JP2008140774A - Method for manufacturing aromatic hydrocarbon-based electrolyte membrane with seal material and aromatic hydrocarbon-based membrane electrode composite with seal material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing aromatic hydrocarbon-based electrolyte membrane with seal material and aromatic hydrocarbon-based membrane electrode composite with seal material, in which high sealability, safety, and durability are provided and cost can be reduced by simplifying manufacturing processes. <P>SOLUTION: The method for manufacturing aromatic hydrocarbon-based electrolyte membrane with seal material includes the steps of: (1) boring a hole through the aromatic hydrocarbon-based electrolyte membrane; (2) setting the aromatic hydrocarbon-based electrolyte membrane in a mold used for forming the seal material; (3) pouring the seal material into the mold where the aromatic hydrocarbon-based electrolyte membrane is set; (4) heating the seal material at a temperature of 140°C or higher; (5) releasing the aromatic hydrocarbon-based electrolyte membrane with the seal material from the mold; and (6) acidizing the aromatic hydrocarbon-based electrolyte membrane with the seal material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aromatic hydrocarbon electrolyte membrane with a sealing material and a method for producing an aromatic hydrocarbon membrane electrode assembly with a sealing material for a fuel cell, particularly a polymer electrolyte fuel cell.

  A fuel cell is a power generation device with low emissions, high energy efficiency, and low burden on the environment. For this reason, it is in the spotlight again in recent years to the protection of the global environment. Compared to conventional large-scale power generation facilities, this is a power generation device expected in the future as a relatively small-scale distributed power generation facility, and as a power generation device for mobile objects such as automobiles and ships. It is also attracting attention as a power source for small mobile devices and portable devices, as an alternative to secondary batteries such as nickel metal hydride batteries and lithium ion batteries, as a charger for secondary batteries, or in combination with secondary batteries. (Hybrid) is expected to be installed in mobile devices such as mobile phones and personal computers.

  In a polymer electrolyte fuel cell (hereinafter sometimes referred to as PEFC), in addition to the conventional PEFC using hydrogen gas as a fuel, a direct fuel cell that directly supplies fuel such as methanol is also available. Attention has been paid. The direct fuel cell has a lower output than the conventional PEFC, but the fuel is liquid and does not use a reformer, so the energy density is high and the usage time of the portable device per filling is long. There is an advantage.

  In PEFC, an anode electrode and a cathode electrode in which a reaction responsible for power generation occurs, and a polymer electrolyte membrane serving as a proton conductor between the anode and the cathode are a membrane electrode composite (hereinafter sometimes referred to as MEA). A cell in which this MEA is sandwiched between separators is configured as a unit. Here, the electrode is composed of an electrode base material (also referred to as a gas diffusion electrode or a current collector) that promotes gas diffusion and collects (supply) electricity, and a catalyst layer that actually becomes an electrochemical reaction field. Yes. For example, in the anode electrode of PEFC, a fuel such as hydrogen gas reacts in the catalyst layer of the anode electrode to generate protons and electrons, and the electrons are conducted to the electrode substrate, and the protons are conducted to the polymer electrolyte membrane. For this reason, the anode electrode is required to have good gas diffusivity, electron conductivity, and proton conductivity. On the other hand, in the cathode electrode, an oxidizing gas such as oxygen or air is reacted with protons conducted from the polymer electrolyte membrane and electrons conducted from the electrode base material in the catalyst layer of the cathode electrode to produce water. For this reason, in the cathode electrode, it is effective to efficiently discharge the generated water in addition to gas diffusibility, electron conductivity, and proton conductivity.

  Among PEFCs, a direct fuel cell using methanol or the like as a fuel requires performance different from that of a conventional PEFC using hydrogen gas as a fuel. That is, in a direct type fuel cell, a fuel such as a methanol aqueous solution reacts with the catalyst layer of the anode electrode to produce protons, electrons, and carbon dioxide at the anode electrode, and the electrons are conducted to the electrode substrate, and the protons are polymer electrolyte. The carbon dioxide passes through the electrode substrate and is released out of the system. For this reason, in addition to the required characteristics of the anode electrode of the conventional PEFC, fuel permeability such as aqueous methanol solution and carbon dioxide emission are also required. Further, in the cathode electrode of the direct type fuel cell, in addition to the reaction similar to that of the conventional PEFC, fuel such as methanol that has permeated through the electrolyte membrane and oxidizing gas such as oxygen or air are mixed with carbon dioxide in the catalyst layer of the cathode electrode. Reactions that produce water also occur. For this reason, since produced water becomes more than conventional PEFC, it is preferable to discharge water more efficiently.

  In order to spread such fuel cells in earnest, it is necessary to reduce the manufacturing cost as well as improve the performance and infrastructure, but it is also important to improve the reliability of the fuel cell. In particular, the sealing performance of fuel is one of the factors that greatly affect performance, reliability, and life, and is a technology that cannot be ignored as a fuel cell system. If a fuel leak occurs, there is a risk of not only deterioration in performance but also adverse effects on the human body and the environment, fire and explosion.

