JP2008277288A - Composite polymer electrolyte membrane manufacturing apparatus, composite polymer electrolyte membrane manufacturing method, functional membrane, and fuel cell - Google Patents

Abstract

In manufacturing a composite polymer electrolyte membrane by impregnating a porous membrane with an electrolyte resin, impregnation unevenness is suppressed, the surface uniformity of the electrolyte membrane is improved, and the quality of the composite polymer membrane is improved. The purpose is to make the manufacturing apparatus and the working environment compact and to efficiently impregnate the electrolyte resin without protruding. Another object of the present invention is to improve the power generation performance of the fuel cell provided with the composite polymer membrane.
Means for feeding a porous membrane as a reinforcing membrane, and means for feeding a polymer electrolyte single membrane having proton conductivity or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis Means for heating the porous membrane and the polymer electrolyte single membrane, or the porous membrane and a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, and the polymer electrolyte single membrane or proton by hydrolysis. An apparatus for producing a composite polymer electrolyte membrane, comprising means for pressurizing and impregnating the porous membrane with a conductive polymer electrolyte precursor single membrane.
[Selection] Figure 2

Description

  The present invention relates to an apparatus for producing a composite polymer electrolyte membrane optimal for a solid polymer electrolyte used in various functional membranes, particularly solid polymer fuel cells, water electrolysis devices, etc., and a method for producing a composite polymer electrolyte membrane, The present invention relates to a fuel cell using a composite polymer electrolyte membrane. In particular, the present invention relates to a manufacturing apparatus for efficiently producing a composite polymer electrolyte membrane excellent in durability without damage due to repeated changes in operating conditions when used in a fuel cell, and a continuous manufacturing method thereof.

  A solid polymer electrolyte fuel cell has a structure in which a solid polymer electrolyte membrane is used as an electrolyte and catalyst electrodes are bonded to both surfaces of the membrane.

  When used as a fuel cell, the polymer solid electrolyte membrane needs to have a low membrane resistance. For that purpose, it is desirable that the film thickness be as thin as possible. However, if the film thickness is too thin, there are problems that pinholes are easily formed during film formation, the film is broken during electrode forming, and a short circuit between the electrodes is likely to occur. In addition, since solid polymer electrolyte membranes used in fuel cells are always used in a wet state, reliability such as pressure resistance and cross-leakage during differential pressure operation due to swelling, deformation, etc. of the polymer membrane due to wetting is reliable. Problems will arise.

  Therefore, in Patent Document 1 below, an ion exchange membrane that does not break even when a change in the water content of the ion exchange resin repeatedly occurs, and the ion exchange resin and a porous membrane such as a fluororesin are in close contact with each other and pinholes are difficult to form. For the purpose of the above, at least the pores of a porous membrane such as a fluororesin prepared by stretching are impregnated with a polymer dissolved in a solvent and dried to adhere to the porous membrane, and then ion exchange groups are introduced to introduce ions. A method of manufacturing an exchange membrane is disclosed.

  By the way, the method for producing an ion exchange membrane disclosed in the following Patent Document 1 has a problem in that since the polymer is soluble in a solvent, the chemical stability is low and the electrolyte performance is likely to deteriorate. That is, since the ion exchange membrane is produced using a polymer dissolved in a solvent, the above-described problems have occurred. In addition, the membrane easily deteriorates due to the swelling change caused by the water content of the electrolyte membrane, and there is a problem that the durability of the fuel cell or the like is shortened. Furthermore, the electrolyte has water retention, and the electrolyte swells due to the movement of protons in the membrane or the purification of water at the electrode, but the porous body does not swell. There was a problem that conductivity was lowered. Electrolyte resin (H-type resin) that has been hydrolyzed in an alcohol solvent and mixed with proton conductivity can be impregnated to give the porous body electrolyte performance, but the intermolecular bonds are weak and soluble. Therefore, there is a problem that it is easily affected by radicals generated at the electrode.

  Therefore, in Patent Document 2 below, a mixture of a perfluorocarbon polymer having a sulfonic acid group or a precursor group thereof and a fibrillated fluorocarbon polymer is formed into a film shape and stretched on at least one side of the obtained film. A method for producing an electrolyte membrane for a polymer electrolyte fuel cell is disclosed in which an auxiliary film is laminated and then stretched under heating. It is also disclosed that a heated roll press is used to stretch the laminate under heating.

  Patent Document 3 below provides a manufacturing apparatus and a manufacturing method capable of continuously and efficiently manufacturing an ion exchange membrane that is chemically stable and hardly causes deterioration in electrolyte performance, and can improve strength. For the purpose of providing an ion exchange membrane production apparatus and production method that can suppress pore collapse of the porous membrane (base material sheet) and improve the stability of bonding with an electrode catalyst, Means for continuously feeding, means for pressurizing and impregnating molten electrolyte polymer in the porous membrane to form an electrolyte membrane, and means for imparting ion exchange to the electrolyte polymer in the electrolyte membrane An ion exchange membrane manufacturing apparatus is disclosed. This ion exchange membrane manufacturing apparatus pressurizes and impregnates a molten electrolyte polymer into a continuously supplied porous membrane to form an electrolyte membrane (F-type resin), and then forms an electrolyte polymer in the electrolyte membrane. Ion exchange properties are imparted (H-type resin), and the electrolyte membrane is formed on the porous membrane by heating and melting the electrolyte membrane and the electrolyte polymer.

