Packaging film for power storage devices, manufacturing method therefor, and power storage device

Abstract

A packaging film for power storage devices that is formed from a laminate comprising at least a base layer and a heat-fusible resin layer, wherein the laminate includes a polyester film, the polyester film includes a polyester containing a diol unit and a dicarboxylic acid unit, and the diol unit contains ethylene glycol using at least one gas selected from the group consisting of carbon monoxide and carbon dioxide as a starting material.

Description

Packaging film for energy storage devices, method for manufacturing the same, and energy storage device

[0001] This disclosure relates to a packaging film for energy storage devices, a method for manufacturing the same, and an energy storage device.

[0002] While various types of energy storage devices have been developed, packaging films are essential components for sealing energy storage device elements such as electrodes and electrolytes in all of them. For example, metal packaging materials have traditionally been widely used as outer coverings for energy storage devices.

[0003] On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, and mobile phones, energy storage devices are required to come in a variety of shapes, as well as be thinner and lighter. However, conventional metal casing materials for energy storage devices have the drawback of being unable to keep up with the diversification of shapes, and also having limitations in terms of weight reduction.

[0004] Therefore, in recent years, a film-like laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated has been proposed as an exterior material for energy storage devices that can be easily processed into various shapes and can achieve thinning and weight reduction (see, for example, Patent Document 1).

[0005] In such an exterior material for energy storage devices, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolytes are placed in the space formed by the recesses. By heat-sealing a heat-sealable resin layer, an energy storage device is obtained in which the energy storage device elements are housed inside the exterior material for the energy storage device.

[0006] Japanese Patent Publication No. 2008-287971, Japanese Patent Publication No. 2011-527348, Japanese Patent Publication No. 2012-519748, Japanese Patent Publication No. 2011-512869, Japanese Patent Publication No. 2018-123390

[0007] Polyester is widely used in various industrial applications because of its excellent mechanical properties, chemical stability, heat resistance, transparency, etc., and its low cost. Polyester may also be used for the substrate layer of packaging films for energy storage devices. Polyester is obtained by polycondensing diol units and dicarboxylic acid units. For example, polyethylene terephthalate is produced by subjecting ethylene glycol and terephthalic acid to an esterification reaction and then a polycondensation reaction using these as raw materials. These raw materials are produced from petroleum, which is a fossil fuel. For example, ethylene glycol is industrially produced from ethylene, and terephthalic acid is industrially produced from xylene.

[0008] In recent years, with the increasing demand for the construction of a recycling-oriented society, in the field of materials, like energy, a shift away from fossil fuels is desired, and the production of polyester from raw materials other than fossil fuels, such as biomass, is being considered. Biomass is an industrial resource originating from the components of living organisms that is not a depletable resource. The carbon contained in biomass is derived from carbon dioxide absorbed from the atmosphere through photosynthesis during the growth process of organisms. Therefore, even if carbon dioxide is emitted by burning biomass, overall, it is considered not to increase the amount of carbon dioxide in the atmosphere. For this reason, biomass is attracting attention as a carbon-neutral renewable energy.

[0009] Recently, the practical application of biomass plastics using these biomasses as raw materials has been rapidly progressing, and attempts have also been made to produce polyester, which is a general-purpose polymer material, from these biomass raw materials (for example, Patent Documents 2 and 3). By using polyester (biomass polyester) produced from biomass-derived raw materials in place of polyester produced using fossil fuel-derived raw materials, the amount of fossil fuel used can be reduced, and the environmental load can be decreased.

[0010] Bioethanol used in the production of biomass polyesters can be produced by a sugar fermentation method from molasses, which is a non-edible raw material, of sugarcane. However, it is empirically known that the yield of crops such as sugarcane is greatly affected by meteorological factors. Therefore, there is concern that it will become difficult to stably procure sugarcane, which is a raw material for bioethanol, due to climate change.

[0011] Ethanol and the like, which are also used as raw materials for plastics, are being produced from resources that are neither fossil fuels nor biomass. For example, ethanol is produced by microbial fermentation using carbon monoxide present in exhaust gases generated from ironworks and factories as a raw material (for example, Patent Document 4). In addition, carbon dioxide present in exhaust gases generated from ironworks and factories is electrolyzed to produce ethylene glycol (for example, Patent Document 5). Furthermore, the production of polyesters from these compounds is also being studied.

[0012] The production of a laminate, which is a component of a package, from a polyester produced from a fossil fuel-derived raw material or a polyester produced from a biomass raw material has been conventionally carried out. However, when a polyester produced using ethanol with carbon monoxide gas as a raw material or ethylene glycol with carbon dioxide gas as a raw material is used for a packaging film for a power storage device, it has not been clarified whether mechanical properties and the like similar to those of a conventional packaging film for a power storage device are exhibited.

[0013] The main object of the present disclosure is to provide a packaging film for a power storage device that can reduce environmental impact and is not inferior in terms of physical properties such as mechanical properties compared to a polyester using a conventional polyester film produced from a fossil fuel-derived raw material as a packaging film for a power storage device. Furthermore, the present disclosure also aims to provide a method for producing the packaging film for a power storage device and a power storage device using the packaging film for a power storage device.

[0014] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that a packaging film for energy storage devices, comprising a laminate comprising at least a base layer and a heat-sealable resin layer, wherein the laminate includes a polyester film, and the polyester film includes a polyester containing diol units and dicarboxylic acid units, and the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide, can reduce environmental impact and is comparable in terms of physical properties such as mechanical properties to a conventional polyester film made from fossil fuel-derived raw materials used for packaging devices.

[0015] This disclosure is the result of further consideration based on these findings. Specifically, this disclosure provides the invention in the following embodiments: A packaging film for energy storage devices, comprising at least a laminate comprising a base layer and a heat-fusible resin layer, wherein the laminate includes a polyester film, the polyester film includes a polyester containing diol units and dicarboxylic acid units, and the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

[0016] According to this disclosure, it is possible to provide a packaging film for energy storage devices that can reduce environmental impact and is comparable in terms of physical properties, such as mechanical characteristics, to conventional polyester films made from fossil fuel-derived raw materials. Furthermore, according to this disclosure, it is possible to provide a method for manufacturing the packaging film for energy storage devices and an energy storage device utilizing the packaging film for energy storage devices.

[0017] This is a schematic diagram showing an example of the cross-sectional structure of the packaging film for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the packaging film for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the packaging film for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the packaging film for energy storage devices of the present disclosure. This is a schematic diagram illustrating a method for housing an energy storage device element in a package formed from the packaging film for energy storage devices of the present disclosure.

[0018] The packaging film for energy storage devices of this disclosure comprises a laminate comprising at least a base layer and a heat-sealable resin layer, wherein the laminate includes a polyester film, and the polyester film includes a polyester containing diol units and dicarboxylic acid units, wherein the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. The packaging film for energy storage devices of this disclosure has a reduced environmental impact and exhibits properties in terms of physical properties such as mechanical properties that are comparable to conventional polyester packaging films for energy storage devices made from fossil fuel-derived raw materials.

[0019] The packaging film for energy storage devices described herein will be described in detail below. In this disclosure, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to". For example, the notation 2 to 15 mm means 2 mm or more and 15 mm or less. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Alternatively, upper and lower limits, upper and lower limits, or lower limits described separately may be combined to form numerical ranges. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0020] Furthermore, in packaging films for energy storage devices, the Machine Direction (MD) and Transfer Direction (TD) of the barrier layer 3 described later can usually be determined during the manufacturing process. For example, when the barrier layer 3 is made of metal foil such as aluminum alloy foil or stainless steel foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Also, in the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and determining the rolling direction (RD) of the metal foil. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined. Similarly, since the MD of the heat-fusible resin layer and the RD of the metal foil coincide, the MD of the heat-fusible resin layer can be determined by observing the surface of the metal foil in the laminate and identifying the rolling direction (RD) of the metal foil. Furthermore, since the TD of the heat-fusible resin layer is perpendicular to the MD of the heat-fusible resin layer, the TD of the heat-fusible resin layer can also be determined.

[0021] Furthermore, if the MD of a packaging film for energy storage devices cannot be identified by the rolling marks of metal foils such as aluminum alloy foil or stainless steel foil, it can be identified by the following method. One method for confirming the MD of a packaging film for energy storage devices is to observe the cross-section of the heat-sealable resin layer of the packaging film with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-sealable resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing each of the cross-sections (a total of 10 cross-sections) in the longitudinal direction of the heat-sealable resin layer, and each of the cross-sections perpendicular to the longitudinal direction, by changing the angle by 10 degrees from the direction parallel to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, the diameter y is defined as the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the heat-sealable resin layer and the rightmost point perpendicular to that point. For each cross-section, the average of the top 20 diameters y of the island shape, ordered from largest to smallest, is calculated. The direction parallel to the cross-section with the largest average diameter y of the island shape is determined to be the MD (Mid-Depth Direction).

[0022] <Laminated Structure and Physical Properties of Packaging Film for Energy Storage Devices> The packaging film 10 for energy storage devices of this disclosure is composed of a laminate having, for example, a base layer 1 and a heat-sealable resin layer 4 in that order from the outside, as shown in Figure 1. In the packaging film 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an energy storage device using the packaging film 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-sealing the peripheral edges of the heat-sealable resin layers 4 of the packaging film 10 facing each other. In the laminate constituting the packaging film 10 for energy storage devices of this disclosure, the base layer 1 side is the outside, and the heat-sealable resin layer 4 side is the inside. If the packaging film 10 for energy storage devices has a barrier layer 3, the base layer 1 side is outside the barrier layer 3, and the heat-sealable resin layer 4 side is inside the barrier layer 3.

[0023] The packaging film 10 for energy storage devices may have a barrier layer 3 between the base layer 1 and the heat-sealable resin layer 4, as shown in Figures 2 to 5, for example. When the packaging film 10 for energy storage devices has a barrier layer 3, it can be suitably used as an outer packaging material for energy storage devices. On the other hand, as shown in Figure 1, when the packaging film 10 for energy storage devices does not have a barrier layer 3, it can be suitably used as an inner bag film placed between the outer packaging material of the energy storage device and the energy storage device element. It should be noted that an outer packaging material is essential for an energy storage device to package the energy storage device element, but whether or not to provide an inner bag film between the outer packaging material and the energy storage device element is selected according to the design of the energy storage device, etc.

[0024] The packaging film 10 for energy storage devices may, for example, have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as needed, for the purpose of improving the adhesion between these layers, as shown in Figures 3 to 5. Furthermore, as shown in Figures 4 and 5, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4, as needed, for the purpose of improving the adhesion between these layers. Also, as shown in Figure 5, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (the side opposite to the heat-fusible resin layer 4), as needed.

[0025] The thickness of the laminate constituting the energy storage device packaging film 10 is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, for example, it can be about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the energy storage device packaging film, which is to protect the energy storage device elements, the thickness of the laminate constituting the energy storage device packaging film 10 can be preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, the preferred range of the laminate constituting the energy storage device packaging film 10 is, for example, approximately 35 to 300 μm, approximately 35 to 250 μm, approximately 35 to 210 μm, approximately 35 to 190 μm, approximately 35 to 180 μm, approximately 35 to 155 μm, approximately 35 to 120 μm, approximately 45 to 300 μm, approximately 45 to 250 μm, approximately 45 to 210 μm, approximately 45 to 190 μm, approximately 45 to 180 μm, approximately 45 to 155 μm, approximately 45 to 120 μm, approximately 60 to 300 μm, approximately 60 to 250 μm, and 6 Examples of suitable thicknesses include approximately 0-210 μm, 60-190 μm, 60-180 μm, 60-155 μm, 60-120 μm, 155-300 μm, 155-250 μm, 155-210 μm, 155-190 μm, 155-180 μm, 190-300 μm, 190-250 μm, and 190-210 μm. In particular, when creating lightweight thin films for energy storage devices, approximately 60-155 μm is preferred, and when improving moldability, approximately 155-190 μm is preferred.

