JP2017135109A - Electrode-forming composition used for microbial fuel cell, electrode, and microbial fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive electrode-forming composition for manufacturing an electrode for microbial fuel cells with excellent power generation characteristics, which is excellent in adhesion with a base material and between raw materials.SOLUTION: A composition for forming microbial fuel cell electrodes contains: a conductive material and/or an oxygen reduction catalyst; and aqueous resin fine particles. In the composition for forming microbial fuel cell electrodes, the aqueous resin minute particles contain an acrylic emulsion polymer. In the composition for forming microbial fuel cell electrodes, the conductive material is a carbon material.SELECTED DRAWING: None

Description

  The present invention relates to a composition for forming an electrode used for a microbial fuel cell, an electrode, and a microbial fuel cell.

  In recent years, development of microbial fuel cells using a fuel cell mechanism has been promoted. This is a power generation method in which electrons generated when organic substances are decomposed by microorganisms are collected and used as electric energy. For example, when it is used for purification of domestic wastewater or the like, it is expected as a water treatment method that can reduce energy consumption because decomposition treatment and power generation can be performed in parallel.

  Two tank types and one tank type are known as the shape of the microbial fuel cell. The common point is that electrons generated from the decomposition reaction by microorganisms at the anode are consumed by the reduction reaction at the cathode via the external circuit. In the two-tank type, both electrodes are separated by a partition such as an ion exchange membrane, and an oxidizing agent such as oxygen or potassium ferricyanide is reacted at the cathode. On the other hand, the single tank type does not have a partition wall, and an air cathode is provided in the same tank as the anode to react with oxygen directly in the atmosphere.

  Regardless of which method is used, for example, assuming water treatment, the electrode can withstand water pressure without peeling off components, and long-term operation is expected. Therefore, the electrode can be used as a binder for binding electrode members such as catalysts and conductive materials. Requires strong adhesion. In order to obtain high power generation performance, it is necessary to select an electrode member, particularly a resin, that does not interfere with microbial reaction and catalytic reaction, and it is desirable that the total amount of resin is small.

  At present, Nafion (registered trademark) manufactured by DuPont is often used as a resin for electrode formation, and its proton conductivity ensures adhesion without interfering with the catalytic reaction particularly at the cathode. However, its performance is not yet sufficient, and it is also mentioned that it is expensive as a problem other than the above, and earnest research is being advanced for improvement (Non-Patent Documents 1 and 2).

Environ. Sci. Technol. (2006), 40, 364-369 Journal of Power Sources (2012), 218, 100-105

  An object of the present invention is to provide an electrode-forming composition for producing an electrode for a microbial fuel cell that is excellent in adhesion between a substrate and a material and excellent in power generation characteristics, and provides an inexpensive electrode-forming composition. That is.

  As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention. That is, the present invention relates to a composition for forming a microbial fuel cell electrode containing a conductive material and / or an oxygen reduction catalyst and aqueous resin fine particles.

  The present invention also relates to the above composition for forming a microbial fuel cell electrode, wherein the aqueous resin fine particles contain an acrylic emulsion polymer.

  Moreover, this invention relates to the said composition for microbial fuel cell electrode formation whose electrically conductive material is a carbon material.

  The present invention also relates to the above composition for forming a microbial fuel cell electrode, wherein the oxygen reduction catalyst is at least one selected from the group consisting of a noble metal catalyst, a base metal oxide catalyst, a carbon catalyst and activated carbon.

  The present invention further relates to the composition for forming a microbial fuel cell electrode containing an aqueous liquid medium.

  The present invention also relates to an electrode for a microbial fuel cell, characterized by using the above composition for forming a microbial fuel cell electrode.

  Further, the present invention provides the composition according to any one of the above, wherein the composition is installed on any one of a liquid surface, a liquid, a side surface, and a bottom surface of the microbial fuel cell, and one surface is in contact with air outside the tank and the back surface is in contact with the electrolyte The present invention relates to an electrode for a microbial fuel cell.

  The present invention also relates to a microbial fuel cell using the microbial fuel cell electrode.

  According to the present invention, a composition for forming a microbial fuel cell electrode in which aqueous resin fine particles are dispersed together with a conductive material and / or an oxygen reduction catalyst has excellent adhesion between particles and a substrate when a coating film is formed. A microbial fuel cell electrode with high strength can be provided.

  In addition, since the binding between the aqueous resin fine particles and the conductive material and / or the oxygen reduction catalyst is due to point contact, for example, in the case of a catalyst having an interface as a reaction field, the catalytic reaction is hardly inhibited. Further, since the resin has excellent adhesion, a small amount of resin is required. As a result, the resistance due to the resin can be reduced. That is, a microbial fuel cell having excellent power generation performance can be provided by using a composition for forming a microbial fuel cell electrode containing a conductive material and / or an oxygen reduction catalyst and aqueous resin fine particles.

  Furthermore, since the aqueous resin fine particles can be produced at a low cost depending on the constituent monomers, the production cost of the composition for forming a microbial fuel cell electrode can be reduced.

<Composite ink for microbial fuel cells>
The composition for forming an electrode for a microbial fuel cell of the present invention (hereinafter referred to as composite ink) contains at least a conductive material and / or an oxygen reduction catalyst, aqueous resin fine particles (A), and an aqueous liquid medium. . The ratio of the conductive material and / or the oxygen reduction catalyst, the aqueous resin fine particles, and the aqueous liquid medium is not particularly limited, and can be appropriately selected within a wide range.

<Water-based resin fine particles>
The aqueous resin fine particles are those in which the resin does not dissolve in water but exists in the form of fine particles, and the aqueous dispersion is generally called an aqueous emulsion and can be used in the present invention.
Emulsions used include (meth) acrylic emulsions, nitrile emulsions, urethane emulsions, diene emulsions (such as styrene / butadiene rubber (SBR)), fluorine emulsions (polyvinylidene fluoride (PVDF) and polytetrafluoroethylene). (PTFE) and the like. Unlike the water-soluble polymer, the emulsion preferably has excellent binding properties between particles and flexibility (film flexibility).
(Particle structure of aqueous resin fine particles)
The particle structure of the aqueous resin fine particles used in the present invention can be a multilayer structure, so-called core-shell particles. For example, it is possible to localize a resin in which a monomer having a functional group is mainly polymerized in the core part or the shell part, or to provide a difference in Tg or composition between the core and the shell, thereby improving the curability and drying. Property, film formability, and mechanical strength of the binder can be improved.

(Particle diameter of aqueous resin fine particles)
The average particle diameter of the aqueous resin fine particles used in the present invention is preferably 10 to 500 nm, and more preferably 10 to 300 nm, from the viewpoint of binding properties and particle stability. Further, when a large amount of coarse particles exceeding 1 μm are contained, the stability of the particles is impaired, so that the coarse particles exceeding 1 μm are preferably at most 5% or less. In addition, the average particle diameter in the present invention represents a volume average particle diameter and can be measured by a dynamic light scattering method.

  The average particle diameter can be measured by the dynamic light scattering method as follows. The cross-linked resin fine particle dispersion is diluted with water 200 to 1000 times depending on the solid content. About 5 ml of the diluted solution is injected into a cell of a measuring apparatus [Microtrack manufactured by Nikkiso Co., Ltd.], and after inputting the solvent (water in the present invention) and the refractive index condition of the resin according to the sample, measurement is performed. The peak of the volume particle size distribution data (histogram) obtained at this time is defined as the average particle size of the present invention.

<(Meth) acrylic emulsion>
Next, the (meth) acrylic emulsion will be described. The (meth) acrylic emulsion is an emulsion polymer containing 10 parts by mass or more of a monomer having a (meth) acryloyl group, preferably 20 parts by mass or more, and more preferably 30 parts by mass or more. Good. Since the monomer having an acryloyl group is excellent in reactivity, resin fine particles can be produced relatively easily. Moreover, the coating film by a (meth) acrylic-type emulsion is excellent in adhesiveness and flexibility.

When using a (meth) acrylic-type emulsion, it is preferable to contain the crosslinked resin fine particle demonstrated below. The crosslinked resin fine particles are resin fine particles having an internal cross-linked structure (three-dimensional cross-linked structure), and it is important that the fine particles are cross-linked inside the particles. When the cross-linked resin fine particles have a cross-linked structure, the electrolytic solution elution resistance can be secured, and the effect can be enhanced by adjusting the cross-linking inside the particles. Moreover, it can contribute to adhesiveness with a base material or another electrode constituent material because bridge | crosslinking-type resin fine particle contains a specific functional group. Furthermore, by adjusting the amount of the cross-linked structure and functional group, a composite ink excellent in the durability of the microbial fuel cell can be obtained.
In addition, cross-linking of particles (cross-particle cross-linking) can be used together for cross-linking, but in this case, since a cross-linking agent is added later, leakage of the cross-linking agent component into the electrolyte or electrode preparation There may be variations. For this reason, it is necessary to use a crosslinking agent to such an extent that the electrolyte solution resistance is not impaired.

