JP2007042593A - Solid electrolyte film and its manufacturing method, equipment, electrode membrane assembly, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a solid electrolyte film having an excellent ion conductivity by making a solid electrolyte into a film continuously by a solution film-forming method. <P>SOLUTION: A dope 24 containing a solid electrolyte and an organic solvent is made to flow and cast on a moving casting band 82 from a casting die 81. A first to a fourth fan ducts 91 to 94 are provided in order at the casting bands 82 in running direction of the casting band. Drying air 301 is sent to the air face 24b of the cast film 24a from the fan duct 91. Then, a skin layer 24c is produced on the air face 24b side of the cast film 24a after passing 60 seconds immediately after casting. The skin layer 24c has a different surface tension from the casting band 82 side of the cast film 24a. The cast film 24a after drying is separated as a film 62 and extended and dried. After drying in a tenter, the film 62 is sent to a drying chamber 69, and furthermore dried by supporting by a plurality of rollers 68. By producing the skin layer 24c in the cast film 24a, a solid electrolyte film 62 having excellent smoothness and flatness can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a solid electrolyte film, a method for producing the same, equipment, an electrode membrane composite using the solid electrolyte film, and a fuel cell, and in particular, a solid electrolyte film having proton conductivity and used in a fuel cell. In addition, the present invention relates to a manufacturing method and equipment thereof, an electrode membrane composite using a solid electrolyte film, and a fuel cell.

  In recent years, lithium ion batteries and fuel cells that can be used as a power source for portable devices and the like have been actively researched, and active research has also been conducted on solid electrolytes that are members thereof. The solid electrolyte is, for example, a lithium ion conductive material or a proton conductive material.

  Generally, there are film-like proton conductive materials, and a film-like solid electrolyte for use as a solid electrolyte layer of a battery such as a fuel cell and a method for producing the same have been proposed. For example, Patent Document 1 proposes a method of immersing a polyvinylidene fluoride resin in a liquid in which an electrolyte and a plasticizer are mixed. Patent Document 2 proposes a method for producing a proton conducting membrane by synthesizing an inorganic compound in a solution containing an aromatic polymer material having a sulfonic acid group and removing the solvent. Yes. In this method, silicon oxide, phosphoric acid derivatives and the like are added to improve pores. In Patent Document 3, a method for producing an ion exchange membrane by adding a metal oxide precursor to a solution containing an ion exchange resin, casting a liquid obtained by subjecting the precursor to hydrolysis and polycondensation reaction, and the like. Has been proposed. In Patent Document 4, a polymer film having proton conductivity is produced by a solution casting method, that is, a solution casting method, and this film is immersed in an organic compound aqueous solution that is soluble in water and has a boiling point of 100 ° C. or higher. Thus, a method of producing a proton conducting membrane by causing equilibrium swelling and evaporating water by heating has been proposed. In Patent Document 5, a method of obtaining a solid electrolyte membrane by dissolving a compound mainly composed of polybenzimidazole having an anionic ionic group in an alcohol solvent having a boiling point of 90 ° C. or higher containing tetraalkylammonium hydroxide. Has been proposed.

  By the way, as a method for forming a polymer into a film, there are a melt film forming method and a solution film forming method as well known. The former can produce a film without using a solvent, but there are problems that the polymer is modified by heating and impurities in the raw polymer remain in the film as they are. On the other hand, although the latter has problems in equipment such as solution production equipment and solvent recovery equipment, the temperature during heating may be low, and it is possible to remove impurities in the polymer in the solution production process. There is. Furthermore, the latter also has an advantage that a film excellent in flatness and smoothness can be produced as compared with the former film.

In Patent Document 6, as a method for producing a solid electrolyte film by a solution casting method, a solution containing an acidic group-containing polymer and a solvent is cast on a support to form a casting membrane. There has been proposed a method in which drying is performed by heating after drying at a temperature equal to or lower than a predetermined value.
JP-A-9-320617 JP 2001-307752 A JP 2002-231270 A JP 2004-79378 A JP 2004-131530 A JP 2005-232240 A

  However, in patent document 1, the solution casting method is denied and the problem that the impurities contained in the raw material remain in the film is not solved. The methods of Patent Documents 2 to 5 are all manufacturing methods on a small scale, and are not considered methods for mass production. And the method of patent document 2 has the problem that dispersion | distribution of the composite_body | complex which consists of a polymer and an inorganic compound is difficult. The method of Patent Document 3 has a problem that the film forming process is complicated. Patent Document 4 has a problem that pores are generated in a film when immersed in water and a uniform film cannot be obtained, and a method for solving this problem is not described. Further, although it is described that various kinds of solid electrolyte films can be produced by the solution casting method, there is no description of a specific method. Patent document 5 limits the raw material to be used, and does not describe that it can be manufactured using other materials having excellent performance.

  Further, according to the method proposed in Patent Document 6, since the drying time of the cast film is long, when it is applied to continuous production, (1) the length of the support is increased, or (2) the support is It is necessary to select one of the methods for keeping the traveling speed low. (1) leads to an increase in equipment size, and (2) lacks film production efficiency. Therefore, it can be said that this method is not suitable for continuous production.

  Accordingly, the present invention provides a solid electrolyte film having a constant quality and excellent ion conductivity by continuously forming a solid electrolyte into a film, a manufacturing method and equipment therefor, an electrode membrane composite using the solid electrolyte film, and a fuel cell The purpose is to provide.

（ただし、ＸはＨ、ＹはＳＯ_２ 、Ｚは化４の（Ｉ）または（II）に示す構造であり、ｎとｍとは０．１≦ｎ／（ｍ＋ｎ）≦０．５を満たす。）

（１１）固体電解質と有機溶媒とを含むドープを、走行する支持体上に流延ダイから流延して流延膜を形成する流延装置と、前記流延膜のエアー面側を乾燥し、流延直後から６０秒経過後の前記流延膜の前記エアー面側に、前記支持体側とは異なる表面張力をもつスキン層を生成させる第１乾燥装置と、前記有機溶媒を含んだ状態の固体電解質フィルムとして前記流延膜を前記支持体から剥がす剥離装置と、前記固体電解質フィルムを乾燥する第２乾燥装置と、を有することを特徴とする溶液製膜設備。
（１２）上記（１）〜（１１）項記載の固体電解質フィルムの製造方法により製造されることを特徴とする固体電解質フィルム。
（１３）上記（１２）記載の固体電解質フィルムと、前記固体電解質フィルムの一方の面に密着して備えられ、外部から供給される水素含有物質からプロトンを発生するためのアノード電極と、前記固体電解質フィルムの他方の面に密着して備えられ、前記固体電解質フィルムを通過した前記プロトンと外部から供給される気体とから水を合成するカソード電極とを有することを特徴とする電極膜複合体。
（１４）上記１３項記載の電極膜複合体と、前記電極膜複合体の電極に接触して備えられ、前記アノード電極及び前記カソード電極と外部との電子の受け渡しをする集電体とを有することを特徴とする燃料電池。 In order to achieve the above object, the present invention has the following features.
(1) A casting process in which a casting film is formed by casting from a casting die on a support that runs a dope containing a solid electrolyte and an organic solvent, and a solid electrolyte film containing the organic solvent. A peeling step of peeling off the casting membrane from the support, and a drying step of drying the solid electrolyte film, drying the air surface side of the casting membrane, and after 60 seconds from immediately after casting, A method for producing a solid electrolyte film, wherein a skin layer having a surface tension different from that of the support side is formed on the air surface side of a cast film.
(2) In the drying step, the skin layer is generated by applying dry air having a wind speed of less than 3 m / sec to the air surface.
(3) A slit nozzle that emits the drying air from a slit provided opposite to the air surface, and a flow of air flowing out of the second opening from the first opening provided opposite to the air surface. The drying is performed by a chamber having either one of a two-dimensional nozzle that sucks air in the vicinity of the film.
(4) The drying is performed on the cast film having a residual solvent amount of 150% by weight to 500% by weight on a dry basis.
(5) The organic solvent is a mixture of a poor solvent and a good solvent for the solid electrolyte.
(6) The weight ratio of the poor solvent in the organic solvent is 10% or more and less than 100%.
(7) The good solvent contains dimethyl sulfoxide, and the poor solvent contains an alcohol having 1 to 5 carbon atoms.
(8) The solid electrolyte is a hydrocarbon polymer.
(9) The hydrocarbon polymer is an aromatic polymer having a sulfonic acid group.
(10) The aromatic polymer is a copolymer represented by the general formulas (I) to (III) of Chemical Formula 1.

(However, X is H, Y is SO ₂ , Z is the structure shown in Chemical Formula (I) or (II), and n and m satisfy 0.1 ≦ n / (m + n) ≦ 0.5. .)

(11) A casting apparatus for casting a dope containing a solid electrolyte and an organic solvent from a casting die on a traveling support to form a casting film, and drying the air surface side of the casting film. The first drying device for generating a skin layer having a surface tension different from that of the support on the air surface side of the cast film after 60 seconds from immediately after casting, and the organic solvent is included. A solution casting apparatus comprising: a peeling device that peels off the casting membrane from the support as a solid electrolyte film; and a second drying device that dries the solid electrolyte film.
(12) A solid electrolyte film produced by the method for producing a solid electrolyte film according to any one of (1) to (11) above.
(13) The solid electrolyte film according to (12), an anode electrode that is provided in close contact with one surface of the solid electrolyte film, and generates protons from a hydrogen-containing substance supplied from the outside, and the solid An electrode membrane composite comprising a cathode electrode that is provided in close contact with the other surface of the electrolyte film and synthesizes water from the proton that has passed through the solid electrolyte film and a gas supplied from the outside.
(14) The electrode membrane composite according to the above item 13, and a current collector that is provided in contact with the electrode of the electrode membrane composite and transfers electrons between the anode electrode and the cathode electrode and the outside. The fuel cell characterized by the above-mentioned.

  According to the present invention, a solid electrolyte film having a constant quality and excellent ion conductivity can be continuously produced. And when the electrode membrane composite using this solid electrolyte is used for a fuel cell, this fuel cell exhibits an excellent electromotive force. In particular, in the casting process, the air surface side of the casting film is dried and a skin layer having a surface tension different from that of the support is generated on the air surface side after 60 seconds from immediately after casting. In addition, a solid electrolyte film excellent in flatness can be obtained. In addition, by gradually drying the surface of the casting membrane to form a skin layer, the surface layer of the casting membrane becomes dense, and when a solid electrolyte film for a fuel cell is formed, crossover can be suppressed. it can.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described here. First, the solid electrolyte film of the present invention will be described, and then the method for producing the film will be described.

[material]
In the present invention, a polymer having a proton donating group is used as a solid electrolyte to be formed into a film by the production method described later. The polymer having a proton donating group is not particularly limited, and a polymer having an acid residue and known as a proton conducting material can be used. Among them, preferred polymers are those having an acid residue, for example, an addition polymerization polymer compound having a sulfonic acid in the side chain, a sulfonated poly (meth) acrylate having a side chain phosphate group, and a polyether ether ketone. Examples include polyether ether ketone, sulfonated polybenzimidazole, sulfonated polysulfone obtained by sulfonated polysulfone, and sulfonated products of heat-resistant aromatic polymer compounds. Examples of the addition polymerization polymer compound having a sulfonic acid in the side chain include perfluorosulfonic acid represented by Nafion (registered trademark), sulfonated styrene, sulfonated polyacrylonitrile styrene, sulfonated polyacrylonitrile butadiene styrene, and the like. Examples of the sulfonated product of the heat resistant aromatic polymer include sulfonated polyimide.

