JP2013114974A - Method of manufacturing polymer electrolyte membrane having characteristic improved by ultraviolet irradiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte membrane with high performance that can attain both durability and bondability to an electrode, and a method of manufacturing the same.SOLUTION: There is provided a hydrocarbon-based solid polymer electrolyte membrane having been subjected to ultraviolet irradiation processing, the hydrocarbon-based solid polymer electrolyte membrane being characterized in being found through IR analysis in an ATR method to have changed in absorption strength ratio I/Iby 10% or more through the ultraviolet irradiation.

Description

  The present invention relates to a method for producing a polymer electrolyte membrane suitable for an electrolyte used in a polymer electrolyte fuel cell.

Solid polymer fuel cells (PEFCs) and direct methanol fuel cells (DMFCs) that use polymer membranes as polymer electrolyte membranes are portable and can be miniaturized. Applications to power generation systems and power supplies for portable devices are being promoted. Currently, perfluorocarbon sulfonic acid polymer membranes represented by Nafion (registered trademark) manufactured by DuPont of the United States are widely used as polymer electrolyte membranes.
However, since these membranes are softened at 100 ° C. or higher, the operating temperature of the fuel cell is limited to 80 ° C. or lower. Increasing the operating temperature has various advantages such as energy efficiency, downsizing of the apparatus, and improvement of catalytic activity, and therefore a polymer electrolyte membrane with higher heat resistance is required.

  As a heat-resistant polymer electrolyte membrane, a sulfonated polymer obtained by treating a heat-resistant polymer such as polysulfone or polyetherketone with a sulfonating agent such as fuming sulfuric acid is known (for example, Non-Patent Document 1). However, it is generally difficult to control the sulfonation reaction with a sulfonating agent. For this reason, the degree of sulfonation becomes excessive or excessive. In addition, there is a problem that the polymer is easily decomposed during sulfonation, and uneven sulfonation is likely to occur.

For this reason, use of a polymer polymerized from a monomer having an acidic group such as a sulfonic acid group as a polymer electrolyte membrane has been studied. For example, Patent Document 1 discloses a polymer electrolyte obtained by reaction of 4,4′-dichlorodiphenylsulfone-3,3′-disulfonic acid soda and 4,4′-dichlorodiphenylsulfone with 4,4′-biphenol. Copolymers that can be obtained are disclosed. The polymer electrolyte membranes containing these polymers as constituent components have less sulfonic acid group heterogeneity as in the case of using the sulfonating agent described above, and the amount of sulfonic acid group introduced and the molecular weight of the polymer are easy to control. It was.
However, a film containing a biphenyl group is not softened even at 250 ° C. or higher, and it is difficult to join the electrode with a hot press method. In order to solve this, use of an aromatic polymer electrolyte having a glass transition temperature (Tg) in the range of 100 to 250 ° C. as a polymer electrolyte membrane has been studied. For example, Patent Document 2 discloses a copolymer having a Tg in the range of 130 to 220 ° C. as a polymer electrolyte. However, the polymer substituted with the biphenyl group has a problem that the durability is lowered.

US Patent Application Publication No. 2002/0091225 JP 2006-342252 A

F. Lufrano et al., “Sulfolated Polysulfone as Prombling Membranes for Polymer Electrolite Fuel Cells,” Science), (USA), John Wiley & Sons, Inc., 2000, 77, p. 1250-1257

  In view of the above-described problems of the prior art, the present invention has been aimed at providing a high-performance polymer electrolyte membrane that can achieve both durability and bondability with an electrode and a method for producing the same. .

  As a result of intensive studies to achieve the above object, the inventors of the present invention include a film containing a polyarylene ether-based compound characterized by including a component represented by the general formula (2) together with the general formula (1) It was found that a polymer electrolyte membrane having excellent bondability with an electrode and excellent durability can be obtained by irradiating the film with ultraviolet rays, and the present invention has been completed.

(1)
Ar represents a divalent aromatic group, Y represents a sulfonic acid group or a ketone group, and X represents H or a monovalent cation species.

(2)
Ar ′ represents a divalent aromatic group.

  By using the production method of the present invention, it is possible to obtain a polymer electrolyte membrane that achieves both good bondability with the electrode and durability.

