JP7133893B2 - Release film for molding polymer electrolyte fuel cell components - Google Patents

Description

TECHNICAL FIELD The present invention relates to a release film suitably used for producing a membrane-electrode assembly (MEA), which is a constituent member of polymer electrolyte fuel cells.

A membrane-electrode assembly (MEA), which is a constituent member of a polymer electrolyte fuel cell (PEFC), has a structure in which catalyst layers are laminated on both sides of a polymer electrolyte membrane. A polymer electrolyte membrane uses a proton-conducting resin, and a polymer having a sulfonium group in its side chain. As an example, a sulfonic acid-based resin composed of strongly acidic perfluorocarbon (-CF2-) is used (eg, Nafion (registered trademark) manufactured by DuPont). The catalyst layer has a structure in which platinum-supported carbon is dispersed in a binder (proton conductive resin).

As an example of a method for manufacturing these MEAs, a method has been proposed in which a polymer electrolyte membrane and a catalyst layer are formed on separate support films by a casting method, and the two are joined by thermocompression bonding at a high temperature of 150° C. or higher. .

As the support film, a fluororesin sheet such as PTFE (polytetrafluoroethylene) has been used from the viewpoint of heat resistance and releasability, but in recent years, a method of using a polyester film has been proposed for the purpose of cost reduction. (See Patent Documents 1 to 3, for example).

In recent years, the ratio of platinum-carrying carbon in the catalyst layer has been increasing in order to improve the functionality of the catalyst layer. However, when the ratio of platinum-supported carbon in the catalyst layer is higher than that of the binder polymer electrolyte resin, the film strength of the catalyst layer as a whole decreases, and when the catalyst layer formed on the support film is transferred to the polymer electrolyte membrane, it cannot be supported. There is a problem that the catalyst layer tends to remain on the film. If the transferability of the catalyst layer is insufficient, the performance of the fuel cell is lowered and the production cost is increased. For example, even if the films described in Patent Documents 1 to 3 were used, transferability was not sufficient.

Japanese Patent Application Laid-Open No. 2003-285396 JP 2010-234570 A JP 2014-154273 A

In view of the above-mentioned special circumstances of MEA, which is a constituent member of a polymer electrolyte fuel cell, it is an object of the present invention to provide a release film for molding a polymer electrolyte fuel cell member, which has good transferability even with a catalyst layer having a weak film strength. is.

That is, the present invention consists of the following configurations.
1. A release film in which an antistatic layer and a release layer are laminated in this order on at least one side of a polyester film, the heat shrinkage at 160 ° C. is 0.8% or less, and the surface specific resistance of the release film surface is A release film for molding a polymer electrolyte fuel cell, characterized by having a resistance of 1×10 ¹¹ Ω/□ or less.
2. 1. The release film for molding a polymer electrolyte fuel cell as described in 1 above, wherein the polyester film is a polyethylene terephthalate film.
3. 2. The polymer electrolyte fuel cell molding release material according to the above 1st or 2nd, wherein the total value of the polar component and the hydrogen bond component of the surface free energy of the surface of the release layer is 8 mJ/m ² or less. mold film.
4. 3. The release film for molding a polymer electrolyte fuel cell according to any one of the above 1 to 3, wherein at least one of the resins contained in the release layer has a glass transition temperature of 130° C. or higher.
5. 4. The release film for molding a polymer electrolyte fuel cell according to any one of the above 1 to 4, wherein the resin contained in the release layer is a cyclic polyolefin resin.
6. 5. The release film for molding a polymer electrolyte fuel cell according to any one of the above 1 to 5, wherein the release layer contains nanoparticles .

According to the present invention, by providing an antistatic layer between the polyester film and the release layer, it is possible to reduce the electrostatic interaction between the release layer and the molding member such as the catalyst layer during transfer. It is possible to provide a release film for molding polymer electrolyte fuel cell members, which has good transferability even with a catalyst layer having a weak film strength.

The present invention will be described in detail below.

(polyester film)
The polyester film used as a substrate in the present invention is a film mainly composed of a polyester resin. Here, "a film mainly composed of a polyester resin" is a film formed from a resin composition containing 50% by mass or more of a polyester resin, and when blended with another polymer, the polyester resin is 50% by mass. % or more, and when other monomers are copolymerized, it means that 50 mol % or more of repeating structural units of polyester are contained. Preferably, the polyester film contains 90% by mass or more, more preferably 95% by mass or more, and still more preferably 100% by mass of the polyester resin in the resin composition constituting the film.

As the polyester resin, the material is not particularly limited, but a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component, or a blend resin thereof can be used. Examples of dicarboxylic acid components include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenyl Carboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydro isophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid , dimer acid, sebacic acid, suberic acid, dodecadicarboxylic acid and the like.

Examples of the diol component constituting the polyester resin include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3- propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone and the like.

The dicarboxylic acid component and the diol component that constitute the polyester resin may be used alone or in combination of two or more. Further, other acid components such as trimellitic acid and other hydroxyl group components such as trimethylolpropane may be appropriately added.

Specific examples of polyester resins include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among these, polyethylene terephthalate is preferred from the viewpoint of the balance between physical properties and cost.

In order to improve handling properties such as slipperiness and winding properties of the polyester film, the film may contain inert particles.

Although the thickness of the polyester film is not particularly limited in the present invention, it is preferably in the range of 12 to 100 μm. 12 to 75 μm is more preferable, and 16 to 50 μm is even more preferable. When the thickness is 12 μm or more, there is no possibility that wrinkles are generated when the catalyst layer is molded and transferred, and when the thickness is 100 μm or less, it is advantageous in terms of cost.

The polyester film used in the present invention preferably has a small thermal shrinkage rate in order to suppress the thermal shrinkage rate of the release film to be produced. For example, the shrinkage rate when treated at 160 ° C. for 30 minutes is preferably 0.8% or less, more preferably 0.6%, by the same measurement method as the heat shrinkage rate of the release film described later. or less, more preferably 0.4% or less, and particularly preferably 0.3% or less. However, the small thermal shrinkage of the release film of the present invention is not simply due to the small thermal shrinkage of the polyester film that serves as the base film. It is something that can be achieved including

The area average surface roughness (Sa) of the surface of the polyester film used in the present invention on which the release layer is laminated is preferably in the range of 1 to 50 nm, more preferably 2 to 30 nm. The maximum protrusion height (P) of the surface of the polyester film used in the present invention on which the release layer is laminated is preferably 2 μm or less, more preferably 1.5 μm or less. When Sa is 50 nm or less and P is 2 μm or less, cracks and pinholes are not likely to occur in the catalyst layer when the catalyst layer is transferred, which is preferable.

