JP2003077492A - Proton conductive membrane for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a membrane which has a high strength and small anisotropy of strength in the membrane and has good oxidation resistance and heat resistance, and shows a high proton conductivity, and a solid polymer electrolyte type fuel cell using this membrane which has a high output and excellent durability. SOLUTION: An inorganic compound of fine powder is uniformly dispersed in a fluorine-contained system polymer. The fine particle has a particle size of 15 μm or less and is made a ratio of 30-80 parts weight and is made a membrane shape of a thickness of 20-300 μm, thereby, has a high proton conductivity and can be used suitably as an electrolyte for a fuel cell.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention discloses a technique relating to a new proton conductive solid polymer electrolyte used in a solid polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In recent years, research and development of solid polymer electrolyte fuel cells using a proton conductive polymer membrane as an electrolyte have been advanced. BACKGROUND ART A solid polymer electrolyte fuel cell has characteristics that it operates at a low temperature, has a high output density, and can be miniaturized, and is regarded as suitable for an on-vehicle power source, a household power source and other applications.

Currently, a proton conductive ion exchange membrane having a thickness of 20 to 200 μm is usually used for a solid polymer electrolyte for a solid polymer electrolyte fuel cell. Since the fuel cell operates in a high temperature oxidizing atmosphere, the electrolyte used for this is required to have heat resistance and oxidation resistance. In particular, a cation exchange membrane made of a perfluorocarbon-based polymer having a sulfonic acid group has excellent characteristics. Therefore, it is widely considered. In particular, the membrane is required to have high proton selective permeability.

In order to reduce the internal resistance of the fuel cell, it is necessary to reduce the electric resistance of the cation exchange membrane, and the method is to increase the amount of sulfonic acid groups in the membrane and to reduce the film thickness. Is being reduced. However, when the amount of the sulfonic acid group is remarkably increased, the mechanical strength of the membrane is lowered, the membrane is apt to creep in the long-term operation of the fuel cell, and the durability of the fuel cell is lowered. On the other hand, if the film thickness is reduced, the mechanical strength of the film decreases, and it becomes difficult to process the film when bonding it to the gas diffusion catalyst layer electrode, and the film itself becomes difficult to handle, and there is a limit. Therefore, as disclosed in Japanese Patent Laid-Open No. 2001-35508, it has been proposed to disperse fibrillated polytetrafluoroethylene in the film to maintain the strength of the film and reduce the film thickness. There is. Newer and better materials are needed.

Further, hydrogen and oxygen are usually used as fuels for solid polymer electrolyte fuel cells, but problems remain in the transportation of hydrogen. That is, it is dangerous to mount hydrogen on a vehicle, and therefore various hydrogen storage and transportation methods are being studied, but at the same time, fuel cells using methyl alcohol as fuel without using hydrogen are being actively studied. However, methyl alcohol permeates the cation exchange membrane made of a perfluorocarbon polymer and reduces the power generation efficiency of the fuel cell. Therefore, as shown in Table 2000-516014, inorganic compounds such as zirconium phosphate and titanium oxide can be deposited on the cation exchange membrane made of perfluorocarbon polymer to reduce the amount of methanol permeation through the membrane. However, the amount of inorganic substances deposited in the membrane is limited, and it is difficult to significantly reduce the amount of methanol permeating the membrane.

Inorganic compounds are preferable materials as one of the materials for the electrolyte of the fuel cell. One method using a finely divided inorganic ion exchanger as a membrane material is disclosed in Patent No. 117044.
It is disclosed in 4. It has been proposed that after heat-press molding a fine powder of polytetrafluoroethylene and a cation-exchangeable inorganic ion-exchanger to form a block, the block is sliced into an oxidation-resistant cation-exchange membrane. ing. However, since polytetrafluoroethylene does not melt, the resulting film is essentially porous, and slicing into a thin film into a film is not industrial. Actually, the selective permeability of cations is extremely low, and the permeability of protons has not been evaluated at all. Japanese Patent No. 1303566 reports that a fluorine-containing anion-exchange polymer electrolyte and a fine powder of an inorganic ion-exchanger of 100 μm or less are used to form an ion-exchange membrane. However, it is a membrane intended for a diaphragm for electrolysis of sodium chloride, and a polymer of perfluorocarbon sulfonic acid is used as a fluorine-containing anion-exchange polymer electrolyte. However, when a polymer of perfluorocarbon sulfonic acid is used, the mechanical strength of the membrane is lowered, and the membrane is apt to creep during long-term operation of the fuel cell, which causes the durability of the fuel cell to be lowered. There is no evaluation of the proton conductivity of the membrane.