Conventionally, as described in Patent Documents 1 to 8 and the like, fuel cell sealing methods have been proposed for the purpose of simplifying the manufacturing process, improving sealing performance, and preventing damage to the electrolyte membrane. According to Patent Documents 1, 2, and 4, a seal material that surrounds the electrode in a frame shape or a gasket (seal material) made of a rubber-like elastic body is used, and a fluororesin sheet or film is disposed between the seal material and the electrolyte membrane. Thus, a seal structure has been proposed. Patent Document 3 proposes a method in which an electrolyte membrane and a packing (seal material) are previously bonded with an adhesive and integrated. Patent Documents 5 and 6 propose a method in which a gasket (seal material) is joined to a gas diffusion layer to form an integrated product. In Patent Documents 7 and 8, the electrolyte membrane and the rubber material are integrated, and then a manufacturing method for performing non-heat vulcanization, and a sealing material is molded using a mold that is devised so that the electrolyte membrane does not become high temperature. A method to compensate for the lack of heat resistance in the water has been proposed.
Japanese Patent Laid-Open No. 5-21077 JP 2003-68319 A JP-A-8-148169 Japanese Patent Laid-Open No. 2005-11661 International Publication No. 02/043172 Pamphlet International Publication No. 02/0889240 Pamphlet International Publication No. 04/052614 Pamphlet International Publication No. 02/061869 Pamphlet

  However, in Patent Documents 1 and 2, it is necessary to insert a film or the like between the sealing material and the electrolyte membrane, which increases the number of manufacturing processes and is a problem in terms of cost. In Patent Document 3, the durability of the adhesive is insufficient, and a portion that cannot follow the deformation of the electrolyte membrane in a long-term test is generated, which easily causes fuel leakage. In Patent Documents 5 and 6, etc., it is necessary to impregnate the gas diffusion layer with rubber or the like, and in addition to the cost problem due to the increase in the manufacturing process, in Patent Document 6, the separator is also provided with a sealing material in order to bring the electrode into contact with the separator. It is necessary to provide grooves having the same shape, which increases the cost of the fuel cell system. In Patent Documents 7 and 8, the sealing material is formed at a low temperature and vulcanized with radiation or the like. However, the crosslinking is insufficient and there is a problem in long-term durability, and the initial equipment investment is large and the cost is increased. This is a device for compensating for the heat resistance and insufficient rigidity of the system electrolyte membrane.

  In view of the background art, the present invention provides an aromatic hydrocarbon electrolyte membrane with a sealing material and an aromatic hydrocarbon with a sealing material that are excellent in sealing performance, durability, and safety, and that can reduce costs by simplifying the manufacturing process. It is an object of the present invention to provide a method for producing a membrane electrode assembly.

The present invention for achieving the above object is a method for producing an aromatic hydrocarbon electrolyte membrane with a sealing material having the following steps.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid-treating aromatic hydrocarbon-based electrolyte membrane with sealing material Also, aromatic hydrocarbon-based membrane electrode assembly with sealing material provided with a pair of electrodes so as to sandwich the electrolyte membrane inside the sealing material In this manufacturing method, the distance between the sealing material and the electrode is 2 mm or less, or the end of the electrode overlaps the sealing material, and the manufacturing method of the aromatic hydrocarbon membrane electrode composite with the sealing material has the following steps It is characterized by.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid treatment of aromatic hydrocarbon electrolyte membrane with sealing material (7) Step of setting anode electrode and cathode electrode inside sealing material of aromatic hydrocarbon electrolyte membrane with sealing material (8) Heat pressing process

  According to the present invention, an aromatic hydrocarbon electrolyte membrane with a sealing material and an aromatic hydrocarbon membrane electrode with a sealing material, which are excellent in sealing performance, durability, and safety, and can be reduced in cost by simplifying the production process A method for producing a composite can be provided, which can contribute to the spread of fuel cells.

  Hereinafter, preferred embodiments of the present invention will be described.

The present invention is a method for producing an aromatic hydrocarbon electrolyte membrane with a sealing material, comprising the following steps.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid-treating aromatic hydrocarbon electrolyte membrane with sealing material The present invention also provides an aromatic hydrocarbon membrane with sealing material in which a pair of electrodes are provided so as to sandwich the electrolyte membrane inside the sealing material. In the method for producing an electrode composite, the gap between the seal material and the electrode is 2 mm or less, or the end of the electrode overlaps the seal material, and the method for producing an aromatic hydrocarbon membrane electrode composite with a seal material having the following steps It is.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid treatment of aromatic hydrocarbon electrolyte membrane with sealing material (7) Step of setting anode electrode and cathode electrode inside sealing material of aromatic hydrocarbon electrolyte membrane with sealing material (8) Step of heating and pressing First, the aromatic hydrocarbon electrolyte membrane in the present invention is a polymer material having a unit in which an ionic group is introduced into an aromatic ring, which is formed into a film shape. Not alkylene It may be bonded via a group or the like. The film thickness is preferably in the range of 1 μm to 300 μm, and preferably 5 μm to 60 μm from the balance of ionic conductivity and mechanical strength.

  The aromatic hydrocarbon electrolyte membrane in the present invention may contain materials other than the aromatic hydrocarbon polymer material for the purpose of improving various characteristics. Is preferably 70% by weight or more from the viewpoint of heat resistance and mechanical strength in the production process of the present invention. 80% by weight or more is more preferable, and 90% by weight or more is more preferable.

As such an ionic group, an atomic group having a negative charge is preferable, and one having proton exchange ability is preferable. Examples of such a functional group, a sulfonic acid group _(-SO 2 (OH)), a sulfuric acid group (-OSO ₂ (OH)), a sulfonimide group _{(-SO 2} NHSO 2 R (R represents an organic group.) ), A phosphonic acid group (—PO (OH) ₂ ), a phosphoric acid group (—OPO (OH) ₂ ), a carboxylic acid group (—CO (OH) 2), and salts thereof can be preferably employed. Two or more kinds of these ionic groups can be contained in the polymer material, and may be preferable by combining them. The combination is appropriately determined depending on the structure of the polymer. Among them, it is more preferable to have at least one of a sulfonic acid group, a sulfonimide group, and a sulfuric acid group from the viewpoint of high proton conductivity, and most preferable to have at least a sulfonic acid group from the viewpoint of hydrolysis resistance. In the case of having a sulfonic acid group, the density of the sulfonic acid group is preferably 0.1 to 5.0 mmol / g, more preferably 0.5 to 3.5 mmol / g, still more preferably from the viewpoint of proton conductivity and water resistance. Is 1.0 to 3.5 mmol / g. By setting the sulfonic acid group density to 0.1 mmol / g or more, a high-power fuel cell can be obtained, and by setting it to 5.0 mmol / g or less, for example, a liquid fuel such as a direct methanol fuel cell can be obtained. When used in a fuel cell that is in direct contact, it is possible to prevent the electrolyte membrane from being excessively swollen by the fuel and eluting or flowing out.

