JP2000344825A - Production of fluorocarbon polymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain uniform polymer particles easily in good yields by bringing an emulsion-polymerized polymer latex into contact with an extracting solvent comprising a fluoro solvent having a specified boiling point to separate an unreacted monomer from the latex, and decreasing the extracting solvent to a specified amount or lower to coagulate the latex into polymer particles. SOLUTION: A polymer latex obtained by emulsion-polymerizing a fluorocarbon monomer is brought into contact with an extracting solvent comprising a fluoro solvent having a boiling point of 10-250 deg.C to separate an unreacted monomer from the latex, and the solvent in the latex is decreased to 10% or below to coagulate the latex into polymer particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing fluorocarbon polymer particles from a latex obtained by emulsion polymerization of a fluorocarbon monomer.

[0002]

2. Description of the Related Art Fluorocarbon polymers are emulsion-polymerized,
It is produced by a method such as suspension polymerization, solution polymerization or bulk polymerization. Emulsion polymerization has advantages such as high volumetric efficiency of a polymerization tank, low heat removal during polymerization and low torque during stirring. In the emulsion polymerization, the unreacted fluorocarbon monomer which is liquid at room temperature is contained in the produced latex, and it is preferable to separate and recover the latex. In particular, unpolymerized fluorocarbon monomers should be separated and recovered prior to aggregation, since fluorocarbon monomers having functional groups may be modified during latex aggregation to obtain polymer particles and the recovery rate of the fluorocarbon polymer may decrease. Is preferred.

Conventionally, an unreacted fluorocarbon monomer is separated from an emulsion polymerization latex by an extraction method using an extraction solvent. As the extraction solvent, CF ₂ ClCF ₂
At least one fluorine-based solvent selected from the group consisting of CFHCl, CF ₃ CF ₂ CHCl ₂ , hydrofluorocarbon and fluorocarbon is used (JP-A-7-118332), and unreacted fluorocarbon monomer is separated. The latex is then added with an acid to agglomerate the polymer to obtain particles.However, conventionally, in many cases, the polymer hardly becomes uniform particles at the time of this aggregation, and when the polymer particles are washed by filtration. In some cases, the polymer particles sometimes clog the filter cloth surface, making filtration difficult.

[0004]

An object of the present invention is to solve the above-mentioned problems. That is, the present invention is to easily produce uniform particles of the fluorocarbon polymer in good yield by aggregating the fluorocarbon polymer from latex obtained by emulsion polymerization of the fluorocarbon monomer, and when filtering and washing the fluorocarbon polymer particles, The present invention provides a method for efficiently and easily producing fluorocarbon polymer particles without causing the polymer to block the filter cloth surface.

[0005]

According to the study of the present inventor, when the fluorocarbon polymer particles are obtained from the latex of the fluorocarbon polymer by coagulation,
The main cause, such as difficulty in forming uniform particles and clogging of the filter cloth surface during washing and filtration of aggregated particles, is the amount of the extraction solvent remaining in the latex together with the type of extraction solvent used. That was found. According to the present invention, as the extraction solvent when separating the unreacted monomer in the latex, a fluorinated solvent having a boiling point of 10 to 250 ° C is used, and the extraction solvent contained in the latex after separating the unreacted monomer. It has been found that the above-mentioned problem can be solved by controlling the content of the polymer to 10% by weight or less, preferably 5% by weight or less, particularly 3% by weight or less. Thus, the present invention
A latex of a fluorocarbon polymer obtained by emulsion polymerization of a fluorocarbon monomer is used.
After separating the unreacted fluorocarbon monomer by contacting with an extraction solvent consisting of a fluorinated solvent having a temperature of 50 ° C.,
Producing the fluorocarbon polymer particles, wherein the extraction solvent contained in the latex is separated and removed, whereby the extraction solvent in the latex is reduced to 10% by weight or less, and then the fluorocarbon polymer particles are aggregated. In the way.