[Problems to be Solved by the Invention]

As a result of intensive investigations by the present inventors on a proton conductor having oxidation resistance and heat resistance and capable of long-term operation, a fine powdery inorganic compound having a particle size of 15 μm or less in one direction was selected. It has been found that forming a film having a predetermined thickness in the presence of a fluorine-containing polymer having oxidation resistance and a compound having a polar group provides an excellent fuel cell electrolyte.

The membrane of the present invention has high strength, little in-plane strength anisotropy, oxidation resistance and heat resistance, and high proton conductivity. By using the membrane of the present invention, a solid polymer electrolyte fuel cell having high output and excellent durability can be obtained.

According to the present invention, fine particles of an inorganic compound having a particle size of 15 μm or less in one direction and a fluorine-containing polymer are used in the presence of a low-molecular compound having a polar group. It can be obtained by forming a film into a film.

The present inventors have found that they have high oxidation resistance and heat resistance
In terms of conductivity, inorganic compounds are used as fuel cell electrolytes.
Various studies were conducted on the use of the
It is difficult to make a thin film. Therefore, finely divided inorganic compounds
The fine powder of the substance is made of a fluorine-based polymer having heat resistance and oxidation resistance.
When I tried to mold it into a membrane, the unexpectedly high prototype
The present invention was found to find that a film having high conductivity is obtained.
completed. That is, the inorganic compound is simply formed into a film with a fluorine-containing polymer.
A membrane having proton conductivity cannot be obtained even if it is molded into.
The particle size of the fine particles of the inorganic compound is at least 15μ in one direction.
Proton conductivity is remarkable when using fine particles of m or less
Become. For example, anatase and rutile used for photocatalyst
Type TiO less than 15 μm, especially less than 50 nm₂Membrane using
Has not been elucidated for the
It exhibits conductivity. Such ultrafine particles of 50 nm or less
BiO is suitable for use as₂, CeO₂, CuO, SnO₂,
Y₂O₃, Nb₂O_Five, MoO₃, WO₃, B₂O_Five, V₂O_Five, Al₂O₃, ZrO₂, S
iO₂, ZnO, Cr₂O₃, Fe₂O₃, TaC, TiC, NbC, SiC, AlN, Si
₃N_Four, BN, Zr₃N_Four, TiN, ZrO₂, HfO₂, ThO ₂, Y₂O₃, Yb
₂O_3, There are CdS etc. Also, CsHSeO_Four, CsHSO_Four, CsH₂PO_Four 
Etc., for example, β-Cs₃(HSO_Four)₂[H_2-x(S_xP_1-x) O_Four] (here
X is 0, 1) and so on is also very effective. In the present invention,
It is a fine powder of known ingredients made by a known method and has the above particle size.
In producing a proton conductive film
If necessary, one or more can be used.

Fine particles of an inorganic compound having a cation exchange property and having a particle size of 15 μm or less in one direction are particularly effective. Specifically, zirconium phosphate,
As represented by zirconium silicate, zirconium stannate, zirconium tungstate, titanium phosphate, cerium phosphate, titanium arsenate, tin antimonate, etc., Mx
Oy (PzOw) nH ₂ Ox has a structure of x, y, n, z,
w is an integer, M is Zr, Ti, Sn, Th, U, cerium, niobium, tartan, etc., and (PzOw) is phosphoric acid, arsenic acid, antimonic acid, vanadic acid, molybdic acid, tungstic acid, oxalic acid, Polyphosphoric acid and the like are common.

Hydroxides and hydrous oxides are also effective. I.e.
General formula MxOy nH₂O (x, y, n are positive integers),
For example, those exhibiting cation exchange properties are Mn⁴⁺, Nb⁵⁺, Ta⁵⁺,
Sb⁵⁺, Si⁴⁺, Mo⁶⁺And so on. Also with heteropoly acids
Then H₂XY₁₂O ₄₀ nH₂Is denoted by O (X is P, As,
 Ge, Si, etc., Y is Mo, W, V, etc., n is a positive integer.)
For example, ammonium molybdate and tungstophosphate
Monium, etc.

