Laminated film and method for producing the same

Abstract

To provide a laminate film capable of providing a resin sheet having high smoothness and good slipperiness.SOLUTION: A laminate film includes a polyester-based substrate film, a release layer placed on at least one surface of the substrate film, and a resin sheet placed on the release layer on a surface on the opposite side of the substrate and satisfies the following conditions: the resin sheet is obtained by curing a resin sheet-forming composition involving at least a resin component (A) and a cross-linking agent (B); the resin sheet is substantially free from a particle; a film thickness (t1) of the resin sheet is 1 μm or over and 20 μm or under; a maximum cross-sectional height (St) of a surface (1) of the resin sheet is 80 nm or over and 1000 nm or under; and a coefficient of static friction measured by laminating a surface (1) of the resin sheet on the opposite side of the release layer surface and a surface (2) of the resin sheet on the release layer side is 1.5 or under. The laminate film is used in an electronic component application and an optical component application.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated film having a resin sheet laminated thereon, and more particularly to a laminated film having a resin sheet laminated thereon that is used for electronic components and optical applications. [Background technology]

[0002] Conventionally, release films based on polyester film have high heat resistance and mechanical properties and have been used as process films used in solution casting of resin sheets such as pressure-sensitive adhesive sheets, cover films, polymer electrolyte membranes, and dielectric resin sheets. In recent years, high smoothness and transparency are required for resin sheets used in electronic components and optical applications, particularly dielectric resin sheets used in film capacitors, and therefore high smoothness has also been required for the surface of release films used as process films. For this reason, technologies such as those described in Patent Documents 1 to 3 have been disclosed, and release layer surfaces with low surface roughness have been proposed.

[0003] However, for example, while high smoothness is required for optical applications to improve transparency, too much smoothness can also result in poor slippage, which can lead to scratches during transportation and other processes, resulting in reduced yields. Also, for electronic component applications such as film capacitors, smoothness is required to improve electrical properties such as breakdown voltage, but too much smoothness can result in poor slippage, which can lead to misalignment and wrinkles when the dielectric resin sheet is wound onto a roll, making it difficult to wind properly and reducing the performance of the film capacitor.

[0004] To improve these problems, Patent Document 4 proposes adding specific particles to resin sheets used for optical purposes such as polarizing plates to impart slipperiness. Also, Patent Document 5 proposes a method of transferring particles on a substrate film to a resin sheet used for film capacitors and the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-144021 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-154273 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-182261 [Patent Document 4] Japanese Patent Application Publication No. 2019-95661 [Patent Document 5] International Publication No. 2020 / 039638 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the method of Patent Document 4, since particles are contained in the resin sheet, there is a concern that the transparency may be insufficient, such as an increase in internal haze, etc. Also, in the method of Patent Document 5, there is a concern that the amount of particles transferred to the resin sheet may be uneven, which may result in unstable slip properties. The present invention is intended to solve the above problems, and proposes a laminated film that can provide a resin sheet that has both high smoothness and good slip properties without substantially adding particles to the interior of the resin sheet. [Means for solving the problem]

[0007] As a result of extensive research, the inventors discovered that by applying a coating liquid containing at least a specific resin and a crosslinking agent under specific conditions onto a smooth substrate film, followed by drying and curing, unevenness resulting from a phase separation structure can be formed on the surface of the laminated film, and they have succeeded in providing good slip properties without the inclusion of particles, etc.

[0008] That is, the present invention comprises the following: [1] A polyester-based substrate film, a release layer disposed on at least one side of the substrate film, and a resin sheet disposed on the surface of the release layer opposite the substrate, Laminated film that satisfies the following (1) to (6): (1) The resin sheet is a resin sheet-forming composition containing at least a resin component (A) and a crosslinking agent (B). The composition is hardened, (2) The resin sheet is substantially particle-free; (3) The thickness (t1) of the resin sheet is 1 μm or more and 20 μm or less, (4) The arithmetic mean height (Sa) of the surface (1) of the resin sheet is 2 nm or more and 30 nm or less, (5) The maximum cross-sectional height (St) of the surface (1) of the resin sheet is 80 nm or more and 1000 nm or less, (6) The static friction coefficient measured by overlapping the surface (1) of the resin sheet opposite to the release layer surface and the surface (2) of the resin sheet on the release layer side is 1.5 or less. [2] In one embodiment, the crosslinking agent (B) contained in the resin sheet-forming composition is liquid at 30°C. [3] In one embodiment, the proportion of the crosslinking agent (B) contained in the resin sheet relative to the entire resin sheet is 10% by mass or more. [4] In one embodiment, the weight average molecular weight of the resin component (A) contained in the resin sheet is 10,000 or more. [5] In one embodiment, the surface free energy of the release layer surface is 40 mJ / m 2 and the adhesion energy is 3.5 mJ / m 2 That's all. [6] In one embodiment, the arithmetic mean height (Sa) of the release layer side surface of the substrate film is 20 nm or less, and the maximum protrusion height (P) is 500 nm or less. [7] In another embodiment, the present invention provides a method for producing any of the laminated films described above, the method comprising coating and molding a resin sheet onto a substrate film by a solution casting method. [Effects of the Invention]

[0009] By using the laminated film of the present invention, a resin sheet having both high smoothness and good slip properties can be provided, and by using the resin sheet formed by the present invention, good products can be provided for various applications. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of the present invention. [Figure 2] 1 is a schematic cross-sectional view illustrating a configuration of the present invention in one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] As shown in Figure 1, the laminate film of the present invention is a laminate film having a polyester-based base film 10, a release layer 11 arranged on at least one side of the base film 10, and a resin sheet 12 arranged on the side of the release layer 11 opposite the base film 10.

[0012] The present invention can provide a resin sheet that can enhance transparency and other properties in optical applications, and also exhibits high smoothness. High smoothness and high slipperiness can be achieved at the same time, and for example, scratches during the transport process can be suppressed, and a decrease in yield can be avoided. Furthermore, for example, in electronic component applications such as film capacitors, a resin sheet exhibiting high smoothness can be provided, and the resin sheet can improve electrical properties such as dielectric breakdown voltage. Furthermore, it is possible to achieve both high smoothness and high slipperiness, which was previously difficult, and for example, when winding the dielectric resin sheet onto a roll, it is possible to suppress slippage and the introduction of wrinkles, It can be easily wound up, allowing it to be transported while maintaining its excellent capacitor performance. Furthermore, the resin sheet of the present invention is substantially free of particles, and can avoid insufficient transparency such as increased internal haze, etc. Also, the problem of unevenness in the amount of particles transferred to the resin sheet can be avoided, and good slip properties can be exhibited.

[0013] (Base film) The present invention has a polyester-based substrate film. The polyester constituting the polyester film used as the substrate of the present invention is not particularly limited, and a film formed from a polyester commonly used for substrate films can be used. A crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component is preferred, and more preferred examples include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, and copolymers containing these resin components as the main component. In particular, a polyester film formed from polyethylene terephthalate is particularly preferred. The polyethylene terephthalate preferably contains 90 mol % or more, more preferably 95 mol % or more, of ethylene terephthalate repeating units, and may contain small amounts of other dicarboxylic acid components or diol components copolymerized therein. From the viewpoint of cost, polyethylene terephthalate produced from terephthalic acid and ethylene glycol alone is preferred. Furthermore, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, and crystallizing agents may be added within a range that does not impair the effects of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film due to its high bidirectional elastic modulus.

