JP2002343380A - Electrolyte film for solid polymer fuel cell, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte film composed of a positive ion exchange film having low resistance and small dimensional variation even when water is absorbed, and to provide a solid polymer fuel cell having the polymer electrolyte film. SOLUTION: The manufacturing method of the electrolyte film for the solid polymer fuel cell includes an extension process after laminating an extension supporting film on at least one surface of a positive ion exchange film composed of perfluorocarbon polymer containing sulfonic acid group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer electrolyte fuel cell, and more particularly to an electrolyte membrane for a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art A hydrogen / oxygen fuel cell has attracted attention as a power generation system whose reaction product is only water in principle and has almost no adverse effect on the global environment. Solid polymer fuel cells were once mounted on spacecraft in the Gemini and Biosatellite programs, but the power density at that time was low. Since then, higher performance alkaline fuel cells have been developed, and up to the present space shuttle, alkaline fuel cells have been adopted for space applications.

However, polymer electrolyte fuel cells have attracted attention again in recent years due to technological advances. The reasons are as follows. (1) A highly conductive film was developed as a solid polymer electrolyte. (2) The catalyst used for the gas diffusion electrode layer is supported on carbon, and this is coated with an ion exchange resin, whereby high activity can be obtained.

At present, a membrane generally used as a solid polymer electrolyte has high proton conductivity, and therefore can exhibit low resistance and high battery performance. On the other hand, since a film having a lower resistance generally has a higher water content, the size of the film tends to increase in the length direction when the film is wet, and various adverse effects are likely to occur. For example, when an operation is performed by incorporating a membrane electrode assembly in which a membrane is sandwiched between a pair of electrodes into a fuel cell unit, the membrane swells due to water generated by the reaction or water vapor supplied together with the fuel gas. , Increasing the dimensions of the membrane. Normally, since the film and the electrode are bonded, the electrode also follows the dimensional change of the film. Since the membrane electrode assembly is restrained by a separator or the like in which a groove is formed as a gas flow path, an increase in dimension becomes a "wrinkle". Then, the wrinkles may fill the grooves of the separator and obstruct the gas flow.

Therefore, the solid polymer electrolyte membrane needs to have a low resistance and a small dimensional change when containing water, and it is preferable that the membrane does not easily swell with a solvent in a coating liquid for producing an electrode. However, as described above, it is difficult to obtain a film that satisfies all of these requirements with the conventional technology.

As a method for solving the above-mentioned problem, a method in which a reinforcing material is combined with a film to achieve the above-mentioned characteristics can be considered.
Specifically, polytetrafluoroethylene (hereinafter, PTF)
E. A method has been proposed in which a porous membrane is impregnated with a fluorinated ion exchange polymer having a sulfonic acid group (Japanese Patent Publication No. 5-75835). However, with a PTFE porous membrane,
It is not possible to suppress the stress at which the ion-exchange membrane stretches when it contains water.

Further, a cation exchange membrane reinforced with a fibril-shaped, woven or non-woven perfluorocarbon polymer has been proposed (JP-A-6-231779).
This film can reduce the dimensional change rate when it contains water, but has a thickness of at most 100 to 200 μm, and cannot realize a sufficiently low resistance.

Further, as a means for obtaining a thin film while improving the strength of the film, a method has been proposed in which an electrolyte membrane is biaxially stretched in a temperature range from a glass transition temperature to a melting point (JP-A-11-354140). Although this method is effective for improving the strength properties, even if the film is stretched in the above temperature range, it is not possible to suppress the dimensional change of the film when it contains water.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for producing an electrolyte membrane for a polymer electrolyte fuel cell which has a low resistance and a small dimensional change when containing water, whereby a high output can be stably obtained. An object is to provide a polymer electrolyte fuel cell.

[0010]

According to the present invention, there is provided a solid polymer comprising the steps of: laminating a stretching auxiliary film on at least one surface of a cation exchange membrane comprising a perfluorocarbon polymer having a sulfonic acid group; Provided is a method for manufacturing an electrolyte membrane for a fuel cell.

In the present invention, when a cation exchange membrane serving as an electrolyte membrane is subjected to a stretching treatment, if only the cation exchange membrane is subjected to a stretching treatment, it is easy to be broken and it is difficult to make the cation exchange membrane thin evenly. When stretched
The film that becomes the electrolyte membrane can be made uniform and thin. That is, the stretching auxiliary film in the present invention is a film that is laminated to assist the stretching of the film serving as the electrolyte membrane.

