JP2023120439A - Laminated film, and method for producing laminated film - Google Patents

Abstract

To provide a laminated film which enables provision of a resin sheet having both high smoothness and good slipperiness.SOLUTION: A laminated film has a base material film, a release layer arranged on at least one surface of the base material film, and a resin sheet arranged on a surface opposite to the base material in the release layer, wherein the base material film has a surface layer A that does not substantially contain particles, and a surface layer B on a surface opposite to the surface layer A, an arithmetic average height (Sa) of the surface layer B is 40 nm or less, and the laminated film satisfies the following conditions. The resin sheet is obtained by curing a resin sheet formation composition containing a resin component (A) and a crosslinking agent (B), the resin sheet does not substantially contain particles, a film thickness (t1) is 1 μm or more and 20 μm or less, a maximum cross-sectional height (St) of a surface (1) is 80 nm or more and 1,000 nm or less, and a coefficient of static friction obtained by measuring the surface (1) opposite to the release layer surface in the resin sheet and a surface (2) on the release layer side in the resin sheet in a stacked manner is 1.5 or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminated film obtained by laminating resin sheets. In particular, the present invention relates to a laminated film obtained by laminating resin sheets used for electronic parts and optical applications.

In the past, release films based on polyester film have high heat resistance and mechanical properties, and are process films used 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, dielectric resin sheets used in film capacitors and other electronic parts and resin sheets used in optical applications are required to have high smoothness and transparency. A high level of smoothness has also been demanded. Therefore, techniques such as those described in Patent Documents 1 to 3 have been disclosed, and proposals have been made to reduce the surface roughness of the release layer surface.

However, for optical applications, for example, high smoothness is required in order to improve transparency. In addition, in electronic component applications such as film capacitor applications, smoothness is required to improve electrical properties such as dielectric breakdown voltage. There was a concern that the film capacitor would not be wound well and the performance of the film capacitor would be degraded due to winding misalignment and wrinkles when winding up.

In order to improve these problems, Patent Document 4 proposes adding specific particles to a resin sheet used for optics such as a polarizing plate to impart slipperiness. Further, 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.

JP 2012-144021 A JP 2014-154273 A JP 2015-182261 A JP 2019-95661 A WO2020/039638

However, in the method of Patent Document 4, since particles are contained in the resin sheet, there is a concern that transparency may be insufficient, such as an increase in internal haze. Moreover, in the method of Patent Document 5, the amount of particles transferred to the resin sheet may become uneven, and there is a concern that the slipperiness may become unstable.
The present invention solves the above problems, and proposes a laminated film capable of providing a resin sheet having both high smoothness and good lubricity without substantially adding particles to the inside of the resin sheet.

As a result of intensive studies by the present inventors, a phase-separated structure on the surface of the laminated film is obtained by applying a coating liquid containing at least a specific resin and a cross-linking agent under specific conditions on a smooth substrate film, followed by drying and curing. We found that the unevenness caused by this was formed, and succeeded in giving good slipperiness without containing particles.

That is, the present invention consists of the following configurations.
[1] It has a polyester-based base film, a release layer disposed on at least one side of the base film, and a resin sheet disposed on the side of the release layer opposite to the base. ,
A 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 cross-linking agent (B),
(2) the resin sheet contains substantially no particles;
(3) the film thickness (t1) of the resin sheet is 1 μm or more and 20 μm or less;
(4) the surface (1) of the resin sheet has an arithmetic mean height (Sa) of 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 stacking the surface (1) of the resin sheet on the side 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 aspect, the cross-linking agent (B) contained in the resin sheet-forming composition is liquid at 30°C.
[3] In one aspect, the ratio of the cross-linking agent (B) contained in the resin sheet to the entire resin sheet is 10% by mass or more.
[4] In one aspect, the resin component (A) contained in the resin sheet has a weight average molecular weight of 10,000 or more.
[5] In one aspect, the release layer surface has a surface free energy of 40 mJ/m ² or less and an adhesion energy of 3.5 mJ/m ² or more.
[6] In one aspect, the release layer-side surface of the substrate film has an arithmetic mean height (Sa) of 20 nm or less and a maximum projection height (P) of 500 nm or less.
[7] In another embodiment, the present invention provides a method for producing a laminated film according to any one of the above, wherein the method comprises 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 having both high smoothness and good slipperiness, and by using the resin sheet molded by the present invention, it is possible to provide products suitable for various purposes. be able to.

It is a schematic sectional drawing which shows the structure of this invention. It is a schematic sectional drawing explaining the structure of this invention in one aspect|mode.

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

INDUSTRIAL APPLICABILITY For optical applications, for example, the present invention can provide a resin sheet capable of enhancing transparency and the like, and furthermore exhibiting high smoothness. In addition, it was previously difficult to
Both high smoothness and high slipperiness can be achieved, for example, it is possible to suppress the occurrence of scratches during the transportation process, etc., and it is possible to avoid a decrease in yield.
In addition, for example, in electronic component applications such as film capacitor applications, it is possible to provide a resin sheet exhibiting high smoothness, 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 has been difficult in the past.
Good windability can be exhibited. Therefore, the capacitor can be transported while maintaining 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 an increase in internal haze. In addition, it is possible to avoid the problem that the amount of particles transferred to the resin sheet becomes non-uniform, and it is possible to exhibit good slipperiness.

