JP2007042590A - Solid electrolyte film and its manufacturing method, equipment, electrode membrane assembly, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously manufacture a film having a constant quality and high ion conductivity by making a solid electrolyte into a film continuously with improved drying speed. <P>SOLUTION: A dope 24 containing a solid electrolyte is made to flow and cast on a moving casting band 82 and a cast film is formed. The film 62 formed by separating the cast film from the casting band 82 is sent to a tenter 64, and by holding the both end parts by a clip 64a and extending in width direction, it is dried. The film 62 is dried in a drying chamber 69 by supporting by a plurality of rollers 68. By a pressure control device 210 connected to a casting chamber 63, the tenter 64, and the drying chamber 69, the vicinity of the cast film and the film 62 in each chamber is decompressed to 600 hPa or less. Since the drying speed of the cast film and the film 62 can be improved and dried, a solid electrolyte having a constant quality can be manufactured continuously while shortening manufacturing time. This solid electrolyte film does not contain impurities and develops a high ion conductivity when used for a fuel cell. <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 and its The present invention relates to a manufacturing method, equipment, 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 for mixing an electrolyte and a plasticizer. Patent Document 2 proposes a method for producing a proton conductive membrane by synthesizing an inorganic compound in a solution containing an aromatic polymer material having a sulfonic acid group and removing the solvent. . 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.
JP-A-9-320617 JP 2001-307752 A JP 2002-231270 A JP 2004-79378 A JP 2004-131530 A

  However, in Patent Document 1, the melt film-forming method is denied, and the problem that impurities contained in the raw material remain in the film is not solved in the manufacturing method. In addition, all the methods of Patent Documents 2 to 5 are manufacturing methods on a small scale, and are not considered methods for mass production.

  Therefore, as a result of intensive studies, the present inventors paid attention to a melt film forming method and a solution film forming method, which are well known as methods for forming a polymer into a film. 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. In addition, there is an advantage that a film excellent in flatness and smoothness can be produced as compared with the former film.

  However, although the method of Patent Document 4 applies the solution casting method, it is described that various solid electrolyte films can be produced by the solution casting method, but there is no description of a specific method. In general, the solution casting method has a problem that it takes a long time to dry a cast membrane or a film. Therefore, even when applied to a solid electrolyte film, it is a problem to establish a method for producing a solid electrolyte film that shortens the drying time and can be continuously and mass-produced.

  The present invention aims to solve the above-mentioned problems, and has ionic conductivity, in particular, ions are protons, high proton conductivity, which is an index of the conductivity, and excellent properties such as excellent mechanical strength. The present invention provides a production method capable of producing a solid electrolyte film continuously and in large quantities in a short production time while maintaining a constant quality by shortening the drying time of a cast film or film.

  Therefore, a method for producing a solid electrolyte film according to the present invention includes a casting film forming step of casting a dope containing a solid electrolyte and an organic solvent from a casting die on a support to form a casting film, An organic solvent contained in the casting film or the film by depressurizing the vicinity of at least one of the casting film and the film by pressure control means, and stripping the casting film as a film from the support. And a reduced-pressure drying step of drying the cast film or film by a drying means while increasing the partial pressure.

  It is preferable to reduce the pressure in the vicinity of at least one of the cast film and the film to 600 hPa or less by the pressure control means.

  The first reduced pressure drying step is a step of stretching the film in the width direction while drying while transporting the film gripped on both sides by the gripping means, and the second reduced pressure drying step is stretched in the width direction. The film is preferably dried while being conveyed while being supported by a plurality of rollers.

  The organic solvent is preferably a mixture of a poor solvent and a good solvent for the solid electrolyte. The weight ratio of the poor solvent in the organic solvent is preferably 10% or more and less than 100%. The good solvent preferably contains dimethyl sulfoxide, and the poor solvent preferably contains an alcohol having 1 to 5 carbon atoms.