Cyanide complexes can also be used as cation exchangers. It is represented by the general formula MX [Y (CN) ₆ ], where M is an alkali metal ion, hydrogen ion, X is Zn, Cu,
Ni, Mn, Cd, Fe, Ti, WO ₃ , MoO _{3 and} other metal ions, Y is
Fe (II), Fe (III), Co (II) and the like are used, and examples thereof include nickel ferrocyanide and zinc ferrocyanide.

The fluorine-containing polymer is tetrafluoroethylene,
Ethylene trifluoride monochloride, vinyl fluoride, vinylidene fluoride, ethylene trifluoride, perfluoropropylene, perfluorobutadiene, perfluoroalkyl vinyl ether, perfluorodivinyl ether, 2,2-bis (trifluoromethyl)- Polymers or copolymers of fluorine-containing vinyl monomers that do not have ion-exchange properties such as 4,5-difluoro-1,3-dioxole or functional groups that can be easily converted into ion-exchange groups, or copolymers, if necessary. One or more of those obtained by copolymerizing a fluorine vinyl monomer and a non-fluorine-containing vinyl monomer such as ethylene are preferably used.

In order to uniformly disperse the inorganic compound and the fluorine-containing polymer, and to make many inorganic compounds exist in the film to enhance the strength of the film, these are added in the presence of a low molecular compound having a polar group, It is necessary to mix and form a film. The low-molecular compound having a polar group referred to here is an ether group, an ester group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a sulfuric ester group, a thiol group, an amino group, a molecular weight of 100 or more having a polar group such as an ammonium group. It refers to 20000 compounds. Specifically, carboxylic acids and salts thereof having long-chain alkyl groups such as stearylcarboxylic acid and salts thereof, sulfonic acids and salts thereof, phosphoric acid and salts thereof, and aliphatic and aromatic compounds having long-chain alkyl groups such as dodecyl alcohol. Examples thereof include alcohols such as group and alicyclic groups, and phthalic acid esters such as dioctyl phthalate.

As the finely powdered inorganic compound, those having a cation exchange property and those having substantially no cation exchange property can be mixed and used as necessary. For example, it is possible to use a mixture of finely powdered zirconium phosphate and finely powdered titanium oxide, silicon oxide or the like. As for the ratio of the finely divided inorganic compound and the fluorine-containing polymer, when the amount of the inorganic compound is large, the resulting film has a low electric resistance, that is, a film having a high electric conductivity but a mechanically weak film. Further, if the proportion of the fluorine-containing polymer is increased, the film becomes mechanically strong, but the electric resistance becomes high. A film containing 30 parts by weight to 80 parts by weight of an inorganic compound and 70 parts by weight to 20 parts by weight of a fluorine-containing polymer having substantially no ion exchange group can be suitably used in the present invention.

In order to uniformly disperse the inorganic compound in the fluorine-containing polymer, the low-molecular weight compound having a polar group is contained in an amount of 2 to 400 parts by weight per 100 parts of the fluorine-containing polymer to form a film. It is desirable that the low molecular weight compound having the polar group is formed into a film, and then a suitable solvent, for example, a low molecular weight compound having the polar group such as methyl alcohol, ethyl alcohol, acetone or tetrahydrofuran is dissolved. However, it is desirable to extract and remove with a solvent that does not dissolve the fluorine-containing polymer.

The method for forming a film using these finely powdered inorganic compound, fluorine-containing polymer and low molecular weight compound having a polar group is not limited, and any conventionally known method for producing a film-shaped product is not limited. Used without any.

When the above three components are mixed and kneaded, a double roll, a calender roll, a single-screw or twin-screw extruder, a high speed mixer, a kneader, a kneader rudder, etc. used for kneading rubber and resin materials, etc. However, a single-screw or twin-screw extruder or a kneader ruder is preferable because it can be formed into a granular material (pellet) which can be easily used in an extrusion film forming process by using it simultaneously with an apparatus such as a pelletizer.

Further, in the case of a calendar roll, a film-like film can be directly formed, but in this case, anisotropy may occur in the strength of the film along the direction in which the film continuously passes through the roll. Therefore, it is necessary to consider temperature, molding speed, etc.

As one method of controlling the strength anisotropy of the film in the above step, for example, an inflation molding method, which is a method of molding a tubular film in extrusion molding, is used, and the internal pressure is applied to the tube discharged from the mold. It is effective to stretch the film not only in the extrusion direction but also in the direction perpendicular to the extrusion direction by inflating the film. When the film is stretched at the same time, a gap may be formed between the inorganic compound and the fluorine-containing polymer, so it is desirable to heat and press the film again.

