Resin film for energy storage devices and energy storage devices

Abstract

A resin film for energy storage devices, The resin film for the energy storage device includes at least a resin layer A, The resin layer A is a resin film for energy storage devices in which, in a DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, with the height of the melting peak with the maximum peak height being defined as 1.0.

Description

[Technical Field]

[0001] This disclosure relates to a resin film for energy storage devices and an energy storage device. [Background technology]

[0002] While various types of energy storage devices have been developed, casing materials are essential components for sealing the device elements, such as electrodes and electrolytes, in all of them. Traditionally, metal casing materials have been widely used 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, conventionally, a film-like laminate in which a base layer / barrier layer / adhesive layer / heat-fusible resin layer is 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. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-287971 [Overview of the project] [Problems that the invention aims to solve]

[0007] If a malfunction occurs in the energy storage device, the gas generated inside the device will be released to the outside as the internal pressure of the device rises, causing the sealing portion of the outer casing (for example, the portion where the aforementioned heat-sealable resin layer is heat-sealed) to open.

[0008] In energy storage devices, the sealing area of ​​the outer casing is large, making it difficult to predict in advance where gases generated inside the energy storage device will be discharged.

[0009] Therefore, the inventors of this disclosure have worked to develop a technology for an energy storage device having a structure in which an energy storage device element is sealed by an outer casing, in which a resin film for the energy storage device is placed so that the energy storage device can be opened appropriately at the location of the resin film for the energy storage device when the internal temperature or internal pressure of the energy storage device rises.

[0010] In a technology for properly opening an energy storage device at the location of the resin film for the energy storage device, it is desirable that even when the temperature of the energy storage device rises, the resin film for the energy storage device exhibits high sealing strength and maintains high airtightness until the temperature reaches a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the sealing strength of the resin film for the energy storage device rapidly decreases, so that the energy storage device opens quickly at the location of the resin film for the energy storage device.

[0011] The primary objective of this disclosure is to provide a resin film for energy storage devices that is applied to an energy storage device having a structure in which energy storage device elements are sealed by an outer casing, wherein even if the internal temperature of the energy storage device rises, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the energy storage device is opened at the location of the resin film for energy storage devices. Furthermore, the primary objective of this disclosure is to provide an energy storage device including the resin film for energy storage devices. [Means for solving the problem]

[0012] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that a resin film for energy storage devices, which is applied to an energy storage device having a structure in which an energy storage device element is sealed by an outer casing, includes at least a resin layer A, and that in a DSC curve obtained by differential scanning calorimetry, when the height of the melting peak with the maximum peak height is set to 1.0, the full width at half maximum of the melting peak with a peak height of 0.3 or more is below a predetermined temperature (°C), then even if the internal temperature of the energy storage device rises, the energy storage device element is sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the energy storage device is opened at the position of the resin film for energy storage devices.

[0013] Furthermore, the inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that even when the kurtosis value of the melting peak of the DSC curve obtained by differential scanning calorimetry of a resin film for energy storage devices applied to an energy storage device having a structure in which the energy storage device elements are sealed by an outer casing is above a predetermined value, when the internal temperature of the energy storage device rises, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the temperature exceeds the predetermined temperature, the energy storage device is opened at the position of the resin film.

[0014] This disclosure was completed after further consideration based on these findings.

[0015] In other words, the first aspect of this disclosure provides the invention in the following aspects. A resin film for energy storage devices, The resin film for the energy storage device includes at least a resin layer A, The resin layer A is a resin film for energy storage devices in which, in a DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, with the height of the melting peak with the maximum peak height being defined as 1.0.

[0016] Moreover, the second aspect of the present disclosure provides an invention according to the aspects described below. A resin film for a power storage device, wherein the resin film for a power storage device has a kurtosis value of the melting peak of the DSC curve obtained by differential scanning calorimetry of 1.5 or more.

Advantages of the Invention

[0017] According to the present disclosure, there is provided a resin film applicable to a power storage device having a structure in which a power storage device element is sealed by an exterior body, and even when the internal temperature of the power storage device rises, up to a predetermined temperature of 60°C or higher, the power storage device element is sealed by the exterior body, and when the predetermined temperature is exceeded, the power storage device is opened at the position of the resin film. Further, according to the present disclosure, there can be provided a power storage device using the resin film and a method for manufacturing the same.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing an example of the cross-sectional structure of the resin film for a power storage device of the present disclosure. [Figure 2] It is a schematic diagram showing an example of the cross-sectional structure of the resin film for a power storage device of the present disclosure. [Figure 3] It is a schematic diagram showing an example of the cross-sectional structure of the resin film for a power storage device of the present disclosure. [Figure 4] It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 5] It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 6] It is a schematic plan view showing an example of the power storage device of the present disclosure. [Figure 7] It is a schematic diagram showing an example of the cross-sectional structure at line A-A' in FIG. 6. [Figure 8] It is a schematic plan view showing an example of the power storage device of the present disclosure. [Figure 9] This is a schematic diagram showing an example of a cross-sectional structure along line A-A' in Figure 8. [Figure 10] This is a schematic perspective view showing an example of the energy storage device of this disclosure. [Figure 11] This is a schematic diagram showing an example of a cross-sectional structure along line A-A' in Figure 10. [Figure 12] This is a schematic cross-sectional view showing an example of the energy storage device of this disclosure. [Figure 13] This is a schematic cross-sectional view showing an example of the energy storage device of this disclosure. [Modes for carrying out the invention]

[0019] A resin film for an energy storage device according to a first aspect of this disclosure includes at least a resin layer A, wherein the resin layer A is characterized in that, in a DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, when the height of the melting peak with the maximum peak height is set to 1.0. With this configuration, even if the internal temperature of the energy storage device rises, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the energy storage device is opened at the location of the resin film for the energy storage device.

[0020] Furthermore, the resin film for energy storage devices according to the second aspect of this disclosure is characterized in that the kurtosis value of the melting peak of the DSC curve obtained by differential scanning calorimetry is 1.5 or more. With the configuration of the resin film for energy storage devices according to the second aspect, even if the internal temperature of the energy storage device rises, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the energy storage device is opened at the position of the resin film for energy storage devices.

[0021] The resin film for energy storage devices of this disclosure will be described in detail below. In this disclosure, the resin film for energy storage devices according to the first embodiment and the resin film for energy storage devices according to the second embodiment are collectively referred to as the resin film for energy storage devices of this disclosure.

[0022] In this disclosure, the numerical range indicated by "~" means "greater than or equal to" and "less than or equal to". For example, the notation 2~15mm means 2mm or more and 15mm 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 and lower limits described separately may be combined to form a numerical range. 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.

[0023] [Resin film for energy storage devices] As shown in Figures 1 to 3, the resin film 1 for energy storage devices according to the first embodiment includes at least a resin layer A. In the DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, when the height of the melting peak with the maximum peak height is set to 1.0. In other words, in the resin film 1 of this disclosure, the full width at half maximum of a predetermined melting peak height of resin layer A is very narrow, at 25°C or less, so it softens rapidly near the melting peak temperature. For this reason, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and once the predetermined temperature is exceeded, the energy storage device can be opened at the location of the resin film for energy storage devices.

[0024] On the other hand, the resin film 1 for energy storage devices according to the second embodiment does not need to include the resin layer A with a predetermined half-width of 25°C or less, and it is sufficient that the kurtosis value of the melting peak of the DSC curve obtained by differential scanning calorimetry is 1.5 or more. The resin film 1 for energy storage devices according to the second embodiment may consist only of the resin layer B (with a predetermined half-width exceeding 25°C) described later. It is also preferable that the resin film 1 for energy storage devices according to the second embodiment includes the resin layer A with a predetermined half-width of 25°C or less, but in this case, the second embodiment becomes the first embodiment.

[0025] The predetermined temperature at which the resin film 1 for energy storage devices of this disclosure (hereinafter sometimes abbreviated as "resin film 1") opens the energy storage device is 60°C or higher, and can be set appropriately according to the required performance of the energy storage device. The predetermined temperature can be, for example, about 80°C or higher, preferably about 90°C or higher, more preferably about 100°C or higher, and also, for example, about 160°C or lower, preferably about 140°C or lower, more preferably about 135°C or lower. Preferred ranges include about 60-160°C, about 60-140°C, about 60-135°C, about 80-160°C, about 80-140°C, about 80-135°C, about 90-160°C, about 90-140°C, about 90-135°C, about 100-160°C, about 100-140°C, and about 100-135°C.

[0026] (Resin layer A) In the resin film 1 of this disclosure, resin layer A is a resin layer in which, in the DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, when the height of the melting peak with the maximum peak height is set to 1.0. A resin layer whose full width at half maximum exceeds 25°C is not resin layer A, but is referred to as resin layer B in this disclosure.

[0027] From the viewpoint of more favorably exhibiting the effects of the present invention, the half-width of the resin layer A is preferably about 25°C or lower, more preferably about 20°C or lower, and even more preferably about 15°C or lower. The lower limit is, for example, about 1°C or higher, about 5°C or higher, about 10°C or higher, and preferred ranges include about 1 to 25°C, about 1 to 20°C, about 1 to 15°C, about 5 to 25°C, about 5 to 20°C, about 5 to 15°C, about 10 to 25°C, about 10 to 20°C, and about 10 to 15°C. The method for measuring the half-width is as follows.

[0028] <Measurement of the full width at half maximum (°C) of the melting peak by differential scanning calorimetry> The following procedure is used to obtain resin layer A from the resin film, acquire a DSC curve for resin layer A by differential scanning calorimetry, and measure the full width at half maximum (°C) of melting peaks with a peak height of 0.3 or higher, with the peak height of the melting peak being set to 1.0. Specifically, the differential scanning calorimetry (DSC) curve is acquired using a differential scanning calorimetry device with a sample weight of approximately 5 mg under a nitrogen atmosphere. The resin is heated from 0°C to 210°C at a heating rate of 10°C / min, and in the DSC curve obtained from the first heating, the line connecting the 40°C point and the 200°C point on the DSC curve is used as the baseline. A line is drawn parallel to the baseline and passing through half the height of the maximum height of the DSC curve. From this line, the line segment contained in the region enclosed by the DSC curve and the baseline is extracted, and the temperatures of the high-temperature and low-temperature endpoints of the line segment are determined. The value obtained by subtracting the low-temperature side temperature from the high-temperature side temperature is taken as the full width at half maximum (°C). If there are multiple line segments, the peak height of the melting peak with the highest peak height is set to 1.0. For all line segments with a peak height of 0.3 or greater, the temperature at the endpoints is extracted, and the value obtained by subtracting the temperature on the lower side from the temperature on the higher side is calculated. The sum of these values ​​is taken as the full width at half maximum of the DSC curve. The measurement is performed three times using the same method, and the average value is obtained. If the resin film is not a single layer, the layer structure is confirmed by observing the cross-section of the film, and then 5 mg or more of resin layer A is scraped off using an ultramicrotome to obtain the DSC curve of resin layer A.

[0029] One method for adjusting the full width at half maximum (FWHM) of resin layer A to 25°C or less is to use polyolefins polymerized in such a way that the FWHM is reduced by control methods such as crystal growth control, catalyst control, or monomer supply control. Alternatively, polyolefins obtained by analyzing the molecular weight distribution of polyolefins during separation and purification after polymerization using techniques such as gel permeation chromatography (GPC) or fractionation, and extracting only those within the desired molecular weight range, can also be used. Furthermore, polyolefins in which the formation of large molecular weight polymer chains is suppressed by controlling reaction time, optimizing reaction conditions such as temperature, pressure, and catalyst concentration, or by adding molecular weight control agents, can also be used. Additionally, polyolefins polymerized using a polymerization catalyst with high activity per supported metal atom and high activity per unit catalyst amount (see, for example, Japanese Patent Publication No. 2010-229347) can also be used. For example, these resin films (preferably polyolefins) can be obtained, selected as candidates for the resin constituting resin layer A, and the FWHM of the resin layer can be measured using the above method. Those with a FWHM of 25°C or less can be adopted as the material constituting resin layer A. For example, the full width at half maximum (FWHM) can be reduced by polymerizing polyolefins with a small molecular weight distribution using ATRP precision radical polymerization, purifying the polymer after polymerization to remove low molecular weight components, or reducing the amount of additives (PE, elastomer, antioxidant). The same applies to kurtosis.

[0030] From the viewpoint of more favorably exhibiting the effects of the present invention, the melting peak temperature of the resin layer A is preferably about 80°C or higher, more preferably about 90°C or higher, even more preferably about 95°C or higher, and also preferably about 250°C or lower, more preferably about 200°C or lower, even more preferably about 160°C or lower, and even more preferably about 140°C or lower. Preferred ranges include approximately 80-250°C, 80-200°C, 80-160°C, 80-140°C, 90-250°C, 90-200°C, 90-160°C, 90-140°C, 95-250°C, 95-200°C, 95-160°C, and 95-140°C.

[0031] In this disclosure, the method for measuring the melting peak temperature is as follows:

[0032] <Measurement of melting peak temperature> The melting peak temperature of the sample (resin) will be measured in accordance with the provisions of JIS K7121:2012 (Method for measuring the transition temperature of plastics (Supplement 1 to JIS K7121:1987)). The measurement will be performed using a differential scanning calorimeter. The sample will be held at 0°C for 15 minutes, then heated from 0°C to 210°C at a heating rate of 10°C / min, and the first melting peak temperature P (°C) will be measured. After that, it will be held at 210°C for 10 minutes. Next, it will be cooled from 210°C to 0°C at a cooling rate of 10°C / min and held for 15 minutes. Furthermore, it will be heated from 0°C to 210°C at a heating rate of 10°C / min and the second melting peak temperature Q (°C) will be measured. The nitrogen gas flow rate will be 50 ml / min. By following the above procedure, the melting peak temperature P (°C) measured in the first measurement and the melting peak temperature Q (°C) measured in the second measurement are determined, and the melting peak temperature measured in the first measurement is taken as the melting peak temperature. When measuring samples with high melting peak temperatures, measurements may be taken in the range from 0°C to 500°C at the same heating rate. If the measurement sample is formed in multiple layers, the temperature of the melting peak showing the maximum peak intensity is taken as the melting peak temperature of the measurement sample.

[0033] The resin constituting resin layer A is not particularly limited as long as it is a resin with a full width at half maximum of 25°C or less. Resin layer A is preferably a layer containing a polyolefin resin (i.e., having a polyolefin skeleton), and more preferably a layer formed of a polyolefin resin. Examples of polyolefin resins include polyolefins such as polyethylene and polypropylene. The polyolefin resin may also be a resin in which polyolefin has been acid-modified (acid-modified polyolefin). Examples of acid-modified polyolefins are not particularly limited as long as they are acid-modified polyolefins, but preferably examples include polyolefins graft-modified with an unsaturated carboxylic acid or its anhydride, such as acid-modified polyethylene and acid-modified polypropylene.

