Release film

Abstract

The purpose of the present invention is to provide a release film excellent in releasability, antistatic property and smoothness, and excellent in processability such as workability and slipperiness when winding the film into a roll.　The present invention is a release film having a base material layer, an antistatic layer, and a release layer in this order. The release layer has an area surface average roughness (Sa) of 10 nm or less, the base material layer has an area surface average roughness (Sa) of 10 nm or less on a surface opposite to a surface with the antistatic layer, the antistatic layer has a thickness of 7-60 nm, the release layer has a thickness of 50 nm or less, and the release layer contains a silicone release agent.

Description

Release film

[0001] The present invention relates to a release film for photosensitive resin formation.

[0002] In the manufacture of printed wiring boards, semiconductor packages, flexible substrates, and the like, there is a process of forming a resist pattern on the substrate by pattern-exposing a photosensitive resin layer on the substrate to polymerize and harden the exposed areas and removing the unexposed areas. In recent years, with the progress of miniaturization of electronic devices and the advancement of circuit integration, and with the demand for miniaturization of laminated electronic components mounted on electronic devices, high resolution that enables the formation of fine resist patterns is required for the photosensitive resin layer. For example, Patent Document 1 discloses a release film that has excellent release properties for a photosensitive resin layer.

[0003] However, as described in the above-mentioned patent documents, when a photosensitive resin is applied onto a release layer, charging of the release film may cause repelling, etc. Therefore, in order to prevent charging, a release film with low charging has been proposed by providing an intermediate layer containing an antistatic agent between the base film and the release layer (Patent Document 2).

[0004] However, with the recent trend toward miniaturization of electronic devices and increased circuit integration, when forming a fine resist pattern on a photosensitive resin layer, the laser light used to harden the photosensitive resin is scattered by the unevenness of the film surface, resulting in a problem of reduced resist resolution. To address this issue, a method of using a smooth substrate film has been considered to suppress light scattering, but providing an antistatic layer and a release layer on a smooth film results in a problem of poor slipperiness and reduced productivity.

[0005] JP 2022-57020 A JP 2014-12417 A

[0006] The present invention has been made in view of the problems of the prior art. That is, an object of the present invention is to provide a release film that is excellent in releasability, antistatic properties, and smoothness, and that is excellent in workability when winding the film into a roll and in processability such as easy lubricity.

[0007] The present inventors have focused on the problem that a release film has a trade-off relationship between the peeling strength, antistatic properties, and slippage properties in a well-balanced manner, and that, for example, improving the peeling strength and antistatic properties of the release film results in a deterioration in slippage properties and a decrease in productivity. As a result of extensive investigations aimed at achieving the above object, the present inventors have found that the above problems can be easily solved by using a film having a specific configuration, and have thus completed the present invention.

[0008] That is, the present invention has the following configurations. [1] A release film having a base layer, an antistatic layer, and a release layer in this order, wherein the release layer has a regional surface average roughness (Sa) of 10 nm or less, the regional surface average roughness (Sa) of the surface of the base layer opposite to the surface having the antistatic layer is 10 nm or less, the antistatic layer has a thickness of 7 to 60 nm, the release layer has a thickness of 50 nm or less, and the release layer contains a silicone-based release agent. [2] The release film according to [1], which has a haze of 1.5% or less. [3] The release film according to [1] or [2], which has a light transmittance of 85% or more at a wavelength of 365 nm. [4] The amount of internal foreign matter of 3 μm or more contained in the base layer is 50 pieces / mm ２ The release film according to any one of [1] to [3] below.

[0009] The release film of the present invention has excellent releasability, antistatic properties, and smoothness, and is suitable as a support for forming a photosensitive resin. A photosensitive resin film using the release film for forming a photosensitive resin of the present invention as a support is excellent in the resolution of the resin layer, the pattern formability of the surface and edges, and the appropriate adhesion of the resin layer. Furthermore, the release film for forming a photosensitive resin of the present invention is also excellent in handleability when used as a support to produce a photosensitive resin film. In the present invention, problems that may arise when the numerical values ​​are outside the ranges described in the specification are sometimes described. On the other hand, if the numerical values ​​are within the ranges described in the specification, the present invention can solve these problems and achieve further effects.

