JPWO2010067743A1 - Electrolyte laminated film, membrane-electrode assembly, and fuel cell - Google Patents

Abstract

The present invention has high dimensional stability and high proton conductivity (low resistance) under low humidity, and when used in a polymer electrolyte fuel cell using hydrogen as a fuel, high output characteristics are obtained even under low humidity. In addition, there are provided an electrolyte membrane having durability and good bonding properties with an electrode, and a membrane-electrode assembly and a polymer electrolyte fuel cell using the electrolyte membrane. A plurality of polymer electrolyte membranes are laminated, at least one of the electrolyte membranes has an ion exchange capacity higher than 1.60 meq / g, and at least one of 0.70 to 1.60 meq / g. Contains a block copolymer (I) having an ion exchange capacity, and at least one of the constituent electrolyte membranes comprising a polymer block (A) having an ion conductive group and a flexible polymer block (B) as constituent components Provided are an electrolyte laminated film, a membrane-electrode assembly and a polymer electrolyte fuel cell using the electrolyte membrane. [Selection figure] None

Description

  The present invention relates to an electrolyte laminate film, a membrane-electrode assembly comprising the electrolyte laminate film, and a polymer electrolyte fuel cell.

  In recent years, fuel cell technology has been counted as one of the pillars of these new energy technologies as a fundamental solution to energy and environmental problems, and as a central energy conversion system in the future hydrogen energy era. In particular, polymer electrolyte fuel cells (PEFCs) are used for stationary power sources for electric vehicles, portable power devices, and households that use electricity and heat simultaneously from the viewpoint of miniaturization and weight reduction. Application to other power supply devices is under consideration. In addition, those using hydrogen as a fuel are expected to be used in a wide range of applications from the viewpoint of output and economy.

  A polymer electrolyte fuel cell is generally configured as follows. First, a catalyst layer containing carbon powder carrying a white metal catalyst and an ion conductive binder made of a polymer electrolyte is formed on both sides of a polymer electrolyte membrane having proton conductivity. A gas diffusion layer, which is a porous material through which fuel gas and oxidant gas are passed, is formed outside each catalyst layer. Carbon paper, carbon cloth, or the like is used as the gas diffusion layer. A structure in which the catalyst layer and the gas diffusion layer are integrated is called a gas diffusion electrode, and a structure in which a pair of gas diffusion electrodes is bonded to the electrolyte membrane so that the catalyst layer faces the electrolyte membrane is a membrane-electrode assembly ( MEA (Mebrane Electrode Assembly). On both sides of this membrane-electrode assembly, separators having electrical conductivity and airtightness are disposed. A gas flow path for supplying a fuel gas or an oxidant gas (for example, air) to the electrode surface is formed in a contact portion of the membrane-electrode assembly and the separator or in the separator. Electric power is generated by supplying fuel gas to one electrode (fuel electrode) and supplying an oxidant gas containing oxygen such as air to the other electrode (oxygen electrode). That is, at the fuel electrode, the fuel is ionized to produce protons and electrons, the protons pass through the electrolyte membrane, the electrons travel through an external electric circuit formed by connecting both electrodes, and are sent to the oxygen electrode, Water is produced by the reaction. In this way, the chemical energy of the fuel can be directly converted into electric energy and taken out.

  In general, these polymer electrolyte fuel cells are not steadily operated, but are repeatedly activated, operated, and stopped. During operation, the polymer electrolyte membrane is wet, but when it stops, the humidity tends to drop. Therefore, there is a demand for an electrolyte membrane that is small in dimensional change and mechanical property change under low humidity (during drying) and when wet, and that has high proton conductivity even under low humidity.

In general, Nafion (registered trademark of Nafion, DuPont), which is a perfluorocarbon sulfonic acid polymer, is used as an electrolyte membrane for a polymer electrolyte fuel cell because it is chemically stable. ing. Nafion is excellent in ionic conductivity under low humidity, so it is possible to obtain good output in the initial stage.However, since the dimensional change between dry and wet is large, the performance deteriorates during long-term power generation tests. It tends to be easy.
In order to improve these characteristics, an electrolyte membrane has been developed in which a film subjected to simultaneous biaxial stretching near the α dispersion temperature and a film subjected to a heat treatment process are laminated (Patent Document 1). However, not only the manufacturing process becomes complicated, but also the dimensional change between drying and wetting has not been sufficiently reduced. In addition, since Nafion is a fluorine-based polymer, environmental considerations are necessary during synthesis and disposal, and it is expensive. Therefore, development of new electrolyte membrane is desired

Several efforts have already been made for the development of ion conductive polymers based on non-fluorine polymers. For example, polyether ether ketone (PEEK) (Patent Document 2), which is a heat-resistant aromatic polymer, has been developed. In order to obtain good output under low humidity, it is necessary to increase proton conductivity under low humidity, that is, to increase the ion exchange capacity. In that case, as with the perfluorocarbon sulfonic acid polymer, Since the dimensional change between time and wet becomes large, the performance tends to decrease during the long-term power generation test.
In order to improve dimensional stability, an electrolyte membrane in which an ion conductive block copolymer suitable as an electrolyte membrane for a fuel cell using methanol as a fuel is cross-linked with a polyvalent amine or a radical has been studied (Patent Document 3). ). However, since these have insufficient radical resistance at the cross-linked sites, they lack reliability and life in fuel cells using hydrogen as a fuel.
On the other hand, an electrolyte membrane is also proposed in which a polymer membrane having a low ion exchange capacity (preferably less than 0.7 meq / g) and a polymer membrane having a high ion exchange capacity (preferably 0.7 meq / g or more) are laminated ( Patent Document 4). Although this electrolyte membrane is excellent in dimensional stability and methanol barrier property, a configuration excellent in proton conductivity and power generation characteristics under low humidity is not disclosed.
As described above, in the solid oxide fuel cell using hydrogen fuel, the current power generation characteristics under low humidity cannot be obtained while keeping the dimensional stability low.

JP 2005-108537 A JP-A-6-93114 JP 2007-258003 A WO2007 / 086309

  The object of the present invention is to combine high dimensional stability and high proton conductivity (low resistance) under low humidity, and when used in a polymer electrolyte fuel cell using hydrogen as a fuel, high output even under low humidity. To provide an electrolyte membrane capable of obtaining characteristics and also having durability and good bondability with an electrode, and a membrane-electrode assembly and a polymer electrolyte fuel cell using the electrolyte membrane It is in.

  As a result of intensive studies to solve the above problems, the inventors of the present invention are electrolyte laminated films obtained by laminating at least two polymer electrolyte membranes as constituent electrolyte membranes, and at least one of the polymer electrolyte membranes. One has an ion exchange capacity higher than 1.60 meq / g, and at least one of the polymer electrolyte membranes has an ion exchange capacity of 0.70 to 1.60 meq / g, and at least one of the constituent electrolyte membranes. Provided as an electrolyte membrane an electrolyte laminate film comprising a block copolymer (I) comprising a polymer block (A) having an ion conductive group and a flexible polymer block (B) as constituent components In addition, the inventors have found that the above problems can be solved by providing a membrane-electrode assembly and a polymer electrolyte fuel cell comprising the same, and have completed the present invention.

That is, the present invention is an electrolyte laminate film in which at least two polymer electrolyte membranes are laminated as a constituent electrolyte membrane, and at least one of the polymer electrolyte membranes has an ion exchange capacity higher than 1.60 meq / g. Furthermore, at least one of the polymer electrolyte membranes has an ion exchange capacity of 0.70 to 1.60 meq / g, and at least one of the constituent electrolyte membranes has a polymer block (A) having an ion conductive group And a block copolymer (I) containing a flexible polymer block (B) as a constituent component.
When there are two constituent electrolyte membranes, they have different ion exchange capacities, and when there are three or more constituent electrolyte membranes, at least two of them have different ion exchange capacities.

In the electrolyte laminated film, at least two of the constituent electrolyte films are preferably electrolyte films containing the block copolymer (I).
In the electrolyte laminated film, at least one of the constituent electrolyte films containing the block copolymer (I) has an ion exchange capacity higher than 1.60 meq / g, and further contains the block copolymer (I). It is preferable that at least one of the constituent electrolyte membranes has an ion exchange capacity of 0.70 to 1.60 meq / g.
The electrolyte laminate film is formed by laminating at least three polymer electrolyte membranes as constituent electrolyte membranes, and two constituent electrolyte membranes constituting the outermost layer of the electrolyte laminate membrane are ions higher than 1.60 meq / g. An electrolyte laminated film that is a polymer electrolyte film having an exchange capacity is preferable.
In the electrolyte laminated film, the polymer block (A) is preferably a polymer block having an aromatic vinyl compound unit as a main repeating unit.
In the said electrolyte laminated film, it is preferable that the ratio of the aromatic vinyl-type compound unit which occupies for a polymer block (A) is 50 mass% or more.

In the electrolyte laminated film, the polymer block (A) has substantially no ion conductive group and has a constraining block (A1) that functions as a constraining phase and an ion conductive block (A2) having an ion conductive group. It is preferable that it consists of.
In the electrolyte laminated film, in the polymer block (A), the constraining block (A1) is a polymer block having an aromatic vinyl compound unit represented by the general formula (a) as a main repeating unit. The ion conductive block (A2) is preferably a polymer block having an aromatic vinyl compound unit represented by the following general formula (b) as a main repeating unit.
In the electrolyte laminate film, the polymer block (B) is an alkene unit having 2 to 8 carbon atoms, a cycloalkene unit having 5 to 8 carbon atoms, a vinylcycloalkene unit having 7 to 10 carbon atoms, or a carbon number having 4 to 8 carbon atoms. A conjugated alkadiene unit, a conjugated cycloalkadiene unit having 5 to 8 carbon atoms, a vinylcycloalkene unit having 7 to 10 carbon atoms in which part or all of the carbon-carbon double bond has been hydrogenated, and 4 to 8 carbon atoms. A polymer block composed of at least one repeating unit selected from the group consisting of a conjugated alkadiene unit and a conjugated cycloalkadiene unit having 5 to 8 carbon atoms is preferred.

In the said electrolyte laminated film, it is preferable that mass ratio of a polymer block (A1) and a polymer block (A2) is 85: 15-20: 80.
In the electrolyte laminated film, the mass ratio of the polymer block (A) to the polymer block (B) is preferably 95: 5 to 5:95.
In the electrolyte laminated film, the ion conductive group is preferably a group represented by —SO ₃ M or —PO ₃ HM (wherein M represents a hydrogen atom, an ammonium ion, or an alkali metal ion). .
The present invention also relates to a membrane-electrode assembly comprising the electrolyte laminate film.
The present invention also relates to a polymer electrolyte fuel cell comprising the membrane-electrode assembly.

In the electrolyte laminate film of the present invention, the polymer block (A) and the polymer block (B) in the block copolymer (I) contained in at least one constituent electrolyte membrane cause microphase separation, and the polymer block (A) and polymer block (B) have a property to gather together, and since polymer block (A) has an ion conductive group, an ion channel is formed by the gathering of polymer blocks (A). It becomes a passage for ions such as protons. In addition, the presence of the polymer block (B) makes the block copolymer (I) elastic and flexible as a whole, and the moldability (assembly) is assured in the production of membrane-electrode assemblies and solid polymer fuel cells. , Bondability, tightenability, etc.). The flexible polymer block (B) is composed of an alkene unit or a conjugated alkadiene unit.
In the present invention, “microphase separation” means phase separation in a microscopic sense, and more specifically, means phase separation in which the formed domain size is less than or equal to the wavelength of visible light (3800 to 7800 mm). It shall be.

  The electrolyte laminated membrane of the present invention has high dimensional stability and high proton conductivity (low resistance) under low humidity, and the membrane-electrode assembly comprising the electrolyte laminated membrane as an electrolyte membrane uses hydrogen as a fuel. When used in a polymer electrolyte fuel cell, it is possible to obtain high output characteristics even under low humidity, and excellent durability and good bondability with electrodes.

