KR20120060445A - Aqueous Emulsion Polymerization of Fluorinated Monomers Containing Vinylidene Fluoride Using Fluorinated Surfactants of Fluorosulfonates - Google Patents

Abstract

PURPOSE: A water-dispersible emulsion polymerization method of a vinylidene fluoride-containing fluorine based monomer is provided to simplify post-treatment process by using a surfactant hardly accumulated in human body with low toxicity, and to obtain high polymerization rate, and moderate dispersion stability and yield. CONSTITUTION: A polymerization method of a fluorine based monomer comprises a step of polymerizing one or more kinds of fluorine based water-dispersible emulsion monomers by using a fluorosulfonate-based surfactant in chemical formula 1: RfX(CH2)nSO3M. In chemical formula 1, Rf is CF3 or C2F5, X is O, C6H4O, or CF3N, M is metallic ion, and n is an integer from 4-12. The fluorine based monomer is vinylidene fluoride, or a mixture in which one or more kinds selected from the vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, and vinyl fluoride are mixed.

Description

Aqueous Emulsion Polymerization of Fluorinated Monomers Containing Vinylidene Fluoride Using Fluorinated Surfactants of Fluorosulfonates}

The present invention relates to a method for producing a fluorine-based polymer by polymerizing a fluorine-based monomer containing vinylidene fluoride (VDF), and more particularly, to an aqueous emulsion polymerization method using an environmentally friendly fluorine-based surfactant.

Fluorine-based polymers have been used industrially for various purposes because they have good physical properties such as thermal stability, chemical resistance, weather resistance, UV stability, and the like.

There are various methods for producing the fluorine-based polymer, such as suspension polymerization, water dispersion emulsion polymerization, solution polymerization, supercritical CO ₂ polymerization, gas phase polymerization and the like. Among these, the most commonly adopted polymerization methods are suspension polymerization and water emulsion emulsion polymerization.

The aqueous dispersion emulsion polymerization is polymerized in the presence of a fluorine-based surfactant used for stabilizing the polymer particles formed, and conventionally perfluoroalkanoic acids or salts thereof (PFOA) as such surfactant Was carried out. By using such a fluorine-based surfactant, it is possible to obtain high polymerization rate, good copolymerization properties of fluorinated olefins with comonomers, small particle size of dispersion, high polymerization yield, good dispersion stability, etc. in the production of fluorine-based polymers.

However, conventionally used fluorine-based surfactants of perfluoroalkanoic acid or salts thereof (PFOA) accumulate in the human body and cause environmental problems, and there is a high price problem. Therefore, it is necessary to find a surfactant that can replace a fluorine-based surfactant such as a conventional perfluoroalkanoic acid or a salt thereof (PFOA). In particular, new environmentally friendly surfactants with low toxicity and little human accumulation should be found.

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

In order to achieve this purpose, the recent research on emulsion polymerization technology to replace the PFOA fluorine-based surfactants is very active. Looking at the conventional studies are as follows.

First, US 3,271,341 discloses perfluoropolyethers of formula A in place of PFOA as novel surfactants used in the preparation of aqueous colloidal polymer dispersions.

[Formula A]

F- (CF ₂ ) _m -O- [CFX-CF ₂ -O} _n -CFX-COOA

(A = cation, X = F or CF ₃ , m = 1-5, n = 0-10)

Next, US Pat. No. 4,621,116 discloses a process for the preparation of copolymers of tetrafluoroethylene in the presence of fluorine-based surfactants of perfluoroalkoxy benzene sulphonic acids and salts of the general formula (B).

[Formula B]

(R _f = perfluoroalkyl group, M = cation)

Next, US 4,990,283 discloses microemulsions in which perfluoropolyether (PFPE) is emulsified using perfluoropolyether carboxylic acid. Techniques for utilizing this microemulsion for emulsion polymerization of various fluorine-based polymers are disclosed in US 4,789,717, US 4,864,006, US 7,122,608, EP 624426 and the like.

Next, US Pat. No. 5,804,650 discloses a technique of using a fluorine-based surfactant having a double bond of any one of Formulas C to H as a reactive surfactant.

