JP2008031462A - Polyelectrolyte emulsion and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyelectrolyte emulsion affording a film that exhibits high adhesion to a substrate, suffers from little deterioration in adhesion particularly even if brought into contact with water or exposed to a highly humid state and has high durability. <P>SOLUTION: [1] The polyelectrolyte emulsion comprises polyelectrolyte particles dispersed in a dispersing medium and has a ζ potential of within the range of -50 to -300 mV at a measuring temperature of 25°C. [2] The polyelectrolyte emulsion described in [1] has a volume-average particle size of 100 nm to 200 μm. [3] A catalyst layer is obtained from a catalyst composition comprising the polyelectrolyte emulsion described in [1] or [2] and a catalyst component. The membrane electrode assembly having the catalyst layer and a solid polymer fuel cell are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention contains a polymer electrolyte which can be used as a binder, a coating material, a battery electrolyte, a polymer solid electrolyte for a fuel cell, a fuel cell electrode, a solid capacitor, an ion exchange membrane, various sensors and the like as solid fine particles. The invention relates to a polymer electrolyte emulsion.

  Conventionally, polymers having hydrophilic groups such as sulfonic acid groups, carboxyl groups (carboxylic acid groups), and phosphoric acid groups have been used for surfactants, emulsifiers, dispersants, solid polymer electrolytes, ion exchange membranes, and the like. Yes. On the other hand, in recent years, such polymers have been applied to binder resins, coating materials, surface treatment agents, and battery electrolytes by taking advantage of the properties such as dispersibility in solvents, hydrophilicity, ion trapping properties, and low volume resistance. It is being considered.

For example, Patent Document 1 discloses that an aqueous dispersion containing a polyorganosiloxane having a sulfonic acid group can form a film with good film formability and excellent water resistance.
Patent Document 2 discloses a step of preparing a dispersion having a negative zeta potential by mixing a cation exchange resin (polymer having a sulfonic acid group) and alcohol, and heating the dispersion. Thus, the step of changing the zeta potential to positive (plus) and the coating liquid obtained by mixing the catalyst powder with the dispersion whose zeta potential is changed efficiently coats the catalyst powder with a cation exchange resin. It is disclosed that it is suitable for producing a catalyst layer of a membrane electrode assembly for a polymer electrolyte fuel cell by increasing the reaction sites at the three-phase interface.

Japanese Patent Laying-Open No. 2005-132996 (Claims) Japanese Patent Laying-Open No. 2005-174861 (Claims)

  The object of the present invention is to provide a film showing high adhesion to a substrate, in particular, a polymer that gives a highly durable film with little decrease in adhesion even when contacted with water or exposed to high humidity. It is to provide an electrolyte emulsion.

The polymer disclosed in Patent Document 1 or Patent Document 2 is a film material, a binder material, or a coating material. Since such a peeling tends to become prominent when brought into contact with water or exposed to a high humidity state, there is a problem that durability (water resistance) becomes insufficient.
As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have completed the present invention. That is, the present invention provides a polymer electrolyte emulsion of the following [1], [2], [3] or [4].
[1] A polymer electrolyte emulsion in which polymer electrolyte particles are dispersed in a dispersion medium and having a zeta potential in the range of −50 mV to −300 mV at a measurement temperature of 25 ° C. [2] The polymer electrolyte emulsion of [1] having a zeta potential in the range of −50 mV to −150 mV [3] The polymer electrolyte particles are dispersed in a dispersion medium, and the zeta potential at a measurement temperature of 25 ° C. is − Polymer electrolyte emulsion obtained in the range of 50 mV to -300 mV [4] Polymer electrolyte emulsion of [3] obtained in the above zeta potential in the range of -50 mV to -150 mV

Furthermore, the present invention provides a preferred embodiment according to any one of the polymer electrolyte emulsions described above,
[5] A polymer electrolyte emulsion according to any one of [1] to [4], in which a volume average particle size determined by a dynamic light scattering method is 100 nm to 200 μm.

In addition, the present invention provides the following [6] to [10] as embodiments using any of the polymer electrolyte emulsions described above.
[6] The polymer electrolyte emulsion according to any of the above, which is used for an electrode of a solid polymer fuel cell [7] A catalyst composition comprising any of the polymer electrolyte emulsions described above and a catalyst component [8] Membrane of membrane electrode assembly [10] [9] having solid polymer fuel cell electrode [9] [8] comprising polymer catalyst composition of [7] Solid polymer fuel cell having an electrode assembly

  In the polymer electrolyte emulsion of the present invention, the polymer electrolyte emulsion having a zeta potential of −50 mV to −300 mV can form a film having high adhesion to the substrate. Furthermore, the polymer electrolyte emulsion having the zeta potential of −50 mV to −150 mV hardly peels off from the substrate even in a high humidity state, and can form a highly water-resistant coating film. Such a coating is extremely useful as a membrane material, a binder material or a coating material, especially as a catalyst layer of a polymer electrolyte fuel cell.

Hereinafter, the present invention will be sequentially described.
<Polymer electrolyte emulsion>
The polymer electrolyte emulsion of the present invention is an emulsion in which polymer electrolyte particles containing a polymer electrolyte are dispersed in a dispersion medium. The production method is not particularly limited. For example, a polymer electrolyte is dissolved in a solvent containing a good solvent for the polymer electrolyte to obtain a polymer electrolyte solution, and then the polymer electrolyte solution. Is dropped into another solvent (poor solvent for the polymer electrolyte) as a dispersion medium for the emulsion, and polymer electrolyte particles are precipitated and dispersed in the dispersion medium to obtain a polymer electrolyte dispersion (polymer electrolyte emulsion). ) Is exemplified. Further, the step of removing the good solvent contained in the obtained polymer electrolyte dispersion using membrane separation such as a dialysis membrane, and further, the polymer electrolyte dispersion is concentrated by distillation or the like to reduce the polymer electrolyte concentration. Adjustment can be shown as a more preferable manufacturing method. By this method, a polymer electrolyte emulsion having stable dispersibility can be produced from any polymer electrolyte. In the exemplified production method, the definitions of “good solvent” and “poor solvent” are defined by the weight of the polymer electrolyte that can be dissolved in 100 g of the solvent at 25 ° C. 1 g or more of the polymer electrolyte is a soluble solvent, and the poor solvent is a solvent in which the polymer electrolyte can dissolve only 0.05 g or less.
The polymer electrolyte emulsion of the present invention can be produced by such a production method. More preferably, the solvent used for preparing the polymer electrolyte solution can sufficiently dissolve the applied polymer electrolyte. It is preferable to contain a good solvent to the extent. In this way, the polyelectrolyte molecules exist in the polyelectrolyte solution in a state in which the molecular chains are relatively spread. When such a polyelectrolyte molecule is charged into the poor solvent to form a polyelectrolyte particle, a portion of the polyelectrolyte molecule having a relatively high affinity for the poor solvent is a particle surface. In addition, a portion having a relatively low affinity is likely to be oriented inside the particle, whereby the surface state of the polymer electrolyte particle can be controlled. The polymer electrolyte emulsion of the present invention requires the zeta potential of the polymer electrolyte particles to be in the above range, and in this respect, a production method that can easily control the surface state of the polymer electrolyte particles is preferable. In addition, when a part of the polymer electrolyte is deposited in the polymer electrolyte solution, the deposited polymer electrolyte is seeded in the process of being charged into the poor solvent to obtain polymer electrolyte particles. As a result, the particle diameter of the polymer electrolyte particles tends to be non-uniform, and a polymer electrolyte emulsion having a suitable average particle diameter described later may be difficult to obtain. In order to avoid such inconvenience, it is preferable that the solvent used in preparing the polymer electrolyte solution contains a good solvent to such an extent that the applied polymer electrolyte can be sufficiently dissolved. As a suitable polymer electrolyte solution, it is sufficient that it is dissolved to such an extent that it can pass through a 0.2 μm pore size filter.