(Base film)
The present invention has a polyester base film. The polyester that constitutes the polyester film used as the base material of the present invention is not particularly limited, and a film formed of polyester that is commonly used as the base material film can be used. Preferably, it is a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate or Further preferred is a copolymer whose main component is the constituent component of the resin. Among others, a polyester film made from polyethylene terephthalate is particularly suitable.
The polyethylene terephthalate preferably contains 90 mol % or more, more preferably 95 mol % or more of repeating units of ethylene terephthalate, and may be copolymerized with other dicarboxylic acid components and diol components in small amounts. From the point of view of cost, one produced only from terephthalic acid and ethylene glycol is preferable. In addition, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallization agents, etc. may be added within limits that do not impair the effects of the film of the present invention. The polyester film is preferably a biaxially oriented polyester film because of its high bidirectional elastic modulus.

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 breakages do not occur in the stretching process. Conversely, when it is 0.70 dl/g or less, the cutting performance is good when cutting into a predetermined product width, and dimensional defects do not occur, which is preferable. Moreover, it is preferable to sufficiently vacuum-dry the raw material pellets.

The method for producing the polyester film in the present invention is not particularly limited, and conventionally generally used methods can be used. For example, the polyester can be melted by an extruder, extruded into a film, cooled by a rotating cooling drum to obtain an unstretched film, and then stretched. The stretching is preferably biaxial stretching from the viewpoint of mechanical properties and the like. The biaxially stretched film can be obtained by a method of sequentially biaxially stretching a longitudinally or laterally uniaxially stretched film in the lateral direction or longitudinal direction, or by a method of simultaneously biaxially stretching an unstretched film in the longitudinal direction and the lateral direction. I can.

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 that the film is stretched 1 to 8 times, particularly 2 to 6 times, in each of the longitudinal and transverse directions.

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 still 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, the release layer processing step, resin sheet molding, and the like. On the other hand, if the thickness of the film is 50 μm or less, the winding diameter when wound into a roll is small, and the winding length of the molded resin sheet can be increased, which is preferable.
When the polyester film as the base film has a multilayer structure described later, the film 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. Preferably, at least one side has a surface layer A which is substantially free of particles. In one aspect, the polyester film, which is the base film, has the surface layer A on the surface facing the resin sheet. When the base film is a laminated polyester film having a multilayer structure of two or more layers, it may have a surface layer B capable of containing particles or the like on the opposite side of the surface layer A substantially free of particles. preferable. As for the laminated structure, the layer on the side where the resin sheet is arranged is the surface layer A, the layer on the opposite side is the surface layer B, and the core layer other than these is the layer C. The layer structure in the thickness direction is A/B, or Laminated structures, such as A/C/B, are mentioned.
The layer C may be composed of multiple layers. Alternatively, 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 impart lubricity for winding the film into a roll.

In the polyester film of the present invention, it is preferred that the surface layer A located on the surface on which the resin sheet is formed substantially does not contain particles. Moreover, 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. 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 a release layer or the like described later is provided 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, when the inorganic elements are quantified by fluorescence X-ray analysis, it is 50 ppm or less, preferably 10 ppm or less, most preferably 10 ppm or less, and most preferably less than the detection limit. means a content of Even if particles are not actively added to the film, contaminants derived from foreign substances, or dirt adhering to the raw material resin or the lines and equipment in the film manufacturing process peel off and enter the film. This is because

The maximum projection height (P) of the surface layer A of the polyester film, that is, the maximum projection height (P) of the release layer side surface of the base film is, for example, 500 nm or less, preferably 200 nm or less, It is more preferably 150 nm or less, still more preferably 100 nm or less, for example 85 nm or less, and 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 the P of the surface layer A of the polyester film is, the more preferable it is. Here, when a release layer, which will be described later, is provided on the surface layer A, the maximum protrusion height (P) after lamination of the release layer is preferably within the above range.

In the polyester film of the present invention, the surface layer B, which forms the opposite surface of the surface layer A, preferably contains particles, particularly silica particles and / or It is preferred to use calcium particles. The content of the particles contained in the surface layer B is preferably 5000 to 15000 ppm in total. At this time, the arithmetic mean height (Sa) of the surface layer B film is preferably in the range of 1 to 40 nm. More preferably, it is in the range of 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, when the film is wound into a roll, air can escape uniformly, resulting in a good roll shape and good flatness. , suitable for the production of resin sheets. Further, when the total amount of silica particles and/or calcium carbonate particles is 15000 ppm or less and Sa is 40 nm or less, aggregation of the lubricant is less likely to occur and coarse projections are not formed.

As the particles contained in the surface layer B, inert inorganic particles and/or heat-resistant organic particles can be used in addition to silica and/or calcium carbonate. Silica particles and/or calcium carbonate particles are more preferably used from the viewpoint of transparency and cost, but other usable inorganic particles include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferable, and when calcium carbonate particles are used, light calcium carbonate surface-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, and particularly preferably 0.5 μm or more and 1.0 μm or less. If the average particle diameter of the particles is 0.1 μm or more, the slipperiness of the substrate film is good, which is preferable. Further, if the average particle size is 2.0 μm or less, it is preferable because there is no possibility that pinholes are generated in the resin sheet due to the coarse particles of the surface layer B.

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

When the surface layer B does not contain particles, it is preferable that a coating layer containing particles on the surface layer B provides lubricity. Although the present coat layer is not particularly limited, it is preferably provided as an in-line coat that is applied during film formation of the polyester film. When the surface layer B does not contain particles and the surface layer B has a coat layer containing particles, 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 1-40 nm. More preferably, it is in the range of 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 inclusion of particles such as lubricants.