[Formula C]

CF ₂ = CF- (CF ₂ ) _a -Y

(a = 1-10, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

[Formula D]

CF ₂ = CF- (CF ₂ CFX) _b -Y

(X = F or CF ₃ , b = 1-5, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

[Formula E]

CF ₂ = CF-O- (CFX) _c -Y

(X = F or CF ₃ , c = 1-10, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

Formula F]

CF ₂ = CF-O- (CF ₂ CFXO) _d -CF ₂ CF ₂ -Y

(X = F or CF ₃ , d = 1-10, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

[Formula G]

CH ₂ = CFCF ₂ -O- (CF (CF ₃ ) CF ₂ O) _e -CF (CF ₃ ) -Y

(e = 0-10, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

[Formula H]

CF ₂ = CFCF ₂ -O- (CF (CF ₃ ) CF ₂ O) _f -CF (CF ₃ ) -Y

(f = 1-10, Y = SO ₃ M or COOM, M = H, NH ₄ or alkali metal)

Next, EP 1,334,996 and US Pat. No. 6,878,772 show the use of a perfluoropolyether (bifunctional) having two substituents of a carboxylic acid substituent and a carboxylic salt substituent of the formula (I) at the same time in the sock end as a surfactant. .

[Formula I]

AR _f -B

(R _f = perfluoroalkyl group, A and B =-(O) _p CFX-COOM, M = NH ₄ , H or alkali metal, X = F or CF ₃ , p = 0 or 1)

Next, US 7,659,333 is filed with a fluorine-based surfactant of formula (J).

[Formula J]

[R _f- (O) _t -CQH-CF ₂ -O] _n -RG

(R _f = Fluorine-based aliphatic group containing at least one oxygen atom, Q = CF ₃ or F, R is an aliphatic or aromatic hydrocarbon group, G is a carboxylic or sulfonic acid or salt thereof, t is 0 or 1, n is 1- 3, MW <500)

Next, in JP 2008-297528 and JP 2008-297529, a technique of using a non-fluorine-based surfactant or a malonic acid or an ester without using a fluorine-based surfactant is proposed.

However, there is still a need for a method for producing a fluorine-based polymer using a new environmentally friendly surfactant having low toxicity and little human accumulation.

Accordingly, an object of the present invention is to provide an emulsion polymerization method characterized by using a new environmentally friendly fluorine-based surfactant having low toxicity and little human accumulation in the production of fluorine-based polymers by polymerization of vinylidene-containing fluorine-based monomers. This new surfactant has good chemical and thermal stability, provides high polymerization rate, good dispersion stability and good yield in emulsion polymerization and provides a fluorine-based polymer having good physical properties such as molecular weight and particle size.

In order to achieve the above object, the present invention is a method for producing a fluorine-based polymer comprising the step of polymerizing one or more fluorine-based monomers by water dispersion emulsion using at least one fluorosulfonate-based surfactant represented by the formula (1) To provide.

[Formula 1]

.

.

(In Formula 1, R _f = CF ₃ or C ₂ F ₅ , X = O, C ₆ H ₄ O or CF ₃ N, M = metal ions, n = 4-12)

The fluorosulfonate-based surfactant according to the present invention has little human accumulation and is safe because it is low toxicity. Accordingly, the post-treatment process is simplified compared to the conventional PFOA surfactant use process, thereby reducing the production cost, and high polymerization during emulsion polymerization. Providing speed, good dispersion stability and good yields, the fluorine-based polymers produced exhibit good molecular weight and particle size. As such, the fluorosulfonate-based surfactant according to the present invention satisfies all of the requirements as a fluorine-based surfactant that can replace the above-mentioned perfluoroalkanoic acid or salt (PFOA). The monomers are of course suitable for the dispersion emulsion polymerization of vinyl fluoride-containing fluorinated monomer mixtures.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention provides a method for preparing a fluorine-based polymer comprising the step of polymerizing one or more fluorine-based monomers by water dispersion emulsion using at least one fluorosulfonate-based surfactant represented by the following formula (1).

(In the formula 1,

R _f is CF ₃ or C ₂ F ₅ ,

X is O, C ₆ H ₄ O or CF ₃ N,

M is a metal ion,

n is an integer of 4-12.)

Preferably, M is an ion of sodium, potassium, ammonium or the like.

In the method for producing a fluorine-based polymer according to the present invention, water dispersion emulsion polymerization of the fluorine-based monomer is initiated in the presence of a fluorosulfonate-based surfactant according to the present invention. In this case, the fluorosulfonate-based surfactant may be commercially available, or may be synthesized by a method commonly used in the art.

