JP7370537B2 - Release film and method for producing release film - Google Patents

Description

The present invention relates to a release film and a method for manufacturing the same, more specifically a release film used for sealing a semiconductor device and a method for manufacturing the same, and even more particularly for use in transfer molding or compression molding. This invention relates to a release film and its manufacturing method.

In order to seal semiconductor devices with resin, molding techniques such as transfer molding and compression molding are used. In the above molding method, a release film is often used to easily remove the molded article from the mold after the resin has hardened within the mold. Until now, various proposals have been made regarding release films.

For example, Patent Document 1 below describes a coating film formed from a composition containing a fluororesin (A) containing a functional group X and a mold release component (B), and a layer formed from a non-fluorinated polymer. Disclosed is a release film characterized by comprising:
Furthermore, Patent Document 2 below discloses a release film having at least a release layer (I) having excellent release properties and a plastic support layer (II) that supports the release layer (I), the plastic support layer (II) ) has a strength at 200% elongation at 170°C of 1 MPa to 50 MPa, and the xylene gas permeability of the release film at 170°C of 5 x 10 ^-15 (kmol・m/(s・m ²・kPa )) A release film for a gas barrier semiconductor resin mold is disclosed which is characterized by the following properties.

Japanese Patent Application Publication No. 2015-74201 International Publication No. 2008/020543

As mentioned above, the release film is used to easily remove the molded article from the mold. The release film is required to be easily peeled off from the molded article after the resin is cured.

Furthermore, in manufacturing semiconductor devices, it is necessary to prevent electrostatic damage to the semiconductor devices. Electrostatic damage occurs due to electrostatic discharge (ESD). Destruction of a semiconductor device due to ESD can occur due to instantaneous discharge of a charged conductor (or semiconductor device). A discharge current flows within a semiconductor device due to ESD, and the semiconductor device may be destroyed due to local heat generation and/or electric field concentration. In recent years, with the rapid progress in miniaturization of semiconductor devices, the resistance of semiconductor devices to ESD has also become lower.

In order to prevent the occurrence of ESD, semiconductor device manufacturing lines are provided with electrostatic damage prevention means, such as antistatic devices. However, providing an electrostatic damage prevention means on a semiconductor device manufacturing line may result in an increase in manufacturing costs. We believe that if static electricity dissipation properties can be imparted to the release film used in the semiconductor device manufacturing process, for example, in the semiconductor device sealing process, ESD countermeasures in the sealing process can be implemented at a lower cost. It will be done.

Based on the above, the main object of the present invention is to provide a release film having static electricity dissipation properties.

The present inventors have discovered that a release film having a specific configuration is suitable because it has excellent mold release properties and static electricity dissipation properties.

That is, the present invention has a base layer made of a polyester resin and a surface layer made of a tetrafluoroethylene resin containing a conductive filler, and has a surface resistivity Rs of 1× Provided is a release film having a resistance of 10 ¹¹ Ω or less.
According to one embodiment of the present invention, the conductive filler contains carbon black, and the tetrafluoroethylene resin further has an average particle size of 1 μm to 1 μm when measured according to a laser diffraction particle size analysis method. It may include particles that are 15 μm.
In this embodiment, the carbon black may include Ketjenblack.
The DBP oil absorption amount of the Ketjen black may be 250 ml/100 g or more.
The carbon black may further include furnace black.
In this implementation, the carbon black may include furnace black.
The particles may be inorganic particles.
The inorganic particles may be silicon dioxide particles.
According to another embodiment of the invention, the conductive filler includes carbon black, and the carbon black may include Ketjen black and furnace black.
The polyester resin may be a polyethylene terephthalate resin.
The glass transition temperature of the polyester resin may be 60°C to 95°C.
The surface layer may be laminated on one of the two surfaces of the base layer.
A surface layer made of a fluororesin may be laminated on the other of the two surfaces of the base layer.
The release film of the present invention can be used for sealing semiconductor devices.
In the sealing, the surface layer made of tetrafluoroethylene resin containing the conductive filler may be placed in contact with the sealing resin.
The release film of the present invention can be used for transfer molding or compression molding.
The mold release film of the present invention can be used for molding more than once.

Further, the present invention provides a surface layer formed from a tetrafluoroethylene resin containing a conductive filler on one of two surfaces of a base material layer formed from a polyester resin. Also provided is a method for producing a release film, which includes a surface layer forming step and has a surface resistivity Rs of 1×10 ¹¹ Ω or less.
Moreover, the present invention
a base material layer formed from polyester resin;
and a surface layer formed from a tetrafluoroethylene resin containing a conductive filler and silicon dioxide particles,
The average particle size of the silicon dioxide particles is 1 μm to 15 μm when measured according to a laser diffraction particle size analysis method,
The tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
The content of the silicon dioxide particles is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The content of the conductive filler is 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The conductive filler contains carbon black,
The carbon black includes at least furnace black having a DBP oil absorption of 200 ml/100 g or less,
The surface resistivity Rs is 1×10 ⁹ Ω or less,
We also provide release films.
The polyester resin may be a polyethylene terephthalate resin.
The polyester resin may have a glass transition temperature of 60°C to 95°C.
The surface layer may be laminated on one of the two surfaces of the base layer.
A surface layer made of a fluororesin may be laminated on the other of the two surfaces of the base layer.
The release film may be used for sealing a semiconductor device.
In the sealing, the release film may be arranged such that the surface layer made of a tetrafluoroethylene resin containing the conductive filler is in contact with the sealing resin.
The release film may be used for transfer molding or compression molding.
The release film may be used for molding more than once.
Moreover, the present invention
A surface layer formed from a tetrafluoroethylene resin containing a conductive filler and silicon dioxide particles on one of two surfaces of a base layer formed from a polyester resin. including a forming step;
The average particle size of the silicon dioxide particles is 1 μm to 15 μm when measured according to a laser diffraction particle size analysis method,
The tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
The content of the silicon dioxide particles is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The content of the conductive filler is 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The conductive filler contains carbon black,
The carbon black includes at least furnace black having a DBP oil absorption of 200 ml/100 g or less,
The surface resistivity Rs of the release film to be produced is 1×10 ⁹ Ω or less,
A method of manufacturing a release film is also provided.

ADVANTAGE OF THE INVENTION The present invention provides a mold release film that has excellent mold release properties and static electricity dissipation properties.
Note that the effects of the present invention are not necessarily limited to the effects described herein, and may be any of the effects described herein.

1 is a diagram showing an example of the structure of a release film of the present invention. It is a figure which shows an example of the usage method of the release film of this invention in transfer molding. It is a figure which shows an example of the usage method of the release film of this invention in compression molding.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. Note that the embodiments described below are examples of typical embodiments of the present invention, and the present invention is not limited only to these embodiments.

1. First embodiment (release film)

(1) Description of the first embodiment

The release film of the present invention has a base layer made of a polyester resin and a surface layer made of a tetrafluoroethylene resin containing a conductive filler, and has a surface resistivity Rs. is 1×10 ¹¹ Ω or less. With the surface layer formed from a tetrafluoroethylene resin containing a conductive filler, it is possible to achieve a surface resistivity Rs that is not more than the above upper limit, that is, it is possible to impart static electricity dissipation to the release film. . Further, the release film of the present invention can exhibit excellent mold release properties and has static electricity dissipation properties due to the combination of the surface layer and the base layer.

As mentioned 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, and even more. It is 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, and even more particularly 1×10 ⁴ Ω or more. By having a surface resistivity Rs within the above numerical range, the release film of the present invention can prevent ESD from occurring during the sealing process of a semiconductor device. The surface resistivity Rs is measured according to IEC (International Electrotechnical Commission) standard 61340-5-1. Specifically, the measurement is performed as follows. That is, first, a release film sample having dimensions of 10 cm x 10 cm is obtained. For example, a measurement main electrode (electrode size φ50 mm) and a guard electrode (outer diameter φ80 mm, inner diameter φ70 mm) of a digital ultra-high resistance/microcurrent meter (ADCMT5451, ADC Co., Ltd.) are brought into contact with the molded body side surface layer of the sample. A voltage of 10 V is applied while these electrodes are in contact with each other, and the surface resistivity Rs is measured.

For example, in order to impart static electricity dissipation to a single-layer release film, it is conceivable to add a conductive filler to the resin forming the single-layer release film. However, when a conductive filler is included in a single-layer release film, physical properties of the film, such as film strength (particularly strength and elongation), tend to deteriorate. Moreover, in this case, mold releasability may also be reduced. The deterioration in film physical properties and mold release properties tends to occur, for example, in the case of a single-layer mold release film. For example, strength, elongation, and releasability are important factors for release films used in semiconductor device encapsulation processes, and a decrease in these properties is particularly problematic. Furthermore, the inclusion of a conductive filler in the release film raw material may result in a decrease in film formability or productivity and an increase in cost when forming a single layer release film. Furthermore, it is also difficult to clean the extruder used for film formation.
Furthermore, in order to impart static electricity dissipation to the release film, it is conceivable to add a surfactant to the surface layer, for example. However, surfactants have a low conductivity imparting effect, and tetrafluoroethylene resins are also poorly compatible with surfactants. Furthermore, when the surface layer contains a surfactant, the physical properties of the release film, such as release properties and durability, may deteriorate. Furthermore, in this case, bleed-out of the surfactant may lead to the occurrence of contamination at the contact surface with the release film. Furthermore, the static electricity dissipative properties of surfactants may not be exhibited at low humidity, and it may be necessary to adjust the humidity conditions in order for the surfactants to exhibit static electricity dissipative properties.
As described above, the release film of the present invention has a layer structure including a base layer made of a polyester resin and a surface layer made of a tetrafluoroethylene resin, and the surface layer is formed of a base layer made of a polyester resin and a surface layer made of a tetrafluoroethylene resin. Since the tetrafluoroethylene resin contains a conductive filler, it has static electricity dissipation while maintaining excellent physical properties as a release film.

According to one embodiment of the present invention, the conductive filler contains carbon black, and the tetrafluoroethylene resin has an average particle size of 1 μm to 15 μm when measured according to a laser diffraction particle size analysis method. may include particles that are .
By including the particles, it is possible to improve the electrostatic dissipation properties of carbon black. Therefore, when the particles are included, desired static electricity dissipation properties can be imparted to the release film with a smaller amount of carbon black. This also contributes to preventing deterioration of physical properties due to the addition of carbon black to the release film.
Furthermore, the inclusion of the particles in the surface layer improves the releasability of the release film.
Furthermore, by including the particles in addition to carbon black, the dispersibility of carbon black in the tetrafluoroethylene resin can be improved, and the appearance of the release film can also be improved.

In the embodiment, the carbon black preferably includes Ketjenblack. When Ketjen black is included, the dispersibility improving effect of the particles is particularly likely to be exhibited. Furthermore, Ketjenblack can impart static electricity dissipation properties with a smaller amount than other carbon blacks. Therefore, desired static electricity dissipation properties can be imparted to the release film while suppressing the influence on the physical properties of the release film.

