JP5233256B2 - Electrolyte membrane-catalyst layer assembly with reinforcing sheet - Google Patents

Description

  The present invention relates to an electrolyte membrane-catalyst layer assembly with a reinforcing sheet.

  A fuel cell is a cell in which electrodes are arranged on both sides of an electrolyte and generates electricity by an electrochemical reaction between hydrogen and oxygen, and only water is generated during power generation. Thus, unlike conventional internal combustion engines, fuel cells are expected to become popular as next-generation clean energy systems because they do not generate environmental load gases such as carbon dioxide. In particular, the polymer electrolyte fuel cell has a low operating temperature and low electrolyte resistance. In addition, it uses a highly active catalyst, so it can achieve high output even with a small size. Is expected to be put to practical use.

  This polymer electrolyte fuel cell uses a solid polymer electrolyte membrane having proton conductivity, and a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of the electrolyte membrane. And it has the structure which has arrange | positioned the gasket so that the circumference | surroundings of the electrode which consists of this catalyst layer and a gas diffusion layer may be enclosed, and also this was pinched | interposed with the separator. Further, since the gasket is installed so as to surround the outer side of the electrode from the viewpoint of positional accuracy, a gap is formed between the gasket and the electrode, and the electrolyte membrane corresponding to this gap portion is an electrode. It is in a state where it is not pressed by either of the gaskets. Here, when power generation and non-power generation of the polymer electrolyte fuel cell are repeated, the electrolyte membrane repeats a wet state and a dry state, but the electrolyte membrane corresponding to the gap portion is pressed by an electrode or a gasket. Therefore, expansion and contraction are repeated. As a result, the electrolyte membrane is fatigued, and the electrolyte membrane is damaged when used for a long time.

  In order to solve this problem, for example, the polymer electrolyte fuel cell disclosed in Patent Document 1 further includes a reinforcing film in a gap between the electrode and the gasket. This reinforcing membrane is formed in a frame shape having an opening at the center as in the case of the gasket, and the outer peripheral edge of the reinforcing membrane is sandwiched between the gasket and the electrolyte membrane. The peripheral edge is sandwiched between the separator and the gas diffusion layer. As described above, the polymer electrolyte fuel cell of Patent Document 1 uses the reinforcing membrane to restrain the gap portion between the gasket and the electrode, thereby suppressing expansion and contraction of the electrolyte membrane. Yes.

However, the reinforcing membrane of Patent Document 1 is a membrane composed of a single layer of fluororesin or the like, and a gasket is directly disposed on the membrane. By adopting such a configuration, However, it is impossible to sufficiently relax the expansion and contraction of the electrolyte membrane. Therefore, when the battery is operated for a long time, the electrolyte membrane may not be sufficiently damaged, and further improvement is desired.
Japanese Patent No. 3052536 (FIG. 1)

  An object of the present invention is to provide an electrolyte membrane-catalyst layer assembly that can sufficiently suppress the expansion and contraction of the electrolyte membrane, prevent the electrolyte membrane from being damaged even when the battery is operated for a long time, and suppress the occurrence of gas leak. It is to be.

  As a result of intensive studies in view of the above problems, the inventors of the present invention have solved the above problems by using a reinforcing sheet using a specific layer structure and a specific material. It was found that can be obtained. The present invention has been completed based on such findings. That is, the present invention relates to the following electrolyte membrane-catalyst layer assembly with a reinforcing sheet.

Item 1. An electrolyte membrane-catalyst layer assembly comprising a solid polymer electrolyte membrane and a catalyst layer,
(1) A catalyst layer is laminated on each side except the outer peripheral edge of the solid polymer electrolyte membrane,
(2) A frame-shaped reinforcing sheet having an opening at the center is installed on the outer peripheral edges of both surfaces of the solid polymer electrolyte membrane,
(3) the reinforcing sheet, (i) a first polyolefin down resins layer, which is composed of a (ii) non-woven fabric,
(4) first polyolefin down resins layer constituting the reinforcing sheet is arranged to contact the solid polymer electrolyte membrane,
(5) The first polyolefin resin layer includes at least one selected from an olefin resin, an olefin copolymer, and a resin obtained by acid-modifying these.
An electrolyte membrane-catalyst layer assembly with a reinforcing sheet.

Item 2. Item 2. The electrolyte membrane-catalyst layer assembly according to Item 1, wherein the reinforcing sheet is disposed on the outer peripheral edge portions of both surfaces of the solid polymer electrolyte membrane and the outer peripheral edge portion of the catalyst layer.

