TW201537818A - Polymer electrolyte membrane - Google Patents

Abstract

A polymer electrolyte membrane containing a reinforcing material, wherein the polymer electrolyte membrane contains a polymer electrolyte obtained by crosslinking a body molded from a composition containing a compound (X) and a block copolymer (Z). The compound (X) has, in the molecule, two or more aromatic rings in which one or more hydrogens are substituted with a hydroxyl group. The block copolymer (Z) contains: a polymer block (A), which comprises structural units derived from an aromatic vinyl compound and which has an ion-conductive group; and an amorphous polymer block (B), which comprises structural units derived from an unsaturated aliphatic hydrocarbon, and which does not have an ion-conductive group. The reinforcing material is a porous material.

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 ( Refer to 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 main component enhances the hot water resistance of the polymer electrolyte membrane (see Patent Document 3).

[Previous 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.

In addition, the dimensional stability in the hot water of the polymer electrolyte membrane, or the start and stop of the polymer electrolyte fuel cell, the durability during repeated wetting and drying (hereinafter referred to as "starting and stopping durability") There is room for improvement.

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, and which has excellent hot water resistance.

According to the present invention, the above object is achieved by providing a polymer electrolyte membrane comprising a polymer electrolyte membrane comprising a reinforcing material, the polymer electrolyte membrane containing comprising: comprising an aromatic vinyl compound derived The polymer block (A) having an ion conductive group (hereinafter referred to as "polymer block (A)"), and a structural unit derived from an unsaturated aliphatic hydrocarbon, and having no ion conductivity a block copolymer (Z) of the amorphous polymer block (B) (hereinafter simply referred to as "polymer block (B)") (hereinafter referred to as "block copolymer (Z)") and a polymer electrolyte obtained by crosslinking a molded body of a composition of a compound (X) (hereinafter referred to simply as "compound (X)") having an aromatic ring in which two or more hydrogen atoms are substituted by a hydroxyl group, and The reinforcing material is a porous material.

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, and which is excellent in hot water resistance. In addition, the polymer electrolyte membrane of the present invention has a small dimensional change in hot water, and is excellent in start-stop durability when applied to a polymer electrolyte fuel cell, and therefore can be suitably used for a solid polymer fuel. battery.

[Formation of the Invention]

[Polymer electrolyte membrane]

The polymer electrolyte membrane of the present invention contains the polymer electrolyte and the reinforcing material described below.

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

Polymer electrolyte

The polymer electrolyte is obtained by crosslinking a molded body containing a composition of the block copolymer (Z) and the compound (X) of the polymer block (A) and the polymer block (B). Polymer block (A) is derived from aromatic B A structural unit of an olefinic compound and having a polymer block of an ion conductive group. Further, 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. The compound (X) is a compound having an aromatic ring in which two or more hydrogen atoms in the molecule are substituted with a hydroxyl group.

In the polymer electrolyte, 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 Å) or less.

(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; 300,000 or less, particularly 180,000 or less, contains a block copolymer. The above composition of (Z) and the compound (X) 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 1.0 to 3.8 meq/g, and particularly preferably in the range of 1.5 to 3.4 meq/g, and 1.8 to 3.0 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/or polymer block (B), respectively, or may have a plurality of. 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, one type of these block copolymers may be used alone or two or more types may be used in combination.

In the block copolymer (Z ₀ ), from the viewpoint of ion conductivity and mechanical strength, (total amount of polymer blocks (A ₀ )): (total amount of polymer blocks (B)), by mass The range of 95:5~5:95 is better, the range of 75:25~15:85 is better, the range of 65:35~20:80 is better, and the range of 45:55~25:75 is the best. . When the mass ratio is in the range of 95:5 to 5:95, particularly in the range of 45:55 to 25:75, the polymer electrolyte membrane of the present invention is used in a solid polymer fuel cell. The tendency to be excellent.

<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 an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a second butyl group, and a third butyl group; a halogenated alkyl group having 1 to 4 carbon atoms such as chloromethyl, 2-chloroethyl or 3-chloroethyl; 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 good, and when it is 100,000 or less, particularly 30,000 or less, the hot water resistance is good, and the block copolymer (Z) and the block copolymer (Z) are contained. The above composition of the compound (X) 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 At least one selected from the group consisting of an alkene having 4 to 8 carbon atoms and a conjugated diene having 4 to 8 carbon atoms More preferably selected from isobutylene, butadiene and isoprene at least 1, particularly preferably selected from butadiene and isoprene is at least one. The unsaturated aliphatic hydrocarbons are polymerized as a single monomer or polymerized in two or more kinds to form a monomer. 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 capable of forming 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, vinyl propionate, and butyric acid. Vinyl esters such as vinyl ester 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. By reducing the carbon-carbon double bond in the polymer block (B) as described above, the heat deterioration resistance of the polymer electrolyte membrane can be improved.

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 usually in the range of preferably 5,000 to 250,000, more preferably in the range of 15,000 to 200,000, particularly preferably in the range of 50,000 to 150,000, and most preferably in the range of 80,000 to 140,000. In the polymer electrolyte membrane of the present invention, when the Mn is 5,000 or more, particularly 80,000 or more, mechanical strength and start-stop durability are good, and when it is 250,000 or less, particularly 140,000 or less, the block copolymer (Z) and the compound are contained. The above composition of (X) is excellent in moldability 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, 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 (1).

(wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R ² represents an alkyl group having 3 to 8 carbon atoms; and R ³ and R ⁴ 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 (1) include 4-propylstyrene, 4-isopropylstyrene, 4-butylstyrene, and 4-isobutylene. More preferably, styrene, 4-tert-butyl styrene, 4-octyl styrene, α-methyl-4-tert-butyl styrene, α-methyl-4-isopropyl styrene, etc. Is 4-tert-butyl styrene, 4-isopropyl styrene, α-methyl-4-tert-butyl styrene, α-methyl-isopropyl styrene, further preferably 4- Tributylstyrene. 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, and isoprene. 1,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-glycan a conjugated diene having 4 to 8 carbon atoms such as a diene; carbon number of ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc. ~8 olefin; (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc.; vinyl acetate, vinyl propionate, vinyl butyrate a vinyl ester such as trimethyl vinyl acetate; a vinyl ether such as methyl vinyl ether or 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 tends to have excellent start-stop durability when used in a polymer electrolyte fuel cell, and when it is 50,000 or less, it contains a block copolymer (Z) and a compound ( The composition of the above X) tends to be excellent in formability.

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 hexablock 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 eight embedded Segment copolymers, etc. 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, one type of these block copolymers may be used alone or two or more types may be used in combination.

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 can be produced by polymerizing each of the above monomers to produce a block copolymer comprising the polymer block (A ₀ ) and the polymer block (B) (Z _{0 )} After that, it is produced by a method of introducing an ion conductive group into the polymer block (A ₀ ).

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; An aromatic organic sulfonic acid represented by 4,6-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 one or more hydrogenogens having two or more in the molecule. A compound of an aromatic ring substituted with a hydroxy group and is considered to function as a crosslinking agent. It is presumed that the compound (X) has two or more such aromatic rings in the molecule, and the compound (X) is selectively present in the phase containing the hydrophilic polymer block (A), and therefore it is considered to be hydrophilic. The polymer block (A) is selectively crosslinked without impairing the flexibility of the polymer electrolyte membrane, and the hot water resistance is improved.

As the aromatic ring, a hydrocarbon-based aromatic ring such as a benzene ring, a naphthalene ring or an anthracene ring is preferred, and a benzene ring is more preferred.

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 carbon in the 2, 4, and 6 positions is It is preferable that at least one of the carbons having a substituent has a substituent, and from the viewpoint of improving the tensile elongation at break and the tensile strength at break of the polymer electrolyte membrane, it is more preferable that the carbon at the 4-position has a methyl group.