Hereinafter, the present invention will be described in detail.
The block copolymer (I) contained in at least one of the polymer electrolyte membranes which are constituent electrolyte membranes of the electrolyte laminated membrane of the present invention is at least 50 of the polymer electrolyte membrane containing the block copolymer (I) in order to sufficiently exhibit its characteristics. It is preferable to contain in the ratio of -100 mass%, It is more preferable to contain at 70 mass% or more, It is much more preferable to contain at 90 mass% or more. As other constituents of the polymer electrolyte membrane, a polymer having an aromatic vinyl compound unit as a main repeating unit, a polymer having a conjugated alkadiene as a main repeating unit, a hydrogenated product thereof, an alkene as a main repeating unit, , Polymer having (meth) acrylic acid ester as the main repeating unit, polymer having vinyl ester as the main repeating unit, polymer having vinyl ether as the main repeating unit, polyether ketone, polysulfide, polyphosphazene, polyphenylene , Polybenzimidazole, polyethersulfone, polyphenylene oxide, polycarbonate, polyamide, polyimide, polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polyphenylquinoxaline, polysiloxane Other polymer materials such as phosphorus and polytriazine, softeners, stabilizers, light stabilizers, antistatic agents, mold release agents, flame retardants, foaming agents, pigments, dyes, whitening agents, carbon fibers, inorganic fillers And various other additives.

The block copolymer (I) comprises an ion conductive group-containing polymer block (A) and a flexible polymer block (B) as constituent components. As the polymer block (A), an aromatic vinyl compound is used. Polymer block whose unit is the main repeating unit, polyether ketone block, polysulfide block, polyphosphazene block, polyphenylene block, polybenzimidazole block, polyethersulfone block, polyphenylene oxide block, polycarbonate block, polyamide block, polyimide block, poly Urea block, polysulfone block, polysulfonate block, polybenzoxazole block, polybenzothiazole block, polyphenylquinoxaline block, polyquinoline block, Litriazine block, etc., among them, polymer block mainly comprising aromatic vinyl compound unit, polyetherketone block, polysulfide block, polyphosphazene block, polyphenylene block, polybenzimidazole block, polyethersulfone block, A polyphenylene oxide block or the like is preferable, and a polymer block having an aromatic vinyl compound unit as a main repeating unit is more preferable from the viewpoint of easy synthesis.
The aromatic ring in the aromatic vinyl compound is preferably a carbocyclic aromatic ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring. As specific examples of these aromatic vinyl compounds, when α-carbon is tertiary carbon, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-isopropylstyrene 4-n-propylstyrene, 4-isopropylstyrene, 4-n-butylstyrene, 4-isobutylstyrene, 4-t-butylstyrene, 4-n-octylstyrene, 2,4-dimethylstyrene, 2,5- Aromatic vinyl compounds such as dimethyl styrene, 3,5-dimethyl styrene, 2,4,6-trimethyl styrene, 2-methoxy styrene, 3-methoxy styrene, 4-methoxy styrene, vinyl naphthalene, vinyl anthracene and the like can be mentioned.
Further, when the α-carbon is a quaternary carbon, a hydrogen atom bonded to the α-carbon atom is an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, n-propyl group, isopropyl group, n- Substituted with a butyl group, isobutyl group, sec-butyl group or tert-butyl group), a halogenated alkyl group having 1 to 4 carbon atoms (chloromethyl group, 2-chloroethyl group, 3-chloroethyl group, etc.) or a phenyl group. Specific examples include aromatic vinyl compounds, such as α-methylstyrene, α-methyl-4-methylstyrene, α-methyl-4-ethylstyrene, α-methyl-4-t-butylstyrene. 1,1-diphenylethylene and the like. These can be used singly or in combination of two or more. Among them, styrene, α-methylstyrene, 4-methylstyrene, 4-ethylstyrene, α-methyl-4-methylstyrene, α-methyl-2-methylstyrene Is preferred. The form in the case of copolymerizing two or more of these may be random copolymerization, block copolymerization, graft copolymerization or tapered copolymerization.

  The polymer block (A) may contain one or more other monomer units as long as the effects of the present invention are not impaired. Examples of such other monomers include conjugated alkadienes having 4 to 8 carbon atoms (1,3-butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2,4-hexadiene, 2,3- Dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-heptadiene, 1,4-heptadiene, 3,5-heptadiene, etc.), alkenes having 2 to 8 carbon atoms (ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 1-heptene, 2-heptene, 1-octene, 2-octene, etc.), (meth) acrylic acid ester (Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate) Le, vinyl pivalate, etc.), vinyl ethers (methyl vinyl ether, isobutyl vinyl ether, etc.), and the like. The form of copolymerization with the other monomer must be random copolymerization.

  When the polymer block (A) is a repeating unit mainly composed of an aromatic vinyl compound unit, microphase separation from the polymer block (B) is more likely to occur, and as a result, ion conductivity can be increased. . In this case, the aromatic vinyl compound unit preferably occupies 50% by mass or more of the polymer block (A) in order to impart sufficient ion conductivity to the finally obtained polymer electrolyte laminate film, It is more preferable to occupy 70% by mass or more, and even more preferable to occupy 90% by mass or more.

    The molecular weight of each polymer block (A) can be appropriately selected depending on the properties of the electrolyte laminated film, required performance, other polymer components, and the like. When the molecular weight is large, the mechanical properties of the electrolyte laminate film tend to be high. However, when the molecular weight is too large, it becomes difficult to form and form the block copolymer (I). In this case, it is difficult to form an ion channel, and thus there is a tendency that ion conductivity is not exhibited, and mechanical characteristics tend to be low. Therefore, it is important to appropriately select a molecular weight according to required performance. The molecular weight of each polymer block (A) in the state where the ion conductive group is not introduced is usually selected from the range of 1,000 to 1,000,000 as the number average molecular weight in terms of polystyrene. Preferably, it is selected from the range of 2,000-250,000, and more preferably selected from the range of 3,000-100,000.

  The polymer block (A) may be crosslinked by a known method within a range not impairing the effects of the present invention. By introducing cross-linking, the ion channel phase formed by the polymer block (A) is less likely to swell, and the change in mechanical properties (such as tensile properties) between drying and wetting tends to be further reduced.

  The ion conductive group that can be used in the present invention is not particularly limited, and a normal polar functional group having ion conductivity can be used, and those having a high affinity with anions and / or cations, particularly functional groups. Those which are easily dissociated as ions are preferred, and examples thereof include sulfonic acid groups, phosphonic acid groups, carboxylic acid groups, quaternary ammonium salts, and quaternary salts of pyridine. In particular, a salt obtained by exchanging a protonic functional group or a proton of the protonic functional group with another ion is excellent in proton conductivity, and examples thereof include a sulfonic acid group, a phosphonic acid group, a carboxylic acid group, and salts thereof. From the viewpoints of ion conductivity, ease of introduction, cost, etc., sulfonic acid groups and phosphonic acid groups and their salts are preferably used. The ion exchange capacity can be adjusted by appropriately selecting the type and concentration of the ion conductive group.

  Further, the polymer block (A) may be composed of a constraining block (A1) having substantially no ion conductive group and an ion conductive block (A2) having an ion conductive group. The polymer block (A1) and the polymer block (A2) have a property of causing microphase separation, and the polymer blocks (A1) and the polymer blocks (A2) are aggregated. Since the polymer block (A1) needs to exhibit a restraining function in an atmosphere where power is generated, the polymer block has a glass transition point or softening point of 40 ° C. or higher when it becomes a homopolymer. The constraint block is preferably 70 ° C. or higher, more preferably 80 ° C. or higher. Since the polymer block (A2) has an ion conductive group, an ion channel is formed by the assembly of the polymer blocks (A2) and becomes a passage for protons. Here, the monomer unit constituting the constraining block (A1) and the ion conductive block (A2) can be selected from monomer units that can constitute the polymer block (A).

  The ratio of the constraining block (A1) and the ion conductive block (A2) is not particularly limited, but the ratio of the monomer units before introducing the ion conductive group is 85:15 to 0: 100. Is preferable, and is preferably 85:15 to 20:80, more preferably 80:20 to 20:80, from the viewpoint that the characteristics of each block can be sufficiently extracted. 75:25 to 25:75 in that (I) has a low molecular weight (for example, 50,000 or less), that is, the characteristics of each block can be sufficiently extracted even in a configuration excellent in moldability, film forming property, and the like. Is most preferred.

  The restraint block (A1) having substantially no ion conductive group is represented by the following general formula (a).

(Wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{2 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, at least one of which is carbon It represents a polymer block having an aromatic vinyl compound unit represented by the formula (1 to 8) as a main repeating unit.

In the general formula (a), the alkyl group having 1 to 4 carbon atoms represented by R ¹ may be linear or branched, and is methyl, ethyl, propyl, isopropyl, butyl, sec-butyl. Group, isobutyl group, tert-butyl group and the like. The alkyl group having 1 to 8 carbon atoms represented by R ^{2 to} R ⁴ may be independently linear or branched, and is methyl, ethyl, propyl, isopropyl, butyl, sec-butyl. Group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, 1-methylpentyl group, heptyl group, octyl group and the like. Preferable specific examples of the aromatic vinyl compound unit represented by the general formula (a) include p-methylstyrene unit, 4-tert-butylstyrene unit, p-methyl-α-methylstyrene unit, 4-tert. -Butyl- (alpha) -methylstyrene unit etc. are mentioned, These may be used 1 type or in combination of 2 or more types. The form in the case of polymerizing (copolymerizing) two or more of these may be random copolymerization, block copolymerization, graft copolymerization, or tapered copolymerization.

The polymer block (A1) may contain one or more other monomer units in addition to the aromatic vinyl compound unit as long as the function as a constraining phase is not hindered. Examples of the monomer that gives such other monomer unit include conjugated alkadienes having 4 to 8 carbon atoms, alkenes having 2 to 8 carbon atoms, (meth) acrylic acid esters, vinyl esters, vinyl ethers, and the like. Specific examples thereof are the same as in the description of the polymer block (A) described above. The copolymerization form of the aromatic vinyl compound and the other monomer needs to be random copolymerization.
From the viewpoint of fulfilling the function as a constrained phase, the above-mentioned aromatic vinyl compound unit preferably accounts for 50% by mass or more, more preferably 70% by mass or more, and 90% by mass of the polymer block (A1). It is even more preferable to occupy% or more.

  The molecular weight of each polymer block (A1) is appropriately selected depending on the properties of the polymer electrolyte constituting the polymer electrolyte membrane in the present invention, the required performance, other polymer components, and the like. When the molecular weight is large, the mechanical properties of the polymer electrolyte tend to be high. However, when the molecular weight is too large, it is difficult to form and form the block copolymer (I), and when the molecular weight is small, the mechanical properties tend to be low. Therefore, it is important to appropriately select the molecular weight according to the required performance. The molecular weight is usually preferably selected from the range of 800 to 500,000 as the number average molecular weight in terms of polystyrene, more preferably selected from the range of 2000 to 150,000, and preferably 3000 to 50,000. Even more preferably, it is selected from a range.

  The ion conductive block (A2) having an ion conductive group is represented by the following general formula (b).

(In the formula, Ar ¹ represents an aryl group having 6 to 14 carbon atoms which may have ¹ to 3 substituents, and R ⁵ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or 1 to 3). It represents an aryl group having 6 to 14 carbon atoms which may have one substituent) and a polymer block having a main repeating unit.