JP-A-9-194609 JP 2001-345111 A Japanese Patent Laying-Open No. 2005-162784

  In the method disclosed in Patent Document 1, the polymer is hydrophilic, while the stretched porous membrane is hydrophobic, and it is easy to become familiar with the solvent, but is highly durable. Absent. Therefore, there is a concern that the electrolyte and PTFE are separated during use.

  Moreover, although the technique disclosed in Patent Document 2 and Patent Document 3 described above for melting and impregnating a reinforcing membrane with an electrolyte is an excellent method for producing a composite electrolyte membrane, (1) Shortening of the impregnated film formation time is required, and (2) problems in the roll press method include (i) non-impregnated part and impregnated part, impregnation unevenness, (ii) sufficient electrolyte impregnation There were problems such as damage to the reinforcing membrane before and (iii) deformation of the membrane due to the protrusion of the electrolyte resin.

The reason why such a problem occurs is as follows.
(1) Since it is a single wafer type, it takes a lot of time to manufacture one sheet due to avoidance of membrane cutting, sample take-out time, pasting time, press time considering heat transfer of the entire press jig, etc. .
(2) In the roll pressing step, the sample is subjected to high-pressure pressing while being in contact with the heating roll, but since the contact time is only in the nip, the heat transfer time is extremely short. For this reason, the amount of heat transfer becomes insufficient, and when the load is maximized, the electrolyte resin is not sufficiently melted, so the pressure of the roll press is transmitted to the reinforcement membrane through the electrolyte resin, so that the reinforcement membrane is not impregnated. fall into disrepair.
(3) Since the impregnation conditions are carried out under high temperature conditions where the resin flows, if the pressure is applied during the impregnation, the resin flows in the out-of-plane direction.

  Patent Document 3 discloses a composite polymer electrolyte membrane obtained by pressure-impregnating a polymer electrolyte having proton conductivity melted in a porous membrane or a polymer electrolyte precursor resin having proton conductivity by hydrolysis. As a means for forming, a method is disclosed in which the resin discharged from a screw extruder is pressure impregnated by directly contacting a reinforcing film conveyed between feeding rolls opposed to a resin mold. Although pressurization is performed by narrowing the distance between the resin mold and the feed roll, the balance between the reinforcing film transport tension and the applied pressure directly affects the impregnation uniformity, and the apparatus involves difficulty in setting transport conditions. Further, the extruded resin has a problem that it protrudes out of the porous film when the film thickness is adjusted in the downstream process.

  The present invention was invented in view of the above-mentioned problems of the prior art, and in the production of a composite polymer electrolyte membrane by impregnating a porous membrane with an electrolyte resin, impregnation unevenness was suppressed and the surface of the electrolyte membrane was The purpose of the present invention is to improve the uniformity of the resin, improve the quality of the composite polymer film, make the manufacturing apparatus and the working environment compact, and efficiently impregnate the electrolyte resin without protruding. Another object of the present invention is to improve the power generation performance of the fuel cell provided with the composite polymer membrane.

  As a result of earnestly examining the combination of a single membrane and a porous membrane made of an electrolyte resin and a press roll, in order to produce a composite polymer electrolyte membrane by impregnating a porous membrane with an electrolyte resin, The present inventors have found that the above problems can be solved, and have reached the present invention.

  That is, first, the present invention is an invention of an apparatus for producing a composite polymer electrolyte membrane, and has at least (1) a means for feeding a porous membrane as a reinforcing membrane, and (2) proton conductivity. Means for feeding a polymer electrolyte single membrane or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis; (3) the porous membrane and the polymer electrolyte single membrane, or the porous membrane and the hydrolysis A means for heating the polymer electrolyte precursor single membrane having proton conductivity by means of (4) the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis as the porous membrane Means for impregnation under pressure.

Here, the proton-conducting polymer electrolyte (hereinafter sometimes referred to as H-type resin) has a sulfonic acid group and the like, and has proton conductivity even if it is not modified in a later step. Yes, a polymer electrolyte precursor having proton conductivity by hydrolysis (hereinafter sometimes simply referred to as a polymer electrolyte precursor or F-type resin) is a hydrolysis process or an acidification process in a later step. Has a precursor group that is modified to a proton conductive group such as a sulfonic acid group, for example, a —SO ₂ F group or a —SO ₂ Cl group.

  In addition, the polymer electrolyte single membrane and the polymer electrolyte precursor single membrane are respectively a film shape (film or sheet) in which the polymer electrolyte and the polymer electrolyte precursor are not in a resin mass state or a molten state, but are themselves self-supporting. ).

  Furthermore, the composite polymer electrolyte membrane referred to in the present invention is an electrolyte membrane having strength and conductivity by filling the pores of a porous membrane as a reinforcing membrane with a polymer electrolyte.

  In the present invention, it is preferable that each of the above means (1) to (4) can be continuously operated to provide a continuous production apparatus for a composite polymer electrolyte membrane. That is, since the polymer electrolyte single membrane, the polymer electrolyte precursor single membrane, and the porous membrane can be continuously moved at a constant speed, the polymer electrolyte membrane can be continuously produced.

  In the production apparatus of the present invention, (3) means for heating the porous membrane and the polymer electrolyte single membrane, or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis; 4) The means for pressure impregnating the porous membrane with the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis may be independent mechanisms, but these (3) The means (4) and (4) preferably comprise a series of belt presses and rolls. In the production apparatus of the present invention, maintaining the impregnation temperature in (4) at a constant temperature is a factor that greatly affects the improvement in impregnation, so in (3), the heating temperature is the polymer electrolyte single membrane or Productivity can be improved by heating the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis at a temperature close to the melting temperature. However, in continuous conveyance, it becomes difficult for the molten resin to stand on its own, and this causes the non-uniform impregnation portion to be generated by the means (4). By using a series of belt presses and rolls, it is possible to heat and convey while restricting in-plane deformation, it is possible to impregnate uniformly, and productivity can be improved.