The solid electrolyte is preferably a hydrocarbon polymer, and the hydrocarbon polymer is more preferably an aromatic polymer having a sulfonic acid group, and the aromatic polymer is represented by the general formula (I) It is more preferable that the copolymer is composed of each structural unit represented by (III) to (III). However, in Chemical formula 3, X is H, Y is SO ₂ , Z is the structure shown in Chemical formula (I) or (II), and n and m are 0.1 ≦ n / (n + m) ≦ 0. .5 is satisfied.

  The production facility for a solid electrolyte film of the present invention includes a casting film forming apparatus for casting a dope containing a solid electrolyte and an organic solvent from a casting die onto a support, and a casting film. A film forming apparatus that peels off as a film from a support, a pressure control means, and a drying means, and the pressure control means depressurizes the vicinity of at least one of the casting film and the film, thereby casting film or film And a reduced-pressure drying device that dries the cast film or film by a drying means while increasing the partial pressure of the organic solvent contained therein.

  The first vacuum drying apparatus grips the pressure control means capable of reducing the pressure in the vicinity of the film, the drying means for drying the film, and both end portions of the film, and expands or contracts the width of the film by adjusting the width. The second vacuum drying apparatus includes a pressure control means capable of reducing the pressure in the vicinity of the film, a drying means for drying the film, and a film while supporting the film. It is preferable that it is a conveyance decompression drying apparatus provided with a some roller.

  The solid electrolyte film of the present invention is manufactured by any one of the above manufacturing methods.

  The electrode membrane composite of the present invention is provided with the above solid electrolyte film and 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 a cathode electrode that is provided in close contact with the other surface of the solid electrolyte film and synthesizes water composed of protons that have passed through the solid electrolyte film and gas supplied from the outside.

  Furthermore, the present invention comprises the above electrode membrane composite, and a current collector provided in contact with the electrode of the electrode membrane composite and for transferring electrons to and from the anode and cathode electrodes. The fuel cell includes the characteristic fuel cell.

  According to the present invention, a solid electrolyte film having high ionic conductivity and excellent properties such as mechanical strength can be obtained. Further, by reducing the pressure at the time of drying the cast film and the film, the partial pressure of the solvent contained in each film is increased, so that the drying time can be shortened. In addition, since the operation can be performed at a low drying temperature, an effect such as reduction in fuel, that is, reduction in cost can be expected. Therefore, according to the present invention, since a solid electrolyte film can be continuously produced in a short time while maintaining a constant quality, a high quality solid electrolyte film can be continuously and mass-produced. And the electrode membrane assembly using this solid electrolyte film expresses an excellent electromotive force when used in a fuel cell.

  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 gazettes are 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) 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 hydrogen atom, and casting this on a support. The solid electrolyte film made of a polymer having the structure of Chemical Formula 3 can be produced by peeling off the precursor film as a film) and substituting the precursor film with proton to change X to H.

  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 hydrogen atoms, 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 50% 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, and particularly with respect to before immersion. What the fall rate of the ionic conductivity after immersion is 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.

  Regarding durability, before and after the time-lapse test immersed in 50% methanol at a constant temperature, each change rate of weight, ion exchange capacity, and methanol diffusion coefficient is preferably 20% or less, preferably 15% or less. Some 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 50% methanol, 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. 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 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 in advance by filtration. In the following description, the obtained solution is referred to as a dope.

  The organic solvent used for the dope (sometimes simply referred to as a solvent) may be any 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 a dope so that it may become the range of 1 to 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 a dope so that it may become the range of 1 to 30 weight% with respect to the total weight when it is set as a film.

  Further, when the obtained solid electrolyte film is used in a fuel cell, an active metal catalyst that promotes the oxidation-reduction 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 first filtration device 22 that filters the mixed liquid 16 that has come out to form a dope 24, a flash device 26 that adjusts the concentration of the dope 24, and a second filtration device 27 that filters the concentration-adjusted dope 24. With. Further, the dope manufacturing facility 10 is provided with a recovery device 28 for recovering the solvent generated in the flash device 26 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.

  The flow of manufacturing the dope 24 using the dope manufacturing facility 10 will be described below. 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. Further, from the additive tank 15, a necessary amount of an additive solution prepared by mixing an additive with a desired solvent in advance 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 addition, it is preferable to use the solvent used when preparing dope for the solvent which prepares an additive solution.

