JP2011103176A - Electrolyte laminated film, membrane-electrode assembly, and polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: a fluorine electrolyte membrane is expensive, is high in oxygen permeability with low durability against radicals thus generated, and is high in environmental loads accompanying fluorine exhaust at manufacturing and discarding, wherein an electrolyte membrane using an engineering plastic material has low power-generating characteristics estimated by cell resistance, and especially, has low cell resistance as well as low power-generating characteristics under low humidity. <P>SOLUTION: In the electrolyte laminated film made by laminating at least two electrolyte membranes as constituents, at least one of the electrolyte membranes is one (i) mainly composed of a polymer (I) having an ion-conductive group and an aromatic ring as a main chain, and further, at least one of the electrolyte membranes is one (ii) mainly composed of a block copolymer (II) constituted of a polymer block (A) having an ionic conductive group, and a polymer block (B) not having an ion-conductive group, as a structural component. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In recent years, fuel cell technology has been counted as one of the pillars of new energy technology as a fundamental solution to energy and environmental problems. In particular, the polymer electrolyte fuel cell (PEFC) can be expected to be small and light, so it can be used for driving power sources for electric vehicles, power sources for portable devices, and household stationary devices that use electricity and heat simultaneously. Application to a wide range of applications such as power supply equipment is under consideration.

  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 a catalyst layer and a gas diffusion layer are integrated is called a gas diffusion electrode, and a structure in which a pair of gas diffusion electrodes is joined to a polymer electrolyte membrane so that the catalyst layer faces the polymer electrolyte membrane is a membrane- It is called an electrode assembly (MEA; Membrane 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 generate protons and electrons, the protons pass through the polymer electrolyte membrane, and the electrons move through an external electric circuit formed by connecting both electrodes and are sent to the oxygen electrode, where they are oxidized. Water is produced by reacting with the agent. In this way, the chemical energy of the fuel can be directly converted into electric energy and taken out.

  As a polymer electrolyte membrane used in a solid polymer fuel cell, a fluorine-based polymer electrolyte membrane has been mainly used at first (for example, Nafion (registered trademark, manufactured by DuPont)). Since the fluorine-based polymer electrolyte membrane is excellent in ionic conductivity under low humidity, a favorable output can be obtained. In addition to high mechanical strength during drying, the coefficient of linear expansion when humidified is low, the strength is maintained even when the fuel cell is turned on and off, and the strength is maintained. . However, these fluorine-based polymer electrolyte membranes have high oxygen permeability, low durability against radicals generated thereby, high environmental burdens due to fluorine discharge during production and disposal, and high cost. Therefore, alternative materials are required.

  As an alternative to a fluorine-based polymer electrolyte, a polymer electrolyte membrane comprising a polymer electrolyte in which an engineering plastic material is used as a base polymer and an ion conductive group such as a sulfonic acid group is introduced has been proposed.

  For example, a sulfonated product of polyetheretherketone (PEEK) has been proposed (see, for example, Patent Document 1). Since such a polymer electrolyte membrane does not contain fluorine, no fluorine compound is generated at the time of production and disposal of the polymer electrolyte membrane, or at the time of deterioration. Moreover, since the mechanical strength is high and the linear expansion coefficient when humidified is low, the strength and durability during use are also excellent. Furthermore, since the oxygen barrier property is high, the generation of radicals generated by the oxygen gas flowing into the fuel electrode is suppressed, and the film is hardly deteriorated. However, polymer electrolyte membranes using these materials have the problem of poor bondability with the catalyst layer.

  Thus, an electrolyte laminated film in which a polymer electrolyte having a low softening temperature is applied to these non-fluorinated electrolyte films has been proposed. Patent Document 2 proposes an electrolyte laminated film obtained by applying Nafion having a low softening temperature to the engineering plastic polymer electrolyte film.

JP-A-6-93114 International Publication WO2004 / 051776

Macromolecules, (1969), 2 (5), 453-458. Kautsch. Gummi, Kunstst. , (1984), 37 (5), 377-379; Polym. Bull. , (1984), 12, 71-77.

  However, an electrolyte membrane using an engineering plastic material has low power generation characteristics evaluated by cell resistance, and cell resistance / power generation characteristics tend to be greatly deteriorated particularly under low humidity.

  In addition, when Nafion is applied to improve the bondability with the catalyst layer, it is virtually impossible to separate Nafion at the time of disposal, and the load on disposal is as high as that of conventional fluorine-based electrolyte membranes. It becomes.

  Therefore, the present invention shows low cell resistance in a wide humidity range, and further has excellent mechanical strength at the time of drying and suppresses the linear expansion coefficient at the time of humidification. It is an object of the present invention to provide a non-fluorine polymer electrolyte membrane that maintains its power generation characteristics and is excellent in radical durability because of its excellent radical durability. Another object is to provide a membrane-electrode assembly comprising the polymer electrolyte membrane. It is another object of the present invention to provide a polymer electrolyte fuel cell comprising the membrane-electrode assembly.

  The inventors of the present invention have made extensive studies to solve the above problems, and are electrolyte laminated films for solid polymer fuel cells, in which at least two polymer electrolyte films are laminated as constituent electrolyte films, At least one of the molecular electrolyte membranes is a polymer electrolyte membrane (i) having as a main component a polymer (I) having an ion conductive group and having an aromatic ring in the main chain, and further comprising the polymer electrolyte A polymer electrolyte comprising as a main component a block copolymer (II) comprising at least one of a membrane block (A) having an ion conductive group and a polymer block (B) having no ion conductivity as a constituent component It has been found that the above problems can be solved by providing an electrolyte laminate film characterized by being a membrane (ii), and a membrane-electrode assembly and a polymer electrolyte fuel cell comprising the electrolyte laminate film, The present invention It has been completed.

That is, the invention described in claim 1
A polymer electrolyte membrane formed by laminating at least two polymer electrolyte membranes as a constituent electrolyte membrane, wherein at least one of the polymer electrolyte membranes has an ion conductive group and has an aromatic ring in the main chain A polymer electrolyte membrane (i) comprising (I) as a main component, wherein at least one of the polymer electrolyte membranes has a polymer block (A) having an ion conductive group and a heavy polymer having no ion conductive group; The present invention relates to an electrolyte laminated film, which is a polymer electrolyte film (ii) mainly composed of a block copolymer (II) having a combined block (B) as a constituent component.

The invention according to claim 2
2. The electrolyte laminated film according to claim 1, wherein the polymer block (B) is a rubber-like polymer block (B).

The invention according to claim 3
The polymer (I) is polyether ketones, polyether ether ketones, polyether ketone ketones, polyphenylene sulfides, polyphenylene ethers, polysulfones, polyether sulfones, polyether ether sulfones, polyphenylene sulfones. And at least one segment selected from polyphenylene sulfoxides, polyphenylene sulfide sulfones, polyphenylene oxides, polyparaphenylenes, polybenzoxazoles, polybenzothiazoles, polybenzimidazoles, and polyimides. It is related with the electrolyte laminated film of description.

The invention according to claim 4
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). .

The invention according to claim 5
2. The electrolyte laminated film according to claim 1, wherein the polymer block (A) has an aromatic vinyl compound unit as a main repeating unit in the polymer (II).

The invention according to claim 6
3. The electrolyte laminated film according to claim 2, wherein the block copolymer (II) further comprises a non-rubber-like polymer block (C) having no ion conductive group.

The invention according to claim 7
The said polymer block (C) is an electrolyte laminated film of Claim 6 which is a polymer block which has an aromatic vinyl type compound unit represented by the following general formula (a) as a main repeating unit.

（式中、Ｒ^１は水素原子又は炭素数１〜４のアルキル基であり、Ｒ^２〜Ｒ^４はそれぞれ独立に水素原子又は炭素数１〜８のアルキル基を表し、そのうち少なくとも１つはアルキル基を表す）

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ^{2 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and at least one of them is an alkyl group. Represents a group)

Further, the invention according to claim 8 is
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 diene unit having 4 to 8 carbon atoms and a carbon number. 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 invention according to claim 9 is
It is related with the electrolyte laminated film of Claim 6 whose mass ratio of the said polymer block (C) and the said polymer block (A) is 85: 15-20: 80.

