JP6790421B2 - Release film - Google Patents

Description

The present invention relates to a release film, and more particularly to a release film suitably used for manufacturing an electronic component, particularly a membrane-electrode assembly (MEA) which is a component of a polymer electrolyte fuel cell. It is a thing.

The 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 proton conductive resin is used for the polymer electrolyte membrane, and a polymer having a sulfonium group in the side chain is used. As an example, a sulfonic acid-based resin composed of strongly acidic perfluorocarbon (-CF2-) is used (for example, 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 these MEA manufacturing methods, a method has been proposed in which a polymer electrolyte membrane and a catalyst layer are molded into separate support films by a casting method and then thermocompression bonded at a high temperature of 150 ° C. or higher to bond the two. ..

As the support film, a fluororesin film typified by polytetrafluoroethylene (PTFE), which is not contaminated with silicone or the like and has high chemical resistance and heat resistance, has been used. However, such a conventional technique has a problem that when the film is processed by the roll-to-roll method, the storage elastic modulus of the PTFE film is low even at room temperature, so that the feeling of waist is weak and the processability is not always sufficient.

Further, a film provided with a release layer on a PET film is cheaper than a fluorine-based film, has excellent processability, and has a mold release property (see, for example, Patent Documents 1 to 3). However, such a conventional technique has the elasticity of a PET film. Since the rate is high even at a high temperature, there is a problem that pressure is not uniformly applied to the transfer portion during thermal transfer of the catalyst layer, and transfer unevenness is likely to occur.

Japanese Unexamined Patent Publication No. 2015-11901 Japanese Unexamined Patent Publication No. 2014-154273 Japanese Unexamined Patent Publication No. 2003-285396

The present invention has been made in view of the above-mentioned special circumstances of MEA, which is a constituent member of a polymer electrolyte fuel cell, against the background of problems of the prior art, and an object of the present invention is at the time of coating a catalyst layer. It is an object of the present invention to provide a release film having excellent transferability, which can improve the pressure uniformity in the transfer process while maintaining the handleability at the time of processing.

That is, the present invention has the following configuration.
1. 1. A release film having a release layer on at least one side of a polyester film, characterized in that the release elastic modulus at 30 ° C. is 1500 MPa or more and the storage elastic modulus at 100 ° C. is 1000 MPa or less. Release film.
2. 2. The release film according to the first aspect, which is used for molding a polymer electrolyte fuel cell member.
3. 3. The release film according to the first or second above, wherein the storage elastic modulus at 150 ° C. is 20 MPa or more and 500 MPa or less.
4. The release film according to any one of the above 1 to 3, wherein the total value of the polar component of the surface free energy of the surface of the release layer and the hydrogen bond component is 8 mJ / m ² or less.
5. The release film according to any one of the above 1 to 4, wherein the polyester constituting the polyester film contains a copolymerized polyester.
6. Any of the first to fifth above, wherein the copolymerized polyester contains an aromatic dicarboxylic acid component, an ethylene glycol, and a glycol component containing a branched aliphatic glycol and / or an alicyclic glycol as a constituent component. The release film described in Crab.
7. The release film according to the release layer, the olefin resin, any foregoing first to sixth, characterized in that it comprises at least one resin selected from the full Tsu Motokei resin.
8. The release film according to the seventh aspect, wherein the olefin resin is cyclic polyolefin or polymethylpentene.

According to the present invention, as a release film preferably used for electronic component manufacturing applications such as solid polymer fuel cell member molding applications, while maintaining handleability during processing during catalyst layer coating. The pressure uniformity in the transfer step can be improved, and a release film having excellent transferability can be provided.

Hereinafter, the present invention will be described in detail.

(Release film)
The release film of the present invention is a release film having a release layer on at least one side of a polyester film as a base material. The storage elastic modulus of the release film at 30 ° C. is preferably 1500 MPa or more. When the storage elastic modulus at 30 ° C. is 1500 MPa or more, the mechanical strength at the time of peeling at room temperature is not insufficient, and the handleability at room temperature is maintained, which is preferable. It is particularly preferably 2000 MPa or more, and further preferably 2500 MPa or more. However, if the storage elastic modulus at 30 ° C. is too large, the rigidity may be too strong and the handleability may be deteriorated. Therefore, it is preferably set to 7,000 MPa or less. More preferably, it is 5000 MPa or less.

Further, the release film of the present invention preferably has a storage elastic modulus of 1000 MPa or less at 100 ° C. When the storage elastic modulus at 100 ° C. is 1000 MPa or less, the pressure is uniformly applied when the catalyst layer laminated on the release film and the electrolyte membrane are thermocompression bonded, so that the adhesion between the catalyst layer and the electrolyte membrane is improved and the release film is released. Therefore, the catalyst layer is easily transferred. Therefore, the transferability of the catalyst layer from the release film is improved, which is preferable. It is more preferably 700 MPa or less, and particularly preferably 600 MPa or less. However, if the storage elastic modulus at 100 ° C. is too low, the heat resistance may be insufficient, so it is preferably 150 MPa or more.

Further, the release film of the present invention preferably has a storage elastic modulus of 20 MPa or more at 150 ° C. When the storage elastic modulus at 150 ° C. is 20 MPa or more, heat resistance that can withstand the heat during thermal transfer of the catalyst layer can be realized, which is preferable. It is more preferably 30 MPa or more, and particularly preferably 50 MPa or more. Further, the release film of the present invention preferably has a storage elastic modulus at 150 ° C. of 500 MPa or less. When the storage elastic modulus at 150 ° C. is 500 MPa or less, the catalyst layer is sufficiently deformed during thermal transfer, so that it is excellent in followability to the surface unevenness of the electrolyte membrane, and the adhesion between the catalyst layer and the electrolyte membrane is improved, which is preferable. It is more preferably 200 MPa or less, and particularly preferably 100 MPa or less.

(Polyester film)
The polyester film used as the base film in the present invention is preferably a polyester film contained as a copolymerized polyester constituent component, and particularly preferably a homopolyester typified by polyethylene terephthalate or polyethylene naphthalate and a copolymerized polyester. It is a polyester film that is mixed and used. Further, the polyester film is more preferably a biaxially stretched film. The raw materials used for the polyester film and the preferred production method are described below.

The polyester film preferably used in the present invention is a biaxial polyester composed of an aromatic dicarboxylic acid component and a glycol component containing ethylene glycol and branched aliphatic glycol and / or alicyclic glycol. It is preferably used as a part of the raw material of the oriented polyester film.

In the copolymerized polyester, the aromatic dicarboxylic acid component is mainly composed of terephthalic acid, naphthalenedicarboxylic acid or an ester-forming derivative thereof, but the amount of the terephthalic acid and / or naphthalenedicarboxylic acid component with respect to the total dicarboxylic acid component is 70 mol%. As mentioned above, it is preferably 85 mol% or more, particularly preferably 95 mol% or more, and particularly preferably 100 mol%.

Examples of the branched aliphatic glycol include neopentyl glycol, 1,2-propanediol, and 1,2-butanediol. Examples of the alicyclic glycol include 1,4-cyclohexanedimethanol and trimethylolpropane.