Hereinafter, the method for producing a polymer electrolyte membrane according to the present invention will be specifically described.
[Polymer electrolyte]
The polymer electrolyte of the present invention is a polyarylene ether compound characterized by containing a constituent represented by the general formula (2) together with the general formula (1).

Ar represents a divalent aromatic group, Y represents a sulfonic acid group or a ketone group, and X represents H or a monovalent cation species.

Ar ′ represents a divalent aromatic group.

  The polymer electrolyte used in the present invention includes a random block copolymer, a segmented block copolymer, a polymer having a long chain or short chain branch (for example, a comb polymer), a star polymer, etc. It may have a higher order structure. In particular, the use of a copolymer that can form a co-continuous structure by phase separation of a hydrophilic part and a hydrophobic part, such as a segmented block copolymer, improves the durability and proton conductivity of the polymer electrolyte membrane. Is preferable. Examples of such a segmented block copolymer include a copolymer of a hydrophilic segment having an acidic group or a salt thereof and a hydrophobic segment having no acidic group and a salt thereof. Such a segmented block copolymer can be obtained, for example, by polymerizing an oligomer constituting the segment directly or via another compound.

When the polymer electrolyte used in the present invention is an aromatic polymer mainly composed of a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2), The molar ratio is preferably in the range of 7:93 to 70:30. The molar ratio of 7:93 means that when the number of moles of the repeating unit represented by the general formula 1 is 7, the number of moles of the repeating unit represented by the general formula 2 is 93. When the number of repeating units represented by the general formula 1 is larger than the molar ratio of 70:30, the fuel permeability when used as a polymer electrolyte membrane may increase, which is not preferable. When the number of repeating units represented by the general formula 1 is less than the molar ratio of 7:93, it is not preferable because the proton conductivity when the polymer electrolyte membrane is made decreases and the resistance increases. The molar ratio is more preferably in the range of 10:90 to 50:50, and still more preferably in the range of 10:90 to 40:60.
In the aromatic polymer, the bonding mode of each repeating unit represented by each general formula is not particularly limited, and examples thereof include random bonding, alternating bonding, and bonding in a continuous block structure. The aromatic polymer may be composed of a single bonding mode or a combination of two or more bonding modes.

[Preferred example of production method of polymer electrolyte]
The aromatic polymer having a repeating unit represented by the general formula (1) or the like includes monomers represented by the following general formulas 3 to 5 (for example, (activated) dihalogen aromatic compounds, aromatic diols, aromatics Can be produced by a known method (for example, polymerization reaction by a known aromatic nucleophilic substitution reaction in the presence of a basic compound). Further, it is preferable to further use 4,4′-biphenol represented by the general formula 6 because physical characteristics such as film form stability are improved.

[In the general formulas 3 to 6, Z ₁ and Z ₃ are each independently any one of Cl atom, F atom, I atom and Br atom, Z ₂ is O atom, S atom, —CH ₂ — group. , —C (CH ₃ ) ₂ — group, —C (CF ₃ ) ₂ — group, cyclohexylene group, or direct bond, n1 represents an integer of 1 or more. X and Y are the same as X and Y, respectively. ]

Specific examples of the monomer represented by the general formula 3 include 3,3′-disulfo-4,4′-dichlorodiphenyl sulfone, 3,3′-disulfo-4,4′-difluorodiphenyl sulfone, 3,3 ′. -Disulfo-4,4'-dichlorodiphenyl ketone, 3,3'-disulfo-4,4'-difluorodiphenyl ketone, 3,3'-disulfobutyl-4,4'-dichlorodiphenyl sulfone, 3,3'-disulfobutyl Dihalogen aromatic compounds such as -4,4'-difluorodiphenyl sulfone, 3,3'-disulfobutyl-4,4'-dichlorodiphenyl ketone, 3,3'-disulfobutyl-4,4'-difluorodiphenyl ketone, and these In which the sulfonic acid group forms a salt with a monovalent cation. Specific examples of the cation are as described above.
Examples of the compound represented by the general formula 3 in which the sulfonic acid group is a salt include sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, 3,3′-disulfone Sodium salt-4,4′-difluorodiphenylsulfone, sodium 3,3′-disulfonate-4,4′-dichlorodiphenylketone, sodium 3,3′-disulfonate-4,4′-difluorodiphenylketone, 3, 3′-potassium disulfonate-4,4′-dichlorodiphenylsulfone, 3,3′-potassium disulfonate-4,4′-difluorodiphenylsulfone, 3,3′-potassium disulfonate-4,4′-dichlorodiphenyl Examples thereof include ketones and potassium 3,3′-disulfonate-4,4′-difluorodiphenyl ketone.

