Release film

Abstract

To provide a release film which has a low environmental load and is excellent in peelability.SOLUTION: A release film has an antistatic layer, a polyester film as a base material, and a release layer in this order, wherein the release layer is a layer formed on the base material, the release layer is formed from a coating liquid forming the release layer, the coating liquid contains a UV curable type silicone resin, intrinsic viscosity of the base material film is 0.50 to 0.90 dl / g, thickness thereof is 10 μm or more and 188 μm or less, and thickness of the release layer is 0.001 μm or more and 1.5 μm or less, the antistatic layer is formed from a coating liquid for an antistatic layer, and the coating liquid for the antistatic layer contains a polymer antistatic agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a release film for producing all-solid-state battery materials. [Background technology]

[0002] In recent years, with the widespread use of information-related devices and communication devices such as mobile phones and personal computers, as well as the rapid expansion and development of IoT (Internet of Things) devices and wearable devices, development of rechargeable batteries to be used as power sources has been progressing. The automotive industry is also placing importance on the development of high-output, high-capacity batteries for use in electric and hybrid vehicles. While various types of batteries, such as nickel-metal hydride batteries and lithium-ion batteries, have been considered, lithium-ion batteries have recently attracted particular attention due to their high energy density and output.

[0003] A typical lithium-ion battery is composed of a positive electrode, which combines a positive electrode active material layer containing a positive electrode active material with a positive electrode current collector layer that collects current from the positive electrode active material layer; a negative electrode, which combines a negative electrode active material layer containing a negative electrode active material with a negative electrode current collector layer that collects current from the negative electrode active material layer; an electrolyte layer that transports lithium ions; and a separator layer that separates the positive and negative electrodes to prevent short circuits between the electrodes and contains an electrolyte solution in its porous structure, forming paths for the transport of lithium ions.

[0004] The electrolyte of a lithium-ion secondary battery is typically composed of an electrolyte salt and an organic solvent. The organic solvent must have a high dielectric constant to dissolve the electrolyte at a high concentration and a low viscosity to facilitate the rapid migration of lithium ions. Examples of suitable organic solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and mixtures of these and other organic solvents. Because these organic solvents are flammable, safety precautions are essential to prevent fires caused by overcharging the battery or short circuits due to lithium dendrite formation, as well as fires caused by leakage.

[0005] As one of the safety measures, research into all-solid-state batteries, such as all-solid-state lithium secondary batteries, which use sulfide-based or oxide-based solid electrolytes instead of organic solvents, is currently being actively conducted.

[0006] All-solid-state batteries are obtained, for example, by forming each of the layers (solid electrolyte layer, positive electrode active material layer, negative electrode active material layer, current collector layer, and insulating layer) into a thin plate by coating or printing a mixed slurry of powdered components mixed with a binder, solvent, etc. onto a carrier film such as PET that has been treated for release, drying the film, and then pressing the resulting material together. In this process, copper or aluminum foil may be used for the current collector layer, and some layers may be formed directly on copper or aluminum foil.

[0007] All-solid-state batteries can also be produced by a green sheet method used in laminated ceramic technologies such as LTCC (Low Temperature Co-Fired Ceramics) and HTCC (High Temperature Co-Fired Ceramics). A green sheet is a sheet that is made by mixing ceramic powder of a specific composition with a binder, a solvent, etc. to produce a homogeneous slurry, which is then coated or printed, dried, and then fired. A method for producing this green sheet has been described in which the slurry is coated on a release film such as PET as a carrier film, and the film is peeled off after drying (see, for example, Patent Documents 1 and 2).

[0008] Specifically, Patent Document 1 describes a method for producing an ion-conductive solid electrolyte by firing a green sheet containing an inorganic compound powder and an organic binder that exhibits lithium ion conductivity at least after heat treatment, the method comprising: a slurry production step of mixing the inorganic compound powder and the organic binder to produce a slurry; a coating step of applying the slurry to a carrier film to produce a coating film; a drying step of drying the coating film; a peeling step of peeling the coating film from the carrier film to produce a green sheet; and a lamination step of laminating the green sheets to produce a laminate, wherein the moisture content of the coating film immediately after the peeling step is 0.1 to 5%. However, in the means for solving the problems and examples of this document, it is also described that in producing a green sheet for a solid electrolyte, the slurry is cast onto a PET film that has been subjected to a release treatment using a doctor blade.

[0009] Patent Document 2 also describes a method for manufacturing an all-solid-state battery including an electrode active material layer and a solid electrolyte layer, the method including at least one of a step of applying and drying a solid electrolyte slurry in which at least a solid electrolyte and a binder are dispersed in a solvent to form a solid electrolyte sheet, and a step of applying and drying an active material slurry in which at least an electrode active material and a binder are dispersed in a solvent to form an electrode active material sheet, wherein at least one of the solid electrolyte slurry and the active material slurry contains, as the solvent, a first solvent and a second solvent having a boiling point higher than that of the first solvent. However, the background art, detailed description, and examples of this document state that a PET film that has been subjected to a release treatment is used. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-108882 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-243472 Summary of the Invention [Problem to be solved by the invention]

[0011] As described in the documents, these conventional technologies focus on suppressing defects and tears in the green sheet when it is peeled from the release-treated PET film after drying. To achieve this, Document 1 controls the moisture content of the dried green sheet and the environment in which the green sheet is placed, while Document 2 controls the solvent composition of the slurry. However, they have not focused on another important factor, the peeling characteristics of the carrier film.

[0012] Furthermore, in recent years, as indicated in Target 12.5 of the SDGs (Sustainable Development Goals) (by 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse), reducing the environmental impact of production activities has become an urgent issue. However, in the background art, attention has not been paid to reducing the amount of release film used as a carrier film.

[0013] The present invention provides a release film used in producing a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer, which are materials for an all-solid-state battery. The release film reduces the environmental load by suppressing the intrinsic viscosity of the polyester film, the thickness of the substrate, and the thickness of the release layer, while also providing good releasability for each layer sheet formed on the release film. [Means for solving the problem]

[0014] As a result of extensive research to solve the above problems, the present inventors have found that the above object can be achieved by a method for producing a release film having the following configuration, and have completed the present invention. That is, the present invention comprises the following: 1. A release film for use in the production of all-solid-state battery materials, which comprises a polyester film as a base material and a release layer provided on at least one side thereof, wherein the base film has an intrinsic viscosity of 0.50 to 0.90 dl / g, a thickness of 10 μm or more and 188 μm or less, and the thickness of the release layer is 0.001 μm or more and 1.5 μm or less. 2. The release film for producing an all-solid-state battery material according to claim 1, wherein the thickness of the base film is 12 μm or more and 100 μm or less, the intrinsic viscosity is 0.52 to 0.62 dl / g, and the thickness of the release layer is 0.002 μm or more and 1.0 μm or less. 3. The release film for producing an all-solid-state battery material according to claim 1 or 2, characterized in that the thickness of the base film is 15 μm or more and 50 μm or less, and the thickness of the release layer is 0.003 μm or more and 0.60 μm or less. 4. The release film for producing an all-solid-state battery material according to any one of items 1 to 3, wherein the thickness of the base film is 19 μm or more and 40 μm or less, and the thickness of the release layer is 0.004 μm or more and 0.50 μm or less. 5. The amount of silicone extracted by hexane from the release film is 3 mg / m 2 5. A release film for producing an all-solid-state battery material according to any one of claims 1 to 4, characterized in that: 6. The amount of silicone extracted by hexane from the release film is 2 mg / m 2 6. A release film for producing an all-solid-state battery material according to any one of claims 1 to 5, characterized in that: 7. The amount of silicone extracted by hexane from the release film is 1 mg / m 2 7. A release film for producing an all-solid-state battery material according to any one of claims 1 to 6, characterized in that: 8. The release film for producing an all-solid-state battery material according to any one of items 1 to 7, wherein an antistatic layer is provided on at least one surface of the release film. 9. The release film for producing an all-solid-state battery material according to claim 8, wherein an antistatic layer and a release layer are laminated in this order on at least one surface of the base film. 10. The release film for producing an all-solid-state battery material according to item 8 or 9, characterized in that the thickness of the antistatic layer is 0.001 μm or more and 1.0 μm or less. 11. A release film for producing an all-solid-state battery material according to any one of items 8 to 10, wherein the thickness of the antistatic layer is 0.002 μm or more and 0.50 μm or less. 12. A solid electrolyte layer for an all-solid-state battery, produced using the release film for producing an all-solid-state battery material according to any one of items 1 to 11. 13. A positive electrode active material layer for an all-solid-state battery, produced using the release film for producing an all-solid-state battery material according to any one of items 1 to 11. 14. A negative electrode active material layer for an all-solid-state battery, produced using the release film for producing an all-solid-state battery material according to any one of items 1 to 11. 15. A current collector layer for an all-solid-state battery, produced using the release film for producing an all-solid-state battery material according to any one of items 1 to 11. 16. An insulating layer for an all-solid-state battery, produced using the release film for producing an all-solid-state battery material according to any one of items 1 to 11. 17. An all-solid-state battery manufactured using at least any one of the materials described in paragraphs 12 to 16. [Effects of the Invention]