Of these, neopentyl glycol and 1,4-cyclohexanedimethanol are particularly preferable. Further, in the present invention, it is a more preferable embodiment that 1,3-propanediol or 1,4-butanediol is used as a copolymerization component in addition to the above-mentioned glycol component. It is suitable to use these glycols as a copolymerization component in order to impart the above-mentioned characteristics, and further, it is excellent in transparency and heat resistance, and from the viewpoint of improving the adhesion with the adhesive modification layer. Is also preferable.

Further, if necessary, one or more of the following dicarboxylic acid components and / or glycol components may be used in combination with the copolymerized polyester as the copolymerization components.
Other dicarboxylic acid components that can be used in combination with terephthalic acid or its ester-forming derivative include (1) isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, and diphenoxyetanedicarboxylic acid. Aromatic dicarboxylic acids such as acids, diphenylsulfondicarboxylic acids, 5-sodium sulfoisophthalic acids, and phthalic acids or ester-forming derivatives thereof, (2) oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid , An aliphatic dicarboxylic acid such as fumaric acid and glutaric acid or an ester-forming derivative thereof, (3) an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid or an ester-forming derivative thereof, (4) p-oxybenzoic acid, Examples thereof include oxycarboxylic acids such as oxycaproic acid and ester-forming derivatives thereof.

On the other hand, examples of other glycol components that can be used in combination with ethylene glycol and branched aliphatic glycol and / or alicyclic glycol include aliphatic glycols such as pentanediol and hexanediol, bisphenol A, and bisphenol S. Examples thereof include aromatic glycols and their ethylene oxide adducts, diethylene glycols, triethylene glycols and dimerdiols.

Further, if necessary, the copolymerized polyester can be further copolymerized with a polyfunctional compound such as trimellitic acid, trimesic acid, or trimethylolpropane.

As the catalyst used in producing the copolymerized polyester, for example, an alkaline earth metal compound, a manganese compound, a cobalt compound, an aluminum compound, an antimony compound, a titanium compound, a titanium / silicon composite oxide, a germanium compound and the like can be used. .. Among these, titanium compounds, antimony compounds, germanium compounds, and aluminum compounds are preferable from the viewpoint of catalytic activity.

When producing the copolymerized polyester, it is preferable to add a phosphorus compound as a heat stabilizer. As the phosphorus compound, for example, phosphoric acid, phosphorous acid and the like are preferable.

From the viewpoint of moldability, adhesion, and film-forming stability, the copolymerized polyester preferably has an intrinsic viscosity of 0.50 dl / g or more, more preferably 0.55 dl / g or more, and particularly preferably 0. It is 60 dl / g or more. If the intrinsic viscosity is less than 0.50 dl / g, the moldability tends to decrease. When a filter for removing foreign matter is provided on the melt line, the upper limit of the intrinsic viscosity is preferably 1.0 dl / g from the viewpoint of discharge stability during extrusion of the molten resin.

The polyester film used as the base film in the present invention is prepared by blending a copolymerized polyester having a large amount of copolymerization components with a homopolyester (for example, polyethylene terephthalate) to adjust the amount of the copolymerization components.

By forming a film using the blending method, transparency and a high melting point (heat resistance) can be realized while maintaining the same flexibility as when only the copolymerized polyester is used. Further, when only homopolyester (for example, polyethylene terephthalate) is used, the elastic modulus does not become too high, the pressure is likely to be uniformly applied to the transfer portion during thermal transfer of the catalyst layer, and transfer unevenness is less likely to occur.

Further, at least one kind of the copolymerized polyester and a homopolyester other than polyethylene terephthalate (for example, polytetramethylene terephthalate or polybutylene terephthalate) may be blended and used as a raw material for the molding polyester film of the present invention. Absent.

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

The haze of the release film of the present invention is preferably 10% or less. By setting the haze to 10% or less, the appearance inspection of the obtained release film can be facilitated.

In the present invention, the thickness of the polyester film is not particularly limited, but 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 it is 12 μm or more, wrinkles are less likely to occur when the catalyst layer is molded and transferred, which is preferable. Further, when it is 100 μm or less, it is advantageous in terms of cost, and it is preferable because the rigidity is not too strong (not too hard).

The polyester film used in the present invention preferably has a small heat shrinkage rate in order to suppress the heat shrinkage rate of the produced release film. For example, the heat shrinkage when treated at 160 ° C. for 30 minutes by the same measuring method as the heat shrinkage of the release film described later is preferably 2.5% or less, more preferably 2.0. % Or less, more preferably 1.5% or less, and particularly preferably 1.0% or less. However, the small heat shrinkage of the release film of the present invention is not simply brought about by the small heat shrinkage of the polyester film as the base film, and the drying process conditions after application of the release agent, which will be described later, are optimized. It can be reached including.

The region surface average roughness (Sa) of the surface on which the release layer of the polyester film used in the present invention 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 on which the release layer of the polyester film used in the present invention 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, there is no risk of cracks or pinholes occurring in the catalyst layer when the catalyst layer is transferred, which is preferable.

The polyester film as a base material may be a single layer or a laminated layer of two or more types. In addition, various additives can be contained in the film, if necessary, as long as the effects of the present invention are exhibited. Examples of the additive include an antioxidant, a light resistant agent, an antioxidant, an organic wetting agent, an antistatic agent, an ultraviolet absorber, a surfactant and the like. When the film has a laminated structure, it is also preferable to add additives according to the function of each layer, if necessary.

The polyester film can be obtained, for example, by melt-extruding the above polyester resin into a film and cooling and solidifying it with a casting drum to form a film. As the polyester film of the present invention, either a non-stretched film or 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 sequential biaxial stretching method, a vertical and horizontal simultaneous biaxial stretching method, and the like can be adopted. As described above, a biaxially stretched polyester film is particularly preferable.

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

It is preferable that the release film of the present invention controls heat shrinkage when heated at 150 ° C. or higher and suppresses oligomers precipitated from the polyester film. The method for controlling the heat shrinkage is not particularly limited, and examples thereof include annealing a polyester film. The annealing treatment may be performed in-line when molding the polyester film, or may be performed offline when processing the release layer after molding.

The method for suppressing the oligomers precipitated from the polyester film is not particularly limited, and examples thereof include a method of modifying the resin used for the polyester film and a method of providing an oligomer precipitation prevention layer on the polyester film by means such as coating. ..

In order to suppress the heat shrinkage rate of the base polyester film used in the present invention, the polyester film may be annealed during film formation (in-line) or may be annealed offline. Further, in-line annealing and offline annealing may be used in combination.

The polyester film used as the base film in the present invention is particularly preferably a biaxially stretched film. In the present invention, the thermal deformation rate of the film under a minute tension (initial load 49 mN) can be controlled by the molecular orientation by biaxial stretching, which is a drawback of the unstretched sheet, such as solvent resistance and dimensional stability. Sex is improved. That is, it is possible to improve the solvent resistance and heat resistance, which are the drawbacks of the unstretched sheet, while maintaining the ease of deformation of the unstretched sheet during heating (following of the surface unevenness of the electrolyte membrane). ..

