TW201537817A - Polyelectrolyte film - Google Patents

Abstract

Provided is a polyelectrolyte film that is obtained by performing a crosslinking treatment after forming a composition that contains: a block copolymer (Z) comprising a polymer block (A) that has an ion-conducting group and that comprises a structural unit that is derived from an aromatic vinyl compound and an amorphous polymer block (B) that does not have an ion-conducting group and that comprises a structural unit that is derived from an unsaturated aliphatic hydrocarbon; and a compound (X) that is represented by formula (1) (in the formula, R1 represents a hydrogen atom, a hydroxyl group, or an alkyl group that has 1-4 carbon atoms, R2 represents a hydrogen atom, a hydroxyl group, an alkyl group that has 1-4 carbon atoms, or an alkoxy group that has 1-4 carbon atoms, and R3 represents a hydroxyalkyl group that has 1-4 carbon atoms).

Description

Polymer electrolyte membrane

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

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

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

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

On the other hand, a polymer electrolyte membrane is known, which A structural unit derived from an aromatic vinyl compound and a block copolymer containing a polymer block having an ion conductive group and a flexible polymer block (see 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, a solid polymer type using hydrogen as a fuel In the fuel cell, in order to increase the output, it is necessary to increase the temperature of use, and in order to improve the durability (hot water resistance) of the polymer electrolyte membrane for hot water (for example, 90 ° C or higher), specifically, It is possible to suppress the elution of the polymer electrolyte membrane due to hot water or to suppress the voltage drop accompanying the operation for a long period of time at a high temperature.

For example, it is known to use the above flexible polymer block as a source The structural unit of the vinyl compound enhances the hot water resistance of the polymer electrolyte membrane by crosslinking the block copolymer of the flexible polymer block with 1,2-polybutadiene or the like as a main component (refer to the patent literature) 3).

Prior technical literature Patent literature

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

Patent Document 2 International Publication No. 2006/070929

Patent Document 3 International Publication No. 2012/043400

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

Accordingly, an object of the present invention is 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.

According to the invention, the above object is achieved by providing the following polymer electrolyte membrane.

In the polymer electrolyte membrane, the composition containing the block copolymer (Z) and the compound (X) represented by the following formula (1) (hereinafter simply referred to as "compound (X)") is subjected to crosslinking treatment after molding. The block copolymer (Z) comprises a polymer block (A) comprising an ion conductive group derived from a structural unit derived from an aromatic vinyl compound (hereinafter referred to as "polymer block (A)" And an amorphous polymer block (B) containing a structural unit derived from an unsaturated aliphatic hydrocarbon and having no ion conductive group (hereinafter simply referred to as "polymer block (B)").

(wherein R ¹ represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms; and R ² represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms; and R ³ A hydroxyalkyl group having a carbon number of 1 to 4.

According to the present invention, it is possible to provide a polymer electrolyte membrane which is composed of a non-fluorine-based material, is soft and hard to be broken, and is excellent in hot water resistance.

Fig. 1 is a graph showing the relationship between the operation time and the voltage of the polymer electrolyte fuel cell of the present invention.

Form of implementing the invention [Polymer electrolyte membrane]

The polymer electrolyte membrane of the present invention crosslinks a composition containing the block copolymer (Z) containing the polymer block (A) and the polymer block (B) and the compound (X) after forming. Processed.

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

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

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

The polymer electrolyte membrane of the present invention may also comprise a polymer electrolyte comprising at least one layer of a composition comprising a block copolymer (Z) of a polymer block (A) and a polymer block (B) and a compound (X) after crosslinking after molding Multilayer film of layers.

(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 obtained polymer electrolyte membrane has high tensile elongation at break properties; when it is 300,000 or less, particularly 180,000 or less, it contains a block copolymer ( The 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 0.8 to 3.2 meq/g, and particularly preferably in the range of 1.3 to 3.0 meq/g, and 1.8 to 2.8 meq/ The range of g is the best. The polymer electrolyte membrane obtained by the present invention has a good ion conductivity of 0.4 meq/g or more, and 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 embedded The segment (A) and the polymer block (B) 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.

Polymer block (A) and polymer in block copolymer (Z) The bonding arrangement of the block (B) 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 of the polymer electrolyte membrane obtained by the present invention, an ABA type triblock copolymer, an ABABA type pentablock copolymer, and an (AB) _n D type star copolymer are preferred, and ABA The triblock copolymer is more preferred. In the polymer electrolyte membrane of the present invention, the block copolymers may be used alone or in combination of two or more.