The polyester film that serves as the substrate may be a single layer or a laminate of two or more layers. In addition, if necessary, various additives can be incorporated into the film as long as the effects of the present invention are achieved. Examples of additives include antioxidants, light stabilizers, anti-gelling agents, organic wetting agents, antistatic agents, ultraviolet absorbers, and surfactants. When the film has a laminated structure, it is also preferable to contain additives depending on the function of each layer, if necessary.

The polyester film can be obtained, for example, by melt-extrusion of the above polyester resin into a film, cooling and solidification with a casting drum to form a film, and the like. As the polyester film of the present invention, both a non-stretched film and a stretched film can be used, but a stretched film is preferable from the viewpoint of durability such as mechanical strength and chemical resistance. When the polyester film is a stretched film, the stretching method is not particularly limited, and a vertical uniaxial stretching method, a horizontal uniaxial stretching method, a vertical and horizontal successive biaxial stretching method, a vertical and horizontal simultaneous biaxial stretching method, etc. can be employed.

The surface layer of the polyester film may be subjected to surface treatments such as an anchor coat layer, corona treatment, plasma treatment and flame treatment in order to improve adhesion with the adhesion improving layer. When providing an anchor coat layer, in-line coating is preferable from the viewpoint of cost.

In order to suppress the thermal shrinkage rate of the substrate polyester film used in the present invention, the annealing treatment may be performed during film formation (in-line) of the polyester film, or the annealing treatment may be performed off-line.

Known methods can be used to perform the annealing treatment in-line. For example, as a method for reducing the heat shrinkage of the polyester film in the lateral stretching process, the end of the film is cut off from the clip behind the heat setting zone for crystallization, the take-up speed of the film behind it is adjusted, and the film Thermal relaxation treatment can be performed by lowering the tension in the running direction.

When in-line annealing is performed in the lateral stretching step, the film temperature when cutting off the film ends is preferably 140° C. or higher, more preferably 150° C. or higher, and more preferably 160° C. or higher. However, if the temperature is too high, the planarity may be impaired, so it is preferable to set the temperature to about 230° C. or less.

When annealing treatment is performed off-line, it can be performed at the same time as the release layer to be described later is applied. Detailed process conditions will be described later.

(Antistatic layer)
It is necessary to laminate an antistatic layer on the release film of the present invention. The present inventors have found that lamination of an antistatic layer can reduce the electrostatic interaction between the release layer and the transferred material, thereby improving transferability. In the present invention, the antistatic layer is preferably provided between the polyester film and the release layer. When the antistatic layer is laminated on the side of the polyester film opposite to the side on which the release layer is laminated, the conductivity of the release layer surface is poor and the effect is small, which is not preferable. Addition of a conductive additive to the release layer is also not preferable because there is a concern that the additive may migrate to the catalyst layer.

The means for laminating the antistatic layer is not particularly limited, and known methods such as a coating method, a vacuum deposition method, and lamination can be used. is preferable from the viewpoint of

As the antistatic agent, a polymer or surfactant utilizing ion conduction such as a cationic compound, a silicon oxide film, a conductive metal compound, a π-electron conjugated conductive polymer, or the like can be used. From the viewpoint of antistatic properties under humidity, it is preferable to use a π-electron conjugated conductive polymer. In addition, since the π-electron conjugated conductive polymer can maintain a high level of antistatic performance without depending on the moisture in the air, a release layer was laminated on the antistatic layer of the present invention. High antistatic performance can be maintained even afterward.

Examples of π-electron conjugated conductive polymers include aniline polymers containing aniline or its derivatives as structural units, pyrrole polymers containing pyrrole or its derivatives as structural units, and acetylene polymers containing acetylene or its derivatives as structural units. Polymers, thiophene-based polymers containing thiophene or a derivative thereof as a structural unit, and the like can be mentioned. In order to obtain high transparency, the π-electron conjugated conductive polymer preferably does not have a nitrogen atom. Among them, a thiophene-based polymer containing thiophene or its derivative as a structural unit is excellent in terms of transparency. are preferred, and polyalkylenedioxythiophenes are particularly preferred. Polyalkylenedioxythiophenes include polyethylenedioxythiophene, polypropylenedioxythiophene, poly(ethylene/propylene)dioxythiophene, and the like.

In order to further improve the antistatic properties of the thiophene-based polymer containing thiophene or a derivative thereof as a structural unit, a doping agent is added, for example, to 100 parts by mass of the polymer containing thiophene or a derivative thereof as a structural unit. 0.1 parts by mass or more and 500 parts by mass or less can be blended. If the amount is too small, the electron transfer becomes difficult, resulting in a problem of deterioration in antistatic performance. Examples of the doping agent include LiCl, R _1-30 COOLi (R _1-30 : a saturated hydrocarbon group having 1 to 30 carbon atoms), R _1-30 SO ₃ Li, R _1-30 COONa, R _{1-30 SO3Na , R1-30COOK , R1-30SO3K} , Tetraethylammonium, _I2 , _{BF3Na , BF4Na} , HClO4, _CF3SO3H , FeCl3 _, Tetracyanoquinoline (TCNQ) , Na ₂ B ₁₀ Cl ₁₀ , phthalocyanine, porphyrin, glutamic acid, alkyl sulfonate, polystyrene sulfonate Na (K, Li) salt, styrene/styrene sulfonate Na (K, Li) salt copolymer, polystyrene sulfonate anion , styrenesulfonic acid/styrenesulfonic acid anion copolymer, and the like.

The antistatic layer of the invention may contain a binder component. Adhesion with a polyester film can be improved by including a binder component. The binder resin is not particularly limited, but known resins can be used. For example, polyester resin, polyurethane resin, polyacrylate resin, polyvinyl formal resin, polyvinyl butyral resin, epoxy resin, polyamide Solvent or water-soluble resins such as resins, polystyrene resins, styrene-acrylic copolymer resins, chlorinated polypropylene resins, polyether resins, and silicon oxide films can be used.