As a method for producing the biaxially oriented polyester film, for example, after drying the polyester resin as necessary, it is supplied to a known melt extruder, extruded into a sheet from a slit-shaped die, and cast by a method such as electrostatic application. A method is used in which the unstretched sheet is biaxially stretched after being brought into close contact with a drum and cooled and solidified to obtain an unstretched sheet.

As a biaxially stretched method, a method is adopted in which an unstretched sheet is stretched and heat-treated in the longitudinal direction (MD) and the width direction (TD) of the film to obtain a biaxially stretched film having a desired degree of in-plane orientation. .. Among these methods, in terms of film quality, the MD / TD method of stretching in the longitudinal direction and then stretching in the width direction, or the TD / MD method of stretching in the width direction and then stretching in the longitudinal direction, etc. A shaft stretching method and a simultaneous biaxial stretching method in which the longitudinal direction and the width direction are stretched almost simultaneously are desirable. Further, in the case of the simultaneous biaxial stretching method, a tenter driven by a linear motor may be used. Further, if necessary, a multi-stage stretching method in which stretching in the same direction is performed in multiple stages may be used.

The film stretching ratio at the time of biaxial stretching is preferably 1.6 to 4.2 times in the longitudinal direction and the width direction, and particularly preferably 1.7 to 4.0 times. In this case, the stretching ratio in the longitudinal direction and the stretching ratio in the width direction may be increased, or may be the same. It is more preferable that the stretching ratio in the longitudinal direction is 2.8 to 4.0 times and the stretching ratio in the width direction is 3.0 to 4.5 times.

It is particularly preferable that the stretching conditions for producing the polyester film in the present invention are selected, for example, to adopt the following conditions in order to satisfy the above-mentioned characteristics specified in the present invention.

In the longitudinal stretching, it is more preferable that the stretching temperature is 50 to 110 ° C. and the stretching ratio is 1.6 to 4.0 times so that the subsequent transverse stretching can be performed smoothly.

Normally, when polyethylene terephthalate is stretched, if the stretching temperature is lower than the appropriate conditions, the yield stress suddenly increases at the initial stage of the start of transverse stretching, so that stretching cannot be performed. Further, even if stretching is possible, the thickness and stretching ratio tend to be non-uniform, which is not preferable.

Further, when the stretching temperature is higher than the appropriate conditions, the initial stress is low, but the stress is not high even when the stretching ratio is high. Therefore, the film has a small stress at 100% elongation at 25 ° C. Therefore, by taking the optimum stretching temperature, it is possible to obtain a highly oriented film while ensuring stretchability.

However, 1 to 40 mol of the copolymerized polyester ester constituent unit (for example, an ester constituent unit consisting of terephthalic acid and neopentyl glycol, an ester constituent unit consisting of terephthalic acid and 1,4-cyclohexanedimethanol, etc.) When% is included, the stretching stress drops sharply as the stretching temperature is raised so as to eliminate the yield stress. In particular, since the stress does not increase even in the latter half of stretching, the orientation does not increase, and the stress at 100% elongation at 25 ° C. decreases. Therefore, in the present invention, in the case of a film using a copolymerized polyester, the stretching temperature in the lateral direction is preferably set to the following conditions.

First, the preheating temperature is preferably 50 ° C. to 150 ° C. Next, in the first half of the transverse stretching, the stretching temperature is preferably −20 ° C. to + 25 ° C., particularly preferably −15 ° C. to + 25 ° C. with respect to the preheating temperature. Further, in the latter half of the transverse stretching, the stretching temperature is preferably 0 ° C. to −40 ° C., particularly preferably −10 ° C. to −40 ° C. with respect to the stretching temperature of the first half portion. By adopting such a condition, the yield stress is small in the first half of the transverse stretching, so that the stretching is easy, and in the latter half, the orientation is easy. The stretching ratio in the lateral direction is preferably 2.5 to 5.0 times.

Further, the film is heat-treated after biaxial stretching, and this heat treatment is performed in an oven. The heat treatment temperature and heat treatment time are set within the following ranges depending on the level of the required heat shrinkage rate. The heat treatment temperature is preferably in the range of 120 to 245 ° C, particularly preferably 150 to 240 ° C. The heat treatment time is preferably 1 to 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction. In the present invention, even within the range of the heat treatment temperature, the suitable range differs depending on the composition of the film raw material used. Therefore, the heat treatment temperature is set so that the surface orientation of the film is 0.095 or less. It is important to set. The reason will be described in detail later.

When performing the annealing treatment in-line, for example, the following method can be generally used. In order to reduce the heat shrinkage rate at 160 ° C. in the longitudinal direction and the lateral direction of the film, it is preferable to raise the heat treatment temperature, lengthen the heat treatment time, and perform the relaxation treatment. The heat treatment temperature is preferably 200 to 230 ° C., and the heat treatment is preferably performed while relaxing at a relaxation rate of 1 to 8%. Further, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

It is difficult to lengthen the production line and lengthen the heat treatment time in order to reduce the heat shrinkage rate at 160 ° C. in the longitudinal direction and the lateral direction of the film due to equipment restrictions. Further, if the feed rate of the film is slowed down, the productivity is lowered. As described above, it is important to keep the section temperature as low as around 100 ° C. up to the stretching section. On the other hand, in heat fixing, it is important to quickly raise the temperature to a high temperature of about 200 ° C. Therefore, as a measure to solve the problem, it is recommended as a preferable embodiment to install a far-infrared heater in the heat treatment zone to reinforce the heating.

Further, a method of providing a heat insulating section of 1 m or more between the stretching section and the heat fixing section to improve the heating efficiency after the heat insulating section can be mentioned. Specifically, the heating efficiency can be improved by strengthening the partition for each section to reduce the leakage of heat flow. Further, a method of adjusting the pressure in the oven while ensuring the air volume by adjusting the balance and strength of the air volume and suppressing the leakage of heat flow may be used. Further, for heating that is insufficient with hot air heating, a method of adding an infrared heater to the strong heating section is also suitable. In addition, the amount of heating is increased by increasing the length of the heat fixing section and the number of sections. Such methods are also effective.

The release film of the present invention preferably has a storage elastic modulus of 1500 MPa or more at 30 ° C. and a storage elastic modulus of 1000 MPa or less at 100 ° C. in the longitudinal and width directions of the film, and more preferably 150. The storage elastic modulus at ° C. is 20 MPa or more and 500 MPa or less. In order to achieve such a storage elastic modulus, when producing a film containing the above-mentioned copolymerized polyester as a constituent component, the plane orientation of the film is adjusted. It is preferable to control the film in a specific range, that is, the degree of surface orientation of the film is preferably lowered to 0.095 or less, and particularly preferably 0.001 to 0.090. By lowering the degree of plane orientation in this way, the storage elastic modulus of the film can be adjusted.

