JP6911322B2 - 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.

For example, 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 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 fluorine-based resin film typified by polytetrafluoroethylene (PTFE) is conventionally often used. The fluorine-based resin film is widely used because it is not contaminated with silicone or the like and has high chemical resistance and heat resistance. 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, since the fluorine-based resin film is expensive, there is a problem that the manufacturing cost is high.

Due to the above circumstances, a proposal has been made to use a PET film provided with a release layer as the support film. It has been reported that a film provided with a release layer on a PET film is cheaper than a fluorine-based film, has excellent processability, and has transferability (see, for example, Patent Documents 1 to 3).

However, organic components such as silicone resin, olefin resin, and fluorine resin are used in the release layer provided on the reported PET film, and when used as a molding film for electronic component members, There was a risk that low molecular weight substances such as oligomers contained in the resin used for the release layer and decomposition products generated during high temperature treatment would be mixed into the molded electronic parts and deteriorate the performance.

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

In view of the above circumstances, the present invention has been made in the background of the problems of the prior art, and provides a release film having excellent transferability even when used at a high temperature and suitable for molding high-performance electronic components. There is.

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, wherein the release layer is a metal thin film layer.
2. The release film according to the first aspect, wherein the surface free energy of the surface of the release layer is 40 mJ / m ^{2 or more.}
3. 3. The release film according to the first or second above, wherein the heat shrinkage rate after heat treatment at 160 ° C. for 30 minutes is 1.0% or less.
4. The release film according to any one of the above 1 to 3, wherein the thickness of the metal thin film layer is 100 nm or less.
5. The release film according to any one of the above 1 to 4, wherein the surface roughness (Sa) of the surface of the release layer is 50 nm or less.
6. The release film according to any one of the above 1 to 5, wherein the haze is 20% or less and the total light transmittance is 1% or more.
7. The metal thin film layer is Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, Pd, Ag, In, Sn, Ta, W, Re, Ir, Pt, Au, Tl. The release film according to any one of the above 1 to 6, which contains one or more metals selected from Pb and Pb.

According to the present invention, as a release film preferably used for electronic component manufacturing applications represented by solid polymer fuel cell member molding applications, oligomers and decomposition products are precipitated in the release layer even after high temperature treatment. Since the amount is small, it is possible to provide a release film having excellent transferability.

Hereinafter, the present invention will be described in detail.

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, and the release layer is a metal thin film layer. As a result of diligent studies to solve the above problems, the inventors have found that a film provided with a metal thin film layer as a release layer on at least one side of the polyester film solves the above problems. That is, they have found that by laminating a metal thin film layer on at least one surface of a polyester film, it is possible to obtain a release film that has excellent transferability even after high temperature treatment and is peeled off at the interface between the metal thin film layer and the molded electronic component. .. Furthermore, it has been found that since metal itself has high heat resistance, it is difficult to decompose even at high temperatures, and the possibility that the performance of molded electronic components deteriorates is low.

Many films in which a metal thin film layer is laminated on these polyester films are known, but few reports suggest that they can be used as a release film. For example, Japanese Patent Application Laid-Open No. 2010-76405 proposes a transfer printing sheet in which an ink layer is formed on a vapor-deposited surface of a film in which silica or alumina is vapor-deposited on at least one side of the film. In order to peel off, it is necessary to stretch the ink layer and deform the ink layer, and the ink layer cannot be peeled off without stretching. Therefore, from the findings so far, a polyester film provided with a metal thin film layer as a release layer as in the present invention can be used as a release film for electronic component manufacturing applications represented by solid polymer fuel cell member molding applications. I couldn't imagine it could be done. On the other hand, the present inventors have made the present invention as a result of repeated studies focusing on the chemical resistance, solvent resistance, and heat resistance of the metal. Further, as a particularly preferable embodiment, the release film of the present invention has a high surface free energy and is excellent in coatability when coating a slurry of a polymer electrolyte fuel cell molding member, so that a uniform film can be obtained. It can be formed, the thickness uniformity of the molded member can be improved, and the performance of the polymer electrolyte fuel cell can be improved.

