JP2002332366A - Process for preparing sulfonate group-containing polymer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient process for preparing a polymeric, solid electrolyte film. SOLUTION: In a process for preparing a sulfonate group-containing fluorine polymer, a fluorine polymer containing a repeating unit having a sulfonyl fluoride group at its side chain terminal is treated with an amine to obtain a polymer, which is heat molded and subsequently treated with an acid to be converted, via a single step, into a fluorine polymer containing a repeating unit having a sulfonate group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a fluorine-based polymer membrane useful as a fluorine-based polymer electrolyte membrane such as a fuel cell diaphragm.

[0002]

2. Description of the Related Art In recent years, fuel cells using a solid polymer membrane as an electrolyte have been attracting attention because they can be reduced in size and weight and have a high output density even at a relatively low temperature. Development is accelerating. Solid polymer electrolytes used for such purposes are required to have excellent proton conductivity, appropriate water retention, gas barrier properties against hydrogen gas, oxygen gas, and the like. As a material satisfying such requirements, various polymers having a sulfonic acid group or a phosphonic acid group at the terminal of a main chain or a side chain have been studied, and many materials have been proposed (O. Savad).
ogo, Journal of New Materi
als for Electrochemical S
systems I, 47-66 (1998)). However, under actual fuel cell operating conditions, active oxygen species having high oxidizing power are generated at the electrodes, and in order to stably operate the fuel cell over a long period of time, especially under such a severe oxidizing atmosphere, Durability is required. Many hydrocarbon-based materials that have been proposed to date show excellent characteristics with respect to the initial characteristics of fuel cell operation,
In many cases, concerns have been raised about long-term operation.

For this reason, at present, studies for practical use include the following general formula (4):

Embedded image (In the above general formula (4), m is 0 or 1, n is 2 or 3, k, l is an integer of 1 or more, and 1.5 ≦ k / l ≦ 14)
Is mainly employed.

[0004] This polymer has an extremely close molding temperature and thermal decomposition temperature due to thermal melting, and it is generally difficult to perform thermoforming with the structure of general formula (4). Therefore, the following general formula (5) which usually has thermoplasticity:

Embedded image (In the general formula (5), m and n are the same as the general formula (4).) A copolymer of a perfluorovinyl ether monomer represented by the general formula (4) and tetrafluoroethylene (TFE) was formed by melt molding. Thereafter, a film having the structure represented by the general formula (4) is obtained by performing saponification and acid treatment reactions.

That is, conventionally, the terminal of the side chain is -SO ₂ F
The fluoropolymer of the type molded into a film by such melt molding, converting the film converted to alkali by sulfonate type, such as NaOH or KOH, to further -SO ₃ H form by reaction with an acid such as hydrochloric acid Means is used.

However, in such a conventional film forming process, when a continuous process is performed on a film of a -SO ₂ F type copolymer having a practical copolymer composition by a roll process or the like, the following process is required. There's a problem. 1) -SO ₂ F type film has problems such that the film is too soft to increase the tension, and high-speed film formation cannot be performed, and sag tends to occur during film formation. Further, -SO ₂
Since the F-type polymer has high adhesiveness of the film, it is necessary to prevent the adhesiveness between the films using interleaving paper or the like, which hinders productivity. 2) Further, in the film treatment step, particularly in the saponification step (alkali treatment step), a high-temperature and long-time reaction is required. Further, in this step, the dimensional change of the film before and after saponification is remarkable, so that wrinkles are likely to occur during the film formation, and it is difficult to increase the productivity in order to suppress the wrinkles. Although preferred for film formation of the sulfonate-type polymer obtained by alkaline treatment of -SO ₂ F type polymer is easy to convert to possible -SO ₃ H type, actually -SO ₃ M In the case of (M = alkali metal, alkaline earth metal) mold, the moldable temperature becomes high,
It is difficult to form a film industrially advantageously.

In US Pat. No. 3,784,399, sulfonamide (—SO ₂ N) is obtained by treating the surface of a —SO ₂ F type polymer film with ammonia.
H ₂₎ phased film, it can be suitably used in the brine electrolysis applications is disclosed. The technology related to the polymer membrane is as follows.
Via Intermediate polymer obtained by reaction of an amine in the presence of water with the present invention that induces the film finally -SO ₃ H type polymer, in the chemical structure of the film is different from even in applications .