The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are obtained by emulsion polymerization of an ethylenically unsaturated monomer in water in the presence of a surfactant with a radical polymerization initiator. Resin fine particles. The (meth) acrylic emulsion suitably used in the present invention is preferably obtained by emulsion polymerization of an ethylenically unsaturated monomer containing the following monomers (C1) and (C2) in the following proportions.
(C1) From the group consisting of an ethylenically unsaturated monomer (c1) having a monofunctional or polyfunctional alkoxysilyl group and a monomer (c2) having two or more ethylenically unsaturated groups in one molecule At least one monomer selected: 0.1 to 5% by mass
(C2) Ethylenically unsaturated monomers (c3) other than the monomers (c1) to (c2): 95 to 99.9% by mass
(However, the total of (c1) to (c3) is 100% by mass)

  Of the ethylenically unsaturated monomers constituting the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, (c1) and (c3) are in one molecule unless otherwise specified. A monomer having one ethylenically unsaturated group is shown.

<About the monomer group (C1)>
The functional group (alkoxysilyl group, ethylenically unsaturated group) possessed by the monomer contained in the monomer group (C1) is a self-crosslinking reactive functional group, and is mainly used for particle internal crosslinking during particle synthesis. Has the effect of forming. Electrolytic solution resistance can be improved by sufficiently carrying out internal crosslinking of the particles. Therefore, it is possible to obtain crosslinked resin fine particles by using a monomer contained in the monomer group (C1). In addition, by sufficiently carrying out particle crosslinking, the resistance to electrolytic solution can be improved.

  Examples of the monomer (c1) having one ethylenically unsaturated group and an alkoxysilyl group in one molecule include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ- Methacryloxypropyl tributoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyl Dimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, etc. It is.

  Examples of the monomer (c2) having two or more ethylenically unsaturated groups in one molecule include allyl (meth) acrylate, 1-methylallyl (meth) acrylate, and 2-methylallyl (meth) acrylate. 1-butenyl (meth) acrylate, 2-butenyl (meth) acrylate, 3-butenyl (meth) acrylate, 1,3-methyl-3-butenyl (meth) acrylate, 2- (meth) acrylate 2- Chloroallyl, 3-chloroallyl (meth) acrylate, o-allylphenyl (meth) acrylate, 2- (allyloxy) ethyl (meth) acrylate, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, (meth) Geranyl acrylate, rosinyl (meth) acrylate, cinnamyl (meth) acrylate, diallyl maleate, diallyl itaconic acid (Meth) acrylic acid esters containing ethylenically unsaturated groups such as vinyl (meth) acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, 2- (2′-vinyloxyethoxy) ethyl (meth) acrylate ; Ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, diacryl Multifunctional (meth) acrylic acid esters such as 1,1,1-trishydroxymethylethane acid, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylpropanetriacrylic acid Divinylbenzene, divinyl adipate, etc. Vinyls; diallyl isophthalate, diallyl phthalate, etc. diallyl such as diallyl maleate and the like.

  The purpose of the alkoxysilyl group or ethylenically unsaturated group in the monomer (c1) or monomer (c2) is to introduce a cross-linked structure into the particle by self-condensation or polymerization mainly during the polymerization. However, a part of it may remain inside or on the surface after polymerization. The remaining alkoxysilyl group or ethylenically unsaturated group contributes to interparticle crosslinking of the binder composition. In particular, an alkoxysilyl group is preferable because it has an effect of improving the adhesion to a substrate.

  In this invention, the monomer contained in a monomer group (C1) is used 0.1 to 5 mass% in the whole ethylenically unsaturated monomer (100 mass% in total) used for emulsion polymerization. It is characterized by that. Preferably it is 0.5-3 mass%.

<About monomer group (C2)>
The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are the monomer (c1) having one ethylenically unsaturated group and an alkoxysilyl group in one molecule described above, In addition to the monomer (c2) having two or more ethylenically unsaturated groups in one molecule, the monomer group (C2) is ethylenic other than the monomers (c1) and (c2). The monomer (c3) having an unsaturated group can be obtained by emulsion polymerization at the same time.

The monomer (c3) is not particularly limited as long as it is a monomer other than the monomers (c1) and (c2) and has an ethylenically unsaturated group.
Monomer (c4) having one ethylenically unsaturated group and monofunctional or polyfunctional epoxy group in one molecule, one ethylenically unsaturated group and monofunctional or polyfunctional amide group in one molecule And at least one monomer selected from the group consisting of a monomer (c5) having one ethylenically unsaturated group and a monofunctional or polyfunctional hydroxyl group in one molecule (c6) And the monomer (c7) having an ethylenically unsaturated group other than the monomer and the monomers (c1), (c2), and (c4) to (c6) can be used.
By using the monomers (c4) to (c6), an epoxy group, an amide group, or a hydroxyl group can be left in the particles or the surface of the crosslinked resin fine particles. Physical properties can be improved. In the monomers (c4) to (c6), the functional group tends to remain inside or on the surface even after the synthesis of the particles, and the adhesion effect to the substrate is large even in a small amount. Moreover, a part of them may be used for the crosslinking reaction, and by adjusting the degree of crosslinking of these functional groups, it is possible to balance the resistance to electrolytic solution and the adhesion.

  Examples of the monomer (c4) having one ethylenically unsaturated group and a monofunctional or polyfunctional epoxy group in one molecule include glycidyl (meth) acrylate and 3,4-epoxycyclohexyl (meth) acrylate. Etc.

  Examples of the monomer (c5) having one ethylenically unsaturated group and a monofunctional or polyfunctional amide group in one molecule include, for example, a primary amide group-containing ethylenically unsaturated monomer such as (meth) acrylamide. N-methylol acrylamide, N, N-di (methylol) acrylamide, alkylol (meth) acrylamides such as N-methylol-N-methoxymethyl (meth) acrylamide; N-methoxymethyl- (meth) acrylamide, Monoalkoxy (meth) acrylamides such as N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meth) acrylamide, N-pentoxymethyl- (meth) acrylamide; N, N-di (methoxymethyl) acrylamide, N-ethoxy Methyl-N-methoxymethylmethacrylamide, N, N-di (ethoxymethyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N-di (propoxymethyl) acrylamide, N-butoxymethyl-N- (Propoxymethyl) methacrylamide, N, N-di (butoxymethyl) acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N-di (pentoxymethyl) acrylamide, N-methoxymethyl-N Dialkoxy (meth) acrylamides such as (pentoxymethyl) methacrylamide; dialkylamino (meth) acrylamides such as N, N-dimethylaminopropylacrylamide and N, N-diethylaminopropylacrylamide; N, N- Methyl acrylamide, N, N-dialkyl such as diethyl acrylamide (meth) acrylamides; and diacetone (meth) keto group, such as acrylamide-containing (meth) acrylamides and the like.

  Examples of the monomer (c6) having one ethylenically unsaturated group and a monofunctional or polyfunctional hydroxyl group in one molecule include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. 4-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, glycerol mono (meth) acrylate, 4-hydroxyvinylbenzene, 1-ethynyl-1-cyclohexanol, allyl Examples include alcohol.

  Some of the functional groups of the monomers contained in the monomers (c4) to (c6) may react during particle polymerization and be used for intraparticle crosslinking. In this invention, the monomer contained in monomer (c4)-(c6) is 0.1-20 mass% in the whole ethylenically unsaturated monomer (100 mass% in total) used for emulsion polymerization. It is used. Preferably it is 1-15 mass%, Most preferably, it is 2-10 mass%.

  The monomer (c7) is not particularly limited as long as it is a monomer having an ethylenically unsaturated group other than the monomers (c1), (c2), and (c4) to (c6). For example, a monomer (c8) having one ethylenically unsaturated group and an alkyl group having 8 to 18 carbon atoms in one molecule, one ethylenically unsaturated group in one molecule, and a cyclic structure And the monomer (c9). When the monomer (c8) and / or the monomer (c9) is used for the emulsion polymerization as the monomer (c7) (including other monomers as the monomer (c7)) The monomers (c8) and (c9) are all monomers having an ethylenically unsaturated group ((c1), (c2), (c4) to (c6) and (c7)). It is preferable that 30-95 mass% is contained in total. It is preferable to use the monomer (c8) or the monomer (c9) because the particle stability during particle synthesis and the resistance to electrolytic solution are excellent.

  Examples of the monomer (c8) having one ethylenically unsaturated group and an alkyl group having 8 to 18 carbon atoms in one molecule include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and myristyl. (Meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned.

  Examples of the monomer (c9) having one ethylenically unsaturated group and a cyclic structure in one molecule include alicyclic ethylenically unsaturated monomers and aromatic ethylenically unsaturated monomers. It is done. Examples of the alicyclic ethylenically unsaturated monomer include cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and examples of the aromatic ethylenically unsaturated monomer include benzyl (meth) acrylate. Phenoxyethyl (meth) acrylate, styrene, α-methylstyrene, 2-methylstyrene, chlorostyrene, allylbenzene, ethynylbenzene and the like.