  Preferable examples of perfluorosulfonic acid include substances described in, for example, JP-A-4-366137, JP-A-6-231777, and JP-A-6-342665. Is particularly preferred. However, in Chemical formula 5, m is 100 to 10000, 200 to 5000 is preferable, and 500 to 2000 is more preferable. And n is 0.5-100, and 5-13.5 is especially preferable. X is substantially equivalent to m, and y is substantially equivalent to n.

  Preferred examples of the sulfonated styrene, the sulfonated polyacrylonitrile styrene, and the sulfonated polyacrylonitrile butadiene styrene include the compounds described in JP-A-5-174856 and JP-A-6-1111834, and the substances shown in Chemical formula 6. Can be mentioned.

  Examples of the sulfonated product of the heat-resistant aromatic polymer include, for example, JP-A-6-49302, JP-A-2004-10777, JP-A-2004-345997, JP-A-2005-15541, JP-A-2005-15541. JP 2002-110174 A, JP 2003-100317 A, JP 2003-55457 A, JP 9345818 A, JP 2003-257451 A, JP 2000-510511 A, JP 2002-105200 A. Substances described in the gazette can be mentioned, and among them, the substances shown in Chemical Formula 3 and Chemical Formulas 7 and 8 below are particularly preferable.

  In particular, the film of the substance shown in Chemical Formula 3 achieves both the hygroscopic expansion coefficient and the proton conductivity. When n / (m + n) <0.1, there are too few sulfonic acid groups, and proton conduction paths, so-called proton channels may not be sufficiently formed. Therefore, the obtained film may not exhibit proton conductivity sufficient for practical use. In addition, when n / (m + n)> 0.5, the water absorbability of the film becomes high, so that the expansion coefficient due to water absorption, that is, the water absorption expansion coefficient increases, and the film is likely to deteriorate.

  The sulfonation reaction in the process of obtaining the above compound can be performed according to various synthetic methods in known literature. As the sulfonating agent, sulfuric acid (concentrated sulfuric acid), fuming sulfuric acid, gaseous or liquid sulfur trisulfide, sulfur trisulfide complex, amidosulfuric acid, chlorosulfonic acid and the like can be used. As the solvent, hydrocarbons (benzene, toluene, nitrobenzene, chlorobenzene, dioxetane, etc.), alkyl halides (methylene chloride, chloroform, dichloroethane, carbon tetrachloride, etc.) and the like can be used. The reaction temperature may be determined in the range of −20 ° C. to 200 ° C. according to the activity of the sulfonating agent. As another method, a mercapto group, a disulfide group, and a sulfinic acid group can be introduced into the monomer in advance, and a sulfonated product can be synthesized by an oxidation reaction with an oxidizing agent. At this time, hydrogen peroxide, nitric acid, bromine water, hypochlorite, hypobromite, potassium permanganate, chromic acid, etc. can be used as the oxidizing agent, and water, acetic acid, Propionic acid or the like can be used. The reaction temperature in this method may be determined in the range of room temperature (for example, 25 ° C.) to 200 ° C. according to the activity of the oxidizing agent. As yet another method, a sulfonated compound may be synthesized by introducing a halogenoalkyl group into the monomer in advance and performing a substitution reaction with sulfite, bisulfite, or the like. In this case, water, alcohols, amides, sulfoxides, sulfones and the like can be used as the solvent. The reaction temperature may be determined in the range of room temperature (for example, 25 ° C.) to 200 ° C. In addition, the solvent in the above sulfonation reaction may be a mixture in which two or more kinds of substances are mixed.

In the reaction step to the sulfonated product, an alkyl sulfonating agent may be used. As a general method, there is a Friedel-Crafts reaction using sultone and AlCl ₃ (Journal of Applied Polymer Science, Vol. 36, 1753-1767, 1988). When an alkyl sulfonating agent is used to perform the Friedel-Crafts reaction, hydrocarbons (benzene, toluene, nitrobenzene, acetophenone, chlorobenzene, trichlorobenzene, etc.), alkyl halides (methylene chloride, chloroform, dichloroethane, Carbon chloride, trichloroethane, dichloroethane, tetrachloroethane, etc.) can be used. The reaction temperature may be determined in the range of room temperature to 200 ° C. Note that the solvent in the reaction may be a mixture of two or more substances.

  In the case of producing a solid electrolyte film having the structure of Chemical Formula 3, sulfonation may be performed in the film production process described later. That is, a film containing a precursor (hereinafter referred to as a precursor film) produced by producing a dope containing a polymer (hereinafter referred to as a precursor) in which X in Chemical Formula 3 is a cation species other than a proton. The precursor film is protonated to form a hydrogen atom (hereinafter referred to as H unless otherwise specified) to produce a solid electrolyte film made of a polymer having the structure of Chemical Formula 3. be able to.

  The cationic species means an atom or atomic group that generates a cation when ionized. This cationic species need not be monovalent. As cations other than protons, alkali metal cations, alkaline earth metal cations, and ammonium cations are preferable, and calcium ions, barium ions, quaternary ammonium ions, lithium ions, sodium ions, and potassium ions are more preferable. In addition, even if a film is produced by leaving X in Chemical Formula 3 as a cationic species without using H, the film has a function as a solid electrolyte. However, the proton conductivity increases as the proportion of X cationic species substituted with H increases. In that sense, X is particularly preferably H.

As solid electrolyte, what has the following various performance is preferable. The ionic conductivity is preferably 0.005 S / cm or more, and more preferably 0.01 S / cm or more, for example, at 25 ° C. and a relative humidity of 70%. Further, the ionic conductivity after being immersed in a 64% by weight aqueous methanol solution at 18 ° C. for one day is preferably 0.003 S / cm or more, more preferably 0.008 S / cm or more, particularly before immersion. What the fall rate of the ionic conductivity after immersion with respect to 20% or less is preferable. The methanol diffusion coefficient is preferably 4 × 10 ⁻⁷ cm ² / s or less, and particularly preferably 2 × 10 ⁻⁷ cm ² / s or less.

  As for strength, those having an elastic modulus of 10 MPa or more are preferred, and those having a modulus of 20 MPa or more are particularly preferred. The method for measuring the elastic modulus is described in detail in paragraph [0138] of JP-A-2005-104148, and the above value of the elastic modulus is a value obtained by a tensile tester manufactured by Toyo Baldwin. Therefore, when obtaining the elastic modulus using another test method or tester, it is preferable to obtain the correlation with the value obtained by the test method or tester in advance.

  As for durability, it is preferable that each change rate of weight, ion exchange capacity, and methanol diffusion coefficient is 20% or less before and after a time-lapse test immersed in a 64 wt% methanol aqueous solution at a constant temperature, and 15% The following are particularly preferred. Further, before and after the time-lapse test in hydrogen peroxide, the rate of change in weight, ion exchange capacity, and methanol diffusion coefficient is preferably 20% or less, and particularly preferably 10% or less. Further, in a 64 wt% methanol aqueous solution, the volume swelling rate at a constant temperature is preferably 10% or less, and particularly preferably 5% or less.

  Further, those having a stable water absorption and water content are preferred. Moreover, it is preferable that it is so small that solubility is substantially negligible with respect to alcohols, water, and a mixed solvent of alcohol and water. Further, it is preferable that the weight loss and the shape change when immersed in the liquid are small enough to be substantially ignored.

  The ionic conduction performance of the solid electrolyte film is expressed by a so-called index which is a ratio between the ionic conductivity and the methanol permeability coefficient. And it can be said that the larger the index in a certain direction, the higher the ion conduction performance in that direction. In the thickness direction of the solid electrolyte film, the ionic conductivity is proportional to the thickness, and the methanol permeability coefficient is inversely proportional to the thickness. Therefore, the ionic conductivity of the solid electrolyte film can be controlled by changing the thickness. In a solid electrolyte film used for a fuel cell, an anode electrode is provided on one side and a cathode electrode is provided on the other side. Therefore, the index in the thickness direction of the solid electrolyte film is larger than the index in the other direction. Is preferred. The thickness of the solid electrolyte film is preferably 10 to 300 μm. For example, in the case of a solid electrolyte having both high ionic conductivity and methanol diffusion coefficient, it is particularly preferable to produce a film having a thickness of 50 to 200 μm, and a solid having both low ionic conductivity and methanol diffusion coefficient. In the case of an electrolyte, it is particularly preferable to produce a film so that the thickness is 20 to 100 μm.

  The heat resistant temperature is preferably 200 ° C. or higher, more preferably 250 ° C. or higher, and particularly preferably 300 ° C. or higher. The heat-resistant temperature here means a temperature that reaches 5% weight loss when heated at a heating rate of 1 ° C./min. Note that this weight reduction is calculated excluding the amount of evaporation such as moisture.

Furthermore, when a solid electrolyte is used as a film for a fuel cell, the solid electrolyte is preferably a solid electrolyte having a maximum output density of 10 mW / cm ² or more.

  By using the above solid electrolyte, it is possible to produce a solution suitable for production of a film, and it is possible to produce a solid electrolyte film suitable for a fuel cell. The solution suitable for the production of the film is, for example, a solution having a relatively low viscosity and easily removing foreign matters by filtration. The obtained solution is referred to as a dope in the following description.

  The dope solvent may be an organic compound that can dissolve the polymer as the solid electrolyte. Examples include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, chlorobenzene, etc.), alcohols (eg, methanol, ethanol, n-propanol, n-butanol, diethylene glycol, etc.), Ketones (eg, acetone, methyl ethyl ketone, etc.), esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.), ethers (eg, tetrahydrofuran, methyl cellosolve, etc.), and nitrogen-containing compounds (N-methylpyrrolidone (NMP)) N, N-dimethylformamide (DMF), N, N′-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO) and the like.

  The dope solvent may be a mixture of a plurality of substances. When making a solvent into a mixture, it is preferable to set it as the mixture of the good solvent of a solid electrolyte, and a poor solvent. In the case of producing a solid electrolyte film having the structure of Chemical Formula 3, when protonation is carried out in the film production process, a mixture of a precursor good solvent and a poor solvent may be used as a solvent. Mix the solvent and solid electrolyte so that the solid electrolyte is 5% by weight of the total weight, and determine whether the solvent used is a poor solvent or a good solvent based on the presence or absence of insoluble matter. can do. A good solvent for the solid electrolyte, that is, a substance that dissolves the solid electrolyte has a relatively high boiling point among the compounds generally used as the solvent, while the poor solvent has a boiling point among the compounds generally used as the solvent. Is the relatively low one. Therefore, by mixing the poor solvent with the good solvent, the efficiency and effect of removing the solvent in the film production process can be enhanced, and in particular, the drying efficiency of the cast film can be greatly improved.

  In a mixture of a good solvent and a poor solvent, the weight ratio of the poor solvent is preferably as large as possible, specifically 10% or more and less than 100%. More preferably, (weight of good solvent) :( weight of poor solvent) is 90:10 to 10:90. Thereby, since the ratio of the low boiling-point component in the weight of all the solvents becomes large, the drying efficiency and the drying effect in the manufacturing process of a solid electrolyte film can be improved more.

  As the good solvent component, DMF, DMAc, DMSO, and NMP are preferable. Among them, DMSO is particularly preferable in terms of safety and relatively low boiling point. As the poor solvent component, a so-called lower alcohol having 1 to 5 carbon atoms, methyl acetate, and acetone are preferable. Among them, a lower alcohol having 1 to 3 carbon atoms is more preferable, and when DMSO is used as a good solvent. Methyl alcohol is particularly preferred from the viewpoint of the most excellent compatibility with it.

  In order to improve various film characteristics when the solid electrolyte is used as a film, an additive can be added to the dope. Examples of the additive include an antioxidant, fibers, fine particles, a water absorbing agent, a plasticizer, and a compatibilizer. The addition rate of these additives is preferably in the range of 1% by weight to 30% by weight when the total solid content in the dope is 100% by weight. However, the addition rate and the type of substance do not adversely affect the ionic conductivity. The additive will be specifically described below.