[0034] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0035] 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 a cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, examples of cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0036] In acid-modified polyolefins, the polyolefin to be acid-modified is also preferably the aforementioned polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or its anhydride, or by block polymerization or graft polymerization of an α,β-unsaturated carboxylic acid or its anhydride to a cyclic polyolefin.

[0037] Examples of carboxylic acids or their anhydrides used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When polyolefin resins are 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 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. In other words, when polyolefin resins are measured by infrared spectroscopy in this case, a peak originating from maleic anhydride is detected. 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.

[0038] The resin layer A may be formed by a single resin component or by a blended polymer combining two or more resin components. From the viewpoint of film-forming properties of the resin layer A, it is preferable to form it by a blended polymer combining two or more resin components. When using a blended polymer, it is preferable that the resin layer A has acid-modified polypropylene as the main component (50% by mass or more) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of improving the electrolyte resistance of the resin layer A, it is preferable that the resin layer A contains polypropylene or acid-modified polypropylene alone as the resin.

[0039] Furthermore, the resin layer A may contain an adhesive component. Examples of adhesive components include elastomers.

[0040] The elastomer is not particularly limited as long as it exhibits adhesive properties when compounded with polyolefin, for example, an elastomer composed of a thermoplastic resin (thermoplastic elastomer) is preferred.

[0041] Preferred elastomers include styrene-based elastomers, olefin-based elastomers, acrylic-based elastomers, silicone-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, and rubber-based elastomers. The elastomer may be used individually or in combination of two or more types.

[0042] There are no particular limitations on the type of styrene-based elastomer, but specific examples include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

[0043] Examples of olefin-based elastomers include copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene. For example, ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM) are preferred. Also, copolymers of α-olefins with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene are also examples. Furthermore, carboxy-modified nitrile rubber obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid is also an example.

[0044] Acrylic elastomers are mainly composed of acrylic acid esters, and specifically, ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc., are preferably used. In addition, glycidyl methacrylate, allyl glycidyl ether, etc., can be used as crosslinking monomers. Furthermore, copolymers with acrylonitrile or ethylene can also be used. Specifically, examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

[0045] Silicone-based elastomers primarily consist of organopolysiloxanes, and include polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers.

[0046] Urethane elastomers consist of structural units of a hard segment made of low molecular weight ethylene glycol and diisocyanate, and a soft segment made of high molecular weight (long-chain) diol and diisocyanate. Examples of high molecular weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene neopentylene adipate).

[0047] Polyester elastomers are obtained by polycondensation of a dicarboxylic acid or its derivative with a diol compound or its derivative. Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, as well as aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic kernel are substituted with methyl, ethyl, or phenyl groups, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used individually or in combination of two or more.

[0048] Specific examples of diol compounds include aliphatic and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol. Furthermore, examples include bisphenol A, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-propane, and resorcinol. These compounds can be used individually or in combination of two or more.

[0049] Examples of polyamide-based elastomers include block copolymers in which polyamide is the hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene-propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, or silicone rubber are the soft segment components.

[0050] Examples of rubber-based elastomers include polyisobutylene.

[0051] Among elastomers, styrene-based elastomers and olefin-based elastomers are preferred, with styrene-based elastomers being particularly preferred.

[0052] The proportion of elastomer contained in resin layer A is not particularly limited, but is preferably about 50% by mass or less, more preferably about 10 to 50% by mass, and even more preferably about 10 to 40% by mass.

[0053] The resin layer A contained in the resin film 1 of this disclosure may be only one layer or may be two or more layers. The number of resin layers A contained in the resin film 1 is preferably one to three layers, more preferably one to two layers, and even more preferably one layer. As stated above, the resin layer A contained in the resin film 1 according to the second embodiment may be zero layers.

[0054] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the thickness of the resin layer A in the resin film 1 is preferably about 5 μm or more, more preferably about 8 μm or more, even more preferably about 10 μm or more, and also preferably about 80 μm or less, more preferably about 60 μm or less, even more preferably 40 μm or less. Preferred ranges include about 5 to 80 μm, about 5 to 60 μm, about 5 to 40 μm, about 8 to 80 μm, about 8 to 60 μm, about 8 to 40 μm, about 10 to 80 μm, about 10 to 60 μm, and about 10 to 40 μm. If there are two or more resin layers A, these thicknesses are the total thickness of the resin layers A.

[0055] From the viewpoint of more favorably exhibiting the effects of the present invention, the ratio of the thickness of resin layer A to the total thickness (100%) of resin film 1 is preferably about 5% or more, more preferably about 10% or more, and even more preferably about 15% or more. The upper limit is about 100%, about 95% or less, about 90% or less, about 85% or less, about 80%, etc. Preferred ranges are about 5-100%, about 5-95%, about 5-90%, about 5-85%, about 5-80%, about 10-100%, about 10-95%, about 10-90%, about 10-85%, about 10-80%, about 15-100%, about 15-95%, about 15-90%, about 15-85%, and about 5-85%. When resin layer A is included in two or more layers, the ratio of these thicknesses is the ratio of the total thickness of resin layer A.

[0056] (Resin layer B is different from resin layer A) As described above, in the resin film 1 of this disclosure, resin layer A is a resin layer in which, in the DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, when the height of the melting peak with the maximum peak height is set to 1.0. In other words, resin layer B, which is different from resin layer A, is a resin layer whose full width at half maximum exceeds 25°C. The full width at half maximum of resin layer B is not particularly limited as long as it exceeds 25°C.

[0057] From the viewpoint of more favorably exhibiting the effects of the present invention, the melting peak temperature of the resin layer B is preferably 80°C or higher, more preferably about 90°C or higher, even more preferably about 100°C or higher, and also preferably about 160°C or lower, more preferably about 150°C or lower, and even more preferably about 140°C or lower. Preferred ranges include approximately 80 to about 165°C, approximately 80 to 150°C, approximately 80 to 140°C, approximately 90 to 165°C, approximately 90 to 150°C, approximately 90 to 140°C, approximately 100 to 165°C, approximately 100 to 150°C, and approximately 100 to 140°C.

[0058] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, the half-width of the resin layer B is, for example, about 26°C or higher, about 30°C or higher, about 50°C or higher, and the upper limit is preferably about 90°C or lower, more preferably about 80°C or lower, and even more preferably about 70°C or lower. Preferred ranges include about 25°C to 90°C, about 25°C to 80°C, about 25°C to 70°C, about 26 to 90°C, about 26 to 80°C, about 26 to 70°C, about 30 to 90°C, about 30 to 80°C, about 30 to 70°C, about 50 to 90°C, about 50 to 80°C, and about 50 to 70°C. The method for measuring the half-width is as described above.

[0059] The material used to form resin layer B is not particularly limited. Examples of materials used to form resin layer B include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicon resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. Among these, it is particularly preferable to include a polyolefin resin, and more preferably to include a layer formed from a polyolefin resin. Even if the material used to form resin layer B is a polyolefin resin, resin layer B is a resin layer whose full width at half maximum exceeds 25°C.

[0060] Specifically, 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 polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); 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 copolymers thereof. These polyamides may be used individually or in combination of two or more.

[0061] Specifically, examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters with ethylene terephthalate as the main repeating unit, and copolymer polyesters with butylene terephthalate as the main repeating unit. Furthermore, specific examples of copolymer polyesters with ethylene terephthalate as the main repeating unit include copolymer polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). Furthermore, specific examples of copolymer polyesters with butylene terephthalate as the main repeating unit include copolymer polyesters polymerized with butylene isophthalate using butylene terephthalate as the main repeating unit (hereinafter abbreviated as polybutylene(terephthalate / isophthalate)), polybutylene(terephthalate / adipate), polybutylene(terephthalate / sebacate), polybutylene(terephthalate / decanedicarboxylate), and polybutylene naphthalate. These polyesters may be used individually or in combination of two or more types.

[0062] Furthermore, at least one of the resin layers B may be formed from a nonwoven fabric made of the above-mentioned resin. When formed from a nonwoven fabric, it is preferable that the nonwoven fabric is made of the aforementioned polyolefin resin, polyamide resin, or the like.

[0063] If the resin film 1 contains a resin layer B, the resin layer B may be only one layer or two or more layers. In this case, the number of resin layers B contained in the resin film 1 is preferably 1 to 5 layers, more preferably 1 to 3 layers, and even more preferably 1 to 2 layers.

[0064] When the resin film 1 of this disclosure includes a resin layer B, from the viewpoint of more favorably achieving the effects of the invention of this disclosure, the thickness of the resin layer B is preferably about 1 μm or more, more preferably about 3 μm or more, even more preferably about 5 μm or more, and also preferably about 50 μm or less, more preferably about 40 μm or less, even more preferably 30 μm or less. Preferred ranges include about 1 to 50 μm, about 1 to 40 μm, about 1 to 30 μm, about 3 to 50 μm, about 3 to 40 μm, about 3 to 30 μm, about 5 to 50 μm, about 5 to 40 μm, and about 5 to 30 μm. When two or more layers of resin layer B are included, these thicknesses are the total thickness of the resin layers B.

[0065] From the viewpoint of more favorably exhibiting the effects of the present invention, if the resin film is composed of multiple layers and includes resin layer A and resin layer B, the ratio of the thickness of resin layer A to the total thickness of resin layer A and resin layer B is preferably about 0.1 or more, more preferably about 0.3 or more, even more preferably about 0.5 or more, and also preferably about 50 or less, more preferably about 40 or less, even more preferably about 30 or less. Preferred ranges include about 0.1 to 50, about 0.1 to 40, about 0.1 to 30, about 0.3 to 50, about 0.3 to 40, about 0.3 to 30, about 0.5 to 50, about 0.5 to 40, and about 0.5 to 30.

[0066] (Additives) In the resin film 1 of this disclosure, at least one of the resin layers A and resin layer B may each contain, in addition to the resin, additives such as colorants such as pigments, fillers, and lubricants.

[0067] Various inorganic pigments can be used as pigments. Specific examples of pigments include carbon (carbon, graphite), as exemplified in the filler section described later. Carbon (carbon, graphite) is a material commonly used inside energy storage devices and can be suitably incorporated because it does not leach into the electrolyte. Furthermore, a sufficient coloring effect can be obtained with an amount that does not significantly impede adhesion, and it does not melt with heat, thus increasing the apparent melt viscosity of the added resin. In addition, it prevents the pressurized area from becoming thin during heat bonding (heat sealing), providing excellent sealing between the energy storage device exterior material and the metal terminals.

[0068] When a pigment is added to at least one of the resin layers A and B, the amount added is, for example, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin component of each layer of the resin film 1, when using carbon black with a particle size of about 0.03 μm. When both a pigment and a filler are added to the resin film 1, both the filler and the pigment may be added to the same layer, but from the viewpoint of not hindering the heat-sealing properties of the resin film 1, it is preferable to add the filler and the pigment to different layers.

[0069] The particle size of the filler can be in the range of approximately 0.1 to 35 μm, preferably approximately 5.0 to 30 μm, and more preferably approximately 10 to 25 μm. The filler content can be approximately 5 to 30 parts by mass, more preferably approximately 10 to 20 parts by mass, per 100 parts by mass of the resin component forming each layer of the resin film 1.

[0070] Both inorganic and organic fillers can be used. Examples of inorganic fillers include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. Examples of organic fillers include fluororesins, phenolic resins, urea resins, epoxy resins, acrylic resins, benzoguanamine-formaldehyde condensates, melamine-formaldehyde condensates, polymethyl methacrylate crosslinks, and polyethylene crosslinks. From the viewpoint of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, and among these, spherical aluminum oxide and silica are particularly preferred. As for the method of mixing the filler into the resin components that form each layer of the resin film 1, methods such as melt-blending the two in advance using a Banbury mixer or the like to create a masterbatch and then mixing it in a predetermined ratio can be employed, or a direct mixing method with the resin components can be used.

[0071] From the viewpoint of improving the sealing performance of the energy storage device of this disclosure, each layer constituting the surface of the resin film 1 may contain a lubricant. The concentration of the lubricant is preferably 2000 ppm or less, more preferably 1500 ppm or less, even more preferably 1000 ppm or less, and also preferably 200 ppm or more, more preferably 500 ppm or more, with preferred ranges being approximately 200 to 2000 ppm, approximately 200 to 1500 ppm, approximately 200 to 1000 ppm, approximately 500 to 2000 ppm, approximately 500 to 1500 ppm, and approximately 500 to 1000 ppm.

[0072] 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.

[0073] If the layers constituting the resin film 1 are made of resin films, the surfaces of these layers may be subjected to known easy-adhesion methods such as corona discharge treatment, ozone treatment, or plasma treatment, as needed.

[0074] In the manufacture of the resin film 1 of this disclosure, the lamination of each layer can be carried out by known methods such as the extrusion lamination method, the T-die method, the inflation method, and the thermal lamination method.

[0075] The melting peak temperature of the resin film for energy storage devices of this disclosure is preferably about 60°C or higher, more preferably about 80°C or higher, even more preferably about 90°C or higher, and also preferably about 250°C or lower, more preferably about 220°C or lower, and even more preferably about 200°C or lower. Preferred ranges include about 60-250°C, about 60-220°C, about 60-200°C, about 80-250°C, about 80-220°C, about 80-200°C, about 90-250°C, about 90-220°C, and about 90-200°C.

[0076] Multiple melting peak temperatures may be observed in the resin film 1, and multiple melting peak temperatures may be observed when multiple resins are used to form the resin film 1. It is preferable that the multiple melting peak temperatures observed in the resin film 1 satisfy the values ​​of these melting peak temperatures. However, this disclosure does not exclude resin films in which melting peak temperatures that do not satisfy these values ​​are observed from the resin film 1.

[0077] (Laminated structure and physical properties of resin films for energy storage devices) A resin film 1 according to a first aspect of the present disclosure includes at least a resin layer A, as shown, for example, in Figures 1 to 3. When the resin film 1 of the present disclosure has a single-layer structure, as shown in Figure 1, the resin layer A consists only of a first layer 11.

[0078] Furthermore, as shown in Figure 2, when the resin film 1 according to the first embodiment has a two-layer structure, it becomes a multilayer structure in which a first layer 11 made of resin layer A and a second layer 12 are laminated together. Moreover, as shown in Figure 3, when the resin film 1 according to the first embodiment has a three-layer structure, it becomes a multilayer structure in which a first layer 11 made of resin layer A, a second layer 12 and a third layer 13 are laminated together. The resin film 1 according to the first embodiment only needs to include at least one layer of resin layer A, and may have a multilayer structure such as a four-layer structure or a five-layer structure. When the resin film 1 has a multilayer structure, the number of layers of the resin film 1 may be, for example, 2 to 5 layers, 2 to 4 layers, or 2 to 3 layers. In Figures 2 and 3, the second layer 12 and the third layer 13 may each be resin layer A, or instead of resin layer A, they may be the aforementioned resin layer B.