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

The material of the polyester resin is not particularly limited, but a copolymer formed by polycondensing a dicarboxylic acid component and a diol component, or a blended resin thereof can be used. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenyl. Caroxydate, diphenoxyetanedicarboxylic acid, diphenylsulfoncarboxylic acid, anthracendicarboxylic 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 , Dimeric 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, and 1,3-. Examples thereof include propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.

The dicarboxylic acid component and the diol component constituting 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. When a plurality of dicarboxylic acid components and diol components are copolymerized, it is preferable that the repeating structural unit of ethylene terephthalate is contained in an amount of 50 mol% or more.

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

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

In the present invention, the thickness of the polyester film is not particularly limited, but is preferably in the range of 12 to 125 μm. 12 to 75 μm is more preferable, and 16 to 50 μm is even more preferable. If it is 12 μm or more, there is no risk of wrinkles during molding and transfer of the resin layer, and if it is 125 μm or less, it is advantageous in terms of cost.

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 antioxidants, lightfasteners, antigelling agents, organic wetting agents, antistatic agents, ultraviolet absorbers, surfactants 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 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 longitudinal uniaxial stretching method, a horizontal uniaxial stretching method, a longitudinal / horizontal sequential biaxial stretching method, a longitudinal / horizontal simultaneous biaxial stretching method, and the like can be adopted.

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

(Metal thin film layer)
The metal thin film layer in the present invention is not particularly limited, and any metal compound can be used. The metal refers to a simple substance belonging to a transition metal or a main group metal in the periodic table, or an oxide, a nitride, or an alloy thereof. For example, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, Pd, Ag, In, Sn, Ta, W, Re, Ir, Pt, Au, Tl, Pb, etc. Transition metals and main group metals represented by the element symbols of can be used, and each of them may be used alone or their oxides may be used. It is easy to reflect and is preferable. The metal thin film layer may contain other components as long as this property is not lost.

For the metal thin film layer of the present invention, a metal having a low affinity for carbon used in the catalyst layer can be preferably used, especially in the application of forming the catalyst layer of the polymer electrolyte fuel cell. Although it is not theoretically clear, the present inventors preferably use, for example, Al, Ti, Cr, Ta, W, Pt, Au, Mo and the like as a metal having a low affinity for carbon in various experiments. Other metals such as Cu and Ni can also be used. For the catalyst layer of the polymer electrolyte fuel cell, for example, an electrolyte polymer (for example, a sulfonic acid-based resin composed of perfluorocarbon (-CF2-)) was used as a binder for carbon particles supporting Pt as a catalyst. It is configured. In recent years, the catalyst layer has a structure in which the ratio of Pt-supported carbon in the catalyst layer is increased from the viewpoint of power generation efficiency, and the strength of the catalyst layer is weak and becomes brittle. Therefore, Pt-supported carbon tends to remain in the release layer, and by using a metal having a low affinity for carbon for the release layer, it can be suitably used as a release film for molding a polymer electrolyte fuel cell.

The identification of the metal used in the metal thin film layer of the present invention can be qualitatively or quantitatively analyzed by using an analysis method such as ICP emission spectroscopy or fluorescent X-ray analysis. Further, the method is not limited to these, and other inorganic analysis methods can also be used.

The film thickness of the metal thin film layer of the present invention is not particularly limited, but is preferably 5 to 400 nm, more preferably 7 to 100 nm, and even more preferably 7 to 30 nm from the viewpoint of transferability and productivity. Is. When it is 5 nm or more, the film tends to be uniform and sufficient transferability can be obtained, which is preferable. Further, when it is 400 nm or less, the manufacturing cost can be suppressed, which is preferable. For applications that require transparency, the upper limit of the thin film is preferably 100 nm or less. Above 100 nm, the luster peculiar to metal reduces transparency.

The film thickness of the metal thin film layer of the present invention can be measured by observing the cross section with a transmission electron microscope. It can also be measured by using other inorganic analyzes such as ICP emission spectroscopic analysis, atomic absorption spectrometry, and fluorescent X-ray analysis.