Further, when the fluorine-containing polymer is dissolved in a solvent, a low-molecular compound having a polar group is mixed with a viscous solution of the polymer, and a fine powdery inorganic compound is dispersed in the solution to obtain a fluidity. It is desirable to remove the solvent by forming a substance or a plastic mixture into a film. In the case of a liquid, it is possible to use a film that is cast continuously or in a batch on a flat plate and the solvent is scattered to leave the film. For example, a viscous mixture may be applied to a woven fabric, a non-woven fabric, a porous film or other porous substrate having oxidation resistance, and the solvent may be continuously dispersed to form a film.

Further, in any of the film forming methods, in order to obtain the mechanical strength of the film, an oxidation resistant woven fabric, non-woven fabric, porous film, short fiber or the like is used within a range where the electric resistance of the film does not significantly increase. It can exist inside. In addition, the surface of the ion-exchange membrane formed in this manner generally has a larger amount of the fluorine-based polymer in the thickness of micron than the ion-exchanger in many cases. This reduces the electrical conductivity of the membrane. In addition, it is often desirable to remove the surface layer of several microns by polishing both surfaces of the film or performing sandblasting on both surfaces in association with the improvement of the adhesiveness when the electrode catalyst is attached.

Having described the general method of making the membranes of the present invention,
In order to reduce the electrical resistance of the membrane, the membrane of the invention may be heterogeneous with respect to the membrane cross section. That is, like a reverse osmosis membrane, only one surface layer of the membrane may have a dense structure and the inside and the opposite surface may be porous. Particularly desirable structure in this case is a case where both surface layers of the film are dense and the inside is porous.

From the viewpoint of internal resistance of the fuel cell, mechanical strength, diffusion of fuel and gas through the membrane, and handling, the thickness of the membrane is preferably in the range of 10-300 μm, more preferably 20-150 μm. is there.

The method for forming the catalyst layer on the film-like material is not limited, and conventionally known methods can be applied without any limitation. That is, the membrane is immersed in a solution of a soluble platinum group salt, the salt is adsorbed on the membrane surface of the membrane, ion-exchanged, and then immersed in a reducing agent solution such as hydrazine and Na ₂ BO ₄ to form a membrane surface. A method of precipitating a metal, a method of uniformly mixing platinum tetrafluoride and platinum black previously synthesized by the Thomas method, etc., followed by pressure molding into a thin film, and then pressure bonding to both sides of the proton conductive membrane of the present invention, platinum A method of depositing a platinum group metal on a film surface by sputtering with a group metal as a target under high vacuum, and a perfluorocarbon polymer having an ion exchange group, a platinum group catalyst, and a fine powder by the method described in Tokuyo 2000-516014. Applying a composition comprising a catalyst layer adjusted with carbon (carbon black) and other additives onto the surface of the proton conductive film,
There is no particular limitation on the method such as spraying, printing, etc., and the method of making it exist by some other method. For example, when applying, it is desirable to adjust the viscosity of the liquid in the range of 1 to 10 ² poise. This viscosity can be determined by (i) selecting particle size, (ii) utilizing the composition of catalytically active particles and binder, (iii) adjusting the water content, or (iv) preferably It can be adjusted by adding viscosity modifiers such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and cellulose, and polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate and polymethyl vinyl ether. The catalyst layer must be porous. Generally, the average pore diameter is preferably in the range of 0.01 to 50 μm, most preferably 0.1 to 30 μm. Its porosity is generally in the range of 10 to 99%, preferably 10 to 60%. Further, although the amount of the catalyst to be supported varies depending on the method of depositing the catalyst, the catalyst particles are present on the surface of the membrane in an amount of about 0.02 mg / cm ² to about 20 m.
The method is not limited as long as it is deposited in the range of g / cm ² .

DETAILED DESCRIPTION OF THE INVENTION

The proton-conducting membrane of the present invention has a porous catalyst layer attached on both sides, and a porous conductive current collector is arranged in contact with the catalyst layer to provide a catalyst on one side of the membrane. Atmospheric pressure or pressurized hydrogen gas or aqueous methanol solution is placed in the room, and atmospheric pressure or pressurized oxygen or air is placed in the other room, and electric energy generated by the reaction of hydrogen or methanol with oxygen. Take out. In addition, a large number of the above units are arranged in series or in parallel with this as a unit to take out the required electric power.