The block copolymer (Z ₀ ) (the total amount of the polymer blocks (A ₀ )): (the total amount of the polymer blocks (B)), in the range of 95:5 to 5:95 by mass ratio Preferably, the range of 75:25~15:85 is better, the range of 65:35~20:80 is particularly good, and the range of 50:50~25:75 is the best. When the mass ratio is within the above range, the obtained polymer electrolyte membrane has durability (starting stop durability) in terms of ion conductivity, mechanical strength, and re-wetting and drying with the start and stop of the polymer electrolyte fuel cell. There is an excellent tendency.

<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, hydrogen on the vinyl group of the above aromatic vinyl compound In the atom, 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 with 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 other monomers are mixed with the above aromatic vinyl compound and then polymerized. 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. When Mn is 1,000 or more, particularly 6,000 or more, ion conductivity is good. When the Mn is 100,000 or less, particularly 30,000 or less, the hot water resistance is good, and the above-described composition containing the block copolymer (Z) and the compound (X) is excellent in moldability and 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 embedded in a structural unit derived from an unsaturated aliphatic hydrocarbon and having no ion conductive group. segment. 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.

As the unsaturated fat which can form the above polymer block (B) Examples of the aliphatic hydrocarbons include ethylene having 2 to 8 carbon atoms such as ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-heptene and 1-octene; a carbon naphthenic acid having 7 to 10 carbon atoms such as an alkane, ethylene cyclohexane, ethylene cycloheptane or ethylene cyclooctane; carbon of ethylene cyclopentene, ethylene cyclohexene, ethylene cycloheptene, ethylene cyclooctene or the like Number of 7 to 10 ethylene cyclic olefins; butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, a conjugated diene having a carbon number of 4 to 8 such as 2-ethyl-1,3-butadiene or 1,3-heptadiene; a carbon number of cyclopentadiene or 1,3-cyclohexadiene 5 to 8 conjugated cycloalkadiene, etc., and preferably ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc. a olefin having 2 to 8 carbon atoms; butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, a conjugated diene having 4 to 8 carbon atoms such as 2-ethyl-1,3-butadiene or 1,3-heptadiene, more preferably an olefin having 4 to 8 carbon atoms and a carbon number of 4 to 8. The conjugated diene is further preferably isobutylene, butadiene and isoprene, and particularly preferably dibutyl Alkene and isoprene. These unsaturated aliphatic hydrocarbons are polymerized as a single monomer or polymerized in two or more kinds to form a polymer block (B). The copolymerization form in which two or more kinds of unsaturated aliphatic hydrocarbons are used together is preferably a random copolymerization.

Further, the polymer block (B) is in the use temperature region, Insofar as the effect of the polymer block (B) imparting flexibility to the block copolymer (Z) is not impaired, other non-anhydrous aliphatic hydrocarbons may be contained. Structural unit. 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 these other monomers are mixed with the above-mentioned unsaturated aliphatic hydrocarbon and then polymerized. These other structural units are preferably 5 mol% or less of the structural unit forming the polymer block (B). That is, in the structural unit forming the polymer block (B), 95 mol% or more is preferably a structural unit derived from an unsaturated aliphatic hydrocarbon.

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

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

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

Mn per one polymer block (B), usually The range of 5,000 to 250,000 is better, the range of 7,000 to 200,000 is better, the range of 15,000 to 150,000 is particularly good, and the range of 30,000 to 100,000 is the best. When Mn is 5,000 or more, particularly 30,000 or more, the mechanical strength is particularly good, and the start-stop durability in which the wet (start) and dry (stop) are repeatedly performed in the fuel cell is excellent. When the Mn is 250,000 or less, particularly 100,000 or less, the block copolymer (Z) is excellent in moldability and is also advantageous in production.

<Other polymer blocks (C)>

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

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

(wherein R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R ⁵ represents an alkyl group having 3 to 8 carbon atoms; and R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkane having 3 to 8 carbon atoms; base.)