The invention according to claim 10 is
2. The electrolyte laminated film according to claim 1, wherein a mass ratio of the polymer block (B) in the block copolymer (II) is 5 to 95 mass%.

The invention according to claim 11 is
The electrolyte laminated film according to claim 1, wherein the ion conductive group is a functional group represented by —SO ₃ M or —PO ₃ HM (wherein M represents a hydrogen atom, an ammonium ion, or an alkali metal ion). About.

Further, the invention according to claim 12 is
2. The electrolyte laminated film according to claim 1, wherein the polymer electrolyte membrane (i) has a thickness of 2 to 20 [mu] m, and the polymer electrolyte membrane (ii) has a thickness of 2 to 40 [mu] m.

The invention according to claim 13 is
The present invention relates to a membrane-electrode assembly comprising the electrolyte laminated film according to claim 1.

The invention as set forth in claim 14
The present invention relates to a polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 13.

  The electrolyte laminate film of the present invention has high dimensional stability and high mechanical durability even in a wide range of humidity changes from low humidity to high humidity, and is used in a polymer electrolyte fuel cell using hydrogen as a fuel. Excellent output characteristics and durability. This leads to the omission of many auxiliary devices conventionally required for controlling the humidity, which is advantageous for downsizing and cost reduction of the apparatus. Further, since the polymer electrolyte membrane has a high gas barrier property, it has excellent durability against radicals generated by permeation of oxygen and has a long life. Furthermore, the membrane-electrode assembly and the fuel cell using the electrolyte laminate film are excellent in power generation characteristics and radical durability.

  Hereinafter, the present invention will be described in detail.

  The polymer (I), which is the main component of the polymer electrolyte membrane (i) constituting the electrolyte laminated membrane of the present invention, preferably accounts for 70% by mass or more of the polymer electrolyte membrane (i), and 90% by mass or more. It is further desirable to occupy 95% by mass or more. A plurality of polymers (I) may be used in combination, and in this case, the main component of the polymer electrolyte membrane (i) may be constituted as the sum of the plurality of polymers (I) to be used. In the case where a plurality of polymers (I) are used in combination, it is desirable that the mutual affinity is high, and similarity such as primary structure and polarity is important.

  The components other than the polymer (I) contained in the polymer electrolyte membrane (i) constituting the electrolyte laminated membrane of the present invention are not particularly limited as long as the effects of the present invention are not impaired. Polymer materials (for example, polymers having no ion-conducting group and having an aromatic ring in the main chain; other polymer electrolytes (for example, polymer electrolytes similar to the block copolymer (II))); various inorganic materials ( For example, metal oxides, composite oxides, hydroxides, halides, carbonates, sulfates, silicates, etc., inorganic electrolytes having ionic conductivity, or inorganic salts having no ionic conductivity, etc.); Contains additives (eg, softeners, stabilizers, light stabilizers, antistatic agents, mold release agents, flame retardants, foaming agents, pigments, dyes, brighteners), each alone or in combination of two or more. May be.

  In the electrolyte laminate film of the present invention, at least one polymer electrolyte membrane (i) is laminated, but a plurality of layers may be used.

  The polymer (I), which is the main component of the polymer electrolyte membrane (i) used in the electrolyte laminate film of the present invention, is a polymer having an ion conductive group and having an aromatic ring in the main chain. Polyether ketones, polyether ether ketones, polyether ketone ketones, polyphenylene sulfides, polyphenylene ethers, polysulfones, polyether sulfones, polyether ether sulfones, polyphenylene sulfones, polyphenylene sulfoxides, polyphenylene sulfide sulfones The structure of an aromatic polymer having at least one segment selected from the group, polyphenylene oxides, polyparaphenylenes, polybenzoxazoles, polybenzothiazoles, polybenzimidazoles and polyimides. That. Among these, polyether ketones, polyether ether ketones, polyether ketone ketones, polyphenylene sulfides, and polyphenylene ethers are preferable from the viewpoint of dimensional stability, mechanical durability, and radical durability associated with gas barrier properties.

  The aromatic ring in these segments may have a substituent, for example, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group or a propyl group, a methoxy group or an ethoxy group having 1 to 1 carbon atoms. Substituents such as 6 alkoxy groups, aralkyl groups having 7 to 12 carbon atoms such as benzyl group, aryl groups such as phenyl group and naphthyl group, and halogens such as fluorine atom, chlorine atom and bromine atom. There may be a plurality of substituents, in which case they may be different. The hydrocarbon functional group such as an alkyl group, an alkoxy group, an aralkyl group, and an aryl group may have a structure in which a hydrogen atom of the functional group is substituted with another functional group.

  The polymer (I) may be a copolymer composed of two or more types of segments, and may be a random copolymer, a block copolymer, or a graft copolymer. Moreover, what was obtained by superposing | polymerizing can also use polymer (I), and can also use a commercial item. For example, polyether ether ketones can be obtained from VICTREX as “VICTREX PEEK”, and polyphenylene sulfides from Kureha Corporation as “Fortron KPS”.

  The molecular weight of the polymer (I) in a state where no ion-conducting group is introduced is usually preferably selected from 2,000 to 1,000,000 as the number average molecular weight in terms of polystyrene. More preferably, it is selected from the range of 5,000 to 500,000, more preferably from 8,000 to 100,000.

The ion-conducting group possessed by the polymer (I) is not particularly limited as long as the membrane-electrode assembly produced using the electrolyte laminate film can express sufficient ionic conductivity. A sulfonic acid group, a phosphonic acid group, a carboxyl group or a salt thereof represented by —SO ₃ M, —PO ₃ HM, or —COOM (wherein M represents a hydrogen atom, an ammonium ion, or an alkali metal ion). A sulfonic acid group, a phosphonic acid group or a salt thereof represented by —SO ₃ M or —PO ₃ HM is preferably used from the viewpoint of exhibiting particularly high ion conductivity.

  There are no particular restrictions on the position at which the ion conductive group of the polymer (I) is introduced, it may be introduced directly into the aromatic ring of the main chain, or it may be an alkyl group having 1 to 12 carbon atoms, a fluorinated alkyl group, carbon. It may be bonded to the main chain via an aromatic residue having 6 to 24 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or the like.

  In the case of, for example, a sulfonic acid group as the ion conductive group of the polymer (I), the introduction method is a method using sulfuric acid, a method using a mixture of sulfuric acid and an aliphatic acid anhydride, a method using chlorosulfonic acid, chloro A method using a mixture of sulfonic acid and trimethylsilyl chloride, a method using sulfur trioxide, a method using a mixture of sulfur trioxide and triethyl phosphate, and an aromatic organic compound represented by 2,4,6-trimethylbenzenesulfonic acid A method using sulfonic acid or the like is exemplified.

  For example, in the case of a phosphonic acid group as the ion conductive group of the polymer (I), the introduction method is such that after introducing a halomethyl group onto the aromatic ring, phosphorus trichloride and anhydrous aluminum chloride are added thereto and reacted. Examples thereof include a method of introducing a phosphonic acid group by performing a hydrolysis reaction, a method of introducing a phosphinic acid group onto an aromatic ring, and then oxidizing the phosphinic acid group with nitric acid to form a phosphonic acid group.

The ion exchange capacity of the polymer (I) is preferably in the range of 0.1 mmol / g to 5.0 mmol / g, and more preferably in the range of 0.5 mmol / g to 4.0 mmol / g. The ion exchange capacity can be adjusted by appropriately selecting conditions such as the type, concentration, temperature, and treatment time of the ion conductive group. The ion exchange capacity or the sulfonation rate or the phosphonation rate in the polymer (I) is determined by using an analytical means such as acid value titration method, infrared spectroscopic spectrum measurement, nuclear magnetic resonance spectrum ( ¹ H-NMR spectrum) measurement. Can be calculated.