[0026] In the packaging film 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3 (optionally provided), the adhesive layer 5 (optionally provided), the heat-sealable resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the packaging film 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Specifically, when the packaging film 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the packaging film 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, if the energy storage device packaging film 10 of this disclosure includes a base layer 1 and a heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the energy storage device packaging film 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Also, if the energy storage device packaging film 10 of this disclosure is a laminate containing a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the energy storage device packaging film 10 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0027] The packaging film for energy storage devices of this disclosure has a laminate strength between the base layer 1 and the barrier layer 3, as measured by the method described in <Measurement of Laminate Strength> below, preferably 5 N / 15 mm or more, more preferably 8 N / 15 mm or more, and even more preferably 10 N / 15 mm or more. The upper limit is preferably 25 N / 15 mm or less, more preferably 20 N / 15 mm or less, and even more preferably 18 N / 15 mm or less. Preferred ranges include approximately 5 to 25 N / 15 mm, approximately 5 to 20 N / 15 mm, approximately 5 to 18 N / 15 mm, approximately 8 to 25 N / 15 mm, approximately 8 to 20 N / 15 mm, approximately 8 to 18 N / 15 mm, approximately 10 to 25 N / 15 mm, approximately 10 to 20 N / 15 mm, and approximately 10 to 18 N / 15 mm.

[0028] <Measurement of Laminate Strength> From the packaging film for energy storage devices, cut out strips of material with a width of 15 mm in the TD direction and a length of 150 mm in the MD direction. Next, at the MD direction end of the sample, peel off approximately 10 mm from the base layer and the barrier layer in the MD direction, and extend the gripping area between the base layer and the barrier layer by attaching tape to both layers. Using the chucks of a commercially available tensile testing machine, grip the tape attached to the base layer and barrier layer, respectively, to prepare the measurement sample. For the obtained measurement sample, measure the laminate strength (peel strength) between the base layer and the barrier layer using a tensile testing machine under the conditions of 180-degree peel, tensile speed of 50 mm / min, and gauge length of 50 mm at 25°C and a 50% RH atmosphere. The strength when the gauge length reaches 57 mm is taken as the laminate strength. The average of three measurements is used. In the preparation of the measurement sample, the adhesive layer may be present on the surface of the substrate layer, on the surface of the barrier layer, or on both the substrate layer and the barrier layer in the area where the substrate layer and the barrier layer have been separated.

[0029] The packaging film for energy storage devices of this disclosure has a tensile breaking strength in the MD direction, as measured by the method described in <Measurement of Tensile Breaking Characteristics> below, preferably about 40 MPa or more, more preferably about 50 MPa or more, even more preferably about 60 MPa or more, and also preferably about 130 MPa or less, more preferably about 120 MPa or less, and even more preferably about 110 MPa or less. Preferred ranges include about 40 to 130 MPa, about 40 to 120 MPa, about 40 to 110 MPa, about 50 to 130 MPa, about 50 to 120 MPa, about 50 to 110 MPa, about 60 to 130 MPa, about 60 to 120 MPa, and about 60 to 110 MPa. Furthermore, the tensile breaking strength in the TD direction is preferably about 50 MPa or more, more preferably about 60 MPa or more, even more preferably about 70 MPa or more, and also preferably about 140 MPa or less, more preferably about 130 MPa or less, and even more preferably about 120 MPa or less. Preferred ranges include about 50 to 140 MPa, about 50 to 130 MPa, about 50 to 120 MPa, about 60 to 140 MPa, about 60 to 130 MPa, about 60 to 120 MPa, about 70 to 140 MPa, about 70 to 130 MPa, and about 70 to 120 MPa.

[0030] Furthermore, the packaging film for energy storage devices of this disclosure has a tensile break elongation in the MD direction, as measured by the method described in <Measurement of Tensile Breaking Characteristics> below, preferably about 10% or more, more preferably about 15% or more, even more preferably about 20% or more, and also preferably about 120% or less, more preferably about 110% or less, even more preferably about 100% or less. Preferred ranges include about 10-120%, about 10-110%, about 10-100%, about 15-120%, about 15-110%, about 15-100%, about 20-120%, about 20-110%, and about 20-100%. Furthermore, the tensile break elongation in the TD direction is preferably about 10% or more, more preferably about 15% or more, even more preferably about 20% or more, and also preferably about 120% or less, more preferably about 110% or less, and even more preferably about 100% or less. Preferred ranges include about 10-120%, about 10-110%, about 10-100%, about 15-120%, about 15-110%, about 15-100%, about 20-120%, about 20-110%, and about 20-100%.

[0031] <Measurement of Tensile Breaking Characteristics> In accordance with the provisions of JIS K7127:1999, the tensile breaking strength and tensile breaking elongation of the packaging film for energy storage devices will be measured in the MD direction and TD direction, respectively. A commercially available tensile testing machine will be used for the measurement. The measurement conditions will be as follows: Prepare a rectangular sample with a sample width of 15 mm and a sample length of 150 mm, one sample for tensile testing in the MD direction (15 mm width in the TD direction, 150 mm length in the MD direction) and one sample for tensile testing in the TD direction (15 mm width in the MD direction, 150 mm length in the TD direction), with a gauge spacing of 50 mm, a tensile speed of 100 mm / min, and a test environment of 23°C, and use the average value of three measurements.

[0032] <Polyester Film> The laminate constituting the packaging film for energy storage devices of this disclosure includes a polyester film. In the packaging film for energy storage devices of this disclosure, the layer containing the polyester film is not particularly limited, but it is preferably included in at least one of the base layer 1 and the heat-sealable resin layer 4, and more preferably in the base layer 1. The packaging film for energy storage devices of this disclosure may further include a polyester film in which the diol unit is ethylene glycol that does not use at least one gas selected from the group consisting of carbon monoxide and carbon dioxide as a raw material.

[0033] In this disclosure, the polyester film comprises a polyester consisting of diol units and dicarboxylic acid units, wherein the diol units contain ethylene glycol obtained from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

[0034] "Polyester" refers to a polymer polymerized by ester bonds. Such polyesters are usually obtained by polycondensation of diol units and dicarboxylic acid units. That is, the polyester contained in polyester films is obtained by polycondensation reaction using ethylene glycol, which is produced from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide, as the diol unit, and dicarboxylic acid as the dicarboxylic acid unit.

[0035] The following describes ethylene glycol produced using carbon monoxide gas as a raw material, and ethylene glycol produced using carbon dioxide gas as a raw material.

[0036] (Ethylene glycol produced from carbon monoxide gas) Ethylene glycol produced from carbon monoxide gas can be manufactured from ethanol produced from carbon monoxide gas. For example, ethylene glycol produced from carbon monoxide gas can be obtained by conventionally known methods, such as a method that generates ethylene glycol via ethylene oxide from ethanol produced from carbon monoxide gas.

[0037] (Microbial fermentation) Ethanol, which is produced from carbon monoxide gas, can be obtained through microbial fermentation.

[0038] Microbial fermentation is carried out, for example, in a fermentation tank filled with a culture medium containing water and microorganisms. A raw material gas containing carbon monoxide is supplied to the fermentation tank, and the carbon monoxide gas is converted to ethanol inside the tank. The raw material gas may also contain other substances besides carbon monoxide, such as carbon dioxide, nitrogen, or oxygen.

[0039] The fermentation tank is preferably a continuous fermentation apparatus, and may be of any type: agitated, air-lift, bubble tower, loop, open-bond, or photobio. The raw material gas and culture medium may be continuously supplied to the fermentation tank, but it is not necessary to supply the raw material gas and culture medium simultaneously; the raw material gas may be supplied to the fermentation tank after the culture medium has been supplied. The raw material gas is generally blown into the fermentation tank via a sparger or the like.

[0040] The culture medium is not particularly limited as long as it has an appropriate composition for culturing microorganisms, but it is a liquid containing water as the main component and nutrients (e.g., vitamins, phosphoric acid, etc.) dissolved or dispersed in this water.

[0041] The temperature of the fermentation tank is preferably controlled to 40°C or below. By controlling the temperature to 40°C or below, the microorganisms in the fermentation tank do not die, and ethanol is efficiently produced when the raw material gas comes into contact with the microorganisms. The temperature of the fermentation tank is more preferably 38°C or below, and more preferably 10°C or above, more preferably 20°C or above, and even more preferably 30°C or above, in order to enhance the activity of the microorganisms.

[0042] The microorganisms (species) used to ferment the raw material gas are not particularly limited, as long as they can produce ethanol by fermenting the raw material gas using carbon monoxide as the main raw material. For example, it is preferable that the microorganisms (species) produce ethanol from the raw material gas through the fermentation action of gas-assimilating bacteria. Among gas-assimilating bacteria, the genus Clostridium is preferred from the viewpoint of gas assimilation and culture stability, and Clostridium autoetanogenum is more preferred. Further examples are given below.

[0043] Gas-utilizing bacteria include both eubacteria and archaea.

[0044] Examples of true bacteria include bacteria of the genera Clostridium, Moorella, Acetobacterium, Carboxydocella, Rhodopseudomonas, Eubacterium, Butyribacterium, Oligotropha, Bradyrhizobium, and the aerobic hydrogen-oxidizing bacteria Ralsotonia.

[0045] On the other hand, examples of archaea include bacteria of the genus Methanobacterium, bacteria of the genus Methanobrevibacter, bacteria of the genus Methanocalculus, bacteria of the genus Methanococcus, bacteria of the genus Methanosarcina, bacteria of the genus Methanosphaera, bacteria of the genus Methanothermobacter, Metha Examples include bacteria of the genus Nothrix, bacteria of the genus Methanoculleus, bacteria of the genus Methanofollis, bacteria of the genus Methanogenium, bacteria of the genus Methanospirillium, bacteria of the genus Methanosaeta, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, bacteria of the genus Arcaheoglobus, and the like. Among these, as archaea, bacteria of the genus Methanosarcina, bacteria of the genus Methanococcus, bacteria of the genus Methanothermobacter, bacteria of the genus Methanothrix, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, and bacteria of the genus Archaeoglobus are preferred.

[0046] Furthermore, due to their excellent assimilation capabilities of carbon monoxide and carbon dioxide, archaeons of the genera Methanosarcina, Methanothermobacter, or Methanococcus are preferred, with Methanosarcina or Methanococcus being particularly preferred. Specific examples of Methanosarcina bacteria include Methanosarcina barkeri, Methanosarcina mazei, and Methanosarcina acetivorans.

[0047] From among the gas-assimilating bacteria described above, it is preferable to select and use bacteria with high ethanol production capacity. For example, Clostridium autoethanogenum, Clostridium ljungdahlii, Clostridium aceticum, Clostridium carboxidivorans, Moorella thermoacetica, Acetobacterium woodii, etc. are preferred.

[0048] Ethanol produced by microbial fermentation is obtained, for example, as an ethanol-containing liquid mixed with a culture medium. Ethanol can be separated from this ethanol-containing liquid using a separation device. Examples of separation devices include solid-liquid separators, distillation devices, and separation membranes, but it is preferable to use a combination of a solid-liquid separator and a distillation device. The separation process using a combination of a solid-liquid separator and a distillation device will be described in detail below.

[0049] The ethanol-containing liquid obtained by microbial fermentation is separated in a solid-liquid separation apparatus into a solid component mainly consisting of microorganisms and a liquid component containing ethanol. The ethanol-containing liquid obtained by microbial fermentation contains not only the target product, ethanol, but also microorganisms and their remains that were present in the fermentation tank as solid components, so solid-liquid separation is performed to remove these. Examples of solid-liquid separation apparatuses include filters, centrifuges, and apparatuses using solution precipitation methods. Alternatively, the solid-liquid separation apparatus may be an apparatus that evaporates the liquid component containing ethanol from the ethanol-containing liquid and separates it from the solid component (for example, a heating and drying apparatus). In this case, all of the liquid component containing the target product, ethanol, may be evaporated, or the liquid component may be partially evaporated so that the target ethanol evaporates preferentially.

[0050] The liquid components separated by solid-liquid separation are further distilled in a distillation apparatus to separate the target product, ethanol. This distillation separation allows for the purification of large quantities of ethanol to high purity with a simple operation.

[0051] When performing distillation, known distillation apparatus such as a distillation column can be used. Furthermore, in distillation, for example, the process is carried out so that the distillate contains the target product, ethanol, in high purity, while the bottom liquid (i.e., distillation residue) contains water as the main component (for example, 70% by mass or more, preferably 90% by mass or more). By carrying out the process in this way, the target product, ethanol, and water can be largely separated.

