JP4911822B2 - Production method of ion exchange resin membrane - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ion exchange resin membrane used in a fuel cell.
[0002]
[Prior art]
An ion exchange resin is a polymer material having a strong acid group such as a sulfonic acid group or a carboxylic acid group in the polymer chain, and has a property of selectively permeating specific ions. It is used in various applications such as fuel cells, chloroalkali, water electrolysis, hydrohalic acid electrolysis, salt electrolysis, oxygen concentrators, humidity sensors, gas sensors and the like. In particular, fuel cells convert fuel chemical energy into electrical energy by electrochemically oxidizing hydrogen, methanol, or the like, and are attracting attention as a clean electrical energy supply source.
[0003]
By the way, an ion exchange resin membrane used in such a fuel cell is required to exhibit high ion conductivity.
It has been reported in JP-A-4-366137 and JP-A-6-342665 that the ionic conductivity of the ion-exchange resin membrane greatly depends on the water content of the membrane. It is known to show high ionic conductivity. Therefore, when using for a fuel cell, the device which lowers | hangs the electrical resistance at the time of electric power generation is achieved by using the ion-exchange resin film | membrane used as a high moisture content, and achieving high ion conductivity.
[0004]
However, the ion exchange resin membrane having such a high moisture content has a large dimensional change due to water absorption and dehydration, and is extremely complicated to handle. The ion exchange resin membrane deteriorates due to repeated expansion and contraction, and there is a problem in terms of long-term durability.
On the other hand, the ionic conductivity of the ion exchange resin membrane also greatly depends on the number of ion exchange groups. Usually, the smaller the dry weight (EW) per equivalent of ion exchange groups, that is, the number of ion exchange groups. It has been found that ion exchange resin membranes with higher amounts exhibit greater ionic conductivity. However, even when the EW is small, the dimensional change of the film accompanying water absorption and dehydration becomes large, and there is a problem that it is easily dissolved in water or hot water. Therefore, for fuel cells, the EW is normally limited to about 950 to 1200.
[0005]
Also, after impregnating the perfluorosulfonic acid ion exchange resin membrane in an alcohol aqueous solution such as methanol, a mixed solvent of tetraethoxysilane and alcohol, which is a metal alkoxide, is added, and tetraethoxysilane is added by the catalytic action of the sulfonic acid group. An ion exchange resin membrane in which silica is contained in a perfluorosulfonic acid ion resin exchange membrane by hydrolysis and polycondensation reaction has also been reported (KA Mauritz, RF Storey and CK Jones, in Multiphase Polymer Materials: Blends and Ionomers, LA Utracki and RA Weiss, Editors, ACS Symposium Series No. 395, p. 401, American Chemical Society, Washington, DC (1989)). When this inventor evaluated this ion exchange resin membrane, it turned out that the dimensional change of the membrane accompanying water absorption and dehydration becomes small. However, the production of such an ion exchange resin membrane containing silica is accompanied by a swelling process of the ion exchange resin membrane with an aqueous alcohol solution, so that mass production is extremely difficult.
[0006]
On the other hand, ion exchange resin membranes containing fine particles of silica and / or silica fibers are disclosed in JP-A-6-1111827, and hygroscopic inorganic porous particles are dispersed and mixed in JP-A-9-251857. A resin film is disclosed. The present inventors also examined these ion exchange resin membranes. As a result, no remarkable effect was found with respect to the dimensional change of the membranes due to water absorption and dehydration and dissolution in water at low EW.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing an ion exchange resin membrane that can be used in a fuel cell and has a small dimensional change due to water absorption and dehydration and is hardly dissolved in water even when EW is small. Is.
[0008]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors, a metal oxide precursor was added to a solution containing an ion exchange resin, and a liquid obtained by hydrolysis and polycondensation reaction of the metal oxide precursor was cast into a film. It was found that the ion exchange resin membrane produced in this way has little change in the dimensional change of the membrane due to water absorption and dehydration, and it is difficult to dissolve in water even if the EW is small.