In the method for producing a fluorine-based polymer according to the present invention, the amount of the fluorosulfonate-based surfactant to be used depends on the required physical properties such as the solid content and particle size of the prepared fluorine-based polymer, but for the good physical properties of the fluorine-based polymer It is preferably 0.01 to 2% by weight based on the amount of polymer.

In the method for producing a fluorine-based polymer according to the present invention, the fluorosulfonate-based surfactant may be used alone or in combination with one or more other perfluoropolyether-based fluorine-based surfactants.

At this time, the preferred perfluoropolyether-based fluorine-based surfactant may be selected from the group consisting of the compound of formula 2 to formula 4.

(In Formula 2,

n is an integer from 1 to 6,

X is -COOH or -COOM (M = Na, K or NH ₄ )

(3)

m is an integer of 0 to 3,

L is -CF (CF ₃ )-, -CF _2- , or -CF ₂ CF _2- ,

X is -COOH or -COOM (M = Na, K or NH ₄ )

(In Formula 4,

R _f ′ is a C ₁ -C ₄ straight or branched perfluoroalkyl group,

X is -COOH or -COOM (M = Na, K or NH ₄ )

In this case, the mixing ratio of the fluorosulfonate-based surfactant represented by Formula 1 with the perfluoropolyether-based fluorine-based surfactant is preferably 1:10 to 10: 1 by weight.

In the method for producing a fluorine-based polymer according to the present invention, the water dispersion emulsion polymerization is preferably carried out in a temperature range of 20 ~ 110 ℃ and a pressure range of 5 ~ 20 bar. In addition, the pH of the reactant for emulsion polymerization is preferably 5-10.

In the method for producing a fluorine-based polymer according to the present invention, the aqueous dispersion emulsion polymerization may use an initiator to initiate free radical polymerization of the fluorine-based monomer. Suitable initiators can include peroxides, azo compounds, and redox based initiators. Examples of peroxide initiators include hydrogen peroxide, sodium or barium peroxide, diacetyl peroxide, disuccinyl peroxide. Dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoylacetyl peroxide, digglutaric acid peroxide, diacyl peroxide such as dilauryl peroxide and the like. Minerals include ammonium persulfate and alkaline salt persulfate. Persulfate initiators such as ammonium persulfate (APS) can be used alone or in combination with other reducing agents. Suitable reducing agents include ammonium bisulfite or sodium metabisulfite, thiosulfates such as ammonium, potassium, sodium, hydrazine, and the like. It is preferable that the quantity of the said initiator is 0.05 to 0.5 weight%.

In addition, in the method for producing a fluorine-based polymer according to the present invention, the water dispersion emulsion polymerization may use a chain transfer agent (chain transfer agent). Examples of chain transfer agents include esters such as diethylmalonate, dimethyl ether, ethers such as methyl t-butyl ether, alkanes such as ethane, propane and n-pentane, halogenated hydrocarbons such as CCl ₄ , CHCl ₃ and CH ₂ Cl _2, and the like. Carbon fluoride compounds such as CH ₂ FCF ₃ (HCFC-134a);

In the method for producing a fluorine-based polymer according to the present invention, the fluorine-based monomer is tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene, vinyl fluoride (VF) and vinylidene fluoride ( Fluorinated monomers of VDF). Preferably, the fluorinated monomer may use vinylidene fluoride (VDF), and the vinylidene fluoride may be used alone or in tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene, and vinyl. It can be used as a mixture mixed with at least one selected from the group consisting of fluoride (VF).

In the method for producing a fluorine-based polymer according to the present invention, the solid content of the fluorine-based polymer in the dispersed phase in the water dispersion emulsion polymerization is preferably in the range of 10 to 25%, the particle size (volume average diameter) of the fluorine-based polymer is 40-450 It is preferred to have a value in the nm range. In this case, the fluorine-based polymer may be separated from the dispersed phase by aggregation if the polymer in the solid form is desired.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

< Example  1> Fluorosulfonate Type  Preparation of Fluorinated Polymer Using Surfactant 1