In the present invention, the antistatic agent contained in the antistatic layer is preferably contained in an amount of 20% by mass or more, more preferably 30% by mass or more. In the case of using a π-electron conjugated conductive polymer as an antistatic agent, when using the doping agent, the content of the π-electron conjugated conductive polymer in the antistatic layer specified in the present application is It is the total amount of the conductive polymer and the doping agent.

A surfactant may be used in the antistatic layer in the invention to improve the appearance. Examples of surfactants include nonionic surfactants such as polyoxyethylene octylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, and fluoroalkylcarboxylic acids, perfluoroalkylcarboxylic acids, perfluoroalkylbenzenesulfones. Fluorinated surfactants such as acids, perfluoroalkyl quaternary ammonium, and perfluoroalkyl polyoxyethylene ethanol can be used.

The antistatic layer may contain a lubricant, a dye, an ultraviolet absorber, a cross-linking agent, a silane coupling agent, and the like, if necessary, as long as the object of the present invention is not impaired.

Methods for coating and laminating an antistatic layer on the substrate film surface include a gravure roll coating method, a reverse roll coating method, a knife coater method, a dip coating method, a spin coating method and the like, and a coating method suitable for the conductive composition. is not particularly limited. Moreover, it can be provided by an in-line coating method in which a coating layer is provided in the film production process, or an off-line coating method in which a coating layer is provided after film production.

The drying temperature for forming the antistatic layer is usually 60° C. or higher and 150° C. or lower, preferably 90° C. or higher and 140° C. or lower. When this temperature is 60° C. or higher, the treatment can be performed in a short period of time, which is preferable from the viewpoint of improving productivity. On the other hand, when this temperature is 150° C. or less, the flatness of the film is maintained, which is preferable.

The film thickness of the antistatic layer of the invention is preferably 0.005 μm or more and 5 μm or less. It is more preferably 0.01 μm or more and 1 μm or less, and still more preferably 0.01 μm or more and 0.2 μm or less. When the film thickness of the antistatic layer is 0.005 μm or more, an antistatic effect can be obtained, which is preferable. On the other hand, when it is 5 μm or less, there is no fear of impairing the releasability, which is preferable.

(release layer)
In the present invention, it is necessary to laminate a release layer on at least one side of the polyester film. Although the resin used for the release layer is not particularly limited, it is preferable to provide a release layer containing the resin (A) described below.

The resin (A) contained in the release layer of the release film of the present invention is preferably selected from olefin resins and fluorine resins. Moreover, it is preferable that these release layers are provided on the polyester film by coating with a coating liquid containing the resin (A) as described above.

Examples of the olefinic resin used for the release layer include copolymerized polyethylene, cyclic polyolefin, polymethylpentene, and the like. From the viewpoint of heat resistance, cyclic polyolefin, polymethylpentene, and the like are preferably used. By using the above resin for the release layer, even when heat-treated at 150° C. or higher, it is possible to maintain releasability from binders such as Nafion used for electrolyte membranes, which is preferable.

Copolymerized polyethylene can be obtained by copolymerizing polyethylene with α-olefins such as propylene, n-butene, n-pentene and n-hexene. Adhesion to the polyester film can be improved by introducing a functional group such as a hydroxyl group or a carboxyl group into these resins and cross-linking them with a cross-linking agent.

A cyclic polyolefin is a resin containing a cyclic olefin as a polymer component. Cyclic olefins are polymerizable cyclic olefins having an ethylenic double bond in the ring, and can be classified into monocyclic olefins, bicyclic olefins, tricyclic or higher polycyclic olefins, and the like. Examples of monocyclic olefins include cyclic C4-12 cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and the like. Examples of bicyclic olefins include 2-norbornene; alkyl groups such as 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene (C1-4 alkyl group) norbornenes; norbornenes having alkenyl groups such as 5-ethylidene-2-norbornene; 5-methoxycarbonyl-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene and the like norbornenes having an alkoxycarbonyl group; norbornenes having a cyano group such as 5-cyano-2-norbornene; 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene having an aryl group norbornenes; octaline; octaline having an alkyl group such as 6-ethyl-octahydronaphthalene;

Examples of polycyclic olefins include dicyclopentadiene; 2,3-dihydrodicyclopentadiene, methanooctahydrofluorene, dimethanooctahydronaphthalene, dimethanocyclopentadienonaphthalene, methanooctahydrocyclopentadienonaphthalene, etc. derivatives having substituents such as 6-ethyl-octahydronaphthalene; adducts of cyclopentadiene and tetrahydroindene and the like; trimers and tetramers of cyclopentadiene;

These cyclic olefins can be used alone or in combination of two or more. Among these cyclic olefins, it is preferable to use a bicyclic olefin because both flexibility and releasability can be achieved. The ratio of bicyclic olefins (especially norbornenes) to the total cyclic olefins may be 10 mol% or more, for example, 30 mol% or more, preferably 50 mol% or more, more preferably 80 mol% or more. , bicyclic olefin alone (100 mol %). In particular, when the proportion of tricyclic or higher polycyclic olefins becomes large, it is not preferable because it becomes difficult to use for roll-to-roll production.

Specific examples of bicyclic olefins include norbornene (2-norbornene, optionally having substituents), octaline (octahydronaphthalene, optionally having substituents), and the like. Examples of the substituents include alkyl groups, alkenyl groups, aryl groups, hydroxyl groups, alkoxy groups, carboxyl groups, alkoxycarbonyl groups, acyl groups, cyano groups, amide groups, and halogen atoms. These substituents may be used alone or in combination of two or more. Among these bicyclic olefins, norbornenes such as norbornene and norbornene having an alkyl group (C1-4 alkyl group such as methyl group and ethyl group) are particularly preferred.

The cyclic polyolefin is preferably a cyclic olefin-chain olefin copolymer further containing a chain olefin as a polymerization component. By using the above copolymer, flexibility can be imparted and processing becomes easier.

Examples of chain olefins include chain C2 such as ethylene, propylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. -10 olefins and the like. These chain olefins can be used alone or in combination of two or more. Among these chain olefins, α-chain C2-8 olefins are preferred, and α-chain C2-4 olefins (especially ethylene) are more preferred.

The ratio (molar ratio) between the cyclic olefin and the chain olefin is, for example, cyclic olefin/chain olefin = 100/0 to 1/99, preferably 90/10 to 10/90, more preferably 70/30 to 20. /80. When the ratio of the cyclic olefin satisfies the above range, it is preferable in terms of heat resistance and peelability.