  Specific examples of the monomer represented by the general formula 4 include 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, and 2,2-bis (4-hydroxyphenyl) hexafluoropropane. Bis (4-hydroxyphenyl) sulfide (4,4′-thiobisphenol), 4,4′-dihydroxydiphenyl ether, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl sulfone (bisphenol) S), aromatic diols such as a terminal hydroxyl group-containing phenylene ether oligomer (having a structure represented by the following general formula 7) and the like, and in particular, bis (4-hydroxyphenyl) sulfide, 1,1-bis (4-hydroxyphenyl) cyclohexane, terminal hydroxyl Containing phenylene ether oligomer are preferred.

[In General Formula 7, n is an integer of 1 or more, and a mixture of a plurality of components with different n may be used. ]

The monomer represented by the general formula 4 enhances the flexibility of the polymer electrolyte membrane, and brings about effects such as prevention of breakage against deformation and improvement in bondability with an electrode due to a decrease in glass transition temperature.
Examples of the monomer represented by the general formula 5 include monomers having a leaving group in a nucleophilic substitution reaction such as halogen and nitro group on the same aromatic ring and an electron-withdrawing group that activates it. Specific examples include activated dihalogen aromatic compounds such as 2,6-dichlorobenzonitrile and 2,6-difluorobenzonitrile, but are not limited thereto.

Examples of the monomer represented by the general formula 6 include aromatic diols such as 4,4′-biphenol and 4,4′-dimercaptobiphenol, and 4,4′-biphenol is particularly preferable.
In the present invention, various other activated dihalogen aromatic compounds, dinitro aromatic compounds, bisphenol compounds, and bisthiophenol compounds can be used in combination with the monomers represented by the general formulas 3 to 6 as monomers. Examples of the bisphenol compound or bisthiophenol compound include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, and bis (4-hydroxyphenyl). Sulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxy) -3,5-dimethylphenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (4-hydroxy-2,5-dimethylphenyl) methane, bis (4-hydroxyphenyl) phenylmethane, Hydroquinone, resorcin, bis (4-hydroxyphenyl) ketone, 1,4-ben Njichioru, 1,3 benzenedithiol, phenolphthalein, 10- (2,5-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphatonin phenanthrene-10-oxide, and the like. In addition, various aromatic diols or various aromatic dithiols that can be used for polymerization of polyarylene ether compounds by aromatic nucleophilic substitution reaction may be used.

  In addition, as a raw material of the polymer of another embodiment constituting the polymer electrolyte of the present invention, aromatic tetraamino compounds such as 3,3 ′, 4,4′-tetraaminodiphenylsulfone, 3,3′-diaminobenzidine and the like And aromatic dicarboxylic acids having an ionic group such as monosodium 2,5-dicarboxybenzenesulfonate and 3,5-dicarboxyphenylphosphonic acid. Polycondensation can be performed using these monomers to obtain a polyazole polymer electrolyte such as polybenzimidazole.

The molecular weight of the polymer electrolyte is not particularly limited, but it is preferable that the number average molecular weight measured by using gel permeation chromatography with polyethylene glycol as a standard is in the range of 10,000 to 500,000. If it is less than 10,000, the physical properties of the film may deteriorate. The larger the molecular weight, the better from the viewpoint of mechanical properties, but if it is too large, the solid content concentration of the polymer electrolyte composition may be lowered when the polymer electrolyte membrane is produced using the polymer electrolyte composition. May not be obtained, and there may be a problem in removing the solvent.
The logarithmic viscosity of the polymer electrolyte composition is preferably in the range of 0.1 to 10.0 dL / g, and more preferably in the range of 0.3 to 5.0 dL / g. If the logarithmic viscosity is 0.1 dL / g or less, it may be difficult to form a film. On the other hand, if the logarithmic viscosity is 10.0 dL / g or more, the viscosity of the composition may become too high or the concentration may become too low, making film formation difficult.
The softening temperature of the polymer electrolyte is preferably 120 ° C. or higher, and more preferably 140 to 300 ° C.