Specific examples of the compound (X) include bisphenol S, 4,4'-dihydroxybiphenyl-2,2'-disulfonic acid, and 4,4'-dihydroxybiphenyl-3,3'-. Disulfonic acid, 2,2'-dihydroxybiphenyl-4,4'-disulfonic acid, 5,5'-methylenebis(2-hydroxybenzoic acid), 4,4'-isopropylidene double (2,6-dichlorophenol), 4,4'-isopropylidene bis(2,6-dibromophenol), 4,4'-(9-fluorenylene)diphenol, bis(2-hydroxyl Phenyl)methane, 2,2'-biphenol, 4,4'-biphenol, bis(4-hydroxyphenyl)methane, bisphenol A, 4,4'-hexafluoroisopropylidenediol, 2 , 2-bis(4-hydroxy-3-tolyl)propane, 1,1-bis(4-hydroxy-3-tolyl)ethane, 2,2'-methylenebis(6-t-butyl 4-methylphenol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-ethylenebis(4,6-di-tert-butylphenol) , 3,3'-extended ethyldioxydiphenol, 1,4-bis(3-hydroxyphenoxy)benzene, 1,3-bis(4-hydroxyphenoxy)benzene, bis(4-hydroxyl -3,5-xylyl)methane, bis(4-hydroxyphenyl)toluene, hexestrol, ninhydrin (dithranol), 1,1'-bi-2-naphthol, dihydroguaiaretic acid, bis(3,4-dihydroxy-6-tolyl)toluene, 9-(4-hydroxybenzyl)- a compound having two aromatic rings in the molecule such as 10-(4-hydroxyphenyl)anthracene; 1,1,3-glycol(2-methyl-4-hydroxy-5-t-butylphenyl) Alkane, 2,6-bis(4-hydroxy-3,5-dimethylbenzyl)-4-cresol, 1,1,1-cis (4-hydroxyphenyl)ethane, ginseng (4-hydroxyl) Phenyl)methane, bis(4-hydroxy-3-methyl)-4-hydroxy-3-methoxytoluene, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol a compound having 3 aromatic rings in the molecule such as 2,6-bis(2,4-dihydroxybenzyl)-4-cresol; 1,1,2,2-anthracene (4-hydroxyphenyl) Ethane, α,α,α',α'-肆(4-hydroxyphenyl)p-xylene, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, C- Methyl cup [4] resorcinol arene, calix[4]arene, 6,6'-bis(2-hydroxy-5-methylbenzyl)-4,4'-dimethyl-2,2' a compound having four aromatic rings in the molecule such as methylene diphenol; 2,2-bis[4-hydroxy-3,5-bis(2-hydroxy-5-methylbenzyl)phenyl]propane a compound having six aromatic rings in a molecule such as a calix[6]arene; poly-2-hydroxy-5-vinylbenzenesulfonic acid Poly-2-vinyl phenol, poly-3-vinyl phenol, poly-4-vinyl phenol, etc. in a phenol skeleton of a polymer repeat unit.

Wherein, selected from 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(2,6-dibromophenol), 4,4'- (9-fluorenylene) diphenol, bis(2-hydroxyphenyl)methane, 2,2'-biphenol, 4,4'-biphenol, bis(4-hydroxyphenyl)methane, bisphenol A, 4,4'-hexafluoroisopropylidenediol, 2,2-bis(4-hydroxy-3-tolyl)propane, 1,1-bis(4-hydroxy-3-tolyl)ethane, 2 , 2'-methylenebis(6-tert-butyl-4-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'- Ethylene bis(4,6-di-tert-butylphenol), 3,3'-extended ethyldioxydiphenol, 1,4-bis(3-hydroxyphenoxy)benzene, 1,3-double (4-hydroxyphenoxy)benzene, bis(4-hydroxy-3,5-dimethylphenyl)methane, bis(4-hydroxyphenyl)methyl Benzene, hexestrol, ninhydrin, 1,1'-bi-2-naphthol, dihydroguaiaretic acid, bis(3,4-dihydroxy-6-tolyl)toluene, 9-(4 -hydroxybenzyl)-10-(4-hydroxyphenyl)indole, 1,1,3-glycol(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 2,6- Bis(4-hydroxy-3,5-dimethylbenzyl)-4-cresol, 1,1,1-cis (4-hydroxyphenyl)ethane, ginseng (4-hydroxyphenyl)methane, double (4-hydroxy-3-tolyl)-4-hydroxy-3-methoxytoluene, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, 2,6-double (2,4-dihydroxybenzyl)-4-cresol, 1,1,2,2-indole (4-hydroxyphenyl)ethane, α,α,α',α'-肆(4-hydroxyl Phenyl)p-xylene, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, C-methylcup[4]resorcinol arene, calix[4]arene, 6,6'-bis(2-hydroxy-5-methylbenzyl)-4,4'-dimethyl-2,2'-methylene diphenol, 2,2-bis[4-hydroxy-3 , 5-bis((2-hydroxy-5-methylbenzyl))phenyl]propane, calix[6]arene, poly-2-vinylphenol, poly-3-vinylphenol, poly-4-vinylphenol Preferably, the compound is selected from the group consisting of 2,2'-biphenol, 4,4'-biphenol, bisphenol A, 3,3'-extended ethyldioxydiphenol, 1,4-bis(3-hydroxyl) Phenoxy)benzene, 1,3-bis(4-hydroxyl) Phenoxy)benzene, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, 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- The compound of vinyl phenol and poly-4-vinyl phenol is more preferably selected from the group consisting of 2,2'-biphenol, 4,4'-biphenol, 3,3'-ethylidene dioxy phenol, 1,4 - bis(3-hydroxyphenoxy)benzene, 1,3-bis((4-hydroxyphenoxy))benzene, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-methyl Phenol, 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 compound is particularly preferred, from the viewpoint of hot water resistance, selected from 2, 2' -biphenol, 4,4'-biphenol, 1,4-bis(3-hydroxyphenoxy)benzene, 1,3-bis(4- Hydroxyphenoxy)benzene, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol, 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 - The compounds of vinyl phenol and poly-4-vinyl phenol are optimal. From the viewpoint of suppressing the voltage drop during operation of the polymer electrolyte membrane for the polymer electrolyte fuel cell and the start-stop durability of the polymer electrolyte membrane, it is selected from the group consisting of poly-4-vinylphenol and 2,6-double ( Compounds of 2-hydroxy-5-methylbenzyl)-4-cresol and 2,6-bis(2,4-dihydroxybenzyl)-4-cresol are particularly preferred, poly-4-vinylphenol, 2 , 6-bis(2-hydroxy-5-methylbenzyl)-4-cresol is most 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 polymer electrolyte is obtained by crosslinking a molded body containing a composition of the block copolymer (Z) and the compound (X).

In the composition containing the block copolymer (Z) and the compound (X) which form the polymer electrolyte, the amount of the compound (X) is increased from the viewpoint of improving the hot water resistance and ion conductivity of the polymer electrolyte membrane. The mass fraction of the block copolymer (Z) is preferably in the range of 0.1 to 25 parts by mass, more preferably in the range of 1 to 20 parts by mass, particularly preferably in the range of 1.5 to 15 parts by mass, and in the range of 2 to 12 parts by mass. optimal. Moreover, from the viewpoint of improving hot water resistance and ion conductivity, and facilitating the gel fraction to be in a preferable range, The number of moles of the aromatic ring in which one or more hydrogen atoms of the substance (X) are substituted with a hydroxyl group is 0.1 to 70 moles per 100 parts by mole of the ion conductive group of the block copolymer (Z) The range is better, the range of 0.5 to 60 moles is better, the range of 0.8 to 50 moles is particularly good, and the range of 3 to 38 moles is the best.

In the formation of the molded body of the composition, a fluid composition containing the block copolymer (Z), the compound (X) and the solvent is preferably used from the viewpoint of the film-form molded body. After the fluid composition is applied onto a substrate or a reinforcing material to be described later, a film-shaped molded body can be formed by removing the solvent.

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 fats such as hexane, heptane, and octane. a hydrocarbon; 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, mixed solvent of xylene and isobutanol, mixed solvent of toluene and isopropanol, mixed solvent of toluene and isobutanol and octane, mixed solvent of toluene and isopropanol and octane .

The fluid composition is prepared by dissolving or dispersing the block copolymer (Z) and the compound (X) in the above solvent. A stabilizer such as a softener, a phenolic stabilizer, a sulfur-based stabilizer, or a phosphorus stabilizer may be used in combination with the stabilizer, the optical stabilizer, the antistatic agent, and the like, as long as the effect of the present invention is not impaired. Various additives such as mold release agents, 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 50% by mass or more, preferably 70% by mass, from the viewpoint of the ion conductivity of the obtained polymer electrolyte membrane. The above is better, and 85 mass% or more 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.