  The ion conductive group of the polymer (I) 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 polymer (I) may contain one or a plurality of other monomer units as long as the effects of the present invention are not impaired, and various additives such as a softener, a stabilizer, and a light stabilizer. An agent, an antistatic agent, a release agent, a flame retardant, a foaming agent, a pigment, a dye, a whitening agent, and the like may be contained alone or in combination of two or more.

  The block copolymer (II), which is the main component of the polymer electrolyte membrane (ii) constituting the electrolyte laminate film of the present invention, preferably accounts for 70% by mass or more of the polymer electrolyte membrane (ii), and 90% by mass. % And more preferably 95% by mass or more. A plurality of these block copolymers (II) may be used in combination, and in this case, the main component of the polymer electrolyte membrane (ii) may be constituted as the sum of the plurality of block copolymers (II) to be used. When a plurality of block copolymers (II) are used in combination, it is desirable that the mutual affinity is high, and this is important for the similarity of the primary structure and polarity of each block constituting the block copolymer (II).

  Components other than the block copolymer (II) contained in the polymer electrolyte membrane (ii) constituting the electrolyte laminated membrane of the present invention are not particularly limited as long as the effects of the present invention are not impaired, Other polymer materials (for example, polymers having no ion conductive group; other polymer electrolytes (for example, polymer electrolytes similar to the polymer (I))); various inorganic materials (for example, metal oxides, complex oxidation) Products, hydroxides, halides, carbonates, sulfates, silicates, etc., inorganic electrolytes having ionic conductivity, or inorganic salts having no ionic conductivity); various additives (for example, softeners, Stabilizers, light stabilizers, antistatic agents, mold release agents, flame retardants, foaming agents, pigments, dyes, and brighteners) may be used alone or in combination of two or more.

  In the electrolyte laminate film of the present invention, at least one polymer electrolyte membrane (ii) is laminated, but a plurality of layers may be used.

  The polymer block (A) and the polymer block (B) constituting the block copolymer (II) contained in the polymer electrolyte membrane (ii) used in the electrolyte laminated membrane of the present invention may undergo microphase separation. Highly desirable. Microphase separation here refers to a block copolymer in which the ends of two or more types of chain polymers are linked by covalent bonds, and the same type of polymer chains aggregate and phase separate. This is a periodic structure obtained by forming a periodic self-organized structure from nanoscale to submicron scale. Such a microphase separation structure means phase separation in which the formed domain size is not more than the wavelength of visible light (3800 to 7800 mm). The polymer blocks (A) and the polymer blocks (B) have a property of gathering, and the polymer block (A) has an ion conductive group, so that the ion channels are formed by the gathering of the polymer blocks (A). It is formed and becomes a passage for ions such as protons.

  The polymer block (A) which is a constituent component of the block copolymer (II) may be a polymer block having an ion exchange group and capable of synthesizing the block copolymer. For example, a polymer block mainly composed of an aromatic vinyl compound unit, a polyether ketone block, a polysulfide block, a polyphosphazene block, a polyphenylene block, a polybenzimidazole block, a polyether sulfone block, a polyphenylene oxide block, a polycarbonate block, Polyamide block, polyimide block, polyurea block, polysulfone block, polysulfonate block, polybenzoxazole block, polybenzothiazole block, polyphenylquinoxaline block, polyquinoline block, polytriazine block, polyacrylate derivative block, polymethacrylate derivative block, etc. Among them, the main repetition of aromatic vinyl compound units Polymer block unit, polyetherketone blocks, polysulfide block, polyphosphazene block, polyphenylene block, polybenzimidazole block, polyether sulfone block, polyphenylene oxide block are preferred. Among these, a polymer block having an aromatic vinyl compound unit as a main repeating unit, which is easy to synthesize and has high affinity and excellent bonding properties due to the structural similarity to the polymer (I). More preferred.

  The aromatic ring contained in the aromatic vinyl compound unit constituting the polymer block (A) is preferably a carbocyclic aromatic ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring. Specific examples of these aromatic vinyl compounds include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-isopropylstyrene, 4-n-butyl. Styrene, 4-isobutylstyrene, 4-t-butylstyrene, 4-n-octylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene Aromatic vinyl compounds such as 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, vinylnaphthalene and vinylanthracene.

  Further, the aromatic vinyl compound unit may be a carbocyclic aromatic ring and the α-carbon may be a quaternary carbon. That is, a hydrogen atom bonded to an α-carbon atom is an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, or tert. -Butyl group), halogenated alkyl groups having 1 to 4 carbon atoms (chloromethyl group, 2-chloroethyl group, 3-chloroethyl group, etc.) or aromatic vinyl compounds substituted with phenyl groups, and the like. Specific examples include α-methyl styrene, α-methyl-4-methyl styrene, α-methyl-4-ethyl styrene, α-methyl-4-t-butyl styrene, 1,1-diphenylethylene, and the like.

  These can be used alone or in combination of two or more. Among them, styrene, α-methylstyrene, 4-methylstyrene, 4-ethylstyrene, α-methyl-4-methylstyrene, α-methyl-2-methylstyrene are used. From the viewpoints of availability of materials, ease of synthesis, and introduction of ion exchange groups.

  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 dienes 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, Vinyl valine acid, etc.), vinyl ethers (methyl vinyl ether, isobutyl vinyl ether, etc.), and the like. The copolymerization form with the other monomer is desirably random copolymerization.

  When the polymer block (A) has an aromatic vinyl compound unit as a main repeating unit, it is advantageous in causing microphase separation with the polymer block (B), 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 electrolyte laminated film, and 70% by mass. %, More preferably 90% by mass or more.

  It is preferable for the polymer block (A) to occupy 5 to 60% by mass of the block copolymer (II) in order to impart sufficient ionic conductivity to the resulting electrolyte laminate film. More preferably, it occupies 10 to 55% by mass, and more preferably 20 to 50% by mass or more.

  The molecular weight of each polymer block (A) is 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 a block copolymer. When the molecular weight is small, the microphase-separated structure and thus the ion channel In view of these tendencies, the molecular weight can be appropriately selected according to the required function. .

  The molecular weight of each polymer block (A) in the state where the ion conductive group is not introduced is preferably selected from among 3,000 to 100,000 as the number average molecular weight in terms of polystyrene. More preferably, it is selected from the range of 4,000 to 50,000, more preferably from 5,000 to 20,000. Moreover, it is preferable to select from among 5,000-10,000 from the viewpoint of the ease of solution preparation at the time of film formation, and film forming property.

  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 block copolymer (II) in the polymer electrolyte membrane (ii) constituting the electrolyte laminate film of the present invention needs to have an ion conductive group in the polymer block (A). This is because the introduction of the ion conductive group to the polymer block (A) is particularly effective for improving the radical resistance of the entire block copolymer (II).

  The ion conductive group possessed by the polymer block (A) is not particularly limited, and functional groups having ion conductivity can be used, and those having high affinity with anions and / or cations, particularly one of functional groups. Those in which the moiety is easily dissociated as ions are suitable, 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.

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 by using the electrolyte laminate film can express sufficient ion conductivity. Among them, —SO ₃ M or —PO is particularly preferable. A sulfonic acid group, a phosphonic acid group, a carboxyl group or a salt thereof represented by ₃ HM or -COOM (wherein M represents a hydrogen atom, an ammonium ion or an alkali metal ion) can be used. in view illustrating the ion conductivity, a sulfonic acid group represented by -SO ₃ M or _-PO 3 HM, a phosphonic acid group or their salts are preferably used.

  The introduction position of the ion conductive group into the polymer block (A) is not particularly limited. Even if it is introduced into the aromatic compound unit or the aromatic vinyl compound unit, it is introduced into the other monomer units described above. However, from the viewpoint of facilitating ion channel formation, it is preferably introduced into the aromatic ring of the aromatic compound unit or aromatic vinyl compound unit.