  Examples of the monomer (c7) other than the monomer (c8) and the monomer (c9) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth). ) Alkyl group-containing ethylenically unsaturated monomers such as acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate; nitrile group-containing ethylenically unsaturated monomers such as (meth) acrylonitrile; perfluoromethylmethyl (meta ) Acrylate, perfluoroethylmethyl (meth) acrylate, 2-perfluorobutylethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorooctylethyl (meth) acrylate, 2-perfluoroiso Nonylethyl (meth) acrylate, 2-par Fluorononylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, perfluoropropylpropyl (meth) acrylate, perfluorooctylpropyl (meth) acrylate, perfluorooctyl amyl (meth) acrylate, perfluorooctylun Perfluoroalkyl group-containing ethylenically unsaturated monomer having 1 to 20 carbon atoms such as decyl (meth) acrylate; perfluorobutylethylene, perfluorohexylethylene, perfluorooctylethylene, perfluorodecyl Perfluoroalkyl such as ethylene, perfluoroalkyl group-containing ethylenically unsaturated compounds such as alkylene; polyethylene glycol (meth) acrylate, methoxypolyethylene Glycol (meth) acrylate, ethoxypolyethyleneglycol (meth) acrylate, propoxypolyethyleneglycol (meth) acrylate, n-butoxypolyethyleneglycol (meth) acrylate, n-pentoxypolyethyleneglycol (meth) acrylate, phenoxypolyethyleneglycol (meth) acrylate , Polypropylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, propoxypolypropylene glycol (meth) acrylate, n-butoxypolypropylene glycol (meth) acrylate, n-pentoxypolypropylene glycol (meta ) Acrylate, phenoxy polypropylene glycol (Meth) acrylate, polytetramethylene glycol (meth) acrylate, methoxypolytetramethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, hexaethylene glycol (meth) acrylate, methoxyhexaethylene glycol (meth) acrylate Ethylenically unsaturated compounds having a polyether chain such as: ethylenically unsaturated compounds having a polyester chain such as a lactone-modified (meth) acrylate; (meth) acrylic acid dimethylaminoethyl methyl chloride salt, trimethyl-3- (1- (Meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) ammonium chloride, and trime Quaternary ammonium base-containing ethylenically unsaturated compounds such as ru-3- (1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride; vinyl acetate, vinyl butyrate, vinyl propionate, vinyl hexanoate, caprylic acid Fatty acid vinyl compounds such as vinyl, vinyl laurate, vinyl palmitate and vinyl stearate; Vinyl ether ethylenically unsaturated monomers such as butyl vinyl ether and ethyl vinyl ether; 1-hexene, 1-octene, 1-decene, 1 Α-olefinic ethylenically unsaturated monomers such as dodecene, 1-tetradecene and 1-hexadecene; allyl monomers such as allyl acetate and allyl cyanide; vinyl such as vinyl cyanide, vinylcyclohexane and vinylmethylketone Monomer; acetylene, ethynyl Examples include ethynyl monomers such as toluene.

  Examples of the monomer (c7) other than the monomer (c8) and monomer (c9) include maleic acid, fumaric acid, itaconic acid, citraconic acid, and alkyl or alkenyl monoesters thereof. , Phthalic acid β- (meth) acryloxyethyl monoester, isophthalic acid β- (meth) acryloxyethyl monoester, terephthalic acid β- (meth) acryloxyethyl monoester, succinic acid β- (meth) acryloxyethyl Carboxyl group-containing ethylenically unsaturated monomers such as monoesters, acrylic acid, methacrylic acid, crotonic acid and cinnamic acid; Tertiary butyl group-containing ethylenically unsaturated monomers such as tertiary butyl (meth) acrylate; Sulfonic acid group-containing ethylenically unsaturated monomers such as vinyl sulfonic acid and styrene sulfonic acid; -Hydroxyethyl) methacrylate unsaturated phosphate-containing ethylenically unsaturated monomers; diacetone (meth) acrylamide, acrolein, N-vinylformamide, vinyl methyl ketone, vinyl ethyl ketone, acetoacetoxyethyl (meth) Keto group-containing ethylenically unsaturated monomers such as acrylate, acetoacetoxypropyl (meth) acrylate, acetoacetoxybutyl (meth) acrylate (monomers having one ethylenically unsaturated group and a keto group in one molecule) Body).

  When a keto group-containing ethylenically unsaturated monomer is used as the monomer (c7), a polyfunctional hydrazide compound having two or more hydrazide groups capable of reacting with a keto group as a crosslinking agent is mixed with the binder composition. A tough coating film can be obtained by crosslinking between a keto group and a hydrazide group. This has excellent electrolytic solution resistance and binding properties.

  Among the monomers (c7), an ethylenically unsaturated monomer having a carboxyl group, a tertiary butyl group (tertiary butanol is removed by heat to form a carboxyl group), a sulfonic acid group, and a phosphoric acid group. The resin fine particles obtained by copolymerization of the body have the effect of improving the physical properties such as adhesion of the base material, while the functional groups remain in the particles and on the surface after polymerization, and at the same time agglomerate during synthesis. It can be preferably used because it may prevent or maintain the particle stability after synthesis.

  A part of the carboxyl group, tertiary butyl group, sulfonic acid group, and phosphoric acid group may react during polymerization and be used for intraparticle crosslinking. In the case of using a monomer containing a carboxyl group, a tertiary butyl group, a sulfonic acid group, and a phosphoric acid group, the total amount of ethylenically unsaturated monomers (100% by mass in total) used in the emulsion polymerization is 0. The content is preferably 1 to 10% by mass, and more preferably 1 to 5% by mass. Furthermore, these functional groups may react during drying and be used for cross-linking within or between particles.

  For example, a carboxyl group can react with an epoxy group during polymerization and drying to introduce a crosslinked structure into the resin fine particles. Similarly, a tertiary butyl group can react with an epoxy group in the same manner as described above since tertiary butyl alcohol is generated and a carboxyl group is formed when heat of a certain temperature or higher is applied.

  These monomers (c7) are used in combination of two or more of the above-mentioned monomers in order to adjust the polymerization stability and glass transition temperature of the particles, as well as the film formability and film properties. Can be used. Further, for example, by using (meth) acrylonitrile in combination, there is an effect that rubber elasticity is exhibited.

<Method for Producing Crosslinked Resin Fine Particles in (Meth) Acrylic Emulsion Suitable for Use in the Present Invention>
The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are synthesized by a conventionally known emulsion polymerization method.

<Emulsifier used in emulsion polymerization>
As the emulsifier used in the emulsion polymerization in the present invention, a conventionally known one such as a reactive emulsifier having an ethylenically unsaturated group or a non-reactive emulsifier having no ethylenically unsaturated group may be arbitrarily used. it can.

  Reactive emulsifiers having an ethylenically unsaturated group can be further roughly classified into anionic and nonionic nonionic ones. In particular, when an anionic reactive emulsifier or nonionic reactive emulsifier having an ethylenically unsaturated group is used, the dispersion particle size of the copolymer becomes finer and the particle size distribution becomes narrower. This is preferable. These anionic reactive emulsifiers or nonionic reactive emulsifiers having an ethylenically unsaturated group may be used singly or in combination.

  Specific examples of the anionic reactive emulsifier having an ethylenically unsaturated group are illustrated below, but the emulsifiers that can be used in the present invention are not limited to those described below.

  As an emulsifier, an alkyl ether type (as commercial products, for example, Aqualon KH-05, KH-10, KH-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adeka Soap SR-10N, SR-20N manufactured by ADEKA Co., Ltd., Laterum PD-104 manufactured by Kao Corporation); sulfosuccinic acid ester system (for example, LATEMUL S-120, S-120A, S-180P, S-180A manufactured by Kao Corporation, Elemiol manufactured by Sanyo Chemical Co., Ltd.) JS-2 etc.); alkylphenyl ether type or alkylphenyl ester type (commercially available products include, for example, Aqualon H-2855A, H-3855B, H-3855C, H-3856, HS-05 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) , HS-10, HS-20, HS-30, ADEKA Corporation ADEKA rear SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N, etc.) (meth) acrylate sulfate ester (commercially available products include, for example, Japanese emulsifiers) Antox MS-60, MS-2N, Sanyo Kasei Kogyo Co., Ltd., Eleminol RS-30, etc.); Phosphate ester (for example, H-3330PL, Daiichi Kogyo Seiyaku Co., Ltd., stock) Adeka Soap PP-70 manufactured by the company ADEKA).