As the stabilizer which can be used for the above fluid composition, 2,6-di-t-butyl-p-cresol, 6-t-butyl-o-cresol, 2-t-butyl-p-pair can be mentioned. Phenol, 6-t-butyl-2,4-xylenol, 4-tert-butyl-2,6-dipropofol, 2,6-di-t-butyl-4-ethylphenol, 4- Second butyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 4-butyl resorcinol, 3,5-di-t-butyl-4-hydroxyl Benzoic acid, 4-hydroxy-3,5-dimethylbenzoic acid, gallic acid, vanillic acid, 4,4',4"-trihydroxytriphenylmethane, 4,4',4" -trihydroxyphenylethane, pentaerythritol-indole [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2 ,4,6-gin (3,5-di-t-butyl-4-hydroxybenzyl)benzene, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid Ester, triethylene glycol-bis[3-(3-tert-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy- 3,5-di-t-butylanilino)-1,3,5-three , 2,2-thio-di-extended ethyl bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 3,5-di-t-butyl-4- Hydroxy-benzylphosphonate-diethyl ester, cis-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanate, 3,9-bis[2-[3- (3-tert-butyl-4-hydroxy-5-tolyl)propenyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5] Phenolic stabilizers such as monoalkane; neopentyl lanthanum strontium (3-lauryl thiopropionate), distearyl 3,3'-thiodipropionate, dilauryl 3,3'-sulfur a sulfur-based stabilizer such as propionate or dimyristyl 3,3'-thiodipropionate; ginsylphenylphosphite and bis(2,4-di-t-butylphenyl) A phosphate-based stabilizer such as a phosphate ester or a distearyl pentaerythritol diphosphite, and a phenolic stabilizer is preferred. 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 polymer electrolyte can be formed by crosslinking a molded body comprising a composition containing the block copolymer (Z) and the compound (X). It is preferred to form the fluid composition into a film shape and then crosslink it. Specifically, a method of producing a polymer electrolyte membrane will be described below.

"Strengthen"

The polymer electrolyte membrane of the present invention contains the above polymer electrolyte and a reinforcing material as a porous material. By having the reinforcing material, the polymer electrolyte membrane of the present invention can improve the tensile strength at break, and at the same time, the dimensional change particularly in hot water is small, and the start-stop durability is applied when applied to a solid polymer fuel cell. Sex is also getting better.

The porous material used for the reinforcing material may be in the form of a film, and the pores are preferably connected between the main faces of the film.

It is preferable that the main surface of the film-shaped reinforcing material is parallel to the main surface of the polymer electrolyte membrane itself.

The thickness of the film-like reinforcing material is preferably in the range of 3 to 70 μm, more preferably 5 to 40 μm, particularly preferably 6 to 20 μm, and most preferably 7 to 17 μm. When the thickness is 3 μm or more, the polymer electrolyte membrane tends to have excellent mechanical strength. Moreover, the film resistance of the polymer electrolyte membrane tends to be low by a thickness of 70 μm or less.

The porosity of the porous material is preferably 40 to 95%, more preferably 50 to 93%, further preferably 60 to 90%, particularly preferably 70 to 89%, and most preferably 80 to 88%. When the porosity is 40% or more, the polymer electrolyte membrane is excellent in ion conductivity, and when it is 70% or more (particularly 80% or more), the polymer electrolyte membrane including the polymer electrolyte membrane is used. Excellent initial power generation characteristics. Moreover, when it is 95% or less, the strength of the polymer electrolyte membrane tends to be excellent.

In the void of the porous material forming the reinforcing material, a composition containing a polymer electrolyte (a composition containing the block copolymer (Z) and the compound (X)) is preferably impregnated, and the composition is fluidized as described above. The form of the composition is impregnated in the voids of the porous material to remove the solvent, and Cross-linking is more desirable.

From the viewpoint of improving the power generation performance and the fuel barrier property, the filling rate of the polymer electrolyte in the void of the porous material forming the reinforcing material is preferably 70% by volume or more, more preferably 85% by volume or more, and 95% by volume or more. good.

The average pore diameter of the porous material forming the reinforcing material is usually 0.001 to 1000 μm, preferably 0.005 to 800 μm, more preferably 0.01 to 500 μm. When it is 0.001 μm or more, the filling rate of the composition of the polymer electrolyte in the voids containing the porous material is likely to be increased, and when it is 1000 μm or less, the strength of the polymer electrolyte membrane tends to be high.

The material of the porous material forming the reinforcing material is not limited, and examples thereof include polyolefins such as polyethylene, polypropylene, and polyalkene; polyaromatic ethylene such as polystyrene; polyethylene terephthalate and poly Polyesters such as aryl esters; poly(meth)acrylates such as polymethyl methacrylate; polyamines; polyimines; aromatic polyether ketones such as polyether ketones and polyether ether ketones; Alcohol; cellulose; polysulfide; polyphosphazene; polyphenylene; polybenzimidazole; polyether oxime; polyphenylene oxide; polycarbonate; polyurethane; polyquinoline Polyquine Porphyrin; polyurea; polyfluorene; polysulfonate; polybenzoate Azole; polybenzothiazole; polythiazole; polyphenyl quin Porphyrin; polyquinoline; polyoxane; poly three Polypyridine; polypyrimidine; poly Thiazole; polytetrazapyrene; poly Azole; polyvinylpyridine; polyvinylimidazole; polypyrrolidone; polytetrafluoroethylene; polydifluoroethylene; resin;

Forming reinforcement from the viewpoints of flexibility, mechanical strength, etc. The porous material is preferably composed of fibers, and from the viewpoint of productivity, non-woven fabric is more preferable. From the viewpoint of strength, as the above fibers, fibers of aramid fibers, glass fibers, cellulose fibers, nylon fibers, vinylon fibers, polyester fibers, polyolefin fibers, ray fibers, and the like are preferred. The aromatic unit is mainly used from the viewpoints of the mechanical durability and the chemical durability, the productivity (the ease of formation of a porous material, the ease of formation of a joined body to be described later), the startability of the material, and the like. The liquid crystal polyester fiber and the aramid fiber are more preferably composed of a liquid crystal polyester fiber mainly composed of an aromatic unit, from the viewpoint of low water absorption, acid resistance, and chemical resistance. These fibers may be used alone or in combination of two or more. In addition, as a non-woven fabric which consists of this fiber, a commercial item can be used suitably, for example, Vecrus (registered trademark) by KURARAY KURAFLEX Co., Ltd. is mentioned.

The liquid crystal polyester containing an aromatic unit as a main component of the fiber which forms the porous material of the above-mentioned reinforcing material exhibits optical anisotropy (liquid crystallinity) in the molten phase, and is derived from aromatic diol and aromatic A structural unit (aromatic unit) of a dicarboxylic acid or an aromatic hydroxycarboxylic acid is used as a main component. The liquid crystal polyester having the aromatic unit as a main component is preferably composed of, for example, a combination of structural unit groups represented by the following formulas (A) to (G) as a main component, p-hydroxybenzoic acid and 6-hydroxy- 2-naphthoic acid is a main component (the combination of the structural unit groups represented by the following formula (E) is a main component), or p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, or terephthalic acid. Further, it is more preferable that the biphenol is a main component (the combination of the structural unit groups represented by the following formula (G) is a main component). The term "principal component" as used herein refers to 50% of the liquid crystal polyester which has more than the aromatic unit as the main component. % by mass of ingredients.

(In the above formula, l, m, n, p, q, r, s and t are the numbers of the respective structural units, and each independently represents a number of 1 or more.)

From the viewpoint of improving the mechanical strength and chemical durability of the polymer electrolyte membrane, it is preferable that 70% or more of the fibers forming the porous material include a liquid crystal polyester fiber mainly composed of an aromatic unit, and more preferably 80% or more, and 90% or more. Very good.

The average fiber diameter of the fibers forming the porous material is The range of 0.5 to 20 μm is preferable, the range of 1 to 10 μm is better, and the range of 2 to 5 μm is particularly preferable.

When the porous material is a non-woven fabric, the basis weight of the nonwoven fabric is preferably 0.2 to 30 g/m ² , the range of 0.5 to 15 g/m ² is more preferable, and the range of 1 to 7 g/m ² is particularly preferable.

The method for producing the nonwoven fabric is not particularly limited, and examples thereof include a known method of producing a nonwoven fabric such as a dry method, a wet method, a spunbonding method, a flash spinning method, a melt blowing method, or a melt electrospinning method. Among them, from the viewpoint of making the average fiber diameter into a preferable range, it is preferable to manufacture by a melt blow method.

Further, the reinforcing material may contain a commonly used additive such as a coloring agent, an antioxidant, or an ultraviolet absorber, as needed.

[Method of Manufacturing Polymer Electrolyte Membrane]

Next, a method of producing the polymer electrolyte membrane of the present invention will be described. In the polymer electrolyte membrane of the present invention, the fluid composition including the block copolymer (Z), the compound (X) and the solvent forming the polymer electrolyte and the porous material serving as the reinforcing material are used to form the inclusion-containing block. The bonded body of the film-form molded body and the reinforcing material of the composition of the copolymer (Z) and the compound (X) (hereinafter simply referred to as "joined body") is obtained by crosslinking the molded body.