[0052] The temperature inside the distillation apparatus during ethanol distillation is not particularly limited, but is preferably 100°C or lower, more preferably 95°C or lower, and preferably 70°C or higher. By setting the temperature inside the distillation apparatus within the above range, the separation of ethanol from other components such as water can be reliably achieved.

[0053] The pressure inside the distillation apparatus during ethanol distillation may be atmospheric pressure, but is preferably less than atmospheric pressure, and more preferably 60 kPa to 150 kPa. By setting the pressure inside the distillation apparatus within this range, the separation efficiency of ethanol can be improved, and the yield of ethanol can be increased.

[0054] (Ethylene glycol produced from carbon dioxide gas) Ethylene glycol produced from carbon dioxide gas can be obtained by electrolysis of carbon dioxide gas. The following describes the method for producing ethylene glycol from carbon dioxide gas by electrolysis.

[0055] (Electrolysis) Electrolysis can be performed, for example, using an electrolytic cell comprising an anode, a cathode, and an ion exchange membrane arranged to separate the anode and the cathode.

[0056] The anode undergoes the oxidation reaction of water (H₂O), producing oxygen (O₂) and hydrogen ions (H₂O). + ) is generated. Alternatively, the hydroxide ions (OH-) produced on the cathode side undergo an oxidation reaction, producing oxygen (O2) and water (H2O). On the other hand, the cathode produces hydrogen ions (H) produced on the anode side. + ) and electrons (e - This process involves reducing carbon dioxide (CO2) and reducing carbon compounds produced by the reduction of carbon dioxide, thereby generating carbon compounds such as ethylene glycol (C2H6O2). In this way, ethylene glycol can be produced using carbon dioxide as a raw material by reducing carbon dioxide on the cathode side of the electrolytic cell.

[0057] The anode is preferably composed mainly of a catalytic material capable of reducing the overpotential of the reaction that oxidizes water or hydroxide ions. Examples of such catalytic materials include metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys and intermetallic compounds containing these metals, binary metal oxides such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, and Sr-Fe-O, quaternary metal oxides such as Pb-Ru-Ir-O and La-Sr-Co-O, and metal complexes such as Ru complexes and Fe complexes.

[0058] The cathode is preferably composed of a catalytic material capable of reducing the overpotential of the reaction that reduces carbon dioxide. Examples of such catalytic materials include metals such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), and tin (Sn), as well as alloys and intermetallic compounds containing at least one of these metals, carbon materials such as carbon (C), graphene, CNT (carbon nanotube), fullerene, and Ketjenblack, and metal complexes such as Ru complexes and Re complexes.

[0059] (Diol Units) The diol units used in this disclosure are not limited to ethylene glycol produced from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. That is, ethylene glycol produced from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide may be used in combination with other diols. Even when used in combination with other diols, as long as ethylene glycol produced from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide is used, this disclosure can reduce the environmental burden.

[0060] Other examples of diols include diols derived from fossil fuels and diols derived from biomass.

[0061] As the fossil fuel-derived diol, compounds having two or more, preferably two to eight, hydroxyl groups in one molecule can be used. Specifically, the fossil fuel-derived diol is not particularly limited and conventionally known compounds can be used, such as polypropylene glycol (PPG), neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG), butylene glycol (BG), hexamethylene glycol, triethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, etc. These can be used individually or in combination of two or more.

[0062] As biomass-derived diols, aliphatic diols obtained from plant raw materials such as corn, sugarcane, cassava, and sago palm can be used. Examples of biomass-derived aliphatic diols include polypropylene glycol (PPG), neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG), butylene glycol (BG), and hexamethylene glycol, all of which can be obtained from plant raw materials by the methods described below. These may be used alone or in combination.

[0063] Biomass-derived polypropylene glycol is produced by a fermentation method that breaks down plant materials to obtain glucose, via glycerol to 3-hydroxypropyl aldehyde (HPA). Compared to polypropylene glycol produced by the fermentation method described above, polypropylene glycol produced by bio-methods such as fermentation is preferable in terms of safety, yields useful by-products such as lactic acid, and can also be produced at a lower cost.

[0064] Biomass-derived butylene glycol can be produced by manufacturing glycol from plant materials, obtaining succinic acid through fermentation, and then hydrogenating it. Biomass-derived ethylene glycol can be produced, for example, from bioethanol obtained by conventional methods via ethylene.

[0065] (Dicarboxylic acid units) For polyester dicarboxylic acid units, for example, dicarboxylic acids derived from fossil fuels are used. Aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their derivatives can be used without limitation as dicarboxylic acids derived from fossil fuels.

[0066] Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and dimethyl terephthalate is preferred as a derivative of aromatic dicarboxylic acid.

[0067] Furthermore, specific examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid, which are typically linear or alicyclic dicarboxylic acids with 2 to 40 carbon atoms. Derivatives of aliphatic dicarboxylic acids include lower alkyl esters such as methyl esters, ethyl esters, propyl esters, and butyl esters of the above aliphatic dicarboxylic acids, and cyclic acid anhydrides of the above aliphatic dicarboxylic acids, such as succinic anhydride. Among these, adipic acid, succinic acid, dimer acid, or mixtures thereof are preferred, and those mainly composed of succinic acid are particularly preferred. Methyl esters of adipic acid and succinic acid, or mixtures thereof, are more preferred as derivatives of aliphatic dicarboxylic acids.

[0068] Furthermore, the dicarboxylic acid units of the polyester may be dicarboxylic acids derived from biomass.

[0069] As biomass-derived dicarboxylic acids, aliphatic dicarboxylic acids obtained from plant raw materials such as renewable plant-derived oils like soybean oil, linseed oil, tung oil, coconut oil, palm oil, and castor oil, as well as recycled oils mainly composed of these used in waste cooking oils, can be used. Examples of biomass-derived aliphatic dicarboxylic acids include sebacic acid, succinic acid, phthalic acid, adipic acid, glutaric acid, and dimer acid. For example, sebacic acid is produced as a byproduct of heptyl alcohol by alkaline thermal decomposition of ricinoleic acid obtained from castor oil.

[0070] Furthermore, biomass-derived terephthalic acid can be used as an aromatic dicarboxylic acid derived from biomass. Biomass-derived terephthalic acid can be produced, for example, by manufacturing isobutanol from corn, sugars, or wood, then converting isobutanol to isobutylene, then dimerizing it to produce isooctene, then synthesizing p-xylene via radical cleavage, recombination, and cyclization, and finally oxidizing it (International Publication No. 2009 / 079213).

[0071] When using biomass-derived dicarboxylic acids as dicarboxylic acid units, this disclosure particularly prefers the use of biomass-derived terephthalic acid.

[0072] Furthermore, the dicarboxylic acid units of the polyester may be dicarboxylic acids derived from carbon dioxide gas.

[0073] An example of a dicarboxylic acid produced using carbon dioxide gas as a raw material is terephthalic acid produced using carbon dioxide gas. Terephthalic acid produced using carbon dioxide gas can be produced, for example, by using a composite catalyst containing chromium oxide and a predetermined H-ZSM-5 zeolite to produce p-xylene using carbon dioxide gas and hydrogen gas as raw materials, and then oxidizing the p-xylene (Japanese Patent Publication No. 2019-205969).

[0074] These dicarboxylic acids can be used individually or in combination of two or more.

[0075] The polyester may be a copolymerized polyester in which a copolymerizing component is added as a third component in addition to the diol units and dicarboxylic acid units described above. Specific examples of copolymerizing components include a bifunctional oxycarboxylic acid, and at least one polyfunctional compound selected from the group consisting of trifunctional or higher polyhydric alcohols, trifunctional or higher polyhydric acids and / or their anhydrides, and trifunctional or higher oxycarboxylic acids, in order to form a crosslinked structure. Among these copolymerizing components, bifunctional and / or trifunctional or higher oxycarboxylic acids are particularly preferred because they tend to easily produce copolymerized polyesters with a high degree of polymerization. Among these, the use of trifunctional or higher oxycarboxylic acids is most preferred because it is possible to easily produce polyesters with a high degree of polymerization in very small amounts without using chain extenders, which will be described later.

[0076] Furthermore, the above-mentioned polyester may be a high-molecular-weight polyester obtained by chain extension (coupling) of these copolymerized polyesters. Chain extenders such as carbonate compounds and diisocyanate compounds can also be used, but the amount is usually 10 mol% or less, preferably 5 mol% or less, and more preferably 3 mol% or less, of the total monomer units constituting the polyester, for carbonate bonds and urethane bonds.

[0077] Examples of carbonate compounds include diphenyl carbonate, ditrile carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, and dicyclohexyl carbonate. In addition, carbonate compounds derived from hydroxy compounds such as phenols and alcohols, or composed of the same or different hydroxy compounds, can be used.

[0078] Examples of diisocyanate compounds include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0079] The polyester used in this disclosure can be obtained by conventionally known methods of polycondensation of the above-mentioned diol units and dicarboxylic acid units. Specifically, it can be produced by general melt polymerization methods such as performing an esterification reaction and / or transesterification reaction between the above-mentioned diol units and dicarboxylic acid units, followed by a polycondensation reaction under reduced pressure, or by known solution heating dehydration condensation methods using organic solvents.

[0080] The amount of diol used in the production of polyester is substantially equimolar to 100 moles of dicarboxylic acid or its derivative. However, generally, due to distillation during esterification and / or transesterification and / or condensation polymerization reactions, an excess of 0.1 mol% to 20 mol% is used.

[0081] Furthermore, the polycondensation reaction is preferably carried out in the presence of a polymerization catalyst. The timing of adding the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction; it may be added when the raw materials are being charged, or when the reduced pressure is started.

[0082] Polymerization catalysts generally include compounds containing metal elements from groups 1 to 14 of the periodic table, excluding hydrogen and carbon. Specifically, these include compounds containing organic groups such as carboxylates, alkoxy salts, organic sulfonates, or β-diketate salts, which contain at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium, as well as inorganic compounds such as oxides and halides of the aforementioned metals and mixtures thereof. Among these, metal compounds containing titanium, zirconium, germanium, zinc, aluminum, magnesium, or calcium, or mixtures thereof, are preferred, with titanium compounds, zirconium compounds, or germanium compounds being particularly preferred. Furthermore, because the polymerization rate is higher when the catalyst is molten or dissolved during polymerization, it is preferable that the catalyst be liquid during polymerization or a compound that dissolves in ester low polymers or polyesters.

[0083] As titanium compounds, tetraalkyl titanates are preferred, specifically including tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, or mixed titanates thereof. Titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium (diisoproxide)acetylacetonate, titanium bis(ammonium lactate) dihydroxyl, titanium bis(ethyl acetate) diisopropoxide, titanium (triethanolamine) isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolamine, butyl titanate dimer, etc. are also suitably used. Furthermore, titanium oxide and composite oxides containing titanium and silicon are also suitably used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium(oxy)acetylacetonate, titaniumtetraacetylacetonate, titanium bis(ammonium lactate) dihydroxyde, polyhydroxytitanium stearate, titanium lactate, butyl titanate dimer, titanium oxide, and titania / silica composite oxide (for example, product name: C-94 from Accordis Industrial Fibers) are preferred, and in particular, tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium(oxy)acetylacetonate, titaniumtetraacetylacetonate, and titania / silica composite oxide (for example, product name: C-94 from Accordis Industrial Fibers) are preferred.

[0084] Specific examples of zirconium compounds include zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris(butoxy)stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, potassium zirconium oxalate, polyhydroxyzirconium stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate, or mixtures thereof. Zirconium oxide or, for example, a composite oxide containing zirconium and silicon may also be used. Among these, zirconyl diacetate, zirconium tris(butoxy) stearate, zirconium tetraacetate, zirconium acetate hydroxide, zirconium ammonium oxalate, zirconium potassium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, and zirconium tetra-t-butoxide are preferred.

[0085] Germanium compounds include, specifically, inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. Due to their price and availability, germanium oxide, tetraethoxygermanium, or tetrabutoxygermanium are preferred, and germanium oxide is particularly preferred.

