JP4815759B2 - Polymer electrolyte composite membrane, production method thereof and use thereof - Google Patents

Description

  The present invention relates to a polymer electrolyte composite membrane having a polymer electrolyte composite layer in which a porous base material having micropores is filled with a polymer electrolyte composed of a hydrophobic portion and a hydrophilic portion, a method for producing the same, and a use thereof.

In recent years, fuel cells (solid polymer electrolyte fuel cells) using proton conductive polymer membranes as electrolytes have been actively studied. Solid polymer electrolyte fuel cells have the characteristics that they operate at a low temperature, have a high output per unit area and can be miniaturized, and are considered to be promising for applications such as in-vehicle power supplies. Various molecular electrolyte membranes have been proposed.
For example, a polymer electrolyte composite membrane in which a porous base material is filled with a polymer electrolyte has been proposed (Patent Document 1).

JP-A-6-29032

However, although the above-described composite membrane has improved mechanical strength as compared with a single membrane of a polymer electrolyte, there is a problem in that satisfactory ion generation performance cannot be obtained due to insufficient ionic conductivity.
Accordingly, an object of the present invention is to provide a polymer electrolyte composite membrane exhibiting high power generation performance, a method for producing the same, and a use thereof.

  As a result of intensive studies on polymer electrolytes in order to find a polymer electrolyte composite membrane exhibiting high power generation performance, the present inventors have formed a phase separation structure of a hydrophobic part and a hydrophilic part in a solid state as a polymer electrolyte. And using a specific polymer electrolyte in which the sum of the size of the hydrophobic domain and the size of the hydrophilic domain in the phase separation structure is equal to or less than the average pore diameter of the micropores of the porous substrate. The molecular electrolyte composite membrane was found to exhibit high power generation performance, and various studies were further made to complete the present invention.

That is, the present invention provides a polymer electrolyte composite membrane having a polymer electrolyte composite layer in which a porous base material having micropores is filled with a polymer electrolyte composed of a hydrophobic portion and a hydrophilic portion, In the solid state, a phase separation structure of a hydrophobic part and a hydrophilic part is formed, and the following formula (1)
a + b ≦ d (1)
(Wherein, a is the size of the hydrophobic domain in the phase separation structure (nm), b is the size of the hydrophilic domain (nm), and d is the average pore diameter (nm) of the micropores of the porous substrate.
). )
A molecular electrolyte composite membrane characterized by satisfying the above requirements is provided.

  The present invention also provides a method for producing a polymer electrolyte composite membrane having a polymer electrolyte composite layer in which a porous base material having micropores is filled with a polymer electrolyte composed of a hydrophobic portion and a hydrophilic portion. The present invention provides a method for producing a polymer electrolyte composite membrane characterized by using a polymer electrolyte that forms a phase-separated structure of a hydrophobic part and a hydrophilic part in a solid state and satisfies the formula (1). .

  Furthermore, the present invention provides a fuel cell using the above polymer electrolyte composite membrane.

According to the present invention, the polymer electrolyte forms a phase separation structure of a hydrophobic part and a hydrophilic part in a solid state, and the sum of the size of the hydrophobic domain and the hydrophilic domain in the phase separation structure is porous. By using a specific polymer electrolyte that is equal to or smaller than the average pore diameter of the fine pores of the porous substrate, a polymer electrolyte composite membrane exhibiting high power generation performance can be provided.
In addition, since the polymer electrolyte composite membrane of the present invention exhibits high power generation performance, it is advantageous not only as a fuel cell using hydrogen as a fuel but also as an electrolyte membrane in, for example, a direct methanol fuel cell using alcohol such as methanol. is there.

Hereinafter, the present invention will be described in detail.
In the polymer electrolyte composite membrane of the present invention, the polymer electrolyte in the polymer electrolyte composite layer forms a phase separation structure of a hydrophobic part and a hydrophilic part in a solid state, and the size of the hydrophobic domain in the phase separation structure a (Nm), the size b (nm) of the hydrophilic domain, and the average pore diameter d (nm) of the micropores of the porous substrate satisfy the above formula (1).