[Method of forming polymer electrolyte composition]
The polymer electrolyte composition of the present invention can be formed into a molded body such as a fiber or a film by any method such as extrusion, spinning, rolling or casting. Among these, it is preferable to mold from a solution dissolved in an appropriate solvent.
A method of obtaining a molded body from a solution can be performed using a conventionally known method. For example, by heating, drying under reduced pressure, mixing with a solvent (good solvent) that dissolves the polymer electrolyte and the biphenyl derivative, the polymer electrolyte and biphenyl derivative can be mixed with a solvent that does not dissolve (poor solvent), etc. A good solvent can be removed from the molecular electrolyte composition to obtain a molded body. The poor solvent is preferably distilled off by heating or drying under reduced pressure. At this time, it may be formed into various shapes such as a fiber shape, a film shape, a pellet shape, a plate shape, a rod shape, a pipe shape, a ball shape, and a block shape in a form combined with other compounds as necessary. it can. When combined with a compound having a similar dissolution behavior, it is preferable in that good molding can be achieved. The acidic group in the molded product thus obtained may contain a salt form with a monovalent cation, but is converted to a free acidic group by acid treatment as necessary. You can also.

[Production method of polymer electrolyte membrane]
A polymer electrolyte membrane can also be produced from the polymer electrolyte composition of the present invention. The polymer electrolyte membrane may be not only the polymer electrolyte composition of the present invention but also a composite membrane with a support such as a porous membrane, a nonwoven fabric, fibrils, and paper. The obtained polymer electrolyte membrane can be used as a polymer electrolyte membrane for fuel cells.
The most preferable method for forming the polymer electrolyte membrane is a cast from a polymer electrolyte composition containing a good solvent. The polymer electrolyte membrane is obtained by removing the good solvent from the cast solution as described above. Can be obtained. The removal of the poor solvent is preferably by drying from the uniformity of the polymer electrolyte membrane. Moreover, in order to avoid decomposition | disassembly and alteration of a polymer electrolyte or a solvent, it can also be dried at the lowest possible temperature under reduced pressure. Further, when the viscosity of the polymer electrolyte composition is high, when the substrate or the composition is heated and cast at a high temperature, the viscosity of the composition is lowered and can be easily cast. The thickness of the cast film of the composition is not particularly limited, but is preferably 10 to 1000 μm. More preferably, it is 50-500 micrometers. If the cast membrane is thinner than 10 μm, it tends to be unable to maintain the form as a polymer electrolyte membrane, and if it is thicker than 1000 μm, a non-uniform polymer electrolyte membrane tends to be easily formed. As a method for controlling the thickness of the cast film, a known method can be used. For example, the thickness of the cast film can be controlled by the amount and concentration of the composition to be cast, such as by using an applicator or doctor blade to make the thickness constant, or using a glass petri dish to make the cast area constant. can do. The cast film can obtain a more uniform film by adjusting the solvent removal rate. For example, when heating, it is preferable to lower the evaporation rate at a low temperature in the first stage. In addition, when the cast film is immersed in a poor solvent such as water, the cast film is allowed to solidify at a suitable time before being immersed in an air atmosphere or an inert gas atmosphere. Can be adjusted.