[0079] Figure 2 shows an example in which the resin film 1 according to the first embodiment has a two-layer structure in which a first layer 11 and a second layer 12 are laminated, and the first layer 11 is resin layer A. However, both the first layer 11 and the second layer 12 may be resin layer A, and the second layer 12 may be resin layer B.

[0080] Furthermore, Figure 3 shows an example in which the resin film 1 according to the first embodiment has a three-layer structure in which a first layer 11, a second layer 12, and a third layer 13 are laminated, and the first layer 11 is resin layer A. However, in addition to the first layer 11, at least one of the second layer 12 and the third layer 13 may also be resin layer A or resin layer B.

[0081] As described above, when the resin film 1 according to the first embodiment has a multilayer structure, the resin layer A included in the resin film 1 of this disclosure may be only one layer or may be two or more layers, and the same applies when the resin film 1 according to the first embodiment has a four-layer structure, a five-layer structure, etc.

[0082] In the case where the resin film 1 according to the first embodiment has a multilayer structure of three or more layers, the first layer 11 constituting the resin layer A may be a layer constituting the surface of the resin film 1 of this disclosure, or it may not be a layer constituting the surface of the resin film 1. For example, Figure 3 shows a three-layer structure in which the second layer 12 and the third layer 13 are laminated on both sides of the first layer 11, which is the resin layer A. However, for example, it may also be a three-layer structure in which the first layer 11 and the third layer 13, which are the resin layer A, are laminated on both sides of the second layer 12.

[0083] In the resin film 1 according to the first embodiment, from the viewpoint of providing a layer other than the first layer 11 constituting the resin layer A with a function to enhance the heat-sealability of the resin film 1, it is also preferable that the layer constituting the surface of the resin film 1 is a resin layer B other than resin layer A.

[0084] On the other hand, the resin film according to the second embodiment does not need to include resin layer A, regardless of whether it is a single-layer structure or a multi-layer structure, and can be composed only of resin layer B. The resin film according to the second embodiment can also have, for example, a 1- to 5-layer structure, preferably a 1- to 4-layer structure, and more preferably a 1- to 3-layer structure (for example, the aforementioned first layer 11, second layer 12, and third layer 13 are all composed of resin layer B).

[0085] The thickness of the resin film 1 for energy storage devices is not particularly limited, as long as it does not exert the effects of the present invention. However, from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, and also preferably about 150 μm or less, more preferably about 120 μm or less, and even more preferably about 100 μm or less. Preferred ranges include about 10 to 150 μm, about 10 to 120 μm, about 10 to 100 μm, about 15 to 150 μm, about 15 to 120 μm, about 15 to 100 μm, about 20 to 150 μm, about 20 to 120 μm, and about 20 to 100 μm.

[0086] The resin film 1 according to the second embodiment has a kurtosis value of approximately 1.5 or more at the melting peak of the DSC curve obtained by differential scanning calorimetry. From the viewpoint of more favorably exhibiting the effects of the present invention, the kurtosis value of the resin film 1 according to the second embodiment is preferably approximately 2.5 or more, more preferably approximately 3.0 or more, and the upper limit is, for example, approximately 10.0 or less, approximately 8.0 or less, approximately 6.0 or less, and preferred ranges include approximately 1.5 to 10.0, approximately 1.5 to 8.0, approximately 1.5 to 6.0, approximately 2.5 to 10.0, approximately 2.5 to 8.0, approximately 2.5 to 6.0, approximately 3.0 to 10.0, approximately 3.0 to 8.0, and approximately 3.0 to 6.0. The method for measuring the kurtosis value is as follows.

[0087] <Measurement of kurtosis value (kurtosis) of melting peak by differential scanning calorimetry> The following procedure is used to obtain a differential scanning calorimetry (DSC) curve for a resin film and measure the kurtosis value of the melting peak in the DSC curve. Specifically, the differential scanning calorimetry (DSC) curve is obtained using a differential scanning calorimetry device with a sample weight of approximately 5 mg under a nitrogen atmosphere. The resin is heated from 0°C to 210°C at a heating rate of 10°C / min, and the straight line connecting the 40°C point and the 200°C point on the DSC curve obtained from the first heating is used as the baseline. The kurtosis is calculated for the melting peak of the obtained DSC curve. Here, kurtosis is defined as the fourth-order standardized moment minus 3, so that the kurtosis of the normal distribution is 0. The kurtosis is calculated using the Kurtosis function from the Python scipy library. The measurement is performed three times using the same method, and the average value is adopted.

[0088] As a means of adjusting the crustosis value of the resin film 1 to 1.5 or higher, the same means as for adjusting the full width at half maximum of the resin layer A can be exemplified. The polyolefin can be obtained, used as a candidate resin for the resin film 1, and the crustosis value of the resin film 1 can be measured using the method described above. Those with a value of 1.5 or higher can be adopted as the material for the resin film 1.

[0089] Furthermore, with respect to the resin film 1 according to the first embodiment, from the viewpoint of more favorably exhibiting the effects of the present invention, the kurtosis value (kurtosis) of the melting peak of the DSC curve obtained by differential scanning calorimetry is preferably about 1.5 or more, more preferably about 2.5 or more, and even more preferably about 3.0 or more. The upper limit is, for example, about 10.0 or less, about 8.0 or less, about 6.0 or less, and preferred ranges include about 1.5 to 10.0, about 1.5 to 8.0, about 1.5 to 6.0, about 2.5 to 10.0, about 2.5 to 8.0, about 2.5 to 6.0, about 3 to 10.0, about 3.0 to 8.0, and about 3.0 to 6.0.

[0090] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the resin film 1 of the present disclosure has the characteristic that the ratio of the following seal strength B (N / 15mm) to the following seal strength A (N / 15mm) (seal strength B / seal strength A) is preferably 2.0 or more, more preferably 2.4 or more, and even more preferably 2.7 or more. The upper limit of this ratio is, for example, 40 or less, preferably 30 or less, and even more preferably 25 or less, and preferred ranges include approximately 2.0 to 40, approximately 2.0 to 30, approximately 2.0 to 25, approximately 2.4 to 40, approximately 2.4 to 30, approximately 2.4 to 25, approximately 2.7 to 40, approximately 2.7 to 30, and approximately 2.7 to 25.

[0091] Furthermore, the resin film 1 of this disclosure has a seal strength A (N / 15mm) of preferably 50N / 15mm or less, more preferably 45N / 15mm or less, and even more preferably 40N / 15mm or less. The lower limit is, for example, 1N / 15mm or more, preferably 3N / 15mm or more. Preferred ranges include approximately 1-50N / 15mm, 1-45N / 15mm, 1-40N / 15mm, 3-50N / 15mm, 3-45N / 15mm, and 3-40N / 15mm.

[0092] <Measurement conditions for seal strength A and B> (Measurement of opening temperature) The seal strengths A and B (N / 15mm) of the resin film for energy storage devices are measured according to the application in which the resin film for energy storage devices is used (described later). Furthermore, the temperatures A and B used when measuring seal strengths A and B are determined by performing the following opening tests 1-5, depending on the application.

[0093] (Opening Test 1) When the resin film for energy storage devices of this disclosure is used to interpose between heat-fusible resin layers at a location where heat-fusible resin layers of an exterior material for energy storage devices are heat-fussed together (see Application 1 below), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 1.

[0094] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) Prepare one casing material for an energy storage device (8cm wide x 19cm high) with a total thickness of 153μm, consisting of layers with a melting peak temperature of 140℃ and a thickness of 40μm, stacked in this order. Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device should be 3cm wide x 1.5cm high. Position the casing material and the resin film for the energy storage device so that their horizontal and vertical dimensions match. More specifically, horizontally, the center positions of the casing material and the resin film for the energy storage device should be... The materials are positioned to match, and vertically, the 3cm long side of the resin film for the energy storage device is aligned with the 8cm short side of the outer casing material for the energy storage device, which is the vertical bottom edge. Next, the short side of the outer casing material for the energy storage device and the two long sides where the resin film for the energy storage device is positioned are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample, and it is placed in an oven. Air is blown into the test sample, and the internal pressure is maintained at a constant level once it reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature when the test sample is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0095] (Measurement of seal strength A and B at temperatures A and B determined in opening test 1) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) An exterior material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers of 40 μm each (with a melting peak temperature of 140°C) in that order, and it is cut to a size of 60 mm (Z direction) x 150 mm (X direction). The exterior material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and an energy storage device resin film (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between them. In this state, a laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (where both sides of the energy storage device resin film are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the energy storage device resin film is sandwiched between the heat-sealable resin layers.

[0096] For the obtained test specimens, the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature -20°C) shall be measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at each measurement environment temperature, one exterior material for the energy storage device and the opposite exterior material for the energy storage device are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance is 50 mm), and the seal strength (N / 15 mm) at each temperature is measured.

[0097] (Opening Test 2) When the resin film for energy storage devices of this disclosure is used as an adhesive film for metal terminals interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing that seals the energy storage device element (see Application 4 below), the temperatures A and B used when measuring the seal strengths A and B are determined by the procedure of the following opening test 2.

[0098] (procedure) (Fabrication of resin films for energy storage devices with metal terminals) A metal terminal is prepared by using an aluminum alloy foil measuring 400 μm thick × TD 15 mm × MD 55 mm as the metal terminal, and after alkaline cleaning, a surface-treated metal terminal is prepared by baking a treatment layer of chromate phosphate to a thickness of approximately 100 nm. Two pieces of adhesive film for metal terminals are cut to the size of TD 15 mm × MD 30 mm. A resin film for a power storage device with metal terminals is prepared, consisting of a laminate of adhesive film for metal terminals / metal terminal / adhesive film for metal terminals (placed so that the center of the MD direction of the metal terminal and the center of the MD direction of the adhesive film for metal terminals coincide). A polytetrafluoroethylene (PTFE film, thickness 100 μm) is placed on top of the laminate (covering the surface of the adhesive film for metal terminals with the PTFE film), and the laminate is placed on a press machine heated to 200°C (resin layer A is on the hot plate side), and a silicone sponge sheet is placed on top, and the resin film is heated by standing at a pressure of 0.25 MPa for 16 seconds. Allow the heated laminate to cool naturally to 25°C.

[0099] Prepare one 153μm thick exterior material for an energy storage device (8cm wide x 19cm high) with a total thickness of 153μm, consisting of the following layers: base layer (PET (12μm thick) / adhesive (3μm thick) / nylon (15μm thick) / adhesive layer (3μm thick) / barrier layer (aluminum alloy foil, 40μm thick) / adhesive layer (maleic anhydride modified polypropylene, 40μm thick) / heat-sealable resin layer (polypropylene, peak melting temperature 140℃, 40μm thick). Fold the exterior material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during opening test 2. As shown in the schematic diagrams of Figures 6 and 7, the peripheral area where the heat-sealable resin layers of the energy storage device exterior material are heat-sealed together. At the short side of 3a, a resin film for energy storage devices with metal terminals is placed between the heat-sealable resin layers. Furthermore, the resin film is positioned so that its horizontal (z-direction) and vertical (x-direction) orientations coincide with the exterior material for the energy storage device. More specifically, in the horizontal (z-direction), the center positions of the exterior material for the energy storage device and the resin film for energy storage devices with metal terminals coincide, and in the vertical (x-direction), the 3cm long side of the resin film for energy storage devices, which is the lower end of the vertical (x-direction), aligns with the 8cm short side of the exterior material for the energy storage device, which is the lower end of the vertical (x-direction). Next, the short side of the exterior material for the energy storage device where the resin film for energy storage devices with metal terminals is placed is heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 200°C, 6 seconds, and a seal width of 7 mm, and the two long sides are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in an oven. A φ5 mm tube is attached to the jig set up above, ensuring that no air leaks. Air is introduced into the sample through the tube and the pressure is increased to 0.1 MPa. With the pressure increased to 0.1 MPa, the test sample temperature is heated from room temperature (25°C) at a heating rate of 6°C / min until it reaches 150°C. The opening temperature of the test sample when it is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0100] (Measurement of seal strength A and B at temperatures A and B determined in opening test 2) The sealing strengths A and B of the resin film for the energy storage device at temperatures A and B determined in opening test 2 are measured using the following procedure.

[0101] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) A casing material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers of 40 μm each (with a peak melting temperature of 140°C) in that order, and it is cut to a size of 60 mm (Z direction) x 150 mm (X direction). The heat-sealable resin layer of the casing material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film with metal terminals (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between the layers. In this state, a laminate is obtained by heat-sealing it in a sealing machine with an upper metal head and a lower rubber head at 200°C x 0.5 MPa x 6 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (one side of each of the two resin films for energy storage devices, which are placed on both sides of the metal terminals, is heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film for energy storage devices is sandwiched between the heat-sealable resin layers of the casing material for energy storage devices)

[0102] The obtained test specimens are measured in accordance with JIS K7127:1999, determining the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature -20°C) as follows: Using a tensile testing machine with a constant temperature chamber, one outer packaging material and the opposite outer packaging material are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) at each temperature is measured. A thermocouple is attached to the test specimen, and the test specimen itself is heated to temperature A or B, held for 1 minute, and then tensile testing is started.

[0103] (Opening Test 3) When the resin film for energy storage devices of this disclosure is used as a heat-sealable resin layer for an exterior material for an energy storage device (see Application 2 below), or as an adhesive layer between the barrier layer and the heat-sealable resin layer for an exterior material for an energy storage device (see Application 3 below), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 3.

[0104] (procedure) A biaxially oriented PET film (12 μm thick) and a biaxially oriented nylon film (3 μm thick) are laminated in this order as base layers using a dry lamination method. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021 H-O, 40 μm thick) with corrosion-resistant coatings formed on both sides is laminated using a dry lamination method. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of the PET film to form an adhesive layer (3 μm thick after curing) on ​​the PET film. Next, the biaxially oriented nylon film is laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of the aluminum foil with corrosion-resistant coatings formed on both sides to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Next, the adhesive layer on the aluminum foil and the PET film / nylon film laminate are laminated in a direction in which the nylon film is in contact with the aluminum foil, and then an aging treatment is performed to create a laminate of a base layer / adhesive layer / barrier layer.