  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 encloses the outer surface thereof, a jacket 46 supplied with a heat transfer medium between the mixing tank 17, a first stirrer 48 rotated by a motor 47, and a second stirrer 52 rotated by a motor 51, It has. The mixing tank 17 supplies the heat transfer medium to the inside of the jacket 46 and circulates it to adjust the temperature inside. The internal temperature of the mixing tank 17 is preferably in the range of −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 so that the solid electrolyte and the solvent can be mixed efficiently and effectively, and the second stirrer 52 is a dissolver type eccentric stirrer. Preferably there is.

  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 body (not shown) and a jacket (not shown) for passing a heat transfer medium between the tube body, and further, the mixed liquid 16 is added. It is preferable to have a pressurizing part (not shown) for pressing. 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 of proceeding dissolution while cooling the mixed solution 16 so that the temperature of the mixed solution 16 is maintained or 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 liquid mixture 16 is brought to about room temperature by the temperature controller 21, it is filtered by the first filtration device 22 to remove foreign matters such as impurities and aggregates, thereby obtaining a dope 24. The filter used in the first filtration device 22 preferably has an average pore diameter of 50 μm or less, more preferably 10 μm or less.

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

  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 first 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 second 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 second 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 perform a bubble removal process before sending it to the second 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 flash evaporation in the flash device 26 is condensed and recovered as a liquid by a recovery device 28 having a condenser (not shown). 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.

  With the above manufacturing method, the dope 24 having a solid electrolyte concentration or a precursor concentration of 5 wt% or more and 50 wt% or less can be manufactured. The solid electrolyte concentration or precursor 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]
Next, a method for producing a solid electrolyte film will be described. FIG. 2 is a schematic view of the film manufacturing equipment 33 used in the present embodiment. However, FIG. 2 shows an example of a film manufacturing facility according to the present invention, and the present invention is not limited to the embodiment shown here.

  In the film manufacturing facility 33, the dope 24 before casting is filtered, and a filtering device 61 for removing coarse particles and foreign matters contained in the dope 24 and the filtered dope 24 are flowed on the support. The casting chamber 63 for forming the casting film 24a and the casting film 24a is peeled off from the support as the film 62, and then the film 62 is held while being transported while holding both side ends of the film 62. A tenter 64 for drying, an edge-cutting device 67 for cutting off both end portions of the film 62, a drying chamber 69 for drying the film 62 over a plurality of rollers 68, and a cooling chamber for cooling the film 62 71, a static elimination device 72 for reducing the amount of charge of the film 62, a knurling roller 73 for embossing the side ends, and a winding chamber 76 for winding the film 62. Further, a pressure control device 210 connected to the casting chamber 63, the tenter 64, and the drying chamber 69 is provided.

  A stirrer 78 that is rotated by a motor 77 is attached to the stock tank 32. By stirring the dope 24 by rotating the stirrer 78, precipitation and aggregation of solids contained therein are suppressed. The stock tank 32 is connected to the filtration device 61 via the pump 80.

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. In addition, a temperature controller that controls the temperature of the casting die 81 is preferably 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.

  Further, the film manufacturing facility 33 may be provided with a thickness measuring machine such as an infrared thickness gauge, and feedback control to the automatic thickness adjusting mechanism may be performed by an adjustment program based on the thickness profile and a detection result by the thickness measuring machine. 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. The 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 casting band 82 below the casting die 81 is stretched around the rotating rollers 85 and 86 and is continuously conveyed by the drive rotation of at least one of the rotating rollers.

  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 organic solvent 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 the present embodiment, a heat transfer medium flow path (not shown) is formed in the rotation rollers 85 and 86, and the heat transfer medium maintained at a predetermined temperature passes through the flow path to rotate. The temperature of the 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.

Instead of the rotating rollers 85 and 86 and the casting band 82, a rotating drum (not shown) can be used as a support. 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 band 82, there are first to third air ducts 91 to 93 that blow wind to evaporate the solvent of the casting film 24a, and wind that disturbs the shape of the casting film 24a. In order to suppress hitting 24a, the first air duct disposed closest to the casting bead among the air ducts is provided with a wind shielding plate 94.