[0015] According to the present invention, it has become possible to provide a release film that can be used to produce a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, an insulating layer of an all-solid-state battery, and an all-solid-state battery manufactured using any of these materials, which simultaneously achieves a reduction in the environmental load by suppressing both the thickness of the polyester film substrate and the thickness of the release layer, and the releasability of each layer sheet formed on the release film. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an all-solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0017] As a result of intensive research to solve the above problems, the present inventors have found a release film for use in producing an all-solid-state battery material, which has at least a polyester film as a substrate and a release layer provided on at least one side thereof, wherein the substrate film has an intrinsic viscosity of 0.50 to 0.90 dl / g, a thickness of 10 μm or more and 188 μm or less, and a thickness of the release layer of 0.001 μm or more and 1.5 μm or less. The present invention will be described in detail below.

[0018] (polyester film) In the present invention, the polyester constituting the polyester film used as the substrate is not particularly limited. Films of polyesters commonly used as substrates for release films can be used. However, preferred are crystalline linear saturated polyesters composed of aromatic dibasic acid components and diol components. For example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or copolymers primarily composed of these resin components are more preferred, with polyester films formed from polyethylene terephthalate being particularly preferred. The polyethylene terephthalate preferably contains 90 mol% or more, more preferably 95 mol% or more, of ethylene terephthalate repeating units. While small amounts of other dicarboxylic acid components and diol components may be copolymerized, from a cost perspective, polyethylene terephthalate produced solely from terephthalic acid and ethylene glycol is preferred. Furthermore, known additives, such as antioxidants, light stabilizers, UV absorbers, and crystallization agents, 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 due to its high bidirectional elastic modulus.

[0019] (Intrinsic viscosity of polyester film) The intrinsic viscosity of the polyester film is an important requirement of the present invention, which is related to reducing the environmental impact. It must be 0.50 to 0.90 dL / g, and more preferably 0.52 to 0.62 dL / g. When the intrinsic viscosity is 0.50 dL / g or higher, breakage during the stretching process can be suppressed. On the other hand, when the intrinsic viscosity is 0.90 dL / g or lower, an increase in back pressure during the melting process can be suppressed, enabling extrusion at the desired production volume and further suppressing the promotion of thermal degradation due to shear heat generation.

[0020] The method for producing the polyester film of the present invention is not particularly limited, and any conventionally used method can be used. For example, the polyester can be melted in an extruder, extruded into a film, and cooled on a rotating cooling drum to obtain an unstretched film, which can then be biaxially stretched. A biaxially stretched film can be obtained by sequentially biaxially stretching a uniaxially stretched film in the longitudinal or transverse direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions.

[0021] In the present invention, the stretching temperature during stretching of the polyester film is preferably equal to or higher than the second-order transition point (Tg) of the polyester, and the stretching is preferably 1 to 8 times, particularly 2 to 6 times, in both the longitudinal and transverse directions.

[0022] (Thickness of polyester film) The thickness of the polyester film is an important requirement of the present invention, which is related to reducing the environmental impact. Specifically, the thickness must be 10 μm or more and 188 μm or less, preferably 12 μm or more and 100 μm or less, more preferably 15 μm or more and 50 μm or less, and even more preferably 19 μm or more and 40 μm or less. A film thickness of 10 μm or more can suppress deformation due to heat during the production of the base film or during the processing step of the release layer. On the other hand, a film thickness of 188 μm or less can reduce the environmental impact, prevent the rigidity of the entire release film from increasing, and allow the polyester film to deform appropriately, particularly when peeling off the thin layer sheets from the release film, suppressing the concentration of deformation on the layer sheets, and avoiding the risk of tearing, cracking, or cracking in the layer sheets.

[0023] The polyester film substrate may be a single layer or a multilayer structure consisting of two or more layers. An example of a multilayer structure is one in which a surface layer A substantially free of particles is provided on the lamination surface side of each layer sheet formed on a release film. In the case of a laminated polyester film having such a structure, it is preferable to provide a surface layer B, which may contain particles, on the surface opposite the substantially particle-free surface layer A. The layer structure in the thickness direction may be a layer structure such as release layer / A / B or release layer / A / C / B, where the layer on the side to which the release layer is applied is surface layer A, the layer opposite surface layer B is surface layer B, and the other core layer is layer C. Naturally, layer C may be a multilayer structure. Furthermore, surface layer B may not contain particles. In this case, it is preferable to provide a coating layer containing particles and a binder on surface layer B to impart slip properties for winding the film into a roll.

[0024] In the polyester film substrate of the present invention, in the case of a single-layer structure or, as an example of a multilayer structure, in which a surface layer A substantially containing no particles is formed on the laminated surface side of each layer sheet formed on a release film, the surface layer B forming the surface opposite to the surface to which the release layer is applied preferably contains particles having an average particle size of 0.01 to 10 μm in a proportion of 0.005 to 5 wt % in particular, from the viewpoints of film slipperiness and ease of air escape. In addition to silica and / or calcium carbonate, inert inorganic particles and / or heat-resistant organic particles can be used as the particles. From the viewpoints of transparency and cost, silica particles and / or calcium carbonate particles are more preferred, but other usable inorganic particles include alumina-silica composite oxide particles and hydroxyapatite particles. Examples of heat-resistant organic particles include cross-linked polyacrylic particles, cross-linked polystyrene particles, and benzoguanamine particles. When silica particles are used, porous colloidal silica is preferred. When calcium carbonate particles are used, precipitated calcium carbonate surface-treated with a polyacrylic acid-based polymer compound is preferred from the viewpoint of preventing particle shedding. Each of the layers may contain two or more types of particles made of different materials, or may contain particles of the same type but with different average particle sizes.

[0025] When the surface layer B does not contain particles, it is preferable to provide slipperiness by a coating layer containing particles on the surface layer B. This coating layer is not particularly limited, but it is preferably provided by in-line coating, in which the coating layer is applied during the production of the polyester film.

[0026] Furthermore, from an economical standpoint, in the case where the polyester film substrate is a single layer or where the laminated surface of each layer sheet formed on a release film has a surface layer A that is substantially free of particles, 50 to 90% by mass of recycled raw materials such as film scraps or PET bottles can be used for the layers other than the surface layer A (surface layer B or the aforementioned intermediate layer C).

[0027] (Release layer) The release film of the present invention is the polyester film having a release layer formed on at least one side thereof. The release layer may be provided on only one side or on both sides. When the release layer is provided on only one side, a layer such as a lubricating layer may be provided on the opposite side as needed.

[0028] (Release agent component) The release layer of the present invention can be made from any combination of silicone-based release agents, alkyd-based release agents, olefin resin-based release agents, fluorine-based release agents, alkyl-based release agents, combinations of these, those cured with crosslinking agents, UV / electron beam curable resins, and those made by curing and polymerizing a monomer component polymerizable by UV / electron beams with UV / electron beams, as well as combinations of other resins and binder resins. In addition to the resins and compounds described above, other components such as adhesion improvers, antistatic agents, antioxidants, fillers, colorants, and UV inhibitors can also be added within the scope of the present invention, provided that the effects of the present invention are not impaired. Furthermore, for crosslinking agents, curable resins, and other components that undergo a reaction to form the release layer, a catalyst can of course be used to promote the reaction.

[0029] The release layer in the present invention may contain particles, but from the viewpoint of suppressing pinholes and surface irregularities in the all-solid-state battery material, the particle size is preferably 1 μm or less.

[0030] (Silicone release agent) The silicone-based release agent used in the release layer in the present invention is a compound having a silicone structure in its molecule, and is not particularly limited as long as it can obtain the effects of the present invention. For example, polyorganosiloxanes, such as polydimethylsiloxane (abbreviated as PDMS), modified polyorganosiloxanes in which a portion has been modified with, for example, an ether compound or a functional group, and even among modified polyorganosiloxanes, those having reactive functional groups and a structure that hardens when reacted with ultraviolet light, electron beams, or heat, or when used in combination with a crosslinking agent, can be suitably used.

