RELEASE FILM AND METHOD FOR MANUFACTURING RELEASE FILM.

Abstract

A release film with electrostatic dissipation properties is provided. The present invention provides a release film comprising a base layer formed from a polyester resin and a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, and the release film having a surface resistivity Rs of 1 x 10¹¹ Ω or less. Preferably, the electrically conductive filler comprises carbon black, and the tetrafluoroethylene resin further comprises particles having an average particle size of 1 µm to 15 µm determined by laser diffraction particle size analysis.

Description

RELEASE FILM AND METHOD FOR MANUFACTURING RELEASE FILM Technical Field The present invention relates to a release film and a method for manufacturing the film; more specifically, it relates to a release film used to seal a semiconductor device and a method for manufacturing the film; and further specifically, it relates to a release film used for transfer molding or compression molding and a method for manufacturing the film. Prior Art To seal a semiconductor device with a resin, a molding technique such as transfer molding or compression molding is used. In this molding technique, a release film is frequently used to facilitate the release of a molded item from a mold after the resin has cured in the mold, and several release films have been developed. For example, Patent Document 1 describes a release film comprising a coated film formed from a composition containing a fluorine resin (A) having a functional group X and a release component (B) and comprising a layer formed from a non-fluorinated polymer. Patent Document 2 describes a gas barrier release film for semiconductor resin molding. The release film comprises at least a release layer (I) having excellent mold release properties and a plastic support layer (II) supporting the release layer. The plastic support layer (II) has a tensile strength of 1 MPa to 50 MPa at 200% elongation at 170°C, and the release film has a xylene gas permeability of 5 x 10¹⁵ (kmol⁻¹ / (s⁻¹·m²⁻¹·kPa)) at 170°C. List of References Patent Documents Patent Document 1: JP-A No. 2015-74201 Patent Document 2: WO2008 / 020543 Brief Description of the Invention Technical Problem A release film is used to facilitate the release of a molded item from a mold, as described above. It is desirable that the release film be easily released from the molded item after the resin has cured. In the fabrication of semiconductor devices, it is necessary to prevent electrostatic destruction. Electrostatic destruction is caused by electrostatic discharge (ESD). ESD destruction of a semiconductor device can be caused by the instantaneous discharge of a charged conductor (or another semiconductor device). ESD causes discharge current to flow in a semiconductor device, and the resulting local heat generation and / or electric field concentration can destroy the device. In recent years, rapid progress in the miniaturization of semiconductor devices has made them more vulnerable to ESD. To prevent electrostatic discharge (ESD), semiconductor device manufacturing lines are equipped with electrostatic destruction prevention measures, such as antistatic devices. However, equipping these lines can increase manufacturing costs. If electrostatic dissipation properties can be imparted to a release film used, for example, in a sealing stage of a semiconductor device during manufacturing, ESD at the sealing stage can be prevented at a lower cost. In view of the above circumstances, the present invention is primarily proposed to provide a release film having an electrostatic dissipation property. Solution to the Problem rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y The inventors of the present invention have found that a release film having a specific configuration has excellent mold release properties and is suitable for electrostatic dissipation properties. The present invention provides a release film comprising a base layer formed from a polyester resin and a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, and the release film has a surface resistivity Rs of 1 x 1011Ω or less. According to one aspect of the present invention, the electrically conductive filler may comprise carbon black, and the tetrafluoroethylene resin may further comprise particles having an average particle size of 1 μm to 15 μm as determined by laser diffraction particle size analysis. In appearance, carbon black may include ketjen black. Ketjen black can have a DBF oil absorption amount of 250 ml / 100 go more. Carbon black may also include furnace black. In appearance, carbon black may include furnace black. rzbbnn / zznz / E / Y The particles can be inorganic particles. Inorganic particles can be silicon dioxide particles. According to another aspect of the present invention, the electrically conductive filler may comprise carbon black, and the carbon black may comprise ketjen black and furnace black. The polyester resin may be a polyethylene terephthalate resin. Polyester resin can have a glass transition temperature of 60°C to 95°C. The surface layer can be laminated onto one side of the two sides of the base layer. On the other side of the two sides of the base layer, a surface layer formed from a fluororesin can be laminated. The release film of the present invention can be used to seal a semiconductor device. In sealing, the release film can be positioned so that the surface layer formed from the tetrafluoroethylene resin comprising the electrically conductive filler comes into contact with a sealing resin. The release film of the present invention can be used for transfer molding or compression molding. The release film of the present invention can be used for molding two or more times. The present invention also provides a method for manufacturing a release film. The method comprises a surface layer forming step for forming, on one face of the two faces of a base layer formed from a polyester resin, a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, and the manufactured release film has a surface resistivity Rs of 1 x 10¹¹ Ω or less. Advantageous Effects of the Invention According to the present invention, a release film is provided that has excellent mold release properties and an electrostatic dissipation property. The effect of the invention is not necessarily limited to that described in this paragraph and may be any of the effects described herein. Brief Description of the Drawings Fig. 1 is a view showing an example structure of a release film of the present invention. Figs. 2A, 2B, 2C, 2D and 2E are views showing an example use of a release film of the present invention in transfer molding. Figures 3A, 3B, 3C and 3D are views showing an exemplary use of a release film of the present invention in compression molding. Description of Modalities The embodiments for carrying out the present invention will now be described in detail. The embodiments described below are merely examples of typical embodiments of the present invention, and the present invention is not limited to these embodiments. 1. First modality (release film) (1) Description of the first modality A release film of the present invention comprises a base layer formed from a polyester resin and a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler and having a surface resistivity Rs of 1 x 10⁻¹¹ Ω or less. With the surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, the release film may have a surface resistivity Rs no greater than the above upper limit, or the release film may have an electrostatic dissipation property. With a combination of the surface layer and the base layer, the release film of the present invention may exhibit excellent mold release properties and has an electrostatic dissipation property. The surface resistivity Rs of the release film of the present invention is, as described above, 1 x 10¹¹ Ω or less and may preferably be less than 1 x 10¹¹ Ω, more preferably 1 x 10¹⁰ Ω or less, more preferably 1 x 10⁹ Ω or less, and particularly preferably 1 x 10⁸ Ω or less, 5 x 10⁷ Ω or less, 3 x 10⁷ Ω or less, or 1 x 10⁷ Ω or less. The surface resistivity Rs of the release film of the present invention is, for example, 1 x 10³ Ω or more, particularly 5 x 10³ Ω or more, and more particularly 1 x 10⁴ Ω or more. Having a surface resistivity Rs within the numerical range above, the release film of the present invention can prevent ESD during a sealing stage of a semiconductor device. The surface resistivity Rs is determined in accordance with International Electrotechnical Commission (IEC) standard 61340-5-1.The measurement is specifically carried out by the following procedure: first, a 10 cm x 10 cm release film sample is prepared; a main measuring electrode (an electrode size of φ50 mm) and a protective electrode (an outer diameter of φ80 mm, an inner diameter of φ70 mm) of, for example, a digital ultra-high resistance meter / microammeter (ADCMT5451, ADC Corporation) are brought into contact with a side surface layer of the molded sample article; a voltage of 10 V is applied to the sample with these electrodes; and the surface resistivity Rs is determined. For example, to impart electrostatic dissipation properties to a single-layer release film, an electrically conductive filler could be added to a resin forming the single-layer release film. However, a single-layer release film comprising an electrically conductive filler is likely to have reduced film properties (specifically strength and elongation), such as film strength. Furthermore, such a film may have reduced mold release properties. Deterioration in film and mold release properties is likely to be observed, for example, in a single-layer release film.For example, a release film used in a sealing stage of a semiconductor device essentially has properties of strength, elongation, and mold release, and the deterioration of these properties is particularly problematic. Furthermore, when an electrically conductive filler is used as a release film material, the formability or productivity of the film compared to a single-layer release film can deteriorate, increasing film forming costs. Additionally, an extruder used to form the film is difficult to clean. To impart electrostatic dissipation properties to a release film, a surfactant could be added to a surface layer, for example. However, surfactants are less effective at imparting electrical conductivity, and tetrafluoroethylene resins have low compatibility with surfactants. Furthermore, when a surface layer contains a surfactant, a release film may exhibit inferior physical properties such as mold release and durability. In this case, surfactant runoff can contaminate the contact surface with the release film. Additionally, a surfactant may not be effective at low humidity levels and may require humidity control to exert electrostatic dissipation properties. The release film of the present invention, as described above, has a layered structure comprising a base layer formed from a polyester resin and a surface layer formed from a tetrafluoroethylene resin, and the tetrafluoroethylene resin forming the surface layer comprises an electrically conductive filler. The release film therefore has electrostatic dissipation properties while maintaining excellent physical properties as a release film. According to one embodiment of the present invention, the electrically conductive filler may comprise carbon black, and the tetrafluoroethylene resin may comprise particles having an average particle size of 1 pm to 15 pm as determined by laser diffraction particle size analysis. When the particles are contained, the electrostatic dissipation property exerted by the carbon black can be enhanced. Consequently, when the particles are contained, a smaller amount of carbon black can be used to impart the desired electrostatic dissipation property to the release film. This also helps prevent the deterioration of physical properties caused by the addition of carbon black to a release film. The particles contained in the surface layer improve the mold release properties of the release film. The particles contained in addition to carbon black improve the dispersibility of carbon black in tetrafluoroethylene resin and can improve the appearance of the release film. In this embodiment, the preferred carbon black comprises Ketjen black. When Ketjen black is present, the particles are particularly likely to exert a dispersibility-enhancing effect. A smaller amount of Ketjen black can impart a different electrostatic dissipation property than carbon blacks. Consequently, Ketjen black can impart a proposed electrostatic dissipation property to a release film while suppressing effects on the physical properties of the release film. In this formulation, the preferred carbon black also includes oven black. When carbon black and oven black are combined, the effect of improving the appearance of a release film is enhanced, in addition to the effect described when carbon black is used alone. More specifically, the film surface becomes a more uniform black. In this form, carbon black may include furnace black. Even when furnace black is present, the particles can improve the dispersibility of a tetrafluoroethylene resin. A smaller mass of carbon black can impart electrostatic dissipation properties compared to furnace black. According to another embodiment of the present invention, the electrically conductive filler may comprise carbon black, and the carbon black may comprise ketjen black and furnace black. In this embodiment, the particles having an average particle size of 1 μm to 15 μm and described in the preceding embodiment are not necessarily contained. A combination of ketjen black and furnace black may improve the dispersibility of the carbon black in a tetrafluoroethylene resin without the particles. According to yet another embodiment of the present invention, the electrically conductive filler may comprise carbon black. In this embodiment, the particles having an average particle size of 1 μm to 15 μm and described in the preceding embodiment are not necessarily included. In this embodiment, the carbon black is preferably Ketjen black. In the release film of the present invention, the surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler may constitute a surface or each surface. The surface layer can be laminated onto one face of the two faces of the base layer (i.e., the surface layer can be laminated directly onto one face of the base layer), or another layer can be interposed between the surface layer and the base layer. (2) Example of the release film configuration of the present invention An example structure of the release film of the present invention is shown in Fig. 1. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y As shown in Fig. 1, a release film 100 of the present invention comprises a base layer 101 and surface layers 102 and 103 laminated on both sides of the base layer. The 101 base layer is made of a polyester resin. The surface layer 102 is formed from a tetrafluoroethylene resin comprising an electrically conductive filler. When used to seal a semiconductor device, the release film 100 is positioned so that the surface layer 102 comes into contact with a sealing resin. The surface layer 102 imparts an electrostatic dissipation property to the release film. The surface layer 103, for example, can be formed from a fluororesin and preferably from a tetrafluoroethylene resin. The fluororesin forming the surface layer 103 may or may not include an electrically conductive filler. When used to seal a semiconductor device, the release film 100 is positioned so that the surface layer 103 comes into contact with a mold. Because the surface layer 103 is formed from a fluororesin, particularly a tetrafluoroethylene resin, the release film 100 can provide excellent mold release properties and prevent mold contamination (particularly contamination by oligomers). As described above, the release film of the present invention may comprise, for example, a base layer formed from a polyester resin, a first surface layer laminated on one side of the base layer and formed from a tetrafluoroethylene resin comprising an electrically conductive filler, and a second surface layer laminated on the other side of the base layer and formed from a fluororesin (preferably a tetrafluoroethylene resin). Another layer can be interposed between the base layer and the first surface layer and / or the second surface layer, but, for example, in order to reduce production costs, the release film of the present invention can have a three-layer structure with respect to the base layer, the first surface layer laminated on the base layer, and the second surface layer laminated on the base layer. (3) Use of the release film of the present invention The release film of the present invention can be used to seal a semiconductor device. In sealing, the release film is positioned so that the surface layer comprising an electrically conductive filler comes into contact with a sealing resin. The release film of the present invention can suppress ESD in sealing and can prevent electrostatic destruction of a semiconductor device. Consequently, the release film of the present invention can eliminate the need for an antistatic device placed around a mold and sealing apparatus and can reduce production costs. The molding technique for sealing a semiconductor device can be appropriately selected by a person skilled in the art. Examples of molding techniques include transfer molding and compression molding, and the release film of the present invention is suitable for use in such molding. The release film of the present invention can be used, for example, in transfer molding or compression molding while being placed between a mold and a resin. In such molding (particularly during a curing stage of a sealing resin), the surface layer comprising an electrically conductive filler is in contact with the resin, and the other surface layer is in contact with the mold. The molding temperature during the molding process where the release film of the present invention is used can be, for example, 100°C to 250°C, and preferably 120°C to 200°C. An exemplary use of the release film of the present invention in transfer molding will be described with reference to Figs. 2. rzbbnn / zznz / E / Y As shown in Fig. 2A, a release film 100 of the present invention is placed between an upper mold 201 and a lower mold 203 with a semiconductor device-loaded substrate 202. The release film 100 is thus positioned so that one surface layer 102 formed from a tetrafluoroethylene resin comprising an electrically conductive filler comes into contact with the resin 204 described below, and the other surface layer 103 comes into contact with the inner face of the upper mold 201 described below. Next, as shown in Fig. 2B, while the release film 100 bonds onto the inner face of the mold 201, the upper mold 201 is brought into contact with the substrate 202 and the lower mold 203. In this state, the surface layer 103 is in contact with the inner face of the upper mold 201. Next, as shown in Fig. 2C, a resin 204 is introduced between the upper mold 201 and the substrate 202, and then the resin 204 is cured. At this stage, the surface layer 102 formed from a tetrafluoroethylene resin comprising an electrically conductive filler is in contact with the resin 204. After curing, as shown in Fig. 2D, the upper mold 201 is removed from the substrate 202. The release film of the present invention has excellent mold release properties, and this allows the cured resin 204 to be released uniformly from the upper mold 201 at the stage of Fig. 2D. If the mold release properties are insufficient, a release film 250 could adhere to a cured resin 204, for example, as shown in Fig. 2E. An exemplary use of the release film of the present invention in compression molding will be described with reference to Figs. 3. As shown in Fig. 3A, a release film 100 of the present invention is placed between a lower mold 301 and an upper mold 303 with a substrate loaded with a semiconductor device 302. The release film 100 is thus positioned so that one surface layer 102 formed of a tetrafluoroethylene resin comprising an electrically conductive filler comes into contact with the resin 304 described below, and the other surface layer 103 comes into contact with the inner face of the lower mold 301 described below. Next, as shown in Fig. 3B, while the release film 100 is bonded to the inner face of the lower mold 301, a resin 304 is placed in a cavity of the lower mold 301. At this stage, the surface layer 102 formed from a tetrafluoroethylene resin comprising an electrically conductive filler rzbbnn / zznz / E / Y is in contact with the resin 304, and the surface layer 103 is in contact with the inner face of the lower mold 301. As shown in Fig. 3C, the upper mold 303 is moved to be brought into contact with the lower mold 301. Then, the resin 304 is cured. After curing, as shown in Fig. 3D, the upper mold 303 is removed from the lower mold 301. The release film of the present invention has excellent mold release properties, and this allows the cured resin 304 to be released uniformly from the lower mold 301 at the stage of Fig. 3D. The release film of the present invention can be used for molding various resins, and can be used, for example, for molding an epoxy resin or a silicone resin. The type of resin to be used to form a molded article can be appropriately selected by a person skilled in the art. The release film of the present invention can be used for molding, for example, two or more times, preferably four or more times, more preferably five or more times, more preferably six or more times, and even more preferably eight or more times. The release film of the present invention can be used for molding, for example, 2 to 20 times, preferably 4 to 15 times, more preferably 5 to 15 times, more preferably 6 to 15 times, or even more preferably 8 to 12 times. Through multiple release operations, the release film of the present invention maintains its performance and is unlikely to break. Consequently, the release film of the present invention can be used in multiple molding processes. This can reduce molding costs. (4) Details of layers forming the release film of the present invention (4-1) Base layer La capa base incluida en la película de liberación de la presente invención se forma de una resina de poliéster. La resina de poliéster puede ser una resina que contiene poliéster como un componenti principal. El poliéster, por ejemplo, puede ser uno de o una mezcla de dos o más de PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene terephthalate), PCT (polycyclohexilene dimethylene terephthalate), PEB (polietileno-poxybenzoato), y polietileno bisfenoxy carboxilato. Preferably, polyester resin is a polyethylene terephthalate resin. Polyethylene terephthalate resin may be a resin that contains polyethylene terephthalate as a principal component. In this description, a major component is the component that constitutes the highest percentage of the components that make up a resin. For example, the major component of a resin that is polyester may mean that the polyester content in the resin is, for example, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more, relative to the mass of the resin, and may mean that the resin is composed of polyester. The major component of a resin that is polyethylene terephthalate means substantially the same. According to a preferred embodiment of the present invention, the base layer included in the release film can be formed from an easily moldable polyethylene terephthalate resin. Easily moldable polyethylene terephthalate resin (also referred to as an easily moldable PET resin) is a term used to describe a PET resin that has greater moldability than a conventional polyethylene terephthalate resin. The base layer formed from the easily moldable polyethylene terephthalate resin particularly contributes to the development of the lead film of the present invention, which has low contamination properties. According to a preferred embodiment of the present invention, the glass transition temperature of the polyester resin forming the base layer can preferably be 60°C to 95°C, and more preferably 65°C to 90°C. For example, easily moldable polyethylene terephthalate resin has a glass transition temperature within the aforementioned range. The resin forming the base layer has a glass transition temperature within this range, and this contributes to the production of the release film of the present invention, which is usable in multiple moldings. Conventional polyethylene terephthalates typically have a glass transition temperature of 100°C or higher. The glass transition temperature of the easily moldable polyethylene terephthalate resin composition is lower than the glass transition temperature of conventional polyethylene terephthalate. The glass transition temperature is determined by differential thermal analysis (DTA). Easily moldable polyethylene terephthalate resin can be a polyethylene terephthalate copolymer resin, for example. The polyethylene terephthalate copolymer can be produced, for example, by reacting terephthalic acid, ethylene glycol, and a copolymer component, or by mixing and melting a polymer such as a copolymer component and polyethylene terephthalate and then carrying out the distribution reaction. The copolymer component can be an acid component or it can be an alcohol component, for example. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y Examples of the acid component include aromatic dibasic acids (such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), aliphatic dicarboxylic acids (such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid), and alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid). Examples of the alcohol component include aliphatic diols (such as butanediol, neopentyl glycol, and hexanediol) and alicyclic diols (such as cyclohexanedimethanol). As a copolymer component, these compounds can be used individually or in combination with other compounds. The acid component specifically can be isophthalic acid and / or sebacic acid. A commercially available product can be used as the base layer, which is made of easily moldable polyethylene terephthalate resin. For example, Teleflex FT, Teleflex FT3, and Teleflex FW2 (each manufactured by Teijin Film Solutions Ltd.) can be used as the base layer. Alternatively, EMBLET CTK-38 (manufactured by Unitika Ltd.) can also be used as the base layer. The base layer formed from the easily moldable polyethylene terephthalate resin can be produced by a method described, for example, in documents JP-A No. Hei-2305827, JP-A No. Hei-3-86729 or JP-A No. Hei-3-110124. According to a preferred embodiment of the present invention, the base layer can be produced by biaxial stretching of an easily moldable polyethylene terephthalate resin having preferably an in-plane orientation coefficient of 0.06 to 0.16, more preferably 0.07 to 0.15, as described in any of the above published documents. The tensile strength of the base layer, as determined at 175°C according to JIS K7127, may preferably be 40 MPa to 200 MPa, more preferably 40 MPa to 120 MPa, even more preferably 40 MPa to 110 MPa, and particularly preferably 45 MPa to 100 MPa. The tensile elongation at base layer break, as determined at 175°C according to JIS K7127, may preferably be 200% to 500%, more preferably 250% to 450%, and even more preferably 300% to 400%. The base layer, which has tensile strength and / or elongation at break within the aforementioned numerical ranges, contributes to the production of the release film of the present invention, which is usable in multiple moldings. Tensile strength and elongation at break within the aforementioned numerical ranges can be achieved, for example, by forming the base layer from an easily moldable polyethylene terephthalate resin. The easily moldable polyethylene terephthalate resin has greater extensibility than a conventional PET resin. rzbbnn / zznz / E / Y The polyester resin of the base layer is a readily moldable polyethylene terephthalate resin, and thus the release film of the present invention has low contamination properties during molding. Furthermore, the release film of the present invention can be used for multiple molding processes. The effects achieved by the release film of the present invention will be described in more detail below. A polyethylene terephthalate (PET) resin contains oligomers produced during its manufacture that have low degrees of polymerization. When a release film comprising a layer formed from such a PET resin is used for molding, the oligomer can migrate to the surface of the release film and contaminate a molded article and / or the mold surface. Contamination can occur even when, for example, a fluorinated resin layer is laminated onto the surface of the PET resin layer. This is believed to be because the oligomer passes through the fluorinated resin layer. Contamination is likely to occur particularly when a single release film is used in a molding process multiple times.This is believed to be due to the application of heat to the polyethylene terephthalate resin during molding, which causes the oligomer to move from the interior of the resin to the surface. The easily moldable polyethylene terephthalate resin also contains oligomers. However, when the release film of the present invention has a configuration in which a base layer formed from an easily moldable polyethylene terephthalate resin and a resin layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler are laminated, not only can an electrostatic dissipation property be imparted to the lead film, but oligomer contamination can also be suppressed or prevented. Moreover, the release film of the present invention maintains the electrostatic dissipation property and low contamination properties through multiple molding operations. A typical release film is replaced with a fresh one after each molding operation. This is because when a release film used in one molding operation is used in another, it is highly likely to tear. Tear of a release film is detrimental to the molding process and can result in an abnormally shaped molded item or adhesion between the mold and the molded item, for example. When the release film of the present invention has a configuration in which a base layer formed from an easily moldable polyethylene terephthalate resin and a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler are laminated, the release film is unlikely to break and maintains its mold release properties, electrostatic dissipation properties, and low contamination properties even when used for multiple moldings. Therefore, the release film according to the present invention can be used for multiple moldings, thus reducing molding costs. The thickness of the base layer, for example, can be 10 µm to 80 µm, preferably 15 µm to 75 µm, and more preferably 20 µm to 70 µm. The thickness contributes to the formation of the release film of the present invention, which is usable in multiple moldings. (4-2) Surface layer formed of tetrafluoroethylene resin comprising an electrically conductive filler (4-2-1) Tetrafluoroethylene resin The release film of the present invention comprises a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler. The tetrafluoroethylene resin preferably does not contain chlorine. The absence of chlorine improves the durability and / or antifouling properties of the layer. The tetrafluoroethylene resin, for example, may be a cured product of a tetrafluoroethylene resin composition containing a tetrafluoroethylene polymer with a reactive functional group and a curing agent. The tetrafluoroethylene polymer containing a reactive functional group within the tetrafluoroethylene resin composition may be a tetrafluoroethylene polymer that is curable by a