  Here, the sulfonic acid group density is the molar amount of the sulfonic acid group introduced per unit dry weight of the polymer material, and the larger the value, the higher the degree of sulfonation. The sulfonic acid group density of the polymer material to be used can be measured by elemental analysis, neutralization titration, nuclear magnetic resonance spectroscopy or the like. Elemental analysis is preferable from the viewpoint of ease of measurement of sulfonic acid group density and accuracy, and analysis is usually performed by this method. However, the neutralization titration method is used when it is difficult to accurately calculate the sulfonic acid group density by the elemental analysis method such as when a sulfur source is included in addition to the sulfonic acid group. Furthermore, when it is difficult to determine the sulfonic acid group density by these methods, it is possible to use a nuclear magnetic resonance spectrum method.

  Specific examples of the aromatic hydrocarbon-based electrolyte membrane include polyphenylene oxide, polyether ketone, polyether ether ketone, polyether sulfone, polyether ether sulfone, poly ether from the viewpoint of mechanical strength, fuel durability, heat resistance, and the like. Examples include ether phosphine oxide, polyether ether phosphine oxide, polyphenylene sulfide, polyamide, polyimide, polyetherimide, polyimidazole, polyoxazole, and polyphenylene. It can be a mixture of two or more tumors.

  In particular, from the viewpoint of heat resistance and mechanical strength, the aromatic hydrocarbon is preferably polyether ketone, polyether sulfone, or polyimide.

  Moreover, an ionic group is introduced into a part of these polymers to form an electrolyte membrane. As for the method of introducing an ionic group into these polymer materials, an ionic group may be introduced into the polymer, or a monomer having an ionic group may be polymerized. Introduction of a phosphonic acid group into a polymer can be performed, for example, by a method described in “Polymer Preprints Japan”, 51, 750 (2002). Introduction of a phosphate group into the polymer is possible by, for example, phosphate esterification of a polymer having a hydroxyl group. Introduction of a carboxylic acid group into the polymer is possible by, for example, oxidizing a polymer having an alkyl group or a hydroxyalkyl group. Introduction of a sulfonimide group into the polymer is possible, for example, by treating a polymer having a sulfonic acid group with an alkylsulfonamide. The introduction of sulfate groups into the polymer is possible, for example, by sulfate esterification of a polymer having hydroxyl groups. The introduction of the sulfonic acid group into the polymer can be performed, for example, by a method in which the polymer is reacted with chlorosulfonic acid, concentrated sulfuric acid, or fuming sulfuric acid. These ionic group introduction methods can be controlled to a desired ionic group density by appropriately selecting conditions such as treatment time, concentration, and temperature.

  In addition, as a method for polymerizing a monomer having an ionic group, for example, a method described in “Polymer Preprints”, 41 (1) (2000) 237. When a polymer is obtained by this method, the degree of introduction of ionic groups can be easily controlled by the charging ratio of monomers having ionic acid groups.

  When the aromatic hydrocarbon electrolyte membrane used has a non-crosslinked structure, the weight average molecular weight is preferably 10,000 to 5,000,000, more preferably 30,000 to 1,000,000. By setting the weight average molecular weight to 10,000 or more, it is possible to obtain mechanical strength that can be practically used. The weight average molecular weight can be measured by GPC method.

In particular, as the ionic group, an aromatic hydrocarbon electrolyte membrane having a sulfonic acid group as described above is most preferable. However, as an example of using a polymer material having a sulfonic acid group, a —SO ₃ M group (M is There is a method in which a polymer containing a metal) is formed from a solution state, then heat-treated at a high temperature to remove the solvent, and after providing a sealing material, proton substitution is performed to obtain an aromatic hydrocarbon electrolyte membrane with a sealing material. The metal M may be any salt as long as it can form a salt with sulfonic acid, but Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W, and the like are preferable. Among these, Li, Na, K, Ca, Sr, and Ba are more preferable, and Li, Na, and K are more preferable. Film formation in the state of these metal salts enables heat treatment at a high temperature, and this method is suitable for a polymer material system that can obtain a high glass transition point and a low water absorption rate.

  Further, there is no particular problem even if it is combined with a polymer material not containing an ionic group, fine particles, fibers, a porous base material, etc., and it may be preferable from heat resistance and water resistance.

  Next, the manufacturing process of the present invention will be described.

  The step of opening the through hole in the aromatic hydrocarbon electrolyte membrane is necessary to integrate the sealing material with the aromatic hydrocarbon electrolyte membrane without using an adhesive or the like. The through holes can be integrated by being filled with a sealing material and connected to the front and back of the electrolyte membrane. This through hole is preferably provided so as to surround a portion where the sealing material is applied to the aromatic hydrocarbon electrolyte membrane, that is, a portion to be sealed, but the interval, diameter and shape thereof are the sealing material used, molding temperature, and sealing portion. It can be determined experimentally as appropriate depending on the size of. As a means for opening the through hole, a conventionally known method can be used, and a punching punch, a Thomson blade, a cutting plotter, or the like can be used.