  In the vicinity of the casting band 82, there are first to third air ducts 91 to 93 that blow wind to evaporate the solvent of the casting film 24a, and wind that disturbs the shape of the casting film 24a. And a wind shield 94 for suppressing the contact with 24a.

  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 organic solvent condensed and liquefied by the condenser 98 is provided outside the casting chamber 63.

  A blower 102 is provided in the transition portion 101 downstream of the casting chamber 63. Further, a tenter 64 is provided downstream thereof. 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 water 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 manufacturing the film 62 using the film manufacturing facility 33 will be described.

  In the stock tank 32, the dope 24 is always made uniform by the rotation of the stirrer 78. Thereby, precipitation and aggregation of the solid content in the dope 24 are suppressed until it is cast. Here, the dope 24 can be appropriately mixed with various additives even during the stirring. And the dope 24 is filtered with the filtration apparatus 61, and the foreign material of a size more than predetermined particle size and a gel-like foreign material are removed.

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 preferably set to 0.01 m / min or less. At the time of casting, the casting amount of the dope 24 is determined in consideration of the concentration of the dope 24 to be used and the desired thickness of the film product.

  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) that detects the positions of both ends of the casting band 82 and a position adjuster (not shown) that adjusts the position of the casting band 82 according to the detection data from 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. The temperature of the casting chamber 63 is preferably set to −10 ° C. to 57 ° C. by the temperature controller 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.

  The inside of the casting chamber 63 is preferably kept as low as possible by adsorbing and recovering the evaporated solvent as described above, and the humidity is preferably 50% RH or less. When the humidity is high, the casting membrane absorbs moisture in the air, so there are cases where the layers are separated and the porosity is increased, but by reducing the humidity as described above, A few cast films can be formed. More preferably, the humidity is 20% RH or less. In this embodiment, 10% RH is set.

  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 bead has a predetermined pressure value. The reduced pressure value is preferably set to −2500 Pa to −10 Pa from the area on the downstream side 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 maintained 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.

  After the casting film 24a has a self-supporting property, the casting film 24a is peeled off from the casting band 82 while being supported by the peeling roller 109 to form a film 62 containing a solvent. The film 62 is fed to the tenter 64 after being supported by a plurality of rollers and conveyed through the crossing section 101. 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 by the clip 64a and conveyed. The gripping means may be a pin instead of a 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 at least any one of the crossover part 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.

  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.

  The film 62 from which both end portions have been cut and removed is sent to the drying chamber 69, where drying is further promoted. 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 10% 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.

  The film 62 is cooled to approximately room temperature in the cooling chamber 71. When 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.

  In the solution casting method, various steps such as a drying step and a side edge portion excision and removal step are performed before the film (solid electrolyte film) peeled off from the support is wound up. In each of these processes or between each process, the film is mainly supported or conveyed by a roller. These rollers include a driving roller and a non-driving roller, and the non-driving roller is mainly used for determining a film conveyance path and improving conveyance stability.

  The neutralizing device 72 sets the charged voltage while the film 62 is being conveyed to a predetermined value. 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.

  Details of the drying method, which is a specific method of the present invention, will be described below.

  As shown in FIG. 2, a pressure control device 210 is connected to the casting chamber 63, the tenter 64, and the drying chamber 69 of this embodiment. When the casting film 24a or the film 62 is dried in each chamber, the pressure control device 210 reduces the pressure so that the pressure in the vicinity of the casting film 24a or the film 62 becomes a desired degree of pressure reduction. In this case, it is preferable to depressurize the vicinity of the casting film or film to be depressurized to 600 hPa or less. Thereby, the partial pressure of the organic solvent contained in the cast film or film can be increased to lower the boiling point, and as a result, the drying temperature can be decreased. In addition, since the drying speed can be improved by lowering the drying temperature, it is possible to reduce the drying time, that is, the manufacturing time. Furthermore, when the pressure is reduced as described above, the film can be dried while suppressing the occurrence of unevenness in drying, so that a film product having excellent flatness and smoothness can be produced. The degree of decompression may be 600 hPa or less with respect to the atmosphere, but the higher the degree of decompression, the higher the drying rate. More preferably, it is 300 hPa or less, and it is particularly preferably 200 hPa or less. As the pressure control device 210, a commercially available decompressor that can arbitrarily adjust the degree of decompression may be used.

