阅读说明：本技术 层叠电解质膜、膜电极复合体、水电解式氢产生装置、以及层叠电解质膜的制造方法 (Laminated electrolyte membrane, membrane electrode assembly, water electrolysis type hydrogen generator, and method for producing laminated electrolyte membrane ) 是由 南林健太 尾形大辅 白井秀典 出原大辅 于 2020-03-19 设计创作，主要内容包括：本发明以防止带催化剂层的电解质膜中可见的由电解质膜与接合性促进层的接合性的不充分引起的电压上升、及烃系高分子电解质膜的氧化劣化为课题,提供一种在包含烃系高分子电解质的第一层的至少单面层叠有包含氟系高分子电解质及聚偏二氟乙烯的第二层,并在第一层与第二层的界面附近具有混合区域的层叠电解质膜。(The present invention provides a laminated electrolyte membrane in which a second layer comprising a fluorine-based polymer electrolyte and polyvinylidene fluoride is laminated on at least one surface of a first layer comprising a hydrocarbon-based polymer electrolyte, and a mixed region is provided in the vicinity of the interface between the first layer and the second layer, in order to prevent a voltage rise and oxidation degradation of the hydrocarbon-based polymer electrolyte membrane, which are caused by insufficient bondability between the electrolyte membrane and a bondability-promoting layer, which are observed in an electrolyte membrane with a catalyst layer.)

1. A laminated electrolyte membrane comprising a first layer mainly composed of a hydrocarbon polymer electrolyte and a second layer mainly composed of a fluorine polymer electrolyte and polyvinylidene fluoride laminated on at least one surface of the first layer, wherein the first layer and the second layer are laminated via a region in which two constituent components are present in a mixed state, and the region is hereinafter referred to as a mixed region.

2. The laminated electrolyte membrane according to claim 1, wherein a third layer containing a fluorine-based polymer electrolyte as a main component is laminated on a surface of the second layer opposite to the first layer.

3. The laminated electrolyte membrane according to claim 1 or 2, wherein at least one of the first layer, the second layer, and the third layer comprises platinum.

4. A laminated electrolyte membrane as claimed in any one of claims 1 to 3, wherein the thickness of the mixed region is 0.2 μm or more.

5. The laminated electrolyte membrane according to any one of claims 1 to 4, wherein the content of polyvinylidene fluoride contained in the second layer is 20 to 90% by mass, assuming that the total mass of the fluorine-based polymer electrolyte and polyvinylidene fluoride is 100% by mass.

6. A laminated electrolyte membrane as claimed in any one of claims 1 to 5, wherein the weight average molecular weight of the polyvinylidene fluoride is 30 ten thousand or more.

7. A laminated electrolyte membrane as claimed in any one of claims 1 to 6, wherein the thickness of the second layer is 40% or less of the thickness of the first layer.

8. A laminated electrolyte membrane as claimed in any one of claims 1 to 7, wherein the peeling force of the first layer and the second layer is 0.3N or more.

9. The laminated electrolyte membrane according to any one of claims 1 to 8, wherein the hydrocarbon-based polymer electrolyte contains a polyether ketone polymer having an ionic group as a main component.

10. A laminated electrolyte membrane with a catalyst layer, comprising an anode catalyst layer on one surface of the laminated electrolyte membrane according to any one of claims 1 to 9 and a cathode catalyst layer on the opposite surface.

11. A laminated electrolyte membrane with catalyst layers according to claim 10, wherein a second layer is laminated between the first layer and the anode catalyst layer.

12. A membrane-electrode assembly comprising a laminated electrolyte membrane with a catalyst layer according to claim 10 or 11, an anode power supply body laminated on the anode catalyst layer, and a cathode power supply body laminated on the cathode catalyst layer.

13. The membrane electrode assembly according to claim 12, wherein the anode power supply is composed of an inorganic conductive substance.

14. A water electrolysis type hydrogen generator produced by using the laminated electrolyte membrane according to any one of claims 1 to 9.

15. A water electrolysis type hydrogen generator produced by using the laminated electrolyte membrane with a catalyst layer according to claim 10 or 11.

16. A water electrolysis type hydrogen generator produced by using the membrane electrode assembly according to claim 12 or 13.

17. A method for producing a laminated electrolyte membrane, comprising the steps of a and b,

step a: a step of forming a first layer containing a hydrocarbon-based polymer electrolyte,

step b: and a step of forming a second layer by applying a solution A in which a fluorine-based polymer electrolyte and polyvinylidene fluoride are dissolved in an aprotic polar solvent to the first layer.

Technical Field

The present invention relates to an electrolyte membrane used in a water electrolysis apparatus or a fuel cell.

Background

Fuel cells are power generation devices that extract electrical energy by electrochemically oxidizing a fuel such as hydrogen gas, and have recently attracted attention as clean energy sources. Among fuel cells, Polymer Electrolyte Membrane (PEM) type fuel cells are expected to be widely used as relatively small-scale distributed power generation facilities and power generation devices for mobile bodies such as automobiles and ships because of their low standard operating temperature, about 100 ℃, and high energy density. In addition, since the battery also attracts attention as a power source for small-sized mobile devices and mobile devices, it is expected to be mounted on mobile phones, personal computers, and the like, instead of secondary batteries such as nickel hydride batteries and lithium ion batteries.

There are various methods for producing hydrogen gas used as fuel for fuel cells, and if electrolysis of water is performed using surplus power generated from renewable energy, the hydrogen gas can be converted into hydrogen energy without discharging carbon dioxide. Methods for producing hydrogen gas by electrolysis of water include alkaline water electrolysis and Polymer Electrolyte Membrane (PEM) type water electrolysis, but PEM type water electrolysis has a feature of being capable of operating at a high current density and flexibly coping with output fluctuations of renewable energy.

The principle of PEM-type water electrolysis is shown below.

1. The water supplied to the anode is oxidized by applying a voltage, and oxygen, protons, and electrons are generated.

2. The protons are conducted to the cathode via the ion exchange groups in the electrolyte membrane.

3. The electrons are conducted from the anode to the cathode by an external circuit by applying a voltage.

4. The protons combine with the electrons at the cathode to produce hydrogen gas.

As such a polymer electrolyte membrane used in a PEM-type water electrolysis apparatus, there has been reported an example using a membrane using a fluorine-based polymer electrolyte membrane represented by "Nafion (registered trademark)" manufactured by DuPont, u.s.a. However, the fluorine-based polymer electrolyte membrane has a large hydrogen permeation and is insufficient in hydrogen gas barrier property. Therefore, the water electrolysis apparatus has safety problems of a decrease in current efficiency and mixing of hydrogen and oxygen due to permeation of generated hydrogen from the cathode to the anode. Further, since the fluorine-based polymer electrolyte membrane is a rubber-based material having low breaking strength, there is a problem that the membrane is easily deformed. Further, when the electrolyte membrane is thickened in order to solve the problem, there is a problem that the electrolytic efficiency of the water electrolysis apparatus decreases as the proton conductivity decreases.

In order to solve such problems, it has been proposed to use a hydrocarbon polymer electrolyte membrane instead of a fluorine polymer electrolyte membrane (for example, patent document 1). The hydrocarbon polymer electrolyte membrane has excellent hydrogen barrier properties even when it is a thin film, and has high breaking strength, so that deformation can be suppressed.

One of the problems in the application of hydrocarbon polymer electrolyte membranes is the bondability of the electrolyte membrane to the catalyst layer. Patent document 2 proposes an electrolyte membrane with a catalyst layer in which a bonding promoting layer containing a fluorine-based polymer electrolyte and graphitized carbon particles is disposed between the electrolyte membrane and the catalyst layer, thereby improving the bonding between the two.

[ Prior art documents ]

Patent document

Patent document 1: japanese patent laid-open No. 2016-

Patent document 2: japanese patent laid-open publication No. 2008-512884

Disclosure of Invention

Problems to be solved by the invention

However, it has been found that an electrolyte membrane with a catalyst layer using a hydrocarbon polymer electrolyte membrane has the following two problems. The problem is the following two points.

1) The electrolyte membrane has insufficient adhesion to the adhesion promoting layer, and peeling causes a voltage rise.