[0010] The release film of the present invention is a film comprising a substrate layer having an antistatic layer and a release layer provided in this order on at least one side thereof. (Substrate Layer) A polyester-based resin film is preferably used as the substrate layer constituting the release film of the present invention. Examples include films made of polyester-based resins primarily composed of polyesters such as aromatic linear polyesters composed of aromatic dicarboxylic acids and diols, such as polyethylene terephthalate and polyethylene naphthalate, aliphatic linear polyesters composed of aliphatic dicarboxylic acids and diols, and copolymers thereof. Among these, films made of aromatic linear polyester resins, such as polyethylene terephthalate and polyethylene naphthalate, are preferred. The substrate layer may be formed from one type of the polyester-based resin or a mixture of two or more types. Such a substrate layer may be a single layer or a multi-layer structure consisting of two or more layers. The thickness of the film is preferably 12 to 75 μm, more preferably 25 to 70 μm, and even more preferably 30 to 50 μm. If the thickness exceeds 75 μm, the resolution tends to decrease, and if the thickness is less than 12 μm, the strength is insufficient and tearing may occur, especially during peeling. The linear polyester refers to a polyester that contains no or almost no trivalent or higher polyvalent monomers. Specifically, the total content of trivalent or higher polyhydric alcohols and trivalent or higher polycarboxylic acid compounds is less than 1 mol %, preferably 0.5 mol % or less, of the total amount of carboxylic acid components and alcohol components.

[0011] The catalyst for polycondensation used in producing the polyester resin is not particularly limited, but antimony trioxide is preferred because it is inexpensive and has excellent catalytic activity. It is also preferable to use a germanium compound or a titanium compound. More preferred polycondensation catalysts include catalysts containing aluminum and / or its compound and a phenolic compound, catalysts containing aluminum and / or its compound and a phosphorus compound, and catalysts containing an aluminum salt of a phosphorus compound. The upper limit of the content of the antimony compound in the polyester is preferably 150 ppm, more preferably 120 ppm, and even more preferably 80 ppm or less. An antimony content of 150 ppm or less suppresses light scattering of the laser light used to cure the photosensitive resin, enabling the formation of fine patterns in the photosensitive resin.

[0012] Furthermore, the base layer in the present invention is not particularly limited in terms of its layer structure, and may be a single-layer polyester-based resin film, a two-layer structure having different components, or a polyester-based resin film consisting of at least three layers having an outer layer and an inner layer.

[0013] (Release Layer) The area surface average roughness (Sa) of the release layer of the release film of the present invention is 10 nm or less, preferably 8 nm or less, more preferably 6 nm or less, and particularly preferably 5 nm or less. The area surface average roughness (Sa) of the release layer means the area surface average roughness (Sa) of the surface opposite to the surface of the release layer having the antistatic layer. When the area surface average roughness (Sa) is 10 nm or less, light scattering of the laser light for curing the photosensitive resin is suppressed, making it possible to form a fine pattern of the photosensitive resin. The area surface average roughness (Sa) of the release layer is preferably 0.1 nm or more, more preferably 0.5 nm or more, and may be 1 nm or more or 1.5 nm or more. When the area surface average roughness (Sa) is less than 0.1 nm, there is a concern that the ease of slippage when winding the film into a roll may decrease.

[0014] In the release film of the present invention, the area surface average roughness (Sa) of the surface of the base layer opposite to the surface having the antistatic layer is 10 nm or less, preferably 8 nm or less, more preferably 6 nm or less, and particularly preferably 5 nm or less. When the area surface average roughness (Sa) is 10 nm or less, light scattering of the laser light for curing the photosensitive resin is suppressed, making it possible to form a fine pattern of the photosensitive resin. The area surface average roughness (Sa) of the surface of the base layer opposite to the surface having the antistatic layer is preferably 0.1 nm or more, more preferably 0.5 nm or more, and may be 1 nm or more or 1.5 nm or more. When the area surface average roughness (Sa) is less than 0.1 nm, there is a concern that the ease of sliding when winding the film into a roll may decrease.

[0015] In one embodiment, the area surface average roughness (Sa) of the release layer is preferably smaller than or equal to the area surface average roughness (Sa) of the surface of the base layer opposite to the surface having the antistatic layer. Such a relationship suppresses light scattering of the laser light used to harden the photosensitive resin, enabling fine pattern formation of the photosensitive resin and avoiding problems such as reduced resist resolution. Furthermore, good slipperiness can be exhibited. In particular, the above relationship allows the release film to have a good balance of peel strength, light scattering suppression, and slipperiness. Conventional release films with antistatic properties have excellent antistatic properties and satisfy the minimum required properties for other physical properties, but further improvement in any of slipperiness, winding ability, and film-forming ability has sometimes been required. On the other hand, unlike conventional release films, the present invention can have a good balance of antistatic properties, releasability, slipperiness, winding ability, and film-forming ability. Furthermore, a photosensitive resin film using the release film for photosensitive resin formation of the present invention as a support is excellent in the resolution of the resin layer, the pattern formability of the surface and edges, and the appropriate adhesion of the resin layer, and further, is excellent in handleability when producing a photosensitive resin film using the release film for photosensitive resin formation of the present invention as a support.