  The amount of ion-conductive group introduced is appropriately selected depending on the required performance of the obtained block copolymer (II), but sufficient ion conductivity to be used as an electrolyte membrane for a polymer electrolyte fuel cell. In order to express it, it is usually preferable that the ion exchange capacity of the block copolymer (II) is 0.70 meq / g or more, and that the amount is 1.00 meq / g or more. It is more preferable. The upper limit of the ion exchange capacity of the block copolymer (II) is 4.00 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 polymer block (B) having no ion conductive group is preferably a polymer block that undergoes microphase separation from the polymer block (A). For example, styrene derivatives (α-, o-, m-, p-alkyl, alkoxyl, halogen, haloalkyl, nitro, cyano, amide, ester substituted products of styrene), conjugated dienes 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.), C2-C8 alkene (ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2- Hexene, 1-heptene, 2-heptene, 1-octene, 2-octene, etc.), C5-C8 cycloalkene (cyclopentene, cyclohexene) , Cycloheptene and cyclooctene), vinylcycloalkenes having 7 to 10 carbon atoms (vinylcyclopentene, vinylcyclohexene, vinylcycloheptene, vinylcyclooctene, etc.), (meth) acrylate esters (methyl (meth) acrylate, ( (Meth) ethyl acrylate, butyl (meth) acrylate, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, etc.), vinyl ethers (methyl vinyl ether, isobutyl vinyl ether, etc.) and the like.

  “No ion conductive group” in the polymer block (B) means having no ion conductive group to the extent that it does not substantially exhibit ion conductivity, and the repetition of the polymer block (B) The number of ion conductive groups per unit may be 0.1 or less, and preferably 0.05 or less.

  Among these, the polymer block (B) is preferably composed of the rubber-like polymer block (B), and this makes the block copolymer (II) elastic and flexible as a whole. In the production of a membrane-electrode assembly or a polymer electrolyte fuel cell, the moldability (such as assembling property, bonding property, and tightening property) is improved. The rubber-like polymer block (B) here means that the glass transition point or softening point is 30 ° C. or less, preferably 20 ° C. or less, and more preferably 10 ° C. or less. Here, the glass transition point or softening point can be inferred from the measured value of the homopolymer corresponding to the polymer block (B).

  The rubbery polymer block (B) is composed of alkene units having 2 to 8 carbon atoms, cycloalkene units having 5 to 8 carbon atoms, vinylcycloalkene units having 7 to 10 carbon atoms, and conjugated diene units having 4 to 8 carbon atoms. And a polymer block composed of at least one repeating unit selected from the group consisting of conjugated cycloalkadiene units having 5 to 8 carbon atoms, alkene units having 2 to 8 carbon atoms, and conjugates having 4 to 8 carbon atoms. More preferably, it is a polymer block comprising at least one repeating unit selected from diene units, and at least one repeating unit selected from alkene units having 2 to 6 carbon atoms and conjugated diene units having 4 to 8 carbon atoms. More preferably, the polymer block is composed of units. In the above, the most preferable alkene unit is a structure unit saturated with a double bond of an isobutene unit, a 1,3-butadiene unit (1-butene unit, 2-butene unit), or a structure saturated with a double bond of an isoprene unit. Unit (2-methyl-1-butene unit, 3-methyl-1-butene unit, 2-methyl-2-butene unit). Combination of saturated structural units (1-butene unit, 2-butene unit), structural units saturated with a double bond of isoprene unit (2-methyl-1-butene unit, 3-methyl-1-butene unit, 2- Most preferred is the combined use of methyl-2-butene units. Most preferred as conjugated diene units are 1,3-butadiene units and / or isoprene units. These can be used alone or in combination of two or more.

  When a monomer capable of constituting the repeating unit is polymerized (copolymerized), when a conjugated diene is used as the monomer, a plurality of possible polymerization modes (for example, 1 in 1,3-diene) , 2-bond, 3,4-bond, 1,4-bond), and if the glass transition point or softening point is 30 ° C. or less, the ratio of these polymerization modes (for example, 1 , 2-bond and 1,4-bond) is not particularly limited.

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 diene 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 electrolyte laminate film, it is preferable that 80 mol% or more of such carbon-carbon double bonds are hydrogenated, 90 More preferably, at least mol% is hydrogenated, and even more preferably at least 95 mol% is hydrogenated. For example, as the polymer block (B), one obtained by polymerizing a conjugated diene unit having 4 to 8 carbon atoms and hydrogenating substantially all of the carbon-carbon double bonds may be used. 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.

  In addition, by reducing the double bonds in the polymer block (B) in this manner, the ion conductive group introduction reaction is less likely to occur. For example, the block copolymer having no ion conductive group has an ionic conductivity. When the block copolymer (II) is produced by carrying out a group introduction reaction, it is advantageous for forming a polymer block (B) having no ion conductive group.

  In order for the polymer block (B) to give elasticity to the block copolymer (II), the rubbery polymer block (B) preferably contains 70% by mass or more of a preferable repeating unit, More preferably 80% or more, and more preferably 90% or more. Other repeating units may include, for example, aromatic vinyl compound units such as styrene units and vinyl naphthalene units, and halogen-containing vinyl compound units such as vinyl chloride units.

  It is preferable that the polymer block (B) accounts for 40% by mass or more of the block copolymer (II) because excellent water resistance is exhibited. It is more preferable to occupy 50 mass%, and it is still more preferable to occupy 60 mass% or more. When the polymer block (B) is rubbery, the block copolymer (II) preferably occupies 25% or more, more preferably 40% or more in order to exhibit flexibility.

  The molecular weight of each polymer block (B) is 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 (II). When the molecular weight is small, the microphase separation structure, and thus Since it is difficult to form an ion channel, the ion conductivity tends not to be exhibited, and the mechanical properties tend to be low. Therefore, considering these tendencies, the molecular weight is appropriately selected according to the required function. be able to.

  The structure of the block copolymer (II) 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), and at least one It is desirable that at least one end of the polymer block (B) is not a terminal of the block copolymer (II). 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 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 60:40 to 5:95, more preferably 50:50 to 10:90, and 40:60 to It is even more preferable that the ratio is 20:80. When the mass ratio is in this range, it is advantageous that the ion channel formed by the polymer block (A) becomes a cylindrical or continuous phase by microphase separation, and practically sufficient ion conductivity is exhibited. Moreover, the ratio of the polymer block (B) which is hydrophobic becomes appropriate, and excellent water resistance is exhibited.

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

  The number average molecular weight of the block copolymer (II) 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 (II) of the present invention may further include a non-rubber polymer block (C) having no ion conductive group as a constituent component. The polymer block (C) functions as a constraining phase. Since the polymer block (C) here needs to exhibit a restraining function under the use conditions, its glass transition point or softening point needs to exceed 30 ° C., and the glass transition point or The softening point is preferably 40 ° C. or higher, more preferably 70 ° C. or higher, and further preferably 80 ° C. or higher. Here, the glass transition point or softening point can be inferred from the measured value of the homopolymer corresponding to the polymer block (C).

  As the polymer block (C), a polymer block having an aromatic vinyl compound unit as a main repeating unit, a polyether ketone block, a polysulfide block, a polyphosphazene block, a polyphenylene block, a polybenzimidazole block, a polyether sulfone block, Polyphenylene oxide block, polycarbonate block, polyamide block, polyimide block, polyurea block, polysulfone block, polysulfonate block, polybenzoxazole block, polybenzothiazole block, polyphenylquinoxaline block, polyquinoline block, polytriazine block, polyacrylate derivative Blocks, polymethacrylate derivative blocks, etc. A polymer block, a polyetherketone block, a polysulfide block, a polyphosphazene block, a polyphenylene block, a polybenzimidazole block, a polyethersulfone block, and a polyphenylene oxide block having a main unit as a main repeating unit are preferred, and the synthesis is easy. From the viewpoint that the structure is similar to that of the polymer (I) used in the present invention, the polymer block is mainly composed of an aromatic vinyl compound unit from the viewpoint of high affinity and uniform integration. More preferred.