[0014] The intrinsic viscosity of the polyethylene terephthalate film is preferably 0.50 to 0.70 dL / g, more preferably 0.52 to 0.62 dL / g. When the intrinsic viscosity is 0.50 dL / g or more, breakage does not occur frequently during the stretching process, which is preferable. Conversely, when the intrinsic viscosity is 0.70 dL / g or less, cuttability is good when cutting to a predetermined product width, and dimensional defects do not occur, which is preferable. In addition, it is preferable to thoroughly vacuum dry the raw material pellets.

[0015] The method for producing the polyester film of the present invention is not particularly limited, and any conventionally commonly used method can be used. For example, the polyester can be melted in an extruder, extruded into a film, and cooled on a rotating cooling drum to obtain an unstretched film, which can then be stretched. Biaxial stretching is preferred in terms of mechanical properties, etc. A biaxially stretched film can be obtained by sequentially biaxially stretching a uniaxially stretched film in the longitudinal or transverse direction in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions.

[0016] In the present invention, the stretching temperature during stretching of the polyester film is preferably equal to or higher than the second-order transition point (Tg) of the polyester, and the stretching is preferably 1 to 8 times, particularly 2 to 6 times, in both the longitudinal and transverse directions.

[0017] The polyester film preferably has a thickness of 6 μm or more and 50 μm or less, more preferably 8 μm or more and 31 μm or less, and even more preferably 10 μm or more and 28 μm or less. A film thickness of 6 μm or more is preferable because there is no risk of deformation due to heat during film production, during the processing step of the release layer, during molding of the resin sheet, etc. On the other hand, a film thickness of 50 μm or less is preferable because the winding diameter when wound into a roll is small and the winding length of the resin sheet to be molded can be long. When the polyester film used as the base film has a multilayer structure as described below, the thickness of the entire base film falls within the above range.

[0018] The polyester film may be a single layer or a multilayer film of two or more layers. It is preferable that at least one surface of the polyester film is provided with a surface layer A that is substantially free of particles. In one embodiment, the polyester film serving as the substrate film has the surface layer A on the surface facing the resin sheet. When the substrate film is a laminated polyester film having a multilayer structure of two or more layers, it is preferable that the surface layer B that can contain particles or the like is provided on the surface opposite the surface layer A that is substantially free of particles. As for the layer structure, when the layer on the side where the resin sheet is placed is the surface layer A, the layer on the opposite side is the surface layer B, and the other core layer is the layer C, the layer structure in the thickness direction may be a layer structure such as A / B or A / C / B. Layer C may be composed of multiple layers. Surface layer B may not contain particles. In this case, it is preferable to provide a coating layer containing particles and a binder on surface layer B to impart slip properties for winding the film into a roll.

[0019] In the polyester film of the present invention, the surface layer A located on the surface on which the resin sheet is formed preferably contains substantially no particles. The arithmetic mean height (Sa) of the surface layer A of the polyester film, i.e., the arithmetic mean height (Sa) of the surface on the release layer side of the base film, is preferably 20 nm or less. Furthermore, the arithmetic mean height (Sa) is particularly preferably 10 nm or less. When Sa is 20 nm or less, pinholes and local thickness variations are less likely to occur during the molding of the resin sheet, which is preferable. The smaller the arithmetic mean height (Sa) of the surface layer A, the more preferable it is, but it may be 0.1 nm or more. Here, when a release layer, etc., described below, is provided on the surface layer A, it is preferable that the release layer contains substantially no particles, and the arithmetic mean height (Sa) after lamination of the release layer is preferably within the above range. In the present invention, "substantially no particles" means, for example, in the case of inorganic particles, that the content of inorganic elements is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit, when quantified by fluorescent X-ray analysis. This is because even if particles are not actively added to the film, contaminants from foreign matter or dirt adhering to the raw resin or the lines and equipment used in the film manufacturing process may peel off and become mixed into the film.

[0020] The maximum protrusion height (P) of the surface layer A of the polyester film, i.e., the maximum protrusion height (P) of the release layer side surface of the base film, is, for example, 500 nm or less, preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, for example, 85 nm or less, particularly preferably 50 nm or less. If the maximum protrusion height (P) is 500 nm or less, defects such as pinholes and local thinning do not occur during resin sheet formation, and the yield is favorable, which is preferable. It can be said that the smaller P of the surface layer A of the polyester film is the better, but it may be 1 nm or more, or 3 nm or more. Here, when a release layer or the like described below is provided on the surface layer A, it is preferable that the maximum protrusion height (P) after lamination of the release layer falls within the above range.

[0021] In the polyester film of the present invention, surface layer B, which forms the surface opposite surface layer A, preferably contains particles from the viewpoint of the film's slipperiness and ease of air escape, and silica particles and / or calcium carbonate particles are particularly preferred. The particle content is preferably 5,000 to 15,000 ppm in total in surface layer B. In this case, the arithmetic mean height (Sa) of the film in surface layer B is preferably in the range of 1 to 40 nm, more preferably 5 to 35 nm. When the total content of silica particles and / or calcium carbonate particles is 5,000 ppm or more and Sa is 1 nm or more, air can be uniformly released when the film is wound into a roll, resulting in a good wound shape and good flatness, making it suitable for the production of resin sheets. Furthermore, when the total content of silica particles and / or calcium carbonate particles is 15,000 ppm or less and Sa is 40 nm or less, the lubricant is less likely to aggregate and large protrusions are not formed, resulting in stable quality during resin sheet molding, which is preferred.

[0022] In addition to silica and / or calcium carbonate, the particles contained in the surface layer B may also include inert inorganic particles and / or heat-resistant organic particles. From the standpoint of transparency and cost, it is more preferable to use silica particles and / or calcium carbonate particles. Other inorganic particles that can be used include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferred. When calcium carbonate particles are used, light calcium carbonate that has been surface-treated with a polyacrylic acid-based polymer compound is preferred from the standpoint of preventing the lubricant from falling off.

[0023] The average particle size of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 1.0 μm or less. An average particle size of 0.1 μm or more is preferable because the slipperiness of the substrate film is good. Furthermore, an average particle size of 2.0 μm or less is preferable because there is no risk of pinholes being generated in the resin sheet due to coarse particles in the surface layer B.

[0024] The surface layer B may contain two or more types of particles made of different materials, or may contain particles of the same type but with different average particle sizes.

[0025] When surface layer B does not contain particles, it is preferable to provide easy slippage by a coating layer containing particles on surface layer B. This coating layer is not particularly limited, but is preferably provided by in-line coating, in which coating is performed during the production of the polyester film. When surface layer B does not contain particles but has a coating layer containing particles on surface layer B, the surface of the coating layer preferably has an arithmetic mean height (Sa) in the range of 1 to 40 nm, for the same reasons as for the arithmetic mean height (Sa) of surface layer B described above. It is more preferably in the range of 5 to 35 nm.