[0006]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a solvent used for extracting and separating the unreacted liquid fluorocarbon monomer from a latex obtained by emulsion polymerization of a fluorocarbon monomer, which is preferably liquid at normal temperature, comprises: Boiling point is 10 to 250 ° C, preferably 50 to 180 ° C
Is preferred. Among them, those having a boiling point difference of 20 ° C. or more from the fluorocarbon monomer are preferred because of the ease of separation by distillation after extraction of the fluorocarbon monomer. Preferred examples of the fluorinated solvent used in the present invention,
Hydrochlorofluorocarbon, hydrofluorocarbon (HFC) or fluorocarbon (FC). Specific examples of hydrochlorofluorocarbons include C
F ₂ ClCF ₂ CFHCl or CF ₃ CF ₂ CHCl ₂ . The hydrofluorocarbon preferably has a linear, branched or cyclic shape having 4 to 12 carbon atoms, and specific examples thereof include C ₄ F ₉ C ₂ H ₅ (CF ₃ ) ₂ CFCFHCFHCF.
₃ , C ₆ F ₁₇ H ₁ , C ₆ F ₁₃ C ₂ H ₅ or C ₈ F ₁₇ C ₂ H _5. Specific examples of the fluorocarbon include C ₆ F ₁₄ and C _{8
F 18, C 4 F 9)} 3 N,

Embedded image There is. These fluorinated solvents are used alone or as a mixture as an extraction solvent. The extraction treatment of the unreacted fluorocarbon monomer from the latex in the present invention is performed by mixing a latex with a fluorine-based solvent, stirring or shaking the mixture, and then allowing the mixture to stand. The mixing ratio (weight) of the latex and the fluorinated solvent is preferably 20/1 to 1
/ 10, especially 10/1 to 1/2 are used. After the two-layer separation, the extraction solvent containing the unreacted monomer in the lower layer is extracted, the extraction solvent is newly added, and the above operation is repeated, whereby the unreacted monomer can be quantitatively separated and recovered.

In the present invention, after the unreacted fluorocarbon monomer is extracted and separated from the latex, the fluorine-based solvent used for the extraction and separation is not more than 10% by weight (external value not including the fluorine-based solvent), preferably 5%.
It is separated and removed so as to be at most 3% by weight, especially at most 3% by weight. Such separation and removal is preferably carried out by vaporizing the fluorinated solvent by heating the latex or by passing or bubbling an inert gas to the latex alone or in combination. When heating the latex, preferably 5 to 250 ° C, particularly 45 to 180 ° C
The heating temperature of the latex is preferably lower than the boiling point of the fluorine-based solvent. The extraction solvent vaporized by heating is recovered using a condenser or the like. In this case, it is preferable to use a combination of aerating the inert gas from the gas phase or bubbling from the liquid phase so that the fluorine-based solvent is more easily vaporized. In order to further increase the separation / removal rate of the vaporized fluorine-based solvent, it is preferable to flow an inert gas after the removal of the solvent reaches equilibrium by heating. The inert gas preferably has a low flow rate for improving the removal rate of the vaporized solvent, but the operation time is long. Increasing the flow rate decreases the removal rate,
It is possible to reduce the content of the extraction solvent in the latex in a short time. When separating and removing fluorine-based solvents,
Stirring can also be used in combination. The stirring rotation speed affects the reduction time of the extraction solvent content, and the extraction solvent in the latex can be reduced in a shorter time when the stirring rotation speed is higher. Further, the separation and removal of the fluorine-based solvent is more effective when performed under a reduced pressure of preferably 680 mmHg or more in absolute pressure.

As the fluorocarbon monomer forming the fluorocarbon polymer particles produced by the present invention, those which are liquid at room temperature are preferably used, and various ones can be exemplified. Examples thereof include a carboxylic acid group, a sulfonic acid group, and a phosphorus compound. A fluorovinyl compound having an acid group such as an acid group or a functional group convertible to the acid group on the pendant side chain, particularly a perfluorovinyl compound, is preferred. The fluorocarbon polymer obtained by emulsion polymerization in the present invention means a homopolymer or a copolymer of such a fluorovinyl compound, and among them, a copolymer of a fluorovinyl compound and a fluorinated olefin compound is preferable. It is an object.