Specific examples of the method for forming the above-mentioned joined body include: 1) a method of disposing a porous material as a reinforcing material on a smooth substrate, and applying a fluid composition to the porous material, and removing the solvent; Applying the aforementioned fluid composition on a smooth substrate, in the flow The surface of the movable composition is a method in which the porous material of the reinforcing material is laminated, and the solvent is removed. 3) After applying the fluid composition on a smooth substrate, the porous material of the reinforcing material is formed on the molded body. After the material is laminated and the solvent is removed, a fluid composition is further applied thereon, and the solvent is removed.

As the substrate on which the fluid composition is applied, a smooth substrate composed of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), glass, or the like is usually used.

As a method of applying the fluid composition to a substrate or a porous material which is a reinforcing material, a method using a coater or an applicator may be mentioned.

In addition, as a method of applying the fluid composition to the porous material which is a reinforcing material, the porous material is continuously moved in the fluid composition, and the fluid composition is dipped. The method of nip.

At the time of forming the above-mentioned joined body, the impregnation of the fluid composition in the void of the porous material forming the reinforcing material may be simultaneously performed. Further, the porous material impregnated with the polymer electrolyte may be used in advance, and the joined body may be formed by any one of the above 1) to 3).

Further, in any one of the above 1) to 3), the same or different fluid composition may be further applied to one or both of the surfaces of the obtained joined body to remove the solvent. Further, a plurality of obtained joined bodies may be bonded together.

The temperature at which the solvent is removed does not decompose in the block copolymer (Z) The range can be arbitrarily selected, and a plurality of temperatures can also be arbitrarily combined. The removal of the solvent can be carried out under ventilated conditions or under vacuum conditions, 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.

By molding the molded body of the composition containing the block copolymer (Z) and the compound (X) in the bonded body obtained as described above, a polymer electrolyte can be formed, and the polymer electrolyte membrane of the present invention can be obtained. . As the crosslinking method, heating or energy beam irradiation such as electron beam or the like 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 removal of the solvent, further heating or active energy ray irradiation may be 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, and particularly preferably from 0.4 to 100 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.

As the active energy irradiation, for example, when the electron beam is crosslinked, 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.

Further, the block copolymer (Z) is crosslinked, and can be confirmed by an increase in hot water resistance, an increase in gel fraction, and the like, which will be described later.

The gel fraction of the polymer electrolyte membrane can be measured by the method described in the examples below, and is preferably 30% or more, more preferably 50% or more, more preferably 70% 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.

When a substrate is used for the formation of the bonded body, the polymer electrolyte membrane is usually peeled off from the substrate. In addition, when the bonded body is produced without using a substrate by the above-described immersion, nip or the like, peeling is not required.

[Examples]

The present invention will be specifically described below by way of examples, comparative examples and reference examples, but the 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. Phenolphthalein as an indicator with 0.01 equivalent of NaOH standard water The solution (force price f) titrates the hydrogen chloride produced in the water (titration amount b (ml)).

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. × 15cm) total 3 )

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 4 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 4 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)

A 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1 was prepared, and the release-treated PET film (Mitsubishi Resin) After coating with a thickness of about 300 μm, the product name: MRF) was dried at 100 ° C for 6 minutes in a hot air dryer to obtain a film-like polymer electrolyte. The wide-area dynamic viscoelasticity measuring apparatus ("DVE-V4FT Rheospectler" manufactured by Rheology Co., Ltd.) was used to obtain a film-like polymer electrolyte in a tensile mode (frequency: 11 Hz), a temperature increase rate of 3 ° C / min, and -80 The temperature was raised to 250 ° C, and the storage elastic modulus (E'), the loss elastic modulus (E"), and the loss tangent (tan δ) were measured. Based on the storage elastic modulus at 80 to 100 ° C which was not derived from the crystallized olefin polymer. The change in the number determines the amorphousness of the polymer block (B).

Similarly, 13% by mass of a toluene/isobutanol (mass ratio 7/3) solution of the block copolymer (Z-2) and 10% by mass of toluene/different of the block copolymer (Z-3) were used. Butanol/n-octane (mass ratio 3/3/4) solution, block copolymer (Z-4) 13% by mass of toluene/isobutanol (mass ratio 70/30) solution instead of block copolymer (13-1%) of a toluene/isobutanol (mass ratio 77/23) solution of (Z-1), and the amorphous state of the polymer block (B) was determined in the same manner.

As a result, in all of the above block copolymers (Z), the polymer block (B) was amorphous.

(Measurement of Filling Rate of Polymer Electrolyte in Reinforcing Material)

The polymer electrolyte membranes obtained in the examples and the comparative examples 1 to 4 were subjected to a concentrated ion beam (JEM-9320FIB manufactured by JEOL Ltd.) with an accelerating voltage. 30KV conditional cutting. Then, the cross section was analyzed using a super-high decomposition energy analysis scanning electron microscope (SU-70 manufactured by Hitachi High-Technologies) under the conditions of an acceleration voltage of 3 kV, a working distance (WD) of 15 mm, and a magnification of 3,500 times.

As a result, since no void portion was observed, the filling ratio was 100%.

[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 content of 2 L, and then stirred at 60 ° C while sequentially. 28.6 ml of styrene, 14.4 ml of 4-tert-butylstyrene, 28.6 ml of styrene, 14.4 ml of 4-tert-butylstyrene, 114.9 ml of isoprene, 14.4 ml of 4-tert-butylstyrene were added. 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- Tert-butylstyrene)-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, a three-necked flask containing 1 L of nitrogen was added, and 270 ml of dichloromethane and 149 ml of acetic anhydride were added, 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 equipped with a volume 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 room temperature for 4 hours. It dissolves. 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, 1000 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) 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, 7.5 ml of dehydrated cyclohexane, 3.33 ml of a second butyllithium (1.12 mol/L cyclohexane solution), and 27 ml of tetrahydrofuran were added to an autoclave having a nitrogen content of 2000 ml, and then stirred at 60 ° C. 28.3 ml of 4-tert-butylstyrene, 81.7 ml of styrene, 28.3 ml of 4-tert-butylstyrene, 171 ml of butadiene, 28.3 ml of 4-tert-butylstyrene, and styrene 81.7 were sequentially added. Polymerization of ml and 4-tert-butylstyrene 28.3 ml to obtain poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-tert-butylstyrene)-b- Polybutadiene-b-poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-tert-butylstyrene). The Mn of the obtained block copolymer was 108,000, the 1,4-bond amount of the polybutadiene block was 55.0%, and the content of the structural unit derived from styrene was 39.9 mass%, which originated from 4-third. The content of the structural unit of butyl styrene was 29.5% 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 polybutadiene polymer block (polymer block (B)), and poly(4-tert-butyl styrene) are obtained. Block copolymer (Z ₀ ) of polymer block (polymer block (C)) [poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-third Styrene)-b-polybutadiene-b-poly(4-tert-butylstyrene)-b-polystyrene-b-poly(4-tert-butylstyrene) (hereinafter referred to as " Block copolymer (Z ₀ -2)")]. The hydrogenated polybutadiene 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, a three-necked flask containing 1 L of nitrogen was added, and 114 ml of dichloromethane and 57.4 ml of acetic anhydride were added, and while stirring at 0 ° C, 33.4 ml of concentrated sulfuric acid was added dropwise, and the mixture was stirred at 0 ° C for 60 minutes to prepare a sulfonation. Agent. On the other hand, 40 g of the block copolymer (Z ₀ -2) was placed in a glass reaction vessel equipped with a 3 L inner volume of a stirrer, and after replacing nitrogen in the system, 522 ml of dichloromethane was added thereto, and the mixture was stirred at normal temperature for 4 hours. It dissolves. A 204 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, 600 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) used in the polymer electrolyte membrane of the present invention (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 2.9 meq/g.

[Manufacturing Example 3]

(Manufacture of block copolymer (Z ₀ -3))

After drying, 147 ml of dehydrated cyclohexane and 1.28 ml of second butyllithium (1.20 mol/L cyclohexane solution) were added to an autoclave having a nitrogen content of 1.4 L, and then stirred at 60 ° C. Add 28.0ml of styrene, 8.1ml of 4-tert-butylstyrene, 112ml of isoprene, 4-tert-butyl Polymerization of 8.1 ml of styrene and 28.0 ml of styrene to obtain polystyrene-b-poly(4-tert-butylstyrene)-b-polyisoprene-b-poly(4-tert-butylbenzene Ethylene)-b-polystyrene. The Mn of the obtained block copolymer was 159,000, 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 12.2% 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 -3)")]. The hydrogenated polyisoprene block of the obtained block copolymer (Z ₀ -3) had a hydrogenation rate of 99% or more.