[0086] When using metal compounds as polymerization catalysts, the amount of catalyst used, as the amount of metal relative to the resulting polyester, has a lower limit of 5 ppm or more, preferably 10 ppm or more, and an upper limit of 30,000 ppm or less, preferably 1,000 ppm or less, more preferably 250 ppm or less, and particularly preferably 130 ppm or less. Using too much catalyst is not only economically disadvantageous but also reduces the thermal stability of the polymer, while using too little reduces polymerization activity, which in turn makes the polymer more susceptible to decomposition during polymer production. In this context, reducing the amount of catalyst used reduces the amount of terminal carboxyl groups in the resulting polyester, so reducing the amount of catalyst used is a preferred approach.

[0087] The reaction temperature for esterification and / or transesterification reactions between diol units and dicarboxylic acid units is typically in the range of 150°C to 260°C, and the reaction atmosphere is typically under an inert gas atmosphere such as nitrogen or argon. The reaction pressure is typically between atmospheric pressure and 10 kPa. The reaction time is typically between 1 hour and 10 hours.

[0088] In the manufacturing process described above, a chain extender (coupling agent) may be added to the reaction system. After the polycondensation is complete, the chain extender is added to the reaction system in a uniform molten state without a solvent and reacted with the polyester obtained by polycondensation.

[0089] High molecular weight polyesters using these chain extenders (coupling agents) can be manufactured using known techniques. The chain extender is added to the reaction system in a uniform molten state without a solvent after the polycondensation is complete, and reacted with the polyester obtained by polycondensation. Specifically, a polyester with a higher molecular weight can be obtained by reacting the above-mentioned chain extender with a polyester prepolymer obtained by catalytic reaction of a diol and a dicarboxylic acid, which has substantially hydroxyl groups at its terminals and a mass-average molecular weight (Mw) of 20,000 or more, preferably 40,000 or more. If the prepolymer has a mass-average molecular weight of 20,000 or more, even under harsh conditions such as a molten state, the residual catalyst will not affect the reaction, and high molecular weight polyester can be produced without the formation of gel during the reaction, even with the use of a small amount of coupling agent.

[0090] In this disclosure, the polyester film is a film containing the polyester described above. That is, it is a film containing polyester (hereinafter also referred to as "gas-derived polyester") made from ethylene glycol using at least one gas selected from the group consisting of carbon monoxide and carbon dioxide as a raw material.

[0091] From the viewpoint of reducing environmental impact, the content of gas-derived polyester in the polyester film is preferably 50% by mass or more, preferably 80% by mass or more, and preferably 95% by mass or more. Furthermore, the content of gas-derived polyester in the polyester film is 100% by mass or less, 99% by mass or less is practical, and 97% by mass or less is more practical.

[0092] The polyester film may contain various additives, to the extent that the properties of the present disclosure are not impaired. Examples of additives include plasticizers, ultraviolet stabilizers, color inhibitors, matting agents, deodorants, flame retardants, weather-resistant agents, antistatic agents, yarn friction reducers, mold release agents, antioxidants, ion exchange agents, and coloring pigments. The content of these additives is, for example, 5% by mass or more and 50% by mass or less.

[0093] To obtain a polyester film by processing polyester into a film shape, a conventional method of forming a film from polyester can be employed. Specifically, after drying gas-derived polyester pellets, the pellets are supplied to a melt extruder heated to a temperature above the melting point (Tm) and below Tm + 70°C to melt the pellets. The melted pellets are then extruded into a sheet shape through a die, such as a T-die, and the extruded sheet is rapidly cooled and solidified in a rotating cooling drum or the like to form a polyester film. The polyester film obtained in this way consists of a single layer.

[0094] As for the melt extruder, single-screw extruders, twin-screw extruders, vented extruders, tandem extruders, etc., can be used depending on the purpose.

[0095] The polyester film according to this disclosure is preferably biaxially stretched. Biaxial stretching can be carried out by conventionally known methods, and may be sequential or simultaneous biaxial stretching. Sequential and simultaneous biaxial stretching will be described below.

[0096] (Sequential biaxial stretching) In sequential biaxial stretching, the film extruded onto the cooling drum as described above is stretched in the longitudinal direction, and then the film is stretched in the transverse direction.

[0097] Longitudinal stretching is usually performed by the difference in peripheral speed of the rolls and may be done in one stage or in multiple stages using multiple pairs of rolls. The longitudinal stretching ratio is preferably 2.0 times or more, more preferably 2.5 times or more, preferably 15.0 times or less, more preferably 7.0 times or less, even more preferably 5.0 times or less, and even more preferably 4.2 times or less. This suppresses variations in optical properties such as in-plane phase difference.

[0098] The stretching temperature is preferably 50°C or higher, more preferably 80°C or higher, even more preferably 95°C or higher, and preferably 120°C or lower, more preferably 115°C or lower, and even more preferably 110°C or lower. This suppresses variations in optical properties such as in-plane phase difference.

[0099] Transverse stretching is typically performed using the tenter method, where the film is transported while being held at both ends with clips. The transverse stretching ratio is preferably 2 times or more, more preferably 2.5 times or more, preferably 15 times or less, and more preferably 5 times or less. This helps to suppress variations in optical properties such as in-plane phase difference.

[0100] The stretching temperature is preferably 50°C or higher, more preferably 90°C or higher, even more preferably 95°C or higher, and preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 105°C or lower. This suppresses variations in optical properties such as in-plane phase difference.

[0101] As described above, the sequentially biaxially stretched film is preferably subjected to a heat treatment in a tenter that is above the stretching temperature but below the melting point in order to impart flatness and dimensional stability. Specifically, it is preferable to perform heat setting at a temperature of 120°C or higher, more preferably 190°C or higher, and more preferably 235°C or lower, and more preferably 225°C or lower. Furthermore, from the viewpoint of suppressing variations in optical properties such as in-plane phase difference, it is preferable to perform a heat treatment extension of 1% to 10% or less in the first half of the heat treatment. This makes it possible to suppress variations in optical properties such as in-plane phase difference.

[0102] After heat treatment, the film is slowly cooled to room temperature before being wound up. Additionally, relaxation treatments may be used in combination with heat treatment and slow cooling as needed. The relaxation rate during heat treatment is preferably 0.5% or more, more preferably 0.8% or more, even more preferably 1% or more, preferably 5% or less, more preferably 3% or less, even more preferably 2.5% or less, and even more preferably 2% or less. This suppresses variations in optical properties such as in-plane phase difference. The relaxation rate during slow cooling is preferably 0.5% or more, preferably 3% or less, more preferably 2% or less, even more preferably 1.5% or less, and even more preferably 1.0% or less. This suppresses variations in optical properties such as in-plane phase difference. From the viewpoint of flatness, the temperature during slow cooling is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower.

[0103] (Simultaneous Biaxial Stretching) In simultaneous biaxial stretching, the film extruded onto the cooling drum as described above is guided to a simultaneous biaxial tenter, and while gripping both ends of the film with clips, it is transported and stretched simultaneously and / or in stages in the longitudinal and transverse directions. Simultaneous biaxial stretchers include pantograph type, screw type, drive motor type, and linear motor type, but the drive motor type or linear motor type is preferred because the stretching ratio can be changed arbitrarily and relaxation processing can be performed at any point.

[0104] The magnification ratio for simultaneous biaxial stretching is preferably 2 times or more as an area magnification, more preferably 3 times or more, even more preferably 6 times or more, even more preferably 10 times or more, and also preferably 50 times or less, more preferably 30 times or less, even more preferably 25 times or less, even more preferably 20 times or less, and particularly preferably 15 times or less. This suppresses variations in optical properties such as in-plane phase difference.

[0105] In the case of simultaneous biaxial stretching, it is preferable to make the stretching ratios in the longitudinal and transverse directions the same, and to make the stretching speeds approximately equal, in order to suppress in-plane orientation differences.

[0106] The stretching temperature for simultaneous biaxial stretching is preferably 50°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower. This suppresses variations in optical properties such as in-plane phase difference.

[0107] It is preferable to subsequently heat-treat the simultaneously biaxially stretched film in a heat-setting chamber within a tenter, above the stretching temperature and below the melting point, in order to impart flatness and dimensional stability. The conditions for this heat treatment are the same as those for the heat treatment after sequential biaxial stretching.

[0108] The thickness of the polyester film is arbitrary depending on its application, but is usually between 5 μm and 500 μm. The tensile breaking strength of such a film is between 10 MPa and 600 MPa in the MD direction and between 10 MPa and 600 MPa in the TD direction, and the tensile breaking elongation is between 10% and 350% in the MD direction and between 3% and 300% in the TD direction. Thus, the polyester film according to this disclosure has physical properties equivalent to those of conventional polyester films manufactured from fossil fuel-derived materials or biomass-derived materials.

[0109] The polyester film included in the packaging film for energy storage devices of this disclosure is not limited to a single-layer configuration, but may also have a multi-layer configuration. When the polyester film of this disclosure has a multi-layer configuration, at least one layer may contain gas-derived polyester, while the other layers may not contain gas-derived polyester. Examples of polyesters that constitute the layers not containing gas-derived polyester include at least one selected from the group consisting of fossil fuel-derived polyester, biomass-derived polyester, and recycled polyester. Recycled polyester refers to polyester that has been collected and recycled from used containers and other products that have been shipped to the market.

[0110] Polyester films can also be subjected to secondary processing to impart various surface functions such as chemical, electrical, magnetic, mechanical, friction / abrasion / lubrication, optical, thermal, and biocompatibility. Examples of secondary processing include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, and surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[0111] <Layers forming the packaging film for energy storage devices> [Base layer 1] In this disclosure, the base layer 1 is a layer provided for purposes such as enabling the packaging film for energy storage devices to function as a base material. The base layer 1 is located on the outer layer side of the packaging film for energy storage devices.

[0112] The material forming the base layer 1 is not particularly limited, as long as it has the function of a base material, that is, at least insulating properties. The base layer 1 can be formed using, for example, a resin, and the resin may contain additives described later.

[0113] When the base layer 1 is formed of a resin, the base layer 1 can be formed, for example, of a resin film. When the base layer 1 is formed of a resin film, a pre-formed resin film may be used as the base layer 1 when manufacturing the packaging film 10 for energy storage devices of this disclosure by laminating the base layer 1 with a barrier layer 3 or the like. Alternatively, the resin forming the base layer 1 may be formed into a film on the surface of a barrier layer 3 or the like by extrusion molding or coating, resulting in a base layer 1 formed of a resin film. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include sequential biaxial stretching, inflation method, and simultaneous biaxial stretching. Examples of resin coating methods include roll coating, gravure coating, and extrusion coating.

[0114] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. The resin forming the base layer 1 may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins.

[0115] When the resin forming the substrate layer of this disclosure includes polyester, it is preferable to use a polyester film as described in the section on <Polyester Film> (i.e., a polyester film containing a polyester comprising diol units and dicarboxylic acid units, wherein the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide). Details of the polyester film are as described in the section on <Polyester Film>.

[0116] The base layer 1 preferably contains these resins as its main component, and more preferably contains polyester or polyamide as its main component. Here, "main component" means that among the resin components contained in the base layer 1, the content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the base layer 1 contains polyester or polyamide as its main component, it means that among the resin components contained in the base layer 1, the content of polyester or polyamide is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0117] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0118] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). Furthermore, the polyester may be a copolymer of two or more polyesters selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate. These polyesters may be used individually or as mixtures of two or more types.

[0119] Furthermore, examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0120] The base layer 1 preferably contains at least one of polyester film, polyamide film, and polyolefin film, preferably at least one of stretched polyester film, stretched polyamide film, and stretched polyolefin film, more preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, and stretched polypropylene film, and even more preferably at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

[0121] The base layer 1 may be a single layer or may consist of two or more layers. If the base layer 1 consists of two or more layers, the base layer 1 may be a laminate formed by laminating resin films with an adhesive, or it may be a laminate of two or more resin films formed by co-extruding resin. Furthermore, the laminate of two or more resin films formed by co-extruding resin may be used as the base layer 1 in its unstretched state, or it may be used as the base layer 1 after uniaxial stretching or biaxial stretching.