In the present invention, the fluorovinyl compound includes a carboxylic acid group or a carboxylic acid type functional group which can be converted to a carboxylic acid group, or a sulfonic acid group or a sulfonic acid type functional group which can be converted to a sulfonic acid group. Can be exemplified.

As a preferred fluorovinyl compound having a carboxylic acid type functional group, a general formula CF ₂ ＣＦCF (O
_{CF 2 CFCF 3) a O (} CF 2) b COOCH 3 ( where, a in the formula is 0 to 3, b is 1 to 5) are exemplified. A fluorovinyl compound having a sulfonic acid type functional group has a general formula CF ₂ ＝ CF (OCF ₂ CFCF ₃ ) _c O (CF ₂ ) _d S
O ₂ F (where c is 0 to 3 and d is 1 to 5)
Is exemplified.

Next, as the fluorinated olefin compound copolymerized with the fluorovinyl compound, ethylene tetrafluoride, ethylene trifluoride chloride, propylene hexafluoride,
Examples include ethylene trifluoride, vinylidene fluoride, and vinyl fluoride. Preferably, it is a fluorinated olefin compound represented by the general formula CF ₂ ＣCZY (where Z and Y are a fluorine atom, a chlorine atom, a hydrogen atom, or —CF ₃ ). Among them, perfluoroolefin is preferable,
Particularly, ethylene tetrafluoride is preferred.

In the present invention, two or more kinds of each of the above-mentioned monomers of the fluorovinyl compound and the fluorinated olefin compound may be used. In addition to these monomers, other component monomers such as CH
₂ = CR ₄ R ₅ (where R ₄ and R ₅ are a hydrogen atom and carbon number 1)
An olefin compound represented by an alkyl group or an aromatic nucleus of 8 to 8, CF ₂ ＣＦCFORf (Rf has 1 to 1 carbon atoms)
10 perfluoro such fluorovinyl ethers of alkyl groups shows a) _{a, CF 2 = CF-CF =} CF 2, CF 2 =
One or more kinds of divinyl monomers such as CFO (CF ₂ ) _e OCF = CF ₂ (e is 1 to 4) may be used in combination. Preferred representative examples of the olefin compound include ethylene, propylene, butene-1, isobutylene, styrene, α-methylstyrene, pentene-
1, hexene-1, heptene-1, 3-methyl-butene-1, 4-methyl-pentene-1 and the like. Among them, use of ethylene, propylene, isobutylene or the like is preferred in view of production and performance of the produced copolymer. Further, for example, it is possible to crosslink a copolymer obtained by using a divinyl monomer in combination, and to improve the mechanical strength when a molded product such as a film or a film is formed from fluorocarbon polymer particles.

The composition ratio of the fluorovinyl compound, the fluorinated olefin compound and the other component monomers forming the fluorocarbon polymer in the present invention is suitably selected according to the purpose, in relation to the performance of the polymer. .

The amount of the fluorovinyl compound is preferably 1 to 50 mol%, and more preferably 3 to 35 mol%, of the repeating unit derived from the fluorovinyl compound, based on all repeating units in the copolymer. If the amount of the fluorovinyl compound is too large, the ion exchange capacity in the case of a molded article such as an ion exchange membrane increases, but the mechanical strength is impaired, and further, the ion exchange capacity decreases due to an increase in water content. Come. On the other hand, if the amount is too small, the ion exchange function is not exhibited, which is not preferable.

On the other hand, the abundances of the fluorinated olefin compound and other component monomers in the fluorocarbon polymer of the present invention greatly depend on electrical, mechanical, chlorine resistance and the like, and these are suitably selected according to the purpose. .
For example, when an olefin compound is used as the fluorinated olefin compound and the other component monomer, the molar ratio of the other component monomer / the fluorinated olefin compound is preferably 5/95 to 70/30, particularly preferably 10/95. 90-6
Preferably, it is 0/40. When fluorovinyl ether, divinyl ether, or the like is used as the other component monomer, the repeating units derived from these monomers are contained in an amount of 30 mol% or less, preferably 2 to 20%, based on all the repeating units of the copolymer. It is preferable to set the ratio to about mol%.