A known production method can be used for forming the metal thin film layer as long as the object of the present invention is not impaired. For example, a PVD method (physical vapor deposition method) such as a vacuum deposition method, a sputtering method, and an ion plating method, or a CVD method (chemical vapor deposition method) can be mentioned. In particular, the vacuum deposition method and the sputtering method are preferable from the viewpoint of production speed and stability. In the vacuum deposition method, a single metal (Al, Au, Ti, etc.) can be used as the vapor deposition source material, and resistance heating, high-frequency induction heating, electron beam heating, etc. are used as the heating method. Can be done. Further, as the reactive gas, oxygen, nitrogen, water vapor or the like can be introduced, or reactive vapor deposition using means such as ozone addition and ion assist can be used, but in order to obtain the properties peculiar to the metal, the reaction can be used. It is preferable not to let it. Further, the film forming conditions may be changed as long as the object of the present invention is not impaired, such as applying a bias to the substrate, raising the substrate temperature, or cooling the substrate.

The release film used in the present invention preferably has a small heat shrinkage rate. For example, the shrinkage rate when treated at 160 ° C. for 30 minutes by the heat shrinkage rate measuring method described later is preferably 1.0% or less, more preferably 0.8% or less, still more preferably. It is 0.4% or less, and particularly preferably 0.3% or less. When the heat shrinkage rate is 1.0% or less, the deformation of the release film is reduced during the heat treatment, the deformation of the molded electronic component is suppressed, and there is no risk of performance deterioration, which is preferable. Therefore, when used as a release film for molding a polymer electrolyte fuel cell member, cracking of the catalyst layer can be effectively suppressed even in a process in which a high temperature of 150 ° C. or higher is applied, which is suitable. Regarding the lower limit of the heat shrinkage rate, although some negative data may be obtained, 0% is the most preferable, and 0.1% or more may be used.

In order to suppress the heat shrinkage rate of the release film of the present invention, the polyester film may be annealed during film formation (that is, in-line) or may be annealed offline.

The region surface average roughness (Sa) of the release layer surface of the release film used in the present invention is preferably in the range of 50 nm or less, more preferably 30 nm or less, and further preferably 10 nm or less. It can be said that the smaller the region surface average roughness (Sa) on the surface of the release layer of the release film is, the better, but it may be 1 nm or more, and may be 2 nm or more. The maximum protrusion height (P) 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, pinholes and the like are unlikely to occur in the molded product obtained by using the release film, so that it can be suitably used.

The region surface average roughness (Sa) on the opposite surface of the release layer of the release film used in the present invention is not particularly limited, but is preferably in the range of 1 to 50 nm.

The release film of the present invention preferably has high transparency, and the film haze is preferably 20% or less. More preferably, it is 10% or less, and even more preferably 8% or less. A film haze of 20% or less is preferable because defect detection and visual inspection can be performed accurately when an electronic component or the like is molded.

The total light transmittance of the release film of the present invention is preferably 1% or more, more preferably 20% or more, further preferably 40% or more, still more preferably 60% or more. If the total light transmittance is lower than 1%, the transparency of the release film is lowered, and it is difficult to detect defects with a transmission type defect inspection device or the like, which is not preferable.

The release film of the present invention preferably has a low contact angle with a liquid such as water in order to improve the wettability when the slurry is applied and molded on the release film and to form a uniform film. For example, in the case of water, 70 degrees or less is preferable, 50 degrees or less is more preferable, and 30 degrees or less is still more preferable. Further, in the case of diiodomethane, the temperature is preferably 50 degrees or less. For 1-bromonaphthalene, 50 degrees or less is preferable, 35 degrees or less is more preferable, and 25 degrees or less is still preferable. Although the lower limit has a problem in measurement accuracy, it may be 3 degrees or more, 5 degrees or more, or 8 degrees or more for each liquid.

The surface free energy of the release layer of the release film of the present invention ^{is preferably 40 mJ / m 2} or more. More preferably, it is 60 mJ / m ² or more. When the surface free energy is 40 mJ / m ² or more, the coatability of the slurry is improved during coating and molding, and the thickness uniformity of the molded polymer electrolyte fuel cell member is improved, which is preferable. As a general release film, non-silicone materials such as silicone and olefin are used, but the surface free energy of the release film using them ^{is often lower than 40 mJ / m 2} , and the slurry. There are problems such as being easy to play during coating, and the release film of the present invention can solve such problems.