  Antioxidants include (hindered) phenolic, monovalent or divalent sulfur, trivalent phosphorus, benzophenone, benzotriazole, hindered amine, cyanoacrylate, salicylate, oxalic acid anilide These compounds are listed as preferred examples. Specific examples thereof include compounds described in JP-A-8-53614, JP-A-10-101873, JP-A-11-114430, and JP-A-2003-151346.

  Preferred examples of the fibers include perfluorocarbon fibers, cellulose fibers, glass fibers, polyethylene fibers and the like, and specifically, JP-A-10-31815, JP-A-2000-231938, JP-A-2001-307545. Examples thereof include fibers described in JP-A-2003-317748, JP-A-2004-63430, and JP-A-2004-107461.

  Examples of the fine particles include titanium oxide and zirconium oxide, and specific examples include various fine particles described in JP-A Nos. 2003-178777 and 2004-217931.

  Water-absorbing agents, that is, hydrophilic substances include cross-linked polyacrylate, starch-acrylate, poval, polyacrylonitrile, carboxymethylcellulose, polyvinylpyrrolidone, polyglycol dialkyl ether, polyglycol dialkyl ester, synthetic zeolite, titania gel, zirconia gel And yttria gel are preferable examples, and specific examples thereof include water absorbing agents described in JP-A-7-135033, JP-A-8-20716, and JP-A-9351857.

  Preferred examples of the plasticizer include phosphate ester compounds, chlorinated paraffins, alkylnaphthalene compounds, sulfone alkylamide compounds, oligoethers, and aromatic nitriles. And plasticizers described in JP-A-2003-317539.

  As the compatibilizer, those having a boiling point or sublimation point of 250 ° C. or higher are preferable, and those having a boiling point or 300 ° C. or higher are more preferable.

  The dope may further contain various polymers for the purpose of (1) increasing the mechanical strength of the film and (2) increasing the acid concentration in the film.

  Among the above objects, a polymer having a molecular weight of about 10,000 to 1,000,000 and having a good compatibility with the solid electrolyte is suitable for (1). For example, perfluorinated polymers, polystyrene, polyethylene glycol, polyoxetane, polyether ketone, polyether sulfone, and polymers containing two or more polymer repeating units are preferred. Moreover, it is preferable to contain these substances in dope so that it may become the range of 1-30 weight% with respect to the total weight when it is set as a film. The compatibility with the solid electrolyte may be improved by using a compatibilizer. As the compatibilizer, those having a boiling point or sublimation point of 250 ° C. or higher are preferable, and those having a boiling point of 300 ° C. or higher are more preferable.

  Among the above objects, (2) is preferably a polymer having a proton acid site. Examples of such a polymer include perfluorosulfonic acid polymers such as Nafion (registered trademark), sulfonated polyetheretherketone having a phosphate group in the side chain, sulfonated polyethersulfone, sulfonated polysulfone, and sulfonated polybenzimidazole. Examples thereof include sulfonated products of heat-resistant aromatic polymer compounds such as Moreover, it is preferable to contain these substances in dope so that it may become the range of 1 to 30 weight% (less than) with respect to the total weight when it is set as a film.

  Furthermore, when the obtained solid electrolyte film is used in a fuel cell, an active metal catalyst that promotes the redox reaction between the anode fuel and the cathode fuel may be added to the dope. As a result, the fuel that has permeated into the solid electrolyte film from one electrode is consumed in the solid electrolyte without reaching the other electrode, so that the crossover phenomenon can be prevented. The active metal catalyst is not particularly limited as long as it functions as an electrode catalyst, but platinum or an alloy based on platinum is particularly suitable.

[Dope production]
FIG. 1 shows a dope manufacturing facility. However, the present invention is not limited to the dope manufacturing apparatus and method shown here. The dope manufacturing facility 10 includes a solvent tank 11 for storing a solvent, a hopper 12 for supplying a solid electrolyte, an additive tank 15 for storing an additive, a solvent, a solid electrolyte, and an additive. A mixing tank 17 to be mixed into the mixed liquid 16, a heating device 18 for heating the mixed liquid 16, a temperature regulator 21 for adjusting the temperature of the heated mixed liquid 16, and a temperature regulator 21. A filtration device 22 for filtering the mixed liquid 16 that has exited, a flash device 26 for adjusting the concentration of the dope 24 from the filtration device 22, and a filtration device 27 for filtering the dope 24 whose concentration has been adjusted are provided. The dope manufacturing facility 10 further includes a recovery device 28 for recovering the solvent and a regeneration device 29 for regenerating the recovered solvent. The dope manufacturing facility 10 is connected to a film manufacturing facility 33 via a stock tank 32. In addition, although the valves 36-38 for adjusting the amount of liquid feeding and the pumps 41 and 42 for liquid feeding are provided in the dope manufacturing equipment 10, about the increase / decrease in the position and number where these are arrange | positioned It is changed appropriately.

  When the dope manufacturing facility 10 is used, the dope 24 is manufactured by the following method. By opening the valve 37, the solvent is sent from the solvent tank 11 to the mixing tank 17. Next, the solid electrolyte is fed into the mixing tank 17 from the hopper 12. At this time, the solid electrolyte may be continuously fed to the mixing tank 17 by sending means for continuously measuring and sending, or may be fed to the mixing tank 17 by sending means for weighing and sending a predetermined amount. It may be sent intermittently. In addition, the required amount of the additive solution is sent from the additive tank 15 to the mixing tank 17 by opening and closing the valve 36.

  In addition to the method of sending the additive as a solution, for example, when the additive is liquid at room temperature, the additive can be fed into the mixing tank 17 in the liquid state. Further, when the additive is solid, a method of feeding into the mixing tank 17 using a hopper or the like is also possible. When a plurality of types of additives are added, a solution in which a plurality of types of additives are dissolved can be placed in the additive tank 15. Alternatively, it is also possible to use a plurality of additive tanks and put a solution in which the additive is dissolved in each of them and send them to the mixing tank 17 through independent pipes.

  In the above description, the order of putting in the mixing tank 17 is the solvent, the solid electrolyte, and the additive, but is not limited to this order. For example, a preferred amount of solvent can be fed after the solid electrolyte is fed into the mixing tank 17. In addition, the additive is not necessarily limited to mixing the solid electrolyte and the solvent in the mixing tank 17, and may be mixed into the mixture of the solid electrolyte and the solvent in an in-line mixing method or the like in a later step.

  The mixing tank 17 includes a jacket 46 that encloses the outer surface thereof and is supplied with a heat transfer medium between the mixing tank 17, a first stirrer 48 that is rotated by a motor 47, and a second stirrer 52 that is rotated by a motor 51. It is preferable that it is attached. The temperature of the mixing tank 17 is adjusted by a heat transfer medium flowing into the inside of the jacket 46, and a preferable temperature range is −10 ° C. to 55 ° C. By appropriately selecting and using the types of the first stirrer 48 and the second stirrer 52, the mixed liquid 16 in which the solid electrolyte is swollen with the solvent is obtained. The first stirrer 48 preferably has an anchor blade, and the second stirrer 52 is preferably a dissolver type eccentric stirrer.

  Next, the liquid mixture 16 is sent to the heating device 18 by the pump 41. The heating device 18 is preferably a jacketed tube having a tube main body (not shown) and a jacket for passing a heat transfer medium between the tube main body, and further pressurizing the mixed liquid 16. It is preferable to have a part (not shown). By using such a heating device 18, the solid content in the mixed solution 16 can be effectively and efficiently dissolved under heating conditions or pressure heating conditions. Hereinafter, such a method of dissolving a solid component in a solvent by heating is referred to as a heating dissolution method. In the heating dissolution method, it is preferable to heat the mixed solution 16 so as to be 60 ° C to 250 ° C.

  Note that the solid component may be dissolved in a solvent by a cooling dissolution method instead of the heating dissolution method. The cooling dissolution method is a method in which dissolution is advanced while cooling so that the temperature of the mixed liquid 16 is maintained or even lower. In the cooling dissolution method, the mixed solution 16 is preferably cooled to a temperature of −100 ° C. to −10 ° C. The solid electrolyte can be sufficiently dissolved in the solvent by the heating dissolution method or the cooling dissolution method as described above.

  After the mixed liquid 16 is brought to about room temperature by the temperature controller 21, it is filtered by a filtration device 22 to remove foreign matters such as impurities and aggregates to obtain a dope 24. The filter used for the filtration device 22 preferably has an average pore size of 10 μm or less.

  The dope 24 after filtration is sent to the stock tank 32 by the valve 38 and once stored, and then used for the production of a film.

  By the way, as described above, the method in which the solid component is once swollen and then dissolved to form a solution increases the time required for the dope production as the concentration of the solid electrolyte in the solution is increased. May be a problem. In such a case, it is preferable to once make a dope having a concentration lower than the target concentration and then carry out a concentration step to achieve the target concentration. For example, the dope 24 filtered by the filtering device 22 can be sent to the flash device 26 by the valve 38, and the dope 24 can be concentrated by evaporating a part of the solvent of the dope 24. The concentrated dope 24 is extracted from the flash device 26 by the pump 42 and sent to the filtration device 27. The temperature of the dope 24 during filtration is preferably 0 ° C to 200 ° C. The dope 24 from which foreign matter has been removed by the filtration device 27 is sent to the stock tank 32 and once stored, and then used for film production. In addition, since the concentrated dope 24 may contain bubbles, it is preferable to carry out a bubble removal process before sending it to the filtration device 27. As the bubble removal method, for example, various known methods such as an ultrasonic irradiation method for irradiating the dope 24 with ultrasonic waves are applied.

  Further, the solvent gas generated by the flash evaporation in the flash device 26 is condensed by the recovery device 28 having a condenser (not shown) and recovered as a liquid. The recovered solvent is regenerated and reused as a solvent for dope production by the regenerator 29. Such collection and recycling have advantages in terms of manufacturing costs and are effective in preventing adverse effects on the human body and the environment because they are implemented in a closed system.

  By the above manufacturing method, the dope 24 having a solid electrolyte concentration of 5 wt% or more and 50 wt% or less can be manufactured. The solid electrolyte concentration is more preferably in the range of 10 wt% to 40 wt%. The concentration of the additive is preferably in the range of 1% by weight to 30% by weight when the total solid content in the dope is 100% by weight.

[Film production]
A method for producing a solid electrolyte film will be described. FIG. 2 is a schematic view of the film manufacturing facility 33. However, the present invention is not limited to the film manufacturing method and equipment as shown here. In the film manufacturing facility 33, a filtration device 61 for removing foreign substances from the dope 24 sent from the stock tank 32, and a dope 24 filtered by the filtration device 61 are cast to produce a solid electrolyte film (hereinafter simply referred to as a film). A casting chamber 63, 62, a tenter 64 that holds both side ends of the film 62 and dries while conveying the film 62, an edge-cutting device 67 that separates both side ends of the film 62, and a film 62. A drying chamber 69 for drying while being conveyed over a plurality of rollers 68, a cooling chamber 71 for cooling the film 62, a static eliminating device 72 for reducing the charge amount of the film 62, and embossing at the side end A knurling roller pair 73 for applying the film and a winding chamber 76 for winding the film 62 are provided.

  A stirrer 78 that is rotated by a motor 77 is attached to the stock tank 32, and precipitation and aggregation of the solid content of the dope 24 are suppressed by stirring. The stock tank 32 is connected to the filtration device 61 via the pump 80. The filter used for the filtration device 61 preferably has an average pore diameter of 10 μm or less. Thereby, it can prevent that the impurity which becomes a factor of deterioration of the initial performance of proton conductivity and a time-dependent deterioration of proton conductivity mixes in a film. The presence or absence of impurities such as insoluble matter can be visually evaluated by illuminating the dope sampled from the stock tank 32 with a fluorescent lamp.