[0027]

EXAMPLES The contents of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, the electric resistance of the membrane is 1000 cycles of alternating current (Hewlett
It is the value measured at 25.0 ° C. by Packard LCR Meter 4263). The mechanical strength is a value measured at room temperature with a Murren burst tester (Toyo Seiki Seisakusho Co., Ltd.). The ion exchange capacity was measured by equilibrating the membrane to 1.0 N hydrochloric acid and then washing with methyl alcohol.
Wash with the pH indicator methyl orange until it no longer colors,
Then, it was dipped in 0.5N saline and the hydrogen ion ion-exchanged with sodium was titrated with 0.1N caustic soda using methyl orange as an indicator to divide the value by the dry weight of the membrane. The water content of the membrane was determined by washing the membrane used in the above measurement with pure water, wiping both sides of the membrane with filter paper to remove excess water, and then weighing the wet weight of the membrane.
Then, after drying with an air dryer at 100 ° C. for 5 hours, it was weighed. This was taken as the dry weight of the membrane, and the value obtained by dividing the difference between the wet weight and the dry weight by the dry weight was taken as the water content. Regarding the membrane permeability of methanol, the proportion of methanol in the membrane permeate under pressure (10 Mpa) of a solution in which 10% by volume of methanol was dissolved in deionized water was measured by gas chromatography. It is a thing.

[0028]

Example 1 Polyvinylidene fluoride (Kureha Chemical Co., Ltd., KF polymer, # 1300) was dissolved in N-methylpyrrolidone in an amount of 12 wt% to prepare a uniform viscous polymer solution. To 200 parts of this solution, 30 parts of dibutyl phthalate was added and uniformly mixed. Then, 30 parts of hexagonal scaly zirconium phosphate (manufactured by Toagosei) having an average particle size of slightly less than about 1 μm was added and mixed uniformly. The viscous mixture was cast on a horizontal glass plate and heated to disperse the solvent. The remaining film was immersed in methyl alcohol, and dibutyl phthalate in the film was extracted to obtain a proton conductive film. The film obtained has a thickness of 80 μm.
The electric resistance was 0.13 Ωcm ² when equilibrated with 1.0 N hydrochloric acid and the electric resistance was measured. The ion exchange capacity of the membrane was 1.82 meq / g (dry membrane) and the water content was 0.35. The mechanical strength was 0.8 kgf / cm ² . This film is silver
It was installed in a two-chamber electrodialysis tank made of acrylic resin with an effective current-carrying area of 10 cm ² equipped with a silver chloride electrode, 0.50 N saline solution was put into both chambers, and electrodialysis was performed at a current density of 1 A / dm ² for 1 hour. After electrodialysis, when the transport number (current efficiency) was calculated from the concentration changes in the anode chamber and cathode chamber and the energized electricity measured with a digital coulometer (day thickness measurement, digital coulometer, NDCM-4),
It was 95%.

[0029]

Example 2 Daikin PFA (copolymer of ethylene tetrafluoride and perfluoroalkyl vinyl ether, NEOFLON
200 parts of PFA pellets AP-201) and 200 parts of an oligomer of ethylene trifluoride monochloride (Daifloyl # 20, made by Daikin) are mixed, melted and kneaded with a mixer, and then the average particle diameter is about 1 μ
Hexagonal scale-like zirconium phosphate of a little m (manufactured by Toa Gosei)
Was added to 350 parts and kneaded further uniformly, and pelletized with a pelletizer. This is applied to a T-die and extruded to a thickness of 200 μm.
It was molded into a film. Further, this film was applied to a pressure roller to give a film of 50 μm. This membrane was immersed in dichloroethylene to extract and remove the oligomer. Next, hot water (110
After heated swell among ° C.), 1.0 the electric resistance measured by equilibrium N hydrochloric acid was 0.2Ωcm ^2. The ion exchange capacity and mechanical strength of the membrane are 1.54 meq /
Gram (dry film) and 0.6 kgf / cm ² , water content was 0.32
Met. When the transport number of the membrane was determined in the same manner as in Example 1, it was 93%.