In the embodiment, the carbon black particularly preferably further includes furnace black. By including the combination of Ketjen black and furnace black, in addition to the effect described above regarding the case where Ketjen black is included, the appearance of the release film is improved. More specifically, the black color on the film surface becomes more uniform.

In the embodiment, the carbon black may include furnace black. Even when furnace black is included, the effect of improving the dispersibility in the tetrafluoroethylene resin by the particles can be exhibited. Note that Ketjen black can provide static electricity dissipation with less mass than furnace black.

According to another embodiment of the invention, the conductive filler includes carbon black, and the carbon black may include Ketjen black and furnace black. In this embodiment, the particles having an average particle size of 1 μm to 15 μm as described in relation to the one embodiment above may not be included. By combining Ketjen black and furnace black, the dispersibility of carbon black in the tetrafluoroethylene resin can be improved even if the particles are not included.

According to yet another embodiment of the invention, the conductive filler may include carbon black. In this embodiment, the particles having an average particle size of 1 μm to 15 μm as described in relation to the one embodiment above may not be included. In this embodiment, the carbon black is preferably Ketjenblack.

The release film of the present invention may have a surface layer formed from a tetrafluoroethylene resin containing a conductive filler on one surface or both surfaces. .
Further, the surface layer may be laminated on one of the two surfaces of the base layer (that is, the surface layer may be laminated directly on the one surface of the base layer). ), or another layer may be present between the surface layer and the base layer.

(2) Configuration example of the release film of the present invention

An example of the structure of the release film of the present invention is shown in FIG. As shown in FIG. 1, the release film 100 of the present invention is composed of a base layer 101 and surface layers 102 and 103 laminated on both sides thereof.
The base material layer 101 is made of polyester resin.
The surface layer 102 is made of a tetrafluoroethylene resin containing a conductive filler. When the release film 100 is used for sealing a semiconductor device, the surface layer 102 is placed in contact with the sealing resin. The surface layer 102 imparts static electricity dissipation properties to the release film.
The surface layer 103 may be made of, for example, a fluororesin, preferably a tetrafluoroethylene resin. The fluororesin forming the surface layer 103 may not contain or may contain a conductive filler. When the release film 100 is used for sealing a semiconductor device, the surface layer 103 is placed in contact with a mold. Since the surface layer 103 is made of a fluororesin, particularly a tetrafluoroethylene resin, the release film 100 exhibits excellent mold releasability and prevents mold contamination (especially mold contamination caused by oligomers). ) can be prevented.
As described above, the release film of the present invention includes a base layer made of, for example, a polyester resin, and a polytetrafluoroethylene base layer laminated on one side of the base layer and containing a conductive filler. A first surface layer formed of a resin, and a second surface layer laminated on the other side of the base material layer and formed of a fluororesin (preferably a tetrafluoroethylene resin). can have
Note that another layer may exist between the base material layer and the first surface layer and/or the second surface layer, but for example, in order to reduce manufacturing costs, the release method of the present invention The film may have a three-layer structure including the base layer, the first surface layer, and the second surface layer laminated on the base layer.

(3) How to use the release film of the present invention

The release film of the present invention can be used for sealing semiconductor devices. In the sealing, the surface layer containing the conductive filler is placed in contact with the sealing resin. The release film of the present invention can suppress the occurrence of ESD during the sealing, and can prevent electrostatic damage to semiconductor devices. Therefore, the release film of the present invention can eliminate the need for an antistatic device provided around the mold and device for performing the sealing, contributing to reduction in manufacturing costs.

A molding method for encapsulating a semiconductor device may be appropriately selected by a person skilled in the art. Examples of the molding method include transfer molding and compression molding, 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, in transfer molding or compression molding, by being placed between a mold and a resin. In these moldings (particularly in the process of curing the sealing resin), the surface layer containing the conductive filler is in contact with the resin, and the other surface layer is in contact with the mold. The molding temperature in molding using the release film of the present invention may be, for example, 100°C to 250°C, preferably 120°C to 200°C.

An example of how to use the release film of the present invention in transfer molding will be described with reference to FIG. 2.
As shown in FIG. 2(A), the mold release film 100 of the present invention is placed between an upper mold 201 and a lower mold 203 on which a semiconductor element mounting substrate 202 is placed. Here, the surface layer 102 formed from a polytetrafluoroethylene resin containing a conductive filler is in contact with a resin 204 (described later), and the other surface layer 103 is in contact with an inner surface of an upper mold 201 (described later). , the release film 100 is placed.
Next, as shown in FIG. 2B, the upper mold 201 is brought into contact with the substrate 202 and the lower mold 203 with the release film 100 stuck to the inner surface of the mold 201. In this state, the surface layer 103 is in contact with the inner surface of the upper mold 201.
Next, as shown in FIG. 2C, resin 204 is introduced between upper mold 201 and substrate 202, and then resin 204 is cured. At this stage, the surface layer 102 made of tetrafluoroethylene resin containing a conductive filler is in contact with the resin 204.
After curing, the upper mold 201 is separated from the substrate 202 as shown in FIG. 2(D). Since the mold release film of the present invention has excellent mold release properties, it makes it possible to smoothly release the cured resin 204 from the upper mold 201 in the step shown in FIG. 2(D).
If the release property of the release film is not good, the release film 250 may stick to the cured resin 204, as shown in FIG. 2(E), for example.

An example of how to use the release film of the present invention in compression molding will be described with reference to FIG. 3.
As shown in FIG. 3(A), the release film 100 of the present invention is placed between a lower mold 301 and an upper mold 303 to which a substrate 302 on which a semiconductor element is mounted is attached. Here, the surface layer 102 formed from a polytetrafluoroethylene resin containing a conductive filler is in contact with a resin 304 (described later), and the other surface layer 103 is in contact with an inner surface of a lower mold 301 (described later). , the release film 100 is placed.
Next, as shown in FIG. 3(B), the resin 304 is placed in the recess of the lower mold 301 with the release film 100 stuck to the inner surface of the lower mold 301. At this stage, the surface layer 102 made of tetrafluoroethylene resin containing a conductive filler is in contact with the resin 304, and the surface layer 103 is in contact with the inner surface of the lower mold 301. .
As shown in FIG. 3C, the upper mold 303 is moved to contact the lower mold 301. Thereafter, the resin 304 is cured.
After curing, the upper mold 303 is separated from the lower mold 301 as shown in FIG. 3(D). Since the mold release film of the present invention has excellent mold release properties, it makes it possible to smoothly release the cured resin 304 from the lower mold 301 in the step of FIG. 3(D).

The release film of the present invention may be used for molding various resins, for example, epoxy resin or silicone resin. The type of resin for forming the molded body may be appropriately selected by those skilled in the art.

The release film of the present invention can be used for molding, for example, two or more times, preferably four or more times, more preferably five or more times, more preferably six or more times, even more preferably eight or more times. The release film of the present invention can be used, for example, 2 to 20 times, preferably 4 to 15 times, more preferably 5 to 15 times, more preferably 6 to 15 times, even more preferably 8 to 12 times. It can be used for molding. The mold release film of the present invention maintains its performance through multiple mold releases and is resistant to tearing. Therefore, the release film of the present invention can be used for multiple moldings. Thereby, molding costs can be reduced.

(4) Details of layers constituting the release film of the present invention

(4-1) Base material layer

The base material layer included in the release film of the present invention is formed from a polyester resin. The polyester resin may be a resin containing polyester as a main component. Examples of the polyester include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PCT (polycyclohexylene dimethylene terephthalate), PEB (polyethylene-p- oxybenzoate), and polyethylene bisphenoxy carboxylate, or a mixture of two or more thereof.
Preferably, the polyester resin is a polyethylene terephthalate resin. The polyethylene terephthalate resin may be a resin containing polyethylene terephthalate as a main component.
In this specification, the term "main component" means the component with the highest content among the components constituting the resin. For example, if the main component of the resin is polyester, it means that the content 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 based on the mass of the resin. % or more, 95% or more by mass, or 98% or more by mass, or it may mean that the resin is composed only of polyester. The same applies when the main component of the resin is polyethylene terephthalate.

According to one of the preferred embodiments of the present invention, the base material layer included in the release film may be formed from an easily moldable polyethylene terephthalate resin. Easily moldable polyethylene terephthalate resin (also referred to as easily moldable PET resin) is a term used to refer to PET resin that has better moldability than ordinary polyethylene terephthalate resin. The fact that the base material layer is formed of the easily moldable polyethylene terephthalate resin particularly contributes to the low staining properties of the release film of the present invention.

According to one preferred embodiment of the present invention, the glass transition temperature of the polyester resin forming the base 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 above numerical range. The fact that the resin forming the base layer has a glass transition temperature within this numerical range contributes to making the release film of the present invention usable in multiple molding operations.
Common polyethylene terephthalate generally has a glass transition temperature of 100°C or higher. The glass transition temperature of the easily moldable polyethylene terephthalate resin composition is lower than that of general-purpose polyethylene terephthalate.
The glass transition temperature is measured by differential thermal analysis (DTA).

The easily moldable polyethylene terephthalate resin may be, for example, a copolymerized polyethylene terephthalate resin. Copolymerized polyethylene terephthalate may be obtained, for example, by reacting terephthalic acid, ethylene glycol, and a copolymer component, or by mixing and melting the copolymer component polymer and polyethylene terephthalate, and then performing a partition reaction. It may be obtained by
The copolymerization component may be, for example, an acid component or an alcohol component. The acid components include aromatic dibasic acids (such as isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid), aliphatic dicarboxylic acids (such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid), and alicyclic acids. Mention may be made, for example, of the group dicarboxylic acids such as cyclohexanedicarboxylic acid. Examples of the alcohol component include aliphatic diols (eg, butanediol, hexanediol, neopentyl glycol, etc.) and alicyclic diols (eg, cyclohexanedimethanol, etc.). As the copolymerization component, one or a combination of two or more of these compounds may be used. The acid component can in particular be isophthalic acid and/or sebacic acid.

As the base material layer formed from the easily moldable polyethylene terephthalate resin, a commercially available material may be used. For example, Teflex (trademark) FT, Teflex (trademark) FT3, and Teflex (trademark) FW2 (all manufactured by Teijin Film Solutions Ltd.) can be used as the base material layer. Furthermore, Emblet CTK-38 (manufactured by Unitika Co., Ltd.) may be used as the base material layer.
The base material layer formed from the easily moldable polyethylene terephthalate resin may be manufactured by the method described in, for example, JP-A-2-305827, JP-A-3-86729, or JP-A-3-110124. good. According to one preferred embodiment of the present invention, the base layer has a planar orientation coefficient of preferably 0.06 to 0.16, more preferably 0.07 to 0.16, as described in any of these publications. It may be one obtained by biaxially stretching an easily moldable polyethylene terephthalate resin so that the film diameter is 0.15.

