JP2008277241A - Method of manufacturing polymer electrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a polymer electrolyte membrane in which unevenness of thickness, wrinkles, and irregularities are hardly caused and which is improved in morphology stability of membrane and stability of membrane characteristics. <P>SOLUTION: The method of forming the polymer electrolyte membrane includes: a spread step (A1) in which ionic group-contained polymer electrolyte solution is flowed and spread on a support to form a spread membrane; a drying step (A2) of evaporating solvent from the spread membrane; and a desolvation step (A3) of extracting the solvent by a liquid in which the dried membrane is mixed in a solvent of the ionic group-contained polymer electrolyte. In the method, the step (A2) and the step (A3) are carried out without separating the membrane from the support. In the drying step (A2), the polymer electrolyte membrane is dried so that it becomes a self-supporting membrane of solvent content 15-30 mass% in the range of the following formula (I) as to the relation of the coating thickness factor T of the polymer electrolyte solution and the drying speed R1 (g/m<SP>2</SP>×min.). 2≤R<SB>1</SB>×T≤56 (I), provided that R<SB>1</SB>expresses a drying speed (g/m<SP>2</SP>xmin.), T expresses a coating thickness (μm)/300(μm) of the polymer electrolyte solution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a polymer electrolyte membrane.

  In recent years, new power generation technologies with excellent energy efficiency and environmental friendliness have attracted attention. Above all, polymer electrolyte fuel cells using polymer electrolyte membranes have high energy density, and because they have features such as being easy to start and stop because of lower operating temperatures than other types of fuel cells. Developments as power supply devices for electric vehicles and distributed power generation are advancing.

  As the polymer solid electrolyte membrane, a proton conductive ion exchange membrane is usually used. In addition to proton conductivity, the polymer solid electrolyte membrane must have characteristics such as fuel permeation deterrence and mechanical strength that prevent permeation of hydrogen and the like of the fuel. It has been found that unevenness of thickness, wrinkles, and unevenness of the electrolyte membrane influence as a factor governing these characteristics.

Conventionally, as a means for eliminating wrinkles and unevenness, a method of drying by applying tension to the film has been reported (for example, Patent Document 1), but the thickness is uneven at the periphery of the fixed portion and the portion farthest from the fixed portion. There was a problem. In addition, there is a problem that wrinkles and irregularities generated in the previous process cannot be sufficiently eliminated by fixing only during drying.
In particular, a polymer solid electrolyte membrane produced by so-called solution casting, in which a solvent solution of a polymer electrolyte is cast on a support and then desolvated to form a membrane, not only stabilizes the membrane shape but also membranes. There is a need to improve the stability of the morphology and the stability of the film properties.
JP 2003-192805 A

  The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to provide a method for producing a polymer electrolyte membrane which is a stable film formation method in which unevenness in thickness, wrinkles, and unevenness is unlikely to occur, and the stability of the film morphology and film characteristics is improved. It is to be.

（ただし、Ａｒは２価の芳香族基、Ｙはスルホン基又はケトン基、ＸはＨ及び／又は１価のカチオン種、Ｚは直接結合、エーテル結合及びチオエーテル結合から選ばれる少なくとも１種である。）

（ただし、Ａｒ’は２価の芳香族基、Ｚ’は直接結合、エーテル結合及びチオエーテル結合から選ばれる少なくとも１種である。） As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have reached the present invention.
That is, this invention consists of the following structures.
[1] A casting step (A ₁ ) in which an ionic group-containing polymer electrolyte solution is cast on a support to form a cast membrane, a drying step (A ₂ ) in which a solvent is evaporated from the cast membrane, and the above It comprises a desolvation step (A ₃ ) of extracting the solvent with a liquid miscible with the solvent of the ionic group-containing polymer electrolyte, and the steps (A ₂ ) and (A ₃ ) are separated from the support by the membrane. In the method for forming a polymer electrolyte membrane carried out without peeling, the relationship between the coating thickness coefficient T of the polymer electrolyte solution and the drying rate R ₁ (g / m ² · min) in the drying step (A ₂ ) A method for forming a polymer electrolyte membrane, comprising drying until a self-supporting membrane having a solvent content of 15 to 30% by mass within the range of the following formula (I) is obtained.
2 ≦ R ₁・ T ≦ 56 (I)
(However, R ₁ : Drying rate (g / m ² · min),
T: Coating thickness of polymer electrolyte solution (μm) / 300 (μm))
[2] The desolvation rate _R 2 (g / ^{m 2} · min) in the desolvation process _{(A 3),} 1~20g / ^m in the ^2-minute, desolvation until the solvent content of less than 8% [1 ] The formation method of the polymer electrolyte membrane of description.
[3] An acid treatment step in which the polymer electrolyte membrane formed in the above [1] or [2] is attached to a support and is contacted with an inorganic acid-containing acidic solution to convert an ionic group into an acid type ( B), a method for producing a polymer electrolyte membrane comprising an acid removal step (C) for removing free acid in the acid-treated membrane and a drying step (D) for drying the acid removal membrane, ) To (D) are processed without peeling the polymer electrolyte membrane from the support. The manufacturing method of the polymer electrolyte membrane as described in any one of.
[4] A method for producing a polymer electrolyte membrane, wherein the polymer electrolyte membrane obtained in [3] has an average pore diameter of 0.1 to 10 nm by a DSC method.
[5] The ionic group-containing polymer electrolyte according to any one of [1] to [4], wherein the ionic group-containing polymer electrolyte is a polyarylene ether compound including the structural units represented by the general formula (1) and the general formula (2). A method for producing a polymer electrolyte membrane.

(However, Ar is a divalent aromatic group, Y is a sulfone group or a ketone group, X is H and / or a monovalent cationic species, Z is at least one selected from a direct bond, an ether bond and a thioether bond. .)

(However, Ar ′ is a divalent aromatic group, and Z ′ is at least one selected from a direct bond, an ether bond and a thioether bond.)

According to the present invention, in the film containing the solvent in close contact with the support, the movement and diffusion of the solvent to the film surface (opposite side of the support) can be controlled, so that the shape of the film is stabilized. The variation can be reduced, and the film characteristics can be stabilized and the variation can be reduced.
In addition, even for an ultrathin polymer electrolyte membrane having a thickness of 160 μm or less, a uniform polymer electrolyte membrane excellent in shape stability is produced with less thickness unevenness, less wrinkles and unevenness on the entire surface of the membrane. Can do. Furthermore, since the pore diameter inside the membrane can be controlled, a polymer electrolyte membrane having stable membrane characteristics, particularly permeation performance, can be produced. This is particularly effective in the case of a polymer electrolyte having a softening temperature of 90 ° C. or higher, preferably 140 to 250 ° C.