[0105] Next, in the case where "the resin film for energy storage devices of this disclosure is used as a heat-sealable resin layer for an exterior material for energy storage devices (see Application 2 below))", a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, the resin film for energy storage devices is laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the obtained laminate is aged and heated to obtain an exterior material for energy storage devices (total thickness 123 μm) in which a biaxially oriented PET film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (3 μm) / heat-sealable resin layer (50 μm) are laminated in this order.

[0106] On the other hand, when the resin film for energy storage devices of this disclosure is "used as an adhesive layer between the barrier layer and the heat-fusible resin layer of an exterior material for energy storage devices (see Application 3 below))", the adhesive layer / heat-fusible resin layer is laminated on top of the barrier layer of each laminate obtained above by co-extruding a resin that forms the adhesive layer (30 μm thick) as a resin film for energy storage devices and random polypropylene (peak melting temperature 140°C) that forms the heat-fusible resin layer (10 μm thick) on top of the barrier layer of each laminate obtained above. Next, the obtained laminate is aged and heated to obtain an exterior material for energy storage devices (total thickness 113 μm) in which a biaxially oriented PET film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (30 μm) / heat-fusible resin layer (10 μm) are laminated in this order.

[0107] Following the above procedure, one casing material for the energy storage device is prepared. The casing material for the energy storage device is folded in half so that the heat-sealable resin layer is on the inside, and a φ11 mm hole is made in one place on one side (exactly in the center of the rectangle measuring 8 cm wide x 9.5 cm high). A jig for installing a tube to supply air into the sample during opening test 3 is attached to the position of the hole. As shown in the schematic diagrams of Figures 6 and 7, the short side and two long sides of the test piece, which is the casing material for the energy storage device, are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in the oven, and a φ5 mm tube is attached to the jig installed above so as not to leak air. Air is supplied into the sample through the tube and the pressure is increased to 0.1 MPa. With the pressure increased to 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature B (°C) is defined as temperature A - 20°C.

[0108] (Measurement of seal strength A and B at temperatures A and B determined in opening test 3) The sealing strengths A and B of the resin film for the energy storage device at temperatures A and B determined in opening test 3 are measured using the following procedure.

[0109] (procedure) After cutting the exterior material for the energy storage device obtained by the above procedure to a size of 60 mm in the MD direction and 150 mm in the TD direction, the heat-sealable resin layer of the exterior material for the energy storage device is folded in half with the heat-sealable resin layer facing inward, and the heat-sealable resin layers of the exterior material are heat-sealed together using a heat sealing machine with 7 mm wide upper and lower metal heads at a temperature of 190°C, a surface pressure of 0.5 MPa, and for 3 seconds to obtain a laminate. The obtained laminate is cut to obtain 15 mm strip-shaped test pieces. The seal strength of the obtained test pieces at temperatures A and B is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at temperatures A and B, one exterior material for an energy storage device and the opposite exterior material for an energy storage device are chucked and pulled at a peel angle of 180° (chuck distance is 50 mm), and the seal strength A (N / 15 mm) at temperature A and the seal strength B (N / 15 mm) at temperature B are measured.

[0110] (Opening Test 4) When the resin film for energy storage devices of this disclosure is used to be interposed between the exterior material and the lid of the energy storage device (see Application 5 below), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 4.

[0111] (procedure) Prepare one 153μm thick exterior material for an energy storage device (360mm in the MD direction x 180mm in the TD direction), with the following layers stacked in this order: base layer (PET (thickness 12μm) / adhesive (thickness 3μm) / nylon (thickness 15μm) / adhesive layer (thickness 3μm) / barrier layer (aluminum alloy foil, thickness 40μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140℃, thickness 40μm). Wrap the exterior material around a dummy cell (aluminum metal block) measuring 100mm (vertical) x 140mm (horizontal) x 30mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the exterior material for the energy storage device faces the block. Covers 60 (100mm (vertical) x 5mm (horizontal) x 30mm (thickness), polypropylene) are placed on the openings (left and right) of the exterior material for the energy storage device. Set one of each (melting peak temperature 140°C). A resin film for the energy storage device is sandwiched between one of the lids 60 and the outer material for the energy storage device. After wrapping the lid 60 and dummy cell and applying tension so that there is no gap, the heat-sealable resin layers of the outer material for the energy storage device are heat-sealed at the heat-sealed portion 70 where they meet, using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. Lid The contact surface between 60 and the exterior material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and a time of 3 seconds to obtain a test sample in which the exterior body of the energy storage device includes the exterior material for the energy storage device and a lid, and is interposed between the exterior material for the energy storage device and the lid. In the test sample, a φ11 mm hole is pre-drilled in the center of an aluminum metal block measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which is used as a dummy cell. At this time, a similar hole is drilled in the same position as the dummy cell. To ensure a match, a φ11mm hole is pre-drilled in the outer casing. A jig is attached to the hole in the test sample, and a φ5mm tube is then attached to the jig, ensuring no air leaks. Air is introduced into the sample through the tube, and the pressure is increased to 0.1 MPa. With the pressure at 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0112] (Measurement of seal strength A and B at temperatures A and B determined in opening test 4) The sealing strengths A and B of the resin film for the energy storage device at temperatures A and B determined in opening test 4 are measured using the following procedure.

[0113] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) One sheet of exterior material for energy storage devices (360mm in the MD direction x 180mm in the TD direction) with a total thickness of 153μm is prepared, consisting of layers with a melting peak temperature of 140℃ and a thickness of 40μm stacked in this order. The heat-sealable resin layer of the exterior material for energy storage devices is wrapped around a dummy cell (aluminum metal block) measuring 100mm in length x 140mm in width x 30mm in thickness, which mimics an electrode body, so that the heat-sealable resin layer faces the block. One lid 60 (100mm in length x 5mm in width x 30mm in thickness, polypropylene, melting peak temperature 140℃) is set on each of the openings (left and right) of the exterior material for energy storage devices. An energy storage device resin film is sandwiched between one of the lids 60 and the exterior material for energy storage devices, and the heat-sealed joints 70 where the exterior materials for energy storage devices face each other are made to contact while tension is applied after wrapping, ensuring there is no gap between the lid 60 and the dummy cell, using a dedicated wrapping and sealing machine. At a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, heat sealing is performed using an upper metal sealing bar and a lower silicone rubber. The junction between the lid 60 and the exterior material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. An incision is made in the test sample along the long side direction of the lid material (MD direction of the exterior material) with a cutter, and the dummy cell that was placed inside is removed. An incision of 15 mm width is made in the exterior material for the energy storage device at the position including the installation position of the resin film for the energy storage device, and a test piece is obtained in which the exterior material for the energy storage device / resin film for the energy storage device is 15 mm wide and sealed to the lid. The obtained test piece is JIS In accordance with the provisions of K7127:1999, the seal strength at the measurement temperatures A and B shall be measured as follows:Using a tensile testing machine with a constant temperature chamber, the sealing strength (N / 15mm) between the exterior material for the energy storage device, the resin film for the energy storage device, and the lid is measured at a speed of 300 mm / min in the measurement environments of temperature A and temperature B, respectively, with one exterior material and the opposite lid chucked together at a peel angle of 180° (chuck distance of 50 mm), and the sealing strength (N / 15 mm) at each temperature is measured.

[0114] (Opening test 5) When the resin film for energy storage devices of this disclosure is used to be interposed between the lid body and the covering of the exterior of the energy storage device (see Application 6 below), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 5.

[0115] (procedure) Prepare one 153μm thick exterior material for an energy storage device (360mm in the MD direction x 180mm in the TD direction), consisting of the following layers: base layer (PET (thickness 12μm) / adhesive (thickness 3μm) / nylon (thickness 15μm) / adhesive layer (thickness 3μm) / barrier layer (aluminum alloy foil, thickness 40μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140℃, thickness 40μm). Wrap the exterior material for the energy storage device around a dummy cell (aluminum metal block) measuring 100mm (vertical) x 140mm (horizontal) x 30mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the exterior material for the energy storage device faces the block. Set one lid 60 on each of the openings (left and right) of the exterior material for the energy storage device. A cover 60 was formed by insert molding a 1mm thick polypropylene (peak melting temperature 140°C), which is heat-sealable to the exterior of an energy storage device, onto the periphery of an aluminum frame measuring 98mm in length, 5mm in width, and 28mm in thickness, as a covering 61. At this time, before injection molding, a resin film for energy storage devices, cut to a size of 8mm in the MD direction and 50mm in the TD direction, was placed on one of the longitudinal sides of the cover body 62 and injected molded so that it was sandwiched between the cover body 62 and the covering 61. 60. After wrapping the dummy cell and applying tension to ensure there is no floating, the heat-sealable resin layers of the outer material for the energy storage device are heat-sealed at the heat-sealable portion 70 where they meet using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. The contact surface between the lid 60 and the outer material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, so that the outer body of the energy storage device is sealed to the energy storage device. A test sample is obtained that includes an exterior material for a pipe and a lid, wherein the lid includes a lid body and a covering that covers the periphery of the lid body, and is interposed between the lid body and the covering. In the test sample, a φ11 mm hole is pre-drilled in the center of an aluminum metal block measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which is used as a dummy cell. At this time, a φ11 mm hole is also pre-drilled in the exterior material so that a similar hole aligns with the dummy cell.A jig is attached to the hole in the test sample, and a φ5mm tube is then attached to the jig in a way that prevents air leakage. Air is introduced into the sample through the tube to increase the pressure to 0.1 MPa. With the pressure at 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature B (°C) is defined as temperature A - 20°C.

[0116] (Measurement of seal strength A and B at temperatures A and B determined in opening test 5) The sealing strengths A and B of the resin film for the energy storage device at temperatures A and B determined in opening test 5 are measured using the following procedure.

[0117] (procedure) Prepare one casing material for an energy storage device with a total thickness of 153 μm (360 mm in the MD direction x 180 mm in the TD direction), consisting of the following layers: base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm). Wrap the casing material around a dummy cell (aluminum metal block) measuring 100 mm (length) x 140 mm (width) x 30 mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the casing material for the energy storage device faces the block side. Covers 60 are placed on the openings (left and right) of the casing material for the energy storage device. Set them one by one. A cover 61 is made by insert molding a 1mm thick polypropylene (peak melting temperature 140℃) that can be heat-welded to the outer casing of the energy storage device into the periphery of the lid body 62 (98mm long x 5mm wide x 28mm thick, made of aluminum) to form the lid body 60. At this time, before injection molding, a resin film for the energy storage device cut to a size of 8mm in the MD direction x 50mm in the TD direction is placed on one of the longitudinal sides of the lid body 62. The lid body 62 and the covering 61 are injection molded so as to be sandwiched between them. After wrapping the lid body 60 and the dummy cell, tension is applied so that there is no gap between them, and the heat-sealable resin layers of the exterior material for the energy storage device come into contact with each other. The heat-sealable portion 70 is then heat-sealed using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. The contact edges of the lid body 60 and the exterior material for the energy storage device are heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and the lid includes a lid body and a covering that covers the periphery of the lid body, and is interposed between the lid body and the covering. An incision is made in the test sample along the long side direction of the lid material (MD direction of the exterior material) with a cutter, and the dummy cell that was placed inside is removed.A 15mm wide cut is made in the exterior material for the energy storage device at the location where the resin film for the energy storage device is installed, and a test specimen is obtained in which the exterior material for the energy storage device is 15mm wide and sealed to the lid, and furthermore, the resin film for the energy storage device is sandwiched at the boundary between the lid body and the covering of the lid to which the 15mm wide exterior material for the energy storage device is sealed. For the obtained test specimen, the seal strength at the measurement temperatures A and B is measured in accordance with the provisions of JIS K7127:1999 as follows: Using a tensile testing machine with a constant temperature chamber, at the measurement environments of temperatures A and B, one exterior material and the opposite lid are chucked and pulled at a speed of 300mm / min with a peel angle of 180° (chuck distance is 50mm), and the seal strength (N / 15mm) at each temperature between the exterior material for the energy storage device / covering of the lid / resin layer for the energy storage device / lid body is measured. A thermocouple is attached to the test specimen, and once the specimen itself reaches temperature A or temperature B, tension is started after holding it for 1 minute.

[0118] [Application] The resin film 1 for energy storage devices of this disclosure can be suitably used as a resin film for energy storage devices because, even if the internal temperature of the energy storage device rises, the energy storage device elements are sealed by the outer casing up to a predetermined temperature of 60°C or higher, and when the predetermined temperature is exceeded, the energy storage device is opened at the location of the resin film 1 for energy storage devices. The following 1) to 6) are examples of specific applications of the resin film 1 for energy storage devices of this disclosure.

[0119] 1) In applications where the heat-sealable resin layers of the exterior material for energy storage devices are heat-sealed together, the material is interposed between the heat-sealable resin layers. 2) Applications in which it is used as a heat-sealable resin layer for exterior materials of energy storage devices. 3) Applications where it is used as an adhesive layer between the barrier layer and the heat-fusible resin layer of the exterior material for energy storage devices. 4) An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrode of a power storage device element and an outer casing that seals the power storage device element. 5) The casing of the energy storage device includes an casing material for the energy storage device and a cover. Applications in which the device is interposed between the exterior material for the energy storage device and the cover. 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. Applications in which it is interposed between the lid body and the covering

[0120] The following will explain the uses described in 1) through 6) above with specific examples.

[0121] 1) Uses (Applications in which the heat-sealable resin layers of the exterior material for energy storage devices are interposed between the heat-sealable resin layers at the point where they are heat-sealed together.) For example, in Figures 6 and 7, the resin film 1 for energy storage devices of this disclosure is interposed between opposing heat-fusible resin layers 35 at the peripheral edge 3a of the exterior material 3 for energy storage devices, where the heat-fusible resin layers 35 are heat-fussed together to seal the energy storage device elements 4 of the energy storage device 10 of this disclosure. In Figure 10, the resin film 1 of this disclosure is interposed between opposing heat-fusible resin layers 35 at the heat-fussed portion 70 (a strip-shaped portion extending from the ridge on the long side of the exterior material 3 for energy storage devices) where the heat-fusible resin layers 35 are heat-fussed together to seal the energy storage device elements 4 of the energy storage device 10 of this disclosure. The resin film 1 and the heat-fusible resin layers 35 on both sides thereof are heat-fussed together when the energy storage device elements 4 are sealed with the exterior material 3 for energy storage devices. That is, both sides of the resin film 1 are heat-fusible to the heat-fusible resin layers 35.

[0122] The resin film 1 of this disclosure seals the energy storage device 10 until the energy storage device 10 reaches a predetermined temperature of 60°C or higher. When the energy storage device reaches the predetermined temperature, the energy storage device opens at the position of the resin film 1 between the heat-sealable resin layers, allowing gas generated inside the energy storage device to be released to the outside. By positioning the resin film 1 in a part of the area where the heat-sealable resin layers 35 of the exterior material for the energy storage device are heat-sealed together, gas can be selectively discharged to the outside from a specific position where the resin film 1 is placed. In other words, the position from which the gas is discharged can be set to any position in the heat-sealed portion between the heat-sealable resin layers 35.