The film stretched by the above-mentioned method can be not only uniform and thin, but also can reduce the dimensional change rate when it contains water. Cheap.

Further, the present invention comprises a cation exchange membrane having a specific resistance of 20 Ω · cm or less, a dimensional change rate of -5% to + 5% when containing water, and a thickness of 3 to 90 μm. An electrolyte membrane for a polymer electrolyte fuel cell is provided.

Here, the specific resistance of the film in the present specification is:
Indicates the film resistance per unit area, specifically 80 ° C.
It refers to a film resistance value per unit area measured by a four-terminal AC method in a 95% humidity atmosphere. The specific resistance of the membrane is
It is a factor that directly affects the power generation characteristics of the fuel cell, and the lower the specific resistance, the better. Specific resistance is 20Ω · cm
If it exceeds, the resistance loss of the battery increases and the power generation efficiency decreases. In order to improve battery performance, it is more preferable that the resistance is 10 Ω · cm or less.

In this specification, the dimensional change rate of a film when it is hydrated means that the film is changed from an atmosphere at 25 ° C. and a humidity of 50% to 25%.
The dimensional change ratio in the length direction of the film when immersed in water at ° C. and held for 60 minutes or more is shown. In the present invention, the dimensional change rate of -5% to + 5% means that the dimensional change rate is -5% to + 5% regardless of the length of the film in any direction.

If the dimensional change rate of the electrolyte membrane is out of the range of -5% to + 5%, the dimensions of the membrane change due to the humidity of the atmosphere in which the membrane is handled, and a problem tends to occur in the handleability of the membrane. In addition, when an operation is performed by incorporating a membrane electrode assembly in which a membrane is combined with an electrode into a fuel cell, the membrane swells and its dimensions increase, and the electrodes bonded to the membrane follow the dimensional change of the membrane.
Usually, since the joined body is restrained by a separator or the like, it becomes a "wrinkle", and there is a possibility that the groove of the wrinkled separator is filled and the flow of gas is hindered.

When the thickness of the electrolyte membrane is less than 3 μm, the strength of the membrane is weak and the handling property is poor, and the membrane electrode for arranging and bonding electrodes on both sides of the membrane and incorporating it into a polymer electrolyte fuel cell. There is a possibility that the film may be broken at the time of producing the joined body. On the other hand, if the thickness of the electrolyte membrane is too large, the movement of water in the membrane during power generation is hindered, and the power generation characteristics deteriorate. During power generation, the water content differs between the anode side and the cathode side of the membrane, and a distribution of the water content can be formed in the thickness direction. This is one of the causes of lowering the power generation characteristics, and the thicker the film, the more remarkable this phenomenon.

According to the production method of the present invention, the electrolyte membrane can be made uniform and thin, and the dimensional change rate when hydrated can be reduced, so that the specific resistance is 20 Ω · cm or less. Has a dimensional change rate of -5% to + 5%,
An electrolyte membrane comprising a cation exchange membrane having a thickness of 3 to 90 μm is obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the production method of the present invention, it is preferable to specifically prepare an electrolyte membrane by the following procedure. (1) Kneading and pelletizing of a perfluorocarbon polymer having a sulfonic acid group precursor group by twin-screw extrusion molding. (2) Film formation by uniaxial extrusion using the above pellets. (3) Hydrolysis, acidification treatment, washing and drying. (4) Biaxial stretching after laminating the stretching auxiliary film.

The steps (1) to (4) will be described more specifically. In the step (1), the perfluorocarbon polymer powder having a sulfonic acid group precursor group is biaxially extruded and formed into pellets. Here, the precursor group of the sulfonic acid group refers to a group that becomes a sulfonic acid group by hydrolysis or the like, and specifically indicates a —SO ₂ F group, a —SO ₂ Cl group, or the like.
In step (2), the pellets obtained in step (1)
Preferably, it is extruded under heating and formed into a film. In addition, directly without the step of pelletizing (1),
It may be extruded and formed into a film in the step of uniaxial extrusion. In the case of uniaxial extrusion molding under heating, it is preferable to form the film so that the temperature of the film is about 200 to 270 ° C. When the film temperature is lower than 200 ° C., the discharge pressure becomes too high, and the productivity may be reduced. When the film temperature exceeds 270 ° C., the surface of the obtained film tends to be rough and the thickness of the film tends to be uneven.

