Release film and method for manufacturing the release film

Abstract

The present invention relates to providing a release film having static electricity diffusibility. The present invention provides a release film having: a base material layer formed of a polyester resin; and a surface layer formed of a tetrafluoroethylene resin containing a conductive filler; and the surface resistivity Rs is 1×10<supgt;11< / supgt; Ω or less. Preferably, the conductive filler contains carbon black, and the tetrafluoroethylene resin further contains particles having an average particle diameter of 1 μm to 15 μm as measured by a laser diffraction particle size analysis method.

Description

Technical Field

[0001] The present invention relates to a release film and a method for manufacturing the same. More specifically, the present invention relates to a release film for sealing a semiconductor device and a method for manufacturing the same. Further, in particular, the present invention relates to a release film for transfer molding or compression molding and a method for manufacturing the same. Background Art

[0002] In order to seal a semiconductor device with a resin, for example, a molding method such as a transfer molding method and a compression molding method can be used. In the molding method, after the resin hardens in the mold, a release film is often used to easily peel the molded body from the mold. To date, various proposals for release films have been made.

[0003] For example, Patent Document 1 below discloses a release film characterized by including: a coating film formed from a composition containing a fluororesin (A) having a functional group X and a release component (B); and a layer formed from a non-fluorinated polymer.

[0004] In addition, Patent Document 2 below discloses a gas barrier release film for a semiconductor resin mold, which has at least a release layer (I) with excellent releasability and a plastic support layer (II) supporting the release layer (I). The plastic support layer (II) has a strength of 1 MPa to 50 MPa at 200% elongation at 170°C, and the release film has a xylene gas permeability of 5×10 -15 (kmol·m / (s·m 2 ·kPa)) or less at 170°C.

[0005] (Prior Art Documents)

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-74201.

[0007] Patent Document 2: International Publication No. 2008 / 020543. Summary of the Invention

[0008] (Problems to be Solved by the Invention)

[0009] As described above, a release film is used to easily peel a molded body from a mold. Regarding the release film, it is required to easily peel from the molded body after the resin hardens.

[0010] In addition, in the manufacture of semiconductor devices, it is necessary to prevent electrostatic damage to the semiconductor devices. Electrostatic damage is caused by ESD (Electrostatic Discharge). The damage to the semiconductor device caused by ESD can be caused by the instantaneous discharge of a charged conductor (or semiconductor device). ESD causes a discharge current to flow through the semiconductor device, and the semiconductor device is damaged due to local heating and / or electric field concentration. In recent years, with the rapid progress of miniaturization of semiconductor devices, the tolerance of semiconductor devices to ESD has gradually decreased.

[0011] In order to prevent the generation of ESD, in the production line of semiconductor devices, for example, an anti-static damage mechanism such as an anti-static device is provided. However, the setting of an anti-static damage mechanism in the production line of semiconductor devices will increase the manufacturing cost. It is generally considered that in the manufacturing process of semiconductor devices, if, for example, an electrostatic diffusion property can be imparted to the release film used in the sealing process of semiconductor devices, the ESD countermeasure in the sealing process can be carried out at a lower cost.

[0012] Based on the above situation, the main object of the present invention is to provide a release film having an electrostatic diffusion property.

[0013] (Technical means for solving the problem)

[0014] The inventors of the present invention found that: a release film having a specific structure has excellent releasability and an electrostatic diffusion property, and is therefore suitable.

[0015] That is, the present invention provides a release film having: a base material layer formed of a polyester resin; and a surface layer formed of a tetrafluoroethylene resin containing a conductive filler; and the surface resistivity Rs is 1×10 11 Ω or less.

[0016] According to an embodiment of the present invention, the conductive filler may include carbon black, and the tetrafluoroethylene resin may further contain particles having an average particle diameter of 1 μm to 15 μm when measured by a laser diffraction particle size analysis method.

[0017] In this embodiment, the carbon black may include Ketjenblack.

[0018] The DBP (Di-n-Butyl Phthalate) oil absorption amount of the Ketjenblack may be 250 ml / 100 g or more.

[0019] The carbon black may further include furnace black.

[0020] In this embodiment, the carbon black may include furnace black.

[0021] The particle may be an inorganic particle.

[0022] The inorganic particle may be a silica particle.

[0023] According to other embodiments of the present invention, the conductive filler may include carbon black, and the carbon black may include Ketjen black and furnace black.

[0024] The polyester resin may be a polyethylene terephthalate resin.

[0025] The glass transition temperature of the polyester resin may be from 60°C to 95°C.

[0026] The surface layer may be laminated on one of the two surfaces of the base material layer.

[0027] On the other surface of the two surfaces of the base material layer, a surface layer formed of a fluororesin may be laminated.

[0028] The release film of the present invention can be used for sealing semiconductor devices.

[0029] In the sealing, the surface layer formed of the tetrafluoroethylene resin containing the conductive filler can be arranged in a manner of contacting the sealing resin.

[0030] The release film of the present invention can be used for transfer molding or compression molding.

[0031] The release film of the present invention can be used for molding two or more times.

[0032] In addition, the present invention also provides a method for manufacturing a release film, including: a surface layer forming step of forming a surface layer formed of a tetrafluoroethylene resin containing a conductive filler on one of the two surfaces of a base material layer formed of a polyester resin; and the surface resistivity Rs of the manufactured release film is 1×10 11 Ω or less.

[0033] (Effects of the Invention)

[0034] Through the present invention, a release film with excellent release properties and electrostatic diffusivity is provided. Furthermore, the effects of the present invention are not necessarily limited to the effects described herein, and may also be any of the effects described in this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a diagram showing an example of the structure of the release film of the present invention.

[0036] Figure 2 It is a diagram showing an example of the usage method of the release film of the present invention in transfer molding.

[0037] Figure 3This is a diagram showing an example of the method of using the release film of the present invention in compression molding. Detailed Embodiments

[0038] Hereinafter, the embodiments for carrying out the present invention will be described in detail. Furthermore, the embodiments described below represent an example of the representative embodiments of the present invention, and the present invention is not limited only to these embodiments.

[0039] 1. First Embodiment (Release Film)

[0040] (1) Description of the First Embodiment

[0041] The release film of the present invention has: a base material layer formed of a polyester resin; and a surface layer formed of a tetrafluoroethylene resin containing a conductive filler; and the surface resistivity Rs is 1×10 11 Ω or less. By using the surface layer formed of a tetrafluoroethylene resin containing a conductive filler, the surface resistivity Rs below the aforementioned upper limit value can be achieved, that is, the release film can be given electrostatic diffusibility. In addition, the release film of the present invention can exhibit excellent releasability and has electrostatic diffusibility through the combination of this surface layer and this base material layer.

[0042] As described above, the surface resistivity Rs of the release film of the present invention is 1×10 11 Ω or less, preferably less than 1×10 11 Ω, more preferably 1×10 10 Ω or less, still more preferably 1×10 9 Ω or less, particularly preferably 1×10 8 Ω or less, 5×10 7 Ω or less, 3×10 7 Ω or less, or 1×10 7 Ω or less. The surface resistivity Rs of the release film of the present invention is, for example, 1×10 3 Ω or more, particularly 5×10 3 Ω or more, even more particularly 1×10 4Ω or more. By having a surface resistivity Rs within the aforementioned numerical range, the release film of the present invention can prevent the generation of ESD during the sealing process of semiconductor devices. The surface resistivity Rs is measured in accordance with the International Electrotechnical Commission (IEC) standard 61340-5-1. Specifically, this measurement is carried out as follows. That is, first, a release film sample with a size of 10 cm × 10 cm is obtained. For example, the measurement main electrode (electrode size φ50 mm) and the protection electrode (outer diameter φ80 mm, inner diameter φ70 mm) of a digital ultra-high resistance / micro-current meter (ADCMT5451, ADC Co., Ltd.) are brought into contact with the formed body side surface layer of this sample. While maintaining the state where these electrodes are in contact, a voltage of 10 V is applied, and then the surface resistivity Rs is measured.

[0043] For example, in order to impart electrostatic diffusibility to a single-layer release film, it can be considered to add a conductive filler to the resin forming the single-layer release film. However, when a single-layer release film contains a conductive filler, for example, film physical properties such as film strength (especially strength and elongation) are likely to decrease. In addition, in this case, the release property may sometimes decrease. The decrease in the film physical properties and release property is, for example, likely to occur in the case of a single-layer release film. For example, in the case of a release film used in the semiconductor device sealing process, strength, elongation, and release property are important factors, and the decrease in these is particularly problematic. Furthermore, the inclusion of a conductive filler in the release film raw material may also lead to a decrease in film-forming property or productivity and an increase in cost during the film formation of the single-layer release film. Moreover, it is difficult to clean the extruder used for the film formation.

[0044] In addition, in order to impart electrostatic diffusibility to the release film, for example, it is conceivable to add a surfactant to the surface layer or the like. However, the effect of imparting conductivity by the surfactant is low, and furthermore, the compatibility between the tetrafluoroethylene resin and the surfactant is poor. Moreover, when the surface layer contains a surfactant, for example, physical properties of the release film such as release property and durability may decrease. Furthermore, in this case, contamination may occur on the contact surface between the surface layer and the release film due to the exudation of the surfactant. Moreover, the electrostatic diffusibility of the surfactant sometimes does not appear at low humidity, and sometimes it is necessary to adjust the humidity conditions in order to exhibit the electrostatic diffusibility obtained by the surfactant.

[0045] As described above, the release film of the present invention has a layer structure including a base material layer formed of a polyester resin and a surface layer formed of a tetrafluoroethylene resin, and has a configuration in which the tetrafluoroethylene resin forming this surface layer contains a conductive filler, whereby excellent physical properties of the release film can be maintained and electrostatic diffusibility can be achieved.

[0046] According to an embodiment of the present invention, the conductive filler may include carbon black, and the tetrafluoroethylene resin may contain particles having an average particle diameter of 1 μm to 15 μm as measured by laser diffraction particle size analysis.

[0047] By containing the particles, the electrostatic diffusivity obtained from the carbon black can be improved. Therefore, when the particles are contained, the desired electrostatic diffusivity can be imparted to the release film with a smaller amount of carbon black. This also contributes to preventing the deterioration of physical properties caused by adding carbon black to the release film.

[0048] In addition, by containing the particles in the surface layer, the releasability of the release film is improved.

[0049] In addition, by further containing the particles in addition to carbon black, the dispersibility of carbon black in the tetrafluoroethylene resin can be improved, and furthermore, the appearance of the release film can be improved.

[0050] In the embodiment, the carbon black preferably includes Ketjen black. When Ketjen black is included, the effect of improving the dispersibility obtained from the particles is particularly likely to be exerted. In addition, compared with other carbon blacks, Ketjen black can impart electrostatic diffusivity in a smaller amount. Therefore, the influence on the physical properties of the release film can be suppressed, and the desired electrostatic diffusivity can be imparted to the release film.

[0051] In the embodiment, the carbon black more preferably further includes furnace black. By including a combination of Ketjen black and furnace black, in addition to the effects in the case of including Ketjen black described above, the effect of improving the appearance of the release film is also exerted. More specifically, the black color on the film surface becomes more uniform.

[0052] In the embodiment, the carbon black may also include furnace black. When furnace black is included, the effect of improving the dispersibility in the tetrafluoroethylene resin obtained from the particles can also be exerted. Furthermore, compared with furnace black, Ketjen black can impart electrostatic diffusivity with less mass.

[0053] According to another embodiment of the present invention, the conductive filler may include carbon black, and this carbon black may include Ketjen black and furnace black. In this embodiment, the particles having an average particle diameter of 1 μm to 15 μm according to the above-described embodiment may not be included. By the combination of Ketjen black and furnace black, even without the particles, the dispersibility of carbon black in the tetrafluoroethylene resin can be improved.

[0054] According to still another embodiment of the present invention, the conductive filler may include carbon black. In this embodiment, the particles having an average particle diameter of 1 μm to 15 μm according to the above-described embodiment may not be included. In this embodiment, the carbon black is preferably Ketjen black.