Further, Japanese Patent Application Laid-Open No. 50-49394 discloses a polymer having a side chain terminal —SO ₃ H type or a salt thereof.
A method for treating a fluorinated polymer is disclosed in which the polymer is brought into contact with a tertiary amine, a quaternary ammonium base, or the like, and then the polymer that has been brought into contact is melt-treated. The technology has the purpose of a defective portion of the -SO ₃ H type polymer film repair by melt processing, shown in the present invention,
1) treatment of the -SO ₂ F type polymer by contact with an amine compound in the presence of water, 2) characteristics of the modified film and a high-productivity film forming method utilizing the characteristics, or Productivity-SO ₃ H by only acid treatment of the treated membrane
It differs from the patterning process in the method and application.

[0009]

SUMMARY OF THE INVENTION The present invention solves the problems of tackiness, processability, and complexity of the hydrolysis process in the production of the proton-type solid electrolyte membrane, and is suitable for use in fuel cells and the like. It is an object of the present invention to provide a method for efficiently producing a proton-type solid electrolyte membrane and a novel precursor polymer suitable for the film-forming process.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a polymer treated with an amine compound in the presence of water is used as an intermediate to efficiently achieve the object. The inventors have found that a proton conductive polymer can be produced, and have accomplished the present invention. That is, the present invention provides the following general formula (1):

Embedded image In the side chain, a sulfonic acid group represented by —R _f —SO ₃ H (1) (in the above general formula (1), R _f represents a perfluoroalkylene group having 1 to 4 carbon atoms) A method for producing a film comprising a polymer, comprising:

The following general formula (2)

Embedded image A polymer containing a substituent represented by the side chain represented by —R _f —SO ₂ F (2) (in the above formula (2), R _f is the same as in the above formula (1)) A step of bringing into contact with an amine compound in the presence of water, 2) a step of melt-forming the obtained modified polymer, and 3) a step of treating the obtained film with an acid.

The sulfonic acid group-containing side chain has the following formula (3)

Embedded image (In the above formula (3), m is 0 or 1, n is 2 or 3)
The method for producing a membrane comprising a polymer having a sulfonic acid group in a side chain, characterized in that the molecular weight per one sulfonic acid group (Equiv
The present invention relates to a method for producing a membrane comprising a polymer containing a sulfonic acid group in a side chain, wherein the weight of the polymer (alent weight: hereinafter referred to as EW) is 400 to 1500.

Hereinafter, the present invention will be described in detail. That is, the present inventors are conventional sulfonic acid precursors-
It has been found that by treating an SO ₂ F type polymer with an amine compound in the presence of water, it can be easily converted to a thermoplastic intermediate polymer having high heat stability. Since the intermediate polymer exhibits a high thermal decomposition temperature and can be melt-molded in a low temperature region, it can be stably melt-formed under mild conditions without denaturing the polymer.

The present inventors have further obtained this method.
The intermediate polymer membrane is -SO _TwoPoly with F group
Adhesion is lower than that of the
No sticky paper is necessary because it is hard to stick and easy to peel off,
Furthermore, -SO_TwoHigh elastic modulus compared to F-type polymer film
That high-speed film formation with high tension is possible
Has been found to be suitable for film production with high productivity.
did. Also, a film of the intermediate polymer obtained by this method
Is easily obtained by only acid treatment under mild conditions._ThreeH-type port
That it can be converted to rimer, and before and after the acid treatment step
Changes in the film size at-_TwoF polymer membrane
No need to worry about wrinkles like saponification process
From high quality -SO with high productivity_ThreeMade of H-type polymer film
It turned out to be suitable for construction.

As described above, Japanese Patent Application Laid-Open No. 50-49 / 1979
No. 394 discloses a side chain terminal -SO _ThreeH-type polymer
Or its salts with tertiary amines, quaternary ammonium bases, etc.
Contact and then melt-process the contacted polymer.
A method for treating a denatured polymer is disclosed. The technology is
-SO_ThreeH-type polymer film for defect processing
It is intended for more repair. Accordingly
Therefore, the gazette contains the features of the present application, 1) -SO_TwoF
Contact of amine-type polymers with amine compounds in the presence of water
Treatment 2) The properties of the modified membrane and its properties were utilized
High productivity film forming method, or 3) film obtained in the above step
Productivity-SO only by acid treatment_ThreeH-form treatment etc.
Is not described at all.

