course of polymerizing the fluorinated monomer is pH- . When the pH of the reaction medium is 5 to 10, the fluorinated emulsifier tends to dissolve in the emulsion polymerization and the pH can be easily recovered from the reaction medium after completion of the reaction. The pH of the reaction medium can be adjusted by using, for example, sodium hydroxide, potassium hydroxide, ammonia water or the like, but is not limited thereto.

The chain transfer agent of the present invention can be used in the present invention for controlling the molecular weight of the polymer produced in the water dispersion emulsion polymerization. Specific examples thereof include esters such as diethyl malonate, ethers such as dimethyl ether and methyl t-butyl ether, alkanes such as n-pentane such as ethane and propane, halogenated hydrocarbons such as carbon tetrachloride, chloroform and dichloromethane, Carbon fluoride compounds such as fluoroethane, methyl acetate, ethyl acetate, propyl acetate and butyl acetate may be used, but not always limited thereto. The content thereof is preferably 0.1 to 3 parts by weight based on 100 parts by weight of the fluorine-based monomer for controlling the molecular weight.

The initiator of the present invention can be used to initiate the free radical polymerization of the fluorine-based monomer. Suitable initiators may include peroxides, azo based compounds and liddox-based initiators. Specifically, examples of the peroxide initiator include, for example, hydrogen peroxide, sodium or barium peroxide, diacetyl peroxide, diglycinoyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoyl acetyl peroxide , Diacyl peroxide such as diglyutaric acid peroxide and dilauryl peroxide, and the like can be used. As the inorganic substance, ammonium persulfate and alkali salt persulfate can be used. The per sulfate initiator such as ammonium ammonium persulfate may be used alone or in combination with other reducing agents. Suitable reducing agents include, but are not necessarily limited to, ammonia bisulfite or sodium sulfite, such as sodium methabisulfite, ammonia, potash, sodium, and the like. The content thereof is preferably 0.001 to 1 part by weight based on 100 parts by weight of the fluorine-based monomer in order to initiate free radical polymerization.

In the process for preparing a fluorinated polymer according to the present invention, it is preferable that the above water-dispersion emulsion polymerization is carried out at a temperature of 20 to 110 ° C and a pressure of 5 to 80 bar to easily control the weight average molecular weight and the particle size Which is preferable in the following.

The fluoropolymer prepared by the process of the present invention has a solids content of 10 to 35%, an average diameter of 50 to 500 nm and a weight average molecular weight of 50,000 to 800,000 g / mol.

The process for recovering the fluorinated emulsifier represented by the above formula (1) of the present invention is also included in the scope of the present invention.

The polymer of the fluorine-based monomer produced by the emulsion polymerization using the fluorine-based emulsifier of the present invention may be separated from the aqueous phase as a reaction medium and used as a powder after drying if necessary. In order to recover the fluorinated emulsifier from the aqueous phase from which the polymer of the fluorinated monomer is removed, the pH of the aqueous phase may be adjusted to 4 or lower, preferably 1 to 4, and the pH of the aqueous phase may be adjusted to the above- Sulfuric acid, and the like can be used, but the present invention is not limited thereto.

The fluorine-based emulsifier of the present invention satisfies all the requirements as a fluorine-based emulsifier that can replace conventional perfluoroalkanoic acid (PFOA) or its salt (APFO) and satisfies all of the requirements of fluorine-based monomers as well as water- Can be usefully used.

Further, in the present invention, it is possible to have excellent polymerization rate, dispersion stability and yield in emulsion polymerization using a fluorine-based emulsifier, and to easily control the molecular weight and particle size of the polymer.

In addition, the fluoropolymer produced by the present invention has low toxicity, has no human accumulation, and is environmentally friendly.

Further, the fluorinated emulsifier used in the present invention can be simply recovered by adjusting the pH of the aqueous solution to 4 or less.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the molecular weights according to the polymers of Examples and Comparative Examples of the present invention. Fig.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

The embodiments described below are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. It will be apparent to those skilled in the art that, unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, And a description of the known function and configuration will be omitted.

The following physical properties were measured by the following methods.

1) Molecular weight

The weight average molecular weight and the polydispersity index (PDI) of the fluorinated polymer prepared by the polymer emulsifier and the emulsion polymerization were measured by gel permeation chromatography (GPC, Waters 2690). Dimethylacetoamide (DMAc) was used as mobile phase at room temperature and measured by RI detector. The molecular weight standard curve was prepared using monodispersed polystyrene.

