JP2007123152A - Thin film, and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid film comprising a fine pore wall where proton donor groups are distributed, which has fine pores of nanometer size excellent in properties of: having no fault as the conventional technology does; high proton conductivity; acid catalyst capability; ion-exchange capability; chemical resistance; and thermal resistance. <P>SOLUTION: The hybrid film is characterized in that it has 3-dimensional fine pores with diameters in the range of 2nm to 500nm in which a metal oxide with fine pores of diameters smaller than those of the 3-dimensional fine pores, having at least one of proton conductivity and ion-exchange capability is contained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin film and a manufacturing method thereof. More particularly, the present invention relates to a proton conductive material used for energy devices and electrochemical sensors, an acid catalyst membrane used for producing fine chemical products and polymer products, a thin film that can be used for an ion exchange membrane, and a method for producing the same.

  In recent years, solid polymer fuel cells (PEFC) have been actively developed as a very clean next-generation energy that uses hydrogen as a fuel and discharges only water. In addition, a direct methanol fuel cell (DMFC) using methanol instead of hydrogen as a fuel has been proposed, and is expected and actively researched as a high-capacity battery for portable devices that replaces a lithium secondary battery.

  The important functions of the electrolyte membrane (proton conducting membrane) used in these polymer electrolyte fuel cells are the fuel (hydrogen, methanol aqueous solution, etc.) supplied to the cathode catalyst electrode and the oxidant gas (oxygen etc.) supplied to the anode. ) Physically, electrically insulating the positive electrode and the negative electrode, and transmitting protons generated on the positive electrode to the negative electrode. In order to satisfy these functions, a certain degree of mechanical strength and high proton conductivity are required.

  As the electrolyte membrane for a polymer electrolyte fuel cell, a sulfonic acid group-containing perfluorocarbon polymer typically represented by Nafion (registered trademark) is used. These electrolyte membranes have excellent proton conductivity and relatively high mechanical strength, but further improvements are desired in the following respects. That is, in these electrolyte membranes, protons conduct through water in the cluster channels formed by the water and sulfonic acid groups contained in the membranes, so proton conductivity depends greatly on the moisture content of the membrane due to the humidity of the battery usage environment. To do. The polymer electrolyte fuel cell is preferably operated in a temperature range of 100 to 150 ° C. from the viewpoint of reducing poisoning of the catalyst electrode by CO and increasing the activation of the catalyst electrode. However, in such an intermediate temperature range, the proton conductivity decreases with a decrease in the water content of the electrolyte membrane, so that expected battery characteristics cannot be obtained. Also, the softening point of the electrolyte membrane is around 120 ° C., and the mechanical strength of the electrolyte membrane cannot be obtained when operated in this temperature range.

  On the other hand, when these electrolyte membranes are used for DMFC, the following phenomenon occurs. That is, these membranes that are inherently water-containing have a low barrier property against methanol of fuel, so that methanol supplied to the positive electrode permeates the electrolyte membrane and reaches the negative electrode. This causes a methanol crossover phenomenon that lowers the battery output. This is one of the important issues to be solved for the practical application of DMFC.

  Under such circumstances, the momentum for developing proton conductive membranes to replace Nafion has increased, and several promising electrolyte materials have been proposed. For example, proton conductive glass is known as an inorganic proton conductive material. These are obtained by polymerizing tetraalkoxysilane in the presence of an acid by a sol-gel method, and are known to have low humidity dependency at high temperatures. However, proton conductivity is insufficient and it is not suitable as an electrolyte for fuel cells.

  In order to facilitate film formation while taking advantage of the properties of inorganic materials, nanocomposite materials combined with polymer materials have been proposed. For example, a method for producing a proton conductive membrane by complexing with a polymer compound having a sulfonic acid group in the side chain, silicon oxide, and protonic acid is disclosed (for example, see Patent Documents 1 to 3). In addition, an organic-inorganic nano-hybrid type proton conductive material which has an organosilicon compound as a precursor and is generated by a sol-gel reaction in the presence of a protonic acid has been proposed (for example, see Patent Document 4).

  These organic-inorganic composites and hybrid proton conductive materials are composed of an inorganic component that is a proton conducting portion and composed of silicic acid and a protonic acid, and an organic component that imparts flexibility to the material. It is something that has no degree.

In addition, a thin film in which mesoporous silica is synthesized in the pores of alumina obtained by anodization has been reported (see Non-Patent Document 1). However, the report does not describe proton conductive membranes and ion exchange membranes, and application to proton conductive membranes and ion exchange membranes is not considered.
Further, although the membrane reported in Non-Patent Document 1 suggests the use as a catalyst, it is unclear and it is unclear what kind of catalyst and how to use it.

  Although a proton conducting membrane using mesoporous silica has also been reported (Non-patent Document 2), since the membrane is composed only of mesoporous silica, it is difficult to increase the film thickness. The strength is not enough.

Although a proton conductive membrane using mesoporous P ₂ O ₅ —SiO ₂ glass has also been reported (Non-patent Document 3), mesoporous P ₂ O ₅ —SiO ₂ glass is brittle and breaks when assembling battery cells. There are problems such as easy.