  In the production apparatus of the present invention, the means for heating (3) the porous membrane and the polymer electrolyte single membrane, or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, (4) Prior to the means for pressure impregnating the porous membrane with the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, the porous membrane and the polymer electrolyte single membrane, or the A porous membrane and a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis are preheated (specifically, preheating). Specifically, a combination of a belt press and a heating roller is preferable. By combining the belt press and the heating roller, the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane can be preheated sufficiently uniformly as compared with the case where a pair of heating rollers is simply used.

  The material of the belt press is not particularly limited, but a stainless steel (SUS) belt or a steel belt with a surface treatment (such as a Teflon (trade name) coat) that imparts corrosion resistance to the surface from the viewpoint of corrosion resistance, heat transfer, etc. Preferably exemplified. Similarly, the material of the heating roller is not particularly limited, but a stainless steel (SUS) roller, a steel roller having a surface treatment (such as hard chrome plating) that imparts corrosion resistance to the surface, and the like are preferably exemplified.

  In the production apparatus of the present invention, a pair of pressure rollers is preferably used from the viewpoint of continuity as the means for pressure impregnating the porous membrane with the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane. When the surface of at least one of the pair of pressure rollers is soft, it is preferable that the polymer electrolyte or the polymer electrolyte precursor can be prevented from protruding outside the porous membrane.

  By the way, if fuel cell power generation is continued, a gas leak occurs from the electrolyte membrane in the vicinity of the cell wall portion, the electromotive force decreases, and the durability evaluation fails. In the vicinity of the cell edge, the stress due to the swelling / shrinking deformation of the MEA during power generation concentrates on the film edge where the fastening structure is free. Or the film | membrane thinness by the chemical degradation peculiar to an edge has generate | occur | produced. Therefore, gas permeation is likely to occur partially. On the other hand, in order to improve the performance, it is possible to improve the performance by reducing the IR loss. This is because there is a trade-off between the electrolyte membrane thinning and the increase in gas permeability in the evaluation over time.

  Therefore, in the production apparatus of the present invention, in producing a polymer electrolyte single membrane having proton conductivity or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, the thickness of these single membranes is locally determined. A film thickness adjusting means to be controlled can be provided. By controlling the thickness of the single membrane locally, the membrane degradation progresses during fuel cell operation, and membrane thinning occurs. The MEA contributes to battery performance while increasing the thickness near the cell wall and the membrane edge. A portion of the electrolyte membrane can be thinned.

  As a specific example of the film thickness adjusting means, a discharge amount when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film is periodically changed. Preferred are those that fluctuate and those that periodically change the take-up speed when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film. Illustrated.

  2ndly, this invention is invention of the manufacturing method of a composite polymer electrolyte membrane using the manufacturing apparatus of said composite polymer electrolyte membrane, (5) The process of feeding the porous membrane which is a reinforcement film | membrane, (6) a step of feeding a polymer electrolyte single membrane having proton conductivity or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis; and (7) the porous membrane and the polymer electrolyte single membrane. Or a step of heating the porous membrane and a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step described below, and (8) the polymer electrolyte single membrane or hydrolysis And a step of impregnating the porous membrane with a polymer electrolyte precursor single membrane having proton conductivity.

  In the method for producing a composite polymer electrolyte membrane of the present invention, it is possible to continuously operate the steps (5) to (8), (7) the porous membrane and the polymer electrolyte single membrane, Or a step of heating the porous membrane and a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step, and (8) the polymer electrolyte single membrane or the polymer electrolyte precursor single The step of pressure impregnating the membrane into the porous membrane is preferably performed using a series of belt presses and rolls, and the step of heating the polymer electrolyte single membrane or polymer electrolyte precursor single membrane is belt pressed and heated. It is preferable to use a roller, the belt press is a steel belt, the heating roller is preferably a steel roller, and a polymer electrolyte single membrane or a polymer electrolyte precursor single membrane is pressed against the porous membrane. The dipping step is preferably performed with a pair of pressure rollers, the surface of at least one of the pair of pressure rollers is preferably soft, and the like. As described in the manufacturing apparatus.

  In the method of the present invention, the time for heating the porous membrane and the polymer electrolyte single membrane or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step is as follows: It is determined in consideration of the temperature at which the resin melts and the impregnation property. For example, when combining the above-described belt press and heating roller, it is preferable to select a preheating time of 10 seconds to 2 minutes.

  As a more specific aspect of the method for producing a composite polymer electrolyte membrane of the present invention, a porous membrane as a reinforcing membrane and two polymer electrolyte single membranes having proton conductivity on both sides of the porous membrane or By sandwiching a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis and sandwiching two peelable protective sheets from both sides, these peelable protective sheets-polymer electrolyte single membrane or polymer electrolyte precursor It is preferable to laminate and feed the body single membrane-porous membrane-polymer electrolyte single membrane or polymer electrolyte precursor single membrane-peelable protective sheet.

  In the method of the present invention, when the polymer electrolyte single membrane having proton conductivity or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis is produced, the thickness of these single membranes is locally controlled. In particular, the discharge rate when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film varies periodically. Or by periodically changing the take-up speed when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film. The method of locally controlling the thickness of the single membrane is preferable as described in the above-described composite polymer electrolyte membrane production apparatus.

