JP2014175116A - Laminate for fuel battery fabrication, manufacturing method thereof, and manufacturing method of fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate which makes possible to increase the productivity of a film electrode assembly serving as a constituent member of a solid polymer type fuel battery.SOLUTION: A laminate for fuel battery fabrication comprises: a mold releasing film including a base layer formed from a synthetic resin having an elastic modulus of 100-1000 MPa at 150°C and a release layer formed from a syndiotactic polystyrene resin on at least one side of the base layer; and a layer stacked on the mold releasing film and including an ion exchange resin. The layer including an ion exchange resin is an electrolytic film of a solid polymer type fuel battery, an electrode film or a film electrode assembly. A surface of the release layer may have a center-line average roughness Ra of 1-50 nm. The base layer may be composed of a stretch film formed from polyester. The release layer may be formed by coating.

Description

  The present invention relates to a layer containing a release film and an ion exchange resin (electrolyte for a polymer electrolyte fuel cell) used when a membrane electrode assembly, which is a constituent member of a polymer electrolyte fuel cell, is produced (film formation). The present invention relates to a laminate (laminated film) with a membrane, an electrode membrane or a membrane electrode assembly), a method for producing the same, and a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell has a basic configuration called a membrane electrode assembly (MEA). MEA is a laminate obtained by laminating an electrode membrane (catalyst layer or electrode catalyst membrane) mainly composed of carbon powder carrying a platinum group metal catalyst on both surfaces of a solid polymer electrolyte membrane which is an ion exchange membrane. Is further sandwiched between a fuel gas supply layer and an air supply layer which are conductive porous membranes. In this MEA, both the electrolyte membrane and the electrode membrane contain an ion exchange resin, but the electrolyte membrane and the electrode membrane are usually formed by a casting method and / or a coating method. As a method of laminating an electrolyte membrane and an electrode membrane, usually, both layers formed on a support are brought into contact with each other, and are adhered by thermocompression bonding at about 130 to 150 ° C. and a pressure of about 1 to 10 MPa. A method of peeling the body is used. For this reason, a release film is used as the support, and the release film is required to have appropriate peelability and adhesion to the electrolyte membrane and the electrode film, as well as heat resistance. Known release films include, for example, fluorine-based films, silicone-coated polyethylene terephthalate films, polymethylpentene films, and polypropylene films. However, the ion exchange resin contained in the electrolyte membrane and the electrode membrane is a resin having a unique structure having a main chain of a fluororesin having a high releasability and a side chain containing a sulfonic acid group having a low releasability. It is difficult to predict the behavior related to peelability, and it is difficult to balance peelability and adhesion.

  In JP 2003-285396 A (Patent Document 1), in a base film in which an electrode film and / or an electrolyte film made of at least a solid polymer electrolyte is formed on the surface, the base film is on a support film and at least one side thereof. A substrate film for producing an electrode film and / or an electrolyte film on which a film having releasability is laminated is disclosed, and a fluorine-based resin is described as the film having releasability.

  However, the fluorine-based film has excellent heat resistance, releasability, and non-contamination, is expensive, and is difficult to burn in waste incineration after use, and generates toxic gases. Have. Furthermore, since the elastic modulus is low, it is difficult to manufacture by a roll-to-roll method, and productivity is low.

  Japanese Unexamined Patent Publication No. 2009-54362 (Patent Document 2) discloses a release film used for forming a green sheet used as a solid electrolyte of a fuel cell, and a silicone resin on both sides of a biaxially oriented polyester film. A release film having a release layer is disclosed.

  However, although the silicone resin is excellent in heat resistance and releasability, the silicone resin moves to the electrolyte membrane or the electrode membrane to cause contamination, and the quality is easily impaired.

  JP 2009-87604 A (Patent Document 3) discloses a film for transferring a catalyst layer for a fuel cell in which a catalyst layer is formed on one surface of a substrate film. A laminated film of a film A made of a resin having a glass transition temperature of 50 ° C. or higher and a melting point of 200 ° C. or higher and a film B made of an olefin resin having a glass transition temperature of less than 50 ° C. and a melting point of 200 ° C. or higher, As the catalyst layer, a catalyst layer transfer film formed on the film B side is disclosed, and as a resin constituting the film B, poly-4-methylpentene-1, polyethylene, and polypropylene are described.

  However, a film formed of polymethylpentene contains a low molecular weight component, and the low molecular weight component migrates to the electrolyte membrane or the catalyst layer to cause contamination, and the quality is easily impaired. In addition, a film formed of polyethylene or polypropylene has low heat resistance and peelability.

  On the other hand, JP 2011-88387 A (Patent Document 4) includes a syndiotactic polystyrene (SPS) resin as a main component, and heat shrinkage rates in the longitudinal and width directions of the film before and after heat treatment at 180 ° C. for 30 minutes. Discloses a laminate for producing a flexible printed circuit board in which a biaxially oriented film having a thickness of 0.1 to 1.0% and a soft film are laminated. In this document, a film containing an SPS resin is used as a cover resin for protecting an electric circuit formed on a base film by etching or the like.