Hereinafter, the present invention will be described in more detail. Incidentally, it is possible to convert the thermoplastic polymer and equivalent polymers of the present invention by contacting an amine compound to use polymers of -SO ₃ H type in the present invention, a method of the polymer present invention A film can be formed by the same method.

As the amine compound used in the method of the present invention, a nitrogen-containing compound having various structures forming an ammonium salt with sulfonic acid is applicable, and usually, the following general formula (6):

Embedded image It is represented by NR ¹ R ² R ³ (6). Here, in the general formula (6),
R ¹ , R ² , and R ³ are hydrogen, an alkyl group, an aryl group, or an aralkyl group (which may be the same or different), or ^one of R ¹ , R ² , and R ³ Two or more may be linked to form a ring structure. R ¹ , R ² , R
Among ³ , the number of hydrogen is usually 3 or less, preferably 2 or less, particularly preferably 1 or less.

The amine compound to be used preferably has a compact structure as much as possible because of good operability. Therefore, when R ¹ , R ² and R ³ are any of an alkyl group, an aryl group and an aralkyl group, In both cases, the number of carbon atoms is usually within 12 carbon atoms, preferably within 8 carbon atoms, particularly preferably within 3 carbon atoms. Further, R ¹ , R ² , and R ³ may combine to form a ring, in which case R ¹ , R ² , R 3
The total number of carbon atoms in ³ is preferably 20 or less, and in this case, the ring may be conjugated.

When R ¹ , R ² and R ³ are alkyl groups, specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t
-Butyl, pentyl, hexyl, heptyl, cyclohexyl, cycloheptyl, pyrrolidyl, piperidyl and the like. In the case of an aryl group or an aralkyl group, specific examples include a phenyl group, a tolyl group, a xylyl group, a benzyl group, a phenethyl group, a naphthyl group, and a biphenyl group. In the case of a conjugated ring compound, examples of the amine compound include pyrrole, pyridine, pyrimidine, alkyl-substituted or unsubstituted imidazole, and the like.

When ammonia is used as the amine compound, an organic amine is preferably used as the amine compound because the melting temperature is high and the difference between the melting temperature and the thermal decomposition temperature is small. When a quaternary ammonium compound is used as the amine compound, it is difficult to convert the resulting polymer into a sulfonic acid type polymer by acid treatment, which is not suitable for the present invention.

The method of treating the polymer with the amine compound is not particularly limited, but a flake, powder, or the like may be added to a bath filled with a mixed solution of the amine compound and water or a solution containing an organic solvent. Method of immersing polymer in the form of pellets or pellets, method of applying a mixed solution of amine compound and water or a solution containing an organic solvent to the polymer by spraying, etc., and gaseous amine compound and water coexist For example, a method of holding a flake-like, powder-like, or pellet-like polymer in an atmosphere in which the flakes are formed. The required amount of the amine compound and water at this time is determined based on the amount of the polymer to be treated. The amount of water is generally more -SO ₂ F group equivalents of the polymer to be processed is used. No upper limit is required. The amount of amine compound may be a -SO ₂ F group and the amount of more than equivalent of the polymer to be processed is preferably in an amount of more than 2 equivalents of -SO ₂ F groups in the polymer to be processed, with respect to the upper limit No limitation is required. In each case, it is most preferable to mix the water and the amine compound before adding the polymer.However, in a water-free amine compound atmosphere, the polymer wetted with water is treated in a treatment environment. You can put it down. In each case, heating may be performed as needed. The lower limit of the temperature in this case is the temperature at which the —SO ₂ F group is actually denatured at a realistic rate, and specifically, is 0 ° C. or higher, more preferably 15 ° C. or higher, and further preferably 50 ° C. or higher. It is. The upper limit may be lower than the temperature at which the polymer after the amine compound treatment is thermally denatured, but is usually 300 ° C or lower, preferably 250 ° C or lower. Regarding the processing time,
It is sufficient that the time is longer than the time when the polymer is completely converted, and there is no particular limitation, but too long treatment is not preferable in terms of production efficiency. Further, in this case, an appropriate basic compound can be used as a trapping agent for hydrogen fluoride produced as a by-product, and specifically, NR ¹ R ² R
³ itself, NaF, an alkali metal carbonate or the like can be used.

The polymer to be treated in the present invention can be obtained, for example, by copolymerizing a vinyl monomer having a substituent represented by the above general formula (2) in the side chain with another vinyl monomer. Here, -R _f - is a perfluoroalkylene group having 1 to 4 carbon atoms, and specific examples thereof include those exemplified for example by the following equation (7).