  Nonionic reactive emulsifiers that can be used in the present invention include, for example, alkyl ether-based (commercially available products such as Adeka Soap ER-10, ER-20, ER-30, ER-40, manufactured by ADEKA Corporation, Laterum PD-420, PD-430, PD-450, etc. manufactured by Kao Corporation; alkyl phenyl ethers or alkyl phenyl esters (for example, Aqualon RN-10, RN- manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 20, RN-30, RN-50, ADEKA Corporation ADEKA rear soap NE-10, NE-20, NE-30, NE-40, etc.); (meth) acrylate sulfate ester system (commercially available products include, for example, RMA-564, RMA-568, RMA-1114, etc. manufactured by Nippon Emulsifier Co., Ltd.) .

  When the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are obtained by emulsion polymerization, together with the above-described reactive emulsifier having an ethylenically unsaturated group, an ethylenically unsaturated group may be used. Non-reactive emulsifiers that do not have any can be used in combination. Non-reactive emulsifiers can be broadly classified into non-reactive anionic emulsifiers and non-reactive nonionic emulsifiers.

  Examples of non-reactive nonionic emulsifiers include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkyl such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether Sorbitan monolaurate, sorbitan monostearate, sorbitan higher fatty acid esters such as sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate, Polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate; oleic acid monoglyceride, stearic acid monoglyceride Glycerine higher fatty acid esters such as chloride, polyoxyethylene-polyoxypropylene block copolymers, and the like can be exemplified polyoxyethylene distyrenated phenyl ether.

  Examples of non-reactive anionic emulsifiers include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate esters such as sodium lauryl sulfate; polyoxyethylene lauryl ether Polyoxyethylene alkyl ether sulfates such as sodium sulfate; polyoxyethylene alkylaryl ether sulfates such as polyoxyethylene nonylphenyl ether sodium sulfate; sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, polyoxyethylene lauryl sulfosuccinic acid Alkylsulfosuccinic acid ester salts such as sodium and derivatives thereof; polyoxyethylene distyrenated phenyl ether And the like can be exemplified sulfuric ester salts.

  The usage-amount of the emulsifier used in this invention is not necessarily limited, It can select suitably according to the physical property calculated | required when crosslinked type resin microparticles are used as a final binder. For example, the emulsifier is usually preferably 0.1 to 30 parts by mass, more preferably 0.3 to 20 parts by mass with respect to a total of 100 parts by mass of the ethylenically unsaturated monomers. More preferably, it is in the range of 5 to 10 parts by mass.

  In emulsion polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, a water-soluble protective colloid can be used in combination. Examples of water-soluble protective colloids include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose salt; Examples thereof include saccharides, and these can be used alone or in a combination of plural kinds. The amount of the water-soluble protective colloid used is 0.1 to 5 parts by mass, more preferably 0.5 to 2 parts by mass per 100 parts by mass in total of the ethylenically unsaturated monomers.

<Aqueous medium used in emulsion polymerization>
Examples of the aqueous medium used in the emulsion polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention include water, and a hydrophilic organic solvent does not impair the object of the present invention. Can be used in

<Polymerization initiator used in emulsion polymerization>
The polymerization initiator used for obtaining the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention is not particularly limited as long as it has the ability to initiate radical polymerization, and is known in the art. Oil-soluble polymerization initiators and water-soluble polymerization initiators can be used.

  The oil-soluble polymerization initiator is not particularly limited, and examples thereof include benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, tert-butyl peroxy (2-ethylhexanoate), and tert-butyl peroxide. Organic peroxides such as oxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4- Examples thereof include azobis compounds such as dimethylvaleronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobiscyclohexane-1-carbonitrile. These can be used alone or in combination of two or more. These polymerization initiators are preferably used in an amount of 0.1 to 10.0 parts by mass with respect to 100 parts by mass of the ethylenically unsaturated monomer.

  In the present invention, it is preferable to use a water-soluble polymerization initiator. For example, ammonium persulfate, potassium persulfate, hydrogen peroxide, 2,2′-azobis (2-methylpropionamidine) dihydrochloride and the like are conventionally known. A thing can be used conveniently. Moreover, when performing emulsion polymerization, a reducing agent can be used together with a polymerization initiator if desired. Thereby, it becomes easy to accelerate the emulsion polymerization rate or to perform the emulsion polymerization at a low temperature. Examples of such a reducing agent include reducing organic compounds such as metal salts such as ascorbic acid, ersorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate, sodium thiosulfate, sodium sulfite, sodium bisulfite, Examples include reducing inorganic compounds such as sodium bisulfite, ferrous chloride, Rongalite, thiourea dioxide, and the like. These reducing agents are preferably used in an amount of 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the total ethylenically unsaturated monomer.

<Conditions for emulsion polymerization>
In addition, it can superpose | polymerize by a photochemical reaction, radiation irradiation, etc. irrespective of an above described polymerization initiator. The polymerization temperature is not less than the polymerization start temperature of each polymerization initiator. For example, in the case of a peroxide-based polymerization initiator, it may be usually about 70 ° C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.

<Other materials used for reaction>
Further, if necessary, sodium acetate, sodium citrate, sodium bicarbonate, etc. as a buffering agent, and octyl mercaptan, 2-ethylhexyl thioglycolate, octyl thioglycolate, stearyl mercaptan, lauryl mercaptan as a chain transfer agent A suitable amount of mercaptans such as t-dodecyl mercaptan can be used.

  When a monomer having an acidic functional group such as a carboxyl group-containing ethylenically unsaturated monomer is used for polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, Or can be neutralized with a basic compound after polymerization. When neutralizing, it can be neutralized with ammonia or alkylamines such as trimethylamine, triethylamine and butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine and aminomethylpropanol; and a base such as morpholine. . However, it is a highly volatile base that is highly effective in drying, and preferred bases are aminomethylpropanol and ammonia.

<Uncrosslinked compound (E) to be added to polymerized resin fine particles> Platinum-supported carbon The (meth) acrylic emulsion suitably used in the present invention is an uncrosslinked epoxy group in addition to the crosslinked resin fine particles. At least one uncrosslinked compound (E) selected from the group consisting of a containing compound, an uncrosslinked amide group-containing compound, an uncrosslinked hydroxyl group-containing compound, and an uncrosslinked oxazoline group-containing compound [hereinafter referred to as Compound (E) and In some cases, it may be expressed. The compound (E) is a compound that does not dissolve in the aqueous liquid medium and is dispersed.

  The “uncrosslinked functional group-containing compound” which is the compound (E) is the interior of the (meth) acrylic emulsion that is preferably used in the present invention as in the monomer included in the monomer group (C1). Unlike a compound that forms a cross-linked structure (three-dimensional cross-linked structure), it refers to a compound that is added after emulsion polymerization (polymer formation) of resin fine particles (does not participate in internal cross-linking of resin fine particles). That is, “uncrosslinked” means that it is not involved in the formation of an internal crosslinked structure (three-dimensional crosslinked structure) of the (meth) acrylic emulsion suitably used in the present invention.

  The (meth) acrylic emulsion suitably used in the present invention has a cross-linked structure to ensure the resistance to electrolyte, and by using the compound (E), an epoxy group in the compound (E), At least one functional group selected from an amide group, a hydroxyl group, and an oxazoline group can contribute to adhesion to the substrate or another electrode constituent material. Furthermore, by adjusting the amount of the cross-linked structure and functional group, a composite ink excellent in the durability of the microbial fuel cell can be obtained.

  The crosslinked resin fine particles in the (meth) acrylic emulsion preferably used in the present invention must be crosslinked inside the particles. Electrolytic solution resistance can be ensured by appropriately adjusting the crosslinking inside the particles. Furthermore, the functional group-containing crosslinked resin fine particles are at least one selected from the group consisting of an uncrosslinked epoxy group-containing compound, an uncrosslinked amide group-containing compound, an uncrosslinked hydroxyl group-containing compound, and an uncrosslinked oxazoline group-containing compound. By adding the uncrosslinked compound (E), an epoxy group, an amide group, a hydroxyl group or an oxazoline group can act on the base material and effectively improve the adhesion to the base material and other electrode constituent materials. it can. Since the functional group contained in the compound (E) is stable by heat during long-term storage or electrode production, the effect of adhesion to a substrate is large even when used in a small amount. Furthermore, it is excellent in storage stability. The compound (E) may react with the functional group in the cross-linked resin fine particles for the purpose of adjusting the flexibility and the electrolytic solution resistance of the binder. If the functional group in the compound (E) is used too much for the reaction, the functional group capable of interacting with the substrate or the electrode is reduced. For this reason, the reaction between the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention and the compound (E) does not impair the adhesion to the substrate or other electrode constituent materials. There must be. Further, when a part of the functional group contained in the compound (E) is used for the crosslinking reaction [when the compound (E) is a polyfunctional compound], by adjusting the degree of crosslinking of these functional groups, It is possible to balance the resistance to electrolytic solution and the adhesion.

<Uncrosslinked epoxy group-containing compound>
Examples of the uncrosslinked epoxy group-containing compound include epoxy group-containing ethylenically unsaturated monomers such as glycidyl (meth) acrylate and 3,4-epoxycyclohexyl (meth) acrylate; Radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers containing monomers; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol Diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) Cyclohexane Polyfunctional epoxy compounds; bisphenol A- epichlorohydrin epoxy resins, and epoxy resins such as bisphenol F- epichlorohydrin type epoxy resin.