[0009]
That is, the present invention
1 . A metal oxide precursor selected from Al, Si, and Y is added to a solution containing an ion exchange resin represented by the following formula (2) having a sulfonic acid group or a carboxylic acid group having an EW of 250 or more and 800 or less. A method for producing an ion exchange resin membrane for a fuel cell , characterized in that a liquid obtained by adding and hydrolyzing and polycondensing the metal oxide precursor is cast into a membrane,
_{^{- [CF 2 CX 1 X 2}} ] a - [CF 2 -CF (-O- (CF 2 -CF (CF 2 X 3)) b -O C - (CFR 1) d - (CFR 2) e - ( _{^{CF 2) f -X 4)]}} - (2)
(In the formula, X ¹ , X ² and X ³ are independently a halogen element or a perfluoroalkyl group having 1 to 3 carbon atoms, a is an integer of 0 to 20, b is an integer of 0 to 8, and c is 0 or 1. , D and e and f are each independently an integer of 0 to 6 (where d + e + f is not equal to 0), R ¹ and R ² are independently a halogen element or a C 1-10 perfluoroalkyl group or fluorochloroalkyl group , X ⁴ is COOZ or SO ₃ Z (Z is a hydrogen atom))
2. The method for producing an ion exchange resin membrane according to the above 1, wherein the ion exchange resin is represented by the above formula (2) (where b = 0),
3. An ion exchange resin membrane for a fuel cell , characterized by being produced by the method according to 1 or 2 above ,
4). A membrane electrode assembly comprising the ion exchange resin membrane according to 3 above ,
5. A polymer electrolyte fuel cell comprising the ion exchange resin membrane according to 3 above ,
About.
[0010]
Below, the manufacturing method of the ion exchange resin membrane of this invention is demonstrated in detail. In the production method of the present invention, a metal oxide precursor is added to a solution containing an ion exchange resin, and a liquid obtained by hydrolysis and polycondensation reaction of the metal oxide precursor is cast into a film. The present invention relates to a method for producing an exchange resin membrane.
The ion exchange resin used in the present invention is a fluorocarbon polymer (hereinafter referred to as an ion) obtained by copolymerizing a fluorinated olefin and a vinyl fluoride compound having an ion exchange group precursor (a sulfonic acid group precursor or a carboxylic acid group precursor). (Referred to as an exchange resin precursor) and subsequently hydrolyzing the ion exchange group precursor to a fluorocarbon polymer having a sulfonic acid group or a carboxylic acid group.
The ion exchange resin precursor is composed of a fluorinated olefin represented by CF ₂ = CX ¹ X ² (X ¹ and X ² are each independently a halogen element, a C 1-10 perfluoroalkyl group or a fluorochloroalkyl group) _{, CF 2 = CF (-O- (} CF 2 -CF (CF 2 X 3)) b -O C - (CF 2) f -X 5 (CFR 1) d - - (CFR 2) e) is represented by Vinyl fluoride compound (c is 0 or 1, d and e and f are each independently an integer of 0 to 6 (where d + e + f is not equal to 0), R ¹ and R ² are independently a halogen element or 1 to 10 perfluoroalkyl groups or fluorochloroalkyl groups, X ⁵ is CO ₂ R ³ , COR ⁴ , or SO ₂ R ⁴ (R ³ is a hydrocarbon alkyl group having 1 to ³ carbon atoms, R ⁴ is a halogen element) ) And a fluorocarbon copolymer.
[0011]
Typical fluorinated olefins include CF ₂ = CF ₂ , CF ₂ = CFCl, CF ₂ = CCl ₂ . The fluorinated vinyl compound, _{specifically, CF 2 = CFO (CF 2} ) z -SO 2 F, CF 2 = CFOCF 2 CF (CF 3) O (CF 2) z -SO 2 F, CF 2 = _{CF (CF 2) z -SO 2} F, CF 2 = CF (OCF 2 CF (CF 3)) z-1 - (CF 2) 2 -SO 2 F, CF 2 = CFO (CF 2) z -CO 2 _{R, CF 2 = CFOCF 2 CF} (CF 3) O (CF 2) z -CO 2 R, CF 2 = CF (CF 2) z -CO 2 R, CF 2 = CF (OCF 2 CF (CF 3)) _{z - (CF 2) 2 -CO} 2 R (z is an integer of 1 to 8, R represents a hydrocarbon-based alkyl group having 1 to 3 carbon atoms).