  In the present embodiment, as a method for defining the degree of decompression in each chamber, the vapor pressure is defined for N-methylpyrrolidone (NMP) used as the solvent of the dope 24, the value is grasped, and shown below. By comparing with the NMP saturated vapor pressure, the degree of decompression in each room is obtained. For example, the NMP saturated vapor pressure is 1013 hPa (202 ° C.), 267 hPa (150 ° C.), 33 hPa (100 ° C.). However, when NMP is not used as a solvent, the degree of pressure reduction may be defined by arbitrarily extracting from the solvent used and comparing the saturated vapor pressure with the vapor pressure for the solvent.

  The reduced-pressure drying step of reducing the pressure during the drying effectively works to shorten the drying time even if it is performed only when at least one of the casting film 24a and the film 62 is dried. In this embodiment, in order to obtain a more excellent decompression effect, the pressure control device 210 is connected to the casting chamber 63, the tenter 64, and the drying chamber 69, and this pressure control is performed when drying in each chamber. The apparatus 210 is operated and vacuum drying is performed.

  In this embodiment, the pressure control device 210 is connected to the casting chamber 63, the tenter 64, and the drying chamber 69 to perform drying under reduced pressure. On the other hand, the bridge portion 101 does not reduce pressure but dries the film 62 under substantially normal pressure. However, by combining a plurality of drying temperatures arbitrarily and combining any combination of normal pressure and reduced pressure, not only drying under normal atmospheric pressure but also low temperature drying can be performed under reduced pressure. In addition, decomposition or alteration of the solvent, solvent, or additive can be suppressed. Therefore, desired physical properties can be expressed in the film 62 to be manufactured.

  Drying under reduced pressure can be any of from drying on a support to tenter drying that stretches in the width direction of the film while transporting the film by a transporting means such as a clip, and post-drying after removal of the clip. Even in the zone, it is possible to obtain the effect of the reduced pressure described above, such as solvent removal. The zone for controlling the degree of decompression is not limited to one place, and may be all drying zones, or may be a mode in which each zone, a part of each zone, or intermittently in each zone. In the present embodiment, any one of the casting chamber 63, the tenter 64, and the drying chamber 69 may be used, or these may be combined, and the form is not particularly limited. Further, a pressure control device may be provided (or connected) in the vicinity of the transition part 101 to reduce the pressure in the vicinity of the film 62 that transports the transition part 101.

  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, in particular, a direct methanol fuel cell, and also used as a solid electrolyte film sandwiched between two electrodes of a fuel cell. Can do. 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 the 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. 3 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. The MEA 131 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. 4 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. This is more advantageous in terms of ion conduction. 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 a direct methanol fuel cell, a methanol aqueous solution having a methanol concentration of 3 wt% to 64 wt% is used as an 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, the optimum concentration is determined by the methanol permeability of the solid electrolyte used. 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

[Production of solid electrolyte film]
Casting from the casting die 81 to the casting band 82 running on the dope A to form a casting film 24a, and drying air of 30 to 50 ° C. is blown by the first to third air ducts 91 to 93 to solidify the raw material A The cast membrane was dried until the residual solvent amount was 30 wt% with respect to the solid electrolyte. When the casting film 24 a had self-supporting properties, the casting film was peeled off from the casting band 82 as a film 62, and then the film 62 was fed into the tenter 64. In the tenter 64, while the both ends of the film 62 are gripped and conveyed by the clip 64a, the residual content of the raw material A is reduced to 15% by weight with respect to the solid content of the raw material A, that is, the solid electrolyte by the drying air of 50 ° C. The film 62 was dried. Then, after the film 62 was detached from the clip 64 a at the exit of the tenter 64, both side ends that were gripped and damaged by the clip 64 a were cut and removed by the ear clip device 67.