[0123] In the application of 1) described above, the position in which the resin film 1 of this disclosure is placed is not particularly limited as long as it is a position in which the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device are heat-sealed together. For example, if the energy storage device 10 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the peripheral edge 3a of the heat-sealed exterior material 3 for the energy storage device. Furthermore, the resin film 1 of this disclosure only needs to be placed in at least one location among the positions in which the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device are heat-sealed together, and may be placed in two or more locations.

[0124] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figure 6, if the energy storage device 10 is rectangular in plan view and the resin film is placed along one side of the rectangle (in the example in Figure 6, the resin film is placed along the z direction), the ratio of the length of the resin film 1 to the length of that side is, for example, about 3 to 98%. Also, the ratio of the width direction of the resin film (perpendicular to the length direction and thickness direction, in the example in Figure 6, the direction along the x direction) to the seal width of that side (perpendicular to the length direction and thickness direction, in the example in Figure 7, the direction along the x direction) is, for example, about 30 to 200%. Furthermore, the size of the resin film in the width direction is, for example, about 20 to 300%, with the size of the resin film 1 in the length direction as the base 100%.

[0125] In the energy storage device 10, the metal terminal 2 is electrically connected to the energy storage device element 4 and protrudes to the outside of the energy storage device exterior material 3. It is preferable that the resin film 1 of this disclosure is positioned so as not to be located between the metal terminal 2 and the energy storage device exterior material 3 (heat-fusible resin layer). Furthermore, it is preferable that the resin film 1 of this disclosure does not come into contact with the metal terminal 2.

[0126] 2) Uses (Used as a heat-sealable resin layer for exterior materials of energy storage devices) In applications where the resin film 1 for energy storage devices of this disclosure is used as a heat-sealable resin layer 35 of an exterior material 3 for energy storage devices, as shown in Figure 4, the resin film 1 for energy storage devices of this disclosure is used as a heat-sealable resin layer 35 of an exterior material 3 for energy storage devices which is composed of a laminate having, from the outside, at least a barrier layer 33 and a heat-sealable resin layer 35 in that order.

[0127] In application 2), the resin film 1 for energy storage devices is used as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices. Therefore, when the energy storage device element is sealed with the exterior material 3 for energy storage devices, the resin film 1 constituting the heat-sealable resin layer 35 is heat-sealed.

[0128] By using the resin film 1 for energy storage devices of this disclosure as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices, the energy storage device can be opened at the location of the heat-sealable resin layer 35, allowing gas generated inside the energy storage device to be released to the outside. In this application, when multiple exterior materials for energy storage devices are used to seal the energy storage device elements, it is sufficient that the heat-sealable resin layer of at least one of the exterior materials for energy storage devices is made of the resin film 1 for energy storage devices of this disclosure, and the heat-sealable resin layers of the remaining exterior materials for energy storage devices do not need to be made of the resin film 1 for energy storage devices.

[0129] 3) Uses (Used as an adhesive layer between the barrier layer and the heat-sealable resin layer of the exterior material for energy storage devices) In applications where the resin film 1 for energy storage devices of this disclosure is used as an adhesive layer 34 between the barrier layer 33 and the heat-fusible resin layer 35 of the exterior material 3 for energy storage devices, as shown in Figure 5, the resin film 1 for energy storage devices of this disclosure is used as an adhesive layer 34 of the exterior material 3 for energy storage devices, which is composed of a laminate comprising, from the outside, at least, a barrier layer 33, an adhesive layer 34, and a heat-fusible resin layer 35 in that order.

[0130] By using the resin film 1 for energy storage devices of this disclosure as the adhesive layer 34 of the exterior material 3 for energy storage devices, the energy storage device can be opened at the location of the adhesive layer 34, allowing gas generated inside the energy storage device to be released to the outside. In this application, when multiple exterior materials for energy storage devices are used to seal the energy storage device elements, it is sufficient that the adhesive layer of at least one exterior material for energy storage devices is made of the resin film 1 for energy storage devices of this disclosure, and the adhesive layers of the remaining exterior materials for energy storage devices do not need to be made of the resin film 1 for energy storage devices.

[0131] 4) Uses (Used as an adhesive film for metal terminals, interposed between metal terminals electrically connected to the electrodes of an energy storage device element and an outer casing that seals the energy storage device element.) In applications where the resin film 1 for energy storage devices of this disclosure is used as an adhesive film for metal terminals interposed between metal terminals electrically connected to electrodes of an energy storage device element and an outer casing that seals the energy storage device element, the resin film 1 for energy storage devices is used as an adhesive film 5 for metal terminals, as shown in Figures 8 and 9.

[0132] By using the resin film 1 for energy storage devices of this disclosure as an adhesive film 5 for metal terminals, the energy storage device can be opened at the location of the adhesive film 5 for metal terminals, allowing gas generated inside the energy storage device to be released to the outside. In this application, if multiple adhesive films for metal terminals are used, it is sufficient that at least one of the adhesive films for metal terminals is made of the resin film 1 for energy storage devices of this disclosure; the remaining adhesive films for metal terminals do not need to be made of the resin film 1 for energy storage devices.

[0133] 5) Uses (Applications in which the exterior of a power storage device includes an exterior material for the power storage device and a lid, and is used interposed between the exterior material for the power storage device and the lid.) As shown in Figures 10 and 11, if the exterior 30 of the energy storage device 10 includes an exterior material 3 for the energy storage device and a cover 60, the resin film 1 for the energy storage device of this disclosure can be used interposed between the exterior material 3 and the cover 60. Figure 10 shows two resin films 1: one used for application 1) and another used for application 5).

[0134] As shown in Figures 10 and 11, in this disclosure, the energy storage device element 4 of the energy storage device 10 may be sealed by other members such as a lid 60 in addition to the energy storage device exterior material 3. The energy storage device exterior material 3 and other members such as the lid 60 constitute an exterior body 30 (exterior body for energy storage device) that seals the energy storage device element 4. As shown in Figures 10 and 11, for example, the energy storage device element may be housed inside the cylindrical energy storage device exterior material 3, and the opening may be closed with a lid 60. Figure 11 shows a diagram in which the lid 60 is composed of a lid body 62 and a covering 61 (covering the periphery of the lid body 62).

[0135] Another example of using the cover 60 is to house the energy storage device element connected to the cover 60 inside the casing material 3 for the energy storage device, which is configured in a cylindrical shape so that an opening is formed, and then close the opening with the cover 60. In this case, the cover 60 also functions as a metal terminal 2 (for example, as shown in Figure 13). The cover 60 and the casing material 3 for the energy storage device are preferably joined by any means.

[0136] When using the cover 60, it is preferable that the exterior material 3 for the energy storage device be wrapped around the energy storage device element and the cover 60, in order to reduce the dead space between the energy storage device element and the exterior material 3 for the energy storage device in order to improve the volumetric energy density of the energy storage device.

[0137] The lid 60 can be formed, for example, from a resin molded product, a metal molded product, or a combination thereof. In this disclosure, when the lid is described as a resin molded product, the lid is not composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the lid is a metal molded product, the lid can also function as a metal terminal, and therefore the lid can be a metal terminal. The lid may be composed of a resin material and a conductive material.

[0138] For example, in the schematic diagrams shown in Figures 10 and 11, an energy storage device element is housed inside a cylindrical outer casing material 3 for the energy storage device, and the opening is closed by a resin lid 60. The lid 60 also has a through hole into which a metal terminal 2 electrically connected to the energy storage device element 4 is inserted. In this embodiment, the energy storage device 10 consists of an outer casing material 3 and a lid 60 that seals the energy storage device element 4, and the metal terminal 2 is exposed to the outside through the through hole in the lid 60. An adhesive film 5 can be placed between the metal terminal 2 and the lid 60 to improve their adhesion.

[0139] In the application of 5) described herein, by using the resin film 1 for energy storage devices of this disclosure interposed between the exterior material 3 for energy storage devices and the lid 60, the energy storage device can be opened at the position between the exterior material 3 and the lid 60, and gas generated inside the energy storage device can be released to the outside.

[0140] In the application of 5) described above, the position in which the resin film 1 of the present disclosure is placed is not particularly limited as long as it is between the exterior material 3 for the energy storage device and the lid 60. For example, if the lid 60 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the periphery of the lid 60. Furthermore, the resin film 1 of the present disclosure only needs to be placed in at least one location between the exterior material 3 for the energy storage device and the lid 60, and may be placed in two or more locations.

[0141] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figure 11, if the lid 60 is rectangular in plan view and the resin film 1 is placed along one side of the rectangle, the ratio of the length of the resin film to the length of that side is, for example, about 3 to 98%. Furthermore, the size of the resin film 1 in the width direction (the direction perpendicular to the length direction and thickness direction, and in the example of Figure 11, the depth direction of the paper) is, for example, about 20 to 300% of the size of the resin film 1 in the length direction, with the length direction being 100% as the base.

[0142] 6) Uses (An application in which an outer casing of an energy storage device includes an outer casing material for an energy storage device and a lid, the lid includes a lid body and a covering that covers the periphery of the lid body, and is used interposed between the lid body and the covering.) As shown in Figures 12 and 13, the resin film for the energy storage device of this disclosure can also be used interposed between the lid body 62 and the covering 61 that constitute the lid 60 described above.

[0143] In other words, as explained in the application of 5) above, in this disclosure, the energy storage device element 4 of the energy storage device 10 may be sealed by other members such as a lid 60 in addition to the energy storage device exterior material 3. The energy storage device exterior material 3 and other members such as the lid 60 constitute an exterior body 30 (exterior body for energy storage device) that seals the energy storage device element 4. As shown in Figures 12 and 13, for example, the energy storage device element may be housed inside the cylindrical energy storage device exterior material 3, and the opening may be closed with a lid 60. In Figures 12 and 13 relating to the application of 6), the lid 60 is shown to be composed of a lid body 62 and a covering 61 that covers the periphery of the lid body 62.

[0144] As described above, the lid 60 can be formed, for example, from a resin molded product, a metal molded product, or a combination thereof. In this disclosure, when the lid is described as a resin molded product, the lid is not composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the lid is a metal molded product, the lid can also function as a metal terminal, and therefore the lid can be a metal terminal. The lid may be composed of a resin material and a conductive material.

[0145] For example, in the schematic diagram shown in Figure 12, an energy storage device element is housed inside a cylindrical outer casing material 3 for the energy storage device, and the opening is closed by a resin lid 60. The lid body 62 also has a through hole into which a metal terminal 2 electrically connected to the energy storage device element 4 is inserted. In this embodiment, the energy storage device 10 consists of an outer casing material 3 and a lid 60 that seals the energy storage device element 4, and the metal terminal 2 is exposed to the outside through the through hole in the lid body 62. An adhesive film 5 can be placed between the metal terminal 2 and the lid body 62 to improve their adhesion.

[0146] Furthermore, in Figure 13, the energy storage device element, connected to the lid body 62, is housed inside the cylindrical exterior material 3 for the energy storage device, which is configured to form an opening, and the opening is closed by the lid 60. The lid body 62 also functions as a metal terminal 2. It is preferable that the lid 60 and the exterior material 3 for the energy storage device are joined by any means.

[0147] As described above, in order to improve the volumetric energy density of the energy storage device, it is preferable that the energy storage device exterior material 3 be wrapped around the energy storage device element and the cover 60 in order to reduce the dead space between the energy storage device element and the energy storage device exterior material 3.

[0148] In the application of 6), by using the resin film 1 for energy storage devices of this disclosure interposed between the lid body 62 and the covering 61, the energy storage device can be opened at a position between the lid body 62 and the covering 61 (i.e., at the position of the lid 60), and gas generated inside the energy storage device can be released to the outside.

[0149] In the application of 6) described above, the position in which the resin film 1 of the present disclosure is placed is not particularly limited as long as it is between the lid body 62 and the covering 61. For example, if the lid body 62 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the periphery of the lid body 62. Furthermore, the resin film 1 of the present disclosure only needs to be placed in at least one location between the lid body 62 and the covering 61, and may be placed in two or more locations.

[0150] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figures 12 and 13, if the lid body 62 is rectangular in plan view and the resin film 1 is placed along one side of the rectangle, the ratio of the length of the resin film to the length of that side is, for example, about 3 to 98%. Also, the width of the resin film 1) (the direction perpendicular to the length and thickness directions, and in the example of Figures 12 and 13, the depth direction of the paper) is, for example, about 20 to 300%, with the length of the resin film 1 as the base size of 100%.

[0151] Furthermore, in the applications described in 1) to 6) above, the resin film 1 may be temporarily fixed by partially heat-sealing it (for example, by using point seals).

[0152] (Pressure-sensitive adhesive layer) In the resin film 1 for energy storage devices of this disclosure, a pressure-sensitive adhesive layer may be provided so as to constitute the surface of at least one side of the resin film 1 for energy storage devices. The pressure-sensitive adhesive layer is provided partially so as to constitute the surface of the resin film 1. The pressure-sensitive adhesive layer is a layer that performs a function (temporary fixing function) of fixing the resin film 1 for energy storage devices by pressure-sensitive adhesive force at the position where the resin film 1 for energy storage devices is placed on the energy storage device 10 during the manufacturing of the energy storage device 10. By fixing the resin film 1 for energy storage devices in a predetermined position during the manufacturing of the energy storage device 10, displacement of the resin film 1 for energy storage devices during the manufacturing of the energy storage device 10 is suppressed, and the resin film 1 for energy storage devices can be placed with high positional accuracy.

[0153] From the viewpoint of suitably exhibiting the effects of the present invention, the ratio of the area of ​​the portion on which the pressure-sensitive adhesive layer is laminated to the total area of ​​one side of the resin film is preferably about 50% or less, more preferably about 40% or less, even more preferably about 30% or less, and also preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more. Preferred ranges include about 5-50%, about 5-40%, about 5-30%, about 10-50%, about 10-40%, and about 10-30%.

[0154] The position on the surface of the resin film 1 where the pressure-sensitive adhesive layer is provided is not particularly limited, as long as the pressure-sensitive adhesive layer performs its function. For example, as shown in Figure 4, the pressure-sensitive adhesive layer can be provided at one end of the resin film 1.

[0155] Furthermore, it is preferable to provide the pressure-sensitive adhesive layer in a pattern. The pattern on which the pressure-sensitive adhesive layer is formed is not particularly limited and may include dots, stripes, grids, geometric patterns (polygons such as triangles, squares, and rectangles, as well as circles, ellipses, etc.).