[0055] Regarding the release film of the present invention, the surface layer formed of a tetrafluoroethylene resin containing a conductive filler may constitute one surface, or may also constitute two surfaces.

[0056] In addition, the surface layer may be laminated on one of the two sides of the base material layer (that is, the surface layer may be directly laminated on the one side of the base material layer), or there may be other layers between the surface layer and the base material layer.

[0057] (2) Example of the structure of the release film of the present invention

[0058] An example of the structure of the release film of the present invention is shown in Figure 1 . As Figure 1 shown, the release film 100 of the present invention is composed of a base material layer 101, and surface layers 102 and 103 laminated on both sides of the base material layer 101.

[0059] The base material layer 101 is formed of a polyester resin.

[0060] The surface layer 102 is formed of a tetrafluoroethylene resin containing a conductive filler. When the release film 100 is used for sealing a semiconductor device, it is arranged such that the surface layer 102 contacts the sealing resin. Electrostatic diffusibility is imparted to the release film through the surface layer 102.

[0061] The surface layer 103 may be formed of a fluororesin, preferably a tetrafluoroethylene resin. The fluororesin forming the surface layer 103 may not contain a conductive filler, or may also contain a conductive filler. When the release film 100 is used for sealing a semiconductor device, it is arranged such that the surface layer 103 contacts the mold. Since the surface layer 103 is formed of a fluororesin, especially a tetrafluoroethylene resin, the release film 100 can exhibit excellent release properties and prevent mold contamination (especially mold contamination caused by oligomers).

[0062] As described above, the release film of the present invention may have, for example: a base material layer formed of a polyester resin; a first surface layer laminated on one side of the base material layer and formed of a tetrafluoroethylene resin containing a conductive filler; and a second surface layer laminated on the other side of the base material layer and formed of a fluororesin (preferably a tetrafluoroethylene resin).

[0063] Furthermore, there may be other layers between the base material layer and the first surface layer and / or the second surface layer. However, for example, in order to reduce the manufacturing cost, the release film of the present invention may have a three-layer structure composed of the base material layer and the first surface layer and the second surface layer laminated on the base material layer.

[0064] (3) Method of using the release film of the present invention

[0065] The release film of the present invention can be used for sealing semiconductor devices. In the sealing, it is arranged such that the surface layer containing the conductive filler contacts the sealing resin. The release film of the present invention can suppress the occurrence of ESD in this sealing and can prevent electrostatic damage to semiconductor devices. Therefore, the release film of the present invention can contribute to reducing the manufacturing cost without the need for a mold for the sealing and an anti-static device provided around the device.

[0066] The molding method for sealing semiconductor devices can be appropriately selected by those skilled in the art. As such a molding method, for example, transfer molding and compression molding can be cited, and the release film of the present invention is suitable for use in these moldings. The release film of the present invention can be used, for example, between a mold and a resin in transfer molding or compression molding. In these moldings (especially in the process of hardening the sealing resin), the surface layer containing the conductive filler contacts this resin, and the other surface layer contacts this mold. The molding temperature in the molding using the release film of the present invention is, for example, 100°C to 250°C, preferably 120°C to 200°C.

[0067] Refer to Figure 2 An example of the usage method of the release film of the present invention in transfer molding will be described.

[0068] As Figure 2 (A) shows, the release film 100 of the present invention is arranged between the upper mold 201 and the lower mold 203 on which the semiconductor component mounting substrate 202 is placed. Here, the release film 100 is arranged such that the surface layer 102 formed of a tetrafluoroethylene resin containing a conductive filler contacts the resin 204 described later, and the other surface layer 103 contacts the inner surface of the upper mold 201 described later.

[0069] Subsequently, as Figure 2 (B) shows, with the release film 100 attached to the inner surface 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 contacts the inner surface of the upper mold 201.

[0070] Subsequently, as Figure 2 (C) shows, the resin 204 is introduced between the upper mold 201 and the substrate 202, and then the resin 204 is hardened. At this stage, the surface layer 102 formed of a tetrafluoroethylene resin containing a conductive filler contacts the resin 204.

[0071] After hardening, as Figure 2 (D) shows, the upper mold 201 is separated from the substrate 202. Since the release film of the present invention has excellent release properties, Figure 2In the process of (D), the cured resin 204 can be smoothly demolded from the upper mold 201.

[0072] In the case of poor mold release property of the mold release film, for example Figure 2 as shown in (E), the mold release film 250 may adhere to the cured resin 204.

[0073] Refer to Figure 3 An example of the method of using the mold release film of the present invention in compression molding is described.

[0074] As Figure 3 As shown in (A), the mold release film 100 of the present invention is disposed between the lower mold 301 and the upper mold 303 (on which the substrate 302 carrying the semiconductor component is mounted). Here, the mold release film 100 is disposed such that the surface layer 102 formed of a tetrafluoroethylene resin containing a conductive filler contacts the resin 304 described later, and the other surface layer 103 contacts the inner surface of the lower mold 301 described later.

[0075] Subsequently, as Figure 3 shown in (B), with the mold release film 100 attached to the inner surface of the lower mold 301, the resin 304 is disposed in the recess of the lower mold 301. At this stage, the surface layer 102 formed of a tetrafluoroethylene resin containing a conductive filler contacts the resin 304, and the surface layer 103 contacts the inner surface of the lower mold 301.

[0076] As Figure 3 shown in (C), the upper mold 303 is moved to contact the lower mold 301. Then, the resin 304 is cured.

[0077] After curing, as Figure 3 shown in (D), the upper mold 303 is separated from the lower mold 301. Since the mold release film of the present invention has excellent mold release property, in Figure 3 the process of (D), the cured resin 304 can be smoothly demolded from the lower mold 301.

[0078] The mold release film of the present invention can be used for the molding of various resins, for example, it can be used for the molding of epoxy resins or silicone resins. The type of resin used to form the molded body can be appropriately selected by those skilled in the art.

[0079] The release film of the present invention can be used for molding, for example, more than 2 times, preferably more than 4 times, more preferably more than 5 times, more preferably more than 6 times, and even more preferably more than 8 times. The release film of the present invention can be used for molding, for example, from 2 to 20 times, preferably from 4 to 15 times, more preferably from 5 to 15 times, more preferably from 6 to 15 times, and even more preferably from 8 to 12 times. The release film of the present invention maintains the performance of the release film after multiple releases and is not easily damaged. Therefore, the release film of the present invention can be used for multiple molding. Thereby, the molding cost can be reduced.

[0080] (4) Details of the layer constituting the release film of the present invention

[0081] (4-1) Base material layer

[0082] The base material layer contained in the release film of the present invention is formed of a polyester resin. The polyester resin can be a resin containing polyester as a main component. The polyester can be, for example, PET (Polyethylene Terephthalate), PEN (Polyethylene Naphthalate), PBT (Polybutylene Terephthalate), PBN (Polybutylene Naphthalate), PCT (Polycyclohexylenedimethylene Terephthalate), PEB (Polyethylene-p-oxybenzoate), or polybis(phenoxycarboxylic acid)ethylene ester, or a mixture of one or more of them.

[0083] Preferably, the polyester resin is a polyethylene terephthalate resin. The polyethylene terephthalate resin can be a resin containing polyethylene terephthalate as a main component.

[0084] In this specification, the so-called "main component" refers to the component with the highest content ratio among the components constituting the resin. For example, when the main component of the resin is polyester, it can mean that, with respect to the mass of this resin, the content ratio of polyester 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, or it means that this resin is composed only of polyester. The same applies to the case where the main component of the resin is polyethylene terephthalate.

[0085] According to a preferred embodiment of the present invention, the base material layer contained in the release film may be formed of an easily moldable polyethylene terephthalate resin. The easily moldable polyethylene terephthalate resin (also referred to as easily moldable PET resin) is a term used to refer to a PET resin having more excellent formability than the more common polyethylene terephthalate resin. The formation of the base material layer from the easily moldable polyethylene terephthalate resin is particularly helpful for the low contamination property of the release film of the present invention.

[0086] According to a preferred embodiment of the present invention, the glass transition temperature of the polyester resin forming the base material layer is preferably 60°C to 95°C, more preferably 65°C to 90°C. For example, the easily moldable polyethylene terephthalate resin has a glass transition temperature within the aforementioned numerical range. The resin forming the base material layer having a glass transition temperature within this numerical range is helpful for enabling the release film of the present invention to be used in multiple moldings.

[0087] Generally, ordinary polyethylene terephthalate has a glass transition temperature of over 100°C. The glass transition temperature of the easily moldable polyethylene terephthalate resin composition is lower than that of the general polyethylene terephthalate.

[0088] The glass transition temperature is measured by DTA (Differential Thermal Analysis).

[0089] The easily moldable polyethylene terephthalate resin may, for example, be a copolymerized polyethylene terephthalate resin. The copolymerized polyethylene terephthalate can be obtained, for example, by reacting terephthalic acid, ethylene glycol, and a copolymerization component, or can also be obtained by mixing and melting a polymer of the copolymerization component with polyethylene terephthalate and then performing a distributive reaction.

[0090] The copolymerization component may be, for example, an acid component or an alcohol component. As the acid component, aromatic dicarboxylic acids (such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid, etc.), aliphatic dicarboxylic acids (such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, etc.), and alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid, etc.) can be cited. As the alcohol component, aliphatic diols (such as butanediol, hexanediol, neopentyl glycol, and hexanediol, etc.) and alicyclic diols (such as cyclohexanedimethanol, etc.) can be cited. As the copolymerization component, one or a combination of two or more of these compounds can be used. The acid component is particularly preferably isophthalic acid and / or sebacic acid.

[0091] As the base material layer formed of the easily moldable polyethylene terephthalate resin, commercially available products that can be obtained can also be used. For example, as the base material layer, the following can be used: Teflex (trademark) FT, Teflex (trademark) FT3, and Teflex (trademark) FW2 (all manufactured by Teijin Film Solution Co., Ltd.). In addition, as the base material layer, Emblet CTK-38 (manufactured by Unitika Ltd.) can be used.

[0092] The base material layer formed of the easily moldable polyethylene terephthalate resin can be manufactured, for example, by the methods described in Japanese Patent Laid-Open No. 2-305827, Japanese Patent Laid-Open No. 3-86729, or Japanese Patent Laid-Open No. 3-110124. According to a preferred embodiment of the present invention, the base material layer can be biaxially stretched with the surface orientation coefficient preferably being 0.06 to 0.16, more preferably 0.07 to 0.15, as described in any of these publications, using the easily moldable polyethylene terephthalate resin.

[0093] When the tensile breaking strength of the base material layer is measured at 175 °C in accordance with JIS (Japanese Industrial Standards) K7127, it is preferably 40 MPa to 200 MPa, more preferably 40 MPa to 120 MPa, still more preferably 40 MPa to 110 MPa, and particularly preferably 45 MPa to 100 MPa.

[0094] When the tensile breaking elongation of the base material layer is measured at 175 °C in accordance with JIS K7127, it is preferably 200% to 500%, more preferably 250% to 450%, still more preferably 300% to 400%.

[0095] The base material layer having a tensile breaking strength and / or a tensile breaking elongation within the above numerical ranges is helpful for enabling the release film of the present invention to be used in multiple moldings. The tensile breaking strength and the tensile breaking elongation within the above numerical ranges can be obtained, for example, by forming the base material layer from the easily moldable polyethylene terephthalate resin. The stretchability of the easily moldable polyethylene terephthalate resin is more excellent than that of general PET resins.

[0096] Since the polyester resin of the base material layer is an easily moldable polyethylene terephthalate resin, the release film of the present invention has low contamination during molding. Furthermore, the release film of the present invention can be used for multiple moldings. Hereinafter, the effects exhibited by the release film of the present invention will be described in detail.