The cyclic polyolefin is also preferably a copolymer containing, as a polymer component, a cyclic olefin or chain olefin having an alkyl group of 3 to 10 carbon atoms in the side chain. By using these copolymers, heat resistance can be improved while maintaining flexibility.

Examples of alkyl groups having 3 to 10 carbon atoms include propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl, neopentyl, hexyl, heptyl and octyl. linear or branched alkyl groups such as groups, 2-ethylhexyl groups, nonyl groups and decanyl groups. These C3-10 alkyl groups can be used alone or in combination of two or more. Among these, a linear C4-9 alkyl group (eg, n-butyl group, n-hexyl group, n-octyl group, etc.) is preferred from the viewpoint of excellent balance between heat resistance, elasticity and toughness, and further A linear C4-8 alkyl group (especially a linear C5-7 alkyl group such as n-hexyl group) is preferred.

Chain olefins having a C3-10 alkyl group include, for example, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene , 1-undecene, 1-dodecene, and other α-chain C5-13 olefins. These chain olefins can be used alone or in combination of two or more. Among these chain olefins, α-chain C6-12 olefins are preferable, and α-chain C6-10 olefins (especially α-chain C7-9 olefins such as 1-octene) are more preferable. .

The cyclic olefin having a C3-10 alkyl group may be a cyclic olefin in which the cyclic olefin skeleton exemplified in the section of the cyclic olefin is substituted with a C3-10 alkyl group. Bicyclic olefins (especially norbornene) are preferred as the cyclic olefin skeleton. Preferred cyclic olefins having a C3-10 alkyl group include, for example, 5-propyl-2-norbornene, 5-butyl-2-norbornene, 5-pentyl-2-norbornene, 5-hexyl-2-norbornene, 5-octyl -2-norbornene, 5-decyl-2-norbornene, and other linear or branched C3-10 alkylnorbornenes. These cyclic olefins can be used alone or in combination of two or more. Among these cyclic olefins, linear C4-9 alkylnorbornenes are preferred, and linear C4-8 alkylnorbornenes (particularly linear C5-7 alkylnorbornenes such as 5-hexyl-2-norbornene) are more preferred. ).

The ratio (molar ratio) between the cyclic olefin unit and the linear or cyclic olefin unit (including an alkyl group having 3 to 10 carbon atoms) is, for example, the former/latter = 50/50 to 99/1, preferably 60/ It is about 40 to 95/5, more preferably about 70/30 to 90/10 (particularly about 75/25 to 90/10). If the proportion of the cyclic olefin unit (A) is too low, the heat resistance tends to be low, and if it is too high, the elasticity and toughness tend to be low.

Other copolymerizable monomers include, for example, vinyl ester-based monomers (e.g., vinyl acetate, vinyl propionate, etc.); diene-based monomers (e.g., butadiene, isoprene, etc.); Monomers [eg, (meth)acrylic acid, derivatives thereof ((meth)acrylic acid esters, etc.)] and the like can be exemplified. These other copolymerizable monomers may be used alone or in combination of two or more. The content of these other copolymerizable monomers is, for example, 5 mol % or less, preferably 1 mol % or less, relative to the entire cyclic polyolefin.

The cyclic polyolefin may be a resin obtained by addition polymerization, or may be a resin obtained by ring-opening polymerization (such as ring-opening metathesis polymerization). Also, the polymer obtained by ring-opening metathesis polymerization may be a hydrogenated resin. The cyclic polyolefin can be polymerized by conventional methods such as ring-opening metathesis polymerization using a metathesis polymerization catalyst, addition polymerization using a Ziegler-type catalyst, addition polymerization using a metallocene catalyst (generally, metathesis polymerization catalyst ring-opening metathesis polymerization) and the like can be used.

The glass transition temperature (Tg) of the cyclic polyolefin used in the present invention can be selected from the range of about 10 to 350°C. ~350°C. If the glass transition temperature is too low, the heat resistance is lowered, and if it is too high, roll-to-roll production becomes difficult.

The number average molecular weight of the cyclic polyolefin is, for example, 1000 to 200000, preferably 5000 to 200000, more preferably 10000 to 200000 (especially 30000 to 150000) in terms of polystyrene in gel permeation chromatography (GPC).

As a commercial product of cyclic polyolefin, TOPAS (registered trademark) (manufactured by Polyplastics Co., Ltd.) can be preferably used. Among the TOPAS series, TOPAS 6017S has a glass transition temperature (Tg) of 170° C. or higher, and is particularly preferable because deterioration of the release layer hardly occurs even with heat treatment at 150° C. or higher.

As a commercial product of cyclic polyolefin, there is also ARTON (registered trademark) (manufactured by JSR Corporation), which can be preferably used. Since the polar component of the surface free energy of the release layer is increased, TOPAS (registered trademark) may be superior in releasability.

The polymethylpentene resin used for the release layer in the present invention is a copolymer containing at least the structural unit A and the structural unit B. Structural unit A preferably contains a total of 50 mol% or more, more preferably 70 mol% or more, and 85 mol% or more of a resin derived from 4-methyl-1-pentene and/or 3-methyl-1-pentene. It is more preferable to include Each may be used alone or in combination.

Structural unit B is preferably composed of at least one olefin-derived resin selected from ethylene and α-olefins having 3 to 4 carbon atoms and is contained in an amount of 5 mol % or more. The upper limit of the content of the structural unit B is preferably 50 mol% or less, more preferably 30 mol% or less, and even more preferably 15 mol% or less.

Preferred examples of the α-olefin having 3 to 4 carbon atoms used in the structural unit B include 1-butene and propylene, but propylene is more desirable from the viewpoint of physical properties. α-olefins having 3 to 4 carbon atoms, ethylene, and the like may be used alone or in combination.

In addition to the structural unit A and the structural unit B, the polymethylpentene resin may have structural units of other polymerizable compounds. For example, vinyl compounds having a cyclic structure such as styrene, vinylcyclopentene, vinylcyclohexane, and vinylnorbornane; vinyl esters such as vinyl acetate; unsaturated organic acids such as methacrylic acid, acrylic acid and maleic anhydride, or derivatives thereof; butadiene, conjugated dienes such as isoprene and pentadiene; and non-conjugated polyenes such as 1,4-hexadiene, octadiene, cyclopentadiene, norbornene and norbornadiene.