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 inside of the film is less likely to be affected by the particles contained in the surface layer B and the like, and the arithmetic mean height (Sa) easily satisfies the above range, which is preferable. When the total thickness of the base film is 50% or less of the total thickness of the base film, the ratio of the recycled raw material used in the surface layer B can be increased, and the environmental load is reduced, which is preferable.

From the viewpoint of economy, the layers other than the surface layer A (the surface layer B or the intermediate layer C described above) may contain 50 to 90% by mass of recycled film scraps and PET bottle raw materials. Even in this case, the type, amount, particle size and arithmetic mean height (Sa) of the lubricant contained in the surface layer B preferably satisfy the above ranges.

In addition, a film before or after uniaxial stretching is applied to the surface of the surface layer A and/or the surface layer B in order to improve the adhesion of a release layer to be applied later or to prevent electrification. A coat layer may be provided on the surface, and corona treatment or the like may be applied. When a coat layer is provided on the surface layer A, the coat layer preferably 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. Resins constituting the release layer are 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. . When the resin sheet to be described later contains a cross-linking agent, it is preferable that the resin sheet contains a silicone resin because the releasability is improved.
In this specification, the substrate and the release layer laminate may be simply referred to as a release film.

The release layer can contain, for example, a silicone resin. Silicone resins are resins having a silicone structure in the molecule, and include curable silicones, silicone graft resins, modified silicone resins such as alkyl-modified silicone resins, and the like. is preferably used. Examples of reactive curable silicone resins that can be used include those of addition reaction type, those of condensation reaction type, and those of ultraviolet or electron beam curable type. More preferably, a low-temperature curing addition reaction system that can be processed at a low temperature and an ultraviolet or electron beam curing system are preferable. By using these materials, the polyester film can be processed at a low temperature during the coating process. Therefore, the polyester film is less thermally damaged during processing, a polyester film with high flatness can be obtained, and defects such as pinholes can be reduced even when a thin resin sheet is produced.

Examples of the addition-reactive silicone resin include those obtained by reacting polydimethylsiloxane having vinyl groups at its terminals or side chains and hydrogen siloxane with a platinum catalyst to cure the resin. At this time, it is more preferable to use a resin that can be cured at 120° C. within 30 seconds because processing can be performed at a low temperature. Examples include low temperature addition cures from Dow Toray (LTC1006L, LTC1056L, LTC300B, LTC303E, LTC310, LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC755, LTC760A, etc.) and thermal UV cures (LT C851, BY24- 510, BY24-561, BY24-562, etc.), solvent addition + UV curing type manufactured by Shin-Etsu Chemical Co., Ltd. (X62-5040, X62-5065, X62-5072T, KS5508, etc.), dual cure curing type (X62-2835, X62- 2834, X62-1980, etc.).

As a condensation reaction type silicone resin, for example, polydimethylsiloxane having an OH group at the terminal and polydimethylsiloxane having an H group at the terminal are subjected to a condensation reaction using an organic tin catalyst to form a three-dimensional crosslinked structure. mentioned.

Examples of UV-curing silicone resins include, for example, the most basic types of resins that use the same radical reaction as in normal silicone rubber cross-linking, those that introduce unsaturated groups for photocuring, and those that decompose onium salts with ultraviolet rays. For example, a strong acid is generated to cleave the epoxy group to cause cross-linking, or a thiol addition reaction to vinylsiloxane causes cross-linking. Also, an electron beam can be used instead of the ultraviolet rays. Electron beams have stronger energy than ultraviolet rays, and can perform a cross-linking reaction by radicals without using an initiator as in the case of ultraviolet curing. Examples of resins used include Shin-Etsu Chemical UV curable silicone (X62-7028A/B, X62-7052, X62-7205, X62-7622, X62-7629, X62-7660, etc.), Momentive Performance Materials UV curable silicone (TPR6502, TPR6501, TPR6500, UV9300, UV9315, XS56-A2982, UV9430, etc.), Arakawa Chemical UV curable silicone (Silicolase UV POLY200, POLY215, POLY201, KF-UV265AM, etc.) ).

Acrylate-modified or glycidoxy-modified polydimethylsiloxane can also be used as the ultraviolet curable silicone resin. Good release performance can also be obtained by mixing these modified polydimethylsiloxanes with polyfunctional acrylate resins, epoxy resins, or the like and using them in the presence of an initiator.

Examples of other resins that can be used include stearyl-modified or lauryl-modified alkyd resins or acrylic resins, or alkyd resins obtained by reaction of methylated melamine, acrylic resins, and olefin resins.

Examples of aminoalkyd resins obtained by reaction of methylated melamine include Tesfine 303, Tesfine 305 and Tesfine 314 manufactured by Hitachi Chemical Co., Ltd. Examples of aminoacrylic resins obtained by reaction of methylated melamine include Tesfine 322 manufactured by Hitachi Chemical Co., Ltd.

When the above resins are used in the release layer of the present invention, one type may be used, or two or more types may be mixed and used. Also, in order to adjust the release force, it is possible to mix additives such as a light release additive and a heavy release additive.

Additives such as an adhesion improver and an antistatic agent may be added to the release layer of the present invention. In order to improve the 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, atmospheric pressure plasma treatment, etc. before providing the release layer.