The casting chamber 63 includes a casting die 81 that flows out of the dope 24, and a casting band 82 as a traveling support. As a material of the casting die 81, precipitation hardening type stainless steel is preferable, and its thermal expansion coefficient is preferably 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. And it has almost the same corrosion resistance as SUS316 in the forced corrosion test with electrolyte aqueous solution, and even if it is immersed in a mixed solution of dichloromethane, methanol and water for 3 months, pitting (opening) occurs at the gas-liquid interface. Those having corrosion resistance that do not occur are preferred. The casting die 81 is preferably produced by grinding a material that has passed for one month or more after casting, whereby the dope 24 uniformly flows inside the casting die 81, and the flow described later. Streaks and the like are prevented from occurring in the spread film 24a. The so-called wetted surface in contact with the dope 24 of the casting die 81 preferably has a finishing accuracy of 1 μm or less in terms of surface roughness and a straightness of 1 μm / m or less in any direction. The clearance of the slit of the casting die 81 can be adjusted in the range of 0.5 mm to 3.5 mm by automatic adjustment. The chamfer radius R of the corner portion of the liquid contact portion at the tip of the lip of the casting die 81 is constant and 50 μm or less over the entire width of the casting die 81. The casting die 81 is preferably a coat hanger type die.

  The width of the casting die 81 is not particularly limited, but is preferably about 1.1 to 2.0 times the width of the film 62 as the final product. Further, it is preferable that a temperature control device for controlling the temperature of the casting die 81 is attached to the casting die 81 so that the temperature of the dope 24 during film formation is maintained at a predetermined temperature. Further, it is more preferable that the casting die 81 is provided with a plurality of thickness adjusting bolts (heat bolts) provided at a predetermined interval in the width direction and an automatic thickness adjusting mechanism that adjusts a gap between the slits with the heat bolt. . The heat bolt is preferably subjected to film formation by setting a profile according to the amount of pump 81 (preferably a high precision gear pump) according to a preset program. In order to precisely control the dope feed amount, the pump 80 is preferably a high-precision gear pump. In addition, a thickness measuring machine such as an infrared thickness gauge is provided in the film manufacturing facility 33, and feedback control to the automatic thickness adjusting mechanism is performed by an adjustment program based on the thickness profile and a detection result by the thickness measuring machine. Also good. It is preferable to use a casting die 81 that can adjust the slit interval of the tip lip to be ± 50 μm or less so that the difference in thickness at any two positions excluding both side ends of the film 62 as a product is within 1 μm.

More preferably, a cured film is formed at the lip end of the casting die 81. A method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. In the case of using ceramics as the cured film, it is preferable to use a ceramic that can be ground, has a low porosity, is not brittle, has good corrosion resistance, and has no affinity or adhesion to the dope 24. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like. Among them, WC is particularly preferable. The WC coating can be performed by a thermal spraying method.

  In order to prevent the dope 24 from locally drying and solidifying at the lip tip of the casting die 81, it is preferable to attach a solvent supply device (not shown) for supplying a solvent to the lip tip in the vicinity of the lip tip. . The position where the solvent is supplied is preferably a peripheral portion of a three-phase contact line formed by both ends of the casting bead, both ends of the lip tip, and the outside air. The flow rate of the supplied solvent is preferably 0.1 mL / min to 1.0 mL / min for each side. Thereby, it is possible to prevent foreign matters, for example, solid components deposited from the dope 24 and those mixed in the casting bead from the outside from being mixed in the casting film 24a. In addition, as a pump which supplies a solvent, it is preferable to use a pulsation rate of 5% or less.

  The width of the casting band 82 is not particularly limited, but it is preferable to use a casting band having a range of 1.1 to 2.0 times the casting width of the dope 24. Further, it is preferable that the length is 20 m to 200 m, the thickness is 0.5 mm to 2.5 mm, and the surface roughness is polished to be 0.05 μm or less.

  The material of the casting band 82 is not particularly limited, but is preferably stainless steel. Other materials include non-woven plastic films such as polyethylene terephthalate (PET) film, polybutylene terephthalate (PBT) film, nylon 6 film, nylon 6,6 film, polypropylene film, polycarbonate film and polyimide film. It is preferably a long product having chemical stability and heat resistance that can cope with the solvent to be used and the film forming temperature. In this embodiment, a casting band 82 made of SUS that is not dissolved in the solvent to be used is used.

  The rotating rollers 85 and 86 are preferably provided with a heat transfer medium circulating device 87 for supplying the heat transfer medium to the rotating rollers 85 and 86 and controlling the surface temperature of the rollers. The surface temperature is set to a predetermined value. In this embodiment, a heat transfer medium flow path (not shown) is formed in the rotary rollers 85 and 86, and the heat transfer medium maintained at a predetermined temperature passes through the flow path, The temperature of the rotating rollers 85 and 86 is maintained at a predetermined value. The surface temperature of the casting band 82 is appropriately set according to the type of solvent, the type of solid component, the concentration of the dope 24, and the like.

A rotating drum (not shown) can be used as a support instead of the rotating rollers 85 and 86 and the casting band 82. In this case, it is preferable that the rotation can be performed with high accuracy so that the rotation speed unevenness is 0.2% or less. The rotating drum preferably has an average surface roughness of 0.01 μm or less, and preferably has a surface subjected to a hard chrome plating treatment or the like. Thereby, sufficient hardness and durability can be improved. In addition, it is preferable that the surface defects of the rotating drum, the casting band 82, and the rotating rollers 85 and 86 are suppressed to a minimum. Specifically, there is no pinhole of 30 μm or more, and the number of pinholes of 10 μm or more and less than 30 μm is 1 / m ² or less, and the number of pinholes of less than 10 μm is preferably ² / m ² or less.

  In the vicinity of the casting die 81, a decompression chamber 90 is preferably provided to control the pressure upstream of the casting bead formed from the casting die 81 to the casting band 82 in the traveling direction of the casting band 82. .

  A first air duct 91 is provided along the casting band 82 on the downstream side of the casting die 81 in the traveling direction of the casting band 82, and second to fourth on the downstream side of the first air duct 91. Blower ducts (blower chambers) 92 to 94 are sequentially provided. As shown in FIG. 3, the 1st-4th ventilation ducts 91-94 are connected with the dry air circulation part 96 which has an air blower and a heater. The dry air circulation unit 96 supplies the dried air to the first to fourth air ducts 91 to 94. The first to fourth air ducts 91 to 94 emit dry air toward a surface (hereinafter referred to as an air surface) 24b opposite to the surface in contact with the casting band 82 of the casting film 24a. Thereby, dry air flows in the vicinity of the casting film 24a, and the solvent contained in the casting film 24a evaporates. A wind shield 95 extending in the width direction of the casting band 82 is provided between the casting die 81 and the first air duct 91 so as to stand upright. A labyrinth seal 95a is disposed at the lower end of the wind shielding plate 95, and the labyrinth seal 95a blocks the backflow of the wind generated along with the traveling of the casting band 82, that is, the accompanying wind (hereinafter referred to as the “bound wind”). is doing. As a result, the drying air does not directly hit the casting film 24 a between the casting die 81 and the first air duct 91. Hereinafter, a region between the casting die 81 and the first air duct 91 is referred to as a “sequential wind region 300”.

  In the first air duct 91, a slit nozzle 91a having an elongated opening (slit) in the width direction of the casting band 82 is formed. By the dry air 301 from the first air duct 91, the casting film 24a The air surface 24b is gradually dried. By this dry air 301, a skin layer 24c having a surface tension different from that of the casting band 82 side of the casting film 24a is generated on the air surface 24b side of the casting film 24a 60 seconds after the casting. The An enlarged view (A) of a portion surrounded by a broken line in FIG. 3 shows a cross-sectional view of the casting film 24a on which the skin layer 24c is generated.

  The wind speed of the drying air 301 is preferably less than 3 m / sec in the same direction as the moving direction of the casting film 24a. When dry air with a large wind speed exceeding 3 m / sec is applied to the air surface 24b, streaks and unevenness are generated on the air surface 24b, and the dried film surface may not be smooth and flat. In addition, the wind speed of this dry wind 301 is a relative value with respect to the moving speed of the casting film 24a.

  Moreover, it is preferable that the temperature of the drying air 301 is less than 100 degreeC, and it is more preferable that it is 20 to 70 degreeC. In this drying step, when the casting membrane 24a absorbs water, the casting membrane 24a is phase-separated and solidified, resulting in a film having a high porosity. Therefore, it is preferable to use a low-humidity drying air for drying the casting film 24a immediately after casting. That is, the humidity of the dry air 301 is preferably less than 50% RH, and more preferably less than 20% RH.

  Further, the direction of the wind that is a weak wind with a wind speed of 2 m / sec or less is not constant. When the trendy wind that is a turbulent flow hits the air surface 24b of the casting film 24a immediately after casting, streaky unevenness corresponding to the wind direction of the trending wind is generated on the air surface 24b. Therefore, it is preferable to apply certain restrictions to the wind speed of the incoming wind, the distance between the wind shielding plate 95 and the first air duct 91, and the time during which the casting film 24a passes through the incoming wind region 300. It is preferable that the wind speed of the incoming wind with respect to the casting film 24a is small. Specifically, it is preferably less than 1.0 m / sec, and particularly preferably less than 0.5 m / sec. The distance between the wind shielding plate 95 and the first air duct 91 is preferably shorter, specifically, 3000 mm or less, more preferably 2000 mm or less, and still more preferably 1000 mm or less. Further, it is preferable that the time required for the casting film 24a to pass through the leading wind region 300 is short, specifically, it is preferably 15 seconds or less, more preferably 10 seconds or less, and most preferably 7 seconds or less. .

  The 2nd-4th ventilation ducts 92-94 dry the casting film 24a in which the skin layer 24c was produced | generated, and give the casting film 24a self-supporting property. Each of these air ducts 92 to 94 also has a nozzle that is substantially the same as the first air duct 91. In addition, although the nozzle shape of each air duct 91-94 is not specifically limited, What can send dry air substantially uniformly in the width direction of the casting film 24a is preferable. It is preferable that the wind speed of the dry wind which comes out of the 2nd-4th ventilation ducts 92-94 is a substantially the same direction as the moving direction of the casting film 24a, and is about 15 m / sec. The temperature of the drying air is preferably 150 ° C. or lower, and more preferably 30 ° C. or higher and 150 ° C. or lower. The humidity of the drying air is preferably less than 50% RH.

  The drying conditions of the air ducts 91 to 94 necessary for generating the skin layer 24c are not limited to the above-described conditions. What is necessary is just to set the drying conditions which form the skin layer 24c in the casting film | membrane 24a after 60 second progress from immediately after casting according to the casting dope component and casting equipment used for a casting process. . Examples of means for adjusting to the desired drying conditions include the temperature and gas concentration of the drying air, the number of air ducts to be installed, and the arrangement position. By combining these, it becomes possible to set drying conditions according to the form of the casting process.

  A two-dimensional nozzle may be used instead of the slit nozzle 91a. The two-dimensional nozzle includes first and second openings facing the air surface 24b. The first opening emits dry air toward the air surface 24b. The second opening sucks air in the vicinity of the casting film 24a. Further, the number of slit nozzles 91a and two-dimensional nozzles is not limited to one, and may be plural. Further, fins that change the direction of the drying air may be provided in each slit nozzle 91a or two-dimensional nozzle. Further, an exhaust port having substantially the same shape as each nozzle is provided between each slit nozzle 91a and the two-dimensional nozzle, and the dry air sent from the slit nozzle 91a or the like and hitting the casting film 24a is exhausted. Good.