2) The catalyst layer is in electrical contact with the hydrocarbon polymer electrolyte membrane, and when the electrode is at a high potential as in a water electrolysis apparatus, the hydrocarbon polymer electrolyte membrane is oxidized and deteriorated.

Means for solving the problems

The present invention for solving the above problems is an electrolyte membrane in which a second layer containing a fluorine-based polymer electrolyte and polyvinylidene fluoride as main components is laminated on at least one surface of a first layer containing a hydrocarbon-based polymer electrolyte as a main component, and the first layer and the second layer are laminated via a region in which components constituting both layers are present in a mixed state (hereinafter, the region is referred to as a mixed region).

Effects of the invention

In the electrolyte membrane of the present invention, good bondability can be achieved for the first layer and the second layer, and for the catalyst layer and the second layer, respectively. Further, the hydrocarbon-based polymer electrolyte layer as the first layer can be prevented from coming into contact with the electrode on the high potential side, thereby preventing oxidative deterioration.

Drawings

Fig. 1 is a cross-sectional photograph of a mixed region of a laminated electrolyte membrane according to an embodiment of the present invention, which is taken in an enlarged manner.

Detailed Description

The laminated electrolyte membrane of the present invention will be described in detail below.

[ Hydrocarbon-based polyelectrolyte ]

The hydrocarbon-based polyelectrolyte is a hydrocarbon-based polymer having an ionic group. The hydrocarbon polymer having an ionic group means a polymer having a main chain comprising a hydrocarbon as a main constituent unit and having an ionic group imparted to the main chain or a side chain, and the main chain and the side chain are substantially not fluorinated. The term "substantially non-fluorinated" means that a polymer having a fluorinated moiety in a very small portion of the main chain or side chain thereof is not excluded, and specifically refers to a hydrocarbon polymer having an ionic group, including a polymer having a fluorine atom content of less than 5% per number average molecular weight of the polymer.

The hydrocarbon polymer constituting the hydrocarbon polyelectrolyte is preferably an aromatic hydrocarbon polymer in particular. The aromatic hydrocarbon-based polymer is a polymer having a hydrocarbon skeleton having an aromatic ring in the main chain, and specific examples thereof include polymers having an aromatic ring in the main chain and having a structure selected from polysulfone, polyethersulfone, polyphenylene ether, polyarylether-based polymer, polyphenylene sulfide sulfone, polyphenylene oxide, polyarylene-based polymer, polyarylene ketone, polyether ketone, polyarylene phosphine oxide, polyether phosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide and polyimide sulfone. In addition, the polysulfone, polyethersulfone, polyetherketone, etc. mentioned herein are generic terms of structures having sulfone bond, ether bond, ketone bond in their molecular chains, and include polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone, polyetherketoneetherketoneketone, polyetherketonesulfone, etc. The hydrocarbon framework may have a plurality of these structures. Among these, a polyether ketone polymer, which is a polymer having a polyether ketone structure in the main chain, is particularly preferable as the main component. Here, the term "main component" means that the mass of the ether ketone moiety considered as a repeating unit is 50 mass% or more, assuming that the mass of the entire polymer is 100 mass%.

The ionic group of the hydrocarbon polymer electrolyte used in the present invention may be an ionic group having proton exchange ability. As such an ionic group, a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, and a carboxylic acid group can be preferably used. The ionic group may be contained in the polymer in 2 or more species. Among them, the polymer more preferably has at least a sulfonic acid group, a sulfonimide group, and a sulfuric acid group in terms of high proton conductivity, and most preferably has a sulfonic acid group in terms of raw material cost.

[ fluorine-based polyelectrolyte ]

The fluorine-based polyelectrolyte refers to a polymer having a main chain comprising perfluorocarbon as a main constituent unit, and having an ionic group imparted to the main chain or a side chain thereof. Examples of the fluorine-based polymer electrolyte include perfluorocarbon polymers (which may contain etheric oxygen atoms) having sulfonic acid groups. Among these, a copolymer having a repeating unit based on tetrafluoroethylene and a repeating unit of a perfluorocarbon having a sulfonic acid group is preferable. Commercially available products of such copolymers include: resins based on perfluorocarbon sulfonic acid polymers, polytrifluoroethylene sulfonic acid polymers, perfluorocarbon sulfonic acid polymers, trifluorostyrene sulfonic acid polymers, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymers, ethylene-tetrafluoroethylene copolymers, polyvinylidene fluoride-perfluorocarbon sulfonic acid polymers, ethylene-tetrafluoroethylene copolymers, trifluorostyrene copolymers, and trifluorostyrene, such as Nafion (registered trademark: manufactured by DuPont) and Aquivion (registered trademark: manufactured by Solvay). From the viewpoint of power generation performance such as heat resistance and chemical stability, a fluorine-based polymer electrolyte composed of a perfluorocarbon sulfonic acid-based polymer is particularly preferable.

[ platinum ]

The laminated electrolyte membrane of the present invention preferably contains platinum. Platinum may be used by reducing platinum or a platinum precursor compound. AsPlatinum precursor, for example, H₂Pt(OH)₆、PtO₂·nH₂O, and the like. In the case of using a platinum precursor, it can be easily reduced to platinum by using a reducing agent in a solution containing the platinum precursor. As the reducing agent for the platinum precursor, hydrogen, hydrazine, formaldehyde, formic acid or oxalic acid, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, a mixture of these, and the like can be used.

The particle size of platinum used in the laminated electrolyte membrane is not particularly limited, but platinum having a small particle size is preferably used in order to reduce the thickness of the hydrogen permeation preventing layer. The particle diameter of platinum is preferably 1 μm or less, more preferably 100nm or less, and further preferably 20nm or less.

Further, platinum may be contained in any one of a first layer, a second layer, and a third layer described below, but is preferably contained in the second layer or the third layer.

[ polyvinylidene fluoride ]

By polyvinylidene fluoride, copolymers of vinylidene fluoride with other copolymerizable monomers are included within the meaning of polyvinylidene fluoride mentioned in the present invention, in addition to homopolymers of vinylidene fluoride (i.e., pure polyvinylidene fluoride). As the monomer copolymerizable with vinylidene fluoride, for example, one or two or more of tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, trichloroethylene, vinyl fluoride and the like can be used. Such polyvinylidene fluoride can be obtained by emulsion polymerization or suspension polymerization.

When the polyvinylidene fluoride used as the second layer has a large molecular weight, the polyvinylidene fluoride in the mixed region is strongly entangled with the molecular chains of the hydrocarbon polymer electrolyte and the fluorine polymer electrolyte, and the adhesiveness is improved. Therefore, the weight average molecular weight of polyvinylidene fluoride is preferably 30 ten thousand or more, and more preferably 50 ten thousand or more.

[ first layer ]

The laminated electrolyte of the present invention has a layer (first layer) containing a hydrocarbon-based polymer electrolyte as a main component. The hydrocarbon-based polymer electrolyte forming this layer is as described above. Here, the main component means that 50 mass% or more of all components contained in a unit volume in a portion of the first layer other than the mixed region described later is a hydrocarbon-based polymer electrolyte, and preferably 70 mass% or more, more preferably 80 mass% or more, and particularly preferably substantially consists of a hydrocarbon-based polymer electrolyte. Here, "substantially" means that a small amount, specifically less than 1 mass%, of other components is allowed to be contained, and typically means that no other components are contained.

[ second layer ]

The laminated electrolyte membrane of the present invention has a layer (second layer) containing a fluorine-based polymer electrolyte and polyvinylidene fluoride as main components on at least one surface of the first layer. Here, the main component means that 50 mass% or more of all components contained in a unit volume in a portion of the second layer other than the mixed region described later is composed of the fluorine-based polymer electrolyte and the polyvinylidene fluoride, and preferably 70 mass% or more, more preferably 80 mass% or more, and particularly preferably substantially composed of the fluorine-based polymer electrolyte and the polyvinylidene fluoride. Here, "substantially" means that a small amount, specifically less than 1 mass%, of other components is allowed to be contained, and typically means that no other components are contained.