Here, the size a (nm) of the hydrophobic domain and the size b (nm) of the hydrophilic domain can be measured by, for example, a transmission electron microscope or small-angle X-ray diffraction. Among these, the former is preferably used, and in this case, specifically, an ultrathin section cut out in the thickness direction of the membrane composed only of a polymer electrolyte is dyed into a hydrophobic domain and a hydrophilic domain by a conventional method by a staining method, Measure the diameter of the largest circle contained in each domain at 10 or more locations and calculate the average value of each. In this manner, the size, that is, the size a (nm) of the hydrophobic domain and the size b (nm) of the hydrophilic domain can be measured.
Further, a + b, which is the sum of the size of the hydrophobic domain and the size of the hydrophilic domain, may be calculated by substituting the value obtained as described above. When the phase separation structure is formed, the diameter of the maximum circle included in both the dyed hydrophobic domain and the hydrophilic domain may be measured at 10 or more locations, and the average value may be substituted. Although the former method and the latter method may show different values, in the present invention, the value obtained by at least one of the methods should satisfy the formula (1).
In addition, it is preferable to use what was manufactured with the same solvent and the same drying conditions as the film | membrane made from a polymer electrolyte only at the time of composite film manufacture.
A + b, which is the sum of the size of the hydrophobic domain and the size of the hydrophilic domain, is usually about 1 to 200 nm. Preferably it is about 3-100 nm, More preferably, it is about 10-80 nm.

As the hydrophilic portion of the polymer electrolyte also include segment ion exchange groups in the polymer was introduced, the ion-exchange groups, for example, _{-SO 3 H, -COOH, -PO (} OH) 2, -POH ( _{OH), - SO 2 NHSO 2} -, - Ph (OH) (Ph is and cation exchange groups such as a phenyl _{group), -NH 2, -NHR, -NRR} ', - NRR'R''+, Anion exchange groups such as —NH ₃ ⁺ (R: represents an alkyl group, a cycloalkyl group, an aryl group, etc.) can be mentioned. A part or all of these groups may form a salt with a counter ion.
Examples of the hydrophobic part in the polymer electrolyte include a segment in which an ion exchange group as described above in the polymer is not introduced.

When two types of segments as described above coexist in the polymer electrolyte, whether they are combined or mixed, these are caused by the interaction between chemically different segments, Usually, the phase is separated into a hydrophobic domain, which is a region consisting of each segment, ie, a region consisting of a hydrophobic portion, and a hydrophilic domain, which is a region consisting of a hydrophilic portion, in a nanometer size.
In the present invention, these domains each preferably have a continuous phase separation structure, and more preferably have a phase separation structure continuous in parallel with the film thickness direction.

As a typical example of a polymer electrolyte that forms such a phase separation structure, for example, (A) a polymer having a main chain made of an aliphatic hydrocarbon and having a sulfonic acid group and / or a phosphonic acid group introduced therein is used. (B) a polymer composed of an aliphatic hydrocarbon in which some or all of the hydrogen atoms in the main chain are substituted with fluorine, and a polymer in which a sulfonic acid group and / or a phosphonic acid group are introduced (C) a polymer electrolyte in which the main chain has an aromatic ring and a sulfonic acid group and / or phosphonic acid group is introduced; (D) the main chain does not substantially contain a carbon atom. A polymer electrolyte such as polysiloxane and polyphosphazene, into which a sulfonic acid group and / or phosphonic acid group is introduced; (E) the sulfonic acid group and / or phosphonic acid of (A) to (D); Basic A copolymer comprising any two or more repeating units selected from repeating units constituting the preceding polymer, and having a sulfonic acid group and / or phosphonic acid group introduced therein; (F) Examples thereof include a polymer electrolyte having a nitrogen atom in the main chain or side chain and an acidic compound such as sulfuric acid or phosphoric acid introduced by ionic bonding.
Examples of the polymer electrolyte (A) include polyvinyl sulfonic acid, polystyrene sulfonic acid, poly (α-methylstyrene) sulfonic acid, and the like.