<Zeta potential>
The surface of the polyelectrolyte particles contained in the polyelectrolyte emulsion of the present invention is charged by the ion exchange groups of the polyelectrolyte contained in the polyelectrolyte particles being ionized in the dispersion medium, and the surface potential (zeta potential). ).
The zeta potential of the polymer electrolyte emulsion of the present invention is determined by measurement of electrophoretic mobility by a laser Doppler method at a measurement temperature of 25 ° C. Such zeta potential is due to the particulate matter contained in the polymer electrolyte emulsion, and the potential resulting from the polymer electrolyte particles is of course used using an additive as described later. When the additive particles dispersed in the form of particles are contained, it may be caused by a potential due to the additive particles.

  Here, since the polymer electrolyte emulsion obtained by the production method exemplified above is easy to obtain polymer electrolyte particles in which the ion exchange groups are oriented toward the particle surface, the molecular structure of the polymer electrolyte, the ion By controlling the exchange capacity or the degree of ion dissociation of ion exchange groups, a polymer electrolyte emulsion having a high zeta potential can be obtained. Further, the zeta potential can be controlled by a dielectric constant of the dispersion medium and a zeta potential adjusting agent (details will be described later) such as an ionic strength adjusting agent soluble in the dispersion medium.

  The inventors of the present invention have various adhesion characteristics of polymer electrolyte emulsions including different molecular structures, adhesion strength of the obtained film to the substrate, durability of the film to water (water resistance), etc. As a result, it was found that when the zeta potential of the polymer electrolyte emulsion is in the range of −50 mV to −300 mV, it is possible to form a film having good adhesion to the substrate. In order to obtain a film having good adhesion, it is more preferable that the zeta potential of the polymer electrolyte emulsion is -100 mV to -300 mV. Furthermore, the present inventors have a zeta potential in the range of −50 to −150 mV of the polymer electrolyte emulsion, even if the resulting coating comes into contact with water or is exposed to a high humidity state. It has been found that water resistance to such an extent that adhesion can be maintained is developed. In order to obtain higher water resistance, the zeta potential is particularly preferably −50 mV to −120 mV.

The reason why such adhesion and water resistance are manifest is not clear, but the present inventors presume as follows. That is, the adhesiveness is presumed to be due to the electrostatic interaction between the particles and the substrate due to the surface potential of the particles contained in the polymer electrolyte emulsion. Further, regarding the durability of the coating, in the range of an appropriate zeta potential, the hydrophobic portion of the polymer electrolyte tends to appear particularly on the surface of the polymer electrolyte particle, and the network between the hydrophobic portions of the polymer electrolyte particle is formed during the coating formation. Is presumed to be formed.
Note that a polymer electrolyte emulsion having a zeta potential in the range of 0 mV to -50 mV is not preferable because the adhesion to the substrate is remarkably lowered. On the other hand, a negatively charged polymer electrolyte emulsion exceeding −300 mV requires a polymer electrolyte having a large amount of ion-exchange groups in the molecule, and thus the production itself is difficult.
A suitable polymer electrolyte and a suitable dispersion medium for obtaining such a zeta potential polymer electrolyte emulsion will be described later.

<Average particle size>
The average particle size of the particles contained in the polymer electrolyte emulsion of the present invention is preferably in the range of 100 nm to 200 μm, expressed as a volume average particle size determined by a dynamic light scattering method. The average particle size is preferably in the range of 150 nm to 10 μm, and more preferably in the range of 200 nm to 1 μm. When the average particle size is in the above range, the resulting polymer electrolyte emulsion has practical storage stability, and when the coating is formed, the uniformity of the coating tends to be relatively good. . The above particles refer to all the particulate substances dispersed in the polymer electrolyte emulsion in the form of particles. In addition to the polymer electrolyte particles containing the polymer electrolyte, the following additives are used. Is a concept including all particles dispersed in the polymer electrolyte emulsion, such as particles made of the additive.

<Polymer electrolyte>
Next, a suitable polymer electrolyte applied to the present invention will be described.
The polymer electrolyte used in the present invention includes, for example, a sulfonic acid group (—SO ₃ H), a carboxyl group (—COOH), a phosphonic acid group (—PO (OH) ₂ ), a phosphinic acid group (—POH (OH )), Sulphonimide groups (—SO ₂ NHSO ₂ —), cation exchange groups such as phenolic hydroxyl groups (—Ph (OH) (Ph represents a phenyl group)), or primary to tertiary amine groups Having an anion exchange group such as Among these, a polymer electrolyte having a sulfonic acid group and / or a phosphonic acid group is more preferable, and a polymer electrolyte having a sulfonic acid group is particularly preferable.

  Representative examples of such a polymer electrolyte include, for example, (A) a polymer electrolyte in which a sulfonic acid group and / or a phosphonic acid group are introduced into a polymer having a main chain composed of an aliphatic hydrocarbon; A polymer electrolyte in which a sulfonic acid group and / or a phosphonic acid group are introduced into a polymer in which all or some of the hydrogen atoms in the hydrocarbon chain are substituted with fluorine atoms; (C) an aromatic polymer having an aromatic ring in the main chain; A polyelectrolyte in which a sulfonic acid group and / or a phosphonic acid group is introduced into the molecule; (D) a sulfonic acid group and / or a polymer such as polysiloxane or polyphosphazene substantially free of carbon atoms in the main chain; A polyelectrolyte in which a phosphonic acid group has been introduced; (E) any one selected from repeating units constituting the polymer before introduction of the sulfonic acid group and / or phosphonic acid group in (A) to (D) A polyelectrolyte in which a sulfonic acid group and / or a phosphonic acid group is introduced into a copolymer comprising at least one kind of repeating unit; (F) a basic nitrogen atom in the main chain or side chain, and sulfuric acid in the nitrogen atom And a polymer electrolyte into which an acidic compound such as phosphoric acid is introduced by ionic bonding.

  Examples of the polymer electrolyte (A) include a resin in which a sulfonic acid group is introduced into a polyvinyl sulfonic acid such as an ethylene-vinyl sulfonic acid copolymer, polystyrene, or poly (α-methylstyrene) with a sulfonating agent. Polystyrene sulfonic acid, poly (α-methylstyrene) sulfonic acid, and the like.