When the content of the fluorine-based polyelectrolyte in the second layer is small, the membrane resistance becomes large. Therefore, when the total mass of the fluorine-based polymer electrolyte and the polyvinylidene fluoride is 100 mass%, the fluorine-based polymer electrolyte is preferably 20 mass% or more, more preferably 60 mass% or more, and further preferably 70 mass% or more. When the content of the fluorine-based polymer electrolyte is increased and the content of the polyvinylidene fluoride is decreased, the adhesiveness to the first layer is decreased. Therefore, when the total mass of the fluorine-based polymer electrolyte and the polyvinylidene fluoride is 100 mass%, the fluorine-based polymer electrolyte is preferably 90 mass% or less, more preferably 80 mass% or less. By setting the range, the adhesiveness and the ion conductivity are compatible, and the effect of the compatibility of the efficiency and the durability is obtained. The weight ratio of the fluorine-based polymer electrolyte to the polyvinylidene fluoride was determined in the portion of the second layer other than the mixed region described later.

The present invention can realize high hydrogen barrier properties and mechanical strength by using the first layer containing a hydrocarbon polymer electrolyte as a main electrolyte layer. Therefore, the thickness of the second layer is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less of the thickness of the first layer. When the film thickness of the second layer is reduced, the mixed region becomes thin, and the adhesiveness between the first layer and the second layer is reduced. Therefore, the thickness of the second layer is preferably 1% or more, and more preferably 5% or more, with respect to the thickness of the first layer. The measurement and determination of the thickness of the first layer and the second layer are as described in example 1 (4) below.

[ third layer ]

The laminated electrolyte membrane of the present invention may have a layer (third layer) containing a fluorine-based polymer electrolyte as a main component laminated on the surface of the second layer opposite to the surface on which the first layer is laminated.

The third layer does not contain a hydrocarbon polymer electrolyte. Here, the main component means that 60 mass% or more of all components contained in the third layer per unit volume is a fluorine-based polymer electrolyte, and preferably 70 mass% or more, more preferably 80 mass% or more, and particularly preferably substantially consists of a fluorine-based polymer electrolyte. Here, "substantially" means that a small amount, specifically less than 1 mass%, of other components (excluding the hydrocarbon-based polymer electrolyte) are allowed to be contained, and typically means that no other components are contained.

The present invention achieves higher hydrogen barrier properties and mechanical strength when the first layer containing a hydrocarbon-based polymer electrolyte is used as the main electrolyte layer. Therefore, the thickness of the third layer is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less of the thickness of the first layer. The lower limit is preferably 0.1% or more with respect to the thickness of the first layer.

[ method for producing laminated electrolyte Membrane ]

The laminated electrolyte membrane of the present invention can be manufactured by the steps shown below.

First, as a first step, a first layer containing a hydrocarbon-based polymer electrolyte as a main component is formed.

As an example of the method for forming the first layer, the first layer can be formed by sequentially performing a step of forming a layer in a state where an ionic group contained in the hydrocarbon polymer electrolyte and a cation of an alkali metal or an alkaline earth metal form a salt, and a step of exchanging a cation of an alkali metal or an alkaline earth metal, which forms a salt with an ionic group, with a proton. This forming method will be described in more detail below. In the present specification, a polymer electrolyte in which an ionic group and a cation of an alkali metal or an alkaline earth metal form a salt is hereinafter referred to as a "salt-type polymer electrolyte".

The method for forming the first layer includes a step of forming a layer using a salt-type polyelectrolyte, and then exchanging cations of an alkali metal or an alkaline earth metal, which has formed a salt with an ionic group, with protons. The step of exchanging the cations with the protons is preferably a step of bringing a salt-type polyelectrolyte into contact with an acidic aqueous solution. Moreover, the contacting is more preferably a step of immersing the first layer in an acidic aqueous solution. In this step, the proton in the acidic aqueous solution is replaced with a cation ionically bonded to the ionic group, and the remaining water-soluble impurities, or the remaining monomer, solvent, residual salt, and the like are simultaneously removed. The acidic aqueous solution to be used is not particularly limited, but preferably a protonic acid such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid, trifluoromethanesulfonic acid, methanesulfonic acid, phosphoric acid, or citric acid is used. The temperature, concentration, and the like of the acidic aqueous solution are also appropriately determined, but from the viewpoint of productivity, it is preferable to use an aqueous solution of sulfuric acid of 3 mass% or more and 30 mass% or less at a temperature of 0 ℃ or more and 80 ℃ or less.

The solvent used in forming the first layer may be appropriately selected depending on the polymer species. As the solvent, for example, aprotic polar solvents such as N, N-dimethylacetamide, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1, 3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, and the like, ester solvents such as γ -butyrolactone, ethyl acetate, butyl acetate, and the like, carbonate solvents such as ethylene carbonate, propylene carbonate, and the like, and alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like can be preferably used. Further, a mixed solvent obtained by mixing two or more of these solvents may be used.

Further, for the purpose of viscosity adjustment, various low boiling point solvents such as alcohol solvents such as methanol, ethanol, 1-propanol, and isopropanol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate, butyl acetate, and ethyl lactate, hydrocarbon solvents such as hexane and cyclohexane, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, halogenated hydrocarbon solvents such as chloroform, dichloromethane, 1, 2-dichloroethane, perchloroethylene, chlorobenzene, dichlorobenzene, and hexafluoroisopropanol, ether solvents such as diethyl ether, tetrahydrofuran, and 1, 4-dioxane, nitrile solvents such as acetonitrile, nitrated hydrocarbon solvents such as nitromethane and nitroethane, and various low boiling point solvents such as water may be mixed in the solvent.

In addition, as an example of a method for forming the second layer, a method for forming an electrolyte layer containing a fluorine-based polymer electrolyte and polyvinylidene fluoride as main components on the formed first layer can be cited. When the membrane-forming solvent remains in the laminated electrolyte membrane even after drying, it is preferable to wash the laminated electrolyte membrane with pure water.

The solvent used for forming the second layer is preferably a solvent having a high affinity for the components of the first layer, from the viewpoint of forming a mixed region in the vicinity of the interface between the first layer and the second layer and improving the bondability. Therefore, it is preferable to use an aprotic polar solvent, and it is more preferable to use a solvent used for film formation of the first layer.

The peeling force between the first layer and the second layer of the laminated electrolyte membrane of the present invention is preferably 0.3N or more, more preferably 1.0N or more, and particularly preferably 2.0N or more. The upper limit is not particularly limited, but is generally 10.0N or less. The greater the peeling force is, the more the peeling between the first layer and the second layer is suppressed, and the performance degradation during the operation of the apparatus can be prevented.

[ mixing region ]

In the laminated electrolyte membrane of the present invention, the first layer and the second layer are laminated via a region (mixed region) in which components constituting both layers are present in a mixed state.

The mixed region is a region in which a length (for convenience, also referred to as "thickness") in the thickness direction, which is observed by the method described in the later-described item 1.(4) of example, is 0.1 μm or more, and in which at least one selected from the group consisting of a hydrocarbon polymer electrolyte and a polyvinylidene fluoride and a fluorine polymer electrolyte is observed, is sandwiched between a layer composed of only a component constituting the first layer and a layer composed of only a component constituting the second layer, as shown in fig. 1. The thicker the mixed region is, the higher the bonding strength between the first layer and the second layer is, and therefore the thickness is preferably 0.2 μm or more, more preferably 0.5 μm or more, and further preferably 1.0 μm or more. On the other hand, if the mixed region becomes too thick and the hydrocarbon-based polymer electrolyte is exposed at the surface layer of the laminated electrolyte membrane, the hydrocarbon-based polymer electrolyte in contact with the electrode may be oxidized and deteriorated when used as an electrolyte membrane. Therefore, the thickness of the mixed region is preferably such that the hydrocarbon-based polymer electrolyte is not exposed to the surface layer, and is 80% or less of the total thickness of the first layer and the second layer.

The concentration of the polyelectrolyte solution to be used is preferably 3 to 40% by mass, more preferably 5 to 30% by mass. If the solution viscosity is too low, the retention of the solution is poor, and a liquid flow is generated. On the other hand, when the solution viscosity is too high, the surface smoothness of the electrolyte membrane may be deteriorated.