First, the step of forming the polymer electrolyte membrane of the present invention includes a casting step (A ₁ ) in which an ionic group-containing polymer electrolyte solution is cast on a support to form a casting membrane, from the casting membrane. A drying step (A ₂ ) for evaporating the solvent, and a desolvation step (A ₃ ) for extracting the solvent with a liquid miscible with the solvent of the ionic group-containing polymer electrolyte. The steps (A ₂ ) and It is important to carry out the step (A ₃ ) without peeling off the membrane from the support.
Furthermore, the relationship between the coating thickness coefficient T of the polymer electrolyte solution in the drying step (A ₂ ) and the drying rate R ₁ (g / m ² · min) measured by the method described later is within the range of the following formula (I). It is characterized by drying until it becomes a self-supporting membrane having a solvent content of 15 to 30% by mass.
2 ≦ R ₁・ T ≦ 56 (I)
(However, R ₁ : Drying rate (g / m ² · min),
T: Coating thickness of polymer electrolyte solution (μm) / 300 (μm))

In the state where R ₁ · T exceeds 56, foaming occurs, or only the surface portion of the casting membrane dries rapidly, and the subsequent removal of the solvent on the support side (inside the membrane) becomes difficult. To do. Further, if R ₁ · T is less than 2, there is a problem in terms of productivity.
The preferred range of R ₁ · T is 10 to 50. If it is within this range, it is possible to avoid the occurrence of foaming due to drying and rapid drying or roughening of the membrane surface, and to provide a polymer electrolyte membrane with excellent quality. Moreover, it is also preferable from the viewpoint of the balance between the quality of the membrane and the productivity.
When the range of R ₁ · T is 2 to 30, the average pore size (by DSC method) in the polymer electrolyte membrane is within the range of 0.1 to 10 nm, and the variation in pore size becomes small, and the membrane In addition to the morphological stability, membrane properties such as improving methanol permeation deterrence while maintaining ionic conductivity are likely to be further improved.

In order to make R ₁ · T within the above range, it is important that the solvent on the support side is smoothly diffused to the film surface without unevenness. Atmosphere temperature such as air, treatment time, air volume, wind speed, solution coating This can be achieved by selecting appropriate conditions according to the thickness, the type of solvent, the type of electrolyte polymer, the amount of ionic groups, and the like.
For example, depending on the type of solvent used, the temperature may be dried at a temperature of 100 ° C. or lower of the boiling point of the solvent used until the solvent content of the membrane is 15 to 30% by mass to obtain self-supporting property, When the solvent content of the membrane on the support side is 15 to 30% by mass, the solvent is further removed at a temperature up to 70 ° C., which is the boiling point of the solvent used, and drying is performed until self-supporting properties are obtained. Is applicable.
The wind speed is preferably a relatively gentle wind speed of 0.5 m / min or 1.0 m / min as long as the flow is perpendicular to the coating film from the viewpoint that the film surface uniformity can be easily obtained. If the flow is parallel, there is no physical collision with the surface of the coating film, and therefore any drying speed that does not cause foaming is applicable even at a wind speed of 10 m / min or 20 m / min.

Examples of the polymer electrolyte solvent in the casting step (A ₁ ) include aprotic polarities such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and hexamethylphosphonamide. A suitable solvent can be selected from alcohols such as methanol and ethanol, but is not limited thereto. A plurality of these solvents may be used as a mixture within a possible range. The compound concentration in the solution is preferably in the range of 0.1 to 50% by mass. If the compound concentration in the solution is less than 0.1% by mass, it tends to be difficult to obtain a good molded product, and if it exceeds 50% by mass, the workability tends to deteriorate.

  As the support, resin films and resin sheets such as polyethylene, polyester, nylon, and Teflon (registered trademark), glass, and the like can be used. However, the support is not particularly limited as long as it can withstand a solvent containing water and an acid. . Further, the support may be surface-modified by corona treatment or mirror treatment.

The thickness of the solution at the time of casting is not particularly limited, but is preferably 10 to 2500 μm. More preferably, it is 50-1500 micrometers, More preferably, it is 50-1000 micrometers. If the thickness of the solution is thinner than 10 μm, the shape as an electrolyte membrane tends to be not maintained, and if it is thicker than 2500 μm, a non-uniform electrolyte membrane tends to be easily formed.
A known method can be used as a method for controlling the casting thickness of the solution. For example, the thickness can be controlled with the amount and concentration of the solution with a constant thickness using an applicator, a doctor blade, or the like, and with a cast area constant using a glass petri dish or the like. A more uniform film can be obtained from the cast solution by adjusting the solvent removal rate. For example, in the case of heating, there is a method in which the first stage is performed at a low temperature and the temperature is raised later. In addition, when immersed in a non-solvent such as water, the coagulation rate of the compound can be adjusted by leaving the solution in air or an inert gas for an appropriate time.

The cast film on the support is sent to the drying step (A ₂ ) together with the support. As the method for removing the solvent in the drying step (A ₂ ), drying by heat treatment or reduced pressure treatment is preferable from the viewpoint of the uniformity of the electrolyte membrane. Moreover, in order to avoid decomposition | disassembly and a quality change of a compound or a solvent, it is preferable to dry at the lowest temperature possible under reduced pressure. It is preferable to dry until 70% or more of the solvent is removed and the cast film exhibits self-supporting properties.
Further, when the viscosity of the solution is high, when the support or the solution is heated and cast at a high temperature, the viscosity of the solution is lowered and the casting can be easily performed.

The membrane obtained by drying the cast membrane until it exhibits self-supporting property is further subjected to a solvent removal step (A ₃ ) in which the membrane is removed with a liquid that is miscible with the solvent of the ionic group-containing polymer electrolyte together with the support. Sent.
The liquid miscible with the solvent of the ionic group-containing polymer electrolyte is not particularly limited as long as it is miscible with the solvent and can be desolvated, but water is preferable.

In the present invention, the film formed in the film forming step (A) is further treated in an acid treatment step (B) in which an ionic group is converted into an acid form by contacting with an inorganic acid-containing acidic solution together with a support. The As the inorganic acid in the acid treatment step (B), an aqueous solution of hydrochloric acid, nitric acid, sulfuric acid or the like can be used. The temperature at the time of making it contact with acidic aqueous solution is not specifically limited.
As a result, the membrane can be brought into contact with an acidic aqueous solution without peeling from the support, the entire surface of the membrane is fixed by the support, swelling in the plane of the membrane is suppressed, and thickness unevenness and wrinkle generation are reduced. Can do.

The acid-treated membrane that has passed through the acid treatment step (B) then passes through an acid removal step (C) that removes free acid in the membrane, and the acid-removed membrane is further dried in the drying step (D). .
The step of removing excess acid in the acid-treated film without peeling the film from the support is preferably brought into contact with water. The method of contacting with water is not particularly limited, such as a method of contacting with running water such as a shower, a method of immersing in water, and the like. Further, contact with water may be repeated. At this time, if the salt used in the contact contains salt, the acidic group may be converted back to the metal salt, so at least use water that has been subjected to ion removal treatment, such as ion-exchanged water. Is desirable.

Also in the drying step (D), moisture is removed without peeling the polymer electrolyte membrane from the support. The drying method is not particularly limited, but is preferably air-dried. As a method of air-drying, the polymer electrolyte membrane can be dried by applying air or leaving it without applying air. The wind may be heated. Moreover, it can also be dried by applying heat from the support side.
The residual solvent content in the film after finishing the drying step (D) is preferably less than 1% by mass, and more preferably the residual solvent content is such that it cannot be detected by NMR as it is.

  The production method of the present invention is characterized in that the steps (B) to (D) are carried out without peeling the membrane from the support. As a result, even when the membrane is in contact with a solvent containing water, there is no problem such as swelling and deformation of the membrane, and there is little thickness unevenness, wrinkles and unevenness on the entire surface of the polymer electrolyte membrane, and the polymer electrolyte membrane is uniform. Can be obtained.