  In addition, as the polymer electrolyte of the above (B), a polymer having a perfluoroalkylsulfonic acid in a side chain represented by Nafion (registered trademark of DuPont, the same applies hereinafter) and a main chain being a perfluoroalkane, A sulfonic acid type polystyrene-graft-ethylene-tetrafluoroethylene copolymer composed of a main chain made by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer and a hydrocarbon side chain having a sulfonic acid group Α, β, β-trifluorostyrene is graft-polymerized on a film made by copolymerization (ETFE, for example, JP-A-9-102322) or copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, A sulfonic acid type poly (trifluorostyrene) -graph obtained by introducing a sulfonic acid group into a solid polymer electrolyte membrane -ETFE film (e.g., U.S. Patent No. 4,012,303 and U.S. Pat. No. 4,605,685), and the like.

  The polymer electrolyte (C) may be one in which the main chain is interrupted by a hetero atom such as an oxygen atom. For example, polyether ether ketone, polysulfone, polyether sulfone, poly (arylene ether) , Polyimide, poly ((4-phenoxybenzoyl) -1,4-phenylene), polyphenylene sulfide, polyphenylquinoxalen, and other homopolymers each having a sulfonic acid group introduced therein, sulfoarylated polybenzimidazole , Sulfoalkylated polybenzimidazole, phosphoalkylated polybenzimidazole (for example, JP-A-9-110882), phosphonated poly (phenylene ether) (for example, J. Appl. Polym. Sci., 18, 1969 (1974)) Etc.

Examples of the polymer electrolyte (D) include polysiloxanes having phosphonic acid groups described in Polymer Prep., 41, No. 1, 70 (2000), in which sulfonic acid groups are introduced into polyphosphazene. Etc.
As the polymer electrolyte of (E), a sulfonic acid group and / or a phosphonic acid group are introduced into a random copolymer, but a sulfonic acid group and / or a phosphonic acid group are introduced into an alternating copolymer. The sulfonic acid group and / or the phosphonic acid group may be introduced into the block copolymer. Examples of the sulfonic acid group introduced into the random copolymer include a sulfonated polyethersulfone-dihydroxybiphenyl copolymer (for example, JP-A-11-116679).

Examples of the polymer electrolyte (F) include polybenzimidazole containing phosphoric acid described in JP-T-11-503262.
In the block copolymer contained in the polymer electrolyte of the above (E), specific examples of the block having a sulfonic acid group and / or a phosphonic acid group include, for example, a sulfonic acid group described in JP-A-2001-250567 and And / or a block having a phosphonic acid group.
The polyelectrolyte in the present invention is preferably a block copolymer or a graft copolymer, and in particular, a polymer having an aromatic ring in the main chain as in the above (C) is preferable, and in particular, a sulfonic acid group and / or Alternatively, a polymer having a phosphonic acid group introduced is preferably used.
The weight average molecular weight of the polymer electrolyte used in the present invention is usually about 1,000 to 1,000,000, and the ion exchange group equivalent weight is usually about 500 to 5,000 g / mol.
Further, additives such as plasticizers, stabilizers, mold release agents and the like used for ordinary polymers can be contained within a range not contrary to the object of the present invention. For example, a polymer containing a phosphonic acid group (Japanese Patent Laid-Open No. 2003-282096) or the like is compatible with a polymer electrolyte and hardly eluted, and thus can be preferably used as a stabilizer.

In the present invention, the polymer electrolyte as described above is used. In combination with the porous base material, the above formula (which is a relational expression with the average pore diameter d (nm) of the micropores ( Those satisfying 1) are selected.
Here, as the average pore diameter d (nm) of the fine pores of the porous substrate, a value obtained by the bubble point method (ASTM F316-86) is preferably used.
The average pore diameter d is usually about 1 to 1,000,000 nm, preferably about 30 to 10,000 nm, more preferably about 50 to 1,000 nm.