[0026] From the viewpoint of reducing pinholes, it is preferable that recycled raw materials or the like are not used for the surface layer A, which is the layer on which the resin sheet is provided, in order to prevent particles such as lubricants from being mixed in.

[0027] The thickness ratio of the surface layer A, which is the layer on which the resin sheet is provided, is preferably 20% to 50% of the total thickness of the base film. If it is 20% or more, the film is less likely to be affected from the inside by particles contained in the surface layer B, etc., and it is easy to ensure that the arithmetic mean height (Sa) satisfies the above range, which is preferable. If it is 50% or less of the total thickness of the base film, the proportion of recycled materials used in the surface layer B can be increased, which is preferable because it reduces the environmental impact.

[0028] From an economical standpoint, recycled raw materials such as film scraps and PET bottles can be used in an amount of 50 to 90% by mass for the layers (surface layer B or the aforementioned intermediate layer C) other than the surface layer A. Even in this case, it is preferable that the type and amount of the lubricant contained in the surface layer B, as well as the particle size and arithmetic mean height (Sa) thereof, satisfy the above ranges.

[0029] Furthermore, in order to improve the adhesion of a release layer or the like to be applied later, to prevent static electricity, or the like, a coating layer may be provided on the surface of surface layer A and / or surface layer B before stretching or after uniaxial stretching in the film-forming process, and corona treatment or the like may also be performed. When a coating layer is provided on surface layer A, it is preferable that the coating layer does not substantially contain particles.

[0030] (Release layer) The present invention has a release layer disposed on at least one side of a substrate film, for example, between the substrate film and a resin sheet. The resin constituting the release layer is not particularly limited, and silicone resins, fluororesins, alkyd resins, various waxes, aliphatic olefins, etc. can be used, and each resin can be used alone or in combination of two or more types. When a crosslinking agent is contained in the resin sheet described below, it is preferable to contain a silicone resin because this improves releasability. In this specification, the substrate and release layer laminate may be simply referred to as a release film.

[0031] The release layer can contain, for example, a silicone resin. Silicone resins are resins having a silicone structure within the molecule, and examples 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. More preferably, low-temperature curable addition reaction-based resins that can be processed at low temperatures, and ultraviolet or electron beam curable resins are preferred. By using these resins, processing can be performed at low temperatures 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.

[0032] Examples of silicone resins that use addition reactions include those that are cured by reacting polydimethylsiloxane, which has vinyl groups at 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; and solvent addition + UV-cure types (X62-5040, X62-5065, X62-5072T, KS5508, etc.) and dual-cure types (X62-2835, X62-2834, X62-1980, etc.) manufactured by Shin-Etsu Chemical.

[0033] An example of a condensation reaction silicone resin is one in which a polydimethylsiloxane having an OH group at its terminal and a polydimethylsiloxane having an H group at its terminal are subjected to a condensation reaction using an organotin catalyst to form a three-dimensional crosslinked structure.

[0034] 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. (Silicolyse UV POLY200, POLY215, POLY201, KF-UV265AM, etc.).

[0035] The UV-curable silicone resin may be an acrylate-modified or glycidoxy-modified polydimethylsiloxane, etc. Good release properties can also be achieved by mixing such modified polydimethylsiloxane with a polyfunctional acrylate resin or epoxy resin, etc., and using the mixture in the presence of an initiator.

[0036] Other suitable examples of resins that can be used include stearyl-modified or lauryl-modified alkyd resins or acrylic resins, or alkyd-based resins, acrylic-based resins, and olefin-based resins obtained by reaction of methylated melamine.

[0037] Examples of the amino alkyd resin obtained by a reaction such as with methylated melamine include Tesfine 303, Tesfine 305, and Tesfine 314 manufactured by Hitachi Chemical Co., Ltd. Examples of the amino acrylic resin obtained by a reaction such as with methylated melamine include Tesfine 322 manufactured by Hitachi Chemical Co., Ltd.

[0038] 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, additives such as light release additives and heavy release additives may be added to adjust the release force.

[0039] The release layer of the present invention may contain additives such as an adhesion improver and an antistatic agent. In order to improve adhesion to the substrate, it is also preferable to subject the surface of the polyester film to pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment before providing the release layer.

[0040] In the present invention, the thickness of the release layer may be set depending on the intended use and is not particularly limited, but is preferably in the range of 0.005 to 2.0 μm after curing. A release layer thickness of 0.005 μm or more is preferable because release performance is maintained. Furthermore, a release layer thickness of 2.0 μm or less is preferable because the curing time is not too long and there is no risk of uneven thickness of the resin sheet due to a decrease in the flatness of the release film. Furthermore, because the curing time is not too long, there is no risk of the resin constituting the release coating layer agglomerating and forming protrusions, which is preferable because pinhole defects in the resin sheet are less likely to occur.

[0041] The surface free energy of the release layer provided on the substrate film of the present invention is 12 mJ / m 2 More preferably, it is 18 mJ / m or more. 2 or more, 20 mJ / m 2 More preferably, 12 mJ / m or more. 2 If the thickness is more than this, repelling or the like is less likely to occur when the solution for the resin sheet is applied, which is preferable.

[0042] The surface free energy of the release layer provided on the substrate film of the present invention is 40 mJ / m 2 It is preferably 35 mJ / m or less. More preferably, it is 35 mJ / m 2 less than 30 mJ / m 2 More preferably, it is 40 mJ / m 2 If it is less than this, the molded resin sheet will have good releasability, which is preferable. In the present invention, the surface free energy means the surface free energy of at least the surface of the release layer that comes into contact with the resin sheet.

[0043] The water adhesion energy of the surface of the release layer of the present invention that comes into contact with the resin sheet is, for example, 3.0 mJ / m 2 or more, 3.5 mJ / m 2 More preferably, 4.0 mJ / m or more. 2 That's 5.5mJ / m 2 More preferably, it is 3.0 mJ / m or more. 2 This is preferable because swelling of the coated edge is suppressed when the resin sheet is coated with the solution. Suppression of swelling of the coated edge during coating suppresses edge edge formation when the laminate film is wound into a roll, improving the wound appearance and the flatness of the laminate film, which is preferable.

[0044] The water adhesion energy of the release layer surface can be improved by adding additives to the release layer or adjusting the polymer composition. For example, in the case of silicone resin, this can be improved by introducing a siloxane unit with a phenyl group on the side chain into the polydimethylsiloxane skeleton, or by adding a silicone resin with T units (trifunctional) or Q units (tetrafunctional).

[0045] In addition to the above, the water adhesion energy of the release layer surface can also be improved by changing the composition of the silicone resin. For example, an addition reaction silicone resin can be cured by heating a polydimethylsiloxane with vinyl groups introduced at the terminal or side chain and a hydrogensiloxane in the presence of a platinum catalyst. The water adhesion energy can also be changed by changing the molar amount of Si-H groups in the hydrogensiloxane relative to the molar amount of vinyl groups (Si-Vy) at the terminal. For example, the water adhesion energy tends to increase when there is a higher amount of Si-H relative to Si-Vy, and the ratio of Si-H / Si-Vi is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more.