Although there are reports of using a porous membrane as a matrix and filling the pores with a proton-conducting substance (for example, Patent Document 5 and Patent Document 6), the substance filling the pores has pores. However, for this reason, under low humidification conditions, etc., it is difficult to retain sufficient moisture in the proton conducting membrane, and it is difficult to sufficiently exhibit proton conducting performance.
JP-A-10-69817 Japanese Patent Laid-Open No. 11-203936 JP 2001-307752 A Japanese Patent No. 3103888 International Patent Publication No. 2003/075386 Pamphlet JP 2003-335895 A Japanese Patent Laid-Open No. 2004-2865 Japanese Patent Laid-Open No. 2004-18751 JP 2003-359860 A Nature Materials, vol3, p337-341 Chemistry and Industry Vol.57 No.4 p410-413 (2004) Advanced Materials., 12, 18, p1370-1372 (2000)

  The present invention aims to solve the above problems. That is, the object of the present invention is a proton conductive material used in energy devices and electrochemical sensors having high handling properties and durability, a thin film usable in catalyst membranes and ion exchange membranes used in the production of fine chemical products and polymer products, and The manufacturing method is provided.

  In order to achieve the above object, according to the present invention, the pores of the thin film having the three-dimensional pores having a diameter of 2 nm to 500 nm have pores having a diameter smaller than the pore diameter of the thin film, proton conductivity, ion exchange There is provided a thin film containing a metal oxide having at least one of any of the above properties. According to a preferred embodiment, the thin film of the present invention is composed of either ceramic or organic polymer. The organic polymer is preferably polytetrafluoroethylene or polyimide having high chemical resistance and heat resistance. Ceramics include metal oxides, metal carbides, metal nitrides and the like.

  The thin film of the present invention preferably has a thickness of 1 mm or less (more preferably 60 μm or less), but the thin film obtained by anodic oxidation has a thickness of the oxide film portion, and other thin films obtained by various methods. It is appropriately formed on a support or a substrate, but the support and the substrate are not included in the film thickness. From the viewpoint of film strength, the lower limit of the film thickness is preferably 5 μm or more.

  In the present invention, the three-dimensional pores do not include linear pores that are almost perpendicular to the one-dimensional membrane surface (in the range of 90 ° ± 20 °) as individual shapes. However, as will be described later, when a three-dimensional pore is formed as a whole by crossing with other pores, it may be a substantially vertical linear pore. The pores are linear, curved, or bent except for being substantially perpendicular to the membrane surface (in the range of 90 ° ± 20 °) (here, linear, curved, bent) It is the shape when a longitudinal section is imaged). As an aggregate of pores, the pores may intersect each other and are regular and / or irregular pores, which are generated by mesh-like pores, deaeration, desolvation, defunctional groups, etc. Those in which continuous spaces are continuously connected shall also fall within the range of the three-dimensional pores. The three-dimensional pores are preferably penetrating in that a substance can pass or move between both surfaces of the thin film. Such three-dimensional pores can be confirmed by observing with a scanning electron microscope.

In the present invention, proton conductivity means that a proton is a proton donating group such as a hydroxyl group (—OH, —SO ₂ —OH, —C (O) —OH, —P (O) (OH) ₂ , —NR ₃ —H). ⁺ (R is a hydrocarbon group such as an alkyl group, including a cyclic imidazole group, etc.) and a water molecule, and has a property of showing conductivity.

  In the present invention, the ion exchange property refers to ion exchange governed by ion equilibrium when an ion concentration gradient occurs.

  In the present invention, examples of the methanol-impermeable organic polymer include epoxy resin, Teflon (registered trademark) resin, polypropylene, polyethylene, polyethylene terephthalate, and polyester.

  In the present invention, the polyimide means a polymer having an imide group in the main chain, and includes a narrowly defined polyimide obtained from polyamideimide, tetracarboxylic acid and diamine.

  According to the present invention, as will be described below, the pores of the thin film having three-dimensional pores with a diameter of 2 nm to 500 nm have pores with a diameter smaller than the pore diameter of the thin film, and have proton conductivity and ion exchange properties. A thin film characterized in that it contains a metal oxide having at least one of the above properties can be obtained. Such a membrane has excellent proton conductivity and ion exchange properties, and also has good durability and stability, and is useful for fuel cells, electrochemical sensor applications, capacitors, catalyst membranes, ion exchange membranes, and the like.

  The present invention will be described in more detail. The thin film having a three-dimensional pore having a diameter of 2 nm to 500 nm according to the present invention has a pore having a diameter smaller than the pore diameter of the thin film, and has at least one property of proton conductivity and ion exchange. A thin film characterized by containing the above-described metal oxide is produced by a two-stage process. In the first stage, a thin film having three-dimensional pores with a diameter of 2 nm to 500 nm is prepared. In the second stage, the thin film has pores with a diameter smaller than that of the thin film, proton conductivity, ion exchange. A metal oxide structure having at least one of the above properties is prepared.

  First, a method for producing a thin film having three-dimensional pores having a diameter of 2 nm to 500 nm in the first stage will be described. The thin film preparation method in the first stage includes photolithography, semiconductor patterning technology such as electron beam exposure, X-ray exposure, and other semiconductor processing technologies, sputtering method, anodization, sol-gel method, thermal stability. There are a method of mixing and dispersing two or more types of organic polymers different from each other and decomposing only a more thermally unstable organic polymer, a partial thermal decomposition method of a block copolymerized organic polymer, and the like, but not limited thereto. In addition, a polyimide precursor can be formed into a film by cyclization by heating to form a polyimide, and at the same time, a porous polyimide film can be formed by using a heat treatment method to remove water generated during condensation or coexisting organic substances. Although possible (methods described in Patent Document 7, Patent Document 8, Patent Document 9 and the like), a method of dissolving a component to be removed by using a chemical treatment method may be employed.