Examples of the aryl group having 6 to 14 carbon atoms represented by Ar ¹ in the general formula (b) include a phenyl group, a naphthyl group, a phenanthryl group, an anthryl group, an indenyl group, a biphenylyl group, and a pyrenyl group. And a naphthyl group is preferable, and a phenyl group is more preferable. The optional 1 to 3 substituents that can be directly bonded to the aromatic ring of the aryl group are each independently a linear or branched alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, propyl group). Group, isopropyl group, butyl group, sec-butyl group, isobutyl group, tert-butyl group, etc.). The alkyl group having 1 to 4 carbon atoms represented by R ⁵ in the general formula (b) may be linear or branched, and is methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group. , Isobutyl group, tert-butyl group and the like. Examples of the aryl group having 6 to 14 carbon atoms that may have 1 to 3 substituents in R ⁵ include a phenyl group, a naphthyl group, a phenanthryl group, an anthryl group, an indenyl group, a biphenylyl group, and a pyrenyl group. The optional 1 to 3 substituents that can be directly bonded to the aromatic ring of the aryl group are each independently a linear or branched alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group). Group, propyl group, isopropyl group, butyl group, sec-butyl group, isobutyl group, tert-butyl group, etc.).
Specific examples of the aromatic vinyl compound that gives the aromatic vinyl compound unit represented by the general formula (b) include styrene, vinyl naphthalene, vinyl anthracene, vinyl phenanthrene, vinyl biphenyl, α-methyl styrene, 1-methyl. Examples include -1-naphthylethylene and 1-methyl-1-biphenylylethylene, and styrene and α-methylstyrene are particularly preferable.
The aromatic vinyl compound that gives the aromatic vinyl compound unit represented by the general formula (b) may be used alone or in combination of two or more. The form in the case of copolymerizing two or more types may be random copolymerization, block copolymerization, graft copolymerization, or tapered copolymerization.

The polymer block (A2) may contain one or more other monomer units in addition to the aromatic vinyl compound unit within a range not impairing the effects of the present invention. Examples of the monomer that gives such other monomer unit include conjugated alkadienes having 4 to 8 carbon atoms, alkenes having 2 to 8 carbon atoms, (meth) acrylic acid esters, vinyl esters, vinyl ethers, and the like. Specific examples thereof are the same as in the description of the polymer block (A) described above. The copolymerization form of the aromatic vinyl compound and the other monomer needs to be random copolymerization.
The proportion of the aromatic vinyl compound unit contained in the polymer block (A2) is preferably 50 mol% or more, more preferably 60 mol% or more from the viewpoint of imparting sufficient ion conductivity, It is still more preferable that it is 80 mol% or more.

  The molecular weight of each polymer block (A2) in the state where the ion conductive group is not introduced is appropriately selected depending on the properties of the polymer electrolyte, required performance, other polymer components, etc., but the number average in terms of polystyrene The molecular weight is usually preferably selected from the range of 500 to 500,000, more preferably selected from the range of 1000 to 100,000, and more preferably selected from the range of 2000 to 50,000. Even more preferred.

  The polymer block (A2) may be crosslinked by a known method within a range not impairing the effects of the present invention. By introducing cross-linking, changes in dimensions and mechanical properties (tensile properties) between drying and wetting tend to be further reduced.

  The block copolymer (I) used in the polymer electrolyte laminate film of the present invention comprises a flexible polymer block (B) as a constituent component in addition to the polymer block (A). The polymer block (B) forms a flexible phase. The polymer block (A) and the polymer block (B) undergo a microphase separation, and the polymer block (A) and the polymer block (B) have a property of gathering together, and the polymer block (A ) Has an ion conductive group, so that an ion channel is formed by the assembly of the polymer blocks (A) and becomes a passage for protons. By having such a polymer block (B), the block copolymer (I) becomes elastic and flexible as a whole, and formability (assembleability) in the production of membrane-electrode assemblies and polymer electrolyte fuel cells. , Bondability, tightenability, etc.) are improved. The flexible polymer block (B) here is a so-called rubber-like polymer block having a glass transition point or softening point of 50 ° C. or lower, preferably 20 ° C. or lower, more preferably 10 ° C. or lower.

  Monomers that can constitute the repeating unit constituting the flexible polymer block (B) include alkenes having 2 to 8 carbon atoms, cycloalkenes having 5 to 8 carbon atoms, and vinylcycloalkenes having 7 to 10 carbon atoms. A conjugated alkadiene having 4 to 8 carbon atoms and a conjugated cycloalkadiene having 5 to 8 carbon atoms, a vinylcycloalkene having 7 to 10 carbon atoms in which one of the carbon-carbon double bonds is hydrogenated, and a carbon-carbon double bond 4 to 8 conjugated alkadienes in which one of them is hydrogenated, conjugated cycloalkadienes having 5 to 8 carbon atoms in which one of the carbon-carbon double bonds is hydrogenated, (meth) acrylic acid esters, vinyl esters Vinyl ethers and the like, and these can be used alone or in combination of two or more. The form in the case of copolymerizing two or more types may be random copolymerization, block copolymerization, graft copolymerization, or tapered copolymerization. Further, when the monomer to be used for (co) polymerization has two carbon-carbon double bonds, any of them may be used for the polymerization, and in the case of conjugated alkadiene, it is a 1,2-bond. 1,4-bonds may be used, and the ratio of 1,2-bonds to 1,4-bonds is not particularly limited as long as the glass transition point or softening point is 50 ° C. or lower.

When the repeating unit constituting the polymer block (B) has a carbon-carbon double bond as in the case of a vinylcycloalkene unit, a conjugated alkadiene unit or a conjugated cycloalkadiene unit, the present invention From the standpoint of improving the power generation performance and heat deterioration resistance of the membrane-electrode assembly using the polymer electrolyte laminate film, it is preferable that 30 mol% or more of such carbon-carbon double bonds are hydrogenated. More preferably, 50 mol% or more is hydrogenated, and more preferably 80 mol% or more is hydrogenated. The hydrogenation rate of the carbon-carbon double bond can be calculated by a commonly used method, for example, iodine value measurement method, ¹ H-NMR measurement or the like.

  The polymer block (B) has 2 to 2 carbon atoms from the viewpoint of giving the resulting block copolymer (I) elasticity and, in turn, good moldability in the production of a membrane-electrode assembly and a polymer electrolyte fuel cell. 8 alkene units, 5 to 8 carbon cycloalkene units, 7 to 10 vinyl cycloalkene units, 4 to 8 conjugated alkadiene units, 5 to 8 conjugated cycloalkadiene units, carbon- 7-10 carbon vinylcycloalkene units in which some or all of the carbon double bonds have been hydrogenated, 4 to 8 carbon conjugated alkadiene units in which some or all of the carbon-carbon double bonds have been hydrogenated And a polymer comprising at least one repeating unit selected from conjugated cycloalkadiene units having 5 to 8 carbon atoms in which some or all of the carbon-carbon double bonds are hydrogenated. Preferably, it is a rock, a alkene unit having 2 to 8 carbon atoms, a conjugated alkadiene unit having 4 to 8 carbon atoms, and a conjugate having 4 to 8 carbon atoms in which part or all of the carbon-carbon double bonds are hydrogenated. More preferably, it is a polymer block composed of at least one repeating unit selected from alkadiene units, and is an alkene unit having 2 to 6 carbon atoms, a conjugated alkadiene unit having 4 to 8 carbon atoms, and a carbon-carbon double bond. It is even more preferable that the polymer block is composed of at least one repeating unit selected from conjugated alkadiene units having 4 to 8 carbon atoms partially or wholly hydrogenated. In the above, the most preferable alkene unit is an isobutene unit, and the most preferable conjugated alkadiene unit is a 1,3-butadiene unit and / or an isoprene unit.

  As the alkene having 2 to 8 carbon atoms, ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 1-heptene, 2-heptene, 1 -Octene, 2-octene and the like, and cyclopentene having 5 to 8 carbon atoms include cyclopentene, cyclohexene, cycloheptene and cyclooctene, and vinylcycloalkene having 7 to 10 carbon atoms as vinylcyclopentene, vinylcyclohexene, Examples thereof include vinylcycloheptene and vinylcyclooctene. Examples of the conjugated alkadiene having 4 to 8 carbon atoms include 1,3-butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2,4-hexadiene, 2 , 3-Dimethyl-1,3-butadiene, 2-ethyl-1, -Butadiene, 1,3-heptadiene, 1,4-heptadiene, 3,5-heptadiene and the like are mentioned, and examples of the conjugated cycloalkadiene having 5 to 8 carbon atoms include cyclopentadiene and 1,3-cyclohexadiene. .

  In addition to the above monomers, the polymer block (B) may contain other monomers as long as the purpose of the polymer block (B) to give elasticity to the block copolymer (I) is not impaired. For example, it may contain aromatic vinyl compounds such as styrene and vinyl naphthalene; halogen-containing vinyl compounds such as vinyl chloride. In this case, the copolymerization form of the monomer and other monomer needs to be random copolymerization. The amount of such other monomer used is preferably less than 50% by weight, more preferably less than 30% by weight, based on the total of the above monomers and other monomers. It is still more preferable that it is less than mass%.

  The structure of the block copolymer (I) having the polymer block (A) and the polymer block (B) as constituent components is not particularly limited, but it is desirable that there are a plurality of polymer blocks (A). It is desirable that at least one end of (B) is not a terminal of the block copolymer (I). Examples include an ABA type triblock copolymer, an ABBA type triblock copolymer and an AB type diblock copolymer, an ABBA type tetrablock copolymer. Polymer, A-B-A-B-A type pentablock copolymer, B-A-B-A-B type pentablock copolymer, (A-B) nX-type star copolymer (X is And (BA) nX type star copolymer (X represents a coupling agent residue). These block copolymers (I) may be used alone or in combination of two or more.

  The mass ratio of the polymer block (A) to the polymer block (B) is preferably 95: 5 to 5:95, more preferably 90:10 to 10:90, and 65:35 to 10 : 90 is even more preferable. When this mass ratio is 95: 5 to 5:95, it is advantageous for the ion channel formed by the polymer block (A) to become a cylindrical or continuous phase by microphase separation, which is practically sufficient. Excellent ionic conductivity is exhibited, and the ratio of the polymer block (B) that is hydrophobic is appropriate, and excellent water resistance is exhibited.

  When the block copolymer (I) used in the present invention is composed of the polymer block (A1), the polymer block (A2) and the polymer block (B), the structure of the block copolymer is not particularly limited. As examples, A2-B-A2-type triblock copolymer, A2-B-A1-A2 tetrablock copolymer, B-A2-B-A1 tetrablock copolymer, A2-B-A1-B tetra Block copolymer, A1-B-A1-A2 tetrablock copolymer, A2-B-A2-A1 tetrablock copolymer, A2-A1-B-A1-A2 pentablock copolymer, A1-A2- B-A2-A1 pentablock copolymer, A2-A1-B-A2-A1 pentablock copolymer, A1-B-A2-B-A1 pentablock copolymer, A2-B-A1-A2-B Penta Lock copolymer, A2-B-A1-A2-A1 pentablock copolymer, A2-B-A1-B-A1 pentablock copolymer, A2-B-A2-B-A1 pentablock copolymer, A2-B-A2-A1-B pentablock copolymer, B-A2-B-A2-A1 pentablock copolymer, B-A2-B-A1-A2 pentablock copolymer, B-A2-B -A1-B pentablock copolymer, A1-A2-A1-B-A1 pentablock copolymer, etc. are mentioned.

  The block copolymer (I) used in the present invention includes those partially containing graft bonds. Examples of the block copolymer partially containing a graft bond include those in which a part of the constituting polymer block is grafted to the main part (for example, main chain) of the block copolymer.

  The number average molecular weight of the block copolymer (I) used in the present invention is not particularly limited, but is usually 10,000 to 1,000 as the number average molecular weight in terms of polystyrene in a state where no ion conductive group is introduced. 15,000 is preferable, 15,000 to 700,000 is more preferable, and 20,000 to 500,000 is even more preferable.

The block copolymer (I) constituting the polymer electrolyte laminate film of the present invention needs to have an ion conductive group in the polymer block (A). Examples of ions in the present invention when referring to ionic conductivity include protons. The ion conductive group is not particularly limited as long as the membrane-electrode assembly produced using the polymer electrolyte laminate film can express sufficient ionic conductivity, but among them -SO ₃ M or A sulfonic acid group, a phosphonic acid group or a salt thereof represented by —PO ₃ HM (wherein M represents a hydrogen atom, an ammonium ion or an alkali metal ion) is preferably used. As the ion conductive group, a carboxyl group or a salt thereof can also be used. The introduction position of the ion conductive group is the polymer block (A) because it is particularly effective for improving the radical resistance of the entire block copolymer.