As a method of forming the first layer and the second layer by the casting coating, a method such as knife coating, direct roll coating (direct roll coat), Meyer bar coating (Meyer bar coat), gravure coating, reverse coating, air knife coating, spray coating, brush coating, dip coating, die coating, vacuum die coating (vacuum die coat), curtain coating, flow coating, spin coating, screen printing, and inkjet coating can be used.

For drying the solvent, known methods such as heating of the substrate, hot air, and infrared heater can be selected as the method of drying. The drying temperature is preferably 200 ℃ or less, more preferably 130 ℃ or less, in view of decomposition of the polymer electrolyte.

Additives such as a crosslinking agent, a crystallization nucleating agent, a plasticizer, a stabilizer, a release agent, an antioxidant, a radical-supplementing agent, and inorganic fine particles, which are generally used in polymer compounds, may be added to the laminated electrolyte membrane in a range not departing from the object of the present invention for the purpose of improving mechanical strength, improving thermal stability of ionic groups, improving water resistance, solvent resistance, improving radical resistance, improving coatability of coating solutions, improving storage stability, and the like.

The laminated electrolyte membrane of the present invention can be applied to various uses. For example, the film can be applied to medical applications such as artificial skin, filtration applications, applications of ion exchange resins such as chlorine-resistant reverse osmosis membranes, applications of various structural materials, electrochemical applications, humidification films, antifogging films, antistatic films, deoxygenation films, films for solar cells, and gas barrier films. Among them, can be preferably used for various electrochemical applications. Examples of electrochemical applications include solid polymer fuel cells, redox flow cells, electrochemical hydrogen pumps, hydrogen purifiers, water electrolyzers, and chlor-alkali electrolyzers, and particularly, the electrochemical application is suitably used for water electrolyzers.

< electrolyte membrane with catalyst layer, membrane-electrode assembly, electrochemical hydrogen pump, and water electrolysis hydrogen generator

The battery used in the water electrolysis apparatus has a structure in which a catalyst layer, an electrode substrate, and a separator are sequentially laminated on both surfaces of the composite electrolyte membrane of the present invention. Among them, an electrolyte Membrane having a Catalyst layer laminated on both surfaces of an electrolyte Membrane (i.e., a layer structure of Catalyst layer/electrolyte Membrane/Catalyst layer) is called a Catalyst Coated Membrane (CCM), and an electrolyte Membrane having a Catalyst layer and a gas diffusion substrate laminated in this order on both surfaces of an electrolyte Membrane (i.e., a layer structure of gas diffusion substrate/Catalyst layer/electrolyte Membrane/Catalyst layer/gas diffusion substrate) is called a Membrane Electrode Assembly (MEA).

As a method for producing CCM, a coating method in which a catalyst layer paste composition for forming a catalyst layer is applied to the surface of an electrolyte membrane and dried, or a method (transfer method) in which only a catalyst layer is formed on a substrate and the catalyst layer is transferred to laminate the catalyst layer on the electrolyte membrane is generally performed.

Here, the catalyst layer on the anode side is referred to as an anode catalyst layer, and the catalyst layer on the cathode side is referred to as a cathode catalyst layer. In the present invention, it is preferable that the second layer is disposed between the first layer and the anode catalyst layer. By adopting such a configuration, direct contact between the first layer and the anode catalyst layer is prevented, whereby oxidative deterioration of the components constituting the first layer can be suppressed, and deterioration of performance when used in a device such as a fuel cell or a water electrolysis type hydrogen generator can be prevented.

In the case of MEA by pressing (press), a known method (for example, Electrochemical, electroless plating method described in 1985, 53, page 269, eds. (j. electrochem. soc.), Electrochemical Science and Technology (Electrochemical Science and Technology), hot press bonding method of gas diffusion electrodes described in 1988, 135, 9, page 2209, and the like) can be applied. The temperature or pressure at the time of pressing may be appropriately selected depending on the thickness of the electrolyte membrane, the water content, the catalyst layer, or the electrode substrate. In the present invention, the electrolyte membrane can be combined by pressing even in a dry state or a water-absorbed state. Specific examples of the pressing method include roll pressing with a predetermined pressure or gap (clearance) and plate pressing with a predetermined pressure, and it is preferable to perform the pressing in the range of 0 to 250 ℃ from the viewpoints of industrial productivity, suppression of thermal decomposition of the polymer material having an ionic group, and the like. In terms of the electrolyte membrane or electrode protection, the pressurization is preferably as weak as possible within a range in which the adhesion between the electrolyte membrane and the catalyst layer is maintained, and in the case of the flat pressing, the pressurization is preferably 10MPa or less, and from the viewpoint of preventing short-circuiting of the anode and cathode electrodes, it is one of preferable options to stack the electrodes and the electrolyte membrane without performing a lamination process, and to use the battery as a water electrolysis apparatus. In this method, when the operation is repeated as a water electrolysis apparatus, the deterioration of the electrolyte membrane, which is presumed to be a cause of the short-circuited portion, tends to be suppressed, and the durability as a water electrolysis apparatus becomes good. In the control of the pressing conditions, it is preferable that the temperature is increased after the pressing, the temperature is maintained at a predetermined voltage and temperature, the pressure is maintained, the temperature is decreased, and then the pressure is released, in order to obtain a uniform electrolyte membrane with a catalyst layer without wrinkles or peeling. If the temperature is raised while applying pressure or the pressure is released before lowering the temperature, three-dimensional thermal shrinkage may occur in a state where the interface between the electrolyte membrane and the catalyst layer is not fixed, and peeling may occur due to wrinkles or poor adhesion.

Physical properties required for the power supply body of the water electrolysis type hydrogen generator include a gas-liquid flow path function, good conductivity, acid resistance, oxidation resistance, hydrogen embrittlement resistance, heat resistance, processability, and the like, and any material can be used as long as it has such physical properties. Examples of the conductive material include a porous conductive sheet mainly composed of a conductive material, and examples of the conductive material include a calcined material derived from polyacrylonitrile, a calcined material derived from pitch, a carbon material such as graphite or expanded graphite, stainless steel, molybdenum, titanium, nickel, zirconium, niobium, tantalum, and the like.

The anode power supply is preferably an inorganic conductive material that is not oxidized by the high potential of the anode at the time of electrolysis of water, and is preferably stainless steel, molybdenum, titanium, nickel, zirconium, niobium, tantalum, or the like, and particularly preferably titanium. The form of the conductive material is not particularly limited, and is fibrous or particulate, and is preferably a fibrous conductive inorganic material (inorganic conductive fiber). As the porous conductive sheet using the inorganic conductive fiber, any one of a woven fabric and a nonwoven fabric can be used. As the woven fabric, plain weave, twill weave, satin weave, jacquard weave (figured crocade), and the like can be used without particular limitation. The nonwoven fabric may be produced by a method such as a papermaking method, a needle punch (needle punch) method, a spunbond (spunbond) method, a water jet punch (water jet punch) method, or a melt-blown (melt-blow) method, without any particular limitation. The porous conductive sheet using the inorganic conductive fibers may be expanded metal (expanded metal), punched metal (woven metal), or woven fabric.

In the porous conductive sheet, conductive particles such as carbon black or conductive fibers such as carbon fibers are preferably added as an auxiliary agent for improving conductivity. Further, the porous conductive sheet is preferably subjected to plating treatment with platinum for the purpose of improving stability.

Examples

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

1. Evaluation method

The measurement conditions for the respective physical properties are as follows.

(1) Molecular weight of the Polymer

The number average molecular weight and the weight average molecular weight of the polymer solution were measured by Gel Permeation Chromatography (GPC). HLC-8022GPC manufactured by Tosoh was used as an integrated apparatus of an ultraviolet detector and a differential refractometer, and 2 TSK gel SuperHM-H (inner diameter 6.0mm, length 15cm) manufactured by Tosoh was used as a GPC column, and the number average molecular weight and the weight average molecular weight were determined by measuring at a flow rate of 0.2 mL/min using an N-methyl-2-pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10mmol/L lithium bromide) in terms of standard polystyrene.