Item 3. Item 3. The electrolyte membrane-catalyst layer assembly according to Item 1 or 2, wherein the non-woven fabric of (ii) is (1) natural fiber, or (2) a fiber made of a synthetic resin having a melting point of 200 ° C or higher.

Item 4. Inside, a part of the first polyolefin down resins layer is invaded, the electrolyte membrane according to any one of Items 1 to 3 of the nonwoven fabric of the (ii) - catalyst layer assembly.
Item 5. Item 5. The electrolyte membrane according to Item 4, wherein a part of the first polyolefin resin layer penetrates into the non-woven fabric of (ii), and the thickness of the penetrated first polyolefin resin layer is 5 to 30 μm. -Catalyst layer assembly.

Item 6 . Wherein (ii) non-woven on the addition of a second polyolefin down resins layer formed by forming electrolyte membrane according to any one of claim 1-5 - catalyst layer assembly.

Item 7 . Said second polyolefin down trees further gasket on the fat layer are arranged, the electrolyte membrane according to claim 6 - catalyst layer assembly.

Item 8 . Inside, a part of the second polyolefin down resins layer is invaded, the electrolyte membrane according to claim 6 or 7 of the nonwoven fabric of the (ii) - catalyst layer assembly.

1. Electrolyte membrane-catalyst layer assembly with reinforcing sheet The electrolyte membrane-catalyst layer assembly with reinforcing sheet of the present invention is an electrolyte membrane-catalyst layer assembly in which catalyst layers are laminated on both sides of a solid polymer electrolyte membrane. (1) A catalyst layer is laminated on each side of the solid polymer electrolyte membrane excluding the outer peripheral edge, and (2) an opening in the center on the outer peripheral edge on both sides of the solid polymer electrolyte membrane. (3) The reinforcing sheet is at least selected from the group consisting of (i) a first polyolefin-based resin layer, and (ii) a fibrous sheet and a porous sheet. (4) The first polyolefin resin layer constituting the reinforcing sheet is disposed so as to contact the solid polymer electrolyte membrane. Thus, by disposing a specific reinforcing sheet, it is possible to suppress damage to the electrolyte membrane-catalyst layer assembly, and to prevent gas leakage of fuel gas such as hydrogen.

  The electrolyte membrane-catalyst layer assembly of the present invention has, for example, as shown in FIG. 1, a double-sided surface (upper surface and upper surface and a solid polymer electrolyte membrane (hereinafter also simply referred to as “electrolyte membrane”)). A catalyst layer is laminated on the lower surface. Thus, since the catalyst layer is formed slightly smaller than the electrolyte membrane, the catalyst layer is not formed on the outer peripheral edge of the electrolyte membrane. The distance A from the outer peripheral edge of the electrolyte membrane to the outer peripheral edge of the catalyst layer is not particularly limited, but is preferably about 0 to 10 mm (particularly about 1 to 8 mm), for example.

  In the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention, a frame-shaped reinforcing sheet having an opening at the center is installed on the outer peripheral edge portions of both surfaces of the solid polymer electrolyte membrane. The reinforcing sheet is (i) the first polyolefin resin layer, and (ii) at least one sheet selected from the group consisting of a fibrous sheet and a porous sheet (hereinafter also referred to as “fibrous porous sheet”). The first polyolefin resin layer is disposed so as to be in contact with the electrolyte membrane. At this time, as shown in FIG. 2, the first polyolefin-based resin layer is disposed on the electrolyte membrane so as to cover the outer peripheral edge and side surfaces of the upper surface and the lower surface of the electrolyte membrane. A fibrous porous sheet is laminated on each of the upper surface and the lower surface of the first polyolefin resin layer. The fibrous porous sheet may be laminated on the entire surface of the first polyolefin resin layer, or may be laminated only partially, but in the present invention, the first polyolefin resin layer and the fibrous material are viewed in plan view. It is preferable that the porous sheet has substantially the same shape and size. The reinforcing sheet may be disposed on the outer peripheral edge of the electrolyte membrane, for example, not only on the outer peripheral edge of the electrolyte membrane but also on the outer peripheral edge of the catalyst layer formed on the electrolyte membrane. (FIG. 3). The distance B of the reinforcing sheet that protrudes from the electrolyte membrane is not particularly limited, but is preferably about 5 to 50 mm (particularly about 10 to 30 mm), for example. Further, the distance C of the reinforcing sheet laminated on the outer peripheral edge of the electrolyte membrane (and further on the outer peripheral edge of the catalyst layer) is not limited, but is, for example, about 1 to 30 mm (particularly about 3 to 20 mm). Preferably there is.