The above-mentioned other polymerizable compound can be contained in a ratio of 10 mol % or less with respect to the total 100 mol % of the structural unit A and the structural unit B. More preferably, it is 5 mol % or less.

The polymethylpentene resin used in the present invention may be modified, and preferably has one or more functional groups such as an acid anhydride group, a hydroxyl group, an active hydrogen-containing group such as a carboxyl group, and an epoxy group. one of. By having these functional groups, it is possible to improve the adhesion to polyester resins such as polyethylene terephthalate and polyethylene naphthalate when used in combination with a cross-linking agent. These functional groups can be introduced by known methods. The amount of functional groups to be introduced is preferably 10 equivalents or less with respect to the polymethylpentene resin.

The polymethylpentene resin used in the present invention can be polymerized by a known method, and can be obtained by polymerization under a catalyst for olefin polymerization such as a metallocene catalyst.

Fluorine-based resins preferably used in the present invention include PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), PVF (polyvinyl fluoride), and the like. Copolymers, PFA (copolymer of tetrafluoroethylene (C ₂ F ₄ ) and perfluoroalkoxyethylene), FEP (copolymer of tetrafluoroethylene and hexafluoropropylene), ETFE (tetrafluoroethylene (- C ₂ F ₄ -) and ethylene (-C ₂ H ₄ -)). Also, an acrylate-modified fluorine-based resin can be added to a polyfunctional acrylate or the like and used.

The glass transition temperature (Tg) of the resin (A) used for the release layer of the release film of the present invention is preferably 130° C. or higher, more preferably 150° C. or higher, from the viewpoint of heat resistance. It is preferable that the glass transition temperature (Tg) of the resin (A) is high, and for example, it can be said to be about 350°C, and may be 300°C or lower. The material of the resin (A) is particularly preferably a cyclic polyolefin resin as described above.

The resin used for the release layer of the release film of the present invention may be of one type or a mixture of a plurality of resins. It is preferable that the release layer contains the resin (A), and in this case, the composition ratio of the resin (A) is preferably 50% by mass or more based on the total resin components of the release layer.

It is also preferred that the release layer of the present invention contains nanoparticles. By containing nanoparticles, the effect of improving the elastic modulus of the release layer and improving the transferability was observed. Although the materials of the nanoparticles used in the present invention are not particularly limited, they refer to particles having a primary particle size of 100 nm or less. It is more preferably 60 nm or less, still more preferably 30 nm or less, and most preferably 15 nm or less. Although the lower limit of the primary particle size is not particularly limited, it may be 1 nm or more, or 3 nm or more. The present inventors found that by containing nanoparticles in the release layer, the elastic modulus of the release layer is improved, and the peeling force when peeling off the catalyst layer and the electrolyte membrane molded on the release film is reduced, resulting in transferability. was found to improve. The release layer contains particles other than nanoparticles, additives described later, cross-linking agents, and other resins other than the release agent at a content that does not impair the effects of the present invention. It may be mixed at a content of less than 50% by mass of the layer solid content mass.

The method for measuring the primary particle size of the nanoparticles is to observe the particles in the cross section of the film after processing with a transmission electron microscope or scanning electron microscope, observe 100 particles that are not agglomerated, and use the average value. It was carried out by a method of using an average particle size.

The shape of the particles is not particularly limited as long as it satisfies the object of the present invention, and spherical particles and irregularly shaped non-spherical particles can be used. The particle diameter of amorphous particles can be calculated as a circle equivalent diameter. The circle-equivalent diameter is a value obtained by dividing the observed particle area by π, calculating the square root, and doubling the result.

The material of the nanoparticles contained in the release film of the present invention is not particularly limited, but inorganic particles such as silica, zirconium oxide, titanium oxide, alumina, kaolin, calcium carbonate, barium sulfate, carbon black, and crosslinked acrylic Examples include organic particles such as resins, crosslinked polystyrene resins, melamine resins, and crosslinked silicone resins. Among these, it is preferable to use silica and alumina.

The nanoparticles contained in the release film of the present invention are preferably contained in an amount of 20 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the resin contained in the release layer as a solid content. More preferably, it is 20 parts by mass or more and 100 parts by mass or less. When the amount of nanoparticles to be added is 20 parts by mass or more, the effect of improving the elastic modulus of the release layer can be obtained, and the effect of improving transferability can be obtained, which is preferable. On the other hand, when the content is 200 parts by mass or less, the haze of the film does not become too large, the appearance does not look dull, and there is no fear of nanoparticles coming off, which is preferable.

The release film of the present invention preferably has a haze of 10% or less. By setting the haze to 10% or less, the appearance inspection of the obtained release film can be facilitated. Although it can be said that the lower limit of haze is more preferable, the lower limit is currently about 0.2%.

The release layer may further contain known additives. Known additives include, for example, fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity modifiers, thickeners, agents, defoamers, UV absorbers, and the like may be included.

A cross-linking agent can also be used for the release layer in the present invention in addition to the above resins. As the cross-linking agent, isocyanate-based, carbodiimide-based, epoxy-based, melamine-based, metal chelate-based, and the like can be used. In the case where the resin used for the release layer has a reactive functional group, the use of a cross-linking agent in combination is preferable because the adhesiveness to the polyester film can be improved.

The film thickness of the release layer in the present invention is desirably 0.01 μm or more and 5 μm or less. More desirably, it is 0.02 μm or more and 1 μm or less. More preferably, it is 0.02 μm or more and 0.2 μm or less. A thickness of 0.01 μm or more is preferable because the releasability can be obtained. On the other hand, when the thickness is 5 μm or less, there is no risk of curling of the film, and it is advantageous in terms of cost, which is preferable.

The surface free energy γs of the release layer of the present invention is not particularly limited, but the sum of the polar component γsp and the hydrogen bonding component γsh of the surface free energy is preferably 8 mJ/m ² or less, more preferably 5 mJ/m ² or less. is more preferable, and 2 mJ/m ² or less is even more preferable. When the sum of the polar component γsp and the hydrogen bond component γsh of the surface free energy is 8 mJ/m ² or less, the releasability is not impaired even after the thermocompression bonding process at 150°C or higher, which is preferable. The lower limit of the sum of the polar component γsp and the hydrogen bond component γsh of the surface free energy is 0 mJ/m ² .