Embedded image

Accordingly, for example, the vinyl monomer having a substituent represented by the above general formula (2) in the side chain is specifically exemplified by the following formula (8).

Embedded image

In particular, the following general formula (9)

Embedded image (In the above general formula (9), m is 0 or 1, n is 2 or 3) It is particularly preferable because of good operability.

The comonomers to be mated may be one or more fluorinated olefins, one or more non-fluorinated olefins, or a combination of a fluorinated olefin and a non-fluorinated olefin,
When used as a fuel cell diaphragm or the like, a fluorinated olefin is preferred, a perfluoroolefin is more preferred, and tetrafluoroethylene is particularly preferred. Further considering the polymer structure, a combination of the above general formula (9) and tetrafluoroethylene, that is, the following general formula (5)

Embedded image (In the general formula (5), m is 0 or 1, n is 2 or 3, k, l is an integer of 1 or more, and 1.5 ≦ k / l ≦ 14)
Most preferably, it is a polymer represented by Here, examples of the fluorinated olefin include tetrafluoroethylene, trifluorochloroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and the like. When the polymer containing the substituent represented by the above general formula (2) in the side chain is a copolymer with these monomers, the composition ratio is determined by hydrolyzing the obtained —SO ₂ F type polymer. When converted to a sulfonic acid-containing polymer by the above method, the molecular weight per sulfonic acid (Equivalent weight)
Preferably, t) is set to be in the range of 400 to 1500, more preferably in the range of 600 to 1200, and still more preferably in the range of 700 to 1100. Also,
If the copolymer composition ratio is expressed in terms of% by weight, the proportion of the component of the repeating unit containing a sulfonic acid group represented by the above general formula (1) in the side chain is preferably 95 to 30% by weight, and 90 to 40% by weight.
Is more preferable, and 85 to 45% is more preferable.

A modified polymer (hereinafter referred to as "precursor polymer of the present invention") obtained by treating a polymer having a substituent represented by the above general formula (2) in the side chain represented by the general formula (2) with an amine compound Is expressed as a film. Various methods are employed as a film forming method, and usually, a melt film forming method is used. As a melt film forming method, a method in which an amine-treated polymer formed into a powder, a flake, or a pellet is formed by a calender method, an inflation method, a T-die method, a cutting method, an emulsion method, a hot press method, or the like. Is exemplified. Among them, the T-die method and the inflation method are more preferable in consideration of the productivity of the film formation. The heat treatment temperature at this time is equal to or higher than the temperature at which the precursor polymer of the present invention melts and has sufficient fluidity, and lower than the temperature at which the precursor polymer of the present invention thermally decomposes. Therefore, as the molding temperature, a wide range of temperatures can be adopted as long as the molding temperature is within the above range.
Preferably 150 ° C to 370 ° C, particularly preferably 180 ° C.
Temperatures in the range of ° C to 350 ° C are used.

In addition, a method in which a polymer is dissolved in a solvent in which a polymer treated with an amine compound is soluble and a film is formed by a casting method is also exemplified. Examples of the solvent in this case include alcohols such as ethanol and propyl alcohol, and a mixed solvent thereof with water, a fluorinated alcohol, a mixed solvent of a fluorinated organic compound and an alcohol, and an acid amide.

The precursor polymer film of the present invention thus obtained is easily converted to a sulfonic acid type by performing a hydrolysis reaction with an acid. Examples of the acid used here include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and aqueous hydrogen bromide, and mixtures of these with water or an organic solvent, and organic acids such as trifluoromethanesulfonic acid and trifluoroacetic acid. And a mixture of water and an organic solvent. As the organic solvent used for mixing, a substance which is miscible with an acid and is capable of swelling the precursor polymer of the present invention is preferable. Examples of the organic solvent include methanol, ethanol,
Alcohols such as isopropyl alcohol, ketones such as acetone, ethers such as dimethoxyethane,
And a halogen-based solvent such as HFC43-10mee.