[0031] (Alkyd release agent) The alkyd-based release agent used in the release layer in the present invention is a compound obtained by condensing a polyhydric alcohol and a polybasic acid, and is not particularly limited as long as the effects of the present invention can be obtained, and for example, a compound consisting of only a polyhydric alcohol and a polybasic acid, or a compound partially modified with a fatty acid such as myristic acid, palmitic acid, stearic acid, or behenic acid can be suitably used. These resins can be used alone or in combination, and further, these resins can be crosslinked or combined with a melamine resin, a benzoguanamine resin, a glycoluril resin, an epoxy resin, or the like in order to be used as a binder resin.

[0032] (olefin resin release agent) The olefin resin-based release agent used in the release layer of the present invention can be produced by applying a solution of an olefin resin to the surface of a polyester film as a substrate, followed by drying. Suitable olefin resin release agents include those that have an olefin structure in the main chain, such as ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, and ethylene-1-octene copolymers, and are soluble in low-boiling, commonly used solvents such as toluene and methyl isobutyl ketone, or in water, or are water-dispersible. These can be used alone or in combination.

[0033] (Fluorine-based release agent) The fluorine-based release agent used in the release layer of the present invention is a compound containing fluorine in the molecule. There are no particular limitations on the type of fluorine compound, provided that the effects of the present invention can be achieved. Any fluorine compound commonly used in release agents can be used. Examples of such fluorine compounds include polymers (including oligomers) made of fluorine-containing vinyl polymerizable monomers or copolymers thereof, copolymers of fluorine-containing vinyl polymerizable monomers and fluorine-free vinyl polymerizable monomers, and mixtures thereof, each containing 5 to 80 mol% fluorine atoms. Among these release agents, those having reactive functional groups and structures that cure when exposed to ultraviolet light, electron beams, or heat, or when used in combination with a crosslinking agent, can also be suitably used.

[0034] (Method for forming release layer) In the present invention, the means for forming the release layer is not particularly limited, and any method can be selected, such as a method in which a coating liquid containing a release agent and a solvent is applied to the surface of a substrate film by a coating method and the solvent is then dried and removed, a method in which when a curable component is used, the solvent is simultaneously cured by applying heat to dry and remove the solvent, a method in which the solvent is dried and then further heated to cure, a method in which the solvent is dried and then removed and then cured by irradiation with ultraviolet light or an electron beam, or a method in which a liquid resin is used without using a solvent in the coating liquid and the coating is cured by applying heat or irradiating with ultraviolet light or an electron beam without drying and removing the solvent after coating.As for the coating method, any known method can be used, such as roll coating methods such as gravure coating and reverse coating, bar coating methods such as a Mayer bar, spray coating, and air knife coating.

[0035] (Release layer thickness) In the present invention, the thickness of the release layer is an important requirement for achieving both the releasability of each layer sheet formed on the release film and the release film, as well as reducing the environmental impact. Specifically, the thickness must be 0.001 μm or more and 1.5 μm or less, preferably 0.002 μm or more and 1.0 μm or less, more preferably 0.003 μm or more and 0.60 μm or less, and even more preferably 0.004 μm or more and 0.50 μm or less. When the thickness of the release layer is 0.001 μm or more, the required release performance can be obtained, and when it is 1.5 μm or less, the use of unnecessary release layer components can be reduced, and processing can be performed with appropriate drying and curing times, improving productivity and further suppressing an increase in the environmental impact.

[0036] (Prevents silicone migration from the release layer) All-solid-state battery manufacturing methods include peeling off each layer formed on a release film, thermocompression bonding, and then laminating the layers. Alternatively, the binder is removed (degreasing) by heating, and the laminate is then sintered before use. In this case, if a silicone compound is used as an additive in the release agent itself, release layer, antistatic layer, etc., the silicone compound may migrate to each layer. This migration is not a problem if it does not impair the effects of the present invention, or if the silicone is oxidized or thermally decomposed during degreasing and sintering, so that it no longer impairs the effects of the present invention. However, especially when the layers are laminated and used as is without degreasing or sintering, the silicone compound transferred from the release film to each layer may adversely affect the bonding of the layers and the migration of lithium ions. To prevent this, methods include reducing the amount of silicone compound used as a release agent or additive, or reacting and immobilizing the silicone compound by crosslinking or other methods to suppress migration. If silicone migration is a problem, the release film should be used with a silicone extractable by hexane of 3 mg / m or less. 2 It is desirable that the concentration is less than 2 mg / m 2 It is more preferable that it is 1 mg / m or less. 2 It is even more desirable that:

[0037] In order to improve the adhesion of the release layer to the base film in the present invention, it is also preferable to form an antistatic layer on the polyester film surface before providing the release layer, or to form an antistatic layer on the polyester film surface in advance, and then form the release layer thereon, to subject the formed antistatic layer to pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment.

[0038] (antistatic layer) The release film of the present invention has a feature that prevents re-adhesion of a molded product that has been peeled off due to peeling electrification and heavy peeling due to static electricity, which are problems that arise when using a release film made of polyester. In addition to the method of adding an antistatic agent to the release agent, a separate antistatic layer can be provided. In particular, when an organic solvent is used during the molding of each layer sheet formed on a release film, it is desirable that peeling electrification be low.

[0039] Methods for preventing peeling static electricity from occurring on a release film include providing an antistatic layer on the surface opposite to the surface on which the release layer is formed, and laminating an antistatic layer and a release layer in that order on at least one surface of the polyester film substrate. Either method can be selected.

[0040] (Antistatic layer components) The antistatic agent used in the antistatic layer of the present invention is not particularly limited, and surfactants and the like can be used. Examples of surfactants include anionic antistatic agents whose functional groups are alkyl sulfate or alkyl phosphate; cationic antistatic agents whose functional groups are quaternary ammonium salt, quaternary ammonium resin, or imidazoline; nonionic antistatic agents whose functional groups are sorbitan or ether; and amphoteric antistatic agents whose functional groups are betaine. Conductive polymer antistatic agents such as polyaniline and thiophene polymers can also be used. The antistatic layer of the present invention may contain a binder component. The inclusion of a binder component can improve the adhesion of the antistatic layer to the polyester film. The binder resin is not particularly limited, but known resins can be used, such as polyester resins, polyurethane resins, polyacrylate resins, polyvinyl formal resins, polyvinyl alcohol resins, polyvinyl butyral resins, epoxy resins, polyamide resins, melamine resins, polystyrene resins, styrene-acrylic copolymer resins, chlorinated polypropylene resins, polyether resins, and silicon oxide films, or other solvent- or water-soluble or dispersible resins.

[0041] In the present invention, the antistatic layer may contain other components in addition to the antistatic agent and binder resin, as long as the effects of the present invention are not impaired.

[0042] In the present invention, the means for forming the antistatic layer is not particularly limited, and any method can be selected, such as a method in which a coating liquid containing an antistatic agent, a binder resin, and a solvent is applied to the surface of a substrate film by coating, and the solvent is then dried and removed; a method in which, when a curable component is used, the solvent is dried and removed and then cured by applying heat; a method in which the solvent is dried and then cured by irradiation with ultraviolet light or an electron beam, etc. As for the coating method, any known method can be used, such as a roll coating method such as gravure coating or reverse coating, a bar coating method such as a Mayer bar coating, a spray coating method, or an air knife coating method.

[0043] In order to improve the adhesion of the antistatic layer to the substrate film in the present invention, it is also preferable to subject the polyester film surface to pretreatment such as anchor coating, corona treatment, plasma treatment, atmospheric pressure plasma treatment, etc. before providing each coating layer.

[0044] (Thickness of antistatic layer) In the present invention, the thickness of the antistatic layer is not particularly limited and can be set depending on the objectives of antistatic performance and reducing environmental impact, but specifically, it is preferably 0.001 μm to 1.0 μm, more preferably 0.002 μm to 0.50 μm. When the thickness of the antistatic layer is 0.001 μm or more, the required antistatic performance can be obtained, and when it is 1.0 μm or less, it is possible to prevent the use of unnecessary antistatic layer components and shorten the time required for drying and curing, thereby improving productivity and preventing an increase in environmental impact.