  The aromatic ring of the aromatic vinyl compound unit is preferably a carbocyclic aromatic ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring. Specific examples of these aromatic vinyl compounds include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-isopropylstyrene, 4-n-butyl. Styrene, 4-isobutylstyrene, 4-t-butylstyrene, 4-n-octylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene Aromatic vinyl compounds such as 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, vinylnaphthalene and vinylanthracene.

  In addition, as the carbocyclic aromatic ring that the aromatic vinyl compound unit has, the α-carbon may be a quaternary carbon. That is, a hydrogen atom bonded to an α-carbon atom is an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, or tert. -Butyl group), halogenated alkyl groups having 1 to 4 carbon atoms (chloromethyl group, 2-chloroethyl group, 3-chloroethyl group, etc.) or aromatic vinyl compounds substituted with phenyl groups, and the like. Specifically, α-methylstyrene, α-methyl-4-methylstyrene, α-methyl-4-ethylstyrene, α-methyl-4-t-butylstyrene, α-methyl-4-isopropylstyrene, 1, Examples include 1-diphenylethylene.

  These can be used alone or in combination of two or more. Among them, 4-t-butylstyrene, 4-isopropylstyrene, α-methyl-4-t-butylstyrene, and α-methyl-isopropylstyrene are preferable. 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 (C) 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 dienes 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, Vinyl valine acid, etc.), vinyl ethers (methyl vinyl ether, isobutyl vinyl ether, etc.), and the like. The copolymerization form with the other monomer is desirably random copolymerization.

  When the polymer block (C) accounts for 10% by mass or more of the block copolymer (II), the mechanical strength is kept high, which is preferable. More preferably, it occupies 20% by mass or more, and more preferably 25% by mass or more.

  Although there is no limitation in particular in the ratio of a polymer block (C) and a polymer block (A), it is 85: 15-0: 100 as a ratio of the monomer unit before introduce | transducing an ion conductive group. Is preferable, and it is preferably 85:15 to 20:80 and more preferably in the range of 75:25 to 25:75 in order to achieve both the mechanical strength of the polymer block (C) and high ionic conductivity. It is preferable.

  Further, the total of the rubber-like polymer block (B) and the polymer block (C) accounts for 40% by mass or more of the block copolymer (II), so that excellent water resistance is exhibited. It is more preferable to occupy 50 mass%, and it is still more preferable to occupy 60 mass% or more.

  The polymer block (C) having substantially no ion conductive group has the following general formula (a):

（式中、Ｒ^１は水素原子又は炭素数１〜４のアルキル基であり、Ｒ^２〜Ｒ^４はそれぞれ独立に水素原子又は炭素数１〜８のアルキル基を表し、そのうち少なくとも１つはアルキル基を表す）で表される芳香族ビニル系化合物単位を主たる繰返し単位として有する重合体ブロックから構成されていてもよい。一般式（ａ）のＲ^１で表される炭素数１〜４のアルキル基は、直鎖状でも分岐状でもよく、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、ｓｅｃ−ブチル基、イソブチル基、ｔｅｒｔ−ブチル基などが挙げられる。一般式（ａ）のＲ^２〜Ｒ^４で表される炭素数１〜８のアルキル基は、直鎖状でも分岐状でもよく、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、ｓｅｃ−ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ｔｅｒｔ−ペンチル基、ヘキシル基、１−メチルペンチル基、ヘプチル基、オクチル基などが挙げられる。一般式（ａ）で表される芳香族ビニル系化合物単位の好適な具体例としては、ｐ−メチルスチレン単位、４−ｔｅｒｔ−ブチルスチレン単位、ｐ−メチル−α−メチルスチレン単位、４−ｔｅｒｔ−ブチル−α−メチルスチレン単位等が挙げられ、これらは１種または２種以上組み合わせて用いてもよい。これら２種以上を重合（共重合）させる場合の形態は、ランダム共重合でもブロック共重合でもグラフト共重合でもテーパード共重合でもよい。

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ^{2 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and at least one of them is an alkyl group. It may be composed of a polymer block having as a main repeating unit an aromatic vinyl compound unit represented by: The alkyl group having 1 to 4 carbon atoms represented by R ¹ in the general formula (a) may be linear or branched, and is a methyl group, ethyl group, propyl group, isopropyl group, butyl group, 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 in the general formula (a) may be linear or branched, and is methyl, ethyl, propyl, isopropyl, butyl, sec Examples include -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 (C) may contain one or more other monomer units in addition to the aromatic vinyl compound unit as long as the function as a constrained phase is not hindered. Examples of the monomer that provides such other monomer units include conjugated dienes having 4 to 8 carbon atoms, alkenes having 2 to 8 carbon atoms, (meth) acrylic acid esters, vinyl esters, vinyl ethers, and the like. The copolymerization form of the aromatic vinyl compound and the other monomer is desirably random copolymerization.
From the viewpoint of serving as a constrained phase, the aromatic vinyl compound unit described above preferably occupies 50% by mass or more, more preferably 70% by mass or more of the polymer block (C), and 90% by mass. It is even more preferable to occupy% or more.

  The molecular weight of the polymer block (C) is appropriately selected depending on properties of the polymer electrolyte, 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, but when it is too large, it becomes difficult to mold and form a block copolymer, and when the molecular weight is small, the mechanical properties tend to be low, It is important to select the molecular weight appropriately according to the required performance. The number average molecular weight in terms of polystyrene is usually preferably selected from 800 to 500,000, more preferably from 2,000 to 150,000, and more preferably from 3,000 to 50,000. It is more preferable to select between.

  When the block copolymer (II) used in the present invention is composed of a polymer block (C), a polymer block (A) and a polymer block (B), the structure of the block copolymer (II) is: Although not particularly limited, examples include A-B-C-A tetrablock copolymer, B-A-B-C tetrablock copolymer, A-B-C-B tetrablock copolymer, C-B- C-A tetra-block copolymer, A-B-A-C tetra-block copolymer, A-C-B-C-A penta-block copolymer, C-A-B-A-C penta-block copolymer Polymer, A-C-B-C-A pentablock copolymer, C-B-A-B-C pentablock copolymer, A-B-C-A-B pentablock copolymer, A-B -C-A-C pentablock copolymer, A-B-C-B-C pentablock copolymer Coalescence, A-B-A-B-C pentablock copolymer, A-B-A-C-B pentablock copolymer, B-A-B-A-C pentablock copolymer, B-A -B-C-A pentablock copolymer, B-A-B-C-B pentablock copolymer, C-A-C-B-C pentablock copolymer and the like.

  The polymer block (A) and the polymer block (B), which are constituent components of the block copolymer (II), undergo microphase separation, and the polymer block (A) and the polymer block (B) are separated from each other. Each of the polymer blocks (A) has an ion conductive group, and therefore, an ion channel is formed by the assembly of the polymer blocks (A) and becomes a passage for protons.

  The block copolymer (II) 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 graft-bonded to a main part (for example, main chain) of the block copolymer.

  It does not specifically limit regarding the manufacturing method of block copolymer (II) used by this invention, A well-known method can be used. For example, there is a method in which an ion conductive group is bonded after a block copolymer having no ion conductive group is produced. In this case, a polymer block composed of a repeating unit in which an ion conductive group is easily introduced and a block copolymer composed of a polymer block in which the ion conductive group is difficult to be introduced are first produced, and an ion conductive group introduction reaction is performed. A polymer block consisting of a repeating unit in which an ion conductive group is easily introduced becomes the polymer block (A), and a polymer block consisting of a repeating unit in which the ion conductive group is difficult to be introduced is a polymer block (B) or (C). It becomes. For polymer blocks consisting of repeating units in which ion-conducting groups are difficult to be introduced, a monomer may be selected so that a site that is easily functionalized such as a double bond disappears after polymerization. Sites that are likely to be removed may be removed after polymerization (for example, hydrogenation of double bonds).