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

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

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

Mn per one polymer block (C), usually The range of 1,000 to 50,000 is better, the range of 1,500 to 30,000 is better, and the range of 2,000 to 20,000 is particularly good. When the Mn is 1,000 or more, the polymer electrolyte membrane obtained by the present invention tends to have excellent mechanical strength, and when it is 50,000 or less, the above-described composition containing the block copolymer (Z) and the compound (X) is used. It is excellent in formability and is also advantageous in terms of production.

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

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

<Manufacture of block copolymer (Z ₀ )>

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

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

As a specific example of the method for producing the block copolymer (Z ₀ ), a polymer block (A ₀ ) containing a structural unit derived from an aromatic vinyl compound and a structural unit derived from a conjugated diene are produced. The method in which the polymer block (B) is a block copolymer (Z ₀ ) of the component includes (1) using an anionic polymerization initiator in a cyclohexane solvent at a temperature of 20 to 100 ° C. Under the conditions, an aromatic vinyl compound, a conjugated diene, and an aromatic vinyl compound are successively anionized to obtain an ABA type block copolymer; (2) an anionic polymerization initiator is used in a cyclohexane solvent, a method in which an aromatic vinyl compound or a conjugated diene is subjected to anion polymerization successively at a temperature of 20 to 100 ° C, and then a coupling agent such as phenyl benzoate is added to obtain an ABA type block copolymer; (3) In the non-polar solvent, an organolithium compound is used as a starter, and an aromatic vinyl compound having a concentration of 5 to 50% by mass is carried out at a temperature of -30 to 30 ° C in the presence of a polar compound having a concentration of 0.1 to 10% by mass. Anionic polymerization and conjugated diene with the resulting work After the anionic polymerization of the polymer, an coupling agent such as phenyl benzoate is added 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 can be exemplified a compound; chlorosulfonic acid; a mixture of chlorosulfonic acid and trimethylchlorosilane; sulfur trioxide; a mixture of sulfur trioxide and triethyl phosphate; 2,4,6-trimethylbenzenesulfonic acid Representative of aromatic organic sulfonic acids and the like. 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 a compound represented by the following formula (1).

(wherein R ¹ represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms; and R ² represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms; and R ³ A hydroxyalkyl group having a carbon number of 1 to 4.

Examples of the hydroxyalkyl group having 1 to 4 carbon atoms include a methylol group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, and a 1-hydroxypropyl group. Hydroxy-1-methylethyl, 2-hydroxy-1-methylethyl, 1-hydroxybutyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, etc., and having a carbon number of 1 or The hydroxyalkyl group of 2 is preferably a hydroxymethyl group, a 1-hydroxyethyl group and a 2-hydroxyethyl group.

It is presumed that the compound (X) is selectively present in the hydrophilic polymer block because it has a hydroxyphenyl group and a hydroxyalkyl group having 1 to 4 carbon atoms, preferably a hydroxyalkyl group having 1 or 2 carbon atoms. Since the phase of (A) is considered to be selectively crosslinked by the hydrophilic polymer block (A), the flexibility of the polymer electrolyte membrane is impaired, and the hot water resistance is improved.

Specific examples of the compound (X) include 4-hydroxybenzyl alcohol, vanillyl alcohol, 3,4-dihydroxybenzyl alcohol, 2,6-di-t-butyl-4-hydroxycresol, and 2-(4). -hydroxyphenyl)ethanol, 2-(3,4-dihydroxyphenyl)ethanol, 4-hydroxy-3-methoxy-α-methylbenzyl alcohol, 3-(4-hydroxyphenyl)-1- Propanol, 1-(4-hydroxyphenyl)-2-propanol, 1-(4-hydroxyphenyl)-1-propanol, 2-(4-hydroxyphenyl)-2-propanol, 4- (4-Hydroxyphenyl)-1-butanol, 4-(4-hydroxyphenyl)-2-butanol, 3-(4-hydroxyphenyl)-2-methylpropanol, 3-(4- Hydroxyphenyl)-1-butanol, 1-(4-hydroxyphenyl)-2-methyl-2-propanol, 3-(4-hydroxyphenyl)-2-butanol, 2-(4- Hydroxyphenyl)-2-methyl-1-propanol and the like.

Among them, from the viewpoint of hot water resistance of the polymer electrolyte membrane, 4-hydroxybenzyl alcohol, vanillyl alcohol, 3,4-dihydroxybenzyl alcohol, 2,6-di-t-butyl-4-hydroxycresol, 2-( 3,4-dihydroxyphenyl)ethanol, 2-(4-hydroxyphenyl)ethanol, 4-hydroxyl Preferably, the benzyl-3-methoxy-α-methylbenzyl alcohol is vanillyl alcohol or 2-(4-hydroxyphenyl)ethanol.