(2) Ion Exchange Capacity (IEC)

The measurement was carried out by neutralization titration. The measurement was performed 3 times, and the arithmetic mean value thereof was taken.

1. The surface of the measurement sample, which was proton-substituted and sufficiently washed with pure water, was wiped to remove water, and then vacuum-dried at 100 ℃ for 12 hours or more to determine the dry weight.

2. 50mL of a 5% by mass aqueous sodium sulfate solution was added to the electrolyte, and the mixture was allowed to stand for 12 hours and then ion-exchanged.

3. The sulfuric acid produced was titrated with a 0.01mol/L aqueous sodium hydroxide solution. As an indicator, a commercially available phenolphthalein solution for titration was added in an amount of 0.1 w/v%, and the point of light purplish red color was defined as an end point.

IEC is determined by the following formula.

IEC (meq/g) — concentration of an aqueous sodium hydroxide solution (mmol/ml) × dropwise addition amount (ml)/dry weight (g) of the sample.

(3) Film thickness of electrolyte film

The measurement was carried out using model ID-C112 manufactured by ミツトヨ, which was attached to a Granite Comparator Stand (Granite Comparator Stand) BSG-20 manufactured by ミツトヨ (mitotoyo).

The film thickness was measured by cutting the electrolyte membrane to 10cm square, measuring the portions 5cm from the end in the MD direction, 1cm, 3cm, 5cm, 7cm, and 9cm from the end in the TD direction, and the portions 5cm from the end in the TD direction, 1cm, 3cm, 5cm, 7cm, and 9cm from the end in the MD direction, and calculating the average value of these 9 points. The average value thereof is defined as the film thickness of the electrolyte membrane.

(4) Confirmation of the mixed region by Scanning Transmission Electron Microscope (STEM), measurement of the thickness thereof, and determination of the thickness of the first, second, and third layers

The sample piece of the electrolyte membrane was immersed in a2 mass% lead acetate aqueous solution as a staining agent, and allowed to stand at 25 ℃ for 48 hours to perform a staining treatment. The dyed sample was taken out and embedded in epoxy resin. The sheet was cut at room temperature by 100nm using an ultra microtome (Ultramicrotome), and observation was performed under the following conditions.

A. For the cut cross section of the electrolyte membrane sheet, energy dispersive X-ray (EDX) quantitative line analysis was performed from one surface (referred to as "surface a" for convenience) side toward the other surface side, i.e., in the thickness direction. The measurement apparatus and the measurement conditions were as follows.

The device comprises the following steps: atomic decomposition energy analysis electron microscope (STEM)

JEM-ARM200F Dual-X (manufactured by JEOL)

EDX Detector JED2300(JEOL manufacturing)

Acceleration voltage: 200 kV.

B. Focusing on the fluorine atom concentration, in the measurement of the above item a, the intensity distribution of the fluorine atom concentration with respect to the thickness direction is obtained with the distance from the surface a taken as the X axis and the fluorine atom concentration taken as the Y axis.

The above operation was performed on 10 samples, and from the 10 intensity distribution curves obtained, an intensity distribution curve (an example is shown in fig. 1) was obtained in which the fluorine atom concentration was averaged with the Y axis being the average value of the fluorine atom concentration. It is to be understood that all samples are measured from the same surface side. In fig. 1, the Y axis indicates a large value in the direction of the arrow.

C. In the intensity distribution curve obtained by the B term and having the averaged fluorine atom concentration, the minimum value of the fluorine atom concentration is taken at the portion corresponding to the first layer, and the maximum value of the fluorine atom concentration is taken at the portion corresponding to the second layer or the third layer as the fluorine atom concentration of the layer. In addition, the corresponding portions can be understood from the stacking order and SEM photograph images.

D. When the fluorine atom concentration of the first layer obtained by the above-mentioned C term is C1 and the fluorine atom concentration of the second layer is C2, a position on the X axis between the position on the X axis where C1 is obtained and the position on the X axis where C2 is obtained and which indicates a fluorine atom concentration of (C1+ C2)/2 is regarded as a boundary surface between the first layer and the second layer. When there are a plurality of positions on the X axis indicating the fluorine atom concentration of (C1+ C2)/2, the position obtained by the arithmetic mean of the X axis coordinate values corresponding to the fluorine atom concentration is regarded as the boundary surface between the first layer and the second layer.

In the case where the third layer is present, a surface regarded as a boundary surface between the first layer or the second layer and the third layer is similarly obtained.

E. When D is defined as the difference between C1 and C2, i.e., | C1-C2|, a region between a position on the X axis where C1 is obtained and a position on the X axis where C2 is obtained and which represents a fluorine concentration of (C1+ C2)/2+0.3 × D, (C1+ C2)/2-0.3 × D is defined as a mixed region, and a thickness corresponding to (C1+ C2)/2 ± 0.3 × D is defined as a thickness of the mixed region. When there are a plurality of positions on the X axis indicating the fluorine concentration of (C1+ C2)/2+0.3 × D or (C1+ C2)/2-0.3 × D, the position determined by the arithmetic average of the X axis coordinate values corresponding to the fluorine atom concentration is the position corresponding to (C1+ C2)/2+0.3 × D or (C1+ C2)/2-0.3 × D.

F. The thicknesses of the first layer, the second layer, and the third layer are determined based on the determined positions of the surfaces regarded as the boundary surfaces of the layers and the distance from the surface a.

(5) Test of bondability

The electrolyte membrane was immersed in pure water at 80 ℃ for 24 hours, and the presence or absence of peeling between the first layer and the second layer was observed. When no peeling was confirmed, "bonding" is shown in the table, and when peeling was confirmed, "peeling" is shown.

(6) Peeling test

1. An electrolyte membrane to be evaluated or an electrolyte membrane with a catalyst layer, and a commercially available NR212(Nafion 50 μm) were prepared by cutting each membrane to 5cm × 12 cm.

2. In the case of an electrolyte membrane with a catalyst layer, the catalyst layer is wiped off by a solvent such as alcohol that does not dissolve the electrolyte membrane.

3. A Teflon (Teflon) sheet (3cm × 5cm) was placed on the upper 3cm portion of the longer side of the electrolyte membrane to be evaluated, and NR212 was superimposed thereon in a position matching the electrolyte membrane to be evaluated.

4. The electrolyte membranes overlapped in the 3. center were overlapped and heated and pressed at 150 ℃ under 4.5MPa for 10 minutes.

5. The sample prepared in 4 was cut into a long strip of 1cm × 12cm to prepare a peel test piece.

6. The electrolyte membrane to be evaluated and NR212 were held by upper and lower chucks of a tensile tester, and the stress at the time of the upper chuck stroke was measured.

7. The average of the stress at the stroke distance of 5cm to 8cm was calculated as the peeling force.

A measuring device: autograph AG-IS (manufactured by Shimadzu corporation)

Stroke speed: 10 mm/min

Test piece: width 1cm x length 12cm

Distance between samples: 2cm

Test temperature: at 23 deg.C in pure water

Test number: n is 5.

(7) Production of electrolyte Membrane (CCM) with catalyst layer

Will be in the middle of the fieldA platinum catalyst TEC10E50E manufactured by metall industries co and "Nafion (registered trademark)" ("Nafion (registered trademark)") manufactured by DuPont corporation were mixed in a ratio of 2: 1 in an amount such that the amount of platinum is 0.3mg/cm²The cathode catalyst layer transfer film a100 was prepared by coating a commercially available Teflon (Teflon) film.