The tensile breaking strength of the base layer is preferably 40 MPa to 200 MPa, more preferably 40 MPa to 120 MPa, even more preferably 40 MPa to 110 MPa, particularly when measured at 175° C. according to JIS K7127. Preferably, it may be 45 MPa to 100 MPa.
The tensile elongation at break of the base material layer is preferably 200% to 500%, more preferably 250% to 450%, even more preferably 300% to 300%, when measured at 175°C according to JIS K7127. It can be 400%.
The fact that the base material layer has a tensile strength at break and/or a tensile elongation at break within the above numerical range contributes to making the release film of the present invention usable in multiple molding operations. The tensile strength at break and elongation at break within the above numerical ranges can be obtained, for example, by forming the base material layer from an easily moldable polyethylene terephthalate resin. Easily moldable polyethylene terephthalate resin has better extensibility than general-purpose PET resin.

Since the polyester resin of the base 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. The effects achieved by the release film of the present invention will be explained in more detail below.

Polyethylene terephthalate resin contains oligomers with a low degree of polymerization that are produced during its production. When molding is performed using a release film including a layer formed from a polyethylene terephthalate resin, the oligomer may migrate to the surface of the release film and contaminate the molded product and/or the mold surface. This contamination may occur even if, for example, a fluororesin layer is laminated on the surface of the polyethylene terephthalate resin layer. This is considered to be because the oligomer passes through the fluororesin layer. Further, the contamination is particularly likely to occur when one mold release film is used for multiple moldings. This is probably because heat is applied to the polyethylene terephthalate resin during molding, causing the oligomer to migrate from the inside of the resin to the surface.
Easily moldable polyethylene terephthalate resin also contains the oligomer. However, the release film of the present invention has a structure in which a base layer made of an easily moldable polyethylene terephthalate resin and a surface layer made of a tetrafluoroethylene resin containing a conductive filler are laminated. In this case, not only can electrostatic dissipation properties be imparted to the release film, but also contamination by the oligomer can be reduced or eliminated. Moreover, the static electricity dissipation and low staining properties of the release film of the present invention are maintained through multiple moldings.

Further, generally, the release film is replaced with a new one every time molding is performed. This is because if a mold release film that has been used once for molding is used again for molding, the possibility that the mold release film will be torn increases. Breaking of the release film is fatal to molding, and may result in, for example, an abnormal shape of the molded article or the mold may adhere to the molded article.
When the release film of the present invention has a structure in which a base layer formed from an easily moldable polyethylene terephthalate resin and a surface layer formed from a tetrafluoroethylene resin containing a conductive filler are laminated, Even when the release film is used for multiple molding operations, it is resistant to tearing and maintains its release properties, static electricity dissipation properties, and low contamination properties. Therefore, the release film according to the invention can be used for multiple moldings, thereby reducing molding costs.

The thickness of the base layer may be, for example, 10 μm to 80 μm, preferably 15 μm to 75 μm, more preferably 20 μm to 70 μm. This thickness contributes to enabling the release film of the present invention to be used in multiple moldings.

(4-2) Surface layer formed from tetrafluoroethylene resin containing conductive filler

(4-2-1) Tetrafluoroethylene resin

The release film of the present invention includes a surface layer formed from a tetrafluoroethylene resin containing a conductive filler. The tetrafluoroethylene resin preferably does not contain chlorine. By not containing chlorine, the durability and/or antifouling properties of the layer are improved. The tetrafluoroethylene resin may be, for example, a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent.

The reactive functional group-containing tetrafluoroethylene polymer 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 may be appropriately selected by those skilled in the art.
The reactive functional group may be, for example, a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, or a silyl group, and is preferably a hydroxyl group. These groups allow the reaction for obtaining the cured product to proceed favorably.
Among these reactive functional groups, hydroxyl groups are particularly suitable for the reaction to obtain the cured product. That is, the reactive functional group-containing tetrafluoroethylene polymer may preferably be a hydroxyl group-containing tetrafluoroethylene polymer.

The fluorine-containing units of the reactive functional group-containing tetrafluoroethylene polymer are preferably fluorine-containing units based on perfluoroolefins. The fluorine-containing units based on the perfluoroolefins are more preferably tetrafluoroethylene (tetrafluoroethylene, hereinafter also referred to as "TFE"), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether). (PAVE) may be based on one, two, or three selected from (PAVE). Preferably, among the fluorine-containing units based on the perfluoroolefins, the fluorine-containing units based on TFE are the largest.

The hydroxyl value of the reactive functional group-containing tetrafluoroethylene polymer (especially the hydroxyl value of the hydroxyl group-containing tetrafluoroethylene polymer) is preferably 10 mgKOH/g to 300 mgKOH/g, more preferably 10 mgKOH /g to 200 mgKOH/g, and even more preferably 10 mgKOH/g to 150 mgKOH/g. When the hydroxyl value of the reactive functional group-containing tetrafluoroethylene polymer is at least the lower limit of the above numerical range, the curability of the resin composition can be improved. Further, the hydroxyl value of the reactive functional group-containing tetrafluoroethylene polymer is less than or equal to the upper limit of the numerical range, making the cured product of the resin composition suitable for multiple moldings. It can contribute to The hydroxyl value is obtained by measuring by a method based on JIS K 0070.

The acid value of the reactive functional group-containing tetrafluoroethylene polymer (especially the acid value of the hydroxyl group-containing tetrafluoroethylene polymer) is preferably 0.5 mgKOH/g to 100 mgKOH/g, and more preferably can be from 0.5 mgKOH/g to 50 mgKOH/g. When the acid value of the reactive functional group-containing tetrafluoroethylene polymer is at least the lower limit of the above numerical range, the curability of the resin composition can be improved. Further, the acid value of the reactive functional group-containing tetrafluoroethylene polymer is below the upper limit of the above numerical range, making the cured product of the resin composition suitable for multiple moldings. It can contribute to

The reactive functional group of the reactive functional group-containing tetrafluoroethylene polymer can be obtained by copolymerizing a monomer having the reactive functional group with a fluorine-containing monomer (particularly the above-mentioned perfluoroolefin). It may be incorporated into fluorinated ethylene polymers. That is, the reactive functional group-containing tetrafluoroethylene-based polymer may include a polymer unit based on a reactive functional group-containing monomer and a polymer unit based on a fluorine-containing monomer (particularly the above-mentioned perfluoroolefin).

When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group may preferably be a hydroxyl group-containing vinyl ether or a hydroxyl group-containing allyl ether. Examples of the hydroxyl group-containing vinyl ether include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, Examples of the hydroxyl group-containing allyl ether include 5-hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether, and examples of the hydroxyl group-containing allyl ether include 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Alternatively, the monomer having reactive functional groups may 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 may be used. When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group is more preferably a hydroxyl group-containing vinyl ether, particularly preferably 4-hydroxybutyl vinyl ether and /or 2-hydroxyethyl vinyl ether.

When the reactive functional group is a carboxyl group, the monomer having the reactive functional group may preferably be an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid.
When the reactive functional group is an amino group, the monomer having the reactive functional group may be, for example, amino vinyl ether or allylamine.
When the reactive functional group is a silyl group, the monomer having the reactive functional group may preferably be a silicone vinyl monomer.

The fluorine-containing monomer is preferably a perfluoroolefin. As perfluoroolefins, mention may be made, for example, of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE). Preferably, the fluorine-containing monomer comprises TFE.

Preferably, the reactive functional group-containing tetrafluoroethylene polymer includes, in addition to polymerized units based on reactive functional group-containing monomers and polymerized units based on fluorine-containing monomers, polymerized units based on non-fluorine-containing vinyl monomers. It can be included. The fluorine-free vinyl monomer can be, for example, one or a combination of two or more selected from the group consisting of carboxylic acid vinyl esters, alkyl vinyl ethers, and non-fluorinated olefins.
Examples of carboxylic acid vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, vinyl benzoate, and vinyl para-t-butylbenzoate.
As alkyl vinyl ethers, mention may be made, for example, of methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether.
Examples of non-fluorinated olefins include ethylene, propylene, n-butene, and isobutene.
In addition to the reactive functional group-containing tetrafluoroethylene-based polymer, for example, vinylidene fluoride (VdF ), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinyl ether.

The reactive functional group-containing tetrafluoroethylene polymer is, for example, a TFE/non-fluorinated olefin/hydroxybutyl vinyl ether copolymer, a TFE/carboxylic acid vinyl ester/hydroxybutyl vinyl ether copolymer, or a TFE/non-fluorinated olefin/hydroxybutyl vinyl ether copolymer. It may be an alkyl vinyl ether/hydroxybutyl vinyl ether copolymer.
More specifically, the reactive functional group-containing tetrafluoroethylene polymer is a TFE/isobutylene/hydroxybutyl vinyl ether copolymer, a TFE/vinyl versatate/hydroxybutyl vinyl ether copolymer, or a TFE/isobutylene/hydroxybutyl vinyl ether copolymer. It may be a VdF/hydroxybutyl vinyl ether copolymer. The reactive functional group-containing tetrafluoroethylene polymer may particularly preferably be a TFE/isobutylene/hydroxybutyl vinyl ether copolymer or a TFE/vinyl versatate/hydroxybutyl vinyl ether copolymer.
As the reactive functional group-containing tetrafluoroethylene polymer, for example, products of the Zeffle GK series can be used.

The curing agent contained in the tetrafluoroethylene resin composition may be appropriately selected by a person skilled in the art depending on the type of reactive functional group contained in the reactive functional group-containing tetrafluoroethylene polymer. .
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.
When the reactive functional group is a carboxyl group, the curing agent may be one or a combination of two or more selected from amino curing agents and epoxy curing agents.
When the reactive functional group is an amino group, the curing agent may be one or a combination of two or more selected from a carbonyl group-containing curing agent, an epoxy curing agent, and an acid anhydride curing agent.
The content of the curing agent in the tetrafluoroethylene resin composition is, for example, 15 parts by mass to 50 parts by mass, preferably 15 parts by mass to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. It may be from 20 parts by weight to 40 parts by weight, more preferably from 23 parts by weight to 35 parts by weight. These numerical ranges also apply to the content of the curing agent in the cured product of the tetrafluoroethylene resin composition.
The content of the curing agent may be measured by a pyrolysis gas chromatography (Py-GC/MS) method.

In one embodiment of the present invention, the reactive functional group contained in the reactive functional group-containing tetrafluoroethylene polymer may be a hydroxyl group, and the curing agent may be an isocyanate curing agent. In this embodiment, the isocyanate-based curing agent is preferably a hexamethylene diisocyanate (HDI)-based polyisocyanate.
The content of the HDI polyisocyanate in the tetrafluoroethylene resin composition is, for example, 15 parts by mass to 50 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. The amount may preferably be 20 parts by weight to 40 parts by weight, more preferably 23 parts by weight to 35 parts by weight. These numerical ranges also apply to the content of the HDI polyisocyanate in the cured product of the tetrafluoroethylene resin composition.