The polymer electrolyte membrane of the present invention can have any film thickness depending on the purpose, but is preferably as thin as possible from the viewpoint of proton conductivity. Specifically, it is preferably 3 to 200 μm, more preferably 5 to 150 μm, and particularly preferably 5 to 100 μm. If the thickness of the polymer electrolyte membrane is less than 3 μm, 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 polymer electrolyte membrane becomes too strong and handling Tend to be difficult.

As the polymer for forming the polymer electrolyte membrane in the present invention, a known polymer electrolyte can be used.
For example, as an aromatic hydrocarbon-based polymer containing an ionic group, an aromatic or aromatic ring and ether bond, sulfone bond, imide bond, ester bond, amide bond, urethane bond, sulfide bond, carbonate bond and Non-fluorine ion conductive polymer having a structure having at least one linking group selected from ketone bonds, such as polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene , Polyarylene-based polymer, polyphenylquinoxaline, polyaryl ketone, polyether ketone, polybenzoxazole, polybenzthiazole, polybenzimidazole, polyimide, etc. A polymer containing a sulfonic acid group, a phosphonic acid group, a carboxyl group, and at least one of those derivatives is a polymer which has been introduced.
In addition, the ionic conductivity of a polymer is expressed by including functional groups, such as a sulfonic acid group, a phosphonic acid group, and a carboxyl group, in a polymer. Among these, a functional group that acts particularly effectively is a sulfonic acid group. Polysulfone, polyethersulfone, polyetherketone, etc. as used herein are generic names for polymers having a sulfone bond, an ether bond, and a ketone bond in their molecular chains. Polyetherketoneketone, polyetheretherketone, It includes polyether ether ketone ketone, polyether ketone ether ketone ketone, polyether ketone sulfone and the like, and is not limited to a specific polymer structure.

  Among the polymers containing the functional group, a polymer having a sulfonic acid group on the aromatic ring can be obtained by reacting a polymer having a skeleton as in the above example with an appropriate sulfonating agent. Examples of such sulfonating agents include those using concentrated sulfuric acid or fuming sulfuric acid that have been reported as examples of introducing sulfonic acid groups into aromatic hydrocarbon polymers (for example, Solid State Ionics, 106, P.219 (1998)), those using chlorosulfuric acid (for example, J. Polym. Sci., Polym. Chem., 22, P.295 (1984)), those using anhydrous sulfuric acid complex (for example, J Polym. Sci., Polym. Chem., 22, P. 721 (1984), J. Polym. Sci., Polym. Chem., 23, P. 1231 (1985)) and the like are effective. In order to obtain the ionic group-containing polymer of the present invention, in particular, a polymer whose ion conductivity is a sulfonic acid group, it can be carried out by using these reagents and selecting reaction conditions according to each polymer. . Moreover, it is also possible to use the sulfonating agent described in Japanese Patent No. 2884189.

  The aromatic hydrocarbon ionic group-containing polymer can also be synthesized using a monomer containing an acidic group in at least one of the monomers used for polymerization. For example, in a polyimide synthesized from an aromatic diamine and an aromatic tetracarboxylic dianhydride, an acidic group-containing polyimide is obtained by using a diamine containing a sulfonic acid group or a phosphonic acid group as at least one of the aromatic diamines. I can do it. Polybenzoxazole synthesized from aromatic diamine diol and aromatic dicarboxylic acid, polybenzthiazole synthesized from aromatic diamine dithiol and aromatic dicarboxylic acid, polybenzimidazole synthesized from aromatic tetramine and aromatic dicarboxylic acid In this case, an acid group-containing polybenzoxazole, polybenzthiazole, or polybenzimidazole can be obtained by using a sulfonic acid group-containing dicarboxylic acid or a phosphonic acid group-containing dicarboxylic acid as at least one kind of aromatic dicarboxylic acid. Polysulfone, polyethersulfone, polyetherketone, etc. synthesized from aromatic dihalide and aromatic diol are synthesized by using sulfonic acid group-containing aromatic dihalide or sulfonic acid group-containing aromatic diol as at least one monomer. I can do it. At this time, it is preferable to use a sulfonic acid group-containing dihalide rather than a sulfonic acid group-containing diol because the degree of polymerization tends to be high and the thermal stability of the obtained acidic group-containing polymer is high.

  Aromatic hydrocarbon ionic group-containing polymers are polyarylene ether compounds such as sulfonic acid group-containing polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyether ketone polymers, and polyarylene compounds. More preferably.

（ただし、Ａｒは２価の芳香族基、Ｙはスルホン基又はケトン基、ＸはＨ及び／又は１価のカチオン種、Ｚは直接結合、エーテル結合及びチオエーテル結合から選ばれる少なくとも１種である。）

（ただし、Ａｒ’は２価の芳香族基、Ｚ’は直接結合、エーテル結合及びチオエーテル結合から選ばれる少なくとも１種である。）
一般式（１）及び一般式（２）で示される構成単位のポリマー中の比率（モル比）は、ポリマー組成より計算することができるスルホン酸基含有量で示すと、０．３〜３．５ｍｅｑ／ｇの範囲にあることが好ましい。０．３ｍｅｑ／ｇよりも少ない場合には、イオン伝導膜として使用したときに十分なイオン伝導性を示さない傾向があり、３．５ｍｅｑ／ｇよりも大きい場合にはイオン伝導膜を高温高湿条件においた場合に膜膨潤が大きくなりすぎて使用に適さなくなる傾向がある。より好ましくは０．６〜３．０ｍｅｑ／ｇである。 Among the polyarylene ether compounds and polyarylene compounds, the following polymers are more preferable.
That is, it is a polyarylene ether compound containing the structural units represented by general formula (1) and general formula (2).

(However, Ar is a divalent aromatic group, Y is a sulfone group or a ketone group, X is H and / or a monovalent cationic species, Z is at least one selected from a direct bond, an ether bond and a thioether bond. .)

(However, Ar ′ is a divalent aromatic group, and Z ′ is at least one selected from a direct bond, an ether bond and a thioether bond.)
When the ratio (molar ratio) in the polymer of the structural units represented by the general formula (1) and the general formula (2) is expressed by the sulfonic acid group content that can be calculated from the polymer composition, 0.3 to 3. It is preferably in the range of 5 meq / g. When it is less than 0.3 meq / g, there is a tendency that sufficient ion conductivity is not exhibited when used as an ion conductive membrane, and when it is greater than 3.5 meq / g, the ion conductive membrane is not heated and humidified. When the conditions are met, membrane swelling tends to be too large to be suitable for use. More preferably, it is 0.6-3.0 meq / g.

［一般式３において、Ｘは−Ｓ（＝Ｏ）_２−基又は−Ｃ（＝Ｏ）−基を、ＹはＨ又は１価の陽イオンを、Ｚ^１はＯ又はＳ原子のいずれかを、Ｚ^２は、Ｏ原子、Ｓ原子、−Ｃ（ＣＨ_３）_２−基、−Ｃ（ＣＦ_３）_２−基、−ＣＨ_２−基、シクロヘキシル基、直接結合のいずれかを、ｎ
１は１以上の整数を表す。］ Among the aromatic hydrocarbon-based ionic group-containing polymers, those having a repeating unit represented by the general formula 3 are particularly preferable.