  As described above, an inorganic thin film or an organic thin film may be used. In the case of an inorganic thin film, it is preferable to use semiconductor processing technology such as photolithography, fine pattern formation technology such as electron beam exposure and X-ray exposure, sputtering method, anodic oxidation, etc. in order to create pores. Cost and yield From this point, anodic oxidation is more preferable.

  In the case of an organic thin film, porous polyimide is preferable from the viewpoint of heat resistance, chemical resistance, ease of functional group modification, and the like.

  The thin film having three-dimensional pores with a diameter of 2 nm to 500 nm is preferably composed of an organic polymer or a ceramic material (metal oxide, metal carbide, metal nitride). In the case of assembling a fuel cell system in which heat resistance is regarded as important, those containing a ceramic material are preferred, and those containing a metal oxide are more preferred from the viewpoint of cost and ease of production. In addition, when a fuel cell system in which mechanical strength is regarded as important is built, the entire membrane may be brittle if it is an inorganic substance. In this case, an organic polymer is removed from a three-dimensional pore having a diameter of 2 nm to 500 nm. It is preferable to use it as a thin film having

  In addition, since the organic polymer is flexible, it can be used in various forms, and when used for a catalyst, an ion exchange membrane, or the like, since it has good handling properties, it is versatile.

  Among organic polymers, porous polyimide is preferred because of its heat resistance, chemical resistance, and ease of functional group modification. Polyimide (narrowly defined) polymerizes monomers belonging to tetracarboxylic acid components and diamine components, preferably aromatic compounds. Is obtained.

  The diamine is not particularly limited as long as it is an aromatic diamine, but preferably 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-dimethyl-4,4′-. Diaminodiphenyl ether, 3,3′-diethoxy-4,4′-diaminodiphenyl ether, para-phenylenediamine (hereinafter sometimes abbreviated as p-PDA), meta-phenylenediamine, 4,4 Examples thereof include aromatic diamines such as' -diaminodiphenyl ether (hereinafter sometimes abbreviated as DADE). In addition, the diamine component may be diaminopyridine, specifically, 2,6-diaminopyridine, 3,6-diaminopyridine, 2,5-diaminopyridine, 3,4-diaminopyridine, and the like. Is mentioned. The diamine component may be used in combination of two or more of the above diamines.

  The tetracarboxylic acid component is preferably a biphenyltetracarboxylic acid component, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as s-BPDA). 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as a-BPDA), but 2,3,3 ′, 4′- or 3, 3 ', 4,4'-biphenyltetracarboxylic acid, or a salt of 2,3,3', 4'- or 3,3 ', 4,4'-biphenyltetracarboxylic acid or an esterified derivative thereof Also good. The biphenyl tetracarboxylic acid component may be a mixture of the above biphenyl tetracarboxylic acids.

  In addition, the tetracarboxylic acid component described above is obtained by using pyromellitic acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 2,2-bis (3,4- Dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bis (3,4-dicarboxyphenyl) thioether or acids thereof Aromatic tetracarboxylic acids such as anhydrides, salts or esterified derivatives may be substituted. Further, a part or all of these aromatic tetracarboxylic acid components may be replaced with alicyclic tetracarboxylic acids, or acid anhydrides, salts or esterified derivatives thereof.

  Such a thin film made of porous polyimide can also be used from commercially available products.

  In the present invention, various properties can be imparted by post-processing the organic polymer constituting the thin film.

  For example, the post-treatment of the porous polyimide described in Patent Document 8 is not particularly limited. However, a treatment such as sulfonation with chlorosulfonic acid or the like is performed, or a monomer into which a functional group is introduced as described in Patent Document 7 By synthesizing porous polyimide by polymerization from the above, the surface of the porous polyimide can be hydrophilized. Thereby, when producing a metal oxide having a diameter smaller than the pore diameter of the thin film produced in the second stage and having at least one of proton conductivity and ion exchange properties, It has the effect of preventing gaps at the interface between the thin film pores and the metal oxide, and at the same time, functions such as proton conductivity, ion exchange, and the like, which the metal oxide bears, can also bear the porous polyimide, It becomes possible to improve the function of the entire thin film. For example, the sulfonic acid content of the sulfonated aromatic polyimide is preferably 0.5 milliequivalents or more per gram, more preferably 1 milliequivalents or more.

  In addition, regarding the thin film of the present invention, pores having a diameter of 2 to 500 nm are measured with a pore distribution measuring device (a porosimeter device based on a mercury intrusion method, a BET adsorption measuring device based on a nitrogen adsorption method, a bubble point method, and a half dry method. The average pore diameter calculated by a palm porometer device based on the above is in the range of 2 to 500 nm. The BET adsorption measuring device (nitrogen adsorption under liquid nitrogen temperature conditions) is measured in the region of 2 nm or more and less than 50 nm, and the porosimeter device or palm porometer device is used in the region of 50 nm or more and 500 nm or less. It shall be used when it is a through hole. The measurement with a palm porometer device is performed under conditions of 25 ° C. ± 5 ° C. At the time of measuring the pore diameter, measurement is performed after removing substances in the pores such as template molecules by baking or extraction.