  However, this document does not describe a fuel cell. Furthermore, in the examples of this document, the substrate, the coverlay, and the laminated film are stacked in order and subjected to thermocompression pressing, and then the laminated film is peeled off and the appearance of the coverlay is observed, but the details of the coverlay are described. Not. Even when this film is used in the manufacture of a fuel cell, the flexibility is too high, and the productivity is lowered.

  Japanese Unexamined Patent Publication No. 2011-94268 (Patent Document 5) discloses a release film for manufacturing synthetic leather having a release layer made of a synthetic resin film obtained by stretching a styrene polymer having a syndiotactic structure. Yes. This document describes a polyurethane resin as a synthetic leather.

  However, this document does not describe a fuel cell. Furthermore, although this document describes a release film formed of a base material such as a synthetic resin film and a release layer, details and significance of the base material are not described, and two layers are laminated. Films have many manufacturing steps and are disadvantageous in terms of recyclability, and are not used in the examples.

  Japanese Patent Laid-Open No. 2001-287316 (Patent Document 6) uses a syndiotactic polystyrene single resin on at least one side of an outermost layer as a release film at the time of molding a printed circuit board, and uses an intermediate layer as the syndiotactic polystyrene resin. A laminated film made of a resin other than thermoplastic resin or thermosetting resin is disclosed. In the examples of this document, an acid-modified polyolefin, high-density polyolefin, and polycarbonate are used as an intermediate layer, and a laminated film is produced by coextrusion.

  However, this document does not describe a fuel cell. Furthermore, since it is an extruded film, irregularities such as fish eyes are likely to occur, and the surface smoothness is low. When the smoothness of the release film is low and the thickness is not uniform, the surfaces of the electrolyte membrane and the electrode film are also affected by the release film, and the smoothness is lowered. As a result, there is a difference in the degree of deterioration of the catalyst due to the occurrence of a close contact portion and a loose contact portion at the interface between the electrolyte membrane and the electrode membrane and the interface between the electrode membrane and the gas diffusion layer. Becomes shorter.

JP 2003-285396 A (Claims 1 and 2, paragraph [0008], Example) JP 2009-54362 A (Claim 1) JP 2009-87604 A (Claim 1, paragraph [0014]) JP 2011-88387 A (Claim 1, paragraph [0002], Example) JP 2011-94268 A (Claim 1, paragraphs [0002] [0019] to [0023], Examples) JP 2001-287316 A (Claim 1, paragraph [0001], Example)

  Accordingly, an object of the present invention is to provide a laminate (laminated film) capable of improving the productivity of a membrane electrode assembly which is a constituent member of a polymer electrolyte fuel cell, a manufacturing method thereof, and a membrane electrode junction of a polymer electrolyte fuel cell. It is in providing the manufacturing method of a body.

  Another object of the present invention is to provide a stable process without peeling between the electrolyte membrane or the electrode membrane and the release film, even if it is manufactured by heat treatment in a roll-to-roll manner. An object of the present invention is to provide a laminate capable of producing a membrane electrode assembly, a method for producing the same, and a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell.

  Still another object of the present invention is to provide a laminate capable of producing a membrane electrode assembly for a polymer electrolyte fuel cell without contaminating the electrolyte membrane or electrode membrane, a method for producing the same, and a membrane electrode for a polymer electrolyte fuel cell. It is providing the manufacturing method of a conjugate | zygote.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a base material layer formed of a synthetic resin having a specific elastic modulus is formed on at least one surface of the base material layer and is syndiotactic. By laminating an electrolyte membrane, an electrode membrane or a membrane electrode assembly of a solid polymer fuel cell on a release film including a release layer formed of a tic polystyrene resin (SPS resin), the membrane Since it has peelability and heat resistance suitable for producing an electrode assembly, the productivity of the membrane electrode assembly can be improved.

  That is, the laminate of the present invention is a laminate formed of a release film and a layer laminated on the release film and containing an ion exchange resin, and the release film is 150 ° C. A base material layer formed of a synthetic resin having an elastic modulus of 100 to 1000 MPa, and a release layer formed on at least one surface of the base material layer and formed of a syndiotactic polystyrene-based resin. The layer containing the ion exchange resin is an electrolyte membrane, an electrode membrane, or a membrane electrode assembly of a polymer electrolyte fuel cell. The center line average roughness Ra of the release layer surface may be 1 to 50 nm. The base material layer may be a stretched film formed of polyester. The release layer may be formed of a coating. The ion exchange resin may be a fluororesin having a sulfonic acid group in the side chain. The laminate of the present invention may be a laminate produced by a roll-to-roll method.

  The manufacturing method of the said laminated body including the lamination process which laminates | stacks the layer containing an ion exchange resin on a release film is also contained in this invention.