[0097] The polyethylene terephthalate resin contains oligomers with a low degree of polymerization generated during the production of the polyethylene terephthalate resin. When using a release film containing a layer formed of the polyethylene terephthalate resin for molding, sometimes these oligomers transfer to the surface of the release film, thereby contaminating the molded article and / or the surface of the mold. Even if a surface layer such as a fluororesin layer is laminated on the surface area of the polyethylene terephthalate resin layer, this contamination will also occur. It is considered that the reason is that these oligomers penetrate through this fluororesin layer. In addition, this contamination is particularly likely to occur when using a single release film for multiple moldings. It is probably because heat is applied to the polyethylene terephthalate resin during molding, causing these oligomers to transfer from the inside of this resin to the surface.

[0098] The easily moldable polyethylene terephthalate resin also contains these oligomers. However, when the release film of the present invention has a structure in which a base material layer formed of the easily moldable polyethylene terephthalate resin and a surface layer formed of a tetrafluoroethylene resin containing a conductive filler are laminated, not only can electrostatic diffusibility be imparted to the release film, but also the contamination caused by these oligomers can be reduced or eliminated. Furthermore, the electrostatic diffusibility and low contamination property of the release film of the present invention are maintained even after multiple moldings.

[0099] In addition, generally, the release film is replaced with a new one every time a molding is performed. The reason is that if the release film that has been used for molding is used for molding again, the possibility of damage to this release film increases. For molding, damage to the release film is fatal, for example, it may cause an abnormality in the shape of the molded article or the mold may adhere to the molded article.

[0100] When the release film of the present invention has a structure in which a base material layer formed of the easily moldable polyethylene terephthalate resin and a surface layer formed of a tetrafluoroethylene resin containing a conductive filler are laminated, even if this release film is used for multiple moldings, it is not easily damaged and maintains the release property, electrostatic diffusibility, and low contamination property of the release film. Therefore, the release film of the present invention can be used for multiple moldings, thereby reducing the molding cost.

[0101] The thickness of the base material layer can be, for example, 10 μm to 80 μm, preferably 15 μm to 75 μm, and more preferably 20 μm to 70 μm. This thickness helps to enable the release film of the present invention to be used for multiple moldings.

[0102] (4-2) Surface layer formed of a tetrafluoroethylene resin containing a conductive filler

[0103] (4-2-1) Tetrafluoroethylene resin

[0104] The release film of the present invention includes a surface layer formed of a tetrafluoroethylene resin containing a conductive filler. This tetrafluoroethylene resin preferably contains no chlorine. By containing no chlorine, the durability and / or antifouling property of this layer is improved. This tetrafluoroethylene resin may be, for example, a cured product of a tetrafluoroethylene resin composition containing a tetrafluoroethylene polymer having a reactive functional group and a curing agent.

[0105] The tetrafluoroethylene polymer having a reactive functional group contained in the tetrafluoroethylene resin composition may be a tetrafluoroethylene polymer that can be cured by the curing agent. The reactive functional group and the curing agent can be appropriately selected by those skilled in the art.

[0106] The reactive functional group may be, for example, a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, or a silicon group, and preferably a hydroxyl group. Through these groups, the reaction for obtaining the cured product can proceed well.

[0107] Among these reactive functional groups, the hydroxyl group is particularly suitable for the reaction to obtain the cured product. That is, the tetrafluoroethylene polymer having a reactive functional group is preferably a hydroxyl group-containing tetrafluoroethylene polymer.

[0108] The fluorine-containing unit of the tetrafluoroethylene polymer having a reactive functional group is preferably a fluorine-containing unit based on a perfluoroolefin. This fluorine-containing unit based on a perfluoroolefin is more preferably based on one, two, or three selected from tetrafluoroethylene (Tetrafluoroethylene; hereinafter also referred to as "TFE" in this specification), hexafluoropropylene (HFP; Hexafluoropropylene), and perfluoro(alkyl vinyl ether) (PAVE) (Perfluoroalkylvinylether). It is preferred that among this fluorine-containing unit based on a perfluoroolefin, the fluorine-containing unit based on TFE is the most.

[0109] The hydroxyl value of the tetrafluoroethylene polymer having a reactive functional group (especially the hydroxyl value of the hydroxyl group-containing tetrafluoroethylene polymer) is preferably from 10 mgKOH / g to 300 mgKOH / g, more preferably from 10 mgKOH / g to 200 mgKOH / g, and even more preferably from 10 mgKOH / g to 150 mgKOH / g. By the hydroxyl value of the tetrafluoroethylene polymer having a reactive functional group being not less than the lower limit value of the foregoing numerical range, the curability of the resin composition can be good. In addition, the hydroxyl value of the tetrafluoroethylene polymer having a reactive functional group being not more than the upper limit value of the foregoing numerical range can contribute to making the cured product of this resin composition suitable for multiple molding. This hydroxyl value is obtained by measuring according to the method of JIS K 0070.

[0110] The acid value of the tetrafluoroethylene polymer containing reactive functional groups (especially the acid value of the tetrafluoroethylene polymer containing hydroxyl groups) is preferably from 0.5 mgKOH / g to 100 mgKOH / g, more preferably from 0.5 mgKOH / g to 50 mgKOH / g. When the acid value of the tetrafluoroethylene polymer containing reactive functional groups is above the lower limit value of the aforementioned numerical range, the curability of the resin composition can be good. In addition, when the acid value of the tetrafluoroethylene polymer containing reactive functional groups is below the upper limit value of the aforementioned numerical range, it can contribute to making the cured product of this resin composition suitable for multiple molding.

[0111] The reactive functional groups of the tetrafluoroethylene polymer containing reactive functional groups can be introduced into this tetrafluoroethylene polymer by copolymerizing a monomer having this reactive functional group with a fluorine-containing monomer (especially the aforementioned perfluoroolefin). That is, the tetrafluoroethylene polymer containing reactive functional groups may contain a polymerization unit based on a monomer containing reactive functional groups and a polymerization unit based on a fluorine-containing monomer (especially the aforementioned perfluoroolefin).

[0112] When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group is preferably a hydroxy-containing vinyl ether or a hydroxy-containing allyl ether. As the hydroxy-containing vinyl ether, for example, 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 can be cited. As the hydroxy-containing allyl ether, for example, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether can be cited. Instead, the monomer having the reactive functional group may also be a hydroxyalkyl ester of (meth)acrylic acid such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. As the monomer having the reactive functional group, one or a combination of two or more of these compounds can be used. When the reactive functional group is a hydroxyl group, from the viewpoint of the curability of the resin composition, the monomer having the reactive functional group is more preferably a hydroxy-containing vinyl ether, especially preferably 4-hydroxybutyl vinyl ether and / or 2-hydroxyethyl vinyl ether.

[0113] When the reactive functional group is a carboxyl group, the monomer having the reactive functional group is preferably an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid.

[0114] When the reactive functional group is an amino group, the monomer having the reactive functional group may be, for example, amino vinyl ether or allylamine.

[0115] When the reactive functional group is a silicon group, the monomer having the reactive functional group is preferably a silicone vinyl monomer.

[0116] The fluorine-containing monomer is preferably a perfluoroolefin. Examples of the perfluoroolefin include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE). It is preferred that the fluorine-containing monomer contains TFE.

[0117] It is preferred that the tetrafluoroethylene-based polymer containing a reactive functional group contains, in addition to the polymerization unit based on the monomer containing a reactive functional group and the polymerization unit based on the fluorine-containing monomer, a polymerization unit based on a non-fluorinated vinyl monomer. Examples of such non-fluorinated vinyl monomers may be one or a combination of two or more selected from the group consisting of vinyl carboxylates, alkyl vinyl ethers, and non-fluorinated olefins.

[0118] Examples of the vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl hexanoate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl benzoate, and vinyl p-tert-butylbenzoate.

[0119] Examples of the alkyl vinyl ether include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether.

[0120] Examples of the non-fluorinated olefin include ethylene, propylene, n-butene, and isobutene.

[0121] In addition, the tetrafluoroethylene-based polymer containing a reactive functional group may contain, for example, a polymerization unit based on a fluorine-based monomer other than perfluoroolefins such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluoro vinyl ether, in addition to the polymerization unit based on the monomer containing a reactive functional group and the polymerization unit based on the fluorine-containing monomer which is a perfluoroolefin.

[0122] The tetrafluoroethylene-based polymer containing a reactive functional group may be, for example, a TFE / non-fluorinated olefin / hydroxybutyl vinyl ether copolymer, a TFE / vinyl carboxylate / hydroxybutyl vinyl ether copolymer, or a TFE / alkyl vinyl ether / hydroxybutyl vinyl ether copolymer.

[0123] More specifically, the tetrafluoroethylene polymer containing reactive functional groups may be a TFE / isobutene / hydroxybutyl vinyl ether copolymer, a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer, or a TFE / VdF / hydroxybutyl vinyl ether copolymer. The tetrafluoroethylene polymer containing reactive functional groups is particularly preferably a TFE / isobutene / hydroxybutyl vinyl ether copolymer or a TFE / vinyl versatate / hydroxybutyl vinyl ether copolymer.

[0124] As the tetrafluoroethylene polymer containing reactive functional groups, for example, products of the Zeffle GK series can be used.

[0125] The curing agent contained in the tetrafluoroethylene resin composition can be appropriately selected by those skilled in the art according to the type of reactive functional groups contained in the tetrafluoroethylene polymer containing reactive functional groups.

[0126] When the reactive functional group is a hydroxyl group, the curing agent is preferably one or a combination of two or more selected from isocyanate curing agents, melamine resins, silicate compounds, and isocyanate group-containing silane compounds.

[0127] When the reactive functional group is a carboxyl group, the curing agent is preferably one or a combination of two or more selected from amine curing agents and epoxy curing agents.

[0128] When the reactive functional group is an amino group, the curing agent may be one or a combination of two or more selected from carbonyl group-containing curing agents, epoxy curing agents, and acid anhydride curing agents.

[0129] With respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the curing agent in the tetrafluoroethylene resin composition may be, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, and more preferably 23 parts by mass to 35 parts by mass. These numerical ranges also apply to the content of the curing agent in the cured product of this tetrafluoroethylene resin composition.

[0130] The content of the curing agent can be measured by pyrolysis gas chromatography-mass spectrometry (Py-GC / MS; Pyrolysis-Gas Chromatography / Mass Spectrometry) method.

[0131] In one embodiment of the present invention, the reactive functional group contained in the tetrafluoroethylene-based polymer containing a reactive functional group may be a hydroxyl group and the hardener may be an isocyanate-based hardener. In this embodiment, the isocyanate-based hardener is preferably a polyisocyanate of hexamethylene diisocyanate (HDI; Hexamethylene diisocyanate).

[0132] With respect to 100 parts by mass of the tetrafluoroethylene-based polymer containing a reactive functional group, the content of the HDI-based polyisocyanate in the tetrafluoroethylene-based resin composition may be, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, and more preferably 23 parts by mass to 35 parts by mass. These numerical ranges also apply to the content of the HDI-based polyisocyanate in the cured product of this tetrafluoroethylene-based resin composition.

[0133] As the HDI-based polyisocyanate, for example, one or a combination of two or more selected from isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates can be used. In the present invention, the isocyanate-based hardener is preferably 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.

[0134] When a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate is used as the hardener, the mass ratio of the two is, for example, 10:6 to 10:10, preferably 10:7 to 10:9. With respect to 100 parts by mass of the tetrafluoroethylene-based polymer containing a reactive functional group, the total amount of the two may be, for example, 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.

[0135] The content ratio of these hardeners can be determined by pyrolysis gas chromatography (Py-GC / MS) method.

[0136] (4-2-2) Conductive filler

[0137] The tetrafluoroethylene-based resin forming the surface layer contains a conductive filler. The conductive filler may be, for example, one or a combination of two or more selected from metal-based conductive fillers, carbon-based conductive fillers, metal oxide-based conductive fillers, and metal-plated conductive fillers.

