JP7409465B2 - Laminated film and method for manufacturing laminated film - Google Patents

Description

The present invention relates to a laminated film in which resin sheets are laminated. In particular, the present invention relates to a laminated film in which resin sheets are laminated for use in electronic components and optical applications.

Conventionally, release films based on polyester films have high heat resistance and mechanical properties, and are used as process films for solution casting of resin sheets such as adhesive sheets, cover films, polymer electrolyte membranes, and dielectric resin sheets. has been used as. In recent years, resin sheets used for electronic components and optical applications, such as dielectric resin sheets used in film capacitors, are required to have high smoothness and transparency. High smoothness has also been required. For this reason, techniques such as those described in Patent Documents 1 to 3 have been disclosed, and a mold release layer having a lower surface roughness has been proposed.

However, for example, in optical applications, high smoothness is required to improve transparency, but high smoothness deteriorates slipperiness, and there is a risk that scratches may occur during the transportation process, reducing yield. In addition, in electronic component applications such as film capacitors, smoothness is required to improve electrical properties such as dielectric breakdown voltage, but if the smoothness is too high, slipperiness will be poor, and dielectric resin sheets cannot be rolled. When winding the film up, there were concerns that the winding would be misaligned and wrinkles would be mixed in, making it impossible to wind it properly and reducing the performance of the film capacitor.

In order to improve these problems, Patent Document 4 proposes adding specific particles to a resin sheet used for optical purposes such as a polarizing plate to impart slipperiness. Moreover, Patent Document 5 proposes a method of transferring particles on a base film to a resin sheet used for a film for a film capacitor or the like.

Japanese Patent Application Publication No. 2012-144021 Japanese Patent Application Publication No. 2014-154273 Japanese Patent Application Publication No. 2015-182261 JP2019-95661A International Publication 2020/039638

However, in the method of Patent Document 4, since particles are included in the resin sheet, there is a concern that transparency may be insufficient, such as increased internal haze. Further, in the method of Patent Document 5, there is a risk that the amount of particles transferred to the resin sheet may become non-uniform, and there is a concern that slipperiness may become unstable.
The present invention solves the above problems and proposes a laminated film that can provide a resin sheet that is highly smooth and has good sliding properties without substantially adding particles inside the resin sheet.

As a result of extensive studies, the present inventors found that by applying a coating liquid containing at least a specific resin and a crosslinking agent under specific conditions to a smooth base film, and drying and curing it, a phase-separated structure is created on the surface of the laminated film. They discovered that the unevenness caused by this can be molded, and succeeded in providing good slipperiness without the inclusion of particles.

That is, the present invention has the following configuration.
[1] A polyester base film, a release layer disposed on at least one side of the base film, and a resin sheet disposed on the surface of the release layer opposite to the base material. ,
Laminated film that satisfies the following (1) to (6):
(1) The resin sheet is obtained by curing a resin sheet forming composition containing at least a resin component (A) and a crosslinking agent (B),
(2) The resin sheet does not substantially contain particles;
(3) The film 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 surface of the mold release layer and the surface (2) of the resin sheet on the mold 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 in 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 surface of the release layer is 40 mJ/m ² or less, and the adhesion energy is 3.5 mJ/m ² or more.
[6] In one embodiment, the arithmetic mean height (Sa) of the release layer side surface of the base 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 a laminated film according to any of the above, which method includes coating and molding a resin sheet on a base film by a solution casting method. including.

By using the laminated film of the present invention, it is possible to provide a resin sheet that is highly smooth and has good sliding properties, and by using the resin sheet molded according to the present invention, it is possible to provide products that are good for various uses. be able to.

1 is a schematic cross-sectional view showing the configuration of the present invention. FIG. 1 is a schematic cross-sectional view illustrating the configuration of the present invention in one embodiment.

As shown in FIG. 1, the laminated film of the present invention includes a polyester base film 10, a release layer 11 disposed on at least one side of the base film 10, and a base film 10 in the release layer 11. is a laminated film having a resin sheet 12 disposed on the opposite surface.

INDUSTRIAL APPLICATION This invention can provide the resin sheet which can improve transparency etc. for an optical use, for example, Comprising: Moreover, it can provide the resin sheet which shows high smoothness. Moreover, it was previously difficult to
It is possible to achieve both high smoothness and high slipperiness, and for example, it is possible to suppress scratches during the conveyance process, and to avoid a decrease in yield.
Furthermore, for electronic component applications such as film capacitor applications, a resin sheet that exhibits high smoothness can be provided, and the resin sheet can improve electrical properties such as dielectric breakdown voltage. In addition, it is possible to achieve both high smoothness and high slipperiness, which was difficult in the past, and for example, when winding a dielectric resin sheet onto a roll, it is possible to suppress winding misalignment and wrinkles, etc.
It can exhibit good winding properties. Therefore, it is possible to transport the capacitor while maintaining its excellent capacitor performance.
Furthermore, according to the present invention, the resin sheet does not substantially contain particles, and it is possible to avoid insufficient transparency such as increased internal haze. Further, it is possible to avoid the problem of non-uniformity in the amount of particles transferred to the resin sheet, and it is possible to exhibit good slipperiness.

(Base film)
The present invention has a polyester base film. The polyester constituting the polyester film used as the base material of the present invention is not particularly limited, and a polyester film formed from a polyester commonly used as a base film can be used. Preferably, it is a crystalline linear saturated polyester consisting of an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or these. More preferred is a copolymer whose main component is a constituent component of the resin. In particular, polyester films formed from polyethylene terephthalate are particularly suitable.
In polyethylene terephthalate, the repeating units of ethylene terephthalate are preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid components and diol components may be copolymerized. From the viewpoint of cost, it is preferred to use only terephthalic acid and ethylene glycol. Further, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallizing agents, etc. may be added within a range that does not impede the effects of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film for reasons such as high elastic modulus in both directions.

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, it is preferable because many breaks do not occur during the stretching process. On the other hand, if it is 0.70 dl/g or less, it is preferable because the cutting properties are good when cutting into a predetermined product width and dimensional defects do not occur. Further, it is preferable that the raw material pellets be sufficiently vacuum dried.