  A second polyolefin resin layer may be further laminated on the outer side of the reinforcing sheet of the present invention (that is, the surface of the fibrous porous sheet opposite to the first polyolefin resin layer). (2) A gasket may be disposed on the surface of the polyolefin resin layer (FIG. 4). Thereby, gas leak can be prevented more reliably. Also in this case, the reinforcing sheet and the gasket may be disposed not only on the outer peripheral edge portion of the electrolyte membrane but also on the outer peripheral edge portion of the catalyst layer formed on the electrolyte membrane ( FIG. 5).

  An electrolyte membrane-electrode assembly can be obtained by disposing known or commercially available gas diffusion layers on the catalyst layers on both sides of the electrolyte membrane-catalyst layer assembly of the present invention. Moreover, a polymer electrolyte fuel cell can be manufactured by arrange | positioning a well-known or commercially available separator on both surfaces of the said electrolyte membrane electrode assembly.

  Next, the material of each component of the electrolyte membrane-catalyst layer assembly configured as described above will be described.

(Solid polymer electrolyte membrane)
As the solid polymer electrolyte membrane, known or commercially available membranes can be used. For example, the polymer electrolyte membrane can also be produced by applying a solution containing a hydrogen ion conductive polymer electrolyte on a substrate and drying it. Can do. Examples of the hydrogen ion conductive polymer electrolyte include a perfluorosulfonic acid-based fluorine ion exchange resin, more specifically, a perfluorocarbonsulfonic acid-based resin in which the C—H bond of a hydrocarbon ion-exchange membrane is substituted with fluorine. Examples include polymers (PFS polymers). By introducing a fluorine atom having high electronegativity, it is chemically very stable, the dissociation degree of the sulfonic acid group is high, and high ion conductivity can be realized. Specific examples of such a hydrogen ion conductive polymer electrolyte include “Nafion” (registered trademark) manufactured by DuPont, “Flemion” (registered trademark) manufactured by Asahi Glass Co., Ltd., and “Aciplex” manufactured by Asahi Kasei Corporation. ”(Registered trademark),“ Gore Select ”(registered trademark) manufactured by Gore, and the like. The concentration of the hydrogen ion conductive polymer electrolyte contained in the hydrogen ion conductive polymer electrolyte-containing solution is usually about 5 to 60% by weight, preferably about 20 to 40% by weight. The thickness of the electrolyte membrane is usually about 20 to 250 μm, preferably about 20 to 80 μm.

(Catalyst layer)
The catalyst layer is a known or commercially available platinum-containing catalyst layer (cathode catalyst and anode catalyst). Specifically, the catalyst layer contains (1) carbon particles supporting catalyst particles and (2) a hydrogen ion conductive polymer electrolyte. Examples of the catalyst particles include platinum, a platinum alloy, a platinum compound, and the like. Examples of platinum alloys include alloys of platinum with at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron, and the like. In general, the catalyst particles contained in the cathode catalyst layer are platinum, and the catalyst particles contained in the anode catalyst layer are an alloy of the metal and platinum. Moreover, as a hydrogen ion conductive polymer electrolyte, the same material as what is used for the electrolyte membrane mentioned above can be used.

(Polyolefin resin layer)
Examples of the polyolefin resin constituting the polyolefin resin layer include olefin resins such as polyethylene (low density polyethylene, medium density polyethylene, high density polyethylene, etc.), polypropylene, polybutene, polyisobutylene, polybutadiene, and polyisoprene. Also, olefin resins such as ethylene-α / olefin copolymer, ethylene-propylene copolymer; ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene- Examples also include acrylic resins such as methacrylate ester copolymers; vinyl acetate resins such as ethylene-vinyl acetate copolymers. Other examples include ionomer resins. Furthermore, an acid-modified polyolefin resin obtained by modifying these resins may be used.

  Preferred examples of the acid-modified polyolefin resin include those obtained by graft-modifying the polyolefin resin with an unsaturated carboxylic acid. Specific examples include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-acrylic acid ester copolymer, and ethylene-methacrylic acid ester copolymer that are graft-modified with unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid used for the acid modification include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, citraconic acid, citraconic anhydride, itaconic acid, itaconic anhydride, and the like. The amount (modified amount) of the unsaturated carboxylic acid contained in the acid-modified polyolefin resin may be, for example, about 0.01 to 6% by weight. When this acid-modified polyolefin resin is used, if necessary, a butene component, an ethylene-propylene copolymer, an ethylene-propylene-butene copolymer, a propylene-α / olefin copolymer, an olefin elastomer Etc. may be mixed.