[0138] Examples of the metal-based conductive fillers include, for example, powdery conductive fillers such as silver, copper, nickel, tin, and silver-plated copper powder; and fibrous conductive fillers such as copper, stainless steel, aluminum, brass, and iron fibers. Examples of the carbon-based conductive fillers include, for example, powdery conductive fillers such as carbon black and graphite; and fibrous conductive fillers such as carbon nanotubes (CNT; Carbon Nanotube) and carbon fibers. Examples of the metal oxide-based conductive fillers include, for example, powdery conductive fillers such as tin oxide, indium oxide, and zinc oxide powder. Examples of the metal-plated conductive fillers include, for example, powdery conductive fillers such as glass beads or mica powder plated with metal, and fibrous conductive fillers such as glass fibers or carbon fibers plated with metal.

[0139] The conductive filler is preferably the carbon-based conductive filler, and may be, for example, a powdery conductive filler of carbon type or a fibrous conductive filler of carbon type as described above.

[0140] With respect to 100 parts by mass of the tetrafluoroethylene-based polymer containing reactive functional groups, the content of the conductive filler in the tetrafluoroethylene-based resin composition may be, for example, 1 part by mass to 25 parts by mass, preferably 1 part by mass to 23 parts by mass. These numerical ranges are also applicable to the content of the conductive filler in the cured product of this tetrafluoroethylene-based resin composition.

[0141] The conductive filler preferably contains carbon black. The conductive filler may also be only carbon black. As carbon black, for example, one or a combination of two or more selected from Ketjen black, furnace black, acetylene black, channel black, thermal black, and lamp black can be used. The conductive filler preferably contains either or both of Ketjen black and furnace black. Ketjen black and furnace black are particularly suitable for imparting electrostatic diffusibility to the release film of the present invention.

[0142] Ketjen black has a small primary particle size and a hollow structure, so the filling amount per unit weight is large. Therefore, electrostatic diffusibility is imparted to the release film using a small amount of Ketjen black.

[0143] According to a preferred embodiment of the present invention, the carbon black contained in the tetrafluoroethylene-based resin forming the surface layer contains Ketjen black. The carbon black may also be only Ketjen black, for example.

[0144] When the conductive filler contains Ketjen black, with respect to 100 parts by mass of the tetrafluoroethylene-based polymer containing reactive functional groups, the content of Ketjen black in the tetrafluoroethylene-based 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. These numerical ranges are also applicable to the content of Ketjen black in the cured product of this tetrafluoroethylene-based resin composition.

[0145] When the tetrafluoroethylene resin forming the surface layer contains Ketjen black and does not contain the particles described in the following "(4-2-3) particles", it is preferable that the content of the Ketjen black is 3 parts by mass or more with respect to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group. Thereby, the surface resistivity Rs can be set to, for example, 1×10 8 Ω or less, and particularly can be set to 5×10 7 Ω or less. In this case, with respect to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group, the content of the Ketjen black is, for example, 3 parts by mass to 15 parts by mass, and more preferably 5 parts by mass to 10 parts by mass.

[0146] When the tetrafluoroethylene resin forming the surface layer contains Ketjen black and contains the particles (especially silica particles) described in the following "(4-2-3) particles", with respect to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group, the content of the Ketjen black can be 1 part by mass or more. By the combination of the particles and the Ketjen black, the surface resistivity Rs can be set to, for example, 1×10 8 Ω or less, and particularly can be set to 5×10 7 Ω or less. In addition, by the combination of the particles and the Ketjen black, the dispersibility of the Ketjen black in the tetrafluoroethylene resin composition can be improved. Thereby, a better appearance of the release film surface can be obtained.

[0147] According to one of the particularly preferred embodiments of the present invention, the carbon black contained in the tetrafluoroethylene resin forming the surface layer includes Ketjen black and furnace black. The carbon black may also be only a combination of, for example, Ketjen black and furnace black.

[0148] When the conductive filler contains Ketjen black and furnace black, with respect to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group, the content of the Ketjen black in the tetrafluoroethylene resin composition is preferably 1 part by mass to 10 parts by mass, more preferably 2 parts by mass to 9 parts by mass, and still more preferably 3 parts by mass to 8 parts by mass. These numerical ranges also apply to the content of the Ketjen black in the cured product of this tetrafluoroethylene resin composition. In this case, with respect to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group, the content of the furnace black in the tetrafluoroethylene resin composition can be, for example, 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. These numerical ranges also apply to the content of the furnace black in the cured product of this tetrafluoroethylene resin composition.

[0149] When the tetrafluoroethylene resin forming the surface layer contains Ketjen black and furnace black but does not contain the particles described in the following “(4-2-3) particles”, with respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the Ketjen black is preferably 1 part by mass to 10 parts by mass, more preferably 2 parts by mass to 9 parts by mass, and still more preferably 3 parts by mass to 8 parts by mass. These numerical ranges are also applicable to the content of the Ketjen black in the cured product of this tetrafluoroethylene resin composition. In the above case, with respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the furnace black in the tetrafluoroethylene resin composition may be, for example, 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. By adopting the contents within these numerical ranges, the surface resistivity Rs can be set to, for example, 1×10 8 Ω or less, and particularly can be set to 5×10 7 Ω or less.

[0150] When the tetrafluoroethylene resin forming the surface layer contains Ketjen black, furnace black and the particles (especially silica particles) described in the following “(4-2-3) particles”, with respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the Ketjen black in the tetrafluoroethylene resin composition is preferably 1 part by mass to 8 parts by mass, more preferably 2 parts by mass to 7 parts by mass, and still more preferably 3 parts by mass to 6 parts by mass. These numerical ranges are also applicable to the content of the Ketjen black in the cured product of this tetrafluoroethylene resin composition. In the above case, with respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the furnace black in the tetrafluoroethylene resin composition may be, for example, 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. By adopting the contents within these numerical ranges, the surface resistivity Rs can be set to, for example, 1×10 8 Ω or less, and particularly can be set to 5×10 7 Ω or less.

[0151] The DBP oil absorption of the Ketjen black is preferably 250 ml / 100 g or more, more preferably 280 ml / 100 g or more, and still more preferably 300 ml / 100 g or more. The DBP oil absorption of the Ketjen black is, for example, 1000 ml / 100 g or less, particularly 800 ml / 100 g or less, and still more particularly may be 600 ml / 100 g or less.

[0152] In this specification, the DBP oil absorption is a value measured by the method according to JIS K6217-4.

[0153] The iodine adsorption amount of the Ketjen black is preferably 500 mg / g or more, more preferably 600 mg / g or more, and still more preferably 700 mg / g or more. The iodine adsorption amount of the Ketjen black is preferably 1500 mg / g or less, more preferably 1400 mg / g or less, and still more preferably 1200 mg / g or less.

[0154] In this specification, the iodine adsorption amount is a value measured by the method according to JIS K6217-1.

[0155] The Ketjen black is preferably in powder form. By being in powder form, the appearance of the surface layer is improved. Regarding the average particle size of the powdered Ketjen black, the average particle size preferably measured by the laser diffraction particle size analysis method may be 1 μm to 20 μm, more preferably 3 μm to 17 μm, still more preferably 5 μm to 15 μm, and particularly preferably 7 μm to 13 μm. The average particle size is the volume-averaged diameter weighted by volume and is measured according to JIS Z8825. The average particle size can be measured, for example, using a particle size analysis measuring device (SALD-2200, Shimadzu Corporation). It is generally considered that containing such fine particles in the content ratio within the above numerical range will contribute to the improvement of dispersibility and / or the improvement of appearance.

[0156] The porosity of the Ketjen black is preferably 50% by volume or more, more preferably 52% by volume or more, and still more preferably 55% by volume or more. The porosity of the Ketjen black is, for example, 90% by volume or less, particularly 85% by volume or less, and even more particularly 80% by volume or less. In this specification, the porosity is the ratio of the pore volume to the total of the carbon volume and the pore volume as shown in the following formula.

[0157] Porosity (% by volume) = A÷(A + B)×100.

[0158] (A: Pore volume per unit mass (cm 3 / g), B: Carbon volume per unit mass (cm 3 / g)).

[0159] A is the amount of gas adsorption (physical adsorption) measured by a pore distribution measuring device. B is the reciprocal of the true density (g / cm 3 ), and this true density is measured by the pycnometer method.

[0160] According to a preferred embodiment, the carbon black contained in the tetrafluoroethylene resin forming the surface layer contains furnace black in addition to Ketjen black. The carbon black may be only, for example, Ketjen black and furnace black. By the carbon black containing Ketjen black and furnace black, the appearance of the release film is improved. More specifically, the black color on the surface of the release film becomes more uniform.

[0161] The DBP oil absorption of the furnace black is preferably 200 ml / 100 g or less, more preferably 150 ml / 100 g or less, and still more preferably 100 ml / 100 g or less. The DBP oil absorption of the furnace black is, for example, 40 ml / 100 g or more, particularly 50 ml / 100 g or more, and still more particularly may be 60 ml / 100 g or more. This DBP oil absorption is a value measured by the method according to JIS K6217-4.

[0162] When the nitrogen adsorption specific surface area of the furnace black is measured according to JIS K6217-2, it is preferably 10 m 2 / g to 70 m 2 / g, more preferably 15 m 2 / g to 50 m 2 / g, still more preferably 20 m 2 / g to 40 m 2 / g.

[0163] The furnace black is preferably in powder form. By being in powder form, the appearance of the surface layer is improved. Regarding the average particle size of the powdered furnace black, the average particle size preferably measured by the electron microscope method can be 30 nm to 150 nm, more preferably 50 nm to 100 nm, still more preferably 60 nm to 90 nm, and particularly preferably 70 nm to 80 nm. The average particle size is the volume average diameter weighted by volume and is measured according to JIS Z8825. The average particle size can be measured, for example, using a particle size analysis measuring device (SALD-2200, Shimadzu Corporation). It is generally considered that containing such fine particles in the ratio within the above numerical range will contribute to the improvement of dispersibility and / or appearance.

[0164] When measuring the pH value of the mixed solution obtained by mixing the furnace black and distilled water with a glass electrode pH meter, it is preferably 5.5 to 8.5, more preferably 6 to 8, and still more preferably 6.5 to 7.5.

[0165] (4-2-3) Particles

[0166] The tetrafluoroethylene resin forming the surface layer preferably contains the following particles. The average particle diameter of these particles, as measured by laser diffraction particle size analysis, is 1 μm to 15 μm, more preferably 1 μm to 12 μm, and even more preferably 2 μm to 10 μm. These particles are particles other than the conductive filler, for example, particles other than carbon black. The average particle diameter is the volume-averaged diameter weighted by volume and is measured according to JIS Z8825. The average particle diameter can be measured, for example, using a particle size analysis measuring device (SALD-2200, manufactured by Shimadzu Corporation). By containing these particles, the required electrostatic diffusivity can be imparted to the release film using a smaller amount of carbon black. By containing these particles, the dispersibility of the conductive filler in the tetrafluoroethylene resin can be improved. The improvement of this dispersibility leads to an improvement in the appearance of the surface of the release film. In addition, by containing these particles, the releasability of the release film can also be improved.

[0167] The particles are preferably inorganic particles or organic particles. As inorganic particles, for example, the following can be cited: silica (especially amorphous silica), calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, alumina, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. As organic particles, for example, crosslinked polymer particles and calcium oxalate can be cited. In the present invention, the particles are preferably inorganic particles, more preferably silica particles, and even more preferably amorphous silica. The amorphous silica can be sol-gel type silica. As the amorphous silica, for example, the amorphous silica of the Sylysia series can be used.

[0168] With respect to 100 parts by mass of the tetrafluoroethylene polymer containing reactive functional groups, the content of the particles in the tetrafluoroethylene resin composition can be, for example, 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. These numerical ranges also apply to the content of the particles in the cured product of this tetrafluoroethylene resin composition.

[0169] The content of the particles can be measured by TGA (Thermogravimetric Analysis).

[0170] (4-2-4) Other components

[0171] The tetrafluoroethylene resin composition may contain a solvent. The type of solvent can be appropriately selected by those skilled in the art. As the solvent, for example, the following can be cited: butyl acetate, ethyl acetate, and methyl ethyl ketone (also called MEK). For example, a mixture of these three can be used as the solvent.