  FIG. 4 is a schematic diagram showing the flow of dry air by the first air duct 91. As shown to (A), as shown to (B)-(D) other than the 1st ventilation duct 91 which sends the dry wind 301 to the running direction (henceforth a band running direction) A1 of the casting band 82, as shown to (A). Alternatively, the air ducts 305 to 307 may be used to send the drying air 301 in the width direction B1 of the casting film 24a orthogonal to the band traveling direction A1. In the air duct 305 shown in (B), the drying air 301 is sent toward the center of the casting membrane 24a from a nozzle 305a formed near both side edges of the casting membrane 24a. In the air duct 306 shown in (C), the drying air 301 is sent from the nozzle 306a formed near the center of the casting membrane 24a toward both side edges of the casting membrane 24a. In the air duct 307 shown in (D), dry air is sent from a nozzle 307a formed near one side edge of the casting membrane 24a to an exhaust port 307b formed near the other side edge.

  The casting chamber 63 is provided with a temperature control device 97 for keeping the internal temperature at a predetermined value, and a condenser (condenser) 98 for condensing and recovering the volatile organic solvent. A recovery device 99 for recovering the condensed and liquefied organic solvent is provided outside the casting chamber 63.

  The transition portion 101 downstream of the casting chamber 63 is provided with a blower 102, and this blower 102 sends dry air to the film 62. The film that has passed through the crossing portion 101 is sent to the tenter 64, where the end in the width direction is gripped by a film gripping member such as a tenter clip 64a or a pin, and stretching is performed in the width direction. Further, drying air is introduced into the tenter 64, whereby the film 62 is dried. It is preferable to divide the inside of the tenter 64 into different temperature zones and adjust the drying conditions as appropriate for each of the zones. The film 62 that has exited the tenter 64 is sent to the ear-cutting device 67. The ear clip device 67 is provided with a crusher 103 for finely cutting the side edge scraps of the cut film 62.

  An adsorption recovery device 106 for adsorbing and recovering the solvent gas generated by evaporation from the film 62 is attached to the drying chamber 69. In FIG. 2, a cooling chamber 71 is provided downstream of the drying chamber 69, but a humidity control chamber (not shown) for adjusting the moisture content of the film 62 between the drying chamber 69 and the cooling chamber 71. ) May be provided. The static eliminator 72 is a forced static eliminator such as a static eliminator, and can adjust the charged voltage of the film 62 so as to be within a predetermined range (for example, −3 kV to +3 kV). The static eliminator 72 is illustrated as being disposed on the downstream side of the cooling chamber 71, but is not limited to this installation position. The knurling imparting roller pair 73 imparts knurling to both end portions of the film 62 by embossing. Inside the take-up chamber 76, a take-up roll 107 for taking up the film 62 and a press roller 108 for controlling the tension during the take-up are provided.

  Next, an example of a method for producing the film 62 using the film production equipment 33 as described above will be described below. The dope 24 is always made uniform by the rotation of the stirrer 78. Various additives can be appropriately mixed in the dope 24 during the stirring.

  The dope 24 is sent to the stock tank 32, and solid matter precipitation and aggregation are suppressed by stirring until it is cast. And the foreign material of a size more than a predetermined particle size and a gel-like foreign material are removed by filtration with the filtration apparatus 61. FIG.

The dope 24 is cast from the casting die 81 to the casting band 82. The relative position of the rotary roller 85 and the rotary roller 86 and / or the rotational speed of at least one of them is adjusted so that the tension generated in the casting band 82 is 10 ³ N / m × 10 ⁶ N / m. The relative speed difference between the casting band 82 and the rotating rollers 85 and 86 is 0.01 m / min. It is made to become the following. It is preferable that the speed fluctuation of the casting band 82 is 0.5% or less, and the meandering in the width direction that occurs when the casting band 82 makes one round is 1.5 mm or less. In order to suppress this meandering, a detector (not shown) for detecting the positions of both ends of the casting band 82 and a position adjusting device (not shown) for adjusting the position of the casting band 82 according to the detection data by this detector. It is more preferable to provide feedback control of the position of the casting band 82. Further, it is preferable that the position fluctuation in the vertical direction associated with the rotation of the rotary roller 85 is within 200 μm for the casting band 82 immediately below the casting die 81. In addition, the temperature of the casting chamber 63 is preferably set to −10 ° C. to 57 ° C. by the temperature control device 97. The solvent evaporated in the casting chamber 63 is recovered by the recovery device 99 and then regenerated and reused as a solvent for dope production.

  A casting bead is formed from the casting die 81 to the casting band 82, and a casting film 24 a is formed on the casting band 82. In order to stabilize the state of the casting bead, the decompression chamber 90 is preferably controlled so that the upstream area of the casting bead has a predetermined pressure value. The decompression value of the decompression chamber 90 is preferably −2500 Pa to −10 Pa from the downstream area with respect to the bead. It is preferable to attach a jacket (not shown) to the decompression chamber 90 so that the internal temperature is kept at a predetermined temperature. In order to keep the shape of the casting bead desired, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 81 to suck both sides of the bead. The edge suction air volume is preferably in the range of 1 L / min to 100 L / min.

  As shown in FIG. 3, the casting film 24 a immediately after casting passes through the downward direction of the first air duct 91 after passing through the steep wind region 300. When passing below the first air duct 91, the dry air 301 from the first air duct 91 hits the air surface 24b of the casting membrane 24a. The air surface 24b is gradually dried by the drying air, and a skin layer 24c is generated on the air surface 24b. The skin layer 24c is a layer having a surface tension different from that of the casting film 24a on the casting band 82 side. In this way, the air surface 24b side of the casting film 24a is solidified to generate the skin layer 24c. By the generation of the skin layer 24c, the smoothing of the casting film 24a on the air surface 24b side proceeds, and the air surface 24b of the casting film 24a becomes dense. Since the solid electrolyte film for a fuel cell manufactured from such a casting membrane 24a has a dense layer on the surface, the dense layer can prevent passage of fuel and suppress crossover.

  The skin layer 24c is generated 60 seconds after the casting film 24a is cast. If the skin layer 24c is to be generated within 60 seconds from the formation of the casting film 24a, dry air having a wind speed of 3 m / second or more is required. When drying air having a high wind speed is applied to the casting film 24a, streaks and unevenness are generated on the air surface 24b, and the surface of the dried film may not be smooth. In particular, in the casting film 24a immediately after casting, streaks and unevenness are easily generated on the air surface 24b by the dry air. In addition, it is preferable that the thickness of the skin layer 24c is 2% or more and 40% or less with respect to the thickness of the film 62 which is the final form of the product.

  The residual solvent amount of the casting film 24a at the start of drying with the drying air 301 is preferably 150% by weight or more and 500% by weight or less, and particularly preferably 200% by weight or more and 350% by weight or less based on the dry weight. When the amount of residual solvent in the casting film 24a at the start of drying by the drying air 301 is less than 150% by weight on the dry weight basis, the degree of drying has progressed too much, so the skin layer on the air surface 24b side. Cannot be generated. On the other hand, a dope having a residual solvent amount exceeding 500% by weight on a dry basis is difficult to perform stable casting from the casting die 81. The amount of residual solvent based on the dry amount is a value calculated by {(xy) / y} × 100, where x is the film weight at the time of sampling and y is the weight after the sampling film is dried. It is. After the drying process by the first air duct 91, the casting film 24 a having the skin layer 24 c on the air surface 24 b is self-supporting by the air blowing of the second to fourth air ducts 92 to 94. Until dried. The skin layer 24c may be generated using the dry air 301 from the first air duct 91 and the dry air from the second to fourth air ducts 92 to 94.

  As shown in FIG. 2, after the casting film 24 a has self-supporting properties, it is peeled off from the casting band 82 while being supported by the peeling roller 109. The film 62 containing the solvent is supported by a plurality of rollers and conveyed through the crossing portion 101 and then sent to the tenter 64. In the crossing portion 101, it is possible to apply a draw tension to the film 62 by making the rotational speed of the downstream roller faster than the rotational speed of the upstream roller. Moreover, in the crossover part 101, the drying air of desired temperature is sent to the film 62 vicinity from the air blower 102, or is directly sprayed on the film 62, and the drying of the film 62 is advanced. At this time, the temperature of the drying air is preferably 20 ° C to 250 ° C.

  The film 62 sent to the tenter 64 is dried while its both ends are held and conveyed by holding means such as a clip 64a. A pin may be used instead of the clip, and the film may be pierced and held by the pin. Moreover, it is preferable to divide the inside of the tenter 64 into different temperature zones and adjust the drying conditions appropriately for each of the zones. In the tenter 64, the film 62 can be stretched in the width direction. As described above, in at least one of the crossover portion 101 and the tenter 64, at least one direction of the casting direction and the width direction of the film 62 is 100.5% to 300% of the dimension before stretching. It is preferable to stretch so as to be.

  The film 62 is dried to a predetermined residual solvent amount by the tenter 64, and then both end portions thereof are cut and removed by the edge-cutting device 67. The separated both end portions are sent to the crusher 103 by a cutter blower (not shown). By the crusher 103, the side end portion is crushed into chips. Since this chip is reused for dope manufacturing, the raw material can be effectively used. In addition, although it can also abbreviate | omit about the cutting process of this both-sides edge part, it is preferable to carry out in any one from the said casting process to the process of winding up the said film.

  On the other hand, the film 62 from which both side ends have been removed is sent to the drying chamber 69 and further dried. The internal temperature of the drying chamber 69 is not particularly limited, but is determined according to the heat resistance (glass transition point Tg, heat distortion temperature, melting point Tm, continuous use temperature, etc.) of the solid electrolyte, and is Tg or less. It is preferable. The internal temperature of the drying chamber 69 is preferably 120 ° C. or higher and 185 ° C. or lower, and is preferably dried until the residual solvent amount of the film 62 is less than 3% by weight. In the drying chamber 69, the solvent gas evaporated from the inside floats as the film 62 is dried. However, in the present embodiment, the solvent gas floating is absorbed and recovered by the adsorption recovery device 106. The air from which the solvent component has been removed by the adsorption recovery device 106 is sent again as dry air into the drying chamber 69.

  In addition, it is more preferable that the drying chamber 69 is divided into a plurality of sections in order to change the blowing temperature. In addition, if a preliminary drying chamber (not shown) is provided between the ear opener 67 and the drying chamber 69 to preliminarily dry the film 62, the film temperature is prevented from rising rapidly in the drying chamber 69. The shape change of the film 62 at 69 can be suppressed. Note that, instead of or in addition to drying with such drying air, drying under reduced pressure, drying with far infrared rays, drying with microwaves, or the like may be performed.

  The film 62 exiting the drying chamber 69 is cooled to approximately room temperature in the cooling chamber 71. In the case where a humidity control chamber is provided between the drying chamber 69 and the cooling chamber 71, it is preferable to blow air adjusted to a desired humidity and temperature onto the film 62 in the humidity control chamber. In addition, when providing a humidity control chamber, it is preferable that the internal temperature shall be 20 degreeC or more and 30 degrees C or less, and the humidity shall be 40 RH% or more and 70 RH% or less. Thereby, it is possible to suppress the occurrence of curling of the film 62 and winding failure when winding.

  The neutralizing device 72 sets the charged voltage while the film 62 is being conveyed to a predetermined value. The charged voltage after neutralization is preferably -3 kV to +3 kV. Further, the film 62 is preferably imparted with knurling by a knurling roller pair 73. In addition, it is preferable that the height of the unevenness | corrugation of the knurled location is 1 micrometer-200 micrometers.