The compound (X) may be used alone or in combination of two or more.

The content of the compound (X) in the composition is preferably in the range of 0.01 to 25 parts by mass based on 100 parts by mass of the block copolymer (Z), from the viewpoint of the hot water resistance of the polymer electrolyte membrane, 1~ The range of 10 parts by mass is better, and the range of 4 to 6 parts by mass is particularly good.

<Method for Producing Polymer Electrolyte Membrane>

Next, a method of producing the polymer electrolyte membrane of the present invention will be described. In general, a polymer electrolyte membrane is prepared by preparing a fluid composition containing a block copolymer (Z), a compound (X) and a solvent as a polymer electrolyte, and applying the fluid composition to a substrate or the like, and then removing the solvent. Further, a molded body comprising a composition containing the block copolymer (Z) and the compound (X) was obtained, and obtained by crosslinking the molded body.

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

The above fluid composition is in a solvent to make a block copolymer (Z) and the compound (X) are prepared by dissolving or dispersing. Further, various stabilizers, inorganic fillers, and photosensitizers such as a crosslinking agent, a softener, a phenolic stabilizer, a sulfur-based stabilizer, and a phosphorus stabilizer may be used in combination as long as the effects of the present invention are not impaired. Various additives such as antistatic agents, 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.

As a softener which can be used for the above fluid composition, Examples thereof 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, pentaerythritol-indole [3-(3,5-di-t-butyl-)- 4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-paran (3,5-di-t-butyl-4-hydroxybenzyl)benzene, octadecyl -3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 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) Phosphate stabilizer such as phosphate ester or distearyl pentaerythritol diphosphite. These may be used alone or in combination of two or more.

As inorganic filling that can be used for the above fluid composition Examples of the agent 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 The molecular weight, the composition, and the ion exchange group capacity are appropriately selected, but from the viewpoint of productivity, 5 to 20% by mass is preferable.

The above fluid composition, usually from polyterephthalic acid Coating is performed on a smooth substrate made of ethylene glycol (PET) or glass. As a coating method, the method of apply|coating using a coater, an applicator, etc. is mentioned.

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

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

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

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

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

When the crosslinking is carried out by heating, it is preferably 50 to 250 ° C, more preferably 60 to 200 ° C, more preferably 70 to 180 ° C, and most preferably 100 to 150 ° C. Further, as the heating time, 0.1 to 400 hours is preferable, 0.2 to 200 hours is more preferable, 0.4 to 100 hours is particularly preferable, and 0.5 to 30 hours is the best. 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.

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

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

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

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

Example

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

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

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

The ion exchange capacity was obtained by the following formula.

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

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

Mn was measured by the 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 3 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 3 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

Further, the sulfonation ratio of the sulfonated polyetheretherketone obtained in Production Example 4 was calculated from the results of ¹ H-NMR measurement under the following conditions.

Solvent: dimethyl hydrazine

Measuring temperature: 30 ° C

Cumulative number: 32 times

(Measurement of storage elastic modulus)

11.5% by mass of a toluene/isobutanol (mass ratio 65/35) solution of the block copolymer (Z-1) and the block copolymer (Z-2) obtained in Production Examples 1 and 2, respectively. The film was applied to a PET film (manufactured by Toyobo Co., Ltd., trade name: K1504) having a thickness of about 300 μm, and dried at 100 ° C for 4 minutes in a hot air dryer to obtain a molded body having a thickness of 20 μm.

Using a wide-area dynamic viscoelasticity measurement guide ("DVE-V4FT Rheospectler" manufactured by Rheology Co., Ltd.), the obtained molded body was pulled Stretching mode (frequency: 11 Hz), heating rate of 3 ° C / min, heating from -80 ° C to 250 ° C, measuring storage elastic modulus (E '), loss elastic modulus (E") and loss tangent (tan δ). There is no change in the storage elastic modulus of the polymerized olefin polymer at 80 to 100 ° C, and the amorphous state of the polymer block (B) is judged. The result is about the block copolymer (Z-1) and the incorporation. The segment copolymer (Z-2) and the polymer block (B) are amorphous.