[0012]
The fluorocarbon copolymer may be a copolymer containing a third component such as perfluoroolefin such as hexafluoropropylene or chlorotrifluoroethylene, or perfluoroalkyl vinyl ether.
As a polymerization method of such an ion exchange resin precursor, a solution polymerization method in which the above-mentioned vinyl fluoride compound is dissolved in a solvent such as chlorofluorocarbon and then reacted with a gas of fluorinated olefin, and a solvent such as chlorofluorocarbon is used. A bulk polymerization method in which polymerization is performed without polymerization, and an emulsion polymerization method in which a vinyl fluoride compound is charged together with a surfactant in water and emulsified, and then reacted with a fluoroolefin gas for polymerization. The ion exchange resin precursor is represented by the following formula (1).
_{^{- [CF 2 CX 1 X 2}} ] a - [CF 2 -CF (-O- (CF 2 -CF (CF 2 X 3)) b -O C - (CFR 1) d - (CFR 2) e - ( ^{_{CF 2) f -X 5)]}} - (1)
(In the formula, X ¹ , X ² and X ³ are independently a halogen element or a perfluoroalkyl group having 1 to 3 carbon atoms, a is an integer of 0 to 20, b is an integer of 0 to 8, and c is 0 or 1. , D and e and f are each independently an integer of 0 to 6 (where d + e + f is not equal to 0), R ¹ and R ² are independently a halogen element or a C 1-10 perfluoroalkyl group or fluorochloroalkyl group , X ⁵ is CO ₂ R ³ , COR ⁴ , or SO ₂ R ⁴ (R ³ is a hydrocarbon alkyl group having 1 to ³ carbon atoms, R ⁴ is a halogen element))
[0013]
Next, the ion exchange resin precursor produced by the above method is brought into contact with an alkaline solution to hydrolyze the ion exchange group precursor to produce an ion exchange resin. The hydrolysis of the ion exchange group precursor can be carried out in an aqueous alkali hydroxide solution, and it is advantageous to use a relatively hot solution to further increase the hydrolysis reaction rate. For example, this is a method of hydrolyzing at 70 to 90 ° C. for 16 hours using an aqueous solution containing 20 to 25% sodium hydroxide as disclosed in JP-A 61-19638. Further, in order to swell the membrane and accelerate the hydrolysis reaction rate, the mixture is hydrolyzed with a mixture of an alkali hydroxide aqueous solution and an alcohol solvent such as methyl alcohol, ethyl alcohol or propyl alcohol, or a water-soluble organic solvent such as dimethyl sulfoxide. A method of decomposing is used. For example, a method of hydrolyzing at 90 ° C. for 1 hour using an aqueous solution containing 11 to 13% potassium hydroxide and 30% dimethyl sulfoxide disclosed in JP-A-57-139127, JP-A-3-6240 This is a method of hydrolyzing at 60 to 130 ° C. for 20 minutes to 24 hours using an aqueous solution containing 15 to 50 wt% of alkali hydroxide and 0.1 to 30 wt% of a water-soluble organic compound.
[0014]
Thus, after forming an ion exchange group by hydrolysis, the ion exchange resin represented by the following formula (2) having an alkali metal ion exchange group or an alkaline earth metal ion exchange group by washing with water. Can be obtained. Furthermore, it is also possible to produce an ion exchange resin having an acid ion exchange group by acid treatment with an inorganic acid such as hydrochloric acid.
_{^{- [CF 2 CX 1 X 2}} ] a - [CF 2 -CF (-O- (CF 2 -CF (CF 2 X 3)) b -O C - (CFR 1) d - (CFR 2) e - ( ^{_{CF 2) f -X 4)]}} - (2)
(In the formula, X ¹ , X ² and X ³ are independently a halogen element or a perfluoroalkyl group having 1 to 3 carbon atoms, a is an integer of 0 to 20, b is an integer of 0 to 8, and c is 0 or 1. , D and e and f are each independently an integer of 0 to 6 (where d + e + f is not equal to 0), R ¹ and R ² are independently a halogen element or a C 1-10 perfluoroalkyl group or fluorochloroalkyl group , X ⁴ is COOZ or SO ₃ Z (Z is an alkali metal atom, an alkaline earth metal atom, or a hydrogen atom))
[0015]
The EW of the ion exchange resin used in the production method of the present invention is not particularly limited, but is 250 or more and 1200 or less, preferably 250 or more and 1000 or less, more preferably 250 or more and 800 or less, and even more preferably 250 or more and 700 or less. .