  The film 62 is taken up by a take-up roll 107 in the take-up chamber 76. It is preferable to wind the film while applying a desired tension to the film 62 by the press roller. It is more preferable to gradually change the tension from the start to the end of winding, thereby preventing excessive winding in the film roll. The width of the film 62 to be wound is preferably 100 mm or more. The present invention is also applied to the production of a thin film having a film thickness of 5 μm or more and 300 μm or less.

  In the present invention, when casting the dope 24, a method in which two or more kinds of dopes are simultaneously laminated co-cast or sequentially laminated co-cast may be used. When performing simultaneous lamination and co-casting, a casting die to which a feed block is attached may be used, or a multi-manifold casting die may be used. As for the film which consists of a multilayer by co-casting, it is preferable that any one of the two layers exposed on the surface is 0.5% to 30% of the total thickness of the film. Further, in the case of simultaneous lamination co-casting, the concentration of each dope is set in advance so that when the dope is cast from the die slit to the support, the high-viscosity dope is wrapped and cast by the low-viscosity dope. It is preferable to adjust. In the case of simultaneous lamination and co-casting, the bead formed from the die slit to the support is in contact with the outside world, that is, the exposed dope has a larger proportion of the poor solvent than the internal dope. It is preferable.

  In place of the above-described method for forming a solid electrolyte into a film, a film in which the solid electrolyte enters the pores is manufactured by holding the solid electrolyte in the pores of a so-called porous substrate in which a plurality of pores are formed. However, a solid electrolyte film different from the above embodiment can be manufactured. As a method for producing such a solid electrolyte film, a method in which a sol-gel reaction solution containing a solid electrolyte is applied onto a porous substrate and the solid electrolyte is put into pores, and the porous substrate includes a solid electrolyte. There is a method of immersing in a sol-gel reaction solution to fill the solid electrolyte in the pores. Preferable examples of the porous substrate include porous polypropylene, porous polytetrafluoroethylene, porous cross-linked heat-resistant polyethylene, and porous polyimide. Moreover, a solid electrolyte film can also be formed by processing a solid electrolyte into a fiber shape, filling voids in the fiber with other polymer compounds, etc., and forming the film using the fiber. In this case, examples of the other polymer compound for filling the void include the substances mentioned as additives in the present specification.

  The solid electrolyte film of the present invention can be suitably used as a proton conductive membrane for a fuel cell, particularly a direct methanol fuel cell, and can be used as a solid electrolyte film sandwiched between two electrodes of a fuel cell. it can. Furthermore, as electrolytes, display elements, electrochemical sensors, signal transmission media, capacitors, electrodialysis, electrolytic membranes for electrolysis, gel actuators, salt electrolytic membranes, proton exchange resins in various batteries (redox flow batteries, lithium batteries, etc.) The solid electrolyte film of the present invention can be used.

(Fuel cell)
Hereinafter, an example in which a solid electrolyte film is used for an electrode membrane composite (hereinafter referred to as MEA) and an example in which the electrode membrane composite is used for a fuel cell will be described. However, the modes of the MEA and the fuel cell shown here are examples of the present invention, and the present invention is not limited thereto. FIG. 5 is a schematic cross-sectional view of the MEA. The MEA 131 includes a film 62 and an anode electrode 132 and a cathode electrode 133 that are opposed to each other with the film 62 interposed therebetween.

  The anode electrode 132 has a porous conductive sheet 132 a and a catalyst layer 132 b in contact with the film 62, and the cathode electrode 133 has a porous conductive sheet 133 a and a catalyst layer 133 b in contact with the film 62. Examples of the porous conductive sheets 132a and 133a include carbon paper. The catalyst layers 132b and 133b are made of a dispersion in which carbon particles carrying a catalyst metal such as platinum particles are dispersed in a proton conductive material. Examples of the carbon particles include ketjen black, acetylene black, and carbon nanotube. Examples of the proton conductive material include Nafion (registered trademark).

As the manufacturing method of the MEA 131, the following four methods are preferable.
(1) Proton conductive material coating method: a catalyst paste (ink) containing active metal-carrying carbon, proton conductive material, and solvent is directly applied to both surfaces of the film 62, and the porous conductive sheets 132a and 133a are applied to the (heat) coating layer. A MEA having a five-layer structure is manufactured by pressure bonding.
(2) Porous conductive sheet coating method: After a liquid containing the material of the catalyst layers 132b and 133b, for example, a catalyst paste, is applied to the surfaces of the porous conductive sheets 132a and 133a to form the catalyst layers 132b and 133b. The film 62 is pressure-bonded to produce a MEA 131 having a five-layer structure.
(3) Decal method: After a catalyst paste is applied on PTFE to form catalyst layers 132b and 133b, only the catalyst layers 132b and 133b are formed on the film 62 to form a three-layer structure. The sheets 132a and 133a are pressure-bonded to produce a MEA 131 having a five-layer structure.
(4) Post-catalyst loading method: An ink in which a platinum unsupported carbon material is mixed with a proton conductive material is applied and formed on the film 62, the porous conductive sheets 132a, 133a or PTFE, and then the film is applied to a liquid containing platinum ions. 62 is impregnated, and platinum particles are reduced and deposited in the film to form the catalyst layers 132b and 133b. After the formation of the catalyst layers 132b and 133b, the MEA 131 is produced by the above methods (1) to (3).

  However, the method of making the MEA is not limited to the above method, and various known methods can be applied. For example, in addition to the above methods (1) to (4), there are the following methods. A coating solution containing the materials of the catalyst layers 132b and 133b is prepared in advance, and this coating solution is applied to a support and dried. The support on which the catalyst layers 132b and 133b are formed is pressure-bonded on the both sides of the film 62 so that the catalyst layers 132b and 133b are in contact with the film 62, respectively. And after peeling a support body, the film 62 in which the catalyst layers 132b and 133b were formed in both surfaces is pinched | interposed with the porous conductive sheets 132a and 133a. And MEA can be manufactured by closely contacting the porous conductive sheets 132a and 133a and the catalyst layers 132b and 133b.

  FIG. 6 is a schematic view of a fuel cell. The fuel cell 141 includes an MEA 131, a pair of separators 142 and 143 that sandwich the MEA 131, a current collector 146 made of a stainless net attached to the separators 142 and 143, and a packing 147. An anode pole side opening 151 is provided in the anode pole side separator 142, and a cathode pole side opening 152 is provided in the cathode pole side separator 143. Gas fuel such as hydrogen and alcohols (such as methanol) or liquid fuel such as an alcohol aqueous solution is supplied from the anode electrode side opening 151, and oxidant gas such as oxygen gas and air is supplied from the cathode electrode side opening 152. Is supplied.

  A catalyst in which active metal particles such as platinum are supported on a carbon material is used for the anode electrode 132 and the cathode electrode 133. Commonly used active metal particle sizes are in the range of 2 to 10 nm. However, the smaller the particle size, the greater the surface area per unit weight, which increases the activity and is advantageous. However, if it is too small, it is difficult to disperse without agglomeration, so about 2 nm is said to be the small limit. .

  The active polarization in the hydrogen-oxygen fuel cell is larger in the cathode electrode, that is, the air electrode than in the anode electrode, that is, the hydrogen electrode. This is because the rate of the cathode electrode reaction, that is, the oxygen reduction reaction, is slower than that of the anode electrode. For the purpose of improving the activity of the oxygen electrode, various platinum-based binary metals such as Pt—Cr, Pt—Ni, Pt—Co, Pt—Cu, and Pt—Fe can be used. In a direct methanol fuel cell using a methanol aqueous solution as the anode fuel, in order to suppress catalyst poisoning by CO generated during the oxidation process of methanol, Pt—Ru, Pt—Fe, Pt—Ni, Pt—Co, and Pt—Mo are used. Pt-Ru-Mo, Pt-Ru-W, Pt-Ru-Co, Pt-Ru-Fe, Pt-Ru-Ni, Pt-Ru-Cu, Pt-Ru-Sn, etc. A platinum group ternary metal such as Pt—Ru—Au can be used. As the carbon material for supporting the active metal, acetylene black, Vulcan XC-72, ketjen black, carbon nanohorn (CNH), and carbon nanotube (CNT) are preferably used.

The catalyst layers 132b and 133b are generated by (1) transporting the fuel to the active metal, (2) providing a field for the oxidation (anode electrode) and reduction (cathode electrode) reaction of the fuel, and (3) oxidation / reduction. And (4) transports protons generated by the reaction to the solid electrolyte, that is, the film 62. For (1), the catalyst layers 132b and 133b are made porous so that liquid and gaseous fuel can permeate deeply. For (2), the active metal catalyst supported on the carbon material is responsible, and (3) is also responsible for the carbon material. In order to fulfill the function (4), a proton conductive material is mixed in the catalyst layers 132b and 133b. The proton conductive material of the catalyst layer is not limited as long as it is a solid having a proton donating group, but is represented by a polymer compound having an acid residue used for the film 62, for example, Nafion (registered trademark). Preferable examples include sulfonated products of heat-resistant aromatic polymers such as perfluorosulfonic acid, side chain phosphate group poly (meth) acrylate, sulfonated polyetheretherketone, and sulfonated polybenzimidazole. When the solid electrolyte used as the material of the film 62 is used for the catalyst layers 132b and 133b, the catalyst layers 132b and 133b and the film 62 are the same type of material, so that the electrochemical adhesion between the solid electrolyte and the catalyst layer is increased. Considering ionic conductivity, it becomes more advantageous. It is suitable from a viewpoint of battery output and economical efficiency to make the usage-amount of an active metal into the range of 0.03-10 mg / cm < ² >. The amount of the carbon material supporting the active metal is preferably 1 to 10 times the weight of the active metal. The amount of the proton conductive material is preferably 0.1 to 0.7 times the weight of the active metal-carrying carbon.

  The catalyst layers 132b and 133b are also referred to as an electrode base material, a permeable layer, or a backing material, and play a role of preventing current collection and deterioration of gas permeation and accumulation of water. Usually, carbon paper or carbon cloth can be used, and polytetrafluoroethylene (PTFE) treated for water repellency can be used.

MEA is incorporated into a battery, preferably having an area resistance value of 3Omucm ² below by the AC impedance method in a state filled with fuel, more preferably those of 1 .OMEGA.cm ² or less, and most preferably those 0.5Omucm ² below. The area resistance value is obtained from the product of the actually measured resistance value and the area of the sample.

  What can be used as a fuel of a fuel cell will be described. Examples of the anode fuel include hydrogen, alcohols (such as methanol, isopropanol, and ethylene glycol), ethers (such as dimethyl ether, dimethoxymethane, and trimethoxymethane), formic acid, borohydride complex, and ascorbic acid. Examples of the cathode fuel include oxygen (including oxygen in the atmosphere) and hydrogen peroxide.

In the direct methanol fuel cell, a methanol aqueous solution having a methanol concentration of 3 to 64% by weight is used as the anode fuel. According to the anode reaction formula (CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ ), 1 mol of water is required for 1 mol of methanol, and the methanol concentration at this time corresponds to 64% by weight. The higher the methanol concentration, there is an advantage that the weight and volume of the battery including the fuel tank with the same energy capacity can be reduced. However, the higher the methanol concentration, the more so-called crossover phenomenon that methanol permeates the solid electrolyte and reacts with oxygen on the cathode side to lower the voltage, and the output tends to decrease. Therefore, it is preferable to determine the methanol concentration in consideration of methanol permeation that induces a crossover phenomenon. The cathode reaction formula of the direct methanol fuel cell is (3/2) O ₂ + 6H ⁺ + 6e ⁻ → H ₂ O, and oxygen (usually oxygen in the air) is used as the fuel.