[0046] The release layer of the present invention preferably has an arithmetic mean height (Sa) of not only the polyester substrate but also 20 nm or less. Furthermore, it is particularly preferable that the arithmetic mean height (Sa) is 10 nm or less. When Sa is 20 nm or less, pinholes and local thickness variations are less likely to occur during molding of the resin sheet, which is preferable. The smaller the arithmetic mean height (Sa) of the release layer, the better, but it may be 0.1 nm or more. The maximum protrusion height (P) of the release layer is, for example, 500 nm or less, preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, for example, 85 nm or less, particularly preferably 50 nm or less. If the maximum protrusion height (P) is 500 nm or less, defects such as pinholes and localized thinning do not occur during resin sheet formation, and the yield is favorable, which is preferable.

[0047] 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 by coating or the like on one side of the polyester film substrate, the solvent and the like are removed by drying, and then the layer is heated and dried, thermally cured, or ultraviolet cured.

[0048] Any known coating method can be used as the coating method for the release layer, and conventionally known methods such as roll coating methods such as gravure coating and reverse coating, bar coating methods such as wire bars, die coating, spray coating, and air knife coating can be used.

[0049] When a thermosetting material is used for the release layer, the drying temperature during solvent drying and heat curing is preferably 180°C or less, more preferably 160°C or less, even more preferably 140°C or less, and most preferably 120°C or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and most preferably 10 seconds or less. At 180°C or less, the flatness of the film is maintained and there is little risk of uneven thickness of the resin sheet, which is preferable. At 120°C or less, the film can be processed without impairing the flatness, and there is a further reduction in the risk of uneven thickness of the resin sheet, which is particularly preferable. The lower limit of the drying temperature is not particularly limited, but is preferably 60° C. or higher. A temperature of 60° C. or higher is preferred because a release film can be obtained without any solvent remaining in the release layer.

[0050] When a UV-curable material is used for the release layer, the drying temperature during solvent drying and heat curing is preferably 120°C or less, more preferably 100°C or less, and most preferably 90°C or less. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and most preferably 10 seconds or less. A temperature of 120°C or less is preferable because the flatness of the film is maintained and there is little risk of causing uneven thickness in the resin sheet. A temperature of 90°C or less is particularly preferable because the film can be processed without impairing the flatness and there is further less risk of causing uneven thickness in the resin sheet. The lower limit of the drying temperature is not particularly limited, but is preferably 60° C. or higher. A temperature of 60° C. or higher is preferred because a release film can be obtained without any solvent remaining in the release layer.

[0051] When a UV-curable material is used for the release layer, it is preferable to irradiate it with active energy rays after the solvent has dried to cause a curing reaction. Known techniques such as UV rays and electron beams can be used as the active energy rays, and UV rays are preferred. The cumulative amount of light when UV rays are used can be expressed as the product of illuminance and irradiation time. For example, it can be 10 to 500 mJ / cm. 2 It is preferable that the content is equal to or greater than the lower limit, because the release layer can be sufficiently cured. It is preferable that the content is equal to or less than the upper limit, because thermal damage to the film due to heat during irradiation can be suppressed and the smoothness of the surface of the release layer can be maintained.

[0052] (resin sheet) The laminated film of the present invention has a resin sheet disposed on the surface of the release layer opposite to the substrate. For example, the resin sheet to be laminated on the release film of the present invention is obtained by curing a resin sheet-forming composition containing at least a resin component (A) and a crosslinking agent (B). As a result of extensive investigation, it has been found that the resin sheet of the present invention can be produced under the specific conditions described below, for example, from the resin sheet-forming composition of the present invention, so that the resin component (A) and the crosslinking agent (B) can be cured in a phase-separated state, forming appropriate irregularities on the surface of the resin sheet, and allowing the resin sheet to exhibit slip properties without containing particles or the like.

[0053] The combined mass ratio of the resin component (A) and the crosslinking agent (B) is preferably 80 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more of the solid content of the entire resin sheet. A content of 80 mass% or more is preferable because it improves the physical properties of the resin sheet, such as strength and heat resistance.

[0054] The mass ratio of the resin component (A) to the crosslinking agent (B) is preferably (A) / (B) = 90 / 10 to 50 / 50. A blending ratio of the crosslinking agent (B) of 10% by mass or more is preferred because it increases the unevenness after phase separation and improves slipperiness. A blending ratio of the crosslinking agent (B) of 50% by mass or less is preferred because it prevents a decrease in the film strength of the resin sheet, improves sheet handleability, and prevents unreacted crosslinking agent from blocking with the back surface of the laminate film when wound up. For example, the proportion of the crosslinking agent (B) contained in the resin sheet relative to the entire resin sheet is preferably 10% by mass or more and 50% by mass or less. In one embodiment, the proportion of the crosslinking agent (B) contained in the resin sheet relative to the entire resin sheet is 10% by mass or more and less than 50% by mass, for example, 15% by mass or more and 45% by mass or less. By including the crosslinking agent (B) under these conditions, the above-mentioned effects can be more effectively achieved.

[0055] The resin component (A) is not particularly limited, and known resins can be used. For example, epoxy resins, phenoxy resins, polyester resins, urethane resins, fluorine resins, acrylic resins, olefin resins, imide resins, sulfone resins, etc. can be used, and they may be used alone or in combination of two or more. The weight-average molecular weight (Mw) of the resin component (A) used in the present invention is 10,000 or more, preferably 10,000 to 200,000, and more preferably 30,000 to 100,000. A weight-average molecular weight of 10,000 or more is preferred because the resin sheet has high strength and good handleability. A weight-average molecular weight of 200,000 or less is preferred because the solution viscosity is low during solution film formation, resulting in good productivity. The method for measuring the weight-average molecular weight (Mw) is not particularly limited, and it can be measured using GPC or the like.

[0056] The crosslinking agent (B) is not particularly limited, and known crosslinking agents can be used. For example, crosslinking agents such as isocyanate, melamine, carbodiimide, and oxazoline can be used, and they may be used alone or in combination of two or more. It is preferable that the crosslinking agent reacts with the functional group contained in the resin component (A). The crosslinking agent (B) contained in the resin sheet-forming composition is preferably liquid at 30°C. In the present invention, a liquid means that it has fluidity, for example, a viscosity of 10,000 mPa·s or less. Being liquid at 30°C is preferable because it can effectively promote phase separation from the resin component (A) during drying of the solution-cast resin sheet, making it easier to create surface irregularities in the resin sheet.

[0057] The resin sheet may contain additives other than the resin component (A) and the crosslinking agent (B) as long as the above ranges are satisfied. However, the resin sheet is substantially free of particles. The resin sheet according to the present invention is preferably free of particles, since this effectively increases the transparency of the molded resin sheet for optical applications, and improves the electrical properties of electronic components such as dielectric sheets used in film capacitors. For example, for optical applications, the resin sheet may have a haze of 2% or less. Alternatively, the haze may be 1% or less. In one embodiment, the haze of the resin sheet is 0.1% or more. For electronic components such as film capacitors, the resin sheet may have a breakdown voltage of 200 V / μm or more. Alternatively, the breakdown voltage may be 300 V / μm or more. In one embodiment, the breakdown voltage is 500 V / μm or less.