  The reason why the pore diameter of the thin film prepared in the first stage is 2 to 500 nm is that in the second stage, the thin film has pores having a diameter smaller than the pore diameter of the thin film and is either proton-conductive or ion-exchangeable. When producing a metal oxide having at least one property, the pores of the metal oxide are likely to be formed along the pores of the first-stage membrane. This is because it is preferable in terms of improving the diffusibility of the substance. The pore diameter of the prepared thin film in the first stage is more preferably 2 to 200 nm, and most preferably 2 to 100 nm.

  Next, the production of a metal oxide having pores having a diameter smaller than that of the thin film and having at least one of proton conductivity and ion exchange properties will be described. The metal oxide preparation method having at least one of the properties of proton conductivity and ion exchange in the second stage should be prepared by the sol-gel method in the pores of the thin film prepared in the first stage. Is preferred.

  In this case, the sol-gel method may be a general method and is not particularly limited. For example, a metal alkoxide, a metal halide, a metal oxide, an organic metal ester, or the like is used as a raw material. Also, in the sol-gel reaction, a polymer having a polar functional group as a template, a surfactant, an ionic liquid, an organic amine, It is preferable to add a quaternary ammonium salt or the like.

  Although the said sol-gel method is not specifically limited, For example, the existing various methods performed at the time of a mesoporous silica synthesis | combination etc. can be used.

  Although not particularly limited during the sol-gel reaction, it is possible to improve the regularity of the pores of the metal oxide by adding a salt such as NaCl.

  During the sol-gel reaction, it is possible to improve the water resistance of the metal oxide by adding Zr, Ti or the like, and a metal oxide composed only of Zr oxide and / or Ti oxide may be used. Of course, Si oxide may be the main component and a part may be composed of Zr oxide and / or Ti oxide.

In addition, although not particularly limited during the sol-gel reaction, the addition of NaF or NaBF ₄ as a fluorine source can accelerate polycondensation, shorten the synthesis time, and increase the thickness of the pore wall of the metal oxide. It is also possible to improve the performance.

  The pores having a diameter smaller than the pore size of the thin film are preferably 1 nm or more, more preferably 1.5 nm or more, from the viewpoint of water retention in the pores and proton conductivity. These pore sizes are the same as the method for measuring the pore size of a thin film, but when measuring a region of 2 nm or less, nitrogen adsorption measurement is performed with a BET apparatus.

  After the sol-gel reaction, a drying step at about 100 ° C. (preferably 100 ± 50 ° C.) and a firing step at a temperature higher than that (preferably about 200 ° C. to 500 ° C. are preferable). It is possible to promote polycondensation and obtain a more durable thin film.

  After the sol-gel reaction, the obtained thin film having three-dimensional pores having a diameter of 2 nm to 500 nm has pores having a diameter smaller than the pore diameter of the thin film, and is either proton-conductive or ion-exchangeable. When a thin film characterized by containing a metal oxide having at least one of the above properties is observed with an electron microscope, a metal oxide is formed as a by-product in a sol-gel reaction at a place other than within the pores of the thin film. There is a case. When inconvenience occurs when the metal oxide is by-produced in a place other than the inside of such pores, there is no particular limitation, but the by-product metal oxidation is performed by polishing the thin film surface by a conventionally known polishing method such as a CMP process. Things can be removed.

  In addition, the thin film of the present invention has pores having a diameter smaller than the pore diameter of the thin film by sol-gel reaction in the pores of the thin film having a thickness of 1 mm or less and having a three-dimensional pore with a diameter of 2 nm to 500 nm. Then, a metal oxide having at least one of proton conductivity and ion exchange properties is prepared, and thereafter, although not particularly limited, a CMP (chemical mechanical polishing (planarization)) process, etc., By polishing the surface of the thin film by a general polishing method, the hybrid film of the present invention having a film thickness of 1 mm or less can also be produced.

  The three-dimensional hexagonal symmetric P63 / mmc structure or the two-dimensional hexagonal symmetric P6mm structure is preferable in terms of improving proton conductivity and reducing pressure loss. The structure of P63 / mmc or P6 mm can be confirmed by X-ray diffraction, electron beam diffraction, or the like.

The composition of the metal oxide is not particularly limited, but preferably contains at least one element from group 2 to group 16 of the periodic table as a metal species, and includes Si, Al, P, S, N, Zr, and Ti atoms. Those containing any of them are preferred from the viewpoint of improving proton conductivity, ion exchange properties and durability. For example, when silica is used as the metal oxide, proton conductivity and ion exchange may be insufficient with silica alone. In this case, this method is effective. In particular, phosphorus or sulfur having a hydroxyl group such as a phosphate group or a sulfate group is preferably contained on the surface of the metal oxide from the viewpoint of improving proton conductivity and ion exchange properties. These functional groups have high proton donating ability, and protons are proton donating groups (—OH, —SO ₂ —OH, —C (O) —OH, —P (O) (OH) ₂ , —NR ₃ — It becomes easy to hop between H ⁺ (R is a hydrocarbon group such as an alkyl group, including a cyclic imidazole group) and the like and a water molecule. By containing phosphorus or sulfur having a hydroxyl group on the surface of the metal oxide, proton conductivity and ion exchange can be improved. These functional groups do not need to be present directly on the metal oxide, but may be those in which the functional group and the metal oxide are bonded by a hydrocarbon (alkyl group or the like).