Next, the ion exchange resin produced by the above method is dissolved in water, a non-aqueous solvent, or a mixed solvent of water and a non-aqueous solvent by a general method to form a solution. Although it does not specifically limit as a non-aqueous solvent said here, Alcohol solvents, such as methanol, ethanol, and isopropanol, are preferable. Moreover, the solution-ization mentioned here also includes a state in which the ion exchange resin is dispersed in a micelle form. If the ion exchange resin is difficult to dissolve, it can also be dissolved under pressure such as heating or autoclave.
[0016]
Further, a metal oxide precursor is added to the solution containing the ion exchange resin. The addition amount of the metal oxide precursor is not particularly limited, but is 0.01 to 200 equivalents, preferably 0.1 to 100 equivalents, more preferably 0.1 to 50 equivalents with respect to 1 equivalent of the ion exchange resin. Even more preferably, it is 0.1 to 20 equivalents.
[0017]
The metal oxide precursor used in the present invention is not particularly limited, but an alkoxide containing Al, B, P, Si, Ti, Zr, and Y is preferable. Specific examples of Al alkoxides include Al (OCH ₃ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (OC ₃ H ₇ ) ₃ , Al (OC ₄ H ₉ ) ₃ , and alkoxides containing B. For example, as specific examples of alkoxides containing B (OCH ₃ ) ₃ and P, P (OCH ₃ ) ₃ and as specific examples of alkoxides containing Si, Si (OCH ₃ ) ₄ and Si (OC _As specific examples of alkoxides containing ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ , and Ti, Ti (OCH ₃ ) ₄ and Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₃ H ₇ ) ₄ , Ti (OC ₄ H ₉ ) ₄ and Zr-containing specific examples of alkoxide include Zr (OCH ₃ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC _{3 H 7) 4, Zr (OC} 4 H 9) 4 and the like. Specific examples of the alkoxide containing Y include Y (OC ₄ H ₉ ) ₃ . These may be used alone or in combination of two or more. Moreover, La [Al (i-OC 3 H 7) 4] 3, Mg [Al (i-OC 3 H 7) 4] 2, Mg [Al (sec-OC 4 H 9) 4] 2, Ni [Al Bimetallic alkoxides such as (i-OC ₃ H ₇ ) ₄ ] ₂ , (C ₃ H ₇ O) ₂ Zr [Al (OC ₃ H ₇ ) ₄ ] ₂ , Ba [Zr ₂ (OC ₂ H ₅ ) ₉ ] ₂ May be used.
[0018]
When the solution containing the ion exchange resin contains water, hydrolysis and polycondensation reaction of the metal oxide precursor starts simultaneously with the addition of the metal oxide precursor. When the solution containing the ion exchange resin is non-aqueous or has a small water content, the metal oxide precursor is added, and after stirring, water is added and stirred to start hydrolysis and polycondensation reaction of the metal oxide precursor. The amount of water is not particularly limited, but is 1 equivalent to 100 equivalents, preferably 2 equivalents to 80 equivalents, more preferably 3 equivalents to 50 equivalents, and even more preferably 3 to 1 equivalent of the metal oxide precursor. Equivalent to 30 equivalents.
[0019]
Although it does not specifically limit as reaction temperature, Preferably it is 1 to 100 degreeC, More preferably, it is 10 to 80 degreeC, More preferably, it is 20 to 50 degreeC. Note that the above temperature may be set from the time of addition of the metal oxide precursor. Although it does not specifically limit as reaction time, 1 second or more and 24 hours or less are preferable, More preferably, they are 30 seconds or more and 8 hours or less, More preferably, they are 1 minute or more and 1 hour or less. As the metal oxide precursor undergoes hydrolysis and polycondensation, the viscosity of the solution increases.