[0016] The thickness of the release layer of the release film of the present invention is 50 nm or less, preferably 40 nm or less, and more preferably 30 nm or less. If the thickness of the release layer exceeds 50 nm, there is a concern that the ease of slippage when winding the film into a roll may decrease, or sufficient antistatic effect may not be obtained. In particular, in the present invention, a thickness of the release layer of 50 nm or less can exhibit a good balance of good releasability and antistatic property. The thickness of the release layer is preferably more than 5 nm, more preferably 7 nm or more, even more preferably 10 nm or more, and particularly preferably 20 nm or more. If the thickness of the release layer is 5 nm or less, sufficient releasability cannot be obtained. Furthermore, in the present invention, by keeping the thickness within the above range, for example, a good balance of release force and surface resistivity can be maintained, and excessive or insufficient release force or surface resistivity can be suppressed. The thickness of the release layer may be more than 5 nm and 50 nm or less, or may be 7 nm or more and 40 nm or less, or 10 nm or more and 30 nm or less.

[0017] (Antistatic Layer) The thickness of the antistatic layer in the release film of the present invention is 60 nm or less, preferably 50 nm or less, more preferably 45 nm or less, even more preferably 38 nm or less, and particularly preferably 30 nm or less. If the thickness of the antistatic layer exceeds 60 nm, there is a concern that the ease of slippage when winding the film into a roll may decrease. In addition, the surface resistance tends to increase, making the release film more likely to become charged. As a result, there may be cases where the film is not suitable for forming electronic devices, circuits, etc. The thickness of the antistatic layer is 7 nm or more, preferably 10 nm or more. If the thickness of the antistatic layer is less than 7 nm, a sufficient antistatic effect cannot be obtained. The thickness of the antistatic layer may be 7 nm or more and 60 nm or less, or 10 nm or more and 38 nm or less.

[0018] The haze of the release film of the present invention is preferably 1.5% or less, more preferably 1.3% or less, and even more preferably 1.25% or less. If the haze exceeds 1.5%, there is a concern that the light scattering of the laser light for curing the photosensitive resin will increase, resulting in a decrease in resolution. The haze of the release film may be 0%, 0.1% or more, or 0.3% or more.

[0019] The light transmittance at a wavelength of 365 nm of the release film of the present invention is, for example, 85% or more, preferably 87% or more, and more preferably 90% or more. The light transmittance at a wavelength of 365 nm is, for example, 100% or less, and may be 98% or less, or may be 97% or less. If the light transmittance at a wavelength of 365 nm is less than 85%, there is a concern that the light scattering of the laser light for curing the photosensitive resin will increase, resulting in a decrease in resolution. In the present invention, the light transmittance is measured by irradiating light from the release layer side toward the substrate layer.

[0020] The amount of internal foreign matter of 3 μm or more contained in the base layer of the release film of the present invention is preferably 50 pieces / mm ２ More preferably, 40 pieces / mm ２ More preferably, it is 30 pieces / mm or less. ２ The number of internal foreign particles of 3 μm or more is 50 / mm ２ If the number of internal foreign matters of 3 μm or more contained in the base layer exceeds 0 pieces / mm ２ 1 piece / mm ２ or more, and ２ Internal foreign matter of 3 μm or more is identified by measuring the major axis of the foreign matter using a microscope.

[0021] The release film of the present invention can be used to laminate a photosensitive resin layer used in the production of, for example, printed wiring boards, semiconductor packages, flexible substrates, etc., onto the release layer. The photosensitive resin layer may be used in a process in which a pattern is exposed on a substrate to polymerize and harden the exposed portions, and the unexposed portions are removed to form a resist pattern on the substrate. For example, when a photosensitive resin layer or a resin sheet described below is laminated onto the release layer of the present invention, moderate adhesion is preferred. Specifically, the peel force is preferably 50 mN / 50 mm or more but less than 300 mN / 50 mm, and may be 60 mN / 50 mm or more but 250 mN / 50 mm or less, or 80 mN / 50 mm or more but 200 mN / 50 mm or less. By having the peel force within the above range, the photosensitive resin layer can be held and peeled in an appropriate state. In addition, the surface resistance and dynamic friction coefficient can be brought within certain ranges, so that a good balance of antistatic properties, easy peelability, and easy slippage can be achieved. Furthermore, when the release film of the present invention is used as a release film for forming a photosensitive resin, the photosensitive resin layer formed is excellent in resolution of the resin layer, pattern formability on the surface and edges, and moderate adhesion of the resin layer. Furthermore, the handleability when producing a photosensitive resin film using the release film for forming a photosensitive resin of the present invention as a support is also excellent. In another aspect, the release layer contains a silicone-based release agent as a main component and further contains a mixture of at least one release agent selected from an alkyd resin-based release agent, a polyolefin-based release agent, and an acrylic resin-based release agent. However, the peel force may be 300 mN / 50 mm or more and less than 800 mN / 50 mm, and moderate adhesion is preferable, so that the peel force is preferably 300 mN / 50 mm or more and 600 mN / 50 mm or less.