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

After drying, 146 ml of dehydrated cyclohexane and 2.60 ml of second butyllithium (1.0 mol/L cyclohexane solution) were added to an autoclave having a nitrogen content of 1.4 L, and then stirred at 60 ° C. Polystyrene-b-polybutadiene-b-polystyrene was synthesized by sequentially adding 19.8 ml of styrene, 135 ml of butadiene, and 19.8 ml of styrene. The Mn of the obtained block copolymer was 76,000, the 1,4-bond amount of the polybutadiene block was 59.9%, and the content of the structural unit derived from styrene 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 15 hours under a hydrogen pressure of 0.5 to 1 MPa and 70 ° C using a Ni/Al-based Ziegler-type catalyst. Obtaining a block copolymer (Z ₀ ) comprising a polystyrene polymer block (polymer block (A ₀ )) and a hydrogenated polybutadiene polymer block (polymer block (B)) [polyphenylene] Ethylene-b-hydrogenated polybutadiene-b-polystyrene (hereinafter referred to as "block copolymer (Z ₀ -1)")].

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

(Manufacture of block copolymer (Z-1))

In 389 ml of dichloromethane, 195 ml of acetic anhydride and 87.0 ml of sulfuric acid were mixed at 0 ° C to prepare a sulfonating agent. On the other hand, 100 g of the block copolymer (Z ₀ -1) was placed in a glass reaction vessel having a capacity of 5 L of a stirrer, and the inside of the system was vacuumed, and the operation of introducing nitrogen was repeated three times, and then nitrogen was introduced. Into the state, 1000 ml of dichloromethane was added, and after stirring at normal temperature for 4 hours to dissolve, 610 ml of the above sulfonating agent was added dropwise over 5 minutes. After completion of the dropwise addition, the mixture was stirred at room temperature for 48 hours, and then 720 ml of distilled water was added dropwise with stirring to terminate the reaction, and the solid component was solidified and precipitated.

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) used in the polymer electrolyte membrane of the present invention (hereinafter referred to as It is "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 2.3 meq/g.

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

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, 4-tert-butyl group Polymerization of 14.4 ml of styrene, 28.6 ml of styrene and 14.4 ml of 4-tert-butylstyrene gave 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-butyl Styrene). 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, which originated 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 -2)")].

The hydrogenated polyisoprene block of the obtained block copolymer (Z ₀ -2) had a hydrogenation rate of 99% or more.

(Manufacture of block copolymer (Z-2))

After drying, 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 -2) was placed in a glass reaction vessel having a capacity of 5 L of a stirrer, and after replacing nitrogen in the system, 1600 ml of dichloromethane was added thereto, and the mixture was stirred at normal temperature for 4 hours. Dissolved. 486 ml of the previously prepared sulfonating agent was added dropwise to the solution over 5 minutes. After stirring at room temperature for 48 hours, 100 ml of distilled water was added to stop the reaction, and while stirring, 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-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 100 mol%, and the ion exchange capacity was 2.6 meq/g.

[Manufacturing Example 3] (Manufacture of sulfonated polyetheretherketone)

30 g of polyetheretherketone resin (PEEK, 450P manufactured by VICTREX Co., Ltd.) was substituted with nitrogen in a glass reaction vessel equipped with a stirrer, and then 550 g of concentrated sulfuric acid was added thereto, followed by stirring at room temperature to dissolve. After stirring at room temperature for 110 hours, the reactant was poured into ice-cold water to cause the polymer to coagulate and precipitate. The solid component was filtered, and the solid component was transferred to a beaker, and 2 L of distilled water was added thereto, and the mixture was washed with stirring, and then collected by filtration. This washing and filtering operation was repeated until the pH of the washing water did not change, and the finally filtered polymer was vacuum dried to obtain a sulfonated polyetheretherketone (hereinafter referred to as "SPEEK"). The sulfonation ratio of the monomer unit of the obtained SPEEK was 69% by ¹ H-NMR analysis, and the ion exchange capacity of the sulfonated polyetheretherketone was 2.0 meq/g.