An indium oxide catalyst manufactured by ユミコア and Nafion (registered trademark) ("Nafion (registered trademark)") manufactured by DuPont were mixed in a ratio of 2: 1 in the catalyst ink prepared by adjusting the weight ratio of indium to indium in the ink, the amount of indium was 2.5mg/cm²The anode catalyst layer transfer film a200 was prepared by coating a commercially available Teflon (Teflon) film. 1 pair of films obtained by cutting the anode catalyst layer transfer film a200 and the cathode catalyst layer transfer film a100 into 5cm square pieces were prepared, and the films were superposed so as to face each other with the polymer electrolyte membrane to be evaluated interposed therebetween. In the case of using a laminated electrolyte membrane as a polymer electrolyte membrane, a cathode catalyst layer transfer film a100 is disposed on the first layer side surface, and an anode catalyst layer transfer film a200 is disposed on the second layer side or the third layer side surface. Then, the temperature was increased from the pressurized state, the pressure was heated and pressed at 150 ℃ and 5MPa for 3 minutes, and the temperature was decreased to 40 ℃ or lower in the pressurized state, and then the pressure was released, thereby obtaining an electrolyte membrane with a catalyst layer for a water electrolysis apparatus using a200 as an anode and a100 as a cathode.

(8) Production of Membrane Electrode Assembly (MEA)

The catalyst layer-equipped electrolyte membrane for a water electrolysis apparatus was sandwiched between commercially available porous titanium sintered plates 2 to obtain a membrane electrode assembly for a water electrolysis apparatus.

(9) Water electrolysis performance test

The membrane electrode assembly for a water electrolysis apparatus was mounted on a JARI standard cell "Ex-1" (electrode area 25 cm) manufactured by Yinghe (Co.)²) The cell temperature was set at 80 ℃ and the conductivity was set at 1. mu. Scm^-1The following pure water was supplied to one of the electrodes (oxygen generating electrode: anode) at atmospheric pressure and at a flow rate of 0.2L/min.

The other electrode (hydrogen generating electrode: cathode) was configured such that the pressure could be controlled by a back pressure valve, and was purged with 100% RH nitrogen gas to be at atmospheric pressure before evaluation.

A Multistat 1480 manufactured by ソーラトロン and a Power amplifier Model PBi500L-5U (Power boost Model PBi500L-5U) were used to load a current of 50A (current density 2A/cm)²) And outputting the data. After the current was held at atmospheric pressure for 10 hours, the cell voltage at that time was measured. The lower the cell voltage, the more excellent the water electrolysis efficiency.

(10) Durability test for Water Electrolysis

After the test of (9), a load current of 50A (current density 2A/cm) was further applied under atmospheric pressure²) The cell was kept for 200 hours, and the cell voltage thereafter was measured. Table 1 shows the voltage rise after the durability test. The smaller the voltage rise from the test (9), the more excellent the durability.

2. Synthesis example

Synthesis example 1 Synthesis of Block copolymer b1

(Synthesis of 2, 2-bis (4-hydroxyphenyl) -1, 3-dioxolane (K-DHBP) represented by the following general formula (G1))

In a 500ml flask equipped with a stirrer, a thermometer and a distillation tube, 49.5g of 4, 4' -dihydroxybenzophenone, 134g of ethylene glycol, 96.9g of trimethyl orthoformate and 0.50g of p-toluenesulfonic acid monohydrate were charged and dissolved. Then, stirring the mixture for 2 hours at the temperature of between 78 and 82 ℃. Further, the internal temperature was gradually raised to 120 ℃ until the distillation of methyl formate, methanol and trimethyl orthoformate was completely stopped. After the reaction solution was cooled to room temperature, the reaction solution was diluted with ethyl acetate, and the organic layer was washed with 100mL of a 5% aqueous potassium carbonate solution and separated, and then the solvent was distilled off. To the residue was added 80mL of methylene chloride to precipitate crystals, which were then filtered and dried to obtain 52.0g of 2, 2-bis (4-hydroxyphenyl) -1, 3-dioxolane.

(Synthesis of 3,3 '-disulfonic acid sodium salt-4, 4' -difluorobenzophenone represented by the following general formula (G2))

109.1g (Aldrich reagent) of 4, 4' -difluorobenzophenone in oleum (50% SO)₃)150mL (Wako pure chemical industries, Ltd.) was reacted at 100 ℃ for 10 hours. Thereafter, a small amount of the solution was gradually added to a large amount of water, neutralized with NaOH, and then 200g of common salt was added to precipitate a composition. The obtained precipitate was filtered off, and recrystallized using an aqueous ethanol solution to obtain sodium 3,3 '-disulfonate-4, 4' -difluorobenzophenone represented by the general formula (G2).

(Synthesis of oligomer a 1' not containing Ionic group and represented by the following general formula (G3))

A1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet, and a Dean-Stark Trap (Dean-Stark Trap) was charged with potassium carbonate 16.59g (Aldrich reagent, 120mmol), K-DHBP 25.8g (100mmol), and 4, 4' -difluorobenzophenone 20.3g (Aldrich reagent, 93mmol), and after nitrogen substitution, dehydration was performed at 160 ℃ in N-methylpyrrolidone (NMP)300mL and toluene 100mL, toluene was removed by heating, and polymerization was performed at 180 ℃ for 1 hour. Purification was carried out by reprecipitation using a large amount of methanol to obtain oligomer a1 (terminal hydroxyl group) containing no ionic group. The number average molecular weight was 10000.

A500 mL three-necked flask equipped with a stirrer, a nitrogen inlet, and a dean-Stark trap was charged with potassium carbonate (1.1 g, Aldrich reagent (8 mmol)), and the above oligomer a1 (terminal hydroxyl group) containing no ionic group (20.0 g, 2mmol), and after nitrogen substitution, the flask was dehydrated at 100 ℃ in NMP (100 mL) and cyclohexane (30 mL), and then heated to remove cyclohexane, and then charged with decafluorobiphenyl (4.0 g, Aldrich reagent (12 mmol)) and reacted at 105 ℃ for 1 hour. Purification was carried out by reprecipitation using a large amount of isopropanol to obtain an oligomer a 1' (terminal fluoro group) not containing an ionic group represented by the following formula (G3). The number average molecular weight is 11000, and the number average molecular weight of the oligomer a 1' containing no ionic group is 10400 obtained by subtracting the linking (linker) site (molecular weight 630).

(here, m is a positive integer)

(Synthesis of Ionic group-containing oligomer a2 represented by the following general formula (G4))

A1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet, and a dean-Stark trap was charged with 27.6g of potassium carbonate (Aldrich reagent, 200mmol), 12.9g (50mmol) of K-DHBP, 9.3g (Aldrich reagent, 50mmol) of 4,4 ' -biphenol, 39.3g (93mmol) of 3,3 ' -disulfonic acid 4,4 ' -difluorobenzophenone, and 18-crown-617.9 g (Wako pure chemical 82mmol), and after nitrogen substitution, dehydration was performed at 170 ℃ in 300mL of NMP or 100mL of toluene, toluene was removed by heating, and polymerization was performed at 180 ℃ for 1 hour. Purification was performed by reprecipitation using a large amount of isopropanol to obtain an oligomer a2 (terminal hydroxyl group) containing an ionic group represented by the following formula (G4). The number average molecular weight was 16000.

(in the formula (G4), M represents sodium or potassium; n is a positive integer)

(Synthesis of oligomer a2 as the segment containing ionic groups (A1), oligomer a1 as the segment containing no ionic groups (A2), and Block Polymer b1 of octafluorobiphenylene as the linking site)

A500 mL three-necked flask equipped with a stirrer, a nitrogen inlet, and a dean-Stark trap was charged with 0.56g of potassium carbonate (Aldrich reagent, 4mmol) and 16g (1mmol) of an oligomer a2 (terminal hydroxyl group) containing an ionic group, and after nitrogen substitution, the flask was dehydrated at 100 ℃ in 100mL of NMP or 30mL of cyclohexane, the cyclohexane was heated to remove the cyclohexane, and 11g (1mmol) of an oligomer a 1' (terminal fluorine group) containing no ionic group was added to the flask, and the reaction was carried out at 105 ℃ for 24 hours. Reprecipitation was conducted using a large amount of isopropanol to thereby purify, and a block copolymer b1 was obtained. Weight average molecular weight is 34 ten thousand

The block copolymer b1 itself was used as a polymer electrolyte membrane, and after a proton substitution/deprotection reaction was performed by immersing in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours, it was immersed in a large excess amount of pure water for 24 hours and sufficiently washed, and the ion exchange capacity determined by neutralization titration was 2.12 meq/g.