However, simply lowering the plane orientation of the film will result in too low a storage elastic modulus. When a copolymerized polyester containing branched aliphatic glycol and / or alicyclic glycol as a copolymerization component, which is a preferred embodiment of the present invention, is used as a film raw material, molecules at a high temperature due to the bulkiness of the molecular structure of the glycols. Motility can be suppressed. Furthermore, the storage elastic modulus of the release film can be controlled within the above range by synergistic means by lowering the plane orientation of the film using specific stretching conditions.

As described above, it is one of the preferable embodiments to set the degree of surface orientation of the biaxially oriented polyester film to a low level. Generally, a method of lowering the draw ratio and a method of raising the heat fixing temperature are known as means for lowering the degree of surface orientation, but the former method is not preferable because the thickness unevenness of the film is deteriorated. Therefore, the latter method is preferable. In the latter case, the above-mentioned problem arises, but it can be avoided by a method exemplified as a preferred embodiment. Further, in the present invention, it is necessary to use a copolymerized polyester as the biaxially oriented polyester film, and the melting point is lower than that of the homogeneous polymer. Therefore, when the heat fixing temperature is raised, the clip that holds the film in the transverse stretching step The film is easy to fuse. Therefore, it is important that the vicinity of the clip is sufficiently cooled when the clip releases the film at the tenter outlet. Specifically, in order to prevent fusion between the film and the clip, (1) a method of providing a heat shield wall on the clip portion so that the clip is not easily heated, and (2) a clip cooling mechanism is added to the tenter. Method, (3) A method of setting a long cooling section after heat fixation to sufficiently cool the entire film in order to strengthen the cooling capacity, (4) Cooling by increasing the length of the cooling section and the number of sections. It is preferable to adopt a method of increasing efficiency, (5) a method of strengthening the cooling of the clip by using a type in which the return portion of the clip runs outside the furnace. Here, the melting point is the endothermic peak temperature at the time of melting detected at the time of the primary temperature rise of the so-called differential scanning calorimetry (DSC). The melting point is a value obtained by measuring at a heating rate of 20 ° C./min using a differential scanning calorimeter (V4.OB2000 type manufactured by DuPont).

When the annealing treatment is performed offline, it can be performed at the same time as the release layer described later is applied, and this method is preferable because the heat shrinkage rate of the release film, which is a product, can be suppressed particularly effectively.

(Oligomer precipitation prevention layer)
In the present invention, an oligomer precipitation prevention layer may be provided on at least one side of the polyester film. The surface on which the oligomer precipitation prevention layer is provided is preferably provided on the opposite side of the surface of the polyester film on which the release layer is provided, and in addition, the surface of the polyester film is provided at the interface between the release layer and the polyester film. It is more preferable to prevent the precipitation of oligomers from both sides. By providing the oligomer precipitation prevention layer, even if a polyester film in which oligomers are easily precipitated is used, precipitation of oligomers on the surface of the release film is suppressed, process contamination by oligomers, and solid polymer fuel cell components that are transcripts. It is preferable because the migration to is reduced.

The resin used for the oligomer precipitation prevention layer is not particularly limited, but preferably contains at least one of a polyester resin, an isocyanate resin, an acrylate resin, and a melamine resin. It is preferable that these oligomer precipitation prevention layers are provided on the polyester film by coating. The oligomer precipitation prevention layer may be provided when the polyester film is formed, or may be continuously provided when the release layer is applied.

(Release layer)
In the present invention, it is necessary to provide a release layer on at least one side of the polyester film. No particular limitation is imposed on the resin used for the release layer, but preferably comprising at least one or more kinds of olefin resin and off Tsu Motokei resin. It is preferable that these release layers are provided on the polyester film by coating.

Examples of the olefin resin used for the release layer include copolymerized polyethylene, cyclic polyolefin, and polymethylpentene, but from the viewpoint of heat resistance, it is preferable to use cyclic polyolefin, polymethylpentene, and the like. By using the resin for the release layer, it is possible to maintain the releasability with the binder used for the electrolyte membrane such as Nafion even when the heat treatment is performed at 150 ° C. or higher, which is preferable.

The copolymerized polyethylene can be copolymerized with α-olefins such as propylene, n-butene, n-pentene, and n-hexene. 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, the adhesion to the polyester film can be improved.

The cyclic polyolefin is a resin containing a cyclic olefin as a polymerization component. The cyclic olefin is a polymerizable cyclic olefin having an ethylenic double bond in the ring, and can be classified into a monocyclic olefin, a bicyclic olefin, a polycyclic olefin having three or more rings, and the like. Examples of monocyclic olefins include cyclic C4-12 cycloolefins such as cyclobutene, cyclopentene, cycloheptene, and cyclooctene. 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. Norbornenes having (C1-4 alkyl group); norbornenes having alkenyl groups such as 5-ethylidene-2-norbornene; 5-methoxycarbonyl-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, etc. Norbornenes having an alkoxycarbonyl group of; norbornenes having a cyano group such as 5-cyano-2-norbornene; having an aryl group such as 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene. Examples thereof include norbornenes; octalin; octalin having an alkyl group such as 6-ethyl-octahydronaphthalene.

Examples of polycyclic olefins include dicyclopentadiene; 2,3-dihydrodicyclopentadiene, methanooctahydrofluorene, dimethanooctahydronaphthalene, dimethanocyclopentadienonaphthalene, methanooctahydrocyclopentadienonaphthalene, etc. Derivatives of: Derivatives having a substituent such as 6-ethyl-octahydronaphthalene; Additives of cyclopentadiene and tetrahydroindene and the like, tri-tetrameric compounds of cyclopentadiene and the like.

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 proportion of bicyclic olefins (particularly norbornenes) in the total cyclic olefins may be 10 mol% or more, for example, 30 mol% or more, preferably 50 mol% or more, still more preferably 80 mol% or more. , Bicyclic olefin alone (100 mol%) may be used. In particular, if the proportion of polycyclic olefins having three or more rings is large, it becomes difficult to use them in the roll-to-roll method, which is not preferable.

Specific examples of the bicyclic olefin include norbornene (2-norbornene, which may have a substituent), octalin (octahydronaphthalene, which may have a substituent), and the like. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, an acyl group, a cyano group, an amide group and a halogen atom. 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 preferable.

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

Examples of the chain olefin 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 can be mentioned. These chain olefins can be used alone or in combination of two or more. Among these chain olefins, α-chain C2-8 olefins are preferable, and α-chain C2-4 olefins (particularly ethylene) are more preferable.

The ratio (molar ratio) of the cyclic olefin to the chain olefin is, for example, cyclic olefin / chain olefin = 100/0 to 1/99, preferably 90/10 to 10/90, and more preferably 70/30 to 20. It is about / 80. If the proportion of the cyclic olefin is too small, the heat resistance is lowered and the peelability is also lowered, which is not preferable.

Other copolymerizable monomers include, for example, vinyl ester-based monomers (eg, vinyl acetate, vinyl propionate, etc.); diene-based monomers (eg, butadiene, isoprene, etc.); (meth) acrylic-based Monomers [for example, (meth) acrylic acid, or derivatives thereof (such as (meth) acrylic acid ester)] 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, based on the total cyclic polyolefin.