  The method of containing phosphorus or sulfur having a hydroxyl group on the surface of the metal oxide is not particularly limited. For example, as a method of (1), a metal is formed by a sol-gel method using phosphate esters at the time of forming the metal oxide. A metal alkoxide (for example, mercaptopropyltrimethoxysilane) having a thiol group introduced as a part of the pore wall of the oxide and a hydrogen peroxide solution is used to simultaneously convert the thiol group to a sulfonic acid group when forming the metal oxide. The method of oxidizing and introducing as a part of the pore wall of a metal oxide is raised. Further, for example, as the method (2), after the metal oxide is prepared, as a post-treatment, the hydroxyl group on the surface of the metal oxide may be treated with a phosphate ester, sulfuryl chloride or the like to be hydrolyzed. Further, the hydroxyl group on the surface of the metal oxide can be treated as a post-treatment with a metal alkoxide containing a thiol group, etc., and oxidized to be converted into a sulfonic acid group or the like.

  However, in the method of (2), if a phosphate group or a sulfate group is modified and introduced as a post-treatment after the preparation of the metal oxide, it is easily modified near the entrance of the metal oxide pores. Since it is not easy to uniformly dispose phosphoric acid groups and sulfuric acid groups on the substrate, and the manufacturing process takes one step further, as in the method (1), one step ( It is preferable to introduce in one pot.

  In addition, in order to adjust the pore diameter of the metal oxide, various templates can be selected as a template during the synthesis of the metal oxide. After the synthesis of the metal oxide, although not particularly limited, the metal oxide can be oxidized using a metal alkoxide or the like. The pores of the metal oxide can also be narrowed by polycondensation at the pore walls of the product.

  The thin film having a three-dimensional pore having a diameter of 2 nm to 500 nm according to the present invention has a pore having a diameter smaller than the pore diameter of the thin film, and has at least one property of proton conductivity and ion exchange. It can be further functionalized as a proton conducting membrane by bringing an organic polymer into contact with the pores of the metal oxide. For example, by contacting an organic polymer having a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, an imidazole group, etc., when applied to a fuel cell, the separator between the electrode or gas flow path and the proton conducting membrane are bonded. The electrical conductivity can be improved. At this time, the place where the organic polymer having a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, or the like contacts may be inside or outside the pores of the metal oxide. When contacting inside and outside the pores, there is no particular limitation, but the organic polymer may be applied to the film surface and pressurized, and as a result, there is no problem even if the polymer enters and presses into the pores. When contacting within the pores of the metal oxide, a proton conductive membrane made only of an organic polymer having a known sulfonic acid group, phosphoric acid group, carboxylic acid group, etc., or a sulfonic acid group, phosphoric acid group, carboxylic acid group, etc. Unlike a proton conducting membrane that is combined with an organic polymer and an inorganic substance, the thin film of the present invention has pores with a diameter smaller than the pore diameter of the thin film within the pores of the thin film, and has either proton conductivity or ion exchange properties. Since it has a metal oxide having at least one of these properties, the film strength is high and the water retention is high due to nano-order pores.

  Examples of the organic polymer having the sulfonic acid group, phosphoric acid group, carboxylic acid group, imidazole group, etc. include organic polymers such as polyether, polyether ketone, polytetrafluoroethylene, sulfonic acid group, phosphoric acid group, carboxylic acid group. And those having an imidazole group introduced therein.

  In addition, by contacting methanol-impermeable organic polymer (epoxy resin, Teflon (registered trademark) resin, polypropylene, polyethylene, polyethylene terephthalate, polyester, etc.) with the metal oxide pores, the battery can be used for DMFC applications. The methanol crossover phenomenon in which the output decreases can be suppressed. The method for bringing the methanol-impermeable organic polymer into contact with the pores is not particularly limited, but the polymer may be applied to the membrane surface and pressurized, and as a result, the polymer enters and is injected into the pores. There is no problem.

  Unlike the organic polymer having a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, an imidazole group, or the like, the methanol-impermeable organic polymer preferably has no such functional group.

  However, in order to use the effects of the organic polymer having the sulfonic acid group, phosphoric acid group, carboxylic acid group, imidazole group, etc. and the effect of the methanol-impermeable organic polymer, two polymers may be mixed and used. .

  As the methanol-impermeable organic polymer, when a mixed gas of methanol, water, and nitrogen (1.5: 1.5: 97 (volume ratio)) is sent to a resin film (50 μm thickness) at room temperature, An organic polymer having a permeation amount of preferably 10% or less, more preferably 5% or less, and particularly preferably 3% or less with respect to the supply amount of methanol is preferred. Examples of such a polymer include polyethylene, polypropylene, epoxy resins, Examples thereof include Teflon (registered trademark) resin and polyester such as polyethylene terephthalate.

  The pore diameter of the metal oxide can be measured by nitrogen adsorption measurement, a transmission electron microscope, or a scanning electron microscope, similarly to the thin film prepared in the first stage.