  Among epoxy group-containing compounds, in particular, epoxy resins such as bisphenol A-epichlorohydrin type epoxy resins and bisphenol F-epichlorohydrin type epoxy resins, and ethylenically unsaturated monomers containing epoxy group-containing ethylenically unsaturated monomers. A radical polymerization resin obtained by polymerizing a saturated monomer is preferred. The epoxy resin can be expected to have a synergistic effect of improving the electrolytic solution resistance by having a bisphenol skeleton and improving the adhesion of the substrate by the hydroxyl group contained in the skeleton. In addition, a radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer including an epoxy group-containing ethylenically unsaturated monomer has a substrate adhesion by having more epoxy groups in the resin skeleton. By improving and being resin, the effect which improves electrolyte solution resistance compared with a monomer can be anticipated.

<Uncrosslinked amide group-containing compound>
As an uncrosslinked amide group-containing compound, for example, a primary amide group-containing compound such as (meth) acrylamide; N-methylolacrylamide, N, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meta) ) Alkylol (meth) acrylamide compounds such as acrylamide; N-methoxymethyl- (meth) acrylamide, N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meta ) Monoalkoxy (meth) acrylamide compounds such as acrylamide and N-pentoxymethyl- (meth) acrylamide; N, N-di (methoxymethyl) acrylamide, N-ethoxymethyl-N-methoxymethylmethacrylamide, N, N -Di (Etoki Methyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N-di (propoxymethyl) acrylamide, N-butoxymethyl-N- (propoxymethyl) methacrylamide, N, N-di (butoxymethyl) Dialkoxy (meth) acrylamides such as acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N-di (pentoxymethyl) acrylamide, N-methoxymethyl-N- (pentoxymethyl) methacrylamide Compounds; dialkylamino (meth) acrylamide compounds such as N, N-dimethylaminopropylacrylamide and N, N-diethylaminopropylacrylamide; N, N-dimethylacrylamide and N, N-diethylacrylamide Any dialkyl (meth) acrylamide compound; keto group-containing (meth) acrylamide compound such as diacetone (meth) acrylamide or the like, and the above amide group-containing ethylenically unsaturated monomers; Examples thereof include a radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing a monomer.

  Among the amide group-containing compounds, radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers including amide group-containing ethylenically unsaturated monomers such as acrylamide are particularly preferable. By having more amide groups in the resin skeleton, the substrate adhesion can be improved, and by using the resin, the effect of improving the resistance to electrolytic solution can be expected compared to the monomer.

<Uncrosslinked hydroxyl group-containing compound>
Examples of the uncrosslinked hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate 4-hydroxyvinylbenzene, Hydroxyl group-containing ethylenically unsaturated monomers such as 1-ethynyl-1-cyclohexanol and allyl alcohol; radical polymerization obtained by polymerizing ethylenically unsaturated monomers containing the hydroxyl group-containing ethylenically unsaturated monomers Resins: linear aliphatic diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol; propylene glycol, neopentyl glycol 3-methyl-1,5 Pentanediol, 2,2-branched aliphatic diols such as diethyl-1,3-propanediol; and 1,4-bis cyclic diol such as (hydroxymethyl) cyclohexane.

  Among the hydroxyl group-containing compounds, radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers including a hydroxyl group-containing ethylenically unsaturated monomer or cyclic diols are particularly preferable. A radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing a hydroxyl group-containing ethylenically unsaturated monomer improves the substrate adhesion by having more hydroxyl groups in the resin skeleton. Moreover, the effect which improves electrolyte solution resistance can be anticipated compared with a monomer by being resin. Moreover, cyclic diols can be expected to have an effect of improving the resistance to electrolytic solution by having a cyclic structure in the skeleton.

<Uncrosslinked oxazoline group-containing compound>
Examples of the uncrosslinked oxazoline group-containing compound include 2′-methylenebis (2-oxazoline), 2,2′-ethylenebis (2-oxazoline), and 2,2′-ethylenebis (4-methyl-2-oxazoline). ), 2,2′-propylenebis (2-oxazoline), 2,2′-tetramethylenebis (2-oxazoline), 2,2′-hexamethylenebis (2-oxazoline), 2,2′-octamethylene Bis (2-oxazoline), 2,2′-p-phenylenebis (2-oxazoline), 2,2′-p-phenylenebis (4,4′-dimethyl-2-oxazoline), 2,2′-p -Phenylenebis (4-methyl-2-oxazoline), 2,2'-p-phenylenebis (4-phenyl-2-oxazoline), 2,2'-m-phenylenebis (2-oxazoline), 2 , 2′-m-phenylenebis (4-methyl-2-oxazoline), 2,2′-m-phenylenebis (4,4′-dimethyl-2-oxazoline), 2,2′-m-phenylenebis ( 4-phenylenebis-2-oxazoline), 2,2′-o-phenylenebis (2-oxazoline), 2,2′-o-phenylenebis (4-methyl-2-oxazoline), 2,2′-bis (2-oxazoline), 2,2′-bis (4-methyl-2-oxazoline), 2,2′-bis (4-ethyl-2-oxazoline), 2,2′-bis (4-phenyl-2) -Oxazoline), and further an oxazoline group-containing radical polymerization resin.

  Among oxazoline group-containing compounds, in particular, phenylene bis-type oxazoline compounds such as 2′-p-phenylenebis (2-oxazoline), or ethylenically unsaturated monomers containing an oxazoline group-containing ethylenically unsaturated monomer A radical polymerization resin obtained by polymerizing is preferred. The phenylenebis type oxazoline compound has an effect of improving the resistance to electrolytic solution by having a phenyl group in the skeleton. In addition, a radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing an oxazoline group-containing ethylenically unsaturated monomer has a substrate adhesion by having more oxazoline groups in the resin skeleton. By improving and being resin, compared with a monomer, electrolyte solution resistance can be improved.

(Addition amount of compound (E), molecular weight)
Compound (E) is preferably added in an amount of 0.1 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the solid content of the cross-linked resin fine particles. Furthermore, two or more types of compounds (E) can be used in combination.

  Although the molecular weight of a compound (E) is not specifically limited, It is preferable that a mass mean molecular weight is 1,000-1,000,000, Furthermore, 5,000-500,000 are more preferable. In addition, the said mass mean molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

<Conductive material>
Next, the conductive material will be described. The conductive material is contained to increase the electron conductivity at the electrode and facilitate the redox reaction. Although carbon materials are mainly mentioned here, the material is not limited to this.
The carbon material which is a conductive material used in the present invention is not particularly limited as long as it is a carbon material having conductivity, but carbon black, graphite, conductive carbon fiber (carbon nanotube, carbon nanofiber, carbon fiber) ), Graphene, fullerene and the like can be used alone or in combination of two or more.

  Carbon black is a furnace black produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially ketjen black using ethylene heavy oil as a raw material. Channel black that has been rapidly cooled and precipitated, thermal black obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and particularly various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used in combination. Ordinarily oxidized carbon black, hollow carbon and the like can also be used.

As the specific surface area of the carbon black used increases, the number of contact points between the carbon black particles increases, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) determined from the amount of nitrogen adsorbed is 20 m ² / g or more and 1500 m ² / g or less, preferably 50 m ² / g or more and 1500 m ² / g or less, more preferably 100 m ^2. / G or more and 1500 m ² / g or less are desirable.

  Further, the particle size of the carbon black to be used is preferably 0.005 to 1 μm, particularly preferably 0.01 to 0.2 μm in terms of primary particle size. However, the primary particle diameter here is an average of the particle diameters measured with an electron microscope or the like.

  It is desirable that the dispersed particle size of the carbon material, which is a conductive material, in the composite ink is refined to 0.03 μm or more and 5 μm or less.

  The dispersed particle size referred to here is a particle size (D50) that is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. A particle size distribution meter such as a dynamic light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.).

Examples of commercially available carbon black include Toka Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Furnace Black), Printex L and the like (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA
, Conductex 975 ULTRA, etc., PUER BLACK100, 115, 2
05, etc. (Columbian, Furnace Black), # 2350, # 2400B, # 2600B, # 3050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B, etc. (Mitsubishi Chemical, Furnace Black), MONARCH1400, 1300, 900, Vulcan XC-72R, BlackPearls 2000, etc. (Cabot, Furnace Black), Ensaco 250G, Ensaco 260G, Ensaco 350G, SuperP-Li (manufactured by TIMCAL), Ketjen Black EC-300J, EC-600JD (manufactured by Akzo) Examples of graphite such as Denka Black, Denka Black HS-100, FX-35 (manufactured by Denka Co., acetylene black) include artificial graphite, flake graphite, and lump. Graphite, including but natural graphite such as earthy graphite, is not limited thereto, may be used in combination of two or more.