(Manufacture of block copolymer (Z-3))

After drying, 161 ml of dichloromethane and 81 ml of acetic anhydride were added to a three-necked flask containing 1 L of nitrogen, and 36 ml of concentrated sulfuric acid was added dropwise while stirring at 0 ° C, 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 -3) was placed in a glass reaction vessel equipped with a 3 L inner volume 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. It dissolves. 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) used in the polymer electrolyte membrane of the present invention (hereinafter referred to as "Block copolymer (Z-3)"). The ratio (sulfonation ratio) of the obtained block copolymer (Z-3) 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.

[Manufacturing Example 4]

(Manufacture of block copolymer (Z ₀ -4))

After drying, 147 ml of dehydrated cyclohexane, 1.95 ml of tetrahydrofuran, and 1.99 ml of a second butyllithium (0.7 mol/L cyclohexane solution) were added to an autoclave having a nitrogen content of 1.4 L, and then at 40 ° C. After stirring, 21.6 ml of 4-methylstyrene, 140 ml of butadiene and 21.6 ml of 4-methylstyrene were sequentially added to polymerize to obtain poly(4-methylstyrene)-b-polybutadiene-b. - Poly(4-methylstyrene). The Mn of the obtained block copolymer was 78,000, and the 1,4-bond amount of the polybutadiene block determined from ¹ H-NMR (400 MHz) was 58.5%, and the structure derived from 4-methylstyrene The content of the unit was 30.0% 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 at a hydrogen pressure of 0.5 to 1 MPa and 70 ° C using a Ni/Al-based Ziegler-type catalyst. a block copolymer comprising a poly(4-methylstyrene) polymer block (polymer block (A ₀ )) and a hydrogenated polybutadiene polymer block (polymer block (B)) (Z ₀ ) [Poly(4-methylstyrene)-b-hydrogenated polybutadiene-b-poly(4-methylstyrene) (hereinafter referred to as "block copolymer (Z ₀ -4)")] . The hydrogenated polybutadiene block of the obtained block copolymer (Z ₀ -4) had a hydrogenation rate of 99% or more.

(Manufacture of block copolymer (Z-4))

In 35.1 ml of dichloromethane, 23.4 ml of acetic anhydride and 10.5 ml of sulfuric acid were mixed at 0 ° C to prepare a sulfonating agent. On the other hand, 50 g of the block copolymer (Z ₀ -4) was placed in a glass reaction vessel equipped with a 3 L stirrer, and the inside of the system was evacuated and the operation of introducing nitrogen was repeated three times to introduce nitrogen. After adding 612 ml of dichloromethane and stirring at room temperature for 4 hours to dissolve, 69.1 ml of the above sulfonating agent was added dropwise over 5 minutes. After stirring at normal temperature for 7 hours, 500 ml of distilled water was added dropwise with stirring to stop the reaction, and the solid was analyzed. After distilling off the dichloromethane 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 recovered 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-4). )"). The ratio (sulfonation ratio) of the obtained block copolymer (Z-4) to the sulfonic acid group derived from the structural unit derived from 4-methylstyrene was 65.2 mol%, and the ion exchange capacity was 1.5 meq/g.

[Example 1]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) , product name: MARUKA LYNCUR M, grade: S-1, Mn: 1100~1500) as compound (X), the mass ratio of block copolymer (Z-1) / poly-4-ethylphenol is 100/9.6 And preparing a fluid composition. Then, the flowable composition was applied to a PET film (Mitsubishi Resin, trade name: MRF) which was subjected to release treatment, and then a non-woven 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, hereinafter referred to as "non-woven fabric (a)"), and the wrinkles are not overlapped with the coated surface from above, and After impregnating the fluid composition in the void of the nonwoven fabric (a), it was dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 125 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). A bonded body having a thickness of 20 μm and a nonwoven fabric (a). The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 2]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, grade: S-1) As the compound (X), the mass ratio of the block copolymer (Z-1)/poly-4-vinylphenol is 100/9.6, and the fluid composition is prepared. Things. Next, the nonwoven fabric (a) is not wrinkled from above by coating the fluid composition on a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) at a thickness of about 125 μm. Parallel to the coated surface and overlap, and not woven After impregnating the fluid composition in the void of (a), it was dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 75 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). The body and the non-woven fabric (a) have a thickness of 16 μm. The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Example 3]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, grade: S-1) As the compound (X), the mass ratio of the block copolymer (Z-1)/poly-4-vinylphenol is 100/9.6, and the fluid composition is prepared. Things. Next, the non-woven fabric (a) is not wrinkled from above by coating the fluid composition on a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) with a thickness of about 200 μm. The liquid composition was placed in parallel with the coated surface, and the fluid composition was impregnated into the void of the nonwoven fabric (a), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 150 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). The body and the non-woven fabric (a) have a thickness of 27 μm. The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Example 4]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, grade: S-1) As the compound (X), the mass ratio of the block copolymer (Z-1)/poly-4-vinylphenol is 100/9.6, and the fluid composition is prepared. Things. Then, the flowable composition was applied to a PET film (Mitsubishi Resin, trade name: MRF) which was subjected to release treatment, and then a non-woven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus) was applied. (registered trademark), an average fiber diameter of 7 μm, a basis weight of 6 g/cm ² , a porosity of 68.9%, and a thickness of 14 μm, hereinafter referred to as "non-woven fabric (b)"), which are not caused by the fact that the wrinkles are parallel to the coated surface and overlap. After impregnating the fluid composition in the void of the nonwoven fabric (b), it was dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 125 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). A bonded body having a thickness of 20 μm and a nonwoven fabric (b). The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Example 5]

(Production of polymer electrolyte membrane)

In addition to using a non-woven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus (registered trademark), an average fiber diameter of 3 μm, a basis weight of 2.4 g/cm ² , a porosity of 86.8%, and a thickness of 13 μm, hereinafter referred to as "non-woven fabric (c)" In the same manner as in Example 1, except that the nonwoven fabric (a) was used, a polymer electrolyte membrane having a thickness of 20 μm was produced.

[Embodiment 6]

(Production of polymer electrolyte membrane)

In addition to the use of another non-woven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus (registered trademark), average fiber diameter 3 μm, basis weight 2.7 g/cm ² , porosity: 84.6%, thickness 13 μm, hereinafter referred to as "non-woven fabric (d)" In the same manner as in Example 1, except that the nonwoven fabric (a) was used, a polymer electrolyte membrane having a thickness of 20 μm was produced.

[Embodiment 7]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, grade: S-1) As the compound (X), the mass ratio of the block copolymer (Z-1)/poly-4-vinylphenol is 100/9.6, and the fluid composition is prepared. Things. Next, by coating the fluid composition on a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) at a thickness of about 200 μm, a polyester-based nonwoven fabric (Kwana Paper Co., Ltd.) was used. ), product name: 05TH-8, basis weight 7.6g/cm ² , porosity: 85.5%, thickness 38μm, hereinafter referred to as "non-woven fabric (e)"), no wrinkles are formed from above, and the coated surface is parallel and overlaps. Further, the fluid composition was impregnated in the void of the nonwoven fabric (e), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further coated thereon by a thickness of about 250 μm, dried at 100 ° C for 6 minutes in a hot air dryer, and coated with the above fluid composition at a thickness of about 250 μm, and dried at 100 ° C in a hot air dryer. After 6 minutes, a molded body containing a composition of the block copolymer (Z-1) and the compound (X) and a bonded body having a thickness of 45 μm of the nonwoven fabric (e) were obtained. The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 8]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 7/3) solution of the block copolymer (Z-2) obtained in Production Example 2, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) , product name: MARUKA LYNCUR M, grade: S-1) as compound (X), the mass ratio of block copolymer (Z-2) / poly-4-vinylphenol is 100/10.5, in addition to In the same manner as in Example 1, a polymer electrolyte membrane having a thickness of 20 μm was produced.