  Here, as the porous membrane, a known material can be used as a reinforcing material for the composite polymer electrolyte membrane. Among these, at least one selected from polytetrafluoroethylene (PTFE), a tetrafluoroethylene copolymer containing 10 mol% or less of a copolymer component, and polysiloxane is preferably exemplified.

  The composite polymer electrolyte membrane produced by the apparatus or method of the present invention can be used for various applications as a functional membrane. 3rdly, this invention is a functional film which consists of said composite polymer electrolyte membrane.

  Fourth, the present invention is a polymer electrolyte fuel cell having a composite polymer electrolyte membrane produced by the above apparatus or method.

  According to the present invention, the thickness of the solid polymer electrolyte membrane can be reduced, and the polymer film or the polymer sheet substrate is used as a support for the electrolyte membrane, so that the strength of the electrolyte membrane is reinforced. Therefore, the fuel cell including the solid polymer electrolyte membrane according to the present invention is highly durable, has a small amount of fuel gas cross-leakage, and can improve current-voltage characteristics.

  In impregnating the porous membrane with the electrolyte resin, preheating the single membrane and the porous membrane made of the electrolyte resin suppresses uneven impregnation and improves the uniformity of the surface of the electrolyte membrane. The quality can be improved, the manufacturing apparatus and the working environment can be made compact, and the electrolyte resin can be effectively impregnated without protruding. Thereby, the power generation performance of the fuel cell including the composite polymer membrane can be improved.

  In addition, when producing polymer electrolyte single membranes having proton conductivity or polymer electrolyte precursor single membranes having proton conductivity by hydrolysis, the thickness of these single membranes is locally controlled to produce cells. In the process, the film thickness at the edge is thickened in a grid pattern in the width direction and the longitudinal direction, and the thickness of the cell center part (the part where the catalyst layer is laminated) is also the edge thickness. It can be done independently, and approaches to improve durability and acquire performance can be approached independently. As a result, it is possible to ensure high durability performance while improving the power generation performance by making the film thickness of the MEA portion where the catalyst layer is bonded extremely thin.

FIG. 1 shows an example of a conventional process for producing a composite polymer electrolyte membrane by thermocompressing an electrolyte to a porous membrane using a flat plate press. The upper and lower sides of the reinforcing membrane are sandwiched between electrolyte membranes, and the upper and lower sides are sandwiched with Teflon (trade name), and heated and pressurized using silicon rubber as a buffer material. Specifically, since the reinforcing film is damaged at high pressure, pressurization is performed at a low pressure of about 5 kg / cm ^{2 for} about 10 to 15 minutes with a flat plate press until the entire laminated film reaches the melting temperature.

  FIG. 2 shows an example of a process for producing a composite polymer electrolyte membrane by thermocompression bonding of an electrolyte preheated to a porous membrane according to the present invention. All roll-to-roll, with a porous membrane as a reinforcing membrane as a central base material, two polymer electrolyte single membranes having proton conductivity on both sides of the porous membrane or a polymer having proton conductivity by hydrolysis The electrolyte precursor single film is sandwiched, and two peelable protective sheets (Teflon sheet: trade name) are sandwiched from both sides thereof, and these peelable protective sheets-polymer electrolyte single film or polymer electrolyte precursor single film -Porous membrane-Polymer electrolyte single membrane or polymer electrolyte precursor single membrane-Peelable protective sheet is laminated and fed. These laminates are transported by sandwiching one of the rolls constituting the pair of crimping rolls and the surface of the pair of crimping rolls with an SUS belt that rotates endlessly in an inverted S shape, and preliminarily heating these laminates. At the same time, it is crimped by a pair of rolls. As a result, the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane is moderately softened, and the porous membrane is uniformly impregnated. Specifically, the electrolyte resin can be sufficiently softened by preheating for 1 min with a continuous roll-to-roll, and the pressure can be continuously increased by impregnation.

  FIG. 3 shows the control of the thickness of these single membranes in the production of the proton conductive polymer electrolyte single membrane or the proton conductive polymer electrolyte precursor single membrane according to the present invention. The schematic diagram of the film thickness adjustment process to perform is shown.

By the film thickness adjusting method shown in FIG. 3, the film is formed so that a thick film portion is formed in the width direction and the longitudinal direction. In FIG. 3, each symbol represents the following matters.
X: film width dimension that becomes an end when formed into a cell Y: longitudinal dimension that becomes a control section when formed into a cell D1: film thickness required to ensure durability D2: film thickness L1 required to ensure performance : Thick film partial lip clearance L2: Thin film partial lip clearance W1: Thick film resin discharge amount W2: Thin film resin discharge amount V1: Thick film pulling speed V2: Thin film pulling speed

  The resin discharge amount Wl and / or W2 is periodically changed (by Y), or the take-up speeds V1 and / or V2 are periodically changed (by Y) to form a thick film portion in the longitudinal direction. . Further, by forming a difference between the lip clearances L1 and L2, the film is formed so that a thick film portion is formed in the width direction.

  FIG. 4 shows a structure of a polymer electrolyte single membrane having proton conductivity whose thickness is controlled locally or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis and a reinforcing membrane manufactured in FIG. The schematic diagram of a bonding process and these integration processes is shown.

  As shown in FIG. 4, the electrolyte resin single film is bonded to both surfaces of the reinforcing film so that the thick film portion and the capsule portion of the single electrolyte resin film coincide with each other. Next, the reinforcing film and the electrolyte resin single film are integrated by heating and pressing so as to be immersed in the melting table. Thereby, the electrolyte membrane thickened in a lattice shape is completed.