  Moreover, the manufacturing method of the membrane electrode assembly of a polymer electrolyte fuel cell including the peeling process which peels a release film from the said laminated body is also contained in this invention.

  In the present invention, a base material layer formed of a synthetic resin having a specific elastic modulus and formed on at least one surface of the base material layer and formed of a syndiotactic polystyrene resin (SPS resin) An electrolyte membrane, an electrode membrane or a membrane electrode assembly of a polymer electrolyte fuel cell is laminated on a release film including a release layer, and the release layer is suitable for producing the membrane electrode assembly Since peelability and heat resistance can be realized, the productivity of the membrane electrode assembly can be improved. In particular, since the release film has appropriate elasticity, it can be wound on a roll, can be continuously produced by a roll-to-roll system, and is heated by a roll-to-roll system ( For example, even if it manufactures by heat-processing 140 degreeC or more, it can manufacture stably, without peeling between the layers of an electrolyte membrane or an electrode film, and a release film, and can improve productivity. In addition, since the releasability can be improved without including a low molecular weight release agent such as a silicone compound, a membrane electrode assembly for a fuel cell can be produced without contaminating the electrolyte membrane or the electrode membrane.

[Laminate]
The laminate of the present invention is formed of a release film and a layer (electrolyte membrane, electrode membrane or membrane electrode assembly) laminated on the release film and containing an ion exchange resin.

(Release film)
The release film is a release film for producing a membrane electrode assembly (MEA) of a polymer electrolyte fuel cell, and is a substrate formed of a synthetic resin having an elastic modulus of 100 to 1000 MPa at 150 ° C. And a release layer formed of a syndiotactic polystyrene (SPS) resin. In particular, the release film of the present invention may be a film for peeling an MEA after laminating an electrolyte membrane and / or an electrode membrane containing an ion exchange resin on the membrane.

(A) Release layer The SPS resin may have a regular arrangement (stereoregularity) in which side chain phenyl groups protrude alternately with respect to the main chain as a main structure. The degree of stereoregularity (tacticity) is determined by nuclear magnetic resonance ( ¹³ C-NMR) using isotope carbon, which are continuous constituent units such as diads, triads, and triads. (Pentad) can be evaluated by quantifying, and in the case of a syndiotactic structure, for example, it may be evaluated by the ratio of racemic dyad or racemic pentad. The ratio of racemic dyad in the SPS resin may be, for example, 75% or more, preferably 85% or more, more preferably 95% or more, and the ratio of racemic pentad is 30% or more, preferably 50%. More preferably, it may be 70% or more. If the stereoregularity is too low, the crystallinity of the SPS resin is lowered and the heat resistance of the release film is lowered.

  The SPS resin may have a melting point (Tm) of about 270 ° C. or less, for example, 200 to 270 ° C., preferably 220 to 270 ° C., and more preferably about 240 to 270 ° C. The glass transition temperature (Tg) of the SPS resin may be 100 ° C. or lower, and is, for example, 40 to 100 ° C., preferably 60 to 100 ° C., and more preferably about 80 to 100 ° C. If the glass transition temperature and the melting point are too high, the production of the resin becomes difficult. In the present specification, the glass transition temperature and the melting point can be measured using a differential scanning calorimeter (DSC).

  The crystallinity of the SPS resin may be, for example, 10% or more, for example, 10 to 100%, preferably 20 to 80%, and more preferably about 30 to 50%. In this specification, the crystallinity can be obtained by measuring wide-angle X-rays using an X-ray diffractometer.

  Examples of the aromatic vinyl monomer for forming the SPS resin include styrene and alkyl-substituted styrene (for example, vinyl toluene such as o-methyl styrene, m-methyl styrene, p-methyl styrene, vinyl xylene, p -Ethyl styrene, p-isopropyl styrene, butyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, etc.), alkoxy-substituted styrene (for example, methoxy styrene, ethoxy styrene, etc.), halogen-substituted styrene (for example, o- Chlorostyrene, m-chlorostyrene, p-chlorostyrene, o-bromostyrene, o-fluorostyrene, etc.), α-alkyl substituted styrene substituted with an alkyl group at the α-position (for example, α-methylstyrene, α-ethylstyrene) Aryl substituted styrene (e.g. Nirusuchiren etc.), and the like vinylnaphthalene. These aromatic vinyl monomers can be used alone or in combination of two or more.

Among these aromatic vinyl monomers, styrene, _C1-4 alkyl-substituted styrene (vinyltoluene such as m-methylstyrene and p-methylstyrene, pt-butylstyrene, etc.), halogen-substituted styrene (m- Chlorostyrene, p-chlorostyrene, p-fluorostyrene and the like), α-C _1-4 alkyl-substituted styrene (α-methylstyrene and the like) are preferable, and styrene is particularly preferable. When combining styrene with other aromatic vinyl monomers (such as p-methylstyrene), the proportion of other aromatic vinyl monomers is based on the total amount of styrene and other aromatic vinyl monomers. For example, 50 mol% or less may be sufficient, for example, 1-30 mol%, Preferably it is 3-20 mol%, More preferably, it is about 5-15 mol%.