  The introduction position of the ion conductive group into the polymer block (A) is not particularly limited, but when the polymer block (A) contains an aromatic ring in the repeating unit, the viewpoint of facilitating ion channel formation. Therefore, it is preferably introduced into the aromatic ring.

  The amount of ion-conducting group introduced is appropriately selected depending on the required performance of the resulting block copolymer (I), etc., but has sufficient ion conductivity to be used as an electrolyte membrane for a polymer electrolyte fuel cell. In order to express, it is usually preferable that the ion exchange capacity of the block copolymer (I) is 0.70 meq / g or more, and 0.80 meq / g or more. It is more preferable. The upper limit of the ion exchange capacity of the block copolymer (I) is 4.0 meq / g or less because if the ion exchange capacity becomes too large, the hydrophilicity tends to increase and the water resistance becomes insufficient. preferable.

  The production method of the block copolymer (I) used in the present invention is not particularly limited, and a known method can be used, but after producing a block copolymer having no ion conductive group, A method of bonding an ion conductive group is preferable.

  Depending on the type, molecular weight, etc. of the monomer constituting the polymer block (A) or (B), the production method of the polymer block (A) or (B) can be a radical polymerization method, an anionic polymerization method, a cationic polymerization method, Although it is appropriately selected from coordination polymerization method and the like, radical polymerization method, anionic polymerization method and cationic polymerization method are preferably selected from the viewpoint of industrial ease. In particular, the so-called living polymerization method is preferable from the viewpoint of molecular weight, molecular weight distribution, polymer structure, ease of bonding between the polymer block (B) and the polymer block (A) made of flexible components, and specifically living A radical polymerization method, a living anion polymerization method, and a living cation polymerization method are preferred.

As a specific example of the production method, a production method of a block copolymer comprising a polymer block (A) composed of poly (α-methylstyrene) and a polymer block (B) composed of a conjugated alkadiene will be described. In this case, it is preferable to produce by a living anionic polymerization method from the viewpoint of industrial ease, molecular weight, molecular weight distribution, ease of bonding between the polymer block (A) and the polymer block (B), and the following specific examples A typical synthesis example is shown.
(1) A method of obtaining an ABA block copolymer by sequentially polymerizing α-methylstyrene under a temperature condition of −78 ° C. after conjugated alkadiene polymerization using a dianionic initiator in a tetrahydrofuran solvent (Macromolecules , (1969), 2 (5), 453-458),
(2) α-methylstyrene is subjected to bulk polymerization using an anionic initiator, then conjugated alkadiene is sequentially polymerized, and then a coupling reaction is performed with a coupling agent such as tetrachlorosilane, and (AB) nX Method for obtaining a type block copolymer (Kautsch. Gummi, Kunstst., (1984), 37 (5), 377-379; Polym. Bull., (1984), 12, 71-77),

(3) An organic lithium compound in a nonpolar solvent is used as an initiator, and a concentration of 5 to 50% by mass at a temperature of −30 ° C. to 30 ° C. in the presence of a polar compound having a concentration of 0.1 to 10% by mass. A polymer obtained by polymerizing α-methylstyrene, conjugated alkadiene to the resulting living polymer, and then adding a coupling agent to obtain an ABA block copolymer.
(4) A concentration of 5 to 50% by mass at a temperature of −30 ° C. to 30 ° C. in the presence of a polar compound having a concentration of 0.1 to 10% by mass using an organolithium compound in a nonpolar solvent as an initiator. Α-methylstyrene (a monomer constituting the polymer block (A2)) is polymerized, and the resulting living polymer is polymerized with a conjugated alkadiene. From the resulting α-methylstyrene polymer block and the conjugated alkadiene polymer block, A method for obtaining an A2-B-A1 type block copolymer by polymerizing a monomer constituting the polymer block (A1) to a living block copolymer.

Specific examples of the production method include a polymer block (A1) having an aromatic vinyl compound such as 4-tert-butylstyrene as a main repeating unit, a polymer block (A2) comprising styrene or α-methylstyrene, and a conjugated alkadiene. A method for producing a block copolymer or graft copolymer having a polymer block (B) comprising the above as a constituent component will be described. In this case, the living anion polymerization method is preferable from the viewpoint of industrial ease, molecular weight, molecular weight distribution, ease of bonding of the polymer blocks (A1), (B) and (A2), and the following specific synthesis examples Is shown.
(5) An anionic polymerization initiator is used in a cyclohexane solvent, and an aromatic vinyl compound such as 4-tert-butylstyrene is polymerized at a temperature of 10 to 100 ° C., and then a conjugated alkadiene and styrene are sequentially polymerized. (6) Aromatic compounds such as 4-tert-butylstyrene using an anionic polymerization initiator in a cyclohexane solvent at a temperature of 10 to 100 ° C. A method in which a vinyl compound is polymerized and then styrene and conjugated alkadiene are sequentially polymerized, and then a coupling agent such as phenyl benzoate is added to obtain an A1-A2-B-A2-A1 type block copolymer,

(7) Using an anionic polymerization initiator in a cyclohexane solvent, under a temperature condition of 10 to 100 ° C., an aromatic vinyl compound such as 4-tert-butylstyrene, a conjugated alkadiene, 4-tert-butylstyrene, etc. A1-B-A1 type block copolymer is prepared by sequential polymerization of aromatic vinyl compounds and an anionic polymerization initiator system (anionic polymerization initiator / N, N, N ′, N′-tetramethylethylenediamine) is added. And then lithiating the conjugated alkadiene unit and then polymerizing styrene to obtain an A1-B (-g-A2) -A1 type block / graft copolymer,
(8) A concentration of 5 to 50% by mass at a temperature of −30 ° C. to 30 ° C. in the presence of a polar compound having a concentration of 0.1 to 10% by mass using an organolithium compound in a nonpolar solvent as an initiator. Α-methylstyrene is polymerized, and the resulting living polymer is sequentially polymerized with an aromatic vinyl compound such as conjugated alkadiene or 4-tert-butylstyrene to produce an A2-B-A1 type block copolymer, and a similar technique Α-methylstyrene is polymerized in step A2, and the resulting living polymer is sequentially polymerized with an aromatic vinyl compound such as 4-tert-butylstyrene, an aromatic vinyl compound such as conjugated alkadiene, 4-tert-butylstyrene, and the like. A method of obtaining a -A1-B-A1 type block copolymer can be employed / applied.

  The block copolymer thus produced is subjected to a hydrogenation reaction of double bonds of conjugated alkadiene units having 4 to 8 carbon atoms constituting the polymer block (B). As a method of the hydrogenation reaction, a solution of a block copolymer obtained by anionic polymerization or the like is charged into a pressure vessel, and a hydrogenation reaction is performed in a hydrogen atmosphere using a Ziegler type hydrogenation catalyst such as a Ni / Al type. The method of performing can be illustrated.

  Next, a method for bonding an ion conductive group to the obtained block copolymer will be described. First, a method for introducing a sulfonic acid group into the obtained block copolymer will be described. Sulfonation can be performed by a known sulfonation method. As such a method, an organic solvent solution or suspension of a block copolymer is prepared, a sulfonating agent is added and mixed, a method of adding a gaseous sulfonating agent directly to the block copolymer, etc. Is exemplified.

  Sulfonating agents used include sulfuric acid, a mixture of sulfuric acid and aliphatic acid anhydride, chlorosulfonic acid, a mixture of chlorosulfonic acid and trimethylsilyl chloride, sulfur trioxide, a mixture of sulfur trioxide and triethyl phosphate. Examples thereof include aromatic organic sulfonic acids represented by 2,4,6-trimethylbenzenesulfonic acid. Examples of the organic solvent to be used include halogenated hydrocarbons such as methylene chloride, linear aliphatic hydrocarbons such as hexane, cyclic aliphatic hydrocarbons such as cyclohexane, and the like. You may use it, selecting suitably from several combinations.

  As a method for removing the sulfonated product as a solid from the reaction solution containing the sulfonated product of the block copolymer, a method of pouring the reaction solution into water and precipitating the sulfonated product, and then distilling off the solvent at atmospheric pressure, Stopper water is gradually added and suspended in the reaction solution, and the sulfonated product is precipitated, and then the solvent is distilled off at atmospheric pressure. From the viewpoint of increasing the washing efficiency, a method of gradually adding and suspending the stopper water in the reaction solution to precipitate the sulfonated product is suitably used.

  A method for introducing a phosphonic acid group into the obtained block copolymer will be described. Phosphonation can be performed by a known phosphonation method. Specifically, for example, an organic solvent solution or suspension of a block copolymer is prepared, and the copolymer is reacted with chloromethyl ether or the like in the presence of anhydrous aluminum chloride to introduce a halomethyl group into the aromatic ring. Thereafter, there may be mentioned a method in which phosphorus trichloride and anhydrous aluminum chloride are added and reacted, followed by a hydrolysis reaction to introduce a phosphonic acid group. Alternatively, a method may be exemplified in which phosphorus trichloride and anhydrous aluminum chloride are added to the copolymer and reacted to introduce a phosphinic acid group into the aromatic ring, and then the phosphinic acid group is oxidized with nitric acid to form a phosphonic acid group.

The degree of sulfonation or phosphonation is, as already mentioned, until the ion exchange capacity of the block copolymer is 0.70 meq / g or more, especially 0.80 meq / g or more, but 4.0 meq / g or less. It is desirable to be sulfonated or phosphonated so that Thereby, practical ion conduction performance is obtained. The ion exchange capacity of the sulfonated or phosphonated block copolymer, or the sulfonation rate or phosphonation rate in the aromatic vinyl compound in the block copolymer is determined by acid value titration, infrared spectroscopic measurement, nuclear It can be calculated using an analytical means such as magnetic resonance spectrum ( ¹ H-NMR spectrum) measurement.

  The electrolyte laminate film of the present invention has at least two electrolyte membranes having different ion exchange capacities so that the electrolyte laminate membrane has both high dimensional stability and high proton conductivity (low resistance) under low humidity. Is important to. That is, when there are two constituent electrolyte membranes, they have different ion exchange capacities, and when there are three or more constituent electrolyte membranes, at least two of them have different ion exchange capacities.

  In order for the electrolyte laminate membrane of the present invention to exhibit sufficient ion conductivity for use as an electrolyte laminate membrane for a polymer electrolyte fuel cell, at least one ion exchange of the polymer electrolyte membrane which is a constituent electrolyte membrane The capacity needs to be higher than 1.60 meq / g, and preferably 1.70 meq / g or more. The upper limit of the ion exchange capacity is preferably 4.0 meq / g or less because if the ion exchange capacity becomes too large, the hydrophilicity tends to increase and the water resistance becomes insufficient. Further, in order to have sufficient dimensional stability, it is necessary that at least one ion exchange capacity of the polymer electrolyte membrane which is a constituent electrolyte membrane is in a range of 0.70 to 1.60 meq / g, It is preferably 0.80 to 1.50 meq / g. If the ion exchange capacity becomes too small, proton conductivity tends to decrease under low humidity.

  As the electrolyte membrane constituting the electrolyte laminated film of the present invention, it is important to reduce the resistance between the electrolyte membrane and the electrode in order to bring out high power generation characteristics under low humidity. From this point of view, the electrolyte laminate film of the present invention is formed by laminating at least three polymer electrolyte membranes as constituent electrolyte membranes, and the two constituent electrolyte membranes constituting the outermost layer of the electrolyte laminate membrane are both 1.60 meq. A polymer electrolyte membrane having an ion exchange capacity higher than / g is preferred.

  In addition, when the electrolyte laminate film of the present invention is used as an electrolyte laminate film for a polymer electrolyte fuel cell, in order to have sufficient ion conductivity and high dimensional stability under low humidity, The difference between the ion exchange capacity of the electrolyte membrane having the larger capacity and the ion exchange capacity of the electrolyte membrane having the smaller capacity is preferably 0.05 meq / g or more, more preferably 0.10 meq / g or more. Is more preferably 0.15 meq / g or more.