curing agent. The reactive functional group and the curing agent may be appropriately selected by a person skilled in the art. The reactive functional group, for example, can be a hydroxyl group, a carboxyl group, the group represented by -COOCO-, an amino group, or a silyl group, and is preferably a hydroxyl group. Such a group allows a reaction to yield the cured product and thus proceed satisfactorily. Of these reactive functional groups, a hydroxyl group is particularly suitable for the reaction to give the cured product. In other words, the tetrafluoroethylene polymer containing the preferred reactive functional group can be a tetrafluoroethylene polymer containing a hydroxyl group. The fluorine-containing unit of the tetrafluoroethylene polymer containing the reactive functional group is preferably a fluorine-containing unit based on a perfluoroolefin. The fluorine-containing unit in the perfluoroolefin may preferably be based on one, two, or three selected from tetrafluoroethylene (also referred to as TFE in this description), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ethers) (PAVEs). Preferably, of the perfluoroolefin-based fluorine-containing units, the amount of a TFE-based fluorine-containing unit is the largest. The hydroxyl value of the tetrafluoroethylene polymer containing the reactive functional group (particularly the hydroxyl value of the tetrafluoroethylene polymer containing the hydroxyl group) may preferably be 10 mg KOH / g to 300 mg KOH / g, more preferably 10 mg KOH / g to 200 mg KOH / g, and even more preferably 10 mg KOH / g to 150 mg KOH / g. A tetrafluoroethylene polymer containing the reactive functional group with a hydroxyl value not less than the lower limit of the above numerical range can produce a resin composition with good curing properties. A tetrafluoroethylene polymer containing the reactive functional group with a hydroxyl value not greater than the upper limit of the above numerical range can contribute to the formulation of a resin composition that yields a cured product suitable for multiple molding operations.The hydroxyl value is determined by an rzbbnn / zznz / E / Y method in accordance with JIS K 0070. The acid value of the tetrafluoroethylene polymer containing a reactive functional group (particularly the acid value of the tetrafluoroethylene polymer containing a hydroxy group) may preferably be 0.5 mg KOH / g to 100 mg KOH / g, or more preferably 0.5 mg KOH / g to 50 mg KOH / g. A tetrafluoroethylene polymer containing a reactive functional group with an acid value not less than the lower limit of the aforementioned numerical range may result in a resin composition with good curing properties. A tetrafluoroethylene polymer containing a reactive functional group with an acid value not greater than the upper limit of the aforementioned numerical range may contribute to the formulation of a resin composition that yields a cured product suitable for multiple molding operations. The reactive functional group of the tetrafluoroethylene polymer can be introduced into the tetrafluoroethylene polymer by copolymerizing a monomer with the reactive functional group with a monomer containing fluorine (particularly the perfluoroolefin mentioned above). In other words, the tetrafluoroethylene polymer can contain a polymer unit based on a monomer with the reactive functional group and a polymer unit based on a monomer containing fluorine (particularly the perfluoroolefin mentioned above). When the reactive functional group is a hydroxy group, the monomer bearing the reactive functional group can preferably be a vinyl ether containing a hydroxy group or an allyl ether containing a hydroxy group. Examples of vinyl ethers containing a hydroxy group include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether, and 6-hydroxyhexyl vinyl ether. Examples of allyl ethers containing a hydroxy group include 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Alternatively, the monomer that has the reactive functional group, for example, can be a hydroxyalkyl ester of (meth)acrylic acid, such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.Like the monomer that has the reactive functional group, these compounds can be used individually or in combination with two or more of them. When the reactive functional group is a hydroxy group, the monomer that most preferably has the reactive functional group can be a vinyl ether containing a hydroxy group, and specifically preferably 4-hydroxybutyl vinyl ether and / or 2-hydroxyethyl vinyl ether from the standpoint of the curing properties of the resin composition. When the reactive functional group is a carboxyl group, the monomer that has the reactive functional group can preferably be an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid. When the reactive functional group is an amino group, the monomer that has the reactive functional group, for example, can be an amino vinyl ether or allylamine. When the reactive functional group is a silyl group, the monomer that has the reactive functional group can preferably be a silicone-type vinyl monomer. The fluorine-containing monomer is preferably a perfluoroolefin. Examples of perfluoroolefins include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ethers) (PAVEs). Preferably, the fluorine-containing monomer comprises TFE. Preferably, the tetrafluoroethylene polymer containing a reactive functional group may contain, in addition to the polymer unit based on a monomer containing a reactive functional group and the polymer unit based on a monomer containing fluorine, a polymer unit based on a fluorine-free vinyl monomer. The fluorine-free vinyl monomer, for example, may be a single monomer or a combination of two or more monomers selected from vinyl carboxylates, alkyl vinyl ethers, and non-fluorinated definites. Examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, vinyl benzoate, and vinyl para-butylbenzoate. Examples of alkyl vinyl ethers include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether. Examples of non-fluorinated olefins include ethylene, propylene, n-butene, and isobutene. The tetrafluoroethylene polymer containing a reactive functional group may contain, in addition to the polymer unit based on a monomer containing a reactive functional group and the polymer unit based on a monomer containing fluorine such as a perfluoroolefin, a polymer unit based on a fluoromonomer other than perfluoroolefin, such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinyl ether. The tetrafluoroethylene polymer containing a reactive functional group, for example, can be a copolymer of rzbbnn / zznz / E / Y TFE / non-fluorinated olefin / hydroxybutyl vinyl ether, an rzbbnn / zznz / E / Y copolymer of TFE / vinyl carboxylate / hydroxybutyl vinyl ether or a copolymer of TFE / alkyl vinyl ether / hydroxybutyl vinyl ether. More specifically, the tetrafluoroethylene polymer containing the reactive functional group can be a TFE / isobutylene / hydroxybutyl vinyl ether copolymer, a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer, or a TFE / VdF / hydroxybutyl vinyl ether copolymer. The tetrafluoroethylene polymer containing the particularly reactive functional group can preferably be a TFE / isobutylene / hydroxybutyl vinyl ether copolymer or a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer. As a tetrafluoroethylene polymer containing a reactive functional group, for example, a product can be used in a Zeffle GK series. The curing agent contained in the tetrafluoroethylene resin composition can be appropriately selected by a person skilled in the art depending on the type of reactive functional group contained in the tetrafluoroethylene polymer containing the reactive functional group. When the reactive functional group is a hydroxy group, the preferred curing agent may be a single agent or a combination of two or more agents selected from isocyanate curing agents, melamine resins, silicate compounds, and silane compounds containing an isocyanate group. When the reactive functional group is a carboxyl group, the preferred curing agent may be a single agent or a combination of two or more agents selected from amino curing agents and epoxy curing agents. When the reactive functional group is an amino group, the curing agent can be a single agent or a combination of two or more agents selected from carbonyl-containing curing agents, epoxy curing agents, and acid anhydride curing agents. The curing agent content in the tetrafluoroethylene resin composition, for example, may be 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the curing agent content in a cured product of the tetrafluoroethylene resin composition. The content of the curing agent can be determined by pyrolysis gas chromatography (Py-GC / MS). In one embodiment of the present invention, the reactive functional group contained in the tetrafluoroethylene polymer may be a hydroxy group, and the curing agent may be an isocyanate curing agent. In this embodiment, the isocyanate curing agent is preferably a hexamethylene diisocyanate (HDI) polyisocyanate. The HDI polyisocyanate content in the tetrafluoroethylene resin composition, for example, may be 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the HDI polyisocyanate content in a cured product of the tetrafluoroethylene resin composition. Like HDI polyisocyanate, for example, a single polyisocyanate or a combination of two or more polyisocyanates selected from isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates can be used. In the present invention, the isocyanate curing agent can preferably be an isocyanurate-type polyisocyanate and / or an adduct-type polyisocyanate, and more preferably a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate. When a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate is used as the curing agent, the mass ratio of the two is, for example, 10:6 to 10:10 and preferably 10:7 to 10:9. The total amount of the two, for example, may be 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, and more preferably 25 parts by mass to 35 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. The content ratio of these curing agents can be determined by pyrolysis gas chromatography (Py-GC / MS). (4-2-2) Electrically conductive filler The tetrafluoroethylene resin that forms the surface layer comprises an electrically conductive filler. The electrically conductive filler, for example, may be a single filler or a combination of two or more fillers selected from electrically conductive metal fillers, electrically conductive carbon fillers, electrically conductive metal oxide fillers, and electrically conductive metal plating fillers. Examples of electrically conductive metal fillers include electrically conductive powder fillers such as silver, copper, nickel, tin, and silver-plated copper powders, and electrically conductive fibrous fillers such as copper fibers, stainless steel, aluminum, brass, and iron. Examples of electrically conductive carbon fillers include electrically conductive powder fillers such as carbon black and graphite, and electrically conductive fibrous fillers such as carbon nanotubes (CNTs) and carbon fibers. Examples of electrically conductive metal oxide fillers include electrically conductive powder fillers such as tin oxide, indium oxide, and zinc oxide powders.Examples of electrically conductive metal-plated fillers include electrically conductive powder fillers such as metal-plated glass beads and metal-plated mica powder, and electrically conductive fibrous fillers such as metal-plated glass fibers and metal-plated carbon fibers. The electrically conductive filler of choice is the electrically conductive carbon filler and, for example, it can be the electrically conductive carbonaceous powder filler described above or the electrically conductive carbonaceous fibrous filler. The content of the electrically conductive filler in the tetrafluoroethylene resin composition, for example, may be 1 part by mass to 25 parts by mass, and preferably 1 part by mass to 23 parts by mass, relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the content of the electrically conductive filler in a cured product of the tetrafluoroethylene resin composition. The electrically conductive filler preferably comprises carbon black. The electrically conductive filler may consist solely of carbon black. For example, a single carbon black or a combination of two or more carbon blacks selected from ketjen black, furnace black, acetylene black, channel black, thermal black, and lamp black may be used. The electrically conductive filler preferably comprises one or both of ketjen black and furnace black. Ketjen black and furnace black are particularly suitable for imparting an electrostatic dissipation property to the release film of the present invention. Ketjen black has a small primary particle size and a hollow structure, thus carrying a large amount of charge per unit weight. Consequently, a small amount of Ketjen black imparts an electrostatic dissipation property to a release film. According to a preferred embodiment of the present invention, the carbon black contained in the tetrafluoroethylene resin forming the surface layer comprises rzbbnn / zznz / E / Y ketjen black. The carbon black may consist solely of ketjen black, for example. When the electrically conductive filler comprises Ketjen black, the Ketjen black content in the tetrafluoroethylene resin composition may be, for example, 1 part by mass to 25 parts by mass, preferably 1 part by mass to 10 parts by mass, and more preferably 3 parts by mass to 8 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the Ketjen black content in a cured product of the tetrafluoroethylene resin composition. When the tetrafluoroethylene resin forming the surface layer comprises Ketjen black but does not comprise the particles described below in (4-2-3) Particles, the Ketjen black content is preferably 3 parts by mass or more to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. This can make the release film have a surface resistivity Rs of, for example, 1 x 10⁸ Ω or less, particularly 5 x 10⁷ Ω or less. In this case, the Ketjen black content is, for example, 3 parts by mass to 15 parts by mass and more preferably 5 parts by mass to 10 parts by mass to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y When the tetrafluoroethylene resin forming the surface layer comprises ketjen black and includes particles (particularly silicon dioxide particles) described later in (4-2-3) Particles, the ketjen black content can be 1 part by mass or more relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. When the particles and ketjen black are used in combination, a smaller ketjen black content can result in a release film with a surface resistivity Rs of, for example, 1 x 10⁸ Ω or less, particularly 5 x 10⁷ Ω or less. A combination of the particles and ketjen black can improve the dispersibility of the ketjen black in the tetrafluoroethylene resin composition. This improves the surface appearance of the release film. According to a particularly preferred embodiment of the present invention, the carbon black contained in the tetrafluoroethylene resin forming the surface layer comprises ketjen black and oven black. The carbon black may consist solely of a combination of ketjen black and oven black, for example. When the electrically conductive filler comprises ketjen black and oven black, the content of ketjen black in the tetrafluoroethylene resin composition can preferably be 1 part by mass to 100 parts by mass, more preferably 2 parts by mass to 9 parts by mass, and even more preferably 3 parts by mass to 8 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the content of ketjen black in a cured product of the tetrafluoroethylene resin composition. In this case, the content of oven black in the tetrafluoroethylene resin composition, for example, can be 1 part by mass to 25 parts by mass, preferably 3 parts by mass to 20 parts by mass, and more