2) Particle size

The particle size of the fluoropolymer prepared by emulsion polymerization was measured by observing the dried particles with a scanning electron microscope (Tescan VEGA II LSU).

3) Solids

After the polymerization, a certain amount of reactants were collected and dried in an oven at 120 ° C for 24 hours, and the mass before and after drying was measured to determine the solid content.

4) ¹ H-NMR

The chemical composition of the polymer emulsifier was measured by ¹ H-NMR (Bruker DRX-300 FT-NMR) using DMSO-d6 as a solvent.

5) Melting point

The thermal properties of the dried samples were measured by differential scanning calorimetry (TA Instruments, DSC2910).

[Example 1]

In a 1 L reaction vessel equipped with a stirrer and a condenser, 390 g of distilled water, 0.1 g of sodium hydrogencarbonate and 0.5 g of sodium lauryl sulfate were added, and the temperature of the reaction was raised to 75 캜 using a circulating thermostat. 20 g of a monomer mixture composed of 40 g of methacrylic acid, 40 g of trifluoroethylmethacrylate, 20 g of tridecafluoroethylmethacrylate and 0.3 g of 1-octanethiol was added and stirred at a stirring speed of 250 rpm for 20 minutes Respectively. 0.5 g of sodium persulfate dissolved in 10 g of distilled water was charged into the reactor to initiate polymerization of the monomers. 30 minutes after the initiation of the reaction, the remaining monomer mixture was continuously fed at a flow rate of 30 ml per hour. After completion of the monomer addition, the reaction was continued for 2 hours to complete the synthesis of the fluorinated emulsifier.

After the temperature of the reaction mixture was cooled to room temperature, 1 L of a distilled water solution in which 15 g of sodium hydroxide had been dissolved was mixed with the reaction mixture to completely dissolve the resulting fluorinated emulsifier particles. The resultant mixture was slowly dissolved in 1.5 L of a distilled water solution containing 20 g of hydrochloric acid To form a precipitate of a fluorine-based emulsifier. The formed precipitate was separated by filtration, washed several times with distilled water, and dried at a temperature of 60 ° C and a reduced pressure to recover the final fluorinated emulsifier. The final yield of the fluorinated emulsifier was 98.7% of the monomer used in the reaction and the weight average molecular weight measured by GPC was 55,000 g / mol. The chemical composition of the fluorinated emulsifier (FASP) was determined by ¹ H-NMR and found to be 0.653 mole fraction of methacrylic acid, 0.306 mole fraction of trifluoroethylmethacrylate, and 0.041 mole fraction of tridecafluoroethylmethacrylate.

Thereafter, a high-pressure reactor of a stainless steel material with a magnetic drive was used for the emulsion polymerization of the fluorine-based monomer. The temperature inside the reactor was controlled by supplying a heating medium to the reactor jacket using a circulating thermostat outside the reactor. After 300 g of distilled water as a dispersion medium, 0.5 g of a fluorinated emulsifier (FASP) and 1 g of ethyl acetate (EA) were added into the reactor, nitrogen was purged several times to remove oxygen, 50 g of vinylidene fluoride (VDF) Lt; RTI ID = 0.0 > 82 C. < / RTI > The reaction was initiated by adding 1 g of sodium persulfate dissolved in a small amount of distilled water, and 60 g of vinylidene fluoride was continuously added to maintain the pressure in the reactor at 20 atm or more. After addition of the specified amount of monomer, the reaction was further terminated by reacting for 30 minutes and discharging unreacted monomer. The results are shown in Table 1.

Sodium chloride was added to an aqueous dispersion of a certain amount of vinylidene fluoride polymer to induce aggregation of the polymer particles, followed by separation of the polymer using a filtration apparatus. Aqueous hydrochloric acid solution was added to the resulting filtrate to maintain a pH of 3 to obtain a white precipitate of the fluorinated emulsifier. After filtration, the mass of the filtrate was measured and the recovery rate of the fluorinated emulsifier was measured. The results are shown in Table 1 .

[Examples 2 to 12]

Experiments were carried out in the same manner as in Example 1 except that the amounts of the monomers, the fluorinated emulsifiers and the ethyl acetate were changed in Example 1, and the results are shown in Table 1.