[Example 1] (Production of polymer electrolyte membrane)

After preparing a 11.7% by mass toluene/isobutanol (mass ratio 65/35) solution of the block copolymer (Z-1) obtained in Production Example 1, vanillyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a compound. (X) A fluid composition was prepared by setting the mass ratio of the block copolymer (Z-1)/vanillin to 100/5. Then, the fluid composition was applied to a PET film (manufactured by Toyobo Co., Ltd., trade name: K1504) which was subjected to release treatment at a thickness of about 300 μm, and dried at 100 ° C for 4 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The obtained molded body was subjected to heat treatment in a thermostat at 140 ° C for 3 hours to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Embodiment 2] (Production of polymer electrolyte membrane)

After preparing a 11.5 mass% toluene/isobutanol (mass ratio 77/23) solution of the block copolymer (Z-2) obtained in Production Example 2, vanillyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added thereto. The mass ratio of the block copolymer (Z-2) / vanillyl alcohol was 100/5, and a fluid composition was prepared. Next, the fluid composition was applied to a PET film (Mitsubishi Resin, trade name: MRV) which had been subjected to release treatment at a thickness of about 300 μm, and dried at 100 ° C for 4 minutes in a hot air dryer. A molded body having a thickness of 20 μm. The obtained molded body was subjected to heat treatment in a thermostat at 140 ° C for 3 hours to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Example 3] (Production of polymer electrolyte membrane)

In addition to the addition of 2-(4-hydroxyphenyl)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) in place of vanillyl alcohol, the mass ratio of the block copolymer (Z-2)/2-(4-hydroxyphenyl)ethanol was In the same manner as in Example 2 except 100/5, a molded body having a thickness of 20 μm was obtained. The obtained molded body was subjected to heat treatment in a thermostat at 140 ° C for 1 hour to carry out crosslinking to prepare a polymer electrolyte membrane of the present invention.

[Example 4] (Production of polymer electrolyte membrane)

After preparing a 11.7% by mass toluene/isobutanol (mass ratio 65/35) solution of the block copolymer (Z-1) obtained in Production Example 1, vanillyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a compound. (X) A fluid composition was prepared by making the mass ratio of the block copolymer (Z-1) / vanillyl alcohol 100/5.

Then, the liquid composition was applied to a PET film (manufactured by Toyobo Co., Ltd., trade name: K1504) which was subjected to a release treatment to a thickness of about 150 μm, and then a non-woven fabric (KURARAY KURAFLEX Co., Ltd., Vecrus) was used. (registered trademark), an average fiber diameter of 7 μm, a basis weight of 3 g/cm ² , a porosity of 76.2%, and a thickness of 9 μm) without causing wrinkles to overlap with the coated surface from above, and impregnating the fluid composition with the nonwoven fabric Dry at 100 ° C for 4 minutes with a hot air dryer. The above flowable composition was further coated with a thickness of about 125 μm thereon, and dried at 100 ° C for 4 minutes in a hot air dryer to obtain a composition containing the block copolymer (Z-1) and the compound (X). The molded body composed of the molded body and the non-woven fabric had a thickness of 20 μm. The obtained joined body was heat-treated at 140 ° C for 3 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)

After preparing a 16% by mass toluene/isobutanol (mass ratio 70/30) solution of the block copolymer (Z-1) obtained in Production Example 1, 1,2-polybutadiene was added (Japan Soda Co., Ltd.) ), product name: PB-1000; Mn1,000, polymerization degree 19) 40% by mass toluene solution as a crosslinking agent to make the mass of block copolymer (Z-1) / 1,2-polybutadiene The ratio was 100/5, and a fluid composition was prepared. Then, the fluid composition was applied to a PET film (manufactured by Toyobo Co., Ltd., trade name: K1504) having a release treatment at a thickness of about 350 μm, and dried at 100 ° C for 4 minutes in a hot air dryer. A molded body having a thickness of 30 μm. The obtained molded body was subjected to an electron Curtain type electron beam irradiation apparatus (manufactured by Iwasaki Electric Co., Ltd., trade name: CB250/30/20 mA) by applying an accelerating voltage of 150 kV, a beam current of 8.6 mA, and a dose of 300 kGy. The electron beam irradiation was carried out by crosslinking, and the polymer electrolyte membrane of Comparative Example 1 was produced.

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

In addition to the addition of α,α'-dihydroxy-1,4-diisopropylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) to replace vanillyl alcohol, the block copolymer (Z-2) / α, α ' - two A molded body having a thickness of 20 μm was obtained in the same manner as in Example 2 except that the mass ratio of hydroxy-1,4-diisopropylphenylethanol was 100/7. The polymer electrolyte membrane of Comparative Example 2 was produced by heat-treating the obtained molded body in a thermostat at 140 ° C for 5 hours.