[0030]

Example 3 ZrOCl 8H ₂ O was dissolved in 1N hydrochloric acid to prepare a 4N zirconium chloride solution. To this, twice the equivalent of phosphoric acid in PO ₄ / Zr ratio was added to obtain a precipitate of zirconium phosphate.
This was filtered, washed with water, dried, pulverized with a ball mill and classified to obtain a fine powder having a particle size of about 1 μm or less. Table 1 shows this and polyvinylidene fluoride (Kureha Chemical, KF Polymer, # 1300).
Was dispersed and dissolved in N-methylpyrrolidone. To this, 30 parts of cyclohexanone was added to polyvinylidene fluoride and uniformly stirred with a homogenizer to obtain an extremely viscous mixture. This was cast on a horizontal plate and heated to disperse the solvent. The obtained membrane was immersed in ethyl alcohol to remove extractable components, and then equilibrated in 1N hydrochloric acid to obtain a proton conductive membrane.

[Table 1] 1) By weight. 2) Polyvinylidene fluoride 3) Zirconium phosphate with an average particle size of about 1 μm 4) It shows a specific resistance. (Ωcm) 5) kgf / cm ² 6) Milli-equivalent / gram (dry membrane) 7) Proportion of methanol (volume%) in the membrane permeate under pressure.

[0031]

Example 4 40 parts of polyvinylidene fluoride (Kureha Chemical Co., KF polymer, # 1300) was dissolved in 300 parts of N-methylpyrrolidone. To this polyvinylidene fluoride, 60 parts of titanium phosphate (made by Toa Gosei) having an average particle diameter of about 4 μm is used.
Part of the mixture was added and uniformly mixed and dispersed. Then, dibutyl phthalate was added to this at a ratio of Table 2 to polyvinylidene fluoride and uniformly stirred with a homogenizer to obtain an extremely viscous slurry mixture. This was cast on a horizontal flat plate and heated to 100 ° C. to scatter the solvent. The obtained membrane was immersed in ethyl alcohol to remove extracted components, and then equilibrated in 1.0N hydrochloric acid to give a proton conductive membrane. The electric resistance in the table is a value measured at 25.0 ° C. after equilibrating with 1.0 N hydrochloric acid.

[Table 2] 1) By weight. 2) Polyvinylidene fluoride 3) Titanium phosphate with an average particle size of less than 4 μm 4) Dibutyl phthalate 5) Specific resistance (Ωcm) 6) kgf / cm ² 7) Meq / g (dry film)

[0032]

[Example 5] 30 parts of anatase-type titanium oxide (ST-01 manufactured by Ishihara Sangyo Co., Ltd.) having a particle size of 7 nm was mixed with 12% N- of vinylidene fluoride.
Disperse in 400 parts of methylpyrrolidone solution, add 30 parts of dioctyl phthalate to this, stir and mix well, cast on a flat plate that has been leveled, heat and dry to 80 ° C, and thickness
A 60 μm film was obtained. This was immersed in acetone to remove dioctyl phthalate to obtain a proton conductive film. When this was equilibrated with a 1.0 N aqueous hydrochloric acid solution and the electrical resistance was measured, it was 0.2 Ωcm ² . The water content of the membrane is 0.30
Met.

[0033]

Example 6 Titanium oxides having different particle sizes were synthesized. The grain size was controlled by controlling the aging time during crystal growth. Polyvinylidene fluoride solution that is a 10% solution of dimethylformamide in 60 parts of titanium oxide
Mix 700 parts uniformly and add 50 parts of dioctyl phthalate
Parts were added to make a viscous, uniform slurry. These were poured onto a horizontal flat plate and heated to disperse the solvent to obtain a film having a thickness of 100 μm. Then, this was immersed in ethyl alcohol to obtain a proton conductive film. The electrical resistance, mechanical strength, and water permeation amount under pressure of this were measured.

[Table 3] 1) Ω cm ² 2) kgf / cm ² 3) cm ³ / sec. Cm ^2. Mpa × 10 ⁵ 4) (dry film weight-wet film weight) / dry film weight)

[0034]

Example 7 Zirconium phosphate having an average particle size of 1 μm and silicon oxide having a particle size of 5 nm (Leorosyl, MT-10, manufactured by Tokuyama Corp.)
Was mixed in a ratio of 3: 2, and to 300 parts of this, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether 240
300 parts of a perfluoropropylene oligomer was added thereto, and the mixture was heated and mixed at 400 ° C. to be melted into pellets. This was extruded by an inflation molding machine to form a film having a thickness of 150 μm. The film was further biaxially stretched and further heated and rolled to obtain a film having a thickness of 30 μm. The membrane is thoroughly extracted with 1,1,3 trichlorotrifluoroethylene to remove the perfluoropropylene oligomers,
The proton-conducting film of the present invention is used. When the electric resistance was measured under the same conditions as above, it was 0.25 Ωcm ² and the water content was 0.45. The cation transport number was 94%.