In the present invention, the thickness of the release layer may be set according to the purpose of use, and is not particularly limited. good. It is preferable that the thickness of the release layer is 0.005 μm or more because the release performance is maintained. In addition, when the thickness of the release layer is 2.0 μm or less, the curing time is not too long, and there is no risk of thickness unevenness of the resin sheet due to deterioration of the flatness of the release film, which is preferable. Moreover, since the curing time does not become too long, there is no risk of aggregation of the resin constituting the release coating layer, and there is no risk of formation of protrusions.

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

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. It is more preferably 35 mJ/m ² or less, and even more preferably 30 mJ/m ² or less. When it is 40 mJ/m ² or less, it is preferable because the peelability of the molded resin sheet is good.
In the present invention, the surface free energy means the surface free energy of at least the surface of the release layer 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. It is more preferably 4.0 mJ/m ² or more, more preferably 5.5 mJ/m ² or more. It is preferable that it is 3.0 mJ/m ² or more because swelling of the coating edge is suppressed when the solution of the resin sheet is applied. Suppressing swelling of the coating edge during coating suppresses ridges when the laminated film is wound into a roll, which improves the appearance of the roll and improves the flatness of the laminated film, which is preferable.

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

In order to improve the water adhesion energy on the surface of the release layer, as a method other than those described above, it is also possible to change the composition of the silicone resin. For example, addition reaction silicone resins can be cured by heating polydimethylsiloxane and hydrogen siloxane having vinyl groups introduced at their terminals or side chains in the presence of a platinum catalyst. -Vy), the water adhesion energy can also be changed by changing the molar amount of Si—H groups in the hydrogensiloxane. For example, the more Si-H than Si-Vy, the higher the water adhesion energy, and the Si-H/Si-Vi ratio is preferably 1.0 or more, more preferably 1.5 or more, 2.0 or more is more preferable.

The release layer of the present invention preferably has an arithmetic mean height (Sa) of 20 nm or less not only for the polyester base material but also for the release layer. 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, still more preferably 100 nm or less, for example 85 nm or less, and 50 nm or less. Especially preferred. 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.

In the present invention, the method for forming the release layer is not particularly limited. is removed by drying, followed by heat drying, heat curing, or ultraviolet curing.

As a method for coating the release layer, any known coating method can be applied, for example, roll coating methods such as gravure coating method and reverse coating method, bar coating methods such as wire bar coating, die coating, spray coating, air A conventionally known method such as a knife coating method can be used.

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, and 140° C. or less. is more preferable, and 120° C. or less is most preferable. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, most preferably 10 seconds or less. When the temperature is 180° C. or lower, the flatness of the film is maintained, and the possibility of causing unevenness in the thickness of the resin sheet is small, which is preferable. When the temperature is 120° C. or lower, the film can be processed without impairing the flatness of the film, and the possibility of causing unevenness in the thickness of the resin sheet is further reduced, which is particularly preferable.
Although the lower limit of the drying temperature is not particularly limited, it is preferably 60° C. or higher. It is preferable because the release film can be obtained without the solvent remaining in the release layer at 60° C. or higher.

When an ultraviolet 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 90° C. or less. is most preferred. The heating time is preferably 30 seconds or less, more preferably 20 seconds or less, most preferably 10 seconds or less. When the temperature is 120° C. or lower, the flatness of the film is maintained, and the possibility of causing unevenness in the thickness of the resin sheet is small, which is preferable. When the temperature is 90° C. or lower, the film can be processed without impairing the flatness of the film, and the possibility of causing unevenness in the thickness of the resin sheet is further reduced, which is particularly preferable.
Although the lower limit of the drying temperature is not particularly limited, it is preferably 60° C. or higher. It is preferable because the release film can be obtained without the solvent remaining in the release layer at 60° C. or higher.

When an ultraviolet curable material is used for the release layer, it is preferable to irradiate an active energy ray to cause a curing reaction after drying the solvent. As the active energy rays to be used, known techniques such as ultraviolet rays and electron beams can be used, and ultraviolet rays are preferably used. The integrated amount of light when ultraviolet rays are used can be expressed as the product of the illuminance and the irradiation time. For example, it is preferably 10 to 500 mJ/cm ² . It is preferable to make the release layer more than the lower limit because the release layer can be sufficiently cured. It is preferable that the thickness is not more than the above upper limit because it is possible to suppress thermal damage to the film due to heat during irradiation and to maintain the smoothness of the surface of the release layer.

(resin sheet)
The laminated film of the present invention has a resin sheet arranged on the surface of the release layer opposite to the substrate.
For example, the resin sheet laminated on the release film of the present invention is obtained by curing a resin sheet-forming composition containing at least the resin component (A) and the cross-linking agent (B).
As a result of intensive studies, the resin sheet of the present invention is produced under specific conditions described later, for example, from the resin sheet-forming composition according to the present invention. It is possible to harden the resin sheet at 100 rpm, form appropriate irregularities on the surface of the resin sheet, and exhibit slipperiness of the resin sheet without containing particles or the like in the resin sheet.

The total mass ratio of the resin component (A) and the cross-linking agent (B) accounts for preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more of the solid content of the entire resin sheet. . When the content is 80% by mass or more, physical properties such as strength and heat resistance of the resin sheet are improved, which is preferable.