  Examples of the polymer electrolyte (B) include, as described in JP-A-9-102322, a main chain formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, and a sulfonic acid group. Sulfonic acid type polystyrene-graft-ethylene-tetrafluoroethylene copolymer (ETFE) composed of a hydrocarbon-based side chain having benzene, U.S. Pat. No. 4,012,303 or U.S. Pat. No. 4,605,685 And α, β, β-trifluorostyrene are graft-polymerized to a copolymer of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer described in the publication No. 1, and then a sulfone such as chlorosulfonic acid or fluorosulfonic acid. Examples thereof include a polymer electrolyte obtained by introducing a sulfonic acid group with an agent.

  The polymer electrolyte (C) may be one in which the main chain is interrupted by a hetero atom such as an oxygen atom. For example, polyether ether ketone, polysulfone, polyether sulfone, poly (arylene ether) ), Polyimide, poly ((4-phenoxybenzoyl) -1,4-phenylene), polyphenylene sulfide, polyphenylquinoxalen and other homopolymers each having a sulfonic acid group introduced therein, sulfoarylated polybenz Imidazole, sulfoalkylated polybenzimidazole, phosphoalkylated polybenzimidazole (JP-A-9-110882), phosphonated poly (phenylene ether) (J. Appl. Polym. Sci., 18, 1969 (1974)), etc. Is mentioned.

  Examples of the polymer electrolyte (D) include those in which a sulfonic acid group is introduced into polyphosphazene.

As the polymer electrolyte of (E), a sulfonic acid group and / or a phosphonic acid group are introduced into a random copolymer, but a sulfonic acid group and / or a phosphonic acid group are introduced into an alternating copolymer. The sulfonic acid group and / or the phosphonic acid group may be introduced into the block copolymer.
Examples of the sulfonic acid group introduced into the random copolymer include a sulfonated polyethersulfone-dihydroxybiphenyl copolymer described in JP-A-11-116679.
As the block copolymer, for example, as disclosed in JP-A-2001-250567, a block copolymer having a block containing a sulfonic acid group, or a sulfonic acid group of this block copolymer Examples thereof include block copolymers in which a part or all of them are replaced with phosphonic acid groups.

  Examples of the polymer electrolyte (F) include polybenzimidazole containing phosphoric acid described in JP-T-11-503262.

  Among the polymer electrolytes as described above, the polymer electrolytes (C) and (E) are preferable from the viewpoint of achieving both higher adhesion and water resistance (durability). Those having an acid group-introduced structure and a polymer main chain having an aromatic ring are preferred because polymer electrolyte particles having a high negative zeta potential can be easily obtained.

  Among the block copolymers, a block copolymer having a segment having an ion exchange group and a segment having substantially no ion exchange group is preferable. Such a block copolymer may be a block copolymer having one of these segments, or may be a block copolymer having two or more of any one segment. Any of multiblock copolymers having two or more may be used.

Furthermore, the polyelectrolyte emulsion of the present invention may contain other components in addition to the above-described polyelectrolyte particles as long as the effects intended by the present invention are not hindered. Examples of such other components include inorganic or organic particles, adhesion assistants, sensitizers, leveling agents, and coloring agents.
In particular, when the coating obtained from the polymer electrolyte emulsion of the present invention is used as a constituent component of a fuel cell electrode, a peroxide is generated at the electrode during the operation of the fuel cell. The substance diffuses and changes to radical species, which moves to the ion conductive membrane bonded to the electrode, and may deteriorate the ion conductive material (polymer electrolyte) constituting the ion conductive membrane. . In order to avoid such inconvenience, it is preferable to use a stabilizer capable of imparting radical resistance as an additive in the polymer electrolyte emulsion.
Such a stabilizer may be contained in the polymer electrolyte particles constituting the polymer electrolyte emulsion, may be dissolved in the dispersion medium, or other than the polymer electrolyte particles, It may exist as fine particles composed of components.

<Dispersion medium>
The dispersion medium constituting the polymer electrolyte emulsion of the present invention is not particularly limited as long as the dispersibility of the applied polymer electrolyte is not hindered, and water, alcohol solvents such as methanol and ethanol, and nonpolar organic materials such as hexane and toluene. A solvent or a mixture thereof is used. Among these, it is preferable to use water or a solvent containing water as a main component as a dispersion medium from the viewpoint of reducing environmental load when industrially used.

<Polymer electrolyte concentration>
0.1-10 weight% is suitable for the polymer electrolyte used for the polymer electrolyte emulsion of this invention with respect to this polymer electrolyte emulsion total weight. More preferably, it is 0.5-5 weight%, More preferably, it is 1-2 weight%. If the content of the polymer electrolyte with respect to the total weight of the polymer electrolyte emulsion is in the above range, it is efficient because a large amount of solvent is not required to form a film, and it is preferable because it is excellent in coatability.

<Zeta potential regulator>
In order to adjust the zeta potential of the polymer electrolyte emulsion of the present invention, it can be controlled within a suitable range depending on the type of polyelectrolyte forming the polymer electrolyte particles, the additive, and the type of dispersion medium as described above. As a simpler method, there is a method using a zeta potential adjusting agent. To adjust the zeta potential, there are a method of changing the pH of the emulsion and a method of controlling the ionic strength or dielectric constant of the dispersion medium, and these methods may be appropriately combined. A method using such a zeta potential regulator is preferable from the viewpoint of easy operation.
For example, the zeta potential can be adjusted by utilizing the fact that the zeta potential decreases as the pH increases. Such pH can be adjusted using an acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, or an alkali such as sodium hydroxide or calcium hydroxide.
Further, the zeta potential can be adjusted by utilizing the fact that the zeta potential decreases as the ionic strength increases. In order to adjust the ionic strength, inorganic salts such as sodium chloride, potassium chloride, and aluminum nitrate can be used.
Further, the zeta potential can be adjusted by utilizing the fact that the zeta potential decreases as the relative dielectric constant of the solvent as the dispersion medium decreases. The relative dielectric constant of such a solvent is, for example, a ratio described in known literature such as a solvent handbook (Shozo Asahara / Jinichiro Tokura / Shin Okawara / Yoshio Kumano / Gaku Seno, Kodansha, published in 1976). The dielectric constant can be selected. In addition, since the relative permittivity is additive, the relative permittivity of the dispersion medium itself can be easily obtained from the type of solvent contained in the dispersion medium and the relative permittivity thereof. Among them, preferred solvents include formamide (dielectric constant: 111), dimethyl sulfoxide (dielectric constant: 49), N-methyl-2-pyrrolidone (dielectric constant: 32), and methyl alcohol (dielectric constant: 33). , Water (relative dielectric constant: 78) and the like can be appropriately mixed and adjusted.
In the above, “the zeta potential is reduced” means that the potential difference at the interface between the polymer electrolyte particles and the dispersion medium is reduced in the polymer electrolyte emulsion of the present invention.