The porous substrate having micropores used in the present invention is a substrate for filling the polymer electrolyte, and for further improving the strength, flexibility, and durability of the polymer electrolyte membrane. used. Therefore, any porous material that satisfies the above purpose of use may be used, and examples thereof include porous membranes, woven fabrics, non-woven fabrics, and fibrils, and they can be used regardless of their shapes and materials.
From the viewpoint of heat resistance and the effect of reinforcing physical strength, aliphatic, aromatic, or fluorine-containing polymers are preferred.

  Examples of the aliphatic polymer include, but are not limited to, polyethylene, polypropylene, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer. In addition, polyethylene here is a general term for ethylene-based polymers having a polyethylene crystal structure, and includes, for example, a copolymer of ethylene and other monomers. Specifically, linear low-density polyethylene (LLDPE) And copolymers of ethylene and α-olefin, ultrahigh molecular weight polyethylene, and the like. Polypropylene here is a general term for propylene-based polymers having a polypropylene crystal structure, such as commonly used propylene-based block copolymers and random copolymers (these are copolymers with ethylene, 1-butene, etc.). Is a polymer)

Examples of the aromatic polymer include polyester, polyethylene terephthalate, polycarbonate, polyimide, polysulfone, and the like.
Examples of the fluorine-containing polymer include thermoplastic resins having at least one carbon-fluorine bond in the molecule. Usually, those having a structure in which all or most of the hydrogen atoms of the aliphatic polymer are substituted with fluorine atoms are preferably used.
Specific examples thereof include polytrifluoroethylene, polytetrafluoroethylene, polychlorotrifluoroethylene, poly (tetrafluoroethylene-hexafluoropropylene), poly (tetrafluoroethylene-perfluoroalkyl ether), and polyvinylidene fluoride. Although it is mentioned, it is not limited to these. Of these, polytetrafluoroethylene and poly (tetrafluoroethylene-hexafluoropropylene) are preferable, and polytetrafluoroethylene is particularly preferable. In addition, these fluororesins preferably have an average molecular weight of 100,000 or more because of good mechanical strength.

When such a porous substrate is used as a diaphragm of a solid polymer electrolyte fuel cell, the film thickness is usually 1 to 100 μm, preferably 3 to 30 μm, more preferably 5 to 20 μm, and the porosity is usually 20 -98%, preferably 40-95%.
If the thickness of the porous substrate is too thin, the effect of reinforcing the strength after compounding or the reinforcing effect of imparting flexibility and durability is insufficient, and gas leakage (cross leak) is likely to occur. On the other hand, if the film thickness is too thick, the electric resistance becomes high, and the obtained composite film becomes insufficient as a diaphragm of the polymer electrolyte fuel cell. If the porosity is too small, the resistance as a solid electrolyte membrane is increased. If it is too large, the strength of the porous substrate itself is generally weakened and the reinforcing effect is reduced.

Next, a method for producing a polymer electrolyte composite membrane will be described.
The production method of the present invention is greatly characterized in that a polymer electrolyte satisfying the above formula (1) and a porous substrate are used, and the method of combining the polymer electrolyte and the porous substrate is particularly limited. There is no.
As a composite method, for example, a polymer electrolyte is made into a solution, a porous membrane is impregnated in this solution, and after removing the porous membrane, a solvent is dried to obtain a composite membrane, or this solution is applied to the porous membrane. , A method of drying the solvent to obtain a composite membrane, contacting the porous membrane with this solution under reduced pressure, then impregnating the solution into the pores of the porous membrane by returning to normal pressure, and drying the solvent to form the composite membrane The method of obtaining etc. are mentioned.

  Here, the solvent for producing the polyelectrolyte solution is not particularly limited as long as it can dissolve the polyelectrolyte and can be removed thereafter. For example, N, N-dimethylformamide (DMF), Aprotic polar solvents such as N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, etc. Chlorinated solvents, alcohols such as methanol, ethanol and propanol, alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether Such as is preferably used. These can be used singly, but two or more solvents can be mixed and used as necessary. Among them, dimethylacetamide, dichloromethane / methanol mixed solvent, dimethylformamide, and dimethylsulfoxide are preferable because of high solubility.