As the HDI-based polyisocyanate, one or a combination of two or more selected from, for example, isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates can be used. In the present invention, the isocyanate-based curing agent 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.
When a combination of isocyanurate type polyisocyanate and adduct type polyisocyanate is used as the curing agent, the mass ratio of the two is, for example, 10:6 to 10:10, preferably 10:7 to 10:9. The total amount of both is, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, more preferably 25 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. parts to 35 parts by weight.
The content ratio of these curing agents may be determined by pyrolysis gas chromatography (Py-GC/MS) method.

(4-2-2) Conductive filler

The tetrafluoroethylene resin forming the surface layer contains a conductive filler. The conductive filler may be one or a combination of two or more selected from, for example, a metal-based conductive filler, a carbon-based conductive filler, a metal oxide-based conductive filler, and a metal-plated conductive filler. .
Examples of the metallic conductive filler include powdered conductive fillers such as silver, copper, nickel, tin, and silver-plated copper powder, and fibers such as copper, stainless steel, aluminum, brass, and iron fibers. Examples include conductive fillers. Examples of the carbon-based conductive filler include powdered conductive fillers such as carbon black and graphite, and fibrous conductive fillers such as carbon nanotubes (CNTs) and carbon fibers. Examples of the metal oxide conductive filler include powdered conductive fillers such as tin oxide, indium oxide, and zinc oxide powder. Examples of the metal-plated conductive filler include a powder conductive filler metal-plated with glass beads or mica powder, and a fibrous conductive filler metal-plated with glass fiber or carbon fiber. I can do it.
The conductive filler is preferably the carbon-based conductive filler, and may be, for example, the carbon-based powder conductive filler or the carbon-based fibrous conductive filler as described above.
The content of the conductive filler in the tetrafluoroethylene resin composition is, for example, 1 part by mass to 25 parts by mass, preferably 1 part by mass to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. may range from 1 part by weight to 23 parts by weight. These numerical ranges also apply to the content of the conductive filler in the cured product of the tetrafluoroethylene resin composition.

The conductive filler preferably contains carbon black. The conductive filler may be only carbon black. As the 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 may be used. The conductive filler preferably includes one or both of Ketjen black and furnace black. Ketjen black and furnace black are particularly suitable for imparting static electricity dissipation properties to the release film of the present invention.
Since Ketjen black has a small primary particle size and a hollow structure, it has a large filling amount per unit weight. Therefore, a small amount of Ketjenblack imparts static electricity dissipation properties to the release film.

According to one of the preferred embodiments of the present invention, the carbon black contained in the tetrafluoroethylene resin forming the surface layer includes Ketjen black. The carbon black may be, for example, only Ketjenblack.
In the case where the conductive filler contains Ketjen black, the content of the Ketjen black in the tetrafluoroethylene resin composition is based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. On the other hand, it may be, for example, 1 part to 25 parts by weight, preferably 1 part to 10 parts by weight, more preferably 3 parts to 8 parts by weight. These numerical ranges also apply to the content of Ketjen black in the cured product of the tetrafluoroethylene resin composition.

In the case where the tetrafluoroethylene resin forming the surface layer contains Ketjen black but does not contain the particles described below as "(4-2-3) particles", the content of Ketjen black is preferably is 3 parts by mass or more based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. Thereby, the surface resistivity Rs can be set to, for example, 1×10 ⁸ Ω or less, particularly 5×10 ⁷ Ω or less. In this case, the content of the Ketjen black is, for example, 3 parts by mass to 15 parts by mass, more preferably 5 parts by mass to 10 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. Part by mass.

In the case where the tetrafluoroethylene resin forming the surface layer contains Ketjen black and also contains particles (particularly silicon dioxide particles) described below as "(4-2-3) particles", the Ketjen black The content of black may be 1 part by mass or more based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. The combination of the particles and the Ketjen black allows the surface resistivity Rs to be, for example, 1×10 ⁸ Ω or less, particularly 5×10 ⁷ Ω or less, with a smaller Ketjen black content. Moreover, the combination of the particles and the Ketjen black can improve the dispersibility of the Ketjen black in the tetrafluoroethylene resin composition. This results in a better appearance of the release film surface.

According to one particularly preferred embodiment 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 be, for example, only a combination of Ketjen black and furnace black.
When the conductive filler contains Ketjen black and furnace black, the content of the Ketjen black in the tetrafluoroethylene resin composition is 100% of the reactive functional group-containing tetrafluoroethylene polymer. Based on parts by weight, it may be preferably 1 part to 10 parts by weight, more preferably 2 parts to 9 parts by weight, and even more preferably 3 parts to 8 parts by weight. These numerical ranges also apply to the content of Ketjen black in the cured product of the tetrafluoroethylene resin composition. In the above case, the content of the furnace black in the tetrafluoroethylene resin composition is, for example, 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. parts, preferably 3 parts to 20 parts by weight, more preferably 5 parts to 18 parts by weight. These numerical ranges also apply to the content of the furnace black in the cured product of the tetrafluoroethylene resin composition.

In the case where the tetrafluoroethylene resin forming the surface layer contains Ketjen black and furnace black but does not contain the particles described below as "(4-2-3) particles", the content of Ketjen black is preferably 1 part by mass to 10 parts by mass, more preferably 2 parts to 9 parts by mass, even more preferably 3 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. It may be from 8 parts by weight to 8 parts by weight. These numerical ranges also apply to the content of Ketjen black in the cured product of the tetrafluoroethylene resin composition. In the above case, the content of the furnace black in the tetrafluoroethylene resin composition is, for example, 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. parts, preferably 3 parts to 20 parts by weight, more preferably 5 parts to 18 parts by weight. By adopting a content within these numerical ranges, the surface resistivity Rs can be set to, for example, 1×10 ⁸ Ω or less, particularly 5×10 ⁷ Ω or less.

In the case where the tetrafluoroethylene resin forming the surface layer contains Ketjen black and furnace black, and also contains particles (particularly silicon dioxide particles) described below as "(4-2-3) particles", The content of the Ketjenblack in the tetrafluoroethylene resin composition is preferably 1 part by mass to 8 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. More preferably, it may be from 2 parts by weight to 7 parts by weight, and even more preferably from 3 parts by weight to 6 parts by weight. These numerical ranges also apply to the content of Ketjen black in the cured product of the tetrafluoroethylene resin composition. In the above case, the content of the furnace black in the tetrafluoroethylene resin composition is, for example, 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. parts, preferably 3 parts to 20 parts by weight, more preferably 5 parts to 18 parts by weight. By adopting a content within these numerical ranges, the surface resistivity Rs can be set to, for example, 1×10 ⁸ Ω or less, particularly 5×10 ⁷ Ω or less.

The DBP oil absorption amount of the Ketjen black is preferably 250 ml/100 g or more, more preferably 280 ml/100 g or more, and even more preferably 300 ml/100 g or more. The DBP oil absorption amount of Ketjenblack may be, for example, 1000 ml/100 g or less, particularly 800 ml/100 g or less, and more particularly 600 ml/100 g or less.
In this specification, DBP oil absorption is a value measured by a method based on JIS K6217-4.

The iodine adsorption amount of the Ketjen black is preferably 500 mg/g or more, more preferably 600 mg/g or more, and even 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 even more preferably 1200 mg/g or less.
In this specification, the amount of iodine adsorption is a value measured by a method based on JIS K6217-1.

The Ketjen black is preferably in powder form. The powder form improves the appearance of the surface layer. The average particle size of the powdered Ketjen black is preferably 1 μm to 20 μm, more preferably 3 μm to 17 μm, even more preferably 5 μm to 15 μm, as measured according to a laser diffraction particle size analysis method. Particularly preferably, the thickness may be 7 μm to 13 μm. The average particle diameter is a volume-weighted volume average diameter, and is measured according to JIS Z8825. The average particle size can be measured using, for example, a particle size analyzer (SALD-2200, Shimadzu Corporation). It is thought that including such fine particles at a content within the above numerical range contributes to improved dispersibility and/or improved appearance.

The porosity of the Ketjen black is preferably 50% by volume or more, more preferably 52% by volume or more, and even more preferably 55% by volume or more. The porosity of the Ketjenblack is, for example, 90% by volume or less, particularly 85% by volume or less, and more particularly 80% by volume or less. In this specification, the porosity is the ratio of pore volume to the total of carbon volume and pore volume, and is expressed by the following formula.
Porosity (volume%) = A÷(A+B)×100
(A: Pore volume per unit mass (cm ³ /g), B: Carbon volume per unit mass (cm ³ /g))
A is the amount of gas adsorption (physical adsorption) measured by a pore distribution measuring device. B is the reciprocal of true density (g/cm ³ ), and the true density is measured by the pycnometer method.

According to one of the preferred embodiments, the carbon black contained in the tetrafluoroethylene resin forming the surface layer includes furnace black in addition to Ketjen black. The carbon black may be, for example, only Ketjen black and furnace black. When the carbon black includes 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.

The DBP oil absorption amount of the furnace black is preferably 200 ml/100 g or less, more preferably 150 ml/100 g or less, and even more preferably 100 ml/100 g or less. The DBP oil absorption amount of the furnace black may be, for example, 40 ml/100 g or more, particularly 50 ml/100 g or more, and even more particularly 60 ml/100 g or more. The DBP oil absorption amount is a value measured by a method based on JIS K6217-4.

The nitrogen adsorption specific surface area of the furnace black is preferably 10 m ² /g to 70 m 2 /g, more preferably 15 m ^{2 /} g to 50 m ² /g, when measured according to JIS K6217-2. Even more preferably it is 20 m ² /g to 40 m ² /g.

Preferably, the furnace black is in powder form. The powder form improves the appearance of the surface layer. The average particle size of the powdered furnace black is preferably 30 nm to 150 nm, more preferably 50 nm to 100 nm, even more preferably 60 nm to 90 nm, particularly preferably 70 nm to 80 nm, as measured by electron microscopy. It can be. The average particle diameter is a volume-weighted volume average diameter, and is measured according to JIS Z8825. The average particle size can be measured using, for example, a particle size analyzer (SALD-2200, Shimadzu Corporation). It is thought that including such fine particles at a content within the above numerical range contributes to improved dispersibility and/or improved appearance.

The pH of the mixture obtained by mixing the furnace black with distilled water when measured with a glass electrode pH meter is preferably 5.5 to 8.5, more preferably 6 to 8, and even more. Preferably, it may be 6.5 to 7.5.

(4-2-3) Particles

The tetrafluoroethylene resin forming the surface layer preferably has an average particle diameter of 1 μm to 15 μm, more preferably 1 μm to 12 μm, even more preferably 2 μm to 2 μm, as measured according to a laser diffraction particle size analysis method. Contains particles that are 10 μm. The particles are particles other than conductive filler, for example, particles other than carbon black. The average particle diameter is a volume-weighted volume average diameter, and is measured according to JIS Z8825. The average particle size can be measured using, for example, a particle size analyzer (SALD-2200, Shimadzu Corporation). By including the particles, desired static electricity dissipation properties can be imparted to the release film using a smaller amount of carbon black. By including the particles, the dispersibility of the conductive filler in the tetrafluoroethylene resin can be improved. The improvement in dispersibility results in an improvement in the appearance of the surface of the release film. Furthermore, by including the particles, the release properties of the release film can be improved.