[0058] The resin sheet of the present invention can have good slip properties even if it does not substantially contain particles, due to the presence of minute irregularities on the surface caused by phase separation between the resin component (A) and the crosslinking agent (B). The static friction coefficient of the resin sheet peeled from the substrate film is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. A static friction coefficient of 1.5 or less is preferable because it provides good winding and running properties and is easy to handle when used for optical applications or electronic components. The static friction coefficient of the resin sheet may be 0.1 or more. In one embodiment, the static friction coefficient measured by overlapping the surface (1) of the resin sheet opposite the release layer, indicated by reference numeral 13, with the surface (2) of the resin sheet, indicated by reference numeral 14, is 1.5 or less. The static friction coefficient measured under the above conditions is more preferably 1.0 or less, and even more preferably 0.8 or less. Alternatively, the static friction coefficient may be 0.1 or more. In this way, since the static friction coefficient measured by overlapping both sides of the resin sheet is within the above range, the resin sheet of the present invention can achieve both high smoothness and excellent winding and running properties.

[0059] The arithmetic mean roughness (Sa) of the surface (1) of the resin sheet of the laminate film of the present invention (the surface opposite to the surface in contact with the release layer) is 2 nm or more and 30 nm or less, more preferably 2 nm or more and 20 nm or less, and even more preferably 2.5 nm or more and 15 nm or less. When it is 2 nm or more, the lubricity of the resin sheet becomes good, which is preferable. When it is 30 nm or less, there is less concern about defects such as pinholes occurring, which is preferable, even when the resin sheet is peeled from the laminate film and wound up into a roll.

[0060] The maximum cross-sectional height (St) of the surface (1) of the resin sheet of the laminate film of the present invention (the surface opposite to the surface in contact with the release layer) is 80 nm or more and 1000 nm or less, more preferably 100 nm or more and 600 nm or less, and even more preferably 150 nm or more and 500 nm or less. When it is 80 nm or more, the lubricity of the resin sheet becomes good, which is preferable. When it is 1000 nm or less, there is less concern about defects such as pinholes occurring, which is preferable, even when the resin sheet is peeled from the laminate film and only the resin sheet is wound into a roll. The maximum cross-sectional height (St) is the sum of the absolute values ​​of the maximum protrusion height (P) and the maximum valley depth (V).

[0061] The maximum protrusion height (P) of the surface (1) of the resin sheet of the laminated film of the present invention (the surface opposite to the surface in contact with the release layer) is preferably 500 nm or less, more preferably 250 nm or less, even more preferably 200 nm or less, may be 185 nm or less, for example, 150 nm or less, particularly preferably 135 nm or less, and may be, for example, 100 nm or less. It is preferable that the maximum projection height (P) is 500 nm or less, because defects such as pinholes do not occur even when the resin sheet is peeled from the laminated film and the resin sheet alone is wound into a roll. The smaller the maximum projection height P, the more preferable it is, but it may be 1 nm or more, or 3 nm or more, for example, 35 nm or more.

[0062] By setting the arithmetic mean roughness (Sa) and maximum profile height (St) of the surface (1) of the resin sheet of the laminated film of the present invention within the above-mentioned ranges, good slip properties can be obtained even on a highly smooth surface. In particular, it is preferable to control the maximum profile height (St) within the above-mentioned range.

[0063] In one embodiment, the maximum valley depth (V) of the surface (1) of the resin sheet of the laminate film is preferably 45 nm or more and 350 nm or less, for example, 45 nm or more and 300 nm or less, and preferably 45 nm or more and 250 nm or less. When the maximum valley depth (V) is within such a range, even if the maximum protrusion height (P) is in the range of 250 nm or less, it is easy to control the maximum cross-sectional height (St) within the above range, which is preferable because the slipperiness of the resin sheet can be improved.

[0064] The arithmetic mean roughness (Sa) of the surface (2) of the resin sheet of the laminate film of the present invention (the surface in contact with the release layer) is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 5 nm or less. When the surface (2) is 10 nm or less, even when the resin sheet is peeled from the laminate film and wound up into a roll, the risk of defects such as pinholes is reduced, which is preferable.

[0065] The thickness (t1) of the resin sheet of the present invention is 1 μm or more and 20 μm or less. More preferably, it is 1 μm or more and 10 μm or less, and even more preferably, it is 2 μm or more and 8 μm or less. If the thickness (t1) of the resin sheet is 1 μm or more, it is preferable because it is less likely to break after peeling from the base film and can be easily handled. If the thickness (t1) of the resin sheet is 20 μm or less, it is preferable because the wet coating film thickness does not become too thick during solution casting and molding is easy.

[0066] The thickness (t1) of the resin sheet is not particularly limited and can be measured by a known method, such as a contact-type thickness meter or an optical interference-type thickness meter, or by observing the cross section with a scanning electron microscope or a transmission electron microscope.

[0067] The method for laminating the resin sheet of the present invention on a substrate film is preferably to form a coating liquid containing at least the above-mentioned resin component (A) and crosslinking agent (B) dissolved or dispersed in an organic solvent, water, or the like on the release layer by a solution film-forming method, and like the coating method for the release layer, the coating can be performed by a known method. For example, 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.

[0068] It is preferable to have a heating step for drying and curing the solvent after applying the coating liquid to the release layer. The heating method is not particularly limited, but the coated laminated film can be heated using hot air, infrared rays, etc. The laminated film of the present invention is preferably applied and dried by roll-to-roll, and it is particularly preferable to dry using hot air in a drying oven using a floating method or a roll support method.

[0069] The maximum temperature of the drying oven is preferably 60°C or higher and 160°C or lower, more preferably 70°C or higher and 140°C or lower, and even more preferably 70°C or higher and 130°C or lower. A temperature of 60°C or higher is preferable because there is little residual solvent in the resin sheet after drying, and there is no risk of the performance of the resin sheet (for example, electrical properties if used as a dielectric layer) decreasing. A temperature of 160°C or lower is preferable because there is no risk of wrinkles occurring in the laminated film due to heat. Furthermore, a temperature higher than 160°C may cause excessive phase separation between the resin component and the crosslinking agent in the resin sheet, which may decrease the crosslink density of the resin sheet, so a temperature of 160°C or lower is preferable.

[0070] The time from applying the coating liquid to the substrate film to placing it in the drying oven is preferably within 5 seconds, more preferably within 3 seconds, and even more preferably within 2 seconds. If it is within 5 seconds, phase separation between the resin component and the crosslinking agent in the coating liquid does not proceed too much, which is preferable because there is no risk of a decrease in the crosslink density of the resin sheet.

[0071] After applying the coating liquid to the substrate film, the time for heating at the maximum temperature in the drying oven is preferably 1 second or more, and more preferably 2 seconds or more. A time of 1 second or more is preferable because the reaction of the crosslinking agent progresses. The upper limit of the heating time is preferably 60 seconds or less, more preferably 40 seconds or less, and even more preferably 20 seconds or less. A time of 60 seconds or less is preferable because excessive segregation of the crosslinking agent on the surface of the resin sheet can be suppressed, and the performance of the resin sheet is not deteriorated.

[0072] By subjecting the resin sheet of the present invention to the above-mentioned drying conditions, phase separation between the resin component (A) and the crosslinking agent (B) can be moderately advanced, and the arithmetic mean roughness (Sa) and maximum cross-sectional height (St) of the resin sheet surface (1) can be controlled within the above-mentioned ranges, thereby enabling the resin sheet to exhibit good slip properties without adding particles to the resin sheet.