  FIG. 5 shows a schematic view of a fuel cell assembly process using the electrolyte membrane manufactured in FIG. 4 and thickened in a lattice shape. As shown in FIG. 5, the electrolyte membrane that has been thickened in a lattice shape is arranged so that the film thickness portion is just at the end of the cell, and a catalyst layer, a diffusion layer, and a separator are assembled to the electrolyte membrane.

  Hereinafter, the steps of FIGS. 3 to 5 will be described in detail. In this description, the electrolyte membrane is formed according to the melt impregnation method.

  In the film thickness adjusting step of FIG. 3, at the time of manufacturing the electrolyte single film, a portion that becomes an end when the cell is assembled is formed into a film thickness. Specifically, (1) In the step of forming an electrolyte resin single film by melt extrusion film formation, the die width adjustment is performed to increase the film thickness by adjusting the die lip in the die width direction position that is the end in the cell forming step. The film thickness is increased by reducing the take-off speed or by reducing the resin extrusion amount, etc., at the conveyance direction position that becomes the end in the cell forming step.

In the film thickness adjusting process of FIG. 4, the electrolyte single film manufactured in the film thickness adjusting process is bonded to the front and back of the reinforcing film in the melt impregnation process. For this reason, adjustment is performed so that the positions match when bonding. Next, it melt-impregnates after bonding.
3 to 4 can be realized by roll-to-roll, which is preferable from the viewpoint of productivity.

  By producing the electrolyte membrane by the steps of FIGS. 3 to 4, it becomes possible to increase the thickness of the end portion in the cell forming step in a lattice shape in the width direction and the longitudinal direction. At the same time, it is possible to reduce the thickness of the cell center (the part where the catalyst layer is laminated) independently of the thickness of the edges, and to approach approaches to improve durability and acquire performance independently. Become. As a result, it is possible to ensure high durability performance while improving the power generation performance by making the film thickness of the MEA portion where the catalyst layer is bonded extremely thin.

  The series of steps described above can be manufactured by roll-to-roll, and is excellent in productivity. About an actual process, it is possible by a general conveyance technique and mechanism.

  The polymer film or polymer sheet, which is a base material for the porous membrane, used in the present invention is not only composed of a polymer material having a single chemical structure including a copolymer, but also having a plurality of different chemical structures. Polymer alloys and polymer blends made of these polymer materials can also be used. The polymer film or polymer sheet may be a composite containing other materials such as inorganic compounds and metals in a dispersed state, and may include two or more layers including layers made of different plastics or other materials. A laminate having a layer structure may be used.

  Specific examples of the polymer film or sheet include, for example, methacrylate resins such as polymethyl methacrylate (PMMA); polystyrene, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin). Polystyrene; Polyimide (PI); Polyetherimide (PEI); Polyamideimide; Polyesterimide; Polycarbonate (PC); Polyacetal; Polyarylene ether such as polyphenylene ether (PPO); Polyphenylene sulfide (PPS); Polyarylate; Polyaryl; Polysulfone (Polysulfone); Polyethersulfone (PES) (Polyethersulfone); Polyurethanes; Polyethylene terephthalate (PET) Polyester resins such as polyether ether ketone (PEEK) and polyether ketone ketone (PEKK); polyacrylic esters such as polybutyl acrylate and polyethyl acrylate; polybutoxymethylene Polyesters; Polysulfides; Polyphosphazenes; Polytriazines; Polycarboranes; Polynorbornene; Epoxy resin; Polyvinyl alcohol; Polyvinylpyrrolidone; Polydienes such as polyisoprene and polybutadiene; Polyisobutylene, etc. Polyalkenes; Fluorine resins such as vinylidene fluoride resin, hexafluoropropylene resin, hexafluoroacetone resin, polytetrafluoroethylene resin; polyethylene, Polypropylene, ethylene - (a thermoplastic resin) resins such as polyolefin resins such as propylene copolymer including without being limited thereto.

  These polymer films or sheet base materials can be appropriately selected according to the use of the composite polymer porous membrane having pores. For example, in applications such as filters and separators, chemical stability and the like are considered. Fluorine resin or olefin resin can be preferably used.

  The thickness of the polymer film or sheet substrate is not particularly limited, and can be appropriately selected depending on the use of the composite polymer porous membrane having pores. For example, 0.1 μm or more (for example, 0 .1 μm to 10 mm).

  In the present invention, various known polymer electrolytes can be used as the material for the polymer electrolyte single membrane. For example, a polymer having a strong acid group such as sulfonic acid in its chemical structure, such as a polymer such as vinyl sulfonic acid, vinyl phosphonic acid, allyl sulfonic acid, allyl phosphonic acid, styrene sulfonic acid, styrene phosphonic acid, is preferable. The invention is not limited to these.

In the present invention, various known polymer electrolyte precursors can be used as the polymer electrolyte precursor single film material. The polymer electrolyte precursor is not only a polymer electrolyte monomer itself having the above ionic functional group but also a monomer having a group that is converted into an ionic functional group by a reaction in a subsequent step. For example, in the present invention, a polymer film or sheet substrate is impregnated with an electrolyte-generating monomer, polymerized, and further, a sulfonyl halide group [—SO ₂ X ¹ ] or a sulfonate group [—SO ₃ ] in the molecular chain. R ¹ ] or a halogen group [—X ₂ ] is produced by making it into a sulfonic acid group [—SO ₃ H]. In addition, phenyl groups, ketones, ether groups and the like present in the electrolyte-generating monomer units present in the polymer film or sheet substrate can be produced by introducing sulfonic acid groups with chlorosulfonic acid.