[0020]
In order to impart flexibility to the ion exchange resin film formed using the ion exchange resin solution of the present invention, an organosilicon compound can be added simultaneously with the addition of the metal oxide precursor.
The organosilicon compound is not particularly limited. For example, silylating agents such as trimethylchlorosilane, dimethyldichlorosilane and hexamethyldisilazane, silane coupling agents such as vinyltrichlorosilane and vinyltrimethoxysilane, and others, ethyldichlorosilane, Examples include ethyltrichlorosilane, dimethyldichlorosilane, tetraisocyanate silane, tetramethylsilane, trichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, methyldichlorosilane, methyltrichlorosilane, monomethyltriisoisanate silane, and diethoxydimethylsilane.
[0021]
In addition, a drying control agent may be added to prevent cracking of the ion exchange resin membrane. Although it does not specifically limit as a drying control agent, Dimethylformamide, formamide, etc. are mentioned.
A film obtained by adding a metal oxide precursor to a solution containing the ion exchange resin produced as described above, and subjecting the metal oxide precursor to hydrolysis and polycondensation reaction is cast on a substrate. By doing so, an ion exchange resin membrane can be obtained. Although it does not specifically limit as a viscosity of this liquid, It is preferable that it is 1-100000 cps. The liquid may contain an unreacted metal oxide precursor.
[0022]
The casting method is not particularly limited, and for example, a known coating method such as a gravure roll coater, a natural roll coater, a reverse roll coater, a knife coater, or a dip coater can be used.
Further, the substrate is not particularly limited, but a general polymer film, metal foil, a substrate such as alumina or Si, a porous film obtained by stretching a PTFE film described in JP-A-8-162132, JP The fibrillated fibers shown in Japanese Patent Publication No. 53-149981 and Japanese Patent Publication No. 63-61337 can be used.
[0023]
After casting, it is solidified by drying and / or heat treatment by a known method such as hot air drying to obtain an ion exchange resin membrane. When the ion exchange resin membrane thus formed is used for a fuel cell, there are cases where the whole substrate is used, and only the ion exchange resin membrane is used after peeling the ion exchange resin membrane from the substrate. is there.
The EW of the ion exchange resin membrane obtained by the production method of the present invention is not particularly limited, but is 250 or more and 1200 or less, preferably 250 or more and 1000 or less, more preferably 250 or more and 800 or less, and even more preferably 250 or more and 700 or less. It is. Although it does not specifically limit as thickness, It is preferable that it is 1 micrometer or more in order to make a gas permeability low, and it is 500 micrometers or less which makes the electrical resistance at the time of electric power generation small.
[0024]
The ion exchange resin membrane obtained by the production method of the present invention contains a metal oxide. Although it does not specifically limit as a metal oxide, It is preferable that it is an oxide which consists of Al, B, P, Si, Ti, Zr, and Y. The content of the metal oxide is not particularly limited, but it is 1 wt% or more and sufficient proton conductivity is obtained in order to obtain an ion exchange resin membrane that does not dissolve in water and has a small dimensional change due to water absorption and dehydration. Therefore, it is preferably 90 wt% or less. More preferably, they are 2 wt% or more and 70 wt% or less, More preferably, they are 5 wt% or more and 50 wt% or less.
[0025]
Further, by appropriately using the production method of the present invention, an ion exchange resin membrane can be obtained in which the dimensional change of the membrane accompanying water absorption and dehydration is small. The dimensional change referred to here is the film area after being immersed in water at 30 ° C. for 24 hours and the film area after being dried under reduced pressure at 30 ° C. for 8 hours, and expressed as the rate of change. Evaluate with. When used in a fuel cell, there is no particular limitation to satisfy the durability, but it is preferably 100% or less, more preferably 50% or less, and even more preferably 30% or less.
[0026]
Furthermore, by appropriately using the production method of the present invention, an ion exchange resin membrane that is difficult to dissolve in water even if the EW is small can be obtained. The solubility in water is evaluated by the weight reduction rate of the membrane before and after immersing the membrane in 90 ° C. water for 8 hours. When used in a fuel cell, it is not particularly limited, but it is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less.
Next, the case where the ion exchange resin membrane obtained by the manufacturing method of the present invention is used for a fuel cell will be described.