The method for producing the polyester film in the present invention is not particularly limited, and any conventionally commonly used method can be used. For example, it can be obtained by melting the polyester in an extruder, extruding it into a film, cooling it in a rotating cooling drum to obtain an unstretched film, and then stretching the unstretched film. The stretching is preferably biaxial stretching from the viewpoint of mechanical properties. 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. I can do it.

In the present invention, the stretching temperature during stretching of the polyester film is preferably higher than the secondary transition point (Tg) of the polyester. It is preferable to stretch the film 1 to 8 times, particularly 2 to 6 times, in both the longitudinal and transverse directions.

The thickness of the polyester film is preferably 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. If the thickness of the film is 6 μm or more, it is preferable because there is no risk of deformation due to heat during film production, processing of a release layer, molding of a resin sheet, and the like. On the other hand, if the thickness of the film is 50 μm or less, the diameter when wound into a roll is small and the length of the resin sheet to be formed can be increased, which is preferable.
When the polyester film as the base film has the multilayer structure described below, the thickness of the base film as a whole falls within the above range.

The polyester film may be a single layer or a multilayer of two or more layers. It is preferable that at least one side has a surface layer A that is substantially free of particles. In one embodiment, the polyester film that is the base film has a surface layer A on the resin sheet side. When the base film is a laminated polyester film having a multilayer structure of two or more layers, a surface layer B that can contain particles etc. may be provided on the opposite side of the surface layer A that does not substantially contain particles. preferable. As for the laminated structure, if the layer on the side where the resin sheet is placed is surface layer A, the layer on the opposite side is surface layer B, and the core layer other than these is layer C, the layer structure in the thickness direction is A/B, or Examples include laminated structures such as A/C/B.
Layer C may have a plurality of layers. Further, the surface layer B may not contain particles. In that case, it is preferable to provide a coating layer containing particles and a binder on the surface layer B in order to provide slipperiness for winding the film into a roll.

In the polyester film of the present invention, it is preferable that the surface layer A located on the surface on which the resin sheet is formed does not substantially contain particles. Further, the arithmetic mean height (Sa) of the surface layer A of the polyester film, that is, the arithmetic mean height (Sa) of the release layer side surface of the base film is preferably 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 unevenness are less likely to occur during molding of the resin sheet, which is preferable. Although it can be said that the smaller the arithmetic mean height (Sa) of the surface layer A is, the more preferable it is, but it may be 0.1 nm or more. Here, when providing a release layer as described below on the surface layer A, it is preferable that the release layer does not substantially contain particles, and the arithmetic mean height (Sa) after lamination of the release layer is within the above range. It is preferable to enter. In the present invention, "substantially free of particles" means, for example, in the case of inorganic particles, the amount of inorganic elements determined by fluorescent X-ray analysis is 50 ppm or less, preferably 10 ppm or less, and most preferably below the detection limit. This means the content. Even if particles are not actively added to the film, contaminants derived from foreign substances or dirt attached to the raw resin or the line or equipment in the film manufacturing process are peeled off and mixed into the film. This is because there is.

The maximum protrusion height (P) of the surface layer A of the polyester film, that is, 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, The thickness is 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 will not occur during the formation of the resin sheet, and the yield will be good, which is preferable.
It can be said that P in the surface layer A of the polyester film is preferably as small as possible, but it may be 1 nm or more, or 3 nm or more. Here, when a release layer, which will be described later, 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.

In the polyester film of the present invention, the surface layer B forming the opposite surface to the surface layer A preferably contains particles, particularly silica particles and/or carbonate particles, from the viewpoint of the slipperiness of the film and the ease with which air can escape. Preferably, calcium particles are used. The total amount of particles contained in the surface layer B is preferably 5,000 to 15,000 ppm. At this time, the arithmetic mean height (Sa) of the film of the surface layer B is preferably in the range of 1 to 40 nm. More preferably, the range is 5 to 35 nm. When the total amount of silica particles and/or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be released uniformly when the film is rolled up, resulting in a good rolled shape and good flatness. , it becomes suitable for manufacturing resin sheets. Further, when the total amount 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 coarse protrusions are not formed, which is preferable because the quality is stable during resin sheet molding.

As the particles contained in the surface layer B, other than silica and/or calcium carbonate, inert inorganic particles and/or heat-resistant organic particles can be used. From the viewpoint of transparency and cost, it is more preferable to use silica particles and/or calcium carbonate particles, but other inorganic particles that can be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Examples of the heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. In addition, when using silica particles, porous colloidal silica is preferable, and when using calcium carbonate particles, light calcium carbonate whose surface is treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off. .

The average particle diameter of the particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, particularly preferably 0.5 μm or more and 1.0 μm or less. It is preferable that the average particle diameter of the particles is 0.1 μm or more because the base film has good slipperiness. Further, it is preferable that the average particle diameter is 2.0 μm or less, since there is no fear that pinholes will be generated in the resin sheet due to the coarse particles of the surface layer B.

The surface layer B may contain two or more types of particles made of different materials. Further, particles of the same type but having different average particle diameters may be contained.

When the surface layer B does not contain particles, it is preferable that a coating layer containing particles be provided on the surface layer B to provide slipperiness. This coat layer is not particularly limited, but is preferably provided as an in-line coat applied during the production of the polyester film. When the surface layer B does not contain particles and has a coat layer containing particles on the surface layer B, the surface of the coat layer has an arithmetic mean height (Sa) for the same reason as the arithmetic mean height (Sa) of the surface layer B described above. The height (Sa) is preferably in the range of 1 to 40 nm. More preferably, the range is 5 to 35 nm.

From the viewpoint of reducing pinholes, it is preferable not to use recycled raw materials in 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.

The thickness ratio of the surface layer A, which is the layer on which the resin sheet is provided, is preferably 20% or more and 50% or less of the total layer thickness of the base film. If it is 20% or more, the effect of particles contained in the surface layer B etc. is less likely to be felt from inside the film, and the arithmetic mean height (Sa) can easily satisfy the above range, which is preferable. When the thickness is 50% or less of the total thickness of the base film, the ratio of recycled raw materials used in the surface layer B can be increased, and the environmental burden is reduced, which is preferable.