  Next, it is a step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material. The aromatic hydrocarbon electrolyte is used by using a mold for molding a sealing material having a recess having a predetermined sealing material shape. It is preferable to set so that the through-hole part opened in the film | membrane overlaps a recessed part. The shape of the recess is not particularly limited and can be determined according to the purpose. The upper and lower mold recesses are set so as to cover the through-holes opened in the aromatic hydrocarbon electrolyte membrane, so that the sealing material that has flowed into the recesses is formed on the front and back surfaces of the electrolyte membrane as protrusions having an arbitrary shape. If the sealing material is connected to the front and back through a penetrating work so as to surround the portion to be sealed, the sealing material can be secured for a long time without slipping or peeling unless the electrolyte is broken. Moreover, it is preferable to carry out in this state in the state which heated the type | mold for sealing material formation to 100 degreeC or more. By heating, the time mentioned above 140 degreeC required in a post process is shortened, and productivity improves. The temperature is preferably 140 ° C. or higher, and more preferably preheated to the same temperature as the maximum temperature in the subsequent process.

  The step of pouring the sealing material into the mold for molding the sealing material in which the aromatic hydrocarbon electrolyte membrane is set refers to the step of pouring the sealing material into the sealing material molding die having the groove described above by an arbitrary method. There are usually known methods. For example, a preferable example is a method of pushing out from a discharge port by a piston method by the pressure described in the above-mentioned Patent Document WO-052614.

  Although it does not specifically limit as a sealing material, The following things of a diene type or a non-diene type can be used. Specifically, natural rubber, isoprene rubber; synthetic natural rubber, butadiene rubber, chloroprene rubber, rubber-like copolymer of isobutene and isoprene; butyl rubber, rubber-like copolymer of styrene and butadiene, ethylene and propylene Rubbery copolymer, rubbery copolymer of ethylene, propylene and diene, rubbery copolymer of acrylonitrile and butadiene; added with nitrile rubber, chlorosulfonated polyethylene, ethyl acrylate or other acrylates Rubbery copolymer with a small amount of monomer enabling sulfurization; acrylic rubber, polychloromethyloxirane; epichlorohydrin rubber, rubbery copolymer of ethylene oxide and epichlorohydrin, fluoro and perfluoroalkyl Or a rubbery copolymer having a perfluoroalkoxy group in the side chain Rubber copolymer of tetrafluoroethylene and propylene, silicone rubber with methyl and vinyl substituents in the polymer chain, silicone rubber with methyl, vinyl and fluoro substituents in the polymer chain, polyester urethane , Polyether urethanes, rubbery copolymers of ethyl acrylate or other acrylic esters with ethylene, rubbery copolymers of ethyl acrylate or other acrylic esters with acrylonitrile, hydrogenated acrylonitrile and Rubber-like copolymer of butadiene, rubber-like copolymer of carboxylated acrylonitrile and butadiene, norbornene rubber, rubber-like copolymer of acrylonitrile, butadiene and isoprene, brominated isobutene and isoprene Rubbery copolymer; brominated butyl rubber, chlorinated Rubbery copolymer of isobutene and isoprene; chlorinated butyl rubber, rubbery copolymer of epichlorohydrin and allyl glycidyl ether, rubbery copolymer of ethylene oxide, epichlorohydrin and allyl glycidyl ether , Silicone rubber with methyl substituent in the polymer chain; Polydimethylsiloxane, Silicone rubber with methyl and phenyl substituents in the polymer chain, Silicone rubber with methyl and vinyl substituents and phenyl substituents in the polymer chain Etc.

  These rubbers can be appropriately selected depending on the fuel to be used and use conditions, and may be used in a mixture of two or more kinds or in a laminate of two or more layers. Preferred examples of the balance between cost, sealability and fuel resistance include rubbery copolymers of ethylene, propylene and diene (EPDM) and rubbery copolymers of ethylene tetrafluoride and propylene.

  In the present invention, the sealing material poured into the mold for molding the sealing material needs to be heated at 140 ° C. or higher. As a result, a reaction such as crosslinking of the sealing material is promoted, and mechanical strength, water resistance, and durability are imparted. It is preferably 150 ° C. or higher, more preferably 160 ° C. or higher in terms of reliably performing crosslinking, and the crosslinking time can be shortened, which is also preferable from the viewpoint of productivity. The term “crosslinking” as used herein means a state in which there is substantially no fluidity to heat or a state insoluble in a solvent. The determination of crosslinking in the present invention is performed based on whether or not it is substantially insoluble in a solvent, and can be specifically determined by the following method. For example, a polymer electrolyte material (about 0.1 g) serving as a specimen is washed with pure water and then vacuum-dried at 40 ° C. for 24 hours to measure the weight. The polymer electrolyte material is immersed in a 100-fold weight solvent and heated in a sealed container at 70 ° C. for 40 hours with stirring. Next, filtration is performed using filter paper (No. 2) manufactured by Advantech. During filtration, the filter paper and the residue are washed with the same solvent of 100 times weight, and the eluate is sufficiently eluted in the solvent. Dry the filtrate and determine the weight of the elution. When the elution weight is less than 10% of the initial weight, it is determined to be substantially insoluble in the solvent. This test is performed on two types of solvents, water and methanol, and when it is determined that all the solvents are substantially insoluble, it is determined that the polymer electrolyte material has a crosslinked structure.

  In addition, it is preferable from the viewpoint of productivity that the entire mold for sealing material is heated without being released from the mold for molding the seal material, but after the mold is released from the mold for molding the seal material, heating for crosslinking is performed. Alternatively, in addition to heating, irradiation with radiation, ultraviolet rays, electron beams, or the like may be performed.

  The heating time at 140 ° C. or higher is not particularly limited, but is preferably within 30 minutes, preferably within 15 minutes from the viewpoint of productivity and prevention of thermal deterioration of the electrolyte membrane. Heating for 30 minutes or more may cause thermal deterioration of the electrolyte membrane.

  In addition, perfluoro electrolyte membranes that are not aromatic hydrocarbon electrolyte membranes cannot be subjected to a process that deteriorates or deforms in this heating process and is set in a preheated sealing material mold. It is.