[0027]
When the ion exchange resin membrane of the present invention is used for a polymer electrolyte fuel cell, it is used as a membrane electrode assembly (MEA) in which two types of electrodes of an anode and a cathode are joined on both sides. The electrode is composed of fine particles of a catalytic metal and a conductive agent supporting the fine particle, and a water repellent is included as necessary. The catalyst used for the electrode is not particularly limited as long as it is a metal that promotes hydrogen oxidation and oxygen reduction. Platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium , Tungsten, manganese, vanadium, or alloys thereof. Of these, platinum is mainly used. In order to produce MEA from the electrode and the ion exchange resin membrane of the present invention, for example, the following method is performed. A platinum-supported carbon serving as an electrode material is dispersed in a solution obtained by dissolving a fluorine-based ion exchange resin in a mixed solution of alcohol and water to form a paste. A certain amount of this is applied to a PTFE sheet and dried. Next, the application surfaces of the PTFE sheet are faced to each other, an ion exchange resin film is sandwiched therebetween, and transfer bonding is performed by hot pressing. The hot press temperature depends on the type of the ion exchange resin membrane, but is usually 100 ° C. or higher, preferably 130 ° C. or higher, more preferably 150 ° C. or higher.
[0028]
The polymer electrolyte fuel cell includes the MEA manufactured as described above, a current collector, a fuel cell frame, a gas supply device, and the like. Among them, the current collector (bipolar plate) is a graphite or metal flange having a gas flow path on the surface and the like, and supplies hydrogen and oxygen to the MEA surface in addition to transmitting electrons to an external load circuit. Has a function as a flow path. By inserting a plurality of MEAs between such current collectors and stacking them, a fuel cell is manufactured. The fuel cell is operated by supplying hydrogen to one electrode and oxygen or air to the other electrode. The higher the operating temperature of the fuel cell, the higher the catalyst activity. Therefore, the fuel cell is preferably operated at 50 ° C to 100 ° C, where moisture management is easy, but it may be operated at 100 ° C to 150 ° C. A higher supply pressure of oxygen or hydrogen is preferable because the fuel cell output increases, but it is preferable to adjust the pressure to an appropriate pressure range so as not to damage the membrane.
[0029]
The ion exchange resin membrane formed from the ion exchange resin solution of the present invention can be used for chloralkali, water electrolysis, hydrohalic acid electrolysis, salt electrolysis, oxygen concentrator, humidity sensor, gas sensor, etc. in addition to fuel cells. It is also possible to use it.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not restrict | limited to an Example.
[0031]
[Example 1]
As an ion exchange resin precursor, a fluorocarbon copolymer of CF ₂ CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ —SO ₂ F was used. The EW of this ion exchange resin precursor was 614, and the melt index (MI (g / 10 minutes)) measured at a temperature of 270 ° C. and a load of 2.16 kg based on JIS K-7210 was 44230. About 1 g of a molded product obtained by melt-extruding this ion exchange resin precursor and molded to a thickness of 500 μm was converted to a reaction liquid containing 15 wt% potassium hydroxide, 30 wt% dimethyl sulfoxide and 55 wt% water at 60 ° C. For 4 hours to perform hydrolysis treatment.
[0032]
Then, it was washed with ion exchange water at 30 ° C. and then immersed in a 2N hydrochloric acid aqueous solution at 30 ° C. for 3 hours, and then the acid was washed out with ion exchange water to obtain an ion exchange resin having a sulfonic acid group.
1.4 g of a mixed solvent in which tetraethoxysilane and methanol are mixed at a weight ratio of 1: 1 is added to 2 g of a 50% solution obtained by dissolving the ion exchange resin in ion exchange water at 60 ° C. The polycondensation reaction was started. The liquid was stirred at 60 ° C. to advance the reaction. When the liquid became highly viscous, the liquid was poured into the petri dish. This liquid was dried at room temperature overnight and then heat-treated at 110 ° C. to obtain an ion exchange resin membrane of the present invention.