The density of the polyolefin resin is not limited, but is usually about 800 to 1000 kg / cm ³ , preferably about 850 to 950 kg / cm ³ . The density of the present invention is measured in accordance with ASTM D1505.

  The melting point of the polyolefin resin is appropriately determined depending on the temperature at the time of hot pressing or the like. For example, in the case of polyethylene (including acid-modified polyethylene), it is usually about 100 to 130 ° C, preferably about 110 to 125 ° C. In the case of polypropylene (including acid-modified polypropylene), it is usually about 135 to 170 ° C, preferably about 140 to 160 ° C. The melting point of the present invention is measured according to ASTM D2117.

  The MFR (melt flow rate) of the polyolefin resin is not limited, and is, for example, about 1 to 10 g / 10 minutes, preferably about 2 to 9.5 g / 10 minutes. The MFR of the present invention is measured according to ASTM D1238.

  The first polyolefin resin layer and the second polyolefin resin layer are made of the above-described polyolefin resin, and the polyolefin resins constituting the first polyolefin resin layer and the second polyolefin resin layer are the same. May be different.

(Fibrous sheet and porous sheet)
In the present invention, at least one sheet (fibrous porous sheet) selected from the group consisting of a fibrous sheet and a porous sheet is laminated on the upper surface and the lower surface of the first polyolefin resin layer. Thereby, flexibility can be given to the reinforcing sheet while maintaining rigidity.

  In this invention, the fibrous porous sheet laminated | stacked on the upper surface and lower surface of a 1st polyolefin resin layer may be the same, and may differ. For example, a fibrous sheet may be laminated on the upper surface, and a porous sheet may be laminated on the lower surface, or vice versa.

  The fibrous sheet may be composed of any one of organic fibers and inorganic fibers, for example.

  As the organic fiber, any of natural fiber and synthetic resin fiber can be used.

  Examples of natural fibers include cellulose, wool, silk, cotton, and hemp.

  As the synthetic resin constituting the synthetic resin fiber, for example, commercially available resins having a melting point of 200 ° C. or higher can be widely used. Specifically, polyester, polyamide, polyimide, polymethylpentene (230 to 240 ° C.), polyphenylene oxide (285-288 ° C.), synthetic resins such as polysulfone, polyether ether ketone (334 ° C.), polyphenylene sulfide (280 ° C.), and the like.

  In the present invention, polyester is particularly preferable, and wholly aromatic polyester is particularly preferable. Examples of such wholly aromatic polyesters include copolymers of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (Kuraray "Vectran", Kuraray "Veculus"), p-hydroxybenzoic acid. And a copolymer of terephthalic acid and 4,4′-dihydroxybisphenyl (“Sumika Super” manufactured by Sumitomo Chemical).

  Examples of the inorganic fiber include glass fiber, carbon fiber, rock fiber and the like.

  The fibrous sheet may be a woven fabric or a non-woven fabric. The fibrous sheet may be an unstretched sheet or may be a porous sheet stretched in a uniaxial or biaxial direction.

  In the present invention, a nonwoven fabric is preferred, and among these, a nonwoven fabric made of synthetic resin fibers is preferred, and a nonwoven fabric made of wholly aromatic polyester fibers is particularly preferred. Thereby, rigidity, flexibility, etc. can be improved further.

  The nonwoven fabric may be obtained by either a wet method or a dry method, but is preferably a dry method from the viewpoint of cost, solvent resistance and the like, and a melt blown method is particularly preferable among the dry methods.

The basis weight of the fibrous sheet is not limited, but may be, for example, about 5 to 25 g / m ² . The density of the fibrous sheet is not limited and is preferably about 0.15 to 0.45 g / cm ³ . By setting it as this range, flexibility etc. improve further.

  Examples of the material constituting the porous sheet include the same materials as the synthetic resin constituting the synthetic resin fiber. The porosity of the porous sheet may be, for example, about 10 to 80% by volume, preferably about 25 to 70% by volume.

  The porous sheet may be, for example, a needle punch method; an emboss roll method; a hot melt punch method; a physical punch method using a knife, a cutter, a rotary die roll or the like; a laser beam processing; a corona discharge; Can be manufactured.

(Reinforcement sheet)
For example, as shown in FIG. 6, the reinforcing sheet of the present invention has a frame shape having an opening in a plan view in the center, and a fibrous porous sheet on the upper and lower surfaces of the first polyolefin resin layer. Are laminated. The shape of the opening of the reinforcing sheet and the outer shape of the reinforcing sheet itself are not limited, and both may be rectangular as shown in FIG. 6 or may be circular.