As the acid treatment method, any method may be used as long as it can bring the acid into contact with the film. Examples of the method include a method of immersing the film in a bath filled with acid and a method of immersing the film in an acid-filled bath. And a method of applying a film to a tank filled with an acid vapor by using a spray or a doctor blade. In each case, heat may be applied if necessary. The lower limit of the temperature in this case is actually -SO
_The temperature is a temperature at which the ₃ H group is denatured at a practical rate, specifically, 0 ° C. or higher, more preferably 15 ° C. or higher, and further preferably 30 ° C. or higher. The upper limit may be less than the temperature at which the polymer has been converted to polymer and the -SO ₃ H form was treated with an amine compound does not thermal deformation, etc., but is usually 300 ° C. or less, preferably 250 ° C. or less, particularly preferably 180 ° C. or less. The processing time is -SO ₃
The upper and lower limits are not particularly limited, as long as the time can be converted to the H group, but it is not preferable to take an excessively long time in terms of production efficiency. As described above, according to the production method of the present invention, a fluorine-based sulfonic acid membrane that can be used for a fluorine-based polymer electrolyte membrane such as a fuel cell diaphragm can be produced with high productivity.

Hereinafter, the present invention will be described with reference to examples.

Example 1 The following formula (10):

Embedded image 10 g of polymer powder represented by the formula (EW = 950, Mel
t Index = 20.2 (Temperature 270C, Load 2.1
6 kg, orifice diameter 2.09 mmφ, length 8 mm)) were placed in a mixed solution of 190 ml of diethylamine and 10 ml of water, and the mixture was heated and refluxed in a 70 ° C. oil bath for 1.5 hours. Thereafter, the powder was filtered, sufficiently washed with running water, and dried. When this infrared absorption spectrum was measured (FTS-60A / 896 manufactured by Japan Bio-Rad Co., Ltd.)
Type FT-IR), -S observed around 1460 cm ^-1
The absorption peak due to O ₂ F disappears and 2800 cm ⁻¹
The absorption peak attributable to peripheral ～3000Cm ^-1 to -NCH ₂ CH ₃ appears was confirmed. Further, the thermal decomposition behavior of the treated powder was measured by thermogravimetry (TG, manufactured by Shimadzu Corporation).
The temperature at which the weight was reduced by 5% was 393 ° C. when measured at a rate of 10 ° C./minute under an Ar gas flow according to A50). This indicates that such an intermediate polymer has excellent heat resistance.

Next, the intermediate polymer powder was pressed with a load of 50 kgf / cm ² for 1 minute using a flat plate press machine heated to 270 ° C., whereby a slightly yellow colored film was obtained. In addition, this film had low adhesion between the films, and was easily separated when one of the films was lifted by hand after the two films were overlapped and lightly pressed. Further, the modulus of elasticity of the above film was measured by Vibron (DDV-01FP manufactured by Orientec Co.) and found to be 5.4 × 10 ⁹ dyne / cm ² at 25 ° C. On the other hand, when the elastic modulus of the —SO ₂ F type film was measured in the same manner, 2.9 × 10 2 at 25 ° C.
^{It was 8} dyne / cm ² . That is, it was shown that the polymer film subjected to the amine treatment had a significantly higher elastic modulus than that before the treatment.

This film (5.0 cm × dry state)
(5.0 cm square) was immersed in 30 ml of 3N sulfuric acid and heated and refluxed in a 130 ° C. water bath for 10 minutes. Thereafter, the film was taken out, washed sufficiently with running water, and the infrared absorption spectrum was measured.
O ₂ F type film potassium hydroxide solution, then match the spectrum of the film of the -SO ₃ H type polymer obtained by treatment with an acid. Thereby, the intermediate polymer is-
It was confirmed that it was converted to SO ₃ H form. The dimensions of the film after conversion in the dry state were 5.1 cm or less on both sides, and the dimensional change was smaller than before the acid treatment.

[0033]

Comparative Example 1 20 g of the same -SO ₂ F type powder as used in Example 1 was immersed in a mixed solution of 30 g of potassium hydroxide, 20 g of dimethyl sulfoxide and 50 g of water, and heated at 90 ° C. for 2 hours. Wash with water and then add 8
Heat treatment at 0 ° C. for 3 hours, washing with water, and drying to give -S
O ₃ H type powder was obtained. When the thermal decomposition behavior of this powder was measured by the same method as in Example 1, the temperature at which the weight was reduced by 5% was 280 ° C. Was thermoformed in such -SO ₃ H type polymer in the same manner as in Example 1, colored brown and did not obtain a smooth film. Therefore, -SO ₃ H type polymer was found to not have a heat resistance suitable for molding. Also, -SO ₂ F type film potassium (5 cm × 5.0 cm square in the dry state) hydroxide 30g, dimethyl sulfoxide 20g, water 50g
And heat-treated at 90 ° C for 2 hours, washed with water, and further heat-treated at 80 ° C for 1 hour in 2N sulfuric acid.
Washed with water, it converted to -SO ₃ H type by drying,
After drying and measuring the size, it was 5.6 cm × 5.5, and was largely swollen.

