TW201538607A - Polymer electrolyte membrane - Google Patents

Abstract

A polymer electrolyte membrane obtained by molding a composition and subjecting the resulting composition to crosslinking, the composition containing a block copolymer (Z), a compound (X), and a compound (Y). The block copolymer (Z) contains a polymer block (A), which comprises structural units derived from an aromatic vinyl compound and has an ion-conductive group, and an amorphous polymer block (B), which comprises structural units derived from an unsaturated aliphatic hydrocarbon and does not have an ion-conductive group. The compound (X) has, in the molecule, two or more aromatic rings in which one or more hydrogens are substituted with a hydroxyl group, and has a structure in which adjacent aromatic rings are bonded via a C1-3 carbon chain containing at least one methylene group. The compound (Y) is represented by general formula (1). (In the formula, R1 represents a hydrogen or C1-2 alkyl group, and R2, R3, R4, R5, R6, and R7 independently represent a hydrogen, hydroxyl group, C1-4 alkyl group, or C1-4 alkoxy group.)

Description

Polymer electrolyte membrane

The present invention relates to a polymer electrolyte membrane useful for a polymer electrolyte fuel cell.

In recent years, fuel cells have attracted attention as power generation systems with high efficiency. The fuel cell is classified into a molten carbonate type, a solid oxide type, a phosphoric acid type, a solid polymer type, or the like depending on the type of the electrolyte. Among these, a structure in which a polymer electrolyte membrane is sandwiched between electrodes (anode and cathode) is provided, and a fuel containing a reducing agent (usually hydrogen or methanol) and an oxidizing agent (usually air) are supplied to the anode and the cathode, respectively. From the viewpoints of low-temperature actuation, small size and light weight, the polymer electrolyte fuel cell for power generation is now being explored for applications such as automotive power supplies, portable equipment power supplies, and household steam and electricity symbiosis systems.

As a material of the polymer electrolyte membrane used in the polymer electrolyte fuel cell, a perfluorocarbon sulfonic acid polymer is often used depending on chemical stability, but since it contains fluorine, the environmental load at the time of production and disposal is Become a topic.

According to the above, in recent years, a polymer electrolyte membrane containing a material (non-fluorine-based material) containing no fluorine is required. For example, a polymer electrolyte membrane containing a polyetheretherketone (PEEK) into which a sulfonic acid group is introduced is known (see Patent Document 1). Although the polymer electrolyte membrane is excellent in heat resistance, it is hard and brittle, so it is easily broken and has no practicality.

On the other hand, a polymer electrolyte membrane comprising a structural unit derived from an aromatic vinyl compound and comprising a block copolymer containing a polymer block having an ion conductive group and a flexible polymer block is known. (Refer to Patent Document 2). The polymer electrolyte membrane is soft and hard to be broken, and the polymer block having the ion conductive group has an ion conductive property because it is microphase-separated from the flexible polymer block to form an ion conductive channel.

On the other hand, in a polymer electrolyte fuel cell using hydrogen as a fuel, it is necessary to increase the use temperature in order to increase the output, and to raise the polymer electrolyte membrane for hot water (for example, 90 ° C or higher) in order to meet the need. The countermeasure against the durability (hot water resistance) is specifically a measure for suppressing elution of the polymer electrolyte membrane due to hot water or suppressing a voltage drop during operation for a long period of time at a high temperature.

For example, it is known that the above-mentioned flexible polymer block is used as a structural unit derived from a vinyl compound by crosslinking a block copolymer of the flexible polymer block with 1,2-polybutadiene or the like as The hot component of the polymer electrolyte membrane is improved by the main component (see Patent Document 3).

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. Hei 6-93114

Patent Document 2 International Publication No. 2006/070929

Patent Document 3 International Publication No. 2012/043400

However, in order to further increase the output of the polymer electrolyte fuel cell, there is still room for improvement in hot water resistance.

On the other hand, with the operation of the polymer electrolyte fuel cell, it is necessary to suppress an increase in the electrical resistance (membrane resistance) of the polymer electrolyte membrane (a decrease in ion conductivity).

Accordingly, an object of the present invention is to provide a polymer electrolyte membrane which is composed of a non-fluorine-based material and which is soft and hard to be broken, has good heat-resistant water, and is used in a polymer electrolyte fuel cell, and has a membrane resistance during operation. Less rise.

According to the present invention, the above object is achieved by providing a polymer electrolyte membrane comprising a block copolymer (Z) and having two or more hydrogen atoms in the molecule. a compound (X) having a structure in which a hydroxy-substituted aromatic ring and adjacent aromatic rings are bonded to each other via a carbon chain having at least one methylene group having 1 to 3 carbon atoms (hereinafter referred to as "compound (X) And a composition of the compound (Y) represented by the following formula (1) (hereinafter simply referred to as "compound (Y)") is subjected to crosslinking treatment after molding, and the block copolymer (Z) contains : a polymer block (A) having an ion conductive group derived from a structural unit derived from an aromatic vinyl compound (hereinafter referred to as "polymer block (A)"), and containing an unsaturated aliphatic group An amorphous polymer block (B) having a structural unit of a hydrocarbon and having no ion conductive group (hereinafter simply referred to as "polymer block (B)").

(wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms; and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, a hydroxyl group, and a carbon number of 1 to 4; Alkyl or alkoxy with 1 to 4 carbon atoms.)

According to the present invention, it is possible to provide a polymer electrolyte membrane which is composed of a non-fluorine-based material, which is soft and hard to be broken, has good heat-resistant water, and has a small increase in membrane resistance during operation in a solid polymer fuel cell. .

Form of implementing the invention [Polymer electrolyte membrane]

The polymer electrolyte membrane of the present invention comprises a composition comprising a block copolymer (Z) comprising a polymer block (A) and a polymer block (B), a compound (X) and a compound (Y). It is formed by cross-linking after forming.

In the polymer electrolyte membrane of the present invention, the polymer block (A) and the polymer block (B) form a micro phase separation structure. As a result, since the phase containing the polymer block (A) forms an ion conductive channel, it exhibits good ion conductivity.

Here, "microphase separation" means phase separation at a microscopic meaning, and more specifically, means that the formed domain size is phase separation of a visible light wavelength (3800 to 7800 □) or less.

It is presumed that in the composition containing the block copolymer (Z), the compound (X), and the compound (Y), the polymer block (A) and the polymer block (B) also form a micro phase separation structure, and the molecule The compound (X) having a hydroxyl group and the compound (Y) are selectively present in the phase formed by the polymer block (A) contained in the block copolymer (Z). According to the above, it is considered that the polymer electrolyte membrane of the present invention can inhibit the decomposition of the polymer block (A) without damaging the flexibility of the polymer electrolyte membrane by selectively crosslinking the polymer block (A). Further, the hot water resistance is improved, and the increase in the film resistance during the operation of the polymer electrolyte membrane in the case of using the polymer electrolyte fuel cell is suppressed.

The polymer electrolyte membrane of the present invention preferably has a thickness of 4 to 170 μm, a range of 8 to 115 μm, a range of 10 to 70 μm, and a range of 12 to 50 μm from the viewpoint of mechanical strength and handleability. optimal. When the film thickness is 4 μm or more, the mechanical strength of the polymer electrolyte membrane or the fuel barrier property is good. When the film thickness is 170 μm or less, the ion conductivity of the polymer electrolyte membrane is good.

The polymer electrolyte membrane of the present invention may further comprise a block copolymer comprising a polymer block (A) and a polymer block (B). A multilayer film of at least one polymer electrolyte layer obtained by subjecting the composition of (Z), the compound (X) and the compound (Y) to a crosslinking treatment after molding.

(block copolymer (Z))

Block copolymer (Z) block copolymer by lines (Z ₀₎ of the polymer block (A ₀₎ obtained by introducing ion-conducting groups, which block copolymer (Z ₀₎ comprising: comprising from The polymer block (A ₀ ) (hereinafter simply referred to as "polymer block (A ₀ )") and the polymer block (B) having no ion conductive group in the structural unit of the aromatic vinyl compound.

The number average molecular weight (Mn) of the block copolymer (Z ₀ ) is not particularly limited, but is usually preferably in the range of 10,000 to 300,000, more preferably in the range of 15,000 to 250,000, and particularly preferably in the range of 40,000 to 200,000, and 70,000 to 180,000. The best range. When the Mn of the block copolymer (Z ₀ ) is 10,000 or more, particularly 70,000 or more, the polymer electrolyte membrane of the present invention has high tensile elongation at break properties; when it is 300,000 or less, particularly 180,000 or less, the present invention is high. The above composition of the molecular electrolyte membrane is excellent in moldability and is also advantageous in production. In the present specification, Mn means a standard polystyrene equivalent value measured by a gel permeation chromatography (GPC) method.

The ion exchange capacity of the block copolymer (Z) is preferably in the range of 0.4 to 4.5 meq/g, more preferably in the range of 0.8 to 3.2 meq/g, and particularly preferably in the range of 1.3 to 3.0 meq/g, and 1.8 to 2.8 meq/ The range of g is the best. In the polymer electrolyte membrane of the present invention, the ion exchange capacity is 0.4 meq/g or more, and the ion conductivity is good, and it is not easily swollen by being 4.5 meq/g or less. The ion exchange capacity of the block copolymer (Z) can be calculated by an acid value titration method.