The release film for molding polymer electrolyte fuel cell members of the present invention preferably has a thermal shrinkage of 0.8% or less after heat treatment at 160° C. for 30 minutes. It is more preferably 0.6% or less, still more preferably 0.5% or less, particularly preferably 0.4% or less, and most preferably 0.3% or less. The term "thermal shrinkage rate" as used in the present invention is obtained by obtaining data in the longitudinal direction and the lateral direction of the sample film by the measuring method described below, and adopting the larger data. A heat shrinkage rate of 0.8% or less is preferable because molding can be performed without cracks in the polymer electrolyte membrane or the catalyst layer even when the heat molding is performed at a high temperature of 150° C. or higher. However, the lower limit of the thermal shrinkage rate may be slightly negative data, and for example, it is preferably -1.0% or more. It can be said that ±0% is most preferable.

Since the release layer in the present invention has releasability even after being heat-treated at a high temperature, it is preferable that the releasability is good even after heat treatment at 150° C. for 10 minutes. Further, it is more preferable that the releasability can be maintained even when heat treatment is performed at 170° C. for 10 minutes. Therefore, among the above resins, it is preferable to use a material having excellent heat resistance for the release layer.

Although the means for providing the release layer of the present invention is not particularly limited, it is preferably provided by solution coating on the polyester film. By providing by solution coating, a smooth release layer can be provided, and off-line annealing can be performed at the same time, which is advantageous in terms of cost.

The solvent used for coating the release agent of the present invention is not particularly limited, and known solvents can be used. Specific examples of solvents include alcohols such as methanol, ethanol, isopropanol, butanol and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate and γ-butyrolactone. Ethers such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), diethylene glycol monobutyl ether (butyl cellosolve), propylene glycol monomethyl ether; Aromatic hydrocarbons such as benzene, toluene, xylene, and methylcyclohexane and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

A coating method for providing a release layer is not particularly limited, and a known method can be used. Examples thereof include gravure coating, die coating, reverse coating, spray coating, curtain coating and bar coating.

The drying temperature after applying the release agent is preferably 90° C. or higher, more preferably 120° C. or higher. In particular, when performing the annealing treatment off-line, the temperature must be 130° C. or higher, more preferably 150° C. or higher. The upper limit of the drying temperature is preferably 200°C or lower, more preferably 190°C or lower. The time for applying the temperature is preferably 3 seconds or more and 120 seconds or less, more preferably 5 seconds or more and 90 seconds or less. More preferably, it is 5 seconds or more and 60 seconds or less. By setting the time within the above period, the desired annealing treatment can be achieved and a film having good heat wrinkles can be obtained.

In the case of off-line annealing, the tension applied to the film in the drying oven when drying the release layer must be 1500 mN/mm ² or less. More preferably, it is 1000 mN/mm ² or less. By setting the tension to 1500 mN/mm ² or less, the film can be annealed at the target temperature without substantially applying tension, and the 160° C. heat shrinkage in the MD direction is 0.8% or less. be able to. The tension applied to the film was obtained from the following formula.
Tension applied to film (mN/mm ² ) = Tension in drying oven (mN) ÷ Width of film (mm) ÷ Thickness of film (mm)

The desired thermal shrinkage rate can be obtained by optimally combining the drying temperature and the tension in the drying oven. More ideal examples are a drying temperature of 150° C. or higher, a drying/annealing time of 10 seconds or longer, and a tension in the drying furnace of 800 mN/mm ² or lower. By combining these conditions, the heat shrinkage after heat treatment at 160° C. for 30 minutes becomes 0.6% or less, and it can be suitably used as a release film for molding polymer electrolyte fuel cell members.

The surface resistance value of the release layer surface of the release film of the present invention must be 1×10 ¹¹ Ω/□ or less. More preferably, it is 1×10 ⁹ Ω/□ or less, and still more preferably 1×10 ⁷ Ω/□ or less. By setting the surface resistance value of the release layer surface to 1×10 ¹¹ Ω/□ or less, it is possible to reduce the electrostatic interaction with adherends such as the catalyst layer and the electrolyte membrane, thereby improving the releasability. can be done. Although the lower limit of the surface resistance value of the release layer surface does not have to be specified, it is preferably 1×10 ³ Ω/□ or more. When the surface resistance value of the release layer surface is 1×10 ³ Ω/□ or more, the processing cost of the antistatic layer is not too high, and an inexpensive release film for molding polymer electrolyte fuel cell members can be provided. preferable.

EXAMPLES In order to describe the present invention in detail, examples are given below, but the present invention is of course not limited to these examples. The evaluation methods used in the present invention are as follows.

(Surface resistance value)
The surface resistance value of the surface of the release film of the present invention is measured by a surface resistance measuring instrument (manufactured by Simco Japan Co., Ltd.) after conditioning for 24 hours under conditions of a temperature of 23 ° C. and a humidity of 55%. , Work Surface Tester ST-3), and evaluated according to the following criteria.

◎: Surface resistance value is 10 ⁶ to 10 ⁷ Ω/□
○: Surface resistance value is 10 ⁸ to 10 ⁹ Ω/□
△: Surface resistance value is 10 ¹⁰ to 10 ¹¹ Ω/□
×: Surface resistance value is 10 ¹² Ω/□ or more

(Surface roughness)
These are values measured under the following conditions using a non-contact surface profile measurement system (VertScan R550H-M100). The area surface average roughness (Sa) adopted the average value of 5 measurements, and the maximum protrusion height (P) adopted the maximum value of 5 measurements.
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 50x ・0.5×Tube lens ・Measurement area: 187×139 μm
Incidentally, (Sa) and (P) in Table 1 show the data of the surface of the substrate polyester film on which the release layer is laminated.

(Measurement of heat shrinkage)
The release film was cut into a square of 10 cm×10 cm and heat-treated at 160° C. for 30 minutes in a hot air oven. After the heat treatment, the vertical and horizontal dimensions of the sample film were measured, and the thermal shrinkage rate was obtained according to the following formula (1). The measurement is performed n = 5 times, and the larger thermal shrinkage rate data is adopted from the average values of the thermal shrinkage rate data in the longitudinal direction and the lateral direction of the sample film, and the thermal shrinkage rate data of the release film. do. When measuring the dimensions before and after the heat treatment, the sample film was aged in a room at 25° C. for 12 hours or longer before the measurement.
Thermal shrinkage ratio = {(Length before shrinkage - Length after shrinkage) / Length before shrinkage} x 100 (%) Formula (1)

(Surface free energy)
The contact angles of water, diiodomethane, and bromonaphthalene whose surface tension is known were measured at 25° C. and 50% RH using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.: fully automatic contact angle meter DM-701). .
The obtained contact angle data is calculated from the "Kitazaki-Hata" theory to obtain the dispersion component γsd, the polar component γsp, and the hydrogen bond component γsh of the surface free energy of the release film. and This calculation was performed using the calculation software in this contact angle meter software (FAMAS).