  In addition, the ion exchange capacity as a whole of the electrolyte laminated film of the present invention is preferably in the range of 1.0 to 3.0 meq / g in order to have sufficient ion conductivity and high dimensional stability. More preferably, it is in the range of 0.2 to 2.7 meq / g, and still more preferably in the range of 1.3 to 2.5 meq / g.

From the above viewpoint, the degree of sulfonation or phosphonation in the block copolymer (I) is such that, in the case of an electrolyte membrane having a large ion exchange capacity, the ion exchange capacity is higher than 1.60 meq / g. In the case of an electrolyte membrane having a small ion exchange capacity, it is preferable to sulfonate or phosphonate to 1.70 meq / g or more and 4.0 meq / g or less. Needs to be sulfonated or phosphonated so that its ion exchange capacity is in the range of 0.70 to 1.60 meq / g, and the sulfone is adjusted to 0.80 to 1.50 meq / g or less. Or phosphonation. The ion exchange capacity of a sulfonated or phosphonated copolymer or an electrolyte membrane containing the copolymer, the sulfonation rate or phosphonation rate of the copolymer is determined by acid value titration method, infrared spectroscopic measurement, nuclear magnetic resonance It can be calculated using an analysis means such as spectrum ( ¹ H-NMR spectrum) measurement.

  At least two of the electrolyte membranes constituting the electrolyte laminate film of the present invention contain the block copolymer (I), and at least one of the block copolymer (I) -containing electrolyte membranes is from 1.60 meq / g. Sufficient ions under low humidity have a high ion exchange capacity and at least one of the block copolymer (I) -containing electrolyte membranes has an ion exchange capacity in the range of 0.70 to 1.60 meq / g. From the viewpoint of combining conductivity and high dimensional stability, it is preferable.

  The ion conductive group may be introduced in the form of a salt neutralized with a suitable metal ion (for example, alkali metal ion) or counter ion (for example, ammonium ion). For example, a block copolymer having a sulfonic acid group in a salt form can be obtained by ion exchange by an appropriate method.

  The electrolyte laminate film of the present invention may have a film containing at least one other ion-conducting group-containing polymer in addition to the film containing the block copolymer (I) as the constituent electrolyte film. Good. Examples of such other ion conductive group-containing polymers include ionomers such as polystyrene sulfonic acid, poly (trifluorostyrene) sulfonic acid, polyvinyl sulfonic acid, polyvinyl carboxylic acid, and polyvinyl phosphonic acid; polytetrafluoroethylene, tetrafluoro Perfluorocarbon polymers such as ethylene / ethylene copolymer, tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, polyvinylidene fluoride, sulfonic acid group, phosphonic acid group and carboxyl Introducing at least one kind of group: polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, poly Examples include engineering plastics such as rylene polymers, polyaryl ketones, polyether ketones, polybenzoxazoles, polybenzthiazoles, and polyimides into which at least one of sulfonic acid groups, phosphonic acid groups, and carboxyl groups is introduced. . Polysulfone, polyethersulfone and polyetherketone as used herein are generic names for polymers having a sulfone bond, an ether bond or a ketone bond in the molecular chain. Polyetherketoneketone, polyetheretherketone, polyketone Includes ether ketone sulfone. The other ion conductive group-containing polymer may be an ion exchange resin further containing at least one of a sulfonic acid group, a phosphonic acid group, and a carboxyl group.

  As long as the effect of the present invention is not impaired, the electrolyte laminated film of the present invention is various additives such as a softening agent, a stabilizer, a light stabilizer, an antistatic agent, a release agent, a flame retardant, a foaming agent, a pigment, Dyes, brighteners, carbon fibers, inorganic fillers and the like may be contained alone or in combination of two or more.

Examples of the softener include petroleum softeners such as paraffinic, naphthenic or aromatic process oils, paraffin, vegetable oil softeners, plasticizers, and the like.
Stabilizers include phenol-based stabilizers, sulfur-based stabilizers, phosphorus-based stabilizers, and the like. Specific examples include 2,6-di-t-butyl-p-cresol, pentaerythryl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) Benzene, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2, -thio-diethylenebi [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrodinamide), 3, 5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, 3,9-bis {2- [3 Phenolic compounds such as-(3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane Stabilizer; pentaerythrityl tetrakis (3-lauryl thiopropionate), distearyl 3,3′-thiodipropionate, dilauryl 3,3′-thiodipropione And sulfur stabilizers such as dimyristyl 3,3′-thiodipropionate; trisnonylphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, diasterylpentaerythritol diphosphite, Examples thereof include phosphorus stabilizers such as bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite.
Specific examples of the inorganic filler include talc, calcium carbonate, silica, glass fiber, mica, kaolin, titanium oxide, montmorillonite, and alumina.

  From the viewpoint of ion conductivity, the content of the block copolymer (I) in the electrolyte laminated film of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass. The above is even more preferable.

  The electrolyte laminated film of the present invention preferably has a film thickness of about 5 to 500 μm from the viewpoints of performance, film strength, handling properties and the like required as an electrolyte membrane for a polymer electrolyte fuel cell. When the film thickness is less than 5 μm, the mechanical strength of the film and the gas barrier property tend to be insufficient. On the contrary, when the film thickness is thicker than 500 μm, the membrane resistance increases and sufficient proton conductivity does not appear, so that the power generation characteristics of the battery tend to be lowered. The film thickness is more preferably 11 to 300 μm, and even more preferably 15 to 80 μm.

  The thickness of the individual membranes in the electrolyte laminated membrane of the present invention is not particularly limited, but the polymer electrolyte membrane having a higher ion exchange capacity, that is, a polymer electrolyte membrane having a higher ion exchange capacity than 1.60 meq / g The thickness is preferably 2 to 20 μm, more preferably 4 to 15 μm, and the polymer electrolyte membrane having a lower ion exchange capacity, that is, the ion exchange capacity is 0.70 to 1.60 meq / g. The thickness of one layer of the polymer electrolyte membrane is preferably 3 to 40 μm, and more preferably 7 to 35 μm. Further, the ratio of the total film thickness of the polymer electrolyte membrane having a higher ion exchange capacity and the total film thickness of the polymer electrolyte film having a lower ion exchange capacity in the electrolyte laminated film of the present invention is not particularly limited, The total film thickness of the polymer electrolyte membrane having a higher ion exchange capacity) / (total film thickness of the polymer electrolyte membrane having a lower ion exchange capacity) is preferably 0.2 to 8.8, preferably 0.3 to 3.6 is more preferable.

As the method for preparing the electrolyte laminated film of the present invention, any method can be adopted as long as it is a normal method for such preparation. For example, the constituent material of the electrolyte laminated film of the present invention (block copolymer (I), the above-mentioned other ion-conducting group-containing polymer, the above-mentioned additive, etc.) is mixed with a suitable solvent, and 5% by mass. After preparing a solution or suspension of the above block copolymer or other ion-conducting group-containing polymer as described above, and then applying it to a PET film that has been subjected to a release treatment using a coater or applicator The solution coating method for obtaining an electrolyte membrane having a desired thickness by removing the solvent under appropriate conditions, the polytetrafluoroethylene sheet or the like in 5% by mass or less of the block copolymer (I) or the above-mentioned After casting a solution or suspension of another ion-conducting group-containing polymer, the solvent is gradually removed over 1 to several days to obtain an electrolyte membrane having a desired thickness. Stroke method, a method of forming a film using a known method such as hot press molding, roll molding, extrusion molding, etc. can be used, but from the viewpoint of easily preparing an electrolyte membrane having good strength and flexibility, A solution coating method is preferably used.
In order to obtain an electrolyte laminated film using any one of the above film forming methods, another layer may be formed on the electrolyte film layer obtained by the above film forming method by any one of the above film forming methods. . Moreover, it is good also as an electrolyte laminated film by laminating | stacking a plurality of electrolyte membranes obtained by any one of the said film-forming methods, and crimping | bonding and laminating by hot roll shaping | molding etc.

  The solvent used at this time is not particularly limited as long as it can prepare a solution having a viscosity that allows solution coating without destroying the structure of the block copolymer (I). Specifically, halogenated hydrocarbons such as methylene chloride, aromatic hydrocarbons such as toluene, xylene, and benzene, linear aliphatic hydrocarbons such as hexane and heptane, and cyclic aliphatic carbonization such as cyclohexane. Examples thereof include ethers such as hydrogen and tetrahydrofuran, alcohols such as methanol, ethanol, propanol, isopropanol, butanol and isobutyl alcohol, or mixed solvents thereof. Depending on the composition of the block copolymer (I), the molecular weight, the ion exchange capacity, etc., one or a combination of two or more of the above-exemplified solvents can be appropriately selected and used. From the viewpoint of easy preparation of an electrolyte membrane having sufficient strength and flexibility, a mixed solvent of toluene and isobutyl alcohol, a mixed solvent of toluene and isopropyl alcohol, a mixed solvent of cyclohexane and isopropyl alcohol, a mixed solvent of cyclohexane and isobutyl alcohol, a tetrahydrofuran solvent A mixed solvent of tetrahydrofuran and methanol is preferable, and a mixed solvent of toluene and isobutyl alcohol and a mixed solvent of toluene and isopropyl alcohol are particularly preferable.

  In addition, the solvent removal conditions in the solution coating method are arbitrarily selected as long as the conditions are such that the ion conductive groups such as sulfonic acid groups of the block copolymer (I) can be removed and the solvent can be completely removed. Is possible. In order to express desired physical properties, a plurality of temperatures may be arbitrarily combined, or a combination of ventilation and vacuum may be arbitrarily combined. Specifically, a method of removing the solvent by hot air drying at about 60 to 100 ° C. over 4 minutes, a method of removing the solvent in 2 to 4 minutes by hot air drying at about 100 to 140 ° C., After pre-drying at about 25 ° C. for about 1 to 3 hours and then drying with hot air drying at about 100 ° C. for several minutes, or after pre-drying at about 25 ° C. for about 1 to 3 hours, 25 Examples include a method of drying for about 1 to 12 hours by vacuum drying in an atmosphere of about 40 ° C. From the viewpoint of easy preparation of an electrolyte membrane having good strength and flexibility, a method of removing the solvent over 4 minutes or more by hot air drying at about 60 to 100 ° C., or about 1 to 3 hours at about 25 ° C. After drying, it is dried by hot air drying at about 100 ° C. over several minutes, or after preliminary drying at about 25 ° C. for about 1 to 3 hours, and then vacuum drying in an atmosphere of about 25-40 ° C. For example, a method of drying for about 1 to 12 hours is preferably used.

  Next, a membrane-electrode assembly using the electrolyte laminate film of the present invention will be described. The production of the membrane-electrode assembly is not particularly limited, and a known method can be applied. For example, a catalyst paste containing an ion conductive binder is applied on the gas diffusion layer by a printing method or a spray method and dried. Forming a joined body of the catalyst layer and the gas diffusion layer, and then joining the pair of joined bodies to each side of the electrolyte laminated film by hot pressing, etc. Is applied to both sides of the electrolyte laminated film by a printing method or a spray method, dried to form a catalyst layer, and a gas diffusion layer is pressure-bonded to each catalyst layer by hot pressing or the like. As another manufacturing method, a solution or suspension containing an ion conductive binder is applied to both surfaces of the electrolyte laminated film and / or the catalyst layer surface of a pair of gas diffusion electrodes, and the electrolyte laminated film and the catalyst layer surface are bonded together. There is a method of joining by thermocompression bonding. In this case, the solution or suspension may be applied to either the electrolyte membrane or the catalyst layer surface, or may be applied to both. As another manufacturing method, first, the catalyst paste is applied to a base film made of polytetrafluoroethylene (PTFE) and dried to form a catalyst layer, and then a pair of base films on the base film is formed. The catalyst layer is transferred to both sides of the electrolyte laminate film by thermocompression bonding, and the base film is peeled to obtain a joined body of the electrolyte laminate film and the catalyst layer, and the gas diffusion layer is crimped to each catalyst layer by hot pressing. There is a way. In these methods, an ion conductive group may be in a salt state with a metal such as Na, and a treatment for returning to a proton type by acid treatment after bonding may be performed.