Next, hydrolysis, acidification treatment, washing and drying are performed (step (3)) to convert the precursor group of the sulfonic acid group into a sulfonic acid group, thereby obtaining a cation exchange membrane. next,
For example, 70-
After heating and laminating using a roll press heated to about 100 ° C. and stretching, the stretching auxiliary film is peeled off to obtain a cation exchange membrane constituting an electrolyte membrane ((4)).
Process).

In the present invention, the film to be a cation exchange membrane is preferably stretched at a temperature in the range of 40 to 200 ° C., and the membrane area is preferably increased by stretching by 5 to 200%. The stretching process is a process of increasing the membrane area by applying an external force to the membrane area held by the cation exchange membrane. The stretching treatment is preferably carried out in a uniaxial or biaxial direction, but a biaxial stretching treatment is particularly preferred in order to stabilize the overall dimensions of the film in the plane direction.

In order to suppress a dimensional change when water is contained, it is necessary to leave a residual stress which contracts in the length direction on the cation exchange membrane appropriately. When the cation exchange membrane is hydrated, its dimension increases in the length direction. If the residual stress that contracts at that time is released, the stress can be eliminated and the dimension can be prevented from increasing. For this reason, in order to leave an appropriate residual stress, it is preferable to adjust the temperature and the stretching ratio during the stretching process. When the temperature of the stretching treatment is lower than 40 ° C., it is difficult to perform the stretching treatment, and it is difficult to obtain the effect of suppressing the dimensional change. Also,
At 200 ° C. or higher, the cation exchange membrane has a degree of freedom due to molecular motion, and moves following external force applied in the stretching process. For this reason, it is difficult to sufficiently leave residual stress that contracts in the length direction in the film.

The stretching ratio is preferably 5 to 200%. If it is less than 5%, the residual stress shrinking in the length direction is too small, and the effect of suppressing the dimensional increase is not sufficient.
If it exceeds 00%, the residual stress is too large, and dimensional shrinkage may occur. As described above, it is necessary to leave a residual stress commensurate with that in order to counteract the stress of the dimensional increase that occurs when water is contained. For this purpose, it is particularly preferable that the stretching temperature is 50 to 120 ° C. The magnification is preferably from 10 to 100%.

The stretching auxiliary film is not particularly limited as long as it can be stretched. For example, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyethylene film, an ethylene-α-olefin copolymer film, an ethylene-vinyl alcohol copolymer film , Ethylene-vinyl acetate copolymer film, ethylene-vinyl acetate-vinyl chloride copolymer film, ethylene-vinyl chloride copolymer film, polypropylene film, polyvinyl chloride film, polyamide film,
Examples include a polyvinyl alcohol film. Among them, a polyethylene terephthalate film or a polypropylene film is preferable.

In particular, the amorphous polyethylene terephthalate film and the cast polypropylene film can be stretched in a temperature range of 70 to 110 ° C. When these films are laminated and stretched, a moderate residual stress is applied to the cation exchange membrane. Is preferable since it can leave

In the present invention, the cation exchange membrane serving as the electrolyte membrane is preferably a cation exchange membrane made of a perfluorocarbon polymer having a sulfonic acid group. As the membrane, a cation exchange membrane made of a hydrocarbon polymer or a partially fluorinated hydrocarbon polymer can be used. The cation exchange membrane may be composed of a single ion exchange resin, or may be a mixture of two or more ion exchange resins.

As the perfluorocarbon polymer having a sulfonic acid group, a conventionally known polymer is widely used. In particular, the general formula CF ₂ = CF (OCF ₂ CFX)
_{m -O p - (CF 2)} n SO 3 H ( wherein X is a fluorine atom or a trifluoromethyl group, m is an integer of 0 to 3, n is an integer from 0 to 12, p is 0 or 1;
When n = 0, p = 0. )), A copolymer of a perfluorovinyl compound represented by the formula (1) with a perfluoroolefin or a perfluoroalkylvinyl ether. Specific examples of the perfluorovinyl compound are represented by formulas 1 to
And a compound represented by any one of the above. However,
In the following formula, q is an integer of 1 to 9, r is an integer of 1 to 8, s is an integer of 0 to 8, and z is 2 or 3.

[0029]

Embedded image

A polymer containing a polymerized unit based on a perfluorovinyl compound having a sulfonic acid group is usually -SO ₂
It is polymerized using a perfluorovinyl compound having a F group, -SO ₂ F groups are converted to -SO ₃ H groups after polymerization.
The perfluorovinyl compound having an —SO ₂ F group can be homopolymerized, but has a low radical polymerization reactivity, and thus is usually used together with a comonomer such as a perfluoroolefin or perfluoro (alkyl vinyl ether) as described above. Used after polymerization. Examples of the perfluoroolefin to be a comonomer include tetrafluoroethylene, hexafluoropropylene, and the like, but usually tetrafluoroethylene is preferably employed.