[0073] (Laminated film) The laminated film of the present invention is used after the resin sheet is peeled from the substrate film in the next step. Therefore, a peeling force of 800 mN / 25 mm width or less from the substrate film is preferred because the resin sheet can be peeled without breaking. It is more preferred to have a peeling force of 500 mN / 25 mm width or less, even more preferred to have a peeling force of 300 mN / 25 mm width or less, and even more preferred to have a peeling force of 200 mN / 25 mm width or less. The peeling force varies depending on the resin sheet to be laminated, and can be adjusted by changing the type of release layer of the substrate film. [Example]

[0074] The present invention will now be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. The evaluation methods used in the present invention are as follows.

[0075] (Arithmetic mean height (Sa), maximum protrusion height (P), maximum valley depth (V), maximum cross-sectional height (St)) The values ​​were measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Ryoka Systems Co., Ltd.). The arithmetic mean height (Sa) was calculated by averaging five measurements, while the maximum protrusion height (P) and maximum valley depth (V) were calculated by measuring seven times and using the maximum values ​​of the five measurements excluding the maximum and minimum values. The maximum cross-sectional height (St) was calculated by adding the absolute values ​​of the maximum protrusion height (P) and maximum valley depth (V). (Measurement conditions) Measurement mode: WAVE mode Objective lens: 10x 0.5x Tube Lens ·Measurement area 936μm×702μm (Analysis conditions) Surface correction: 4th order correction Interpolation: Full interpolation Filtering: Gaussian cutoff value 50μm

[0076] (surface free energy) A contact angle meter (Kyowa Interface Science Co., Ltd.: Fully Automatic Contact Angle Meter DM-701) was used to measure the contact angle of a 1.8 μL drop of water and a 0.9 μL drop of diiodomethane on the release film surface at 25°C and 50% RH. The contact angle was measured 10 seconds after each drop of water onto the release film. The contact angle data for water and diiodomethane obtained using the above method were calculated using the Owens and Wendt theory to determine the dispersion component γd of the surface free energy of the release film, and the component γh based on hydrogen bonding and dipole-dipole interactions. The sum of these components was used to determine the surface free energy γs. This calculation was performed using the analysis software within the contact angle meter software (FAMAS).

[0077] (water adhesion energy) Under conditions of 25°C and 50% RH, a contact angle meter (Kyowa Interface Science Co., Ltd.: Fully Automatic Contact Angle Meter DM-701) was used to drop water (10 μL droplets) onto the release surface of the release film, and starting 2 seconds after the drop, the stage was continuously tilted and the contact angle was measured every 1°. In addition, the tilt angle when the droplet moved 5 dots from the 0° droplet position was determined to be the sliding angle, and the adhesion energy was calculated from this. This calculation was performed using the analysis software within the contact angle meter software (FAMAS).

[0078] (film thickness) The cut-out laminated film was embedded in resin and cut into ultrathin sections using an ultramicrotome. Then, it was directly observed at a magnification of 20,000 times using a JEOL JEM2100 transmission electron microscope, and the thickness of each layer of the laminated film was measured from the observed TEM images.

[0079] (peel force) The laminated film was cut into strips 25 mm wide and 150 mm long, one end of the base film was fixed, one end of the resin sheet was supported, and the resin sheet side was pulled at a speed of 300 mm / min to measure the T-peel strength. A tensile tester (Shimadzu Corporation's "AUTOGRAPH AG-X") was used for the measurement. The measured value was the average of five measurements. The peelability was evaluated based on the measured peel force according to the following criteria. 〇: Peeling was possible with a low peeling force of 100 mN / 25 mm width or less, and even thin films could be peeled off without tearing. ◯△: Peeling was possible with a peeling force of 300 mN / 25 mm width or less, and greater than 100 mN / 25 mm width. △: Peeling was possible when the peeling force was greater than 300 mN / 25 mm width and less than 800 mN / 25 mm width. In areas where the film was extremely thin, some tearing occurred. ×: Unable to peel.

[0080] (Static friction coefficient and slipperiness evaluation) The static friction coefficient of the resin sheet was measured as follows to evaluate the slipperiness. The resin sheet was peeled from the laminated film and fixed to the bottom of a 1.4 kg metal rectangular parallelepiped so that surface (2) of the resin sheet was facing out. Next, the resin sheet was fixed to a flat metal plate with adhesive tape so that surface (1) of the resin sheet was facing out. The metal rectangular parallelepiped was placed so that surface (1) was in contact with surface (2), and the static friction coefficient was measured at a pulling rate of 200 mm / min under conditions of 23°C and 65% RH. The slipperiness was evaluated according to the following criteria. :0.1<μs≦0.8 :0.8<μs≦1.5 ×: Over 1.5 or the friction coefficient is too high to measure

[0081] (Electrical characteristics) A thin aluminum vapor-deposited layer was formed on both sides of the resin sheet peeled from the base film, and the dielectric breakdown voltage (V / μm) was measured at room temperature. The average value of 10 measurements was used and evaluated according to the following criteria. ○: Dielectric breakdown voltage (BDV value) is 300V / μm or more △: Breakdown voltage is 200V / μm or more ×: Breakdown voltage is less than 200V / μm

[0082] (Preparation of polyethylene terephthalate pellets (PET(I))) The esterification reactor used was a continuous esterification reactor consisting of a three-stage complete mixing vessel equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet. The TPA (terephthalic acid) was fed at 2 tons / h, EG (ethylene glycol) at 2 moles per mole of TPA, and antimony trioxide at a concentration that would result in 160 ppm Sb atoms in the PET produced. The resulting slurry was continuously fed into the first esterification reactor and reacted at 255°C for an average residence time of 4 hours at atmospheric pressure. Next, the reaction product in the first esterification reactor was continuously removed from the system and fed to a second esterification reactor, and EG distilled off from the first esterification reactor was fed into the second esterification reactor in an amount of 8 mass% based on the produced PET. Further, an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atoms would be 65 ppm based on the produced PET, and an EG solution containing TMPA (trimethyl phosphate) in an amount such that the P atoms would be 40 ppm based on the produced PET were added, and the reaction was carried out at atmospheric pressure for an average residence time of 1 hour at 260°C. Next, the reaction product in the second esterification reactor was continuously removed from the system and fed to a third esterification reactor, and the reaction was carried out at 39 MPa (400 kg / cm) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 2 0.2% by mass of porous colloidal silica (average particle size: 0.9 μm), which had been dispersed at a pressure of 1000 kJ / cm² for an average number of passes (5 times), and 0.4% by mass of synthetic calcium carbonate (average particle size: 0.6 μm), each containing 1% by mass of ammonium salt of polyacrylic acid per calcium carbonate, were added as 10% EG slurry and reacted at atmospheric pressure for an average residence time of 0.5 hours at 260°C. The esterification reaction product produced in the third esterification reactor was continuously fed to a three-stage continuous polycondensation reactor for polycondensation. The product was filtered through a filter made of sintered stainless steel fibers with a 95% cutoff diameter of 20 μm, then ultrafiltered and extruded into water. After cooling, the product was cut into chips to yield PET chips with an intrinsic viscosity of 0.60 dL / g (hereinafter abbreviated as PET(I)). The lubricant content in the PET chips was 0.6% by mass.