[Polymer electrolyte membrane]
The polymer electrolyte membrane of the present invention can have any thickness depending on the purpose, but is preferably as thin as possible from the viewpoint of proton conductivity. Specifically, the thickness is preferably 5 to 200 μm, more preferably 5 to 100 μm, and most preferably 20 to 80 μm. If the thickness of the polymer electrolyte membrane is less than 5 μm, the handling of the polymer electrolyte membrane becomes difficult and a short circuit or the like tends to occur when a fuel cell is produced. If the thickness is greater than 200 μm, the electrical resistance value of the polymer electrolyte membrane is high. Therefore, the power generation performance of the fuel cell tends to decrease. When used as a polymer electrolyte membrane, the acidic group in the membrane may contain a monovalent cation salt, but can be converted to a free acidic group by an appropriate acid treatment. In this case, it is also effective to immerse the obtained film in an aqueous solution of sulfuric acid, hydrochloric acid or the like with or without heating. The proton conductivity of the polymer electrolyte membrane is preferably 1.0 × 10 ⁻³ S / cm or more. When the proton conductivity is 1.0 × 10 ⁻³ S / cm or more, a good output tends to be obtained in a fuel cell using the polymer electrolyte membrane, and 1.0 × 10 ⁻³ S If it is less than / cm, the output of the fuel cell tends to decrease.

[Surface treatment by UV irradiation]
The polymer electrolyte membrane obtained by the above method is irradiated with ultraviolet rays. As the apparatus, an apparatus that can irradiate light having a wavelength of 100 nm to 300 nm can be used. Moreover, the wavelength of an ultraviolet-ray can use the light source which can generate | occur | produce a single wavelength or several wavelengths.
For example, when a device capable of irradiating light of 185 nm and 254 nm, such as a low-pressure mercury lamp, is used, the light of 185 nm is absorbed by oxygen and generates ozone. When 254 nm light is absorbed by this ozone, excited oxygen atoms are generated. By making the active oxygen derivative produced | generated through the above-mentioned process act on the film surface, the surface of a polymer electrolyte membrane can be hydrophilized.
In addition, it is said that a light source of 185 nm can directly cut an atomic bond of an organic substance, and the effect of hydrophilization treatment can be obtained by irradiating this light as well.
The center wavelength of the ultraviolet light of the dielectric barrier discharge excimer lamp in which the xenon gas is sealed is 172 nm. This light is directly absorbed by oxygen in the atmosphere and can generate excited oxygen atoms and ozone, and 172 nm light has higher photon energy than 185 nm light. For this reason, even if this apparatus is used, the surface of the polymer electrolyte membrane can be easily hydrophilized.
The residue on the surface of the polymer electrolyte membrane modified by the ultraviolet treatment is oxidized and converted into a compound such as carbon dioxide or water, which can be scattered and removed.
The ultraviolet treatment can be performed on one side or both sides of the polymer electrolyte membrane. Further, such treatment may be either in the process of forming the polymer electrolyte membrane (in the middle of film formation) or after the film formation. Conditions such as processing time and processing temperature are not particularly limited because they vary depending on the type of material, but can be arbitrarily selected according to proton conductivity, bonding properties at the time of electrode bonding, and other characteristic balances. Note that characteristics such as film thickness and ion exchange capacity do not substantially vary before and after the surface treatment.
The absorption intensity I _{1585 cm −1} of IR analysis by ATR method is derived from a carboxyl group, and it is considered that the carboxyl group is added after the ultraviolet treatment, and the affinity with the electrode binder is improved.

[Membrane electrode assembly]
By joining the polymer electrolyte membrane of the present invention described above to an electrode, a joined body (membrane electrode assembly) of the polymer electrolyte membrane of the present invention and an electrode can be obtained. As a method for producing this joined body, a conventionally known method can be used. For example, a method of applying an adhesive to the electrode surface and bonding the polymer electrolyte membrane and the electrode, or a polymer electrolyte membrane and the electrode There is a method of heating and pressurizing (hot pressing method). The polymer electrolyte membrane of the present invention has a high affinity with the electrode because the surface is hydrophilized by ultraviolet rays. For this reason, a membrane electrode assembly can be easily produced if a hot press method is adopted. The heating temperature in the hot press method is preferably 100 to 250 ° C., and the pressure is preferably 5 to 10 MPa.

[Fuel cell]
A fuel cell can also be produced using the membrane electrode assembly described above. Since the polymer electrolyte membrane of the present invention is excellent in processability, proton conductivity, and durability, it can be easily produced, has a good output, and can provide a fuel cell excellent in durability. The polymer electrolyte membrane of the present invention is suitable not only for methanol direct fuel cells (DMFC) using methanol as fuel but also for polymer electrolyte fuel cells (PEFC) using hydrogen as fuel. Further, it is also suitable for a fuel cell of a type in which hydrogen is extracted from a hydrocarbon such as methanol, gasoline, ether or the like by a reformer.

EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples. Various measurements were performed as follows.
<IR measurement>
ATR method (single reflection ATR attachment: Thunderdome (manufactured by THERMO SPECTRA TECH), IRE: Ge, incident angle: 45 °, resolution: FT-IR equipment FRS 7000e (infrared microscope: UMA600) manufactured by Varian The IR spectrum of the polymer electrolyte membrane surface was measured at 4 cm ⁻¹ and the number of integrations: 128).
An IR spectrum of the polymer electrolyte membrane was measured by a transmission method (resolution: 4 cm ⁻¹ , integration number: 128 times) using an FT-IR apparatus FTS 60A / 896 manufactured by Varian.

<Ion exchange capacity>
100 mg of the dried polymer electrolyte membrane was immersed in 50 mL of 0.01N NaOH aqueous solution and stirred overnight at 25 ° C. Then, neutralization titration with 0.05N HCl aqueous solution was performed. For neutralization titration, a potentiometric titrator (“COMMITE-980”; manufactured by Hiranuma Sangyo Co., Ltd.) was used. The ion exchange equivalent was calculated by the following formula.
Ion exchange capacity [meq / g] = (10-titer [mL]) / 2

<Proton conductivity>
A platinum wire (diameter: 0.2 mm) is pressed on the surface of a strip-shaped film sample on a probe for self-made measurement (made of polytetrafluoroethylene), and a constant temperature / humidity oven (“LH-” at 80 ° C. and 95% RH) is used. 20-01 "(manufactured by Nagano Kagaku Kikai Seisakusho Co., Ltd.), and the impedance between the platinum wires was measured by a frequency response analyzer (FREQENCY RESPONSE ANALYSER 1250; manufactured by SOLARTRON). Measured by changing the distance between the electrodes, and calculated the conductivity by canceling the contact resistance between the film and the platinum wire from the slope of the distance measured between the electrodes and the resistance measurement value estimated from the CC plot. did.
Conductivity [S / cm] = 1 / (film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm])

<Method for evaluating membrane electrode bondability>
A platinum catalyst supported on fibrous carbon was joined to one side of the polymer electrolyte membrane by a hot press method. This polymer electrolyte membrane electrode assembly (abbreviation: MEA) was read and compared using a scanner (manufacturer: FUJI XEROX, model: Docu Center Color f450) under the conditions of gray scale and 600 dpi.

Comparative Example 1 [Production of polymer electrolyte membrane made of polymer electrolyte]
<Production of polymer electrolyte precursor>
The reactor was charged with 778 parts of sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (S-DCDPS), 553 parts of 2,6-dichlorobenzonitrile (DCBN), 4,4′-biphenol (BP 893 parts, 763 parts of potassium carbonate and 5631 parts of N-methyl-2-pyrrolidone (NMP) were added and reacted at 200 ° C. for 10 hours in a nitrogen atmosphere. After allowing to cool, the polymer was precipitated in water as a strand, and the resulting polymer was washed 5 times with 10 L of water and then dried to obtain a polymer electrolyte precursor. This polymer electrolyte precursor had a logarithmic viscosity of 1.25 dL / g, an ionic group amount of 1.27 (meq / g), and a cation substitution rate (mol%) of 100%.
<Manufacture of polymer electrolyte precursor film>
A precursor solution having a solid content concentration of 24% by mass was prepared using NMP as a solvent. Next, on a non-adhesive polyethylene terephthalate film as a support, a blade coater is set to have a width of 1000 mm and a clearance of 300 μm, and the precursor solution is continuously cast at a temperature of 25 ° C., and dried at 100 ° C. for 60 minutes. Thus, a polymer electrolyte precursor film 1 having a residual amount of NMP of 20% by mass was produced.
The obtained polymer electrolyte precursor film 1 was continuously immersed in water at 25 ° C. for 20 minutes without peeling off from the support, and a polymer electrolyte precursor film having a residual amount of NMP of 0.4% by mass. 2 was produced.
<Manufacture of polymer electrolyte membrane>
The obtained polymer electrolyte precursor film 2 was continuously applied to sulfuric acid aqueous solution tanks 1 and 2 filled with 100 L of a 20 mass% sulfuric acid aqueous solution (pKa = −3.0) at 30 ° C. without peeling from the support. The polymer electrolyte membrane was manufactured by dipping for 20 minutes.
While immersed, the sulfuric acid aqueous solution tank 2 to which the polymer electrolyte precursor film later contacts is supplied with 1 L / min of a new sulfuric acid aqueous solution, and the sulfuric acid aqueous solution tank 1 to which the polymer electrolyte precursor film contacts first is supplied. Supplied 1 L / min of the solution in the sulfuric acid aqueous solution tank 2, and extracted 1 L / min of the liquid from the sulfuric acid aqueous solution tank 1 as a waste liquid.
<Cleaning of polymer electrolyte membrane>
Next, without removing the polymer electrolyte membrane from the support, washing was performed three times for 5 minutes with pure water at 30 ° C. and pH 7 continuously. Thereafter, the washed polymer electrolyte membrane was dried at 40 ° C. for 3 minutes without peeling off from the support to obtain a 30 μm thick polymer electrolyte membrane (water content: 10%) laminated on the support.