(release film haze)
The film haze of the present invention was measured in accordance with JIS K 7136 using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.).

(Glass-transition temperature)
Compliant with JIS K7121, using a differential scanning calorimeter (manufactured by Seiko Instruments, DSC6200), 10 mg of resin sample was heated at 20 ° C./min over a temperature range of 25 to 350 ° C., and the compensation obtained from the DSC curve was obtained. The outer glass transition start temperature was taken as the glass transition temperature.

(Primary particle size of nanoparticles)
The method for measuring the primary particle size of the nanoparticles is to observe the particles in the cross section of the film after processing with a transmission electron microscope or scanning electron microscope, observe 100 particles that are not agglomerated, and use the average value. It was carried out by a method of using an average particle size. The primary particle size of irregularly shaped particles other than spherical particles can be calculated as a circle equivalent diameter. The circle-equivalent diameter is a value obtained by dividing the observed particle area by π, calculating the square root, and doubling the result.

(Transferability)
Transferability was evaluated by the following method. The solid content of 20% Nafion (registered trademark) Dispersion Solution DE2021 CS type (manufactured by Wako Pure Chemical Industries, Ltd.) and carbon black (manufactured by CABOT, VERCANX72R) were mixed so that the mass ratio was 1/9, and the total solid content was After adjusting with isopropanol/water (mass ratio of 8/2) so that the content was 15%, dispersion was performed using a centrifugal stirrer to obtain a slurry for a pseudo catalyst layer. The obtained pseudo-catalyst layer slurry was applied on a release film using an applicator so that the film thickness after drying was 10 μm, and dried in a hot air oven at 90° C. for 2 minutes. Then, after heat treatment in a hot air oven at 150° C. for 15 minutes, the temperature was returned to room temperature, and then the mending tape was peeled off at an angle of 180°. Transferability was evaluated according to the following criteria.

Good: No pseudo-catalyst layer remained on the release film.
Δ: A slight pseudo-catalyst layer remained on the release film.
(A level at which it is possible to somehow recognize that the pseudo-catalyst layer remains when observed on a white mount)
x: A faint pseudo-catalyst layer remained on the release film.
(A level at which the pseudo-catalyst layer remaining black can be clearly recognized when observed on a white mount)

(Crackability evaluation of catalyst layer)
Appearance evaluation such as cracking of the catalyst layer was performed as follows. First, the solid content of 20% Nafion (registered trademark) Dispersion Solution DE2021 CS type (manufactured by Wako Pure Chemical Industries, Ltd.) and carbon black (manufactured by CABOT, VERCANX72R) were mixed so that the mass ratio was 2/8, Dispersion was performed using a centrifugal stirrer to obtain a slurry for a pseudo catalyst layer. The obtained pseudo-catalyst layer slurry was applied on a release film using an applicator so that the film thickness after drying was 5 μm, and dried in a hot air oven at 90° C. for 1 minute. The prepared release film with a simulated catalyst layer was cut into a size of 10 cm×10 cm, heat-treated in a hot air oven at 150° C. for 10 minutes, and the state of the simulated catalyst layer was evaluated according to the following criteria.

○: Good with no cracks in the pseudo catalyst layer △: Appearance defects such as cracks were observed in part of the pseudo catalyst layer (less than 10% of the total area) ×: Most of the pseudo catalyst layer (10% of the total area) above) had appearance defects such as cracks

Furthermore, in order to evaluate workability at high temperatures, the same release film with a simulated catalyst layer as described above was heat-treated at 170° C. for 10 minutes, and the state of the simulated catalyst layer was evaluated for transferability and cracking resistance of the catalyst layer. The evaluation criteria were the same as those described above.

A solution containing resin (A) was prepared as follows.

(Resin solution A-1)
TOPAS (registered trademark) 6017S (manufactured by Polyplastics Co., Ltd.), a cyclic polyolefin resin, was added to toluene so that the solid content was 10% by mass, and heated in a flask with a condenser tube until the toluene refluxed. of toluene solution was obtained.

(Resin solution A-2)
After purging the inside of a dry 300 mL two-necked flask with nitrogen gas, 8.1 mg of dimethylanilium tetrakis(pentafluorophenyl)borate, 235.7 mL of toluene, and toluene solution 7 containing norbornene at a concentration of 7.5 mol/L. 0 mL, 1-octene 3.3 mL, and triisobutylaluminum 2 mL were added and the reaction solution was maintained at 25°C. Separately from this solution, in a glove box, 92.9 mg of (t-butylamido)dimethyl-9-fluorenylsilanetitanium dimethyl [(t-BuNSiMe2Flu)TiMe2] as a catalyst was placed in a flask and 5 mL of toluene was added. was dissolved in Polymerization was initiated by adding 2 mL of this catalyst solution to a 300 mL flask. After 2 minutes, 2 mL of methanol was added to terminate the reaction, and the resulting reaction mixture was placed in a large amount of methanol adjusted to be acidic with hydrochloric acid to deposit a precipitate, which was then filtered, washed, and dried. , 5.0 g of a 2-norbornene/1-octene copolymer was obtained. The resulting copolymer had a number average molecular weight Mn of 121,000, a glass transition temperature (Tg) of 268°C, and a dynamic storage modulus (E') of -20°C. and 1-octene (molar ratio) was former/latter=83/17. The resulting cyclic polyolefin copolymer was dissolved in toluene so that the solid content was 10% by mass.