The particles are preferably inorganic or organic particles. Examples of inorganic particles include silicon dioxide (especially amorphous silicon dioxide), calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Examples of organic particles include crosslinked polymer particles and calcium oxalate. In the present invention, the particles are preferably inorganic particles, more preferably silicon dioxide particles, even more preferably amorphous silicon dioxide. Amorphous silicon dioxide can be sol-gel type silica. As the amorphous silicon dioxide, for example, amorphous silicon dioxide of the Thylysia series can be used.

The content of the particles in the tetrafluoroethylene resin composition is, for example, 3 parts by mass to 30 parts by mass, preferably 4 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. It can be from 5 parts to 20 parts by weight, more preferably from 5 parts to 20 parts by weight. These numerical ranges also apply to the content of the particles in the cured product of the tetrafluoroethylene resin composition.
The content of the particles may be determined by thermogravimetric analysis (TGA).

(4-2-4) Other ingredients

The tetrafluoroethylene resin composition may include a solvent. The type of solvent may be appropriately selected by those skilled in the art. As solvents, mention may be made, for example, of butyl acetate, ethyl acetate, and methyl ethyl ketone (also referred to as MEK). For example, a mixture of these three types can be used as the solvent.

The tetrafluoroethylene resin composition may include a release promoter. Examples of the release accelerator include amino-modified methylpolysiloxane, epoxy-modified methylpolysiloxane, carboxy-modified methylpolysiloxane, and carbinol-modified methylpolysiloxane. Preferably, the mold release promoter is an amino-modified methylpolysiloxane.
The release accelerator is, for example, 0.01 parts by mass to 3 parts by mass, preferably 0.05 parts by mass to 2 parts by mass, based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. Preferably, the amount may be 0.1 part by mass to 1 part by mass. These numerical ranges also apply to the content of the release accelerator in the cured product of the tetrafluoroethylene resin composition.

(4-2-5) Formation of surface layer

The thickness of the surface layer may be, for example, 1 μm to 10 μm, preferably 2 μm to 9 μm, and more preferably 3 μm to 8 μm.

The tetrafluoroethylene resin composition can be produced by mixing and stirring the components described above by means known to those skilled in the art. Mixers such as high-speed mixers, homo mixers, and paint shakers can be used for the mixing and stirring. For the mixing and stirring, a dissolver such as an edge turbine type high speed dissolver may be used.
The cured product of the tetrafluoroethylene resin composition is obtained by coating the tetrafluoroethylene resin composition on the surface of the base layer at a temperature of, for example, 100°C to 200°C, preferably 120°C to 180°C. For example, it can be obtained by heating for 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds. The cured product forms the surface layer. The amount of the tetrafluoroethylene resin composition applied may be appropriately determined by those skilled in the art depending on the thickness of the surface layer to be formed.

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

In one preferred embodiment of the present technology, the surface layer on the molded body side includes the reactive functional group-containing tetrafluoroethylene polymer (particularly the hydroxyl group-containing tetrafluoroethylene polymer), the curing agent, and the particles. It is formed from a cured product of a fluororesin composition containing the above-mentioned mold release accelerator and the above-mentioned conductive filler.
More preferably, the surface layer on the molded body side is formed by curing a tetrafluoroethylene resin composition containing a hydroxyl group-containing tetrafluoroethylene polymer, an HDI polyisocyanate, silicon dioxide particles, an amino-modified methylpolysiloxane, and carbon black. formed from things.
Having this surface layer on the molded body side particularly contributes to providing the mold release film of the present invention with excellent static electricity dissipation properties and mold release properties.

(4-3) Mold side surface layer

(4-3-1) Fluorine resin

The mold-side surface layer of the release film of the present invention may be made of, for example, a fluororesin. According to a preferred embodiment of the invention, the fluororesin does not contain chlorine. By not containing chlorine, the durability and/or antifouling properties of the layer are improved. The fluororesin may be, for example, a cured product of a fluororesin composition containing a fluoropolymer containing a reactive functional group and a curing agent.
The fluororesin preferably contains a tetrafluoroethylene resin, and more preferably contains a tetrafluoroethylene resin as a main component. In this specification, the tetrafluoroethylene resin refers to a component obtained by a curing reaction between a reactive functional group-containing tetrafluoroethylene polymer and a curing agent, which will be described below. "Tetrafluoroethylene resin is the main component" means that the fluorocarbon resin consists only of tetrafluoroethylene resin, or the amount of tetrafluoroethylene resin among the components contained in the fluorocarbon resin. means the most. For example, the content of the tetrafluoroethylene resin in the fluororesin is, for example, 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, based on the total mass of the fluororesin. Particularly preferably, it may be 85% by mass or more. The content may be, for example, 99% by mass or less, particularly 98% by mass or less, and more particularly 97% by mass or less, based on the total mass of the fluororesin.
When the fluororesin is a tetrafluoroethylene resin, the mold side surface layer is, for example, in the above "(4-2) Surface layer formed from a tetrafluoroethylene resin containing a conductive filler". The surface layer may be the same as the above-mentioned surface layer formed from a tetrafluoroethylene resin containing a conductive filler.

The reactive functional group-containing fluoropolymer contained in the fluororesin composition may be a fluoropolymer that can be cured by the curing agent. The reactive functional group and the curing agent may be appropriately selected by those skilled in the art.
The reactive functional group may be, for example, a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, or a silyl group, and is preferably a hydroxyl group. These groups allow the reaction for obtaining the cured product to proceed favorably.
Among these reactive functional groups, hydroxyl groups are particularly suitable for the reaction to obtain the cured product. That is, the reactive functional group-containing fluoropolymer is preferably a hydroxyl group-containing fluoropolymer, more preferably a hydroxyl group-containing tetrafluoroethylene polymer.

The fluorine-containing units of the reactive functional group-containing fluoropolymer are preferably fluorine-containing units based on perfluoroolefins. The fluorine-containing units based on the perfluoroolefins are more preferably tetrafluoroethylene (tetrafluoroethylene, hereinafter also referred to as "TFE"), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether). (PAVE) may be based on one, two, or three selected from (PAVE). Preferably, among the fluorine-containing units based on the perfluoroolefins, the fluorine-containing units based on TFE are the largest.

The hydroxyl value of the reactive functional group-containing fluoropolymer (especially the hydroxyl value of the hydroxyl group-containing fluoropolymer) is preferably 10 mgKOH/g to 300 mgKOH/g, more preferably 10 mgKOH/g to 200 mgKOH/g. and even more preferably 10 mgKOH/g to 150 mgKOH/g. When the hydroxyl value of the reactive functional group-containing fluoropolymer is at least the lower limit of the above numerical range, the curability of the resin composition can be improved. Furthermore, the fact that the hydroxyl value of the reactive functional group-containing fluoropolymer is less than or equal to the upper limit of the numerical range mentioned above contributes to making the cured product of the resin composition suitable for multiple moldings. sell. The hydroxyl value is obtained by measuring by a method based on JIS K 0070.

The acid value of the reactive functional group-containing fluoropolymer (especially the acid value of the hydroxyl group-containing fluoropolymer) is preferably 0.5 mgKOH/g to 100 mgKOH/g, more preferably 0.5 mgKOH/g. It can be ~50 mg KOH/g. When the acid value of the reactive functional group-containing fluoropolymer is at least the lower limit of the above numerical range, the curability of the resin composition can be improved. Furthermore, the fact that the acid value of the reactive functional group-containing fluoropolymer is less than or equal to the upper limit of the above numerical range contributes to making the cured product of the resin composition suitable for multiple moldings. sell.

The reactive functional group of the reactive functional group-containing fluoropolymer can be obtained by copolymerizing the monomer having the reactive functional group with a fluorine-containing monomer (particularly the above-mentioned perfluoroolefin). may be introduced. That is, the reactive functional group-containing fluoropolymer may include a polymerized unit based on a reactive functional group-containing monomer and a polymerized unit based on a fluorine-containing monomer (particularly the above-mentioned perfluoroolefin).

When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group may preferably be a hydroxyl group-containing vinyl ether or a hydroxyl group-containing allyl ether. Examples of the hydroxyl group-containing vinyl ether include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, Examples of the hydroxyl group-containing allyl ether include 5-hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether, and examples of the hydroxyl group-containing allyl ether include 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Alternatively, the monomer having reactive functional groups may 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 may be used. When the reactive functional group is a hydroxyl group, the monomer having the reactive functional group is more preferably a hydroxyl group-containing vinyl ether, particularly preferably 4-hydroxybutyl vinyl ether and /or 2-hydroxyethyl vinyl ether.

When the reactive functional group is a carboxyl group, the monomer having the reactive functional group may preferably be an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or an acid anhydride of an unsaturated carboxylic acid.
When the reactive functional group is an amino group, the monomer having the reactive functional group may be, for example, amino vinyl ether or allylamine.
When the reactive functional group is a silyl group, the monomer having the reactive functional group may preferably be a silicone vinyl monomer.

The fluorine-containing monomer is preferably a perfluoroolefin. As perfluoroolefins, mention may be made, for example, of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE). Preferably, the fluorine-containing monomer comprises TFE.

Preferably, the reactive functional group-containing fluoropolymer may include polymerized units based on a fluorine-free vinyl monomer in addition to the polymerized units based on the reactive functional group-containing monomer and the polymerized units based on the fluorine-containing monomer. The fluorine-free vinyl monomer can be, for example, one or a combination of two or more selected from the group consisting of carboxylic acid vinyl esters, alkyl vinyl ethers, and non-fluorinated olefins.
Examples of carboxylic acid vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, vinyl benzoate, and vinyl para-t-butylbenzoate.
As alkyl vinyl ethers, mention may be made, for example, of methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether.
Examples of non-fluorinated olefins include ethylene, propylene, n-butene, and isobutene.
In addition, the reactive functional group-containing fluoropolymer includes, in addition to a polymer unit based on a reactive functional group-containing monomer and a polymer unit based on a fluorine-containing monomer that is a perfluoroolefin, for example, vinylidene fluoride (VdF), chloro It may also contain polymerized units based on fluoromonomers other than perfluoroolefins, such as trifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinylether.