[0033]
Next, this membrane was vacuum-dried at 30 ° C. for 8 hours, and the membrane weight W ₁ (g) was measured. After weighing, the membrane was again placed in ion exchange water and immersed at 90 ° C. for 8 hours. After cooling, the membrane was taken out of the water and washed with ion exchange water. The membrane was again vacuum dried at 30 ° C. for 8 hours, and the film weight W ₂ (g) was measured. When the weight reduction rate Y (%) by the boiling treatment on the basis of the dry weight before the boiling treatment was calculated by the following formula, the weight reduction rate was 4%.
Y = (W ₁ −W ₂ ) / W ₁ × 100
[0034]
[Comparative Example 1]
When the ion exchange resin produced by the same method as in Example 1 was put in ion exchange water as it was and immersed at 90 ° C. for 8 hours, it was completely dissolved in water.
[0035]
[Example 2]
As an ion exchange resin precursor, a fluorocarbon copolymer (EW: 673, MI: 2061) of CF ₂ CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ —SO ₂ F is used. It was. A molded body of an ion exchange resin having about 1 g of a sulfonic acid group was obtained in the same manner as in Example 1.
1.4 g of a mixed solvent in which tetraethoxysilane and methanol are mixed at a weight ratio of 1: 1 at 60 ° C. is added to 2 g of a 50% solution obtained by boiling the ion exchange resin in ion exchange water. Stirring to initiate the hydrolysis and polycondensation reaction. The liquid was stirred at 60 ° C. to advance the reaction. When the liquid became highly viscous, the liquid was poured into the petri dish. This liquid was dried at room temperature overnight and then heat-treated at 110 ° C. to obtain an ion exchange resin membrane of the present invention having a thickness of 100 μm.
[0036]
Next, this membrane was immersed in ion-exchanged water at 30 ° C. for 1 day, and then the membrane was taken out and measured for dimensions to calculate membrane area A ₁ . This film was vacuum-dried at 30 ° C. for 8 hours, and then the dimension of the film was measured again to calculate the film area A ₂ . The dimensional change D when wet and dry was calculated by the following formula and found to be 90%.
D = (A ₁ −A ₂ ) / A ₁ × 100
[0037]
[Comparative Example 2]
Using the same ion exchange resin precursor as in Example 2, an ion exchange resin film having a thickness of 100 μm was obtained in the same manner as in Example 1. When the dimensional change of this membrane was measured in the same manner as in Example 2 when wet and dry, it was 150%.
[0038]
【Effect of the invention】
The ion exchange resin membrane obtained by the production method of the present invention is very effective as a fuel cell application because it has a small membrane dimensional change due to water absorption and dehydration and is hardly soluble in water even when EW is small. .

Claims (5)

A metal oxide precursor selected from Al, Si, and Y is added to a solution containing an ion exchange resin represented by the following formula (2) having a sulfonic acid group or a carboxylic acid group having an EW of 250 or more and 800 or less. A method for producing an ion exchange resin membrane for a fuel cell , characterized in that a liquid obtained by adding and hydrolyzing and polycondensing the metal oxide precursor is cast into a membrane.
_{^{- [CF 2 CX 1 X 2}} ] a - [CF 2 -CF (-O- (CF 2 -CF (CF 2 X 3)) b -O C - (CFR 1) d - (CFR 2) e - ( _{^{CF 2) f -X 4)]}} - (2)
(In the formula, X ¹ , X ² and X ³ are independently a halogen element or a perfluoroalkyl group having 1 to 3 carbon atoms, a is an integer of 0 to 20, b is an integer of 0 to 8, and c is 0 or 1. , D and e and f are each independently an integer of 0 to 6 (where d + e + f is not equal to 0), R ¹ and R ² are independently a halogen element or a C 1-10 perfluoroalkyl group or fluorochloroalkyl group , X ⁴ is COOZ or SO ₃ Z (Z is a hydrogen atom)) 2. The method for producing an ion exchange resin membrane according to claim 1, wherein the ion exchange resin is represented by the above formula (2) (where b = 0). Claim 1 or 2 for a fuel cell ion exchange resin membrane, characterized in that is manufactured by the method described in. A membrane electrode assembly comprising the ion exchange resin membrane according to claim 3 . A solid polymer fuel cell comprising the ion exchange resin membrane according to claim 3 .