[0083] (Preparation of polyethylene terephthalate pellets (PET(II))) On the other hand, in the above-mentioned production of PET chips, PET chips containing absolutely no particles such as calcium carbonate or silica and having an intrinsic viscosity of 0.62 dl / g were obtained (hereinafter abbreviated as PET(II)).

[0084] (Preparation of polyethylene terephthalate pellets (PET(III))) PET chips were obtained in the same manner as PET(I), except that the type and content of PET(I) particles were changed to 0.75% by mass of synthetic calcium carbonate with an average particle size of 0.9 μm, to which ammonium salt of polyacrylic acid was attached at 1% by mass per calcium carbonate (hereinafter referred to as PET(III)). The lubricant content in the PET chips was 0.75% by mass.

[0085] (Production of base film X1) These PET chips were dried and then melted at 285°C. Then, the melts were melted at 290°C in separate melt extruders. The melts were then filtered through two filters: one containing sintered stainless steel fibers with a 95% cutoff diameter of 15 μm, and the other containing sintered stainless steel particles with a 95% cutoff diameter of 15 μm. The resulting mixtures were then combined in a feedblock, where PET(I) was laminated as surface layer B and PET(II) as surface layer A. The resulting laminate was extruded (cast) at a speed of 45 m / min and electrostatically bonded and cooled on a casting drum at 30°C to obtain an unstretched polyethylene terephthalate sheet with an intrinsic viscosity of 0.59 dl / g. The layer ratio was adjusted to PET(I) / PET(II) = 60% / 40% based on the extrusion rate calculations. The unstretched sheet was then heated with an infrared heater and stretched 3.5 times in the machine direction at a roll temperature of 80°C using a roll speed differential. The film was then introduced into a tenter and stretched 4.2 times in the transverse direction at 140°C. It was then heat-treated at 210°C in a heat-setting zone. It was then relaxed in the transverse direction at 170°C by 2.3%, yielding a biaxially stretched polyethylene terephthalate film substrate film X1 with a thickness of 25 μm. The surface layer A of the obtained substrate film X1 had an Sa of 2 nm, and the surface layer B had an Sa of 29 nm.

[0086] (Production of base film X2 having a release layer) The release coating solution Y1 described below was applied to the surface layer A of the base film X1 obtained above by reverse gravure coating so as to have a wet film thickness of 5 μm, and then dried and cured in a hot air drying oven at 120°C for 30 seconds to obtain a base film X2 with a release layer. The surface roughness Sa of the release layer was 2 nm. (Release coating liquid Y1) Toluene 48 parts by mass Methyl ethyl ketone 48 parts by mass Silicone resin composition (1) (Thermosetting silicone coating, Si-H / Si-Vy=3.0, solid content 30% by mass) 3 parts by mass SRX212P Catalyst (Pt-based curing catalyst manufactured by Dow-Toray) · 1 part by mass

[0087] (Production of base film X3 having a release layer) The layer structure and stretching conditions were the same as for base film X1, but the thickness was adjusted by changing the casting speed to produce a biaxially stretched polyethylene terephthalate film with a thickness of 12 μm. A release layer similar to that for X2 was then provided to obtain base film X3. The surface layer A of the resulting film X3 had an Sa of 3 nm, and the surface layer B had an Sa of 29 nm.

[0088] (Method of manufacturing base film X4 having release layer) The base film X4 used was a 25 μm-thick A4100 (Cosmoshine (registered trademark), manufactured by Toyobo Co., Ltd.) with a release layer similar to that of X2 provided on the surface layer A. A4100 does not substantially contain particles in the film, and a coating layer containing particles is provided by in-line coating only on the surface layer B side. The surface layer A of the base film X4 had an Sa of 1 nm, and the surface layer B had an Sa of 2 nm.

[0089] (Method of manufacturing base film X5 having release layer) The base film X5 used was a 25 μm-thick E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) with a release layer similar to that of X2 provided on the surface layer A. E5101 is configured so that particles are contained in the surface layers A and B of the film. The surface layer A of the base film X5 had an Sa of 25 nm, and the surface layer B had an Sa of 25 nm.

[0090] (Method of manufacturing base film X6 having release layer) The release coating solution Y2 described below was applied to the surface layer A of the base film X1 by reverse gravure coating to a wet film thickness of 5 μm, and then dried and cured in a hot air drying oven at 120°C for 30 seconds to obtain a base film X6 with a release layer. The surface roughness Sa of the release layer was 2 nm. (Release coating liquid Y2) Toluene 48 parts by mass Methyl ethyl ketone 48 parts by mass Silicone resin composition (2) (Thermosetting silicone coating, Si-H / Si-Vy=1.0, solid content 30% by mass) 3 parts by mass SRX212P Catalyst (Pt-based curing catalyst manufactured by Dow-Toray) 0.1 part by mass

[0091] (Method of manufacturing base film X7 having release layer) The release coating solution Y3 described below was applied to the surface layer A of the base film X1 by reverse gravure coating to a wet film thickness of 5 μm, and then dried and cured in a hot air drying oven at 120°C for 30 seconds to obtain a base film X7 with a release layer. The surface roughness Sa of the release layer was 2 nm. (Release coating liquid Y3) Toluene 48 parts by mass Methyl ethyl ketone 48 parts by mass Silicone resin composition (3) (Thermosetting silicone coating, Si-H / Si-Vy=2.2, solid content 30% by mass) 3 parts by mass SRX212P Catalyst (Pt-based curing catalyst manufactured by Dow-Toray) 0.1 part by mass

[0092] Example 1 Resin solution Z is applied to the surface layer A of the base film X2 using the reverse gravure coating method. The resin sheet was coated with 1 so that the thickness of the dried resin sheet would be 3 μm, and then dried in a hot air drying oven at 120°C for 10 seconds to form a resin sheet, producing a laminated film. (In this case, it took 2 seconds from coating to entering the drying oven.) Details are shown in Tables 1 and 2. (Resin solution Z1) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 22.5 parts by mass PKHB solution (solid content 40% by mass) 30.6 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MR-200 5.3 parts by mass (Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0093] (Examples 2 and 3) A laminated film was produced in the same manner as in Example 1, except that the base film was changed to one shown in Table 1.