The reactive functional group-containing fluoropolymer is, for example, TFE/non-fluorinated olefin/hydroxybutyl vinyl ether copolymer, TFE/carboxylic acid vinyl ester/hydroxybutyl vinyl ether copolymer, or TFE/alkyl vinyl ether/ It may be a hydroxybutyl vinyl ether copolymer.
More specifically, the reactive functional group-containing fluoropolymer is a TFE/isobutylene/hydroxybutyl vinyl ether copolymer, a TFE/vinyl versatate/hydroxybutyl vinyl ether copolymer, or a TFE/VdF/hydroxybutyl vinyl ether copolymer. It may be a butyl vinyl ether copolymer. The reactive functional group-containing fluoropolymer may particularly preferably be a TFE/isobutylene/hydroxybutyl vinyl ether copolymer or a TFE/vinyl versatate/hydroxybutyl vinyl ether copolymer.
As the reactive functional group-containing fluoropolymer, for example, products of the Zeffle GK series can be used.

The curing agent contained in the fluororesin composition may be appropriately selected by those skilled in the art depending on the type of reactive functional group contained in the reactive functional group-containing fluoropolymer.
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.
When the reactive functional group is a carboxyl group, the curing agent may be one or a combination of two or more selected from amino curing agents and epoxy curing agents.
When the reactive functional group is an amino group, the curing agent may be one or a combination of two or more selected from a carbonyl group-containing curing agent, an epoxy curing agent, and an acid anhydride curing agent.
The content of the curing agent in the fluororesin composition is, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, based on 100 parts by mass of the reactive functional group-containing fluoropolymer. parts, more preferably 23 parts to 35 parts by weight. These numerical ranges also apply to the content of the curing agent in the cured product of the fluororesin composition.
The content of the curing agent may be measured by a pyrolysis gas chromatography (Py-GC/MS) method.

In one embodiment of the present invention, the reactive functional group contained in the reactive functional group-containing fluoropolymer may be a hydroxyl group, and the curing agent may be an isocyanate-based curing agent. In this embodiment, the isocyanate-based curing agent is preferably a hexamethylene diisocyanate (HDI)-based polyisocyanate.
The content of the HDI polyisocyanate in the fluororesin composition is, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 100 parts by mass of the reactive functional group-containing fluoropolymer. It may be 40 parts by weight, more preferably 23 parts to 35 parts by weight. These numerical ranges also apply to the content of the HDI polyisocyanate in the cured product of the fluororesin composition.

As the HDI-based polyisocyanate, one or a combination of two or more selected from, for example, isocyanurate-type polyisocyanates, adduct-type polyisocyanates, and biuret-type polyisocyanates can be used. In the present invention, the isocyanate-based curing agent 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.
When a combination of isocyanurate type polyisocyanate and adduct type polyisocyanate is used as the curing agent, the mass ratio of the two is, for example, 10:6 to 10:10, preferably 10:7 to 10:9. The total amount of both is, for example, 15 parts by mass to 50 parts by mass, preferably 20 parts by mass to 40 parts by mass, more preferably 25 parts by mass to 35 parts by mass, based on 100 parts by mass of the reactive functional group-containing fluoropolymer. It can be parts by mass.
The content ratio of these curing agents may be determined by pyrolysis gas chromatography (Py-GC/MS) method.

(4-3-2) Particles

The fluororesin forming the surface layer preferably has an average particle size of 1 μm to 15 μm, more preferably 1 μm to 12 μm, even more preferably 2 μm to 10 μm, as measured according to a laser diffraction particle size analysis method. Contains particles. The average particle diameter is a volume-weighted volume average diameter, and is measured according to JIS Z8825. The average particle size can be measured using, for example, a particle size analyzer (SALD-2200, Shimadzu Corporation). By including the particles, the releasability of the release film can be improved.

The types of the particles are as described in "(4-2-3) Particles" above, and the explanation also applies to the particles contained in the mold side surface layer. Therefore, a description of the particles will be omitted.

The content of the particles in the fluororesin composition is, for example, 10 parts by mass to 30 parts by mass, preferably 12 parts by mass to 25 parts by mass, based on 100 parts by mass of the reactive functional group-containing fluoropolymer. , more preferably 15 parts by weight to 20 parts by weight. These numerical ranges also apply to the content of the particles in the cured product of the fluororesin composition.
The content of the particles may be determined by thermogravimetric analysis (TGA).

(4-3-3) Other ingredients

The fluororesin composition may contain a solvent. The type of solvent is as described in "(4-2-4) Other components" above, and the explanation also applies to the solvent contained in the mold side surface layer.

The fluororesin composition may include a release promoter. The type of mold release promoter is as described in "(4-2-4) Other components" above, and the explanation also applies to the solvent contained in the mold side surface layer. The release accelerator is, for example, 0.01 parts by mass to 3 parts by mass, preferably 0.05 parts by mass to 2 parts by mass, more preferably 0 parts by mass, based on 100 parts by mass of the reactive functional group-containing fluoropolymer. .1 part by weight to 1 part by weight. These numerical ranges also apply to the content of the release accelerator in the cured product of the fluororesin composition.

(4-3-4) Formation of mold side surface layer

The thickness of the mold side surface layer may be, for example, 1 μm to 10 μm, preferably 2 μm to 9 μm, and more preferably 3 μm to 8 μm.

The fluororesin composition can be produced by mixing and stirring the components described above by means known to those skilled in the art. Mixers such as high-speed mixers, homo mixers, and paint shakers can be used for the mixing and stirring. For the mixing and stirring, a dissolver such as an edge turbine type high speed dissolver may be used.
The cured product of the fluororesin composition is obtained by coating the fluororesin composition on the surface of the base layer and heating it at, for example, 100°C to 200°C, preferably 120°C to 180°C, for 10 seconds to 240 seconds. , preferably by heating for 30 seconds to 120 seconds. The cured product forms the surface layer. The amount of the fluororesin composition applied may be appropriately determined by those skilled in the art depending on the thickness of the surface layer to be formed.

In one preferred embodiment of the present technology, the mold side surface layer is formed from a cured product of a fluororesin composition containing the reactive functional group-containing fluoropolymer, the curing agent, and the particles. There is.
More preferably, the mold side surface layer is formed from a cured product of a fluororesin composition containing a hydroxyl group-containing tetrafluoroethylene polymer, an HDI polyisocyanate, and silicon dioxide particles.
Having this mold-side surface layer particularly contributes to providing the release film of the present invention with excellent mold release properties.

(5) Physical properties of release film

According to a preferred embodiment of the present invention, the tensile breaking strength of the release film of the present invention is 40 MPa to 200 MPa, more preferably 40 MPa to 120 MPa, and even more preferably is 40 MPa to 110 MPa, particularly preferably 45 MPa to 100 MPa, and the tensile elongation at break of the release film is 200% to 500%, more preferably when measured at 175° C. according to JIS K7127. may be from 250% to 450%, even more preferably from 300% to 400%.
The fact that the tensile strength at break and the tensile elongation at break of the release film of the present invention are within the above numerical ranges contributes to making the release film of the present invention usable in multiple moldings.

The gas (O ² ) permeability of the release film of the present invention is, for example, 5,000 to 50,000 cc/m ² ·24 hr · atm, particularly 5,000 to 30,000 cc/m 2 , when measured at 175°C according to JIS K7126-1. m ² .24 hr.atm, more particularly 5000 to 20000 cc/m ² .24 hr.atm. The release film of the present invention has such low gas permeability. Therefore, by performing molding using the mold release film of the present invention, mold contamination due to gas generated from the resin is suppressed.

The thickness of the release film of the present invention may be, for example, 30 μm to 100 μm, preferably 35 μm to 90 μm, and more preferably 40 to 80 μm. When the thickness of the release film of the present invention is within the above numerical range, the release film easily deforms according to the shape of the mold.

2. Second embodiment (method for manufacturing release film)

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

The surface layer forming step is, for example, a coating step of applying a tetrafluoroethylene resin composition containing a conductive filler to one of two surfaces of a base material layer formed from a polyester resin. and a curing step of curing the tetrafluoroethylene resin composition after the coating step.
Regarding the base material layer and the tetrafluoroethylene resin composition used in the coating process, the contents described in the above "1. First embodiment (release film)" apply, so a description of these will be omitted. .
Said application step may be carried out as appropriate by a person skilled in the art to achieve the desired layer thickness. For example, the tetrafluoroethylene resin composition can be applied to the base material layer by a gravure roll method, a reverse roll method, an offset gravure method, a kiss coating method, a reverse kiss coating method, a wire bar coating method, a spray coating method, or an impregnation method. can be applied on two sides. Apparatus for coating by these methods may be appropriately selected by those skilled in the art.
In the curing step, the fluororesin composition is heated at, for example, 100°C to 200°C, preferably 120°C.
It includes heating at ~180°C, for example for 10 seconds to 240 seconds, preferably 30 seconds to 120 seconds.
The fluororesin composition is cured by the heating.

The other of the two surfaces may be coated with a tetrafluoroethylene resin composition and cured, or a fluororesin composition different from the tetrafluoroethylene resin composition may be applied. It may be applied and cured. Regarding the tetrafluoroethylene resin composition and the fluororesin composition, the contents described in the above "1. First embodiment (release film)" apply. The description of the curing process described regarding the one surface applies to the curing process.

3. Example

Hereinafter, the present invention will be explained in more detail based on Examples. It should be noted that the examples described below are only representative examples of the present invention, and the scope of the present invention is not limited only to these examples.

(Comparative example 1)

A film made of easily moldable polyethylene terephthalate resin (Teflex FT, Teijin Ltd., thickness 50 μm, glass transition temperature 90° C.) was prepared as the base material layer.
Next, two types of fluororesin compositions (hereinafter referred to as a resin composition for a mold side surface layer and a resin composition for a molded body side surface layer) to be applied to the film were prepared. The mold-side surface layer resin composition forms a surface layer that comes into contact with a mold in a semiconductor device sealing process. The molded body surface layer resin composition forms a surface layer that comes into contact with the sealing resin (molded body) in the sealing process.
The resin composition for the mold side surface layer was prepared using 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene polymer solution (Zeffle GK570, Daikin Industries, Ltd., of which 65% by mass was a hydroxyl group-containing tetrafluoroethylene polymer). ), 11.47 parts by mass of amorphous silicon dioxide (Silysia 380, Fuji Silysia Chemical Co., Ltd.), 10 parts by mass of isocyanurate type polyisocyanate (curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), adduct type polyisocyanate It was prepared by mixing and stirring 7.79 parts by mass (curing agent, Duranate AE700-100), 6.18 parts by mass of butyl acetate, 44.62 parts by mass of ethyl acetate, and 89.25 parts by mass of MEK. The average particle diameter (the volume average diameter) of the amorphous silicon dioxide is measured using a particle size analyzer (SALD-2200, Shimadzu Corporation) according to the laser diffraction particle size analysis method. , 9.0 μm.
The resin composition for the surface layer on the side of the molded body is 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene polymer solution (Zeffle GK570, Daikin Industries, Ltd., of which 65 mass% is a hydroxyl group-containing tetrafluoroethylene polymer). , 10 parts by weight of isocyanurate type polyisocyanate (curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.79 parts by weight of adduct type polyisocyanate (curing agent, Duranate AE700-100), 0.0 parts by weight of amino-modified methylpolysiloxane. It was prepared by mixing and stirring 31 parts by mass (mold release accelerator, 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.