[Comparative Example 1]

For the emulsion polymerization of the fluorinated monomers, a stainless steel high pressure reactor with a magnetic drive was used. The temperature inside the reactor was controlled by supplying a heating medium to the reactor jacket using a circulating thermostat outside the reactor. In the reactor, 300 g of distilled water as a dispersion medium, 0.7 g of an emulsifier (ammonium salt of ammonium perfluoroalkanoate: ammonium pentadecafluorooctanoate: APFO) and 0.01 g of ethyl acetate were added, and nitrogen was purged several times to remove oxygen After the addition of 50 g of vinylidene fluoride, the temperature of the reaction product was raised to 82 ° C. The reaction was initiated by the addition of 0.56 g of sodium persulfate dissolved in a small amount of distilled water, and 75 g of vinylidene fluoride was continuously introduced to maintain the pressure in the reactor at 20 atm or more. The reaction was terminated by additionally reacting the unreacted monomer for 30 minutes after a predetermined amount of the monomer was added, and the results are shown in Table 2.

Sodium chloride was added to an aqueous dispersion of a certain amount of vinylidene fluoride polymer to induce aggregation of the polymer particles, followed by separation of the polymer using a filtration apparatus. An aqueous hydrochloric acid solution was added to the resulting clear filtrate to maintain the pH at 3, but it was impossible to obtain an emulsifier.

[Comparative Examples 2 to 4]

Experiments were carried out in the same manner as in Comparative Example 1 except that the amount of ethyl acetate was changed in order to control the molecular weight of the polymer in Comparative Example 1. The results are shown in Table 2.

[Comparative Example 5]

A stainless steel high pressure reactor equipped with a magnetic drive was used, and a circulating chamber was used outside the reactor to supply a heating medium to the reactor jacket to regulate the temperature in the reactor. 300 g of distilled water as a dispersing medium, 0.5 g of an emulsifier (sodium salt of polymethyl methacrylic acid: PMAA) and 0.1 g of ethyl acetate were put into the reactor, and then nitrogen was purged several times to remove oxygen, followed by addition of 50 g of vinylidene fluoride The temperature of the reaction product was raised to 82 占 폚. The reaction was started by adding 1 g of sodium persulfate dissolved in a small amount of distilled water, and 50 g of vinylidene fluoride was continuously introduced to maintain the pressure in the reactor at 20 atm or more. After addition of the specified amount of monomer, the reaction was further terminated by reacting for 30 minutes and discharging unreacted monomer. The results are shown in Table 3.

Sodium chloride was added to an aqueous dispersion of a certain amount of vinylidene fluoride polymer to induce aggregation of the polymer particles, followed by separation of the polymer using a filtration apparatus. An aqueous hydrochloric acid solution was added to the resulting clear filtrate to maintain the pH at 3, but it was impossible to obtain an emulsifier. In the case of PMAA, precipitates of emulsifier can be obtained by adding an aqueous calcium solution, but it is not preferable because precipitation is incomplete and secondary water pollution occurs.

[Comparative Examples 6 to 9]

The experiment was carried out in the same manner as in Comparative Example 1 except that the amount of ethyl acetate was changed to control the molecular weight of the polymer in Comparative Example 5. The results are shown in Table 3.

[Comparative Example 10]

In a 1 L reaction vessel equipped with a stirrer and a condenser, 390 g of distilled water, 0.1 g of sodium hydrogencarbonate and 0.5 g of sodium lauryl sulfate were added, and the temperature of the reaction was raised to 75 캜 using a circulating thermostat. 20 g of a monomer mixture composed of 40 g of methacrylic acid, 40 g of methyl methacrylate, 20 g of butyl methacrylate and 0.3 g of 1-octanethiol was added and stirred at a stirring speed of 250 rpm for 20 minutes. 0.5 g of sodium persulfate dissolved in 10 g of distilled water was charged into the reactor to initiate polymerization of the monomers. After 30 minutes from the initiation of the reaction, the remaining monomer mixture was continuously fed at a flow rate of 30 ml per hour. After completion of the monomer addition, the reaction was continued for 2 hours to complete the synthesis of the hydrocarbon-based polymer emulsifier.

After the temperature of the reaction mixture was cooled to room temperature, 1 L of a distilled water solution in which 15 g of sodium hydroxide had been dissolved was mixed with the reaction mixture to completely dissolve the resulting hydrocarbon emulsifier particles. Then, 1.5 L of a distilled water solution containing 20 g of hydrochloric acid Slowly added to form a precipitate of emulsifier. The formed precipitate was separated by filtration, washed several times with distilled water, and dried at a temperature of 60 ° C and a reduced pressure to recover the final hydrocarbon emulsifier. The final yield of the hydrocarbon emulsifier was 99.1% based on the monomer used in the reaction, and the weight average molecular weight measured by GPC was 27,000 g / mol. The chemical composition of the hydrocarbon-based emulsifier (ASP) was determined by ¹ H-NMR and found to be 0.284 mole fraction of methacrylic acid, 0.529 mole fraction of methyl methacrylate, and 0.187 mole fraction of butyl methacrylate.