The film 62 from which both side ends were removed was sent to a drying chamber 69 and dried while being conveyed by a plurality of rollers 68. The drying chamber 69 was divided into four, and drying air of 50 ° C., 50 ° C., 50 ° C., and 50 ° C. was supplied from the blower (not shown) from the upstream side. At this time, the third and fourth sections in the drying chamber 69 were held at 300 hPa from the upstream side by the pressure control device 210. The conveyance tension of the film 62 by the roller 68 was set to 100 N / m, and the winding center angle of each roller 68 was set to 90 degrees and 180 degrees (exaggerated in FIG. 2). The material of each roller 68 was made of aluminum or carbon steel, and the surface thereof was hard chrome plated. As the surface shape of each roller 68, a flat one and a mat processed by blasting were used. Further, the deflection of the position of the film 62 due to the rotation of the roller 68 was all 50 μm or less. It should be noted that the deflection of the roller with the above-described transport tension was selected to be 0.5 mm or less.

  The solvent gas contained in the drying air in the drying chamber 69 was removed by adsorption by the adsorption recovery device 106. At this time, activated carbon was used as the adsorbent, and desorption was performed using dry nitrogen. And the collect | recovered solvent adjusted the moisture content to 0.3 weight% or less, and reused it as a solvent for dope preparation. Moreover, the solvent amount collect | recovered by a condensation method among all the evaporation solvents was 90 weight%, and most of the remainder was collect | recovered by adsorption collection.

  After drying in the drying chamber 69, the film 62 was sent to the cooling chamber 71, brought to about room temperature, and then the film 62 was sent to a temperature adjustment chamber (not shown) provided with a plurality of temperature control rollers. The temperature adjusting chamber was divided into two, and heating rollers were arranged at a high interval as temperature control rollers on the upstream side, and cooling rollers were arranged on the downstream side. Then, after drying the film 62 by supplying a drying air of 50 ° C. to the inlet-side section, the film 62 is further blown by a cooling roller adjusted to 30 ° C. The temperature was gradually lowered.

  The cooled film 62 was sent into a humidification chamber (not shown). In Example 1, the film 62 was conditioned under different humidity control conditions by providing the first humidification chamber and the second humidification chamber downstream as the humidification chamber. At this time, water vapor having a temperature of 30 ° C. and a dew point of 20 ° C. was supplied in the first humidification chamber, and water vapor having a temperature of 90 ° C. and a humidity of 70% was directly applied to the film 62 in the second humidification chamber. And the solid electrolyte membrane 62 in a dry state was obtained.

  The obtained film 62 was subjected to the following evaluations. 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. Measurement of Residual Solvent Amount of 7 × 35 mm cut from film 62 was collected as a sample, and the sample was subjected to gas chromatography (manufactured by Shimadzu Corp .; GC-18A), and the residual solvent amount (weight%) of film 62 ) Was measured.

3. Ion conductivity measurement About the obtained solid electrolyte 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 obtained in (2) was set in the fuel cell shown in FIG. 3, 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.

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%.

[Production of solid electrolyte film]
The cast film was dried by setting the wind of the first to third air ducts 91 to 93 to 80 to 120 ° C. The drying chamber 69 was divided into four, and the film 62 was dried at 140 ° C., 140 ° C., 140 ° C., and 140 ° C. from the upstream side. At this time, the third and fourth sections in the drying chamber 69 were held at 200 hPa from the upstream side by the pressure control device 210. In addition, in a temperature adjustment chamber (not shown) in which the inside is divided into two and a plurality of temperature control rollers are arranged, after the film 62 is heated by supplying 140 ° C. dry air to the inlet side compartment, In the section on the outlet side, a blower (not shown) was provided to blow 90 ° C. wind, and the temperature control roller was adjusted to 80 ° C. to gradually lower the temperature of the film 62. And the 1st humidification chamber and the 2nd humidification chamber were provided as a humidification chamber (not shown), and the film 62 was sent in the inside. At this time, water vapor having a temperature of 50 ° C. and a dew point of 20 ° C. was supplied to the first humidification chamber, and water vapor having a temperature of 90 ° C. and humidity of 70% was directly applied to the film 62 in the second humidification chamber. Conditions other than the above were the same as in Example 1 to obtain a solid electrolyte film 62 in a dry state. 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