[0122] Specific examples of a laminate of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film is located in the outermost layer of the base layer 1. In a laminate of a polyester resin film and a polyamide resin film, the preferred thickness range of the polyester resin film is approximately 2-33 μm, 2-28 μm, 2-23 μm, 2-18 μm, 2-11 μm, 2-8 μm, 10-33 μm, 10-28 μm, 10-23 μm, 10-18 μm, 10-11 μm, 18-33 μm, and 18-28 μm. The thickness is approximately 18 to 23 μm. Preferred ranges for the thickness of the polyamide resin film include approximately 2 to 33 μm, 2 to 28 μm, 2 to 23 μm, 2 to 18 μm, 2 to 11 μm, 2 to 8 μm, 10 to 33 μm, 10 to 28 μm, 10 to 23 μm, 10 to 18 μm, 10 to 11 μm, 18 to 33 μm, 18 to 28 μm, and 18 to 23 μm.

[0123] If the base layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in adhesive layer 2 described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and then laminated. The anchor coat layer is similar to the adhesive exemplified in adhesive layer 2 described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0124] Furthermore, at least one of the surface and interior of the base layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, and colorants. Only one type of additive may be used, or two or more types may be mixed and used.

[0125] In this disclosure, from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0126] When the lubricant is present on the surface of the base material layer 1, the amount of its presence is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Also, as the amount of the lubricant present on the surface of the base material layer 1, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Also, the preferable range of the amount of the lubricant present on the surface of the base material layer 1 is about 3 - 15 mg / m 2 degree, about 3 - 14 mg / m 2 degree, about 3 - 10 mg / m 2 degree, about 4 - 15 mg / m 2 degree, about 4 - 14 mg / m 2 degree, about 4 - 10 mg / m 2 degree, about 5 - 15 mg / m 2 degree, about 5 - 14 mg / m 2 degree, about 5 - 10 mg / m 2 degree.

[0127] The lubricant present on the surface of the base material layer 1 may be one obtained by exuding the lubricant contained in the resin constituting the base material layer 1, or may be one obtained by applying the lubricant to the surface of the base material layer 1.

[0128] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 μm or more, preferably about 10 μm or more. Also, examples of the thickness of the base layer 1 can be about 100 μm or less, about 90 μm or less, about 70 μm or less, about 50 μm or less, preferably about 35 μm or less, 11 μm or less, or 8 μm or less. Furthermore, preferred thickness ranges for the base layer 1 include approximately 3 to 100 μm, 3 to 90 μm, 3 to 70 μm, 3 to 50 μm, 3 to 35 μm, 3 to 11 μm, 3 to 8 μm, 10 to 100 μm, 10 to 90 μm, 10 to 70 μm, 10 to 50 μm, 10 to 35 μm, and 10 to 11 μm. In particular, when making energy storage devices into lightweight thin films, thicknesses of approximately 3 to 35 μm, 3 to 11 μm, and 3 to 8 μm are preferred, and when improving moldability, thicknesses of approximately 35 to 50 μm are preferred. When the base layer 1 is a laminate of two or more resin films, the thickness of the resin film constituting each layer is not particularly limited, but examples include approximately 2 μm or more, preferably approximately 10 μm or more and approximately 18 μm or more, respectively. Furthermore, the thickness of the resin film constituting each layer can be, for example, about 33 μm or less, preferably about 28 μm or less, about 23 μm or less, about 18 μm or less, 11 μm or less, or 8 μm or less. In addition, preferred ranges for the thickness of the resin film constituting each layer can be about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, or about 18 to 23 μm.

[0129] The base layer 1 contains a coloring agent, which allows the packaging film for energy storage devices to be colored. Known coloring agents such as pigments and dyes can be used. Furthermore, only one type of coloring agent may be used, or two or more types may be mixed together.

[0130] The type of pigment is not particularly limited, as long as it does not impair the function of the substrate layer 1 as a substrate. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0131] Among colorants, carbon black is preferred for, for example, to give the appearance of packaging film for energy storage devices a black color. Furthermore, from the viewpoint of dissipating heat generated from energy storage devices, mica is preferred.

[0132] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0133] The amount of colorant in the base layer 1 is not particularly limited as long as the packaging film for the energy storage device is colored, and for example, it can be about 5 to 60% by mass, preferably about 10 to 40% by mass.

[0134] Ink may be printed on the surface of the base layer 1 of the packaging film for energy storage devices. Furthermore, energy storage devices may experience friction between devices, friction between devices and surrounding components, and friction during transport of the devices. For this reason, in addition to good ink adhesion (good printing characteristics) on the surface of the base layer of the packaging film for energy storage devices, it is preferable that the fixed ink does not easily disappear. From this viewpoint, it is preferable that the contact angle of the surface of the base layer 1 of the packaging film for energy storage devices is 110° or less. That is, in this case, if the base layer 1 constitutes the outermost surface of the packaging film for energy storage devices, the contact angle of the surface of the base layer 1 will be 110° or less. Also, if the surface coating layer is provided on the outside of the base layer 1, the contact angle of the surface of the surface coating layer will be 110° or less. When the contact angle of the surface on the base layer 1 side of the packaging film for energy storage devices is 110° or less, the ink is less likely to be repelled on the surface on the base layer 1 side, resulting in excellent printability, and furthermore, the fixed ink is less likely to disappear. In particular, when printing ink by pad printing on a packaging film for energy storage devices in which a lubricant is present on the surface on the base layer 1 side to improve moldability, the ink may be repelled on the surface on the base layer 1 side, resulting in printing defects. Even in such cases, if the contact angle of the surface on the base layer 1 side is set to 80° or less, the ink is less likely to be repelled, making it a particularly suitable packaging film for energy storage devices in which printing or other designs are formed on the surface of the base layer 1 side by pad printing.

[0135] From the viewpoint of improving printability and making it less likely for the fixed ink to disappear, it is more preferable that the contact angle of the surface on the substrate layer 1 side be 100° or less, and even more preferable that it be 90° or less. The contact angle of the surface on the substrate layer 1 side can be determined, for example, by using a commercially available contact angle measuring device to measure the contact angle of the interface between the substrate and the water droplet 5 seconds after the water droplet is placed on it.

[0136] The contact angle of the surface on the substrate layer 1 side can be preferably reduced to 110° or less by, for example, applying corona treatment to the surface on the substrate layer 1 side. Corona treatment can be performed by irradiating the surface on the substrate layer side with corona discharge using a commercially available corona surface treatment device. The conditions for corona treatment can be such that the contact angle of the surface on the substrate layer 1 side can be reduced to 110° or less by treating the surface on the substrate layer 1 side with an irradiation output of 1 kW or more and a speed of 10 MT / min.

[0137] Furthermore, when printing ink on the surface of the packaging film for energy storage devices, a step is performed in which, after corona treatment, ink is printed on at least a portion of the surface of the base layer 1. The printing method is not particularly limited, but when printing on the packaging film for energy storage devices after molding, pad printing is preferred. Since the contact angle of the surface on the base layer 1 side of the packaging film for energy storage devices is set to 110° or less, ink can be suitably printed even by pad printing, in which ink is easily repelled in the base layer where a lubricant is present on the surface. Therefore, for example, barcodes, patterns, characters, etc. can be suitably formed on at least a portion of the surface of the base layer 1.

[0138] Furthermore, the packaging film for energy storage devices of this disclosure preferably has fine irregularities on at least one surface of the outermost layer. Methods for forming fine irregularities on the surface of the outermost layer of the packaging film for energy storage devices include adding additives such as fine particles to the outermost layer, and forming by contacting a cooling roll having irregularities on its surface. The fine irregularities preferably have a ten-point average roughness of about 0.1 μm or more, more preferably about 0.2 μm or more, and also preferably about 35 μm or less, more preferably about 10 μm or less, with preferred ranges including about 0.1 to 35 μm, about 0.1 to 10 μm, about 0.2 to 35 μm, and about 0.2 to 10 μm. The ten-point average roughness is a value measured using a commercially available surface roughness measuring instrument in accordance with the provisions of JIS B0601:1994.

[0139] [Adhesive layer 2] In the packaging film for energy storage devices of the present disclosure, the adhesive layer 2 is a layer provided between the substrate layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0140] The adhesive layer 2 is formed by an adhesive capable of bonding the substrate layer 1 and the barrier layer 3. The adhesive used to form the adhesive layer 2 is not limited, but may be a chemical reaction type, solvent evaporation type, heat melt type, hot pressure type, etc. It may also be a two-component curing adhesive (two-part adhesive), a one-component curing adhesive (one-part adhesive), or a resin that does not undergo a curing reaction. Furthermore, the adhesive layer 2 may be a single layer or a multi-layer layer.

[0141] Examples of adhesive components include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used individually or in combination of two or more. Among these adhesive components, polyurethane adhesives are particularly preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected appropriately from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components.

[0142] Examples of polyurethane adhesives include polyurethane adhesives comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curing type polyurethane adhesive is used, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. As the second agent, aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds are used. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. The adhesive layer 2 is formed from a polyurethane adhesive, which provides excellent electrolyte resistance to the packaging film for energy storage devices, preventing the substrate layer 1 from peeling off even if electrolyte adheres to the sides.

[0143] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. The inclusion of a colorant in the adhesive layer 2 allows for the coloring of the packaging film for energy storage devices. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0144] The type of pigment is not particularly limited, as long as it does not impair the adhesion of the adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0145] Among colorants, carbon black is preferred for, for example, to give the appearance of packaging film for energy storage devices a black color. Furthermore, from the viewpoint of dissipating heat generated from energy storage devices, mica is preferred.

[0146] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0147] The content of the coloring agent in the adhesive layer 2 is not particularly limited as long as the packaging film for the energy storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0148] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the substrate layer 1 and the barrier layer 3, but for example, it is about 1 μm or more and about 2 μm or more. Alternatively, the thickness of the adhesive layer 2 is about 10 μm or less and about 5 μm or less. Preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0149] [Colored Layer] The colored layer is a layer provided between the base layer 1 and the barrier layer 3 as needed (not shown in the figure). If there is an adhesive layer 2, the colored layer may be provided between the base layer 1 and the adhesive layer 2, and between the adhesive layer 2 and the barrier layer 3. Alternatively, the colored layer may be provided on the outside of the base layer 1. By providing a colored layer, the packaging film for energy storage devices can be colored.

[0150] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer 1 or the surface of the barrier layer 3. Known coloring agents such as pigments and dyes can be used. In addition, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0151] Specific examples of colorants included in the colored layer are the same as those exemplified in the section for [Adhesive Layer 2].

[0152] [Barrier layer 3] In the packaging film for energy storage devices, the barrier layer 3 is a layer that at least prevents the intrusion of moisture. In the packaging film for energy storage devices of this disclosure, the barrier layer 3 is a layer that is provided as needed.

[0153] As described above, when the energy storage device packaging film 10 has a barrier layer 3, the energy storage device packaging film 10 can be suitably used as an outer packaging material for the energy storage device. On the other hand, as shown in Figure 1, when the energy storage device packaging film 10 does not have a barrier layer 3, the energy storage device packaging film 10 can be suitably used as an inner bag film placed between the outer packaging material of the energy storage device and the energy storage device element. An outer packaging material that packages the energy storage device element is essential for an energy storage device, but whether or not to further provide an inner bag film between the outer packaging material and the energy storage device element is selected according to the design of the energy storage device, etc.

[0154] Examples of barrier layer 3 include metal foil, vapor-deposited film, and resin layer with barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as barrier layer 3. Multiple layers of barrier layer 3 may be provided. It is preferable that barrier layer 3 includes a layer made of a metal material. Specific examples of metal materials constituting barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0155] In barrier layer 3, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. Barrier layer 3 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and purified from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) that is not recycled material.

[0156] From the viewpoint of improving the formability of the packaging film for energy storage devices, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is more preferably an aluminum alloy foil containing iron. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, a packaging film for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, a packaging film for energy storage devices with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments.