  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 control, molecular weight distribution control, polymer structure control, ease of bonding between the polymer block (A) and the polymer block (B), and specifically, a living radical polymerization method. Living anionic polymerization and living cationic polymerization are preferred.

As a specific example of the production method, a production method of a block copolymer comprising as a component a polymer block (A) made of poly (α-methylstyrene) and a polymer block (B) made of a conjugated diene 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 type block copolymer by sequentially polymerizing α-methylstyrene under a temperature condition of −78 ° C. after conjugated diene polymerization using a dianionic initiator in a tetrahydrofuran solvent (for example, Non-patent document 1).
(2) α-methylstyrene is subjected to bulk polymerization using an anionic initiator, then conjugated dienes are sequentially polymerized, and then a coupling reaction is performed with a coupling agent such as tetrachlorosilane, and (AB) nX type A method for obtaining a block copolymer (for example, see Non-Patent Documents 2 and 3).
(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 method in which α-methylstyrene is polymerized and a conjugated diene is polymerized in the resulting living polymer, and then a coupling agent is added 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 (A)) is polymerized, the resulting living polymer is polymerized with a conjugated diene, and the resulting α-methylstyrene polymer block and the resulting conjugated diene polymer block are used. A method of obtaining an ABA type block copolymer by polymerizing a monomer constituting the polymer block (A) to a living block copolymer.

As specific examples of the production method, a polymer block (C) having an aromatic vinyl compound such as 4-tert-butylstyrene as a main repeating unit, a polymer block (A) comprising styrene or α-methylstyrene, and A method for producing a block copolymer or graft copolymer comprising a polymer block (B) comprising a conjugated diene 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 polymer blocks (C), (B) and (A), and the following specific synthesis examples Can be adopted / applied.
(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 diene and styrene are sequentially polymerized. And a method of obtaining a CBA type block copolymer.
(6) 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 styrene and a conjugated diene are sequentially polymerized. Then, a coupling agent such as phenyl benzoate is added to obtain a C-A-B-A-C 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 diene, 4-tert-butylstyrene, etc. Sequentially polymerize aromatic vinyl compounds to create a CBC block copolymer and add an anionic polymerization initiator system (anionic polymerization initiator / N, N, N ′, N′-tetramethylethylenediamine) Then, after lithiation of the conjugated diene unit, styrene is polymerized to obtain a CB (-gA) -C 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 diene and 4-tert-butylstyrene to form an ABC type block copolymer, and α-methyl A method of sequentially polymerizing styrene, 4-tert-butylstyrene, conjugated diene, and 4-tert-butylstyrene to obtain an ABCBC block copolymer.

  The block copolymer thus produced is subjected to a hydrogenation reaction of double bonds of conjugated diene 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 system. 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 described above until the ion exchange capacity of the block copolymer (II) is 0.70 meq / g or more, particularly 0.80 meq / g or more. It is desirable to be sulfonated or phosphonated so as to be not more than 00 meq / g. Thereby, practical ion conduction performance is obtained. The ion exchange capacity of the sulfonated or phosphonated block copolymer (II), or the sulfonation rate or phosphonation rate in the aromatic vinyl compound in the block copolymer (II) is determined by acid value titration, red It can be calculated using an analytical means such as an external spectral spectrum measurement or a nuclear magnetic resonance spectrum ( ¹ H-NMR spectrum) measurement.

  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 (II) having a sulfonic acid group in a salt form can be obtained by ion exchange by an appropriate method.

  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, You may contain dye, a brightening agent, etc. individually or in combination of 2 or more types.

  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-diethylenebis [ 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- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane and other phenolic stabilizers Agents: pentaerythrityltetrakis (3-lauryl thiopropionate), distearyl 3,3'-thiodipropionate, dilauryl 3,3'-thiodipropio And sulfur stabilizers such as dimyristyl 3,3′-thiodipropionate; trisnonylphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, diasterylpentaerythritol diphosphite, bis Examples thereof include phosphorus stabilizers such as (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite.

  The electrolyte laminated film of the present invention preferably has a film thickness of about 5 to 500 μm, preferably about 7 to 100 μm, from the viewpoint of performance, film strength, handling properties, etc. required as an electrolyte membrane for a polymer electrolyte fuel cell. It is more preferable that 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 5 to 300 μm.

  The polymer electrolyte membrane (i) and the polymer electrolyte membrane (ii), which are constituent components of the electrolyte laminated membrane of the present invention, are polymer electrolyte membranes (i ) Is 2 to 20 μm, the thickness of the polymer electrolyte membrane (ii) is preferably 2 to 40 μm, the thickness of the polymer electrolyte membrane (i) is 3 to 10 μm, and the polymer More preferably, the thickness of the electrolyte membrane (ii) is 3 to 20 μm. The thickness ratio between the polymer electrolyte membrane (i) and the polymer electrolyte membrane (ii) is preferably 1: 4 to 4: 1.

  The layer configuration of the polymer electrolyte laminate film of the present invention is not particularly limited, but from the viewpoint of improving the electrical bondability between the membrane and the electrode, the outermost polymer electrolyte layer has higher ion conduction capacity than the inside, It is preferable from the viewpoint of improving the electrical characteristics of the membrane and the electrode and improving the battery characteristics. Preferable examples include a polymer electrolyte laminate film having a structure in which an outer layer having a high ion exchange capacity is provided on both sides of an inner layer having a low ion exchange capacity. In addition, a polymer electrolyte laminate film having a structure in which an outer layer (eg, polymer electrolyte membrane (ii)) having higher thermoplasticity is provided on both surfaces of an inner layer (eg, polymer electrolyte membrane (i)) having low thermoplasticity. it can. With such a configuration, joining with the electrode is facilitated by heating. For the same reason, it is desirable to dispose a polymer electrolyte membrane containing a polymer having a structure closer to that of the binder component of the catalyst layer so as to be in contact with the catalyst layer. In addition, a polymer having a structure in which layers having lower mechanical strength (for example, the polymer electrolyte membrane (ii)) are arranged on both sides of a layer having higher mechanical strength (for example, the polymer electrolyte membrane (i)) with good objectivity An electrolyte laminated film can be mentioned. With such a configuration, deformation of the electrolyte laminated film can be further suppressed.

  As for the preparation of the polymer electrolyte laminate film of the present invention, any method can be adopted as long as it is a usual method for such preparation. For example, in order to produce one of the polymer electrolyte membranes constituting the electrolyte laminate film of the present invention, the polymer (I) or the block copolymer (II), and the additives as described above are used in a suitable solvent. And a homogeneous solution or emulsion of the above polymer (I) or block copolymer (II) of 5% by mass or more is prepared, and then a coater or applicator tower is applied to a release-treated PET film or the like. Using a known method such as a solution coating method for obtaining an electrolyte membrane having a desired thickness by removing the solvent under an appropriate condition after application using heat treatment, roll molding, extrusion molding, or the like. A method for forming a film can be used, but a solution coating method is preferably used from the viewpoint of easily preparing an electrolyte membrane having good strength and flexibility.

  In order to form the same or different electrolyte membrane as the second layer on the obtained first electrolyte membrane, the same or different polymer (I) or block copolymer (II) is newly added. Similarly, it can be produced by applying and drying. In the case of producing a laminated film composed of three or more layers, the third and subsequent layers may be applied and dried in the same manner as in the above method. Moreover, you may make it laminate | stack by making the same or different electrolyte membranes obtained as mentioned above press-fit by hot roll shaping | molding. Also, from the viewpoint of improving the interfacial bonding property of the laminated film, for example, after applying the first layer, the uneven substrate is pressed, or the first layer is applied on the uneven substrate. Thus, the surface of the first layer may be made uneven to increase the surface area, and then the second layer may be applied to form a laminate. A similar technique can be applied to the third and subsequent layers.