  The thickness is not limited, but is usually about 20 to 150 μm, preferably about 30 to 100 μm.

  In the present invention, in the reinforcing sheet, the first polyolefin resin layer preferably penetrates into the fibrous porous sheet. Thereby, the adhesiveness of a 1st polyolefin resin layer and a fibrous porous sheet improves, and peeling of a fibrous porous sheet can be prevented at the time of battery operation. The thickness of the invading resin layer is not limited, but is preferably about 5 to 30 μm.

  Moreover, when the 2nd polyolefin-type resin layer is formed, it is preferable that a part of the said 2nd polyolefin-type resin layer also penetrate | invades in the inside of a reinforcement sheet. The thickness of the invading resin layer is not limited, but is preferably about 5 to 60 μm.

  The reinforcing sheet of the present invention can be produced by, for example, heat-melting and extruding a polyolefin resin onto the fibrous porous sheet using a T-die extruder or the like.

  The reinforcing sheet of the present invention is obtained by laminating the above-mentioned fibrous porous sheet on the upper surface and the lower surface of the above-mentioned first polyolefin resin layer. Therefore, since the reinforcing sheet of the present invention has flexibility while maintaining rigidity, when it is installed in the electrolyte membrane-catalyst layer assembly, the dimensional change of the electrolyte membrane-catalyst layer assembly (the electrolyte membrane during battery operation) (Expansion and contraction) can be suppressed. That is, when the electrolyte membrane expands, a force to compress the electrolyte membrane does not expand, and when the electrolyte membrane contracts, a force acts to relieve the contracting force, so that the shape of the electrolyte membrane is made as constant as possible. Thus, expansion and contraction of the electrolyte membrane can be suppressed. As a result, damage to the electrolyte membrane-catalyst layer assembly can be suppressed, and gas leakage of fuel gas such as hydrogen can be prevented.

(gasket)
In this invention, you may arrange | position a gasket further on the surface of the 2nd polyolefin resin layer of a reinforcement sheet as needed.

  As the gasket, it is possible to use a gasket that has a strength sufficient to withstand hot pressing and has a gas barrier property that does not leak fuel and oxidant to the outside. For example, a polyethylene terephthalate sheet, a Teflon (registered trademark) sheet, a silicon rubber sheet, a nitrile rubber sheet, an ethylene propylene rubber sheet, an acrylic rubber sheet and the like can be exemplified.

  The thickness of the gasket is preferably adjusted within a range of about ± 20 μm of the sum of the thickness of the catalyst layer and the thickness of the gas diffusion layer.

2. Manufacturing method of electrolyte membrane-catalyst layer assembly with reinforcing sheet The electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention has, for example, (1) a catalyst layer formed on both surfaces of a solid polymer electrolyte membrane, 2) Manufactured by placing two frame-shaped reinforcing sheets of the present invention having an opening in the center on the catalyst layer-forming electrolyte membrane so that the polyolefin resin layers face each other and hot pressing.

(1) Formation of catalyst layer In forming the catalyst layer on both sides of the solid polymer electrolyte membrane, for example, a catalyst layer forming transfer sheet is arranged so that the catalyst layer faces the electrolyte membrane, and the back side of the transfer sheet Then, a heat press is applied to transfer the catalyst layer to the electrolyte membrane, and the transfer substrate of the transfer sheet is peeled off. At this time, in consideration of workability, it is preferable to simultaneously laminate the catalyst layers on both surfaces of the electrolyte membrane, but the catalyst layers may be formed on each side.

  The pressure level of the heating press is usually about 0.5 to 20 MPa, preferably about 1 to 10 MPa in order to avoid transfer failure.

  It is preferable to heat the pressing surface during the pressing operation. The heating temperature is usually 200 ° C. or lower, preferably 150 ° C. or lower, in order to avoid damage or deformation of the electrolyte membrane. Thus, an electrolyte membrane-catalyst layer assembly is formed by forming catalyst layers on both surfaces of the electrolyte membrane. At this time, since the catalyst layer is slightly smaller than the electrolyte membrane, the outer peripheral edge of the electrolyte membrane is exposed.

  The transfer sheet for forming a catalyst layer is obtained by forming a transfer catalyst layer on a transfer substrate. The transfer sheet for forming a catalyst layer is formed, for example, by preparing a paste composition for forming a catalyst layer by mixing and dispersing the above-described carbon particles supporting the catalyst particles and a hydrogen ion conductive polymer electrolyte in a solvent. The catalyst layer-forming paste composition is produced by applying the catalyst layer-forming paste composition onto a transfer substrate via a release layer as necessary, so that the catalyst layer has a desired film thickness. At this time, the catalyst layer forming paste composition may be applied to the transfer substrate so that the catalyst layer has a shape slightly smaller than the electrolyte membrane.