  Further, the polymer electrolyte composite membrane of the present invention may have a multilayer structure, for example, (composite layer / electrolyte layer), (electrolyte layer / composite layer / electrolyte layer), and these layer configurations superimposed (electrolyte) Layer / composite layer / electrolyte layer / composite layer / electrolyte layer) is also a suitable embodiment.

Next, a fuel cell using the polymer electrolyte composite membrane of the present invention will be described.
A fuel cell is composed of an anode and a cathode of a gas diffusion electrode disposed in opposition to each other, and a membrane electrode assembly comprising a polymer electrolyte membrane that is interposed between and in contact with both electrodes, and selectively allows ions to pass through. A plurality of unit cells to be configured are alternately stacked via a separator provided with a gas flow means. In this fuel cell, a fuel such as hydrogen, reformed gas or methanol is supplied to the anode, and an electrochemical reaction that occurs when an oxidant such as oxygen is supplied to the cathode, that is, the fuel is oxidized electrocatalytically. At the same time, the oxidizing agent is electrocatalytically reduced, and chemical reaction energy is directly converted into electric energy to generate electricity.

Here, the catalyst is not particularly limited as long as it can activate the oxidation-reduction reaction with hydrogen or oxygen, and a known catalyst can be used, but platinum fine particles are preferably used. The platinum fine particles are often preferably those supported on particulate or fibrous carbon such as activated carbon or graphite.
A known material can also be used for the conductive material as the current collector, but porous carbon woven fabric or carbon paper is preferable in order to efficiently transport the raw material gas to the catalyst.
For a method of bonding platinum fine particles or carbon carrying platinum fine particles to a porous carbon woven fabric or carbon paper, and a method of bonding it to a polymer electrolyte sheet, see, for example, J. Org. Electrochem. Soc. : Known methods such as those described in Electrochemical Science and Technology, 1988, 135 (9), 2209 can be used.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Porous substrate>
The following polyethylene porous membrane produced according to JP-A-2002-309024 was used. The average pore diameter is a value determined by the bubble point method ASTM F316-86.
Polyethylene porous membrane A: average pore diameter d = 60 nm
Polyethylene porous membrane B: average pore diameter d = 40 nm

<Evaluation of polymer electrolyte composite membrane>
A platinum catalyst supported on fibrous carbon and a porous carbon woven fabric as a current collector were joined to both surfaces of the polymer electrolyte composite membrane. Power generation characteristics were measured by flowing humidified oxygen gas on one surface of the unit and humidified hydrogen gas on the other surface.

Reference Example 1 (Polymer electrolyte production example)
167.59 g (900 mmol) of 4,4′dihydroxybiphenyl (DOD) and 600 g of benzophenone were dissolved with heating and stirring, and then 132.68 g (960 mmol) of potassium carbonate and 180 ml of toluene were added and heated to azeotropic dehydration, followed by 180 ° C. Then, m-dibromobenzene (20.52 g, 850 mmol) was added, followed by addition of copper (I) bromide (0.43 g, 3 mmol), and the mixture was stirred at 200 ° C. for 6 hours. The reaction solution was cooled and poured into a solution in which the weight ratio of hydrochloric acid / methanol / acetone was (2/70/30), and the precipitated polymer was filtered, washed with water, washed with methanol, and dried under reduced pressure to produce polymer a1. .
Subsequently, 144 g of SUMIKAEXCEL PES5003P (manufactured by Sumitomo Chemical Co., Ltd., hydroxyl-terminated polyethersulfone) and 48 g of the above polymer a1 were dissolved in DMAc, followed by the addition of 4.84 g of potassium carbonate and 9.52 g of decafluorobiphenyl at 80 ° C. for 4 hours. Stir. Cooled and poured the reaction mixture into dilute hydrochloric acid to precipitate the polymer. The block copolymer a2 was obtained by washing with water and methanol. Next, this a2 was sulfonated with concentrated sulfuric acid to obtain the following sulfonated block copolymer A.