[0156] After the resin film 1 is placed during the manufacturing process of the energy storage device, at least a portion of the area where the pressure-sensitive adhesive layer of the resin film 1 is formed can be removed. When removing the area where the pressure-sensitive adhesive layer is formed from the resin film 1 applied to the energy storage device 10, if the resin film 1 has the pressure-sensitive adhesive layer at one end, the pressure-sensitive adhesive layer can be removed by cutting in the thickness direction at the location where the pressure-sensitive adhesive layer is formed. After the resin film 1 is applied to the energy storage device 10, the portion where the pressure-sensitive adhesive layer is formed may be removed entirely or partially.

[0157] Furthermore, when the resin film 1 is applied to the energy storage device 10 and the resin film 1 is heat-fused to the heat-fusible resin layer 35, etc., a difference in adhesive strength may occur between the resin film 1 and the heat-fusible resin layer 35, etc., depending on whether a pressure-sensitive adhesive layer is present or not. In such cases, the design can be made so that no difference in adhesive strength occurs by not placing a pressure-sensitive adhesive layer in the area where the resin film 1 and the heat-fusible resin layer 35, etc. are heat-fused. Alternatively, as described above, the design can be made so that no difference in adhesive strength occurs by completely removing the portion where the pressure-sensitive adhesive layer is formed.

[0158] Furthermore, the pressure-sensitive adhesive layer only needs to constitute and partially form the surface of at least one side of the resin film 1 (i.e., the pressure-sensitive adhesive layer only needs to perform a temporary fixing function), and the entire pressure-sensitive adhesive layer may be located on the surface of the resin film 1, or at least a part of the pressure-sensitive adhesive layer may be embedded in the underlying layer.

[0159] The material used to form the pressure-sensitive adhesive layer is not particularly limited, as long as it has pressure-sensitive adhesive properties (tackiness) and can perform the aforementioned functions of the pressure-sensitive adhesive layer. Examples of materials used to form the pressure-sensitive adhesive layer include resin compositions containing a resin and an adhesive component.

[0160] Examples of resins used in such resin compositions include resins containing a polyolefin skeleton, such as polyolefins and acid-modified polyolefins.

[0161] Examples of resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, include the same resins exemplified in the (Resin Layer A) section above.

[0162] Examples of adhesive components include rosin or its derivatives, such as rosin, hydrogenated rosin, polymerized rosin, and rosin esters; terpene resins such as α-pinene, β-pinene, and limonene; terpene phenol resins, coumarone-indene resins, styrene resins, xylene resins, phenol resins, petroleum resins, and hydrogenated petroleum resins. Furthermore, hydrogenated terpene resins, rosin resins, and petroleum resins are compatible with the elastomer phase of styrene block copolymers and are highly effective in improving adhesion to non-polar materials such as polyolefins, while xylene resins, phenol resins, and styrene resins are compatible with the styrene phase and have the effect of increasing cohesive force. For this reason, hydrogenated terpene resins, rosin resins, and petroleum resins can also be combined with xylene resins, phenol resins, and styrene resins to create adhesive components.

[0163] Furthermore, amorphous polyolefins can also be used as adhesive components. Examples of amorphous polyolefins include amorphous polypropylene, or copolymers of amorphous propylene with other α-olefins. Specific examples include propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-butene-1-ethylene terpolymer, propylene-hexene-1-octene-1-terpolymer, propylene-hexene-1-4-methylpentene-1-terpolymer, propylene-hexene-1-4-methylpentene-1-terpolymer, and polybutene-1. Among the target amorphous alpha polyolefins, those with a high content of low molecular weight components, a number average molecular weight of 20,000 or less, and a glass transition temperature of -20°C or lower are preferred.

[0164] Amorphous polyolefin is preferred as the adhesive component. Examples of commercially available amorphous polyolefins include REXtac2280 (manufactured by REXtac LLC). In a pressure-sensitive adhesive layer, for example, when REXtac2280 is used as the adhesive component and modified polyolefin is used as the resin, the content of REXtac2280 is preferably about 10 parts by mass or about 20 parts by mass per 100 parts by mass of modified polyolefin.

[0165] Other examples of adhesive components include elastomers.

[0166] The elastomer is not particularly limited as long as it is compounded with a resin and exhibits pressure-sensitive adhesion. For example, an elastomer composed of a thermoplastic resin (thermoplastic elastomer) is preferred.

[0167] Preferred elastomers include styrene-based elastomers, olefin-based elastomers, acrylic-based elastomers, silicone-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, and rubber-based elastomers. The elastomer may be used individually or in combination of two or more types.

[0168] There are no particular limitations on the type of styrene-based elastomer, but specific examples include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

[0169] Examples of olefin-based elastomers include copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene. For example, ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM) are preferred. Also, copolymers of α-olefins with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene are also examples. Furthermore, carboxy-modified nitrile rubber obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid is also an example.

[0170] Acrylic elastomers are mainly composed of acrylic acid esters, and specifically, ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc., are preferably used. In addition, glycidyl methacrylate, allyl glycidyl ether, etc., can be used as crosslinking monomers. Furthermore, copolymers with acrylonitrile or ethylene can also be used. Specifically, examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

[0171] Silicone-based elastomers primarily consist of organopolysiloxanes, and include polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers.

[0172] Urethane elastomers consist of structural units of a hard segment made of low molecular weight ethylene glycol and diisocyanate, and a soft segment made of high molecular weight (long-chain) diol and diisocyanate. Examples of high molecular weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene neopentylene adipate).

[0173] Polyester elastomers are obtained by polycondensation of a dicarboxylic acid or its derivative with a diol compound or its derivative. Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, as well as aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic kernel are substituted with methyl, ethyl, or phenyl groups, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used individually or in combination of two or more.

[0174] Specific examples of diol compounds include aliphatic and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol. Furthermore, examples include bisphenol A, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-propane, and resorcinol. These compounds can be used individually or in combination of two or more.

[0175] Examples of polyamide-based elastomers include block copolymers in which polyamide is the hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene-propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, or silicone rubber are the soft segment components.

[0176] Examples of rubber-based elastomers include polyisobutylene.

[0177] Among elastomers, styrene-based elastomers and olefin-based elastomers are preferred, with styrene-based elastomers being particularly preferred.

[0178] The content of the adhesive component in the pressure-sensitive adhesive layer is not particularly limited as long as the pressure-sensitive adhesive layer can perform the functions described above, but for example it is about 0.5% by mass or more, preferably about 1.5% by mass or more, more preferably about 3% by mass or more, and also for example it is about 80% by mass or less, preferably about 50% by mass or less, more preferably about 20% by mass or less, and preferred ranges include about 0.5 to 80% by mass, about 0.5 to 50% by mass, about 0.5 to 20% by mass, about 1.5 to 80% by mass, about 1.5 to 50% by mass, about 1.5 to 20% by mass, about 3 to 80% by mass, about 3 to 50% by mass, and about 3 to 20% by mass.

[0179] The adhesive component may be used alone or in combination of two or more types.

[0180] Furthermore, the pressure-sensitive adhesive layer can also be formed from adhesive materials such as polyurethane, polyester, polyamide, acrylic, polyvinyl acetal, polycarbonate, polyethylene, polyacrylic acid, and polymethyl methacrylate, as well as tacky materials such as phenolic resin, urea resin, and silicone resin.

[0181] The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as the pressure-sensitive adhesive layer performs the functions described above. However, from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 0.5 μm or more, more preferably about 1 μm or more, even more preferably about 1.5 μm or more, and also preferably about 40 μm or less, more preferably about 20 μm or less, and even more preferably about 10 μm or less. Preferred ranges include approximately 0.5 to 40 μm, approximately 0.5 to 20 μm, approximately 0.5 to 10 μm, approximately 1 to 40 μm, approximately 1 to 20 μm, approximately 1 to 10 μm, approximately 1.5 to 40 μm, approximately 1.5 to 20 μm, and approximately 1.5 to 10 μm.

[0182] [Energy storage devices] As described above, the energy storage device 10 of this disclosure has a structure in which the energy storage device element 4 is sealed in an outer casing 30. The energy storage device element 4 comprises at least a positive electrode, a negative electrode, and an electrolyte. In the energy storage device 10 of this disclosure, the resin film 1 is included in at least one of the following embodiments, for example: 1) to 6).

[0183] 1) An embodiment in which the heat-sealable resin layers of the exterior material for an energy storage device are interposed between the heat-sealable resin layers at the position where they are heat-sealed together. 2) Embodiments included as a heat-fusible resin layer for exterior material of energy storage device 3) An embodiment that includes an adhesive layer between the barrier layer and the heat-fusible resin layer of an exterior material for an energy storage device. 4) An embodiment that includes an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing that seals the energy storage device element. 5) The casing of the energy storage device includes an casing material for the energy storage device and a cover. A component included between the exterior material for the energy storage device and the lid. 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering.

[0184] These embodiments 1) to 6) correspond to embodiments in which the resin film 1 of the present disclosure is applied to the energy storage device 10 for the uses described in 1) to 6) above.

[0185] The energy storage device 10 is manufactured by applying the resin film 1 of this disclosure to the energy storage device 10 for the applications described in 1) to 6) above.

[0186] [Exterior material for energy storage devices 3] An example of an exterior material 3 for an energy storage device is one having a laminated structure consisting of a laminate having at least a barrier layer 33 and a heat-fusible resin layer 35 in that order. Figures 4 and 5 show an example of the cross-sectional structure of the exterior material 3 for an energy storage device, in which a base layer 31 (provided as needed), an adhesive layer 32 (provided as needed), a barrier layer 33, an adhesive layer 34 (provided as needed), and a heat-fusible resin layer 35 are laminated in this order. In the exterior material 3 for an energy storage device, the barrier layer 33 is on the outer layer side, and the heat-fusible resin layer 35 is the innermost layer. When assembling the energy storage device, the heat-fusible resin layers 35 located on the periphery of the energy storage device element 4 are brought into contact with each other and heat-fused to seal the energy storage device element 4, thereby sealing the energy storage device element 4. Figures 6 to 9 show an energy storage device 10 using an embossed type exterior material 3 for an energy storage device formed by embossing, but the exterior material 3 for an energy storage device may be an unformed pouch type. Note that pouch-type packaging includes three-sided seal, four-sided seal, and pillow-type packaging, but any type is acceptable.

[0187] The thickness of the laminate constituting the exterior material 3 for energy storage devices is not particularly limited, but from the viewpoint of cost reduction and improvement of energy density, 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 exterior material for energy storage devices, which is to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 3 for energy storage devices 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 for the laminate constituting the outer casing material 3 for the energy storage device is, for example, approximately 35-300 μm, approximately 35-250 μm, approximately 35-210 μm, approximately 35-190 μm, approximately 35-180 μm, approximately 35-155 μm, approximately 35-120 μm, approximately 45-300 μm, approximately 45-250 μm, approximately 45-210 μm, approximately 45-190 μm, approximately 45-180 μm, approximately 45-155 μm, approximately 45-120 μm, approximately 60-300 μm, approximately 60-250 μm, and 60- Examples of thicknesses include approximately 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.

[0188] Furthermore, the energy storage device exterior material 3 can be suitably applied to all-solid-state batteries. The thickness of the laminate constituting the all-solid-state battery exterior material is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, it is preferably about 10,000 μm or less, about 8,000 μm or less, or about 5,000 μm or less. From the viewpoint of maintaining the function of the all-solid-state battery exterior material, which is to protect the battery elements, it is preferably about 100 μm or more. Examples of preferred ranges include approximately 150 μm or more and approximately 200 μm or more, and examples of preferred ranges include approximately 100 to 10000 μm, approximately 100 to 8000 μm, approximately 100 to 5000 μm, approximately 150 to 10000 μm, approximately 150 to 8000 μm, approximately 150 to 5000 μm, approximately 200 to 10000 μm, approximately 200 to 8000 μm, and approximately 200 to 5000 μm, with approximately 100 to 5000 μm being particularly preferred.

[0189] (Base material layer 31) In the exterior material 3 for the energy storage device, the base layer 31 is a layer that functions as the base material for the exterior material of the energy storage device and is the layer that forms the outermost layer.

[0190] The material forming the base layer 31 is not particularly limited, as long as it possesses insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate have excellent electrolyte resistance and are less prone to whitening when exposed to electrolyte, making them suitable for use as a material for forming the base layer 31. Polyamide films also have excellent stretchability, which can prevent whitening due to resin cracking of the base layer 31 during molding, making them suitable for use as a material for forming the base layer 31.

[0191] The base layer 31 may be formed from a uniaxially or biaxially stretched resin film, or from an unstretched resin film. Among these, uniaxially or biaxially stretched resin films, and especially biaxially stretched resin films, are suitable for use as the base layer 31 because their heat resistance is improved by oriented crystallization.

[0192] Among these, nylon, polyester, and more preferably biaxially oriented nylon and biaxially oriented polyester are used as the resin film forming the base layer 31. Furthermore, since all-solid-state batteries are often sealed at high temperatures of 200°C or higher to achieve a service temperature of 150°C or higher, biaxially oriented polyester is the most suitable.

[0193] The base layer 31 can also be constructed by laminating resin films of different materials to improve pinhole resistance and insulation when used as packaging for energy storage devices. Specifically, examples include a multilayer structure in which polyester film and nylon film are laminated, or a multilayer structure in which biaxially oriented polyester and biaxially oriented nylon are laminated. When the base layer 31 is a multilayer structure, each resin film may be bonded via an adhesive, or it may be laminated directly without an adhesive. When bonding without an adhesive, examples include bonding in a thermally molten state such as co-extrusion, sand lamination, or thermal lamination. For the above high-temperature sealing, it is desirable that at least the outermost layer be biaxially oriented polyester.

[0194] Furthermore, the base layer 31 may be made friction-reducing to improve moldability. When the base layer 31 is made friction-reducing, there are no particular restrictions on the coefficient of friction of its surface, but for example, it may be 1.0 or less. Examples of methods for making the base layer 31 friction-reducing include mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

[0195] The thickness of the substrate layer 31 can be, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[0196] (Adhesive layer 32) In the exterior material 3 for the energy storage device, the adhesive layer 32 is a layer that is placed on the base material layer 31 as needed in order to provide adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0197] The adhesive layer 32 is formed by an adhesive capable of bonding the base layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited and may be a chemical reaction type, solvent evaporation type, thermal melting type, hot pressure type, etc.

[0198] As for the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing suppression effect, and heat degradation suppression effect during heat sealing, and effectively suppressing the occurrence of delamination by suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33, two-component curable polyurethane adhesives; polyamide, polyester, or blended resins of these with modified polyolefins are preferred.