The fluorocarbon polymer particles produced by the present invention, particularly when used as an ion exchange membrane, have a wide range of ion exchange capacity of 0.5 to 2.2 meq / g dry resin. Can be. What is characteristic here is that even if the ion exchange capacity is increased,
The molecular weight of the polymer can be increased, so that the mechanical properties and durability of the polymer do not decrease. Even when the ion exchange capacity is within the above range, preferably 0.8 meq / g dry resin or more, particularly 1.0 meq / g dry resin or more, the mechanical properties and electrochemical properties of the ion exchange membrane can be improved. Preferred for performance. Further, the molecular weight of the fluorocarbon polymer obtained in the present invention, for example, when used as an ion-exchange membrane, is related to its mechanical performance and membrane-forming properties. 170-340 ° C, especially 180-300
° C.

In the present invention, the term TQ relates to the molecular weight of the polymer and is defined as the temperature at which the volume flow rate is 100 mm ³ / sec. Here, the volume flow rate is 30 k for the copolymer.
The polymer is melted and discharged from an orifice maintained at a predetermined temperature of 1 mm in diameter and 2 mm in length under a pressure of g / cm ² , and the flow rate of the polymer flowing out is indicated in units of mm ³ / sec.

The ion exchange capacity is as follows. That is, the H-type cation exchange membrane made of a specific polymer is allowed to stand in 1N HCl at 60 ° C. for 5 hours to be completely converted to the H-type, and sufficiently washed with water so that HCl does not remain. Then, 0.5 g of this H-type film was
Leave for 2 days at room temperature in 25 cm ^{3 of a} 0.1 N aqueous NaOH solution. The membrane was then removed and the NaOH in solution
Is determined by back titration with 0.1N HCl.

In the present invention, the emulsion polymerization of a fluorocarbon monomer, for example, the copolymerization reaction of a fluorovinyl compound and a fluorinated olefin compound, is preferably carried out in an aqueous medium. Usually, the amount of the aqueous medium used is controlled to 20 parts by weight or less, preferably 10 parts by weight or less, based on 1 part by weight of the fluorovinyl compound. If the amount of the aqueous medium used is too large, the copolymerization reaction rate is significantly reduced, and it takes a long time to obtain a high copolymer yield. On the other hand, if the amount of the aqueous medium is too large, it becomes difficult to achieve a high molecular weight when a high ion exchange capacity is used, such as when the polymer is used for an ion exchange membrane. Further, the following difficulties are recognized when using a large amount of an aqueous medium. For example, there are disadvantages in work operation such as an increase in the size of a reaction apparatus or separation and recovery of a polymer.

Next, in the emulsion polymerization, for example, copolymerization of the present invention, it is preferable to employ a polymerization reaction pressure of 1 kg / cm ² (gauge pressure, hereinafter the same). If the polymerization reaction pressure is too low, the copolymerization reaction rate cannot be maintained at a practically satisfactory height, and there is difficulty in forming a high molecular weight polymer. On the other hand, if the polymerization reaction pressure is too low, the ion exchange capacity of the produced polymer becomes extremely high, and the mechanical strength and ion exchange performance tend to decrease due to an increase in water content. Incidentally, the polymerization reaction pressure is preferably selected from 50 kg / cm ² or less in consideration of the reaction apparatus or the operation in industrial practice. Although it is possible to employ a polymerization reaction pressure higher than this range, in the present invention, it is optimal to select the polymerization reaction pressure from a range of 1 to 50 kg / cm ^2, preferably 3 to 30 kg / cm ² .

In the polymerization reaction of the present invention, other conditions and operations other than the above reaction conditions can be employed over a wide range without any particular limitation. For example, the reaction temperature, the optimal value can be selected depending on the type of polymerization initiation source, the reaction molar ratio, etc., but usually too high or low temperature is disadvantageous for industrial practice, so 10 to 90 ° C. Preferably 20-8
It is selected from about 0 ° C.