[Embodiment 9]

(Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/n-octane (mass ratio 3/3/4) solution of the block copolymer (Z-3) obtained in Production Example 3, poly-4-vinylphenol was added ( Maruzen Petrochemical Co., Ltd., product name: MARUKA LYNCUR M, grade: S-1) As compound (X), the mass ratio of block copolymer (Z-3)/poly-4-vinylphenol is 100/9.4 And preparing a fluid composition. Next, by applying the fluid composition to a release-treated PEN film (manufactured by Teijin DuPont Films, trade name: Q31M) at a thickness of about 200 μm, the nonwoven fabric (a) is not caused to wrinkle and coat from above. The surfaces were overlapped in parallel, and the fluid composition was impregnated into the voids of the nonwoven fabric (a), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to a thickness of about 200 μm thereon, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a block copolymer (Z-3) and a compound (X). The molded body of the composition and the bonded body of the nonwoven fabric (a) having a thickness of 27 μm. The obtained joined body was heat-treated at 140 ° C for 6 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 10]

(Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/n-octane (mass ratio 3/3/4) solution of the block copolymer (Z-3) obtained in Production Example 3, poly-4-vinylphenol was added ( Maruzen Petrochemical Co., Ltd., product name: MARUKA LYNCUR M, grade: S-1) As compound (X), the mass ratio of block copolymer (Z-3)/poly-4-vinylphenol is 100/9.4 And preparing a fluid composition. Next, by applying the fluid composition to a release-treated PEN film (manufactured by Teijin DuPont Films, trade name: Q31M) at a thickness of about 150 μm, the nonwoven fabric (a) is not wrinkled and coated from above. The surfaces were overlapped in parallel, and the fluid composition was impregnated into the voids of the nonwoven fabric (a), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to a thickness of about 175 μm thereon, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). A bonded body having a thickness of 20 μm and a nonwoven fabric (a). The obtained joined body was heat-treated at 140 ° C for 6 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Example 11]

(Production of polymer electrolyte membrane)

After preparing a 10% by mass toluene/isobutanol/n-octane (mass ratio 3/3/4) solution of the block copolymer (Z-3) obtained in Production Example 3, 2,6-bis (2) was added. -hydroxy-5-methylbenzyl)-4-cresol (asahi Organic Industry Co., Ltd.) as Compound (X), the mass ratio of the block copolymer (Z-3)/2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol was 100/4.5, and the fluidity was prepared. Composition. Next, by applying the fluid composition to a release-treated PEN film (manufactured by Teijin DuPont Films, trade name: Q31M) at a thickness of about 150 μm, the nonwoven fabric (a) is not wrinkled and coated from above. The surfaces were overlapped in parallel, and the fluid composition was impregnated into the voids of the nonwoven fabric (a), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to a thickness of about 175 μm thereon, and dried at 100 ° C for 30 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-3) and the compound (X). A bonded body having a thickness of 20 μm and a nonwoven fabric (a). The obtained joined body was heat-treated at 120 ° C for 6 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 12]

(Production of polymer electrolyte membrane)

A polymer electrolyte membrane having a thickness of 20 μm was produced in the same manner as in Example 11 except that the nonwoven fabric (c) was used instead of the nonwoven fabric (a).

[Example 13]

(Production of polymer electrolyte membrane)

A polymer electrolyte membrane having a thickness of 20 μm was produced in the same manner as in Example 11 except that the nonwoven fabric (d) was used instead of the nonwoven fabric (a).

[Embodiment 14]

(Production of polymer electrolyte membrane)

In addition to using 2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol (manufactured by Asahi Organic Materials Co., Ltd.) as the compound (X), the block copolymer (Z-1) was used. The mass ratio of /2,6-bis(2-hydroxy-5-methylbenzyl)-4-cresol is The addition was carried out in the same manner as in Example 1 except that 100/4.5 was added, and a molded body having a thickness of 20 μm was obtained.

[Example 15]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, grade: S-1) As the compound (X), the mass ratio of the block copolymer (Z-1)/poly-4-vinylphenol is 100/9.6, and the fluid composition is prepared. Things. Then, the flowable composition was applied to a PET film (Mitsubishi Resin, trade name: MRF) which was subjected to release treatment, and then a non-woven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus) was applied. (registered trademark), an average fiber diameter of 3 μm, a basis weight of 4.5 g/cm ² , a porosity of 64.3%, and a thickness of 9 μm, hereinafter referred to as "non-woven fabric (f)"), which do not cause wrinkles and overlap with the coated surface from above. Further, the fluid composition was impregnated in the void of the nonwoven fabric (f), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 125 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). A bonded body having a thickness of 20 μm and a nonwoven fabric (f). The obtained joined body was heat-treated at 140 ° C for 1.5 hours under a nitrogen stream to crosslink the molded body to prepare a polymer electrolyte membrane of the present invention.

[Comparative Example 1]

(Production of polymer electrolyte membrane)

13% by mass of the block copolymer (Z-1) obtained in Production Example 1 was prepared. A solution of toluene/isobutanol (mass ratio 77/23). Next, by applying the solution to a thickness of about 150 μm on a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF), the nonwoven fabric (a) is not caused to wrinkle and coated from above. After being paralleled and overlapping, and impregnating the solution in the void of the nonwoven fabric (a), it was dried at 100 ° C for 6 minutes in a hot air dryer. The solution was further applied to a thickness of about 150 μm thereon, and dried at 100 ° C for 6 minutes in a hot air dryer to prepare a polymer electrolyte membrane having a thickness of 20 μm.

[Comparative Example 2]

(Production of polymer electrolyte membrane)

A polymer electrolyte membrane having a thickness of 20 μm was produced in the same manner as in Comparative Example 1, except that the nonwoven fabric (b) was used instead of the nonwoven fabric (a).

[Comparative Example 3]

(Production of polymer electrolyte membrane)

After preparing a 13% by mass toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, 1,2-polybutadiene was added (Japan Soda) ), product name: PB-1000, number average molecular weight 1,000, degree of polymerization 19) as a crosslinking agent, the mass ratio of block copolymer (Z-1) / 1,2-polybutadiene is 100 / 5.0 And preparing a fluid composition. Next, the non-woven fabric (b) is not wrinkled from above by coating the fluid composition on the release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) at a thickness of about 150 μm. The liquid composition was placed in parallel with the coated surface, and the fluid composition was impregnated into the void of the nonwoven fabric (b), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further coated thereon by a thickness of about 150 μm, and dried at 100 ° C in a hot air dryer. After 6 minutes, a molded body containing a composition of the block copolymer (Z-1) and 1,2-polybutadiene and a bonded body having a thickness of 20 μm of the nonwoven fabric (b) were obtained. An electron curtain type electron beam irradiation apparatus (manufactured by Iwasaki Electric Co., Ltd., trade name: CB250/30/20 mA) was used for the obtained bonded body, and an acceleration voltage of 150 kV, a beam current of 8.6 mA, and a dose of 300 kGy were applied. The molded body was crosslinked by electron beam irradiation to prepare a polymer electrolyte membrane.

[Comparative Example 4]

(Production of polymer electrolyte membrane)

A 13% by mass toluene/isobutanol (mass ratio 70/30) solution of the block copolymer (Z-4) obtained in Production Example 4 was prepared. Next, the non-woven fabric (b) is not wrinkled from above by coating the fluid composition on the release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) at a thickness of about 150 μm. The liquid composition was placed in parallel with the coated surface, and the fluid composition was impregnated into the void of the nonwoven fabric (b), and then dried at 100 ° C for 6 minutes in a hot air dryer. The above fluid composition was further applied to the above-mentioned fluid composition by a thickness of about 150 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a molded body containing a block copolymer (Z-4) and a nonwoven fabric (b). a bonded body having a thickness of 20 μm. The obtained joined body was heat-treated at 130 ° C under a pressure of 1 MPa for 5 minutes to crosslink the molded body to prepare a polymer electrolyte membrane.

[Reference Example 1]

(Production of polymer electrolyte membrane)

After preparing a 11.5 mass% toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-1) obtained in Production Example 1, poly-4-vinylphenol was added (Maruzen Petrochemical Co., Ltd.) Product name: MARUKA LYNCUR M, etc. Grade: S-1) As the compound (X), a mass ratio of the block copolymer (Z-1) / poly-4-ethylphenol was 100 / 9.6, and a fluid composition was prepared. Next, the fluid composition was applied to a PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF) having a thickness of about 300 μm, and dried at 100 ° C for 6 minutes in a hot air dryer to obtain a fluid composition. A molded body having a thickness of 20 μm. The obtained joined body was heat-treated at 140 ° C for 1 hour under a nitrogen stream to crosslink, thereby producing a polymer electrolyte membrane containing a film-like polymer electrolyte.

(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)

The polymer electrolyte membrane obtained in the examples, the comparative examples and the reference examples was cut out into a test piece of 3 cm × 5 cm, 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. Next, the surface state (visual test) of the test piece in the screw tube was visually confirmed, and then 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 (1a) was determined by the following formula.

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

Moreover, the same test piece obtained from the same polymer electrolyte membrane was used, and the same test was performed, and the insoluble matter residual ratio (1b) was calculated|required.