  When applying the paste composition for forming a catalyst layer, the method is not particularly limited. For example, knife coater, bar coater, blade coater, spray, dip coater, spin coater, roll coater, die coater, curtain General methods such as coater and screen printing can be applied.

  The solvent is not limited, and known or commercially available solvents can be widely used. In the present invention, in particular, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, ethylene glycol are used. Monovalent or polyhydric alcohols having about 1 to 4 carbon atoms such as propylene glycol are preferred. These solvents can be used alone or in combination of two or more.

  After applying the paste composition for forming a catalyst layer, the catalyst layer is formed on the transfer substrate by drying at a predetermined temperature and time. The drying temperature is usually about 40 to 100 ° C, preferably about 60 to 80 ° C. The drying time varies depending on the drying temperature and cannot be generally specified, but is usually about 5 minutes to 2 hours, preferably about 10 minutes to 1 hour.

  As a transfer substrate, for example, polyimide, polyethylene terephthalate, polyparvanic acid aramid, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyarylate, polyethylene naphthalate, etc. A polymer film can be mentioned. Further, heat resistance of ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), etc. Fluorine resin can also be used. In addition to the polymer film, the transfer substrate may be coated paper such as art paper, coated paper or lightweight coated paper, or non-coated paper such as notebook paper or copy paper. In the present invention, an inexpensive and easily available polymer film is preferable, and polyethylene terephthalate or the like is more preferable. The thickness of the transfer substrate is usually about 6 to 100 μm, preferably about 10 to 30 μm, from the viewpoints of handleability and economy.

(2) Attaching the reinforcing sheet Next, the catalyst layer is formed on the electrolyte membrane-catalyst layer assembly, for example, so that the first polyolefin-based resin layer faces two frame-like reinforcing sheets provided with openings. The reinforcing sheet is attached by placing on the electrolyte membrane and hot pressing.

  More specifically, a frame-shaped reinforcing sheet having openings on the upper surface and the lower surface of the electrolyte membrane-catalyst layer assembly is disposed. At this time, the reinforcing sheets are arranged so that the first polyolefin resin layers of the reinforcing sheets face each other. Next, the reinforcing sheets are respectively disposed on the outer peripheral edge of the electrolyte membrane so that the catalyst layer is exposed from the opening of the reinforcing sheet except for the outer peripheral edge, and then heated and pressed. At this time, the reinforcing sheet may be disposed not only on the outer peripheral edge of the electrolyte membrane but also on the outer peripheral edge of the catalyst layer.

  At this time, by performing the heat press, the polyolefin resin layers of the two reinforcing sheets are heat-fused to substantially form one first polyolefin resin layer.

  The heating temperature is not limited as long as it is carried out at a temperature at which the polyolefin resin layer melts, but is usually about 60 to 160 ° C, preferably about 80 to 130 ° C. The pressure level is usually about 0.05 to 5 MPa, preferably about 0.1 to 1 MPa.

  In addition, you may provide a gasket on a reinforcement sheet as needed. When this gasket is provided, the reinforcing sheet is a reinforcing sheet in which a first polyolefin resin layer is laminated on one side of a fibrous porous sheet and a second polyolefin resin layer is provided on the other side (first polyolefin type). Resin layer / fibrous porous sheet / second polyolefin resin layer) and a gasket may be hot-pressed on the second polyolefin resin layer. The conditions for the hot press may be the same as those used when the first polyolefin resin layer is provided.

  By providing a known or commercially available gas diffusion layer on both surfaces of the electrolyte membrane-catalyst layer assembly of the present invention, an electrolyte membrane-electrode assembly (MEA) can be obtained, and further known for the electrolyte membrane-electrode assembly. Alternatively, a polymer electrolyte fuel cell can be obtained by providing a commercially available separator.

  According to the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention, breakage of the electrolyte membrane-catalyst layer assembly can be sufficiently suppressed. Therefore, even when the battery is operated for a long time, a gas leak of fuel gas such as hydrogen can be prevented, and the durability time of the fuel cell can be improved.

  The present invention will be described more specifically with reference to the following examples and comparative examples. In addition, this invention is not limited to the following Example.

Example 1
As the electrolyte membrane, NRE212CS (manufactured by Dupont) having a thickness of 50 μm cut to a size of 75 × 75 mm was used.