In the present invention, the electrolyte-forming monomers that are polymerized to become polymer electrolyte precursors are typically monomers shown in the following (1) to (6).
(1) CF ₂ ═CF (SO ₂ X ¹ ), which is a monomer having a sulfonyl halide group (wherein X ¹ is a halogen group —F or —Cl; the same shall apply hereinafter), CH ₂ ═CF ( SO ₂ X ¹ ), and CF ₂ ═CF (OCH ₂ (CF ₂ ) _m SO ₂ X ¹ ) (wherein, m is 1 to 4, the same shall apply hereinafter). Monomer.
(2) CF ₂ ═CF (SO ₃ R ¹ ), which is a monomer having a sulfonate group (wherein R ¹ is an alkyl group, —CH ₃ , —C ₂ H ₅ or —C (CH ₃ ) ₃ The same shall apply hereinafter.), One or more monomers selected from the group consisting of CH ₂ = CF (SO ₃ R ¹ ) and CF ₂ = CF (OCH ₂ (CF ₂ ) _m SO ₃ R ¹ ).

_{(3) CF 2 = CF (} O (CH 2) m X 2) ( wherein, ^{X 2} is -Br or -Cl halogen group. Hereinafter the same.), And _{CF 2 = CF (OCH 2 (} CF ₂ ) One or more monomers selected from the group consisting of _m X ² ).
(4) CF ₂ = CR ² (COOR ³ ) which is an acrylic monomer (wherein R ² is —CH ₃ or —F, and R ³ is —H, —CH ₃ , —C ₂ H ₅ or — And C (CH ₃ ) _{3. The} same shall apply hereinafter.), And one or more monomers selected from the group consisting of CH ₂ = CR ² (COOR ³ ).

(5) One or more monomers selected from the group consisting of styrene, styrene derivative monomers 2,4-dimethylstyrene, vinyltoluene, and 4-tertbutylstyrene.
(6) Acetylnaphthylene, vinyl ketone CH ₂ ═CH (COR ⁴ ) (wherein R ⁴ is —CH ₃ , —C ₂ H ₅ or a phenyl group (—C ₆ H ₅ )), and vinyl ether CH. ₂ = CH (OR ⁵ ) (wherein R ⁵ is —C _n H _{2n + 1} (n = 1 to 5), —CH (CH ₃ ) ₂ , —C (CH ₃ ) ₃ , or a phenyl group. .) One or more monomers selected from the group consisting of:

  If desired, specific examples of crosslinking agents for the electrolyte-forming monomers used in the present invention include divinylbenzene, triallyl cyanurate, triallyl isocyanurate, 3,5-bis (trifluorovinyl) phenol, and 3,5- Examples thereof include bis (trifluorovinyloxy) phenol. One or more kinds of these cross-linking agents are added in an amount of 30 mol% or less based on the total monomer to cause cross-linking polymerization.

  Examples of the use of the composite polymer electrolyte membrane produced in the present invention include various members used in fuel cells such as a gas diffusion layer, a current collecting layer, a moisture permeable layer, and a moisture retaining layer, a nickel metal hydride battery, and a lithium ion battery. It can be used for various functional members such as battery separators used in various types of batteries.

  When the composite polymer electrolyte membrane produced in the present invention is used for a fuel cell, the thickness of the solid polymer electrolyte membrane can be reduced, and the polymer film or the polymer sheet substrate can be used as the electrolyte membrane. Since the strength of the electrolyte membrane can be reinforced because it is used as a support, the fuel cell provided with the composite polymer electrolyte membrane produced in the present invention is highly durable and has a cross leak amount of fuel gas. Less current-voltage characteristics can be achieved.

Examples of the present invention will be described below.
[Examples 1 and 2 and Comparative Examples 1 and 2]
The present invention was implemented with the apparatus and process shown in FIG. As a porous membrane as a reinforcing membrane, a PTFE porous membrane having a thickness of 10 μm prepared by biaxial stretching of polytetrafluoroethylene (PTFE) is used, and Nafion100 (trade name) having a thickness of 13 μm is used as an electrolyte membrane. A Teflon sheet (trade name) having a thickness of 100 μm was used as the peelable protective sheet.

In FIG. 2, (1) to (6) indicate regions of the following steps.
(1) Step of sending out a fluorine-based electrolyte resin / reinforcing film and peelable slip sheet (2) Step of laminating fluorine-based electrolyte resin, reinforcing film and peelable slip sheet (3) Step of heating and conveying (4) Roll Step of pressurizing by pressing (5) Step of peeling interleaving paper (6) Step of winding up melt-impregnated film A comparative example and examples were formed under the roll press conditions shown in Table 1 below.

  For durability evaluation, a power generation test was performed, and a change in the sealing pressure between the cathode side and the anode side was set to 0.01 MPa as a threshold value. Table 2 below shows the results of durability evaluation.

  Hereinafter, the matters accompanying the above-mentioned examples will be described with respect to the continuous method of the present invention, the technical significance of preheating, the use of heat-resistant rubber rolls and the like.

[Continuous construction method]
By impregnating with the roll-to-roll method, the amount of work required for impregnation per unit area (cutting, positioning, setting, etc. peculiar to the sheet format) can be greatly improved, and the time required for manufacturing the required area can be shortened. . By being able to manufacture with a roll-to-roll process, a series of processes for forming a fuel cell, that is, forming a catalyst layer, forming a diffusion layer, and forming a separator, can be performed by a roll-to-roll method, and productivity is greatly improved.