<Emulsifier>
The polymer electrolyte emulsion of the present invention improves the adhesion of the resulting coating to the substrate and its water resistance by adjusting the zeta potential as described above. In order to further improve the dispersion stability of the particles, an emulsifier may be added. Examples of the emulsifier include commonly used surfactants. Here, examples of the surfactant include anionic surfactants such as alkyl sulfate ester (salt), alkylaryl sulfate ester (salt), alkyl phosphate ester (salt), and fatty acid (salt); alkylamine salt, alkyl Cationic surfactants such as quaternary amine salts; Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers and block-type polyethers; Carboxylic acid types (for example, amino acid types, betaineic acid types, etc.) ) And amphoteric surfactants such as sulfonic acid type. Laterum S-180A (manufactured by Kao Corporation), Eleminol JS-2 (manufactured by Sanyo Chemical Co., Ltd.), Aqualon HS-10, KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE-10N, SR-10 Reactive emulsifiers available from the market such as [Asahi Denka Kogyo Co., Ltd.] and Antox MS-60 [Nihon Emulsifier Co., Ltd.] can also be used.

  Furthermore, among polymers having a hydrophilic group, those which are soluble in the dispersion medium in the polymer electrolyte emulsion and have a dispersion function can be used as an emulsifier. Examples of such polymers include styrene / maleic acid copolymer, styrene / acrylic acid copolymer, polyvinyl alcohol, polyalkylene glycol, sulfonated polyisoprene, sulfonated hydrogenated styrene / butadiene copolymer, styrene / Examples thereof include sulfonated products of maleic acid copolymers and sulfonated products of styrene / acrylic acid copolymers. Among these, those that can be dissolved in the used dispersion medium can be selected and used as an emulsifier. In particular, by using a polymer having a sulfonic acid group as it is in the acid form, the volume resistance when used as a proton conductor can be reduced. Examples of such a polymer include a sulfonated product of polyisoprene, a sulfonated product of hydrogenated styrene / butadiene copolymer, a sulfonated product of styrene / maleic acid copolymer, and a sulfonated product of styrene / acrylic acid copolymer. Can do.

  These emulsifiers can be used alone or in combination of two or more. When using an emulsifier, 0.1-50 weight part of emulsifier is normally used with respect to 100 weight part of polymer electrolyte emulsions. The amount of the emulsifier used is preferably 0.2 to 20 parts by weight, more preferably 0.5 to 5 parts by weight. When the amount of the emulsifier used is within this range, it is preferable because the dispersion stability of the polymer electrolyte emulsion is improved and the operability such as suppression of foaming is improved.

<Film forming method>
The polymer electrolyte emulsion of the present invention can be applied to various uses such as a coating material, a binder resin, a polymer solid electrolyte membrane and the like, particularly used in the form of a coating film or a film. Moreover, when using for such a use, in order to improve a physical property etc., another polymer can also be used together. Examples of other polymers include known resins such as urethane resins, acrylic resins, polyester resins, polyamide resins, polyethers, polystyrenes, polyester amides, polycarbonates, polyvinyl chloride, and diene polymers such as SBR and NBR. In particular, when the polymer electrolyte emulsion of the present invention is used as a binder resin for a catalyst layer of a solid polymer fuel cell, it exhibits a high degree of adhesion between the catalyst layer and an ion conductive membrane in contact therewith.

  In addition, the polymer electrolyte emulsion of the present invention can obtain a highly accurate film by various film forming methods. As the film forming method, for example, cast film forming, spray coating, brush coating, roll coater, flow coater, bar coater, dip coater and the like can be used. The coating film thickness varies depending on the use, but is usually a dry film thickness of 0.01 to 1,000 μm, preferably 0.05 to 500 μm.

The substrate to be applied is, for example, a substrate made of a polymer material such as polycarbonate resin, acrylic resin, ABS resin, polyester resin, polyethylene, polypropylene, nylon, a substrate made of non-ferrous metal such as aluminum, copper, duralumin, Examples thereof include steel plates such as stainless steel and iron, carbon materials, alumina, base materials made of inorganic hardened bodies, glass plates, wood, paper, and plaster plates. There is no restriction | limiting in particular in the shape of a base material, Porous materials, such as a nonwoven fabric etc. from a planar thing, can be used.
In addition, when forming a catalyst layer of a solid polymer fuel cell using the polymer electrolyte emulsion, a catalyst ink using the polymer electrolyte emulsion is applied to the ion conductive membrane, A catalyst layer can be formed. The catalyst ink is a term widely used in the art and means a liquid composition for forming a catalyst layer. The catalyst ink is prepared by adding a noble metal such as platinum or a platinum-ruthenium alloy or a complex electrode catalyst to the polymer electrolyte emulsion of the present invention. , 103-112, Kyoritsu Shuppan, published on Nov. 10, 2005), or a composite of the catalyst component and a conductive material such as carbon. be able to.

In addition, the polymer electrolyte emulsion of the present invention uses the above-exemplified base material as a support base material, and after coating and drying the support base material, the film obtained by peeling from the support base material is solid. It can also be used as an ion conductive membrane of a polymer fuel cell.
Or it can use suitably also as a base-material modifier and an adhesive agent which apply | coat and use on the surface of the various base material illustrated above.

<Description of membrane electrode assembly>
Among the uses provided by the polymer electrolyte emulsion of the present invention described above, the membrane electrode assembly (hereinafter referred to as “MEA”) that constitutes a polymer electrolyte fuel cell, particularly a use as a particularly suitable fuel cell member. Details will be described with regard to the use related to the above.
Here, MEA is formed by forming electrodes called catalyst layers containing a catalyst component that promotes a redox reaction between hydrogen and air on both surfaces of an ion conductive membrane. Furthermore, a form having a gas diffusion layer for efficiently supplying gas to the catalyst layer outside both catalyst layers of the MEA may be referred to as a membrane electrode gas diffusion layer assembly (MEGA).

  The MEA is a method in which a catalyst layer is directly formed on an ion conductive film, a method in which a catalyst layer is formed on a flat support substrate, and this is transferred to the ion conductive membrane, and then the support substrate is peeled off. It is manufactured using. Moreover, after forming a catalyst layer on a base material to be a gas diffusion layer such as carbon paper, the catalyst layer may be bonded to an ion conductive film to form MEGA.

The polymer electrolyte emulsion of the present invention is used for members such as catalyst layers or ion conductive membranes, primers and binder resins used as additives for such members, and catalyst layer-ion conductive membranes, which constitute such MEAs. It can be applied to the adhesive used.
In particular, the polymer electrolyte emulsion of the present invention is preferably applied to the catalyst layer among the constituent members of the MEA.
As a more preferred embodiment, a catalyst layer (electrode) is formed on the ion conductive membrane by applying and drying a catalyst ink containing the polymer electrolyte emulsion of the present invention and platinum-supported carbon on the ion conductive membrane. When the MEA is formed by forming the MEA, the obtained MEA is excellent in the adhesive strength between the electrode and the ion conductive membrane, and the electrode is excellent in water resistance (durability). Alternatively, the MEA is formed by applying the polymer electrolyte emulsion of the present invention on the ion conductive membrane and placing platinum-supported carbon particles on the emulsion coating film before drying the obtained emulsion coating film. This MEA is excellent in the adhesive strength between the electrode and the ion conductive membrane, and the electrode is excellent in durability.
In addition, when the MEA catalyst layer and the gas diffusion layer are joined, the MEGA having excellent adhesion and water resistance can be obtained by using the polymer electrolyte emulsion of the present invention as an adhesive.