As long as the release film of the present invention has the function of the present invention, a functional layer may be laminated in addition to the release layer. Examples of the functional layer to be laminated include an antistatic layer, an antiblocking layer, an easy slip layer, a hard coat layer, an ultraviolet absorbing layer, an easy adhesive layer, an adhesive layer and the like. When laminating the functional layer, it is necessary not to hinder the releasability of the present invention, and the place of laminating is between the releasing layer and the polyester film, or the releasable layer of the polyester film is laminated. The other side. These layers may be one layer or two or more layers.

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.

(Thickness of metal thin film)
The cut release film was embedded in resin and ultrathin sectioned using an ultramicrotome. Then, using a JEM2100 transmission electron microscope manufactured by JEOL Ltd., observation was performed directly at a magnification of 20,000, and the thickness of the metal thin film layer was measured from the observed TEM image.

(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: 10x-0.5 x Tube lens Note that (Sa) and (P) in Table 1 show data on the surface on which the release layer of the base polyester film 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 heat shrinkage rate was determined according to the following formula (1). The measurement was performed n = 5 times, and the larger heat shrinkage rate data of the average values of the heat shrinkage rate data in the vertical direction and the horizontal direction of the sample film was adopted, and the heat shrinkage rate data of the release film was used. 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 more, and then the measurement was performed.
Thermal shrinkage = {(length before shrinkage-length after shrinkage) / length before shrinkage} x 100 (%) Equation (1)

(Contact angle)
Water (droplet volume 1.8 μL) on the release surface of the release film 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. , Diiodomethane (appropriate amount of liquid 0.9 μL) and 1-bromonaphthalene (appropriate amount of liquid 0.9 μL) were prepared and their contact angles were measured. As the contact angle, the contact angle 10 seconds after dropping each liquid on the release film was adopted.

(Surface free energy)
The contact angle data of water, diiodomethane, and 1-bromonaphthalene obtained by the above method was calculated from the "Kitasaki-Hata" theory, and the dispersion component γsd, polar component γsp, and hydrogen bond component γsh of the surface free energy of the release film were obtained. The sum of each component was taken as the surface free energy γs. This calculation was performed using the calculation software in the contact angle meter software (FAMAS).

(Haze of release film, total light transmittance)
The film haze of the present invention was measured according to JIS K 7136, and the total light transmittance was measured according to JIS K 7361, using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.).

(Evaluation of transferability)
The transferability was carried out by the following method. 20% Nafion (registered trademark) Dispersion Solution DE2021 CS type (manufactured by Wako Pure Chemical Industries, Ltd.) and carbon black (manufactured by CABOT, VERCANX72R) are mixed so as to have a mass ratio of 1/9, and the total solid content is Was adjusted to 10% with isopropanol / water (mass ratio 8/2), and then dispersed with a centrifugal stirrer for 30 minutes to obtain a slurry for a 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 10 μm, and dried in a hot air oven at 90 ° C. for 2 minutes. Then, after heat-treating at a predetermined temperature for 10 minutes in a hot air oven and returning to room temperature, the mending tape was peeled off at an angle of 180 ° using a mending tape. Transcription was evaluated according to the following criteria. The predetermined temperature was 120 ° C., 140 ° C., 160 ° C., and 180 ° C. at four levels.

◯: No pseudo-catalyst layer remained on the release film.
Δ: The pseudocatalyst layer remained slightly on the release film.
(At a level where it can be recognized that the pseudo-catalyst layer remains when observed on a white mount)
X: The pseudocatalyst layer clearly 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)

(Evaluation of crackability of catalyst layer)
Appearance evaluation such as cracking of the catalyst layer was performed as follows. First, 20% Nafion (registered trademark) Dispersion Solution DE2021 CS type (manufactured by Wako Pure Chemical Industries, Ltd.) and carbon black are mixed so as to have a weight ratio of 3/7, dispersed by a centrifugal stirrer, and a pseudo-catalyst layer. Slurry was obtained. The obtained pseudo-catalyst layer slurry was applied onto 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 at 150 ° C. for 5 minutes in a hot air oven to evaluate the state of the pseudo-catalyst layer according to the following criteria.