[0172] The tetrafluoroethylene resin composition may contain a release promoter. Examples of the release promoter include amino-modified methylpolysiloxane, epoxy-modified methylpolysiloxane, carboxyl-modified methylpolysiloxane, and carbitol-modified methylpolysiloxane. The release promoter is preferably amino-modified methylpolysiloxane.

[0173] With respect to 100 parts by mass of the tetrafluoroethylene polymer having reactive functional groups, the release promoter may be, for example, from 0.01 part by mass to 3 parts by mass, preferably from 0.05 part by mass to 2 parts by mass, more preferably from 0.1 part by mass to 1 part by mass. These numerical ranges are also applicable to the content of the release promoter in the cured product of this tetrafluoroethylene resin composition.

[0174] (4-2-5) Formation of the surface layer

[0175] The thickness of the surface layer is, for example, from 1 μm to 10 μm, preferably from 2 to 9 μm, more preferably from 3 μm to 8 μm.

[0176] The tetrafluoroethylene resin composition can be produced by mixing and stirring the above-described components by a method known to those skilled in the art. For the mixing and stirring, mixers such as a high-speed mixer, a homogenizing mixer, and a paint shaker can be used, for example. For the mixing and stirring, a dissolver such as an edge turbine type high-speed dissolver can also be used, for example.

[0177] The cured product of the tetrafluoroethylene resin composition is obtained by coating the tetrafluoroethylene resin composition on the surface of the substrate layer and heating at, for example, 100°C to 200°C, preferably 120°C to 180°C for, for example, 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds. This cured product forms the surface layer. The amount of the tetrafluoroethylene resin composition coated can be appropriately set by those skilled in the art according to the thickness of the surface layer to be formed.

[0178] The surface layer formed of the tetrafluoroethylene resin containing the conductive filler comes into contact with the molded article during the production of the molded article. In this specification, this surface layer is also referred to as the molded article side surface layer. The other surface layer (the surface layer that comes into contact with the mold during the production of the molded article) is also referred to as the mold side surface layer.

[0179] In a preferred embodiment of the present technology, the molded article side surface layer is formed of a cured product of a fluororesin composition containing the tetrafluoroethylene polymer having reactive functional groups (particularly a tetrafluoroethylene polymer having a hydroxyl group), the curing agent, the particles, the release promoter, and the conductive filler.

[0180] More preferably, the side surface layer of the shaped body is formed of a cured product of a tetrafluoroethylene resin composition containing a hydroxyl group-containing tetrafluoroethylene polymer, an HDI-based polyisocyanate, silica particles, an amino-modified methyl polysiloxane, and carbon black.

[0181] Having such a side surface layer of the shaped body is particularly helpful for imparting excellent electrostatic diffusibility and release properties to the release film of the present invention.

[0182] (4-3) Mold side surface layer

[0183] (4-3-1) Fluororesin

[0184] The mold side surface layer of the release film of the present invention can be formed of a fluororesin, for example. According to a preferred embodiment of the present invention, the fluororesin does not contain chlorine. By not containing chlorine, the durability and / or stain resistance of this layer is improved. This fluororesin can be, for example, a cured product of a fluororesin composition containing a fluoropolymer having a reactive functional group and a curing agent.

[0185] This fluororesin preferably contains a tetrafluoroethylene resin, and more preferably contains a tetrafluoroethylene resin as the main component. In this specification, the tetrafluoroethylene resin refers to a component obtained by a curing reaction of a tetrafluoroethylene polymer having a reactive functional group described below and a curing agent. The so-called tetrafluoroethylene resin as the main component means that this fluororesin is composed only of the tetrafluoroethylene resin, or the amount of the tetrafluoroethylene resin in the components contained in this fluororesin is the largest. For example, with respect to the total mass of this fluororesin, the content ratio of the tetrafluoroethylene resin in this fluororesin can be, for example, 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. With respect to the total mass of this fluororesin, this content ratio can be, for example, 99% by mass or less, particularly 98% by mass or less, and more particularly 97% by mass or less.

[0186] When this fluororesin is a tetrafluoroethylene resin, the mold side surface layer can be the same as the surface layer formed of a tetrafluoroethylene resin containing a conductive filler described in the aforementioned "(4-2) Surface layer formed of a tetrafluoroethylene resin containing a conductive filler", for example.

[0187] The fluoropolymer having a reactive functional group contained in the fluororesin composition can be a fluoropolymer capable of being cured by the curing agent. The reactive functional group and the curing agent can be appropriately selected by those skilled in the art.

[0188] The reactive functional group can be, for example, a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, or a silicon group, and preferably a hydroxyl group. Through these groups, the reaction for obtaining the cured product proceeds well.

[0189] Among these reactive functional groups, a hydroxyl group is particularly suitable for obtaining the reaction of the cured product. That is, the fluoropolymer containing reactive functional groups is preferably a fluoropolymer containing hydroxyl groups, and more preferably a tetrafluoroethylene-based polymer containing hydroxyl groups.

[0190] The fluorine-containing unit of the fluoropolymer containing reactive functional groups is preferably a fluorine-containing unit based on perfluoroolefins. This fluorine-containing unit based on perfluoroolefins is more preferably based on one, two or three selected from tetrafluoroethylene (tetrafluoroethylene, hereinafter also referred to as "TFE" in this specification), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE). It is preferred that among this fluorine-containing unit based on perfluoroolefins, the fluorine-containing unit based on TFE is the most.

[0191] The hydroxyl value of the fluoropolymer containing reactive functional groups (especially the hydroxyl value of the fluoropolymer containing hydroxyl groups) is preferably from 10 mgKOH / g to 300 mgKOH / g, more preferably from 10 mgKOH / g to 200 mgKOH / g, and still more preferably from 10 mgKOH / g to 150 mgKOH / g. When the hydroxyl value of the fluoropolymer containing reactive functional groups is above the lower limit value of the aforementioned numerical range, the curability of the resin composition can be good. In addition, when the hydroxyl value of the fluoropolymer containing reactive functional groups is below the upper limit value of the aforementioned numerical range, it can contribute to making the cured product of this resin composition suitable for multiple molding. This hydroxyl value is obtained by measuring according to the method of JIS K 0070.

[0192] The acid value of the fluoropolymer containing reactive functional groups (especially the acid value of the fluoropolymer containing hydroxyl groups) is preferably from 0.5 mgKOH / g to 100 mgKOH / g, more preferably from 0.5 mgKOH / g to 50 mgKOH / g. When the acid value of the fluoropolymer containing reactive functional groups is above the lower limit value of the aforementioned numerical range, the curability of the resin composition can be good. In addition, when the acid value of the fluoropolymer containing reactive functional groups is below the upper limit value of the aforementioned numerical range, it can contribute to making the cured product of this resin composition suitable for multiple molding.

[0193] The reactive functional groups of the fluoropolymer containing reactive functional groups can be introduced into this fluoropolymer by copolymerizing a monomer having this reactive functional group with a fluorine-containing monomer (especially the aforementioned perfluoroolefin). That is, the fluoropolymer containing reactive functional groups can contain a polymerization unit based on a monomer containing reactive functional groups and a polymerization unit based on a fluorine-containing monomer (especially the aforementioned perfluoroolefin).

[0194] When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group is preferably a hydroxyl group-containing vinyl ether or a hydroxyl group-containing allyl ether. As the hydroxyl group-containing vinyl ether, for example, 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 can be cited. As the hydroxyl group-containing allyl ether, for example, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether can be cited. Instead, the monomer having the reactive functional group may also be, for example, a hydroxyalkyl ester of (meth)acrylic acid such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. As the monomer having the reactive functional group, one or a combination of two or more of these compounds can be used. When the reactive functional group is a hydroxyl group, from the viewpoint of the curability of the resin composition, the monomer having the reactive functional group is more preferably a hydroxyl group-containing vinyl ether, and particularly preferably 4-hydroxybutyl vinyl ether and / or 2-hydroxyethyl vinyl ether.

[0195] When the reactive functional group is a carboxyl group, the monomer having the reactive functional group is preferably an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid.

[0196] When the reactive functional group is an amino group, the monomer having the reactive functional group may be, for example, an amino vinyl ether or an allylamine.

[0197] When the reactive functional group is a silicon group, the monomer having the reactive functional group is preferably a silicone vinyl monomer.

[0198] The fluorine-containing monomer is preferably a perfluoroolefin. As the perfluoroolefin, for example, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE) can be cited. It is preferred that the fluorine-containing monomer contains TFE.

[0199] Preferably, the fluorine-containing polymer having a reactive functional group may contain a polymerization unit based on a non-fluorinated vinyl monomer in addition to the polymerization unit based on the monomer having a reactive functional group and the polymerization unit based on the fluorine-containing monomer. This non-fluorinated vinyl monomer may be, for example, one or a combination of two or more selected from the group consisting of vinyl carboxylates, alkyl vinyl ethers, and non-fluorinated olefins.

[0200] As the vinyl carboxylate, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl hexanoate, vinyl capricate, vinyl laurate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl benzoate, and vinyl p-tert-butylbenzoate can be cited.

[0201] Examples of the alkyl vinyl ether include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether.

[0202] Examples of the non-fluorinated olefin include ethylene, propylene, 1-butene, and isobutene.

[0203] In addition, the fluoropolymer containing a reactive functional group may contain, for example, a polymerization unit based on a fluoromonomer other than a perfluoroolefin such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinylidene fluoride (VF), and fluoro vinyl ether, in addition to a polymerization unit based on a monomer containing a reactive functional group and a polymerization unit based on a fluoromonomer that is a perfluoroolefin.

[0204] The fluoropolymer containing a reactive functional group may be, for example, a TFE / non-fluorinated olefin / hydroxybutyl vinyl ether copolymer, a TFE / carboxylic acid vinyl ester / hydroxybutyl vinyl ether copolymer, or a TFE / alkyl vinyl ether / hydroxybutyl vinyl ether copolymer.

[0205] More specifically, the fluoropolymer containing a reactive functional group may be a TFE / isobutene / hydroxybutyl vinyl ether copolymer, a TFE / isodecanoic acid vinyl ester / hydroxybutyl vinyl ether copolymer, or a TFE / VdF / hydroxybutyl vinyl ether copolymer. The fluoropolymer containing a reactive functional group is particularly preferably a TFE / isobutene / hydroxybutyl vinyl ether copolymer or a TFE / isodecanoic acid vinyl ester / hydroxybutyl vinyl ether copolymer.

[0206] As the fluoropolymer containing a reactive functional group, for example, products of the Zeffle GK series can be used.

[0207] The curing agent contained in the fluororesin composition can be appropriately selected by those skilled in the art according to the type of the reactive functional group contained in the fluoropolymer containing a reactive functional group.

[0208] When the reactive functional group is a hydroxyl group, the curing agent is preferably one or a combination of two or more selected from isocyanate curing agents, melamine resins, silicate compounds, and isocyanate group-containing silane compounds.

[0209] When the reactive functional group is a carboxyl group, the curing agent is preferably one or a combination of two or more selected from amine curing agents and epoxy curing agents.

[0210] When the reactive functional group is an amino group, the curing agent may be one or a combination of two or more selected from carbonyl group-containing curing agents, epoxy curing agents, and acid anhydride curing agents.

[0211] Per 100 parts by mass of the fluoropolymer having reactive functional groups, the content of the hardener in the fluororesin composition may be, for example, 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass. These numerical ranges are also applicable to the content of the hardener in the cured product of this fluororesin composition.

[0212] The content of the hardener can be determined by pyrolysis gas chromatography (Py-GC / MS).

[0213] In one embodiment of the present invention, the reactive functional group contained in the fluoropolymer having reactive functional groups may be a hydroxyl group and the hardener may be an isocyanate hardener. In this embodiment, the isocyanate hardener is preferably a hexamethylene diisocyanate (HDI)-type polyisocyanate.

[0214] Per 100 parts by mass of the fluoropolymer having reactive functional groups, the content of the HDI-type polyisocyanate in the fluororesin composition may be, for example, 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 23 to 35 parts by mass. These numerical ranges are also applicable to the content of the HDI-type polyisocyanate in the cured product of this fluororesin composition.