Further, the block copolymer (Z) may have one polymer block (A) and one polymer block (B), respectively, or may have a plurality of them. When the plurality of polymer blocks (A) are provided, the structures (the types of the structural units, the degree of polymerization, the type of the ion conductive groups, the introduction ratio, and the like) may be the same or different. Further, when a plurality of polymer blocks (B) are provided, the structures (types of structural units, degree of polymerization, etc.) may be the same or different.

The bonding arrangement of the polymer block (A) and the polymer block (B) in the block copolymer (Z) is not particularly limited. Further, the polymer block (A) and the polymer block (B) may be side chains, that is, the block copolymer (Z) used in the present invention contains a graft copolymer.

Examples of the bonding arrangement of the polymer block (A) and the polymer block (B) in the block copolymer (Z) include AB type diblock copolymers (A and B respectively represent polymerization). Block (A), polymer block (B), the same as below), ABA type triblock copolymer, BAB type triblock copolymer, ABAB type tetrablock copolymer, ABABA type pentablock copolymer , BABAB-type pentablock copolymer, (AB) _n D-type star copolymer (D represents a coupling agent residue, n represents an integer of 2 or more. The same applies hereinafter), (BA) _n D-type star copolymer, etc. From the viewpoint of mechanical strength and ion conductivity, an ABA type triblock copolymer, an ABABA type pentablock copolymer, an (AB) _n D type star copolymer is preferable, and an ABA type triblock copolymer is more preferable. In the polymer electrolyte membrane of the present invention, the block copolymers may be used alone or in combination of two or more.

In the block copolymer (Z ₀ ), (the total amount of the polymer blocks (A ₀ )): (the total amount of the polymer blocks (B)), in a mass ratio of 95:5 to 5:95 The range is better, the range of 75:25~15:85 is better, the range of 65:35~20:80 is particularly good, and the range of 50:50~25:75 is the best. When the mass ratio is in the range of 95:5 to 5:95, particularly in the range of 50:50 to 25:75, the polymer electrolyte membrane of the present invention is in ion conductivity, mechanical strength, and accompanying solid polymer fuel cell. There is a tendency to be excellent in the durability (starting stop durability) at the time of starting and stopping and repeating wetting and drying.

<Polymer block (A)>

The polymer block (A) can be formed by introducing an ion conductive group into the polymer block (A ₀ ). The ion conductive group is usually introduced into the aromatic ring of the polymer block (A ₀ ).

The polymer block (A ₀ ) contains a structural unit derived from an aromatic vinyl compound, and the aromatic ring of the aromatic vinyl compound is preferably a carbocyclic aromatic ring such as a benzene ring, a naphthalene ring, an anthracene ring or an anthracene ring. More preferably, it is a benzene ring.

Examples of the aromatic vinyl compound capable of forming the above polymer block (A ₀ ) include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, and 4-ethylidene. Styrene, 2,3-dimethylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2-methoxybenzene Ethylene, 3-methoxystyrene, 4-methoxystyrene, ethylene biphenyl, ethylene terphenyl, vinyl naphthalene, vinyl anthracene, 4-phenoxystyrene, and the like.

Further, among the hydrogen atoms on the vinyl group of the aromatic vinyl compound, a hydrogen atom bonded to the α-position of the aromatic ring (α-carbon) may be substituted with another substituent. Examples of the substituent include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and second butyl group. An alkyl group having 1 to 4 carbon atoms such as a tributyl group; a halogenated alkyl group having 1 to 4 carbon atoms such as a chloromethyl group, a 2-chloroethyl group or a 3-chloroethyl group; or a phenyl group. Examples of the aromatic vinyl compound in which a hydrogen atom bonded to an α-carbon is substituted by such a substituent include α-methylstyrene, α-methyl-4-methylstyrene, and α-methyl-2. -methylstyrene, α-methyl-4-ethylstyrene, 1,1-diphenylethylene, and the like.

Among the above aromatic vinyl compounds which can form the polymer block (A ₀ ), styrene, α-methylstyrene, 4-methylstyrene, 4-ethylstyrene, α-methyl-4-methyl Styrene, α-methyl-2-methylstyrene, ethylene biphenyl and 1,1-diphenylethylene are preferred, styrene, α-methylstyrene, 4-methylstyrene and 1, 1-Diphenylethylene is more preferred, and styrene and α-methylstyrene are particularly preferred.

The polymer block (A ₀ ) can be formed by polymerizing one type of these aromatic vinyl compounds as a monomer or by polymerizing two or more types. The copolymerization form in which two or more kinds of aromatic vinyl compounds are used in combination is preferably a random copolymerization.

The polymer block (A ₀ ) in the present invention may contain one or more kinds of other structural units other than the aromatic vinyl compound, within a range not impairing the effects of the present invention. Examples of the monomer capable of forming the other structural unit include butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, and 2,3-dimethyl- a conjugated diene having 4 to 8 carbon atoms such as 1,3-butadiene, 2-ethyl-1,3-butadiene or 1,3-heptadiene; ethylene, propylene, 1-butene, Alkene having a carbon number of 2 to 8 such as isobutylene, 1-pentene, 1-hexene, 1-heptene or 1-octene; methyl (meth)acrylate or ethyl (meth)acrylate; (meth) acrylate such as butyl (meth) acrylate; vinyl ester of vinyl acetate, vinyl propionate, vinyl butyrate, trimethyl vinyl acetate; methyl vinyl ether, isobutyl ethylene a vinyl ether such as ether. In this case, it is preferred that the copolymerization form of the other monomer and the above aromatic vinyl compound is random copolymerization. These other structural units are preferably 5 mol% or less of the structural unit forming the polymer block (A ₀ ). That is, in the structural unit forming the polymer block (A ₀ ), 95 mol% or more is preferably a structural unit derived from an aromatic vinyl compound.

The Mn of each of the polymer blocks (A ₀ ) is preferably in the range of 1,000 to 100,000, more preferably in the range of 2,000 to 70,000, particularly preferably in the range of 4,000 to 50,000, and most preferably in the range of 6,000 to 30,000. In the polymer electrolyte membrane of the present invention, when the Mn is 1,000 or more, particularly 6,000 or more, the ion conductivity is improved, and when it is 100,000 or less, particularly 30,000 or less, the hot water resistance is improved, and the polymer electrolyte of the present invention is formed. The above composition of the film is excellent in moldability and is also advantageous in production.

As the ion conductive group which the polymer block (A ₀ ) has, the proton conductive group is preferably selected from -SO ₃ M or PO ₃ HM (wherein M represents a hydrogen atom, an ammonium ion or an alkali metal ion) The sulfonic acid group, the phosphonic acid group, and the above-mentioned salts are more preferably one or more, and the sulfonic acid group is particularly preferred.

<Polymer block (B)>

The polymer block (B) is an amorphous polymer block containing a structural unit derived from an unsaturated aliphatic hydrocarbon and having no ion conductive group. Further, the amorphous state of the polymer block (B) was measured for the dynamic viscoelasticity of the block copolymer (Z), and was confirmed by the change in the storage elastic modulus derived from the crystalline olefin polymer.

Examples of the unsaturated aliphatic hydrocarbon which can form the above polymer block (B) include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-heptene, and 1-octyl. a olefin having a carbon number of 2 to 8 such as an alkene; an ethylene cyclohexane having a carbon number of 7 to 10 such as ethylene cyclopentane, ethylene cyclohexane, ethylene cycloheptane or ethylene cyclooctane; ethylene cyclopentene and ethylene cyclohexane a vinylcycloolefin having 7 to 10 carbon atoms such as an alkene, an ethylene cycloheptene or an ethylene cyclooctene; butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2, a conjugated diene having a carbon number of 4 to 8 such as 3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene or 1,3-heptadiene; a conjugated cycloalkadiene having 5 to 8 carbon atoms such as an olefin or a 1,3-cyclohexadiene, and preferably ethylene, propylene, 1-butene, isobutylene, 1-pentene, and 1 a olefin having 2 to 8 carbon atoms such as hexene, 1-heptene or 1-octene; butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2, More preferably, the conjugated diene having 4 to 8 carbon atoms such as 3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene or 1,3-heptadiene is more preferably Further, the olefin having 4 to 8 carbon atoms and the conjugated diene having 4 to 8 carbon atoms are further preferably different. Butylene, butadiene and isoprene, particularly preferably butadiene and isoprene. These unsaturated aliphatic hydrocarbons are polymerized as a single monomer or polymerized in two or more kinds to form a polymer block (B). The copolymerization form in which two or more kinds of unsaturated aliphatic hydrocarbons are used together is preferably a random copolymerization.

Further, the polymer block (B) may contain a non-source within a range of use temperature region without impairing the effect of imparting flexibility to the polymer block (B) to the block copolymer (Z). Other structural units from unsaturated aliphatic hydrocarbons. Examples of the monomer which can form the other structural unit include an aromatic vinyl compound such as styrene or vinyl naphthalene; a halogen-containing vinyl compound such as vinyl chloride; vinyl acetate or vinyl propionate; Vinyl esters such as vinyl butyrate and trimethyl vinyl acetate; vinyl ethers such as methyl vinyl ether and isobutyl vinyl ether. In this case, it is preferred that the copolymerization form of the other monomer and the above unsaturated aliphatic hydrocarbon is random copolymerization. These other structural units are preferably 5 mol% or less of the structural unit forming the polymer block (B). That is, in the structural unit forming the polymer block (B), 95 mol% or more is preferably a structural unit derived from an unsaturated aliphatic hydrocarbon.