In the present invention, it is desirable to select a polymerization initiator having high activity at the above-mentioned suitable reaction temperature. For example, ionizing radiation having high activity can be employed even at room temperature or lower, but a method employing an azo compound or a peroxy compound is generally advantageous for industrial implementation. The polymerization initiator source suitably employed in the present invention is disuccinic peroxide, benzoyl peroxide, lauroyl peroxide, dipentafluoropropionyl peroxide, which exhibits high activity at about 10 to 90 ° C. under the copolymerization reaction pressure. Diacyl peroxide such as 2,2-azobis (2-amidinopropane)
Azo compounds such as hydrochloride, 4,4-azobis (4-cyanovaleric acid) and azobisisobutyronitrile;
Peroxyesters such as t-butylperoxyisobutyrate and t-butylperoxypivalate; peroxydicarbonates such as diisopropylperoxydicarbonate and di-2-ethylhexylperoxydicarbonate; and diisopropylbenzene hydroperoxide And inorganic peroxides such as potassium persulfate and ammonium persulfate, and redox compounds thereof.

In the present invention, the concentration of the polymerization initiator is 0.0001 to 3% by weight, preferably about 0.001 to 2% by weight, based on the total amount of the monomers. By lowering the concentration of the initiator, it is possible to increase the molecular weight of the produced polymer, and it is difficult to maintain a high ion exchange capacity when the ion exchange membrane is used. If the concentration of the initiator is too high, the molecular weight tends to decrease, which is disadvantageous for producing a polymer having a high ion exchange capacity and a high molecular weight. Other surfactants used in ordinary aqueous medium polymerization,
Dispersants, buffers, molecular weight regulators and the like can also be added.

In the present invention, it is preferable to control the concentration of the produced polymer in the latex after the emulsion polymerization to 40% by weight or less, preferably 30% by weight or less. If the concentration is too high, problems such as increased stirring load, difficulty in heat removal, and insufficient diffusion of the fluorinated olefin monomer are observed.

As described above, the latex obtained by emulsion polymerization in an aqueous medium is subjected to extraction and separation of an unpolymerized fluorocarbon monomer by adding a fluorinated solvent as described above. Thereafter, the fluorine-based solvent contained in the latex is separated and removed. An unreacted gaseous monomer such as ethylene tetrafluoride can be easily separated and recovered by a purge method or the like. The latex from which the fluorinated solvent has been removed is then added with an acid such as hydrochloric acid or sulfuric acid to coagulate the polymer, preferably to produce particles of 500 to 3000 μm. For coagulation of the polymer, known coagulation means such as salting out, freeze coagulation, mechanical coagulation and the like may be employed instead of acid.

The aggregated polymer particles are sufficiently washed with water, and then water is replaced with a water-soluble organic solvent such as methanol or acetone. The washing of such polymer particles is carried out on a suitable filter paper using a filtration means, but in the case of the present invention, the polymer particles swell even during washing with water and can be carried out smoothly without blocking the filter cloth surface. . Next, the obtained polymer is subjected to the following treatment, if necessary, to convert the acid type functional group into an ester type. After air drying the polymer, the polymer 10
0 100 cm ³ preferably against parts 400-60
0 cm ³ or more of methanol is added, more preferably sulfuric acid is added thereto, and the mixture is treated at 20 ° C. or more for 1 to 50 hours with stirring. Next, the polymer and methanol are separated, and if sulfuric acid is added, the polymer is washed with methanol to remove the sulfuric acid, and then dried at 40 to 80 ° C. under reduced pressure to obtain polymer particles.

According to the present invention, fluorocarbon polymer particles having an ion exchange group having a high ion exchange capacity and a high molecular weight and having excellent moldability by heating and melting can be advantageously obtained. For example, fluorocarbon polymer copolymerization up in a conventional aqueous medium, even when using the fluorocarbon polymer of -COOR ₁ containing, TQ
Exceeds 300 ° C., but according to the present invention, TQ is 22
It is possible to obtain polymer particles having a temperature of around 0 ° C. With a fluorinated polymer having a TQ of 300 ° C. or higher, molding by heating and melting is extremely difficult and cannot be formed into a film or sheet. However, the fluorocarbon polymer particles according to the present invention can be formed into a film or sheet by extrusion or the like. It can be easily molded.