[Production of solid electrolyte film]
The temperature of the wind from the 1st-3rd ventilation ducts 91-93 was 80-140 degreeC. The drying chamber 69 was divided into four, and the film 62 was dried at 160 ° C., 160 ° C., 160 ° C., and 160 ° C. from the upstream side. At this time, the third and fourth sections in the drying chamber 69 were held at 200 hPa from the upstream side by the pressure control device 210. Further, in a temperature adjustment chamber (not shown) in which the inside is divided into two and a plurality of temperature control rollers are arranged, 160 ° C. dry air is supplied to the inlet side to heat the film 62. After that, a blower (not shown) is provided in the section on the outlet side to supply 110 ° C. dry air, and a cooling roller is provided as a temperature control roller, which is adjusted to 90 ° C., and the film 62 is gradually The temperature was lowered. Then, the first humidification chamber and the second humidification chamber were provided as the humidification chamber 205, and the film 62 was fed. At this time, steam having a temperature of 60 ° C. and a dew point of 20 ° C. was supplied in the first humidification chamber, and steam having a temperature of 90 ° C. and humidity of 70% was directly applied to the film 62 in the second humidification chamber. Conditions other than the above were the same as in Example 1, and the solid electrolyte film 62 in a dry state was obtained as described above. The evaluation results on the obtained film 62 are shown in Table 1.

[Production of solid electrolyte film]
Under the same conditions as in Example 1, the film 62 was manufactured by maintaining all the compartments of the drying chamber 69 at normal pressure. The evaluation results on the obtained film 62 are shown in Table 1.

[Production of solid electrolyte film]
Under the same conditions as in Example 2, the film 62 was manufactured while maintaining all the compartments of the drying chamber 69 at normal pressure. The evaluation results on the obtained film 62 are shown in Table 1.

  Under the same conditions as in Example 3, the film 62 was manufactured while maintaining all the compartments of the drying chamber 69 at normal pressure. The evaluation results on the obtained film 62 are shown in Table 1.

The compound shown in Chemical formula 3 was used as a solid electrolyte. However, protonation for obtaining the compound of Chemical Formula 3, that is, acid treatment was carried out in the film production process as follows, 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. The raw material D was dissolved in a solvent and used for casting. The method for making the 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 (I), n is 0.33, m is 0.67, number average molecular weight Mn is 61000, and quantity average. The 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

  Since the dope is cast and peeled off from the casting band 82 is made of the raw material D, it is called a precursor film. The precursor film from which both side ends were removed by the edge-cutting device 67 through the same conditions as in Example 1 was protonated by acid treatment and then subjected to a washing step. The acid treatment is a step of bringing the precursor film into contact with an acid aqueous solution. By this acid treatment, the structure of the precursor becomes a structure represented by the general formula of Chemical Formula 3, that is, a solid electrolyte. The contact was performed by a method in which an aqueous acid solution was continuously supplied to a liquid tank and a film made of a solid electrolyte was immersed in this aqueous solution. Washing after the acid treatment was carried out with water. The film 62 after the cleaning process was sent to the drying chamber 69. The evaluation results for the obtained film 62 are shown in Table 1.

The compound shown in Chemical formula 3 and different from Example 7 was used as the solid electrolyte. However, protonation for obtaining the compound of Chemical Formula 3 was carried out in the film production process, not before the dope production, as in Example 7. A precursor used as a dope component is referred to as a raw material E. The solvent is a mixture of solvent component 1 and solvent component 2 as shown below. The solvent component 1 is a good solvent for the raw material E, and the solvent component 2 is a poor solvent for the raw material E. In Example 8, X in Chemical Formula 3 is Na, Y is SO ₂ , Z is Chemical Formulas (I) and (II), n is 0.33, m is 0.67, and the number average molecular weight Mn is 68,000 and the weight average molecular weight Mw are 200000. In Chemical Formula 4, (I) is 0.7 mol% and (II) is 0.3 mol%. The other conditions are the same as in Example 7.
-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