[0199] Furthermore, the adhesive layer 32 may be multilayered with different adhesive components. When the adhesive layer 32 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material layer 31 side, and an adhesive component with excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side. Specifically, when the adhesive layer 32 is multilayered with different adhesive components, preferred adhesive components arranged on the barrier layer 33 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyester and acid-modified polyolefins, and resins containing copolymerized polyesters.

[0200] The thickness of the adhesive layer 32 can be, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[0201] (Barrier layer 33) In the exterior material for energy storage devices, the barrier layer 33 is a layer that at least prevents moisture from entering.

[0202] Examples of barrier layers 33 include metal foils, vapor-deposited films, and resin layers that have 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 the barrier layer 33. Multiple layers of barrier layers 33 may be provided. It is preferable that the barrier layer 33 includes a layer made of a metal material. Specifically, examples of metal materials constituting the barrier layer 33 include aluminum alloys, 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.

[0203] In the barrier layer 33, 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. The barrier layer 33 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) and is not recycled material.

[0204] From the viewpoint of improving the formability or conformability of the exterior material 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 or conformability, it is more preferably an aluminum alloy foil containing iron. In an 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, an exterior material for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material 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.

[0205] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0206] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0207] In the case of metal foil, the thickness of the barrier layer 33 should at least function as a barrier layer that prevents moisture from penetrating, for example, about 9 to 200 μm. The thickness of the barrier layer 33 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. Also, the thickness of the barrier layer 33 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 33 include 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 33 is made of aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, from the viewpoint of providing high formability and high rigidity to the exterior material 10 for the energy storage device, the thickness of the barrier layer 33 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 exterior material 10 for energy storage devices facilitates deep drawing, which can contribute to increasing the capacity of energy storage devices. Furthermore, while increasing the capacity of an energy storage device increases its weight, the increased rigidity of the exterior material 10 for energy storage devices contributes to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 33 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.

[0208] Furthermore, if the barrier layer 33 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 33 may 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 33 has a corrosion-resistant coating, the barrier layer 33 includes the corrosion-resistant coating.

[0209] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of exterior materials for energy storage devices. It also prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolyte and water, 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.

[0210] 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 phosphate, titanium phosphate, zirconium phosphate, and zinc phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphates 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. Various solvents can be used as the treatment solution, 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.

[0211] [ka]

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] 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 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms substituted with one hydroxy group 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, 4-hydroxybutyl group, etc. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating unit represented by General Formulas (1) to (4) is preferably about 500 to 1,000,000, more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating unit represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 ). The aminated phenol polymer is used alone or in combination of two or more.

[0216] Another example of a corrosion-resistant coating 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 coating 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.

[0217] 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.

[0218] 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.

[0219] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0220] The amount of corrosion-resistant film to be formed on the surface of the barrier layer 33 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 33 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

[0221] 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 - Peaks originating from at least one of the following are detected.

[0222] 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 70-200°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.

[0223] (adhesive layer 34) In the exterior material 3 for energy storage devices, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as needed in order to firmly bond the heat-fusible resin layer 35. As described above, in the application of 3) (an application in which it is used as an adhesive layer between the barrier layer and the heat-fusible resin layer of the exterior material for energy storage devices), the resin film 1 for energy storage devices of this disclosure is used as the adhesive layer 34 of the exterior material 3 for energy storage devices.

[0224] Furthermore, the adhesive layer 34 can be formed by an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include adhesives composed of a polyester polyol compound and an alicyclic isocyanate compound.

[0225] The thickness of the adhesive layer 34 can be, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[0226] (Thermal adhesive resin layer 35) In the exterior material 3 for energy storage devices, the heat-sealable resin layer 35 is the innermost layer and is a layer that seals the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device. As described above, in the application of 2) (an application in which it is used as a heat-sealable resin layer for the exterior material for energy storage devices), the resin film 1 for energy storage devices of this disclosure is used as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices.

[0227] The resin components used in the heat-fusible resin layer 35 are not particularly limited as long as they are heat-fusible, but for example, in the case of exterior materials for energy storage devices, polyolefins and cyclic polyolefins are generally used.

[0228] Specifically, the polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0229] The 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, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, etc. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0230] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blends thereof; more preferably, polyethylene, polypropylene, copolymers of ethylene and norbornene, and blends of two or more of these.

[0231] The heat-fusible resin layer 35 may be formed by a single resin component, or by a blended polymer combining two or more resin components. Furthermore, the heat-fusible resin layer 35 may be formed as a single layer, or it may be formed as two or more layers made of the same or different resin components.

[0232] Furthermore, the thickness of the heat-sealable resin layer 35 is not particularly limited, but is preferably about 2 to 2000 μm, more preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0233] Furthermore, the resin film 1 of this disclosure can be particularly suitably applied to exterior materials for all-solid-state batteries, and the melting point of the heat-sealable resin layer 35 of the exterior material for all-solid-state batteries is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C.

[0234] Furthermore, examples of resins included in the heat-sealable resin layer 35 of the exterior material for all-solid-state batteries include polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the exterior material for all-solid-state batteries, the heat-sealable resin layer 35 is preferably formed from a polybutylene terephthalate film. In addition, because the heat-sealable resin layer 35 is formed from a polybutylene terephthalate film, it also has excellent adhesion to the resin layer A of the resin film 1 of this disclosure. The polybutylene terephthalate film forming the heat-sealable resin layer 35 may be formed by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34, or the resin forming the polybutylene terephthalate film may be melt-extruded to form a film and then laminated with the adhesive layer 34.

[0235] The polybutylene terephthalate film may be an stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and an unstretched polybutylene terephthalate film is preferred.

[0236] The polybutylene terephthalate film is preferably composed of at least one of homopolybutylene terephthalate and copolymerized polybutylene terephthalate.

[0237] The heat-sealable resin layer 35 may be formed as a single layer, or it may be formed as two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed as two or more layers, at least one layer is preferably made of polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the exterior material for the all-solid-state battery. Furthermore, the layer that adheres to the adhesive layer 34 is preferably made of polybutylene terephthalate film. When the heat-sealable resin layer 35 is formed as two or more layers, the layer not made of polybutylene terephthalate film may be made of, for example, polyolefins such as polypropylene and polyethylene, or acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments compared to polybutylene terephthalate or polyethylene terephthalate, it is preferable that the heat-sealable resin layer 35 is composed solely of a polybutylene terephthalate film such as a homo-PBT layer or a copolymer PBT layer, or solely of polyethylene terephthalate such as a PET layer.

[0238] The energy storage device of this disclosure is an energy storage device such as a battery (including capacitors, capacitors, etc.). The energy storage device of this disclosure may be either a primary battery or a secondary battery, but is preferably used as a secondary battery. The type of secondary battery is not particularly limited and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state 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, capacitors, etc. Among these secondary batteries, the energy storage device of this disclosure is preferably a lithium-ion battery, a lithium-ion polymer battery, or an all-solid-state battery. [Examples]

[0239] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0240] <Resin film for energy storage devices> (Example 1) Random polypropylene films (melting peak temperature 125°C, thickness 30 μm) whose half-width (FWHM) and cruntosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1 were used as resin films for energy storage devices. The resin films for energy storage devices were manufactured by extruding random polypropylene (melting peak temperature 125°C) to a thickness of 30 μm using an extruder and a T-die casting apparatus.

[0241] The resin films in Examples 1 to 13 were selected by measuring the full width at half maximum (FWHM) and crurtosis values ​​using random polypropylene with a molecular weight distribution of 5.0 or less, as described above.

[0242] (Example 2) Random polypropylene films (melting peak temperature 135°C, thickness 30 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1 were used as resin films for energy storage devices. The resin films for energy storage devices were manufactured by extruding random polypropylene (melting peak temperature 135°C) to a thickness of 30 μm using an extruder and a T-die casting apparatus.

[0243] (Example 3) A random polypropylene film (melting peak temperature 125°C, thickness 40 μm) whose full width at half maximum (FWHM) measured by differential scanning calorimetry (see below) satisfies the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 140°C, thickness 5 μm) were laminated on both sides to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. An intermediate polypropylene layer (random polypropylene, melting peak temperature 125°C, thickness 40 μm) was extruded on both sides as resin layer A, and polypropylene (random polypropylene, melting peak temperature 140°C) was extruded as resin layer B to a thickness of 5 μm, resulting in a three-layer structure of random PP (melting peak temperature 140°C, 5 μm) / random PP (melting peak temperature 125°C, 40 μm) / random PP (melting peak temperature 140°C, 5 μm).

[0244] (Example 4) A linear low-density polyethylene film (melting peak temperature 100°C, thickness 40 μm) whose full width at half maximum (FWHM) measured by differential scanning calorimetry (FWHM) and crurtosis value of the melting peak satisfy the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 135°C, thickness 5 μm) were laminated on both sides to form a resin film for energy storage devices. The crurtosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (FWHM) and crurtosis value of the melting peak satisfy the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. An intermediate layer of polyethylene (linear low-density polyethylene, melting peak temperature 100°C, thickness 30 μm) was extruded on both sides as resin layer A, and polypropylene (random polypropylene, melting peak temperature 135°C) was extruded as resin layer B to a thickness of 5 μm, resulting in a three-layer structure of random PP (melting peak temperature 135°C, 5 μm) / LLDPE (melting peak temperature 100°C, 40 μm) / random PP (melting peak temperature 135°C, 5 μm).

[0245] (Example 5) A random polypropylene film (melting peak temperature 125 °C, thickness 40 μm) whose half-width measured by <Measurement of half-width of melting peak (°C) and kurtosis value by differential scanning calorimetry> described later satisfies the values in Table 1 was used as resin layer A, and maleic anhydride-modified random polypropylene films (melting peak temperature 140 °C, thickness 5 μm) were laminated on both sides to obtain a resin film for a power storage device. The kurtosis value of the resin film for a power storage device measured by <Measurement of half-width of melting peak (°C) and kurtosis value by differential scanning calorimetry> described later satisfies the values in Table 1. The resin film for a power storage device was produced in a three-layer structure of random PPa (melting peak temperature 140 °C, 5 μm) / random PP (melting peak temperature 125 °C, 40 μm) / random PPa (melting peak temperature 140 °C, 5 μm) by extruding a carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 °C) with a thickness of 5 μm on both sides of intermediate layer polypropylene (random polypropylene, melting peak temperature 125 °C) as resin layer A using an extruder and a T-die casting device.

[0246] (Example 6) A linear low-density polyethylene film (melting peak temperature: 117 °C, thickness: 20 μm) whose half-width measured by <Measurement of the half-width (°C) of the melting peak and the kurtosis value by differential scanning calorimetry> described below satisfies the values in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature: 135 °C, thickness: 5 μm) were laminated on both sides to obtain a resin film for a power storage device. The kurtosis value of the resin film for a power storage device measured by <Measurement of the half-width (°C) of the melting peak and the kurtosis value by differential scanning calorimetry> described below satisfies the values in Table 1. The resin film for a power storage device was produced in a three-layer structure of random PP (melting peak temperature: 135 °C, 5 μm) / LLDPE (melting peak temperature: 117 °C, 20 μm) / random PP (melting peak temperature: 135 °C, 5 μm) by extruding polypropylene (random polypropylene, melting peak temperature: 135 °C) with a thickness of 5 μm on both sides of intermediate layer polyethylene (linear low-density polyethylene, melting peak temperature: 117 °C, thickness: 20 μm) as resin layer A using an extruder and a T-die casting device.

[0247] (Example 7) A linear low-density polyethylene film (melting peak temperature: 100 °C, thickness: 40 μm) whose half-width measured by <Measurement of the half-width (°C) of the melting peak and the kurtosis value by differential scanning calorimetry> described below satisfies the values in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature: 135 °C, thickness: 5 μm) were laminated on both sides to obtain a resin film for a power storage device. The kurtosis value of the resin film for a power storage device measured by <Measurement of the half-width (°C) of the melting peak and the kurtosis value by differential scanning calorimetry> described below satisfies the values in Table 1. The resin film for a power storage device in Example 7 was produced in the same manner as in Example 4, and the resin film for a power storage device was used as the heat-sealable resin layer of the exterior material for a power storage device.

[0248] (Example 8) A random polypropylene film (melting peak temperature 125°C, thickness 30μm) whose full width at half maximum (FWHM) measured by differential scanning calorimetry (see below) satisfies the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 140°C, thickness 30μm) were laminated on both sides to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. An intermediate polyethylene layer (random polypropylene, melting peak temperature 125°C, thickness 30 μm) was extruded on both sides as resin layer A, and polypropylene (random polypropylene, melting peak temperature 140°C) was extruded as resin layer B to a thickness of 5 μm, resulting in a three-layer structure of random PP (melting peak temperature 140°C, 30 μm) / random PP (melting peak temperature 125°C, 30 μm) / random PP (melting peak temperature 140°C, 30 μm).

[0249] (Example 9) A random polypropylene-polyethylene blend film (melting peak temperature 107°C, thickness 20 μm) whose full width at half maximum (FWHM) measured by differential scanning calorimetry (see below) satisfies the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 127°C, thickness 5 μm) were laminated on both sides to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. An intermediate layer (random polypropylene-polyethylene blend layer, melting peak temperature 107°C, thickness 20 μm) was extruded on both sides as resin layer A, and polypropylene (random polypropylene, melting peak temperature 127°C) was extruded as resin layer B to a thickness of 5 μm, resulting in a three-layer structure of random PP (melting peak temperature 127°C, 5 μm) / random PP-PE (melting peak temperature 107°C, 20 μm) / random PP (melting peak temperature 127°C, 5 μm).

[0250] (Example 10) Random polypropylene films (melting peak temperature 128°C, thickness 30 μm) whose half-width (FWHM) and cruntosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1 were used as resin films for energy storage devices. The resin films for energy storage devices were manufactured by extruding random polypropylene (melting peak temperature 128°C) to a thickness of 30 μm using an extruder and a T-die casting apparatus.

[0251] (Example 11) Maleic anhydride-modified polypropylene (melting peak temperature 125°C, thickness 30 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1, was used as the resin film for the energy storage device. The resin film for the energy storage device in Example 11 was manufactured as an adhesive layer located between the barrier layer and the heat-fusible resin layer of the exterior material for the energy storage device, together with random polypropylene (melting peak temperature 140°C) that forms a heat-fusible resin layer (thickness 10 μm) (opening test 3 described below).

[0252] (Example 12) A random polypropylene film (melting peak temperature 125°C, thickness 30 μm) whose half-width (°C) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1, was used as the resin film for the energy storage device. The resin film for the energy storage device in Example 12 was manufactured in the same manner as in Example 1 and is used by being placed between the exterior material and the lid of the energy storage device.