The cyclic polyolefin may be a resin obtained by addition polymerization, or may be a resin obtained by ring-opening polymerization (ring-opening metathesis polymerization, etc.). Further, the polymer obtained by ring-opening metathesis polymerization may be a hydrogenated hydrogenated resin. The polymerization method of the cyclic polyolefin is a conventional method, for example, ring-opening metathesis polymerization using a metathesis polymerization catalyst, addition polymerization using a Cheegler type catalyst, and addition polymerization using a metallocene-based catalyst (usually, a metathesis polymerization catalyst is used). 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 250 ° C., but from the viewpoint of heat resistance, for example, 60 to 250 ° C., preferably 100 to 250 ° C., more preferably 150 ° C. It is about ~ 250 ° 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.

In gel permeation chromatography (GPC), the number average molecular weight of the cyclic polyolefin is, for example, 1000 to 150,000, preferably 5000 to 120,000, and more preferably 1000 to 100,000 (particularly 2000 to 90000) in terms of polystyrene.

As a commercially available product of cyclic polyolefin, there is TOPAS (registered trademark) (manufactured by Polyplastics), which can be preferably used. Among the TOPAS (registered trademark) series, TOPAS (registered trademark) 6017S has a Tg of 170 ° C. or higher, so that deterioration of the release layer does not easily occur even with a heat treatment of 150 ° C. or higher, which is particularly preferable.

As a commercially available product of cyclic polyolefin, ARTON (registered trademark) (manufactured by JSR Corporation) is also available and can be preferably used. However, ARTON (registered trademark) generally has a polar group in the molecule, and thus is released from the mold. The polar component of the surface free energy of the layer becomes large, and the releasability may be inferior to that of TOPAS (registered trademark).

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

The structural unit B is composed of ethylene and a resin derived from at least one type of olefin selected from α-olefins having 3 to 4 carbon atoms, and preferably contains 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 more preferably 15 mol% or less.

As an example of the α-olefin having 3 to 4 carbon atoms used in the structural unit B, 1-butene and propylene are preferably used, but it is preferable to use propylene from the viewpoint of physical properties and the like. Α-olefins and ethylene having 3 to 4 carbon atoms may be used alone or in combination of two or more.

In addition to the structural unit A and the structural unit B, the polymethylpentene resin may have other structural units of a polymerizable compound. 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; unconjugated polyenes such as 1,4-hexadiene, octadiene, cyclopentadiene, norbornane and norbornadiene can be mentioned.

The above-mentioned other polymerizable compound can be contained in a ratio of 10 mol% or less with respect to a total of 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, the adhesion to polyester resins such as polyethylene terephthalate and polyethylene naphthalate can be improved by using in combination with a cross-linking agent. The method for introducing these functional groups can be carried out by a known method. The amount of functional groups to be introduced is preferably 10 equivalents or less with respect to the polymethylpentene resin.

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

As the fluororesin preferably used in the present invention, PTFE (polytetrafluoroethylene), PVDF (polyfluorovinylidene), PCTFE (polychlorotrifluoroethylene), PVF (polyfluorovinyl), and the like, and these resins were used. Copolymers, PFA (copolymer of ethylene tetrafluoroethylene (C ₂ F ₄ ) and perfluoroalkoxyethylene), FEP (combination of tetrafluoroethylene and hexafluoropropylene), ETFE (tetrafluoroethylene (-) C ₂ F ₄ -) and ethylene (-C ₂ H ₄ -) of the copolymer) and the like. Further, an acrylate-modified fluorine-based resin can be added to a polyfunctional acrylate or the like for use.

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

A cross-linking agent may be used for the release layer in the present invention in addition to the above resin. As the cross-linking agent, isocyanate-based, carbodiimide-based, epoxy-based, melamine-based, metal chelate-based, and the like can be used. When the resin used for the release layer has a reactive functional group, it is suitable because the adhesion with the polyester film can be improved by using a cross-linking agent in combination.

The film thickness of the release layer in the present invention is preferably 0.03 μm or more and 5 μm or less. More preferably, it is 0.05 μm or more and 3 μm or less. If it is thinner than 0.03 μm, the releasability may be insufficient, and if it is thicker than 5 μm, it may affect the curl and cost of the film, which is not desirable.

The surface free energy γs of the release layer of the present invention is not particularly limited, it is preferable that the sum of the polar component γsp a hydrogen bond component γsh in the surface free energy is 8 mJ / m ² or less, 5 mJ / m ² towards the following Is more preferable, and ² mJ / m ² or less is further preferable. When the total of the polar component γsp of the surface free energy and the hydrogen bond component γsh is 8 mJ / m ² or less, the releasability is not impaired even after the thermocompression bonding step at 150 ° C. or higher, which is preferable. As the lower limit of the total of the polar component γsp of the surface free energy and the hydrogen bond component γsh, 0 mJ / m ² can be produced.

The release film of the present invention preferably has a heat shrinkage rate of 2.5% or less after being heat-treated at 160 ° C. for 30 minutes. It is more preferably 2.0% or less, further preferably 1.5% or less, particularly preferably 1.0% or less, and most preferably 0.8% or less. The heat shrinkage rate referred to in the present invention means that data in the vertical direction and the horizontal direction of the sample film are collected by the measurement method described later, and the larger data is adopted. When the heat shrinkage rate is 2.5% or less, it is preferable that the polymer electrolyte membrane and the catalyst layer can be molded without cracking even by thermoforming at a high temperature of 150 ° C. or higher. However, depending on the adoption conditions, the lower limit of the heat shrinkage rate may be slightly negative data, and is preferably −1.0% or more, for example. It can be said that the most preferable is ± 0%.

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

The means for providing the release layer of the present invention is not particularly limited, but it is preferably provided by coating a polyester film with a solution. By providing by solution coating, a smooth release layer can be provided, and offline annealing treatment can be performed at the same time, which is advantageous in terms of cost.

The solvent used for applying the release agent of the present invention is not particularly limited, and a known solvent can be used. Specific examples of the solvent 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. Classes: Ethers such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosorb), diethylene glycol monobutyl ether (butyl cellosolve), propylene glycol monomethyl ether; aromatic hydrocarbons such as benzene, toluene, xylene, methylcyclohexane Includes amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

The coating method for providing the release layer is not particularly limited, and a known method can be used. For example, a gravure coating method, a die coating method, a reverse coating method, a spray coating method, a curtain coating method, a bar coating method and the like can be mentioned.

The drying temperature after applying the release agent is preferably 90 ° C. or higher, and more preferably 120 ° C. or higher. In particular, when the annealing treatment is performed offline, 130 ° C. or higher is required, and 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, and 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 time, a film having a desired annealing treatment and good heat wrinkles can be obtained.