The SPS resin may be a copolymer of a monomer copolymerizable with the aromatic vinyl monomer as long as the coordination property (crystallinity) is not impaired. Examples of the copolymerizable monomer include α-olefins (for example, C _2-8 olefins such as ethylene, propylene, butene, hexene, and octene), and acrylic monomers (for example, (meth) acrylic). Acid, methyl (meth) acrylate, (meth) acrylic acid C _1-10 alkyl ester such as ethyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, etc.), vinyl cyanide Monomers (for example, (meth) acrylonitrile, etc.), unsaturated polycarboxylic acids or acid anhydrides (for example, (anhydrous) maleic acid, etc.), dienes (for example, butadiene, isoprene, etc.), cyclic dienes (For example, cyclopentadiene, dicyclopentadiene, etc.). These copolymerizable monomers can be used alone or in combination of two or more. The proportion of copolymerizable monomers in all monomers may be 50 mol% or less, for example, 1 to 50 mol%, preferably 3 to 40 mol%, more preferably 5 to 30 mol%. Degree.

  As the SPS resin, polystyrene, a copolymer of styrene and p-methylstyrene, a copolymer of styrene and ethylene, and the like are preferable, and polystyrene is particularly preferable. The SPS resin may be a hydrogenated polystyrene resin.

  The weight average molecular weight of the SPS resin is, for example, 10,000 to 1,000,000, preferably 100,000 to 500,000, more preferably 150,000 to 400,000 (especially 180,000) in terms of polystyrene in gel permeation chromatography (GPC). ~ 350,000). When the molecular weight is too low, the heat resistance is lowered, and when it is too large, it is difficult to produce the SPS resin.

  The SPS resin is excellent in heat resistance, but preferably has moderate elasticity from the viewpoint of productivity in a roll-to-roll system, for example, the elastic modulus at 150 ° C. is 500 MPa or less. For example, it may be 1 to 500 MPa, preferably 10 to 400 MPa, and more preferably about 30 to 300 MPa. When the elastic modulus is too large, productivity is lowered.

  The release layer may be formed of the SPS resin alone or may be formed of a composition containing the SPS resin.

  The composition may further contain conventional additives. Examples of conventional additives include fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), antistatic agents, stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity adjustments Agents, thickeners, antifoaming agents and the like may be included. As long as the surface smoothness is not impaired, organic or inorganic particles (for example, an anti-blocking agent such as zeolite) may be included, but it is preferably not included from the viewpoint of improving the surface smoothness.

  In particular, in the present invention, it is preferable that the releasability can be improved without containing a low molecular weight release agent such as a silicone compound that easily contaminates the electrolyte membrane or the electrode membrane, and it is preferable that the silicone compound is not substantially contained. .

  The surface of the release layer is excellent in surface smoothness, can improve the surface smoothness and thickness uniformity of the electrolyte membrane and / or electrode membrane of the polymer electrolyte fuel cell, and can improve the life of the fuel cell. Moreover, since it has moderate roughness, it is excellent in handleability. The centerline average roughness Ra of the release layer surface can be selected from a range of about 1 to 50 nm, and is, for example, about 10 to 40 nm, preferably 15 to 35 nm, and more preferably 20 to 30 nm (particularly 20 to 25 nm). If Ra is too small, the coating layer is likely to be repelled and damaged when a layer containing an ion exchange membrane is applied, and the adhesion between the base material layer and the release layer is reduced, while Ra is large. If too much, the life of the fuel cell is shortened.

  In the present specification, the center line average roughness Ra can be measured by a method based on JIS B0601.

  The release layer may be formed of a stretched film from the viewpoint of improving the film strength. The stretching may be uniaxial stretching, but biaxial stretching is preferred from the viewpoint that the film strength can be improved. Further, the biaxial stretching may be sequential biaxial stretching, but simultaneous biaxial stretching is preferred from the viewpoint of excellent surface smoothness. In sequential biaxial stretching, scratches are easily caused by contact with the roll during longitudinal stretching, and if scratches are present, the peelability is lowered, the surface smoothness of the electrolyte membrane and electrode membrane is lowered, and the battery characteristics are lowered ( Battery life due to a decrease in adhesive strength). The stretching ratio is, for example, about 1.5 to 5 times, preferably 2 to 4.5 times, and more preferably about 2.5 to 3.5 times in the longitudinal and transverse directions, respectively. If the draw ratio is too low, the film strength is insufficient, and if it is too high, the sheet thickness tends to be non-uniform.