[0034]

Embodiment 2 The following formula (11):

Embedded image Was placed in 190 ml of triethylamine and 10 ml of water, and the mixture was heated and refluxed in an oil bath at 80 ° C. for 2 hours. Thereafter, the powder was filtered, thoroughly washed with running water, dried, and dried at a load of 50 kgf / cm ² by a flat plate press heated to 280 ° C.
After pressurizing for minutes, an almost colorless and transparent film was obtained. Measurement of the infrared absorption spectrum of this film, absorption peaks caused by -SO ₂ F disappears, -N
An absorption peak due to CH ₂ CH ₃ appeared.

This film was immersed in 30 ml of 3N sulfuric acid and heated and refluxed in a 130 ° C. water bath for 10 minutes. Thereafter, the film was taken out, washed sufficiently with running water, and the infrared absorption spectrum was measured. The spectrum was obtained by treating a film made of an untreated polymer with a potassium hydroxide solution and then an acid to obtain -SO ₃ H type. It was in perfect agreement with the spectrum of the polymer film. Thus, the intermediate polymer to have been converted into -SO ₃ H type was confirmed.

[0036]

Example 3 5 g of the same -SO ₂ F type polymer powder as used in Example 1 was placed in a microbomb with 100 ml of 20% aqueous ammonia and heated in a 90 ° C. oil bath for 2 hours. Thereafter, the powder was filtered, washed sufficiently with running water, and then washed with a flat plate press heated to 320 ° C.
When pressed under a load of kgf / cm ² for 1 minute, an almost colorless and transparent film was obtained. Measurement of the infrared absorption spectrum of this film, absorption peaks caused by -SO ₂ F disappears, 3000cm ^-1 ~3500cm ^-1
Absorption due to -NH appeared around. In addition, this film had low adhesion between the films, and was easily separated when one of the films was lifted by hand after the two films were overlapped and lightly pressed.

The powder after the treatment was pressed at 50 kgf / cm ² by a flat plate press heated to 320 ° C.
Upon heating for a minute, it turned very dark brown.
However, when the infrared absorption spectra before and after heating were compared, the spectra were almost completely different. Therefore, the polymer after this treatment seems to have relatively good heat resistance. The film was immersed in 30 ml of 3N sulfuric acid and heated and refluxed in a 130 ° C. water bath for 2 hours. Then the film was taken out, after thoroughly washed with running water, was subjected to infrared spectrum, -SO ₃ H type this spectrum obtained by processing the film of the -SO ₂ F form potassium hydroxide solution, then with acid It was consistent with the spectrum of the polymer film. This allows
Intermediate polymer was confirmed to have been converted to -SO ₃ H type.

[0038]

Example 4 5 g of the same -SO ₂ F type polymer powder as used in Example 1 was mixed with 95 ml of n-butylamine and 5 ml of water.
The mixture was placed in a mixed solution (ml) and heated under reflux in an oil bath at 80 ° C for 2 hours. Thereafter, the pellets were taken out, washed thoroughly with running water, and then heated to 270 ° C. with a flat plate press at 50k.
When pressed under a load of gf / cm ² for 1 minute, a very slightly yellow colored film was obtained. When the infrared absorption spectrum of this film was measured, it was found that -SO ₂ F
Absorption peak attributable disappeared in, -NCH ₂ CH ₂ CH
An absorption peak due to ₂ CH ₃ appeared. The film was immersed in 30 ml of 3N sulfuric acid and heated and refluxed in a 130 ° C. water bath for 10 minutes. Then take out the film,
After thoroughly washed with running water, was subjected to infrared spectrum, -SO the spectrum obtained by processing the film of the -SO ₂ F form potassium hydroxide solution, then with acid
The spectrum was consistent with that of the film of the ₃ H-type polymer. Thus, the intermediate polymer to have been converted into -SO ₃ H type was confirmed.