[0045] (Example of the structure of an all-solid-state battery) An example of a cross-sectional view of an all-solid-state battery made of a material produced using the release film of the present invention is shown in Figure 1. In Figure 1, an all-solid-state battery 9 has a structure in which a solid electrolyte layer 3 is sandwiched between a positive electrode 1 and a negative electrode 2, and this structure is further sandwiched between an insulating layer 8. Here, the positive electrode 1 is composed of a positive electrode active material layer 4 and a positive electrode current collector layer 6 that collects current from the positive electrode active material layer 4. The negative electrode 2 is composed of a negative electrode active material layer 5 and a negative electrode current collector layer 7 that collects current from the negative electrode active material layer 5. The structure of the all-solid-state battery is not limited to that shown in Figure 1, and any structure that can be used as an all-solid-state battery can be selected, such as a structure without an insulating layer, or a structure without an insulating layer in which a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collecting layer are repeatedly stacked next to a positive electrode current collecting layer.

[0046] As a manufacturing method for each layer, there are various methods, such as a method in which a slurry in which at least particles for expressing the function and a binder are dispersed in a solvent is prepared for each layer, and then coated on the release film of the present invention, dried to form a sheet, peeled off, and thermocompressed to form a laminate, which is then used as is, or a so-called green sheet method in which the sheet is cut after thermocompression, the individual laminate is heated to thermally remove the binder (degreasing), and then further heated at a high temperature to sinter and densify, thereby forming each layer, and any method can be used, and the method is not limited to the exemplified methods.

[0047] (Solid electrolyte sheet manufacturing process, electrode active material sheet manufacturing process) The solid electrolyte sheet and electrode active material sheet are components that become the above-mentioned solid electrolyte layer, positive electrode active material layer, and negative electrode active material layer, and as described above, can be prepared by applying an active material slurry, in which at least particles of the solid electrolyte and electrode active material and a binder are dispersed in a solvent, onto the release film of the present invention and drying it.

[0048] (Current collector sheet manufacturing process) The current collector sheet is a component that becomes the above-mentioned positive electrode current collector layer and negative electrode current collector layer. This material may be a metal such as aluminum foil or copper foil, but it may also be prepared using a slurry in the same process as the solid electrolyte sheet and electrode active material sheet. When prepared using a slurry, at least conductive particles, and optionally solid electrolyte particles, are used, and the current collector can be prepared by dispersing these in a binder and a solvent to form a current collector slurry, which is then applied to the release film of the present invention and dried.

[0049] (Insulation sheet manufacturing process) The insulating sheet is a member that becomes the insulating layer. This material may be, for example, a polypropylene film, or may be prepared using a slurry in the same process as the solid electrolyte sheet and electrode active material sheet. When prepared using a slurry, the current collector may be prepared by applying a current collector slurry containing at least insulating particles dispersed in a binder and a solvent onto the release film of the present invention and drying the resulting current collector.

[0050] (Solid electrolyte particle component) There are various combinations of solid electrolytes, such as oxide-based solid electrolytes and sulfide-based solid electrolytes as materials, amorphous bodies, crystalline bodies, and glass ceramics as forms, and conductive ions such as lithium ions and sodium ions, and any combination can be used with the release film of the present invention.

[0051] For example, oxide-based solid electrolytes include perovskite-type, NASICON-type, LISICON-type, and garnet-type materials. One example is Lithium-ion battery, which has excellent chemical stability for the positive and negative electrodes, low water absorption, and is easy to handle. 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP) and Li7La3Zr2O 12 (LLZ) is well known, but the present invention is not limited to this, and any material that can be used as a solid electrolyte for an all-solid-state battery can be used.

[0052] In addition, sulfide-based solid electrolytes include crystalline thiosilicon type, LGPS type, argyrodite type, and Li2S-P2S 12 There are materials such as glass, which has high ionic conductivity (12 mScm -1 ) with Li 10 GeP2S 12 (LGPS) and the recently discovered Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (25mScm -1 ) are well known, but the present invention is not limited to these, and any material that can be used as a solid electrolyte for an all-solid-state battery can be used.

[0053] (Positive electrode active material particle component) Examples of the positive electrode active material component include layered compounds such as LiCoO2 and LiNiO2, spinel compounds such as LiMn2O4, olivine compounds such as LiFePO4, LiCoPO4, and LiNiPO4, as well as Li3V2(PO4)3 and Li4Ti5O. 12 However, the present invention is not limited to these, and any material that can be used as a positive electrode active material for an all-solid-state battery can be used.

[0054] (Negative electrode active material particle component) Examples of the negative electrode active material include carbon materials such as graphite, hard carbon, and soft carbon, metals such as Si and Sn, TiO2, Li3V2(PO4)3, and Li4Ti5O. 12 However, the present invention is not limited to these, and any material that can be used as a negative electrode active material for an all-solid-state battery can be used. In addition, the same active material can be used as both the positive electrode active material and the negative electrode active material without any problems.

[0055] (current collector layer particle components) When a current collector layer is formed using a slurry, the material must be made of conductive particles, and thus, the current collector layer components include, but are not limited to, carbon powder and metal powder, and any material that can be used as a current collector layer for an all-solid-state battery can be used.

[0056] (insulating layer particle component) When creating an insulating layer using a slurry, the material must be particles with electrical insulation properties. Therefore, the insulating layer components include, but are not limited to, LiGe2(PO4)3 and ZnO-B2O3, and any material that can be used as an insulating layer in an all-solid-state battery can be used.

[0057] (Particle size of each particle in the slurry) There are no particular restrictions on the particle size of each particle contained in the slurry for forming each of the above layers, as long as it can exhibit the required function of each layer. However, it is preferable that the particle size be 5 μm or less in order to prevent streak defects during slurry coating and uneven distribution due to particle scraping.

[0058] (binder component) Binders used in the slurries for forming the above-mentioned layers include ethyl cellulose, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, styrene butadiene rubber, polyvinylidene fluoride, etc., but any material can be used as a binder for each sheet, and if a green sheet method is used, any material can be used as long as it can also be degreased.

[0059] (solvent) The solvent is not particularly limited and can be selected appropriately as long as it does not cause problems in dispersibility of each component in the slurry, coating properties of the slurry, drying properties, etc.

[0060] The boiling point of the solvent is not particularly limited as long as the coating properties of the slurry are ensured, but it is usually preferably 70°C or higher under atmospheric pressure. On the other hand, from the viewpoint of the formability of the sheet by drying the slurry, it is preferably 130°C or lower, and more preferably 100°C or lower.

[0061] Specific examples of solvents include ethanol, methanol, N,N-dimethylformamide (DMF), methanol, and water. Each slurry may contain a solvent other than the above, such as 1-butanol, isopropyl acetate, or butyl acetate, which have a higher boiling point, or a mixture of three or more solvents. Furthermore, when a mixture of solvents is used, some of the solvents may not dissolve the binder component on their own, and there is no problem as long as the binder is dissolved in the mixed solvent.

[0062] (Mixing ratio of each component in the slurry) The mixing ratio of particles, binder, and solvent in the slurry can be set appropriately based on the performance required for each layer. In addition to these components, the slurry may also contain other components such as a dispersant for uniformly dispersing particles and a plasticizer for imparting flexibility to the dried sheet. The mixing ratio of other components can also be set appropriately, just like the particles, binder, and solvent.

[0063] (Slurry coating and drying conditions) The prepared slurry is coated on the release film of the present invention by various methods and dried. For example, the coating method may be a doctor blade method, a roll coating method, a dip coating method, a die coating method, a spray coating method, a screen printing method, an ink jet method, etc., but is not particularly limited thereto. The drying method and conditions can be appropriately selected. Regarding drying, there is no problem as long as the solvent can be removed from the coated slurry to obtain a sheet for each layer. Furthermore, the solvent remaining in the sheet after drying does not necessarily need to be completely removed. It is acceptable for the solvent to remain in the sheet as long as the sheet can be easily peeled from the release film of the present invention and the peeled sheet can be used without problems in subsequent processes such as thermocompression bonding, degreasing, and baking. Furthermore, the thickness of the sheet after drying can be individually set based on the desired performance, and the thicknesses of the solid electrolyte layer, positive electrode, negative electrode active material layer, current collector layer, and insulating layer in the all-solid-state battery prepared from each sheet may be different from each other.

[0064] (Laminate formation process) The process of laminating the sheets of each layer coated and dried on the release film can be carried out by peeling the sheets from the release film, stacking them together, and thermocompression bonding them together, or by laminating the sheets There is a process of thermocompression bonding each layer together with the release film, and then peeling off the release film, but any of these processes can be used, and these processes can also be combined without any problems. As for the conditions for thermocompression bonding, any conditions can be used as long as the sheet can be heated to a temperature above the softening point of the binder and compressed. As for the compression bonding method, for example, continuous pressing using a roll, flat pressing after cutting the sheet into sheets, isostatic pressing using water pressure, etc. can be used without being limited to these, and any method can be used.