  From the results of the above examples, according to the present invention, the amount of residual solvent can be efficiently and effectively reduced by drying the film while reducing the pressure inside the drying chamber by the pressure control device. It can be seen that the drying efficiency can be improved. Therefore, it is possible to continuously produce a solid electrolyte film having a higher ionic conductivity by further reducing the amount of residual solvent while improving the drying rate. Moreover, it turns out that the solid electrolyte film obtained by this invention can be used conveniently as a solid electrolyte layer of a fuel cell.

It is the schematic of dope manufacturing equipment. It is the schematic of a film manufacturing equipment. 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 33 Film manufacturing equipment 62 Solid electrolyte film 64 Tenta 64a Clip 69 Drying room 131 Electrode membrane composite (MEA)
132 Anode electrode 133 Cathode electrode 141 Fuel cell 146 Current collector 210 Pressure control device

Claims (14)

A casting film forming step of casting a dope containing a solid electrolyte and an organic solvent from a casting die onto a support to form a casting film;
A film forming step of stripping the cast film as a film from the support;
While reducing the pressure of at least one of the casting membrane and the film by pressure control means and increasing the partial pressure of the organic solvent contained in the casting film or the film, the casting means is dried by the drying means. And a vacuum drying step for drying the membrane or the film.   2. The method for producing a solid electrolyte film according to claim 1, wherein the pressure control means reduces the pressure in the vicinity of at least one of the cast film and the film to 600 hPa or less. The first reduced-pressure drying step includes
It is a step of stretching the film in the width direction while drying while transporting the film gripped on both ends by gripping means,
The second vacuum drying step includes
3. The method for producing a solid electrolyte film according to claim 1, wherein the film is dried while being conveyed while being supported by a plurality of rollers.   The method for producing a solid electrolyte film according to claim 1, wherein the organic solvent is a mixture of a poor solvent and a good solvent for the solid electrolyte.   The method for producing a solid electrolyte film according to claim 4, 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 4 or 5, 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 claim 1, wherein the solid electrolyte is a hydrocarbon polymer.   The method for producing a solid electrolyte film according to claim 7, wherein the hydrocarbon polymer is an aromatic polymer having a sulfonic acid group. 9. The method for producing a solid electrolyte film according to claim 8, wherein the aromatic polymer is a copolymer composed of structural units represented by 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 film forming apparatus for casting a dope containing a solid electrolyte and an organic solvent from a casting die onto a support to form a casting film;
A film forming apparatus for stripping the cast film as a film from the support;
A pressure control means and a drying means, wherein the pressure control means depressurizes the vicinity of at least one of the casting membrane and the film to separate the organic solvent contained in the casting membrane or the film. An apparatus for producing a solid electrolyte film, comprising: a vacuum drying apparatus that dries the cast film or the film by the drying means while increasing the pressure. The first reduced pressure drying apparatus comprises:
The pressure control means capable of reducing the pressure in the vicinity of the film, the drying means for drying the film, and both side edges of the film are gripped, and the width of the film can be expanded and contracted by adjusting the width. A stretching decompression drying apparatus comprising a gripping means capable of
The second vacuum drying apparatus comprises:
It is a conveyance decompression drying apparatus provided with the pressure control means which can depressurize the neighborhood of the film, the drying means which dries the film, and a plurality of rollers which convey while supporting the film. Item 10. A facility for producing a solid electrolyte film according to Item 10.   A solid electrolyte film manufactured by the manufacturing 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;
A cathode electrode that is provided in close contact with the other surface of the solid electrolyte film and synthesizes water composed of the proton that has passed through the solid electrolyte film and a gas supplied from the outside;
An electrode membrane composite comprising: The electrode membrane composite according to claim 13,
A fuel cell comprising: a current collector that is provided in contact with an electrode of the electrode membrane composite and transfers electrons to and from the anode electrode and the cathode electrode.

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