When annealing offline, the tension applied to the film in the drying oven when the release layer is dried is preferably 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 is not substantially tensioned, the annealing treatment can be performed at the target temperature, and the heat shrinkage rate at 160 ° C. in the MD direction is set to 2.5% or less. be able to. The tension applied to the film was calculated from the following formula.
Tension applied to the film (mN / mm ² ) = Tension in the drying furnace (mN) ÷ Film width (mm) ÷ Film thickness (mm)

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

In order to explain the present invention in detail, examples will be given below, but of course, the present invention is not limited to these examples. The evaluation method used in the present invention is as follows.

(Intrinsic viscosity of polyester resin (dl / g))
According to JIS K 7637-5, a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass) was used as a solvent, and the measurement was carried out at 30 ° C.

(Storage modulus of release film)
Using a dynamic viscoelasticity measuring device (DVA 225 manufactured by IT Measurement Control Co., Ltd.), 30 ° C., 100 ° C. and 150 ° C. in the longitudinal direction (MD) and width direction (TD) of the film under the following conditions. The storage elastic modulus (E') was determined. The measurement was performed in tension mode.
(A) Sample width: 5 mm
(B) Measurement temperature range: 20 to 250 ° C.
(C) Frequency: 10Hz
(D) Temperature rise rate: 10 ° C./min In Table 1, data are listed in the order of "longitudinal direction (MD) / width direction (TD)" of the film, and is it included in the release film of the present invention? Whether or not, if the data in either direction corresponds to the specified range in each temperature measurement, it shall be included.

(Release film haze)
The film haze of the present invention conformed to JIS K 7136 and was measured using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.).

(ΔHz)
For the amount of change in haze after heat treatment at 150 ° C. for 30 minutes, the haze was measured in the same manner after the release film was heat-treated at 150 ° C. for 30 minutes in a hot air oven, and the difference from the haze before heat treatment was calculated. .. That is, the amount of change in film haze before and after heat treatment at 150 ° C. for 30 minutes (ΔHz ₁₅₀ ) (%) is as shown in the following equation.
ΔHz ₁₅₀ (%) = haze after heat treatment (%) -haze before heat treatment (%)

(Oligomer transferability evaluation)
The oligomer transferability of the release film of the present invention was evaluated according to the following criteria. It was evaluated that the lower the Hz ₁₅₀ (%), the smaller the precipitation of oligomers, and there was no deterioration in battery performance due to process contamination or transfer to the catalyst layer.
◯: When ΔHz ₁₅₀ (%) is 0.5% or less Δ: When ΔHz ₁₅₀ (%) is 0.5 to 1.0% or less ×: When ΔHz ₁₅₀ (%) is 1.0% If also large

(Surface roughness)
It is a value measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). For the region surface average roughness (Sa), the average value of 5 measurements was adopted, and for the maximum protrusion height (P), the maximum value of 5 measurements was adopted.
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 50x ・ 0.5 × Tube lens ・ Measurement area 187 × 139μm
Note that (Sa) and (P) in Table 1 show data on the surfaces on which the release layers of the base polyester film are laminated.

(Measurement of heat shrinkage)
A sample film such as a release film (a polyester film as a base material can also be measured in the same manner) 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 heat shrinkage rate was determined according to the following formula (1). The measurement was performed n = 5 times, and the larger heat shrinkage data of the average values of the vertical and horizontal heat shrinkage data of the sample film was adopted, and the heat shrinkage data of the release film or the like was adopted. And. 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 more and then measured.
Thermal shrinkage = {(length before shrinkage-length after shrinkage) / length before shrinkage} x 100 (%) Equation (1)

(Surface free energy)
The contact angles of water, diiodomethane, and bromonaphthalene having known surface tensions were measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd .: fully automatic contact angle meter DM-701) under the conditions of 25 ° C. and 50% RH. .. As the contact angle used in the calculation, the contact angle 10 seconds after dropping each liquid was adopted.
The obtained contact angle data was calculated from the "Kitasaki-Hata" theory to obtain the dispersion component γsd, polar component γsp, and hydrogen bond component γsh of the surface free energy of the release film, and the sum of each component was the surface free energy γs. And said. This calculation was performed using the calculation software in the contact angle meter software (FAMAS).

(Releasability)
The releasability was evaluated as follows by forming a pseudo-catalyst layer using Nafion (registered trademark) (manufactured by DuPont), which is often used for the catalyst layer and the electrolyte membrane.
Pseudocatalyst layer coating liquid (Nafion (registered trademark) and carbon black solids are 2/8 by mass ratio)
20% Nafion (registered trademark) 20Dispersion Solution DE2021 CS type 10.0 parts by mass (manufactured by Wako Pure Chemical Industries, Ltd., solid content 20 wt%)
Carbon black (manufactured by CABOT, VERCANX72R) 8.0 parts by mass Water 24.6 parts by mass Isopropyl alcohol 57.4 parts by mass The pseudocatalyst layer coating solution was dispersed with a centrifugal stirrer to obtain a slurry for the pseudocatalyst layer. The obtained pseudo-catalyst layer slurry was applied onto a release film using an applicator so that the film thickness after drying was 20 μm, and dried in a hot air oven at 90 ° C. for 2 minutes. After drying, heat treatment was performed at 150 ° C. for 10 minutes or 170 ° C. for 10 minutes, and the area of 1 cm × 10 cm was peeled off using a mending tape. Those that could be peeled off were marked with ◯, and those that could not be peeled off were marked with x. In addition, although peeling was possible, the Nafion (registered trademark) layer remained on a part of the release film was marked with Δ.

(Evaluation of crackability of catalyst layer)
Appearance evaluation such as cracking of the catalyst layer was performed as follows.
Pseudocatalyst layer coating liquid (Nafion (registered trademark) and carbon black solids are 2/8 by mass ratio)
20% Nafion (registered trademark) 20Dispersion Solution DE2021 CS type 10.0 parts by mass (manufactured by Wako Pure Chemical Industries, Ltd., solid content 20 wt%)
Carbon black (manufactured by CABOT, VERCANX72R) 8.0 parts by mass Water 24.6 parts by mass Isopropyl alcohol 57.4 parts by mass Prepare the above pseudocatalyst layer coating solution and disperse it with a centrifugal stirrer to obtain a slurry for the pseudocatalyst layer. It was.
The obtained pseudo-catalyst layer slurry was coated 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 pseudo-catalyst layer was cut into a size of 10 cm × 10 cm and heat-treated in a hot air oven at 150 ° C. for 10 minutes or 170 ° C. for 10 minutes to evaluate the state of the pseudo-catalyst layer according to the following criteria.

◯: Good without cracks in the pseudo-catalyst layer Δ: Poor appearance such as cracks was observed in a part of the pseudo-catalyst layer (less than 10% of the total area) ×: Most of the pseudo-catalyst layer (10% of the total area) The above) had poor appearance such as cracks.

(Evaluation of handleability during processing during catalyst layer coating)
The processability evaluation when coating the catalyst layer was performed as follows. A film sample cut to A4 size is coated with the pseudocatalyst layer coating solution using an applicator so that the coating film thickness after drying is 5 μm, and the film is placed in a hot air oven heated to 120 ° C. for 2 minutes and then glass. A sample was placed on a plate and the smoothness of the film was evaluated. The dried film without wrinkles or curls at the edges of the film was evaluated as ◯, and the film with wrinkles or curls at the edges of the film was evaluated as ×.