[In General Formula 3, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ¹ represents either an O or S atom. , Z ² represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, a cyclohexyl group, or a direct bond,
1 represents an integer of 1 or more. ]

In the general formula 3, it is preferable that X is a —S (═O) ₂ — group because solubility in a solvent is improved. It is preferable that X is a —C (═O) — group because the softening temperature of the polymer can be lowered to further enhance the bonding property with the electrode, or the photocrosslinking property can be imparted to the electrolyte membrane. When used as a polymer electrolyte membrane, Y is preferably an H atom. However, if Y is an H atom, it is easily decomposed by heat or the like. Therefore, during processing such as manufacturing of an electrolyte membrane, Y is set as an alkali metal salt such as Na or K, and Y is converted to H atom by acid treatment after processing. A polymer electrolyte membrane can also be obtained by conversion. Z ¹ is preferably an O atom because there are advantages such as less polymer coloring and easy availability of raw materials. Z ¹ is preferably S because oxidation resistance is improved. n1 is preferably in the range of 1 to 30, and when n1 is 3 or more, a plurality of units having different n1 may be included. Z ² represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, a cyclohexyl group, a direct bond, It is preferable because the bondability is further improved. n1 When in the case of 3 or more is Z ² is O atom, preferably in particular for improving bondability between the electrode catalyst layer in the case of the polymer electrolyte membrane.

［一般式４において、Ａｒ^１は二価の芳香族基を、Ｚ^３はＯ原子又はＳ原子のいずれかを、Ｚ^４は、Ｏ原子、Ｓ原子、−Ｃ（ＣＨ_３）_２−基、−Ｃ（ＣＦ_３）_２−基、−ＣＨ_２−基、シクロヘキシル基、直接結合のいずれかを、ｎ２は１以上の整数を表す。］ It is preferable that the ionic group-containing polymer having a repeating unit represented by the general formula 3 further contains a repeating unit represented by the general formula 4.

[In General Formula 4, Ar ¹ represents a divalent aromatic group, Z ³ represents either an O atom or an S atom, Z ⁴ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, -C _{(CF 3) 2} - group, -CH ₂ - group, a cyclohexyl group, either a direct bond, n2 is an integer of 1 or more. ]

In the general formula 4, it is preferable that Z ³ is an O atom because there are advantages such as little coloring of the polymer and easy availability of raw materials. Z ³ is preferably an S atom since the oxidation resistance is improved. n2 is preferably in the range of 1 to 30, and when n2 is 3 or more, a plurality of units different in n2 may be included. Z ⁴ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, a cyclohexyl group, a direct bond, and an O atom or an S atom. It is preferable because the bondability is further improved. n2 When the case 3 or more is Z ⁴ is O atom, preferably in particular for improving bondability between the electrode catalyst layer in the case of the polymer electrolyte membrane.

  When the ionic group-containing polymer constituting the polymer electrolyte membrane in the present invention is mainly composed of a repeating unit represented by the general formula 1 and a repeating unit represented by the general formula 2, The 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 range of 10:90 to 50:50 is more preferable. More preferably, it is in the range of 10:90 to 40:60. The ionic group-containing polymer in the present invention has an appropriate softening temperature by having the repeating unit represented by the general formula 1 and the general formula 2, and has good bondability with an electrode when a polymer electrolyte membrane is formed. Indicates.

Ar ¹ in the general formula 4 is preferably a divalent aromatic group having an electron-withdrawing group. Examples of the electron-withdrawing group include a sulfone group, a sulfonyl group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid amide group, a sulfonic acid imide group, a carboxyl group, a carbonyl group, a carboxylic acid ester group, a cyano group, a halogen group, Although a trifluoromethyl group, a nitro group, etc. can be mentioned, it is not limited to these, What is necessary is just a well-known arbitrary electron withdrawing group.

A preferred structure of Ar ¹ is a structure represented by chemical formulas 5-8. The structure of Chemical Formula 5 is preferable because it can increase the solubility of the polymer. The structure of Chemical Formula 6 is preferable because it lowers the softening temperature of the polymer to increase the bonding property with the electrode and impart photocrosslinking properties. The structure of Chemical Formula 7 or 8 is preferable because the swelling of the polymer can be reduced, and the structure of Chemical Formula 8 is more preferable. Among the chemical formulas 5 to 8, the structure of the chemical formula 8 is most preferable.

One of the more preferable embodiments of the ionic group-containing polymer constituting the polymer electrolyte membrane of the present invention is that the polymer electrolyte membrane mainly has a structure represented by the general formula 3 and a structure represented by the general formula 4. It is an ionic group-containing polymer that is constituted and that both Z ¹ and Z ² in the general formula 3 are O atoms, and n1 is 3 or more. It is preferable to use such an ionic group-containing polymer because the bondability with the electrode is particularly improved.

One of the more preferable embodiments of the ionic group-containing polymer is more preferably that in Formula 4, Z ³ and Z ⁴ are both O atoms, and n2 is 3 or more. It is preferable to use such an ionic group-containing polymer because the bondability with the electrode is further improved.

［一般式９において、Ｘは−Ｓ（＝Ｏ）_２−基又は−Ｃ（＝Ｏ）−基を、ＹはＨ又は１価の陽イオンを、Ｚ^５はＯ又はＳ原子のいずれかを表す。］ One of the more preferable embodiments of the ionic group-containing polymer constituting the polymer electrolyte membrane of the present invention includes an ionic group-containing polymer having a repeating unit represented by the general formula 9 in addition to the general formula 3 and the general formula 5. It is a polymer. In addition to the repeating units represented by the general formula 1 and the general formula 4, further having the repeating unit represented by the general formula 9 improves the morphological stability of the membrane when a polymer electrolyte membrane is obtained. Is preferable.

[In General Formula 9, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ⁵ represents either an O or S atom. To express. ]

In General Formula 9, it is preferable that X is a —S (═O) ₂ — group because solubility in a solvent is improved. It is preferable that X is a —C (═O) — group because the softening temperature of the polymer can be lowered to further enhance the bonding property with the electrode, or the photocrosslinking property can be imparted to the electrolyte membrane. When used as a polymer electrolyte membrane, Y is preferably an H atom. However, if Y is an H atom, it is easily decomposed by heat or the like. Therefore, during processing such as manufacturing of an electrolyte membrane, Y is set as an alkali metal salt such as Na or K, and Y is converted to H atom by acid treatment after processing. A polymer electrolyte membrane can also be obtained by conversion. Z ⁵ is preferably an O atom because it has advantages such as less coloring of the polymer and easy availability of raw materials. Z ⁵ is preferably S because oxidation resistance is improved.

When the ionic group-containing polymer constituting the polymer electrolyte membrane of the present invention has repeating units represented by the general formulas 3, 4 and 9, Z ¹ and Z ² are O atoms or S It is preferable that it is an atom and n1 is 1, since the bonding property with the electrode catalyst layer in the case of a polymer electrolyte membrane and the morphological stability of the membrane become better. Further, when Z ³ and Z ⁴ are O atoms or S atoms and n2 is 1, the bondability with the electrode catalyst layer in the case of a polymer electrolyte membrane and the morphological stability of the membrane are further increased. Since it becomes favorable, it is preferable.