Furthermore, from the viewpoint of economic efficiency, 50 to 90% by mass of film scraps or recycled raw materials from PET bottles can be used for layers other than the surface layer A (surface layer B or the above-mentioned intermediate layer C). Even in this case, it is preferable that the type, amount, particle size, and arithmetic mean height (Sa) of the lubricant contained in the surface layer B satisfy the above ranges.

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

(Release layer)
The present invention has a release layer disposed on at least one side of the base film, for example, between the base film and the 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 the resin sheet described below contains a crosslinking agent, it is preferable because containing a silicone resin improves mold releasability.
In addition, in this specification, a base material and a release layer laminated body may be simply called a release film.

The release layer can include, for example, silicone resin. Silicone resin is a resin that has a silicone structure in its molecule, and examples include curable silicone, silicone graft resin, and modified silicone resin such as alkyl-modified resin, but from the viewpoint of migration, reactive cured silicone resin It is preferable to use As the reactive curing silicone resin, addition reaction type, condensation reaction type, ultraviolet ray or electron beam curing type, etc. can be used. More preferably, a low-temperature curing addition reaction type that can be processed at a low temperature, and an ultraviolet or electron beam curing type are preferred. By using these materials, processing can be performed at low temperatures when coating a polyester film. Therefore, there is less heat damage to the polyester film during processing, a polyester film with high flatness can be obtained, and defects such as pinholes can be reduced even when producing a thin resin sheet.

Examples of addition reaction type silicone resins include those that are cured by reacting polydimethylsiloxane into which a vinyl group has been introduced into the terminal or side chain with hydrogen siloxane using a platinum catalyst. At this time, it is more preferable to use a resin that can be cured within 30 seconds at 120° C., as this allows processing at low temperatures. Examples include low-temperature addition-curing types manufactured by Dow/Toray (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755, LTC760A, etc.) and thermal UV-curing types (LTC85 1, BY24- 510, BY24-561, BY24-562, etc.), solvent addition + UV curing type (X62-5040, X62-5065, X62-5072T, KS5508, etc.), dual cure curing type (X62-2835, X62- 2834, X62-1980, etc.).

Examples of condensation reaction silicone resins include those that create a three-dimensional crosslinked structure by condensing polydimethylsiloxane having an OH group at the end and polydimethylsiloxane having an H group at the end using an organotin catalyst. Can be mentioned.

Examples of UV-curable silicone resins include those that use the same radical reaction as normal silicone rubber crosslinking as the most basic type, those that are photocured by introducing unsaturated groups, and those that are cured by photocuring by introducing unsaturated groups, and those that are made by decomposing onium salts with UV rays. Examples include those that generate a strong acid and use this to cleave the epoxy groups to effect crosslinking, and those that effect crosslinking by addition reaction of thiol to vinylsiloxane. Moreover, an electron beam can also be used instead of the ultraviolet rays. Electron beams have more energy than ultraviolet rays, and it is possible to carry out a crosslinking reaction using radicals without using an initiator as in the case of ultraviolet curing. Examples of resins used include UV-curing silicones manufactured by Shin-Etsu Chemical (X62-7028A/B, X62-7052, X62-7205, X62-7622, X62-7629, X62-7660, etc.), Momentive Performance UV curing silicone manufactured by Materials Co., Ltd. (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.), UV curing silicone manufactured by Arakawa Chemical Co., Ltd. (Silicolease UV POLY200, POLY215, POLY201, KF-UV265) AM etc. ).

As the above-mentioned ultraviolet curing silicone resin, acrylate-modified or glycidoxy-modified polydimethylsiloxane can also be used. Good mold release performance can also be achieved by mixing these modified polydimethylsiloxanes with polyfunctional acrylate resins, epoxy resins, etc. and using them in the presence of an initiator.

Examples of other resins that may be used include stearyl-modified, lauryl-modified alkyd resins and acrylic resins, and alkyd resins, acrylic resins, and olefin resins obtained by reactions with methylated melamine.

Examples of the amino alkyd resin obtained by the above-mentioned reaction of methylated melamine include Tesfine 303, Tesfine 305, and Tesfine 314 manufactured by Hitachi Chemical. Examples of the aminoacrylic resin obtained by the reaction of methylated melamine include Tesfine 322 manufactured by Hitachi Chemical.

When the above resins are used in the release layer of the present invention, they may be used alone or in a mixture of two or more types. Further, in order to adjust the release force, it is also possible to mix additives such as light release additives and heavy release additives.

Additives such as adhesion improvers and antistatic agents may be added to the release layer of the present invention. Furthermore, in order to improve the adhesion to the base material, it is also preferable to subject the surface of the polyester film to pretreatment such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. before providing the release layer.

In the present invention, the thickness of the mold release layer may be set depending on the purpose of use and is not particularly limited, but preferably the thickness of the mold release layer after curing is within a range of 0.005 to 2.0 μm. good. It is preferable that the thickness of the release layer is 0.005 μm or more because the release performance is maintained. Further, it is preferable that the thickness of the release layer is 2.0 μm or less, since the curing time will not be too long and there will be no risk of uneven thickness of the resin sheet due to deterioration of the flatness of the release film. Furthermore, since the curing time is not too long, there is no risk of the resin constituting the release coating layer coagulating, and there is no risk of forming protrusions, which is preferable because pinhole defects in the resin sheet are less likely to occur.

It is preferable that the surface free energy of the release layer provided on the base film of the present invention is 12 mJ/m ² or more. More preferably, it is 18 mJ/m ² or more, and even more preferably 20 mJ/m ² or more. If it is 12 mJ/m ² or more, it is preferable because repelling and the like are less likely to occur when the solution of the resin sheet is applied.

The surface free energy of the release layer provided on the base film of the present invention is preferably 40 mJ/m ² or less. More preferably, it is 35 mJ/m ² or less, and even more preferably 30 mJ/m ² or less. It is preferable that it is 40 mJ/m ² or less because the molded resin sheet has good releasability.
In the present invention, the above-mentioned surface free energy means the surface free energy of at least the surface of the release layer that is in contact with the resin sheet.