The mass ratio of the resin component (A) and the cross-linking agent (B) is preferably (A)/(B)=90/10 to 50/50. When the blending ratio of the cross-linking agent (B) is 10% by mass or more, unevenness tends to increase after phase separation, and slipperiness is improved, which is preferable. If the blending ratio of the cross-linking agent (B) is 50% by mass or less, the film strength of the resin sheet does not decrease, and the handling property as a sheet is excellent, which is preferable. Blocking with the back side can also be prevented. For example, the ratio of the cross-linking agent (B) contained in the resin sheet to the entire resin sheet is preferably 10% by mass or more and 50% by mass or less. In one aspect, the ratio of the cross-linking agent (B) contained in the resin sheet 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 cross-linking agent (B) under such conditions, the above effects can be exhibited more favorably.

The resin component (A) is not particularly limited, and known resins can be used. For example, epoxy-based resins, phenoxy-based resins, polyester-based resins, urethane-based resins, fluorine-based resins, acrylic-based resins, olefin-based resins, imide-based resins, sulfone-based resins, etc. can be used. Two or more types may be mixed and used. 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. When it is 10000 or more, the strength of the resin sheet is high and the handleability is good, which is preferable. When it is 200,000 or less, the viscosity of the solution becomes low and the productivity is improved when solution film formation is performed, which is preferable. Although the method for measuring the weight average molecular weight (Mw) is not particularly limited, it can be measured using GPC or the like.

The cross-linking agent (B) is not particularly limited, and known cross-linking agents can be used. For example, a cross-linking agent such as isocyanate, melamine, carbodiimide, oxazoline, or the like can be used, and either one kind or a mixture of two or more kinds can be used. It is preferably one that reacts with the functional groups contained in the resin component (A). The cross-linking agent (B) contained in the resin sheet-forming composition is preferably liquid at 30°C. In the present invention, the term "liquid" may be used as long as it has fluidity and, for example, a viscosity of 10000 mPa·s or less. Being a liquid at 30° C. is preferable because phase separation from the resin component (A) can be effectively promoted during drying of the solution casting of the resin sheet, and surface unevenness of the resin sheet is likely to occur.

The resin sheet may contain additives other than the resin component (A) and the cross-linking agent (B) as long as the above range is satisfied. However, the resin sheet is substantially free of particles. Since the resin sheet according to the present invention does not substantially contain particles, for example, in the case of optical applications, the effect of increasing the transparency of the molded resin sheet, the effect of increasing the transparency of the molded resin sheet, and the electronic properties 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 may have a haze of 2% or less. Also, the haze may be 1% or less. In one aspect, the resin sheet has a haze of 0.1% or more. In the case of an electronic component such as a film capacitor, the resin sheet may have a dielectric breakdown voltage of 200 V/μm or more. Also, the dielectric breakdown voltage may be 300 V/μm or more. In one aspect, the breakdown voltage is 500 V/μm or less.

Even if the resin sheet of the present invention does not substantially contain particles, it has fine irregularities on the surface thereof resulting from phase separation between the resin component (A) and the cross-linking agent (B), and therefore exhibits good slipperiness. can have The coefficient of static friction of the resin sheet separated from the base 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 the resin sheet has good windability, running property, etc., and is easy to handle when used as an optical application or an electronic component application. The static friction coefficient of the resin sheet may be 0.1 or more.
In one embodiment, in FIG. 2, the surface (1) of the resin sheet opposite to the release layer indicated by reference numeral 13 and the surface (2) of the resin sheet indicated by reference numeral 14 are overlapped and measured. is 1.5 or less. The coefficient of static friction measured under the above conditions is more preferably 1.0 or less, and even more preferably 0.8 or less. Also, the coefficient of static friction may be 0.1 or more.
Thus, the static friction coefficient measured by stacking both sides of the resin sheet is within the above range, so that the resin sheet of the present invention can achieve both high smoothness and excellent windability and runnability. can.

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) has an arithmetic mean roughness (Sa) of 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 slipperiness of the resin sheet is improved, which is preferable. If 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 into a roll, the fear of causing defects such as pinholes is reduced, which is preferable.

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) has a maximum cross-sectional height (St) of 80 nm or more and 1000 nm or less, more preferably 100 nm or more and 600 nm or less. , 150 nm or more and 500 nm or less. When the thickness is 80 nm or more, the slipperiness of the resin sheet becomes good, which is preferable. If the thickness is 1000 nm or less, even when the resin sheet is peeled off from the laminated film and only the resin sheet is wound into a roll, the fear of causing defects such as pinholes is reduced, which is preferable.
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 projection height (P) on 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. More preferably, it 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 do not occur even when the resin sheet is peeled from the laminated film and the resin sheet alone is wound into a roll. Although it can be said that the smaller the maximum projection 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 the maximum cross-sectional height (St) of the surface (1) of the resin sheet of the laminated film of the present invention within the ranges described above, good lubricity 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 aspect, 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. 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. It 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 into a roll, the fear of causing defects such as pinholes is reduced, 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. It is more preferably 1 μm or more and 10 μm or less, and still more preferably 2 μm or more and 8 μm or less. If the film thickness (t1) of the resin sheet is 1 μm or more, it is preferable because it is difficult to break even after peeling from the base film and can be easily handled. If the film thickness (t1) of the resin sheet is 20 μm or less, the wet coating film thickness does not become too thick during solution film formation, and molding is easy, which is preferable.

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, a cross-section can be observed and measured by 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 resin component (A) and the cross-linking agent (B) described above and dissolved or dispersed in an organic solvent or water is subjected to a solution film forming method. It is preferably formed on the release layer by pressing, and can be applied by a known method similar to the method for applying the release layer. For example, conventionally known methods such as roll coating such as gravure coating and reverse coating, bar coating such as wire bar coating, die coating, spray coating and air knife coating can be used.