[0022] The surface resistance value of the release film of the present invention is, for example, 10.0 log (Ω / □) or more and less than 15 log (Ω / □), or may be 10.5 log (Ω / □) or more and 14.0 log (Ω / □) or less, or may be 10.5 log (Ω / □) or more and 13.0 log (Ω / □) or less. When the surface resistance value is within such a range, a release film with excellent antistatic properties can be provided. This prevents charging when the film is unwound, which is thought to make it possible to prevent deterioration of the wettability of the resin layer and fires due to sparks.

[0023] The dynamic friction coefficient of the release film of the present invention is, for example, 0.50 or more and 1.0 or less, or 0.65 or more and 0.97 or less, or 0.7 or more and 0.95 or less, or 0.75 or more and 0.95 or less. By having the dynamic friction coefficient within the above range, a release film with excellent workability and slipperiness when wound into a roll can be obtained. Here, the present inventors have discovered that, in the present invention, the dynamic friction coefficient can be brought within a predetermined range by having the film thickness of the release layer and the film thickness of the antistatic layer within the range of the present invention. Although the mechanism is still under investigation, it is presumed that, when the relationship between the antistatic agent contained in the antistatic layer and the thickness of the antistatic layer, and the relationship between the predetermined release agent contained in the release layer and the thickness of the release layer, satisfy the conditions of the present invention, an interaction occurs between the antistatic layer and the release layer, and, for example, the antistatic agent is suitably dispersed within the release layer, thereby enabling the development of excellent antistatic properties. As a result, it is believed that a good balance of good peel force, surface resistance, and dynamic friction coefficient can be maintained.

[0024] In the present invention, it is desirable that all physical properties, including peel strength, surface resistance, and dynamic friction coefficient, fall within the numerical ranges described herein. By satisfying all of these physical properties, for example, it is possible to contribute to the integration of electronic devices and circuits, and when forming a fine resist pattern on a photosensitive resin layer, it is possible to suppress light scattering of the laser light used to harden the photosensitive resin due to the uneven shape of the film surface, thereby avoiding problems such as reduced resist resolution. Furthermore, it is possible to provide a release film that has good slip properties and is highly productive. Thus, the release film of the present invention can have a good balance between the peel strength, antistatic properties, and slip properties of the release film.

[0025] (Antistatic Agent) The antistatic layer of the release film of the present invention contains an antistatic agent. Any known antistatic agent can be used, and examples include surfactants, conductive resins, and silicon oxide. Among these, silicon oxide is preferred. Examples of antistatic agents containing silicon oxide include Colcoat EC920, Colcoat EC851, Colcoat P, and Colcoat N-103X, manufactured by Colcoat Co., Ltd. Although not intended to be limited to a specific theory, the antistatic layer contains the above-mentioned antistatic agent, and the release layer further contains a predetermined release agent as a release agent, thereby achieving a good balance of antistatic properties, easy releasability, and easy slippage. Furthermore, photosensitive resin films using the release film for photosensitive resin formation of the present invention as a support are excellent in resin film resolution, pattern formability on the surface and edges, and appropriate resin film adhesion. Furthermore, the handleability when producing a photosensitive resin film using the release film for photosensitive resin formation of the present invention as a support is also excellent. In particular, the present invention suppresses light scattering of laser light for curing photosensitive resin, making it possible to form fine patterns of photosensitive resin, and avoiding the problem of reduced resist resolution.

[0026] The content of the composition containing the antistatic agent is, for example, 10 to 80 parts by mass, and preferably 20 to 50 parts by mass, relative to 100 parts by mass of the antistatic layer coating liquid. The solid content of the antistatic agent contained in the antistatic layer is, for example, 1 to 15 parts by mass, and may be, for example, 1 to 10 parts by mass, relative to 100 parts by mass of the antistatic layer coating liquid. It is presumed that such a blending amount allows the antistatic agent to be suitably dispersed in the antistatic layer, thereby enabling the layer to exhibit excellent antistatic properties.

[0027] (Release Agent) The release agent (additive for improving the release properties of the release layer) used in the release layer of the present invention includes a silicone-based release agent from the viewpoint of releasability. In addition to the silicone-based release agent, a non-silicone-based release agent such as an olefin-based, long-chain alkyl-based, or fluorine-based release agent may also be used in combination. The silicone-based release agent preferably accounts for 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more of the total release agent.

[0028] The silicone-based release agent suitable for forming the release layer in the present invention is a resin having a silicone structure in its molecule, and examples thereof include curable silicones, silicone graft resins, and modified silicone resins such as alkyl-modified silicones. However, from the viewpoint of migration, it is preferable to use a reactive curable silicone resin. Examples of reactive curable silicone resins that can be used include addition reaction-based resins, condensation reaction-based resins, and ultraviolet or electron beam curable resins. Low-temperature curable addition reaction-based resins that can be processed at low temperatures, and ultraviolet or electron beam curable resins are more preferable. The use of these resins allows low-temperature processing when coating polyester films. Therefore, heat damage to the polyester film during processing is reduced, a polyester film with high flatness can be obtained, and defects such as pinholes can be reduced even when producing thin resin sheets.