  As a method of supplying the anode fuel and the cathode fuel to the respective catalyst layers 132b and 133b, (1) a method of forcibly feeding using an auxiliary device such as a pump (active type), and (2) an auxiliary device There are two methods that are not used, for example, a passive type in which the fuel is exposed to the atmosphere by exposing the catalyst layer to the atmosphere due to capillary action or natural fall when the fuel is a liquid, and ( It is also possible to combine 1) and (2). (1) has the advantage that by extracting the water produced on the cathode side, high-concentration methanol can be used as the fuel, and high output can be achieved by air supply, but a fuel supply system is provided. Therefore, there is a drawback that miniaturization is difficult. Although (2) has the advantage that it can be downsized, it has a drawback that the fuel supply is likely to be rate-limiting and it is difficult to produce a high output.

  Since the single cell voltage of the fuel cell is generally 1 V or less, the single cells are used by stacking in series according to the required voltage of the load. As the stacking method, “planar stacking” in which single cells are arranged on a plane and “bipolar stacking” in which single cells are stacked via separators having fuel flow paths formed on both sides thereof are used. The former is suitable for a small fuel cell because the cathode electrode (air electrode) comes out on the surface, so that air can be easily taken in and can be made thin. In addition to this, a method of applying MEMS technology, performing fine processing on a silicon wafer, and stacking has been proposed.

  Fuel cells are considered for various uses such as for automobiles, homes, and portable devices.In particular, direct methanol fuel cells are advantageous in that they can be reduced in size and weight and do not require charging. It is expected to be used as an energy source for various portable devices and portable devices. For example, mobile devices that can be preferably applied include mobile phones, mobile laptop computers, electronic still cameras, PDAs, video cameras, portable game machines, mobile servers, wearable personal computers, mobile displays, and the like. Examples of portable devices that can be preferably applied include portable generators, outdoor lighting devices, flashlights, and electric (assist) bicycles. It can also be preferably used as a power source for industrial or household robots or other toys. Furthermore, it is also useful as a power source for charging secondary batteries mounted on these devices.

  Next, examples of the present invention will be described. In each of the following examples, details will be described in Example 1, and only the conditions different from Example 1 will be described for Examples 2 to 8. In addition, Examples 1-3, 7, and 8 are examples of the embodiment of this invention, and Examples 4-6 are comparative experiments with respect to Examples 1-3.

The raw material A was flash-concentrated with a flash device 26 and dried. The dried raw material A and the solvent were mixed in the following composition, and the solid content of the raw material A was dissolved in the solvent to produce a 20 wt% solid electrolyte dope 24. This dope 24 is referred to as dope A in the following description. The raw material A is 20% Nafion (registered trademark) Dispersion Solution DE2020 (manufactured by DuPont, USA).
-Raw material A after drying; 100 parts by weight-Solvent: 400 parts by weight of perfluorohexane

[Manufacture of solid electrolyte film 62]
The casting film 81 was cast from the casting die 81 to the casting band 82 running on the dope A. The temperature of the casting chamber 63 was kept at 50 ° C. using a temperature control device 97. The casting film 24a on the casting band 82 is sent in parallel to the drying air from the first air duct 91 having a two-dimensional nozzle and the casting films 24a from the second to fourth air ducts 92 to 94. Dried by a dry air. In the first air duct 91, dry air at 50 ° C. and 10% RH is blown at an air surface 24b of the casting film 24a at a wind speed of 2 m / sec. Sprayed on. Then, the 2nd ventilation duct 92 ventilated the dry wind whose temperature is 50 degreeC with the wind speed of 2 m / sec. A skin layer 24c was formed on the air surface 24b of the casting film 24a on the casting film 24a after 120 seconds from immediately after casting. The thickness of the skin layer 24c was 10 μm. Thereafter, the third blowing duct 93 was used to apply dry air having a wind speed of 10 m / sec and a temperature of 40 ° C. to the casting film 24c. Moreover, the 4th ventilation duct 94 applied the dry wind whose temperature is 30 degreeC with the wind speed of 10 m / sec to the casting film 24c. The oxygen concentration in the dry atmosphere on the casting band 82 was maintained at 5 vol%. In order to maintain this oxygen concentration at 5 vol%, the air was replaced with nitrogen gas. Further, in order to condense and recover the solvent in the casting chamber 63, a condenser 98 was provided, and its outlet temperature was set to -10 ° C.

  For 10 seconds after casting, a wind shielding plate 95 was installed so that the dry air did not directly hit the casting bead and the casting film 24a, and the static pressure fluctuation in the vicinity of the casting die 81 was suppressed to ± 1 Pa or less. When the amount of residual solvent in the casting film 24a reached 30% by weight on the dry basis, the film was peeled off from the casting band 82 as the wet film 62 while being supported by the peeling roller 109. In order to suppress the peeling failure, the peeling speed (peeling roller draw) was appropriately adjusted in the range of 100.1% to 110% with respect to the speed of the casting band 82. The surface temperature of the peeled film 62 was 25 ° C. The solvent gas generated by drying was condensed and liquefied by a condenser 66 at −10 ° C. and recovered by a recovery device 99. The recovered solvent was adjusted so that the water content was 0.5% or less. The drying air from which the solvent was removed was heated again and reused as drying air. The film 62 was transported through the roller of the cross section 101 and sent to the tenter 64.

  In the tenter 64, both ends of the film 62 are held by the clip 64a, and are conveyed in the drying zone of the tenter 64 as the clip 64a moves. During this time, the film 62 was dried with a drying air at 50 ° C. until the volatile content relative to the solid content became 15 wt%. The film 62 released from the clip at the exit of the tenter 64 was subjected to ear cutting at both ends of the film 62 serving as a clip gripping portion by an ear cutting device 67. The trimmed film was conveyed while being dried at 50 to 70 ° C. to obtain a film 62 in a dry state with a residual solvent amount of less than 1%. About the obtained film 62, each evaluation mentioned later was implemented. The evaluation results are shown in Table 1. The numbers of the evaluation items in Table 1 correspond to the numbers given to the following evaluation items.

The raw material B and the solvent were mixed in the following composition, and the raw material B was dissolved in the solvent to produce a 20 wt% solid electrolyte dope 24. This dope 24 is referred to as dope B in the following description. The raw material B is sulfonated polyacrylonitrile butadiene styrene having a sulfonation degree of 35%.
-Raw material B; 100 parts by weight-Solvent: 400 parts by weight of N, N-dimethylformamide

In addition, the raw material B was manufactured with the following synthesis methods.
(1) Synthesis of 4- (4- (4-pentylcyclohexyl) phenoxymethyl) styrene After reacting substances having the following composition at 100 ° C. for 7 hours, the resulting reaction solution was cooled to room temperature, Water was added for crystallization. After filtering the crystallization solution, the obtained filtrate was washed with an aqueous solution of water / acetonitrile = 1/1 and air-dried to obtain 4- (4- (4-pentylcyclohexyl) phenoxymethyl) styrene.
-14 parts by weight of 4- (4-pentylcyclohexyl) phenol-9 parts by weight of 4-chloromethylstyrene-11 parts by weight of potassium carbonate-66 parts by weight of N, N-dimethylformamide

(2) Synthesis of graft copolymer A mixture having the following composition was heated to 60 ° C.
-Polybutadiene latex 100 parts-Potassium rosinate 0.83 parts-Dextrose 0.50 parts by weight-Sodium pyrophosphate 0.17 parts by weight-Ferrous sulfate 0.08 parts by weight-Water 250 parts by weight

Thereafter, a mixture having the following composition was added dropwise over 60 minutes to the above mixture to carry out a polymerization reaction.
Acrylonitrile 21 parts by weight 4- (4-4-pentylcyclohexyl) phenoxymethyl) styrene 62 parts by weight t-dodecylthiol 0.5 parts by weight Cumene hydroperoxide 3.0 parts by weight

  After completion of the dropwise addition, 0.2 parts by weight of cumene hydroperoxide was added thereto, followed by cooling for 1 hour to obtain a latex. The obtained latex was put in 60 ° C. and 1% sulfuric acid, and heated to 90 ° C. for coagulation. This was thoroughly washed with water and dried to obtain a graft copolymer.

(3) Synthesis of raw material B by sulfonation of graft copolymer 100 parts by weight of the graft copolymer obtained in (2) was dissolved in 1300 parts by weight of methylene chloride, and the resulting solution was kept at 0 ° C. or lower. While, 13 parts by weight of concentrated sulfuric acid was slowly added thereto. This was stirred for 6 hours to cause precipitation. After removing the solvent, the precipitate was dried to obtain sulfonated polyacrylonitrile butadiene styrene as raw material B. The introduction rate of sulfonic acid groups by titration was 35%.

[Manufacture of solid electrolyte film 62]
The temperature of the casting chamber 63 was 80 ° C. The first air duct 91 and the second air duct 92 have a wind direction in substantially the same direction as the moving direction of the casting film 24a, and cast dry air at 80 ° C. and 10% RH at a wind speed of 2 m / sec. The skin layer 24c was generated on the air surface 24b of the casting film 24a on the air surface 24b of the casting film 24a after 150 seconds had elapsed since the casting. The thickness of the skin layer 24c was 10 μm. The surface of the film 62 at the time of stripping the drying air of the third air duct 93 at a wind speed of 10 m / sec at a temperature of 100 ° C., the air at the air speed of 10 m / sec at a temperature of 80 ° C. A film 62 was produced under the same conditions as in the first example except that the temperature was 60 ° C, the drying air temperature in the drying zone of the tenter 64 was 140 ° C, and the drying temperature in the drying chamber 69 was 140 to 160 ° C. . The evaluation results on the obtained film 62 are shown in Table 1.

The raw material C and the solvent were mixed in the following composition, and the raw material C was dissolved in the solvent to produce a 20 wt% solid electrolyte dope 24. This dope 24 is referred to as dope C in the following description. The raw material C is a sulfopropylated polyethersulfone having a sulfonation degree of 35%, and was synthesized based on the synthesis method described in JP-A No. 2002-110174.
-Raw material C; 100 parts by weight-Solvent: N-methylpyrrolidone 400 parts by weight

[Manufacture of solid electrolyte film 62]
The temperature of the casting chamber 63 was 80 ° C. The first air duct 91 and the second air duct 92 have a wind direction in substantially the same direction as the moving direction of the casting film 24a, and cast dry air at 80 ° C. and 10% RH at a wind speed of 2 m / sec. It sprayed on the air surface 24b of the film | membrane 24a. A skin layer 24c was formed on the air surface 24b of the casting film 24a on the casting film 24a after 150 seconds from immediately after casting. The thickness of the skin layer 24c was 12 μm. The surface of the film 62 at the time of stripping the drying air of the third air duct 93 at a wind speed of 10 m / sec at a temperature of 140 ° C., the air at the air speed of 10 m / sec at a temperature of 140 ° C. A film 62 was produced under the same conditions as in the first example except that the temperature was 70 ° C, the drying air temperature in the drying zone of the tenter 64 was 160 ° C, and the drying temperature in the drying chamber 69 was 160 to 180 ° C. . The evaluation results on the obtained film 62 are shown in Table 1.

  In Example 1, except that the wind speed of the first air duct 91 was 12 m / sec and the skin layer 24c was formed on the air surface 24b of the casting film 24a 40 seconds after casting and dried. The dope A was prepared in the same manner as in Example 1 to produce a film 62. The evaluation results on the obtained film 62 are shown in Table 1.

  In Example 2, except that the wind speed of the first air duct 91 was 12 m / sec and the skin layer 24c was formed on the air surface 24b of the casting film 24a 45 seconds after casting and dried. Dope B was prepared in the same manner as in Example 2 to produce film 62. The evaluation results on the obtained film 62 are shown in Table 1.