［一般式１０において、Ａｒ^２は２価の芳香族基を、Ｚ^６はＯ原子又はＳ原子のいずれかを表す。］ In addition to the repeating units represented by the general formulas 3, 4 and 9, the ionic group-containing polymer constituting the polymer electrolyte membrane of the present invention further has a repeating unit represented by the general formula 10. When a polymer electrolyte membrane is used, it is more preferable because the bondability with the electrode catalyst layer and the morphological stability of the membrane can be greatly improved.

[In General Formula 10, Ar ² represents a divalent aromatic group, and Z ⁶ represents either an O atom or an S atom. ]

Z ⁶ in the general formula 10 is preferably an O atom because there are advantages such as little coloring of the polymer and easy availability of raw materials. Z ⁶ is preferably an S atom because the oxidation resistance is improved. Ar ² in Chemical Formula 10 is preferably a divalent aromatic group having an electron-withdrawing group. Examples of the electron-withdrawing group include a sulfone group, a sulfonyl group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid amide group, a sulfonic acid imide group, a carboxyl group, a carbonyl group, a carboxylic acid ester group, a cyano group, a halogen group, Although a trifluoromethyl group, a nitro group, etc. can be mentioned, it is not limited to these, What is necessary is just a well-known arbitrary electron withdrawing group.

A preferred structure of Ar ² is a structure represented by chemical formulas 5-8. The structure of Chemical Formula 5 is preferable because it can increase the solubility of the ionic group-containing polymer. The structure of Chemical Formula 6 is preferable because it lowers the softening temperature of the ionic group-containing polymer to further enhance the bonding property with the electrode or impart photocrosslinkability. The structure of Chemical Formula 7 or 8 is preferable because the swelling of the ionic group-containing polymer can be reduced, and the structure of Chemical Formula 8 is more preferable. Among the chemical formulas 5 to 8, the structure of the chemical formula 8 is most preferable.

  When the ionic group-containing polymer constituting the polymer electrolyte membrane of the present invention has all the repeating units represented by the general formulas 3, 5, 9, and 10, respectively, mol% of each repeating unit, And it is preferable that mol% of other repeating units satisfy | fill the following Numerical formulas 1-3.

0.9 ≦ (n3 + n4 + n5 + n6) / (n3 + n4 + n5 + n6 + n7) ≦ 1.0 (Expression 1)
0.05 ≦ (n3 + n4) / (n3 + n4 + n5 + n6) ≦ 0.7 (Expression 2)
0.01 ≦ (n4 + n6) / (n3 + n4 + n5 + n6) ≦ 0.95 (Equation 3)
(In the above formula, n3 represents the mol% of the repeating unit represented by the general formula 9, n4 represents the mol% of the repeating unit represented by the general formula 3, and n5 represents the mol of the repeating unit represented by the general formula 10. %, N6 represents the mol% of the repeating unit represented by the general formula 4, and n7 represents the mol% of the other repeating unit.)

  When (n3 + n4 + n5 + n6) / (n3 + n4 + n5 + n6 + n7) is smaller than 0.9, good characteristics cannot be obtained when a polymer electrolyte membrane is obtained, which is not preferable. More preferred is a range of 0.95 to 1.0.

  When (n3 + n4) / (n3 + n4 + n5 + n6) is smaller than 0.05, it is not preferable because sufficient proton conductivity cannot be obtained when a polymer electrolyte membrane is obtained. On the other hand, if it is larger than 0.9, the swellability of the polymer electrolyte membrane is remarkably increased, which is not preferable. A more preferred range is from 0.1 to 0.7.

  (N3 + n4) / (n3 + n4 + n5 + n6) is preferably in the range of 0.07 to 0.5, and more preferably in the range of 0.1 to 0.4. If it is larger than 0.5, the fuel permeability may increase, which is not preferable. If it is smaller than 0.07, the proton conductivity decreases and the resistance increases, which is not preferable.

  When (n4 + n6) / (n3 + n4 + n5 + n6) is less than 0.01, it is not preferable because the bonding property with the electrode catalyst layer is lowered when a polymer electrolyte membrane is formed. If it is greater than 0.95, the swellability of the polymer electrolyte membrane may become too large, which is not preferable. 0.05 to 0.8 is a more preferable range. More preferably, it is in the range of 0.4 to 0.8.

  In the ionic group-containing polymer of the present invention, the bonding mode of each repeating unit represented by each general formula is not particularly limited, and includes random bonding, alternating bonding, bonding in a continuous block structure, and the like. Either is acceptable.

  As a method for synthesizing the ionic group-containing polymer in the present invention, a known method can be adopted and is not particularly limited. However, as a preferable example of a raw material monomer used for synthesis, a monomer having a structure represented by the following general formulas 11 to 13 Can be mentioned. Furthermore, it is preferable to further use a monomer having a structure represented by the general formula 14 because physical properties such as film form stability are improved.

In General Formulas 11 to 14, X is a —S (═O) ₂ — group or —C (═O) — group, Y is H or a monovalent cation, and Z ⁷ and Z ¹⁰ are each independently Any one of Cl atom, F atom, I atom, Br atom and nitro group, Z ⁸ and Z ¹¹ are each independently OH group, SH group, —O—NH—C (═O) —R group. , -S-NH-C (= O) -R group [R represents an aromatic or aliphatic hydrocarbon group. Z ⁹ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, a cyclohexyl group, or a direct bond, and Ar ⁴ Represents an aromatic group having an electron-withdrawing group such as a perfluoroalkyl group such as a sulfone group, a carbonyl group, a sulfonyl group, a phosphine group, a cyano group or a trifluoromethyl group, a nitro group or a halogen group in the molecule.

Specific examples of the compound represented by the general formula 11 include 3,3′-disulfo-4,4′-dichlorodiphenylsulfone, 3,3′-disulfo-4,4′-difluorodiphenylsulfone, 3,3 ′. -Disulfo-4,4'-dichlorodiphenyl ketone, 3,3'-disulfo-4,4'-difluorodiphenyl ketone, 3,3'-disulfobutyl-4,4'-dichlorodiphenyl sulfone, 3,3'-disulfobutyl -4,4'-difluorodiphenyl sulfone, 3,3'-disulfobutyl-4,4'-dichlorodiphenyl ketone, 3,3'-disulfobutyl-4,4'-difluorodiphenyl ketone, and their sulfonic acid groups are 1 Examples include salts with valent cation species. The monovalent cation species may be sodium, potassium, other metal species, various amines, or the like, but is not limited thereto.
Examples of the compound represented by the general formula 11 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 include ketones and potassium 3,3′-disulfonate-4,4′-difluorodiphenyl ketone.

  Specific examples of the compound represented by the general formula 12 include 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, and 2,2-bis (4-hydroxyphenyl) hexafluoropropane. 4,4′-thiobisbenzenethiol, 4,4′-oxybisbenzenethiol, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 1,1-bis (4-hydroxyphenyl) cyclohexane 4,4′-thiobisbenzenethiol, bis (4-hydroxyphenyl) sulfide, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-biphenol, terminal hydroxyl group-containing Phenylene ether oligomer (the structure represented by the following chemical formula 15 ) Is preferable. In Chemical Formula 15, n is an integer of 1 or more, and may be a mixture of n different components. These compounds constitute a unit represented by Ar in the general formula (1).