[0065] (Green sheet method) Next, we will explain the case where a green sheet method is used to obtain an all-solid-state battery by degreasing and firing the laminate obtained in the laminate formation process. Note that it is not necessary to perform both the degreasing process and the firing process, and it is also possible to use a laminate that has only been subjected to the degreasing process, or to perform the process in one step where the firing process also serves as the degreasing process.

[0066] (Degreasing process) When sheets of each layer coated and dried on a release film are used as an all-solid-state battery, they may be able to be used as is. However, because the binder resin typically lacks ionic conductivity and electrical conductivity, the battery's performance may not be fully realized. In this case, a degreasing process is required to decompose and remove the binder contained in each layer by heating the laminate. The temperature, atmosphere, and time of the degreasing process can be selected under any conditions as long as the performance of the resulting all-solid-state battery is achieved. One example is to thermally decompose and remove the binder resin at 410°C in a nitrogen atmosphere, followed by carbonization of the resin at 540°C in an air atmosphere.

[0067] (Firing process) After degreasing the sheets of each layer coated and dried on a release film, they are heated (sintered) at high temperatures, which also serves as a degreasing process, to bond adjacent particles and densify each layer. In particular, when oxide-based compounds are used as solid electrolyte particles, these particles are generally very hard, so simply creating a laminate does not bond the particles together. Therefore, this process may be necessary to reduce interparticle resistance by sintering the particles. The temperature and time of the sintering process can be selected as long as the performance of the resulting all-solid-state battery is achieved. However, an inert atmosphere is typically used to suppress oxidation of each component. Gases used to form the inert atmosphere include nitrogen and argon, and these gases can be selected as appropriate. An example of sintering conditions is 750°C in nitrogen.

[0068] In one aspect, the present invention can provide a release film for producing an all-solid-state battery material, for producing at least one all-solid-state battery member selected from the group consisting of a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer for an all-solid-state battery.

[0069] In another aspect, the present invention can provide at least one all-solid-state battery member selected from the group consisting of a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer for an all-solid-state battery, which is produced using the release film for producing an all-solid-state battery material according to the present invention.

[0070] In another aspect, the present invention provides a method for producing a solid electrolyte layer for an all-solid-state battery, a method for producing a positive electrode active material layer for an all-solid-state battery, and a method for producing a solid electrolyte layer for an all-solid-state battery, each of which comprises using the release film for producing an all-solid-state battery material according to the present invention. The present invention provides a method for manufacturing a member for an all-solid-state battery, selected from the group consisting of a method for manufacturing a negative electrode active material layer for an all-solid-state battery, a method for manufacturing a current collector layer for an all-solid-state battery, and a method for manufacturing an insulating layer for an all-solid-state battery. In another aspect, the present invention provides a laminate comprising the release film of the present invention and at least one all-solid-state battery component selected from the group consisting of a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer for an all-solid-state battery. Because such a laminate contains the release film of the present invention, the at least one all-solid-state battery component selected from the group consisting of a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer for an all-solid-state battery can be peeled off without damaging it. Furthermore, the present invention can achieve both a reduction in environmental impact by reducing the thickness of both the polyester film substrate and the release layer, and good releasability of each layer sheet formed on the release film. In another aspect, the present invention provides a method for producing an all-solid-state battery using the release film for producing an all-solid-state battery material according to the present invention. [Example]

[0071] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The property values ​​used in the present invention were evaluated using the following methods.

[0072] (intrinsic viscosity of polyester) The sample was crushed and dried, then dissolved in a 6 / 4 (weight ratio) mixed solvent of phenol and 1,1,2,2-tetrachloroethane. This solution was centrifuged to remove inorganic particles and other impurities, and then measured at 30°C using an Ubbelohde viscometer. The weight used in the calculation was the weight of the sample minus the weight of components other than polyester.

[0073] (Thickness of release layer and antistatic layer) The cut-out release film was embedded in resin and cut into ultrathin sections using an ultramicrotome, and then directly observed at a magnification of 20,000 times using a JEOL JEM2100 transmission electron microscope to measure the thickness of the release layer and antistatic layer. Note that for release layers and antistatic layers that were very thin, the images obtained by observation were enlarged and used for calculation.

[0074] (Amount of silicone extracted from release film by hexane) Release film is placed on a 300mm x 300mm (area: 0.09m 2 The extract was then concentrated by blowing nitrogen at 40°C, and the extracted components were quantified using the difference spectrum from the solvent. Measurement machine: FT-IR device BioRad FTS-60A / 896 (manufactured by Bio-Rad) Measurement cell: Window material: KCl, cell thickness: 0.203 mm Resolution: 4cm -1 , Number of times accumulated: 128 times

[0075] (Removability of each layer sheet) The release film with each layer sheet was cut to a width of 30 mm, and after static elimination using a static eliminator (Keyence Corporation, SJ-F020), a T-peel test was carried out at a peel speed of 600 mm / min. The obtained sheets of each layer and the release film were visually inspected and evaluated according to the following criteria. ◎: There are no tears, cracks, or cracks in the sheets of each layer, and no peeled residue of any layer components remains on the release film. The release is particularly good. ◯: There are no tears, cracks, or cracks in the layer sheets, and no peeled residue of any layer components remains on the release film. There is no particular problem with peeling. △: Slight breakage, splitting, or cracking of each layer sheet, or slight peeling of each layer component remaining on the release film. ×: One or more of the following clearly occurred: breakage, cracking, or fissure in each layer sheet, or peeling residue of each layer component on the release film.

[0076] (Silicone migration from release film to each layer) After evaluating the peelability of each layer sheet, for a level where no peeled residue of each layer component remained on the release film, a 50 mm long line was drawn with extra-thick (red) magic marker (manufactured by Teranishi Chemical Industry Co., Ltd.) on the surface of each layer sheet that had been in contact with the release film, and the degree of ink repellency was evaluated according to the following criteria. Good: No repellency was observed in the red ink on the sheet. △: Slight repellency was observed in the red ink on the sheet. ×: Clear cissing is observed in the red ink on the sheet.

[0077] (frictional charging) After unwinding the rolled film at a speed of 2 m / min in an atmosphere of 20°C and 40% RH, electrostatic copier toner (Ricoh PPC toner: Type 3300) was evenly sprinkled onto the release layer of the film, and the toner dispersibility was visually observed. Areas that were triboelectrically charged had a lot of toner adhering to them, so they could be judged by their dispersibility. A state in which the toner was evenly adhered was judged to be free of triboelectric charging and was rated as good (○), while areas where a lot of toner had adhered were rated as poor (×).

[0078] (Preparation of polyethylene terephthalate pellets (PET(I))) The esterification reaction apparatus is a 3-stage reactor having a stirrer, a partial condenser, a raw material inlet, and a product outlet. A continuous esterification reactor consisting of a two-stage complete mixing vessel was used. ton / hour, EG (ethylene glycol) is 2 moles per mole of TPA, and trioxide Antimony was added in an amount that would result in 160 ppm of Sb atoms in the produced PET. The mixture was continuously fed to the first esterification reactor of the esterification reactor at atmospheric pressure for an average residence time of 4 The reaction was continued at 255°C for 1 hour. Then, the reaction product in the first esterification reactor was continuously The reaction mixture is taken out of the system and fed to a second esterification reactor, and the first ester is added to the second esterification reactor. EG distilled from the polymerization reactor was fed in an amount of 8 mass % based on the produced PET, and the produced PET was further an EG solution containing magnesium acetate tetrahydrate in an amount such that the Mg atom is 65 ppm relative to T; Contains TMPA (trimethyl phosphate) in an amount that results in 40 ppm of P atoms in the produced PET. The EG solution containing the EG component was added, and the reaction was carried out at atmospheric pressure for an average residence time of 1 hour at 260°C. The reaction product from the second esterification reactor is continuously removed from the system and fed to the third esterification reactor. The mixture was then dispersed at a pressure of 39 MPa (400 kg / cm2) using a high-pressure disperser (manufactured by Nippon Seiki Co., Ltd.). Porous colloidal silica with an average particle size of 0.9 μm, which has been subjected to dispersion treatment with an average number of treatments of 5 passes. 0.2% by mass and ammonium salt of polyacrylic acid attached at 1% by mass per calcium carbonate 0.4 mass% of synthetic calcium carbonate with an average particle size of 0.6 μm was added to the mixture. The reaction was carried out at 260°C for an average residence time of 0.5 hours under normal pressure while adding EG as a slurry. The esterification reaction product produced in the third esterification reactor was subjected to three consecutive polycondensation reactions. The polycondensation is carried out by continuously feeding the material into the device. The fibers are filtered through a sintered filter, then extruded into water, cooled, and cut into chips. As a result, PET chips with an intrinsic viscosity of 0.60 dl / g were obtained (hereinafter abbreviated as PET(I)). The lubricant content in ET(I) was 0.6% by mass.