The water adhesion energy of the surface of the release layer of the present invention in contact with the resin sheet is, for example, 3.0 mJ/m ² or more, preferably 3.5 mJ/m ² or more. More preferably, it is 4.0 mJ/m ² or more, and even more preferably 5.5 mJ/m ² or more. If it is 3.0 mJ/m ² or more, it is preferable because swelling of the coated end portions is suppressed when coating the solution of the resin sheet. Suppressing the swelling of the coated edges during coating is preferable because it suppresses ridges when the laminated film is wound into a roll, resulting in a good winding appearance and good flatness of the laminated film.

In order to improve the water adhesion energy on the surface of the mold release layer, it can be achieved by adding additives to the mold release layer or adjusting the polymer composition. For example, in the case of silicone resin, a siloxane unit having a phenyl group on the side chain is introduced into the polydimethylsiloxane skeleton, or a silicone resin with T units (trifunctional) or Q units (tetrafunctional) is added. This can be improved.

In order to improve the water adhesion energy on the surface of the release layer, it can also be achieved by changing the composition of the silicone resin as a method other than the above. For example, addition reaction-based silicone resins can be cured by heating polydimethylsiloxane and hydrogen siloxane, which have vinyl groups introduced into their terminals or side chains, under a platinum catalyst. -Vy) The water adhesion energy can also be changed by changing the molar amount of Si-H groups in hydrogensiloxane. For example, the water adhesion energy tends to be higher when there is more Si-H than Si-Vy, and the ratio of Si-H/Si-Vi is preferably 1.0 or more, more preferably 1.5 or more. More preferably 2.0 or more.

The release layer of the present invention preferably has an arithmetic mean height (Sa) of not only the polyester base material but also the release layer of 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 unevenness are less likely to occur during molding of the resin sheet, which is preferable. It can be said that the smaller the arithmetic mean height (Sa) of the release layer is, the more preferable it is, but it may be 0.1 nm or more.
Further, 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, and 50 nm or less. Particularly preferred. If the maximum protrusion height (P) is 500 nm or less, defects such as pinholes and local thinning will not occur during the formation of the resin sheet, and the yield will be good, which is preferable.

In the present invention, the method of forming the mold release layer is not particularly limited, and a coating liquid in which a mold release resin is dissolved or dispersed is spread by coating on one side of a polyester film as a base material, and a solvent etc. After removing by drying, heat drying, heat curing, or ultraviolet curing is used.

Any known coating method can be applied to the above-mentioned release layer, such as roll coating methods such as gravure coating method and reverse coating method, bar coating method such as wire bar coating method, die coating method, spray coating method, and air coating method. Conventionally known methods such as a knife coating method can be used.

When using a thermosetting material for the release layer, the drying temperature during solvent drying and thermosetting is preferably 180°C or lower, more preferably 160°C or lower, and 140°C or lower. is more preferable, and most preferably 120° C. or lower. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and most preferably 10 seconds or less. When the temperature is 180° C. or lower, the flatness of the film is maintained and there is little risk of causing thickness unevenness of the resin sheet, which is preferable. It is particularly preferable that the temperature is 120° C. or lower, since the film can be processed without impairing its flatness and the possibility of causing thickness unevenness of the resin sheet is further reduced.
Although the lower limit of the drying temperature is not particularly limited, it is preferably 60°C or higher. It is preferable that the temperature is 60° C. or higher because a release film can be obtained without any solvent remaining in the release layer.

When using an ultraviolet curable material for the release layer, the drying temperature during solvent drying and heat curing is preferably 120°C or lower, more preferably 100°C or lower, and 90°C or lower. is the most preferred. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, and most preferably 10 seconds or less. When the temperature is 120° C. or lower, the flatness of the film is maintained and there is little risk of causing thickness unevenness of the resin sheet, which is preferable. It is particularly preferable that the temperature is 90° C. or lower, since the film can be processed without impairing its flatness and the possibility of causing thickness unevenness of the resin sheet is further reduced.
Although the lower limit of the drying temperature is not particularly limited, it is preferably 60°C or higher. It is preferable that the temperature is 60° C. or higher because a release film can be obtained without any solvent remaining in the release layer.

When using an ultraviolet curable material for the release layer, it is preferable to irradiate active energy rays to cause a curing reaction after the above-mentioned solvent drying. As the active energy ray to be used, known techniques such as ultraviolet rays and electron beams can be used, and it is preferable to use ultraviolet rays. The cumulative amount of light when using ultraviolet light can be expressed as the product of illuminance and irradiation time. For example, it is preferably 10 to 500 mJ/cm ² . It is preferable to set it to the lower limit or more because the release layer can be sufficiently cured. By setting it below the above upper limit, 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, which is preferable.

(resin sheet)
The laminated film of the present invention has a resin sheet disposed on the surface of the release layer opposite to the base material.
For example, the resin sheet to be laminated on the release film of the present invention is a cured resin sheet-forming composition containing at least a resin component (A) and a crosslinking agent (B).
As a result of extensive studies, the resin sheet of the present invention can be produced under specific conditions described below, for example, by forming it from the resin sheet forming composition according to the present invention, in a state in which the resin component (A) and the crosslinking agent (B) are phase-separated. This enables the resin sheet to be cured, form appropriate irregularities on the surface of the resin sheet, and exhibit the slipperiness of the resin sheet without containing particles or the like.

The combined mass ratio of the resin component (A) and the crosslinking agent (B) preferably accounts for 80% by mass or more of the solid content of the entire resin sheet, more preferably 90% by mass or more, and even more preferably 95% by mass or more. . It is preferable that the content is 80% by mass or more because physical properties such as strength and heat resistance of the resin sheet are improved.

The mass ratio of the resin component (A) to the crosslinking agent (B) is preferably (A)/(B) = 90/10 to 50/50. When the blending ratio of the crosslinking agent (B) is 10% by mass or more, it is preferable because the unevenness after phase separation tends to increase and the slipperiness improves. If the blending ratio of the crosslinking agent (B) is 50% by mass or less, the film strength of the resin sheet will not decrease and the sheet will be easy to handle, which is preferable. Blocking with the back side can also be prevented. For example, it is preferable that the proportion of the crosslinking agent (B) contained in the resin sheet to the entire resin sheet is 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 in 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 such conditions, the above effects can be better achieved.