600 ml of deionized water containing 0.06 g of CF ₃ O (CH ₂ ) ₁₀ SO ₃ Na, a fluorosulfonate-based surfactant, was added to a 1,000 ml polymerization reactor, pressurized to 4 bar with nitrogen while stirring at 50 rpm, and Degassing was repeated to drive out the air. The reactor was then heated to 80 ° C. and then pressurized to 30 bar while feeding vinylidene fluoride (VDF) gas. Next, 2 ml of deionized water in which 0.72 g ammonium percellate (APS) was dissolved and 1 ml deionized water in which 0.12 g Na ₂ S ₂ O ₅ was dissolved were injected into the reactor to initiate polymerization. Stirring speed was set to 240 rpm. Thereafter, the VDF was continuously supplied to maintain the reaction pressure at 30 bar. After 0.6 g of VDF reacted, 1.2 g of HCFC-123 was added as a chain transfer agent. After 1 g of VDF reaction, the reaction temperature was adjusted to 100 ° C. to continue the reaction at this temperature. The reaction was terminated after the desired amount of 150 g of VDF had reacted. The total polymerization time was 480 minutes. The reactor was evacuated and the dispersion was withdrawn. The solids content of the resulting dispersion after polymerization was 20% and particle size 385 nm.

< Example  2> Fluorosulfonate Type  Preparation of Fluorinated Polymer Using Surfactant 2

를 사용하는 것을 제외하고는 실시예 1과 동일한 방법으로 수행하여 불소계 고분자를 중합하였다. 중합 후 생성된 분산액의 고체 함량은 20%이고 입자 크기는 430 nm이었다.
As a fluorosulfonate surfactant, instead of C ₂ F ₅ (CH ₂ CF ₂ ) ₃ CH ₂ COONa

Except for using the same as in Example 1 to polymerize the fluorine-based polymer. The solids content of the resulting dispersion after polymerization was 20% and particle size was 430 nm.

< Example  3> Fluorosulfonate Type  Preparation of Fluorinated Polymer Using Surfactants 3

Mixture (0.04 g / 0.02 g) of a mixture of CF ₃ O (CH ₂ ) ₁₀ SO ₃ Na as a fluorosulfonate surfactant and CF ₃ (OCF ₂ ) ₃ CF ₂ COONa as a perfluoropolyether based surfactant A fluorinated polymer was polymerized in the same manner as in Example 1 except for using. The solids content of the resulting dispersion after polymerization was 20% and particle size was 240 nm.

< Example  4> Fluorosulfonate Type  Fluorine-based Polymer Preparation Using Surfactants 4

Except for adding vinylidene fluoride (VDF) / tetrafluoroethylene (TFE) / hexafluoropropylene (HEP) mixture as a reactant instead of vinylidene fluoride (VDF) alone at a constant ratio of 1.0 / 0.4 / 0.6. Was carried out in the same manner as in Example 1 to polymerize the fluorine-based polymer. The total polymerization time was 520 minutes. The solids content of the resulting dispersion after polymerization was 20% and particle size was 340 nm.

Claims (4)

Using at least one fluorosulfonate-based surfactant represented by the formula (1), a method for producing a fluorine-based polymer comprising the step of polymerizing one or more fluorine-based monomers in water dispersion emulsion.
[Formula 1]

.
(In Formula 1,
R _f is CF ₃ or C ₂ F ₅ ,
X is O, C ₆ H ₄ O or CF ₃ N,
M is a metal ion,
n is an integer of 4-12.)
The method of claim 1, wherein M is selected from the group consisting of ions such as sodium, potassium and ammonium.
The fluorosulfonate surfactant according to claim 1, wherein the fluorosulfonate surfactant is used alone or in combination with at least one perfluoropolyether fluorine surfactant selected from the group consisting of the following Chemical Formulas 2 to 4. Method for producing a polymer.
(2)

(In the formula (2)
n is an integer from 1 to 6,
X is -COOH or -COOM (M = Na, K or NH ₄ )
(3)

(In Chemical Formula 3,
m is an integer of 0 to 3,
L is -CF (CF ₃ )-, -CF _2- , or -CF ₂ CF _2- ,
X is -COOH or -COOM (M = Na, K or NH ₄ )
[Chemical Formula 4]

(In Formula 4,
R _f ′ is a C ₁ -C ₄ straight or branched perfluoroalkyl group,
X is -COOH or -COOM (M = Na, K or NH ₄ )
The method of claim 1, wherein the fluorine monomer is vinylidene fluoride (VDF) alone or a group consisting of tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene and vinyl fluoride (VF). Method for producing a fluorine-based polymer, characterized in that the mixture of at least one selected from vinylidene fluoride (VDF) mixed.