[0157] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing a packaging film for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0158] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0159] In the case of metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer that prevents moisture from penetrating, and can be, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 3 is also preferably about 10 μm or more, even more preferably about 20 μm or more, and even more preferably about 25 μm or more. The preferred range for the thickness of the barrier layer 3 is about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above range is particularly preferred. Furthermore, from the viewpoint of providing the packaging film 10 for energy storage devices with high moldability and high rigidity, the thickness of the barrier layer 3 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. Preferred ranges are approximately 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 55-200 μm, 55-85 μm, 55-75 μm, and 55-70 μm. The high moldability of the energy storage device packaging film 10 facilitates deep drawing and can contribute to increasing the capacity of the energy storage device. Furthermore, while the weight of the energy storage device increases with higher capacity, the increased rigidity of the energy storage device packaging film 10 contributes to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 3 is composed of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0160] Furthermore, if the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one. Furthermore, among these treatments, hot water modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. These processes may also be included in the definition of chemical conversion treatment. Furthermore, if the barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0161] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of packaging films for energy storage devices. It also prevents the dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolytes and moisture, particularly the dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil. Furthermore, it improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0162] Various corrosion-resistant coatings are known to be formed by chemical conversion treatments, mainly including corrosion-resistant coatings containing at least one of the following: phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl acetate chromate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphate. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. This coating-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., aluminum alloy foil) using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation. Then, a treatment solution mainly composed of metal phosphate salts such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, and zinc (Zn) phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphate salts and mixtures thereof, or a treatment solution consisting of a mixture of these with synthetic resins, etc., is applied to the degreased surface using a well-known coating method such as roll coating, gravure printing, or immersion, and then dried. The treatment solution can be various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Furthermore, examples of resin components used in this process include polymers such as phenolic resins and acrylic resins, and examples of chromate treatment using an amination phenol polymer having repeating units represented by the following general formulas (1) to (4). In this amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included individually or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, acrylate methacrylate copolymer, acrylate maleic acid copolymer, acrylate styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, or amine salts. Derivatives of polyacrylic acid, such as ammonium salts, sodium salts, or amine salts of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid means a polymer of acrylic acid. Furthermore, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride, and also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0163]

[0164]

[0165]

[0166]

[0167] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2 Examples of alkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. Also, X, R 1 and R 2Examples of hydroxyalkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxyl group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, and 4-hydroxybutyl group. In general formulas (1) to (4), X and R 1 and R 2 The alkyl group and hydroxyalkyl group shown may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a hydroxyalkyl group. The number-average molecular weight of the amination phenol polymer having repeating units represented by general formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The amination phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by the above general formula (1) or general formula (3), and then mixing formaldehyde and amine (R 1 R 2 Using NH) the functional group (-CH2NR 1 R 2 It is produced by introducing ) into the polymer obtained above. The amination phenol polymer can be used alone or in a mixture of two or more types.

[0168] Another example of a corrosion-resistant film is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant film can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0169] An example of a corrosion-resistant coating is one formed by dispersing metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or fine particles of barium sulfate, in phosphoric acid, applying this mixture to the surface of a barrier layer, and then baking it at a temperature of 150°C or higher.

[0170] The corrosion-resistant coating may, if necessary, be a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic and anionic polymers include those mentioned above.

[0171] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0172] The amount of corrosion-resistant film to be formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of coating-type chromate treatment, the surface of the barrier layer 3 is 1 m 2 It is desirable that the product contains, for example, about 0.5 to 50 mg of chromium-based chromium, preferably about 1.0 to 40 mg of phosphorus-based chromium, about 0.5 to 50 mg of phosphorus-based chromium, preferably about 1.0 to 40 mg of phosphorus, and about 1.0 to 200 mg of aminophenol polymer, preferably about 5.0 to 150 mg.

[0173] The thickness of the corrosion-resistant coating is not particularly limited, but from the viewpoint of the cohesive force of the coating and the adhesion force with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy-dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions consisting of Ce, P, and O (e.g., Ce2PO4) can be identified. + CePO4 - (At least one of the above) or, for example, a secondary ion consisting of Cr, P, and O (e.g., CrPO2) + , CrPO4 - A peak originating from at least one of the following is detected:

[0174] The chemical conversion treatment is carried out by applying a solution containing compounds used to form a corrosion-resistant film to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Alternatively, before applying the chemical conversion treatment to the barrier layer, it may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. This degreasing treatment makes it possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. Furthermore, by using an acid degreasing agent, which is a fluorine-containing compound dissolved in an inorganic acid, it is possible to not only degrease the metal foil but also form a fluoride of the passive metal; in such cases, only the degreasing treatment may be performed.

[0175] [Heat-sealable resin layer 4] In the packaging film for energy storage devices of this disclosure, the heat-sealable resin layer 4 is the innermost layer and is a layer (sealant layer) that performs the function of sealing the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device.

[0176] The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but polyolefins, resins containing a polyolefin backbone such as acid-modified polyolefins, and polyesters are preferred. The presence of a polyolefin backbone in the resin constituting the heat-fusible resin layer 4 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby, wave frequency 1780 cm -1 A peak derived from maleic anhydride is detected in the vicinity. If the heat-fusible resin layer 4 is composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0177] When the resin forming the heat-sealable resin layer of this disclosure contains polyester, it is preferable to use the polyester film described in the section on <Polyester Film>. Details of the polyester film are as described in the section on <Polyester Film>.

[0178] The heat-fusible resin layer 4 preferably contains a resin containing a polyolefin skeleton as its main component, more preferably contains polyolefin as its main component, and even more preferably contains polypropylene as its main component. Here, "main component" means a resin component in which the content of the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, if the heat-fusible resin layer 4 contains polypropylene as its main component, it means that the content of polypropylene in the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0179] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. These polyolefin resins may be used individually or in combination of two or more.

[0180] Furthermore, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0181] Furthermore, the polyolefin may be an acid-modified polyolefin. An acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefin, copolymers obtained by copolymerizing the above-mentioned polyolefin with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins can also be used. Examples of acid components used for acid modification include carboxylic acids or their anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0182] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin with an acid component, or by block polymerization or graft polymerization of an acid component to a cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

[0183] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0184] The heat-sealable resin layer 4 may be formed by a single resin, or by a blended polymer of two or more resins. Furthermore, the heat-sealable resin layer 4 may be formed as a single layer, or it may be formed as two or more layers of the same or different resins.

[0185] In the heat-sealable resin layer 4, the same polyester as exemplified in the [base layer 1] is used. When the packaging film 10 for energy storage devices of this disclosure is used as an outer material for all-solid-state batteries, and particularly high heat resistance is required for the heat-sealable resin layer 4, it is also preferable to use a polyester film for the heat-sealable resin layer 4.

[0186] When manufacturing the packaging film 10 for energy storage devices according to this disclosure by laminating the heat-fusible resin layer 4 with a barrier layer 3, an adhesive layer 5, etc., a pre-formed resin film may be used as the heat-fusible resin layer 4. Alternatively, the heat-fusible resin that forms the heat-fusible resin layer 4 may be formed into a film on the surface of the barrier layer 3, adhesive layer 5, etc. by extrusion molding or coating, etc., to form the heat-fusible resin layer 4 from a resin film.

[0187] Furthermore, the heat-sealable resin layer 4 may contain a lubricant or the like as needed. When the heat-sealable resin layer 4 contains a lubricant, the moldability of the packaging film for energy storage devices can be improved. The lubricant is not particularly limited, and known lubricants can be used.

[0188] If the heat-sealable resin layer 4 is too hard, it may slip at the contact points with the equipment when forming the roll material or the packaging film for energy storage devices into a package using the equipment, potentially preventing proper transport. Furthermore, if scratches occur on the packaging film for energy storage devices due to friction, the heat-sealable resin layer 4 may be damaged. Damage to the heat-sealable resin layer 4 can reduce the heat seal strength, so it is preferable that the heat-sealable resin layer 4 has a moderately slippery property. For this reason, when using a non-slippery or low-slippery material as the material constituting the heat-sealable resin layer 4, it is preferable to add a lubricant from the viewpoint of transportability.

[0189] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in the base layer 1. The lubricant may be used alone or in combination of two or more types, with a combination of two or more being preferable.

[0190] In this disclosure, from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the heat-fusible resin layer 4. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more types, with a combination of two or more being preferable.

[0191] When a lubricant is present on the surface of the heat-sealable resin layer 4, there are no particular restrictions on the amount present, but from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferably about 1 mg / m². 2 More preferably, about 3 mg / m² 2 More preferably, about 5 mg / m² 2 More preferably, about 10 mg / m² 2 More preferably, about 15 mg / m² 2 The above is true, and preferably about 50 mg / m² 2 More preferably, about 40 mg / m² 2 The following are preferred ranges, with a preferred range being 1 to 50 mg / m². 2 Degree, 1-40mg / m 2 Degree, 3-50mg / m 2 Degree, 3-40mg / m 2 degree, 5-50mg / m 2 degree, 5-40mg / m 2 degree, 10-50mg / m 2 degree, 10-40mg / m 2 degree, 15-50mg / m 2 degree, 15-40mg / m 2 The degree can be described as follows.

[0192] When a lubricant is present inside the heat-sealable resin layer 4, there are no particular restrictions on its amount. However, from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, even more preferably about 500 ppm or more, and also preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. When two or more types of lubricants are present inside the heat-sealable resin layer 4, the above amount of lubricant is the total amount of lubricant. Furthermore, when two or more types of lubricants are present inside the heat-fusible resin layer 4, the amount of the first type of lubricant is not particularly limited, but from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, even more preferably about 500 ppm or more, and also preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. The amount of the second lubricant is not particularly limited, but from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferably about 50 ppm or more, more preferably about 100 ppm or more, even more preferably about 200 ppm or more, and also preferably about 1500 ppm or less, more preferably about 1000 ppm or less. Preferred ranges include about 50 to 1500 ppm, about 50 to 1000 ppm, about 100 to 1500 ppm, about 100 to 1000 ppm, about 200 to 1500 ppm, and about 200 to 1000 ppm.

[0193] The lubricant present on the surface of the heat-fusible resin layer 4 may be a lubricant contained in the resin constituting the heat-fusible resin layer 4 that has seeped out, or a lubricant may be applied to the surface of the heat-fusible resin layer 4.

[0194] Furthermore, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device element, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described later is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0195] Furthermore, from the viewpoint of stain resistance and processability, it is preferable that the tensile modulus of the heat-fusible resin layer 4, as measured in accordance with the provisions of JIS K7161:2014, falls within the range of 500 MPa to 1000 MPa. More preferable ranges for the tensile modulus of the heat-fusible resin layer 4 include 500 MPa to 800 MPa, even more preferable ranges include 500 MPa to 750 MPa, even more preferable ranges include 500 MPa to 700 MPa, and even more preferable ranges include 510 MPa to 700 MPa.

[0196] The tensile modulus of the heat-fusible resin layer 4 is 500 MPa or higher, which effectively suppresses mold contamination during molding. Specifically, because the tensile modulus of the heat-fusible resin layer 4 is 500 MPa or higher, the lubricant located on the surface of the heat-fusible resin layer 4 is less likely to be scraped off by the mold, thus preventing the lubricant located on the surface of the heat-fusible resin layer 4 from transferring to the mold, and effectively suppressing mold contamination. Furthermore, because the tensile modulus of the heat-fusible resin layer 4 is 1000 MPa or lower, high sealing strength is achieved through heat fusion. Specifically, because the tensile modulus of the heat-fusible resin layer 4 is 1000 MPa or lower, the heat-fusible resin layer 4 is less likely to become brittle, resulting in high sealing strength through heat fusion. If the tensile modulus of the heat-fusible resin layer 4 exceeds 1000 MPa, the heat-fusible resin layer 4 tends to become brittle, making it prone to delamination from the barrier layer 3 laminated via the adhesive layer 5, resulting in reduced seal strength. Furthermore, stretching during the cold forming process may cause whitening or cracking in the stretched portion, potentially degrading battery performance. Additionally, if the tensile modulus of the heat-fusible resin layer 4 exceeds 1000 MPa, extrudeability decreases, leading to reduced productivity. Therefore, in packaging films for energy storage devices, setting the tensile modulus of the heat-fusible resin layer 4 within the range of 500 to 1000 MPa allows for optimal suppression of mold contamination and improvement of seal strength through heat fusion. The tensile modulus of the heat-fusible resin layer 4 can be adjusted by adjusting the molecular weight, melt mass flow rate (MFR), and other factors of the resin constituting the heat-fusible resin layer 4.

[0197] Furthermore, when processing is referred to as the process of joining sealing portions together and folding them during the manufacturing of outer packaging film for energy storage devices, the same problems as described above are likely to occur during this processing. In particular, the outer packaging film for energy storage devices is prone to damage during processing. By setting the tensile modulus of the outer packaging film for energy storage devices to a range of 500 MPa to 1000 MPa, processing can be performed smoothly.