The fluorocarbon polymer particles in the present invention can be formed into an ion exchange membrane by an appropriate means. The ion exchange membrane converts a functional group into a carboxylic acid group by hydrolysis as necessary, and such a hydrolysis treatment can be performed before or after the membrane formation. Usually, it is desirable to carry out hydrolysis treatment after film formation. Various means can be adopted as the film forming means. For example, a known method such as heat-melt molding, latex molding, or cast molding by dissolving in an appropriate solution can be appropriately employed.

The ion exchange membrane made of fluorocarbon polymer particles in the present invention has various excellent performances, and can be widely used in various fields, objects, applications, and the like. For example, it is suitably used in a field where corrosion resistance is particularly required, such as diffusion dialysis and a membrane for a fuel cell. Above all, when used for alkaline electrolysis, it can exhibit high performance that cannot be obtained with a conventional ion exchange membrane.

For example, with a cation exchange membrane obtained by molding the fluorocarbon polymer particles of the present invention,
When an anode chamber and a cathode chamber are defined by dividing the anode and the cathode, and an alkali chloride aqueous solution is supplied to the anode chamber to perform electrolysis and obtain alkali hydroxide from the cathode chamber, a sodium chloride aqueous solution having a concentration of 2N or more is used. By electrolyzing at a current density of 5 to 20 A / dm ² as a raw material, sodium hydroxide having a high concentration of 40% or more can be stably produced over a long period with a current efficiency of 90% or more. Furthermore, operation at a low cell voltage of 4.5 V or less is possible.

[0031]

[Example 1] Into a 2-liter stainless steel autoclave, 1440 g of ion-exchanged water and C ₈ F ₁₇ C
5.0 g of OONH ₄ and 7.0 g of Na ₂ HPO ₄ .12H ₂ O.
2 g, 4.2 g of NaH ₂ PO ₄ .2H ₂ O, (NH ₄ ) ₂
1.15 g of S ₂ O ₈ and CF ₂ ＣＦCFO (CF ₂ ) ₃ C
432 g of OOCH ₃ was charged and sufficiently degassed. afterwards,
The temperature was raised to 39 ° C., ethylene tetrafluoride was introduced into the system, and the pressure was maintained at 5.1 kg / cm ² . 1 at 330 rpm
After stirring for 5 hours, unreacted ethylene tetrafluoride was purged to terminate the reaction. The resulting copolymer is CF ₂ ＣＦCFO
28.6 repeating units derived from (CF ₂ ) ₃ COOCH ₃
It was a latex of a fluorocarbon polymer having a composition containing mol%, and the amount of production (in terms of solid content, hereinafter the same) was 350 g.

The latex is unreacted CF ₂ ＣＦCFO (C
Although it contained F ₂ ) ₃ COOCH ₃ , it was impregnated with the polymer particles in the latex to form a uniform layer. 30 g of C ₆ F ₁₇ H (boiling point 72 ° C.) is added to 100 g of the latex.
g at 30 rpm using a 1 liter stirring tank at 320 rpm.
After mixing for 30 minutes, the mixture was allowed to stand for 30 minutes. After separating the lower C ₆ F ₁₇ H layer, the same amount of C ₆ F ₁₇ H was added again, and the extraction operation was repeated. After performing the extraction operation six times, CF ₂ = CFO (CF ₂ ) ₃ was obtained by gas chromatography analysis of the C ₆ F ₁₇ H layer.
COOCH ₃ was not detected and was extracted quantitatively. The content of the extraction solvent in the latex was 15% by weight (outer cover, the same applies hereinafter).

Next, the latex in the stirring tank was
The mixture was heated at 70 ° C. for 7 hours while stirring at m. After 5 hours, N ₂ gas was introduced into the stirring tank and the gas phase at 10 ml / min. After 7 hours, the extraction solvent content in the latex was 2%.

Thereafter, 5 g of a coagulation aid CH ₃ CCl ₂ F was added to 100 g of the latex and coagulated in an aqueous sulfuric acid solution to obtain uniform particles (average particle size of about 1500 μm).
m). Thereafter, the resultant was treated with methanol, washed, air-dried, and vacuum-dried to obtain 350 g of a polymer.