  Examples of the ion conductive binder constituting the membrane-electrode assembly include existing perfluorosulfones such as “Nafion” (registered trademark, manufactured by DuPont) and “Gore-select” (registered trademark, manufactured by Gore). An ion conductive binder made of an acid polymer, an ion conductive binder made of sulfonated polyethersulfone or sulfonated polyetherketone, an ion conductive binder made of polybenzimidazole impregnated with phosphoric acid or sulfuric acid can be used. . Moreover, you may produce an ion conductive binder from the block copolymer (I) which comprises the electrolyte laminated film of this invention. In order to further enhance the adhesion between the electrolyte laminated film and the gas diffusion electrode, it is preferable to use an ion conductive binder formed of the same material as the constituent electrolyte film on the surface in close contact with the gas diffusion electrode.

  The constituent material of the catalyst layer of the membrane-electrode assembly is not particularly limited as the conductive material / catalyst support, and examples thereof include carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black, and acetylene black, activated carbon, graphite, and the like. These may be used alone or in combination of two or more. The catalyst metal may be any metal that promotes the oxidation reaction of fuel such as hydrogen and methanol and the reduction reaction of oxygen, such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, Cobalt, nickel, chromium, tungsten, manganese, palladium, etc., or alloys thereof, for example, platinum-ruthenium alloys are mentioned. Of these, platinum and platinum alloys are often used. The particle size of the metal serving as a catalyst is usually 10 to 300 angstroms. When these catalysts are supported on a conductive material such as carbon / catalyst support, the amount of catalyst used is small and it is advantageous in terms of cost. The catalyst layer may contain a water repellent as necessary. Examples of the water repellent include various thermoplastic resins such as polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene copolymer, and polyether ether ketone.

  The gas diffusion layer of the membrane-electrode assembly is made of a material having conductivity and gas permeability, and examples of such a material include porous materials made of carbon fibers such as carbon paper and carbon cloth. Moreover, in order to improve water repellency, this material may be subjected to water repellency treatment.

A polymer electrolyte fuel obtained by inserting the membrane-electrode assembly obtained by the above-described method between a conductive separator material that also serves as a gas supply flow path to the electrode and the electrode chamber separation. A battery is obtained. The membrane-electrode assembly of the present invention uses a pure hydrogen type using hydrogen as a fuel gas, a methanol reforming type using hydrogen obtained by reforming methanol, and hydrogen obtained by reforming natural gas. Natural gas reforming type, gasoline reforming type using hydrogen obtained by reforming gasoline, direct methanol type using methanol directly, etc. can be used as a membrane-electrode assembly for polymer electrolyte fuel cells. is there.
The electrolyte laminated film, membrane-electrode assembly and polymer electrolyte fuel cell of the present invention are economical, environmentally friendly, and have both high dimensional stability and high ionic conductivity under low humidity. Can exhibit high output characteristics and can also exhibit excellent durability.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited by these Examples.

Reference example 1
Production of block copolymer comprising poly α-methylstyrene (polymer block (A)) and hydrogenated polybutadiene (polymer block (B)) In the same manner as the previously reported method (WO 02/40611), A poly α-methylstyrene-b-polybutadiene-b-polyα-methylstyrene type triblock copolymer (hereinafter abbreviated as mSBmS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained mSBmS is 78000, the 1,4-bond content determined from ¹ H-NMR measurement is 55%, and the content of α-methylstyrene unit is 28.0. It was mass%. Further, it was found by composition analysis by ¹ H-NMR spectrum measurement that α-methylstyrene was not substantially copolymerized in the polybutadiene block.
Prepare a synthesized cyclohexane solution of mSBmS, charge it into a pressure-resistant vessel that has been sufficiently purged with nitrogen, and then use a Ni / Al Ziegler-type hydrogenation catalyst for 5 hours at 80 ° C. in a hydrogen atmosphere. To obtain a poly α-methylstyrene-b-hydrogenated polybutadiene-b-polyα-methylstyrene type triblock copolymer (hereinafter abbreviated as mSEBmS). When the hydrogenation rate of the obtained mSEBmS was calculated by ¹ H-NMR spectrum measurement, it was 99.3% and the residual double bond ratio was 0.7%.

Reference example 2
Production of block copolymer consisting of polystyrene (polymer block (A2)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (A1)) In a 1400 mL autoclave Then, 819 ml of dehydrated cyclohexane and 1.71 ml of sec-butyllithium (1.25 M-cyclohexane solution) were charged, and then 19.8 ml of 4-tert-butylstyrene and 27.7 ml of styrene were successively added and polymerized successively at 50 ° C. Then, 80.4 ml of isoprene, 26.6 ml of styrene, and 18.1 ml of 4-tert-butylstyrene were successively added and polymerized successively at 60 ° C. to thereby obtain poly (4-tert-butylstyrene) -b-polystyrene- b-polyisoprene-b-polystyrene-b-poly ( 4-tert-butylstyrene) (hereinafter abbreviated as tBSSIStBS) was synthesized, and the number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS was 86050, which was obtained from ¹ H-NMR measurement. -Bond amount was 94.0%, styrene unit content was 32.9% by mass, and 4-tert-butylstyrene unit content was 29.8% by mass.
After preparing a cyclohexane solution of the synthesized tBSSIStBS and charging it in a pressure vessel sufficiently purged with nitrogen, a hydrogenation reaction was performed at 70 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. To obtain poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (hereinafter abbreviated as tBSSEPStBS). . The hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement and found to be 99.9%.

Reference example 3
Production of block copolymer comprising polystyrene (polymer block (A2)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (A1)) 1L autoclave To this, 578 ml of dehydrated cyclohexane and 1.78 ml of sec-butyllithium (1.15 M-cyclohexane solution) were charged, and then 32.2 ml of 4-tert-butylstyrene, 13.5 ml of styrene, 81.6 ml of isoprene, and 13.5 ml of styrene. , And 32.2 ml of 4-tert-butylstyrene, and successively polymerized at 50 ° C., thereby poly (4-tert-butylstyrene) -b-polystyrene-b-polyisoprene-b-polystyrene-b— Poly (4-tert-butylstyrene) (tBSSISt BS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS is 103600, the 1,4-bond content determined from ¹ H-NMR measurement is 94.0%, and the content of styrene units is 17.0 mass. %, 4-tert-butylstyrene unit content was 41.0% by mass.
A cyclohexane solution of synthesized tBSSIStBS was prepared and charged into a pressure-resistant vessel that had been sufficiently purged with nitrogen. Then, a hydrogenation reaction was performed at 50 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. And poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (tBSSEPStBS) was obtained. The hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement and found to be 99.9%.

Reference example 4
Production of block copolymer comprising polystyrene (polymer block (A2)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (A1)) 1400 mL autoclave Into this, 820 ml of dehydrated cyclohexane and 1.56 ml of sec-butyllithium (1.25 M-cyclohexane solution) were added, and then 18.1 ml of 4-tert-butylstyrene and 29.2 ml of styrene were successively added, and polymerization was successively performed at 50 ° C. And then sequentially adding 80.4 ml of isoprene, 28.1 ml of styrene, and 16.6 ml of 4-tert-butylstyrene, followed by sequential polymerization at 60 ° C. to obtain poly (4-tert-butylstyrene) -b-polystyrene. -B-polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (tBSSIStBS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS is 38910, the 1,4-bond content determined from ¹ H-NMR measurement is 94.0%, and the content of styrene units is 37.5 mass. %, 4-tert-butylstyrene unit content was 22.0% by mass.
After preparing a cyclohexane solution of the synthesized tBSSIStBS and charging it in a pressure vessel sufficiently purged with nitrogen, a hydrogenation reaction was performed at 70 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. And poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (tBSSEPStBS) was obtained. The hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement and found to be 99.9%.

Reference Example 5
Production of block copolymer comprising polystyrene (polymer block (A2)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (A1)) 1400 mL autoclave To the mixture, 576 ml of dehydrated cyclohexane and 1.86 ml of sec-butyllithium (1.15 M-cyclohexane solution) were added, and then 24.0 ml of 4-tert-butylstyrene and 19.8 ml of styrene were sequentially added, followed by sequential polymerization at 50 ° C. And then sequentially adding 101.0 ml of isoprene, 19.7 ml of styrene and 23.8 ml of 4-tert-butylstyrene and polymerizing sequentially at 60 ° C. to obtain poly (4-tert-butylstyrene) -b-polystyrene. -B-polyisoprene-b-polystyrene-b-po Li (4-tert-butylstyrene) (tBSSIStBS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS is 113960, the 1,4-bond content determined from ¹ H-NMR measurement is 93.8%, and the content of styrene units is 24.2 mass. %, 4-tert-butylstyrene unit content was 27.6% by mass.
After preparing a cyclohexane solution of the synthesized tBSSIStBS and charging it in a pressure vessel sufficiently purged with nitrogen, a hydrogenation reaction was performed at 70 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. And poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (tBSSEPStBS) was obtained. The hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement and found to be 99.8%.

Reference Example 6
Production of block copolymer comprising polystyrene (polymer block (A2)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (A1)) 1400 mL autoclave To the mixture, 576 ml of dehydrated cyclohexane and 1.58 ml of sec-butyllithium (1.15 M-cyclohexane solution) were added, and then 28.7 ml of 4-tert-butylstyrene and 8.7 ml of styrene were sequentially added, followed by sequential polymerization at 50 ° C. And then sequentially adding 81.6 ml of isoprene, 8.0 ml of styrene, and 28.3 ml of 4-tert-butylstyrene, and sequentially polymerizing at 60 ° C. to obtain poly (4-tert-butylstyrene) -b-polystyrene. -B-polyisoprene-b-polystyrene-b-poly (4 -Tert-butylstyrene) (tBSSIStBS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS is 109570, the 1,4-bond content determined from ¹ H-NMR measurement is 93.8%, and the content of styrene units is 10.9 mass. %, 4-tert-butylstyrene unit content was 42.8% by mass.
After preparing a cyclohexane solution of the synthesized tBSSIStBS and charging it in a pressure vessel sufficiently purged with nitrogen, a hydrogenation reaction was performed at 70 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. And poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (tBSSEPStBS) was obtained. The hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement and found to be 99.9%.

Production Example 1
(1) Synthesis of sulfonated mSEBmS 70 g of the block copolymer (mSEBmS) obtained in Reference Example 1 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour and then purged with nitrogen, and then 563 ml of methylene chloride. And dissolved by stirring at room temperature. After dissolution, a sulfonation reagent obtained by reacting 162 ml of acetic anhydride and 122 ml of sulfuric acid at 0 ° C. in 385.0 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring at room temperature for 72 hours, 30 ml of distilled water as a stopper was added. Thereafter, 1.2 L of distilled water was slowly poured into the polymer solution with stirring to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.2 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and the polymer collected at the end was vacuum-dried to obtain sulfonated mSEBmS. The sulfonation rate of the benzene ring of the α-methylstyrene unit of the obtained sulfonated mSEBmS was 99.9 mol% from ¹ H-NMR analysis, and the ion exchange capacity was 1.91 meq / g.

Production Example 2
Synthesis of Sulfonated mSEBmS 70 g of the block copolymer (mSEBmS) obtained in Reference Example 1 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour and then purged with nitrogen, after which 563 ml of methylene chloride was added, Stir at room temperature to dissolve. After dissolution, a sulfonation reagent obtained by reacting 51.7 ml of acetic anhydride and 39.0 ml of sulfuric acid at 0 ° C. in 123.0 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring for 4 hours at 35 ° C., 10 ml of distilled water as a stopper was added. Thereafter, 1.3 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.3 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated SEBS. The sulfonation rate of the benzene ring of the α-methylstyrene unit of the obtained sulfonated mSEBmS was 72.0 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated mSEBmS was 1.44 meq / g.