  As the conductive carbon fibers, those obtained by firing from petroleum-derived raw materials are preferable, but those obtained by firing from plant-derived raw materials can also be used. For example, VGCF manufactured by Showa Denko Co., Ltd. manufactured with petroleum-derived raw materials can be mentioned.

<Oxygen reduction catalyst>
Next, the oxygen reduction catalyst will be described. Examples of the oxygen reduction catalyst include a noble metal catalyst, a base metal oxide catalyst, a carbon catalyst, and activated carbon. These may be used alone or in combination of two or more.

(Precious metal catalyst)
The noble metal catalyst is a catalyst containing at least one element selected from ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold among transition metal elements. These noble metal catalysts may be used alone or supported on another element or compound. Of these, a catalyst-supporting carbon material is a good example. The catalyst-carrying carbon material refers to a material in which catalyst particles are carried on a carbon material as a catalyst carrier, and there are known and commercially available materials.

  The supporting rate of the catalyst particles on the carbon material is not limited. When platinum is used as the catalyst particles, it can normally be supported up to about 1 to 70% by mass with respect to 100% by mass of the catalyst particles.

The carbon material as the catalyst carrier used in the present invention is not particularly limited as long as it is a carbon particle obtained by heat treating carbon particles derived from inorganic materials and / or organic materials.
Carbon particles derived from inorganic materials include carbon black (furnace black, acetylene black, ketjen black, medium thermal carbon black), activated carbon, graphite, carbon nanotube, carbon nanofiber, carbon nanohorn, graphene nanoplatelet, nanoporous carbon, Carbon fiber etc. are mentioned. Carbon materials have various physical properties and costs, such as particle size, shape, BET specific surface area, pore volume, pore diameter, bulk density, DBP oil absorption, surface acidity, surface hydrophilicity, and conductivity, depending on the type and manufacturer. Because they are different, the optimum material is selected according to the intended use and required performance.
The organic material that becomes the carbon particles after the heat treatment is not particularly limited as long as the material becomes the carbon particles after the heat treatment. Specific organic materials include phenolic resins, polyimide resins, polyamide resins, polyamideimide resins, polyacrylonitrile resins, polyaniline resins, phenol formaldehyde resin resins, polyimidazole resins, polypyrrole resins, poly Examples thereof include benzimidazole resins, melamine resins, pitch, lignite, polycarbodiimide, biomass, protein, humic acid, and derivatives thereof.
These carbon materials are used alone or in combination of two or more.

Examples of commercially available catalyst-supporting carbon materials include platinum-supporting carbon particles such as TEC10E50E, TEC10E70TPM, TEC10V30E, TEC10V50E, and TEC66E50 manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .;
Platinum-ruthenium alloy-supported carbon particles such as TEC66E50 and TEC62E58;
Can be purchased, but is not limited to these.

(Base metal oxide catalyst)
The base metal oxide catalyst used in the present invention is at least one selected from the group consisting of zirconium, tantalum, titanium, niobium, vanadium, iron, manganese, cobalt, nickel, copper, zinc, chromium, tungsten, and molybdenum. Oxides containing transition metals can be used, and carbonitrides of these transition metal elements and carbonitrid oxides of these transition metal elements can be used more preferably.

Composition formula of the base metal oxide catalysts are, for example, M1C _p N _q O _r (although, M1 is a transition metal element, p, q, r represents the ratio of the number of atoms, 0 ≦ p ≦ 3,0 ≦ q ≦ 2, 0 <r ≦ 3), M2 _a M3 _b C _x N _y O _z (where M2 is zirconium, tantalum, titanium, niobium, vanadium, iron, manganese, cobalt, nickel, copper, A metal selected from the group consisting of zinc, chromium, tungsten, and molybdenum, and M3 is at least one metal different from M2 selected from the group: a, b, x, y , Z represents the ratio of the number of atoms, 0.5 ≦ a <1, 0 <b ≦ 0.5, 0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, and a + b = 1. .) Moreover, the catalyst which compounded these compounds and electroconductive compounds can also be used conveniently.

(Carbon catalyst)
The carbon catalyst is a carbon catalyst produced by mixing one or more kinds of carbon materials and a compound containing a nitrogen element and a base metal element and performing a heat treatment, and a conventionally known one can be used. The carbon material used for the carbon catalyst is not particularly limited as long as it is a carbon particle obtained by heat-treating an inorganic material-derived carbon particle and / or an organic material. In general, the active point of the carbon catalyst includes a base metal element contained in a base metal-N4 structure (a structure in which four nitrogen elements are arranged on a plane centering on a base metal element) on the surface of the carbon particle, Examples thereof include carbon elements near the nitrogen element introduced into the edge portion. Therefore, it is important for the carbon catalyst to contain the nitrogen element and the base metal element constituting the active site in order to have oxygen reduction activity. Further, the carbon catalyst, BET specific surface area of preferably 20~2000m ² / g, more preferably 40~1000m ² / g, more preferably 60~600m ² / g.

  As carbon particles derived from inorganic materials, for example, carbon black such as furnace black, acetylene black, ketjen black, and medium thermal carbon black: activated carbon, graphite, carbon nanotube, carbon nanofiber, carbon nanohorn, graphene, graphene nanoplatelet And nanoporous carbon and carbon fiber. Depending on the type and manufacturer, the carbon particles have various physical properties such as particle diameter, shape, BET specific surface area, pore volume, pore diameter, bulk density, DBP oil absorption, surface acid basicity, surface hydrophilicity, conductivity, Since the costs are different, the most suitable material can be selected according to the intended use and required performance. One kind or two or more kinds of inorganic carbon particles are used.

  As the carbon particles derived from the inorganic material, graphene nanoplatelets, carbon black, carbon nanotubes and the like are preferably used because a carbon catalyst having a large specific surface area and high electron conductivity can be easily obtained.

  The organic material that becomes the carbon particles after the heat treatment is not particularly limited as long as the material becomes the carbon particles after the heat treatment. In order to contain the hetero element which becomes an active site in the carbon particle after heat processing, use of the organic material which contains the same hetero element beforehand may be preferable. Specific organic materials include phenolic resins, polyimide resins, polyamide resins, polyamideimide resins, polyacrylonitrile resins, polyaniline resins, phenol formaldehyde resin resins, polyimidazole resins, polypyrrole resins, poly Examples thereof include benzimidazole resins, melamine resins, pitch, lignite, polycarbodiimide, biomass, protein, humic acid, and derivatives thereof.

The compound containing nitrogen element and base metal element is not particularly limited as long as it is a compound containing one or more kinds of nitrogen element and base metal element and does not depart from the gist of the present invention. Examples thereof include organic compounds such as pigments and polymers containing metals, and inorganic compounds such as simple metals, base metal oxides, and metal salts. The said compound can be used 1 type or in combination of 2 or more types. Base metal elements are metal elements excluding noble metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) among transition metal elements. Base metal elements include cobalt, iron, nickel, manganese, and copper. It is preferable to contain at least one selected from titanium, vanadium, chromium, zinc, tin, aluminum, zirconium, niobium, tantalum, and magnesium.
From the viewpoint of efficiently introducing a nitrogen element or a base metal element into the carbon catalyst, an aromatic compound containing nitrogen capable of containing the base metal element in the molecule is preferable. Specific examples include phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, tetraazaannulene compounds, and the like. The aromatic compound may have an electron-withdrawing functional group or an electron-donating functional group introduced therein. In particular, a phthalocyanine compound is particularly preferable as a raw material because compounds containing various base metal elements are available and inexpensive. Specific examples include metal phthalocyanine compounds such as cobalt phthalocyanine compounds, nickel phthalocyanine compounds, and iron phthalocyanine compounds. By using these raw materials, it is possible to provide a carbon catalyst that is inexpensive and has high oxygen reduction activity.

  The method for producing the carbon catalyst is not particularly limited, and a method of carbonizing a cyclic organic compound supported on the surface of a carbon support, a method of carbonizing a mixture of a cyclic organic compound and another organic material, or carbonizing an organic material not containing a cyclic organic compound. A conventionally known method such as a method of using carbon particles derived from an inorganic carbon material can be used. A preferred production method is a method of obtaining a carbon catalyst by mixing carbon particles derived from an inorganic carbon material and a compound containing a nitrogen element and a base metal element, followed by heat treatment in an inert gas atmosphere. The heat treatment may be performed in a plurality of stages at a plurality of temperatures, and may include a step of washing with an acid and drying after or during the heat treatment step.

(Activated carbon)
Specific examples of the activated carbon include activated carbon activated with phenol, coconut shell, rayon, acrylic, coal-petroleum pitch coke, mesocarbon microbeads (MCMB) and the like. Those having a large specific surface area that can form an interface with a larger area even with the same mass are preferred. Specifically, the specific surface area is preferably 30 m ² / g or more, more preferably 500 to 5000 m ² / g, and still more preferably 1000 to 3000 m ² / g.