[Comparative Example 1] Unreacted CF ₂ = CFO (CF ₂ ) was obtained from the latex polymerized and produced in the same manner as in Example 1.
Example 1 Example ₃ was repeated except that ₃ COOCH ₃ was extracted using C ₆ F ₁₇ H, and then heating operation and introduction of N ₂ gas were not performed.
Polymer aggregation was performed in the same manner as described above. The aggregated particles became a single aggregate and did not become particulate.

Example 2 In a 2 liter stainless steel autoclave, 1000 g of ion-exchanged water and C ₈ F ₁₇ C
2.0 g of OONH ₄ and 5. ₂ g of Na ₂ HPO ₄ .12H ₂ O
_{0g, NaH 2 PO 4 · 2H} 2 O to 2.9g, (NH _{4) 2}
0.35 g of S ₂ O ₈ and CF ₂ ＣＦCFO (CF ₂ ) ₂ S
200 g of O ₂ F was charged and sufficiently degassed. Then 57
The temperature was raised to ℃, ethylene tetrafluoride was introduced into the system, and the pressure was maintained at 5.5 kg / cm ² . 5.5 at 750 rpm
After stirring for an hour, unreacted ethylene tetrafluoride was purged to terminate the reaction. The resulting copolymer is CF ₂ ＣＦCFO
It was a latex of a fluorocarbon polymer having a composition containing 19.0 mol% of repeating units derived from (CF ₂ ) ₂ SO ₂ F, and the amount produced was 174 g.

The latex is unreacted CF ₂ ＣＦCFO (C
Although it contained F ₂ ) ₂ SO ₂ F, it was impregnated with the polymer particles in the latex to form a uniform layer. 30 g of C ₆ F ₁₇ H (boiling point 72 ° C.) was added to 100 g of the latex, and the mixture was mixed at 320 rpm for 30 minutes using a 1-liter stirring tank, and then allowed to stand for 30 minutes. After separating the lower C ₆ F ₁₇ H layer, the same amount of C ₆ F ₁₇ H was added again, and the extraction operation was repeated. After the extraction operation was performed six times, CF ₂ = CFO (CF ₂ ) ₂ S was determined by gas chromatography analysis of the C ₆ F ₁₇ H layer.
O ₂ F was not detected and was quantitatively extracted. The extraction solvent content in the latex was 8% by weight.

Next, the latex was heated at 70 ° C. for 6 hours while stirring at 700 rpm. After 5 hours, N ₂ was introduced into the gas phase at 100 ml / min. After 6 hours, the extraction solvent content in the latex was 1.5%.

Thereafter, when the particles were aggregated in a sulfuric acid aqueous solution, uniform particles (average particle diameter of about 1500 μm) were obtained. Thereafter, the same treatment as in Example 1 was performed to obtain a polymer 174.
g was obtained.

Comparative Example 2 Unreacted CF ₂ ＣＦCFO (CF ₂ ) was obtained from the latex polymerized and produced in the same manner as in Example 2.
_{After 2} SO ₂ F was extracted using C ₆ F ₁₇ H, the polymer was aggregated in the same manner as in Example 2 except that the heating operation was not performed. The agglomerated particles became a single aggregate and did not become particles.

Example 3 A 2 liter stainless steel autoclave was charged with 1440 g of ion-exchanged water and C ₈ F ₁₇ C
OONH ₄ to _{2.9g, Na 2 HPO 4 · 12H} 2 O 7.
2 g, 4.2 g of NaH ₂ PO ₄ .2H ₂ O, (NH ₄ ) 2
0.86 g of S ₂ O ₈ and CF ₂ ＣＦCFO (CF ₂ ) ₃ C
The OOCH ₃ 327 g, the CF ₂ = CFOC ₃ F ₇ 105g
Charged and degassed sufficiently. Thereafter, the temperature was raised to 45 ° C., ethylene tetrafluoride was introduced into the system, and the pressure was increased to 7.1 kg / cm.
^It was kept at ² . After stirring at 330 rpm for 14 hours, unreacted ethylene tetrafluoride was purged to terminate the reaction. The resulting copolymer _{CF 2 = CFO (CF 2)} 3 COOCH 3 repeating units 17.8 mol% from, CF ₂ = CFOC ₃
F ₇ with a latex fluorocarbon polymer composition comprising 6.6 mol% of repeating units derived from, the amount is 250
g.