(Evaluation of pressure uniformity in the transfer process)
The pressure uniformity evaluation in the transfer step of the catalyst layer was performed as follows. Using an applicator, the pseudo-catalyst layer coating solution is applied onto a release film so that the film thickness after drying is 20 μm, and dried in a hot air oven at 90 ° C. for 2 minutes to obtain a pseudo-catalyst layer transfer film. Created. Next, as a pseudo-electrolyte film, Nafion (registered trademark) (20Dispersion Solution DE2021 CS type) was applied to a 12 μm-thick PET film (E5100-12 μm manufactured by Toyobo Co., Ltd.) so that the film thickness would be 10 μm after drying. A pseudo-electrolyte film was prepared by drying at ° C for 2 minutes. The catalyst layer laminated surface of the prepared pseudo-catalyst layer transfer film and the electrolyte laminated surface of the pseudo-electrolyte film were overlapped and pressed for 30 seconds under a pressure of 50 kgf / cm ² with a press machine heated to 150 ° C. Then, the case where the film was peeled off and the catalyst layer transferred to the pseudo-electrolyte film was uniformly transferred was evaluated as ◯, and the case where the press uniformity was partially poor and the transfer residue was evaluated as x.

(Manufacturing of polyester film A)
A copolymerized polyester chip having an intrinsic viscosity of 0.69 dl / g, which comprises 100 mol% of terephthalic acid unit as an aromatic dicarboxylic acid component, 40 mol% of ethylene glycol unit and 60 mol% of neopentyl glycol unit as a diol component. Polyester (A) having an intrinsic viscosity of 0.69 dl / g and containing 0.09% by mass of silica particles (manufactured by Fuji Silicia Chemical Co., Ltd., Silicia 310, average particle diameter (SEM method) 2.7 μm). Each of the terephthalate chips (B) was dried. Further, the chips (A) and the chips (B) were mixed so as to have a mass ratio of 25:75. Next, these chip mixtures are melt-extruded from the slit of the T-die at 270 ° C. by an extruder, rapidly cooled and solidified on a chill roll having a surface temperature of 40 ° C. A stretched sheet was obtained.

The obtained unstretched sheet was stretched 3.3 times in the longitudinal direction at 90 ° C. between the heating roll and the cooling roll. Next, the uniaxially stretched film was guided to a tenter and preheated at 120 ° C. for 10 seconds, and the first half of the transverse stretching was stretched 3.9 times at 110 ° C. and the second half at 100 ° C. Further, a heat-fixing treatment was performed at 235 ° C. while performing a relaxation treatment of 7% in the lateral direction to obtain a biaxially stretched polyester film having a thickness of 50 μm.

In the heat fixing treatment zone, an intermediate section of 2 m is provided between the stretched section and a far infrared heater is installed in the heating section of the heat fixing zone, and the limit position where the shielding plate for each section does not come into contact with the film. Expanded to and installed. Even in the cooling section after heating, the section shielding is strengthened, the external return method is used as the clip return method, a clip cooling device is installed, and forced cooling is performed with cold air of 20 ° C, and the clip temperature at the tenter outlet is set to 40. Measures were taken to prevent clip fusion at ℃ or less.

(Adjustment of coating liquid 1)
Dimethyl terephthalate (95 parts by mass), dimethyl isophthalate (95 parts by mass), ethylene glycol (35 parts by mass), neopentyl glycol (145 parts by mass), zinc acetate (0.1 parts by mass) and antimony trioxide (0. 1 part by mass) was placed in a reaction vessel, and a transesterification reaction was carried out at 180 ° C. for 3 hours. Next, 5-sodium sulfoisophthalic acid (6.0 parts by mass) was added, and the esterification reaction was carried out at 240 ° C. for 1 hour, and then at 250 ° C. under reduced pressure (10 to 0.2 mmHg) for 2 hours. The polycondensation reaction was carried out to obtain a copolymerized polyester (1) having a number average molecular weight of 19,500 and a softening point of 60 ° C.

The coating liquid 1 was adjusted with the following composition. After the adjustment, microfiltration was performed with a felt-type polypropylene filter having a filtered particle size (initial filtration efficiency: 95%) of 10 μm to obtain a coating liquid 1.
Water 59.88% by mass
Isopropyl alcohol 25.70% by mass
Water dispersion of copolymerized polyester film (1) (solid content 30% by mass) 13.33% by mass
Snowtex (registered trademark) XL 1.00% by mass
(Coroidal silica, manufactured by Nissan Chemical Industries, Ltd., average particle size 40 nm, solid content 40% by mass)
MP-4540 0.04% by mass
(Coroidal silica, manufactured by Nissan Chemical Industries, Ltd., average particle size 450 nm, solid content 40% by mass)
Surfactant Fluorine-based nonionic type 0.05% by mass
(Made by DIC, Mega Fvck F444)

(Manufacturing of polyester film B)
It contains 100 mol% of terephthalic acid unit as an aromatic dicarboxylic acid component, 70 mol% of ethylene glycol unit as a diol component, and 30 mol% of 1,4-cyclohexanedimethanol unit, and has an intrinsic viscosity of 0.71 dl / g. The polymerized polyester chip (C) and the polyethylene terephthalate chip (D) having an intrinsic viscosity of 0.69 dl / g (without particles) were mixed and dried so as to have a mass ratio of 50:50. Next, these chip mixtures are melt-extruded from the slit of the T-die at 270 ° C. by an extruder, rapidly cooled and solidified on a chill roll having a surface temperature of 40 ° C. A stretched sheet was obtained.

The obtained unstretched sheet was stretched 3.5 times in the longitudinal direction at 90 ° C. between the heating roll and the cooling roll. Next, the coating liquid 1 was applied to one side of the uniaxially stretched film by a reverse kiss coating method so that the resin solid content before stretching was 0.2 μm. The laminated film having the coating layer was guided to a tenter while drying, preheated at 120 ° C. for 10 seconds, and the first half of the transverse stretching was stretched at 105 ° C. and the latter half at 100 ° C. for 3.9 times. Further, a heat fixing treatment was performed at 220 ° C. while performing a 7% relaxation treatment in the lateral direction to obtain a biaxially stretched polyester film having a thickness of 50 μm.

In the heat fixing treatment zone, an intermediate section of 2 m is provided between the stretched section and a far infrared heater is installed in the heating section of the heat fixing zone, and the limit position where the shielding plate for each section does not come into contact with the film. Expanded to and installed. Even in the cooling section after heating, the section shielding is strengthened, the external return method is used as the clip return method, a clip cooling device is installed, and forced cooling is performed with cold air of 20 ° C, and the clip temperature at the tenter outlet is set to 40. Measures were taken to prevent clip fusion at ℃ or less.