  The release layer may have a laminated structure including a layer formed of an SPS-based resin (or a composition including an SPS-based resin) on the surface, for example, a plurality of different layers including an SPS-based resin. It may be a laminated structure formed (for example, a laminate of a layer formed of an SPS resin and a layer formed of an SPS resin and an antiblocking agent), and a layer containing an SPS resin and an SPS It may be a laminate with other layers not containing a resin. In particular, when the release layer is an unstretched film, it is preferably combined with another layer. For example, a laminate in which a release layer is formed on both sides of an intermediate layer formed of rubber or elastomer, or a patent document The laminated body in which the release layer was formed on both surfaces of the soft film described in 4 may be sufficient.

  The average thickness of the release layer is, for example, about 0.1 to 100 μm, preferably about 0.3 to 80 μm, and more preferably about 0.5 to 50 μm. In particular, when the release layer is a coating film, it may be thin, for example, 0.1 to 5 μm, preferably 0.5 to 3 μm, and more preferably about 0.8 to 2 μm. When the release layer is thin, the handleability is excellent, and it is suitable for a roll-to-roll method and the economic efficiency is improved.

(B) Substrate layer The SPS resin is known as a resin having high crystallinity and generally high heat resistance. However, when the MEA of a fuel cell is manufactured by a roll-to-roll method, Since the tension is loaded in addition to the heat treatment in the manufacturing process, the electrolyte film or electrode film and the release film are easily peeled off due to the elongation of the SPS resin. On the other hand, in this invention, such a peeling phenomenon can be suppressed by laminating | stacking with a specific base material layer. That is, the release film can improve the dimensional stability of the release film in the production process of the fuel cell, and can suppress the elongation even when tension is applied in the roll-to-roll method. Even if it is exposed to a high temperature such as by thermocompression bonding, a base layer having a specific elastic modulus and at least one surface of this base layer (usually, A release layer is formed on one surface).

  The base material layer is preferably a base material layer having high heat resistance and high dimensional stability, and may be formed of a synthetic resin having an elastic modulus at 150 ° C. of 100 MPa or more. The elastic modulus may be, for example, about 100 to 1000 MPa, preferably about 150 to 1000 MPa, more preferably about 200 to 1000 MPa (particularly about 250 to 1000 MPa). When the elastic modulus is too small, the dimensional stability is lowered, and peeling from the electrolyte membrane and the electrode membrane occurs in the production by the roll-to-roll method, and the productivity of the fuel cell is lowered.

As such a synthetic resin, for example, various thermoplastic resins and thermosetting resins can be used. From the viewpoint of flexibility that can be produced by a roll-to-roll method, a thermoplastic resin (polypropylene resin, cyclic resin) can be used. Polyolefins, polyesters, polyamides, polyimides, polycarbonates, polyphenylene ethers, polyphenylene sulfides, cellulose esters, etc.) are preferred, and polyesters are particularly preferred from the viewpoint of excellent balance between heat resistance and flexibility. Furthermore, as the polyester, poly C _2-4 alkylene arylate resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) can be preferably used.

  When the release layer is thin (particularly when manufactured by coating), the uneven shape on the surface of the base material layer is easily followed by the release layer, and thus the surface of the base material layer also has appropriate surface smoothness. preferable. The center line average roughness Ra of the surface of the base material layer can be selected from a range of about 1 to 50 nm, and is, for example, about 10 to 40 nm, preferably 15 to 35 nm, and more preferably 20 to 30 nm (particularly 20 to 25 nm). If Ra is too small, the adhesiveness between the base material layer and the release layer is lowered, and it is difficult to use for production in a roll-to-roll method. On the other hand, if Ra is too large, the release layer Surface smoothness decreases.

  The base material layer may also be formed of a stretched film from the viewpoint of improving the film strength. The stretching may be uniaxial stretching, but biaxial stretching is preferred from the viewpoint that the film strength can be improved. The stretching ratio may be, for example, 1.5 times or more (for example, 1.5 to 6 times), preferably 2 to 5 times, more preferably about 3 to 4 times, in the longitudinal and transverse directions, respectively. It is. If the draw ratio is too low, the film strength tends to be insufficient.

  The average thickness of a base material layer is 1-300 micrometers, for example, Preferably it is 5-200 micrometers, More preferably, it is about 10-100 micrometers (especially 20-80 micrometers). If the thickness of the base material layer is too large, production by the roll-to-roll method becomes difficult, and if it is too thin, the dimensional stability is lowered.

  The thickness ratio between the release layer and the base material layer is, for example, release layer / base material layer = 5/1 to 1/10, preferably 3/1 to 1/5, more preferably 2/1 to 1 /. It is about 3 (particularly 1/1 to 1/2).

  As a method for producing the release film, a conventional method can be used. When the release film is formed of a single release layer, for example, a film obtained by extrusion molding may be stretched. In the case of a laminated body, for example, a method such as coating, coextrusion or extrusion lamination, thermocompression bonding, or the like may be used, and lamination may be performed via an adhesive or an adhesive.