preferably 5 parts by mass to 18 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group.These numerical ranges also apply to the content of oven black in a cured product of the tetrafluoroethylene resin composition. When the tetrafluoroethylene resin forming the surface layer comprises ketjen black and oven black, but does not comprise particles described below in (4—2— 3) Particles, the ketjen black content may preferably be 1 part by mass to 10 parts by mass, more preferably 2 parts by mass to 9 parts by mass, and even more preferably 3 parts by mass to 8 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the ketjen black content in a cured product of the tetrafluoroethylene resin composition.In this case, the content of furnace black in the tetrafluoroethylene resin composition, for example, can be 1 part by mass to 2 parts by mass, preferably 3 parts by mass to 20 parts by mass, and more preferably 5 parts by mass to 18 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. Adopting contents within these numerical ranges can result in the release film having a surface resistivity Rs of, for example, 1 x 10⁸ Ω or less, particularly 5 x 10⁷ Ω or less. When the tetrafluoroethylene resin forming the surface layer comprises ketjen black and furnace black and includes particles (particularly silicon dioxide particles) described below in (4-2-3) Particles, the ketjen black content in the tetrafluoroethylene resin composition may preferably be 1 part by mass to 8 parts by mass, more preferably 2 parts by mass to 7 parts by mass, and even more preferably 3 parts by mass to 6 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the ketjen black content in a cured product of the tetrafluoroethylene resin composition.In this case, the content of the rzbbnn / zznz / E / Y oven black in the tetrafluoroethylene resin composition, for example, can be 1 part by mass to 25 parts by mass, preferably 3 parts by mass to 20 parts by mass, and more preferably 5 parts by mass to 18 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. Adopting contents within these numerical ranges can give the release film a surface resistivity Rs of, for example, 1 x 10⁸ Ω or less, particularly 5 x 10⁷ Ω or less. The amount of DBP oil absorption of Ketjen Black is preferably 250 ml / 100 g or more, preferably 280 ml / 100 g or more, and preferably 300 ml / 100 g or more. The amount of DBP oil absorption of Ketjen Black, for example, can be 1,000 ml / 100 g or less, particularly 800 ml / 100 g or less, and more specifically 600 ml / 100 g or less. In the present description, a DBP oil absorption quantity is the value determined by a method in accordance with JIS K6217-4. The iodine adsorption number of Ketjen black is preferably 500 mg / g more, more preferably 600 mg / g more, and more preferably 700 mg / g more. The iodine adsorption number of Ketjen black is preferably 1,500 mg / g less, more preferably 1,400 mg / g less, and more preferably 1,200 mg / g less. rzbbnn / zznz / E / Y In the present description, an iodine adsorption number is the value determined by a method in accordance with JIS K6217-1. Ketjen black is preferably in powder form. Powdered Ketjen black improves the appearance of a surface coating. The preferred powdered Ketjen black may have an average particle size of 1 µm to 20 µm, preferably 3 µm to 17 µm, even more preferably 5 µm to 15 µm, and particularly preferably 7 µm to 13 µm, as determined by laser diffraction particle size analysis. The average particle size is a volume-weighted average diameter and is determined according to UIS Z8825. The average particle size can be determined, for example, with a particle size analyzer (SALD-2200, Shimadzu Corporation). It is believed that such fine particles, contained within the aforementioned numerical range, contribute to improved dispersibility and / or enhanced appearance. The porosity of Ketjen Black is preferably 50% by volume or more, more preferably 52% by volume or more, and even more preferably 55% by volume or more. The porosity of Ketjen Black is, for example, 90% by volume or less, particularly 85% by volume or less, and more particularly 80% by volume or less. In the present description, porosity is the ratio of the pore volume to the total volume of carbon and pores and is expressed by the following formula: Porosity (% by volume) = A / (A + B) x 100 (A: pore volume per unit mass (cm³ / g); B: carbon volume per unit mass (cm³ / g)). A is a quantity of gas adsorption (physical adsorption) determined with a pore distribution analyzer. B is the reciprocal of an actual density (g / cm3) and the actual density is determined by a pycnometer method. According to a preferred embodiment, the carbon black contained in the tetrafluoroethylene resin that forms the surface layer comprises oven black in addition to ketjen black. The carbon black may consist solely of ketjen black and oven black, for example. When the carbon black comprises ketjen black and oven black, the release film has a better appearance. More specifically, the surface of the release film becomes more uniformly black. The oil absorption capacity of DBP of furnace black is preferably 200 ml / 100 g less, preferably 150 ml / 100 g less, and preferably 100 ml / 100 g less. For example, the oil absorption capacity of DBP of furnace black can be 40 ml / 100 g more, particularly 50 ml / 100 g more, and more specifically 60 ml / 100 g more. The oil absorption capacity of DBP is a value determined by a method in accordance with JIS K6217-4. rzbbnn / zznz / E / Y The specific nitrogen adsorption surface area of ​​furnace black is preferably 10 m2 / ga 70 m2 / g, more preferably 15 m2 / ga 50 m2 / g, and even more preferably 20 m2 / ga 40 m2 / g determined in accordance with JIS K6217-2. Oven black is preferably in powder form. Powdered oven black improves the appearance of a surface coating. The preferred powdered oven black particle size is 30 nm to 150 nm, preferably 50 nm to 100 nm, even more preferably 60 nm to 90 nm, and particularly preferably 70 nm to 80 nm, as determined by electron microscopy. The average particle size is a volume-weighted average diameter and is determined according to JIS Z8825. The average particle size can be determined, for example, with a particle size analyzer (SALD-2200, Shimadzu Corporation). It is believed that such fine particles, contained within the aforementioned numerical range, contribute to improved dispersibility and / or enhanced appearance. A liquid mixed from furnace black with distilled water can preferably have a pH of 5.5 to 8.5, more preferably 6 to 8, and even more preferably 6.5 to 7.5 as determined with a glass electrode pH meter. (4-2-3) Particles The tetrafluoroethylene resin that forms the rzbbnn / zznz / E / Y surface layer preferably comprises particles with an average particle size of 1 μm to 15 μm, more preferably 1 μm to 12 μm, and even more preferably 2 μm to 10 μm, as determined by laser diffraction particle size analysis. These particles are distinct from the electrically conductive filler and are, for example, different from carbon black particles. The average particle size is a volume-weighted average diameter and is determined according to JIS Z8825. The average particle size can be determined, for example, with a particle size analyzer (SALD-2200, Shimadzu Corporation). When containing these particles, a resin with a smaller amount of carbon black can impart the proposed electrostatic dissipation property to a release film.When the particles are contained, the dispersibility of the electrically conductive filler can be improved in the tetrafluoroethylene resin. Improved dispersibility can enhance the surface appearance of the release film. The particles can also improve the mold release properties of the release film. The particles are preferably inorganic or organic. Examples of inorganic particles include silicon dioxide particles (particularly amorphous silicon dioxide), calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Examples of organic particles include crosslinked polymer particles and calcium oxalate particles. In the present invention, the particles are preferably inorganic, more preferably silicon dioxide particles, and even more preferably amorphous silicon dioxide particles. The amorphous silicon dioxide may be a sol-gel type silica. For example, amorphous silicon dioxide can be used in a Sylysia series. The particle content in the tetrafluoroethylene resin composition, for example, may be 3 parts by mass to 30 parts by mass, preferably 4 parts by mass to 25 parts by mass, and more preferably 5 parts by mass to 20 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the particle content in a cured product of the tetrafluoroethylene resin composition. The particle content can be determined by thermogravimetric analysis (TGA). (4-2-4) Other components The tetrafluoroethylene resin composition may include a solvent. The type of solvent can be appropriately selected by a person skilled in the art. Examples of solvents include butyl acetate, ethyl acetate, and methyl ethyl ketone (also referred to as MEK). For example, a mixture of these three solvents can be used. The tetrafluoroethylene resin composition may include a release accelerator. Examples of release accelerators include an amino-modified methylpolysiloxane, an epoxy-modified methylpolysiloxane, a carboxy-modified methylpolysiloxane, and a carbinol-modified methylpolysiloxane. Preferably, the release accelerator is an amino-modified methylpolysiloxane. The release accelerator content, for example, may be 0.01 part by mass to 3 parts by mass, preferably 0.05 part by mass to 2 parts by mass, and more preferably 0.1 part by mass to 1 part by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group. These numerical ranges also apply to the release accelerator content in a cured product of the tetrafluoroethylene resin composition. (4-2-5) Formation of the surface layer The thickness of the surface layer, for example, can be 1 μm to 10 μm, preferably 2 to 9 μm, and more preferably 3 pm to 8 μιη. The tetrafluoroethylene resin composition can be produced by mixing and stirring the components described above using means known to a person skilled in the art. For mixing and stirring, for example, a mixer such as a high-speed mixer, a homomixer, or a paint stirrer can be used. For mixing and stirring, for example, a dissolver such as a high-speed edge turbine dissolver can be used. A cured product of the tetrafluoroethylene resin composition can be obtained as follows: the tetrafluoroethylene resin composition is applied to a base layer surface and heated, for example, to 100°C to 200°C, preferably 120°C to 180°C, for example, for 10 to 240 seconds, preferably 30 to 120 seconds. The cured product forms the surface layer. The application rate of the tetrafluoroethylene resin composition can be adjusted appropriately by a person skilled in the art, depending on the thickness of the surface layer formed. The surface layer formed from the tetrafluoroethylene resin comprising the electrically conductive filler comes into contact with a molded article during its production. In this description, the surface layer is also referred to as a molded article-side surface layer. The other surface layer (the surface layer that comes into contact with a mold during the production of a molded article) is also referred to as a mold-side surface layer. In a preferred embodiment of the present art, the surface layer on the side of the molded article comprises a cured product of a fluororesin composition containing the tetrafluoroethylene polymer containing a reactive functional group (particularly a tetrafluoroethylene polymer containing a hydroxy group), the curing agent, the particles, the release accelerator, and the electrically conductive filler. More preferably, the surface layer on the side of the molded article comprises a cured product of a tetrafluoroethylene resin composition containing a tetrafluoroethylene polymer containing a hydroxy group, an HDI polyisocyanate, silicon dioxide particles, an amino-modified methylpolysiloxane, and carbon black. The surface layer on the side of the molded article particularly contributes to the elaboration of the release film of the present invention to have excellent electrostatic dissipation property and mold release properties. (4-3) Mold side surface layer rzbbnn / zznz / E / Y (4-3-1) Fluoresin The mold-side surface layer of the release film of the present invention, for example, can be formed from a fluororesin. According to a preferred embodiment of the present invention, the fluororesin is chlorine-free. The absence of chlorine improves the durability and / or antifouling properties of the layer. The fluororesin, for example, can be a cured product of a fluororesin composition containing a fluoropolymer with a reactive functional group and a curing agent. The fluororesin preferably contains a tetrafluoroethylene resin, and more preferably contains a tetrafluoroethylene resin as a major component. In this description, the tetrafluoroethylene resin is a component produced by the curing reaction of the tetrafluoroethylene polymer containing the reactive functional group described below with a curing agent. A tetrafluoroethylene resin as a major component means that the fluororesin is composed of the tetrafluoroethylene resin, or that the tetrafluoroethylene resin content is the highest among the fluororesin components. For example, the tetrafluoroethylene resin content in the fluororesin may be 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, and particularly preferably 85% by mass or more relative to the total mass of the fluororesin.The content, for example, may be 99% by mass or less, particularly 98% by mass or less, and more particularly 97% by mass or less relative to the total mass of fluoresin. When the fluororesin is a tetrafluoroethylene resin, the mold-side surface layer can be the same as the surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler described in (4-2) Surface layer formed from tetrafluoroethylene resin comprising an electrically conductive filler, e.g. The fluoropolymer containing the reactive functional group in the fluororesin composition may be a fluoropolymer that is curable with the curing agent. The reactive functional group and the appropriate curing agent can be selected by a person skilled in the art. The reactive functional group, for example, can be a hydroxyl group, a carboxyl group, the group represented by -COOCO-, an amino group, or a silyl group, and is preferably a hydroxyl group. Such a group allows a reaction to proceed and the cured product to a satisfactory appearance. Of these reactive functional groups, a hydroxyl group is particularly well-suited to the reaction to yield the cured product. In other words, the fluoropolymer containing the reactive functional group is preferably a fluoropolymer containing a hydroxyl group, and more preferably a tetrafluoroethylene polymer containing a hydroxyl group. The fluorine-containing unit of the fluoropolymer containing the reactive functional group is preferably a perfluoroolefin-based fluorine-containing unit. The perfluoroolefin-based fluorine-containing unit may more preferably be based on one, two, or three selected from tetrafluoroethylene (also referred to as TFE in this description), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ethers) (PAVEs). Preferably, of the perfluoroolefin-based fluorine-containing units, the amount of a TFE-based fluorine-containing unit is the largest. The hydroxyl value of the fluoropolymer containing the reactive functional group (particularly the hydroxyl value of the fluoropolymer containing the hydroxyl group) can preferably be 10 mg KOH / g to 300 mg KOH / g, more preferably 10 mg KOH / g to 200 mg KOH / g, and even more preferably 10 mg KOH / g to 150 mg KOH / g. A fluoropolymer containing the reactive functional group that has a hydroxyl value not less than the lower limit of the above numerical range can make the resin composition have good curing properties. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y A fluoropolymer containing a reactive functional group with a hydroxyl value no higher than the upper limit of the numerical range above can contribute to making the resin composition suitable for multiple molding operations. The hydroxyl value is determined by a method in accordance with JIS K 0070. The acid value of the fluoropolymer containing a reactive functional group (particularly the acid value of the fluoropolymer containing a hydroxy group) may preferably be 0.5 mg KOH / g to 100 mg KOH / g, or more preferably 0.5 mg KOH / g to 50 mg KOH / g. A fluoropolymer containing a reactive functional group with an acid value no lower than the lower limit of the aforementioned numerical range may contribute to a resin composition with good curing properties. A fluoropolymer containing a reactive functional group with an acid value no higher than the upper limit of the aforementioned numerical range may contribute to a resin composition that is suitable for multiple molding operations. The reactive functional group of the fluoropolymer can be introduced into the fluoropolymer by copolymerizing a monomer with the reactive functional group with a monomer containing fluorine (particularly the perfluoroolefin mentioned above). In other words, the fluoropolymer containing the reactive functional group can consist of a polymer unit based on a monomer with the reactive functional group and a polymer unit based on a monomer containing fluorine (particularly the perfluoroolefin mentioned above). When the reactive functional group is a hydroxy group, the monomer bearing the reactive functional group can preferably be a vinyl ether containing a hydroxy group or an allylic ether containing a hydroxy group. Examples of vinyl ethers containing a hydroxy group include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether, and 6-hydroxyhexyl vinyl ether. Examples of allylic ethers containing a hydroxy group include 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Alternatively, the monomer that has the reactive functional group, for example, can be a hydroxyalkyl ester of (meth)acrylic acid, such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.Like the monomer that has the reactive functional group, these compounds can be used individually or in combination with two or more of them. When the reactive functional group is a hydroxy group, the monomer that most preferably has the reactive functional group can be a vinyl ether that contains a hydroxy group and specifically preferably 4-hydroxybutyl vinyl ether and / or 2-hydroxyethyl vinyl ether from the point of view of the curing properties of the resin composition. When the reactive functional group is a carboxyl group, the monomer that has the reactive functional group can preferably be an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid. When the reactive functional group is an amino group, the monomer that has the reactive functional group, for example, can be an amino vinyl ether or allylamine. When the reactive functional group is a silyl group, the monomer that has the reactive functional group of preference can be a silicone vinyl monomer. The fluorine-containing monomer is preferably a perfluoroolefin. Examples of perfluoroolefins include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ethers) (PAVEs). Preferably, the fluorine-containing monomer comprises TFE. Preferably, the fluoropolymer containing a reactive functional group may contain, in addition to the polymer unit based on a monomer containing a reactive functional group and the polymer unit based on a monomer containing fluorine, a polymer unit based on a fluorine-free vinyl monomer. The fluorine-free vinyl monomer, for example, may be a single monomer or a combination of two or more monomers selected from vinyl carboxylates, alkyl vinyl ethers, and non-fluorinated definite compounds. Examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, vinyl benzoate, and vinyl para-butylbenzoate. Examples of alkyl vinyl ethers include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether. Examples of non-fluorinated fiber include ethylene, propylene, n-butene, and isobutene. The fluoropolymer containing a reactive functional group may contain, in addition to the polymer unit based on a monomer containing a reactive functional group and the polymer unit based on a monomer containing fluorine such as a perfluoroolefin, a polymer unit based on a fluoromonomer other than a perfluoroolefin, such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinyl ether. The fluoropolymer containing a reactive functional group, for example, can be a copolymer of TFE / non-fluorinated olefin rzbbnn / zznz / E / Y / hydroxybutyl vinyl ether, a copolymer of TFE / vinyl carboxylate / hydroxybutyl vinyl ether, or a copolymer of TFE / alkyl vinyl ether / hydroxybutyl vinyl ether. More specifically, the fluoropolymer containing the reactive functional group may be a TFE / isobutylene / hydroxybutyl vinyl ether copolymer, a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer, or a TFE / VdF / hydroxybutyl vinyl ether copolymer. The fluoropolymer containing the reactive functional group, preferably, may be a TFE / isobutylene / hydroxybutyl vinyl ether copolymer or a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer. As a fluoropolymer containing a reactive functional group, for example, a product in a Zeffle GK series can be used. The curing agent contained in the fluororesin composition can be appropriately selected by a person skilled in the technique depending on the type of reactive functional group contained in the fluoropolymer containing the reactive functional group. When the reactive functional group is a hydroxy group, the preferred curing agent may be a single agent or a combination of two or more agents selected from isocyanate curing agents, melamine resins, silicate compounds, and silane compounds containing an isocyanate group. When the reactive functional group is a carboxyl group, the preferred curing agent may be a single agent or a combination of two or more agents selected from amino curing agents and epoxy curing agents. When the reactive functional group is an amino group, the curing agent can be a single agent or a combination of two or more agents selected from carbonyl-containing curing agents, epoxy curing agents, and acid anhydride curing agents. The curing agent content in the fluororesin composition, for example, may be 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass relative to 100 parts by mass of the fluoropolymer containing the reactive functional group. These numerical ranges also apply to the curing agent content in a cured product of the fluororesin composition. The content of the curing agent can be determined by pyrolysis gas chromatography (Py-GC / MS). In one embodiment of the present invention, the reactive functional group contained in the fluoropolymer containing the reactive functional group can be a hydroxy group, and the curing agent can be an isocyanate curing agent. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y In this modality, the isocyanate curing agent is preferably a hexamethylene diisocyanate (HDI) polyisocyanate. The HDI polyisocyanate content in the fluororesin composition, for example, may be 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass relative to 100 parts by mass of the fluoropolymer containing the reactive functional group. These numerical ranges also apply to the HDI polyisocyanate content in a cured product of the fluorine resin composition. Like HDI polyisocyanate, for example, a single polyisocyanate or a combination of two or more polyisocyanates selected from isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates may be used. In the present invention, the isocyanate curing agent may preferably be an isocyanurate-type polyisocyanate and / or an adduct-type polyisocyanate, and more preferably a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate. When a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate is used as the curing agent, the mass ratio of the two is, for example, 10:6 to 10:10 and preferably 10:7 to 10:9. The total amount of the two, for example, may be rzbbnn / zznz / E / Y parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, and more preferably 25 parts by mass to 35 parts by mass relative to 100 parts by mass of the fluoropolymer containing the reactive functional group. The content ratio of these curing agents can be determined by pyrolysis gas chromatography (Py-GC / MS). (4-3-2) Particles The fluororesin that forms the preferred surface layer comprises particles with an average particle size of 1 μm to 15 μm, more preferably 1 μm to 12 μm, and even more preferably 2 μm to 10 μm, as determined by laser diffraction particle size analysis. The average particle size is a volume-weighted average diameter and is determined according to JIS Z8825. The average particle size can be determined, for example, using a particle size analyzer (SALD-2200, Shimadzu Corporation). These particles can improve the mold release properties of the release film. The particle type is as described in (4-2-3) Particles, and the explanation of it also applies to the particles contained in the mold-side surface layer. Therefore, the explanation of the particles is omitted. rzbbnn / zznz / E / Y The particle content in the fluororesin composition, for example, may be 10 parts by mass to 30 parts by mass, preferably 12 parts by mass to 25 parts by mass, and more preferably 15 parts by mass to 20 parts by mass relative to 100 parts by mass of the fluoropolymer containing the reactive functional group. These numerical ranges also apply to the particle content in a cured product of the fluorine resin composition. The particle content can be determined by thermogravimetric analysis (TGA). (4-3-3) Other components The fluororesin composition may include a solvent. The type of solvent is as described in (4-2-4) Other components, and the explanation of it also applies to the solvent contained in the mold-side surface layer. The fluororesin composition may include a release accelerator. The type of release accelerator is as described in (4-2-4) Other components, and the explanation therein also applies to the release accelerator contained in the mold-side surface layer. The release accelerator content, for example, may be 0.01 part by mass to 3 parts by mass, preferably 0.05 part by mass to 2 parts by mass, and more preferably 0.1 part by mass to 1 part by mass relative to 100 parts by mass of the fluoropolymer containing the reactive functional group. These numerical ranges also apply to the release accelerator content in a cured product of the fluororesin composition. (4-3-4) Formation of the surface layer on the mold side The thickness of the surface layer on the mold side, for example, can be 1 μm to 10 μm, preferably 2 to 9 μm and more preferably 3 μm to 8 μm. The fluororesin composition can be produced by mixing and stirring the components described above using methods known to a person skilled in the art. For mixing and stirring, for example, a mixer such as a high-speed mixer, a homomixer, or a paint stirrer can be used. A dissolver, such as a high-speed edge turbine dissolver, can also be used for mixing and stirring. A cured product of the fluororesin composition can be obtained as follows: the fluororesin composition is applied to a base coat surface and heated, for example, to 100°C to 200°C, preferably 120°C to 180°C, for example, for 10 to 240 seconds, preferably 30 to 120 seconds. The cured product forms the surface layer. The application rate of the fluororesin composition rzbbnn / zznz / E / Y can be adjusted appropriately by a person skilled in the art depending on the thickness of the surface layer formed. In a preferred embodiment of the present art, the mold-side surface layer comprises a cured product of a fluororesin composition containing the reactive functional group-containing fluoropolymer, the curing agent, and the particles. More preferably, the mold-side surface layer comprises a cured product of a fluororesin composition containing a tetrafluoroethylene polymer containing a hydroxy group, an HDI polyisocyanate, and silicon dioxide particles. The surface layer on the mold side particularly contributes to the development of the release film of the present invention to have excellent mold release properties. (5) Physical properties of the release film According to a preferred embodiment of the present invention, the tensile breaking strength of the release film of the present invention can be 40 MPa to 200 MPa, more preferably 40 MPa to 120 MPa, even more preferably 40 MPa to 110 MPa, and particularly preferably 45 MPa to 100 MPa, as determined at 175°C according to JIS K7127, and the tensile elongation at break of the rzbbnn / zznz / E / Y release film can be 200% to 500%, more preferably 250% to 450%, and even more preferably 300% to 400%, as determined at 175°C according to JIS K7127. A tensile breaking strength and tensile breaking elongation each within the above numerical ranges contribute to making it possible to use the release film of the present invention in multi-time molding. The gas permeability (O2) of the release film of the present invention, for example, can be 5,000 to 50,000 cc / m²-24 hr·atm, particularly 5,000 to 30,000 cc / m²-24 hr·atm, and more particularly 5,000 to 20,000 cc / m²-24 hr·atm or less, as determined at 175°C according to JIS K7126-1. The release film of the present invention has such low gas permeability. Consequently, when molding is carried out with the release film of the present invention, contamination of the mold by gas generated from a resin can be suppressed. The thickness of the release film of the present invention, for example, can be 30 µm to 100 µm, preferably 35 µm to 90 µm, and more preferably 40 µm to 80 µm. A thickness within the above numerical range makes the release film easily deformable along the shape of a mold. . Second modality (method for manufacturing the rzbbnn / zznz / E / Y release film) The present invention also provides a method for manufacturing the release film described in 1. First embodiment (release film). The manufacturing method comprises a surface layer forming step for forming, on one of two faces of a base layer formed from a polyester resin, a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, and the manufactured release film has a surface resistivity Rs of 1 x 1011Ω or less. The surface layer forming step, for example, comprises an application step for applying a tetrafluoroethylene resin composition comprising an electrically conductive filler onto one side of the two sides of a base layer formed from a polyester resin and, after the application step, a curing step for curing the tetrafluoroethylene resin composition. The description in 1. First modality (release film) applies to the base layer and the tetrafluoroethylene resin composition used in the application stage, and the explanation of the same is omitted. The application stage can be properly carried out by a person skilled in the technique to achieve a proposed layer thickness. For example, the tetrafluoroethylene resin composition rzbbnn / zznz / E / Y can be applied to both sides of the base coat by etching lamination, reverse lamination, offset etching coating, contact coating, reverse contact coating, wire rod coating, spray coating, or impregnation coating. Appropriate equipment for coating using such a method can be selected by a person skilled in the art. The curing step involves heating the fluororesin composition, for example, to 100°C to 200°C, preferably 120°C to 180°C, for example, for 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds. The heating process cures the fluororesin composition. On the other side of the two surfaces, a tetrafluoroethylene resin composition can be applied and