As a perfluoro (alkyl vinyl ether) serving as a comonomer, CF ₂ ＣＦCF— (OCF ₂ C
FY) a compound represented by _t -O-R ^f are preferred. However, where, Y is a fluorine atom or a trifluoromethyl group, t is an integer from 0 to 3, perfluoroalkyl group and R ^f represented by C _u F _{2u + 1} linear or branched (1
≤ u ≤ 12). More specifically, a compound represented by any one of formulas 5 to 7 is exemplified. However, in the following formula, v is an integer of 1 to 8, w is an integer of 1 to 8, and x is 2 or 3.

[0032]

Embedded image

In addition, perfluoroolefins and perful
Other than Oro (alkyl vinyl ether), 1, 1, 2,
3,3,4,4-heptafluoro-4-[(trifluoro
Fluorinated monomers such as roethenyl) oxy] -1-butene
-Also as a comonomer -SO _TwoPerfluoro having F group
It may be copolymerized with a vinyl compound.

The polymer which can constitute the electrolyte membrane of the present invention with a polymer other than the perfluorocarbon polymer is, for example, a polymer containing a polymer unit represented by the formula 8 and a polymer unit represented by the formula 9 Coalescence. Here, P ¹ is a phenyltolyl group, a biphenyltolyl group, a naphthalene reel group, a phenanthrene reel group, or an anthracene reel group, and P ² is a phenylene group, biphenylene group, naphthylene group, phenanthrylene group, anthracylene group, and A ² is a —SO ₃ M group (M is a hydrogen atom or an alkali metal atom; the same applies hereinafter), a —COOM group or a group that is converted to these groups by hydrolysis, B ¹ and B ² each independently represent an oxygen atom, It is a sulfur atom, a sulfonyl group or an isopropylidene group. Structural isomers of P ¹ and P ² is not particularly limited, one or more fluorine atoms of the hydrogen atom of the P ¹ and P ^2, a chlorine atom, be substituted by a bromine atom or an alkyl group having 1 to 3 carbon atoms Good.

[0035]

Embedded image

In the present invention, the ion exchange capacity of the electrolyte membrane is preferably 0.5 to 2.0 meq / g dry resin, particularly preferably 0.7 to 1.6 meq / g dry resin. If the ion exchange capacity is too low, the resistance will increase. On the other hand, if the ion exchange capacity is too high, the affinity for water is too strong, and the membrane may be dissolved during power generation.

The polymer electrolyte fuel cell of the present invention can be obtained according to a usual method, for example, as follows. First,
A solution of a conductive carbon black powder carrying platinum catalyst fine particles and a solution of a sulfonic acid type perfluorocarbon polymer is mixed to obtain a uniform dispersion, and a gas diffusion electrode is formed by any of the following methods to form a membrane electrode. Obtain a conjugate. As the membrane, a cation exchange membrane made of a sulfonic acid type perfluorocarbon polymer subjected to a stretching treatment is used.

The first method is a method in which the dispersion is applied to both sides of the cation exchange membrane, dried, and then both sides are brought into close contact with two sheets of carbon cloth or carbon paper. Second
Is applied to two sheets of carbon cloth or carbon paper and dried, and then sandwiched from both sides of the cation exchange membrane so that the surface to which the dispersion is applied is in close contact with the cation exchange membrane. It is a method of indenting. Here, the carbon cloth or carbon paper has a function as a gas diffusion layer for uniformly diffusing gas into the layer containing the catalyst and a function as a current collector.

The obtained membrane / electrode assembly is formed with a groove serving as a passage for a fuel gas or an oxidizing gas, sandwiched between separators, and assembled into a cell to obtain a polymer electrolyte fuel cell. Here, as the separator, for example, a separator made of a conductive carbon plate can be used.

In the polymer electrolyte fuel cell obtained as described above, hydrogen gas is supplied to the anode side, and oxygen or air is supplied to the cathode side. At the anode, a reaction of H ₂ → 2H ⁺ + 2e ⁻ occurs, and at the cathode, a reaction of 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O occurs, whereby chemical energy is converted into electric energy.