[0215] As the HDI-type polyisocyanate, for example, one or a combination of two or more selected from isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates can be used. In the present invention, the isocyanate hardener is preferably 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.

[0216] When a combination of an isocyanurate-type polyisocyanate and an adduct-type polyisocyanate is used as the hardener, the mass ratio of the two is, for example, 10:6 to 10:10, preferably 10:7 to 10:9. Per 100 parts by mass of the fluoropolymer having reactive functional groups, the total amount of the two may be, for example, 15 to 50 parts by mass, preferably 20 to 40 parts by mass, and more preferably 25 to 35 parts by mass.

[0217] The content ratio of these hardeners can be determined by pyrolysis gas chromatography (Py-GC / MS).

[0218] (4-3-2) particles

[0219] The fluororesin forming the surface layer preferably contains the following particles, and the average particle diameter of the particles measured by the laser diffraction particle size analysis method is 1 μm to 15 μm, more preferably 1 μm to 12 μm, and still more preferably 2 μm to 10 μm. The average particle diameter is the volume average diameter weighted by volume and is measured according to JIS Z8825. The average particle diameter can be measured, for example, using a particle size analysis measuring device (SALD-2200, Shimadzu Corporation). By containing these particles, the releasability of the release film can be improved.

[0220] The type of the particles is as described in the aforementioned "(4-2-3) Particles", and this description also applies to the particles contained in the mold side surface layer. Therefore, the description related to the particles is omitted.

[0221] With respect to 100 parts by mass of the fluoropolymer containing reactive functional groups, the content of the particles in the fluororesin composition can be, for example, 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. These numerical ranges also apply to the content of the particles in the cured product of this fluororesin composition.

[0222] The content of the particles can be measured by thermogravimetric analysis (TGA).

[0223] (4-3-3) Other Components

[0224] The fluororesin composition may contain a solvent. The type of the solvent is as described in the aforementioned "(4-2-4) Other Components", and this description also applies to the solvent contained in the mold side surface layer.

[0225] The fluororesin composition may contain a release promoter. The type of the release promoter is as described in the aforementioned "(4-2-4) Other Components", and this description also applies to the solvent contained in the mold side surface layer. With respect to 100 parts by mass of the fluoropolymer containing reactive functional groups, the release promoter can be, for example, 0.01 parts by mass to 3 parts by mass, preferably 0.05 parts by mass to 2 parts by mass, and more preferably 0.1 parts by mass to 1 part by mass. These numerical ranges also apply to the content of the release promoter in the cured product of this fluororesin composition.

[0226] (4-3-4) Formation of the Mold Side Surface Layer

[0227] The thickness of the mold side surface layer is, for example, 1 μm to 10 μm, preferably 2 μm to 9 μm, and more preferably 3 μm to 8 μm.

[0228] The fluororesin composition can be produced by mixing and stirring the above-described components by methods known to those skilled in the art. For such mixing and stirring, for example, mixers such as high-speed mixers, homogeneous mixers, and coating oscillators can be used. For such mixing and stirring, for example, dissolvers such as edge turbine type high-speed dissolvers can also be used.

[0229] The cured product of the fluororesin composition is obtained by coating the fluororesin composition on the surface of the substrate layer and heating it at, for example, 100°C to 200°C, preferably 120°C to 180°C for, for example, 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds. This cured product forms the surface layer. The amount of the coated fluororesin composition can be appropriately set by those skilled in the art according to the thickness of the surface layer to be formed.

[0230] In a preferred embodiment of the present technology, the mold side surface layer is formed of a cured product of a fluororesin composition containing the fluoropolymer having a reactive functional group, the curing agent, and the particles.

[0231] More preferably, the mold side surface layer is formed of a cured product of a fluororesin composition containing a hydroxyl group-containing tetrafluoroethylene polymer, an HDI-based polyisocyanate, and silica particles.

[0232] Having such a mold side surface layer is particularly helpful for imparting excellent releasability to the release film of the present invention.

[0233] (5) Physical properties of the release film

[0234] According to a preferred embodiment of the present invention, the tensile fracture strength of the release film of the present invention is 40 MPa to 200 MPa when measured at 175°C in accordance with JIS K7127, more preferably 40 MPa to 120 MPa, still more preferably 40 MPa to 110 MPa, particularly preferably 45 MPa to 100 MPa, and the tensile fracture elongation of the release film is 200% to 500% when measured at 175°C in accordance with JIS K7127, more preferably 250% to 450%, still more preferably 300% to 400%.

[0235] The tensile fracture strength and tensile fracture elongation of the release film of the present invention being within the aforementioned numerical ranges are helpful for enabling the release film of the present invention to be used in multiple molding operations.

[0236] The gas (O 2 ) permeability of the release film of the present invention, when measured at 175°C in accordance with JIS K7126-1, is, for example, 5000 cc / m 2 ·24 hr·atm to 50000 cc / m2 ·24 hours·atm, particularly 5000 cc / m 2 ·24 hours·atm to 30000 cc / m 2 ·24 hours·atm, more particularly may be 5000 cc / m 2 ·24 hours·atm to 20000 cc / m 2 ·Less than 24 hours·atm. The release film of the present invention has such a low gas permeability. Therefore, by using the release film of the present invention for molding, mold contamination caused by gas generated from the resin is suppressed.

[0237] The thickness of the release film of the present invention is, for example, 30 μm to 100 μm, preferably 35 μm to 90 μm, and more preferably 40 to 80 μm. By the thickness of the release film of the present invention being within the foregoing numerical range, this release film is liable to deform following the shape of the mold.

[0238] 2. Second Embodiment (Method for Manufacturing Release Film)

[0239] The present invention also provides a method for manufacturing the release film described in the foregoing "1. First Embodiment (Release Film)". This manufacturing method includes: a surface layer forming step of forming a surface layer formed of a tetrafluoroethylene resin containing a conductive filler on one of the two surfaces of a base material layer formed of a polyester resin; the surface resistivity Rs of the manufactured release film is 1×10 11 Ω or less.

[0240] The surface layer forming step described above includes, for example: a coating step of coating a tetrafluoroethylene resin composition containing a conductive filler on one of the two surfaces of a base material layer formed of a polyester resin; and a hardening step of hardening the tetrafluoroethylene resin composition after this coating step.

[0241] Regarding the base material layer and the tetrafluoroethylene resin composition used in the coating step, since the content described in the foregoing "1. First Embodiment (Release Film)" is applicable, the descriptions related to these are omitted.

[0242] The coating step can be appropriately carried out by those skilled in the art in a manner to achieve the required layer thickness. For example, the tetrafluoroethylene resin composition can be coated on the two surfaces of the base material layer by a gravure roll method, a reverse roll method, an offset gravure method, a kiss coat method, a reverse kiss coat method, a wire bar coating method, a spray coating method, or an impregnation method. The apparatus for coating by these methods can be appropriately selected by those skilled in the art.

[0243] This hardening process includes heating the fluororesin composition at, for example, 100°C to 200°C, preferably 120°C to 180°C for, for example, 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds. By this heating, the fluororesin composition is hardened.

[0244] On the other side of these two sides, a tetrafluoroethylene resin composition may be coated and then hardened, or a fluororesin composition different from the tetrafluoroethylene resin composition may also be coated and then hardened. Regarding the tetrafluoroethylene resin composition and the fluororesin composition, the content described in the foregoing "1. First Embodiment (Release Film)" is applicable. For this hardening process, the related description of the hardening process described for the one side is applicable.

[0245] 3. Examples

[0246] Hereinafter, the present invention will be described in more detail based on examples. Furthermore, the examples described below are an example of representative examples of the present invention, and the scope of the present invention is not limited only to these examples.

[0247] [Comparative Example 1]

[0248] As the base material layer, a film formed of an easily moldable polyethylene terephthalate resin (Teflex FT, Teijin Limited, thickness 50 μm, glass transition temperature 90°C) was prepared.

[0249] Subsequently, two fluororesin compositions (hereinafter referred to as the resin composition for the mold side surface layer and the resin composition for the molded body side surface layer) for coating on this film were prepared. The resin composition for the mold side surface layer forms the surface layer in contact with the mold in the sealing process of the semiconductor device. The resin composition for the molded body side surface layer forms the surface layer in contact with the sealing resin (molded body) in this sealing process.

[0250] The resin composition for the mold side surface layer is prepared by mixing and stirring 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene-based polymer solution (Zeffle GK570, manufactured by Daikin Industries, Ltd., in which 65% by mass is a hydroxyl group-containing tetrafluoroethylene-based polymer), 11.47 parts by mass of amorphous silica (Sylysia 380, manufactured by FujiSylysia Chemical Ltd.), 10 parts by mass of an isocyanurate-type polyisocyanate (hardener, Sumidule N3300, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by mass of an adduct-type polyisocyanate (hardener, 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. The average particle diameter (the aforementioned volume average diameter) of the amorphous silica is 9.0 μm when measured by laser diffraction particle size analysis using a particle size analysis measuring device (SALD-2200, manufactured by Shimadzu Corporation).

[0251] The resin composition for the molded body side surface layer is prepared by mixing and stirring 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene-based polymer solution (Zeffle GK570, manufactured by Daikin Industries, Ltd., in which 65% by mass is a hydroxyl group-containing tetrafluoroethylene-based polymer), 10 parts by mass of an isocyanurate-type polyisocyanate (hardener, Sumidule N3300, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by mass of an adduct-type polyisocyanate (hardener, Duranate AE700-100), 0.31 parts by mass of an amine-modified methylpolysiloxane (release promoter, manufactured by Shin-Etsu Chemical Co., Ltd.), 6.18 parts by mass of butyl acetate, 44.62 parts by mass of ethyl acetate, and 89.25 parts by mass of MEK.

[0252] The resin composition for the mold side surface layer is coated on one side of the film, and the resin composition for the molded body side surface layer is coated on the other side of the film. These coatings are performed using a coating device with a gentle touch reverse method. After the coating, these compositions are hardened by heating at 150°C for 60 seconds to obtain a release film (hereinafter referred to as "the release film of Comparative Example 1") having fluororesin layers laminated on both sides of an easily moldable PET resin film.

[0253] The thickness of the release film of Comparative Example 1 was 70 μm ± 5 μm. The thickness of the base material layer in the release film of Comparative Example 1 was 50 μm ± 5 μm. In the two surface layers of the release film of Comparative Example 1, the thickness of the mold-side surface layer formed from the cured product of the resin composition for the mold-side surface layer was 5.5 μm ± 0.5 μm. The thickness of the molded-body-side surface layer formed from the cured product of the resin composition for the molded-body-side surface layer was 5.5 μm ± 0.5 μm.

[0254] Relative to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer, the cured product of the resin composition for the mold-side surface layer contained 17.65 parts by mass of the amorphous silica, 15.39 parts by mass of the isocyanurate-type polyisocyanate, and 11.98 parts by mass of the adduct-type polyisocyanate.

[0255] Relative to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer, the cured product of the resin composition for the molded-body-side surface layer contained 17.65 parts by mass of the amorphous silica, 15.39 parts by mass of the isocyanurate-type polyisocyanate, 11.98 parts by mass of the adduct-type polyisocyanate, and 0.48 part by mass of the amine-modified methyl polysiloxane.

[0256] [Comparative Example 2]

[0257] The amount of the hydroxyl group-containing tetrafluoroethylene-based polymer in the resin composition for the molded-body-side surface layer was reduced by 1 mass%, and acetylene black (ECP600JD, Lion Specialty Chemicals Co., Ltd., powdery) was added in the reduced amount. Otherwise, a release film (the release film of Comparative Example 2) was obtained by the same method as in Comparative Example 1. Regarding this acetylene black, the DBP oil absorption amount was 495 ml / 100 g, and the iodine adsorption amount was 1050 mg / g. The average particle diameter of this acetylene black was 10 μm when measured by the laser diffraction particle size analysis method.