The mold side surface layer resin composition was applied to one side of the film, and the molded body side surface layer resin composition was applied to the other side of the film. These coatings were performed using a kiss-reverse coating device. After the coating, these compositions are cured by heating at 150°C for 60 seconds to form a release film (hereinafter referred to as "Comparative Example 1 A release film (referred to as "Release Film") was obtained.

The thickness of the release film of Comparative Example 1 was 70±5 μm. The thickness of the base material layer in the release film of Comparative Example 1 was 50±5 μm. Of 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 mold side surface layer resin composition was 5.5 ± 0.5 μm. . The thickness of the molded body surface layer formed from the cured product of the resin composition for the molded body surface layer was 5.5±0.5 μm.

The cured product of the resin composition for the mold side surface layer contains 17.65 parts by mass of the amorphous silicon dioxide based on 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer, and contains the isocyanurate type polyester. It contained 15.39 parts by mass of isocyanate and 11.98 parts by mass of the adduct type polyisocyanate.

The cured product of the resin composition for the molded body side surface layer contains 17.65 parts by mass of the amorphous silicon dioxide based on 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer, and contains the isocyanurate type polyisocyanate. 15.39 parts by mass, 11.98 parts by mass of the adduct polyisocyanate, and 0.48 parts by mass of amino-modified methylpolysiloxane.

(Comparative example 2)

The amount of the hydroxyl group-containing tetrafluoroethylene polymer in the resin composition for the surface layer on the molded body side was reduced by 1% by mass, and Ketjen Black (ECP600JD, Lion Specialty Chemicals Co., Ltd., powder form) was added by the amount of the reduced mass. ) A release film (release film of Comparative Example 2) was obtained in the same manner as in Comparative Example 1 except for adding . Regarding the Ketjen black, the DBP oil absorption amount was 495 ml/100 g, and the iodine adsorption amount was 1050 mg/g. The average particle size of the Ketjen black was 10 μm when measured according to a laser diffraction particle size analysis method.
That is, the amount of the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen Black contained in the surface layer on the molded body side of the release film of Comparative Example 2. The amount is 99 parts by mass, and the amount of Ketjen black per 100 parts by mass of the total amount is 1 part by mass.
Further, the amount of Ketjenblack was 1.01 parts by mass per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Comparative Example 2.

(Reference example 1)
Note that in the following, "Example 1" to "Example 9" will be read as "Reference Example 1" and "Reference Example 9", respectively. Furthermore, “Example 14” to “Example 19” shall be read as “Reference Example 14” to “Reference Example 19”, respectively.

The amount of the hydroxyl group-containing tetrafluoroethylene polymer in the resin composition for the surface layer on the molded body side was reduced by 3% by mass, and Ketjen Black (ECP600JP, Lion Specialty Chemicals Co., Ltd., powder form) was added by the reduced mass. A release film (release film of Example 1) was obtained in the same manner as in Comparative Example 1, except for adding .
That is, the amount of the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen black contained in the surface layer on the molded body side of the release film of Example 1. The amount is 97 parts by mass, and the amount of Ketjenblack per 100 parts by mass of the total amount is 3 parts by mass.
Further, the amount of Ketjenblack was 3.09 parts by mass per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 1.

(Example 2)

The amount of the hydroxyl group-containing tetrafluoroethylene polymer in the resin composition for the surface layer on the molded body side was reduced by 5% by mass, and Ketjen black (ECP600JP, Lion Specialty Chemicals Co., Ltd., powder form) was added by the reduced mass. ) A release film (release film of Example 2) was obtained in the same manner as in Comparative Example 1, except that the release film of Example 2 was added.
That is, the amount of the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen black contained in the surface layer on the molded body side of the release film of Example 2. The amount is 95 parts by mass, and the amount of Ketjen black per 100 parts by mass of the total amount is 5 parts by mass.
Further, the amount of Ketjenblack was 5.26 parts by mass per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 2.

(Example 3)

Amorphous silicon dioxide (Silysia 380, Fuji A release film (release film of Example 3) was obtained in the same manner as in Comparative Example 2, except that Silicia Chemical Co., Ltd.) was further added.
That is, the amount of the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen black contained in the surface layer on the molded body side of the release film of Example 3. The amount is 99 parts by mass, and the amount of Ketjen black per 100 parts by mass of the total amount is 1 part by mass.
Further, the amount of Ketjenblack was 1.01 parts by mass per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release film of Example 3. The amount of amorphous silicon dioxide particles was 15.15 parts by mass per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of Example 3.

(Examples 4 and 5)

In the resin composition for the surface layer on the side of the molded body, amorphous silicon dioxide ( Release films (the release film of Example 4 and the release film of Example 5) were obtained in the same manner as in Example 1, except that Cylysia 380 (Fuji Silysia Chemical Co., Ltd.) was further added.
That is, the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen black contained in the surface layer on the molded body side of the release films of Examples 4 and 5. The combined amount was 97 parts by mass, and the amount of Ketjenblack per 100 parts by mass of the combined amount was 3 parts by mass.
Further, the amount of Ketjen black per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release films of Examples 4 and 5 was 3.09 parts by mass. . The amount of amorphous silicon dioxide particles per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release films of Examples 4 and 5 was 5.15 parts by mass and 5.15 parts by mass, respectively. It is 15.46 parts by mass.

(Examples 6 and 7)

The release film (the release film of Example 6 and the example 7) was obtained. Regarding carbon ECP, the DBP oil absorption amount was 365 ml/100 g, and the iodine adsorption amount was 790 mg/g. The average particle size of the Ketjen black was 10 μm when measured according to a laser diffraction particle size analysis method.

(Examples 8 and 9)

In the resin composition for the surface layer on the side of the molded body, amorphous silicon dioxide ( Release films (the release film of Example 8 and the release film of Example 9) were obtained in the same manner as in Example 2, except that Cylysia 380 (Fuji Silysia Chemical Co., Ltd.) was further added.
That is, the hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer and Ketjen black contained in the surface layer on the molded body side of the release films of Examples 8 and 9. The combined amount was 95 parts by mass, and the amount of Ketjenblack per 100 parts by mass of the combined amount was 5 parts by mass.
Further, the amount of Ketjen black per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release films of Examples 8 and 9 was 5.26 parts by mass. . The amounts of amorphous silicon dioxide particles per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release films of Examples 4 and 5 were 5.26 parts by mass and 5.26 parts by mass, respectively. It is 15.79 parts by mass.

(Example 10)

A film made of easily moldable polyethylene terephthalate resin (Teflex FT, Teijin Ltd., thickness 50 μm, glass transition temperature 90° C.) was prepared as the base material layer.
Next, two types of fluororesin compositions (hereinafter referred to as a resin composition for a mold side surface layer and a resin composition for a molded body side surface layer) to be applied to the film were prepared. The mold-side surface layer resin composition forms a surface layer that comes into contact with a mold in a semiconductor device sealing process. The molded body surface layer resin composition forms a surface layer that comes into contact with the sealing resin (molded body) in the sealing process.
The resin composition for the mold side surface layer was the same as that of Comparative Example 1.
The resin composition for the surface layer on the side of the molded body is 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene polymer solution (Zeffle GK570, Daikin Industries, Ltd., of which 65 mass% is a hydroxyl group-containing tetrafluoroethylene polymer). , 10 parts by mass of isocyanurate type polyisocyanate (curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.8 parts by mass of adduct type polyisocyanate (curing agent, Duranate AE700-100), 2.78 parts by mass of Ketjenblack (ECP600JD, Lion Specialty Chemicals Co., Ltd.), Furnace Black 11.1 parts by mass (Mitsubishi Black #10, Mitsubishi Chemical Corporation, average particle size 75 nm, DBP oil absorption 86 ml/100 g), Amorphous silicon dioxide 13 .9 parts by mass (Silysia 380, Fuji Silicia Chemical Co., Ltd.), 0.6 parts by mass of amino-modified methylpolysiloxane (mold release accelerator, Shin-Etsu Chemical Co., Ltd.), 56.9 parts by mass of ethyl acetate, and MEK113.8 Prepared by mixing and stirring parts by weight.

In the same manner as Comparative Example 1, the resin composition for the mold side surface layer and the resin composition for the molded object side surface layer are applied to a film, and then heated to harden these compositions to easily mold them. A release film (hereinafter referred to as "release film of Example 10") was obtained in which fluororesin layers were laminated on both sides of a PET resin film.

The thickness of the release film of Example 10 was 70±5 μm. The thickness of the base layer in the release film of Example 10 was 50±5 μm. Of the two surface layers of the release film of Example 10, the thickness of the mold side surface layer formed from the cured product of the mold side surface layer resin composition was 5.5 ± 0.5 μm. . The thickness of the molded body surface layer formed from the cured product of the resin composition for the molded body surface layer was 5.5±0.5 μm.

The hydroxyl group-containing tetrafluoride per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer, Ketjen black, furnace black, and silicon dioxide particles contained in the molded body side surface layer of the release film of Example 10 The amount of the ethylene polymer is 70 parts by mass, and the amounts of Ketjen black, furnace black, and silicon dioxide particles per 100 parts by mass of the same total amount are 3 parts by mass, 12 parts by mass, and 15 parts by mass, respectively. Department.
Further, the amounts of Ketjen black, furnace black, and silicon dioxide particles were each 4.0 parts per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 10. They are 29 parts by mass, 17.14 parts by mass, and 21.43 parts by mass.

(Examples 11 and 12)

The release film (the release film of Example 11 and A release film of Example 12) was obtained.

(Example 13)

The amounts of Ketjen black and furnace black per 100 parts by mass of the total amount of hydroxyl group-containing tetrafluoroethylene polymer, Ketjen black, furnace black, and silicon dioxide particles were changed to 0 parts by mass and 15 parts by mass, respectively. A release film was obtained in the same manner as in Example 10, except for the following.
The amounts of Ketjen black and furnace black per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release film of Example 13 were 0 parts by mass and 21.43 parts by mass, respectively. It is.

(Example 14)

A film made of easily moldable polyethylene terephthalate resin (Teflex FT, Teijin Ltd., thickness 50 μm, glass transition temperature 90° C.) was prepared as the base material layer.
Next, two types of fluororesin compositions (hereinafter referred to as a resin composition for a mold side surface layer and a resin composition for a molded body side surface layer) to be applied to the film were prepared. The mold-side surface layer resin composition forms a surface layer that comes into contact with a mold in a semiconductor device sealing process. The molded body surface layer resin composition forms a surface layer that comes into contact with the sealing resin (molded body) in the sealing process.
The resin composition for the mold side surface layer is that of Comparative Example 1.
The resin composition for the surface layer on the side of the molded body is 100 parts by mass of a hydroxyl group-containing tetrafluoroethylene polymer solution (Zeffle GK570, Daikin Industries, Ltd., of which 65 mass% is a hydroxyl group-containing tetrafluoroethylene polymer). , 10 parts by mass of isocyanurate type polyisocyanate (curing agent, Sumidur N3300, Sumitomo Bayer Urethane Co., Ltd.), 7.8 parts by mass of adduct type polyisocyanate (curing agent, Duranate AE700-100), 2.78 parts by mass of Ketjenblack (ECP600JD, Lion Specialty Chemicals Co., Ltd.), Furnace Black 11.1 parts by mass (Mitsubishi Black #10, Mitsubishi Chemical Corporation), Amino-modified methylpolysiloxane 0.6 parts by mass (mold release accelerator, Shin-Etsu Chemical) Kogyo Co., Ltd.), 48.6 parts by mass of ethyl acetate, and 97.1 parts by mass of MEK.