(Antistatic layer coating solution AS-1)
A coating liquid was prepared with the following composition.
Water 34.47 parts by mass Isopropyl alcohol 51.20 parts by mass Polyester resin 1.00 parts by mass (Vylonal (registered trademark) MD1500, manufactured by Toyobo Co., Ltd., solid content 30% by mass)
PEDOT/PSS/PTS dispersion 13.30 parts by mass (Verazol (registered trademark) WED-SM, manufactured by Soken Chemical Co., Ltd., solid content 1.5% by mass)
Surfactant (Surfinol Dynol 604, manufactured by Nissin Chemical Industry Co., Ltd.) 0.03 parts by mass

(Antistatic layer coating solution AS-2)
A coating liquid was prepared with the following composition.
Water 28.7 parts by mass Isopropyl alcohol 43.0 parts by mass Silicate hydrolyzate 15.0 parts by mass (Colcoat (registered trademark) N-103X, manufactured by Colcoat, solid content 2% by mass)
PEDOT/PSS/PTS dispersion liquid 13.3 parts by mass (Verazol (registered trademark) WED-SM, manufactured by Soken Chemical Co., Ltd., solid content 1.5% by mass)

(Antistatic layer coating solution AS-3)
A coating liquid was prepared with the following composition.
Water 30.0 parts by mass Isopropyl alcohol 45.0 parts by mass Silicate hydrolyzate 25.0 parts by mass (Colcoat (registered trademark) N-103X, manufactured by Colcoat, solid content 2% by mass)

(Antistatic layer coating solution AS-4)
A coating liquid was prepared with the following composition.
Water 40.6 parts by mass Isopropyl alcohol 58.4 parts by mass Cationic acrylic resin 1.0 parts by mass (Elekondo PQ-10, manufactured by Soken Chemical Co., Ltd., solid content 50% by mass)

(Example 1)
A polyethylene terephthalate film (trade name: E5100, manufactured by Toyobo Co., Ltd.) having a width of 1000 mm and a thickness of 50 μm was coated with antistatic layer coating solution AS-1 by gravure coating so that the film thickness after drying was 40 nm on the corona surface. After that, it was dried at 120° C. for 5 seconds. Thereafter, the following release agent B-1 was applied on the antistatic layer by a gravure coating method so that the film thickness after drying was 100 nm, and dried at 170° C. for 9 seconds. At this time, the tension in the drying furnace was adjusted to 40 N/m (the unit is tension (N) per 1 m of width), and annealing was also performed at the same time to obtain a release film for molding polymer electrolyte fuel cell members. got
(Release agent B-1)
Toluene 60.0 parts by mass Tetrahydrofuran 20.0 parts by mass Resin solution A-1 20.0 parts by mass

(Example 2)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 1, except that the antistatic layer coating solution was changed to AS-2.

(Example 3)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 1, except that the antistatic layer coating solution was changed to AS-3.

(Example 4)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 1, except that the antistatic layer coating solution was changed to AS-4.

(Example 5)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 2, except that the release agent B-1 was changed to the following B-2.
(Release agent B-2)
Toluene 79.5 parts by mass Resin solution A-1 20.0 parts by mass Nano silica particle dispersion 2.5 parts by mass (TOL-ST manufactured by Nissan Chemical Industries, Ltd. Particle size 10 nm Solid content 40% by mass)
(Resin (A)/Nanoparticles (B) = 100 parts by mass/50 parts by mass)

(Example 6)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 2, except that the release agent B-1 was changed to the following B-3.
(Release agent B-3)
Toluene 79.5 parts by mass Resin solution A-1 20.0 parts by mass Nano silica particle dispersion 5.0 parts by mass (TOL-ST, manufactured by Nissan Chemical Industries, Ltd. Particle size 10 nm Solid content 40% by mass)
(Resin (A)/Nanoparticles (B) = 100 parts by mass/100 parts by mass)

( Reference example 7 )
Same as Example 5, except that the drying conditions during the release layer processing were changed to 120° C. for 30 seconds, and the tension in the drying oven was changed to 120 N/m (unit: tension (N) per 1 m width). A release film for molding a solid polymer type fuel cell member was obtained by processing to .

(Example 8)
A release film for molding a polymer electrolyte fuel cell member was obtained by processing in the same manner as in Example 5, except that the drying temperature during processing of the release layer was changed to 130°C.

(Example 9)
A release film for molding a polymer electrolyte fuel cell member was obtained by processing in the same manner as in Example 2, except that the resin solution was changed from A-1 to A-2.

(Comparative example 1)
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 2, except that no antistatic layer was provided.

(Comparative example 2 )
A release film for molding a polymer electrolyte fuel cell member was obtained in the same manner as in Example 2, except that the antistatic layer was provided on the side of the polyester film opposite to the side on which the release layer was coated.

Table 1 summarizes the evaluation results of Examples and Comparative Examples.

By providing a release film with improved release properties by laminating an antistatic layer between a polyester film and a release layer, it is possible to mold components such as catalyst layers and electrolyte membranes used in polymer electrolyte fuel cells. It can be suitably used as a release film for. By using the release film for molding a polymer electrolyte fuel cell according to the present invention, even a catalyst layer or an electrolyte membrane having weak film strength can be easily transferred, and a fuel cell with good performance can be manufactured at a relatively low cost. can be done.

Claims (6)

A release film in which an antistatic layer and a release layer are laminated in order on at least one side of a polyester film, and has a heat shrinkage rate of 0.8% or less when treated at 160 ° C. for 30 minutes, and the release film The surface resistivity is 1×10 ³ Ω/□ or more and 1×10 ⁷ Ω/□ or less,
The haze of the release film is 0.2% or more and 10% or less,
The release layer contains a cyclic polyolefin resin having a glass transition temperature of 130° C. or higher (however, the release layer does not contain a silicone resin),
A release film for molding a polymer electrolyte fuel cell, wherein the release film is annealed under conditions of a drying temperature of 150° C. or higher and a tension of 800 mN/mm ² or lower. 2. The release film for molding a polymer electrolyte fuel cell according to claim 1, wherein the polyester film is a polyethylene terephthalate film. 3. The release mold for molding a polymer electrolyte fuel cell according to claim 1, wherein the total value of the polar component and the hydrogen bond component of the surface free energy of the surface of the release layer is 8 mJ/m ² or less. the film. 4. The release film for molding a polymer electrolyte fuel cell according to claim 1, wherein the release layer contains nanoparticles. 5. The release film for molding a polymer electrolyte fuel cell according to claim 4, wherein the nanoparticles contained in the release layer have a primary particle size of 1 nm or more and 100 nm or less. The region surface average roughness (Sa) of the surface of the polyester film on which the release layer is laminated is 1 to 50 nm, and the maximum protrusion height (P) is 2 μm or less. A release film for molding a polymer electrolyte fuel cell according to any one of the above.