    The solvent used when preparing in a homogeneous solution system can prepare a solution having a viscosity that allows solution coating without destroying the structure of the polymer (I) or the block copolymer (II). There is no particular limitation as long as it is possible. 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. Hydrogens, ethers such as tetrahydrofuran, alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutyl alcohol, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and the like Examples include aprotic polar solvents or mixed solvents thereof. Depending on the structure of the polymer (I) and the block copolymer (II), the structure of the copolymer, the molecular weight, the ion exchange capacity, etc., one or a combination of two or more of the solvents exemplified above may be used. It can be appropriately selected and used. In view of easy adjustment of an electrolyte membrane having particularly good strength and flexibility, an aprotic polar solvent is preferable in the polymer (I), and a mixed solvent of toluene and isobutyl alcohol in the block copolymer (II), 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, and a mixed solvent of tetrahydrofuran and methanol are preferable. In particular, a mixed solvent of toluene and isobutyl alcohol, toluene and isopropyl alcohol The mixed solvent is preferable. From the viewpoint of enhancing the interfacial bonding between the polymer electrolyte membrane (i) and the polymer electrolyte membrane (ii), an appropriate amount of a solvent that dissolves the block copolymer (II) is mixed in the polymer (I) solution during coating. Alternatively, an appropriate amount of a solvent for dissolving the polymer (I) may be mixed in the solution of the block copolymer (II).

  The solvent removal conditions in the solution coating method are such that the solvent can be completely removed at a temperature not higher than the temperature at which ion conductive groups such as sulfonic acid groups of the polymer (1) or the block copolymer (II) are removed. Any selection can be made. 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 polymer (I) or block copolymer (II) 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 of 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 laminate film of the present invention has a high dimensional stability and a high mechanical property even in a wide humidity change from low humidity to high humidity by laminating the polymer electrolyte membrane (i) and the polymer electrolyte membrane (ii). It has durability and is excellent in output characteristics and durability when used in a polymer electrolyte fuel cell using hydrogen as a fuel. This leads to the omission of many auxiliary devices conventionally required for controlling the humidity, which is advantageous for downsizing and cost reduction of the apparatus. Further, since the gas barrier property of the electrolyte membrane is high, it is excellent in the durability of radicals generated by permeation of oxygen and has a long life. Furthermore, since the electrolyte has a flexible polymer having elasticity and flexibility, it has excellent bondability with the electrode, and the membrane-electrode assembly and the fuel cell using the electrolyte laminated film have output characteristics and durability. Excellent in properties.

  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.

(Performance tests and results of polymer films of Examples and Comparative Examples)
The films obtained in each Example or Comparative Example were evaluated by the following tests 1) to 5).

1) Linear expansion coefficient After immersing a sample of 1 cm × 4 cm in distilled water for 4 hours, the length (x) in the longitudinal direction is measured, calculated by the following formula, less than 10% ○, 10% or more × Linear expansion coefficient (%) = (x−4) / 4 × 100

2) Film strength A 5 cm incision was made in a 2.5 cm × 7.5 cm dumbbell-shaped test piece in the long axis direction, and the material was measured at 25 ° C. and 50% relative humidity with an Instron Japan 5566 type tensile tester. The stress was measured under the condition of a tensile speed of 250 mm / min.

3) Power generation characteristics of single cells for fuel cells (under 100% humidity)
The output performance of a single cell for a polymer electrolyte fuel cell produced using the obtained electrolyte membrane and electrolyte laminated membrane was evaluated. Hydrogen was used as the fuel and air was used as the oxidant. The hydrogen supply conditions were stoichiometric 1.3 and humidification at 100% RH. The air supply conditions were stoichiometric 2.0 and humidification at 100% RH. After setting the cell temperature to 70 ° C. and setting the evaluation cells created in the examples and comparative examples, the power generation test was performed, the cell resistance and voltage at 1.0 A / cm ² were evaluated, and the cell resistance As for, less than 3.0 mΩ was marked as ◯, 3.0 mΩ or more as x, and as for voltage, 0.50 V or more was marked as ◯, and less than 0.50 V was marked as x.

4) Power generation characteristics of fuel cell single cells (30% humidity)
The output performance of a single cell for a polymer electrolyte fuel cell produced using the obtained electrolyte membrane and electrolyte laminated membrane was evaluated. Hydrogen was used as the fuel and air was used as the oxidant. The hydrogen supply conditions were stoichiometric 1.3 and humidification 30% RH. The air supply conditions were stoichiometric 2.0 and humidification 30% RH. After setting the cell temperature to 70 ° C. and setting the evaluation cells created in Examples and Comparative Examples, pretreatment was performed using hydrogen and air humidified to 100% RH, and then a power generation test. The cell resistance at 1.0 A / cm ² and the voltage were evaluated. For the cell resistance, less than 3.0 mΩ was marked as ◯, 3.0 mΩ or more as x, and the voltage as 0.45 V or more as ◯, Less than 0.45V was set as x.

5) Durability (open circuit voltage / OCV) test An open circuit test (OCV test) was performed as an acceleration test on the single cell for the polymer electrolyte fuel cell prepared using the obtained electrolyte membrane and electrolyte laminated membrane. . In the test, hydrogen and oxygen were supplied to the anode and the cathode at a rate of 500 mL / min at normal pressure, respectively, and the humidity was 30% RH. After setting the cell temperature to 90 ° C. and setting the cells prepared in the examples and comparative examples, the power generation is not performed and the cells are left in an open circuit state, and the voltage after 100 hours is measured. A value of 0.95 V or higher, 100 hours later 0.90 V or higher was rated as ◯, and less than that was rated as x.

<Reference Example 1>
(Production of block copolymer comprising polystyrene (polymer block (A)), hydrogenated polyisoprene (polymer block (B)) and poly (4-tert-butylstyrene) (polymer block (C))
Into a 1400 mL autoclave was charged 865 ml of dehydrated cyclohexane and 3.27 ml of sec-butyllithium (1.25 M-cyclohexane solution), and then 36.1 ml of 4-tert-butylstyrene and 51.0 ml of styrene were successively added at 50 ° C. Poly (4-tert-butylstyrene) -b-polystyrene by sequential polymerization, followed by sequential addition of 149 ml of isoprene, 49.4 ml of styrene and 33.7 ml of 4-tert-butylstyrene and successive polymerization at 60 ° C. -B-polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (hereinafter abbreviated as tBSSIStBS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained tBSSIStBS is 99010, the 1,4-bond content determined from ¹ H-NMR measurement is 94.0%, and the content of styrene units is 34.8 mass. %, 4-tert-butylstyrene unit content was 24.8% 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 70 ° C. for 8 hours in a hydrogen atmosphere using a Ni / Al Ziegler-type hydrogenation catalyst. To obtain poly (4-tert-butylstyrene) -b-polystyrene-b-hydrogenated polyisoprene-b-polystyrene-b-poly (4-tert-butylstyrene) (hereinafter abbreviated as tBSSEPStBS). . When the hydrogenation rate of the obtained tBSSEPStBS was calculated by ¹ H-NMR spectrum measurement, no peak derived from the polyisoprene double bond was detected.

<Production Example 1>
(Synthesis of sulfonated tBSSEPStBS)
40 g of the block copolymer (tBSSEPStBS) obtained in Reference Example 1 was vacuum-dried for 1 hour in a glass reaction vessel equipped with a stirrer, and then purged with nitrogen. Then, 500 ml of methylene chloride was added, and the mixture was stirred at room temperature. And dissolved. 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. The sulfonation rate of the benzene ring of the styrene unit of the obtained sulfonated tBSSEPStBS was 100 mol% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated tBSSEPStBS was 2.64 meq / g.

<Production Example 2>
(Synthesis of sulfonated polyether ether ketone)
After 30 g of polyetheretherketone resin (PEEK, 450P, manufactured by VICTREX) was replaced with nitrogen in a glass reaction vessel equipped with a stirrer, 550 g of concentrated sulfuric acid was added and dissolved by stirring at room temperature. After stirring at room temperature for 110 hours, the reaction product was poured into ice-cooled water to coagulate and precipitate the polymer. The solid content was filtered, the obtained solid content was transferred to a beaker, 2 L of distilled water was added, and the mixture was washed with stirring, and then recovered by filtration. 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 a sulfonated polyetheretherketone. The sulfonation rate of the obtained sulfonated polyether ether ketone in the monomer unit was 62% from ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated polyether ether ketone was 1.80 meq / g.