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

In addition to the addition of 1,3-diphenoxybenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) to replace vanillyl alcohol, the mass ratio of the block copolymer (Z-2) / 1,3-diphenoxybenzene was 100. In the same manner as in Example 2 except for /9.3, a molded body having a thickness of 20 μm was obtained. The polymer electrolyte membrane of Comparative Example 3 was produced by heat-treating the obtained molded body in a thermostat at 140 ° C for 1 hour.

[Comparative Example 4] (Production of polymer electrolyte membrane)

In addition to the addition of diethylene glycol (Wako Pure Chemical Industries, Ltd.) to replace vanillyl alcohol, the mass ratio of block copolymer (Z-2) / diethylene glycol is 100 / 4, and Example 2 In the same manner, a molded body having a thickness of 20 μm was obtained. The polymer electrolyte membrane of Comparative Example 4 was produced by heat-treating the obtained molded body in a thermostat at 140 ° C for 1 hour.

[Comparative Example 5] (Production of polymer electrolyte membrane)

After preparing a 5.3% by mass solution of dimethyl sulfoxide of SPEEK obtained in Production Example 3, 2-(4-hydroxyphenyl)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to make SPEEK/2-(4-hydroxyl A liquid composition was prepared by mass ratio of phenyl)ethanol to 100/7.2. Next, 166 mg of the fluid composition was poured into a container of polytetrafluoroethylene having a height of 3 cm in a square shape of 8 cm × 8 cm, dried at room temperature, and dried at 30 ° C by a vacuum dryer. After 72 hours, a molded body having a thickness of 20 μm was obtained. The polymer electrolyte membrane of Comparative Example 5 was produced by heat-treating the obtained molded body in a thermostat at 140 ° C for 24 hours.

(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)

A test piece of 3 cm × 5 cm was cut out from the polymer electrolyte membranes obtained in Examples 1 to 4 and Comparative Examples 1 to 5, and dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₁ ) was measured, and then added. After adding 60 mL of distilled water to a solenoid of 110 mL, it was stored in a metal container made of SUS, sealed, and left to stand in a thermostatic chamber at 110 ° C for 96 hours. Next, the state of the surface of the test piece in the screw tube (visual test) 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 residual ratio of the insoluble matter was determined by the following formula.

Insoluble matter residual rate (a) (%) = 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 (b) was calculated|required.

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

(Measurement of crosslink density and gel fraction)

A test piece of 3 cm × 5 cm was cut out from the polymer electrolyte membranes obtained in Examples 1 to 4 and Comparative Examples 1 to 5, and dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₃ ) was measured, followed by dipping. After 30 ml of the solvent was used for 3 hours, the film was taken out, and the mass of the film (measured as mass m ₄ ) was measured in a state containing a solvent. Thereafter, the mixture was dried at 1.3 kPa and 50 ° C for 12 hours, and the mass (measured as mass m ₅ ) was measured.

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

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

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

Gel fraction = m ₅ /m ₃ × 100 (%)

Further, since the polymer electrolyte membrane which is not crosslinked needs to select a solvent which exhibits good solubility as the solvent, toluene/isobutanol (mass ratio 70) is used for Examples 1 to 4 and Comparative Examples 1 to 4. /30) A mixed solvent was used, and in Comparative Example 5, dimethyl hydrazine was used.

(tensile fracture test)

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

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

(the voltage drop rate of the fuel cell)

For the purpose of evaluating the influence on the fuel cell performance of the obtained polymer electrolyte membrane, the voltage drop rate at a high temperature was measured using the fuel cell for evaluation incorporating the polymer electrolyte membrane.

First, the obtained polymer electrolyte membrane was cut into a size of 9 cm × 9 cm, and the PET film UTS-20BAF (manufactured by Nitto Denko Co., Ltd. (trade name)) having a thickness of 5 cm × 5 cm of 9 cm × 5 cm was cut into two pieces.