[0029] Examples of silicone resins that use addition reactions include those that are cured by reacting polydimethylsiloxane, which has vinyl groups introduced into the terminals or side chains, with hydrogen siloxane using a platinum catalyst. In this case, it is more preferable to use a resin that can be cured within 30 seconds at 120°C, as this allows for processing at low temperatures. Examples include low-temperature addition cure types (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755, LTC760A, etc.) and thermal UV cure types (LTC851, BY24-510, BY24-561, BY24-562, etc.) manufactured by Dow-Toray Industries, and solvent addition + UV cure types (X62-5040, X62-5065, X62-5072T, KS5508, etc.) and dual cure cure types (X62-2835, X62-2834, X62-1980, etc.) manufactured by Shin-Etsu Chemical Co., Ltd.

[0030] An example of a condensation reaction silicone resin is one in which a three-dimensional crosslinked structure is formed by condensing a polydimethylsiloxane having an OH group at its terminal with a polydimethylsiloxane having an H group at its terminal using an organotin catalyst.

[0031] Examples of UV-curable silicone resins include, for example, the most basic type that utilizes the same radical reaction as normal silicone rubber crosslinking, those that introduce unsaturated groups to cause photocuring, those that use UV light to decompose onium salts to generate strong acids that then cleave epoxy groups to cause crosslinking, and those that crosslink via an addition reaction of thiol to vinyl siloxane. Also, electron beams can be used instead of UV light. Electron beams have stronger energy than UV light, making it possible to carry out a radical-based crosslinking reaction without using an initiator as in UV curing. Examples of resins that can be used include UV-curable silicones manufactured by Shin-Etsu Chemical Co., Ltd. (X62-7028A / B, X62-7052, X62-7205, X62-7622, ​​X62-7629, X62-7660, etc.), UV-curable silicones manufactured by Momentive Performance Materials (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.), and UV-curable silicones manufactured by Arakawa Chemical Industries, Ltd. (SilicoLease UV POLY200, POLY215, POLY201, KF-UV265AM, etc.).

[0032] It is also preferable to use polydimethylsiloxane-modified resins such as acrylic resins, polyester resins, and urethane resins having polydimethylsiloxane in the side chain. Polydimethylsiloxane-modified resins are more compatible with urethane acrylates than other common release agents, allowing for the formation of a uniform release layer, thereby improving releasability. Examples of commercially available acrylic resins having a polydimethylsiloxane skeleton in the side chain include SIMAC (registered trademark) US350 and SIMAC (registered trademark) US352 (manufactured by Toa Gosei Co., Ltd.), 8BS-9000 (manufactured by Taisei Fine Chemical Co., Ltd.), GL-01, and GL-02R (manufactured by Kyoeisha Chemical Co., Ltd.). Examples of commercially available acrylic resins having a polydimethylsiloxane skeleton and an acryloyl group in the side chain include 8SS-723 (manufactured by Taisei Fine Chemical Co., Ltd.), GL-03, and GL-04R (manufactured by Kyoeisha Chemical Co., Ltd.).

[0033] The coating liquid for forming the release layer is prepared by adding, for example, a silicone resin as a release agent and a catalyst to a solvent. Examples of solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; fatty acid hydrocarbons such as cyclohexane, n-hexane, and n-heptane; halogenated hydrocarbons such as perchloroethylene; ethyl acetate; and methyl ethyl ketone. When applying the coating directly onto the antistatic layer, a mixed solvent of toluene, methyl ethyl ketone, and n-heptane is more preferred because of the high hydrophilicity of the antistatic layer. To prevent voids and haze after coating, the volumetric mixing ratio of toluene / methyl ethyl ketone / n-heptane is preferably 25-45% by volume / 25-45% by volume / 10-50% by volume. The coating liquid is then applied onto the substrate film.

[0034] When the above resins are used in the release layer of the present invention, they may be used alone or in combination of two or more. In addition, in order to adjust the release force, it is also possible to mix additives such as light release additives and heavy release additives.

[0035] The content of the release agent is 0.5 to 20 parts by mass, and preferably 1 to 10 parts by mass, per 100 parts by mass of the release layer coating liquid.

[0036] In the present invention, the method for forming the antistatic layer is not particularly limited, and a method is used in which a coating liquid containing an antistatic agent dissolved therein is spread on one side of a substrate film by coating or the like, the solvent is removed by drying, and then the resulting film is dried by heating, heat-cured, or ultraviolet-cured. The drying temperature during solvent drying and heat-curing is preferably 180°C or less, more preferably 160°C or less, and most preferably 140°C or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and even more preferably 10 seconds or less. A temperature of 180°C or less maintains the flatness of the film, and is therefore preferred as it reduces the risk of thickness unevenness in the antistatic layer. A temperature of 140°C or less is particularly preferred as it allows processing without impairing the flatness of the film and further reduces the risk of thickness unevenness in the antistatic layer.