cured, or a fluororesin composition different from the tetrafluoroethylene resin composition can be applied and cured. The description in 1. First mode (release film) applies to both the tetrafluoroethylene resin composition and the fluororesin composition. For the curing stage, the explanation in the curing stage for one side applies. Examples The present invention will be described in more detail below with reference to examples. The examples described below are merely typical examples of the present invention, and the scope of the invention is not intended to be limited to these examples. (Comparative Example 1) As a base layer, a film was prepared made of an easily moldable polyethylene terephthalate resin (Teleflex FT, Teijin Ltd., 50 μm thick, 90°C glass transition temperature). Two fluororesin compositions (hereafter referred to as a resin composition for a mold-side surface layer and a resin composition for a molded-side surface layer) were then prepared for application to the film. The resin composition for a mold-side surface layer is for forming a surface layer that comes into contact with a mold during the sealing stage of a semiconductor device. The resin composition for a molded-side surface layer is for forming a surface layer that comes into contact with a sealing resin (molded article) during the sealing stage. The resin composition for a mold-side surface layer was prepared by mixing and stirring 100 parts by mass of a tetrafluoroethylene polymer solution containing a hydroxy group (Zeffle GK570, Daikin Industries, Ltd., containing 65% by mass of a tetrafluoroethylene polymer rzbbnn / zznz / E / Y containing a hydroxy group), 11.47 parts by mass of amorphous silicon dioxide (Sylysia 380, Fuji Silysia Chemical Ltd.), 10 parts by mass of an isocyanurate-type polyisocyanate (a curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by mass of an adduct-type polyisocyanate (a curing agent, Duranate AE700-100), 6.18 parts by mass of butyl acetate, 44.62 parts by mass of ethyl acetate, and 89.25 parts by mass of MEK. Amorphous silicon dioxide had an average particle size (average diameter in volume as described above) of 9.0 pm as determined by a particle size analyzer (SALD-2200, Shimadzu Corporation) by laser diffraction particle size analysis. The resin composition for a surface layer on the side of the molded article was prepared by mixing and stirring 100 parts by mass of a tetrafluoroethylene polymer solution containing a hydroxy group (Zeffle GK570, Daikin Industries, Ltd., containing 65% by mass of a tetrafluoroethylene polymer containing a hydroxy group), 10 parts by mass of an isocyanurate-type polyisocyanate (a curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by mass of an adduct-type polyisocyanate (a curing agent, Duranate AE700-100), 0.31 parts by mass of an amino-modified methylpolysiloxane (a release accelerator, Shin-Etsu Chemical), 6.18 parts by mass of butyl acetate, 44.62 parts by mass of ethyl acetate, and 89.25 parts by mass of MEK. On one side of the film, the resin composition for a mold-side surface layer was applied, and on the other side, the resin composition for a molded-side surface layer was applied. Application was carried out using a reverse contact coating apparatus. After application, these compositions were cured by heating to 150°C for 60 seconds to produce a release film in which the fluororesin layers were laminated onto the corresponding faces of an easily moldable PET resin film (hereafter referred to as the release film of Comparative Example 1). The release film in Comparative Example 1 had a thickness of 70 ± 5 μm. The base layer in the release film of Comparative Example 1 had a thickness of 50 ± 5 μm. Of the two surface layers of the release film in Comparative Example 1, the mold-side surface layer, as the cured product of the resin composition for a mold-side surface layer, had a thickness of 5.5 ± 0.5 μm. The molded article-side surface layer, as the cured product of the resin composition for a molded article-side surface layer, also had a thickness of 5.5 ± 0.5 μm. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y The cured product of the resin composition for a mold-side surface layer contained 17.65 parts by mass of amorphous silicon dioxide, 15.39 parts by mass of isocyanurate-type polyisocyanate, and 11.98 parts by mass of adduct-type polyisocyanate relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group. The cured product of the resin composition for a surface layer on the molded article side contained 17.65 parts by mass of amorphous silicon dioxide, 15.39 parts by mass of isocyanurate-type polyisocyanate, 11.98 parts by mass of adduct-type polyisocyanate, and 0.48 parts by mass of amino-modified methylpolysiloxane relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group. (Comparative Example 2) The same procedure as in Comparative Example 1 was carried out, except that the amount of tetrafluoroethylene polymer containing the hydroxy group in the resin composition for a surface layer on the molded article side was reduced by 1% by mass, and 1% by mass of Ketjen Black (ECP600JD, Lion Specialty Chemicals, powder) was added to provide a release film (a release film from Comparative Example 2). Ketjen Black had an oil absorption quantity (DBP) of 495 ml / 100 g and an iodine adsorption number of 1,050 mg / g. Ketjen Black had an average particle size of 10 µm, as determined by laser diffraction particle size analysis. In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 99 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black contained in the surface layer of the molded article side of the release film of Comparative Example 2, and the amount of ketjen black was 1 part by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black. The amount of ketjen black was 1.01 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Comparative Example 2. (Example 1) The same procedure as in Comparative Example 1 was carried out except that the amount of tetrafluoroethylene polymer containing hydroxy group in the resin composition for a surface layer on the side of the molded article was reduced by 3% by mass, and 3% by mass of ketjen black (ECP600JP, Lion Specialty Chemicals, powder) was added to give a release film (a release film rzbbnn / zznz / E / Y of Example 1). In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 97 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black contained in the surface layer on the molded article side of the release film of Example 1, and the amount of ketjen black was 3 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black. The amount of ketjen black was 3.09 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 1. (Example 2) The same procedure as in Comparative Example 1 was carried out except that the amount of tetrafluoroethylene polymer containing hydroxy group in the resin composition for a surface layer on the side of the molded article was reduced by 5% by mass, and 5% by mass of ketjen black (ECP600JP, Lion Specialty Chemicals, powder) was added to give a release film (a release film of Example 2). rzbbnn / zznz / E / Y In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 95 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black contained in the surface layer of the molded article side of the release film of Example 2, and the amount of ketjen black was 5 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black. The amount of ketjen black was 5.26 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 2. (Example 3) The same procedure as in Comparative Example 2 was carried out except that 15 parts by mass of amorphous silicon dioxide (Sylysia 380, Fuji Silysia Chemical Ltd.) was further added to a resin composition for a surface layer on the side of the molded article relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group and ketjen black in total, to give a release film (a release film of Example 3). rzbbnn / zznz / E / Y In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 99 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black contained in the surface layer on the molded article side of the release film of Example 3, and the amount of ketjen black was 1 part by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and total ketjen black. The amount of ketjen black was 1.01 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing a hydroxy group contained in the surface layer on the molded side of the release film of Example 3. The amount of amorphous silicon dioxide particles was 15.15 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing a hydroxy group contained in the surface layer on the molded side of the article of Example 3. (Examples 4 and 5) The same procedure as in Example 1 was carried out except that 5 parts by mass or 15 parts by mass of amorphous silicon dioxide (Sylysia 380, Fuji Silysia Chemical Ltd.) was further added to a resin composition for a rzbbnn / zznz / E / Y surface layer on the side of the molded article relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group and ketjen black in total, to give a release film (a release film of Example 4 or a release film of Example 5). In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 97 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black contained in the surface layer on the molded article side of each release film of Examples 4 and 5, and the amount of ketjen black was 3 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black. The amount of Ketjen Black was 3.09 parts by mass relative to 100 parts by mass of the hydroxy-containing tetrafluoroethylene polymer contained in the surface layer on the molded side of each release film of Examples 4 and 5. The amounts of amorphous silicon dioxide particles were 5.15 parts by mass and 15.46 parts by mass relative to 100 parts by mass of the hydroxy-containing tetrafluoroethylene polymer contained in the surface layers on the molded side of the release films of Examples 4 and 5. Examples 4 and 5, respectively. (Examples 6 and 7) The same procedure as in Examples 4 and 5 was carried out, except that ECP Carbon (Lion Specialty Chemicals) was used as the ketjen black instead of ECP600JP to provide a release film (either the release film from Example 6 or the release film from Example 7). The ECP Carbon had a DBP oil adsorption number of 365 ml / 100 g and an iodine adsorption number of 790 mg / g. The ketjen black had an average particle size of 10 pm, as determined by laser diffraction particle size analysis. (Examples 8 and 9) The same procedure as in Example 2 was carried out except that 5 parts by mass or 15 parts by mass of amorphous silicon dioxide (Sylysia 380, Fuji Silysia Chemical Ltd.) was further added to a resin composition for a surface layer on the side of the molded article relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group and ketjen black in total, to give a release film (a release film of Example 8 or a release film of Example 9). In other words, the amount of tetrafluoroethylene polymer containing a hydroxy group was 95 parts by mass relative to 100 parts by mass of rzbbnn / zznz / E / Y tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black contained in the surface layer on the molded article side of each release film of Examples 8 and 9, and the amount of ketjen black was 5 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing a hydroxy group and the total ketjen black. The amount of ketjen black was 5.26 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing a hydroxy group contained in the surface layer on the molded article side of each release film of Examples 8 and 9. The amounts of amorphous silicon dioxide particles were 5.26 parts by mass and 15.79 parts by mass relative to 100 parts by mass of the tetrafluoroethylene polymer containing a hydroxy group contained in the surface layers on the molded article side of the release films of Examples 8 and 9, respectively. (Example 10) As a base layer, a film formed from an easily moldable polyethylene terephthalate resin (Teleflex FT, Teijin Ltd., thickness of 50 μm, glass transition temperature of 90°C) was prepared. Two fluororesin compositions (hereafter referred to as a resin composition for a mold-side surface layer and a resin composition for a molded-article-side surface layer) were then prepared for application to the film. The resin composition for a mold-side surface layer is for forming a surface layer that comes into contact with a mold during the sealing stage of a semiconductor device. The resin composition for a molded-article-side surface layer is for forming a surface layer that comes into contact with a sealing resin (molded article) during the sealing stage. The resin composition for a mold-side surface layer was the same as in Comparative Example 1. The resin composition for a surface layer on the side of the molded article was prepared by mixing and stirring 100 parts by mass of a tetrafluoroethylene polymer solution containing a hydroxy group (Zeffle GK570, Daikin Industries, Ltd., containing 65% by mass of a tetrafluoroethylene polymer containing a hydroxy group), 10 parts by mass of an isocyanurate-type polyisocyanate (a curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.8 parts by mass of an adduct-type polyisocyanate (a curing agent, Duranate AE700-100), 2.78 parts by mass of ketjen black (ECP600JD, Lion Specialty Chemicals), and 11.1 parts by mass of furnace black (Mitsubishi Black #10, rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y Mitsubishi Chemical Corporation, an average particle size of 7.5 nm, a DBP oil absorption amount of 86 ml / 100 g), 13.9 parts by mass of amorphous silicon dioxide (Sylysia 380, Fuji Silysia Chemical Ltd.), 0.6 part by mass of an amino-modified methylpolysiloxane (a release accelerator, Shin-Etsu Chemical), 56.9 parts by mass of ethyl acetate and 113.8 parts by mass of MEK. In a manner similar to that in Comparative Example 1, the resin composition for a mold-side surface layer and the resin composition for a molded article-side surface layer were applied to the film and cured by heating, to give a release film in which the fluororesin layers were laminated onto the corresponding faces of the easily moldable PET resin film (hereafter referred to as a release film of Example 10). The release film of Example 10 had a thickness of 70 ± 5 μm. The base layer on the release film of Example 10 had a thickness of 50 ± 5 μm. Of the two surface layers of the release film of Example 10, the mold-side surface layer, as the cured product of the resin composition for a mold-side surface layer, had a thickness of 5.5 ± 0.5 μm. The molded article-side surface layer, as the cured product of the resin composition for a molded article-side surface layer, had a thickness of 5.5 ± 0.5 μm. The amount of tetrafluoroethylene polymer containing hydroxy group was 70 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black, furnace black and silicon dioxide particles in total contained in the surface layer of the molded article side of the release film of Example 10, and the amounts of ketjen black, furnace black and silicon dioxide particles were 3 parts by mass, 12 parts by mass and 15 parts by mass, respectively, relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black, furnace black and silicon dioxide particles in total. The amounts of ketjen black, furnace black, and silicon dioxide particles were 4.29 parts by mass, 17.14 parts by mass, and 21.43 parts by mass, respectively, relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 10. (Examples 11 and 12) The same procedure as in Example 10 was carried out except that ECP Carbon or ECP200L (Lion Specialty Chemicals) was used as the ketjen black instead of ECP600JD, to give a release film (a release film from Example 11 or a release film from Example 12). (Example 13) The same procedure as in Example 10 was carried out except that the amounts of ketjen black and furnace black were changed to 0 parts by mass and 15 