<Aqueous liquid medium>
As the aqueous liquid medium used in the present invention, it is preferable to use water, but if necessary, for example, a liquid medium compatible with water is used to improve the coating property to the conductive substrate. You may do it.
Liquid media compatible with water include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphoric acid esters , Ethers, nitriles and the like, and may be used as long as they are compatible with water.

  Furthermore, a thickener, a dispersant, a film forming aid, an antifoaming agent, a leveling agent, a preservative, a pH adjuster, and the like can be blended in the composite ink as necessary. In particular, since it may be difficult to obtain the viscosity and dispersion stability of the composite ink only with the aqueous resin fine particles, it is preferable to contain a thickener or a dispersant.

  The thickener or dispersant is preferably a water-soluble resin, and is not particularly limited. For example, acrylic resin, polyurethane resin, polyester resin, polyamide resin, polyimide resin, polyallylamine resin, phenol resin, Examples thereof include polymer compounds including polysaccharide resins such as epoxy resins, phenoxy resins, urea resins, melamine resins, alkyd resins, formaldehyde resins, silicon resins, fluorine resins, and carboxymethylcellulose. Moreover, if it is water-soluble, the modified substance, mixture, or copolymer of these resin may be sufficient. These can be used alone or in combination.

<Method of adjusting ink mixture for microbial fuel cell>
There is no restriction | limiting in particular in the preparation method of compound ink. In the preparation, each component may be dispersed at the same time, or after dispersing the conductive material and / or the oxygen reduction catalyst in the aqueous liquid medium, the aqueous resin fine particles may be added. The conductive material and / or the oxygen reduction used. It can be optimized by catalyst, aqueous resin fine particles, and aqueous liquid medium. However, when the aqueous catalyst paste composition is prepared first and the aqueous resin fine particles are added afterwards to prepare the composite ink, it can greatly contribute to cost reduction such as shortening of the dispersion time.

  For example, the conductive material and / or the oxygen reduction catalyst is 5 to 80 parts by mass, preferably 10 to 60 parts by mass, and the aqueous resin fine particles are 0.01 to 80 with respect to 100 parts by mass of the solid content of the composite ink of the present invention. Part by mass, preferably 0.02 to 60 parts by mass.

<Disperser / Mixer>
As an apparatus used for obtaining the microbial fuel cell composite ink, a disperser or a mixer that is usually used for pigment dispersion or the like can be used.

  For example, mixers such as dispersers, homomixers, or planetary mixers; homogenizers such as “Clearmix” manufactured by M Technique, or “fillmix” manufactured by PRIMIX; paint conditioner (manufactured by Red Devil), ball mill, sand mill (Shinmaru Enterprises "Dynomill", etc.), Attritor, Pearl Mill (Eirich "DCP Mill", etc.), or Coball Mill, etc .; Media type dispersers; Wet Jet Mill (Genus, "Genus PY", Sugino Media-less dispersers such as “Starburst” manufactured by Machine, “Nanomizer” manufactured by Nanomizer, etc., “Claire SS-5” manufactured by M Technique, or “MICROS” manufactured by Nara Machinery; or other roll mills, etc. Although The present invention is not limited to these. Moreover, as the disperser, it is preferable to use a disperser that has been subjected to a metal contamination prevention treatment from the disperser.

  For example, when using a media-type disperser, a disperser in which the agitator and vessel are made of a ceramic or resin disperser, or the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. Is preferably used. As the media, it is preferable to use glass beads, ceramic beads such as zirconia beads or alumina beads. Moreover, also when using a roll mill, it is preferable to use a ceramic roll. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination. Further, when the catalyst-carrying carbon material is easily cracked or crushed by a strong impact, a medialess disperser such as a roll mill or a homogenizer is preferable to the media disperser.

<Conductive substrate>
The conductive substrate used in the electrode of the present invention is excellent in corrosion resistance and electrical conductivity, has a large surface area, and is excellent in diffusion of reactants and products, and the material and shape are not particularly limited. For example, in addition to carbon materials such as graphite paper, graphite cloth and graphite felt, metal materials such as stainless steel mesh and platinum mesh can be used, but this is not restrictive. The conductive substrate used for the electrode may be subjected to a water repellent treatment in advance. For example, the cathode is impregnated with a dispersion of PTFE, dried, and heated at around 400 ° C. to develop water repellency. Further, a conductive material may be dispersed in the PTFE dispersion. The water repellent treatment is not limited to these.

<Electrode coating method>
The method for applying the composite ink of the present invention is not particularly limited, and a known method can be used. Examples include gravure coating method, spray coating method, screen printing method, dip coating method, die coating method, roll coating method, doctor coating method, knife coating method, screen printing method or electrostatic painting method, etc. As the drying method, standing drying, blow dryer, hot air dryer, infrared heater, far infrared heater, etc. can be used, but it is not particularly limited thereto.

<Configuration of electrode for microbial fuel cell>
The configuration of the electrode used in the present invention is not particularly limited. For example, the conductive substrate is subjected to a water repellent treatment as described above, and then the composite ink of the present invention is applied to one side to form a catalyst layer.

<Configuration of microbial fuel cell>
As described above, the microbial fuel cell is composed of a conductive support serving as an anode holding electron-donating microorganisms and a conductive support serving as a cathode coated with a fuel cell catalyst material as an organic waste water as an electrolyte. A one-chamber type configuration in which an electrolytic cell including the like is inserted without providing a partition, or a two-cell type configuration in which a solid polymer membrane is used and an anode cell and a cathode cell are separated using a solid polymer fuel cell. Good. Further, not only the electrolytic cell surrounded by the surface but also an environment not surrounded by paddy fields, lakes, rivers, and the sea may be used. For example, a cathode is installed on the liquid surface, side surface, and bottom surface that separates the inside of the electrolytic cell holding the electrolytic solution from the outside of the electrolytic cell such as the atmosphere containing oxygen, and a cassette-type electrode that can take in outside air in the liquid. A form such as soaking in the water is conceivable. At this time, the cathode catalyst layer is placed in contact with the electrolyte, and the back surface thereof is in contact with the atmosphere containing oxygen. Thereby, the atmosphere containing oxygen from the outside of the electrolytic cell directly flows into the cathode, and a reaction occurs on the catalyst in the cathode in contact with the electrolytic solution.

  The electrolyte used for the microbial fuel cell contains a substrate having proton conductivity and oxidatively decomposed by microorganisms. The substrate is not particularly limited as long as it is a substance that can be metabolized by microorganisms that donate electrons. For example, in addition to organic substances such as saccharides, proteins, and lipids, inorganic substances such as ammonia may be used, and one or more of them may be contained. Therefore, as the electrolytic solution, domestic wastewater, industrial wastewater, or the like that satisfies the above conditions can be used. In addition, a mediator responsible for electron transfer between the microorganism and the anode may be introduced, and examples thereof include methylene blue and neutral red.

  Microorganisms that donate electrons in the microbial fuel cell may be of a single type or a plurality of types as long as they cause an anodic reaction to oxidize and decompose the substrate to generate electrons. Microorganisms are retained in the electrolytic cell by floating in the electrolytic cell or being fixed on the anode. The microorganism species is not particularly limited, and examples include those belonging to the genus Shewanella and the genus Geobacter.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the examples and comparative examples, “part” represents “part by mass”.

<Preparation of aqueous resin fine particle dispersion>
[Synthesis Example 1]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 40 parts of ion-exchanged water and 0.2 part of Adeka Soap SR-10 (manufactured by ADEKA) as a surfactant. 48.5 parts of methyl methacrylate, 50 parts of butyl acrylate, 1 part of acrylic acid, 0.5 part of 3-methacryloxypropyltrimethoxysilane, 53 parts of ion-exchanged water, and ADEKA rear soap SR-10 (ADEKA Corporation as a surfactant) 1% of the pre-emulsion in which 1.8 parts were mixed in advance was further added. After raising the internal temperature to 70 ° C. and sufficiently substituting with nitrogen, 10% of 10 parts of a 5% aqueous solution of potassium persulfate was added to initiate polymerization. After maintaining the reaction system at 70 ° C. for 5 minutes, the remaining pre-emulsion and the remaining 5% aqueous solution of potassium persulfate were added dropwise over 3 hours while maintaining the internal temperature at 70 ° C., and stirring was further continued for 2 hours. . After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. 25% aqueous ammonia was added to adjust the pH to 8.5, and the solid content was adjusted to 40% with ion-exchanged water to obtain an aqueous resin fine particle dispersion. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Epoxy Group-Containing Compound]>
[Production Example 1]
Into a reaction vessel equipped with a stirrer, thermometer, dropping funnel and refluxing vessel, 20 parts of isopropyl alcohol and 20 parts of water were charged, and 40 parts of methyl methacrylate, 40 parts of methyl acrylate and 20 parts of glycidyl methacrylate were separately added to the dropping tank 1, Moreover, 2 parts of potassium persulfate was dissolved in 30 parts of isopropyl alcohol and 30 parts of water, and charged into the dropping tank 2. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropwise addition, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. and an epoxy having a solid content of 40%. A group-containing compound (methyl methacrylate / methyl acrylate / glycidyl methacrylate copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Amide Group-Containing Compound]>
[Production Example 2]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel was charged with 90 parts of water. Separately, 20 parts of acrylamide was dissolved in the dropping tank 1 and 2 parts of potassium persulfate was dissolved in 90 parts of water. The dropping tank 2 was charged. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the amide having a solid content of 40% was obtained. A group-containing compound (polyacrylamide) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