[0041]

EXAMPLES Example 1 (Example) Polymerized units based on tetrafluoroethylene and CF ₂ ＣＦCFOCF ₂ CF (CF ₃ )
A copolymer powder composed of polymerized units based on O (CF ₂ ) ₂ SO ₂ F (ion exchange capacity: 1.1 meq / g dry resin) was biaxially extruded to obtain pellets. Next, the pellets are formed into a film by a single screw extruder and have a thickness of 55 mm.
A film having a thickness of μm was prepared, hydrolyzed using an aqueous solution containing dimethyl sulfoxide and potassium hydroxide, converted to an —SO ₂ F group into an —SO ₃ H group by acidification with hydrochloric acid, and then washed. After drying, a film having a thickness of 60 μm was obtained.

Next, as a stretching auxiliary film, a film having a thickness of 200
This film was sandwiched from both sides with two μm amorphous polyethylene terephthalate films, and heated and roll-pressed at 80 ° C. to produce a film in which a stretching auxiliary film was laminated on both sides. The length of each of these laminated films at 90 ° C. with respect to each axial direction (the direction (MD direction) through a single-screw extruder (MD direction) and the direction perpendicular to the MD direction (TD direction)) is 40%.
The film was biaxially stretched so that the area increase rate was 96%. Next, the stretch assisting film was peeled off to obtain a stretched film. The thickness of the obtained film was measured at 10 points at intervals of 5 cm, and the average value of the film thickness was calculated. Table 1 shows the stretching conditions and the measurement results of the film thickness before and after the stretching.

[Measurement of Membrane Resistance] A strip-shaped film sample having a width of 5 mm was prepared from the above-mentioned stretched film, and a platinum wire (diameter:
0.2 mm) is pressed in parallel with the width direction at 5 mm intervals, and the sample is held in a constant temperature / humidity chamber at 80 ° C. and a relative humidity of 95%. Was measured to determine an AC specific resistance. Since five platinum wires are pressed at 5 mm intervals, the distance between the electrodes can be changed to 5, 10, 15, and 20 mm. Therefore, the AC resistance at each distance between the electrodes is measured, and the distance between the electrodes and the resistance are measured. The influence of the contact resistance between the platinum wire and the membrane was excluded by calculating the specific resistance of the membrane from the gradient. A good linear relationship was obtained between the distance between the poles and the measured resistance, and the effective resistance was calculated from the slope and the thickness. Table 2 shows the results
Shown in

[Measurement of Dimensional Change When Water is Included] A 200 mm square sample was cut out from the above stretched film and exposed to an atmosphere at a temperature of 25 ° C. and a humidity of 50% for 16 hours.
Each length in the TD direction was measured. Next, the sample was immersed in ion-exchanged water at 25 ° C. for 1 hour, and the lengths in the MD and TD directions were measured in the same manner. The dimensional change rate was calculated from the elongation of the sample at this time. Table 1 shows the results.

[Production and Evaluation of Fuel Cell] The fuel cell was assembled as follows. Polymerized units based on tetrafluoroethylene and CF ₂ ＣＦCF—OCF ₂ CF (CF
₃ ) Ethanol containing a copolymer consisting of polymerized units based on O (CF ₂ ) ₂ SO ₃ H (ion exchange capacity 1.1 meq / g dry resin) and platinum-supported carbon in a mass ratio of 1: 3 Was applied to both surfaces of the stretched film by a die coating method, and dried to form an electrode layer having a thickness of 10 μm and a platinum carrying amount of 0.5 mg / cm ² . Further, carbon cloths were arranged on both outer sides as gas diffusion layers to produce a membrane electrode assembly. On both sides of this membrane electrode assembly, a separator made of a carbon plate obtained by cutting a narrow groove for a gas passage into a zigzag shape, and further, a heater is arranged outside the separator.
A polymer electrolyte fuel cell having an effective membrane area of 25 cm ² was assembled.

The temperature of the fuel cell was maintained at 80 ° C., and air was supplied to the cathode and hydrogen was supplied to the anode at 0.15 MPa, respectively. Current density 0.1 A / cm ^2, and the terminal voltage when the 1A / cm ² were measured. Table 2 shows the results.

[Example 2] The area increase rate during biaxial stretching was 30.
%, A sample was prepared in the same manner as in Example 1, and evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties and preparation conditions of the film, and Table 2 shows the results.

[Example 3] The atmosphere temperature of biaxial stretching was 110 ° C.
A sample was prepared in the same manner as in Example 1 except that the sample was changed to, and evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties and preparation conditions of the film, and Table 2 shows the results.