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, or the like. The laminated film of the present invention is preferably applied and dried by roll-to-roll, and it is particularly preferred that the drying oven uses a floating method or a roll support method and uses hot air to dry.

As for the temperature during drying, 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, even more preferably 70° C. or higher and 130° C. or lower. If the drying temperature is 60° C. or higher, there is little residual solvent in the resin sheet after drying, and there is no possibility that the performance of the resin sheet (for example, the electrical properties in the case of dielectric layers) is lowered, which is preferable. If it is 160° C. or lower, it is preferable because there is no concern that wrinkles will occur in the laminated film due to heat. On the other hand, if the temperature is higher than 160°C, the phase separation between the resin component and the cross-linking agent in the resin sheet may proceed too much and the cross-linking density of the resin sheet may decrease.

The time from the application of the coating solution to the base film until entering the drying oven is preferably within 5 seconds, more preferably within 3 seconds, and even more preferably within 2 seconds. When the time is within 5 seconds, phase separation between the resin component and the cross-linking agent in the coating liquid does not proceed excessively, and there is no concern that the cross-linking density of the resin sheet will decrease, which is preferable.

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 longer, preferably 2 seconds or longer. A time of 1 second or more is preferable because the reaction of the cross-linking 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 time is within 60 seconds, it is possible to prevent the segregation of the cross-linking agent on the surface of the resin sheet from progressing too far, and the performance of the resin sheet is not deteriorated, which is preferable.

By subjecting the resin sheet of the present invention to the above drying conditions, the phase separation of the resin component (A) and the cross-linking agent (B) is moderately progressed, and the arithmetic average roughness (Sa) of the resin sheet surface (1) and The maximum cross-sectional height (St) can be controlled within the range described above, and good lubricity of the resin sheet can be exhibited 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. It is more preferably 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 peel force varies depending on the resin sheet to be laminated, it can be adjusted according to the type of the release layer of the base film.

EXAMPLES 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 methods used in the present invention are as follows.

(Arithmetic mean 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 profile measurement system (VertScan R550H-M100 manufactured by Ryoka Systems Co., Ltd.). The arithmetic average height (Sa) adopts the average value of 5 measurements, the maximum protrusion height (P) and the maximum valley depth (V) are measured 7 times, and the maximum and minimum values are excluded. Maximum value used. As the maximum cross-sectional height (St), a value obtained by adding the absolute values of the maximum protrusion height (P) and the maximum valley depth (V) was adopted.
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 10x ・0.5×Tube lens ・Measurement area: 936 μm×702 μm
(analysis conditions)
・Surface correction: 4th order correction ・Interpolation processing: Complete interpolation ・Filter processing: Gaussian cutoff value 50 μm

(Surface free energy)
Water (drop volume 1.8 μL) 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. , a droplet of diiodomethane (appropriate amount of liquid: 0.9 μL) was prepared, and the contact angle was measured. As 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 are calculated from the "Owens and Wendt" theory, and the dispersion component γd of the surface free energy of the release film, the component γh based on hydrogen bonding and dipole-dipole interaction was obtained, and the surface free energy γs was obtained by summing each component. This calculation was performed using the analysis software in this contact angle meter software (FAMAS).

(water adhesion energy)
Water (drop volume 10 μL) is 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) under the conditions of 25 ° C. and 50% RH. Two seconds after the dropping, the stage was continuously tilted and the contact angle was measured every 1°. Also, the inclination angle when the droplet moved 5 dots from the droplet position of 0° was determined as the sliding angle, and the adhesion energy was calculated therefrom. This calculation was performed using the analysis software in this contact angle meter software (FAMAS).

(film thickness)
The cut laminated film was embedded in a resin and cut into ultrathin slices using an ultramicrotome. Then, using a JEOL JEM2100 transmission electron microscope, direct observation was performed at a magnification of 20,000, and the film thickness of each layer of the laminated film was measured from the observed TEM image.

(Peel force)
Cut the laminated film into strips with a width of 25 mm and a length of 150 mm, fix one end of the base film, hold one end of the resin sheet, pull the resin sheet side at a speed of 300 mm / min, and measure the T-peel strength. It was measured. A tensile tester ("AUTOGRAPH AG-X" manufactured by Shimadzu Corporation) was used for the measurement. The average value of 5 measurements was adopted as the measured value.
Based on the measured peel force, the peelability was evaluated according to the following criteria.
○: It was possible to peel with a low peeling force of 100 mN / 25 mm width or less, and even a thin film could be peeled without tearing. Ta.
Δ: Peeling force was greater than 300 mN/25 mm width and could be peeled at 800 mN/25 mm width or less. At the part where the film thickness was extremely thin, part of the film was sometimes torn. ×: The film could not be peeled off.