[0079] (Preparation of polyethylene terephthalate pellets (PET(II))) In the production of the PET chips, the reaction time in the continuous polycondensation reactor is adjusted to be short. The polymerization was carried out under the same conditions as above, and PET chips with an intrinsic viscosity of 0.41 dl / g were obtained (hereinafter, abbreviated as PET(II).

[0080] (Preparation of polyethylene terephthalate pellets (PET(III))) PET(I) was polymerized in a rotary vacuum polymerization apparatus at a reduced pressure of 0.5 Torr at 220°C to form a solid phase. Polymerization was carried out to obtain PET chips with an intrinsic viscosity of 0.88 dl / g (hereinafter referred to as PET(III)). vinegar).

[0081] (Preparation of polyethylene terephthalate pellets (PET(IV))) PET(I) was polymerized in a rotary vacuum polymerization apparatus at a reduced pressure of 0.3 Torr at 220°C. Further prolonged solid-state polymerization of T(III) resulted in PET with an intrinsic viscosity of 1.12 dl / g. A chip was obtained (hereinafter abbreviated as PET(IV)).

[0082] (Preparation of solid electrolyte slurry) LAGP powder as a solid electrolyte, vinyl butyral resin as a binder resin, dispersion Anhydrous ethanol as a solvent was weighed in a weight ratio of 60:12:28, and the binder resin was After dissolving in the solvent, the solution and LAGP powder were placed in a container containing a dispersion medium. The powder was sealed in a rotating pot. The pot was rotated for 48 hours to separate the LAGP powder. After the dispersion, a degassing treatment was carried out to obtain a solid electrolyte slurry.

[0083] (Preparation of Positive Electrode Active Material Slurry) The positive electrode active material is LiNiPO4 powder, the solid electrolyte is LAGP powder, and the conductive additive is All the carbon powders were mixed in a ratio of 45:45:10 to obtain a positive electrode active material mixed powder. Active material mixed powder, vinyl butyral resin, and absolute ethanol in a weight ratio of 60:11:29 After weighing, a positive electrode active material slurry was obtained in the same manner as in the solid electrolyte slurry.

[0084] (Preparation of negative electrode active material slurry) Graphite powder as the negative electrode active material and LAGP powder as the solid electrolyte were weighed in a weight ratio of 30:70 to prepare a negative electrode active material mixed powder. Next, the negative electrode active material mixed powder, vinyl butyral resin, and anhydrous ethanol were weighed in a weight ratio of 60:11:29, and then a negative electrode active material slurry was prepared in the same manner as the solid electrolyte slurry described above.

[0085] (Preparation of current collector slurry) In this example and the comparative example, the positive electrode and negative electrode current collector layers had the same composition. Carbon powder as a conductive additive and LAGP powder as a solid electrolyte are mixed in a ratio of 12:88. Next, the current collector mixed powder, vinyl butyral resin, and absolute ethanol were weighed in a weight ratio of 60:10:30, and then a current collector slurry was obtained in the same manner as the solid electrolyte slurry.

[0086] (Preparation of insulating slurry) ZnO-B2O3 powder as an insulator, vinyl butyral resin, and absolute ethanol were weighed out in a weight ratio of 60:11:29, and then an insulating slurry was obtained in the same manner as the solid electrolyte slurry described above.

[0087] (Creating solid electrolyte sheets) The solid electrolyte slurry was applied to a release film using a doctor blade and dried at 40°C. After drying, secondary drying was carried out at 80°C to prepare a solid electrolyte sheet with a thickness of 10 µm.

[0088] (Creating a positive electrode active material sheet) The same procedure as for the preparation of the solid electrolyte sheet was carried out except that the positive electrode active material slurry was used as the slurry. A positive electrode active material sheet having a thickness of 40 μm was formed on a release film.

[0089] (Creating a negative electrode active material sheet) The procedure for preparing the solid electrolyte sheet was the same as that for preparing the solid electrolyte sheet, except that the negative electrode active material slurry was used as the slurry. A negative electrode active material sheet having a thickness of 30 μm was formed on a release film.

[0090] (Creating a current collector sheet) A current collector sheet having a thickness of 20 μm was prepared on a release film in the same manner as in the preparation of the solid electrolyte sheet, except that the current collector slurry was used as the slurry.

[0091] (Creating an insulating sheet) An insulating sheet having a thickness of 100 μm was prepared on a release film in the same manner as in the preparation of the solid electrolyte sheet, except that an insulating slurry was used as the slurry.

[0092] Example 1 (Production of base film (A)) PET(I) was dried under reduced pressure at 135°C and 1 Torr for 6 hours, then fed to an extruder and heated to 285°C. This polymer was melted at 100°C. The polymer was then filtered through a stainless steel sintered filter medium (nominal filtration accuracy: 10 μm particles, 95% After filtering the mixture through a filter (cutting), extruding it into a sheet from a nozzle, it is cast using an electrostatic casting method. The mixture was brought into contact with a casting drum with a surface temperature of 30°C to cool and solidify, producing an unstretched film. This unstretched film was stretched 3.4 times in the longitudinal direction at 85°C. The film was stretched 4.4 times in the width direction at 95°C using a tenter and then heat-treated at 220°C for 5 seconds. As a result, a substrate film (A) having a thickness of 38 μm and an intrinsic viscosity of 0.58 dl / g was obtained. This film was produced continuously for 72 hours, but no breakage occurred during the stretching process, and productivity was The film had good visual quality. Other details are shown in Tables 1 and 2.

[0093] (Formation of release layer (a)) 100 parts by mass of UV-curable silicone resin (manufactured by Momentive Performance Materials, Inc., trade name UV9300, solids concentration 100% by mass) and 1.1 parts by mass of the curing catalyst bis(alkylphenyl)iodonium hexafluoroantimonate were diluted with a toluene / methyl ethyl ketone / heptane (=3:5:2) solution to prepare a silicone resin coating solution with a solids content of 2% by mass. This silicone resin coating solution was applied to a substrate film (A) using a Mayer bar, dried at 112°C for 30 seconds, and then irradiated with a UV irradiator at 350 mJ / cm. 2 The thickness of the release layer was adjusted to 0.005 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar.

[0094] (Release film evaluation) This film was subjected to various evaluation tests, and the results were as shown in Tables 1 and 2. The productivity of the base film is good, and the thin release layer reduces the environmental impact. The peelability of the layered sheets is good, and the amount of silicone extracted is small. The transfer of silicone to the resin was small.

[0095] (Comparative Example 1) (Production of base film (B)) A substrate film (B) was produced in the same manner as in Example 1, except that PET (II) was used for the polyethylene terephthalate pellets, and a film with a thickness of 38 μm and an intrinsic viscosity of 0.40 dl / g was obtained. Although the visual quality of the film was good, many film breaks occurred during the 72-hour production, and productivity was significantly reduced compared to Example 1. Therefore, it was determined that the environmental load was too great and the study was discontinued.

[0096] Example 2 (Production of base film (C)) The same procedure as in Example 1 was carried out except that PET(III) was used for the polyethylene terephthalate pellets. The base film (C) was manufactured, and the film had a thickness of 38 μm and an intrinsic viscosity of 0.83 dl / g. During the 72-hour production, no film breakage occurred, and the productivity was as good as in Example 1. The film was good in appearance and the visual quality was good.

[0097] (Formation of release layer) A release layer was formed on the base film (C) in the same manner as in Example 1. At this time, the thickness of the release layer of the obtained release film was 0.005 μm.

[0098] (Film evaluation) This film was subjected to various evaluation tests, and the results were as shown in Tables 1 and 2. As with Example 1, this film had a small environmental impact, the releasability of each layer sheet was good, and the amount of silicone extracted and the silicone transferred to each layer sheet were small.

[0099] (Comparative Example 2) (Production of base film (D)) An attempt was made to produce a base film (D) in the same manner as in Example 1, except that PET (IV) was used for the polyethylene terephthalate pellets. However, during melting in the extruder and extrusion into a sheet, the back pressure of the machine increased, making it impossible to extrude under the same conditions. In order to improve this, the conditions were examined, When the temperature of the machine was raised to 310°C, a film with a thickness of 38 µm and an intrinsic viscosity of 0.92 dL / g was obtained. The obtained film yellowed due to thermal degradation and contained foreign matter. Furthermore, when production was attempted, film breakage occurred frequently and productivity was significantly reduced compared to Example 1. Therefore, it was determined that the environmental impact was too great and the study was discontinued.