  Next, a fuel cell provided with MEA obtained by the polymer electrolyte emulsion of the present invention will be described.

FIG. 1 is a diagram schematically showing a cross-sectional configuration of a fuel cell according to a preferred embodiment. As shown in FIG. 1, the fuel cell 10 has catalyst layers 14a and 14b sandwiching the ion conductive membrane 12 on both sides, and this is the MEA 20 obtained by the manufacturing method of the present invention. Furthermore, the catalyst layers on both sides are provided with gas diffusion layers 16a and 16b, respectively, and separators 18a and 18b are formed in the gas diffusion layers.
Here, the one provided with MEA 20 and gas diffusion layers 16a and 16b is generally abbreviated as MEGA.

  Here, the catalyst layers 14a and 14b are layers that function as electrode layers in the fuel cell, and either one of them serves as an anode catalyst layer and the other serves as a cathode catalyst layer.

  The gas diffusion layers 16a and 16b are provided so as to sandwich both sides of the MEA 20, and promote the diffusion of the raw material gas into the catalyst layers 14a and 14b. The gas diffusion layers 16a and 16b are preferably made of a porous material having electron conductivity. For example, a porous carbon non-woven fabric or carbon paper is preferable because the raw material gas can be efficiently transported to the catalyst layers 14a and 14b.

  Separator 18a, 18b is formed with the material which has electronic conductivity, As this material, carbon, resin mold carbon, titanium, stainless steel etc. are mentioned, for example. Although not shown, the separators 18a and 18b are preferably provided with a groove serving as a flow path for fuel gas or the like on the catalyst layers 14a and 14b side.

  The fuel cell 10 can be obtained by sandwiching MEGA as described above between a pair of separators 18a and 18b and joining them together.

  The fuel cell of the present invention is not necessarily limited to the above-described configuration, and may have a different configuration as long as it does not depart from the spirit of the fuel cell.

  The fuel cell 10 may be one having the above-described structure sealed with a gas seal body or the like. Furthermore, a plurality of the fuel cells 10 having the above structure can be connected in series to be put to practical use as a fuel cell stack. The fuel cell having such a configuration can operate as a solid polymer fuel cell when the fuel is hydrogen, and as a direct methanol fuel cell when the fuel is an aqueous methanol solution.

<Other uses>
In addition, the polymer electrolyte emulsion of the present invention can be expressed or maintained in hydrophilicity and hygroscopicity by coating on various hydrophobic surfaces. In addition, it is possible to prevent dirt and dust due to static electricity. Further, when coated on a porous material such as a non-woven fabric, it exhibits an action of capturing weak bases such as ammonia and amines present in air or water, or ionic substances. In addition, by coating the surface of the battery separator, it is possible to expect an effect that the affinity with the battery electrolyte is improved and the battery characteristics such as self-discharge characteristics are improved.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

<Measurement method of ion exchange capacity>
The polymer electrolyte to be measured was processed into a film form by a solvent casting method, and the dry weight was determined using a halogen moisture meter set at a heating temperature of 105 ° C. Next, this membrane was immersed in 5 mL of a 0.1 mol / L sodium hydroxide aqueous solution, and then 50 mL of ion-exchanged water was added and left for 2 hours. Thereafter, titration was performed by gradually adding 0.1 mol / L hydrochloric acid to the solution in which the membrane was immersed, and the neutralization point was determined. The ion exchange capacity (unit: meq / g) of the polymer electrolyte was calculated from the dry weight of the membrane and the amount of hydrochloric acid required for the neutralization.

<Measurement method of weight average molecular weight>
The weight average molecular weight in terms of polystyrene was determined by gel permeation chromatography (GPC). The measurement conditions for GPC are as follows.
GPC conditions and GPC measurement device HLC-8220 manufactured by TOSOH
・ Two columns AT-80M made by Shodex are connected in series ・ Column temperature 40 ℃
Mobile phase solvent Dimethylacetamide (LiBr added to 10 mmol / dm ³ )
・ Solvent flow rate 0.5mL / min

<Average particle size measurement method>
The average particle size of the particles contained in each emulsion was measured using a dynamic light scattering method (concentrated particle size analyzer FPAR-1000 [manufactured by Otsuka Electronics]). The measurement temperature is 30 ° C., the integration time is 30 minutes, and the wavelength of the laser used for the measurement is 660 nm. The obtained data is analyzed by the CONTIN method by using the analysis software (FPAR system VERSION 5.1.7.2) attached to the above apparatus, and the scattering intensity distribution is obtained. did.

<Zeta potential measurement method>
The electrophoretic mobility was measured by the laser Doppler method, and the zeta potential of the polymer electrolyte emulsion was determined from the dielectric constant and viscosity of the dispersion medium of the polymer electrolyte emulsion. The measurement conditions of the laser Doppler method are as follows.
Laser Doppler Method Measurement Conditions / Laser Doppler Measuring Device Zetasizer Nano by Malvern Instruments Ltd
・ Laser wavelength 632nm
・ Temperature 25 ℃
・ Capillary cell ・ Accumulation times 20 times

<PH measurement method>
The pH was measured to determine the pH of the polymer electrolyte emulsion. The measurement conditions for pH measurement are as follows.
Measurement conditions and pH meter TPX-90i manufactured by TOKO Chemical
・ PH electrode PCE103CS-SR manufactured by TOKO Chemical
・ Measurement temperature 25 ℃
・ PH calibration point pH = 4,7

Production Example 1 [Synthesis of dipotassium 4,4′-difluorodiphenylsulfone-3,3′-disulfonate]
To a reactor equipped with a stirrer, 467 g of 4,4′-difluorodiphenylsulfone and 3500 g of 30% fuming sulfuric acid were added and reacted at 100 ° C. for 5 hours. The obtained reaction mixture was cooled and then added to a large amount of ice water, and 470 mL of a 50% aqueous potassium hydroxide solution was further added dropwise thereto.
Next, the precipitated solid was collected by filtration, washed with ethanol, and dried. The obtained solid was dissolved in 6.0 L of deionized water, 50% aqueous potassium hydroxide solution was added to adjust the pH to 7.5, and then 460 g of potassium chloride was added. The precipitated solid was collected by filtration, washed with ethanol, and dried.
Thereafter, the obtained solid was dissolved in 2.9 L of dimethyl sulfoxide (hereinafter referred to as “DMSO”), insoluble inorganic salts were removed by filtration, and the residue was further washed with 300 mL of DMSO. To the obtained filtrate, 6.0 L of a solution of ethyl acetate / ethanol = 24/1 was added dropwise, and the precipitated solid was washed with methanol, dried at 100 ° C., and 4,4′-difluorodiphenylsulfone-3,3. 482 g of dipotassium dipotassium disulfonate was obtained.