When the unsaturated aliphatic hydrocarbon has a plurality of carbon-carbon double bonds, it can be used for polymerization. For example, in the case of a conjugated diene, it may be a 1,2-bond or a 1,4-bond. Either. In the polymer block (B) in which the conjugated diene is polymerized, a carbon-carbon double bond is usually left. However, from the viewpoint of improving the heat deterioration resistance of the obtained polymer electrolyte membrane, etc., it is preferred to block After the polymerization of the copolymer (Z ₀ ), a hydrogenation reaction (hereinafter referred to as "hydrogenation reaction") is carried out, and the carbon-carbon double bond is hydrogenated (hereinafter referred to as "hydrogenation"). The hydrogenation rate of the carbon-carbon double bond (hereinafter referred to as "hydrogenation rate") is preferably 30 mol% or more, more preferably 50 mol% or more, and particularly preferably 95 mol% or more.

Further, when the ion conductive group is introduced into the block copolymer (Z) after polymerizing the block copolymer (Z ₀ ), the polymer block (B) is a saturated hydrocarbon structure, and the ion conductive group is polymerized. The introduction of the block (B) is less likely to occur, which is preferable. Therefore, when the hydrogenation reaction of the carbon-carbon double bond remaining in the polymer block (B) is carried out after the polymerization of the block copolymer (Z ₀ ), it is preferably carried out before introducing the ion conductive group.

Further, the hydrogenation ratio of the carbon-carbon double bond can be calculated from ¹ H-NMR measurement.

The Mn of each of the polymer blocks (B) is preferably in the range of 5,000 to 250,000, more preferably in the range of 7,000 to 200,000, particularly preferably in the range of 15,000 to 150,000, and most preferably in the range of 30,000 to 100,000. When the Mn is 5,000 or more, particularly 30,000 or more, the polymer electrolyte membrane of the present invention is particularly excellent in mechanical strength and start-stop durability, and when Mn is 250,000 or less, particularly 100,000 or less, the polymer of the present invention is formed. The above composition of the electrolyte membrane is excellent in formability and is also advantageous in production.

<Other polymer blocks (C)>

The block copolymer (Z) may further include a polymer block (C) containing a structural unit derived from an aromatic vinyl compound and having no ion conductive group (hereinafter referred to as "polymer block (C)" ). In the polymer electrolyte membrane of the present invention, the polymer block (C) forms a microphase-separated structure with the polymer block (A) and the polymer block (B).

From the viewpoint of manufacturing advantages, the polymer block (C) preferably contains a structural unit derived from an aromatic vinyl compound represented by the following formula (2).

(wherein R ⁸ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R ⁹ represents an alkyl group having 3 to 8 carbon atoms; and R ¹⁰ and R ¹¹ each independently represent a hydrogen atom or an alkane having 3 to 8 carbon atoms; base.)

When the polymer block (C) is a structural unit derived from an aromatic vinyl compound having at least one alkyl group having 3 to 8 carbon atoms in the aromatic ring, an ion conductive group is introduced into the block copolymer (Z ₀ ). On the other hand, when the block copolymer (Z) is produced, an ion conductive group can be selectively introduced into the polymer block (A ₀ ).

Examples of the aromatic vinyl compound for forming the structural unit represented by the above formula (2) include 4-propylstyrene, 4-isopropylstyrene, 4-butylstyrene, and 4-isobutylene. Styrene, 4-tert-butylstyrene, 4-octylstyrene, α-methyl-4-tert-butylstyrene, α-methyl-4-isopropylstyrene, etc. Preferably, it is 4-tert-butylstyrene, 4-isopropylstyrene, α-methyl-4-tert-butylstyrene, α-methyl-isopropylstyrene, and further preferably 4- Third butyl styrene. These may be used alone or in combination of two or more. When the polymer block (C) is formed by using two or more kinds, the copolymerization form is preferably a random copolymerization.

The polymer block (C) may contain one or more kinds of other structural units other than the aromatic vinyl compound, within a range not impairing the effects of the present invention. Examples of the monomer capable of forming the other structural unit include butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, and 2,4-hexadiene. a conjugated diene having 4 to 8 carbon atoms such as 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene or 1,3-heptadiene; ethylene a olefin having 2 to 8 carbon atoms such as propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-heptene or 1-octene; methyl (meth)acrylate, (methyl) a (meth) acrylate such as ethyl acrylate or butyl (meth) acrylate; a vinyl ester of vinyl acetate, vinyl propionate, vinyl butyrate or trimethyl vinyl acetate; methyl vinyl ether a vinyl ether such as isobutyl vinyl ether. In this case, it is preferred that the copolymerization form of the other monomer and the above aromatic vinyl compound is random copolymerization. These other structural units are preferably 5 mol% or less of the structural unit forming the polymer block (C). That is, in the structural unit forming the polymer block (C), 95 mol% or more is preferably a structural unit derived from an aromatic vinyl compound.

The Mn of each of the polymer blocks (C) is usually in the range of preferably 1,000 to 50,000, more preferably in the range of 1,500 to 30,000, and particularly preferably in the range of 2,000 to 20,000. When the Mn is 1,000 or more, the polymer electrolyte membrane of the present invention tends to have excellent mechanical strength, and when it is 50,000 or less, the above-described composition of the polymer electrolyte membrane of the present invention is formed, and the moldability is excellent, and the production is also excellent. advantageous.

An example of the arrangement when the block copolymer (Z) used in the present invention contains the polymer block (C) is an ABC type triblock copolymer (A, B, and C respectively represent a polymer block ( A), polymer block (B), polymer block (C). The same applies below), ABCA type tetrablock copolymer, ABAC type tetrablock copolymer, BABC type tetrablock copolymer, ABCB type four Block copolymer, ACBC type tetrablock copolymer, CABAC type pentablock copolymer, CBABC type pentablock copolymer, ACBCA type pentablock copolymer, ACBAC type pentablock copolymer, ACBCAC type hexa block Copolymer, CABCAC type hexablock copolymer, ACACBC type hexablock copolymer, ACACBCA type seven block copolymer, ACBCBCA type seven block copolymer, CACBCAC type seven block copolymer, ACACBCAC type octa block copolymer , ACBCBCAC type octa block copolymer, ACBCACBC type octa block copolymer, and the like. Among them, from the viewpoint of mechanical strength and ion conductivity, an ABC type triblock copolymer, an ABCA type tetrablock copolymer, an ABAC type tetrablock copolymer, an ACBC type tetrablock copolymer, and a CABAC type five are preferable. Block copolymer, CBABC type pentablock copolymer, ACBCA type pentablock copolymer, ACBAC type pentablock copolymer, ACBCAC type hexablock copolymer, CABCAC type hexablock copolymer, ACACBC type hexa block Copolymer, ACACBCA type seven block copolymer, ACBCBCA type seven block copolymer, CACBCAC type seven block copolymer, ACACBCAC type octa block copolymer, ACBCBCAC type octa block copolymer, ACBCACBC type octa block copolymer More preferably, it is an ACBC type tetrablock copolymer, an ACBCA type pentablock copolymer, an ACBCAC type hexablock copolymer, an ACACBCAC type octa block copolymer, and further preferably an ACBCA type pentablock copolymer, ACACBCAC type. Octa block copolymer. In the polymer electrolyte membrane of the present invention, the block copolymers may be used alone or in combination of two or more.

When the block copolymer (Z) constituting the polymer electrolyte membrane of the present invention contains the polymer block (C), the block copolymer (Z ₀ ) occupies a polymer block (C) in an amount of 5 to 50. The range of % by mass is better, the range of 7 to 40% by mass is more preferable, and the range of 10 to 30% by mass is particularly preferable. When the content is 5% by mass or more, the obtained polymer electrolyte membrane tends to be excellent in hot water resistance, and when it is 50% by mass or less, the polymer electrolyte membrane obtained tends to have excellent start-stop durability.

<Manufacture of block copolymer (Z ₀ )>

The block copolymer (Z) constituting the polymer electrolyte membrane of the present invention can be produced by polymerizing the above monomers to produce a block copolymer comprising a polymer block (A ₀ ) and a polymer block (B). After the substance (Z ₀ ), a method of introducing an ion conductive group into the polymer block (A ₀ ) is carried out.

The method for producing the block copolymer (Z ₀ ) can be appropriately selected, but it is preferred to polymerize the above monomers by a polymerization method selected from a living radical polymerization method, a living anionic polymerization method and a living cationic polymerization method. The method.