Synthesis example 2 Synthesis of Block copolymer b2

(Synthesis of polyether sulfone (PES) -based Block copolymer precursor b 2' comprising the segment represented by the following formula (G6) and the segment represented by the following formula (G7))

1.78g of anhydrous nickel chloride was mixed with 15mL of dimethyl sulfoxide, and the mixture was adjusted to 70 ℃. 2.37g of 2, 2' -bipyridine was added thereto, and the mixture was stirred at that temperature for 10 minutes to prepare a nickel-containing solution.

Here, 1.35G of zinc powder was added to a solution obtained by dissolving 1.64G of 2, 5-dichlorobenzenesulfonic acid (2, 2-dimethylpropyl) ester and 0.55G of polyether sulfone represented by the following formula (G5) (スミカエクセル PES5200P, Mn of 40,000, Mw of 94,000, manufactured by sumitomo chemical corporation) in 5mL of dimethyl sulfoxide, and the mixture was adjusted to 70 ℃. The solution containing nickel was injected thereto, and polymerization was carried out at 70 ℃ for 4 hours. The reaction mixture was added to 60mL of methanol, followed by addition of 60mL of 6mol/L hydrochloric acid and stirring for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.75G of an off-white block copolymer precursor b 2' (polyarylene precursor) containing a segment represented by the following formula (G6) and the following formula (G7) in a yield of 97%. The weight average molecular weight was 21 ten thousand.

(here, n is independently a positive integer in the formulae (G5) and (G7))

(Synthesis of polyether sulfone (PES) -based Block copolymer b2 comprising the segment represented by the above formula (G7) and the segment represented by the following formula (G8))

0.25g of block copolymer precursor b 2' was added to a mixed solution of 0.18g of lithium bromide monohydrate and 8mL of N-methyl-2-pyrrolidone, and reacted at 120 ℃ for 24 hours. The reaction mixture was poured into 80mL of 6mol/L hydrochloric acid and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain an off-white block copolymer b2 comprising the segment represented by the formula (G7) and the segment represented by the following formula (G8). The weight average molecular weight of the obtained polyarylene (polyarylene) was 19 ten thousand.

The block copolymer b2 itself was used as a polymer electrolyte membrane, and was immersed in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours to perform proton substitution, and then immersed in a large excess amount of pure water for 24 hours to perform sufficient washing, and the ion exchange capacity determined by neutralization titration was 2.02 meq/g.

Synthesis example 3 Synthesis of Block copolymer b3

(Synthesis of hydrophobic oligomer a3 represented by the following formula (G9))

(here, k is a positive integer)

51.9g (0.30mol) of 2, 6-dichlorobenzonitrile, 92.8g (0.27mol) of 2, 2-bis (4-hydroxyphenyl) -1,1,1,3,3, 3-hexafluoropropane and 49.7g (0.36mol) of potassium carbonate were weighed in a 1L three-necked flask equipped with a stirrer, a thermometer, a cooling tube, a Dean-Stark tube and a three-way cock for introducing nitrogen gas.

After nitrogen substitution, 363mL of sulfolane and 181mL of toluene were added and stirred. The flask was immersed in an oil bath and heated to reflux to 150 ℃. The water produced by the reaction was azeotroped with toluene, and the reaction was carried out while removing the water from the system by a dean-stark tube, and the production of water was hardly observed in about 3 hours. After removing most of toluene while slowly raising the reaction temperature, the reaction was continued at 200 ℃ for 3 hours. Next, 12.9g (0.076mol) of 2, 6-dichlorobenzonitrile was added, and the reaction was continued for 5 hours.

The obtained reaction solution was left to cool, and then 100mL of toluene was added thereto for dilution. The precipitate of the inorganic compound produced as a by-product was removed by filtration, and the filtrate was poured into 2L of methanol. The precipitated product was filtered off, recovered and dried, and then dissolved in 250mL of tetrahydrofuran. This was reprecipitated in methanol 2L to obtain 109g of the objective oligomer. The oligomer had a number average molecular weight of 8,000.

(Synthesis of hydrophilic monomer represented by the following formula (G10))

245g (2.1mol) of chlorosulfonic acid was put into a 3L three-necked flask equipped with a stirrer and a cooling tube, followed by 105g (420mmol) of 2, 5-dichlorobenzophenone, and the mixture was reacted in an oil bath at 100 ℃ for 8 hours. After a predetermined time, the reaction mixture was slowly poured into 1000g of crushed ice and extracted with ethyl acetate. The organic layer was washed with brine, dried over magnesium sulfate, and ethyl acetate was distilled off to obtain pale yellow crude crystalline 3- (2, 5-dichlorobenzoyl) benzenesulfonyl chloride. The crude crystals were used directly in the next step without purification.

41.1g (462mmol) of 2, 2-dimethyl-1-propanol (neopentyl alcohol) was added to 300mL of pyridine and cooled to about 10 ℃. Here, it took about 30 minutes to slowly add the obtained crude crystals. After the addition of the total amount, the mixture was further stirred for 30 minutes to allow the reaction. After the reaction, the reaction mixture was poured into 1000mL of hydrochloric acid water, and the precipitated solid was collected. The obtained solid was dissolved in ethyl acetate, washed with an aqueous sodium bicarbonate solution and brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain a crude crystal. It was recrystallized from methanol to obtain white crystals of 3- (2, 5-dichlorobenzoyl) benzenesulfonic acid neopentyl ester represented by the structural formula.

(Synthesis of polyarylene block copolymer b3 represented by the following formula (G11))

(here, k, m, and n are each independently a positive integer.)

In a 1L 3-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, 166mL of dry N, N-dimethylacetamide (DMAc) was added to a mixture of 315.1 g (1.89mmol) of the hydrophobic oligomer A, 39.5g (98.4mmol) of neopentyl 3- (2, 5-dichlorobenzoyl) benzenesulfonate, 2.75g (4.2mmol) of bis (triphenylphosphine) nickel dichloride, 11.0g (42.1mol) of triphenylphosphine, 0.47g (3.15mmol) of sodium iodide and 16.5g (2.53mmol) of zinc under nitrogen.

The reaction system was heated with stirring (finally warmed to 82 ℃ C.) and reacted for 3 hours. A viscosity increase in the system was observed in the middle of the reaction. The polymerization reaction solution was diluted with 180mL of DMAc, stirred for 30 minutes, and filtered using ceria as a filter aid. To a 1L 3-neck flask equipped with a stirrer, 1/3 portions of 25.6g (295 mmol) of lithium bromide were added at intervals of 3 times with 1 hour therebetween to the filtrate, and the mixture was reacted at 120 ℃ for 5 hours under a nitrogen atmosphere. After the reaction, the reaction mixture was cooled to room temperature and poured into 4L of acetone to solidify. After the coagulated product was collected by filtration and air-dried, it was pulverized by a mixer and washed with 1500mL of 1N sulfuric acid while stirring. After filtration, the product was washed with ion-exchanged water until the pH of the washing solution became 5 or more, and then dried at 80 ℃ overnight to obtain the objective block copolymer b 3. The weight average molecular weight of this block copolymer was 20 ten thousand.

The block copolymer b3 itself was used as a polymer electrolyte membrane, and was immersed in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours to perform proton substitution, and then immersed in a large excess amount of pure water for 24 hours to perform sufficient washing, and the ion exchange capacity determined by neutralization titration was 2.38 meq/g.

Synthesis example 4 Synthesis of random copolymer r1

(Synthesis of polyketone random copolymer r1 comprising monomer represented by the formula (G1), 4' -difluorobenzophenone and monomer represented by the formula (G2))

Into a 500mL three-necked flask equipped with a stirrer, a nitrogen inlet, and a dean-Stark trap were charged 13.82g (Aldrich reagent, 100mmol), 20.66g (80mmol) of K-DHBP obtained as an intermediate in Synthesis example 1, 10.5g (Aldrich reagent, 48mmol) of 4,4 ' -difluorobenzophenone, and 13.5g (32mmol) of 3,3 ' -disulfonic acid-4, 4 ' -difluorobenzophenone obtained as an intermediate in Synthesis example 1, and after nitrogen substitution, the mixture was dehydrated at 180 ℃ in 100mL of N-methylpyrrolidone (NMP) and 50mL of toluene, and then the temperature was raised to remove toluene, and polymerization was carried out at 230 ℃ for 6 hours. Reprecipitation was carried out using a large amount of water to thereby purify, and a polyketone random copolymer was obtained. The weight average molecular weight was 25 ten thousand.