The insoluble matter residual ratio (1a) and the insoluble matter residual ratio (1b) 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)

From the polymer electrolyte membrane obtained in the examples, the comparative examples and the reference examples, a test piece of 4 cm × 8 cm was cut out and weighed by a precision balance. Set the mass at this time to M ₁ . The test piece attached to the cylindrical filter paper was refluxed for 8 hours using a Soxhlet extractor in 100 ml of tetrahydrofuran. Thereafter, the test piece was taken out, and tetrahydrofuran was distilled off under conditions of 11 kPa and 40 ° C, and further dried at 1.3 kPa and 80 ° C for 12 hours. The quality of the solid residue only after drying with a precision balance. The mass at this time was taken as M ₂ , and the gel fraction was calculated according to the following formula.

Gel fraction = ((M _{1 -} M ₂ ) / M ₁ ) × 100 (%)

(Measurement of mechanical strength (tensile breaking strength))

The polymer electrolyte membrane obtained in the examples, the comparative examples, and the reference examples was cut out into a dumbbell-shaped test piece, and the mixture was conditioned at 25 ° C and a relative humidity of 40%, and then attached to a tensile tester (manufactured by Instron Japan Co., Ltd., Type: Model 5566), tensile breaking strength was measured under the conditions of 25 ° C, relative humidity of 40%, and tensile speed of 500 mm / min.

(Measurement of dimensional change rate in hot water at 80 ° C)

The polymer electrolyte membrane obtained in the examples, the comparative examples and the reference examples was allowed to stand at 23 ° C and a relative humidity of 50% for 12 hours, and then a test piece of 1 cm × 4 cm was cut out and immersed in hot water at 80 ° C for 4 hours. After that, the length b (cm) of the test piece taken out from the hot water in the longitudinal direction was measured, and the dimensional change rate was obtained by the following formula.

Dimensional change rate (%) = [(b-4) / 4] × 100

[Voltage Decline Rate of Solid Polymer Fuel Cell]

The polymer electricity obtained by evaluating the examples, comparative examples and reference examples For the purpose of influencing the performance of the polymer electrolyte fuel cell, the fuel cell for evaluation of the polymer electrolyte membrane was used to measure the voltage drop rate at a high temperature.

First, the polymer electrolyte membrane was cut out to 9 cm × 9 cm, and the inside was cut into a 5 cm × 5 cm PTFE film having a thickness of 12.5 μm, and contained Pt catalyst-carrying carbon and NAFION D1021 (made by DuPont). After the catalyst layer of (trade name) was sandwiched between the electrodes of the carbon paper, heat treatment (115 ° C, 1 MPa, 8 minutes) was performed by hot pressing to prepare a membrane-electrode assembly (MEA). 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 clamped by two collector plates and two sheets. The board is clamped and the evaluation battery is produced. The load current control terminal connected to the gas supply hose, the drain hose (the drain recovery bottle is attached to the cathode side), the heater power supply, the thermocouple, and the power generation characteristic analyzer (NF circuit design) The voltage detecting terminal is connected to the fabricated evaluation battery, and assembled into an evaluation fuel cell. Hydrogen was supplied to the electrode (anode) of one of the evaluation fuel cells at 70 cc/min, and air was supplied to the other electrode (cathode) at 240 cc/min, and was operated under the following conditions, and the voltage drop rate was measured.

Battery temperature: 80 ° C

Relative humidity: 100%

Current density: 0.3A/cm ²

(The voltage drop rate of the fuel cell is 1)

The evaluation fuel cell was operated until 1200 hours, and the voltage value measured by the voltage detecting terminal connected to the evaluation fuel cell was used to track the voltage value accompanying the operation time, and the initial value was decreased with respect to the start. The voltage value at that time is measured down to 10% of the time.

(The voltage drop rate of the fuel cell is 2)

The voltage value V ₁ (V) after 500 hours of operation and the voltage value V ₂ (V) after 1200 hours of operation were measured by the voltage detecting terminal connected to the fuel cell for evaluation described above, and the voltage drop was calculated by the following formula. speed.

Voltage drop rate (μV/hour) = {(V ₁ - V ₂ ) / (1200-500)} × 10 ⁶

(start stop durability test)

The polymer electrolyte membranes obtained in the examples, the comparative examples, and the reference examples were cut out to a size of 9 cm × 9 cm, and the PET film having a thickness of 25 μm cut into a thickness of 5 cm × 5 cm was sandwiched on both sides, and contained in a Pt-containing catalyst. Carbon and NAFION D1021 (manufactured by DuPont) (product name) and two electrodes of carbon paper, so that each film and the catalyst surface are opposed to each other, and the outside is made of 2 pieces of stainless steel. The plate was sandwiched, and a membrane-electrode assembly was produced by hot pressing (115 ° C, 2 MPa, 8 minutes). Next, the produced membrane-electrode assembly is sandwiched between two sheets of electrically conductive separators that function as a gas supply flow path, and the outer side is sandwiched between two current collector plates and two clamping plates. A single cell was fabricated (electrode area was 25 cm ² ).

Next, the load current control terminal connected to the gas supply hose, the drain hose, the heater power source, the thermocouple, and the power generation characteristic analyzer (NF circuit design) is connected to the voltage detection terminal. Single cell, and assembled fuel cell for evaluation.

While the temperature of the cell was raised to 80 ° C, nitrogen (bubble temperature: 90 ° C) of 80 ° C and 150% RH was supplied from the fuel supply pipe to the anode and the cathode at 200 cc / min. Next, the temperature of the unit cell was maintained at 80 ° C, 150% RH of hydrogen was supplied to the anode at a rate of 200 ml/min, and the cathode was A nitrogen of 150% RH was supplied at a rate of 200 ml/min. Linear scanning voltammetry was carried out 1 hour after the start of the supply. The current value of each voltage value when the voltage value was changed from 0.08 V to 0.50 V at a speed of 0.5 mV/sec was measured, and the amount of hydrogen leakage (L0) was evaluated based on the current value at 0.4 V.

Thereafter, the temperature of the unit cell was maintained at 80 ° C, the anode was supplied with 150% RH of nitrogen at a rate of 2000 ml/min, and the cathode was supplied with 150% RH of nitrogen at a rate of 2000 ml/min for 2 minutes, and the anode was Dry nitrogen (water content: 0.37 ppm) was supplied at a rate of 2000 ml/min, and dry nitrogen was supplied to the cathode at a rate of 2000 ml/min for 2 minutes. This operation was repeated 250 times. Then, the temperature of the unit cell was maintained at 80 ° C, 150% RH of hydrogen was supplied to the anode at a rate of 200 ml/min, and 150% of RH of nitrogen was supplied to the cathode at a rate of 200 ml/min for 1 hour. Thereafter, linear sweep voltammetry was carried out to evaluate the first hydrogen leakage amount (L1). And repeating 250 times to maintain the temperature of the above-mentioned single cell at 80 ° C, supplying 150% RH of nitrogen to the anode at a rate of 2000 ml/min, and supplying 150% RH of nitrogen to the cathode at a rate of 2000 ml/min for 2 minutes, and The anode was supplied with dry nitrogen at a rate of 2000 ml/min, and the cathode was supplied with dry nitrogen at a rate of 2000 ml/min for 2 minutes. Next, the temperature of the unit cell was maintained at 80 ° C, 150% RH of hydrogen was supplied to the anode at a rate of 200 ml/min, and 150% of RH of nitrogen was supplied to the cathode at a rate of 200 ml/min for 1 hour, and linear sweep voltammetry was performed. In the method of repeating the evaluation of the amount of hydrogen leakage, the stage in which the n-th hydrogen leakage amount (Ln) is 10 times or more of L0 is used as the end point. The value obtained by multiplying n by 250 is shown as "cycle number" and is shown in Table 1.

(Initial power generation characteristics test)

The same as the above-mentioned start-stop durability test, using assembled The evaluation fuel cell was subjected to an initial power generation characteristic test in accordance with the following operation.

<Operation 1>

Nitrogen at 80 ° C and 100% RH was supplied to the anode and the cathode at 500 ml/min for 30 minutes while the unit cell was heated to 80 ° C. Next, hydrogen at 80 ° C and 100% RH was supplied to the anode at a rate of 100 ml/min, and air at 80 ° C and 100% RH was supplied to the cathode at a rate of 100 ml/min for 30 minutes.

<Operation 2>

The temperature of the unit cell was maintained at 80 ° C, hydrogen was supplied to the anode at 80 ° C and 100% RH, and air at 80 ° C and 100% RH was supplied to the cathode while the current value was stepwise increased from 0 A to 1.25 A. The voltage value of each current value was measured, and when the voltage value became 0.01 V or less, the current value was returned to 0 A. In addition, the amount of hydrogen supplied to the anode and the amount of supply of air to the cathode are set to 46 ml/min and 168 ml/min in the current values 0A, 1.25A, and 2.5A, respectively, and are set at 3.75A or higher. For stoichiometry 1.5, stoichiometry 2.0. Further, in each current value, the current value was kept for 1 minute each.