  Among these, the release layer is preferably a coating from the viewpoint of the smoothness of the release layer. As the coating method, conventional methods such as roll coater, air knife coater, blade coater, rod coater, reverse coater, bar coater, comma coater, die coater, gravure coater, screen coater method, spray method, spinner method and the like can be mentioned. It is done. Of these methods, the blade coater method, the bar coater method and the like are widely used.

  In the case of producing a release film (particularly a release layer) by coating, examples of the solvent for dissolving the SPS resin include aromatic hydrocarbons (benzene, toluene, xylene, etc.), alicyclic hydrocarbons (cyclohexane, cyclohexanone). , Cyclohexene, etc.), halogenated hydrocarbons (dichloromethane, dichloroethane, etc.), cyclic amides (N-methyl-2-pyrrolidone, etc.), cyclic ethers (dioxane, etc.) and the like. These solvents may be used alone or in combination.

  The release layer formed by coating may be laminated | stacked with the base material layer through the contact bonding layer. The adhesive layer may be a conventional adhesive (for example, urethane adhesive, acrylic adhesive, polyester adhesive, polyamide adhesive, etc.) or pressure sensitive adhesive (for example, rubber pressure sensitive adhesive, acrylic pressure sensitive adhesive, olefin based adhesive). Adhesives, silicone adhesives, etc.) can be used. The average thickness of the adhesive layer is, for example, about 1 to 40 μm, preferably 1 to 20 μm, and more preferably about 1 to 10 μm (particularly 1 to 5 μm).

(Layer containing ion exchange resin)
As the ion exchange resin, a conventional ion exchange resin used in a fuel cell can be used. Among them, a cation exchange resin such as a strong acid cation exchange resin or a weak acid cation exchange resin is preferable, and a sulfonic acid group is used. Particularly preferred are ion exchange resins having a sulfonic acid group (for example, a fluororesin having a sulfonic acid group, a sulfonated product of crosslinked polystyrene). In particular, in a polymer electrolyte fuel cell, a fluororesin having a sulfonic acid group (or —CF ₂ CF ₂ SO ₃ H group) in the side chain, for example, [2- (2-sulfotetrafluoroethoxy) hexafluoropropoxy] A block copolymer of trifluoroethylene and tetrafluoroethylene is preferably used.

  The ion exchange capacity of the ion exchange resin may be 0.1 meq / g or more, for example, 0.1 to 2.0 meq / g, preferably 0.2 to 1.8 meq / g, more preferably 0.3. It may be about ~ 1.5 meq / g (particularly 0.5 to 1.5 meq / g).

  Examples of such ion exchange resins include “Registered trademark: Nafion” manufactured by DuPont, “Registered trademark: Flemion” manufactured by Asahi Glass Co., Ltd., and “Registered trademark: Aciplex manufactured by Asahi Kasei Corporation. ) "," Registered trademark: GORE-SELECT "manufactured by Japan Gore-Tex Co., Ltd. can be used. In addition, as an ion exchange resin, you may use the ion exchange resin etc. which are described in Unexamined-Japanese-Patent No. 2010-234570.

  The layer containing the ion exchange resin may be an electrolyte membrane formed of the ion exchange resin, an electrode membrane containing the ion exchange resin and catalyst particles.

  In the electrode film, the catalyst particles contain a metal component having a catalytic action (in particular, a noble metal such as platinum or an alloy containing a noble metal). Usually, the electrode film for cathode electrode contains platinum, and the electrode film for anode electrode contains platinum. -Including ruthenium alloys. Furthermore, the catalyst particles are usually used as composite particles in which the metal component is supported on a conductive material (carbon material such as carbon black). In the electrode film, the ratio of the ion exchange resin is, for example, about 5 to 100 parts by weight, preferably about 10 to 80 parts by weight, and more preferably about 20 to 50 parts by weight with respect to 100 parts by weight of the catalyst particles.

  The average thickness of the electrolyte membrane is, for example, about 1 to 500 μm, preferably 5 to 300 μm, and more preferably about 10 to 200 μm.

  The average thickness of the electrode film is, for example, about 1 to 100 μm, preferably 5 to 80 μm, and more preferably about 10 to 50 μm.

[Manufacturing method of laminate and membrane electrode assembly]
The manufacturing method of the laminated body of this invention includes the lamination process which laminates | stacks the layer containing an ion exchange resin on a release film.

  In the laminating step, an electrolyte membrane and / or an electrode membrane may be formed on the release film by coating. For example, the electrolyte membrane is laminated on the first release film by coating, A laminate having an electrolyte membrane laminated thereon is manufactured, and an electrode film is laminated on the second release film by coating, and a laminate in which the electrode film is laminated on the release film is produced. Also good.

  In order to form the electrolyte membrane and the electrode membrane by coating (or casting), the electrolyte membrane and the electrode membrane are coated in a state in which an ion exchange resin (and catalyst particles) is dissolved in a solvent.