As a specific example of the method for producing the block copolymer (Z ₀ ), a polymer block (A ₀ ) containing a structural unit derived from an aromatic vinyl compound and a structural unit derived from a conjugated diene are produced. The method in which the polymer block (B) is a block copolymer (Z ₀ ) of the component includes (1) using an anionic polymerization initiator in a cyclohexane solvent at a temperature of 20 to 100 ° C. Under the conditions, an aromatic vinyl compound, a conjugated diene, and an aromatic vinyl compound are successively anionized to obtain an ABA type block copolymer; (2) an anionic polymerization initiator is used in a cyclohexane solvent, a method in which an aromatic vinyl compound or a conjugated diene is subjected to anion polymerization successively at a temperature of 20 to 100 ° C, and then a coupling agent such as phenyl benzoate is added to obtain an ABA type block copolymer; (3) In the non-polar solvent, an organolithium compound is used as a starter, and an aromatic vinyl compound having a concentration of 5 to 50% by mass is carried out at a temperature of -30 to 30 ° C in the presence of a polar compound having a concentration of 0.1 to 10% by mass. Anionic polymerization and conjugated diene with the resulting work Anionic polymer after polymerization, phenyl benzoate and the like of the coupling agent, a method to obtain an ABA type block copolymer.

Further, a block copolymer (Z ₀ ) containing a polymer block (A ₀ ) derived from a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from isobutylene as a component is produced. (4) In a halogen-based/hydrocarbon mixed solvent, a bifunctional halogenated initiator is used at -78 ° C, and isobutylene is cationically polymerized in the presence of Lewis acid to impart aroma. A method in which a group of vinyl compounds is subjected to cationic polymerization to obtain an ABA type block copolymer.

Further, the polymer block (C) may be added as a component of the block copolymer depending on the component which is changed or additionally reacted in the above anionic polymerization or cationic polymerization.

<Manufacture of block copolymer (Z)>

The method for producing the block copolymer (Z) by introducing an ion conductive group into the block copolymer (Z ₀ ) will be described below.

First, a method of introducing a sulfonic acid group into the block copolymer (Z ₀ ) will be described. Introduction of a sulfonic acid group (sulfonation) can be carried out by a known method. For example, a solution or suspension of an organic solvent for preparing a block copolymer (Z ₀ ), a method of adding a sulfonating agent described later to the solution or suspension, or a method of directly mixing the block copolymer (Z ₀ ) A method of adding a gaseous sulfonating agent.

As the sulfonating agent, sulfuric acid; a mixture of sulfuric acid and an acid anhydride; chlorosulfonic acid; a mixture of chlorosulfonic acid and trimethylchlorodecane; sulfur trioxide; a mixture of sulfur trioxide and triethyl phosphate; , 4,6- An aromatic organic sulfonic acid represented by trimethylbenzenesulfonic acid. Among them, a mixture of sulfuric acid and an acid anhydride is preferred. In addition, examples of the organic solvent to be used include a halogenated hydrocarbon such as dichloromethane, a linear aliphatic hydrocarbon such as hexane, a cyclic aliphatic hydrocarbon such as cyclohexane, or an aromatic having an electron attracting group such as nitrobenzene. Family compounds, etc.

Next, a method of introducing a phosphonic acid group in the block copolymer (Z ₀ ) will be described. The introduction of a phosphonic acid group (phosphonation) can be carried out by a known method. For example, in the aromatic ring of the polymer block (A ₀ ), the halomethyl ether is reacted in the presence of aluminum chloride to introduce a halomethyl group, followed by reaction with phosphorus trichloride and aluminum chloride. a phosphorus derivative, followed by a method of converting to a phosphonic acid group by hydrolysis; and an aromatic ring of the above aromatic vinyl compound, reacting phosphorus trichloride with anhydrous aluminum chloride, and using the introduced phosphinic acid group with nitric acid A method of oxidative conversion to a phosphonic acid group.

The introduction rate (sulfonation ratio, phosphine ratio, etc.) of the ion conductive group derived from the structural unit derived from the aromatic vinyl compound of the polymer block (A) in the block copolymer (Z) can be used. ¹ H-NMR was calculated.

<compound (X)>

The compound (X) is an aromatic ring having two or more hydrogen atoms substituted by a hydroxyl group in the molecule, and has a carbon chain of 1 to 3 carbon atoms having at least one methylene group interposed therebetween. And the compound of the bonded structure. Here, the carbon number of the carbon chain means the number of carbon atoms forming the main chain of the carbon chain located between the adjacent aromatic rings.

It is presumed that since the compound (X) has the above structure, it is selectively present in the phase containing the hydrophilic polymer block (A), and therefore it is considered that the hydrophilic polymer block (A) is selectively exchanged. The joint does not damage the softness of the polymer electrolyte membrane and enhance the hot water resistance.

The aromatic ring of the compound (X) is preferably a hydrocarbon-based aromatic ring such as a benzene ring, a naphthalene ring or an anthracene ring, and the benzene ring is more preferable.

Further, when the aromatic ring is a benzene ring, one or more hydrogen atoms of the benzene ring are substituted by a hydroxyl group, but when the carbon on the benzene ring to which the hydroxyl group is bonded is taken as one position, the two, four, and six positions are It is preferable that at least one of the carbons has a substituent, and it is more preferable that the carbon at the 4-position has a methyl group from the viewpoint of improving the tensile elongation at break and the tensile breaking strength of the polymer electrolyte membrane.

Specific examples of the compound (X) include 5,5'-methylenebis(2-hydroxybenzoic acid), bis(2-hydroxyphenyl)methane, bis(4-hydroxyphenyl)methane, and 2 , 2'-methylenebis(6-tert-butyl-4-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), bis(4-hydroxyl) -3,5-dimethylphenyl)methane, 2,6-bis(4-hydroxy-3,5-dimethylbenzyl)-4-cresol, 2,6-bis(2-hydroxy-5-methyl Benzyl)-4-methylphenol, 2,6-bis(2,4-dihydroxybenzyl)-4-cresol, 6,6'-bis(2-hydroxy-5-methylbenzyl)- 4,4'-dimethyl-2,2'-methylene diphenol, poly-2-vinylphenol, poly-3-vinylphenol, poly-4-vinylphenol, poly-2-hydroxy-5-ethylene Benzenesulfonic acid, calix[4]arene, calix[6]arene, 1,1,3-glycol(2-methyl-4-hydroxy-5-t-butylphenyl)butane, and the like.

Wherein, selected from bis(2-hydroxyphenyl)methane, bis(4-hydroxyphenyl)methane, 2,2'-methylenebis(6-tert-butyl-4-cresol), 2, 2'-methylenebis(6-tert-butyl-4-ethylphenol), 1,1,3-glycol(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 2,6-bis(4-hydroxy-3,5-dimethylbenzyl)-4-cresol, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, 2 ,6-bis(2,4-dihydroxybenzyl)-4-cresol, calix[4]arene, 6,6'-bis(2-hydroxy-5-methylbenzyl)-4,4'- a compound of dimethyl-2,2'-methylene diphenol, calix[6]arene, poly-2-vinylphenol, poly-3-vinylphenol, poly-4-vinylphenol is preferably selected from 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, 2,6-bis(2,4-dihydroxybenzyl)-4-cresol, 6,6'-double (2-hydroxy-5-methylbenzyl)-4,4'-dimethyl-2,2'-methylene diphenol, poly-2-vinylphenol, poly-3-vinylphenol, poly-4 - A compound of vinyl phenol is more preferred.

The compound (X) may be used alone or in combination of two or more. When the compound (X) is used in combination, it is preferably used, and at least one compound having at least one aromatic ring having one or more hydrogen atoms substituted by a hydroxyl group in the molecule is preferably used. More preferably, two or more kinds are used. As a specific compound (X), a combination of poly-4-vinylphenol and 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, poly-4-vinylphenol and 2 The combination of 6-bis(2,4-dihydroxybenzyl)-4-cresol is preferred.

The amount of the compound (X) is preferably from 0.01 to 25 parts by mass, and from 0.2 to 20 parts by mass, per 100 parts by mass of the block copolymer (Z), from the viewpoint of the hot water resistance of the polymer electrolyte membrane. The range is better, the range of 0.3 to 15 parts by mass is particularly good, and the range of 1 to 12 parts by mass is the best. Further, from the viewpoint of improving the hot water resistance and the ion conductivity, and the crosslinking density is likely to be in a preferable range, the number of moles of the aromatic ring in which one or more hydrogen atoms of the compound (X) are substituted with a hydroxyl group is relative to 100 moles. The ion conductive group of the block copolymer (Z) of the ear is preferably in the range of 0.1 to 70 moles, more preferably in the range of 0.5 to 60 moles, and particularly preferably in the range of 0.8 to 50 moles. The range of 3~38 moles is the best.

The compound (Y) is a compound represented by the following formula (1).

(wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms; and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, a hydroxyl group, and a carbon number of 1 to 4; Alkyl or alkoxy with 1 to 4 carbon atoms.)

It is considered that the compound (Y) has a function of improving the oxidation stability of the block copolymer (Z). It is considered that the compound (Y) is selectively present in the phase containing the hydrophilic polymer block (A) by the above structure, and by suppressing the use of the polymer electrolyte membrane for the solid polymer fuel cell The deterioration caused by the oxidation of the polymer block (A) during the operation can suppress the increase in the film resistance.