[0037] As a method for applying the coating liquid, any known coating method can be applied, and conventionally known methods such as roll coating methods such as gravure coating and reverse coating, bar coating methods such as wire bar coating, die coating, spray coating, and air knife coating can be used.

[0038] In the present invention, the method for forming the release layer is not particularly limited, and a method is used in which a coating liquid in which a release resin is dissolved or dispersed is spread on one side of a polyester film substrate by coating or the like, the solvent is removed by drying, and then the resulting mixture is dried by heating, heat curing, or ultraviolet curing. In this case, the drying temperature during solvent drying and heat curing is preferably 180°C or less, more preferably 160°C or less, and most preferably 140°C or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and even more preferably 10 seconds or less. When the temperature is 180°C or less, the flatness of the film is maintained and there is little risk of uneven thickness of the release layer, which is preferable. When the temperature is 140°C or less, the film can be processed without impairing the flatness of the film, and there is a further reduction in the risk of uneven thickness of the release layer, which is particularly preferable.

[0039] In the present invention, the coating liquid used to coat the release layer is not particularly limited, but it is preferable to add a solvent having a boiling point of 70° C. or higher. Adding a solvent having a boiling point of 70° C. or higher can prevent bumping during drying, level the coating film, and improve the flatness of the coating film surface after drying. The solvent having a boiling point of 70° C. or higher is preferably contained in an amount of about 50 to 99% by mass relative to the entire coating liquid.

[0040] As a method for applying the coating liquid, any known coating method can be applied, and conventionally known methods such as roll coating methods such as gravure coating and reverse coating, bar coating methods such as wire bar coating, die coating, spray coating, and air knife coating can be used.

[0041] In the present invention, when forming the release layer, ultraviolet irradiation may be performed depending on the type of silicone resin. The amount of ultraviolet irradiation may be an amount that allows the silicone resin to harden, and is usually performed using a high-pressure mercury lamp or an electrodeless lamp (e.g., H-bulb manufactured by Fusion Co., Ltd.) with an irradiation energy per unit area of ​​1 mJ / cm. ２ More than 1000mJ / cm ２ or less, preferably 10 mJ / cm ２ More than 500mJ / cm ２ If the irradiation energy is too low, the silicone resin will not cure well, and problems such as offset will likely occur. On the other hand, if the irradiation energy is too high, the heat from irradiation will cause problems with the flatness of the film, which is undesirable.

[0042] The release film of the present invention may be prepared by laminating, for example, a photosensitive resin layer, a resin sheet, or a resin film on a release layer.

[0043] (Resin Sheet and Photosensitive Resin Layer) In one aspect, the present invention relates to a release film or the like used in the medical field or industrial field, for example, in the manufacturing process of electronic components or electronic substrates, or in the manufacturing process of thermosetting resin members such as fiber-reinforced plastics. More specifically, the present invention relates to the following. The release film is useful for release films, release liners, and separators such as surface protection films and adhesive tapes, separators for tapes used in processes (dicing, die bonding, back grinding) used in the manufacture of semiconductor products, carriers for forming unfired sheets when manufacturing ceramic capacitors, and separators for carriers and protective materials when manufacturing composite materials. In particular, the release film is used as an optical film or a film for manufacturing electronic components. The resin sheet formed on the release film is not particularly limited, and examples thereof include vinyl resin, acrylic resin, epoxy resin, polyester resin, styrene resin, fluororesin, amino resin, and phenolic resin. Furthermore, the release film of the present invention can be used in the manufacture of, for example, printed wiring boards, semiconductor packages, flexible substrates, etc., by laminating a photosensitive resin layer onto the release layer, and is also useful in the manufacture of these products.

[0044] Resin sheets formed using the above resins alone have poor slip properties, which can lead to poor handleability, reduced yield, and potential blocking. To avoid these issues, particles or waxes are added as slip imparting agents. However, when particles are added, the particles may aggregate to form large protrusions, potentially damaging the resin sheet. Furthermore, if transparency is required for the resin sheet, the particle aggregation can increase haze and cause a loss of transparency. Furthermore, when wax is added, when the resin sheet is used for electronic components, the wax may transfer to the electronic components, contaminating them and causing malfunctions. The present invention can impart slip properties to resin sheets without using particles or wax, thereby alleviating the above problems. The resin components forming the resin sheet can be appropriately selected depending on the application. In one aspect, the present invention provides a method for producing a resin sheet using the release film for resin sheet molding according to the present invention. For example, the method for producing a resin sheet includes treating a resin sheet at a drying temperature of 50°C or higher and 120°C or lower, for example, a drying temperature of 60°C or higher and 100°C or lower, with the drying time being preferably 30 seconds or shorter, and more preferably 20 seconds or shorter. In one embodiment, the resin sheet can be laminated on a release film for resin sheet molding, and the surface of the resin sheet facing the release layer has a shape transferred from the release surface of the release film.