Next, a transfer sheet for forming a catalyst layer was prepared as follows. First, 2 g of platinum catalyst-supported carbon (platinum supported amount: 45.7 wt%, manufactured by Tanaka Kikinzoku Co., Ltd., “TEC10E50E”), 1-butanol 10 g, 3-butanol 10 g, fluororesin (5 wt% Nafion Binder, manufactured by DuPont) 20 g and 6 g of water were added, and these were stirred and mixed with a disperser to prepare a paste composition for forming a catalyst layer. Next, the prepared paste composition was applied to a polyester film (Toray, “X44”, thickness 25 μm) so that the platinum weight after drying the catalyst layer was 0.4 mg / cm ² , dried, A transfer sheet for forming a catalyst layer was prepared.

  The transfer sheet for forming a catalyst layer produced as described above was cut into a size of 60 × 60 mm, and placed on both sides of the electrolyte membrane so that the catalyst layer faced the electrolyte membrane side. And it heat-pressed on conditions of 135 degreeC, 5.0 Mpa, and 150 second, the catalyst layer was formed on both surfaces of the electrolyte membrane, and the electrolyte membrane-catalyst layer assembly was produced. The catalyst layer had a thickness of 20 μm.

Subsequently, a reinforcing sheet was produced. The reinforcing sheet is a non-woven fabric made of wholly aromatic polyester fibers (weighing 14 g / cm ² , thickness 50 μm, density 0.21 g / cm ³ ; made by Kuraray, “Vecruz MBBK14F”) on one side, acid-modified polypropylene (“Admer QE840”). “Mitsui Chemicals, Inc., density 895 kg / cm ³ (measuring method ASTM D1505), melting point 140 ° C. (measuring method ASTM D2117), MFR 9.2 g / 10 min (measuring method ASTM D1238)) with a T-die extruder, 44 μm. The reinforcing sheet of Example 1 having a total thickness of 70 μm was obtained by extrusion coating to a thickness.

  This reinforcing sheet was cut into a size of 110 × 110 mm, and an opening with a size of 50 × 50 mm was formed at the center. Then, the two reinforcing sheets are arranged centering on both surfaces of the electrolyte membrane-catalyst layer assembly so that each polyolefin resin layer (maleic acid-modified polypropylene layer) faces the electrolyte membrane-catalyst layer assembly, An electrolyte membrane-catalyst layer assembly with a reinforcing sheet is obtained by thermally fusing the first polyolefin layer of the reinforcing sheet to the electrolyte membrane-catalyst layer assembly by hot pressing at 100 ° C., 1.0 MPa for 30 seconds. Was made.

(Example 2)
An electrolyte membrane-catalyst layer assembly was produced in the same manner as in Example 1 using the same material as in Example 1. Next, a reinforcing sheet was produced. The reinforcing sheet is a non-woven fabric made of wholly aromatic polyester fibers (weighing 14 g / cm ² , thickness 50 μm, density 0.21 g / cm ³ , manufactured by Kuraray, “Vecruz MBBK14F”) on one surface with acid-modified polypropylene (“Admer QE840”). "Mitsui Chemicals, Inc., density 895 kg / cm ³ (measuring method ASTM D1505), melting point 140 ° C. (measuring method ASTM D2117), MFR 9.2 g / 10 min (measuring method ASTM D1238)) with a T-die extruder. Of the non-woven fabric is extruded and coated with a T-die extruder to a thickness of 44 μm, and the total thickness is 100 μm. Reinforcing sheet (first polyolefin resin layer (maleic acid-modified polypropylene layer) / fibrous porous sheet Was acquired / second polyolefin resin layer (maleic acid-modified polypropylene layer)). In addition, the 1st polyolefin resin layer and the 2nd polyolefin resin layer penetrate | invaded the inside of the fibrous porous sheet in the thickness direction, respectively.

  Next, a reinforcing sheet (first polyolefin resin) of Example 2 was formed by placing an ethylene propylene rubber gasket (NOP, “EPDM”, thickness 200 μm) on the second polyolefin resin layer. Layer / fibrous porous sheet / second polyolefin resin layer / gasket).

  An electrolyte membrane-catalyst layer assembly (with gasket) with a reinforcing sheet was produced in the same manner as in Example 1 except that two reinforcing sheets of Example 2 were used.

(Comparative Example 1)
A 100 mm square polypropylene sheet (Torayfan BO, manufactured by Toray Industries, Inc., 40 μm thick) was used, and an opening having a size of 50 × 50 mm was formed at the center. An electrolyte membrane-catalyst layer assembly with a reinforcing sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that two polypropylene sheets were used as reinforcing sheets.