Production Example 3
Synthesis of Sulfonated mSEBmS 70 g of the block copolymer (mSEBmS) obtained in Reference Example 1 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour and then purged with nitrogen, after which 563 ml of methylene chloride was added, Stir at room temperature to dissolve. After dissolution, a sulfonating reagent obtained by reacting 12.9 ml of acetic anhydride and 9.8 ml of sulfuric acid at 0 ° C. in 31.0 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring for 4 hours at 35 ° C., 10 ml of distilled water as a stopper was added. Thereafter, 1.3 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.3 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated SEBS. The sulfonation rate of the benzene ring of the α-methylstyrene unit of the obtained sulfonated mSEBmS was 22.5 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated mSEBmS was 0.49 meq / g.

Production Example 4
Synthesis of Sulfonated tBSSEPStBS 40 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 2 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour, and after replacing with nitrogen, 500 ml of methylene chloride was added. Stir at room temperature to dissolve. After dissolution, a sulfonation reagent obtained by reacting 73.7 ml of acetic anhydride and 33.0 ml of sulfuric acid at 0 ° C. in 147.5 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring at room temperature for 72 hours, 20 ml of distilled water as a stopper was added. Thereafter, 0.7 L of distilled water was slowly poured into the polymer solution to coagulate and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.3 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated tBSSEPStBS. From the ¹ H-NMR analysis, the sulfonation rate of the benzene ring of the styrene unit in the obtained sulfonated tBSSEPStBS was 100 mol%, and the ion exchange capacity of the sulfonated tBSSEPStBS was 2.50 meq / g.

Production Example 5
Synthesis of Sulfonated tBSSEPStBS 50 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 3 was vacuum-dried for 1 hour in a glass reaction vessel equipped with a stirrer, and after replacing with nitrogen, 500 ml of methylene chloride was added. The mixture was dissolved by stirring at room temperature of 25 ° C. for 2 hours. After dissolution, a sulfonating reagent obtained by reacting 31.9 ml of acetic anhydride and 14.2 ml of sulfuric acid at 0 ° C. in 63.7 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring at room temperature for 72 hours, 10 ml of distilled water as a stopper was added. Thereafter, 1.0 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.0 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated tBSSEPStBS. The sulfonation rate of the benzene ring of the styrene unit of the obtained sulfonated tBSSEPStBS was 99 mol% from ¹ H-NMR analysis, and the ion exchange capacity was 1.47 meq / g.

Production Example 6
Synthesis of Sulfonated tBSSEPStBS 40 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 4 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour, and after replacing with nitrogen, 584 ml of methylene chloride was added. Stir at room temperature to dissolve. After dissolution, a sulfonating reagent obtained by reacting 86.1 ml of acetic anhydride and 38.5 ml of sulfuric acid at 0 ° C. in 172.2 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring at room temperature for 72 hours, 20 ml of distilled water as a stopper was added. Thereafter, 1.0 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.0 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated tBSSEPStBS. The sulfonation rate of the benzene ring of the styrene unit in the obtained sulfonated tBSSEPStBS was 99.6 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated tBSSEPStBS was 2.80 meq / g.

Production Example 7
Synthesis of Sulfonated tBSSEPStBS 50 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 5 was vacuum-dried for 1 hour in a glass reaction vessel equipped with a stirrer, and after replacing with nitrogen, 360 ml of methylene chloride was added. Stir at room temperature to dissolve. After dissolution, a sulfonation reagent obtained by reacting 74.3 ml of acetic anhydride and 33.2 ml of sulfuric acid at 0 ° C. in 148.7 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring for 72 hours at room temperature, 15 ml of stop water distilled water was added. Thereafter, 1.0 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 1.0 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated tBSSEPStBS. The sulfonation rate of the benzene ring of the styrene unit in the obtained sulfonated tBSSEPStBS was 97 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated tBSSEPStBS was 1.89 meq / g.

Production Example 8
Synthesis of Sulfonated tBSSEPStBS 20 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 6 was vacuum-dried in a glass reaction vessel equipped with a stirrer for 1 hour and then purged with nitrogen. Then, 176 ml of methylene chloride was added, Stir at room temperature to dissolve. After dissolution, a sulfonating reagent obtained by reacting 13.0 ml of acetic anhydride and 5.8 ml of sulfuric acid at 0 ° C. in 26.0 ml of methylene chloride was gradually added dropwise over 5 minutes. After stirring for 72 hours at room temperature, 5 ml of distilled water as a stopper was added. Thereafter, 0.8 L of distilled water was slowly poured into the polymer solution to solidify and precipitate the polymer. The methylene chloride was removed by distillation at atmospheric pressure, followed by filtration. The solid content obtained by filtration was transferred to a beaker, 0.8 L of distilled water was added, and washing was performed with stirring, followed by filtration and recovery. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and finally the polymer collected by filtration was vacuum dried to obtain sulfonated tBSSEPStBS. The sulfonation rate of the benzene ring of the styrene unit of the obtained sulfonated tBSSEPStBS was 51.3 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated tBSSEPStBS was 0.52 meq / g.

Example 1
(1) Preparation of electrolyte laminated film A 16% by mass toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.50 meq / g) obtained in Production Example 4 was prepared and separated. The first layer is formed by coating the PET film [Toyobo Ester Film K1504] manufactured by Toyobo Co., Ltd. with a thickness of about 75 μm and drying in a hot air dryer at 100 ° C. for 4 minutes. A film (A) having a thickness of 8 μm was obtained.
Next, a 14% by mass toluene / isobutyl alcohol (mass ratio 75/25) solution of the sulfonated tBSSEPStBS (ion exchange capacity 1.47 meq / g) obtained in Production Example 5 was prepared, and about The film was coated with a thickness of 200 μm and dried at 100 ° C. for 4 minutes with a hot air dryer to form a second layer, whereby a 22 μm thick laminated film (B) was obtained.
Next, a 16% by mass toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.50 meq / g) obtained in Production Example 4 was prepared, and the solution was formed on the laminated membrane (B). The film was coated with a thickness of about 100 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to form a third layer, whereby a 29 μm thick laminated film (C) was obtained.
(2) Production of single cell for polymer electrolyte fuel cell An electrode for a polymer electrolyte fuel cell was produced by the following procedure. A 10% by weight aqueous dispersion of Nafion in Pt-Ru alloy catalyst-carrying carbon is added and mixed so that the mass ratio of Pt-Ru alloy catalyst-carrying carbon and Nafion is 1: 1, and the paste is uniformly dispersed. Was prepared. This paste was uniformly applied to one side of the carbon paper. The electrode for anode was produced by drying at 130 ° C. for 30 minutes. Further, a 10% by mass solution of Nafion is added to and mixed with Pt catalyst-carrying carbon so that the mass ratio of Pt catalyst-carrying carbon and Nafion is 1: 0.75 to prepare a uniformly dispersed paste. A cathode electrode was prepared in the same manner as the anode side. The electrolyte laminate film prepared in (1) is sandwiched between the two types of electrodes so that the membrane and the catalyst face each other, and the outside is sandwiched between two heat-resistant films and two stainless steel plates in order, and hot pressing is performed. A membrane-electrode assembly was produced by (130 ° C., 20 kg / cm 2, 8 min). Next, the membrane-electrode assembly produced is sandwiched between two conductive separators that also serve as gas supply channels, and the outside is sandwiched between two current collector plates and two clamping plates. An evaluation cell for a molecular fuel cell was produced.

Example 2
(1) Preparation of electrolyte laminated membrane A 7% by mass toluene / isobutyl alcohol (mass ratio 6/4) solution of the sulfonated mSEBmS (ion exchange capacity 1.91 meq / g) obtained in Production Example 1 was prepared and separated. The first layer is formed by coating the PET film [Toyobo Co., Ltd. “Toyobo Ester Film K1504”] with a thickness of about 150 μm and drying with a hot air dryer at 100 ° C. for 4 minutes. A film (A) having a thickness of 6 μm was obtained.
Next, a 14% by mass toluene / isobutyl alcohol (mass ratio 7/3) solution of the sulfonated mSEBmS (ion exchange capacity 1.44 meq / g) obtained in Production Example 2 was prepared, and about The film was coated at a thickness of 275 μm, and dried at 100 ° C. for 4 minutes with a hot air dryer to form a second layer, whereby a 35 μm thick laminated film (B) was obtained.
Next, a 7% by mass toluene / isobutyl alcohol (mass ratio 6/4) solution of the sulfonated mSEBmS (ion exchange capacity 1.91 meq / g) obtained in Production Example 1 was prepared, and the solution was formed on the laminated film (B). The film was coated with a thickness of about 200 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to form a third layer, thereby obtaining a laminated film (C) having a thickness of 41 μm.
(2) Production of a single cell for a polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained laminated film was used. did.

Example 3
(1) Preparation of electrolyte laminated film A 14% by mass toluene / isobutyl alcohol (mass ratio 75/25) solution of the sulfonated tBSSEPStBS (ion exchange capacity 1.47 meq / g) obtained in Production Example 5 was prepared and separated. Form-treated PET film [Toyobo Co., Ltd. “Toyobo Ester Film K1504”] is coated with a thickness of about 100 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to form the first layer. A film (A) having a thickness of 8 μm was obtained.
Next, a 16% by mass toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.50 meq / g) obtained in Production Example 4 was prepared, and about The film was coated with a thickness of 150 μm, and dried at 100 ° C. for 4 minutes with a hot air dryer to form a second layer, thereby obtaining a laminated film (B) having a thickness of 24 μm.
Next, a 14% by mass toluene / isobutyl alcohol (mass ratio 75/25) solution of the sulfonated tBSSEPStBS (ion exchange capacity 1.47 meq / g) obtained in Production Example 5 was prepared, and the electrolyte laminated membrane (B) was The film was coated at a thickness of about 100 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to form a third layer, thereby obtaining an electrolyte laminated film (C) having a thickness of 32 μm.
(2) Production of a single cell for a polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained laminated film was used. did.

Comparative Example 1
(1) Production of electrolyte membrane for polymer electrolyte fuel cell 18% by mass toluene / isopropyl alcohol (mass ratio 5/5) solution of sulfonated tBSSEPStBS (ion exchange capacity 2.50 meq / g) obtained in Production Example 4 A 30 μm thick film was obtained by coating with a thickness of about 350 μm on a PET film [Toyobo “Toyobo Ester Film K1504” manufactured by Toyobo Co., Ltd.] and drying at 100 ° C. for 4 minutes. It was.
(2) Production of single cell for polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained membrane was used. .

Comparative Example 2
(1) Preparation of electrolyte membrane A 17% by mass toluene / isobutyl alcohol (mass ratio 75/25) solution of the sulfonated tBSSEPStBS (ion exchange capacity 1.47 meq / g) obtained in Production Example 5 was prepared and released. A coated PET film [“Toyobo Ester Film K1504” manufactured by Toyobo Co., Ltd.] is coated with a thickness of about 300 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to obtain a film having a thickness of 30 μm. It was.
(2) Production of single cell for polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained membrane was used. .

Comparative Example 3
(1) Production of electrolyte membrane A 6% by mass toluene / isobutyl alcohol (mass ratio 6/4) solution of the sulfonated mSEBmS (ion exchange capacity 1.91 meq / g) obtained in Production Example 1 was prepared and released. A treated PET film [“Toyobo Ester Film K1504” manufactured by Toyobo Co., Ltd.] is coated with a thickness of about 250 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to obtain a film having a thickness of 11 μm. It was. On the obtained film, a film having a thickness of 29 μm was obtained by applying it twice in the same manner.
(2) Production of single cell for polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained membrane was used. .

Comparative Example 4
(1) Preparation of electrolyte membrane A 14% by mass toluene / isobutyl alcohol (mass ratio 7/3) solution of the sulfonated mSEBmS (ion exchange capacity 1.44 meq / g) obtained in Production Example 2 was prepared and released. A coated PET film [“Toyobo Ester Film K1504” manufactured by Toyobo Co., Ltd.] is coated at a thickness of about 275 μm and dried in a hot air dryer at 100 ° C. for 4 minutes to obtain a film having a thickness of 29 μm. It was.
(2) Production of single cell for polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained membrane was used. .