  Next, it is a step of releasing the aromatic hydrocarbon electrolyte membrane with the sealing material from the mold for forming the sealing material, but the method of releasing from the mold is not particularly limited, and generally known methods can be used. At this time, if the sealing material is in close contact with the mold and is difficult to release, use compressed air or water, or apply a release agent or attach a release film to the part that the sealing material touches in advance You may take

  The sealing material molding die may remain in the heated state or after cooling, but from the viewpoint of productivity, the sealing material molding die is preferably in a heated state.

  Next, the process of acid-treating the aromatic hydrocarbon electrolyte membrane with a sealing material will be described.

  Specifically, this is a step of bringing an aromatic hydrocarbon electrolyte membrane with a sealing material into contact with hydrochloric acid, sulfuric acid, nitric acid, acetic acid or the like. As the contact method, a generally known method can be adopted, and the aromatic hydrocarbon electrolyte membrane with a sealing material may be immersed in an acid solution, or the acid solution may be sprayed onto the aromatic hydrocarbon electrolyte membrane with a sealing material. Good. This step is effective for, for example, proton exchange when a sealing material is applied with an alkali metal salt of a sulfonic acid group, and for removing impurities adhering to and eluting from a mold for molding a sealing material or a sealing material. The treatment temperature, acid concentration, treatment time, treatment method, and the like here can be appropriately determined experimentally, and may be heated or an organic solvent such as alcohols may be added for the purpose of promoting acid treatment. .

  Moreover, it is preferable to wash with water or the like so that no acid remains after the acid treatment, and the pH of the cleaning liquid is preferably up to 6 or more from the viewpoint of acid corrosion in the next step.

  A sealing material for an aromatic hydrocarbon electrolyte membrane with a sealing material of the present invention is formed on a frame, and a pair of electrodes are joined so as to sandwich the electrolyte membrane inside the membrane electrode composite with a sealing material can be produced. .

  Next, the aromatic hydrocarbon membrane electrode composite with a sheet of the present invention will be described.

  A known method can be used to form the electrode, but the distance between the sealing material and the electrode of the aromatic hydrocarbon electrolyte membrane with the sealing material is 2 mm or less. The term “2 mm or less” includes a state in which the end of the electrode overlaps the sealing material. If the distance between the sealing material and the electrode is 2 mm or less, even if the electrolyte membrane swells with fuel, the electrolyte membrane is hardly broken by deformation and durability is improved. The thickness is preferably 1 mm or less, more preferably 0 mm. At 0 mm, the electrolyte membrane portion is not directly exposed to the fuel, so that the durability is further improved. If it is difficult to make the thickness 0 mm in the manufacturing process, the end of the electrode may overlap the sealing material. In this case, the shape of the sealing material is preferably designed so that the portion where the electrodes overlap is thinner than the other portions.

  The electrode may be formed by stacking the gas diffusion electrode substrate after the catalyst layer is provided on the aromatic hydrocarbon electrolyte membrane with the sealing material by catalyst transfer sheet or direct coating, or gas diffusion with the catalyst layer provided. The electrode base material may be directly attached to the aromatic hydrocarbon electrolyte membrane with a sealing material. Further, an adhesive layer for reducing the interface resistance during power generation may be provided between the catalyst layer and the aromatic hydrocarbon electrolyte membrane with a sealing material.

  Such an electrode comprises a catalyst layer and an electrode substrate. The catalyst layer here is a layer containing a catalyst for promoting an electrode reaction, an electron conductor, an ion conductor, and the like. As the catalyst contained in the catalyst layer, for example, a noble metal catalyst such as platinum, palladium, ruthenium, rhodium, iridium, gold is preferably used. One of these may be used alone, or two or more of them, such as alloys and mixtures, may be used in combination.

  Moreover, when using an electronic conductor (conductive material) for a catalyst layer, a carbon material and an inorganic conductive material are preferably used from the point of electronic conductivity or chemical stability. Among these, amorphous and crystalline carbon materials are mentioned. For example, carbon black such as channel black, thermal black, furnace black, and acetylene black is preferably used because of its electron conductivity and specific surface area. Furnace Black includes Vulcan (registered trademark) XC-72R, Vulcan (registered trademark) P, Black Pearls (registered trademark) 880, Black Pearls (registered trademark) 1100, Black Pearls (registered trademark) 1300, Black Pearls manufactured by Cabot Corporation. (Registered Trademark) 2000, Regal (Registered Trademark) 400, Ketjen Black International (trademark) EC, EC600JD, Mitsubishi Chemical Corporation # 3150, # 3250, and the like are listed. Examples include Denka Black (registered trademark) manufactured by Chemical Industries. In addition to carbon black, artificial graphite or carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin, and furan resin can also be used. As the form of these carbon materials, in addition to irregular particles, fibers, scales, tubes, cones, and megaphones can also be used. Moreover, you may use what post-processed these carbon materials.

  Moreover, when using an electronic conductor, it is preferable from the point of electrode performance that it is disperse | distributing uniformly with a catalyst particle. For this reason, it is preferable that the catalyst particles and the electron conductor are well dispersed in advance as a coating liquid. Furthermore, it is also a preferred embodiment to use catalyst-supporting carbon or the like in which the catalyst and the electron conductor are integrated as the catalyst layer. By using this catalyst-supporting carbon, the utilization efficiency of the catalyst is improved, which can contribute to the improvement of battery performance and cost reduction. Here, even when catalyst-supported carbon is used for the catalyst layer, a conductive agent can be added to further increase the electron conductivity. As such a conductive agent, the above-described carbon black is preferably used.