[0045] This application claims the benefit of priority based on Japanese Patent Application No. 2024-050119, filed on March 26, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-050119, filed on March 26, 2024, are incorporated herein by reference.

[0046] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The property values ​​used in the present invention were evaluated using the following methods.

[0047] <Evaluation>

[0048] (1) Peel Strength An adhesive tape ("31B" manufactured by Nitto Denko Corporation) was attached to the surface of a release film, pressed with a pressure roller at a linear pressure of 5 kgf / mm, and then left for 20 hours under conditions of a temperature of 22°C and a humidity of 60%. The release film with the adhesive tape attached was cut into a strip of 25 mm wide and 150 mm long. One end of the adhesive tape was fixed, one end of the release film was supported, and the release film side was pulled at a speed of 300 mm / min to measure the T-peel strength. A tensile tester ("AUTOGRAPHAG-A-1" manufactured by Shimadzu Corporation) was used for the measurement. The results are shown in Table 1. The results in the table were calculated by converting the film width to 50 mm.

[0049] (2) Antistatic property (surface resistivity) The film was cut into a size of 5 cm x 10 cm and seasoned for 24 hours under environmental conditions of a temperature of 23 ° C. and a humidity of 65% RH. Thereafter, the antistatic property of the release layer surface of the release film was measured using a surface resistivity meter (surface resistivity meter, manufactured by Mitsubishi Yuka Co., Ltd.) under environmental conditions of an applied voltage of 500 V, a temperature of 23 ° C., and a humidity of 65% RH, and the surface resistivity (Ω / □) was expressed in logarithm (log (Ω / □)). The measured value was the average value of 5 points.

[0050] (3) Dynamic Friction Coefficient The dynamic friction coefficient of the release film was measured in accordance with JIS K 7125. However, the load cell and the sample were directly connected without using a spring, the mass of the sliding piece was 4.4 kgf, and the test speed was 200 mm / min. Three measurements were taken for each sample, and the average value was used as the dynamic friction coefficient.

[0051] (4) Area surface average roughness (Sa) This value was measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100). The average value of five measurements was used for the area surface average roughness (Sa) of the release film. (Measurement conditions) Measurement mode: WAVE mode Objective lens: 50x magnification 0.5x Tube lens Measurement area: 187 x 139 μm

[0052] (5) Haze The haze of the release film was measured using a haze meter (NDH7000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7105. The measured value was the average value of 10 points.

[0053] (6) Light transmittance at a wavelength of 365 nm Using a spectrophotometer (Shimadzu Corporation, UV-3600iPlus), the light transmittance of the release film in the wavelength range of 300 to 500 nm was measured using the air layer as the standard, and the light transmittance at a wavelength of 365 nm was determined. The light transmittance of the release film was measured by irradiating light from the release layer side toward the base layer.

[0054] (7) Number of internal foreign particles Observation was carried out using a 20x lens of a confocal microscope (OPTELICS HYBRID C3, manufactured by Lasertec Corporation). After focusing on the surface of the base layer of the release film, the stage was moved upward, and the major diameter of the foreign particles in focus was measured as an internal foreign particle. This operation was repeated until the focus was on the bottom surface (the surface opposite to the above surface) of the base layer of the release film, and the number of foreign particles with a major diameter of 3 μm or more was counted. The measurement was carried out three times, and the total number of particles with a major diameter of 3 μm or more was subtracted by 1 mm. ２ The number of foreign particles per unit area was calculated. (Measurement conditions) Objective lens: 20x Measurement area: 700 μm × 750 μm

[0055] (8) Film Thickness The cut-out release film was embedded in resin and cut into ultrathin sections using an ultramicrotome. Then, using a JEOL JEM2100 transmission electron microscope at a magnification of 20,000 times, the film thickness of each layer of the laminate film was measured from the observed TEM image.