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 even if only one type is used. Two or more types may be used in combination. The weight average molecular weight (Mw) of the resin component (A) used in the present invention is 10,000 or more, preferably 10,000 or more and 200,000 or less, and more preferably 30,000 or more and 100,000 or less. If it is 10,000 or more, the strength of the resin sheet is strong and the handleability is good, so it is preferable. When the molecular weight is 200,000 or less, the viscosity of the solution decreases and productivity becomes good when performing solution film formation, which is preferable. The method for measuring the weight average molecular weight (Mw) is not particularly limited, but it can be measured using GPC or the like.

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 one type or a mixture of two or more types may be used. It is preferable that it 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, the liquid may be any fluid as long as it has fluidity, for example, a viscosity of 10,000 mPa·s or less. Being liquid at 30° C. is preferable because phase separation from the resin component (A) can be effectively promoted during drying of solution casting of the resin sheet, and surface irregularities of the resin sheet can be easily formed.

The resin sheet may contain additives in addition to the resin component (A) and the crosslinking agent (B) as long as they satisfy the above ranges. However, the resin sheet does not substantially contain particles. Since the resin sheet according to the present invention does not substantially contain particles, it has the effect of increasing the transparency of the molded resin sheet for optical applications, for example, and for electronic applications such as dielectric sheets used in film capacitors. It is preferable for parts because it is easy to obtain effects such as improved electrical characteristics. For example, for optical applications, the resin sheet can have a haze of 2% or less. Further, the haze may be 1% or less. In one embodiment, the resin sheet has a haze of 0.1% or more. Further, for example, in the case of an electronic component such as a film capacitor, the resin sheet can have a dielectric breakdown voltage of 200 V/μm or more. Further, the dielectric breakdown voltage may be 300 V/μm or more. In one embodiment, the breakdown voltage is 500V/μm or less.

Even if the resin sheet of the present invention does not substantially contain particles, it has good slip properties because of the presence of minute irregularities on the surface due to phase separation of the resin component (A) and the crosslinking agent (B). can have The static friction coefficient of the resin sheet peeled from the base film is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. It is preferable that the static friction coefficient is 1.5 or less because when used as a resin sheet for optical applications or electronic parts applications, the resin sheet has good winding properties, running properties, etc., and is easy to handle. The static friction coefficient of the resin sheet may be 0.1 or more.
In one embodiment, in FIG. 2, the static friction coefficient is measured by overlapping the surface (1) of the resin sheet opposite to the release layer, indicated by the reference numeral 13, and the surface (2) of the resin sheet, indicated by the 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. Further, the static friction coefficient may be 0.1 or more.
As described above, 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. can.

The arithmetic mean roughness (Sa) 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 2 nm or more and 30 nm or less, more preferably 2 nm or more and 20 nm or less. , more preferably 2.5 nm or more and 15 nm or less. When the thickness is 2 nm or more, the resin sheet has good slipperiness, which is preferable. When the thickness is 30 nm or less, even when the resin sheet is peeled off from the laminated film and only the resin sheet is wound up into a roll, there is less concern that defects such as pinholes will occur, which is preferable.

The maximum cross-sectional height (St) 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 80 nm or more and 1000 nm or less, more preferably 100 nm or more and 600 nm or less. , more preferably 150 nm or more and 500 nm or less. When it is 80 nm or more, the resin sheet has good slipperiness, which is preferable. If it is 1000 nm or less, even when the resin sheet is peeled off from the laminated film and only the resin sheet is wound up into a roll, there is less concern that defects such as pinholes will occur, which is preferable.
Note that 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).

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, and 200 nm or less. The following is more preferable, and may be 185 nm or less, for example, 150 nm or less, and particularly preferably 135 nm or less. For example, it may be 100 nm or less.
If the maximum protrusion height (P) is 500 nm or less, defects such as pinholes will not occur even when the resin sheet is peeled off from the laminated film and only the resin sheet is wound up into a roll, which is preferable. Although it can be said that the smaller the maximum protrusion height P is, the more preferable it is, it may be 1 nm or more, 3 nm or more, for example, 35 nm or more.

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

In one embodiment, the maximum valley depth (V) of the surface (1) of the resin sheet of the laminated 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. By having the maximum valley depth (V) within such a range, even if the maximum protrusion height (P) is within the range of 250 nm or less, the maximum cross-sectional height (St) can be easily controlled within the above range. This is preferable because it can improve the slipperiness of the resin sheet.

The arithmetic mean roughness (Sa) of the surface (2) (surface in contact with the release layer) of the resin sheet of the laminated film of the present invention is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 5 nm or less. If the thickness is 10 nm or less, even when the resin sheet is peeled off from the laminated film and only the resin sheet is wound up into a roll, there is less concern that defects such as pinholes will occur, which is preferable.

The film 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 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 difficult to tear even after being peeled off from the base film and can be easily handled. If the film 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 film forming and molding is easy.

The film thickness (t1) of the resin sheet is not particularly limited and can be measured by a known method. For example, a contact type film thickness meter, an optical interference type film thickness meter, or a cross section can be observed and measured using a scanning electron microscope, a transmission electron microscope, or the like.

As a method for laminating the resin sheet of the present invention on a base film, a coating solution containing at least the above-mentioned resin component (A) and crosslinking agent (B) and dissolved or dispersed in an organic solvent, water, etc. is used in a solution casting method. It is preferable to mold it on the mold release layer, and it can be applied by a known method similar to the method for applying the mold release layer. For example, conventionally known methods such as a roll coating method such as a gravure coating method or a reverse coating method, a bar coating method such as a wire bar coating method, a die coating method, a spray coating method, an air knife coating method, etc. can be used.