  As the substance having ion conductivity (ion conductor) used in the catalyst layer, various organic and inorganic materials are generally known. However, when used in a fuel cell, sulfone which improves ion conductivity. A polymer having an ionic group such as an acid group, a carboxylic acid group, or a phosphoric acid group (ion conductive polymer) is preferably used. Among these, from the viewpoint of the stability of the ionic group, a polymer having ion conductivity composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, or the polymer electrolyte material of the present invention is preferably used. As the perfluoro-based ion conductive polymer, for example, Nafion (registered trademark) manufactured by DuPont, Aciplex (registered trademark) manufactured by Asahi Kasei Corporation, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., and the like are preferably used. These ion conductive polymers are provided in the catalyst layer in a solution or dispersion state. At this time, the solvent for dissolving or dispersing the polymer is not particularly limited, but a polar solvent is preferable from the viewpoint of the solubility of the ion conductive polymer. Moreover, the hydrocarbon-based polymer material preferable as the electrolyte membrane described above can also be suitably used as a substance (ion conductor) having ion conductivity in the catalyst layer. In particular, in the case of a fuel cell using methanol aqueous solution or methanol as a fuel, the above-described hydrocarbon polymer material may be effective in durability from the viewpoint of methanol resistance.

  Since the catalyst and the electronic conductors are usually powders, the ionic conductor usually plays a role of solidifying them. It is preferable from the viewpoint of electrode performance that the ionic conductor is added in advance to a coating liquid containing catalyst particles and an electronic conductor as main constituents when the catalyst layer is prepared, and is applied in a uniformly dispersed state. is there. The amount of the ionic conductor contained in the catalyst layer should be appropriately determined according to the required electrode characteristics and the conductivity of the ionic conductor used, and is not particularly limited, but the weight ratio The range of 1 to 80% is preferable, and the range of 5 to 50% is more preferable. When the ion conductor is too small, the ion conductivity is low, and when it is too much, the gas permeability may be hindered.

  Such a catalyst layer may contain various substances in addition to the catalyst, the electron conductor, and the ionic conductor. In particular, in order to improve the binding property of the substance contained in the catalyst layer, a polymer other than the above-described ion conductive polymer may be included. Examples of such a polymer include fluorine atoms such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyhexafluoropropylene (FEP), polytetrafluoroethylene, and polyperfluoroalkyl vinyl ether (PFA). These copolymers, copolymers of monomer units constituting these polymers and other monomers such as ethylene and styrene, or blend polymers can be used. The content of these polymers in the catalyst layer is preferably in the range of 5 to 40% by weight. When there is too much polymer content, there exists a tendency for an electronic and ionic resistance to increase and for electrode performance to fall.

  In addition, when the fuel is a liquid or gas, the catalyst layer preferably has a structure in which the liquid or gas easily permeates, and preferably has a structure that promotes the discharge of by-products due to the electrode reaction.

  Moreover, as an electrode base material, an electrical resistance is low and what can collect or supply electric power can be used. Further, when the catalyst layer is used also as a current collector, it is not necessary to use an electrode substrate. Examples of the constituent material of the electrode base material include carbonaceous and conductive inorganic substances. For example, a fired body from polyacrylonitrile, a fired body from pitch, a carbon material such as graphite and expanded graphite, stainless steel, molybdenum And titanium. These forms are not particularly limited, and are used, for example, in the form of fibers or particles. From the viewpoint of fuel permeability, fibrous conductive materials (conductive fibers) such as carbon fibers are preferable. As an electrode base material using conductive fibers, either a woven fabric or a non-woven fabric structure can be used. For example, carbon paper TGP series, SO series manufactured by Toray Industries, Inc., carbon cloth manufactured by E-TEK, etc. are used. Examples of the woven fabric include plain weave, oblique weaving, satin weaving, crest weaving, binding weaving, and the like. Moreover, as a nonwoven fabric, it does not specifically limit, such as a paper making method, a needle punch method, a spun bond method, a water jet punch method, and a melt blow method. It may also be a knitted fabric. In these fabrics, especially when carbon fibers are used, a plain fabric using flame-resistant spun yarn is carbonized or graphitized woven fabric, and the flame-resistant yarn is carbonized after being processed into a nonwoven fabric by the needle punch method or water jet punch method. Alternatively, a graphitized nonwoven fabric, a flameproof yarn, a carbonized yarn, or a mat nonwoven fabric by a paper making method using a graphitized yarn is preferably used. In particular, it is preferable to use a nonwoven fabric or cloth from the viewpoint of obtaining a thin and strong fabric.

  Examples of the carbon fiber used for the electrode substrate include polyacrylonitrile (PAN) carbon fiber, phenolic carbon fiber, pitch carbon fiber, and rayon carbon fiber.

  In addition, the electrode base material has a water repellent treatment for preventing gas diffusion / permeability deterioration due to water retention, a partial water repellent treatment for forming a water discharge path, a hydrophilic treatment, and a resistance reduction. For example, carbon powder can be added. Further, a conductive intermediate layer containing at least an inorganic conductive substance and a hydrophobic polymer can be provided between the electrode substrate and the catalyst layer. In particular, when the electrode base material is a carbon fiber woven fabric or a nonwoven fabric having a large porosity, by providing the conductive intermediate layer, it is possible to suppress performance degradation due to the catalyst layer soaking into the electrode base material.

  The aromatic hydrocarbon membrane electrode assembly with a sealing material of the present invention is sandwiched between a separator and a current collector provided with a fuel flow path and a fuel intake port, and these are fixed by tightening with screws or caulking. A battery can be produced. The fuel flows to the electrode portion, but the fuel is sealed by a sealing material integrated with the electrolyte membrane.