このスルホン化ブロック共重合体Ａのイオン交換容量は１．４ｍｅｑ／ｇであった。
このものは、1H-NMR測定により、ａ１由来部のみがスルホン化され親水部となり、ＰＥＳ５００３Ｐ由来部は疎水部となっていることが確認された。

The ion exchange capacity of this sulfonated block copolymer A was 1.4 meq / g.
It was confirmed by 1H-NMR measurement that only the a1-derived part was sulfonated to become a hydrophilic part, and the PES5003P-derived part was a hydrophobic part.

  Using this sulfonated block copolymer A, a polymer electrolyte solution dissolved in DMAc at a concentration of 25 wt% was prepared, cast on a glass plate, and dried at 80 ° C. under normal pressure. As a result of measuring the obtained polymer electrolyte membrane (1) with a transmission electron microscope, the sum a + b of the sizes of the hydrophobic domain and the hydrophilic domain was 50 nm.

Reference Example 2 (Polymer electrolyte production example)
(Synthesis of polyethersulfone (b1))
Under a nitrogen atmosphere, 1500 g of hydroxyl group-terminated polyethersulfone (Sumitomo Chemical PES4003P manufactured by Sumitomo Chemical Co., Ltd.) was dissolved in 4000 ml of DMAc. Further, 13 g of potassium carbonate and 600 ml of toluene were added and heated and stirred. After dehydration under the azeotropic conditions of toluene and water, toluene was distilled off. After allowing to cool to room temperature, 123.2 g of decafluorobiphenyl was added and the reaction was carried out while gradually heating to 100 ° C. Then, the reaction liquid was thrown into methanol, the polymer was deposited, it filtered and dried, and polyether sulfones (b1) were obtained. This polyethersulfone (b1) is a polyethersulfone having a terminal substituted with a nonafluorobiphenyloxy group.

(Synthesis of block copolymer B)
Under a nitrogen atmosphere, 96.8 g (0.424 mol) of potassium hydroquinonesulfonate, 202.9 g (0.414 mol) of potassium 4,4′-difluorophenylsulfone-3,3′-disulfonate and 61.6 g (0.445 of potassium carbonate) mol) was dissolved in 2600 ml DMSO. Thereafter, 500 ml of toluene was added, heated and stirred, dehydrated under the azeotropic conditions of toluene and water, and toluene was distilled off. The mixture was heated and stirred at 170 ° C. for 7 hours and then allowed to cool to room temperature to obtain polymer (b2). To this was added 350 g of the polyethersulfone (b1), and the reaction was conducted while gradually heating to 140 ° C. Thereafter, the reaction solution was poured into methanol to precipitate a polymer, filtered, washed twice with about 5 times the amount of hot water at 95 ° C., and then dried to obtain the following sulfonated block copolymer B. .

The polystyrene-equivalent molecular weight of the sulfonated block copolymer B by GPC was Mn = 72000, Mw = 390000, and the ion exchange capacity was 1.43 meq / g. According to 1H-NMR measurement, this is a block copolymer in which the sulfonated polymer (b2) -derived part is a hydrophilic part and the polyethersulfone (b1) -derived part is a hydrophobic part. confirmed.
Using this sulfonated block copolymer B, a polymer electrolyte solution dissolved in NMP at a concentration of 25.5 wt% was prepared, cast on a glass plate, and dried at 80 ° C. under normal pressure. As a result of measuring the obtained polymer electrolyte membrane (2) with a transmission electron microscope, the sum a + b of the hydrophobic domain and the hydrophilic domain was 19 nm.