(Evaluation method)
Regarding the electrolyte membrane-catalyst layer assembly with reinforcing sheet of Example 1, Example 2 and Comparative Example 1, an electrolyte membrane-electrode junction was obtained by laminating a gas diffusion layer (carbon paper) on each catalyst layer surface by hot pressing. A body (MEA) was produced, and a separator was installed on the MEA to produce a polymer electrolyte fuel cell, and a load fluctuation cycle test was conducted. The measurement conditions at this time were a cell temperature of 80 ° C., a fuel utilization rate of 70%, an oxidant utilization rate of 40%, and a humidification temperature of 50 ° C. The load variation condition was performed by scanning 0.01 A / cm ² and 0.3 A / cm ² at intervals of 1 minute.

As a result of the current voltage measurement evaluation, the durability time of the fuel cells of Example 1 and Example 2 was 1000 hours, and the durability time of the fuel cells of Comparative Example 1 was 300 hours. As a result of electrical measurement of the hydrogen gas leak amount, the fuel cell of Example 1 was 1 mA / cm ² , which was substantially equivalent to the initial performance, but the fuel cell of Comparative Example 1 was 15 mA / cm ² or more, This is considered to be caused by hydrogen leakage due to deterioration of the electrolyte membrane. After the evaluation, the fuel cell was disassembled. As a result, in Example 1 and Example 2, the electrolyte membrane was not damaged. On the other hand, in Comparative Example 1, breakage of the electrolyte membrane was visually observed.

  Thus, in the polymer electrolyte fuel cells of Example 1 and Example 2, since the durability time is increased, the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention causes damage to the electrolyte membrane. You can see that the problem has been solved.

FIG. 1 shows an example of a perspective view (a) and a sectional view (b) of an electrolyte membrane-catalyst layer assembly used in the present invention. FIG. 2 shows an example of a sectional view of the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention. FIG. 3 shows an example of a cross-sectional view of the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention. FIG. 4 shows an example of a cross-sectional view of the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention. FIG. 5 shows an example of a sectional view of the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention. FIG. 6 shows an example of a plan view of a reinforcing sheet used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Catalyst layer 3 ... 1st polyolefin resin layer 4 ... Fibrous porous sheet 5 ... Reinforcement sheet 6 ... 2nd polyolefin resin layer 7 ... Gasket 8 ... Opening

Claims (8)

An electrolyte membrane-catalyst layer assembly comprising a solid polymer electrolyte membrane and a catalyst layer,
(1) A catalyst layer is laminated on each side except the outer peripheral edge of the solid polymer electrolyte membrane,
(2) A frame-shaped reinforcing sheet having an opening at the center is installed on the outer peripheral edges of both surfaces of the solid polymer electrolyte membrane,
(3) the reinforcing sheet, (i) a first polyolefin down resins layer, which is composed of a (ii) non-woven fabric,
(4) first polyolefin down resins layer constituting the reinforcing sheet is arranged to contact the solid polymer electrolyte membrane,
(5) The first polyolefin resin layer includes at least one selected from an olefin resin, an olefin copolymer, and a resin obtained by acid-modifying these.
An electrolyte membrane-catalyst layer assembly with a reinforcing sheet. The electrolyte membrane-catalyst layer assembly according to claim 1, wherein the reinforcing sheet is installed on the outer peripheral edge portions of both surfaces of the solid polymer electrolyte membrane and on the outer peripheral edge portion of the catalyst layer. The electrolyte membrane-catalyst layer assembly according to claim 1 or 2, wherein the nonwoven fabric of (ii) is (1) natural fiber, or (2) a fiber made of a synthetic resin having a melting point of 200 ° C or higher. The inside of the nonwoven fabric (ii), part of the first polyolefin down resins layer is invaded, the electrolyte membrane according to claim 1 - catalyst layer assembly. 5. The electrolyte according to claim 4, wherein a part of the first polyolefin resin layer penetrates into the nonwoven fabric of (ii), and the thickness of the penetrated first polyolefin resin layer is 5 to 30 μm. Membrane-catalyst layer assembly. Wherein (ii) non-woven on the addition of a second polyolefin down resins layer formed by forming electrolyte membrane according to any one of claims 1 to 5 - catalyst layer assembly. Catalyst layer assembly - made are further arranged a gasket in said second polyolefin down resins layer, the electrolyte membrane according to claim 6. Inside, a part of the second polyolefin down resins layer is invaded, the electrolyte membrane according to claim 6 or 7 of the nonwoven fabric of the (ii) - catalyst layer assembly.

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