  Applications of the fuel cell using the aromatic hydrocarbon electrolyte membrane with a sealing material of the present invention and the aromatic hydrocarbon membrane electrode composite with a sealing material of the present invention include cell phones, personal computers, PDAs, video cameras (camcorders). ), Portable devices such as digital cameras, handy terminals, RFID readers, digital audio players, various displays, home appliances such as electric shavers and vacuum cleaners, electric tools, household power supply machines, cars such as passenger cars, buses and trucks, It is preferably used as a power supply source for motorcycles, bicycles with electric assist, electric carts, electric wheelchairs, moving bodies such as ships and railways, and various robots. Especially in portable devices, it is used not only for power supply sources, but also for charging secondary batteries installed in portable devices, and also suitable as a hybrid power supply source used in combination with secondary batteries, capacitors, and solar cells. Available to:

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these examples are for understanding this invention better, and this invention is not limited to these.

  The physical properties in the examples were measured by the following methods.

(1) Density of sulfonic acid group After stirring and washing in pure water at 25 ° C. for 24 hours or more, vacuum drying was performed at 100 ° C. for 24 hours, and then the purified and dried polymer was measured by elemental analysis. Analysis of C, H, and N was performed by a fully automatic elemental analyzer varioEL, analysis of S was performed by flask combustion method / barium acetate titration, and analysis of P was performed by flask combustion method / phosphovanadomolybdic acid colorimetric method. . The sulfonic acid group density per unit gram (mmol / g) was calculated from the composition ratio of each polymer.

(2) Weight average molecular weight The weight average molecular weight of the polymer was measured by GPC. Using Tosoh HLC-8022GPC as an integrated device of ultraviolet detector and differential refractometer, and two Tosoh TSK gel SuperHM-H (inner diameter 6.0 mm, length 15 cm) as GPC columns, N-methyl-2 -Measured with a pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10 mmol / L of lithium bromide) at a flow rate of 0.2 mL / min, and the weight average molecular weight was determined in terms of standard polystyrene.

(3) Film thickness It measured using Mitutoyo ID-C112 type | mold set to Mitutoyo granite comparator stand BSG-20.

Example 1
As an aromatic hydrocarbon electrolyte membrane, a membrane made of a sulfonated polyetherketone K salt (equivalent to a sulfonic acid group density of 1.5 mmol / g, a weight average molecular weight of 200,000, a film thickness of 30 μm) was prepared. The through-hole 2 was opened in the electrolyte membrane 1 as described above.

  Next, description will be made with reference to an image cross-sectional view (FIG. 2) in which an aromatic hydrocarbon electrolyte membrane having through holes is set in a mold for forming a sealing material. The pair of lower mold 4 for sealing material molding and upper mold 5 for molding the sealing material preheated to 160 ° C. was sandwiched so that the through-hole 2 opened in the electrolyte membrane 1 was on the sealing material forming groove 3. The upper mold for molding the sealing material is provided with a recessed portion for storing the sealing material raw material 7, and the recessed portion and the groove for forming the sealing material are connected by the sealing material raw material supply port 8.

  Next, after putting uncrosslinked EPDM as a sealing material into the recess and fluidizing it, a mold 6 that can press the recess portion into a piston shape and holding the raw material of the sealing material is set and put into a press machine. The EPDM was crosslinked by holding at a pressure of 50 MPa for 5 minutes.

  Next, the mold for molding the sealing material was taken out from the press machine, and the aromatic hydrocarbon electrolyte membrane with the mold sealing material for molding the sealing material was taken out.

  Next, the aromatic hydrocarbon electrolyte membrane with the sealing material was immersed in 1N hydrochloric acid at 25 ° C. for 12 hours for proton exchange, and then washed with water until the washing solution became neutral.

  Next, two carbon fiber cloth base materials were subjected to a water repellent treatment with a 20% ethylene tetrafluoride solution, and then a carbon black dispersion containing 20% ethylene tetrafluoride was applied and baked to form an electrode. A substrate was prepared.

  On one electrode substrate, an anode electrode catalyst coating solution composed of Pt—Ru-supported carbon and “Nafion (registered trademark)” solution was applied and dried to prepare an anode electrode.

  On the other electrode substrate, a cathode electrode catalyst coating solution composed of Pt-supported carbon and a “Nafion (registered trademark)” solution was applied and dried to prepare a cathode electrode.

  An aromatic hydrocarbon membrane with a sealant is prepared by setting an anode electrode and a cathode electrode inside the sealant of an aromatic hydrocarbon electrolyte membrane with a sealant obtained above and heating and pressing at 100 ° C. and 3 MPa for 5 minutes. An electrode composite was prepared. The distance between the sealing material and the electrode at this time was set to 0 mm.

  When a membrane electrode assembly is sandwiched between separators, 1M methanol aqueous solution is supplied to the anode side at a rate of 1 ml / min, and fuel is supplied to the cathode side by natural aspiration, no fuel leakage is observed, and fuel leakage occurs after 6 months. It did not occur and showed good sealing properties.

Example 2
The aromatic hydrocarbon electrolyte membrane of Example 1 was changed to a membrane made of Na salt of sulfonated polyethersulfone (sulfonic acid group density equivalent to 1.0 mmol / g, weight average molecular weight 200,000, film thickness 30 μm) and cutting. An aromatic hydrocarbon electrolyte membrane with a sealant was obtained in the same manner except that the through hole was opened with a plotter. An anode electrode and a cathode electrode are set inside the sealing material of the obtained aromatic hydrocarbon electrolyte membrane with a sealing material, and heated and pressed at 100 ° C. and 3 MPa for 5 minutes to provide an aromatic hydrocarbon membrane electrode composite with a sealing material. The body was made. The distance between the sealing material and the electrode at this time was set to 2.0 mm.

  When a membrane electrode assembly is sandwiched between separators, 1M methanol aqueous solution is supplied to the anode side at a rate of 1 ml / min, and fuel is supplied to the cathode side by natural aspiration, no fuel leakage is observed, and fuel leakage occurs after 6 months. It did not occur and showed good sealing properties.