(Static friction coefficient and slipperiness evaluation)
The coefficient of static friction of the resin sheet was measured as follows to evaluate the slipperiness.
The resin sheet was peeled off from the laminated film and fixed to the bottom surface of a metal rectangular parallelepiped weighing 1.4 Kg so that the surface (2) of the resin sheet faced up. Then, it was fixed on a flat metal plate with an adhesive tape so that the surface (1) of the resin sheet faced up. A metallic rectangular parallelepiped was placed so that the surfaces (1) and (2) were in contact with each other, and the static friction coefficient was measured at a tensile speed of 200 mm/min under conditions of 23°C and 65% RH.
The slipperiness was judged according to the following criteria.
・ : 0.1<μs≦0.8
・ : 0.8<μs≦1.5
×: more than 1.5 or the coefficient of friction is too high to measure

(Electrical characteristics)
A thin aluminum deposition layer was provided on both sides of the resin sheet separated from the base film, and the dielectric breakdown voltage (V/μm) was measured at room temperature. Using the average value of 10 measurements, evaluation was made according to the following criteria.
〇: Dielectric breakdown voltage (BDV value) is 300 V/μm or more △: Dielectric breakdown voltage is 200 V/μm or more ×: Dielectric breakdown voltage is less than 200 V/μm

(Preparation of polyethylene terephthalate pellets (PET (I)))
As the esterification reactor, a continuous esterification reactor comprising 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) was adjusted to 2 tons/hour, EG (ethylene glycol) was adjusted to 2 mol per 1 mol of TPA, and antimony trioxide was adjusted to give an amount of Sb atoms of 160 ppm relative to the produced PET. It was continuously supplied to the first esterification reactor of the reaction apparatus and reacted at 255° C. for an average residence time of 4 hours under normal pressure. Next, the reaction product in the first esterification reaction can is continuously taken out of the system and supplied to the second esterification reaction can, and distilled off from the first esterification reaction can into the second esterification reaction can. 8 mass % of EG is supplied to the produced PET, and further, an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm relative to the produced PET, and an EG solution containing 40 ppm of P atom relative to the produced PET. An EG solution containing TMPA (trimethyl phosphate) in an amount corresponding to the above was added and reacted at 260° C. under normal pressure for an average residence time of 1 hour. Next, the reaction product in the second esterification reactor was continuously taken out of the system and supplied to the third esterification reactor, and was subjected to 39 MPa (400 kg/cm ² ) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). 0.2% by mass of porous colloidal silica having an average particle size of 0.9 μm, which has been subjected to dispersion treatment for an average number of 5 passes at a pressure of , and 1% by mass of ammonium salt of polyacrylic acid per calcium carbonate. While adding 0.4% by mass of synthetic calcium carbonate with a diameter of 0.6 μm as a 10% EG slurry, the mixture was reacted at normal pressure at 260° C. for an average residence time of 0.5 hours. The esterification reaction product produced in the third esterification reaction vessel was continuously supplied to a three-stage continuous polycondensation reactor for polycondensation to sinter stainless steel fibers having a 95% cut diameter of 20 μm. After filtration with a filter, ultrafiltration was performed, the product was extruded into water, and after cooling, it was cut into chips to obtain PET chips having 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 PET chips, PET chips having an intrinsic viscosity of 0.62 dl/g and containing no particles such as calcium carbonate and silica were obtained (hereinafter abbreviated as PET (II)).

(Preparation of polyethylene terephthalate pellets (PET (III)))
Except for changing the type and content of the particles of PET (I) to 0.75% by mass of synthetic calcium carbonate having an average particle size of 0.9 μm, in which 1% by mass of ammonium salt of polyacrylic acid is 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, they were melted at 285° C. and melted at 290° C. by a separate melt extruder extruder to filter sintered stainless steel fibers with a 95% cut diameter of 15 μm and Filtration was performed in two stages using a filter in which 15 μm stainless steel particles were sintered, and the particles were combined in the feed block to laminate PET (I) as surface layer B and PET (II) as surface layer A. , extruded (casting) into a sheet at a speed of 45 m / min, electrostatically adhered on a casting drum at 30 ° C. by an electrostatic adhesion method, and cooled to form an unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.59 dl / g. Obtained. The layer ratio was adjusted so that PET(I)/PET(II)=60%/40% by calculation of the discharge amount of each extruder. Then, the 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. due to the speed difference between the rolls. After that, it was led to 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. Thereafter, a 2.3% relaxation treatment was applied in the transverse direction at 170° C. to obtain a base film X1 of a biaxially oriented polyethylene terephthalate film having a thickness of 25 μm. Sa of the surface layer A of the obtained base film X1 was 2 nm, and Sa of the surface layer B was 29 nm.

(Production of base film X2 having release layer)
On the surface layer A of the substrate film X1 obtained above, the following release coating liquid Y1 is applied by a reverse gravure coating method so that the wet film thickness is 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 release layer surface 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, Inc.)
・ 1 part by mass

(Production of base film X3 having release layer)
The thickness was adjusted by changing the speed during casting without changing the layer structure and stretching conditions similar to those of the base film X1, to create a biaxially stretched polyethylene terephthalate film with a thickness of 12 μm, and the same separation as X2. 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.

(Manufacturing method of base film X4 having release layer)
As the base film X4, 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. 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 in-line 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.

(Manufacturing method of base film X5 having release layer)
As the base film X5, a release layer similar to X2 was provided on the surface layer A of E5101 (Toyobo Ester (registered trademark) film, manufactured by Toyobo Co., Ltd.) having a thickness of 25 μm. E5101 is configured with particles 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.