[0100] (Comparative Example 3) (Production of base film (E)) Using PET(IV) in polyethylene terephthalate pellets, the extrusion volume per hour was reduced by half. The same procedure as in Example 1 was repeated except that the film speed in the longitudinal and transverse stretching steps was halved. Similarly, when an attempt was made to produce a substrate film (D), the thickness was 38 μm and the intrinsic viscosity was 0.95d However, the obtained film was inferior to that in Example 1. However, yellowing and contamination of foreign matter were observed, which were thought to be due to long periods of residence in the extruder. Regarding the setting, the amount of film obtained is first halved by setting the extrusion amount. During two hours of production, film breakage occurred nine times, and productivity was significantly lower than in Example 1. Therefore, it was determined that the environmental impact would be too great and the study was discontinued.

[0101] Example 3 A release film was prepared in the same manner as in Example 1, except that the thickness of the substrate film was adjusted to 50 μm, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. As with Example 1, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0102] Example 4 A release film was prepared in the same manner as in Example 1, except that the thickness of the substrate film was adjusted to 188 μm, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. As with Example 1, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0103] Comparative Example 4 A release film was prepared in the same manner as in Example 1, except that the thickness of the base film was adjusted to 8 μm. This film wrinkled during the base film production and release layer processing, making it impossible to use as a release film, so the study was discontinued.

[0104] (Comparative Example 5) A release film was prepared in the same manner as in Example 1, except that the thickness of the substrate film was adjusted to 250 μm, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. The amount of silicone extracted from this film and the migration of silicone to each layer sheet were small, but Although the film was very thick and had a large environmental impact, when evaluating the peelability of the film from each layer sheet, the release film was too hard to deform, and deformation was concentrated on the side of each layer sheet, resulting in cracks and splits in the sheet, resulting in poor performance.

[0105] (Examples 5 and 6) A release film was prepared in the same manner as in Example 1, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 1, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0106] (Comparative Example 6) The base film (A) was used as a release film and each evaluation test was carried out without forming a release layer. Because no release layer was formed, the environmental impact was small and there was no silicone extraction, but the peelability of each layer sheet was poor, and in the peel test of each sheet, The sheets of each layer were torn and the components of each layer remained peeled off on the release film.

[0107] (Comparative Example 7) A release film was produced in the same manner as in Example 1, except that the thickness of the release layer was adjusted to 1.8 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar. However, drying at 112°C for 30 seconds left a large amount of solvent remaining, and a release film that could be evaluated could not be obtained.

[0108] (Comparative Example 8) A release film was prepared in the same manner as in Comparative Example 7, except that the drying time was set to 120 seconds. No residual solvent was observed in the film after drying, but the longer drying time resulted in a significantly larger environmental impact. The evaluation results of the film are shown in Tables 1 and 2. Although the thicker release layer required more materials to be used, significantly increasing the environmental impact, an increase in the amount of silicone extracted occurred, which is thought to be due to insufficient curing of the silicone resin when exposed to ultraviolet light, and the quality of the resulting layer sheets for all-solid-state batteries was also inferior to the sheet obtained in Example 1.

[0109] Example 7 (Formation of release layer (b)) UV-curable silicone resin (manufactured by Arakawa Chemical Industries, Ltd., product name: SILICOLEASE UVPOLY21 5, 100 parts by mass of a curing catalyst (manufactured by Arakawa Chemical Industries, Ltd., product name: SilicoLease) 5 parts by mass of UV CATA211, solid content: 18.5% by mass, was dissolved in toluene / MEK=1 The resulting solution was diluted with a mixed solvent at a ratio of 1 / 1 to prepare a release layer coating solution with a solid content of 1.0% by mass. This silicone resin coating solution was applied onto the substrate film (A) using a Mayer bar, dried at 93°C for 30 seconds, and then exposed to an ultraviolet ray irradiation device at 110 mJ / cm 2 The thickness of the release layer was adjusted to 0.005 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar.

[0110] (Release film evaluation) This film was subjected to various evaluation tests, and the results were as shown in Tables 1 and 2. This film had a low environmental impact, the individual layer sheets were easily releasable, and the amount of silicone extracted and the silicone transferred to the individual layer sheets were low.

[0111] (Examples 8 and 9) A release film was prepared in the same manner as in Example 7, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 7, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0112] Example 10 (Formation of release layer (c)) A silicone resin coating solution with a solids content of 2% by weight was prepared by diluting 100 parts by weight of a thermosetting silicone resin (manufactured by Dow Corning Toray Co., Ltd., product name LTC310) and 2.2 parts by weight of a curing catalyst (manufactured by Dow Corning Toray Co., Ltd., SRX212) with a 5:5 toluene / methyl ethyl ketone solution. This silicone resin coating solution was applied to a substrate film (A) using a Mayer bar and then dried at 122°C for 30 seconds to obtain a release film. The thickness of the release layer was adjusted to 0.005 μm after drying by selecting the diameter of the wire wound around the bar.

[0113] (Release film evaluation) This film was subjected to various evaluation tests, and the results were as shown in Tables 1 and 2. This film had a low environmental impact, the individual layer sheets were easily releasable, and the amount of silicone extracted and the silicone transferred to the individual layer sheets were low.

[0114] (Examples 11 and 12) A release film was prepared in the same manner as in Example 10, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 10, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0115] Comparative Example 9 A release film was prepared in the same manner as in Example 7, except that the thickness of the release layer was adjusted to 1.7 μm after drying and UV irradiation by selecting the diameter of the wire wound around the bar. However, drying at 93°C for 30 seconds left a large amount of solvent remaining, and a release film that could be evaluated could not be obtained.

[0116] (Comparative Example 10) A release film was prepared in the same manner as in Comparative Example 9, except that the drying time was set to 120 seconds. No residual solvent was observed in the film after drying, but the longer drying time resulted in a significantly larger environmental impact. The evaluation results of the film are shown in Tables 1 and 2. Although the thicker release layer required more material to be used, significantly increasing the environmental impact, the applied heat was almost entirely used to dry the solvent, and the film temperature did not rise, preventing the thermal addition reaction from proceeding. This resulted in an increase in the amount of silicone extraction, and the quality of the resulting layer sheets for all-solid-state batteries was also inferior to that of the sheet obtained in Example 7.

[0117] (Comparative Example 11) A release film was prepared in the same manner as in Example 10, except that the thickness of the release layer was adjusted to 1.9 μm after drying and UV irradiation by selecting the diameter of the wire wound around the bar. However, drying at 122°C for 30 seconds left a large amount of solvent remaining, and a release film that could be evaluated could not be obtained.

[0118] (Comparative Example 12) A release film was prepared in the same manner as in Comparative Example 11, except that the drying time was set to 120 seconds. No residual solvent was observed in the film after drying, but the longer drying time resulted in a significantly larger environmental impact. The evaluation results of the film are shown in Tables 1 and 2. Although the thicker release layer required more material to be used, significantly increasing the environmental impact, the applied heat was almost entirely used to dry the solvent, and the film temperature did not rise, resulting in an increase in the amount of silicone extraction, which is thought to be due to the thermal addition reaction not proceeding. The quality of the resulting sheet of each layer for an all-solid-state battery was also inferior to that of the sheet obtained in Example 10.

[0119] Example 13 (Formation of release layer (d)) 100 parts by mass of a thermal UV-curable silicone resin (manufactured by Toray Dow Corning Co., Ltd., product name LTC851) and 3.3 parts by mass of a curing catalyst (manufactured by Toray Dow Corning Co., Ltd., product name BY24-835) were diluted with a toluene / methyl ethyl ketone / heptane (=3:5:2) solution to prepare a silicone resin coating solution with a solids content of 2.2% by mass. This silicone resin coating solution was applied to a substrate film (A) using a Mayer bar, dried at 122°C for 30 seconds, and then irradiated with a UV irradiator at 120 mJ / cm. 2 The thickness of the release layer was adjusted to 0.005 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar.

[0120] (Release film evaluation) This film was subjected to various evaluation tests, and the results were as shown in Tables 1 and 2. This film had a low environmental impact, the individual layer sheets were easily releasable, and the amount of silicone extracted and the silicone transferred to the individual layer sheets were low.

[0121] (Examples 14 and 15) A release film was prepared in the same manner as in Example 13, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 13, this film had a small environmental impact, good releasability of each layer sheet, and small amounts of silicone extracted and silicone transferred to each layer sheet.