[0035]

Example 8 Titanium phosphate (produced by Toagosei) having an average particle diameter of about 4 μm and anatase type titanium oxide having a particle diameter of 7 nm are 4: 2.
And 400 parts of a copolymer of ethylene tetrafluoride and perfluoroalkyl vinyl ether is mixed with 300 parts of this, and the perfluoropropylene oligomer 300
Parts were added, and the mixture was heated and mixed at 400 ° C. to obtain pellets. This is T
It was extruded with a die to form a film having a thickness of 150 μm. The film was further biaxially stretched and further heated and rolled to obtain a film having a thickness of 30 μm. The membrane was sufficiently extracted with 1,1,3 trichlorotrifluoroethylene to obtain the membrane of the present invention. The electric resistance was measured under the same conditions as above, and it was 0.20 Ωcm ^2.
The water content was 0.32. Example 1 for the transport number of cations
It was 95% when measured in the same manner as.

[0036]

According to the present invention, hydrogen-oxygen, methanol-
The operating temperature of the oxygen fuel cell can be improved, and stable operation can be achieved.

[Brief description of drawings]

FIG. 1 shows an example of a membrane electrode integrated product having an electrode formed on the surface of the membrane of the present invention and use as an electrolyte of a fuel cell. In particular, the integrated membrane electrode having an electrode formed on the membrane surface of the present invention can be used without any limitation in an electrochemical device in which protons permeate the membrane. In the fuel cell, the fuel source indicated by arrow 6,
For example, hydrogen gas supplied from the anode chamber, methanol (typically methanol / aqueous solution) and the oxidant indicated by the arrow 7 are used, for example, air or oxygen supplied to the cathode chamber. The membrane 1 acts as an electrolyte (proton conductor) and separates the anode chamber from the cathode chamber. A porous anode current collector 4 and a porous cathode current collector 5 are provided for the purpose of extracting the current generated from this battery. The catalyst layer 3 functioning as the cathode is brought into contact with the cathode-side surface of the catalyst layer-carrying membrane 1 facing the cathode. The catalyst layer 2 functioning as an anode is brought into contact with the anode-facing surface of the membrane 1 and the anode current collector 4. Cathode current collector 5 is electrically connected to positive terminal 8 and anode current collector 4 is electrically connected to negative terminal 9.

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) C08K 7/00 C08K 7/00 C08L 27/12 C08L 27/12 H01M 8/10 H01M 8/10 F term (reference) 4F071 AA24 AA26 AA27X AA30X AB18 AB25 AC10 AH15 BB02 BB06 BC01 BC12 4J002 BD141 BD151 BE041 DE138 DH046 EH147 GQ00 5H026 AA06 CX05 EE11 EE19 HH03 HH05

Claims (8)

[Claims] 1. 30 to 80 parts by weight of a finely powdered inorganic compound and 7 parts by weight of a fluorine-containing polymer having substantially no ion exchange group.
A membrane for a fuel cell, which has a dense structure made of a composition containing 0 to 20 parts by weight. 2. The finely divided inorganic compound has a unidirectional size of 15
The membrane for a fuel cell according to claim 1, which is fine particles having a particle diameter of not more than μm. 3. The membrane for a fuel cell according to claim 1, wherein the inorganic compound is fine particles having a cation exchange property. 4. The membrane for a fuel cell according to claim 1, wherein the inorganic compound is titanium oxide. 5. The composition according to claim 1, 2, 3 or 4, wherein 2 to 400 parts by weight of a low molecular weight compound having a polar group is contained in 100 parts by weight of a fluorine-containing polymer to form a film. Membrane for fuel cells. 6. The thickness of the membranous material is 10-300 μm.
4. The membrane for a fuel cell according to any one of 4 above. 7. The membrane for a fuel cell according to claim 1, wherein a catalyst layer containing a platinum group element as a main component is provided on both sides of the membrane material. 8. A fuel cell using the diaphragm for a fuel cell according to claim 1.