In the same manner as Comparative Example 1, the resin composition for the mold side surface layer and the resin composition for the molded object side surface layer are applied to a film, and then heated to harden these compositions to easily mold them. A release film (hereinafter referred to as "Release Film of Example 14") was obtained in which fluororesin layers were laminated on both sides of a PET resin film.

The thickness of the release film of Example 14 was 70±5 μm. The thickness of the base material layer in the release film of Example 14 was 50±5 μm. Of the two surface layers of the release film of Example 14, the thickness of the mold side surface layer formed from the cured product of the mold side surface layer resin composition was 5.5 ± 0.5 μm. . The thickness of the molded body surface layer formed from the cured product of the resin composition for the molded body surface layer was 5.5±0.5 μm.

The hydroxyl group-containing tetrafluoroethylene polymer per 100 parts by mass of the total amount of the hydroxyl group-containing tetrafluoroethylene polymer, Ketjen black, and furnace black contained in the molded body side surface layer of the release film of Example 14 The amount of Ketjen Black and Furnace Black is 85 parts by mass, and the amounts of Ketjen Black and Furnace Black per 100 parts by mass are 3 parts by mass and 12 parts by mass, respectively.
Further, the amounts of Ketjen Black and Furnace Black were 3.53 parts by mass and 14 parts by mass, respectively, per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the molded body side surface layer of the release film of Example 14. .12 parts by mass.

(Example 15)

The amount of the hydroxyl group-containing tetrafluoroethylene polymer per 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 on the molded body side was changed to 92 parts by mass. The release film (of Example 15) was prepared in the same manner as in Example 14, except that the amounts of Ketjen Black and Furnace Black were changed to 3 parts by mass and 5 parts by mass, respectively, per 100 parts by mass of the same total amount. A release film) was obtained.
The amounts of Ketjen black and furnace black per 100 parts by mass of the hydroxyl group-containing tetrafluoroethylene polymer contained in the surface layer on the molded body side of the release film of Example 15 were 3.26 parts by mass and 5.43 parts by mass, respectively. Part by mass.

(Examples 16 and 17)

Release films (the release film of Example 16 and the release film of Example 17) were obtained in the same manner as in Examples 14 and 15, except that carbon ECP was used as Ketjen black instead of ECP600JD. .

(Examples 18 and 19)

Release films (the release film of Example 18 and the release film of Example 19) were obtained in the same manner as in Examples 14 and 15, except that ECP200L was used as Ketjen black instead of ECP600JD.

Tables 1 to 3 show the compositions of the surface layer on the molded body side of the release films of Comparative Examples 1 and 2 and Examples 1 to 19.

Regarding the release films of Comparative Examples 1 and 2 and Examples 1 to 19, the surface resistivity Rs of the surface layer on the molded body side was measured and evaluated according to the following criteria. Note that "E+" regarding 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 ⁹ . The same applies to the surface resistivity Rs of other examples. The evaluation results are shown in Tables 1 to 3 above.
A: Rs is 1×10 ⁹ Ω or less
B: Rs is more than 1×10 ⁹ Ω and less than 1×10 ¹¹ Ω C: Rs is more than 1×10 ¹¹ Ω

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 Examples 1 and 2 and Examples 1 to 19 was evaluated. The dispersibility was evaluated using a grind gauge (Model 232 type grind gauge manufactured by Eriksen Co., Ltd.) in accordance with JIS K5600-2-5. The evaluation results are shown in Tables 1 to 3 above.
A: Streaks do not appear B: Streaks appear at groove depths of 35 μm or less C: Streaks appear at groove depths of 40 μm or less

Regarding the release films of Comparative Examples 1 and 2 and Examples 1 to 19, the appearance of the molded body side surface was visually evaluated. The evaluation criteria are as follows. The evaluation results are shown in Tables 1 to 3 above.
A: There is no uneven black color on the surface.
B: There is slight unevenness in the black color on the surface.
C: There is uneven black color on the surface.

The following can be seen from the evaluation results shown in Tables 1 to 3 above.

It can be seen that the release films of Examples 1 to 19 all have a surface resistivity Rs of 1×10 ¹¹ Ω or less, and have static electricity dissipation properties.

The molded body side surface layer of the release film of Comparative Example 1 did not contain carbon black and had a surface resistivity Rs of more than 1×10 ¹¹ Ω. Further, the surface layer on the molded body side of the release film of Comparative Example 2 contained Ketjen black, but the surface resistivity Rs was more than 1×10 ¹¹ Ω. On the other hand, in Examples 1 and 2, which had a higher content of Ketjen black than Comparative Example 2, the surface resistivity Rs was 1×10 ¹¹ Ω or less. From these results, when the conductive filler is Ketjen black, the content of Ketjen black is, for example, 3 parts by mass or more based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer. It can be seen that by doing so, static electricity dissipation properties can be imparted to the release film.

The surface layer on the molded body side of the release film of Comparative Example 2 contained Ketjenblack, and had a surface resistivity Rs of more than 1×10 ¹¹ Ω. On the other hand, the release film of Example 3, which had the same amount of Ketjenblack but further contained silicon dioxide particles, had a surface resistivity Rs of 1×10 ¹¹ Ω or less. These results show that the combination of Ketjenblack and silicon dioxide particles can impart static electricity dissipation to the release film. It is also found that when silicon dioxide particles are included, static electricity dissipation properties can be imparted to the release film with a smaller amount of Ketjenblack. For example, when silicon dioxide particles are included, the amount of Ketjenblack may be 1 part by mass or more based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer.

From a comparison of the release films of Examples 3 and 5, when silicon dioxide particles are included, the amount of Ketjenblack is 3 parts by mass or more based on 100 parts by mass of the tetrafluoroethylene polymer containing a reactive functional group. It can be seen that this makes it possible to improve the static electricity dissipation properties of the release film.

A comparison of the release films of Examples 4 and 5 and Examples 6 and 7 shows that good static electricity dissipation properties can be obtained even if the type of Ketjenblack is changed.
Further, from a comparison of the release films of Examples 4 and 5 and Examples 8 and 9, it can be seen that even if the amount of Ketjenblack is increased, good static electricity dissipation properties can be obtained.

A comparison of the release films of Examples 1 and 5 shows that by including silicon dioxide particles in addition to Ketjen black, the dispersibility of the composition for preparing the surface layer on the molded body side can be improved, and the resulting molding It can be seen that the appearance of the body side surface layer can be improved.

In Examples 3 to 9, the evaluation results for static electricity dissipation were A, while the evaluation results for dispersibility and appearance were B. On the other hand, in Examples 10 to 12, the evaluation results for static electricity dissipation were A, and the evaluation results for dispersibility and appearance were also A. From these results, by including furnace black in addition to Ketjen black and silicon dioxide particles, it is possible to obtain good static electricity dissipation and improve the dispersibility of the composition for preparing the surface layer on the molded body side. It can be seen that it is possible to improve the appearance of the surface layer on the molded body side.

From the comparison of Examples 10 to 12 and Example 13, it was found that the combination of furnace black and silicon dioxide particles also provided good static electricity dissipation, improved the dispersibility of the composition for preparing the surface layer on the molded body side, and It can be seen that it is possible to improve the appearance of the surface layer on the side of the molded body obtained.

From the results of Examples 14 to 18, it can be seen that good static electricity dissipation properties can also be obtained by a combination of Ketjen black and furnace black. It is also found that the combination can improve the dispersibility of the composition for preparing the surface layer on the molded body side. Although the degree of improvement is inferior to Examples 10 to 12 containing silicon dioxide particles, the results of Examples 14 to 18 show that the combination can improve the appearance of the surface layer on the molded body side.

Further, using the release films of Comparative Examples 1 and 2 and Examples 1 to 19, molding was performed by transfer molding of epoxy resin. The molding was performed as shown in FIG. As a result, no matter which release film was used, the epoxy resin molded article was peeled off smoothly from the release film. Therefore, it can be seen that although the molded body side surface layer of the mold release film of the present invention contains the conductive filler, it has the same mold releasability as when it does not contain the conductive filler. Furthermore, the release properties of the release films of Comparative Examples 1 and 2 and Examples 1 to 19 were maintained through multiple moldings.

100 Release film 101 Base layer 102 Surface layer 103 Surface layer

Claims (10)

a base material layer formed from polyester resin;
and a surface layer formed from a tetrafluoroethylene resin containing a conductive filler and silicon dioxide particles,
The average particle size of the silicon dioxide particles is 1 μm to 15 μm when measured according to a laser diffraction particle size analysis method,
The tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
The content of the silicon dioxide particles is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The content of the conductive filler is 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The conductive filler contains carbon black,
The carbon black includes at least furnace black having a DBP oil absorption of 200 ml/100 g or less,
The surface resistivity Rs is 1×10 ⁹ Ω or less,
Release film. The release film according to claim 1, wherein the polyester resin is a polyethylene terephthalate resin. The release film according to claim 1 or 2, wherein the polyester resin has a glass transition temperature of 60°C to 95°C. The release film according to any one of claims 1 to 3, wherein the surface layer is laminated on one of two surfaces of the base layer. The release film according to claim 3, wherein a surface layer made of a fluororesin is laminated on the other of the two surfaces of the base layer. The release film according to any one of claims 1 to 5, which is used for sealing a semiconductor device. The release film according to claim 6, wherein in the sealing, the surface layer made of a tetrafluoroethylene resin containing the conductive filler is arranged so as to be in contact with a sealing resin. The release film according to any one of claims 1 to 7, used for transfer molding or compression molding. The release film according to any one of claims 1 to 8, which is used for molding twice or more. A surface layer formed from a tetrafluoroethylene resin containing a conductive filler and silicon dioxide particles on one of two surfaces of a base layer formed from a polyester resin. including a forming step;
The average particle size of the silicon dioxide particles is 1 μm to 15 μm when measured according to a laser diffraction particle size analysis method,
The tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
The content of the silicon dioxide particles is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The content of the conductive filler is 1 part by mass to 25 parts by mass based on 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer in the tetrafluoroethylene resin,
The conductive filler contains carbon black,
The carbon black includes at least furnace black having a DBP oil absorption of 200 ml/100 g or less,
The surface resistivity Rs of the release film to be produced is 1×10 ⁹ Ω or less,
Method for manufacturing release film.