(Manufacturing method of base film X6 having release layer)
On the surface layer A of the base film X1, the following release coating liquid Y2 is applied by a reverse gravure coating method so that the wet film thickness is 5 μm, dried and cured in a hot air drying oven at 120° C. for 30 seconds, and released. A layered base film X6 was obtained. Sa on the release layer surface 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, Inc.)
0.1 part by mass

(Manufacturing method of base film X7 having release layer)
On the surface layer A of the base film X1, the following release coating liquid Y3 is applied by a reverse gravure coating method so that the wet film thickness is 5 μm, dried and cured in a hot air drying oven at 120° C. for 30 seconds, and released. A layered base film X7 was obtained. Sa on the release layer surface 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, Inc.)
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 applied so that the film 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 to prepare a laminated film. (At this time, it took two 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 is 5.3 parts by mass of Millionate MR-200 prepared by dissolving phenoxy resin in tetrahydrofuran (manufactured by Tosoh Corporation, isocyanate cross-linking agent, viscosity 200 mPa s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone-based surfactant)

(Examples 2-3)
A laminated film was prepared in the same manner as in Example 1, except that the substrate 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 a 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 is 5.3 parts by mass of Millionate MR-200 prepared by dissolving phenoxy resin in tetrahydrofuran (manufactured by Tosoh Corporation, isocyanate cross-linking agent, viscosity 200 mPa s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone-based 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 cross-linking 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 is 5.3 parts by mass of Millionate MR-400 prepared by dissolving phenoxy resin in tetrahydrofuran (manufactured by Tosoh Corporation, isocyanate cross-linking agent, viscosity 600 mPa s, solid content 99 mass%)
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone-based surfactant)

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

(Example 7)
A laminated film was prepared in the same manner as in Example 1, except that the resin solution Z4 was used to change the ratio of the resin and the cross-linking 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 3.5 parts by mass of Millionate MR-200 prepared by dissolving phenoxy resin in tetrahydrofuran (manufactured by Tosoh Corporation, isocyanate cross-linking agent, viscosity 200 mPa s, solid content 99 mass%).
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone-based surfactant)

(Example 8)
A laminated film was produced in the same manner as in Example 1, except that the resin solution Z5 was used to change the ratio of the resin and the cross-linking 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 1.8 parts by mass of Millionate MR-200 prepared by dissolving phenoxy resin in tetrahydrofuran.
BYK-370 0.4 parts by mass (manufactured by BYK-Chemie Japan, silicone-based surfactant)

(Examples 9-11)
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 shown in Table 1.

(Comparative example 1)
A laminated film was prepared in the same manner as in Example 1, except that the base film was changed to X1 having no 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 cross-linking 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 is BYK-370 0.4 parts by mass prepared by dissolving phenoxy resin in tetrahydrofuran (manufactured by BYK-Chemie Japan, silicone-based surfactant)

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

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

The laminated sheets of the present invention obtained in Examples are resin sheets capable of enhancing transparency and the like in optical applications, and furthermore, can provide resin sheets exhibiting high smoothness. Moreover, both high smoothness and high slipperiness can be achieved, so that, for example, it is possible to suppress the occurrence of scratches during the transportation process, etc., and to avoid a decrease in yield.
In addition, for example, in electronic component applications such as film capacitor applications, it is possible to provide a resin sheet exhibiting high smoothness, 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, for example, it is possible to suppress winding misalignment and inclusion of wrinkles when winding a dielectric resin sheet on a roll, and it is possible to exhibit good windability. . Therefore, the capacitor can be transported while maintaining excellent capacitor performance.
Furthermore, the resin sheet obtained by the present invention does not substantially contain particles, and it is possible to avoid insufficient transparency such as an increase in internal haze. In addition, it is possible to avoid the problem that the amount of particles transferred to the resin sheet becomes non-uniform, 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 release property of the resin sheet was extremely poor, and the resin sheet could not be evaluated. Comparative Example 2 showed that the slipperiness of the resin sheet was particularly poor because the resin sheet-forming composition did not contain a cross-linking 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, so the result was that the slipperiness of the resin sheet was particularly poor.

TECHNICAL FIELD The present invention relates to a laminated film obtained by laminating resin sheets. In particular, the present invention relates to a laminated film obtained by laminating resin sheets used for electronic parts and optical applications.

10 Base film 11 Release layer 12 Resin sheet 13 Resin sheet surface (1)
14 Resin sheet surface (2)

Claims (8)

A polyester-based base film, a release layer disposed on at least one side of the base film, and a resin sheet disposed on the side of the release layer opposite to the base,
The base film has a surface layer A that does not substantially contain particles and a surface layer B on the opposite side of the surface layer A,
The arithmetic mean height (Sa) of the film of the surface layer B is 40 nm or less,
Laminated films that meet the following :
The resin sheet is obtained by curing a resin sheet-forming composition containing at least a resin component (A) and a cross-linking agent (B),
The resin component (A) contains a phenoxy resin,
The cross-linking agent (B) is an isocyanate,
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 release layer surface and a surface (2) of the resin sheet on the release layer side is 1.5 or less. 2. The laminate film according to claim 1, wherein the surface (1) of the resin sheet has an arithmetic mean height (Sa) of 2 nm or more and 30 nm or less. The laminated film according to claim 1, wherein the cross-linking agent (B) contained in the resin sheet-forming composition is liquid at 30°C. 2. The laminated film according to claim 1 , wherein the ratio of the cross-linking agent (B) contained in the resin sheet to the entire resin sheet is 10% by mass or more. 2. 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. 2. The laminate film according to claim 1 , wherein the release layer surface has a surface free energy of 40 mJ/m ² or less and a water adhesion energy of 3.5 mJ/m ² or more. 2. The laminated film according to claim 1 , wherein the release layer-side surface of the substrate film has an arithmetic mean height (Sa) of 20 nm or less and a maximum protrusion height (P) of 500 nm or less. A method for producing a laminated film according to any one of claims 1 to 7 ,
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 .