[Technical significance of preheating]
Heat to resin flow by preheating. By such a preheating step, it is possible to impregnate even when the pressing time is extremely short such as the roll nip time. The preheating temperature is preferably equal to or higher than the temperature at which the elastic modulus of the electrolyte resin is 1/10 or less of room temperature and 1 × 10 ⁻⁷ Pa or less. In the case of a fluorinated electrolyte resin, 200 ° C. or higher is a preferable preheating temperature. The upper temperature limit is determined in consideration of wrinkles generated during conveyance, thermal deformation of interleaf sheets, and the like. Conveying methods such as tenter gripping, inter-roll processing, and belt gripping can be applied.

[Use of heat-resistant rubber roll]
It is also effective to use a heat-resistant rubber roll to seal the width direction so that it does not flow out even in a resin flow state. Since the film existence space can be limited by the silicon rubber and the steel surface at the time of pressurization, the resin flow from the film end can be suppressed even in the resin flow state. Since the elastic modulus of the electrolyte resin is reduced by high-temperature treatment for the purpose of impregnation, the resin flows out from the end of the laminate during pressurization. A combination of rolls whose ends are sealed at the nip can be suitably used. As an example, application of a rubber roll can be considered. The hardness of the rubber roll is defined by a JIS-A type testing machine or the like, and is generally about 15 to 90. The combination of rolls can be considered by evaluating the heading of the heat resistance, press surface shape and electrolyte resin from the end, but at least one of the upper and lower press rolls is a rubber roll and it is effective to ensure sealing .

[Example 3 and Comparative Examples 3 and 4]
The present invention was implemented through the steps shown in FIGS. The electrolyte membrane used is as follows.
Electrolyte single membrane A: Nafion 1000 single membrane electrolyte single membrane B manufactured with thick film portion 50 μm, thin film portion 6 μm Nafion 1000 single membrane electrolyte single membrane C prepared with uniform 50 μm film thickness condition Nafion 1000 single film manufactured with uniform 6 μm film thickness condition film

  Bonding and continuous roll press impregnation were performed, and bonding and impregnation were performed under the following conditions. For durability evaluation, a power generation test was performed, and a change in the sealing pressure on the cathode side and the anode side was set to 0.01 MPa as a threshold value.

[Example 3]
The electrolyte membrane A is bonded to a 10 μm thick PTFE porous membrane produced by biaxially stretching PTFE. At that time, the roll ends were positioned and bonded so that the thickness profiles of the front and back surfaces were the same.

Using a pair of roll press devices in which a 180 ° C. silicon rubber roll is opposed to a 270 ° C. hard chrome plating roll, the laminated sheet is a hot press roll press at a conveyance speed of 0.5 m / min and a press pressure of 1.2 ton. And a reinforcing membrane was impregnated with an electrolyte resin to prepare a melt-impregnated membrane.
The catalyst layers were bonded to the front and back to make an MEA precursor, which was hydrolyzed to generate MEA.

[Comparative Example 3]
The electrolyte membrane B was bonded to a 10 μm thick PTFE porous membrane produced by biaxially stretching PTFE. Using the pair of roll press devices in which the above-mentioned laminated sheets are opposed to a hard rubber plating roll of 270 ° C. with a silicon rubber roll of 180 ° C., a hot press roll press at a conveying speed of 0.5 m / min and a press pressure of 1.2 ton In practice, a reinforcing membrane was impregnated with an electrolyte resin to produce a melt-impregnated membrane.
The catalyst layers were bonded to the front and back to make an MEA precursor, which was hydrolyzed to generate MEA.

[Comparative Example 4]
The electrolyte membrane C was bonded to a 10 μm thick PTFE porous membrane prepared by biaxially stretching PTFE. Using the pair of roll press devices in which the 180 ℃ silicon rubber roll is opposed to the 270 ° C. hard chrome plating roll, the laminated sheet is a hot press roll press at a conveying speed of 0.5 m / min and a press pressure of 1.2 ton. And a reinforcing membrane was impregnated with an electrolyte resin to prepare a melt-impregnated membrane.

  The catalyst layers were bonded to the front and back to make an MEA precursor, which was hydrolyzed to generate MEA. Table 3 below shows the results of power generation performance evaluation and durability evaluation.

  According to the present invention, it is possible to improve the durability of the composite porous electrolyte membrane, and the fuel cell including the polymer electrolyte membrane manufactured according to the present invention is highly durable, and the fuel gas The amount of cross leak is small, and the current-voltage characteristics can be improved. This enhances the durability and power generation performance of the fuel cell and contributes to its practical use and spread.

An example of a conventional process for producing a composite polymer electrolyte membrane by thermocompressing an electrolyte to a porous membrane using a flat plate press will be described. An example of the process of manufacturing a composite polymer electrolyte membrane by thermocompression bonding of an electrolyte preheated to a porous membrane according to the present invention will be described. Schematic diagram of film thickness adjustment process for locally controlling the thickness of these single membranes in the production of proton conductive polymer electrolyte single membranes or polymer electrolyte precursor single membranes having proton conductivity by hydrolysis Indicates. 3. A process of bonding a polymer electrolyte single membrane having proton conductivity whose thickness is locally controlled or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis and a reinforcing membrane manufactured in FIG. The schematic diagram of the integration process is shown. The schematic diagram of a fuel cell assembly | attachment process is shown using the electrolyte membrane thickened in the grid | lattice form manufactured in FIG.