Examples of the solvent include water, alcohols (C _1-4 alkanols such as methanol, ethanol, isopropanol, and 1-butanol), ketones (acetone, methyl ethyl ketone, etc.), ethers (dioxane, tetrahydrofuran, etc.), and sulfoxides. (Such as dimethyl sulfoxide). These solvents can be used alone or in combination of two or more. Among these solvents, water or a mixed solvent of water and C _1-4 alkanol is generally used from the viewpoint of handleability. The concentration of the solute (ion exchange resin, catalyst particles) in the solution is, for example, about 1 to 80% by weight, preferably about 5 to 60% by weight, and more preferably about 10 to 40% by weight.

  As a coating method, a conventional method described in the section of the release layer can be used, and a blade coater method, a bar coater method and the like are generally used.

  After coating the solution containing the ion exchange resin (and catalyst particles), the solvent may be evaporated by heating and drying. The drying temperature may be 50 ° C. or more, for example, about 80 to 200 ° C. (especially 100 to 150 ° C.) for the electrolyte membrane, and 50 to 150 ° C. (particularly 60 to 120 ° C.) for the electrode membrane. )

  In this invention, since the said release film is excellent in a softness | flexibility, such a lamination process can be performed by a roll-to-roll system, and productivity can be improved. Furthermore, since a release film in which a release layer and a base material layer are combined has excellent dimensional stability, the release film is restrained from being stretched by tension even in the roll-to-roll method. Therefore, the layer containing the ion exchange resin can be wound up in a roll shape without peeling off, and productivity can be improved.

  The laminate obtained in the laminating step is subjected to an adhesion step. In the adhesion step, the membrane electrode assembly (MEA) is prepared by bringing the electrolyte membrane and the electrode membrane laminated on the first and second release films into close contact with each other.

  The adhesion between the electrolyte membrane and the electrode membrane is usually brought about by thermocompression bonding. The heating temperature is, for example, about 80 to 200 ° C, preferably about 100 to 180 ° C, and more preferably about 110 to 150 ° C. The pressure is, for example, about 0.1 to 20 MPa, preferably about 0.5 to 15 MPa, and more preferably about 1 to 10 MPa.

  The complex adhered in the adhesion step (laminated body in which the electrolyte layer and the electrode film are in close contact) is subjected to a separation step of peeling the release film from the layer containing the ion exchange resin (electrolyte film and / or electrode film), A membrane electrode assembly of a polymer electrolyte fuel cell is obtained. In the present invention, even a laminate that has undergone the drying process or thermocompression treatment described above has an appropriate peel strength, so that the release film and the layer containing the ion exchange resin do not peel in the lamination process or the adhesion process. In the peeling step, the release film can be easily peeled off and workability can be improved.

  The peel strength between the release film and the layer containing the ion exchange resin (particularly, the peel strength of the laminate in the peeling step) is, for example, 0.1 to 10 mN / mm, preferably 0.5 to 8 mN / mm, Preferably it is about 1-7 mN / mm (especially 2-6 mN / mm). If the peel strength is too high, the peeling work becomes difficult, and if it is too low, workability in the laminating step and the adhesion step is lowered.

  In this specification, the peel strength can be measured by a method in which the film is allowed to stand at 23 ° C. and 50% RH for 1 hour or longer and then peeled by 180 ° under the condition of 300 mm / min.

  Further, with respect to the electrolyte membrane from which the first release film has been peeled off, an electrode film (the second release film is used for the anode electrode) is further formed on the third release film in the same manner as in the adhesion step and the peeling step. In the case of an electrode film, the electrode film of the laminate in which the cathode electrode film) is laminated is adhered and peeled off, and a fuel gas supply layer and an air supply layer are laminated on each electrode film by a conventional method. By doing so, a membrane electrode assembly (MEA) is obtained.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The peelability of the release films obtained in Examples and Comparative Examples was evaluated by the following method.

[Center line average roughness Ra]
In accordance with JIS B0601 (2001), the roughness of the release layer surface of the film was measured using a non-contact surface shape measurement system (“VertScan 2.0” manufactured by Ryoka System Co., Ltd.), and the number of measurements N = 5 The average value of was used.

[Peelability]
The laminates of the release films and ion exchange resin layers obtained in the examples and comparative examples were allowed to stand at 20 ° C. and 50 RH% for 1 hour or longer, then cut to 150 mm × 15 mm size, and cellophane on the ion exchange membrane. A tape (“CT405AP-15” manufactured by Nichiban Co., Ltd.) was attached, and 180 ° peeling was performed at 300 mm / min.