Thereafter, a stainless steel high-pressure reactor equipped with a magnetic drive was used, and a heating medium was supplied to the reactor jacket by using a circulating thermostat outside the reactor to regulate the temperature in the reactor. 300 g of distilled water as a dispersing medium, 0.5 g of the prepared hydrocarbon emulsifier (ASP) and 0.1 g of ethyl acetate were put into the reactor, and nitrogen was purged several times to remove oxygen. Then, 50 g of vinylidene fluoride was added thereto, The temperature was raised to 82 占 폚. The reaction was started by adding 1 g of sodium persulfate dissolved in a small amount of distilled water, and 50 g of vinylidene fluoride was continuously introduced to maintain the pressure in the reactor at 20 atm or more. After a predetermined amount of the monomer was added, the reaction was further terminated for 30 minutes and the unreacted monomer was discharged to terminate the reaction. Sodium chloride was added to an aqueous dispersion of a certain amount of vinylidene fluoride polymer to induce aggregation of the polymer particles, followed by separation of the polymer using a filtration apparatus. Aqueous hydrochloric acid solution was added to the resulting filtrate to maintain a pH of 3 to obtain a white precipitate of the emulsifier. The precipitate was filtered, and the mass was measured after drying to measure the recovery of the emulsifier. The results are shown in Table 4.

[Comparative Examples 11 to 13]

Experiments were carried out in the same manner as in Comparative Example 10, except that the amount of ethyl acetate was changed in order to control the molecular weight of the polymer in Comparative Example 10. The results are shown in Table 4.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

As shown in Tables 1 to 4, the results of emulsion polymerization of vinylidene fluoride (VDF) using FASP, which is a fluorine-based emulsifier containing a perfluoroalkyl group, are similar to those of the conventional emulsifier APFO FASP, which is a fluorinated emulsifier containing a perfluoroalkyl group, can be easily recovered by adjusting the pH of an aqueous solution.

Particularly, in the case of using ethyl acetate (EA) as a chain transfer agent to control the molecular weight of VDF polymer, FASP shows almost the same tendency as APFO, whereas in the comparative example using a polymer emulsifier not containing perfluoroalkyl group, It can be seen that the high molecular weight VDF polymer of 300,000 g / mol or more can not be obtained.

It is therefore evident that the ability to substantially replace APFO is a fluorinated emulsifier containing a perfluoroalkyl group in the molecular structure.

Claims (10)

A method for polymerizing a fluorine-based monomer comprising a fluorine-based emulsifier represented by the following formula (1), further comprising the step of recovering the fluorine-containing emulsifier represented by the above formula (1), wherein the pH of the aqueous solution from which the polymerized fluorine- By weight based on the weight of the fluorine-containing monomer.
[Chemical Formula 1]

[In the above formula (1)
R < ₁ > is hydrogen or methyl,
R ₂ is linear or branched alkyl (C ₁ -C ₁₂ ), or linear partially fluorinated alkyl,
n is an integer of 1 to 5,
x is a molar fraction of 0.20 <

Lt; = 0.80,
y is a molar fraction of 0.01 ≤

Lt; = 0.60,
z is the mole fraction, 0.01 ≤

≤0.50.] The method according to claim 1,
A method for polymerizing a fluorine-based monomer comprising a fluorine-based emulsifier, a chain transfer agent, a fluorine-based monomer and an initiator represented by the above formula (1). The method according to claim 1,
Wherein the fluorine-based emulsifier has a weight average molecular weight of 5,000 to 500,000 g / mol. 3. The method of claim 2,
Wherein the fluorine-based monomer is contained in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of the fluorine-based monomer. 3. The method of claim 2,
Wherein the chain transfer agent is selected from the group consisting of esters, ethers, alkanes, halogenated hydrocarbons and carbon fluoride compounds. 3. The method of claim 2,
The fluorine-based monomer may be at least one selected from the group consisting of vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinyl fluoride, trifluoroethylene, hexafluoroisobutylene, perfluorobutyl ethylene, perfluoro Propyl vinyl ether, perfluoroethyl vinyl ether, perfluoromethyl vinyl ether, perfluoro-2,2-dimethyl-1,3-dioxol and perfluoro-2-methylene- - dioxolane is used as the polymerization initiator. 3. The method of claim 2,
Wherein the initiator is one or more selected from the group consisting of a riddox initiator, a peroxide, and an azo compound. delete delete delete

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