Production Example 2 [Production of polymer electrolyte A]
(Synthesis of polymer compound having sulfonic acid group)
In a flask equipped with an azeotropic distillation apparatus, 9.32 parts by weight of dipotassium 4,4′-difluorodiphenylsulfone-3,3′-disulfonate obtained in Production Example 1 in an argon atmosphere, 2,5-dihydroxybenzene 4.20 parts by weight of potassium sulfonate, 59.6 parts by weight of DMSO, and 9.00 parts by weight of toluene were added, and argon gas was bubbled for 1 hour while stirring these at room temperature.
Thereafter, 2.67 parts by weight of potassium carbonate was added to the obtained mixture, and azeotropic dehydration was performed by heating and stirring at 140 ° C. Thereafter, heating was continued while distilling off toluene, and a DMSO solution of a polymer compound having a sulfonic acid group was obtained. Total heating time was 14 hours. The resulting solution was allowed to cool at room temperature.

(Synthesis of polymer compounds substantially free of ion exchange groups)
In a flask equipped with an azeotropic distillation apparatus, in an argon atmosphere, 8.32 parts by weight of 4,4′-difluorodiphenylsulfone, 5.36 parts by weight of 2,6-dihydroxynaphthalene, 30.2 parts by weight of DMSO, N-methyl- 20.2 parts by weight of 2-pyrrolidone (hereinafter referred to as “NMP”) and 9.81 parts by weight of toluene were added, and argon gas was bubbled for 1 hour while stirring at room temperature.
Thereafter, 5.09 parts by weight of potassium carbonate was added to the obtained mixture, and azeotropic dehydration was performed by heating and stirring at 140 ° C. Thereafter, heating was continued while toluene was distilled off. Total heating time was 5 hours. The resulting solution was allowed to cool at room temperature to obtain a NMP / DMSO mixed solution of a polymer compound substantially free of ion exchange groups.

得られた高分子電解質Ａのイオン交換容量は１．９ｍｅｑ／ｇであり、重量平均分子量は、４．２×１０⁵であった。なお、ｍ、ｎは各ブロックを構成する括弧内の繰返し単位の平均重合度を表すものである。 (Synthesis of block copolymer)
While stirring the obtained NMP / DMSO mixed solution of the polymer compound having substantially no ion exchange group, the total amount of the DMSO solution of the polymer compound having the sulfonic acid group and 80.4 parts by weight of NMP were added thereto. DMSO (45.3 parts by weight) was added, and a block copolymerization reaction was carried out at 150 ° C. for 40 hours.
The reaction solution after completion of the reaction was dropped into a large amount of 2N hydrochloric acid and immersed for 1 hour. Thereafter, the produced precipitate was filtered off and then immersed again in 2N hydrochloric acid for 1 hour. The obtained precipitate was filtered and washed with water, and then immersed in a large amount of hot water at 95 ° C. for 1 hour. And after separating by filtration, the obtained cake was dried at 80 degreeC for 12 hours, and the polymer electrolyte A which is a block copolymer was obtained. The structure of this polymer electrolyte A is shown below.
In addition, description of "block" in a following formula represents having at least one block each having a sulfonic acid group and no block having an ion exchange group.

The obtained polymer electrolyte A had an ion exchange capacity of 1.9 meq / g and a weight average molecular weight of 4.2 × 10 ⁵ . Here, m and n represent the average degree of polymerization of the repeating units in parentheses constituting each block.

（住友化学製スミカエクセルＰＥＳ５２００Ｐ、Ｍｎ＝５．４×１０⁴、Ｍｗ＝１．２×１０⁵）１０．０ｇ、２，２’−ビピリジル４３．８ｇ(２８０．２ｍｍｏｌ)を入れて攪拌した。その後バス温を１５０℃まで昇温し、トルエンを加熱留去することで系内の水分を共沸脱水した後、６０℃に冷却した。次いで、これにビス（１，５−シクロオクタジエン）ニッケル（０）７３．４ｇ(２６６．９ｍｍｏｌ)を加え、８０℃に昇温し、同温度で５時間攪拌した。放冷後、反応液を大量の６ｍｏｌ／Ｌの塩酸に注ぐことによりポリマーを析出させ濾別。その後６ｍｏｌ／Ｌ塩酸による洗浄・ろ過操作を数回繰り返した後、濾液が中性になるまで水洗を行い、減圧乾燥することにより目的とする下記ポリアリーレン系ブロック共重合体である高分子電解質Ｂ １６．３ｇを得た。この高分子電解質Ｂの構造を下記に示す。

得られた高分子電解質Ｂのイオン交換容量は２．３ｍｅｑ／ｇであり、重量平均分子量は、２．７×１０⁵であった。なお、ｌ、ｐは各ブロックを構成する括弧内の繰返し単位の平均重合度を表すものである。 Production Example 2 [Production of polymer electrolyte B]
In a flask equipped with an azeotropic distillation apparatus under an argon atmosphere, DMSO 600 ml, toluene 200 mL, sodium 2,5-dichlorobenzenesulfonate 26.5 g (106.3 mmol), the following polyethersulfone which is terminal chloro type

(Sumitomo Chemical Sumika Excel PES5200P, Mn = 5.4 × 10 ⁴ , Mw = 1.2 × 10 ⁵ ) 10.0 g, 2,2′-bipyridyl 43.8 g (280.2 mmol) was added and stirred. Thereafter, the bath temperature was raised to 150 ° C., and water in the system was azeotropically dehydrated by distilling off toluene, followed by cooling to 60 ° C. Next, 73.4 g (266.9 mmol) of bis (1,5-cyclooctadiene) nickel (0) was added thereto, the temperature was raised to 80 ° C., and the mixture was stirred at the same temperature for 5 hours. After allowing to cool, the reaction solution is poured into a large amount of 6 mol / L hydrochloric acid to precipitate a polymer, which is filtered off. Thereafter, washing and filtration operations with 6 mol / L hydrochloric acid were repeated several times, followed by washing with water until the filtrate became neutral, and drying under reduced pressure, thereby polymer electrolyte B, which is the desired polyarylene block copolymer shown below. 16.3 g was obtained. The structure of this polymer electrolyte B is shown below.

The obtained polymer electrolyte B had an ion exchange capacity of 2.3 meq / g and a weight average molecular weight of 2.7 × 10 ⁵ . Note that l and p represent the average degree of polymerization of the repeating units in parentheses constituting each block.