Example 3
The aromatic hydrocarbon electrolyte membrane of Example 1 was prepared by using a sulfonated polyether ketone K salt (equivalent to a sulfonic acid group density of 1.5 mmol / g, a weight average molecular weight of 200,000) polyimide ("Toray Nice # 3000" manufactured by Toray). Was dissolved in N-methyl-2-pyrrolidone so that the weight ratio of the solid content was 90:10, and was uniformly blended to form a film thickness of 30 μm, followed by heat treatment at 300 ° C. for 10 minutes. The procedure is the same as in Example 1 except that the change is made. An aromatic hydrocarbon electrolyte membrane with a sealing material was obtained. An anode electrode and a cathode electrode are set inside the sealing material of the obtained aromatic hydrocarbon electrolyte membrane with a sealing material, and heated and pressed at 100 ° C. and 3 MPa for 5 minutes to provide an aromatic hydrocarbon membrane electrode composite with a sealing material. The body was made. The distance between the sealing material and the electrode at this time was set to 0.1 mm.

  When the membrane electrode assembly is sandwiched between separators, 1M methanol aqueous solution is supplied to the anode side at a rate of 1 ml / min, and fuel is supplied to the cathode side by natural aspiration, no fuel leakage is observed, and fuel leakage occurs after 6 months. It did not occur and showed good sealing properties.

Example 4
The aromatic hydrocarbon electrolyte membrane with a sealing material obtained in Example 1 was used without acid treatment, and a gas diffusion electrode LT120EN (Pt5 g / m ² ) manufactured by BASF was used as an electrode for both electrodes. Set the electrode cut so that the end 0.2mm overlaps with the sealing material on the aromatic hydrocarbon electrolyte membrane with the sealing material, and heat-press at 15 ° C, 5MPa for 5 minutes, then the aromatic hydrocarbon membrane with the sealing material An electrode composite was prepared. Next, the membrane electrode assembly with the sealant was immersed in 1 M sulfuric acid at 50 ° C. for 2 hours, and the aromatic hydrocarbon electrolyte membrane portion was proton-exchanged, and then washed with water until the washing solution became neutral.

This aromatic hydrocarbon membrane electrode composite with a sealing material is sandwiched between separators, cell temperature 80 ° C., hydrogen with a relative humidity of 70% on the anode side, and air with a relative humidity of 60% on the cathode side. The fuel was supplied so that the anode was 70% and the cathode was 40%.
Hydrogen leakage did not occur for 4 months, and the output retention rate at 0.5 A / cm ² was 95%.

Comparative Example 1
When the aromatic hydrocarbon electrolyte membrane of Example 1 was changed to “Nafion (registered trademark) 117” manufactured by DuPont and performed in the same manner as in Example 1, a pair of molds for molding a sealing material preheated to 160 ° C. When trying to set “Nafion (registered trademark) 117”, the deformation due to heat could not be set greatly.

  The process for producing an aromatic hydrocarbon-based electrolyte membrane with a sealing material and an aromatic hydrocarbon-based membrane electrode assembly with a sealing material according to the present invention includes various electrochemical devices (for example, fuel cells, water electrolysis devices, chloroalkali electrolysis devices). It can be applied to the manufacture of electrolyte membranes used in various storage batteries.

  Although it does not specifically limit as a use of the fuel cell which uses the aromatic hydrocarbon type electrolyte membrane with a sealing material of this invention and the aromatic hydrocarbon type membrane electrode composite with a sealing material, A mobile phone, a personal computer, PDA, a video camera , Digital cameras, portable TVs, digital audio players, hard disk players and other portable devices, cordless vacuum cleaners and other home appliances, toys, electric bicycles, electric wheelchairs, motorcycles, automobiles, buses, trucks and other vehicles and ships, railways, etc. It is preferably used as an alternative to conventional primary batteries and secondary batteries, such as a mobile power source for robots, robots and cyborgs, and stationary generators, or as a hybrid power source with these or solar cells, or for charging.

Image of aromatic hydrocarbon electrolyte membrane with through holes Cross-sectional image of an aromatic hydrocarbon electrolyte membrane with through holes set in a mold for sealing material molding

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Electrolyte membrane 2: Through-hole 3: Sealing material formation groove | channel 4: Lower mold | type for sealing material shaping | molding 5: Upper mold | type for sealing material shaping | molding 6: Mold | die 7 which suppresses sealing material raw material 7: Sealing material raw material 8: Sealing material Raw material supply port

Claims (3)

The manufacturing method of the aromatic hydrocarbon type electrolyte membrane with a sealing material characterized by performing the following process in this order.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid-treating aromatic hydrocarbon electrolyte membrane with sealing material   The method for producing an aromatic hydrocarbon electrolyte membrane with a sealing material according to claim 1, wherein the aromatic hydrocarbon electrolyte membrane contains any one of polyether ketone, polyether sulfone, and polyimide. In the method for producing an aromatic hydrocarbon membrane electrode composite with a sealing material in which a pair of electrodes are provided so as to sandwich an electrolyte membrane inside the sealing material, the distance between the sealing material and the electrode is 2 mm or less, and the following steps are performed. A process for producing an aromatic hydrocarbon-based membrane electrode composite with a sealing material, which is performed in order.
(1) A step of opening a through hole in an aromatic hydrocarbon electrolyte membrane (2) A step of setting an aromatic hydrocarbon electrolyte membrane in a mold for molding a sealing material (3) An aromatic hydrocarbon electrolyte membrane as a sealing material (4) The step of heating the sealing material at 140 ° C. or higher (5) The aromatic hydrocarbon electrolyte membrane with the sealing material is released from the mold for molding the sealing material. Step (6) Step of acid treatment of aromatic hydrocarbon electrolyte membrane with sealing material (7) Step of setting anode electrode and cathode electrode inside sealing material of aromatic hydrocarbon electrolyte membrane with sealing material (8) Heat pressing process

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