[0258] That is, relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene-based polymer and acetylene black contained in the molded-body-side surface layer of the release film of Comparative Example 2, the amount of this hydroxyl group-containing tetrafluoroethylene-based polymer was 99 parts by mass, and relative to the aforementioned total amount of 100 parts by mass, the amount of this acetylene black was 1 part by mass.

[0259] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the molded-body-side surface layer of the release film of Comparative Example 2, the amount of acetylene black was 1.01 parts by mass.

[0260] [Example 1]

[0261] Reduce the amount of the hydroxyl group-containing tetrafluoroethylene polymer in the resin composition for the molded body side surface layer by 3% by mass, and add Ketjenblack (ECP600JP, Lion Corporation, in powder form) in the reduced mass. Otherwise, obtain a release film (the release film of Example 1) by the same method as in Comparative Example 1.

[0262] That is, relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjenblack contained in the molded body side surface layer of the release film of Example 1, the amount of this hydroxyl group-containing tetrafluoroethylene polymer is 97 parts by mass, and relative to the aforementioned total amount of 100 parts by mass, the amount of this Ketjenblack is 3 parts by mass.

[0263] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 1, the amount of Ketjenblack is 3.09 parts by mass.

[0264] [Example 2]

[0265] Reduce the amount of the hydroxyl group-containing tetrafluoroethylene polymer in the resin composition for the molded body side surface layer by 5% by mass, and add Ketjenblack (ECP600JP, Lion Corporation, in powder form) in the reduced mass. Otherwise, obtain a release film (the release film of Example 2) by the same method as in Comparative Example 1.

[0266] That is, relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjenblack contained in the molded body side surface layer of the release film of Example 2, the amount of this hydroxyl group-containing tetrafluoroethylene polymer is 95 parts by mass, and relative to the aforementioned total amount of 100 parts by mass, the amount of this Ketjenblack is 5 parts by mass.

[0267] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 2, the amount of Ketjenblack is 5.26 parts by mass.

[0268] [Example 3]

[0269] In the resin composition for the molded body side surface layer, further add amorphous silica (Sylysia 380, Fuji Silysia Chemical Ltd.) at a ratio of 15 parts by mass relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjenblack. Otherwise, obtain a release film (the release film of Example 3) by the same method as in Comparative Example 2.

[0270] That is, with respect to the total amount of 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer and Ketjen black contained in the formed body side surface layer of the release film of Example 3, the amount of this hydroxyl group-containing tetrafluoroethylene-based polymer is 99 parts by mass, and with respect to the total amount of 100 parts by mass, the amount of this Ketjen black is 1 part by mass.

[0271] In addition, with respect to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the formed body side surface layer of the release film of Example 3, the amount of Ketjen black is 1.01 parts by mass. With respect to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the formed body side surface layer of Example 3, the amount of amorphous silica particles is 15.15 parts by mass.

[0272] [Examples 4 and 5]

[0273] In the resin composition for the formed body side surface layer, amorphous silica (Sylysia 380, Fuji Silysia Chemical Ltd.) was further added at a ratio of 5 parts by mass or 15 parts by mass with respect to the total amount of 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer and Ketjen black. Except for this, release films (the release film of Example 4 and the release film of Example 5) were obtained by the same method as in Example 1.

[0274] That is, with respect to the total amount of 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer and Ketjen black contained in the formed body side surface layer of the release films of Example 4 and Example 5, the amount of this hydroxyl group-containing tetrafluoroethylene-based polymer is 97 parts by mass, and with respect to the total amount of 100 parts by mass, the amount of this Ketjen black is 3 parts by mass.

[0275] In addition, with respect to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the formed body side surface layer of the release films of Example 4 and Example 5, the amount of Ketjen black is 3.09 parts by mass in both cases. With respect to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the formed body side surface layer of the release films of Example 4 and Example 5, the amounts of amorphous silica particles are 5.15 parts by mass and 15.46 parts by mass respectively.

[0276] [Examples 6 and 7]

[0277] Except for using Carbon ECP (Lion Corporation) instead of ECP600JP as Ketjen black, release films (the release film of Example 6 and the release film of Example 7) were obtained by the same method as in Examples 4 and 5. Regarding Carbon ECP, the DBP oil absorption amount is 365 ml / 100 g, and the iodine adsorption amount is 790 mg / g. The average particle diameter of this Ketjen black is 10 μm when measured by the laser diffraction particle size analysis method.

[0278] [Example 8 and Example 9]

[0279] For the resin composition for the side surface layer of the molded body, amorphous silica (Sylysia 380, Fuji Silysia Chemical Ltd.) was further added at a ratio of 5 parts by mass or 15 parts by mass relative to a total of 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjenblack. Other than that, a release film (the release film of Example 8 and the release film of Example 9) was obtained by the same method as in Example 2.

[0280] That is, relative to a total of 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjenblack contained in the side surface layer of the molded body of the release films of Example 8 and Example 9, the amount of this hydroxyl group-containing tetrafluoroethylene polymer is 95 parts by mass, and relative to the aforementioned total of 100 parts by mass, the amount of this Ketjenblack is 5 parts by mass.

[0281] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene polymer contained in the side surface layer of the molded body of the release films of Example 8 and Example 9, the amount of Ketjenblack is 5.26 parts by mass in both cases. Relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene polymer contained in the side surface layer of the molded body of the release films of Example 4 and Example 5, the amounts of amorphous silica particles are 5.26 parts by mass and 15.79 parts by mass, respectively.

[0282] [Example 10]

[0283] As the base material layer, a film formed of an easily moldable polyethylene terephthalate resin (Teflex FT, Teijin Ltd., thickness 50 μm, glass transition temperature 90°C) was prepared.

[0284] Subsequently, two fluororesin compositions (hereinafter referred to as the resin composition for the mold side surface layer and the resin composition for the molded body side surface layer) for coating on this film were prepared. The resin composition for the mold side surface layer forms the surface layer in contact with the mold during the sealing process of the semiconductor device. The resin composition for the molded body side surface layer forms the surface layer in contact with the sealing resin (molded body) during this sealing process.

[0285] The resin composition for the mold side surface layer is the same as in Comparative Example 1.

[0286] The resin composition for the shaped body side surface layer is prepared by mixing and stirring 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene-based polymer solution (Zeffle GK570, Daikin Industries, Ltd., where 65% by mass is a hydroxyl group-containing tetrafluoroethylene-based polymer), 10 parts by mass of an isocyanurate-type polyisocyanate (hardening agent, Sumidule N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.8 parts by mass of an adduct-type polyisocyanate (hardening agent, Duranate AE700-100), 2.78 parts by mass of Ketjenblack (ECP600JD, Lion Corporation), 11.1 parts by mass of furnace black (Mitsubishi Black #10, Mitsubishi Chemical Corporation, average particle size of 75 nm, DBP oil absorption of 86 ml / 100 g), 13.9 parts by mass of amorphous silica (Sylysia 380, Fuji Silysia Chemical Ltd.), 0.6 parts by mass of an amino-modified methylpolysiloxane (release promoter, Shin-Etsu Chemical Co., Ltd.), 56.9 parts by mass of ethyl acetate, and 113.8 parts by mass of MEK.

[0287] The resin composition for the mold side surface layer and the resin composition for the shaped body side surface layer were coated on the film in the same manner as in Comparative Example 1, and then heated to harden these compositions, obtaining a release film having fluororesin layers laminated on both sides of an easily moldable PET resin film (hereinafter referred to as "the release film of Example 10").

[0288] The thickness of the release film of Example 10 is 70 μm ± 5 μm. The thickness of the base material layer in the release film of Example 10 is 50 μm ± 5 μm. In the two surface layers of the release film of Example 10, the thickness of the mold side surface layer formed from the hardened product of the resin composition for the mold side surface layer is 5.5 μm ± 0.5 μm. The thickness of the shaped body side surface layer formed from the hardened product of the resin composition for the shaped body side surface layer is 5.5 μm ± 0.5 μm.

[0289] Relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene-based polymer, Ketjenblack, furnace black, and silica particles contained in the shaped body side surface layer of the release film of Example 10, the amount of this hydroxyl group-containing tetrafluoroethylene-based polymer is 70 parts by mass, and relative to the aforementioned total amount of 100 parts by mass, the amounts of this Ketjenblack, furnace black, and silica particles are 3 parts by mass, 12 parts by mass, and 15 parts by mass, respectively.

[0290] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the shaped body side surface layer of the release film of Example 10, the amounts of Ketjenblack, furnace black, and silica particles are 4.29 parts by mass, 17.14 parts by mass, and 21.43 parts by mass, respectively.

[0291] [Examples 11 and 12]

[0292] Release films (the release film of Example 11 and the release film of Example 12) were obtained by the same method as in Example 10, except that carbon ECP and ECP200L (both from Lion Corporation) were used instead of ECP600JD as Ketjenblack.

[0293] [Example 13]

[0294] A release film was obtained by the same method as in Example 10, except that the amounts of this Ketjenblack and this furnace black relative to 100 parts by mass in total of the hydroxyl group-containing tetrafluoroethylene-based polymer, Ketjenblack, furnace black, and silica particles were changed to 0 part by mass and 15 parts by mass, respectively.

[0295] Relative to 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the surface layer on the molded article side of the release film of Example 13, the amounts of Ketjenblack and furnace black were 0 part by mass and 21.43 parts by mass, respectively.

[0296] [Example 14]

[0297] As the base material layer, a film (Teflex FT, Teijin Limited, thickness 50 μm, glass transition temperature 90°C) formed of an easily moldable polyethylene terephthalate resin was prepared.

[0298] Subsequently, two fluororesin compositions (hereinafter referred to as the resin composition for the surface layer on the mold side and the resin composition for the surface layer on the molded article side) for coating on this film were prepared. The resin composition for the surface layer on the mold side forms the surface layer in contact with the mold in the sealing process of the semiconductor device. The resin composition for the surface layer on the molded article side forms the surface layer in contact with the sealing resin (molded article) in this sealing process.

[0299] The resin composition for the surface layer on the mold side was the resin composition for the surface layer on the mold side of Comparative Example 1.

[0300] The resin composition for the shaped body side surface layer is prepared by mixing and stirring 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene-based polymer solution (Zeffle GK570, Daikin Industries, Ltd., where 65% by mass is a hydroxyl group-containing tetrafluoroethylene-based polymer), 10 parts by mass of an isocyanurate-type polyisocyanate (hardening agent, Sumidule N3300, Sumitomo Bayer Polyurethane Co., Ltd.), 7.8 parts by mass of an adduct-type polyisocyanate (hardening agent, Duranate AE700-100), 2.78 parts by mass of Ketjenblack (ECP600JD, Lion Corporation), 11.1 parts by mass of furnace black (Mitsubishi Black #10, Mitsubishi Chemical Corporation), 0.6 parts by mass of an amine-modified methylpolysiloxane (release promoter, Shin-Etsu Chemical Co., Ltd.), 48.6 parts by mass of ethyl acetate, and 97.1 parts by mass of MEK.

[0301] The resin composition for the mold side surface layer and the resin composition for the shaped body side surface layer were coated on the film in the same manner as in Comparative Example 1, and then heated to harden these compositions, obtaining a release film having fluororesin layers laminated on both surfaces of an easily moldable PET resin film (hereinafter referred to as "the release film of Example 14").

[0302] The thickness of the release film of Example 14 is 70 μm ± 5 μm. The thickness of the base material layer in the release film of Example 14 is 50 μm ± 5 μm. In the two surface layers of the release film of Example 14, the thickness of the mold side surface layer formed by the hardened product of the resin composition for the mold side surface layer is 5.5 μm ± 0.5 μm. The thickness of the shaped body side surface layer formed by the hardened product of the resin composition for the shaped body side surface layer is 5.5 ± 0.5 μm.

[0303] Relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene-based polymer, Ketjenblack, and furnace black contained in the shaped body side surface layer of the release film of Example 14, the amount of this hydroxyl group-containing tetrafluoroethylene-based polymer is 85 parts by mass, and relative to the aforementioned total amount of 100 parts by mass, the amounts of this Ketjenblack and furnace black are 3 parts by mass and 12 parts by mass, respectively.