Example 1
(Manufacture of release film)
A biaxially stretched polyethylene terephthalate (PET) film (“Lumirror T60” manufactured by Toray Industries, Inc., thickness 38 μm) was used as the base layer of the release film, and a biaxially stretched SPS resin film (Kurabo ( These were bonded together with an adhesive for dry lamination (“TM569 / CAT-RT37” manufactured by Toyo Morton Co., Ltd.) using “Eudis” (manufactured by Co., Ltd.) and a release film was prepared.

(Manufacture of laminates)
On the obtained release film, an ion exchange resin solution (“Nafion (registered trademark) DE2020CS type manufactured by DuPont, water-alcohol dispersion of ion exchange resin, solid content concentration 20% by weight)” was prepared, and a Meyer bar The solution was cast on the mold release film using an adhesive, and the coating film was dried in an oven at 100 ° C. to form an ion exchange resin layer (thickness 5 μm). Then, heat treatment was performed for 30 minutes to produce a laminate.

Example 2
(Manufacturing of SPS)
Into a reaction vessel substituted with an inert gas, 600 ml of toluene, 120 mmol of methylaluminoxane, and 0.6 mmol of tetraethoxytitanium were charged, and then 600 ml of styrene was added and a polymerization reaction was performed at 50 ° C. for 2 hours. After completion of the reaction, the reaction was stopped with hydrochloric acid and methanol, and the produced polymer was filtered off and dried to obtain 100 g of SPS having a number average molecular weight of 25000.

(Manufacture of release film)
1 part by weight of the obtained SPS was dissolved in 9 parts by weight of cyclohexanone to prepare a coating solution. A biaxially stretched PET film (“Emblet S50” manufactured by Unitika Ltd., thickness 50 μm) was used as a substrate, and the coating solution was coated by the Mayer bar coating method, dried at 120 ° C. for 3 minutes and separated. A mold layer (thickness 1 μm) was formed. On the other hand, a biaxially stretched PET film (Lumirror T60) is separately prepared as a base material layer of the release film, and the release layer and the base material layer are combined with an adhesive for dry lamination (“TM569 / CAT made by Toyo Morton Co., Ltd.). -RT37 ") was used for bonding with the adhesive thickness (5 μm), and the biaxially stretched PET film on the side opposite to the adhesive layer was peeled off to prepare a release film.

(Manufacture of laminates)
A laminate was produced in the same manner as in Example 1.

Example 3
Except for changing the base layer of the release film to a biaxially stretched polyethylene naphthalate film (“Teonex Q51, surface-treated product” manufactured by Teijin DuPont Films Ltd., thickness 50 μm), the same method as in Example 2, A laminate was produced.

Comparative Example 1
Except for changing the release film to a release film in which the release layer is formed of a melamine resin (“T9004” manufactured by Daicel Value Coating Co., Ltd., base material layer: PET film), the same as in Example 1 Thus, a laminate was produced.

Comparative Example 2
A laminate was produced in the same manner as in Example 1 except that the release film was changed to a PET film (“Emblet S50” manufactured by Unitika Ltd.).

Comparative Example 3
Except for changing the release film to a release film (“TR6-38” manufactured by Unitika Ltd., substrate layer: PET film) in which the release layer is formed of an olefin resin, the same procedure as in Example 1 was performed. Thus, a laminate was produced.

Comparative Example 4
A laminate was produced in the same manner as in Example 1 except that the release film was changed to a polyester release film (“TN200” manufactured by Toyobo Co., Ltd.).

  Table 1 shows the results of evaluating the peelability of the electrolyte membranes obtained in Examples and Comparative Examples.

  As is clear from the results in Table 1, the release films of the examples have moderate peelability, whereas the release films of the comparative examples have high peel strength and lower productivity.

  The laminate of the present invention is used for producing a polymer electrolyte fuel cell.

Claims (8)

A laminate formed of a release film and a layer laminated on the release film and containing an ion exchange resin,
The release film is formed of a base material layer formed of a synthetic resin having an elastic modulus of 100 to 1000 MPa at 150 ° C., and formed of at least one surface of the base material layer and formed of a syndiotactic polystyrene resin. A laminate comprising the release layer, and the layer containing the ion exchange resin being an electrolyte membrane, an electrode membrane, or a membrane electrode assembly of a polymer electrolyte fuel cell.   The laminate according to claim 1, wherein the center line average roughness Ra of the release layer surface is 1 to 50 nm.   The laminate according to claim 1 or 2, wherein the base material layer is a stretched film formed of polyester.   The laminate according to any one of claims 1 to 3, wherein the release film is a film formed by coating.   The laminate according to any one of claims 1 to 4, wherein the ion exchange resin is a fluororesin having a sulfonic acid group in the side chain.   The laminate according to any one of claims 1 to 5, which is produced by a roll-to-roll method.   The manufacturing method of the laminated body in any one of Claims 1-6 including the lamination process which laminates | stacks the layer containing an ion exchange resin on a release film.   The manufacturing method of the membrane electrode assembly of a polymer electrolyte fuel cell including the peeling process which peels a release film from the laminated body in any one of Claims 1-6.