  The monomer having the structure represented by the general formula 12 increases the flexibility of the ionic group-containing polymer, suppresses breakage against deformation, or lowers the glass transition temperature to improve the bondability with the electrode catalyst layer. It can bring about effects such as.

  Examples of the compound represented by the general formula 13 include compounds having a leaving group in a nucleophilic substitution reaction such as halogen or nitro group on the same aromatic ring and an electron-withdrawing group for activating it. Specific examples include 2,6-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-difluorobenzonitrile, 4,4′-dichlorodiphenylsulfone, 4,4 ′. -Difluorodiphenyl sulfone, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, decafluorobiphenyl, and the like, but not limited thereto, other aromatics active in aromatic nucleophilic substitution reaction A group dihalogen compound, an aromatic dinitro compound, an aromatic dicyano compound, and the like can also be used.

  Examples of the compound represented by the general formula 14 include 4,4'-biphenol, 4,4'-dimercaptobiphenol, and 4,4'-biphenol is preferable.

  In the above aromatic nucleophilic substitution reaction, other various activated dihalogen aromatic compounds, dinitroaromatic compounds, bisphenol compounds, bisthiophenol compounds may be used in combination with the compounds represented by the general formulas 11-14. it can.

  Examples of other bisphenol compounds or bisthiophenol compounds 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-benze Examples include dithiol, 1,3-benzenedithiol, phenolphthalein, 10- (2,5-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide. In addition, various aromatic diols or various aromatic dithiols that can be used for polymerization of polyarylene ether compounds by aromatic nucleophilic substitution reaction can also be used, and are not limited to the above compounds. . These compounds constitute a unit represented by Ar in the general formula (1).

  In the method for producing an ionic group-containing polymer electrolyte membrane in the present invention, the activated dihalogen aromatic compound, dinitro aromatic compound, aromatic diol or aromatic dithiol is used as a raw material in the presence of a basic compound. A polymer obtained by polymerization by a known aromatic nucleophilic substitution reaction, preferably having a logarithmic viscosity of 0.1 to 2.0 dL / g and a softening temperature of 90 ° C. or higher, and further having a softening temperature of 140 to The thing of 250 degreeC is more preferable.

EXAMPLES Hereinafter, the present invention will be specifically described using examples, but the present invention is not limited to these examples. Various measurements were performed as follows.
<Solution viscosity of polymer>
The polymer powder was dissolved in N-methylpyrrolidone at a concentration of 0.5 g / dL, the viscosity was measured using a Ubbelohde viscometer in a constant temperature bath at 30 ° C., and the logarithmic viscosity ln [ta / tb] / c was evaluated. (Ta is the drop time of the sample solution, tb is the drop time of the solvent only, and c is the polymer concentration).
<Softening temperature of polymer>
While heating a 5 mm wide acid-type film at a chuck width of 10 mm from 50 ° C. to 250 ° C. at a rate of 2 ° C./min, a dynamic strain of 10 Hz is applied to give dynamic viscoelasticity, Rheogel E-4000 (Toki Sangyo) The measurement was performed using The temperature at the inflection point at which E ′ greatly decreased was defined as the softening temperature.

<Drying speed>
Various dry membranes obtained by drying the cast membrane on the support under various drying conditions are dissolved in dimethyl sulfoxide (DMSO), and each solution is subjected to NMR spectrum analysis under the condition of 128 times of integration by H-NMR. The amount of solvent was determined, the amount of evaporation per unit time / unit area was calculated from the amount of residual solvent relative to the polymer mass, and the drying rate was calculated. Moreover, the drying speed said here means the speed | rate in the state in which the constant-rate drying is progressing except the material preheating period by heat | fever, and the decremental drying period which contributes to structure formation.

<Desolvation rate>
Various desolvation membranes obtained by desolvating the dry membrane on the support under various desolvation conditions were dissolved in dimethyl sulfoxide (DMSO), and each solution was subjected to NMR spectrum under the condition of 128 times of integration by H-NMR. The amount of solvent was determined by analysis, and the amount of solvent decrease per unit time / unit area was calculated from the solvent content relative to the polymer mass, and the solvent removal rate was calculated. Further, the solvent removal rate referred to here means that the liquid miscible with the solvent of the ionic group-containing polymer electrolyte and the solvent in the ionic group-containing polymer electrolyte membrane contained after the drying step are converted at a constant rate. It means speed in the state.

<Film thickness of electrolyte membrane>
The thickness of the polymer electrolyte membrane was measured using a commercially available micrometer (Mitutoyo micrometer, 0.001 mm) after peeling from the support. Measure the thickness of 20 locations on a sample of a polymer electrolyte membrane that has been allowed to stand for at least 24 hours in a measurement chamber controlled at room temperature of 20 ° C and humidity of 30 ± 5% RH for 5 x 5 cm. The average value was the thickness, and the degree of thickness unevenness was indicated by the standard deviation value.

<Measurement of unevenness of electrolyte membrane>
The unevenness of the polymer electrolyte membrane was measured using a commercially available three-dimensional non-contact surface shape measuring device (Ryoka System Micromap). The polymer electrolyte membrane, which has been allowed to stand for 24 hours or more in a measurement chamber controlled at a room temperature of 20 ° C. and a humidity of 30 ± 5% RH, is cut to a size of 3 × 3 cm, and the shape is observed on both sides. And the difference R3 in the height of the maximum recess was measured.

<Average pore diameter by DSC method>
After the ion exchange membrane was immersed in water at 20 ° C. for 2 days to swell, 30 to 50 mg was sampled, packed in an aluminum pan for closed differential scanning calorimetry (DSC), and crimped. At that time, water adhering to the surface was removed by wiping with Kimwipe.
As a DSC temperature program, the temperature was first cooled from room temperature to −100 ° C. at a rate of 50 ° C./min, and held at −100 ° C. for 10 minutes. Thereafter, the temperature was raised to 15 ° C. at a rate of 2.5 ° C./min, and the difference between the melting temperature of the bulk water that appeared during the temperature rise and the melting point of the water that caused the freezing point depression was determined, and this was taken as ΔT. From the obtained ΔT, the pore diameter was determined by the following formula according to the pore theory, and the difference R4 between the maximum diameter and the minimum diameter of 10 samples was measured.
Pore diameter r (Å) = 164 / ΔT

<Ion exchange capacity (acid type)>
As the ion exchange capacity (IEC), the amount of acid type functional groups present in the ion exchange membrane was measured. First, as sample preparation, a sample piece (5 cm × 5 cm) was dried in an oven at 80 ° C. under a nitrogen stream for 2 hours, and further allowed to cool in a desiccator filled with silica gel for 30 minutes, and then the dry mass was measured (Ws). Next, 200 mL of 1 M (mol / liter) sodium chloride-ultra pure aqueous solution and the weighed sample were placed in a 200 mL sealed glass bottle, and stirred at room temperature for 24 hours while being sealed. Next, 30 mL of the solution was taken out, neutralized with a 10 mM (mol / L) aqueous sodium hydroxide solution (commercial standard solution), and IEC was determined from the titration (T) using the following formula.
IEC (meq / g) = 10 T / (30 Ws) × 0.2
(Unit of T: mL, unit of Ws: g)

<Ion conductivity>
The ion conductivity σ was measured as follows.
A platinum wire (diameter: 0.2 mm) is pressed against the surface of a strip-shaped membrane sample on a probe for self-made measurement (made of tetrafluoroethylene resin), the sample is held in water at 25 ° C, and the impedance between the platinum wires is set to SOLARTRON. It was measured by a company 1250 FREQUENCY RESPONSE ANALYSER. The measurement was performed while changing the distance between the electrodes, and the conductivity obtained by canceling the contact resistance between the film and the platinum wire was calculated from the gradient obtained by plotting the distance measured between the electrodes and the resistance measurement value estimated from the CC plot. The distance between the electrodes is 1.5 cm in water at 25 ° C, 80 ° C,
At 95% RH, it was set to 1 cm.
Ion conductivity [S / cm] = 1 / membrane width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm]
In addition, the above analysis was performed on 10 samples, and the maximum and minimum difference R5 was measured.