<Example 1>
(Preparation of electrolyte laminated film)
A 16% by weight toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS obtained in Production Example 1 was prepared, and a release-treated PET film ["Toyobo Ester Film K1504" manufactured by Toyobo Co., Ltd.] A film having a thickness of about 75 μm was coated thereon, and dried with a hot air dryer at 100 ° C. for 4 minutes to obtain a film having a thickness of 7 μm. Next, a 13% by mass dimethyl sulfoxide solution of the sulfonated polyether ether ketone obtained in Production Example 2 was prepared, coated on the membrane with a thickness of about 75 μm, and dried at 100 ° C. for 20 minutes. A film having a total thickness of 14 μm was obtained. A 16% by weight toluene / isopropyl alcohol (mass ratio 5/5) solution of the sulfonated tBSSEPStBS obtained in Production Example 1 was coated thereon with a thickness of about 75 μm, and dried at 100 ° C. for 4 minutes. A film having a thickness of 21 μm was obtained. The obtained electrolyte laminated film was a film having no defects such as bubbles. The linear expansion coefficient of this film was 10%, and the film strength was 27 MPa.

(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 mass% aqueous dispersion of Nafion is added to and mixed with Pt-Ru alloy catalyst-supporting carbon so that the mass ratio of carbon to Nafion is 1: 1, and then n-propyl alcohol is added to water / n-propyl. The mixture was added and mixed until the alcohol mass ratio became 1/1 to prepare a uniformly dispersed paste. This paste was uniformly applied to one side of the carbon paper by a spray method. The electrode for anode was produced by drying at 130 ° C. for 30 minutes. Further, a 10% by mass solution of Nafion was added to and mixed with Pt catalyst-supporting carbon so that the mass ratio of carbon to Nafion was 1: 0.75, and then n-propyl alcohol was added to water / n-propyl alcohol. Was added and mixed until the mass ratio became 1/1, to prepare a uniformly dispersed paste, and a cathode electrode was produced 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 (electrode area is 25 cm ² ) for a molecular fuel cell was produced. The power generation characteristics under 100% humidity conditions were 2.3 mΩ for the cell characteristics and 0.50 V for the voltage. Further, the cell characteristic under a 30% humidity condition was 2.8 mΩ, and the voltage was 0.47V. The open circuit voltage was 0.97 V in the initial stage and 0.90 V after 100 hours.

<Comparative Example 1>
(Preparation of electrolyte membrane)
A 20% by mass dimethyl sulfoxide solution of the sulfonated polyetheretherketone obtained in Production Example 2 was prepared, and a thickness of about 200 μm was formed on a release-treated PET film [“Toyobo Ester Film K1504” manufactured by Toyobo Co., Ltd.]. After coating at 100 ° C. for 20 minutes, the film was peeled from the PET film to obtain a 20 μm thick film. The linear expansion coefficient of this film was 5.4%, and the film strength was 49 MPa.

(Production of single cell for polymer electrolyte fuel cell)
An evaluation cell for a polymer electrolyte fuel cell was produced in the same manner as in Example 1 except that the produced electrolyte membrane was used. The power generation characteristics under 100% humidity conditions were 2.3 mΩ for the cell characteristics and 0.50 V for the voltage. Further, the cell characteristics under a 30% humidity condition were 3.8 mΩ and the voltage was 0.38V. The open circuit voltage was 1.00 V in the initial stage and 0.97 V after 100 hours.
<Comparative example 2>
(Preparation of electrolyte membrane)
An evaluation cell for a polymer electrolyte fuel cell was prepared in the same manner as in Example 1, except that NAFION 211-CS (thickness 25 μm) manufactured by DuPont having a linear expansion coefficient of 10% and a membrane strength of 25 MPa was used as the electrolyte membrane. did. The power generation characteristics under 100% humidity conditions were 2.8 mΩ for cell characteristics and 0.58 V for voltage. Further, the cell characteristics under a 30% humidity condition were 2.8 mΩ, and the voltage was 0.58V. The open circuit voltage was 0.91 V in the initial stage and 0.85 V after 100 hours.

  Table 1 shows the performance test results of 1) to 4) regarding the electrolyte laminated film and the electrolyte film prepared in Example 1 and Comparative Examples 1 and 2.

  As can be seen from the comparison between Example 1 and Comparative Example 1, Comparative Example 1 is excellent in linear expansion coefficient, film strength and durability, but has high cell resistance, and particularly power generation performance under a relative humidity of 30%. Was low. As can be seen from the comparison between Example 1 and Comparative Example 2, Comparative Example 2 is excellent in linear expansion coefficient, film strength and power generation performance, but has low initial OCV value and low long-term durability. Met. On the other hand, it was confirmed that the electrolyte laminated film of Example 1 exhibited high power generation characteristics and excellent durability while suppressing the linear expansion coefficient and keeping the film strength high.

  From the results of the various performance tests described above, the electrolyte laminated film of the present invention has high dimensional stability, mechanical durability, and solid polymer fuel cells even in a wide range of humidity changes from low humidity to high humidity. It is a non-fluorinated electrolyte membrane that exhibits excellent output characteristics, high radical durability, and excellent performance balance. Moreover, since this laminated film is excellent also in the favorable bondability with an electrode, it can be said that the output characteristics and durability of a membrane-electrode assembly and a polymer electrolyte fuel cell using the same are excellent.

Claims (14)

  A polymer electrolyte membrane formed by laminating at least two polymer electrolyte membranes as a constituent electrolyte membrane, wherein at least one of the polymer electrolyte membranes has an ion conductive group and has an aromatic ring in the main chain A polymer electrolyte membrane (i) comprising (I) as a main component, wherein at least one of the polymer electrolyte membranes has a polymer block (A) having an ion conductive group and a heavy polymer having no ion conductive group; An electrolyte laminated film, which is a polymer electrolyte film (ii) mainly composed of a block copolymer (II) having a combined block (B) as a constituent component.   The electrolyte laminated film according to claim 1, wherein the polymer block (B) is a rubber-like polymer block (B).   The polymer (I) is polyether ketones, polyether ether ketones, polyether ketone ketones, polyphenylene sulfides, polyphenylene ethers, polysulfones, polyether sulfones, polyether ether sulfones, polyphenylene sulfones. And at least one segment selected from polyphenylene sulfoxides, polyphenylene sulfide sulfones, polyphenylene oxides, polyparaphenylenes, polybenzoxazoles, polybenzothiazoles, polybenzimidazoles, and polyimides. The electrolyte laminated film described. 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).   2. The electrolyte laminate film according to claim 1, wherein in the block copolymer (II), the polymer block (A) contains an aromatic vinyl compound unit as a main repeating unit.   The electrolyte laminated film according to claim 2, wherein the block copolymer (II) further comprises a non-rubber-like polymer block (C) having no ion conductive group. The electrolyte laminate film according to claim 6, wherein the polymer block (C) is a polymer block having an aromatic vinyl compound unit represented by the following general formula (a) as a main repeating unit.

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ^{2 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and at least one of them is an alkyl group. Represents a group)   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 diene unit having 4 to 8 carbon atoms and a carbon number. 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 electrolyte laminated film according to claim 6, wherein a mass ratio of the polymer block (C) to the polymer block (A) is 85:15 to 20:80.   The electrolyte laminated film according to claim 1, wherein a mass ratio of the polymer block (B) in the block copolymer (II) is from 5 to 95 mass%. The electrolyte laminated film according to claim 1, wherein the ion conductive group is a functional 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 electrolyte laminated film according to claim 1, wherein the thickness of the polymer electrolyte membrane (i) is 2 to 20 µm, and the thickness of the polymer electrolyte membrane (ii) is 2 to 40 µm.   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 13.