After applying the coating liquid to the release layer, it is preferable to include a heating step in order to dry and harden the solvent. The heating method is not particularly limited, but the laminated film after coating can be heated using hot air, infrared rays, or the like. The laminated film of the present invention is preferably coated and dried in a roll-to-roll manner, and is particularly preferably dried using hot air in a drying oven such as a floating method or a roll support method.

Regarding the temperature during drying, the maximum temperature of the drying oven is preferably 60°C or more and 160°C or less, more preferably 70°C or more and 140°C or less, and even more preferably 70°C or more and 130°C or less. If it is 60° C. or higher, there is little residual solvent in the resin sheet after drying, and there is no fear that the performance of the resin sheet (for example, electrical properties if used as a dielectric layer) will deteriorate, so it is preferable. If it is 160° C. or lower, there is no concern that the laminated film will wrinkle due to heat, so it is preferable. Furthermore, if the temperature is higher than 160°C, there is a concern that the phase separation between the resin component and the crosslinking agent in the resin sheet will proceed too much and the crosslinking density of the resin sheet will decrease, so it is preferable to keep the temperature at 160°C or lower.

The time from applying the coating liquid to the base film to entering 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, the phase separation between the resin component and the crosslinking agent in the coating liquid will not proceed too much, and there will be no concern that the crosslinking density of the resin sheet will decrease, which is preferable.

After applying the coating liquid to the base film, the time for heating at the maximum temperature in a drying oven is preferably 1 second or more, and preferably 2 seconds or more. It is preferable that the time is 1 second or more because the reaction of the crosslinking agent proceeds. The upper limit of the heating time is preferably within 60 seconds, more preferably within 40 seconds, and even more preferably within 20 seconds. If the heating time is within 60 seconds, it is preferable because segregation of the crosslinking agent onto the surface of the resin sheet can be prevented from progressing excessively, and the performance of the resin sheet will not be deteriorated.

By subjecting the resin sheet of the present invention to the above-mentioned drying conditions, the phase separation of the resin component (A) and the crosslinking agent (B) can proceed appropriately, and the arithmetic mean roughness (Sa) of the resin sheet surface (1) can be improved. The maximum cross-sectional height (St) can be controlled within the above range, and the resin sheet can exhibit good sliding properties without adding particles to the resin sheet.

(Laminated film)
The laminated film of the present invention is used after the resin sheet is peeled off from the base film in subsequent steps. Therefore, it is preferable that the peeling force from the base film is 800 mN/25 mm width or less because the resin sheet can be peeled off without breaking. More preferably it is 500 mN/25 mm width or less, still more preferably 300 mN/25 mm width or less, and still more preferably 200 mN/25 mm width or less. Since the peeling force differs depending on the laminated resin sheets, it can be adjusted depending on the type of release layer of the base film.

Next, the present invention will be described in detail using Examples and Comparative Examples, but the present invention is of course not limited to the following Examples. Moreover, the evaluation method used in the present invention is as follows.

(Arithmetic average height (Sa), maximum protrusion height (P), maximum valley depth (V), maximum cross-sectional height (St))
These are values measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Ryoka System Co., Ltd.). The arithmetic mean height (Sa) is the average value of 5 measurements, and the maximum protrusion height (P) and maximum valley depth (V) are measured 7 times and the maximum and minimum values are excluded. The maximum value was used. The maximum cross-sectional height (St) was the sum of the absolute values of the maximum protrusion height (P) and the maximum valley depth (V).
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 10x ・0.5×Tube lens ・Measurement area 936μm×702μm
(Analysis conditions)
・Surface correction: Quadratic correction ・Interpolation processing: Complete interpolation ・Filter processing: Gaussian Cutoff value 50μm

(Surface free energy)
Water (droplet volume 1.8 μL) was applied to the release surface of the release film using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.: Fully Automatic Contact Angle Meter DM-701) at 25°C and 50% RH. A droplet of diiodomethane (appropriate amount of liquid: 0.9 μL) was prepared, and its contact angle was measured. For the contact angle, the contact angle 10 seconds after dropping each liquid onto the release film was adopted. The contact angle data of water and diiodomethane obtained by the above method were calculated using the "Owens and Wendt" theory, and the dispersion component γd of the surface free energy of the release film was calculated, and the component γh was calculated based on the hydrogen bond and dipole-dipole interaction. was determined, and the sum of each component was defined as the surface free energy γs. This calculation was performed using analysis software included in the contact angle meter software (FAMAS).

(Water adhesion energy)
Water (droplet volume 10 μL) was dropped on the release surface of the release film using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.: Fully Automatic Contact Angle Meter DM-701) at 25°C and 50% RH. Then, 2 seconds after dropping, the stage was continuously tilted and the contact angle was measured every 1°. In addition, the inclination 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 there. This calculation was performed using analysis software included in the contact angle meter software (FAMAS).

(film thickness)
The cut laminated film was embedded in resin and cut into ultrathin sections using an ultramicrotome. Thereafter, direct observation was performed 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 image.

(Peeling force)
The laminated film was cut into strips with a width of 25 mm and a length of 150 mm, 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 check the T-peel strength. It was measured. For the measurement, a tensile tester ("AUTOGRAPH AG-X" manufactured by Shimadzu Corporation) was used. The average value of 5 measurements was used as the measured value.
The peelability was evaluated based on the measured peeling force according to the following criteria.
〇: It was possible to peel off with a low peeling force of 100mN/25mm width or less, and even a thin film could be peeled off without tearing. 〇△: It was possible to peel off with a peeling force of 300mN/25mm or less and greater than 100mN/25mm width. Ta.
Δ: Peeling force was greater than 300 mN/25 mm width and could be peeled off with less than 800 mN/25 mm width. In parts where the film thickness was extremely thin, some parts were sometimes torn. ×: Could not be peeled off.