This operation was repeated four times to bring the polymer electrolyte membrane into a wet state.

<Operation 3>

By placing the cells for the polymer electrolyte fuel cell in a cool state and supplying the non-humidified nitrogen to the battery cells of the anode and the cathode at a rate of 1000 ml/min for 12 hours, the polymer electrolyte membrane becomes Dry state.

<Operation 4>

In addition to changing the humidity of hydrogen and air to 30% RH, it is implemented. The same operation as operation 1.

<Operation 5>

The same operation as in operation 2 was carried out except that the humidity of hydrogen and air was changed to 30% RH, and the number of repetitions was changed to three times. The current of the third time of the repetition was measured to be 12.5 A (current density 0.5 A/ The resistance value obtained when cm ² ) and 25.0 A (current density 1.0 A/cm ² ).

As shown in Table 1, the polymer electrolyte membrane of the present invention exhibited high hot water resistance. It is understood that Comparative Examples 1 and 2 are not significantly crosslinked, and therefore the hot water resistance is remarkably lower than that of the polymer electrolyte membrane of the present invention. Since the polymer electrolyte membrane of Comparative Example 3 is a polymer electrolyte membrane which is crosslinked by a crosslinking agent other than the compound (X), the hot water resistance thereof is remarkably lower than that of the polymer electrolyte membrane of the present invention.

It is considered that the polymer electrolyte membrane of Comparative Example 4 has a 4-methylstyrene portion thermally crosslinked, but it is understood that since the compound (X) is not used, the ion exchange capacity is low compared to Example 1, although the ion exchange capacity is low. The hot water resistance is also significantly lower.

As is clear from the examples 1 to 15, as long as the block copolymer (Z) is crosslinked and has a polymer electrolyte membrane as a reinforcing material of a porous material, the dimensional change rate in the planar direction is small and the hot water resistance is high.

In the polymer electrolyte membrane of the present invention, when the fuel cell is incorporated and operated, the voltage drop is small and the start-stop is endurance. The durability of 10,000 cycles or more can also be ensured in the sex test. The above can be estimated as a decrease in the excellent hot water resistance of the polymer electrolyte membrane according to the present invention and the expansion ratio in the planar direction.

In the polymer electrolyte membranes containing the reinforcing material having a porosity of 70% or more, the polymer electrolyte membrane of Reference Example 1 which does not contain the reinforcing material is shown in the first, fourth, fifth, sixth, and fifth embodiments. The polymer electrolyte membrane having a specific resistance or less, particularly a polymer electrolyte membrane containing a reinforcing material having a porosity of 80% or more, exhibits a significantly lower resistance value compared to the polymer electrolyte membrane of Reference Example 1, and thus the initial power generation characteristics are obtained. good.

(Evaluation of softness of polymer electrolyte)

The following evaluation was carried out for the purpose of confirming that the polymer electrolyte membrane of the present invention is soft and difficult to be broken.

[Evaluation Example 1]

The polymer electrolyte membrane (membranous polymer electrolyte) obtained in Reference Example 1 was cut out into a dumbbell-shaped test piece, and was conditioned at 25 ° C and a relative humidity of 40%, and then attached to a tensile tester (Instron). The Japanese company's Model 5566 was used to measure tensile breaking strength and tensile elongation at break at 25 ° C, relative humidity of 40%, and tensile speed of 500 mm/min. The results are shown in Table 2.

[Evaluation Example 2]

(Production of film-like polymer electrolyte)

After preparing a 10% by mass toluene/isobutanol/n-octane (mass ratio 3/3/4) solution of the block copolymer (Z-3) obtained in Production Example 3, poly-4-vinylphenol was added ( Maruzen Petrochemical Co., Ltd., product name: MARUKA LYNCUR M, grade: S-1) As compound (X), the mass ratio of block copolymer (Z-3)/poly-4-vinylphenol is 100/9.4 And preparing a fluid composition. Then, the fluid composition was applied onto a release-treated PEN film (manufactured by Teijin DuPont Films, trade name: Q31M), and then dried at 100 ° C for 6 minutes in a hot air dryer to obtain 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, thereby producing a film-shaped polymer electrolyte membrane.

Using the obtained polymer electrolyte, tensile breaking strength and tensile elongation at break were measured in the same manner as in Evaluation Example 1. The results are shown in Table 2.

[Evaluation Example 3]

(Production of film-like polymer electrolyte)

After preparing a 11.5 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. Then, the fluid composition was applied onto a release-treated PET film (manufactured by Mitsubishi Resin Co., Ltd., trade name: MRF), and dried in a hot air dryer at 100 ° C for 6 minutes to obtain 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, thereby producing a film-shaped polymer electrolyte membrane.

Using the obtained polymer electrolyte, tensile breaking strength and tensile elongation at break were measured in the same manner as in Evaluation Example 1. The results are shown in Table 2.

[Evaluation Example 4]

(Production of film-like polymer electrolyte)

After preparing a 10% by mass toluene/isobutanol/n-octane (mass ratio 3/3/4) solution of the block copolymer (Z-3) obtained in Production Example 3, 2,6-bis (2) was added. -Hydroxy-5-methylbenzyl)-4-cresol (manufactured by Asahi Organic Materials Co., Ltd.) as compound (X) to make block copolymer (Z-3)/2,6-bis(2- The mass ratio of hydroxy-5-methylbenzyl)-4-cresol was 100/4.5, and a fluid composition was prepared. Then, the fluid composition was applied onto a release-treated PEN film (manufactured by Teijin DuPont Films, trade name: Q31M), and then dried at 100 ° C for 6 minutes in a hot air dryer to obtain 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, thereby producing a film-shaped polymer electrolyte membrane.

Using the obtained polymer electrolyte, tensile breaking strength and tensile elongation at break were measured in the same manner as in Evaluation Example 1. The results are shown in Table 2.

As shown in Table 2, the polymer electrolyte contained in the polymer electrolyte membrane of the present invention is excellent in tensile breaking strength and tensile elongation at break, and is therefore soft and difficult to be broken. The polymer electrolyte membrane of the present invention containing the polymer electrolyte and the reinforcing material has such flexibility, and as shown in Table 1, the tensile breaking strength is further improved.

[Industrial availability]

According to the present invention, it is possible to provide a polymer electrolyte membrane which is made of a non-fluorine-based material, is soft and hard to be broken, and is excellent in hot water resistance. In addition, the polymer electrolyte membrane of the present invention has a small dimensional change in hot water, and is excellent in start-stop durability when applied to a polymer electrolyte fuel cell, and is therefore applicable to a polymer electrolyte fuel cell. .

Claims (9)

A polymer electrolyte membrane comprising a polymer electrolyte membrane containing a reinforcing material, wherein the polymer electrolyte membrane contains a polymer obtained by crosslinking a molded body containing a composition of the block copolymer (Z) and the compound (X) An electrolyte, 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 a structural unit comprising an unsaturated aliphatic hydrocarbon derived from An amorphous polymer block (B) having no ion conductive group, wherein the compound (X) is an aromatic ring having two or more hydrogen atoms substituted with a hydroxyl group in the molecule, and the reinforcing material is porous material. The polymer electrolyte membrane of claim 1, wherein the porous material is a nonwoven fabric. The polymer electrolyte membrane according to claim 1 or 2, wherein the unsaturated aliphatic hydrocarbon is at least one selected from the group consisting of an alkene having 4 to 8 carbon atoms and a conjugated diene having 4 to 8 carbon atoms. The polymer electrolyte membrane according to claim 3, wherein the polymer block (B) is obtained by hydrogenating a carbon-carbon double bond of a polymer block formed by polymerizing the conjugated diene, and the hydrogenation rate is 30 mol. More than 8% of the ear. The polymer electrolyte membrane according to any one of claims 1 to 4, wherein the block copolymer (Z) further comprises: a polymer comprising a structural unit derived from an aromatic vinyl compound and having no ion conductive group Block (C). The polymer electrolyte membrane according to any one of claims 1 to 5, wherein the content of the compound (X) in the composition is 0.1 to 25 mass based on 100 parts by mass of the block copolymer (Z). Share. The polymer electrolyte membrane according to any one of claims 1 to 6, wherein the compound (X) is selected from the group consisting of a compound having two of the aromatic rings in the molecule, and a compound having three of the aromatic rings in the molecule, in the molecule At least one of a compound having six such aromatic rings and a polymer having a phenol skeleton as a repeating unit. The polymer electrolyte membrane according to any one of claims 1 to 6, wherein the porous material has a porosity of 70 to 95%. A polymer electrolyte fuel cell having the polymer electrolyte membrane according to any one of claims 1 to 8.