[0198] [Adhesive layer 5] In the packaging film for energy storage devices of the present disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or corrosion-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0199] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. As the resin used to form the adhesive layer 5, for example, the same type of adhesive as exemplified in the adhesive layer 2 can be used.

[0200] Furthermore, from the viewpoint of firmly bonding the adhesive layer 5 and the heat-fusible resin layer 4, it is preferable that the resin used to form the adhesive layer 5 contains a polyolefin skeleton, and examples include the polyolefins, acid-modified polyolefins, cyclic polyolefins, and acid-modified cyclic polyolefins exemplified in the heat-fusible resin layer 4 mentioned above. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid, but maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the viewpoint of heat resistance of the packaging film for energy storage devices, it is preferable that the olefin component be a polypropylene-based resin, and it is most preferable that the adhesive layer 5 contains maleic anhydride-modified polypropylene.

[0201] When the resin used to form the adhesive layer 5 contains a polyolefin skeleton, the adhesive layer 5 preferably contains a resin containing a polyolefin skeleton as its main component, more preferably contains acid-modified polyolefin as its main component, and even more preferably contains acid-modified polypropylene as its main component. Here, "main component" means a resin component whose content in the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the adhesive layer 5 contains acid-modified polypropylene as its main component, it means that the content of acid-modified polypropylene in the resin component of the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0202] The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be analyzed by methods such as infrared spectroscopy and gas chromatography-mass spectrometry, and the analytical method is not particularly limited. Furthermore, the presence of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be analyzed by measuring maleic anhydride-modified polyolefin using infrared spectroscopy, for example, at a wavenumber of 1760 cm⁻¹. -1 Nearby, wave frequency 1780 cm -1 A peak originating from maleic anhydride is detected in the vicinity. However, if the degree of acid denaturation is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0203] Furthermore, from the viewpoint of ensuring durability such as heat resistance and content resistance of the packaging film for energy storage devices, as well as moldability while keeping the thickness thin, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Examples of acid-modified polyolefins include those mentioned above.

[0204] Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, ester resins produced by the reaction of epoxy groups and maleic anhydride groups, and amide ester resins produced by the reaction of oxazoline groups and maleic anhydride groups are preferred. If unreacted curing agents such as compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins remain in the adhesive layer 5, the presence of unreacted substances can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0205] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocycles, C=N bonds, and C-O-C bonds. Examples of curing agents having heterocycles include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having C-O-C bonds include curing agents having oxazoline groups and curing agents having epoxy groups. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0206] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, biuretes, and isocyanurates are also examples.

[0207] The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0208] Compounds containing an oxazoline group are not particularly limited as long as they have an oxazoline skeleton. Specific examples of compounds containing an oxazoline group include those with a polystyrene main chain and those with an acrylic main chain. Commercially available examples include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0209] The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0210] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and even more preferably about 200 to 800. In this disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0211] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0212] The proportion of epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0213] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component polyurethane.

[0214] The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere where components that induce corrosion of the barrier layer, such as electrolytes, are present.

[0215] Furthermore, if the adhesive layer 5 is a cured product of a resin composition containing at least one compound selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0216] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0217] When manufacturing the packaging film 10 for energy storage devices according to this disclosure by laminating the adhesive layer 5 with a barrier layer 3, a heat-fusible resin layer 4, etc., a pre-formed resin film may be used as the adhesive layer 5. Alternatively, the heat-fusible resin that forms the adhesive layer 5 may be formed into a film on the surface of the barrier layer 3, the heat-fusible resin layer 4, etc. by extrusion molding or coating, and the adhesive layer 5 may be formed from a resin film.

[0218] The thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less. Alternatively, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more, or about 0.5 μm or more. The range of the thickness of the adhesive layer 5 is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2, or a cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified in the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating. Also, when using the resin exemplified in the heat-fusible resin layer 4, it can be formed, for example, by extrusion molding of the heat-fusible resin layer 4 and the adhesive layer 5.

[0219] [Surface coating layer 6] The packaging film for energy storage devices of the present disclosure may optionally include a surface coating layer 6 on the base layer 1 (on the side opposite to the barrier layer 3 of the base layer 1) for the purpose of improving at least one of the following: design, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the packaging film for energy storage devices when the energy storage device is assembled using the packaging film for energy storage devices.

[0220] The surface coating layer 6 may be made of resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, or phenolic resin, or modified versions of these resins. It may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins. The resin is preferably a curable resin. That is, the surface coating layer 6 is preferably composed of a cured product of a resin composition containing a curable resin.

[0221] If the resin forming the surface coating layer 6 is a curable resin, it may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0222] Examples of two-component curable polyurethanes include polyurethanes comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are provided, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and a polyol compound. Examples of polyurethanes include polyurethanes obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. Furthermore, aliphatic isocyanate compounds refer to isocyanates that have an aliphatic group and no aromatic ring, alicyclic isocyanate compounds refer to isocyanates that have an alicyclic hydrocarbon group, and aromatic isocyanate compounds refer to isocyanates that have an aromatic ring.The surface coating layer 6 is formed of polyurethane, which provides the packaging film for energy storage devices with excellent electrolyte resistance.

[0223] The surface coating layer 6 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, and pigments in at least one of its surface and interior, depending on the functionality to be provided to the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0224] The additive may be either inorganic or organic. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0225] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used individually or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. Mica is also preferred from the viewpoint of heat dissipation from the energy storage device. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0226] The method for forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin to form the surface coating layer 6 can be used. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0227] In this disclosure, from the viewpoint of improving the moldability of the packaging film for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the surface coating layer 6. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more types, with a combination of two or more being preferable.

[0228] If a lubricant is present on the surface of the surface coating layer 6, there are no particular limitations on its amount, but for example, it may be about 3 mg / m². 2 Preferably about 4 mg / m² 2 Above, about 5mg / m 2 The above points are given. Furthermore, the amount of lubricant present on the surface of the surface coating layer 6 is, for example, about 15 mg / m². 2 Preferably about 14 mg / m² 2 Below, about 10mg / m 2 The following are examples. Furthermore, a preferred range for the amount of lubricant present on the surface of the surface coating layer 6 is 3 to 15 mg / m². 2 Degree, 3-14mg / m 2 Degree, 3-10mg / m 2 Degree, 4-15mg / m 2 Degree, 4-14mg / m 2 degree, 4-10mg / m 2 degree, 5-15mg / m 2 Degree, 5-14mg / m 2 degree, 5-10mg / m 2 The degree can be described as follows.

[0229] The lubricant present on the surface of the surface coating layer 6 may be a lubricant contained in the resin constituting the surface coating layer 6 that has seeped out, or a lubricant applied to the surface of the surface coating layer 6.

[0230] The surface coating layer 6 contains a coloring agent, which allows the packaging film for energy storage devices to be colored. Known coloring agents such as pigments and dyes can be used. Furthermore, only one type of coloring agent may be used, or two or more types may be mixed.

[0231] The types of pigments are not particularly limited. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0232] Among colorants, carbon black is preferred for, for example, to give the appearance of packaging film for energy storage devices a black color. Furthermore, from the viewpoint of dissipating heat generated from energy storage devices, mica is preferred.

[0233] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0234] The content of the coloring agent in the surface coating layer 6 is not particularly limited as long as the packaging film for the energy storage device is colored, and for example, it can be about 5 to 60% by mass, preferably about 10 to 40% by mass.

[0235] The thickness of the surface coating layer 6 is not particularly limited as long as it performs the above-mentioned functions as a surface coating layer 6, and for example, it can be about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0236] [Method for manufacturing packaging film for energy storage devices] The method for manufacturing packaging film for energy storage devices is not particularly limited as long as a laminate is obtained by laminating each layer of the outer material for energy storage devices of this disclosure, and at a minimum, a method comprising the step of laminating a base layer 1 and a heat-sealable resin layer 4 is provided.

[0237] An example of a method for manufacturing the packaging film for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated laminate A") is formed by sequentially laminating a base layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form the adhesive layer 2 is applied to the base layer 1 or, if necessary, a barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured.

[0238] Next, a heat-fusible resin layer 4 is laminated onto the barrier layer 3 of the laminate A. When the heat-fusible resin layer 4 is directly laminated onto the barrier layer 3, the heat-fusible resin layer 4 can be laminated onto the barrier layer 3 of the laminate A by methods such as thermal lamination or extrusion lamination. Also, when an adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 and the heat-fusible resin layer 4 can be laminated by methods such as (1) extrusion lamination, (2) thermal lamination, (3) sandwich lamination, or (4) dry lamination. (1) An example of an extrusion lamination method is a method in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated onto the barrier layer 3 of the laminate A by extrusion (co-extrusion lamination method, tandem lamination method). Furthermore, (2) as a thermal lamination method, for example, a laminate is formed by separately laminating an adhesive layer 5 and a heat-fusible resin layer 4, and this is laminated onto the barrier layer 3 of the laminate A, or a laminate is formed by laminating an adhesive layer 5 on the barrier layer 3 of the laminate A, and this is laminated with the heat-fusible resin layer 4. Furthermore, (3) as a sandwich lamination method, for example, a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-fusible resin layer 4 that has been previously made into a sheet, thereby bonding the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5. Furthermore, (4) as a dry lamination method, for example, an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A and dried, or further laminated by baking, and a heat-fusible resin layer 4 that has been previously made into a sheet is laminated onto this adhesive layer 5.

[0239] When a surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the resin used to form the surface coating layer 6 to the surface of the base layer 1. The order of the steps of laminating the barrier layer 3 to the surface of the base layer 1 and laminating the surface coating layer 6 to the surface of the base layer 1 is not particularly limited. For example, the surface coating layer 6 may be formed on the surface of the base layer 1, and then the barrier layer 3 may be formed on the surface of the base layer 1 opposite to the surface coating layer 6.

[0240] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0241] In packaging films for energy storage devices, the processability of each layer constituting the laminate may be improved by subjecting it to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as needed. For example, by applying corona treatment to the surface of the substrate layer 1 opposite to the barrier layer 3, the printability of ink on the surface of the substrate layer 1 can be improved.

[0242] [Applications of Packaging Film for Energy Storage Devices] As described above, the packaging film 10 for energy storage devices of this disclosure can be suitably used as an outer packaging material for energy storage devices. Furthermore, the packaging film 10 for energy storage devices of this disclosure can also be suitably used as an inner bag film disposed between the outer packaging material and the energy storage device element of the energy storage device. In an energy storage device that includes an inner bag film between the outer packaging material and the energy storage device element, for example, a metal can can be used as the outer packaging material. On the other hand, as described above, an outer packaging material having a laminated structure consisting of a laminate having at least a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order is also suitable as an outer packaging material that can achieve thinning and weight reduction.

[0243] The outer casing material for energy storage devices is used in packaging for sealing and housing energy storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, the packaging film for energy storage devices of this disclosure can be used as the outer casing material, and energy storage device elements comprising at least a positive electrode, a negative electrode, and an electrolyte can be housed in the packaging formed by the outer casing material to form an energy storage device.

[0244] Specifically, an energy storage device is provided using the energy storage device packaging film, which covers an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte with the energy storage device packaging film of this disclosure, such that a flange portion (an area where heat-sealable resin layers come into contact) is formed around the periphery of the energy storage device element, with the metal terminals connected to the positive electrode and negative electrode respectively protruding outward, and then heat-seals the heat-sealable resin layers of the flange portion to seal it. When housing an energy storage device element in a package formed from the energy storage device packaging film of this disclosure, the package is formed such that the heat-sealable resin portion of the energy storage device packaging film of this disclosure faces inward (the surface in contact with the energy storage device element). The packaging body may be formed by overlapping the heat-sealable resin layers of two energy storage device packaging films facing each other and heat-sealing the periphery of the overlapped energy storage device packaging films. Alternatively, as shown in the example in Figure 6, one energy storage device packaging film may be folded and overlapped, and the periphery may be heat-sealed to form the packaging body. When folding and overlapping, as shown in the example in Figure 6, the edges other than the folded edge may be heat-sealed to form a three-sided seal, or the edges may be folded to form a flange and then sealed on all four sides. Alternatively, the energy storage device packaging film may be wrapped around the energy storage device element, the heat-sealable resin layers may be sealed together to form a heat-sealed portion, and a lid or the like may be placed to close the openings at both ends, and then heat-sealed to the energy storage device packaging film wrapped around the energy storage device element to seal it. The lid can be formed from, for example, a resin molded product, a metal molded product, or an energy storage device packaging film. Furthermore, recesses for housing energy storage device elements may be formed in the packaging film for the energy storage device by deep drawing or stretch molding. As shown in the example in Figure 6, one packaging film for the energy storage device may have recesses while the other packaging film does not, or recesses may be provided in the other packaging film as well.