[0094] Example 4 A laminated film was produced in the same manner as in Example 1, except that the resin component (A) was changed to resin solution Z6, which had a different weight average molecular weight (Mw). (Resin solution Z6) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 22.5 parts by mass PKHJ solution (solid content 40% by mass) 30.6 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw57000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MR-200 5.3 parts by mass (Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0095] Example 5 A laminated film was produced in the same manner as in Example 1, except that the resin solution was changed to Z2 in order to change the type of crosslinking agent. (Resin solution Z2) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 22.5 parts by mass PKHB solution (solid content 40% by mass) 30.6 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MR-400 5.3 parts by mass (Tosoh Corporation, isocyanate crosslinking agent, viscosity 600 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0096] Example 6 A laminated film was produced in the same manner as in Example 1, except that the resin solution was changed to resin solution Z3 in order to change the type of crosslinking agent. (Resin solution Z3) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 22.5 parts by mass PKHB solution (solid content 40% by mass) 30.6 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MTL 5.3 parts by weight (Tosoh Corporation, isocyanate crosslinking agent, viscosity 50 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0097] Example 7 A laminated film was produced in the same manner as in Example 1, except that resin solution Z4 was used to change the ratio of resin to crosslinking agent. (Resin solution Z4) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 19.9 parts by mass PKHB solution (solid content 40% by mass) 35.0 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MR-200 3.5 parts by mass (Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0098] Example 8 A laminated film was produced in the same manner as in Example 1, except that the resin solution was changed to resin solution Z5 in order to change the ratio of resin to crosslinking agent. (Resin solution Z5) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 17.3 parts by mass PKHB solution (solid content 40% by mass) 39.4 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MR-200 1.8 parts by mass (Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa·s, solid content 99% by mass) BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0099] Examples 9 to 11 A laminated film was produced in the same manner as in Example 1, except that the base film was changed to that shown in Table 1.

[0100] (Examples 12 to 13) A laminated film was produced in the same manner as in Example 1, except that the drying temperature for the resin sheet was changed to the temperature shown in Table 1.

[0101] (Comparative Example 1) A laminated film was produced in the same manner as in Example 1, except that the base film was changed to X1, which had no release layer.

[0102] (Comparative Example 2) A laminated film was produced in the same manner as in Example 1, except that the resin solution was changed to resin solution Z6 which did not contain a crosslinking agent. (Resin solution Z6) Methyl ethyl ketone 41.3 parts by mass Tetrahydrofuran 14.7 parts by mass PKHB solution (solid content 40% by mass) 43.8 parts by mass (Gabriel Phenoxies Phenoxy resin, Mw32000) *The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. BYK-370 0.4 parts by mass (Byk Chemie Japan, silicone surfactant)

[0103] (Comparative Example 3) A laminated film was produced in the same manner as in Example 1, except that the resin sheet was formed so that the maximum cross-sectional height (St) of the surface (1) of the resin sheet was 75 nm.

[0104] The base film used in each example was used after processing the release layer and aging for 3 days at 40° C. The obtained laminated film was also evaluated after aging for 3 days at 40° C.

[0105] [Table 1]

[0106] [Table 2]

[0107] The laminated sheet of the present invention obtained in the examples is a resin sheet that can improve transparency, for example, in optical applications, and also provides a resin sheet that exhibits high smoothness. Furthermore, it is possible to achieve both high smoothness and high slipperiness, and for example, it is possible to suppress scratches during the transport process and avoid a decrease in yield. Furthermore, for electronic component applications such as film capacitors, resin sheets exhibiting high smoothness can be provided, and the resin sheets can improve electrical properties such as breakdown voltage. Furthermore, high smoothness and high slipperiness can be achieved simultaneously, which can suppress, for example, slippage and wrinkles when winding the dielectric resin sheet onto a roll, resulting in good winding properties. Therefore, the dielectric resin sheet can be transported while maintaining its excellent capacitor performance. Furthermore, the resin sheet obtained by the present invention does not substantially contain particles, and can avoid insufficient transparency such as increased internal haze, etc. Furthermore, the problem of unevenness in the amount of particles transferred to the resin sheet can be avoided, and good slip properties can be exhibited.

[0108] In contrast, Comparative Example 1 did not have the release layer according to the present invention, and therefore the peelability of the resin sheet was extremely poor, making it impossible to evaluate the resin sheet. Comparative Example 2 showed results in which the slipperiness of the resin sheet was particularly poor, since the resin sheet-forming composition did not contain a crosslinking agent. In Comparative Example 3, the maximum cross-sectional height (St) of the surface (1) of the resin sheet was outside the range of the present invention, and therefore the results showed that the slipperiness of the resin sheet was particularly poor. [Industrial Applicability]

[0109] The present invention relates to a laminated film having a resin sheet laminated thereon, and more particularly to a laminated film having a resin sheet laminated thereon that is used for electronic components and optical applications. [Explanation of symbols]

[0110] 10 Base film 11 Release layer 12 Resin sheet 13 Surface of resin sheet (1) 14 Surface of resin sheet (2)

Claims

1. The film comprises a polyester-based base film, a release layer disposed on at least one surface of the base film, and a resin sheet disposed on the surface of the release layer opposite to the base film, Laminated film that meets the following requirements: The laminated film is used for electronic components and optical components, the resin sheet is obtained by curing a resin sheet-forming composition containing at least a resin component (A) and a crosslinking agent (B); The resin component (A) contains a phenoxy resin, the crosslinking agent (B) is an isocyanate, the resin sheet is substantially free of particles, The film thickness (t1) of the resin sheet is 1 μm or more and 20 μm or less, The arithmetic mean height (Sa) of the surface (1) of the resin sheet is 2 nm or more and 30 nm or less, The maximum cross-sectional height (St) of the surface (1) of the resin sheet is 80 nm or more and 1000 nm or less, The static friction coefficient measured by overlapping the surface (1) of the resin sheet opposite to the release layer surface and the surface (2) of the resin sheet on the release layer side is 1.5 or less.

2. 2. The laminated film according to claim 1, wherein the crosslinking agent (B) contained in the resin sheet-forming composition is liquid at 30°C.

3. 2. The laminated film according to claim 1, wherein the crosslinking agent (B) contained in the resin sheet accounts for 10% by mass or more of the entire resin sheet.

4. 2. The laminated film according to claim 1, wherein the weight average molecular weight of the resin component (A) contained in the resin sheet is 10,000 or more.

5. The surface free energy of the release layer surface is 40 mJ / m ２ and the water adhesion energy is 3.5 mJ / m or less. ２ 2. The laminated film according to claim 1, wherein the laminated film is a laminated film having the above properties.

6. 2. The laminated film according to claim 1, wherein the arithmetic mean height (Sa) of the release layer side surface of the substrate film is 20 nm or less and the maximum protrusion height (P) is 500 nm or less.

7. A method for producing a laminated film according to any one of claims 1 to 6, A method for producing a laminated film, comprising forming a resin sheet by a solution casting method in which the resin sheet-forming composition is applied to a release layer.

8. Resin sheets used for electronic components and optical components that satisfy the following requirements: the resin sheet is obtained by curing a resin sheet-forming composition containing at least a resin component (A) and a crosslinking agent (B); The resin component (A) contains a phenoxy resin, the crosslinking agent (B) is an isocyanate, the resin sheet is substantially free of particles, The film thickness (t1) of the resin sheet is 1 μm or more and 20 μm or less, The arithmetic mean height (Sa) of the surface (1) of the resin sheet is 2 nm or more and 30 nm or less, The maximum cross-sectional height (St) of the surface (1) of the resin sheet is 80 nm or more and 1000 nm or less. can be, One surface (1) of the resin sheet and the opposite surface (1) of the resin sheet The static friction coefficient measured by overlapping with surface (2) is 1.5 or less.

9. The resin sheet is a sheet peeled from a release film having a substrate and a release layer, The release layer has a surface free energy of 40 mJ / m ２ and the water adhesion energy is 3.5 mJ / m or less. ２ The resin sheet according to claim 8 .

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