(Static friction coefficient and slipperiness evaluation)
The static friction coefficient of the resin sheet was measured as follows, and the slipperiness was evaluated.
The resin sheet was peeled off from the laminated film and fixed to the bottom of a metal rectangular parallelepiped weighing 1.4 kg so that the surface (2) of the resin sheet was facing up. Next, the resin sheet was fixed with adhesive tape onto a flat metal plate with the surface (1) facing up. A metallic rectangular parallelepiped was placed so that surfaces (1) and (2) were in contact with each other, and the coefficient of static friction was measured at a pulling speed of 200 mm/min at 23° C. and 65% RH.
The slipperiness was judged based on the following criteria.
〇: 0.1<μs≦0.8
△: 0.8<μs≦1.5
×: Over 1.5 or the friction coefficient is too high to measure

(Electrical characteristics)
A thin aluminum vapor-deposited layer was provided 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 to evaluate according to the following criteria.
〇: Dielectric breakdown voltage (BDV value) is 300V/μm or more △: Dielectric breakdown voltage is 200V/μm or more ×: Dielectric breakdown voltage is less than 200V/μm

(Preparation of polyethylene terephthalate pellets (PET(I)))
As the esterification reactor, a continuous esterification reactor consisting of a three-stage complete mixing tank having a stirrer, a partial condenser, a raw material inlet, and a product outlet was used. TPA (terephthalic acid) is set at 2 tons/hour, EG (ethylene glycol) is set at 2 moles per 1 mole of TPA, antimony trioxide is set at an amount such that Sb atoms are 160 ppm relative to the produced PET, and these slurries are converted into esters. The mixture was continuously supplied to the first esterification reactor of the esterification reactor, and reacted at 255°C for an average residence time of 4 hours at normal pressure. Next, the reaction product in the first esterification reactor is continuously taken out of the system and supplied to the second esterification reactor, and the reaction product is distilled from the first esterification reactor into the second esterification reactor. In addition, an EG solution containing magnesium acetate tetrahydrate in an amount such that Mg atoms are 65 ppm relative to the produced PET, and 40 ppm P atoms relative to the produced PET is supplied. An EG solution containing an amount of TMPA (trimethyl phosphate) was added, and the mixture was reacted at 260°C for an average residence time of 1 hour at normal pressure. Next, the reaction product of the second esterification reactor was continuously taken out of the system and supplied to the third esterification reactor, and was heated to 39 MPa (400 kg/cm ² ) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). Average particles made of 0.2% by mass of porous colloidal silica with an average particle diameter of 0.9 μm that has been subjected to dispersion treatment at a pressure of 5 times on average and 1% by mass of ammonium salt of polyacrylic acid per calcium carbonate. While adding 0.4% by mass of synthetic calcium carbonate having a diameter of 0.6 μm as a 10% EG slurry, the mixture was reacted at 260° C. for an average residence time of 0.5 hours at normal pressure. The esterification reaction product produced in the third esterification reactor was continuously fed to a three-stage continuous polycondensation reactor to perform polycondensation, and stainless steel fibers with a 95% cut diameter of 20 μm were sintered. After filtration with a filter, ultrafiltration was performed and extruded into water, and after cooling, it was cut into chips to obtain PET chips with an intrinsic viscosity of 0.60 dl/g (hereinafter abbreviated as PET (I)). . The lubricant content in the PET chip was 0.6% by mass.

(Preparation of polyethylene terephthalate pellets (PET(II)))
On the other hand, in the production of the above PET chip, a PET chip with an intrinsic viscosity of 0.62 dl/g containing no particles of calcium carbonate, silica, etc. was obtained (hereinafter abbreviated as PET (II)).

(Preparation of polyethylene terephthalate pellets (PET(III)))
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 1% by mass of ammonium salt of polyacrylic acid was attached per calcium carbonate. A PET chip was obtained in the same manner as PET (I) (hereinafter referred to as PET (III)
). The lubricant content in the PET chip was 0.75% by mass.

(Manufacture of base film X1)
After drying, these PET chips were melted at 285°C, melted at 290°C by a separate melt extruder extruder, and filtered with sintered stainless steel fibers with a 95% cut diameter of 15 μm and a filter with a 95% cut diameter of 15 μm. Two stages of filtration are performed using a filter made of sintered stainless steel particles of 15 μm, which are combined in a feed block, and PET (I) is layered as surface layer B, and PET (II) is layered as surface layer A. The unstretched polyethylene terephthalate sheet with an intrinsic viscosity of 0.59 dl/g was extruded (casted) into a sheet at a speed of 45 m/min, electrostatically adhered and cooled on a casting drum at 30°C using the electrostatic adhesion method. Obtained. The layer ratio was adjusted by calculating the discharge amount of each extruder so that PET (I)/PET (II) = 60%/40%. Next, this unstretched sheet was heated with an infrared heater, and then stretched 3.5 times in the machine direction at a roll temperature of 80° C. using a speed difference between the rolls. Thereafter, it was introduced into a tenter and stretched 4.2 times in the transverse direction at 140°C. Then, heat treatment was performed at 210° C. in a heat fixing zone. Thereafter, a relaxation treatment of 2.3% was performed at 170° C. in the transverse direction to obtain a base film X1 of a biaxially stretched polyethylene terephthalate film having a thickness of 25 μm. The Sa of the surface layer A of the obtained base film X1 was 2 nm, and the Sa of the surface layer B was 29 nm.

(Manufacture of base film X2 having a release layer)
On the surface layer A of the base film X1 obtained above, the following release coating liquid Y1 was coated by reverse gravure coating so that the wet film thickness was 5 μm, and dried at 120°C for 30 seconds in a hot air drying oven. It was cured to obtain a base film X2 with a release layer. Sa on the surface 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 material, 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 Industries)
0.11 parts by mass

(Manufacture of base film X3 having a release layer)
A biaxially stretched polyethylene terephthalate film with a thickness of 12 μm was created by adjusting the thickness by changing the casting speed without changing the layer structure and stretching conditions similar to those of base film A base film X3 was obtained by providing a mold layer. The Sa of the surface layer A of the obtained film X3 was 3 nm, and the Sa of the surface layer B was 29 nm.

(Method for producing base film X4 having a release layer)
As the base film X4, a film in which a release layer similar to X2 was provided on the surface layer A of A4100 (Cosmoshine (registered trademark), manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm was used. A4100 does not substantially contain particles in the film, and has a structure in which a coating layer containing particles is provided only on the surface layer B side by inline coating. The Sa of the surface layer A of the base film X4 was 1 nm, and the Sa of the surface layer B was 2 nm.