[0056] (Example 1) (Preparation of Antistatic Layer Coating Liquid 1) The following materials were mixed to prepare Antistatic Layer Coating Liquid 1. (Antistatic Layer Coating Liquid 1) Isopropanol 60 parts by mass Antistatic agent 40 parts by mass (Colcoat N103X, manufactured by Colcoat Co., Ltd., solid content concentration 2% by mass)

[0057] (Preparation of Release Layer Coating Liquid 1) The following materials were mixed to prepare release layer coating liquid 1. (Release Layer Coating Liquid 1) n-heptane 20.00 parts by mass Toluene 25.86 parts by mass Methyl ethyl ketone 49.00 parts by mass Release agent 2.00 parts by mass (Silicone LTC310 manufactured by Dow-Toray, solid content 30% by mass) Catalyst 0.03 parts by mass (SRX212 manufactured by Dow-Toray, solid content 50% by mass)

[0058] (Production of Release Film) (Formation of Antistatic Layer) Antistatic layer coating liquid 1 was applied to one side of a polyethylene terephthalate film (Cosmoshine A4360, manufactured by Toyobo Co., Ltd., thickness: 38 μm) using a gravure coater, and then dried at 130 ° C. for 30 seconds to form an antistatic layer with a thickness of 20 nm. (Formation of Release Layer) Subsequently, release layer coating liquid 1 was applied to the surface of the antistatic layer using a gravure coater, and then dried at 120 ° C. for 30 seconds to form a release layer with a thickness of 20 nm, and a release film was obtained. The evaluation results of the obtained release film are shown in Table 1.

[0059] Examples 2 to 5 Release films were prepared in the same manner as in Example 1, except that the thicknesses of the antistatic layer and the release layer were changed to those shown in Table 1.

[0060] Example 6 A release film was produced in the same manner as in Example 1, except that the antistatic layer coating solution 1 was changed to the following antistatic layer coating solution 2. (Antistatic layer coating solution 2) Isopropanol 60 parts by mass Antistatic agent 40 parts by mass (Orgacon ICP1010 manufactured by Agfa-Gevaert, solid content 1.2% by mass)

[0061] Comparative Examples 1 to 4 Release films were prepared in the same manner as in Example 1, except that the thicknesses of the antistatic layer and the release layer were changed to those shown in Table 1.

[0062] Table 1 summarizes the evaluation results for each example and comparative example.

[0063]

[0064] The release films described in the examples have excellent releasability, antistatic properties, and smoothness, and can be suitably used as supports for forming photosensitive resins. Photosensitive resin films using the release film for forming photosensitive resins of the present invention as a support exhibit excellent resolution of the resin layer, pattern formability on the surface and edges, and moderate adhesion of the resin layer. Furthermore, when using the release film of the present invention as a support to produce a photosensitive resin film, they also exhibit excellent blocking resistance and easy slippage. On the other hand, in Comparative Example 1, the thickness of the antistatic layer was thinner than the range of the present invention, resulting in a high surface resistance value. Furthermore, the dynamic friction coefficient was about half that of the Examples, showing a tendency to be significantly lower. Therefore, it was insufficient as a support for forming photosensitive resins. In Comparative Example 2, the thickness of the antistatic layer was thicker than the range of the present invention, showing a tendency to have a high dynamic friction coefficient. Therefore, it was insufficient as a support for forming photosensitive resins. In Comparative Example 3, the thickness of the release layer was thinner than the range of the present invention, resulting in a significantly higher peel force than in the Examples, while the dynamic friction coefficient was about half that of the Examples, showing a tendency to be significantly lower. Therefore, it was insufficient as a support for forming a photosensitive resin. In Comparative Example 4, the thickness of the release layer was thicker than the range of the present invention, and the dynamic friction coefficient tended to be significantly higher than in the Examples. Therefore, it was insufficient as a support for forming a photosensitive resin.

[0065] It was also confirmed that when an ultraviolet-curable silicone resin or an acrylic resin having a polydimethylsiloxane skeleton in the side chain was used, a good balance of releasability, antistatic properties, and good slip properties was achieved.

[0066] In this way, by satisfying the various features of the present invention, it is possible to achieve a good balance between releasability, antistatic properties and good slip properties.

[0067] The release film of the present invention has excellent releasability, antistatic properties, and smoothness, and can be suitably used as a support for forming a photosensitive resin. A photosensitive resin film using the release film for forming a photosensitive resin of the present invention as a support is excellent in the resolution of the resin layer, the pattern formability of the surface and edges, and the appropriate adhesion of the resin layer. Furthermore, when a photosensitive resin film is produced using the release film of the present invention as a support, the film is also excellent in blocking resistance and easy slippage. Furthermore, the technical concept of the present invention can be applied to other industrial films, such as base films for optical functional films that require high transparency, and this will make a great contribution to the industry.

Claims

1. A release film having a base layer, an antistatic layer, and a release layer in this order, wherein the release layer has a surface average roughness (Sa) of 10 nm or less, the surface of the base layer opposite to the surface having the antistatic layer has a surface average roughness (Sa) of 10 nm or less, the antistatic layer has a thickness of 7 to 60 nm, the release layer has a thickness of 50 nm or less, and the release layer contains a silicone-based release agent.

2. The release film according to claim 1, which has a haze of 1.5% or less.

3. The release film according to claim 1, which has a light transmittance of 85% or more at a wavelength of 365 nm.

4. The number of internal foreign particles of 3 μm or larger contained in the base material layer is 50 / mm ２ The release film according to claim 1, wherein:

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