得られた高分子電解質Ｃの重量平均分子量は１．３９×１０⁵であった。なお、ｒ、ｓは各ブロックを構成する括弧内の繰返し単位の平均重合度を表すものである。 Production Example 3 [Production of polymer electrolyte C]
4,4′-difluorodiphenylsulfone-3,3′-disulfonate dipotassium 7.74 g (15.77 mmol), potassium 2,5-dihydroxybenzenesulfonate 3.00 g (13.14 mmol) potassium carbonate 1.91 g (13 .80 mmol) and DMSO 49 mL and toluene 35 mL were added. Thereafter, toluene was distilled off by heating at a bath temperature of 150 ° C. for 2 hours to azeotropically dehydrate the water in the system, and then oligomers a were obtained by stirring for 4 hours while maintaining the temperature. The average repeating degree s of oligomer a calculated from the charged value was 5.5.
Separately, in a flask equipped with an azeotropic distillation apparatus, under an argon atmosphere, 8.25 g (40.78 mmol) of 4,4′-dihydroxydiphenyl ether, 9.70 g (38.16 mmol) of 4,4′-difluorodiphenyl sulfone, 6.20 g (44.86 mmol) of potassium carbonate was added, and 82 mL of DMSO and 35 mL of toluene were added. Thereafter, toluene was distilled off by heating at a bath temperature of 150 ° C. for 2 hours to azeotropically dehydrate the water in the system, and then the mixture was stirred while keeping for 4 hours to obtain oligomer b. The average repeating degree r of the oligomer b calculated from the charged value was 15.0.
Subsequently, after the reaction solution was sufficiently allowed to cool to room temperature, the reaction solution of oligomer a was dropped into the reaction solution of oligomer b, and the reaction mass of oligomer a was thoroughly washed with 20 mL of DMSO, and then the internal temperature was 150 ° C. And kept stirring for 9 hours. The reaction solution was allowed to cool and then added dropwise to a large amount of hydrochloric acid, and the resulting precipitate was collected by filtration. Further, washing and filtration were repeated with water until the washing solution became neutral, then treated with hot water at 80 ° C., and then dried at normal pressure at 80 ° C. to obtain 23.51 g of polymer electrolyte C. The structure of this polymer electrolyte C is shown below.

The weight average molecular weight of the obtained polymer electrolyte C was 1.39 × 10 ⁵ . R and s represent the average degree of polymerization of the repeating units in parentheses constituting each block.

Production Example 4 [Synthesis of Stabilizer Polymer d]
Synthesis of polymer a A 2 L separable flask equipped with a reduced pressure azeotropic distillation apparatus was purged with nitrogen, and 63.40 g of bis-4-hydroxydiphenyl sulfone, 70.81 g of 4,4′-dihydroxybiphenyl, and 955 g of N-methyl 2-pyrrolidone. Was added to obtain a uniform solution. Thereafter, 92.80 g of potassium carbonate was added, and dehydrated under reduced pressure at 135 ° C. to 150 ° C. for 4.5 hours while distilling off NMP. Thereafter, 200.10 g of dichlorodiphenylsulfone was added and the reaction was carried out at 180 ° C. for 21 hours.
After completion of the reaction, the reaction solution was added dropwise to methanol, and the precipitated solid was filtered and collected. The recovered solid was further washed with methanol, washed with water, and washed with hot methanol and dried to obtain 275.55 g of polymer a. The structure of this polymer a is shown below. The polymer a had a polystyrene-equivalent weight average molecular weight by GPC measurement of 18000, and the ratio of k and l determined from the integral value of NMR measurement was k: l = 7: 3. In addition, the following "random" description shows that the structural unit which forms the following polymer a is copolymerized at random. Here, k and q represent the average degree of polymerization of the repeating units in the parentheses constituting this random polymer.

Synthesis of Polymer b The 2 L separable flask was purged with nitrogen, and 101.12 g of nitrobenzene and 80.00 g of polymer a were added to obtain a uniform solution. Thereafter, 50.25 g of N-bromosuccinimide was added and cooled to 15 ° C. Subsequently, 106.42 g of 95% concentrated sulfuric acid was added dropwise over 40 minutes, and the reaction was carried out at 15 ° C. for 6 hours. Six hours later, 450.63 g of a 10 w% aqueous sodium hydroxide solution and 18.36 g of sodium thiosulfate were added while cooling to 15 ° C. Thereafter, this solution was added dropwise to methanol, and the precipitated solid was collected by filtration. The recovered solid was washed with methanol, washed with water, washed again with methanol and dried to obtain 86.38 g of polymer b.

Synthesis of Polymer c A 2 L separable flask equipped with a reduced-pressure azeotropic distillation apparatus was purged with nitrogen, and 116.99 g of dimethylformamide and 80.07 g of polymer b were added to obtain a uniform solution. Thereafter, dehydration under reduced pressure was performed for 5 hours while distilling off dimethylformamide. After 5 hours, the mixture was cooled to 50 ° C., 41.87 g of nickel chloride was added, the temperature was raised to 130 ° C., and 69.67 g of triethyl phosphite was added dropwise, and the reaction was carried out at 140 ° C. to 145 ° C. for 2 hours. After 2 hours, an additional 17.30 g of triethyl phosphite was added, and the reaction was carried out at 145 ° C. to 150 ° C. for 3 hours. After 3 hours, the mixture was cooled to room temperature, a mixed solution of 1161 g of water and 929 g of ethanol was added dropwise, and the precipitated solid was filtered and collected. Water was added to the collected solid and sufficiently pulverized, washed with a 5% by weight aqueous hydrochloric acid solution and washed with water to obtain 86.83 g of polymer c.

Synthesis of Polymer d A 5 L separable flask was purged with nitrogen, and 1200 g of 35 wt% hydrochloric acid aqueous solution, 550 g of water and 75.00 g of polymer c were added, and the mixture was stirred at 105 ° C. to 110 ° C. for 15 hours. After 15 hours, the mixture was cooled to room temperature and 1500 g of water was added dropwise. Thereafter, the solid in the system was filtered and collected, and the obtained solid was washed with water and hot water. After drying, 72.51 g of the target polymer d (the following formula) was obtained. The phosphorus content determined from elemental analysis was 5.91%, and the value of x calculated from this elemental analysis value was 1.6 (where x is a phosphonic acid group per biphenylyleneoxy group). Represents the number of This polymer d was used as a stabilizer.

Production Example 5 [Production of Ion Conductive Membrane A]
The polymer electrolyte A obtained in Production Example 1 was dissolved in NMP (N-methyl-2-pyrrolidone) to a concentration of 13.5% by weight to prepare a polymer electrolyte solution. Next, this polymer electrolyte solution was dropped on a glass plate. Then, the polymer electrolyte solution was uniformly spread on the glass plate using a wire coater. At this time, the coating thickness was controlled using a wire coater having a 0.25 mm clearance. After application, the polymer electrolyte solution was dried at 80 ° C. under normal pressure. Then, the obtained membrane was immersed in 1 mol / L hydrochloric acid, washed with ion-exchanged water, and dried at room temperature to obtain an ion conductive membrane A having a thickness of 30 μm.