[0039]

Embodiment 5 Same as in Example 1, -SO_TwoF type
Of polymer powder (5 g) in 50 ml of diethylamine and 0.1 ml of water.
2 ml of the mixed solution, and added in a 70 ° C. oil bath for 2 hours.
Heated to reflux. After that, remove the pellet and run it with running water.
After washing with water, the plate was heated to
kgf / cm^TwoPressing for 1 minute with a load of
A yellow colored film was obtained. Of this film
When the infrared absorption spectrum was measured, -SO_TwoTo F
Absorption peak disappeared, and -NCH_TwoCH _ThreeDue to
Absorption peak appeared. Put this film in 3N sulfuric acid
Immerse in 0ml and heat in 130 ℃ water bath for 10 minutes
Refluxed. After that, remove the film and run it with running water.
After washing, the infrared absorption spectrum was measured.
The vector is -SO_TwoDissolve F-type film with potassium hydroxide
-SO obtained by treatment with liquid and then acid_ThreeH-type polymer
Of the film. This allows for intermediate
Body polymer is -SO_ThreeIt was confirmed that it was converted to H-type
Was.

[0040]

Example 6 In a 200-ml stainless steel pressure-resistant container, the following formula (12):

Embedded image 15g, 30g of HFC43
-10mee and (CF ₃ CF ₂ CF
₂ COO) ₂ in 5% HFC43-10mee solution 0.6
g, the inside of the container was sufficiently purged with nitrogen, and then pressurized to 0.8 MPa with vinylidene fluoride (VdF). VdF as appropriate so as to maintain the internal pressure at 0.8 MPa while stirring at 25 ° C.
Was additionally press-fitted. After reacting for 5 hours, the pressure was released to obtain a cloudy liquid. Methanol was added to this liquid to precipitate a solid, which was filtered, washed with methanol, and dried to obtain 2.0 g of a white solid. This solid was dissolved in acetone and ¹⁹ F-NMR
As a result of measuring the spectrum, it was confirmed that the copolymer was a vinyl monomer of the above formula (12): VdF = 1: 3.5. This -SO ₂ F type polymer was immersed in a mixed solution of 50 ml of triethylamine, 50 ml of acetone and 50 ml of water, heated and refluxed in a 60 ° C. water bath, washed sufficiently with running water, and then measured for infrared absorption spectrum. As a result, the absorption peak due to SO ₂ F disappeared. The flakes were heated with a flat plate press heated to 200 ° C for 5 minutes.
When pressed under a load of 0 kgf / cm ² for 1 minute, a slightly yellow colored film was obtained. The film was further immersed in 30 ml of 3N sulfuric acid and heated and refluxed in a 130 ° C. water bath for 1.5 hours. Then the film was taken out, after thoroughly washed with running water, was measured infrared absorption spectrum, it is a film of -SO ₃ H type is confirmed.

[0041]

According to the method for producing a sulfonic acid group-containing polymer of the present invention, a polymer having low tackiness can be used as a precursor of a sulfonic acid group-containing polymer film. Is very useful as a method for producing a membrane for a fuel cell.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F073 AA27 BA15 BB01 EA32 EA33 EA34 EA35 EA37 EA38 4J100 AC26P AE38Q AP01Q BA56H BA56Q BA57Q BB18Q CA04 CA31 DA01 EA00 HA25 HB25 HB26 HB44 HCB HE14 HC

Claims (3)

[Claims] 1. The following general formula (1): ## STR00001 ## -R _f --SO ₃ H (1) (In the above general formula (1), R _f represents a perfluoroalkylene group having 1 to 4 carbon atoms.) A method for producing a membrane comprising a polymer containing a sulfonic acid-containing group in the side chain represented by the following general formula (2): -R _f -SO ₂ F (2) (2) wherein R _f is the same as in the above general formula (1)) a step of contacting a polymer containing a substituent represented by the general formula (1) with an amine compound in the presence of water; A method of sequentially forming a polymer by melt-forming a film; and 3) treating the obtained film with an acid. 2. The method for producing a polymer according to claim 1, wherein the side chain having a sulfonic acid-containing group has the following general formula (3): (Wherein m is 0 or 1, and n is 2 or 3 in the general formula (3)), wherein the method for producing a membrane comprising a polymer containing a sulfonic acid group in a side chain is characterized by the following formula. 3. The method for producing a polymer according to claim 1, wherein the polymer obtained by the treatment has a molecular weight per sulfonic acid group (Equivalent).
(weight) is from 400 to 1500, a method for producing a membrane comprising a polymer containing a sulfonic acid group in a side chain.