[0245] The energy storage device packaging film of this disclosure can be suitably used for energy storage devices such as batteries (including capacitors, condensers, etc.). Furthermore, the energy storage device packaging film of this disclosure may be used for either primary or secondary batteries, but is preferably used for secondary batteries. The types of secondary batteries to which the energy storage device packaging film of this disclosure can be applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, pseudo-solid-state batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the energy storage device packaging film of this disclosure.

[0246] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0247] [Preparation of Polyester Film A] Pellets (intrinsic viscosity: 0.61 dL / g) made of polyethylene terephthalate were prepared using ethylene glycol derived from carbon monoxide gas as the diol unit and terephthalic acid derived from fossil fuels as the dicarboxylic acid unit. After drying the pellets, they were supplied to an extruder, melted at 260°C, extruded into a sheet from a T-die, and cooled and solidified with a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was held at 88°C for 1 minute, and then simultaneously stretched in the longitudinal and transverse directions at a speed of 100 mm / min with an area ratio of 3.6 times. In this way, polyester film A with a thickness of 12 μm was obtained.

[0248] [Preparation of Polyester Film B] Pellets (intrinsic viscosity: 0.61 dL / g) made of polyethylene terephthalate were prepared using ethylene glycol derived from fossil fuels as the diol unit and terephthalic acid derived from fossil fuels as the dicarboxylic acid unit. After drying the pellets, they were supplied to an extruder, melted at 260°C, extruded into a sheet from a T-die, and cooled and solidified with a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was held at 88°C for 1 minute, and then simultaneously stretched in the longitudinal and transverse directions at a speed of 100 mm / min with an area ratio of 3.6 times. In this way, polyester film B with a thickness of 12 μm was obtained.

[0249] <Manufacturing of Packaging Film for Energy Storage Devices> (Example 1) As a base layer, a laminate was prepared by bonding the above-mentioned polyester film A (polyethylene terephthalate (PET)) film (thickness 12 μm) and stretched nylon (ONy) film (thickness 15 μm) with an adhesive layer (formed with a polyester-based two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, aluminum foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared as a barrier layer. Both sides of the aluminum foil were treated with chemical conversion treatment. The chemical conversion treatment of the aluminum foil was performed using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 The coating was applied to both sides of the aluminum foil using the roll-coating method and then baked to achieve the (dry mass) shown.

[0250] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0251] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 μm thick), were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Next, the obtained laminate was aged and heated to obtain a packaging film for energy storage devices (exterior material for energy storage devices) consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in this order.

[0252] (Example 2) A laminate was prepared by bonding the polyester film A (polyethylene terephthalate (PET)) film (thickness 12 μm) and the polyester film B (polyethylene terephthalate (PET)) film (thickness 12 μm) with an adhesive layer (formed with a polyester-based two-component curing urethane adhesive, with a thickness of 3 μm after curing), and this laminate was used as the base layer. In the same manner as in Example 1, a packaging film for energy storage devices (exterior material for energy storage devices) was obtained, consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order.

[0253] (Comparative Example 1) Except that polyester film B was used instead of polyester film A in the base layer, a packaging film for energy storage devices (exterior material for energy storage devices) was obtained in the same manner as in Example 1, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order.

[0254] (Comparative Example 2) A laminate was prepared by bonding the above-mentioned polyester film B (polyethylene terephthalate (PET)) film (thickness 12 μm) with an adhesive layer (formed with a polyester-based two-component curing urethane adhesive, with a thickness of 3 μm after curing), and this laminate was used as the base layer. In the same manner as in Example 1, a packaging film for energy storage devices (exterior material for energy storage devices) was obtained, consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order.

[0255] <Measurement of Laminate Strength> From the packaging films for energy storage devices obtained in Example 1 and Comparative Example 1, strips with a width of 15 mm and a length of 150 mm in the TD direction were cut out. Next, at the end of the sample in the MD direction, approximately 10 mm was peeled off between the base layer and the barrier layer in the MD direction, and tape was applied to the base layer and barrier layer to extend the gripping area between the base layer and the barrier layer. The tapes attached to the base layer and barrier layer were gripped by the chuck of a tensile testing machine (Shimadzu Corporation, AG-Xplus (product name)), and these were used as measurement samples. The laminate strength (peel strength) between the base layer and the barrier layer of the obtained measurement samples was measured on a tensile testing machine at 25°C and a 50% RH atmosphere under the conditions of 180-degree peeling, a tensile speed of 50 mm / min, and a gauge-to-gauge distance of 50 mm. The strength when the gauge-to-gauge distance reached 57 mm was defined as the laminate strength. The average of three measurements was used. Note that in the preparation of the measurement sample, in the area where the substrate layer and barrier layer were separated, the adhesive layer may be present on the surface of the substrate layer, on the surface of the barrier layer, or on both the substrate layer and the barrier layer.

[0256] The lamination strength of the packaging films for energy storage devices obtained in Example 1 and Comparative Example 1 was 9.4 N / 15 mm, respectively, indicating equivalent lamination strength. Furthermore, the lamination strength of the packaging film for energy storage devices obtained in Example 2 was 9.2 N / 15 mm, and the lamination strength of the packaging film for energy storage devices obtained in Comparative Example 2 was 9.3 N / 15 mm, indicating equivalent lamination strength.

[0257] <Measurement of Tensile Breaking Characteristics> In accordance with the provisions of JIS K7127:1999, the tensile breaking strength and tensile breaking elongation in the MD direction and TD direction were measured for the packaging films for energy storage devices obtained in Example 1 and Comparative Example 1, respectively. A tensile testing machine (Shimadzu Corporation, AG-Xplus (product name)) was used for the measurements. The measurement conditions were as follows: a rectangular sample with a sample width of 15 mm and a sample length of 150 mm was prepared, with a sample for tensile testing in the MD direction (15 mm width in the TD direction, 150 mm length in the MD direction) and a sample for tensile testing in the TD direction (15 mm width in the MD direction, 150 mm length in the TD direction). The gauge length was set to 50 mm, the tensile speed to 100 mm / min, and the test environment to 23°C. The average value of three measurements was used.

[0258] The tensile breaking strength of the energy storage device packaging film obtained in Example 1 was 107 N / 15 mm in the MD direction and 106 N / 15 mm in the TD direction, while the tensile breaking strength of the energy storage device packaging film obtained in Comparative Example 1 was 109 N / 15 mm in the MD direction and 106 N / 15 mm in the TD direction, indicating that Example 1 and Comparative Example 1 had equivalent tensile breaking strengths. Furthermore, the tensile elongation at break of the energy storage device packaging film obtained in Example 1 was 17.0% in the MD direction and 16.5% in the TD direction, while the tensile elongation at break of the energy storage device packaging film obtained in Comparative Example 1 was 16.2% in the MD direction and 17.8% in the TD direction, indicating that Example 1 and Comparative Example 1 had equivalent tensile elongation at breaks.

[0259] Furthermore, the tensile breaking strength of the energy storage device packaging film obtained in Example 2 was 123 N / 15 mm in the MD direction and 154 N / 15 mm in the TD direction, while the tensile breaking strength of the energy storage device packaging film obtained in Comparative Example 2 was 120 N / 15 mm in the MD direction and 155 N / 15 mm in the TD direction, indicating that Example 2 and Comparative Example 2 had equivalent tensile breaking strengths. Additionally, the tensile elongation at break of the energy storage device packaging film obtained in Example 2 was 33.9% in the MD direction and 50.6% in the TD direction, while the tensile elongation at break of the energy storage device packaging film obtained in Comparative Example 2 was 35.2% in the MD direction and 50.5% in the TD direction, indicating that Example 2 and Comparative Example 2 had equivalent tensile elongation at breaks.

[0260] <Ten-point average roughness of the outermost layer surface of the packaging film for energy storage devices> The ten-point average roughness of the surface of the base layer (surface of polyester film A and B) of each packaging film for energy storage devices obtained in Example 1 and Comparative Example 1 was measured according to the method specified in JIS B0601:1994. A Mitutoyo SURFTEST SJ-210 compact surface roughness measuring instrument was used for the measurement, with a measurement speed of 0.5 mm and a range of AUTO. As a result, the ten-point average roughness was 0.69 μm for Example 1 and 0.72 μm for Comparative Example 1.

[0261] As described above, this disclosure provides inventions in the following embodiments: Item 1. A packaging film for an energy storage device comprising at least a laminate comprising a base layer and a heat-sealable resin layer, wherein the laminate includes a polyester film, the polyester film includes a polyester comprising diol units and dicarboxylic acid units, and the diol units include ethylene glycol derived from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. Item 2. The packaging film for an energy storage device according to Item 1, wherein the dicarboxylic acid units include at least one selected from the group consisting of terephthalic acid derived from fossil fuels, terephthalic acid derived from biomass, and terephthalic acid derived from carbon dioxide gas. Item 3. The packaging film for an energy storage device according to Item 1 or 2, wherein the base layer includes the polyester film. Item 4. The packaging film for an energy storage device according to any one of Items 1 to 3, wherein the heat-sealable resin layer includes the polyester film. Item 5. A packaging film for energy storage devices according to any one of claims 1 to 4, further comprising a barrier layer between the base material layer and the heat-sealable resin layer. Claim 6. A packaging film for energy storage devices according to claim 5, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. Claim 7. A packaging film for energy storage devices according to claim 5 or 6, further comprising an adhesive layer between the base material layer and the barrier layer. Claim 8. A packaging film for energy storage devices according to any one of claims 5 to 7, used as an outer material for energy storage devices. Claim 9. A packaging film for energy storage devices according to any one of claims 1 to 8, used as an inner bag film for energy storage devices, disposed between the outer material of the energy storage device and the elements of the energy storage device. Claim 10. A method for producing a packaging film for an energy storage device, comprising at least the step of obtaining a laminate in which a base layer and a heat-fusible resin layer are laminated, wherein the laminate includes a polyester film, the polyester film includes a polyester containing diol units and dicarboxylic acid units, and the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.Item 11. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an energy storage device packaging film according to any one of items 1 to 9.

[0262] 1. Base layer 2. Adhesive layer 3. Barrier layer 4. Heat-sealable resin layer 5. Adhesive layer 6. Surface coating layer 10. Packaging film for energy storage devices

Claims

1. A packaging film for energy storage devices, comprising at least a laminate comprising a base layer and a heat-sealable resin layer, wherein the laminate includes a polyester film, the polyester film includes a polyester comprising diol units and dicarboxylic acid units, and the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

2. The packaging film for energy storage devices according to claim 1, wherein the dicarboxylic acid unit comprises at least one selected from the group consisting of terephthalic acid derived from fossil fuels, terephthalic acid derived from biomass, and terephthalic acid produced from carbon dioxide gas.

3. The packaging film for energy storage devices according to claim 1 or 2, wherein the base layer includes the polyester film.

4. The packaging film for an energy storage device according to claim 1 or 2, further comprising a barrier layer between the base material layer and the heat-sealable resin layer.

5. The packaging film for an energy storage device according to claim 4, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer.

6. The packaging film for an energy storage device according to claim 4, further comprising an adhesive layer between the base material layer and the barrier layer.

7. Packaging film for energy storage devices according to claim 4, used as an outer casing material for energy storage devices.

8. The packaging film for an energy storage device according to claim 1 or 2, which is used as an inner bag film for an energy storage device, to be placed between the outer material of the energy storage device and the elements of the energy storage device.

9. A method for producing a packaging film for an energy storage device, comprising at least the step of obtaining a laminate comprising a base layer and a heat-fusible resin layer, wherein the laminate comprises a polyester film, the polyester film comprises a polyester comprising diol units and dicarboxylic acid units, and the diol units comprise ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

10. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the energy storage device packaging film described in claim 1 or 2.

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