Specific examples of the compound (Y) include 2,2',2"-trihydroxytriphenylmethane, 2,2',4"-trihydroxytriphenylmethane, and 2,4',4"-trihydroxyl group. Triphenylmethane, 4,4',4"-trihydroxytriphenylmethane, 2,4',4"-trihydroxy-3',3"-dimethyltriphenylmethane, 4,4',3", 4"-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 3-methoxy-4,4',4"-trihydroxytriphenylmethane, 3-ethoxy-4 , 4',4"-trihydroxytriphenylmethane, 1,1,1-cis (2-hydroxyphenyl)ethane, 4-[1,1-bis(2-hydroxyphenyl)ethyl]-phenol 2-[1,1-bis(4-hydroxyphenyl)ethyl]-phenol, 1,1,1-cis (4-hydroxyphenyl)ethane, and the like.

Among them, 4,4',4"-trihydroxytriphenylmethane and 1,1,1-cis-(4-hydroxyphenyl)ethane are preferred. These may be used alone or in combination of two or more.

The increase in membrane resistance during operation when the polymer electrolyte membrane is used in a polymer electrolyte fuel cell is suppressed, and ion transmission is improved. The amount of the compound (Y) is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and 0.3 to 15 parts by mass, based on 100 parts by mass of the block copolymer (Z). The range of 10 parts by mass is particularly good, and the range of 0.5 to 8 parts by mass is the best.

<Method for Producing Polymer Electrolyte Membrane>

Next, a method of producing the polymer electrolyte membrane of the present invention will be described. In general, a polymer electrolyte membrane is prepared by preparing a fluid composition including a block copolymer (Z), a compound (X), a compound (Y) and a solvent as a polymer electrolyte, and applying the fluid composition to a substrate or the like. Thereafter, the solvent is removed to obtain a film-shaped formed body comprising a composition containing the block copolymer (Z), the compound (X) and the compound (Y), and obtained by crosslinking the molded body.

Examples of the solvent which can be used in the fluid composition include halogenated hydrocarbons such as dichloromethane; aromatic hydrocarbons such as toluene, xylene, and benzene; and linear aliphatic hydrocarbons such as hexane, heptane, and octane. a cyclic aliphatic hydrocarbon such as cyclohexane; an ether such as tetrahydrofuran; an alcohol such as methanol, ethanol, propanol, isopropanol, butanol or isobutanol. These may be used alone or in combination of two or more. From the viewpoint of solubility or dispersibility of the polymer block contained in each block copolymer (Z), a mixed solvent is preferably used. The mixed solvent of a preferred combination includes a mixed solvent of toluene and isobutanol, a mixed solvent of xylene and isobutanol, a mixed solvent of toluene and isopropyl alcohol, and a mixed solvent of cyclohexane and isopropyl alcohol. a mixed solvent of cyclohexane and isobutanol, a tetrahydrofuran solvent, a mixed solvent of tetrahydrofuran and methanol, a mixed solvent of toluene and isobutanol and octane, a mixed solvent of toluene and isopropyl alcohol and octane, and toluene and different Mixed solvent of butanol, A mixed solvent of xylene and isobutanol, a mixed solvent of toluene and isopropyl alcohol, a mixed solvent of toluene and isobutanol and octane, and a mixed solvent of toluene and isopropyl alcohol and octane are more preferable.

The fluid composition is prepared by dissolving or dispersing the block copolymer (Z), the compound (X) and the compound (Y) in a solvent. A stabilizer such as a softening agent, a sulfur-based stabilizer, or a phosphorus-based stabilizer, an inorganic filler, a light stabilizer, an antistatic agent, a release agent, or the like may be used in combination as needed within the range that does not impair the effects of the present invention. Various additives such as flame retardants, foaming agents, pigments, dyes, bleaches, carbon fibers, etc. are dissolved or dispersed. The content of the block copolymer (Z) in the component (solid content) other than the solvent in the fluid composition is preferably from 50 to 99.98 mass%, preferably from the viewpoint of the ion conductivity of the obtained polymer electrolyte membrane. 98% by mass is better, and 85 to 95% by mass is particularly good.

Examples of the softening agent which can be used in the fluid composition include petroleum-based softeners such as paraffin-based, naphthenic-based, and aromatic-based processing oils; fluid paraffin, vegetable oil-based softeners, and plasticizers. These may be used alone or in combination of two or more.

Examples of the stabilizer which can be used for the fluid composition include pentaerythritol strontium (3-lauryl thiopropionate), distearyl 3,3'-thiodipropionate, and dilauryl. a sulfur-based stabilizer such as 3,3'-thiodipropionate or dimyristyl 3,3'-thiodipropionate; ginsylphenylphosphite, ginseng (2,4-di) A phosphorus-based stabilizer such as tributylphenyl)phosphite or distearyl pentaerythritol diphosphite. These may be used alone or in combination of two or more.

Examples of the inorganic filler which can be used in the fluid composition include talc, calcium carbonate, cerium oxide, glass fiber, mica, kaolin, titanium oxide, montmorillonite, and alumina. These may be used alone or in combination of two or more.

The concentration of the block copolymer (Z) in the fluid composition can be appropriately selected depending on the molecular weight, composition, and ion exchange group capacity, but from the viewpoint of productivity, it is preferably from 5 to 20% by mass.

The fluid composition is usually applied onto a smooth substrate made of polyester (PET, PEN, etc.) or glass, using a coater or an applicator.

Further, the fluid composition may be applied to a porous substrate (porous substrate) by a dip-nip method, a method using a coater or an applicator, or the like. In this case, usually at least a part of the fluid composition is impregnated into the porous substrate. The porous substrate impregnated with at least a part of the fluid composition exhibits a function as a reinforcing material by forming a part of the polymer electrolyte membrane after crosslinking. As the porous substrate, a fibrous substrate such as a woven fabric or a non-woven fabric, or a film-form substrate having a fine through-hole can be used. Examples of the film-form substrate include a film for pore filling of a fuel cell. From the viewpoint of strength, the porous substrate is preferably a fibrous substrate, and the nonwoven fabric is more preferable. Examples of the fibers constituting the fibrous substrate include aramid fibers, glass fibers, cellulose fibers, nylon fibers, vinylon fibers, polyester fibers, polyolefin fibers, and rayon fibers. From the viewpoint of the above, a wholly aromatic polyester fiber or an aramid fiber is preferable, and a wholly aromatic liquid crystal polyester fiber is particularly preferable.

After the fluid composition is applied onto the substrate as described above, the solvent is removed to form a film. The temperature at which the solvent is removed can be arbitrarily selected in a range in which the block copolymer (Z) does not decompose, and a plurality of temperatures can be arbitrarily combined. Specifically, it can be carried out under ventilating conditions, under vacuum conditions, or the like, or any combination thereof. Specifically, a method of removing the solvent by drying in a hot air dryer at 60 to 120 ° C for 4 minutes or more is used, and a method of removing the solvent by drying in a hot air dryer at 120 to 140 ° C for 2 to 4 minutes; After drying for 1 to 3 hours at °C, it is dried in a hot air dryer at 80~120 °C for 5~10 minutes; after drying at 25 °C for 1-3 hours, in an atmosphere of 25~40 °C, Drying under reduced pressure for 1 to 12 hours.

From the viewpoint of easily preparing a polymer electrolyte membrane having good toughness, the solvent can be suitably removed by drying in a hot air dryer at 60 to 120 ° C for 4 minutes or more; and drying at 25 ° C for 1 to 3 After the hour, the method is dried in a hot air dryer at 80 to 120 ° C for 5 to 10 minutes; after drying at 25 ° C for 1 to 3 hours, the pressure is reduced to 1.3 kPa or less in an atmosphere of 25 to 40 ° C. The method of drying for 1 to 12 hours under conditions.

When the polymer electrolyte membrane is used as a multilayer film, for example, after the fluid composition is applied onto a substrate, the solvent is removed to form a first layer, and then another polymer electrolyte is applied to the first layer. The composition was removed by a solvent to form a second layer. Similarly, the third layer or more can be formed. Further, a polymer electrolyte membrane produced separately may be bonded to form a multilayer film.

The polymer electrolyte membrane of the present invention can be formed by applying the fluid composition to a substrate and crosslinking the film-form molded body obtained by removing the solvent. As the crosslinking method, active energy ray irradiation such as heating or electron beam can be suitably employed. Further, the crosslinking by the heating or the active energy ray irradiation may be carried out simultaneously with the removal of the solvent, or may be carried out after the removal of the solvent. Further, after crosslinking by heating or active energy ray irradiation and simultaneous removal of the solvent, heating or active energy ray irradiation may be further performed.

When the crosslinking is carried out by heating, the heating temperature is preferably 50 to 250 ° C, more preferably 60 to 200 ° C, particularly preferably 70 to 180 ° C, and most preferably 100 to 150 ° C. Further, the heating time is preferably from 0.1 to 400 hours, more preferably from 0.2 to 200 hours, particularly preferably from 0.4 to 100 hours, and most preferably from 0.5 to 30 hours. The heating can be carried out under the atmosphere, in a nitrogen atmosphere, or the like, and is preferably carried out under a nitrogen atmosphere.

When the active energy ray is irradiated with, for example, an electron beam, the acceleration voltage is in the range of 50 to 250 kV, and the dose is preferably in the range of 100 to 800 kGy.

In addition, the obtained polymer electrolyte membrane is crosslinked, and it can be confirmed based on the improvement of the hot water resistance mentioned later, the increase of the gel fraction, and the increase of the crosslinking density.