Then, two pieces of a re-peeling film CT100 (manufactured by PANAC (trade name)) of 5.3 cm × 5.3 cm, which were cut inside, were cut into two pieces, and then contained in two sheets of 5.3 cm × 5.3 cm. A PTFE sheet (manufactured by Johnson Matthey Co., Ltd.) with a catalyst layer carrying carbon on a Pt catalyst, which is sandwiched between the catalyst layer and the polymer electrolyte membrane, and a re-peeling film CT100 (PANAC) of 9 cm × 9 cm. (share) system (product name)) clamped. Subsequently, the film was sandwiched between two sheets of a PTFE sheet having a thickness of 100 μm, and then sandwiched between two mirror plates, and heat-treated (150 ° C, 40 kg/cm ² , 10 minutes) by hot pressing to transfer the catalyst layer to a high temperature. A membrane-electrode assembly (MEA) was produced by a molecular electrolyte membrane. Next, the obtained MEA was sandwiched between two sheets of a thickness of 200 μm, which was cut into a width of 5.3 cm × 5.3 cm, and a thickness of 200 μm, and a GDL (with a MPL of 5.3 cm × 5.3 cm) was attached. Two sheets of JNT20-A1 and Sato Light Industrial (manufactured by Sato Light Industrial Co., Ltd.) are sandwiched between two surfaces of the MPL and the catalyst layer, and are sandwiched by two conductive separators that function as a gas supply flow path. Further, the outer side was sandwiched between two clamping plates to prepare an evaluation battery.

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

Hydrogen was supplied at 261 cc/min on one electrode (anode) of the evaluation fuel cell, and air was supplied at 878 cc/min on the other electrode (cathode), and was operated under the following conditions. The relationship between the operation time and the voltage is shown in Fig. 1.

Battery temperature: 80 ° C

Relative humidity: 80%

Current density: 1.0A/cm ²

Using the connection to the operation of the evaluation by the voltage detection of the fuel cell terminals, the measurement operation voltage value after the 50 hours V ₁ (V), the voltage value of the operation 84 hours V ₂ (V), using the following equation voltage drop speed.

Voltage drop speed (mV/hour) = {(V ₁ - V ₂ ) / (84-50)} × 10 ³

As shown in Table 1, the polymer electrolyte membrane of the present invention is excellent in hot water resistance.

Since the polymer electrolyte membrane of Comparative Examples 1 to 4 is a polymer electrolyte membrane containing a compound other than the compound (X), the hot water resistance is inferior to that of the polymer electrolyte membrane of the present invention.

In the polymer electrolyte membrane of Comparative Example 5, since a polymer electrolyte other than the block copolymer (Z) was used, crosslinking could not be performed.

According to the first embodiment, it is understood that the polymer electrolyte membrane of the present invention has a small decrease in voltage when it is assembled into a fuel cell and is operated. It is presumed that this is based on the excellent hot water resistance of the polymer electrolyte membrane of the present invention.

Industrial availability

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

Claims (7)

A polymer electrolyte membrane obtained by subjecting a composition comprising a block copolymer (Z) and a compound (X) to cross-linking after molding, the block copolymer (Z) comprising: a polymer block (A) having a structural unit of a vinyl compound and having an ion conductive group, and an amorphous polymer block (B) containing a structural unit derived from an unsaturated aliphatic hydrocarbon and having no ion conductive group This compound (X) is represented by the following formula (1): In the formula, R ¹ represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms, and R ² represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and R ³ represents A hydroxyalkyl group having 1 to 4 carbon atoms. The polymer electrolyte membrane of claim 1, wherein the unsaturated aliphatic hydrocarbon is a conjugated diene having 4 to 8 carbon atoms. The polymer electrolyte membrane according to claim 1 or 2, wherein the ion conductive group is selected from the group consisting of a sulfonic acid group represented by -SO ₃ M or PO ₃ HM, a phosphonic acid group, and one or more of the salts; In the formula, M represents a hydrogen atom, an ammonium ion or an alkali metal ion. The polymer electrolyte membrane according to any one of claims 1 to 3, wherein R ³ in the formula (1) is a methylol group, a 1-hydroxyethyl group or a 2-hydroxyethyl group. The polymer electrolyte membrane according to any one of claims 1 to 4, wherein the content of the compound (X) in the composition is 0.01 with respect to 100 parts by mass of 100 parts by mass of the block copolymer (Z). ~25 parts by mass. The polymer electrolyte membrane according to any one of claims 1 to 5, wherein the block copolymer (Z) further comprises: a polymer block comprising a structural unit derived from an aromatic vinyl compound and having no ion conductive group (C). A polymer electrolyte fuel cell having the polymer electrolyte membrane according to any one of claims 1 to 6.