(Manufacturing of polyester film C)
A polyethylene terephthalate chip having the above intrinsic viscosity of 0.69 dl / g and containing 0.09% by mass of silica particles (manufactured by Fuji Silysia Chemical Ltd., Cyricia 310, average particle diameter (SEM method) 2.7 μm). (B) and the above-mentioned polyethylene terephthalate chip (D) having an intrinsic viscosity of 0.69 dl / g (without particles) were dried. Further, the chips (B) and the chips (D) were mixed so as to have a mass ratio of 70:30. These chip mixtures were then melt-extruded from the slits of the T-die at 275 ° C. by an extruder.

Then, the extruded resin was cast on a cooling drum having a surface temperature of 30 ° C. and brought into close contact with the surface of the cooling drum by an electrostatic application method to be cooled and solidified to prepare an unstretched film.

The obtained unstretched sheet was heated to 75 ° C. with a roll group heated to 78 ° C., and then heated to 105 ° C. with an infrared heater, and the roll group having a difference in peripheral speed was used in the film longitudinal direction. It was stretched 3.4 times.

Next, the obtained uniaxially stretched film was gripped with a clip and stretched in the film width direction. The stretching temperature in the width direction was 120 ° C., and the stretching ratio in the width direction was 4.0 times. Next, heat treatment was performed at 240 ° C. for 15 seconds, and 3.1% relaxation treatment was performed at 185 ° C. to obtain a polyester film C having a thickness of 50 μm.

Each release agent was adjusted as follows.

(Release agent A-1)
The cyclic polyolefin TOPAS (registered trademark) 6013S (manufactured by Polyplastics) was added to toluene so that the solid content was 2% by mass, and heated in a flask with a cooling tube until the toluene was refluxed to obtain a toluene solution. It was.

(Release agent A-2)
The cyclic polyolefin TOPAS (registered trademark) 6017S (manufactured by Polyplastics) was added to toluene so that the solid content was 2% by mass, and heated in a flask with a cooling tube until the toluene refluxed to obtain a toluene solution. It was.

(Release agent A-3)
The cyclic polyolefin ARTON (registered trademark) G7810 (manufactured by JSR Corporation) was added to toluene so that the solid content was 2% by mass, and the mixture was stirred at room temperature for 12 hours to obtain a toluene solution.

(Release B)
750 mL of 4-methyl-1-pentene and 0.75 mL of a 1.0 mmol / ml toluene solution of triisobutylaluminum were added to an autoclave with a 1.5 L stirrer under nitrogen and stirred. Next, it was heated to 60 ° C. and pressurized with propylene so that the gauge pressure became 0.12 MPa. Next, 1 mmol of methylaminoxane prepared in advance in terms of Al, diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-butyl-fluorenyl) zirconium dichloride 0.34 ml of a toluene solution containing 0.005 mmol of the mixture was press-fitted into an autoclave under nitrogen to initiate a polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the temperature inside the autoclave was 60 ° C. One hour after the start of polymerization, 5 ml of methanol was press-fitted into the autoclave with nitrogen to stop the polymerization, and the autoclave was returned to atmospheric pressure. Then, acetone was added to the reaction solution with stirring, and the powdery polymer containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours. The obtained polymer weighed 34.7 g, and the 4-methyl-1-pentene content in the polymer was 94 mol% and the propylene content was 6 mol%. The melting point (Tm) of the polymer was 200 ° C.
The obtained polymethylpentene polymer was dissolved in methylcyclohexane so as to have a solid content of 2% by mass.

(Example 1)
A release agent A-1 was applied to a polyester film A having a width of 1000 mm and a thickness of 50 μm by a gravure coating method so that the film thickness after drying was 100 nm, and then dried at 170 ° C. for 9 seconds. At this time, the tension in the drying oven was adjusted to 40 N / m (the unit is the tension (N) per 1 m of width), and the annealing treatment was performed at the same time to obtain a release film.

(Example 2)
A release film was obtained by processing in the same manner as in Example 1 except that the release agent was changed to A-2.

(Example 3)
A release film was obtained by processing in the same manner as in Example 1 except that the release agent was changed to A-3.

(Example 4)
A release film was obtained by processing in the same manner as in Example 1 except that the release agent was changed to B.

(Example 5 )
A release film was obtained by processing the polyester film B in the same manner as in Example 1 except that the release agent A-2 was applied .

(Example 6 )
A release film was obtained by processing in the same manner as in Example 5 except that the drying temperature was changed to 130 ° C.

(Example 7 )
A release film was obtained by processing in the same manner as in Example 5 except that the drying temperature was changed to 150 ° C.

(Example 8 )
Mold release by processing in the same manner as in Example 5 except that the drying conditions were changed to 175 ° C. for 75 seconds and the tension in the drying furnace was changed to 12 N / m (the unit is the tension (N) per 1 m of width). I got a film.

(Example 9 )
Mold release by processing in the same manner as in Example 2 except that the drying conditions were changed to 120 ° C. for 30 seconds and the tension in the drying furnace was changed to 120 N / m (unit is tension (N) per 1 m of width). I got a film.

(Comparative Example 1)
Example 2 and Example 2 except that the release agent A-2 was applied to one side of the polyester film C having a width of 1000 mm and a thickness of 50 μm by a gravure coating method so that the film thickness after drying was 100 nm. A release film was obtained by the same processing.

(Reference example 1)
Evaluation was performed using a PTFE sheet having a thickness of 50 μm (Nachias Corporation Naflon (registered trademark) PTFE sheet TOMBO No. 9000).

The release films of Examples and Comparative Examples were evaluated and summarized in Table 1.

According to the invention, as a release film preferably used for electronic component manufacturing applications such as solid polymer fuel cell member molding applications, transfer is performed while maintaining handleability during processing during catalyst layer coating. The pressure uniformity in the process can be improved, and a release film having excellent transferability can be provided.

Claims (5)

A release film for molding a polymer electrolyte fuel cell member , which has a release layer on at least one side of the polyester film, and has a storage elastic modulus of 1000 MPa or more at 30 ° C. and at 100 ° C. The storage elastic modulus is 800 MPa or less,
The polyester film is a mixture of polyester and polyethylene terephthalate containing terephthalic acid, ethylene glycol and neopentyl glycol as constituents, or polyester and polyethylene containing terephthalic acid, ethylene glycol and 1,4-cyclohexanedimethanol as constituents. Contains a mixture with terephthalate,
Release film for molding polymer electrolyte fuel cell members . The release film for molding a polymer electrolyte fuel cell member according to claim 1, wherein the storage elastic modulus at 150 ° C. is 100 MPa or less and 20 MPa or more. The solid polymer fuel cell member molding according to claim 1 or 2 , wherein the total value of the polar component of the surface free energy and the hydrogen bond component on the surface of the release layer is 8 mJ / m ² or less . release film. The release layer for molding a polymer electrolyte fuel cell member according to any one of claims 1 to 3, wherein the release layer contains at least one resin selected from an olefin resin and a fluororesin. Mold film. The release film for molding a polymer electrolyte fuel cell member according to claim 4, wherein the olefin resin is cyclic polyolefin or polymethylpentene.