The gel fraction of the polymer electrolyte membrane can be measured by the method described in the examples below, and is preferably 1% or more, more preferably 20% or more, more preferably 50% or more, and most preferably 80% or more. When the gel fraction is 80% or more, the hot water resistance tends to be particularly good.

The crosslinking density of the polymer electrolyte membrane can be calculated by the method described in the examples below, and is preferably in the range of 0.1 × 10 ^-5 to 100 × 10 ^-5 mol/ml, and 0.5 × 10 ^-5 to 50 × 10 ^- The range of ⁵ mol/ml is better, the range of 1×10 ^-5 to 40×10 ^-5 mol/ml is particularly good, and the range of 2×10 ^-5 to 30×10 ^-5 mol/ml is excellent, 3×10 ^{The range of -5} ~ 15 × 10 ^-5 mol / ml is the best. When the crosslinking density is 3 × 10 ^-5 mol/ml or more, the hot water resistance tends to be good, and when it is 15 × 10 ^-5 mol/ml or less, the tensile elongation at break performance after crosslinking tends to increase. There is a tendency that the start-stop durability is also good.

When a polymer electrolyte membrane is formed on a smooth substrate made of polyethylene terephthalate (PET), glass, or the like, the polymer electrolyte membrane is usually peeled off from the substrate. Further, when a polymer electrolyte membrane is formed on a porous substrate, and the porous substrate is used as a part of the polymer electrolyte membrane, peeling is not required.

Example

The present invention will be specifically described below by way of examples and comparative examples, but the present invention is not limited to the examples.

(Measurement of ion exchange capacity of block copolymer (Z))

The block copolymer (Z) was weighed in a glass vessel (weighing value a (g)), and an excess saturated aqueous solution of sodium chloride ((300 - 500) × a (ml)) was added, and stirred for 12 hours. Using phenolphthalein as an indicator, hydrogen chloride (titration amount b (ml)) produced in water was titrated with 0.01 equivalent of a standard aqueous solution of NaOH (force price f).

The ion exchange capacity was obtained by the following formula.

Ion exchange capacity (meq/g) = (0.01 × b × f) / a

(Measurement of Mn of block copolymer (Z ₀ ))

The Mn was measured by a gel permeation chromatography (GPC) method under the following conditions and calculated in terms of standard polystyrene.

Device: TOSOH (stock) system, trade name: HLC-8220GPC

Lysate: tetrahydrofuran

Pipe column: TOSOH (stock) system, trade name: TSK-GEL (connected 1 TSKgel G3000HxL (76mmI.D.×30cm) in series, 2 TSKgel Super Multipore HZ-M (46mmI.D.×15em) total 3 pieces )

Column temperature: 40 ° C

Detector: RI

Liquid volume: 0.35ml/min

(Measurement conditions of ¹ H-NMR)

The content ratio of each structural unit in the block copolymer (Z ₀ ) obtained in Production Examples 1 to 2 to be described later, and the 1,4-bonding ratio and hydrogenation ratio in the polymer block (B) are as follows. The conditions were measured and the results of ¹ H-NMR were calculated.

Solvent: chloroform

Measuring temperature: room temperature

Cumulative number: 32 times

In addition, the sulfonation ratio of the block copolymer (Z) obtained in the above Production Examples 1 to 2 was calculated from the results of ¹ H-NMR measurement under the following conditions.

Solvent: deuterated tetrahydrofuran / deuterated methanol (mass ratio 80/20) mixed solvent

Measuring temperature: 50 ° C

Cumulative number: 32 times

(Measurement of storage elastic modulus)

9% by mass of toluene/isobutanol/n-octane of the block copolymer (Z-1) and the block copolymer (Z-2) obtained in Production Examples 1 and 2 were separately prepared (mass ratio 3) /3/4) The solution was coated on a release-treated PET film (manufactured by Toyobo Co., Ltd., trade name: K1504) at a thickness of about 300 μm, and dried at 100 ° C for 4 minutes in a hot air dryer to obtain a thickness of 20 μm. Shaped body.

Using a wide-area dynamic viscoelasticity measuring apparatus ("DVE-V4FT Rheospectler" manufactured by Rheology Co., Ltd.), the obtained molded body was heated to 250 in a tensile mode (frequency: 11 Hz), a temperature increase rate of 3 ° C / min, and -80 ° C. °C, the storage elastic modulus (E'), the loss elastic modulus (E"), and the loss tangent (tan δ) were determined. Based on the change in the storage elastic modulus at 80 to 100 ° C derived from the crystallized olefin polymer, The amorphous state of the polymer block (B) was judged. As a result, the polymer block (B) was amorphous with respect to the block copolymer (Z-1) and the block copolymer (Z-2).

[Manufacturing Example 1] (Manufacture of block copolymer (Z ₀ -1))

After drying, 737 ml of dehydrated cyclohexane and 2.06 ml of second butyllithium (0.70 mol/L cyclohexane solution) were added to an autoclave having a nitrogen-substituted capacity of 2 L, and then stirred at 60 ° C while sequentially adding. 28.6 ml of styrene, 14.4 ml of 4-tert-butyl styrene, 28.6 ml of styrene, 14.4 ml of 4-tert-butyl styrene, 114.9 ml of isoprene, 14.4 ml of 4-tert-butyl styrene, Polymerization of 28.6 ml of styrene and 14.4 ml of 4-tert-butylstyrene to obtain polystyrene-b-poly(4-tert-butylstyrene)-b-polystyrene-b-poly (4- Tributylstyrene)-b-polyisoprene -b-poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-tert-butylstyrene). The Mn of the obtained block copolymer was 130,000, the 1,4-bond amount of the polyisoprene block was 93.7%, and the content of the structural unit derived from styrene was 35.6% by mass, derived from 4- The content of the structural unit of tributylstyrene was 24.8% by mass.

The cyclohexane solution of the above block copolymer was prepared, and added to a nitrogen-substituted pressure vessel, and hydrogenation reaction was carried out for 18 hours under a hydrogen pressure of 0.5 to 1 MPa and 70 ° C using a Ni/Al-based Ziegler-type catalyst. A block comprising a polystyrene polymer (polymer block (A ₀ )), a hydrogenated polyisoprene polymer block (polymer block (B)) and poly (4-tert-butyl styrene) are obtained. a block copolymer (Z ₀ ) of a polymer block (polymer block (C)) [polystyrene-b-poly(4-tert-butylstyrene)-b-polystyrene-b- Poly(4-tert-butylstyrene)-b-hydrogenated polyisoprene-b-poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-third Styrene) (hereinafter referred to as "block copolymer (Z ₀ -1)")].

The hydrogenated polyisoprene block of the obtained block copolymer (Z ₀ -1) had a hydrogenation rate of 99% or more.

(Manufacture of block copolymer (Z-1))

After drying, 270 ml of dichloromethane and 149 ml of acetic anhydride were added to a three-necked flask having a nitrogen-substituted capacity of 1 L, and while stirring at 0 ° C, 67 ml of concentrated sulfuric acid was added dropwise, and the mixture was stirred at 0 ° C for 60 minutes to prepare a sulfonating agent. On the other hand, 72 g of the block copolymer (Z ₀ -1) was placed in a glass reaction vessel having a capacity of 5 L of a stirrer, and after replacing nitrogen in the system, 1600 ml of dichloromethane was added thereto, and the mixture was stirred at normal temperature for 4 hours. Dissolved. 486 ml of the previously prepared sulfonating agent was added dropwise to the solution over 5 minutes. After stirring at room temperature for 48 hours, 100 ml of distilled water was added to stop the reaction, and while stirring, 1 L of distilled water was gradually added dropwise to analyze the solid. After the dichloromethane was distilled off under normal pressure, the mixture was filtered, and the recovered solid component was transferred to a beaker, and 1 L of distilled water was added thereto, and after washing with stirring, the solid component was again recovered by filtration. This washing and filtration were repeated until the pH of the washing water did not change, and the obtained solid component was dried at 1.3 kPa and 30 ° C for 24 hours to obtain a block copolymer (Z) used in the polymer electrolyte membrane of the present invention (hereinafter referred to as "Block copolymer (Z-1)"). The ratio (sulfonation ratio) of the obtained block copolymer (Z-1) to the sulfonic acid group derived from the structural unit derived from styrene was 100 mol%, and the ion exchange capacity was 2.6 meq/g.

[Manufacturing Example 2] (Manufacture of block copolymer (Z ₀ -2))

After drying, 960 ml of dehydrated cyclohexane and 3.35 ml of second butyllithium (1.22 mol/L cyclohexane solution) were added to an autoclave having a nitrogen-substituted capacity of 2 L, and then stirred at 60 ° C while sequentially adding. 49.5 ml of styrene, 14.3 ml of 4-tert-butylstyrene, 198 ml of isoprene, 14.3 ml of 4-tert-butylstyrene, and 49.5 ml of styrene were polymerized to obtain polystyrene-b-poly (4). -T-butylstyrene)-b-polyisoprene-b-poly(4-tert-butylstyrene)-b-polystyrene. The Mn of the obtained block copolymer was 75,300, the 1,4-bond amount of the polyisoprene block was 94.0%, and the content of the structural unit derived from styrene was 35.0% by mass, derived from 4- The content of the structural unit of tributylstyrene was 11.0% by mass.