(Method for producing base film X5 having a release layer)
As the base film X5, a 25 μm thick E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) with a release layer similar to X2 on the surface layer A was used. E5101 has a structure in which particles are contained in the surface layers A and B of the film. The Sa of the surface layer A of the base film X5 was 25 nm, and the Sa of the surface layer B was 25 nm.

(Method for manufacturing base film X6 having a release layer)
On the surface layer A of the base film X1, apply the following release coating liquid Y2 by reverse gravure coating so that the wet film thickness is 5 μm, and dry and cure it in a hot air drying oven at 120°C for 30 seconds to release it. A layered base film X6 was obtained. Sa on the surface 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 material, 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 Industries)
0.1 part by mass

(Method for manufacturing base film X7 having a release layer)
On the surface layer A of the base film X1, apply the following mold release coating liquid Y3 by reverse gravure coating so that the wet film thickness is 5 μm, and dry and cure it in a hot air drying oven at 120°C for 30 seconds to release the mold. A layered base film X7 was obtained. Sa on the surface 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 material, 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 Industries)
0.1 part by mass

(Example 1)
A resin solution Z is applied onto the surface layer A of the base film X2 using a reverse gravure coating method.
1 was coated so that the thickness of the resin sheet after drying was 3 μm, and dried in a hot air drying oven at 120° C. for 10 seconds to form a resin sheet and create a laminated film. (At this time, it took 2 seconds to enter the drying oven after coating). 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran Millionate MR-200 5.3 parts by mass (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa・s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(Examples 2-3)
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.

(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 having 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 57000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran Millionate MR-200 5.3 parts by mass (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa・s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(Example 5)
A laminated film was produced in the same manner as in Example 1, except that the resin solution Z2 was used 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran Millionate MR-400 5.3 parts by mass (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 600mPa・s, solid content 99% by mass)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(Example 6)
A laminated film was produced in the same manner as in Example 1, except that the type of crosslinking agent was changed to resin solution Z3.
(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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. Millionate MTL 5.3 parts by mass (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 50 mPa・s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(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 and 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. 3.5 parts by mass of Millionate MR-200 (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa・s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(Example 8)
A laminated film was produced in the same manner as in Example 1, except that resin solution Z5 was used to change the ratio of resin and 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran Millionate MR-200 1.8 parts by mass (manufactured by Tosoh Corporation, isocyanate crosslinking agent, viscosity 200 mPa・s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone surfactant)

(Examples 9 to 11)
A laminated film was produced in the same manner as in Example 1, except that the base film shown in Table 1 was used.

(Examples 12-13)
A laminated film was produced in the same manner as in Example 1, except that the drying temperature of the resin sheet was changed to the temperature listed in Table 1.

(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 without a release layer.

(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 containing no 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 (Phenoxy resin manufactured by Gabriel Phenoxies, Mw 32000)
*The solution was prepared by dissolving phenoxy resin in tetrahydrofuran. BYK-370 0.4 parts by mass (manufactured by BYK Chemie Japan, silicone surfactant)

(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.

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

The laminated sheet of the present invention obtained in the Examples is a resin sheet that can improve transparency in optical applications, for example, and can also provide a resin sheet that exhibits high smoothness. Moreover, it is possible to achieve both high smoothness and high slipperiness, and for example, it is possible to suppress scratches during the conveyance process, etc., and it is possible to avoid a decrease in yield.
Furthermore, for electronic component applications such as film capacitor applications, a resin sheet that exhibits 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, and for example, when winding a dielectric resin sheet onto a roll, it is possible to suppress winding misalignment, wrinkles, etc., and exhibit good winding performance. . Therefore, it is possible to transport the capacitor 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. Further, it is possible to avoid the problem of non-uniformity in the amount of particles transferred to the resin sheet, and it is possible to exhibit good slipperiness.

On the other hand, since Comparative Example 1 did not have the release layer according to the present invention, the releasability of the resin sheet was extremely poor, and the resin sheet could not be evaluated. In Comparative Example 2, since the resin sheet forming composition did not contain a crosslinking agent, the slipperiness of the resin sheet was particularly poor.
In Comparative Example 3, since the maximum cross-sectional height (St) of the surface (1) of the resin sheet was outside the range of the present invention, the slipperiness of the resin sheet was particularly poor.

The present invention relates to a laminated film in which resin sheets are laminated. In particular, the present invention relates to a laminated film in which resin sheets are laminated for use in electronic components and optical applications.

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

Claims (8)

A polyester base film having a multilayer structure of two or more layers, a release layer disposed on at least one side of the base film, and a resin disposed on the surface of the release layer opposite to the base material. has a sheet,
Laminated film that satisfies the following:
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, and the resin sheet does not substantially contain particles,
The film thickness (t1) of the resin sheet is 1 μm or more and 20 μm 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,
A static friction coefficient measured by overlapping a surface (1) of the resin sheet opposite to the surface of the mold release layer and a surface (2) of the resin sheet on the mold release layer side is 1.5 or less. The laminated film according to claim 1, wherein the arithmetic mean height (Sa) of the surface (1) of the resin sheet is 2 nm or more and 30 nm or less. The laminated film according to claim 1, wherein the crosslinking agent (B) contained in the resin sheet forming composition is liquid at 30°C. The laminated film according to claim 1, wherein the proportion of the crosslinking agent (B) contained in the resin sheet in the entire resin sheet is 10% by mass or more. The laminated film according to claim 1, wherein the resin component (A) contained in the resin sheet has a weight average molecular weight of 10,000 or more. The laminated film according to claim 1, wherein the surface free energy of the release layer is 40 mJ/m ² or less, and the water adhesion energy is 3.5 mJ/m ² or more. The laminated film according to claim 1, wherein the arithmetic mean height (Sa) of the release layer side surface of the base film is 20 nm or less, and the maximum protrusion height (P) is 500 nm or less. A method for producing a laminated film according to any one of claims 1 to 7, comprising:
A method for producing a laminated film, comprising forming a resin sheet by a solution casting method of applying the resin sheet forming composition to a release layer.