The random copolymer r1 itself was used as a polymer electrolyte membrane, and after a proton substitution/deprotection reaction was performed by immersing in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours, it was immersed in a large excess amount of pure water for 24 hours and sufficiently washed, and the ion exchange capacity determined by neutralization titration was 1.51 meq/g.

[ example 1]

20g of the block copolymer b1 obtained in Synthesis example 1 was dissolved in 80g of NMP and stirred at 20,000rpm for 1 hour by a stirrer to prepare a transparent polyelectrolyte solution b1 having a polymer concentration of 20 mass%.

The resulting polyelectrolyte solution b1 was pressure-filtered using a glass fiber filter, and then the polyelectrolyte solution b1 was cast onto a polyethylene terephthalate (PET) substrate using an applicator, and dried at 100 ℃ for 4 hours to obtain a polymer in the form of a film. The resulting film was immersed in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours to carry out a proton substitution/deprotection reaction, then immersed in a large excess of pure water for 24 hours to sufficiently clean the film, and dried at room temperature to obtain a first layer (film thickness: 50 μm).

On one side of the obtained first layer, a polymer electrolyte solution a (solid content ratio: fluorine polymer electrolyte/polyvinylidene fluoride: 60 mass%/40 mass%, solid content concentration 10 mass%) obtained by dissolving Nafion (a commercially available solution D2020 manufactured by Chemours) as a fluorine polymer electrolyte and W #9300 (weight average molecular weight >100 ten thousand) manufactured by Kureha as a polyvinylidene fluoride in NMP was applied by a bar coater, and dried at 120 ℃ for 2 hours to form a layer, which was immersed in a large excess of pure water for 24 hours and sufficiently washed, and dried at room temperature to form a second layer, thereby obtaining a laminated electrolyte membrane (membrane thickness 55 μm). The thickness of the mixed region of the obtained laminated electrolyte membrane was 1.8 μm.

[ example 2]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that 0.1 mass% of platinum fine particles (average particle diameter 5nm) were added to the polymer electrolyte solution A.

[ example 3]

On the surface of the laminated electrolyte membrane obtained in example 1 on which the second layer on the first layer side was not provided, a20 mass% solution of Nafion (solution D2020, manufactured by commercially available chemiurs) containing 0.2 mass% of platinum fine particles (average particle diameter 5nm) was applied by a bar coater, and dried at 100 ℃ for 1 hour to prepare a third layer, and a laminated electrolyte membrane (film thickness 65 μm) was obtained.

[ example 4]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that W #7200 (weight average molecular weight: 63 ten thousand) produced by commercially available wu-yu (Kureha) was used as polyvinylidene fluoride instead of W #9300 produced by commercially available wu-yu (Kureha).

[ example 5]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that W #1100 (weight average molecular weight: 28 ten thousand) produced by commercial wu-feather (Kureha) was used as polyvinylidene fluoride in place of W #9300 produced by commercial wu-feather (Kureha).

[ example 6]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the solid content ratio of the polymer electrolyte solution a was changed to 90 mass%/10 mass% for the fluorine-based polymer electrolyte/polyvinylidene fluoride.

[ example 7]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the solid content ratio of the polymer electrolyte solution a was changed to 20 mass%/80 mass% of the fluorine-based polymer electrolyte/polyvinylidene fluoride.

[ example 8]

A laminated electrolyte membrane (film thickness: 80 μm) was obtained in the same manner as in example 1, except that the second layer was formed to have a thickness of 30 μm.

[ example 9]

A laminated electrolyte membrane (50.5 μm thick) was obtained in the same manner as in example 1, except that the second layer was 0.5 μm thick.

[ example 10]

A laminated electrolyte membrane (film thickness 11 μm) was obtained in the same manner as in example 1, except that the first layer was 10 μm thick and the second layer was 1 μm thick.

[ example 11]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the block copolymer b2 obtained in Synthesis example 2 was used in place of the block copolymer b 1.

[ example 12]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the block copolymer b3 obtained in Synthesis example 3 was used in place of the block copolymer b 1.

[ example 13]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the random copolymer r1 obtained in Synthesis example 4 was used in place of the block copolymer b 1.

[ example 14]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the solid content ratio of the polymer electrolyte solution a was changed to 95 mass%/5 mass% of the fluorine-based polymer electrolyte/polyvinylidene fluoride.

[ example 15]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that the solid content ratio of the polymer electrolyte solution a was changed to 5 mass%/95 mass% of the fluorine-based polymer electrolyte/polyvinylidene fluoride.

[ example 16]

A laminated electrolyte membrane (55 μm thick) was obtained in the same manner as in example 1, except that W #7300 (weight average molecular weight >100 ten thousand) produced from commercially available wu-feather (Kureha) was used as polyvinylidene fluoride in place of W #9300 produced from commercially available wu-feather (Kureha).

Comparative example 1

A first monolayer electrolyte membrane (50 μm thick) was obtained in the same manner as described in the previous paragraph of example 1. The initial performance is relatively good, but the durability is poor, so the longer the use is, the more unfavorable.

Comparative example 2

A laminated electrolyte membrane (55 μm) was obtained in the same manner as in example 1, except that a20 mass% NMP solution of Nafion (Nafion) (used by replacing NMP with a solution D2020, manufactured by commercially available chemiurs) was used instead of the polymer electrolyte solution a. Peeling of the first layer and the second layer occurs in the dried laminated electrolyte membrane.

Comparative example 3

A solution obtained by mixing a solution D2020 manufactured by Chemours corporation and sold as Nafion solution, KYNAR late RC-10,278 manufactured by アルケマ and sold as polyvinylidene fluoride solution, and water and isopropyl alcohol (IPA) in a mass ratio of 1: 1 is prepared from the following solvents in a mass ratio of 2.3: 1: 4.3A laminated electrolyte membrane (55 μm) was obtained in the same manner as in example 1, except that the polymer electrolyte solution B prepared by mixing the components was used in place of the polymer electrolyte solution A.

The laminated electrolyte membrane produced in this example did not have a mixed region formed.

Comparative example 4

A solution D2020 manufactured by Chemours corporation, which is commercially available as a Nafion solution, was cast on a PET substrate and dried at 100 ℃ for 1 hour, thereby obtaining a first layer (film thickness 50 μm).

On one side of the obtained first layer, a polymer electrolyte solution B (solid content ratio: block copolymer B1/polyvinylidene fluoride 60 mass%/40 mass%, solid content concentration 10 mass%) prepared by dissolving block copolymer B1 and W #9300 produced as polyvinylidene fluoride from commercial wuyu (Kureha) in NMP was applied by a bar coater, and dried at 120 ℃ for 2 hours, to form a layer. The resulting membrane was immersed in a10 mass% sulfuric acid aqueous solution at 80 ℃ for 24 hours to carry out a proton substitution/deprotection reaction, then immersed in a large excess of pure water for 24 hours to sufficiently clean the membrane, and dried at room temperature to prepare a second layer, thereby obtaining a laminated electrolyte membrane (55 μm thick). Peeling of the first layer and the second layer occurs in the dried laminated electrolyte membrane.

Comparative example 5

A nafion film (film thickness 50 μm) was obtained in the same manner as described in the previous paragraph of comparative example 4. Table 1 shows the structure and physical properties of the polymer electrolyte membrane used in each example and comparative example, the results of hydrogen compression evaluation, and water electrolysis evaluation.

TABLE 1

In the "polymer electrolyte" of the first layer in the table, b1 represents block copolymer b1, b2 represents block copolymer b2, b3 represents block copolymer b3, and r1 represents random copolymer r 1.

The present application claims priority based on the japanese patent application No. 2019-063208 filed on 28/3/2019, and may refer to all the contents described in the appended claims and specification of the application of the japanese patent application.

Description of the figures

1 first layer

2 the second layer

3 mixing zone