The cyclohexane solution of the above block copolymer was prepared, and added to a nitrogen-substituted pressure vessel, and hydrogenation reaction was carried out for 18 hours under a hydrogen pressure of 0.5 to 1 MPa and 70 ° C using a Ni/Al-based Ziegler-type catalyst. A block comprising a polystyrene polymer (polymer block (A ₀ )), a hydrogenated polyisoprene polymer block (polymer block (B)) and poly (4-tert-butyl styrene) are obtained. Polymer block (polymer block (C)) block copolymer (Z ₀ ) [polystyrene-b-poly(4-tert-butylstyrene)-b-hydrogenated polyisoprene -b-poly(4-tert-butylstyrene)-b-polystyrene (hereinafter referred to as "block copolymer (Z ₀ -2)")]. The hydrogenated polyisoprene block of the obtained block copolymer (Z ₀ -2) had a hydrogenation rate of 99% or more.

(Manufacture of block copolymer (Z-2))

After drying, 161 ml of dichloromethane and 81 ml of acetic anhydride were added to a three-necked flask having a nitrogen-substituted capacity of 1 L, and while stirring at 0 ° C, 36 ml of concentrated sulfuric acid was added dropwise, and the mixture was stirred at 0 ° C for 60 minutes to prepare a sulfonating agent. On the other hand, 50 g of the block copolymer (Z ₀ -2) was placed in a glass reaction vessel having a capacity of 3 L of a stirrer, and after replacing nitrogen in the system, 800 ml of dichloromethane was added thereto, and the mixture was stirred at normal temperature for 4 hours. Dissolved. 279 ml of the previously prepared sulfonating agent was added dropwise to the solution over 5 minutes. After stirring at room temperature for 48 hours, 100 ml of distilled water was added to stop the reaction, and while stirring, 500 ml of distilled water was gradually added dropwise to analyze the solid. After the dichloromethane was distilled off under normal pressure, the mixture was filtered, and the recovered solid component was transferred to a beaker, and 1 L of distilled water was added thereto, and after washing with stirring, the solid component was again recovered by filtration. This washing and filtration were repeated until the pH of the washing water did not change, and the obtained solid component was dried at 1.3 kPa and 30 ° C for 24 hours to obtain a block copolymer (Z) (hereinafter referred to as "block copolymer (Z-2)). "). The ratio (sulfonation ratio) of the obtained block copolymer (Z-2) to the sulfonic acid group derived from the structural unit derived from styrene was 99 mol%, and the ion exchange capacity was 2.6 meq/g.

[Example 1] (Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/octane (mass ratio 3/3/4) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen) Petrochemical (stock), product name: MARUKA LYNCUR M, grade: S-1, Mn: 1100~1500) as compound (X), the quality of block copolymer (Z-1) / poly-4-vinylphenol The ratio is 100/9.4, and 4,4',4"-trihydroxytriphenylmethane (manufactured by Tokyo Chemical Industry Co., Ltd.) is added as the compound (Y) to make the block copolymer (Z-1) / 4, 4 The mass ratio of ',4"-trishydroxytriphenylmethane was 100/1, and a fluid composition was prepared. Next, the fluid composition was applied to a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF75) at a thickness of about 425 μm, and dried at 100 ° C for 6 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The obtained molded body was subjected to heat treatment under a nitrogen stream at 140 ° C for 1 hour to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 2] (Production of polymer electrolyte membrane)

In addition to 1,1,1-paraxyl (4-hydroxyphenyl)ethane (manufactured by Tokyo Chemical Industry Co., Ltd.) to replace 4,4',4"-trihydroxytriphenylmethane as compound (Y), The mass ratio of the segment copolymer (Z-1)/1,1,1-cis (4-hydroxyphenyl)ethane was 100/1, and the same procedure as in Example 1 was carried out to obtain a molded body having a thickness of 18 μm. The obtained molded body was subjected to heat treatment under a nitrogen stream at 140 ° C for 1 hour to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Example 3] (Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/octane (mass ratio 3/3/4) solution of the block copolymer (Z-1) obtained in Production Example 1, 2,6-bis(2- was added thereto). Hydroxy-5-methylbenzyl)-4-cresol (manufactured by Asahi Organic Materials Co., Ltd.) as the compound (X), the block copolymer (Z-1)/2,6-bis(2-hydroxyl) a mass ratio of -5-methylbenzyl)-4-cresol of 100/4.5, and adding 4,4',4"-trihydroxytriphenylmethane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a compound (Y) The mass ratio of the block copolymer (Z-1) / 4, 4', 4" - trihydroxytriphenylmethane was 100/1, and a fluid composition was prepared. Next, the fluid composition was applied to a PET film (Mitsubishi Resin, trade name: MRF75) which had been subjected to release treatment at a thickness of about 450 μm, and dried at 100 ° C for 30 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The obtained molded body was subjected to heat treatment under a nitrogen gas flow at 120 ° C for 5 hours to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Example 4] (Production of polymer electrolyte membrane)

After preparing a 14.5 mass% toluene/isobutanol (mass ratio 7/3) solution of the block copolymer (Z-2) obtained in Production Example 2, 2,6-bis(2-hydroxy-5-A was added thereto. As a compound (X), a block copolymer (Z-2)/2,6-bis(2-hydroxy-5-methyl group) is used as the compound (X). The mass ratio of benzyl)-4-methylphenol is 100/4.5, and 4,4',4"-trihydroxytriphenylmethane (manufactured by Tokyo Chemical Industry Co., Ltd.) is added as the compound (Y) to copolymerize the block. The mass ratio of the (Z-2)/4,4',4"-trihydroxytriphenylmethane was 100/1, and a fluid composition was prepared. Next, the flowable composition was applied to a PET film (Mitsubishi Resin, trade name: MRF75) which was subjected to release treatment at a thickness of about 250 μm, and was dried by a hot air dryer. After drying at 100 ° C for 30 minutes, a molded body having a thickness of 19 μm was obtained. The obtained molded body was subjected to heat treatment under a nitrogen gas flow at 120 ° C for 5 hours to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Example 5] (Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/octane (mass ratio 3/3/4) solution of the block copolymer (Z-2) obtained in Production Example 2, 2,6-bis(2-) was added. Hydroxy-5-methylbenzyl)-4-cresol (manufactured by Asahi Organic Materials Co., Ltd.) as the compound (X), the block copolymer (Z-2)/2,6-bis(2-hydroxyl) a mass ratio of -5-methylbenzyl)-4-cresol of 100/4.5, and adding 4,4',4"-trihydroxytriphenylmethane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a compound (Y) The mass ratio of the block copolymer (Z-2) / 4, 4', 4" - trihydroxytriphenylmethane was 100/1, and a fluid composition was prepared. Then, the flowable composition was applied to a PET film (Mitsubishi Resin, trade name: MRF75) which was subjected to release treatment, and then the nonwoven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus) was applied. (registered trademark), an average fiber diameter of 7 μm, a basis weight of 3 g/cm ² , a porosity of 76.2%, and a thickness of 9 μm) without causing wrinkles to overlap with the coated surface from above, and after impregnating the fluid composition with the nonwoven fabric, It was dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further coated thereon at a thickness of about 175 μm, and dried at 100 ° C for 30 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-2) and the compound (X). The molded body composed of the molded body and the non-woven fabric had a thickness of 20 μm. The obtained joined body was heat-treated at 120 ° C for 5 hours under a nitrogen stream, and the molded body was crosslinked to prepare a polymer electrolyte membrane of the present invention.

[Reference Example 1] (Production of polymer electrolyte membrane)

After preparing 11% by mass of a toluene/isobutanol/octane (mass ratio 3/3/4) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical (stock), product name: MARUKA LYNCUR M, grade: S-1) as compound (X), the mass ratio of block copolymer (Z-1) / poly-4-vinylphenol is 100/9.4, A fluid composition was prepared. Next, the fluid composition was applied to a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF75) at a thickness of about 350 μm, and dried at 100 ° C for 6 minutes in a hot air dryer. A molded body having a thickness of 19 μm. The obtained molded body was subjected to heat treatment under a nitrogen stream at 140 ° C for 30 minutes to carry out crosslinking, whereby the polymer electrolyte membrane of Reference Example 1 was produced.

[Reference Example 2] (Production of polymer electrolyte membrane)

After preparing a 14% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, 2,6-bis(2-hydroxy-5-A was added thereto. As a compound (X), a block copolymer (Z-1)/2,6-bis(2-hydroxy-5-methyl group) is used as the compound (X). The mass ratio of benzyl)-4-methylphenol was 100/4.5, and a fluid composition was prepared. Next, the flowable composition was applied to a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF75) at a thickness of about 250 μm, and dried at 100 ° C for 30 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The obtained molded body was subjected to heat treatment under a nitrogen stream at 120 ° C for 3 hours to carry out crosslinking, whereby the polymer electrolyte membrane of Reference Example 2 was produced.