In the present invention, the fact that a metal oxide exhibits proton conductivity means that the conductivity is measured by the AC complex impedance method under conditions of 100% relative humidity and 25 ° C. (room temperature), and shows a value of ¹ mS · cm ⁻¹ or more. Is. Preferably, the value is 20 mS · cm ⁻¹ or more.

  In the present invention, the AC complex impedance method is measured at a frequency of 0.01 Hz to 10 kHz and the AC amplitude is 50 mV, and poly (2-acrylamido-2-methylpropane) is used at the interface between the sample and the electrode in order to reduce the interface resistance. Measurement is performed by applying a 15 wt% aqueous solution of sulfonic acid.

  As described above, the thin film of the present invention can be applied to semiconductor processing techniques such as photolithography, fine pattern formation techniques such as electron beam exposure and X-ray exposure, sputtering methods, anodization, sol-gel methods, porous A thin film having pores with a diameter of 2 nm to 500 nm is prepared by a method for preparing a conductive organic polymer film, and then the diameter smaller than the pore diameter of the thin film by a sol-gel method or the like in the pores of the thin film prepared in the first stage. In combination with a method for producing a metal oxide having at least one of proton conductivity and ion exchange properties, and having proton conductivity and ion exchange properties. It is possible to provide a membrane having high characteristics, water retention, membrane strength, and low pressure loss. The proton donating group or ion exchange group is preferably phosphorus or sulfur having a hydroxyl group.

  In addition, since the thin film of the present invention has proton conductivity and ion exchange properties, it can be used as a catalyst film in the production of fine chemical products and polymer products. In this case, since the inside of the nano-order pores becomes the main reaction field, the molecular sieve effect is observed, and the catalyst film is useful in a reaction in which a product having a molecular diameter larger than that of the target molecule can be generated as a by-product. A zeolite membrane is known as a membrane having the same effect. However, the zeolite membrane has pores of angstrom order and has the disadvantage that the diffusion of the substance is bad and the pressure loss is large, but the thin film of the present invention is nano order. Therefore, the pressure loss is small and it is useful as a catalyst membrane.

  It is useful as an acid catalyst when protons are held at some or all of the ion exchange points. Also, it uses transition metals and has pores with a diameter smaller than that of the thin film within the pores of the thin film. In the case of synthesizing a metal oxide having at least one of conductivity and ion exchange properties, or the transition metal fine particles have pores having a diameter smaller than that of the thin film in the pores of the thin film, When supported on a metal oxide having at least one of proton conductivity and ion exchange properties, the function varies depending on the transition metal, but the oxidation catalyst, reduction catalyst, condensation catalyst, polymerization catalyst, Lewis acid catalyst. It is useful as such.

  For example, it is useful as a catalyst for bisphenol A synthesis, a catalyst for CO oxidation, a catalyst for polyacetylene production, a catalyst for polyolefin production, a catalyst for epoxidation reaction of olefins, and the like.

  When introducing protons or transition metals serving as catalytically active species into the thin film, the thin film preferably has ion exchange properties. When the thin film has ion exchange properties, a mineral acid, a transition metal salt or a complex is dissolved in a polar solvent such as alcohol or water, and ion exchange occurs by bringing the thin film into contact with the solution, This is because it becomes possible to introduce protons and transition metals that become catalytically active species more uniformly into the entire thin film.

  The ion exchange property is not particularly limited, but a composite metal oxide composed of a plurality of metal oxides having different charges, for example, a composite metal oxide composed of a trivalent metal (for example, Al) and a tetravalent metal (for example, Si). Occurs when the Al atom has four covalent bonds, and since Al is originally a trivalent metal on the Al atom (near), a negative charge is generated. At that time, a counter cation is generated to compensate for the negative charge on the composite oxide. The counter cation can be ion-exchanged, and the composite oxide has ion-exchange properties. In addition, when a sulfonic acid group, phosphoric acid group, carboxylic acid group, protonated imidazole group, etc. are introduced on the surface of the metal oxide, these functional groups easily release protons. Exchange becomes possible and it has ion exchange property.

  The thin film of the present invention is useful for fuel cell applications such as direct methanol fuel cells (DMFC) and polymer electrolyte fuel cells (PEFC), electrochemical sensor applications requiring ion conductive membranes, capacitors, etc. It is also useful as a catalyst membrane such as an acid catalyst membrane or an ion exchange membrane, or a separation membrane.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1
As a first step, 0.3 g of a porous polyimide film (trade name: Upilex (registered trademark) PT) manufactured by Ube Industries, Ltd. was used. As a result of confirmation with a scanning electron microscope, the porous polyimide film had a network-like structure and had three-dimensional pores. Moreover, as a result of measuring by the palm porometer (PMI palm porometer CF-200AE) based on the bubble point method and a half-dry method, the average pore diameter of the said porous polyimide film was about 150 nm. The thickness of the porous polyimide film was about 30 μm.

As the second step, 14 ml of methanol and 80 μl of 5M aqueous nitric acid solution are added to 2 g of a surfactant, polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol (Aldrich: average molecular weight 5800), and the mixture is stirred uniformly. It was set as the solution. Thereafter, 3.57 ml (16 mmol) of tetraethoxysilane (Si (OCH ₂ CH ₃ ) ₄ , hereinafter referred to as “TEOS”) was added and stirred at 40 ° C. for 3 hours. Thereafter, 0.756 ml of mercaptopropyltrimethoxysilane (hereinafter referred to as “MPTMS”) (manufactured by Aldrich) and 3.65 ml of hydrogen peroxide solution were added and stirred at 40 ° C. for 20 hours.