Comparative Examples 2-3 [Production of Plasma Irradiated Polymer Electrolyte Membrane]
The polymer electrolyte membrane obtained in Comparative Example 1 was irradiated with UV using SKB1102N-01 manufactured by Run Technical Service. Plasma was irradiated using a Corona Station (Plasma) Type PCCE 003-0-1KB4 (linear plasma) manufactured by Sophthal. The electrode width was 200 mm, the distance between the electrode and the film was 2 mm, and the output was 400 W. The conveyance speed was 5 m / min (Comparative Example 2) and 1 m / min (Comparative Example 3).

Examples 1 to 3 [Production of UV-irradiated polymer electrolyte membrane]
The polymer electrolyte membrane obtained in Comparative Example 1 was irradiated with UV using SKB1102N-01 manufactured by Run Technical Service. The distance between the light source and the polymer electrolyte membrane was fixed at 5 cm. The irradiation time was 30, 60, and 120 seconds. Illuminance, 254 nm of about 205mW / cm ^2, 185nm was about 10 mW / cm ^2.
Table 1 shows the evaluation results of the polymer electrolyte membranes obtained in the examples and comparative examples.

  From Table 1, the polymer electrolyte membrane produced by the production method of the present invention was excellent in electrode bondability despite exhibiting proton conductivity equivalent to that of the comparative polymer electrolyte membrane not irradiated with UV. It turns out that it is a polymer electrolyte membrane.

  The method for producing a polymer electrolyte membrane of the present invention facilitates the production of a polymer electrolyte membrane and an electrode assembly, and can provide a more stable membrane electrode assembly, which contributes to industrial development. is there.

Claims (6)

This is a hydrocarbon-based solid polymer electrolyte membrane that has been subjected to ultraviolet irradiation treatment. As a result of IR analysis by ATR method before and after irradiation with ultraviolet rays, the absorption intensity ratio I _{1685 cm -1} / I _{3500 cm -1} is A hydrocarbon-based solid polymer electrolyte membrane characterized by a change of 10% or more from the previous one. The said polymer electrolyte membrane contains the structural component shown by General formula (2) with General formula (1), The hydrocarbon type solid polymer electrolyte membrane characterized by the above-mentioned.

Ar represents a divalent aromatic group, Y represents a sulfonic acid group or a ketone group, and X represents H or a monovalent cation species.

Ar ′ represents a divalent aromatic group. 3. The method for producing a hydrocarbon-based solid polymer electrolyte membrane according to claim 1 or 2, wherein after the formation of the hydrocarbon-based solid polymer electrolyte membrane, the obtained membrane is irradiated with ultraviolet rays.   4. The method for producing a hydrocarbon-based solid polymer electrolyte membrane according to claim 2, wherein the wavelength of the ultraviolet ray is in the range of 100 to 300 nm.   3. A membrane / electrode assembly comprising the hydrocarbon-based solid polymer electrolyte membrane according to claim 1 or 2 and an electrode.   A fuel cell comprising the membrane electrode assembly according to claim 5.