[Production Example 3]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel was charged with 40 parts of water. Separately, 40 parts of 2-ethylhexyl acrylate, 40 parts of styrene, and 20 parts of dimethylacrylamide were added to the dropping tank 1, and 2 parts of potassium sulfate was dissolved in 60 parts of water and charged into the dropping tank 2. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the amide having a solid content of 40% was obtained. A group-containing compound (2-ethylhexyl acrylate / styrene / dimethylacrylamide copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Hydroxyl-Containing Compound]>
[Production Example 4]
Into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel, 20 parts of isopropyl alcohol and 20 parts of water are charged, and 40 parts of methyl methacrylate, 40 parts of butyl acrylate, and 20 parts of 2-hydroxyethyl methacrylate are separately added dropwise. In the tank 1, 2 parts of potassium persulfate was dissolved in 30 parts of isopropyl alcohol and 30 parts of water and charged into the dropping tank 2. After raising the internal temperature to 80 ° C. and sufficiently substituting with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours and polymerized. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the hydroxyl group having a solid content of 40% A containing compound (methyl methacrylate / butyl acrylate / 2-hydroxyethyl methacrylate copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

[Synthesis Examples 2 to 16]
The composition shown in Table 1, Table 2, and Table 3 was synthesized in the same manner as in Synthesis Example 1 to obtain aqueous resin fine particle dispersions of Synthesis Examples 2 to 16. However, in Synthesis Examples 15 and 16, the resin aggregated during emulsion polymerization, and the desired resin fine particles could not be obtained.

<Base metal oxide catalyst>
[Production Example 5]
Oxyzirconium phthalocyanine (manufactured by Dainichi Seika Co., Ltd.) was heat treated in an electric furnace at 1000 ° C. for 10 hours in a mixed gas atmosphere of H ₂ / O ₂ / Ar (volume ratio 0.02 / 0.005 / 0.975). The obtained powder was pulverized in a mortar to obtain a base metal oxide catalyst.

<Carbon catalyst>
[Production Example 6]
Ketjen Black (manufactured by Lion) and iron phthalocyanine (manufactured by Sanyo Dye) are weighed at a mass ratio of 1 / 0.5, and dry-mixed with a particle composite device Mechanofusion (manufactured by Hosokawa Micron) to obtain a mixture. It was. The mixture was filled in an alumina crucible and heat-treated at 800 ° C. for 2 hours in a nitrogen atmosphere in an electric furnace to obtain a carbon catalyst.

<Preparation of composition for microbial fuel cell electrode formation>
[Example 1]
4.8 parts of TEC10E50E (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) as a platinum-supporting carbon material, 30.2 parts of water as an aqueous liquid medium, and 60 parts of a carboxymethyl cellulose aqueous solution (solid content 2%) as a thickener are mixed in a mixer. The mixture was further dispersed in a sand mill. Thereafter, 5 parts of the aqueous resin fine particle dispersion described in Synthesis Example 1 (solid content 40%) was added and mixed with a disper to obtain a mixture ink.

[Examples 2-49, Comparative Examples 1-12]
Using the conductive materials, oxygen reduction catalyst, aqueous resin fine particles, and aqueous liquid medium shown in Tables 4, 5, 6, and 7, composite inks were prepared in the same manner as in Example 1, and Examples 2 to 49 and Comparative Example were compared. The mixed inks of Examples 1 to 12 were obtained.

<Creation of electrode for microbial fuel cell>
Here, the water repellent treatment for the conductive substrate used for the electrode was performed by immersing the carbon cloth in a PTFE solution and drying it, followed by heat treatment at 380 ° C. The composite ink of Example 1 was applied to one side of the carbon cloth so that the catalyst amount was 0.5 mg / cm ^2, and then heated and dried at 110 ° C. for 30 minutes to produce a microbial fuel cell electrode.

  Using the mixed inks of Examples 2 to 49 and Comparative Examples 1 to 12 shown in Tables 4, 5, 6 and 7, microbial fuel cell electrodes were produced in the same manner as the microbial fuel cell electrodes, respectively. .

(Electrode adhesion)
Each of the electrodes produced as described above was cut into 6 grids in the vertical and horizontal directions at intervals of 2 mm using a knife from the electrode surface to the depth reaching the substrate. Adhesive tape was applied to the cut and immediately peeled off, and the degree of catalyst dropping was visually determined. The evaluation criteria are shown below. The results are shown in Tables 4-7.
○: “No peeling (practical level)”
○ △: “Slightly peeled (problem but usable level)”
Δ: “About half peel”
×: “Peeling at most parts”

  From the results of Tables 4, 5, 6 and 7, the composite ink containing the aqueous resin fine particles and the conductive material and / or the oxygen reduction catalyst is compared with the case where the dissolved resin is used when the electrode is produced. Adhesion improved.

<Microbial fuel cell>
The evaluation with the microbial fuel cell of the present invention was carried out in a single tank type configuration.

After anaerobically cultivating a mixture of Shewanella oneidenis MR-1 (single culture, 10 ⁵ cells / mL) and paddy soil in an electrolytic cell having a capacity of 30 mL at 30 ° C. for 3 days, A buffer solution of K ₂ HPO ₄ / KH ₂ PO ₄ (pH 7.0) is used as an electrolyte solution, and 2.0 g COD / L / day (COD: chemical oxygen demand) of domestic wastewater containing sodium acetate as a nutrient substrate Was allowed to flow continuously. Carbon felt was inserted into the electrolytic cell as a conductive support for the anode, and the electrodes of Examples 1 to 49 and Comparative Examples 1 to 12 were respectively installed on the side surfaces of the electrolytic cell as cathodes.

(Power generation test of microbial fuel cell)
Using a potentio galvanostat (VersaSTAT3, manufactured by Princeton Applied Research), current-voltage measurement was performed at room temperature for evaluation. As the power generation characteristics, the power generation characteristics of Examples 1 to 10, 41 and 42 and Comparative Examples 2 and 3 are the percentage (%) of the power generation amount per unit area in each electrode with respect to the power generation amount per electrode unit area of Comparative Example 1. Asked. Similarly, Examples 11 to 20, 43 and 44 and Comparative Examples 5 and 6 are Comparative Example 4, Examples 21 to 30, 45, 46 and 47 and Comparative Examples 8 and 9 are Comparative Example 7 and Examples 31 to 40. 48, 49 and Comparative Examples 11 and 12, the percentage (%) of the power generation amount per unit area in each electrode with respect to the power generation amount per electrode unit area of Comparative Example 10 was obtained.

  From the results shown in Tables 4, 5, 6 and 7, it can be seen that the power generation amount is increased by the combination of the aqueous resin fine particles and the oxygen reduction catalyst. This is presumably because the water-based resin fine particles are point-bonded to the catalyst, so that the reaction interface is larger than that of Comparative Example 1 and the power generation characteristics are improved. Furthermore, even when the amount of the aqueous resin fine particles was reduced, the power generation characteristics were improved while maintaining the adhesion. This is because the aqueous resin fine particles have high adhesiveness, so that even if the content is reduced, there is no problem in the adhesiveness, and it is considered that the power generation characteristics are improved by the amount of the resin that becomes resistance.

Claims (8)

A composition for forming a microbial fuel cell electrode, comprising a conductive material and / or an oxygen reduction catalyst and aqueous resin fine particles.
The composition for forming a microbial fuel cell electrode according to claim 1, wherein the aqueous resin fine particles contain an acrylic emulsion polymer.
The composition for forming a microbial fuel cell electrode according to claim 1 or 2, wherein the conductive material is a carbon material.
The composition for forming a microbial fuel cell electrode according to any one of claims 1 to 3, wherein the oxygen reduction catalyst is at least one selected from the group consisting of a noble metal catalyst, a base metal oxide catalyst, a carbon catalyst and activated carbon.
Furthermore, the composition for microbial fuel cell electrode formation in any one of Claims 1-4 containing an aqueous liquid medium.
A microbial fuel cell electrode comprising the microbial fuel cell electrode forming composition according to claim 1.
The electrode for a microbial fuel cell according to claim 6, wherein the microbial fuel cell electrode is disposed on one of a liquid surface, a liquid surface, a side surface, and a bottom surface of the microbial fuel cell, wherein one surface is in contact with air outside the tank and the back surface is in contact with the electrolyte.
A microbial fuel cell using the microbial fuel cell electrode according to claim 6 or 7.