[0304] In addition, relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene-based polymer contained in the shaped body side surface layer of the release film of Example 14, the amounts of Ketjenblack and furnace black are 3.53 parts by mass and 14.12 parts by mass, respectively.

[0305] [Example 15]

[0306] The amount of the hydroxyl group-containing tetrafluoroethylene polymer relative to 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer, Ketjen black, and furnace black contained in the surface layer of the molded body was changed to 92 parts by mass, and the amounts of this Ketjen black and furnace black relative to 100 parts by mass of the aforementioned total amount were changed to 3 parts by mass and 5 parts by mass, respectively. Except for this, a release film (the release film of Example 15) was obtained by the same method as in Example 14.

[0307] Relative to 100 parts by mass of the amount of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer of the molded body of the release film of Example 15, the amounts of Ketjen black and furnace black were 3.26 parts by mass and 5.43 parts by mass, respectively.

[0308] [Examples 16 and 17]

[0309] Except for using carbon ECP instead of ECP600JD as Ketjen black, release films (the release film of Example 16 and the release film of Example 17) were obtained by the same method as in Example 14 and Example 15.

[0310] [Examples 18 and 19]

[0311] Except for using ECP200L instead of ECP600JD as Ketjen black, release films (the release film of Example 18 and the release film of Example 19) were obtained by the same method as in Example 14 and Example 15.

[0312] The compositions of the surface layers of the molded bodies of the release films of Comparative Example 1, Comparative Example 2, and Examples 1 to 19 are shown in Tables 1 to 3.

[0313] [Table 1]

[0314]

[0315]

[0316] [Table 2]

[0317]

[0318] [Table 3]

[0319]

[0320] For the release films of Comparative Example 1, Comparative Example 2, and Examples 1 to 19, the surface resistivity Rs of the surface layer of the molded body was measured and evaluated according to the following criteria. Furthermore, "E+" related to the surface resistivity Rs in the table means a power of 10. For example, "4.9.E+09" in Example 3 means 4.9×10 9The same applies to the surface resistivity Rs in other examples. The evaluation results are shown in Tables 1 to 3 described above.

[0321] A: Rs is 1×10 9 Ω or less.

[0322] B: Rs exceeds 1×10 9 Ω and is 1×10 11 Ω or less.

[0323] C: Rs exceeds 1×10 11 Ω.

[0324] In addition, the dispersibility of carbon black in the resin composition for the surface layer on the molded body side in the production of the release films of Comparative Example 1 and Comparative Example 2 and Examples 1 to 19 was evaluated. The evaluation of the dispersibility was carried out in accordance with JIS K5600-2-5 using a fineness gauge (Model 232 fineness gauge manufactured by Erichsen GmbH & Co. KG). The evaluation results are shown in Tables 1 to 3 described above.

[0325] A: Streaks appear.

[0326] B: Streaks appear with a groove depth of 35 μm or less.

[0327] C: Streaks appear with a groove depth of 40 μm or less.

[0328] For the release films of Comparative Example 1 and Comparative Example 2 and Examples 1 to 19, the appearance of the surface on the molded body side was visually evaluated. The evaluation criteria are as follows. The evaluation results are shown in Tables 1 to 3 described above.

[0329] A: There is no unevenness in the black color on the surface.

[0330] B: There is slightly uneven black color on the surface.

[0331] C: There is uneven black color on the surface.

[0332] From the evaluation results shown in Tables 1 to 3 described above, the following was found.

[0333] It was found that the release films of Examples 1 to 19 all have a surface resistivity Rs of 1×10 11 Ω or less and have electrostatic diffusibility.

[0334] The surface layer on the molded body side of the release film of Comparative Example 1 does not contain carbon black, and the surface resistivity Rs exceeds 1×10 11 Ω. In addition, although the surface layer on the molded body side of the release film of Comparative Example 2 contains Ketjenblack, the surface resistivity Rs exceeds 1×10 11Ω. On the other hand, in Example 1 and Example 2 where the content of Ketjen black is higher than that of Comparative Example 2, the surface resistivity Rs is 1×10 11 Ω or less. From these results, it can be seen that when the conductive filler is Ketjen black, by setting the content of the Ketjen black to, for example, 3 parts by mass or more relative to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene-based polymer, the release film can be imparted with electrostatic diffusibility.

[0335] The forming body side surface layer of the release film of Comparative Example 2 does not contain Ketjen black, but the surface resistivity Rs exceeds 1×10 11 Ω. On the other hand, in the release film of Example 3 which has the same amount of Ketjen black and further contains silica particles, the surface resistivity Rs is 1×10 11 Ω or less. From these results, it can be seen that by combining Ketjen black and silica particles, the release film can be imparted with electrostatic diffusibility. It is also known that when silica particles are contained, the release film can be imparted with electrostatic diffusibility with a smaller amount of Ketjen black. For example, when silica particles are contained, the amount of Ketjen black can be 1 part by mass or more relative to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene-based polymer.

[0336] From the comparison of the release films of Example 3 and Example 5, it can be seen that when silica particles are contained, by setting the amount of Ketjen black to 3 parts by mass or more relative to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene-based polymer, the electrostatic diffusibility of the release film can be improved.

[0337] From the comparison of the release films of Example 4 and Example 5 with Example 6 and Example 7, it can be seen that even if the type of Ketjen black is changed, good electrostatic diffusibility can be obtained.

[0338] In addition, from the comparison of the release films of Example 4 and Example 5 with Example 8 and Example 9, it can be seen that even if the amount of Ketjen black is increased, good electrostatic diffusibility can be obtained.

[0339] From the comparison of the release films of Example 1 and Example 5, it can be seen that in addition to Ketjen black, further containing silica particles can improve the dispersibility of the composition for preparing the forming body side surface layer and can improve the appearance of the obtained forming body side surface layer.

[0340] In Examples 3 to 9, the evaluation result of electrostatic diffusibility is A. In contrast, the evaluations of dispersibility and appearance are B. On the other hand, in Examples 10 to 12, the evaluation result of electrostatic diffusibility is A, and further the evaluations of dispersibility and appearance are also A. From these results, it can be seen that in addition to Ketjen black and silica particles, further containing furnace black can obtain good electrostatic diffusibility, and can improve the dispersibility of the composition for preparing the forming body side surface layer and improve the appearance of the obtained forming body side surface layer.

[0341] From the comparison between Examples 10 to 12 and Example 13, it is known that by combining furnace black and silica particles, good electrostatic diffusibility can also be obtained, and the dispersibility of the composition for preparing the side surface layer of the molded body can be improved, and the appearance of the obtained side surface layer of the molded body can be improved.

[0342] From the results of Examples 14 to 18, it is known that by combining Ketjen black and furnace black, good electrostatic diffusibility can also be obtained. In addition, it is known that this combination can also improve the dispersibility of the composition for preparing the side surface layer of the molded body. Furthermore, although the degree of improvement is inferior to that of Examples 10 to 12 containing silica particles, from the results of Examples 14 to 18, it is known that by this combination, the appearance of the side surface layer of the molded body can be improved.

[0343] In addition, using the release films of Comparative Example 1 and Comparative Example 2 and Examples 1 to 19, molding of epoxy resin was carried out by transfer molding. This molding was carried out as Figure 2 shown. As a result, in the case of using any of the release films, the molded bodies of the epoxy resin were smoothly peeled off from the release films. From this, it is known that although the side surface layer of the molded body of the release film of the present invention contains a conductive filler, it has the same releasability as the case where no conductive filler is contained. In addition, the releasability of the release films of Comparative Example 1 and Comparative Example 2 and Examples 1 to 19 was maintained after multiple moldings.

[0344] (Explanation of symbols)

[0345] 100: Release film

[0346] 101: Substrate layer

[0347] 102: Surface layer

[0348] 103: Surface layer

Claims

1. A release film having: A base material layer formed of a polyester resin; and A surface layer formed of a tetrafluoroethylene resin containing a conductive filler; Further, the surface resistivity Rs is 1×10 11 Ω or less; The conductive filler includes carbon black; The carbon black includes Ketjen black, and the average particle size of the Ketjen black is 3 μm to 17 μm as measured by laser diffraction particle size analysis; The carbon black further includes furnace black; The dibutyl phthalate oil absorption amount of the furnace black is 200 ml / 100 g or less; The tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a tetrafluoroethylene polymer having a reactive functional group and a curing agent; The tetrafluoroethylene polymer having a reactive functional group contains a polymerization unit based on a hydroxyl group-containing monomer and a polymerization unit based on a perfluoroolefin; The tetrafluoroethylene resin contains silica particles; The average particle size of the silica particles is 1 μm to 15 μm as measured by laser diffraction particle size analysis; and The amount of the silica particles relative to 100 parts by mass of the tetrafluoroethylene resin is 3 parts by mass to 30 parts by mass.

2. The release film according to claim 1, Characterized in that The cured product is a cured product of the tetrafluoroethylene resin composition coated on the surface of the base material layer.

3. The release film according to claim 1 or 2, Characterized in that The dibutyl phthalate oil absorption amount of the Ketjen black is 250 ml / 100 g or more.

4. The release film according to claim 1 or 2, Characterized in that The curing agent is an isocyanate curing agent.

5. The release film according to claim 4, Characterized in that The isocyanate curing agent is one or a combination of two or more selected from isocyanurate type polyisocyanates, adduct type polyisocyanates, and biuret type polyisocyanates.

6. The release film according to claim 1 or 2, Characterized in that Relative to 100 parts by mass of the tetrafluoroethylene polymer having a reactive functional group, the content of the conductive filler in the tetrafluoroethylene resin composition is 1 part by mass to 25 parts by mass.

7. The release film according to claim 1 or 2, Characterized in that The polyester resin is a polyethylene terephthalate resin.

8. The release film according to claim 1 or 2, Characterized in that The glass transition temperature of the polyester resin is 60 °C to 95 °C.

9. The release film according to claim 1 or 2, Characterized in that The surface layer is laminated on one of the two sides of the base material layer.

10. The release film according to claim 9, Characterized in that A surface layer formed of a fluororesin is laminated on the other of the two sides of the base material layer.

11. The release film according to claim 1 or 2, Characterized in that It is used for sealing semiconductor devices.

12. The release film according to claim 11, Characterized in that In the sealing, the surface layer formed of the tetrafluoroethylene resin containing the conductive filler is arranged in a manner of contacting the sealing resin.

13. The release film according to claim 1 or 2, Characterized in that It is used for transfer molding or compression molding.

14. The release film according to claim 1 or 2, characterized in that, it is used for forming more than twice.

15. A method for manufacturing a release film, comprising: a surface layer forming step of forming a surface layer formed of a tetrafluoroethylene resin containing a conductive filler on one of the two surfaces of a substrate layer formed of a polyester resin; the conductive filler contains carbon black; the carbon black contains Ketjen black, and the average particle size of the Ketjen black is 3 μm to 17 μm when measured by a laser diffraction particle size analysis method; the carbon black further contains furnace black; the dibutyl phthalate oil absorption amount of the furnace black is 200 ml / 100 g or less; the tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a tetrafluoroethylene polymer having a reactive functional group and a curing agent; the tetrafluoroethylene polymer having a reactive functional group contains a polymerization unit based on a hydroxyl group-containing monomer and a polymerization unit based on a perfluoroolefin; the tetrafluoroethylene resin contains silica particles; the average particle size of the silica particles is 1 μm to 15 μm when measured by a laser diffraction particle size analysis method; the amount of the silica particles relative to 100 parts by mass of the tetrafluoroethylene resin is 3 parts by mass to 30 parts by mass; and The surface resistivity Rs of the manufactured release film is 1×10 11 Ω or less.

16. The method for manufacturing a release film according to claim 15, characterized in that, in the surface layer forming step, the tetrafluoroethylene resin composition coated on the surface of the substrate layer is cured to form the cured product.

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