<Methanol permeation rate and methanol permeation coefficient>
The methanol permeation rate and methanol permeation coefficient of the proton exchange membrane were measured by the following methods.
Proton exchange immersed for 24 hours in a 5 M (mol / liter) methanol aqueous solution adjusted to 25 ° C. (Methanol aqueous solution is prepared using commercially available reagent-grade methanol and ultrapure water (18 MΩ · cm)) The membrane is sandwiched between H-type cells, 100 mL of a 5 molar aqueous methanol solution is injected into one side of the cell, 100 mL of ultrapure water is injected into the other cell, and the cells on both sides are stirred at 25 ° C. The amount of methanol diffusing into the ultrapure water through the gas was measured by gas chromatography (the area of the proton exchange membrane was 2.0 cm ² ). That is, it calculated using the following formula | equation from the methanol concentration change rate [Ct] (mmol / L / s) of the cell which put the ultrapure water.
Methanol permeation rate [mmol / m ² / s]
= (Ct [mmol / L / s] × 0.1 [L]) / 2 × 10 ⁻⁴ [m ² ]
Methanol permeability coefficient [mmol / m ² / s]
= Methanol permeation rate [mmol / m ² / s] × film thickness [m]
Moreover, the said analysis was performed with respect to 10 samples and the largest and minimum difference R6 was measured.

<Example 1>
3,3′-disulfo-4,4′-dichlorodiphenylsulfone disodium salt 579.1 g, 67,4 g of 2,6-dichlorobenzonitrile, 941.9 g of 4,4′-biphenol, 803.2 g of potassium carbonate, N -5438.9 g of methyl-2-pyrrolidone was added and stirred at 150 ° C. for 1 hour under a nitrogen atmosphere, and then the reaction was continued with the reaction temperature raised to 200 ° C. and the viscosity of the system sufficiently increased. . After standing to cool, it was precipitated in water into strands, and the resulting polymer was washed in water for 40 hours and then dried. The logarithmic viscosity of this polymer was 1.11 dL / g, and the softening temperature was 245 ° C.
Next, a polymer solution was prepared using N-methyl-2-pyrrolidone as a solvent so that the polymer concentration was 27% by mass. The prepared solution was continuously cast on a polyethylene terephthalate film as a support with a blade coater at a temperature of 25 ° C. so that the coating thickness of the polymer solution was 300 μm, 450 μm, and 600 μm, and shown in Tables 1 to 3 The state of the film which was dried under dry conditions and showed self-supporting property was examined. Moreover, the dry film | membrane was extract | collected and the solvent content in each film | membrane was measured.
Based on the amount of residual solvent, R ₁ : drying rate (g / m ² · min) of the film was determined, and R ₁ · T was calculated.
The obtained results are shown in Tables 1-3.
In addition, the film forming state (film appearance, surface quality) after the drying step (A ₂ ) was evaluated in the following three stages.
○: There is no foaming or undulation, and the surface form is good.
Δ: No foaming or undulation, but uneven thickness is observed.
X: There is foaming and undulation, and both the surface form and thickness unevenness are poor.

For the membranes obtained in Tables 1 to 3, the solvent removal treatment by immersion in pure water and a 20% by mass sulfuric acid aqueous solution were carried out under the conditions shown in Table 4 according to the coating thickness without peeling off the polymer membrane from the support. The treatment was performed in the order of conversion of the ionic group into an acid form by immersion, removal of free acid by immersion in pure water, and air drying at 25 ° C. Thereafter, the polymer membrane was peeled from the support to obtain a polymer electrolyte membrane.
The evaluation result about the obtained polymer electrolyte membrane (a part of an Example and a comparative example) is shown to Tables 5-7.
In addition, the external appearance and surface quality of the film after the drying step (D) were evaluated in the following three stages.
○: No trace of water droplets, undulations, wrinkles, and good surface morphology.
Δ: Water droplet traces, undulations, and wrinkles are not observed, but uneven thickness is observed.
X: There are water drop marks, waviness and wrinkles, and both the surface form and thickness unevenness are poor.

<Example 2>
3,3′-Sodium disulfonate-4,4′-dichlorodiphenylsulfone (abbreviation: S-DCDPS) 38.8 g, 2,6-dichlorobenzonitrile (abbreviation: DCBN) 53.5 g after removing bound water, 4 , 4′-biphenol (abbreviation: BP) 18.2 g, 4,4′-thiobisphenol (abbreviation: BPS) 64.0 g, potassium carbonate 59.4 g, N-methyl-2-pyrrolidone (abbreviation: NMP) 375. A polymer having a logarithmic viscosity of 1.37 l / g and a softening temperature of 250 ° C. was obtained in the same manner as in Example 1 except that 3 g was used as a raw material.
Further, the polymer solution was adjusted so that the polymer concentration was 26% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. The evaluation results of the obtained polymer electrolyte membrane are shown in Table 8 and Table 9.

<Example 3>
Dry S-DCDPS 81.0 g, DCBN 72.9 g, terminal hydroxyl group-containing phenylene ether oligomer (SPECIANOL DPE-PL manufactured by Dainippon Ink & Chemicals, Inc .; The average value is 5) (abbreviation: DPE) 191.6 g, potassium carbonate 89.5 g, NMP 1116.1 g were used, and the reaction time was 8 hours. A polymer having a logarithmic viscosity of 0.63 dL / g and a softening temperature of 182 ° C. was obtained.
Further, the polymer solution was adjusted so that the polymer concentration was 30% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. The evaluation results of the obtained polymer electrolyte membrane are shown in Table 10 and Table 11.

<Example 4>
In Example 1, 536 g of 3,3′-disulfo-4,4′-dichlorodiphenylketone disodium salt was used in place of 579.1 g of 3,3′-disulfo-4,4′-dichlorodiphenylsulfone disodium salt. In the same manner, a polymer was synthesized. The logarithmic viscosity of the obtained polymer was 0.87 dL / g.
Further, the polymer solution was adjusted so that the polymer concentration was 28% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. Tables 12 and 13 show the evaluation results regarding the quality of the obtained polymer electrolyte membrane.