Example 1 [Preparation of Emulsion 1]
0.9 g of the polymer electrolyte B obtained in Production Example 2 and 0.1 g of the stabilizer obtained in Production Example 4 were dissolved in 99 g of NMP to produce 100 g of a polymer electrolyte solution. Next, 100 g of this polymer electrolyte solution was dropped into 900 g of distilled water at a dropping rate of 3 to 5 g / min to dilute the polymer electrolyte solution. The diluted solution was dialyzed with running water for 72 hours using a cellulose tube for dialysis membrane dialysis (UC36-32-100 manufactured by Sanko Junyaku Co., Ltd .: molecular weight cut off 14,000). The polymer electrolyte solution after dialysis was concentrated using an evaporator so that the polymer electrolyte particle concentration was 1.5% by weight. Further, the concentrated polymer electrolyte solution was diluted 3 times by weight with isopropyl alcohol to prepare Emulsion 1.
The zeta potential of this emulsion 1 was −240 mV, and the average particle size of the polymer electrolyte particles in the emulsion 1 was 350 nm.
Using the resulting emulsion 1, the following adhesion test and water resistance test were conducted. The results are shown in Table 1.

(Adhesion test)
The ion conductive film A obtained in Production Example 5 was used as a base material for an adhesion test. The obtained emulsion 1 was used as an adhesive between a substrate for adhesion test and an aluminum plate (1 mm). The substrate for adhesion test was cut into a strip shape having a width of 20 mm and a length of 50 mm, and the emulsion 1 was adhered to an aluminum plate as an adhesive with a length of 20 mm as a margin. The amount of emulsion 1 used is approximately 100 μL. After drying at 80 ° C. for 10 minutes, peeling was performed with an autograph AGS-500 manufactured by Shimadzu Corporation at a peeling speed of 300 mm / min and a peeling angle of 90 degrees, and the peeling load at that time was determined. The larger the peel load, the stronger the adhesion.

(Water resistance test)
The ion conductive membrane A obtained in Production Example 5 was used as a base material for a water resistance test. Emulsion 1 was spread evenly on a substrate for water resistance test using a bar coater. At this time, the coating thickness was controlled as a 25 μm clearance. Immediately after application, platinum-supported carbon (SA50BK, manufactured by N.E. Chemcat) was sprinkled on the coating film at a weight of about 10 mg / cm ² and dried at 80 ° C. under normal pressure. The obtained coating film is a coating film in which the emulsion 1 and platinum-supported carbon are combined. After drying, compressed air was blown from the nozzle to remove excess platinum-carrying carbon. The basis weight of the platinum-supported carbon after the removal was about 5 mg / cm ² .
The water resistance of the coating film was evaluated by dropping running water onto the coating film and determining the area ratio of the coating film removed by the water flow. The flowing water was discharged from a water pipe having a pipe diameter of 10 mm and dropped at a speed of 20 ml / sec from a position with a height of 100 mm, and the state of the coating after 1 minute was examined. The higher the water resistance, the smaller the area ratio removed by running water. That is, it means that the area retention rate of the film is large.

Examples 2-5
Various emulsions having the zeta potential adjusted with an aqueous sodium hydroxide solution as shown in Table 1 were prepared for the emulsion 1 shown in Example 1, and an adhesion test and a water resistance test were conducted in the same manner as in Example 1. The results are shown in Table 1 together with the prepared zeta potential and average particle size.

Comparative Example 1
The emulsion 1 shown in Example 1 was prepared by adjusting the zeta potential outside the range of the present invention with an aqueous sodium hydroxide solution as shown in Table 1, and in the same manner as in Example 1, the adhesion test, water resistance A sex test was conducted. The results are shown in Table 1 together with the prepared zeta potential and average particle size.

Example 6 [Preparation of Emulsion 2]
Emulsion 2 was obtained in the same manner as in Example 1 except that the mixture of polymer electrolyte 2 and stabilizer used in Example 1 was replaced with polymer electrolyte 1 obtained in Production Example 1. Table 1 shows the zeta potential, average particle diameter, adhesion test results, and water resistance test results of this emulsion 2.

Examples 7 and 8
Various emulsions having the zeta potential adjusted with an aqueous sodium hydroxide solution as shown in Table 1 were prepared for the emulsion 2 shown in Example 6, and an adhesion test and a water resistance test were conducted in the same manner as in Example 1. The results are shown in Table 1 together with the prepared zeta potential and average particle size.

Comparative Examples 2 and 3
The emulsion 2 shown in Example 6 was prepared by adjusting the zeta potential outside the range of the present invention with an aqueous sodium hydroxide solution as shown in Table 1, and in the same manner as in Example 1, the adhesion test and the water resistance were made. A test was conducted. The results are shown in Table 1 together with the prepared zeta potential and average particle size.

Examples 9-11
Various emulsions having the zeta potential adjusted with NMP, DMSO (dimethyl sulfoxide) or DMF (dimethylformamide) as shown in Table 1 were prepared in the emulsion 1 shown in Example 1, and the adhesion test was performed in the same manner as in Example 1. A water resistance test was conducted. The results are shown in Table 1 together with the prepared zeta potential and average particle size.

Comparative Example 4
An adhesion test and a water resistance test were conducted in the same manner as in Example 1 except that a commercially available Nafion 5 wt% solution (manufactured by Aldrich) was used instead of the emulsion 1. The results are shown in Table 1.

(＊1)エマルション１００重量部に対する添加重量部

(* 1) parts by weight added to 100 parts by weight of emulsion

  As shown in Table 1, when the zeta potential is in the range of −50 mV to −300 mV, the adhesion of the obtained film is high. If the zeta potential is in the range of −50 mV to −150 mV, the obtained film has high water resistance. found.

It is a figure which shows typically the cross-sectional structure of the fuel cell which concerns on suitable embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 12 ... Ion conduction membrane, 14a, 14b ... Catalyst layer, 16a, 16b ... Gas diffusion layer, 18a, 18b ... Separator, 20 ... MEA

Claims (10)

  A polymer electrolyte emulsion in which polymer electrolyte particles are dispersed in a dispersion medium, wherein the zeta potential at a measurement temperature of 25 ° C. is in the range of −50 mV to −300 mV.   The polymer electrolyte emulsion according to claim 1, wherein the zeta potential is in the range of -50 mV to -150 mV.   A polymer electrolyte emulsion obtained by dispersing polymer electrolyte particles in a dispersion medium and using a zeta potential adjuster to adjust the zeta potential at a measurement temperature of 25 ° C. to a range of −50 mV to −300 mV.   The polymer electrolyte emulsion according to claim 3, obtained by setting the zeta potential in a range of -50 mV to -150 mV.   The polymer electrolyte emulsion according to any one of claims 1 to 4, wherein a volume average particle diameter determined by a dynamic light scattering method is 100 nm to 200 µm.   The polymer electrolyte emulsion according to any one of claims 1 to 5, which is used for an electrode of a solid polymer fuel cell.   The catalyst composition containing the polymer electrolyte emulsion in any one of Claims 1-6, and a catalyst component.   An electrode for a polymer electrolyte fuel cell comprising the catalyst composition according to claim 7.   A membrane electrode assembly having the polymer electrolyte fuel cell electrode according to claim 8.   A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 9.

Images