  In the precursor solution prepared as described above, the film in the first stage (porous polyimide film) is immersed, and the entire container containing the precursor solution in which the film is immersed is immersed in an ultrasonic water bath, and at room temperature for over 5 minutes. A sound wave was brought into contact.

  Thereafter, the membrane was pulled up, the excess precursor solution remaining on the membrane surface was drained, the membrane was dried at room temperature, then immersed in liquid paraffin, and heated at 60 ° C. for 20 hours. Thereafter, the membrane is pulled up, the liquid paraffin adhering to the membrane is washed away with hexane, dried at 100 ° C. overnight, and the diameter smaller than the pore diameter of the thin film is within the pores of the thin film having pores with an average pore diameter of about 150 nm. Thus, a thin film film containing a metal oxide having proton conductivity and ion exchange properties and having proton donating groups arranged on the metal oxide pore wall was obtained.

  In the above, it is confirmed by observation with a transmission electron microscope and nitrogen adsorption measurement that the structure having pores having a diameter smaller than the pore diameter exists in the pores of the thin film, and the structure is a metal oxide. This was confirmed by energy dispersive X-ray fluorescence analysis.

When the conductivity of the obtained thin film was measured by the AC complex impedance method under a relative humidity of 70%, it was 20 mS · cm ⁻¹ at room temperature, and proton high conductivity was confirmed. This thin film can be used as a proton conducting membrane.

(Example 2)
As a first step, 0.3 g of a porous polyimide film (trade name: Upilex (registered trademark) PT) manufactured by Ube Industries, Ltd. was used.
The pore diameter was about 150 nm. The thickness of the porous polyimide film was about 30 μm.

As a second step, 7 ml of methanol and 40 μl of pure water are added to 1 g of polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol (Aldrich: average molecular weight: 5800) which is a surfactant, and 0.233 g of ZrCl ₄ is added. In addition, the mixture was stirred to obtain a uniform solution. Thereafter, 1.61 ml of TEOS was added and stirred at room temperature for 1 hour. Thereafter, 0.34 ml of MPTMS was added and stirred at room temperature for 3 hours, and then 30 wt% 1.65 ml of hydrogen peroxide was added and stirred at room temperature for 20 hours.

  In the precursor solution prepared as described above, the film in the first stage (porous polyimide film) is immersed, and the entire container containing the precursor solution in which the film is immersed is immersed in an ultrasonic water bath, and at room temperature for over 5 minutes. A sound wave was brought into contact.

  Thereafter, the membrane was pulled up, the excess precursor solution remaining on the membrane surface was drained, and after drying the membrane at room temperature, the membrane was immersed in liquid paraffin and heated at 60 ° C. for 20 hours. Thereafter, the membrane is pulled up, the liquid paraffin adhering to the membrane is washed away with hexane, and dried at 100 ° C. overnight, so that the fine pores having a diameter smaller than the pore diameter of the thin film are inserted into the pores of the thin film having pores having an average diameter of 150 nm. A thin film containing a metal oxide having pores, proton conductivity and ion exchange properties, and having proton donating groups arranged on the pore walls of the metal oxide was obtained. About the obtained thin film, the same confirmation as Example 1 was performed.

When the conductivity of the obtained thin film was measured by the AC complex impedance method under the condition of a relative humidity of 70%, it was 21 mS · cm ⁻¹ at room temperature, and proton high conductivity was confirmed.

(Example 3)
As a first step, 1 g of a porous polyimide film (trade name: Upilex (registered trademark) PT) manufactured by Ube Industries, Ltd. was used (the pore diameter was about 150 nm. The thickness of the porous polyimide film was about 30 μm). Under a nitrogen atmosphere, 120 ml of dehydrated chloroform was added as a solvent and cooled to 0 ° C. with an ice bath, and then 1 mmol of chlorosulfonic acid was slowly added dropwise. Thereafter, stirring was continued at 0 ° C. for 30 minutes, the temperature was raised to room temperature, stirring was continued for 30 minutes, the temperature was raised to 70 ° C., stirring was continued for 30 minutes, the temperature was lowered and poured into ice water, and the membrane was washed with dilute hydrochloric acid.

As a second step, 7 ml of methanol and 40 μl of pure water are added to 1 g of polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol (Aldrich: average molecular weight: 5800) which is a surfactant, and 0.233 g of ZrCl ₄ is added. In addition, the mixture was stirred to obtain a uniform solution. Thereafter, 1.61 ml of TEOS was added and stirred at room temperature for 1 hour. Thereafter, 0.34 ml of MPTMS was added and stirred at room temperature for 3 hours, and then 30 wt% 1.65 ml of hydrogen peroxide was added and stirred at room temperature for 20 hours.

  The precursor solution prepared as described above is immersed in a film obtained by dividing 0.15 g of the film (porous polyimide film) in the first step, and the ultrasonic water bath together with the container containing the precursor solution in which the film is immersed It was immersed in and contacted with ultrasonic waves for 5 minutes at room temperature.