<Example 5>
Weigh out 0.90 g of 9,9-bis (4-hydroxyphenyl) fluorene, 1.00 g of bisphenol S, 1.45 g of difluorodiphenyl sulfone, and 0.91 g of calcium carbonate in a 50 ml four-necked flask and 20 ml of NMP under a nitrogen stream. The reaction temperature was set at around 175 ° C. and the reaction was continued for about 5 hours. After standing to cool, it was reprecipitated in about 100 ml of methanol and washed with water three times using a mixer to obtain a polymer. The logarithmic viscosity of the obtained polymer was 0.61 dL / g. The polymer sample is stirred with concentrated sulfuric acid (98%) with a magnetic stirrer at room temperature to perform a sulfonation reaction. After the reaction, the sulfuric acid solution is poured into excess ice water to stop the reaction, and the resulting precipitate is collected by filtration. The polymer was washed with water to obtain a sulfonic acid group-containing polymer.
Further, the polymer solution was adjusted so that the polymer concentration was 30% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. Tables 14 and 15 show the evaluation results regarding the quality of the obtained polymer electrolyte membrane.

<Example 6>
Weigh 15 g of 3,3 ′, 4,4′-tetraaminodiphenylsulfone, 14 g of monosodium 2,5-dicarboxybenzenesulfonate, 205 g of polyphosphoric acid (phosphorus pentoxide content 75%) and 164 g of phosphorus pentoxide in a polymerization vessel. take. The temperature was raised to 100 ° C. while flowing nitrogen and slowly stirring on an oil bath. After maintaining at 100 ° C. for 1 hour, the temperature was raised to 150 ° C. for 1 hour, and the temperature was raised to 200 ° C. and polymerized for 4 hours. After completion of the polymerization, the mixture is allowed to cool, and water is added to take out the polymer. After repeating the water washing three times using a home mixer, the water-immersed polymer is neutralized by adding sodium carbonate, and further washed with water repeatedly. It was confirmed that the pH of the solution became neutral and did not change. The obtained polymer was dried under reduced pressure at 80 ° C. overnight. The logarithmic viscosity of the polymer was 1.92 dL / g, and the softening temperature was not below 250 ° C.
Furthermore, the polymer solution was adjusted so that the polymer concentration was 20% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. Tables 16 and 17 show the evaluation results regarding the quality of the obtained polymer electrolyte membrane.

<Example 7>
1.83 g of 3,3 ′, 4,4′-tetraaminodiphenylsulfone, 0.53 g of monosodium 2,5-dicarboxybenzenesulfonate, 1.13 g of 3,5-dicarboxyphenylphosphonic acid, polyphosphoric acid (5 25 g of phosphorus oxide content (75%) and 20 g of phosphorus pentoxide were weighed in a polymerization vessel, and nitrogen was allowed to flow, and the temperature was raised to 100 ° C. while stirring slowly on an oil bath. After maintaining at 100 ° C. for 1 hour, the temperature was raised to 150 ° C. for 1 hour, and the temperature was raised to 200 ° C. and polymerized for 6 hours. After completion of the polymerization, the mixture is allowed to cool, and water is added to take out the polymer. After repeating the water washing three times using a home mixer, the water-immersed polymer is neutralized by adding sodium carbonate, and further washed with water repeatedly. It was confirmed that the pH of the solution became neutral and did not change. The obtained polymer was dried under reduced pressure at 80 ° C. overnight. The logarithmic viscosity of the polymer was 1.18 dL / g and the softening temperature was not below 250 ° C.
Further, the polymer solution was adjusted so that the polymer concentration was 27% by mass, and thereafter a polymer electrolyte membrane having a coating thickness of 300 μm was obtained in the same manner as in Example 1. Tables 18 and 19 show the evaluation results regarding the quality of the obtained polymer electrolyte membrane.

  In Examples 1 to 7, by prescribing the drying rate with hot air and the desolvation rate with pure water immersion, the thickness of the entire surface of the film is small, and there are few wrinkles and irregularities, ensuring a stable film quality, Membrane characteristics such as ion conductivity and methanol permeability are also stable, indicating that the polymer electrolyte membrane is good. On the other hand, in Comparative Examples 1 to 7, the film quality cannot be secured unless the drying rate by hot air is outside the specified range, and the film quality is further deteriorated if the desolvation rate by pure water immersion is also outside the specified range. It can be seen that there is a tendency, and the membrane characteristics vary widely and are poor as a polymer electrolyte membrane.

According to the present invention, it is possible to produce a uniform polymer electrolyte membrane that is extremely thin and has uniform thickness, wrinkles, and unevenness on the entire surface of the polymer electrolyte membrane, and further prevents the permeation of fuel to prevent the permeation of fuel such as hydrogen. Properties such as mechanical strength can be improved, and it is expected to contribute to the development of solid polymer fuel cells.

Claims (6)

A casting step (A ₁ ) of casting an ionic group-containing polymer electrolyte solution on a support to form a casting membrane, a drying step (A ₂ ) of evaporating the solvent from the casting membrane, and the drying membrane It comprises a desolvation step (A ₃ ) in which the solvent is extracted with a liquid miscible with the solvent of the ionic group-containing polymer electrolyte, and the step (A ₂ ) and the step (A ₃ ) are separated from the support. In the method for forming a polymer electrolyte membrane, the relationship between the coating thickness coefficient T of the polymer electrolyte solution and the drying speed R ₁ (g / m ² · min) in the drying step (A ₂ ) is expressed by the following formula ( A method for forming a polymer electrolyte membrane, comprising drying until a self-supporting membrane having a solvent content of 15 to 30% by mass in the range of I) is obtained.
2 ≦ R ₁・ T ≦ 56 (I)
(However, R ₁ : Drying rate (g / m ² · min),
T: Coating thickness of polymer electrolyte solution (μm) / 300 (μm)) The desolvation speed in removing of _{(A 3) R 2 (g} / m 2 · min), in the from 1 to 20 g / ^{m 2} · min, according to claim 1, desolvation until the solvent content of less than 8 wt% Of forming a polymer electrolyte membrane.   An acid treatment step (B) in which the polymer electrolyte membrane formed in claim 1 or 2 is brought into contact with an inorganic acid-containing acidic solution while the polymer electrolyte membrane is attached to a support to convert an ionic group into an acid form, the acid treatment A method for producing a polymer electrolyte membrane comprising an acid removal step (C) for removing free acid in the membrane and a drying step (D) for drying the acid removal membrane, wherein (B) to (D) A process for producing a polymer electrolyte membrane, wherein the step is performed without peeling the polymer electrolyte membrane from the support.   The manufacturing method of the polymer electrolyte membrane whose average pore diameter by DSC method in the polymer electrolyte membrane obtained by Claim 3 is 0.1-10 nm.   The solvent is at least one selected from N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, dimethylimidazolidinone, dimethyl sulfoxide, hexamethylphosphonamide, A method for producing a polymer electrolyte membrane, wherein the liquid to be mixed is water. The manufacturing method of the polymer electrolyte membrane whose ionic group containing polymer electrolyte is a polyarylene ether type compound containing the structural unit shown by General formula (1) and General formula (2).

(However, Ar is a divalent aromatic group, Y is a sulfone group or a ketone group, X is H and / or a monovalent cationic species, Z is at least one selected from a direct bond, an ether bond and a thioether bond. .)

(However, Ar ′ is a divalent aromatic group, and Z ′ is at least one selected from a direct bond, an ether bond and a thioether bond.)