parts by mass, respectively, relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group, ketjen black, furnace black, and silicon dioxide particles in total, to give a release film. The amounts of ketjen black and oven black were 0 parts by mass and 21.43 parts by mass, respectively, relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 13. (Example 14) As a base layer, a film was prepared made of an easily moldable polyethylene terephthalate resin (Teleflex FT, Teijin Ltd., a thickness of 50 pm, a glass transition temperature of 90°C). Two rzbbnn / zznz / E / Y fluororesin compositions (hereafter referred to as a resin composition for a mold-side surface layer and a resin composition for a molded-article-side surface layer) were then prepared for application to the film. The resin composition for a mold-side surface layer is for forming a surface layer that comes into contact with a mold during the sealing stage of a semiconductor device. The resin composition for a molded-article-side surface layer is for forming a surface layer that comes into contact with a sealing resin (molded article) during the sealing stage. The resin composition for a mold-side surface layer was the same as in Comparative Example 1. The resin composition for a surface layer on the side of the molded article was prepared by mixing and stirring 100 parts by mass of a tetrafluoroethylene polymer solution containing a hydroxy group (Zeffle GK570, Daikin Industries, Ltd., containing 65% by mass of a tetrafluoroethylene polymer containing a hydroxy group), 10 parts by mass of an isocyanurate-type polyisocyanate (a curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.8 parts by mass of an adduct-type polyisocyanate (a curing agent, Duranate AE700-100), 2.78 parts by mass of ketjen black (ECP600JD, Lion Specialty Chemicals), 11.1 parts by mass of furnace black (Mitsubishi Black #10, Mitsubishi Chemical Corporation), and 0.6 part by mass of a amino-modified methylpolysiloxane (a release accelerator, Shin-Etsu Chemical), 48.6 parts by mass of ethyl acetate and 97.1 parts by mass of MEK. In a manner similar to that in Comparative Example 1, the resin composition for a mold-side surface layer and the resin composition for a molded article-side surface layer were applied to the film and cured by heating, to give a release film in which the fluororesin layers were laminated onto the corresponding faces of the easily moldable PET resin film (hereafter referred to as a release film of Example 14). The release film of Example 14 had a thickness of 70 ± 5 μm. The base layer on the release film of Example 14 had a thickness of 50 ± 5 μm. Of the two surface layers of the release film of Example 14, the mold-side surface layer, as the cured product of the resin composition for a mold-side surface layer, had a thickness of 5.5 ± 0.5 μm. The molded article-side surface layer, as the cured product of the resin composition for a molded article-side surface layer, had a thickness of rzbbnn / zznz / E / Y 5.5 ± 0.5 min. The amount of tetrafluoroethylene polymer containing hydroxy group was 85 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black, and furnace black in total contained in the surface layer of the molded article side of the release film of Example 14, and the amounts of ketjen black and furnace black were 3 parts by mass and 12 parts by mass, respectively, relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black, and furnace black in total. The amounts of ketjen black and oven black were 3.53 parts by mass and 14.12 parts by mass, respectively, relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 14. (Example 15) The same procedure as in Example 14 was carried out except that the amount of tetrafluoroethylene polymer containing hydroxy group was changed to 92 parts by mass relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black and furnace black in total contained in the rzbbnn / zznz / E / Y layer surface of the molded article side, and the amounts of ketjen black and furnace black were changed to 3 parts by mass and 5 parts by mass, respectively, relative to 100 parts by mass of tetrafluoroethylene polymer containing hydroxy group, ketjen black, and furnace black in total, to give a release film (a release film of Example 15). The amounts of ketjen black and oven black were 3.26 parts by mass and 5.43 parts by mass, respectively, relative to 100 parts by mass of the tetrafluoroethylene polymer containing hydroxy group contained in the surface layer of the molded article side of the release film of Example 15. (Examples 16 and 17) The same procedure as in Example 14 or 15 was carried out except that ECP Carbon was used as the ketjen black instead of ECP600JD, to give a release film (a release film from Example 16 or a release film from Example 17). (Examples 18 and 19) The same procedure as in Example 14 or 15 was carried out except that ECP200L was used as the ketjen black instead of ECP600JD, to give a release film (a release film from Example 18 or a release film from Example 19). The compositions of the molded article in Comparative Examples 1 and 2 and Tables 1 to 3. The surface layers of the release film side of Examples 1 to 19 are shown in rzbbnn / zznz / E / Y [Table 1J rzbbnn / zznz / E / YiAi Example 9 oí un 5.26 15.79 ECP600JD 1.0.E-07 < CÜ CÜ Example 8 oí un 5.26 5.26 ECP600JD 1.4.EI7 < cd CD Example 7 oí £ 3.09 15.46 Carbon ECP 2.6.EI6 < cd CD OE ID 'V ro-i in 3.09 5.15 Carbon ECP o < m CD Example 5 oí £ 6C £ 15.46 ECP600JD 1.0.E-07 < CD CD Example 4 r·^ OO 3.09 5.15 ECP600JD 3.5.E-06 < m CD Example 3 o» Oí un 1.01 15.15 ECP600JD en r en CD CD CD Example 2 oí U1 O 5.26 o ECP600JD 1.0.E+07 o LJ Example 1 oí o 3.09 o ECP600JD 5.8.E-06 < o UJ Comparative Example 2 Oí en en 1.01 O ECP600JD cq oo LJ Comparative Example 1 COI o OO o 1.8.EΊ5 O Amount of fluorine resin in relation to 100 parts by mass of fluorine queen and total ketjen black (parts by mass) Amount of ketjen black in relation to 100 parts by mass of fluorine queen and total ketjen black (parts by mass) Amount of silicon dioxide particles in relation to 100 parts by mass of fluorine queen and total ketjen black (parts by mass) Amount of ketjen black in relation to 100 parts by mass of fluorine queen (parts by mass) Amount of silicon dioxide particles in relation to 100 parts by mass of fluorine queen (parts by mass) Type of ketjen black Surface resistivity [Ω] Surface resistivity evaluation result Dispersibility evaluation result Appearance evaluation result. rzbbnn / zznz / E / Y [Table 2] Example 10 Example 11 Example 12 Example 13 Amount of fluorine resin in relation to 100 parts by mass of fluorine resin, ketjen black, furnace black and total silicon dioxide particles (parts by mass) 70 70 70 70 Amount of ketjen black in relation to 100 parts by mass of fluorine resin, ketjen black, furnace black and total silicon dioxide particles (parts by mass) 3 3 3 0 Amount of furnace black in relation to 100 parts by mass of fluorine resin, ketjen black, furnace black and total silicon dioxide particles (parts by mass) 12 12 12 15 Amount of silicon dioxide particles in relation to 100 parts by mass of fluorine resin, ketjen black, furnace black and total silicon dioxide particles (parts by mass) 15 15 15 15 Amount of ketjen black in relation to 100 parts by mass of fluorine queen (parts by mass) 4.29 4.29 4.29 0.00 Amount of furnace black in relation to 100 parts by mass of fluorine queen (parts by mass) 17.14 17.14 17.14 21.43 Amount of silicon dioxide particle black in relation to 100 parts by mass of fluorine queen (parts by mass) 21.43 21.43 21.43 21.43 Type of ketjen black ECP600JD Carbon ECP ECP200L - Surface resistivity [Ω] 1.2.E+05 8.2.E+05 5.4.E+05 2.0.E+07 Surface resistivity evaluation result AAAA Dispersiveness evaluation result AAAA Evaluation result AAA A. [Table 3] rzbbnn / zznz / E / YiAi Example 19 sm un 3.26 5.43 ECP200L 3.1.E+06 < < ce Example 18 sm rs 3.53 14.12 ECP200L 1.0.E+06 < < ce Example 17 sm un 3.26 5.43 ECP Coal 9.7.E+05 < < ce Example 16 85 í¡ 3.53 14.12 ECP Coal 3.6.E+05 < < ce Example 15 m un 3.26 5.43 ECP600JD 3.4.E+05 < < ce Example 14 m CS 3.53 14.12 ECP600JD 1.7.E+05 < < ce Amount of fluorine resin in relation to 100 parts by mass of fluorine resin, ketjen black and furnace black in total (parts by mass) Amount of ketjen black in relation to 100 parts by mass of fluorine resin, ketjen black and furnace black in total (parts by mass) Amount of furnace black in relation to 100 parts by mass of fluorine resin, ketjen black and furnace black in total (parts by mass) Amount of ketjen black in relation to 100 parts by mass of fluorine resin (parts by mass) Amount of acetylene black in relation to 100 parts by mass of fluorine resin (parts by mass) Type of ketjen black Surface resistivity [Ω] Result of surface resistivity evaluation Result of dispersibility evaluation Result of appearance evaluation. rzbbnn / zznz / E / Y The surface resistivity Rs of the surface layer on the molded article side of each release film in Comparative Examples 1 and 2 and Examples 1 to 19 was determined and evaluated according to the following criteria. In the tables, E+ in the surface resistivity Rs means exponent of 10, and for example, 4.9E+09 in Example 3 means 4.9 x 109. The same applies to the surface resistivities Rs in other examples. The results of the evaluation are shown in Tables 1 to 3. A: Rs is no more than 1 x 109 Ω. B: Rs is more than 1 x 109Ω and not more than 1 x 1011Ω. C: Rs is more than 1 x 1011Ω. In the preparation of resin compositions for a surface coating on the molded article side in the manufacture of the release films for Comparative Examples 1 and 2 and Examples 1 through 19, the dispersibility of carbon black in each composition was evaluated. Dispersibility was assessed using a grinding gauge (Erichsen Model 232 Grindometer) in accordance with JIS K5600-2-5. The evaluation results are shown in Tables 1 through 3. A: No lines observed. B: Lines are observed that have a groove depth of 35 μm or less. rzbbnn / zznz / E / Y C: Lines are observed that have a groove depth of 40 μm or less. The surface appearance of the molded article side of each release film in Comparative Examples 1 and 2 and Examples 1 to 19 was visually evaluated. The evaluation criteria are shown below. The evaluation results are shown in Tables 1 to 3. A: A surface is uniformly black. B: A surface is slightly, but not uniformly, black. C: A surface is not uniformly black. The evaluation results shown in Tables 1 to 3 reveal the following. It is revealed that each film release of the Examples 1 to 19 have a surface resistivity Rs of 1 x 1011Ω or less and have an electrostatic dissipation property. The surface layer on the molded article side of the release film in Comparative Example 1 did not contain carbon black and had a surface resistivity Rs greater than 1 x 10¹¹ Ω. The surface layer on the molded article side of the release film in Comparative Example 2 contained ketjen black but had a surface resistivity Rs greater than 1 x 10¹¹ Ω. In contrast, in Examples 1 and 2, where the ketjen black content was higher than in Comparative Example 2, the surface resistivity Rs was 1 x 10¹¹ Ω or less. These results reveal that when the electrically conductive filler is ketjen black, and the ketjen black content is, for example, 3 parts by mass or more relative to 100 parts by mass of the tetrafluoroethylene polymer containing the reactive functional group, the electrostatic dissipation property can be imparted to a release film. The surface layer on the molded article side of the release film in Comparative Example 2 contained ketjen black but had a surface resistivity Rs greater than 1 x 10¹¹ Ω. In contrast, the release film in Example 3, which contained the same amount of ketjen black but also silicon dioxide particles, had a surface resistivity Rs of 1 x 10¹¹ Ω or less. These results reveal that a combination of ketjen black and silicon dioxide particles can impart an electrostatic dissipation property to a release film. These results also reveal that when silicon dioxide particles are present, a smaller amount of ketjen black can impart an electrostatic dissipation property to a release film.For example, when silicon dioxide particles are contained, the amount of ketjen black may be 1 part by mass or more relative to 100 parts by mass of a tetrafluoroethylene polymer containing a reactive functional group. A comparison of the release films of Examples 3 and 5 reveals that when silicon dioxide particles are contained, and ketjen black is contained in an amount of 3 parts by mass or more relative to 100 parts by mass of a tetrafluoroethylene polymer containing a reactive functional group, the electrostatic dissipation property of a release film can be improved. A comparison between the release films of Examples 4 and 5 and the release films of Examples 6 and 7 reveals that even when the type of ketjen black is changed, a good electrostatic dissipation property is achieved. A comparison between the release films of Examples 4 and 5 and the release films of Examples 8 and 9 reveals that even when contained in a larger amount of ketjen black, a good electrostatic dissipation property is achieved. A comparison of the release films of Examples 1 and 5 reveals that when silicon dioxide particles are contained in addition to ketjen black, the dispersibility of a composition to prepare a surface layer on the side of the molded article can be improved, and the appearance of a surface layer on the side of the molded article produced can be improved. rzbbnn / zznz / E / Y rzbbnn / zznz / E / Y In Examples 3 to 9, the electrostatic dissipation property was rated A, while dispersibility and appearance were rated B. In contrast, in Examples 10 to 12, the electrostatic dissipation property was rated A, and dispersibility and appearance were also rated A. These results reveal that when furnace black is included in addition to ketjen black and silicon dioxide particles, good electrostatic dissipation is achieved, the dispersibility of a composition for preparing a surface layer on the side of the molded article is improved, and the appearance of a surface layer on the side of the molded article can be improved. A comparison between Examples 10 to 12 and Example 13 reveals that a combination of furnace black and silicon dioxide particles can also achieve good electrostatic dissipation properties, improve the dispersibility of a composition to prepare a surface layer on the side of the molded article, and improve the appearance of a produced surface layer on the side of the molded article. The results from Examples 14 to 18 reveal that a combination of ketjen black and furnace black can also achieve good electrostatic dissipation properties. The results also show that this combination can improve the dispersibility of a composition used to prepare a surface layer on the side of the molded article. Although the degree of improvement is less than in Examples 10 to 12, which contain silicon dioxide particles, the results from Examples 14 to 18 show that the combination can improve the appearance of a surface layer on the side of the molded article. The release films of Comparative Examples 1 and 2 and Examples 1 through 19 were used to carry out the molding of an epoxy resin by transfer molding. The molding was carried out as shown in Fig. 2. As a result, the molded article of an epoxy resin was uniformly released from each release film. The result reveals that the surface layer on the side of the molded article of the release film of the present invention, comprising an electrically conductive filler, has substantially the same mold release properties as those of a film that does not comprise an electrically conductive filler. The mold release properties of each release film of Comparative Examples 1 and 2 and Examples 1 through 19 were maintained through multiple molding operations. List of Reference Signs 100 release film 101 base layer rzbbnn / zznz / E / Y