  Thereafter, the membrane was pulled up, the excess precursor solution remaining on the membrane surface was drained, and after drying the membrane at room temperature, the membrane was immersed in liquid paraffin and heated at 60 ° C. for 20 hours. Thereafter, the membrane is pulled up, the liquid paraffin adhering to the membrane is washed away with hexane, and dried at 100 ° C. overnight, so that the fine pores having a diameter smaller than the pore diameter of the thin film are inserted into the pores of the thin film having pores having an average diameter of 150 nm. A thin film containing a metal oxide having pores, proton conductivity and ion exchange properties, and having proton donating groups arranged on the pore walls of the metal oxide was obtained. About the obtained thin film, the same confirmation as Example 1 was performed.

When the conductivity of the obtained thin film was measured by the AC complex impedance method under the condition of 70% relative humidity, it was 40 mS · cm ⁻¹ at room temperature, and proton high conductivity was confirmed. This thin film is excellent as a proton conductive membrane.

(Comparative Example 1)
Trimethyl phosphate ((CH ₃ O) ₃ P (O)) 0.742 g (0.0053 mol), tetraethoxysilane 20.83 g (0.1 mol), water 1.63 g, ethanol 4.6 g (0.1 mol) , 0.027 g of HCl (36 wt% aqueous solution) was added and stirred (CH ₃ O) ₃ P (O): Si (OEt) ₄ : H ₂ O: EtOH: HCl = 0.053: 1: 1: 1: 0. The mixture was mixed with 7.5 g of water, 4.83 g (0.1053 mol) of ethanol, and 0.117 g of HCl (36 wt% aqueous solution), and stirred for 1 hour. 8.06 ml formamide was added to the resulting mixture and left for 1 month.

The obtained gel was heated in air at 50 ° C./h and baked at 700 ° C. for 2 hours to obtain mesoporous P ₂ O ₅ —SiO ₂ glass having mesh-like pores (non-patent of background art) I reviewed Reference 3). However, it was brittle after firing and the film was easily damaged. Incidentally, the thin films produced in Examples 1 to 3 were flexible and not damaged, and were excellent in handling properties.

When the conductivity of the obtained thin film was measured by the AC complex impedance method under the condition of 70% relative humidity, it was 20 mS · cm ⁻¹ at room temperature.

  From the examples and comparative examples, the thin film of the present invention was excellent in handling properties, exhibited high proton conductivity, and was useful as an electric / energy device.

  The present invention contains a metal oxide having pores having a diameter smaller than the pore diameter of the thin film in the pores of the thin film having a three-dimensional pore having a diameter of 2 nm to 500 nm, which has not been heretofore, and the metal oxide has proton conductivity. , A thin film having at least one of ion exchange properties, useful for a proton conductive membrane for a fuel cell, an electrochemical sensor application requiring an ion conductive membrane, a capacitor, and the like, and an acid catalyst membrane It is also useful as a catalyst membrane such as an ion exchange membrane and a separation membrane.

Claims (13)

Metal having pores with a diameter smaller than the pore diameter of the thin film in the pores of the thin film having three-dimensional pores having a diameter of 2 nm to 500 nm, and having at least one of proton conductivity and ion exchange properties A thin film characterized by containing an oxide. The metal oxide having a pore having a diameter smaller than the pore diameter of the thin film and having at least one of proton conductivity and ion exchange properties contains at least one kind of phosphorus atom, sulfur atom and nitrogen atom. The thin film according to claim 1. The organic polymer is in contact with the pores of a metal oxide having a pore diameter smaller than that of the thin film and having at least one of proton conductivity and ion exchange properties. The thin film according to claim 1 or 2. The thin film according to claim 3, wherein the organic polymer contains at least one functional group selected from a sulfonic acid group, a phosphoric acid group, a nitrogen-containing functional group and a carboxylic acid group. The thin film according to claim 3 or 4, wherein the organic polymer is a methanol-impermeable organic polymer. The thin film according to claim 1, wherein the thin film having pores having a diameter of 2 nm to 500 nm is ceramics. The thin film according to any one of claims 1 to 5, wherein the thin film having pores having a diameter of 2 nm to 500 nm is an organic polymer. 8. The thin film according to claim 7, wherein the organic polymer according to claim 7 contains at least one functional group selected from a sulfonic acid group, a phosphoric acid group, a nitrogen-containing functional group and a carboxylic acid group. The thin film according to claim 7 or 8, wherein the organic polymer according to claim 7 or 8 is polyimide. A metal oxide having pores with a diameter smaller than the pore size of the thin film and having at least one of proton conductivity and ion exchange properties is at least one element from groups 2 to 16 of the periodic table. The thin film according to claim 1, comprising two or more. The metal oxide having pores with a diameter smaller than that of the thin film and having at least one of proton conductivity and ion exchange properties is obtained by a sol-gel method. The thin film in any one of 1-10. The thin film according to any one of claims 1 to 10, wherein the thin film is used as an ion exchanger or a proton conducting membrane. A metal oxide having pores having a diameter smaller than the pore size of the thin film according to any one of claims 1 to 12 and having at least one property of proton conductivity and ion exchange properties in one stage ( A method for producing a thin film characterized in that it is synthesized in the pores of the thin film in one pot.