Claims (24)

  Means for feeding a porous membrane as a reinforcing membrane, means for feeding a polymer electrolyte single membrane having proton conductivity or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, and the porosity Means for heating a membrane and a polymer electrolyte single membrane, or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis with the porous membrane, and proton conductivity by the polymer electrolyte single membrane or hydrolysis An apparatus for producing a composite polymer electrolyte membrane comprising means for pressure impregnating the porous membrane with a polymer electrolyte precursor single membrane.   2. The apparatus for producing a composite polymer electrolyte membrane according to claim 1, wherein each means can be operated continuously.   Means for heating the porous membrane and the polymer electrolyte single membrane, or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, and the proton conduction by the polymer electrolyte single membrane or hydrolysis The method for producing a composite polymer electrolyte membrane according to claim 1 or 2, wherein the means for pressurizing and impregnating the porous membrane with the polymer electrolyte precursor single membrane having a property comprises a series of belt presses and rolls. apparatus.   The means for heating the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis is a belt press or a heating roller. Production equipment for composite polymer electrolyte membranes.   The apparatus for producing a composite polymer electrolyte membrane according to claim 4, wherein the belt press is a steel belt, and the heating roller is a steel roller.   The means for pressure impregnating the porous membrane with the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis is a pair of pressure rollers, and at least one of the rollers The apparatus for producing a composite polymer electrolyte membrane according to claim 1, wherein the surface of the composite polymer electrolyte is soft.   When manufacturing the polymer electrolyte single membrane having proton conductivity or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, a film thickness adjusting means for locally controlling the thickness of these single membranes is provided. The apparatus for producing a composite polymer electrolyte membrane according to any one of claims 1 to 6, wherein:   The film thickness adjusting means periodically varies the discharge rate when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film. The apparatus for producing a composite polymer electrolyte membrane according to claim 7, wherein:   The film thickness adjusting means periodically varies the take-up speed when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is formed by extrusion. The apparatus for producing a composite polymer electrolyte membrane according to claim 7, wherein:   A step of feeding a porous membrane as a reinforcing membrane, a step of feeding a polymer electrolyte single membrane having proton conductivity or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, and the porosity Heating the membrane and the polymer electrolyte single membrane, or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step described below, and the polymer electrolyte single membrane Or a method of producing a composite polymer electrolyte membrane comprising a step of pressure impregnating the porous membrane with a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis.   The method for producing a composite polymer electrolyte membrane according to claim 10, wherein the steps are continuously operated.   Heating the porous membrane and the polymer electrolyte single membrane, or the porous membrane and a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step described later, and the polymer 11. The process of pressure impregnating a porous membrane with an electrolyte single membrane or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, using a series of belt presses and rolls. 11. A method for producing a composite polymer electrolyte membrane according to item 11.   The step of heating the porous membrane and the polymer electrolyte single membrane or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step described below is performed by a belt press and heating. The method for producing a composite polymer electrolyte membrane according to any one of claims 10 to 12, wherein the method is carried out using a roller.   The method for producing a composite polymer electrolyte membrane according to claim 13, wherein the belt press is a steel belt, and the heating roller is a steel roller.   The step of heating the porous membrane and the polymer electrolyte single membrane, or the porous membrane and the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis before the pressure impregnation step is 10 seconds to 2 minutes. The method for producing a composite polymer electrolyte membrane according to any one of claims 10 to 14, wherein:   The step of pressure impregnating the porous membrane with the polymer electrolyte single membrane or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis is performed at least once with a pair of pressure rollers. The method for producing a composite polymer electrolyte membrane according to any one of claims 10 to 15.   The method for producing a composite polymer electrolyte membrane according to claim 16, wherein the surface of at least one of the pair of pressure rollers is soft.   Sandwiching a porous membrane as a reinforcing membrane and two polymer electrolyte single membranes having proton conductivity on both sides of the porous membrane or a polymer electrolyte precursor single membrane having proton conductivity by hydrolysis; and Two peelable protective sheets are sandwiched from both sides of the film, and these peelable protective sheets-polymer electrolyte single membrane or polymer electrolyte precursor single membrane-porous membrane-polymer electrolyte single membrane or polymer electrolyte precursor single The method for producing a composite polymer electrolyte membrane according to any one of claims 10 to 17, wherein a membrane-peelable protective sheet is laminated and fed.   In manufacturing the polymer electrolyte single membrane having proton conductivity or the polymer electrolyte precursor single membrane having proton conductivity by hydrolysis, the thickness of these single membranes is locally controlled. Item 19. A method for producing a composite polymer electrolyte membrane according to any one of Items 10 to 18.   The thickness of these single membranes can be varied by periodically varying the discharge rate when a molten polymer electrolyte having proton conductivity or a polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film. The method for producing a composite polymer electrolyte membrane according to claim 19, wherein the control is locally controlled.   The thickness of these single membranes is varied by periodically varying the take-off speed when the molten polymer electrolyte having proton conductivity or the polymer electrolyte precursor having proton conductivity by hydrolysis is extruded to form a film. The method for producing a composite polymer electrolyte membrane according to claim 19, wherein the control is locally controlled.   The porous membrane is at least one selected from polytetrafluoroethylene (PTFE), a tetrafluoroethylene copolymer containing 10 mol% or less of a copolymer component, and polysiloxane. The manufacturing method of the composite polymer electrolyte membrane in any one of 10 thru | or 21.   A functional membrane comprising a composite polymer electrolyte membrane produced by the apparatus according to claim 1.   A polymer electrolyte fuel cell having a composite polymer electrolyte membrane produced by the apparatus according to claim 1.

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