[Reference Example 3] (Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/octane (mass ratio 3/3/4) solution of the block copolymer (Z-2) obtained in Production Example 2, 2,6-bis(2-) was added. Hydroxy-5-methylbenzyl)-4-cresol (manufactured by Asahi Organic Materials Co., Ltd.) as the compound (X), the block copolymer (Z-2)/2,6-bis(2-hydroxyl) The mass ratio of -5-methylbenzyl)-4-cresol was 100/4.5, and a fluid composition was prepared. Next, the fluid composition was applied to a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF75) at a thickness of about 450 μm , and dried at 100 ° C for 30 minutes in a hot air dryer. A molded body having a thickness of 19 μm was obtained. The obtained molded body was subjected to heat treatment under a nitrogen stream at 120 ° C for 3 hours to carry out crosslinking, whereby the polymer electrolyte membrane of Reference Example 3 was produced.

[Comparative Example 1] (Production of polymer electrolyte membrane)

After preparing a 12% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, 4,4',4"-trihydroxytriphenylmethane was added. (Tokyo Chemical Industry Co., Ltd.) As the compound (Y), the mass ratio of the block copolymer (Z-1) / 4, 4', 4" - trihydroxytriphenylmethane was 100/1, and the flow was prepared. Sexual composition. Next, the fluid composition was applied to a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF75) at a thickness of about 350 μm, and dried at 100 ° C for 6 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The polymer electrolyte membrane of Comparative Example 1 was produced by heat-treating the obtained molded body under a nitrogen stream at 140 ° C for 1 hour.

[Comparative Example 2] (Production of polymer electrolyte membrane)

In addition to adding triphenylmethane (Tokyo Chemical Industry Co., Ltd.) instead of 4,4',4"-trihydroxytriphenylmethane, the mass ratio of block copolymer (Z-1)/triphenylmethane was 100/1. In the same manner as in Example 1, a molded article having a thickness of 18 μm was obtained, and the obtained molded body was subjected to heat treatment under a nitrogen stream at 140 ° C for 1 hour to carry out crosslinking, whereby a polymer electrolyte membrane of Comparative Example 2 was produced.

(Performance test and results of polymer electrolyte membrane)

According to the measurement described below. The evaluation method evaluates the performance of the polymer electrolyte membrane. The results are shown in Table 1.

(Hot water resistance test: residual rate of insoluble matter)

A test piece of 3 cm × 5 cm was cut out from the polymer electrolyte membrane obtained in each of the examples, the comparative examples, and the reference examples, and dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₁ ) was measured, and then added to 110 mL. After 60 mL of distilled water was added to the screw, it was housed in a metal container made of SUS, sealed, and left to stand in a thermostat at 110 ° C for 96 hours. Thereafter, the test piece was taken out, dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₂ ) was measured.

The insoluble matter residual ratio (a) was determined by the following formula.

Insoluble matter residual rate (a) (%) = m ₂ / m ₁ × 100

In addition, another test piece of 3 cm × 5 cm was cut out from the same polymer electrolyte membrane, and the same test was carried out using the same test to determine the residual rate (b) of the insoluble matter.

The insoluble matter residual ratio (a) and the insoluble matter residual ratio (b) obtained as described above were arithmetically averaged to obtain an insoluble matter residual ratio. The higher the residual rate of the insoluble matter, the more excellent the hot water resistance.

(Measurement of gel fraction and crosslink density)

A test piece of 3 cm × 5 cm was cut out from the polymer electrolyte membrane obtained in each of the examples, the comparative examples, and the reference examples, and dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₃ ) was measured, and then immersed in 30 ml. Toluene/isobutanol (mass ratio: 70/30) was used for 3 hours, and the film was taken out, and the mass of the film (measured as mass m ₄ ) was measured in a state containing a solvent. Thereafter, the mixture was dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₅ ) was measured.

The crosslink density (ν) was calculated using the formula of Flory Rehner.

ν={ln(1-m ₅ /m ₄ )+m ₅ /m ₄ +0.4×(m ₅ /m ₄ ) ² }/[102×{(m ₅ /m ₄ ) ^1/3 -(m ₅ /m ₄ )/2}]

Further, the gel fraction was calculated according to the following formula.

Gel fraction = m ₅ /m ₃ × 100 (%)

[Film resistance evaluation test of polymer electrolyte membrane]

The increase in the membrane resistance during the operation of the polymer electrolyte membrane used in the polymer electrolyte fuel cell was evaluated by the following method.

The polymer electrolyte membrane obtained in each of the examples, the comparative examples, and the reference examples was cut into a test piece of 9 cm × 9 cm, and the inside was cut into a PTFE film having a thickness of 1 cm μm of 5 cm × 5 cm, and contained in two pieces. The catalyst layer containing Pt catalyst-carrying carbon and NAFION D1021 (manufactured by DuPont) was sandwiched between the electrodes of carbon paper, and then heat-treated by hot pressing (130 ° C, 20 kgf/cm ² , 8 minutes) A membrane-electrode assembly (MEA) was produced. Next, after the produced MEA is combined with a gasket, it is sandwiched by two conductive separators which function as a gas supply flow path, and the outer side is provided with two collector plates and two clamping plates. Clamp and make an evaluation battery. Load current control connected to gas supply hose, drain hose, heater power supply, thermocouple, impedance analyzer (NF circuit design), and power generation analyzer (NF circuit design) The terminal and the voltage detecting terminal are connected to the fabricated evaluation battery, and assembled into an evaluation fuel cell. Nitrogen was supplied at 200 cc/min for each of the electrodes of the evaluation fuel cell, and the membrane resistance r1 was measured by an alternating current impedance method under the conditions of a battery temperature of 100 ° C, a relative humidity of 47%, an AC voltage of 0.05 V, and a frequency of 10 to 100,000 Hz. . Next, hydrogen was supplied at 83 cc/min on one electrode (anode), oxygen was supplied at 273 cc/min on the other electrode (cathode), and the battery was operated at a battery temperature of 100 ° C and a relative humidity of 47% for 60 hours, and then again. The electrodes of the two electrodes were supplied with nitrogen at 200 cc/min, and the membrane resistance r2 was measured by an AC impedance method under the conditions of a battery temperature of 100 ° C, a relative humidity of 47%, an AC voltage of 0.05 V, and a frequency of 10 to 100,000 Hz, and the film resistance was calculated. (r2-r1).

In order to confirm that the polymer electrolyte membrane of the present invention is soft and difficult to be broken, the tensile strength at break and the tensile elongation at break of the obtained polymer electrolyte membrane were measured by the following methods.

A dumbbell-shaped test piece was cut out from the polymer electrolyte membrane, and the sample was conditioned at 25 ° C and a relative humidity of 40%, and then attached to a tensile tester (Model 5566 manufactured by Instron Japan Co., Ltd.) at 25 ° C and a relative humidity of 40%. The tensile breaking strength and the tensile elongation at break were measured under the conditions of a tensile speed of 500 mm/min.

As shown in Table 1, the polymer electrolyte membrane of the present invention is excellent in hot water resistance and can suppress an increase in membrane resistance during operation in a polymer electrolyte fuel cell.

Industrial availability

The polymer electrolyte membrane of the present invention is composed of a non-fluorine-based material, and has a small environmental load during production and disposal, is soft and hard to be broken, and is excellent in hot water resistance, and is in operation during use of a polymer electrolyte fuel cell. Since the increase in resistance is small, it is suitable for use as a polymer electrolyte membrane for a polymer electrolyte fuel cell.

Claims (7)

A polymer electrolyte membrane obtained by subjecting a composition comprising a block copolymer (Z), a compound (X) and a compound (Y) to crosslinking after forming, the block copolymer (Z) comprising: a polymer block (A) comprising a structural unit derived from an aromatic vinyl compound and having an ion conductive group, and an amorphous polymer containing a structural unit derived from an unsaturated aliphatic hydrocarbon and having no ion conductive group In the block (B), the compound (X) has an aromatic ring in which two or more hydrogen atoms in the molecule are substituted with a hydroxyl group, and the adjacent aromatic rings are each contained at least one methylene group. A structure in which a carbon number of 1 to 3 is bonded to a carbon chain, and the compound (Y) is represented by the following general formula (1): In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, a hydroxyl group or a carbon number of 1 to 4. An alkyl group or an alkoxy group having 1 to 4 carbon atoms. The polymer electrolyte membrane according to claim 1, wherein the unsaturated aliphatic hydrocarbon is at least one selected from the group consisting of an olefin having 4 to 8 carbon atoms and a conjugated diene having 4 to 8 carbon atoms. The polymer electrolyte membrane according to claim 1 or 2, wherein the ion conductive group is selected from the group consisting of a sulfonic acid group represented by -SO ₃ M or PO ₃ HM, a phosphonic acid group, and one or more of the salts; In the formula, M represents a hydrogen atom, an ammonium ion or an alkali metal ion. The polymer electrolyte membrane according to any one of claims 1 to 3, wherein the compound (X) is used in an amount of 0.01 to 25 parts by mass based on 100 parts by mass of the block copolymer (Z). The polymer electrolyte membrane according to any one of claims 1 to 4, wherein the compound (Y) is used in an amount of 0.01 to 20 parts by mass based on 100 parts by mass of the block copolymer (Z). The polymer electrolyte membrane according to any one of claims 1 to 5, wherein the block copolymer (Z) further comprises: a polymer block comprising a structural unit derived from an aromatic vinyl compound and having no ion conductive group (C). A polymer electrolyte fuel cell having the polymer electrolyte membrane according to any one of claims 1 to 6.