Example 4 A sample was prepared in the same manner as in Example 1 except that the atmosphere temperature and the area increase rate of the biaxial stretching were changed to 75 ° C. and 15%, respectively, and evaluated in the same manner as in Example 1. Was. Table 1 shows the physical properties and preparation conditions of the film, and Table 2 shows the results.

[Examples 5 and 6] Each of the membranes had an ion exchange capacity of 0.91 meq. / G (Example 5), and 1.33 m
eq. A sample was prepared in the same manner as in Example 3 except that the sample having the / g (Example 6) was used, and the evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties and preparation conditions of the film, and Table 2 shows the results.

[Examples 7 and 8 (Comparative Examples)] Each of the membranes had an ion exchange capacity of 1.1 meq. / G (Example 7), and 0.91 meq. / G (Example 8) was evaluated in the same manner as in Example 1 without biaxial stretching. Table 1 shows the physical properties of the film.
Table 2 shows the results. In addition, when the coating liquid for forming an electrode layer is applied to the membranes of the membranes of Examples 7 and 8 to obtain a membrane electrode assembly, the membrane swells and deforms to form a uniform electrode layer. However, a membrane electrode assembly that could be assembled and evaluated as a fuel cell was not obtained. Therefore, the output characteristics could not be evaluated.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

According to the present invention, a cation exchange membrane having a low electric resistance and a small dimensional change when containing water can be obtained.
When operating a polymer electrolyte fuel cell incorporating a membrane electrode assembly formed by joining electrodes to a membrane, no wrinkles occur even when the membrane electrode assembly is restrained by a separator, etc. The grooves are not filled with the membrane / electrode assembly and the flow of gas is not hindered.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 228/02 C08F 228/02 C08J 5/22 101 C08J 5/22 101 CEU CEU H01M 8/10 H01M 8 / 10 // B29K 27:12 B29K 27:12 B29L 7:00 B29L 7:00 F term (reference) 4F071 AA07 AA26 AA26X AA27X AA39X AF54 AH15 FA05 FC02 FD02 FE06 4F100 AK17A AL01B AL01C AL07A AR00B AR00B BA03 BA03 BA03 BA03 EJ37C GB41 JB20A JG01B JG01C JL04 YY00B YY00C 4F210 AA16 AC03 AD05 AD08 AD35 AE03 AG01 AH33 AR04 AR06 AR12 QA02 QC05 QD22 QG01 QG15 QG18 QW50 4J100 AC26Q AE39P AP01P06H06 HBBAH08A

Claims (7)

[Claims] 1. A method for producing an electrolyte membrane for a polymer electrolyte fuel cell, comprising: laminating a stretching auxiliary film on at least one surface of a cation exchange membrane comprising a perfluorocarbon polymer having a sulfonic acid group, and stretching. Method. 2. The production of an electrolyte membrane for a polymer electrolyte fuel cell according to claim 1, wherein the cation exchange membrane is stretched in a temperature range of 40 ° C. or more and less than 200 ° C. to increase the membrane area by 5 to 200%. Method. 3. The method for producing an electrolyte membrane for a polymer electrolyte fuel cell according to claim 1, wherein the thickness of the cation exchange membrane is 3 to 90 μm by stretching. 4. The method according to claim 1, wherein the perfluorocarbon polymer is CF.
Polymerized units based on ₂ = CF ₂ and CF ₂ = CF (OCF ₂ CF
_{X) m -O p - (CF} 2) n SO 3 polymerized units (wherein X based on H is a fluorine atom or a trifluoromethyl group,
m is an integer of 0 to 3, n is an integer of 0 to 12,
p is 0 or 1, and when n = 0, p = 0. The method for producing an electrolyte membrane for a polymer electrolyte fuel cell according to any one of claims 1 to 3, which is a copolymer comprising: 5. The specific resistance is not more than 20 Ω · cm, the dimensional change rate when containing water is -5% to + 5%, and the thickness is 3 to 5%.
An electrolyte membrane for a polymer electrolyte fuel cell, comprising a cation exchange membrane having a thickness of 90 μm. 6. The electrolyte membrane for a polymer electrolyte fuel cell according to claim 5, wherein said cation exchange membrane is obtained by the method according to any one of claims 1 to 4. 7. A gas diffusion electrode is disposed on both surfaces of the electrolyte membrane according to claim 5 and a separator having a groove serving as a gas flow path formed on the surface is disposed outside the gas diffusion electrode. Characteristic polymer electrolyte fuel cell.