[0122] (Comparative Example 13) A release film was prepared in the same manner as in Example 13, except that the thickness of the release layer was adjusted to 2.0 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar. However, drying at 122°C for 30 seconds left a large amount of solvent remaining, and a release film that could be evaluated could not be obtained.

[0123] (Comparative Example 14) A release film was prepared in the same manner as in Comparative Example 13, except that the drying time was set to 120 seconds. No residual solvent was observed in the film after drying, but the longer drying time resulted in a significantly greater environmental impact. The evaluation results of the film are shown in Tables 1 and 2. Although the thicker release layer required more material to be used, significantly increasing the environmental impact, the applied heat was almost entirely used to dry the solvent, the film temperature did not rise, and the thermal addition reaction did not proceed. In addition, there was an increase in the amount of silicone extraction, which is thought to be due to insufficient curing of the silicone resin under ultraviolet irradiation. The quality of the resulting layer sheets for all-solid-state batteries was also inferior to that of the sheet obtained in Example 13.

[0124] Example 16 (Formation of release layer (e)) A coating solution was prepared by mixing 0.7 parts by weight of polypropylene wax (Hitec E433N, manufactured by Toho Chemical Industry Co., Ltd.), 0.3 parts by weight of an anionic polymer antistatic agent (number average molecular weight: 120,000, Gohsefimer, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 50 parts by weight of methanol, and 49 parts by weight of water. This coating solution was applied to the substrate film (A) using a Mayer bar and then dried at 140°C for 30 seconds to obtain a release film. The thickness of the release layer was adjusted to 0.005 μm after drying by selecting the diameter of the wire wound around the bar.

[0125] (Release film evaluation) This film was subjected to various evaluation tests, and the results are shown in Tables 1 and 2. This film has a low environmental impact, there are no problems with the peelability of each layer sheet, and because no silicone is used in the release layer, there is no silicone migration. Furthermore, because the release layer contains an antistatic agent, a frictional electrification test was conducted and the results were good.

[0126] (Examples 17 and 18) A release film was prepared in the same manner as in Example 16, except that the thickness of the release layer was adjusted to 0.020 or 0.030 μm after drying by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 16, this film had a small environmental impact, there were no problems with the releasability of each layer sheet, and because no silicone was used in the release layer, there was no silicone migration, and the results of the triboelectric charge test were good.

[0127] (Comparative Example 15) A release film was created by adjusting the thickness of the release layer to 1.6 μm after drying by selecting the diameter of the wire wound around the bar; however, drying at 140°C for 30 seconds left a large amount of solvent remaining, and a release film suitable for evaluation could not be obtained.

[0128] Example 19 (Formation of base film (F) with antistatic layer formed on the same surface as the release layer) An antistatic layer coating solution was prepared by mixing 0.6 parts by weight of a quaternary ammonium salt (Soken Chemical Industries, Ltd., PQ-10, solution concentration 50%) as a cationic antistatic agent, 0.3 parts by weight of polyvinyl butyral (Sekisui Chemical Co., Ltd., trade name S-LEC BL-1), and 99.1 parts by weight of ethanol. This antistatic layer coating solution was applied to the substrate film (A) using a Mayer bar and then dried at 92°C for 30 seconds to obtain a release layer-co-faced antistatic layer-formed substrate film (F). The thickness of the antistatic layer was adjusted to 0.030 μm after drying by selecting the diameter of the wire wound around the bar.

[0129] (Formation of release layer (f)) A silicone resin coating solution was prepared by mixing 2 parts by weight of a thermosetting silicone resin (product name KS772, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.055 parts by weight of a catalyst (product name CAT·PL-4, manufactured by Shin-Etsu Chemical Co., Ltd.), 70 parts by weight of toluene, and 30 parts by weight of methyl ethyl ketone. This silicone resin coating solution was applied to the antistatic layer-forming surface of the base film (F) using a Mayer bar and then dried at 162°C for 30 seconds to obtain a release film. The thickness of the release layer was adjusted by selecting the diameter of the wire wound around the bar so that it would be 0.005 μm after drying and UV irradiation.

[0130] (Release film evaluation) This film was subjected to various evaluation tests, and the results are shown in Tables 1 and 2. This film had a low environmental impact, the individual layer sheets were easily releasable, and the amount of silicone extracted and the silicone transferred to the individual layer sheets were small. Furthermore, a test of triboelectric charging showed good results.

[0131] (Examples 20 and 21) A release film was prepared in the same manner as in Example 19, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 19, this film had a small environmental impact, good releasability of each layer sheet, small amounts of silicone extracted and silicone migration to each layer sheet, and good results in the triboelectric charge test.

[0132] Example 22 (Formation of antistatic layer-forming substrate film (G) on the side opposite to the release layer) An antistatic layer coating solution was prepared by mixing 0.3 parts by weight of a cationic polymer antistatic agent (number average molecular weight: 5000, Chemistat 6300H, manufactured by Sanyo Chemical Industries, Ltd.), 0.13 parts by weight of polyethylene wax (Hitec E6000, manufactured by Toho Chemical Industry Co., Ltd.), 50 parts by weight of methanol, and 49.57 parts by weight of water. This antistatic layer coating solution was applied to the substrate film (A) using a Mayer bar and then dried at 142°C for 30 seconds to obtain a release layer-co-face antistatic layer-formed substrate film (G). The thickness of the antistatic layer was adjusted to 0.030 μm after drying by selecting the diameter of the wire wound around the bar.

[0133] (Formation of release layer) (G) is used as the base film, and a release layer is provided on the surface opposite to the antistatic layer. A release film was prepared in the same manner as in Example 19, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. As with Example 19, this film had a small environmental impact, good releasability of each layer sheet, small amounts of silicone extracted and silicone migration to each layer sheet, and good results in the triboelectric charge test.

[0134] (Examples 23 and 24) A release film was prepared in the same manner as in Example 22, except that the thickness of the release layer was adjusted to 0.050 or 0.10 μm after drying and ultraviolet irradiation by selecting the diameter of the wire wound around the bar, and the prepared release film was evaluated. The results are shown in Tables 1 and 2. Like Example 22, this film had a small environmental impact, good releasability of each layer sheet, small amounts of silicone extracted and silicone migration to each layer sheet, and good results in the triboelectric charge test.

[0135] [Table 1A]

[0136] [Table 1B]

[0137] [Table 2A]

[0138] [Table 2B] [Industrial Applicability]

[0139] The present invention provides a release film that has a small environmental impact and excellent releasability, and is used in producing a solid electrolyte layer, a positive electrode active material layer, a negative electrode active material layer, a current collector layer, and an insulating layer, which are materials for all-solid-state batteries. [Explanation of symbols]

[0140] 1...Positive electrode 2...Negative electrode 3...Solid electrolyte layer 4...Cathode active material layer 5...Negative electrode active material layer 6...Positive electrode current collector layer 7...Negative electrode current collector layer 8...Insulating layer 9…All-solid-state battery

Claims

1. A release film having, in this order, an antistatic layer, a polyester film as a base material, and a release layer, The release layer is a layer formed on the substrate, The aforementioned release layer is formed from a coating liquid that forms the release layer, and the coating liquid contains a UV-curable silicone resin. The intrinsic viscosity of the base film is 0.50 to 0.90 dl / g, the thickness is 10 μm or more and 188 μm or less, and the thickness of the release layer is 0.001 μm or more and 1.5 μm or less. The antistatic layer is formed from an antistatic coating liquid, and the antistatic coating liquid contains a polymer antistatic agent. The thickness of the antistatic layer is 0.001 μm or more and 1.0 μm or less. , release film.

2. The release film according to claim 1, wherein the polyester film has a surface layer B that forms a surface opposite to the surface having the release layer, and the surface layer B contains particles with an average particle size of 0.01 to 10 μm in a proportion of 0.005 to 5% by weight.

3. The release film according to claim 1, wherein the polyester film has a surface layer A which is the layer on the side having the release layer, and a surface layer B which is the layer on the opposite side, and the surface layer B contains 50 to 90% by mass of film waste and / or recycled PET bottle material.

4. The polyester film has a surface layer A which is the layer on the side with the release layer, a surface layer B which is the layer on the opposite side, and a core layer C which is the other layers. The release film according to claim 1, wherein the layers other than the surface layer A in the polyester film contain 50 to 90% by mass of film waste and / or recycled PET bottle material.

5. From a solid electrolyte layer, positive electrode active material layer, negative electrode active material layer, current collector layer, and insulating layer for all-solid-state batteries. A release film according to claim 1 for manufacturing at least one all-solid-state battery component selected from the group.

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