Comparative Example 5
(1) Production of electrolyte laminated film A 12.5 mass% toluene / isobutyl alcohol (mass ratio 7/3) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.80 meq / g) obtained in Production Example 6 was prepared. The first layer was formed by coating with a thickness of about 75 μm on a PET film [Toyobo Co., Ltd. “Toyobo Ester Film K1504”] having been subjected to a release treatment, and dried at 100 ° C. for 4 minutes to form a first layer having a thickness of 7 μm. The electrolyte membrane (A) was obtained.
Next, a 19% by mass toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.50 meq / g) obtained in Production Example 4 was prepared, and the solution was applied on the electrolyte membrane (A). The film was coated at a thickness of about 275 μm and dried at 100 ° C. for 4 minutes to form a second layer, thereby obtaining an electrolyte laminated film (B) having a thickness of 37 μm.
Subsequently, a 12.5 mass% toluene / isobutyl alcohol (mass ratio 7/3) solution of the sulfonated tBSSEPStBS (ion exchange capacity 2.80 meq / g) obtained in Production Example 6 was prepared, and an electrolyte laminated film (B ) Was coated at a thickness of about 100 μm and dried at 100 ° C. for 4 minutes to form a third layer, thereby obtaining an electrolyte laminated film (C) having a thickness of 43 μm.
(2) Production of a single cell for a polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained laminated film was used. did.

Comparative Example 6
Production of electrolyte laminated membrane for solid oxide fuel cell 12.5 mass% toluene / isobutyl alcohol (mass ratio 7/3) solution of sulfonated tBSSEPStBS (ion exchange capacity 1.89 meq / g) obtained in Production Example 7 The first layer is formed by coating with a thickness of about 100 μm on a PET film [Toyobo “Toyobo Ester Film K1504”, manufactured by Toyobo Co., Ltd.], and drying at 100 ° C. for 4 minutes. An electrolyte membrane (A) having a thickness of 8 μm was obtained.
Next, a 16% by mass toluene / isobutyl alcohol (mass ratio 8/2) solution of the sulfonated tBSSEPStBS (ion exchange capacity 0.52 meq / g) obtained in Production Example 8 was prepared, and the solution was applied on the electrolyte membrane (A). The film was coated at a thickness of about 250 μm and dried at 100 ° C. for 4 minutes to form a second layer, thereby obtaining an electrolyte laminated film (B) having a thickness of 37 μm.
Next, a 12.5% by mass toluene / isobutyl alcohol (mass ratio 7/3) solution of the sulfonated tBSSEPStBS (ion exchange capacity 1.89 meq / g) obtained in Production Example 7 was prepared, and an electrolyte laminated film (B ) Was coated at a thickness of about 125 μm and dried at 100 ° C. for 4 minutes to form a third layer, thereby obtaining an electrolyte laminated film (C) having a thickness of 44 μm.
(2) Production of a single cell for a polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained laminated film was used. did.

Comparative Example 7
(1) Preparation of electrolyte laminated membrane A 7% by mass toluene / isobutyl alcohol (mass ratio 6/4) solution of the sulfonated mSEBmS (ion exchange capacity 1.91 meq / g) obtained in Production Example 1 was prepared and separated. The first layer is formed by coating the PET film [Toyobo Co., Ltd. “Toyobo Ester Film K1504”] with a thickness of about 150 μm and drying with a hot air dryer at 100 ° C. for 4 minutes. An electrolyte membrane (A) having a thickness of 6 μm was obtained.
Next, a 14% by mass toluene / isobutyl alcohol (mass ratio 8/2) solution of the sulfonated mSEBmS (ion exchange capacity 0.49 meq / g) obtained in Production Example 3 was prepared, and the solution was applied on the electrolyte membrane (A). The coating was applied at a thickness of about 275 μm, and dried at 100 ° C. for 4 minutes in a hot air dryer to form a second layer, thereby obtaining an electrolyte laminated film (B) having a thickness of 35 μm.
Next, a 7% by mass toluene / isobutyl alcohol (mass ratio 6/4) solution of the sulfonated mSEBmS (ion exchange capacity 1.91 meq / g) obtained in Production Example 1 was prepared, and the electrolyte laminated membrane (B) was Was coated with a thickness of about 200 μm, and dried in a hot air dryer at 100 ° C. for 4 minutes to form a third layer, thereby obtaining an electrolyte laminated film (C) having a thickness of 41 μm.
(2) Production of a single cell for a polymer electrolyte fuel cell An evaluation cell for a polymer electrolyte fuel cell was produced under the same conditions as in Example 1- (2) except that the obtained laminated film was used. did.

Performance Tests and Results of Polymer Membranes of Examples and Comparative Examples Membranes prepared from the sulfonated block copolymers obtained in the respective Examples or Comparative Examples were used as samples in the following tests 1) to 2). did.

1) Measurement of linear expansion coefficient After immersing a sample of 1 cm x 4 cm in distilled water for 4 hours, the length (b) in the longitudinal direction was measured and calculated by the following formula.
Linear expansion coefficient (%) = (b-4) / 4 × 100

2) Power generation test of single cell for fuel cell (Test method 1)
Hydrogen was used as the fuel and oxygen was used as the oxidant. The supply conditions of hydrogen were stoichiometric 1.5 and humidification 30% R.V. H. The oxygen supply conditions were stoichiometric 2.0 and humidification 30% R.V. H, set the cell temperature to 70 ° C., set the evaluation cells created in the examples and comparative examples, and then perform a power generation test without pretreatment, when the current density is 0.2 A / cm ² The voltage value of was evaluated.
(Test method 2)
Hydrogen was used as the fuel and air was used as the oxidant. The supply conditions of hydrogen were stoichiometric 1.5 and humidification 30% R.V. H. The air supply conditions were oxygen equivalent stoichiometric 2.0 and humidification 30% R.V. H and the cell temperature was 80 ° C. After setting the evaluation cells created in the examples and comparative examples, once aged with full humidification, a power generation test was carried out after sufficiently flowing 30% humidified gas, and the current density was 0.4 A / cm ² The voltage value of was evaluated.

  The results of the performance test are shown in Table 1.

As can be seen from the comparison between Example 1 and Comparative Examples 1 and 2 and the comparison between Example 2 and Comparative Examples 3 and 4, the laminated films of Examples 1 and 2 were kept relative to each other while the linear expansion coefficient was suppressed. It was confirmed that excellent power generation performance was exhibited even at a humidity of 30%. Further, as can be seen from Comparative Example 5, the electrolyte laminated film composed of the electrolyte membrane having an ion exchange capacity larger than 1.6 shows excellent power generation performance even under a relative humidity of 30%, but the linear expansion coefficient. Becomes higher. As can be seen from Comparative Example 6, in the electrolyte laminated film composed of the electrolyte membrane having an ion exchange capacity larger than 1.6 and the electrolyte membrane having an ion exchange capacity smaller than 0.7, although the linear expansion coefficient is suppressed, It was difficult to conduct a power generation test at a relative humidity of 30%. As can be seen from Comparative Example 7, in the electrolyte laminated film including the electrolyte membrane having an ion exchange capacity smaller than 0.7, the linear expansion coefficient is suppressed, but it is difficult to perform the power generation test under a relative humidity of 30%. there were.
Further, from the comparison between Example 1 and Example 3, when the electrolyte membrane having a high ion exchange capacity is arranged on the side in contact with the electrode, the electrolyte membrane having a low ion exchange capacity is arranged on the side in contact with the electrode. Compared with the case where it was made to show, the power generation performance was excellent.

  From the results of the above various performance tests, the polymer electrolyte laminated film of the present invention can obtain high output characteristics even under low humidity in addition to high dimensional stability. In addition, since excellent bondability with the electrode is also excellent, it can be said that the durability of the membrane-electrode assembly and the polymer electrolyte fuel cell using the same is also excellent.

Claims (15)

  An electrolyte laminate film comprising at least two polymer electrolyte membranes laminated as a constituent electrolyte membrane, wherein at least one of the polymer electrolyte membranes has an ion exchange capacity higher than 1.60 meq / g, and Polymer block (A) in which at least one of the molecular electrolyte membranes has an ion exchange capacity of 0.70 to 1.60 meq / g, and at least one of the constituent electrolyte membranes has an ion conductive group, and a flexible polymer block An electrolyte laminate film comprising a block copolymer (I) having (B) as a constituent component.   The electrolyte laminated film according to claim 1, wherein at least two of the constituent electrolyte films contain a block copolymer (I).   At least one of the constituent electrolyte membranes containing the block copolymer (I) has an ion exchange capacity higher than 1.60 meq / g, and at least one of the constituent electrolyte membranes containing the block copolymer (I) The electrolyte laminated film according to claim 2, wherein one has an ion exchange capacity of 0.70 to 1.60 meq / g.   The electrolyte laminate film is formed by laminating at least three polymer electrolyte membranes as the constituent electrolyte membrane, and the two constituent electrolyte membranes constituting the outermost layer of the electrolyte laminate membrane both have an ion exchange capacity higher than 1.60 meq / g. The electrolyte laminated film according to claim 1, which is a polymer electrolyte film having   The electrolyte laminated film according to claim 1, wherein the polymer block (A) is a polymer block having an aromatic vinyl compound unit as a main repeating unit.   The electrolyte laminated film according to claim 5, wherein a ratio of the aromatic vinyl compound unit in the polymer block (A) is 50% by mass or more.   The said polymer block (A) consists of a restraint block (A1) which does not have an ion conductive group substantially, and functions as a restraint phase, and an ion conductive block (A2) which has an ion conductive group. Electrolyte laminated film. In the polymer block (A), the constraining block (A1) is represented by the following general formula (a):

(Wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{2 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, at least one of which is carbon (Representing an alkyl group of 1 to 8) as a main repeating unit, the ion conductive block (A2) is represented by the following general formula (b).

(In the formula, Ar ¹ represents an aryl group having 6 to 14 carbon atoms which may have ¹ to 3 substituents, and R ⁵ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or 1 to 3). The electrolyte laminate according to claim 7, which is a polymer block having an aromatic vinyl compound unit represented by (optionally represented by an aryl group having 6 to 14 carbon atoms which may have one substituent) as a main repeating unit. film.   The polymer block (B) is an alkene unit having 2 to 8 carbon atoms, a cycloalkene unit having 5 to 8 carbon atoms, a vinylcycloalkene unit having 7 to 10 carbon atoms, a conjugated alkadiene unit having 4 to 8 carbon atoms and a carbon number. 5 to 8 conjugated cycloalkadiene units, 7 to 10 vinylcycloalkene units in which some or all of the carbon-carbon double bonds are hydrogenated, 4 to 8 conjugated alkadiene units and carbon numbers The electrolyte laminated film according to claim 1, which is a polymer block comprising at least one repeating unit selected from the group consisting of 5 to 8 conjugated cycloalkadiene units.   The polymer block (B) is an alkene unit having 2 to 8 carbon atoms, a conjugated alkadiene unit having 4 to 8 carbon atoms, and 4 to 8 carbon atoms in which a part or all of the carbon-carbon double bond is hydrogenated. The electrolyte laminate film according to claim 9, which is a polymer block comprising at least one repeating unit selected from conjugated alkadiene units.   The electrolyte laminated film according to claim 7, wherein a mass ratio of the polymer block (A1) to the polymer block (A2) is 85:15 to 20:80.   The electrolyte laminated film according to claim 1, wherein a mass ratio of the polymer block (A) and the polymer block (B) is 95: 5 to 5:95. The electrolyte laminated film according to claim 1, wherein the ion conductive group is a group represented by —SO ₃ M or —PO ₃ HM (wherein M represents a hydrogen atom, an ammonium ion, or an alkali metal ion).   A membrane-electrode assembly comprising the electrolyte laminate film according to claim 1.   A polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 14.