The latex is unreacted CF ₂ ＣＦCFO (C
Although it contains F ₂ ) ₃ COOCH ₃ and CF ₂ ＣＦCFOC ₃ F ₇ , it is impregnated into the polymer particles in the latex to form a uniform layer. CCLF ₂ per 100 g of the latex
After adding 30 g of CF ₂ CHClF (boiling point: 56 ° C.) and mixing at 320 rpm for 30 minutes using a 1 liter stirring tank, 3
It was left for 0 minutes. After separation of the lower layer of CClF ₂ CF ₂ CHClF layer was repeated the same amount added extraction again CClF ₂ CF ₂ CHClF. After performing the extraction operation six times, C
Gas chromatography analysis of the ClF ₂ CF ₂ CHClF layer showed that CF ₂ ＣＦCFO (CF ₂ ) ₃ COOCH ₃ was not detected and quantitatively extracted. The extraction solvent content in the latex was 12%.

After the extraction, the latex in the stirring tank was
and heated at 55 ° C. for 6 hours. After 5 hours, N ₂
Was introduced at 10 ml / min. After 6 hours, the extraction solvent content was 4.8%.

After the heating operation, the particles aggregated in an aqueous sulfuric acid solution to form uniform aggregated particles (average particle diameter: about 1000 μm).
Thereafter, predetermined processing was performed to obtain 250 g of a polymer.

COMPARATIVE EXAMPLE 3 Unreacted CF ₂ CFO (CF ₂ ) was obtained from the latex polymerized and produced in the same manner as in Example 3.
After a ₃ COOCH ₃ were extracted with CClF ₂ CF ₂ CHClF, it was aggregated without adding heating operation. The agglomerated particles became one massive agglomerate.

[0046]

According to the present invention, uniform particles of the fluorocarbon polymer having excellent moldability can be easily produced by aggregating the fluorocarbon polymer from the latex obtained by emulsion polymerization of the fluorocarbon polymer. In particular, a cation exchange membrane obtained by molding a fluorocarbon polymer having an acid-type functional group obtained by the present invention has a high ion exchange capacity and a high molecular weight, and thus is suitable as a membrane for alkaline electrolysis. In the present invention, the unreacted fluorocarbon monomer can be separated and recovered quantitatively, and the fluorine-based solvent used for extracting the polymer can be separated and recovered almost quantitatively. The fact that the unreacted fluorocarbon polymer and fluorine-based extraction solvent can be quantitatively separated and recovered means that these raw materials can be recycled and used, eliminating the risk of environmental pollution and global warming when released into the atmosphere. it can.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsushi Shimohira 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term in Asahi Glass Co., Ltd. GD02

Claims (5)

[Claims] 1. A fluorocarbon polymer latex obtained by emulsion polymerization of a fluorocarbon monomer is brought into contact with an extraction solvent comprising a fluorinated solvent having a boiling point of 10 to 250 ° C. to separate the unreacted fluorocarbon monomer. By separating and removing the extraction solvent contained in the latex, the extraction solvent in the latex is reduced to 10% by weight or less, and then the fluorocarbon polymer particles in the latex are agglomerated. Method for producing particles. 2. The method according to claim 1, wherein the fluorocarbon polymer is a polymer of a fluorovinyl compound having an acid group or an acid-type functional group that can be converted to the acid group. 3. The method according to claim 1, wherein the fluorocarbon polymer is a copolymer of a fluorovinyl compound having an acid group or an acid-type functional group capable of being converted to the acid group and a fluorinated olefin compound. 4. The method according to claim 1, wherein the fluorinated solvent is hydrochlorofluorocarbon, hydrofluorocarbon or fluorocarbon. 5. Separation of an extraction solvent contained in the latex,
The removal is carried out by heating the latex at 5-250 [deg.] C. to vaporize the extraction solvent.
Manufacturing method.