◯: Good with almost no 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) % Or more) showed poor appearance such as cracks

(Examples 1 to 11)
A polyethylene terephthalate film having a width of 500 mm and a thickness of 50 μm (part number E5100, manufactured by Toyobo Co., Ltd.) annealed under the following annealing condition (1) was put into a vacuum chamber and evacuated to 1.5 × 10 ^-4 Pa. .. Next, argon was introduced to adjust the total pressure to 0.5 Pa. A metal thin film layer was formed by applying power to the target of the metal type shown in Table 1 at a power density of 2 W / cm2, and at a film temperature of 25 ° C. by a DC magnetron sputtering method. The film thickness of the metal thin film layer was controlled by changing the speed at which the film passed over the metal target. The film temperature was substituted by the temperature of the temperature medium of the temperature controller that controls the temperature of the roll on which the film is in contact traveling.
・ Annealing condition (1)
Tension in the drying oven: 40 N / m (Unit is tension per 1 m of width (N))
Drying temperature: 170 ° C
Drying time: 9 seconds

(Example 12)
A release film was prepared in the same manner as in Example 1 except that the polyethylene terephthalate film having a thickness of 50 μm to be used was changed to Cosmo Shine (registered trademark) product number A4300 (manufactured by Toyobo Co., Ltd.).
Cosmo Shine (registered trademark) product number A4300 is a highly smooth film in which easy-adhesion layers are coated on both sides. The release surface of the release film produced using this film also has high smoothness, and even if the catalyst layer or the like is molded, defects such as pinholes are less likely to occur.

( Reference example 13)
Before forming the metal thin film layer, a release film was prepared in the same manner as in Example 1 except that the metal thin film layer was not annealed.

(Example 14)
Before forming the metal thin film layer, a release film was prepared in the same manner as in Example 1 except that the metal thin film layer was annealed under the following annealing condition (2).
・ Annealing condition (2)
Tension in the drying oven: 40 N / m (Unit is tension per 1 m of width (N))
Drying temperature: 130 ° C
Drying time: 9 seconds

(Example 15)
Before forming the metal thin film layer, a release film was prepared in the same manner as in Example 1 except that the metal thin film layer was annealed under the following annealing condition (3).
・ Annealing condition (3)
Tension in the drying oven: 40 N / m (Unit is tension per 1 m of width (N))
Drying temperature: 130 ° C
Drying time: 5 seconds

(Comparative Example 1)
A non-corona-treated surface of a polyethylene terephthalate film (trade name E5100, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm without a metal thin film layer was used.

(Comparative Example 2)
2 parts by mass of a cyclic polyolefin resin (TOPAS (registered trademark) 6017S, manufactured by Polyplastics Co., Ltd.) was dissolved in 78 parts by mass of toluene, and 20 parts by mass of tetrahydrofuran was further added to prepare the coating liquid 1. The coating liquid 1 is applied to the corona-treated surface of a polyethylene terephthalate film (trade name E5100, manufactured by Toyobo Co., Ltd.) having a width of 500 mm and a thickness of 50 μm with a gravure coater so that the film thickness after drying becomes 100 nm, and the film is applied at 140 ° C. for 30 seconds. It was dried to prepare a release film.

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

According to the present invention, as a release film preferably used for electronic component manufacturing applications represented by solid polymer fuel cell member molding applications, oligomers and decomposition products are precipitated in the release layer even after high temperature treatment. Since the amount is small, it is possible to provide a release film having excellent transferability.

Claims (6)

A release film having at least one surface a release layer of the polyester film,
Wherein Ri release layer metal thin film layer der,
A release film having a heat shrinkage rate of 1.0% or less after being heat-treated at 160 ° C. for 30 minutes. The release film according to claim 1, wherein the surface free energy of the surface of the release layer is 40 mJ / m ^{2 or more.} The release film according to claim 1 or 2 , wherein the thickness of the metal thin film layer is 100 nm or less. The release film according to any one of claims 1 to 3 , wherein the surface roughness (Sa) of the surface of the release layer is 50 nm or less. The release film according to any one of claims 1 to 4 , wherein the haze is 20% or less and the total light transmittance is 1% or more. The metal thin film layer is Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, Pd, Ag, In, Sn, Ta, W, Re, Ir, Pt, Au, Tl. The release film according to any one of claims 1 to 5 , wherein the release film contains one or more metals selected from Pb and Pb.