次いで、特開２００３−２８２０９６に記載の方法に準拠しこの共重合体をブロモ化、ホスホン酸エステル化、加水分解することにより、４，４’−ビフェノール由来のユニット１つに対してＢｒが約0.1個、ホスホン酸基が約1.7個置換された下記ホスホン酸基含有ポリマーを得た。

Reference Example 3 (Production example of polymer electrolyte)
Using a 90:10 weight ratio mixture of the sulfonated block copolymer B obtained in Reference Example 2 and the phosphonic acid group-containing polymer synthesized below, a polymer electrolyte solution dissolved in NMP at a concentration of 27 wt% was prepared. After being cast on a glass plate, it was dried at 80 ° C. under normal pressure. As a result of measuring the obtained polymer electrolyte membrane (3) with a transmission electron microscope, the sum a + b of the hydrophobic domain and the hydrophilic domain was 19 nm.
(Synthesis of stabilizing additive phosphonic acid group-containing polymer)
In accordance with the method described in JP-A-10-021943, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxybiphenyl and 4,4′-dichlorodiphenylsulfone are used in the presence of diphenylsulfone and potassium carbonate as a solvent. The following random copolymer was prepared by reacting at a molar ratio of 7: 3: 10.

Next, this copolymer is brominated, phosphonated, and hydrolyzed according to the method described in JP-A-2003-282096, whereby Br is reduced to about 4,4′-biphenol-derived unit. The following phosphonic acid group-containing polymer substituted with 0.1 and about 1.7 phosphonic acid groups was obtained.

Examples 1-3
A polyethylene porous membrane A was fixed on a glass plate, and a polymer electrolyte solution prepared in the same manner as in Reference Examples 1 to 3 was dropped onto the porous membrane. The polymer electrolyte solution was uniformly spread on the porous membrane using a wire coater, the coating thickness was controlled using a bar coater having a clearance of 0.3 mm, and the coating was dried at 80 ° C. under normal pressure. Thereafter, it was immersed in 1 mol / L hydrochloric acid and further washed with ion exchange water to obtain a polymer electrolyte composite membrane.
About this thing, the fuel cell characteristic evaluation was performed and the result was shown in Table 1.

Comparative Example 1
A polymer electrolyte composite membrane was obtained by carrying out according to Example 1 except that the polyethylene porous membrane B was used. About this thing, the fuel cell characteristic evaluation was performed and the result was shown in Table 1.

[Table 1]
Voltage E (V) 0.8 0.6 0.4 0.2
Current value I (A / cm ² )
Example 1 0.08 0.40 0.98 1.28
Example 2 0.20 0.89 1.40 1.70
Example 3 0.17 0.17 1.10 1.40
Comparative Example 1 0.06 0.10 0.21 0.35

Claims (3)

A porous substrate having fine pores, Ri Do from a hydrophobic portion and a hydrophilic portion, the main chain has an aromatic ring, polyelectrolyte complexes polyelectrolyte is filled with a sulfonic acid group and / or phosphonic acid groups A polymer electrolyte composite membrane having a layer, wherein the polymer electrolyte forms a phase separation structure of a hydrophobic part and a hydrophilic part in a solid state, and the following formula (1)
a + b ≦ d (1)
(Wherein, a is the size of the hydrophobic domain in the phase separation structure (nm), b is the size of the hydrophilic domain (nm), and d is the average pore diameter (nm) of the micropores of the porous substrate.
). )
A polymer electrolyte composite membrane characterized by satisfying: A porous substrate having fine pores, Ri Do from a hydrophobic portion and a hydrophilic portion, the main chain has an aromatic ring, polyelectrolyte complexes polyelectrolyte is filled with a sulfonic acid group and / or phosphonic acid groups In producing a polymer electrolyte composite membrane having a layer, a phase separation structure of a hydrophobic part and a hydrophilic part is formed as a polymer electrolyte in a solid state, and the following formula (1)
a + b ≦ d (1)
(Wherein, a is the size of the hydrophobic domain in the phase separation structure (nm), b is the size of the hydrophilic domain (nm), and d is the average pore diameter (nm) of the micropores of the porous substrate.
). )
The manufacturing method of the polymer electrolyte composite film characterized by using the polymer electrolyte which satisfy | fills.   A fuel cell comprising the polymer electrolyte composite membrane according to claim 1.