Claims

1. A release film, characterized in that it comprises: a base layer formed of a polyester resin; and a surface layer formed of a tetrafluoroethylene resin comprising an electrically conductive filler, wherein the release film has a surface resistivity Rs of 1 x 1011 Ω or less.

2. The release film according to claim 1, characterized in that the electrically conductive filler comprises carbon black and the tetrafluoroethylene resin comprises particles having an average particle size of 1 pm to 15 pm as determined by laser diffraction particle size analysis.

3. The release film according to claim 2, characterized in that the carbon black comprises ketjen black.

4. The release film according to claim 3, characterized in that the ketjen black has a DBP oil absorption quantity of 250 ml / 100 go more.

5. The release film according to claim 3 or 4, characterized in that the carbon black rzbbnn / zznz / E / Y 101 further comprises oven black.

6. The release film according to claim 2, characterized in that the carbon black comprises oven black.

7. The release film according to any of claims 2 to 6, characterized in that the particles are inorganic particles.

8. The release film according to claim 7, characterized in that the inorganic particles are silicon dioxide particles.

9. The release film according to claim 1, characterized in that the electrically conductive filler comprises carbon black and the carbon black comprises ketjen black and furnace black.

10. The release film according to any of claims 1 to 9, characterized in that the polyester resin is polyethylene terephthalate resin.

11. The release film according to any of claims 1 to 10, characterized in that the polyester resin has a glass transition temperature of 60°C to 95°C.

12. The release film according to any of claims 1 to 11, characterized in that the surface layer is laminated onto one face of the two faces of the base layer.

13. The release film according to claim 12, characterized in that on another face of the two faces of the base layer, a surface layer formed of a fluororesin is laminated.

14. The release film according to any of claims 1 to 13, characterized in that the release film is to be used to seal a semiconductor device.

15. The release film according to claim 14, characterized in that, in sealing, the release film is positioned so that the surface layer formed from the tetrafluoroethylene resin comprising the electrically conductive filler comes into contact with a sealing resin.

16. The release film according to any of claims 1 to 15, characterized in that it is used for transfer molding or compression molding.

17. The release film according to any of claims 1 to 16, characterized in that it is used for molding two or more times.

18. A method for manufacturing a release film, the method characterized in that it comprises: 103 a surface layer forming step for forming, on one face of the two faces of a base layer formed from a polyester resin, a surface layer formed from a tetrafluoroethylene resin comprising an electrically conductive filler, wherein the manufactured release film has a surface resistivity Rs of 1 x 1011 Ω or less.