  In Example 3, except that the air speed of the first air duct 91 was set to 12 m / second, and the skin layer 24c was formed on the air surface 24b of the casting film 24a 45 seconds after the casting and dried. The dope C was adjusted in the same manner as in Example 3 to produce a film 62. The evaluation results on the obtained film 62 are shown in Table 1.

In this example, the compound shown in Chemical Formula 3 was used as the solid electrolyte. However, protonation for obtaining chemical formula 3, that is, acid treatment, was carried out in the film production process as described below, not before the dope production. An unprotonated product of Chemical Formula 3, that is, a solid electrolyte precursor, is used as a raw material D. Moreover, this raw material D was dissolved in a solvent to obtain a dope for casting. The method for making this dope is the same as the method for making the dope 24 in the first embodiment. The solvent is a mixture of the solvent component 1 that is a good solvent for the raw material D and the solvent component 2 that is a poor solvent for the raw material D. In Example 7, X in Chemical Formula 3 is Na, Y is SO ₂ , Z is Chemical Formula 4 (I), n is 0.33, m is 0.67, number average molecular weight Mn is 61000, and weight average molecular weight. Mw is 159000.
-Raw material D; 100 parts by weight-Solvent component 1; 256 parts by weight of dimethyl sulfoxide-Solvent component 2; 171 parts by weight of methanol

  A polyethylene terephthalate (PET) film was used as the support. This PET film has a long shape and is continuously conveyed. The casting film formed on this support was conveyed to the casting chamber 63. The temperature of the casting chamber 63 was 80 ° C. The first air duct 91 and the second air duct 92 have a wind direction in substantially the same direction as the moving direction of the casting film 24a, and cast dry air at 80 ° C. and 10% RH at a wind speed of 2 m / sec with respect to the casting film 24a. It sprayed on the air surface 24b of the film | membrane 24a. Then, a skin layer 24c was formed on the air surface 24b of the casting film after 150 seconds had passed immediately after casting. The thickness of the skin layer 24c was 13 μm. The drying air of the third air duct 93 was 140 ° C. at a wind speed of 10 m / sec, and the drying air of the fourth air duct 94 was 140 ° C. at a wind speed of 10 m / sec. The cast film provided with the skin layer was introduced into a tank storing water at 30 ° C., and the cast film was peeled off from the PET film in this tank to obtain a precursor film containing a raw material D as a precursor. The contact time between the water and the cast film was 5 minutes.

  Next, water was removed by air shower from the surface of the precursor film taken out of the water bath. This precursor film was conveyed to the tenter 64. In the tenter 64, the film 62 was dried with a drying air at 120 ° C. so that the residual solvent amount was less than 10% by weight with respect to the dry amount standard. The drying time in the tenter 64 is 10 minutes. The precursor film was detached from the clip 64 a at the outlet of the tenter 64, and both end portions gripped by the clip 64 a were cut and removed by an ear-cut device 67 provided downstream of the tenter 64.

  The precursor film from which both side ends were removed was subjected to an acid treatment, and a cleaning process was performed. The acid treatment is a treatment in which the precursor film is brought into contact with an aqueous acid solution. In this example, an acid aqueous solution was continuously supplied to the liquid tank, and the precursor film was immersed in this aqueous solution to perform acid treatment. By this acid treatment, the structure of the raw material D becomes a structure represented by the general formula of Chemical Formula 3. That is, the precursor film becomes the film 62 including the solid electrolyte by the acid treatment. After the acid treatment, the film 62 was washed with water. The film 62 after the cleaning process was sent to the drying chamber 69 and dried at 120 to 185 ° C. The evaluation results for the obtained film 62 are shown in Table 1.

The raw material D of the solid electrolyte precursor in Example 7 was replaced with the raw material E. In this raw material E, X in the chemical formula 3 is Na, Y is SO ₂ , Z is (I) and (II) in the chemical formula 4, n is 0.33, m is 0.67, number average molecular weight Mn is 68000, amount The average molecular weight Mw is 200,000. In Chemical Formula 4, (I) is 0.7 mol% and (II) is 0.3 mol%. As shown below, a mixture of a solvent component 1 that is a good solvent for the raw material E and a solvent component 2 that is a poor solvent for the raw material E was used. Other conditions were the same as in Example 7, and a film 62 was produced. The evaluation results on the obtained film 62 are shown in Table 1.
-Raw material E; 100 parts by weight-Solvent component 1; 200 parts by weight of dimethyl sulfoxide-Solvent component 2; 135 parts by weight of methanol

  The following evaluation was implemented about the film 62 obtained in Examples 1-8. The evaluation results are shown in Table 1. The numbers of the evaluation items in Table 1 correspond to the numbers given to the following evaluation items.

1. Thickness The thickness of the film 62 was continuously measured using an electronic micrometer manufactured by Anritsu Electric Co., Ltd. at a speed of 600 mm / min. Data obtained by the measurement was recorded on the chart paper at a scale of 1/20 and a chart speed of 30 mm / min. And after measuring with respect to a data curve with a ruler, the average value of thickness and the dispersion | variation in the thickness with respect to this average value were calculated | required based on the measured value. In Table 1, (a) represents the average thickness (unit: μm), and (b) represents the thickness variation (unit: μm) relative to (a).

2. Number of Defects The light was applied to the area of the entire width x 1 m of the film 62 and reflected, and the defect part such as deformation was visually detected by the reflected light. Then, the defect location detected visually was confirmed with the polarizing microscope, and the number of the defect locations per 1 mm < ² > was counted. Note that deformations made after sampling, such as scratches, were excluded from the count.

3. Ionic conductivity measurement About the obtained film 62, ten measurement locations were selected every 1 m along the longitudinal direction. Ten of them were punched out as a circular sample having a diameter of 13 mm. Each sample was sandwiched between two stainless steel plates, and ion conductivity was measured by an AC impedance method using Solartron 1470 and 1255B. The measurement was performed under the conditions of 80 ° C. and relative humidity of 95%. As shown in Table 1, the ionic conductivity is shown as an AC impedance value (unit: S / cm).

4). Output density of fuel cell 141 A fuel cell 141 was produced using the film 62, and the output of the fuel cell 141 was measured. The production method of the fuel cell 141 and the measurement method of the power density are as follows.

(1) Preparation of catalyst sheet A used as catalyst layers 132b and 133b 2 g of platinum-supporting carbon and 15 g of a solid electrolyte (5% DMF solution) were mixed and dispersed for 30 minutes with an ultrasonic disperser. The average particle size of the dispersion was about 500 nm. The obtained dispersion was applied onto a carbon paper having a thickness of 350 μm and dried, and then the carbon paper was punched into a circle having a diameter of 9 mm to prepare a catalyst sheet A. The platinum-supporting carbon was obtained by supporting 50 wt% platinum on Vulcan XC72, and the solid electrolyte was the same as that for manufacturing the film 62.

(2) Production of MEA 131 Catalyst sheet A was laminated on both surfaces of solid electrolyte film 62 so that the coating film was in contact with film 62, and thermocompression bonded at 80 ° C. and 3 MPa for 2 minutes to produce MEA 131.

(3) Output Density of Fuel Cell 141 The MEA 131 obtained in (2) above was set in the fuel cell shown in FIG. 5, and a 15 wt% aqueous methanol solution was injected into the opening 151 on the anode electrode side. At this time, the opening 152 on the cathode electrode side was in contact with the atmosphere. The anode electrode 132 and the cathode electrode 133 were connected by a multichannel battery evaluation system (Solartron 1470), and the output density (unit: W / cm ² ) was measured.

  From the results of the above examples, according to the present invention, it is possible to continuously produce a solid electrolyte film with excellent flatness and suppressed defects, and the obtained solid electrolyte film is used as a solid electrolyte layer of a fuel cell. It turns out that it can use suitably.

It is the schematic of dope manufacturing equipment. It is the schematic of a film manufacturing equipment. It is the schematic which shows the 1st ventilation duct periphery. It is the schematic which shows the flow of the dry wind by the 1st ventilation duct of various forms. It is sectional drawing of an electrode membrane composite. It is sectional drawing of a fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dope manufacturing equipment 24 Dope 24b Air surface 24c Skin layer 33 Film manufacturing equipment 62 Solid electrolyte film 64 Tenta 64a Clip 69 Drying chamber 91-94 Air duct 131 Electrode membrane composite (MEA)
132 Anode electrode 133 Cathode electrode 141 Fuel cell 146 Current collector

Claims (14)

A casting process in which a casting film is formed by casting from a casting die on a support that runs a dope containing a solid electrolyte and an organic solvent;
A peeling step of peeling the cast film from the support as a solid electrolyte film containing the organic solvent;
A drying step of drying the solid electrolyte film;
Have
The air surface side of the casting membrane is dried, and a skin layer having a surface tension different from that of the support side is generated on the air surface side of the casting membrane after 60 seconds from immediately after casting. A method for producing a solid electrolyte film.   2. The method for producing a solid electrolyte film according to claim 1, wherein in the drying step, the skin layer is generated by applying dry air having a wind speed of less than 3 m / sec to the air surface.   A slit nozzle that emits the drying air from a slit that is provided to face the air surface, and a portion near the casting film from the second opening that emits the drying air from a first opening that is provided to face the air surface. The method for producing a solid electrolyte film according to claim 1, wherein the drying is performed by a chamber having any one of a two-dimensional nozzle for sucking air.   The method for producing a solid electrolyte film according to any one of claims 1 to 3, wherein the drying is performed on the cast film having a residual solvent amount of 150 wt% or more and 500 wt% or less on a dry basis.   The method for producing a solid electrolyte film according to any one of claims 1 to 4, wherein the organic solvent is a mixture of a poor solvent and a good solvent for the solid electrolyte.   6. The method for producing a solid electrolyte film according to claim 5, wherein a weight ratio of the poor solvent in the organic solvent is 10% or more and less than 100%.   The method for producing a solid electrolyte film according to claim 5 or 6, wherein the good solvent contains dimethyl sulfoxide, and the poor solvent contains an alcohol having 1 to 5 carbon atoms.   The method for producing a solid electrolyte film according to any one of claims 1 to 7, wherein the solid electrolyte is a hydrocarbon polymer.   The method for producing a solid electrolyte film according to claim 8, wherein the hydrocarbon polymer is an aromatic polymer having a sulfonic acid group. The method for producing a solid electrolyte film according to claim 9, wherein the aromatic polymer is a copolymer represented by the general formulas (I) to (III) of Chemical Formula 1.

(However, X is H, Y is SO ₂ , Z is the structure shown in Chemical Formula (I) or (II), and n and m satisfy 0.1 ≦ n / (m + n) ≦ 0.5. .)

A casting apparatus for casting a dope containing a solid electrolyte and an organic solvent from a casting die on a traveling support to form a casting film;
First drying that dries the air surface side of the casting membrane and generates a skin layer having a surface tension different from that of the support on the air surface side of the casting membrane after 60 seconds from immediately after casting. Equipment,
A peeling device for peeling the cast film from the support as a solid electrolyte film containing the organic solvent;
A second drying device for drying the solid electrolyte film;
A facility for producing a solid electrolyte film, comprising:   A solid electrolyte film produced by the production method according to claim 1. A solid electrolyte film according to claim 12;
An anode electrode that is provided in close contact with one surface of the solid electrolyte film and generates protons from a hydrogen-containing substance supplied from the outside;
An electrode membrane composite comprising: a cathode electrode that is provided in close contact with the other surface of the solid electrolyte film and synthesizes water from the proton that has passed through the solid electrolyte film and a gas supplied from the outside. body. The electrode membrane composite according to claim 13,
A fuel cell comprising: a current collector provided in contact with an electrode of the electrode membrane composite; and a current collector for transferring electrons to and from the anode electrode and the cathode electrode.

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