[0253] (Example 13) A linear low-density polyethylene film (melting peak temperature 95°C, thickness 40 μm) whose half-width (FWHM) measured by differential scanning calorimetry (see below) satisfies the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 135°C, thickness 5 μm) were laminated on both sides to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the value in Table 1. The resin film for the energy storage device was manufactured using an extruder and a T-die casting apparatus. An intermediate layer (linear low-density polyethylene layer, melting peak temperature 95°C, thickness 40 μm) was extruded on both sides as resin layer A, and polypropylene (random polypropylene, melting peak temperature 135°C) was extruded as resin layer B to a thickness of 5 μm, resulting in a three-layer structure of random PP (melting peak temperature 135°C, 5 μm) / LLDPE (melting peak temperature 95°C, 40 μm) / random PP (melting peak temperature 135°C, 5 μm). The resin film of Example 13 is used by placing it between the lid body and the covering of the outer casing of the energy storage device.

[0254] (Comparative Example 1) Random polypropylene films (melting peak temperature 126°C, thickness 30 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1 were used as resin films for energy storage devices. The resin films for energy storage devices were manufactured by extruding random polypropylene (melting peak temperature 126°C) to a thickness of 30 μm using an extruder and a T-die casting apparatus.

[0255] (Comparative Example 2) A random polypropylene film (melting peak temperature 140°C, thickness 40 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1, was used as resin layer A, and a maleic anhydride-modified polypropylene film (melting peak temperature 140°C, thickness 40 μm) was laminated on one side to form a resin film for energy storage devices. The crurtosis value of the resin film for energy storage devices, measured by differential scanning calorimetry as described below, satisfies the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. An intermediate polypropylene layer (random polypropylene, melting peak temperature 140°C, thickness 40 μm) was used as resin layer A, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 40 μm as resin layer B, resulting in a two-layer structure of random PPa (140°C, 40 μm) / random PP (140°C, 40 μm).

[0256] (Comparative Example 3) This is an example where the resin film for the energy storage device was not used in the opening test 1 described later.

[0257] (Comparative Example 4) A random polypropylene film (melting peak temperature 125°C, thickness 10 μm) whose full width at half maximum (FWHM) measured by differential scanning calorimetry (see below) satisfies the value in Table 1 was used as resin layer A, and random polypropylene films (melting peak temperature 140°C, thickness 30 μm) were laminated on both sides to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the value in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. A 3-layer structure was created by extruding a 30μm thick layer of polypropylene (random polypropylene, melting peak temperature 140℃) as resin layer A on both sides of an intermediate polypropylene layer (random polypropylene, melting peak temperature 125℃, thickness 10μm) as resin layer A, and a 30μm thick layer of polypropylene (random polypropylene, melting peak temperature 140℃, thickness 140℃) as resin layer B.

[0258] (Comparative Example 5) A polypropylene film (melting peak temperature 160°C, thickness 30 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1 was used as the resin film for the energy storage device. The resin film for the energy storage device in Comparative Example 5 was manufactured as an adhesive layer located between the barrier layer and the heat-fusible resin layer of the exterior material for the energy storage device, together with acid-modified polypropylene (melting peak temperature 140°C) (opening test 3 described below).

[0259] (Comparative Example 6) Two maleic anhydride-modified random polypropylene films (melting peak temperature 144°C, thickness 44 μm), whose half-width (FWHM) measured by differential scanning calorimetry (see below) satisfies the values ​​in Table 1, were used as resin layer A. A polyethylene naphthalate film (melting peak temperature 260°C, thickness 12 μm) was laminated between these layers to form a resin film for energy storage devices. The crustosis value of the resin film for energy storage devices, measured by differential scanning calorimetry (see below) satisfies the values ​​in Table 1. The resin film for energy storage devices was manufactured using an extruder and a T-die casting apparatus. A 12μm thick PEN film with an anchor coating was used as the base layer. On both sides of this PEN film, a 44μm thick layer of carbon black-containing maleic anhydride-modified polypropylene (PPa layer, peak melting temperature 140℃) was extruded as an adhesive film for bonding metal terminals. The resulting structure was a three-layer configuration of random PPa (140℃, 44μm) / PEN (260℃, 12μm) / random PPa (140℃, 44μm).

[0260] (Comparative Example 7) A random polypropylene film (melting peak temperature 140°C, thickness 40 μm) whose half-width (FWHM) and crurtosis values, measured by differential scanning calorimetry as described below, satisfy the values ​​in Table 1, was used as resin layer A, and a maleic anhydride-modified polypropylene film (melting peak temperature 140°C, thickness 40 μm) was laminated on one side to form a resin film for energy storage devices. The crurtosis value of the resin film for energy storage devices, measured by differential scanning calorimetry as described below, satisfies the value in Table 1. The resin film for energy storage devices of Comparative Example 7 was manufactured in the same manner as Comparative Example 2 and is used by being placed between the exterior material and the lid of the energy storage device.

[0261] (Comparative Example 8) The half-width and kurtosis value measured by <Measurement of the half-width (°C) of the melting peak and kurtosis value by differential scanning calorimetry> described below satisfy the values in Table 1. A random polypropylene film (melting peak temperature: 140°C, thickness: 40 μm) was used as the resin layer A, and an anhydrous maleic acid-modified polypropylene film (melting peak temperature: 140°C, thickness: 40 μm) was laminated on one side to obtain a resin film for a power storage device. The kurtosis value measured by <Measurement of the half-width (°C) of the melting peak and kurtosis value by differential scanning calorimetry> described below for the resin film for a power storage device satisfies the values in Table 1. The resin film for a power storage device of Comparative Example 8 was manufactured in the same manner as Comparative Example 2 and is disposed and used between the lid body and the covering body of the exterior body for a power storage device.

[0262] <Measurement of the melting peak temperature> The melting peak temperature of the measurement sample (resin film) was measured in accordance with the provisions of JIS K7121:2012 (Method for Measuring the Transition Temperature of Plastics (Addendum 1 to JIS K7121:1987)). The measurement was performed using a differential scanning calorimeter. The measurement sample was held at 0°C for 15 minutes, then heated from 0°C to 210°C at a heating rate of 10°C / min to measure the first melting peak temperature P (°C). After that, it was held at 210°C for 10 minutes. Next, it was cooled from 210°C to 0°C at a cooling rate of 10°C / min and held for 15 minutes. Further, it was heated from 0°C to 210°C at a heating rate of 10°C / min to measure the second melting peak temperature Q (°C). The flow rate of nitrogen gas was set to 50 ml / min. By the above procedure, the first measured melting peak temperature P (°C) and the second measured melting peak temperature Q (°C) were obtained, and the first measured melting peak temperature was taken as the melting peak temperature. When measuring a sample with a high melting peak temperature, the range from 0°C to 500°C is measured at the same heating rate.

[0263] <Measurement of the half-width (°C) of the melting peak and kurtosis value by differential scanning calorimetry> For each example and comparative example, DSC curves were obtained for resin layer A of the resin film by differential scanning calorimetry using the following procedure. The full width at half maximum (°C) of melting peaks with a peak height of 0.3 or higher was measured using the following procedure, with the height of the melting peak with the maximum peak height set to 1.0.

[0264] (procedure) Differential scanning calorimetry (DSC) curves are obtained using a differential scanning calorimetry system (Hitachi High-Tech Science DSC7000X) with a sample weight of approximately 5 mg under a nitrogen atmosphere. The sample is heated from 0°C to 210°C at a heating rate of 10°C / min. In the DSC curve obtained from the first heating cycle, a straight line connecting the 40°C point and the 200°C point on the DSC curve is used as the baseline. A line is drawn parallel to the baseline and passing through half the height of the maximum height of the DSC curve. From this line, the line segments contained within the region enclosed by the DSC curve and the baseline are extracted, and the temperatures at the high-temperature and low-temperature endpoints of the line segments are determined. The half-width (°C) is calculated by subtracting the low-temperature end from the high-temperature end. If there are multiple line segments, the peak height of the melting peak with the highest peak height is set to 1.0. For all line segments with a peak height of 0.3 or more, the temperature at the endpoints is extracted, and the value obtained by subtracting the temperature on the lower side from the temperature on the higher side is calculated. The sum of these values ​​is taken as the full width at half maximum of the DSC curve. In addition, the kurtosis is calculated for the melting peaks of the obtained DSC curve. Here, kurtosis is defined by subtracting 3 from the fourth-order standardized moment so that the kurtosis of the normal distribution is 0. The kurtosis is calculated using the Kurtosis function from the Python scipy library. The measurement is performed three times using the same method, and the average value is adopted. If the resin film for the energy storage device is not a single layer, the layer structure is confirmed by observing the cross-section of the film, and then 5 mg or more of resin layer A is scraped off using an ultramicrotome to obtain the DSC curve of resin layer A.

[0265] The measurement results for the full width at half maximum (°C) of the melting peak and the crustosis value are shown in Table 1, respectively.

[0266] <Measurement of sealing strength A and B of resin film> The seal strengths A and B (N / 15mm) of the resin film for energy storage devices are measured according to the application in which the resin film for energy storage devices is used (as described above). Furthermore, the temperatures A and B used when measuring seal strengths A and B were determined by performing the following opening tests 1-5, according to the application.

[0267] (Opening Test 1) When a resin film for energy storage devices is used to interpose between heat-fusible resin layers at a location where the heat-fusible resin layers of the exterior material for energy storage devices are heat-fussed together (see Application 1 above), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of Opening Test 1 below.

[0268] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) Prepare one casing material for an energy storage device (8cm wide x 19cm high) with a total thickness of 153μm, consisting of layers with a melting peak temperature of 140℃ and a thickness of 40μm. Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device should be 3cm wide x 1.5cm high. Position the casing material and the resin film for the energy storage device so that their horizontal and vertical dimensions match. More specifically, horizontally, the center of the casing material and the resin film for the energy storage device should match. The components are positioned to align, and vertically, the 3cm long side of the resin film for the energy storage device is aligned with the 8cm short side of the outer casing material for the energy storage device, which is the vertical bottom edge. Next, the short side and two long sides of the resin film on the outer casing material for the energy storage device are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample, and it is placed in an oven. Air is blown into the test sample, and the internal pressure is maintained at a constant level once it reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until it reaches 150°C. The opening temperature when the test sample is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0269] (Measurement of seal strength A and B at temperatures A and B determined in opening test 1) The sealing strengths A and B of the resin film for energy storage devices were measured at temperatures A and B determined in opening test 1 using the following procedure. The results are shown in Table 1.

[0270] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) An exterior material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers of 40 μm each (with a melting peak temperature of 140°C) in that order, and it is cut to a size of 60 mm (Z direction) x 150 mm (X direction). The exterior material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and an energy storage device resin film (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between them. In this state, a laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (where both sides of the energy storage device resin film are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the energy storage device resin film is sandwiched between the heat-sealable resin layers.

[0271] For the obtained test specimens, the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature -20°C) shall be measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at each measurement environment temperature, one exterior material for the energy storage device and the opposite exterior material for the energy storage device are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance is 50 mm), and the seal strength (N / 15 mm) at each temperature is measured.

[0272] (Opening Test 2) When the resin film for energy storage devices of this disclosure is used as an adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing that seals the energy storage device element (see Application 4 above), the temperatures A and B used to measure the seal strengths A and B were determined by the procedure of the following opening test 2.

[0273] (procedure) (Fabrication of resin films for energy storage devices with metal terminals) A surface-treated metal terminal is fabricated by baking a 400μm thick x TD15mm x MD55mm aluminum alloy foil to create a metal terminal. Two sheets of adhesive film for metal terminals, which is a resin film for energy storage devices, are cut to a size of TD15mm x MD30mm. A resin film for energy storage devices with metal terminals is prepared, consisting of an adhesive film for metal terminals / metal terminal / adhesive film for metal terminals stacked in that order (placed so that the center of the MD direction of the metal terminal and the center of the MD direction of the adhesive film for metal terminals coincide). A polytetrafluoroethylene (PTFE film, thickness 100μm) is placed on top of the laminate (covering the surface of the adhesive film for metal terminals with the PTFE film), and the laminate is placed on a press machine heated to 200°C (resin layer A is on the hot plate side), and a silicone sponge sheet is placed on top, and the press is left undisturbed for 16 seconds at a pressure of 0.25MPa to heat the adhesive film. The laminate is then allowed to cool naturally to 25°C.

[0274] Prepare one 153 μm thick outer casing material for an energy storage device (8 cm wide x 19 cm high) with the following layers laminated in this order: base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm). Fold the outer casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11 mm hole in one place on one side (exactly in the center of the 8 cm wide x 9.5 cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during opening test 2. Schematic diagrams are shown in Figures 6 and 7. As shown in the figure, at the position on the short side of the peripheral portion 3a where the heat-fusible resin layers of the exterior material for the energy storage device are heat-fusible together, a resin film for the energy storage device with metal terminals is placed between the heat-fusible resin layers. Furthermore, the resin film for the energy storage device is positioned so that its horizontal (z-direction) and vertical (x-direction) orientations coincide with those of the exterior material for the energy storage device. More specifically, in the horizontal (z-direction), the resin film for the energy storage device is positioned so that the center positions of the exterior material for the energy storage device and the resin film for the energy storage device with metal terminals coincide, and in the vertical (x-direction) In this process, the 3cm long side of the resin film for the energy storage device is positioned so that it aligns with the 8cm short side of the outer casing material for the energy storage device, which is the bottom edge in the vertical (x) direction. Next, the short side of the outer casing material for the energy storage device on which the resin film for the energy storage device is positioned is heat-sealed under the conditions of a pressure of 0.5MPa, a temperature of 200℃, 6 seconds, and a seal width of 7mm, and the two long sides are heat-sealed under the conditions of a pressure of 0.5MPa, a temperature of 190℃, 3 seconds, and a seal width of 7mm. At this time, the resin film for the energy storage device Both sides of the sheet are heat-sealed to a heat-sealable resin layer. A thermocouple is attached to the test sample and placed in an oven. A φ5 mm tube is attached to the fixture set up above, ensuring no air leaks. Air is introduced into the sample through the tube and pressurized to 0.1 MPa. With the pressure at 0.1 MPa, the test sample was heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reached 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0275] (Measurement of seal strength A and B at temperatures A and B determined in opening test 2) The seal strengths A and B of the resin film for energy storage devices were measured at temperatures A and B determined in opening test 2 using the following procedure. The results are shown in Table 1.

[0276] (procedure) (Seal strength measurement) The same exterior material for energy storage devices as in Opening Test 1 is used. The exterior material for energy storage devices is cut to a size of 60 mm in the MD direction and 150 mm in the TD direction. The exterior material is then folded in half with the heat-sealable resin layer facing inward, and the metal terminal with resin film obtained above is sandwiched between the folds. In this state, a laminate is obtained by heat-sealing it at 200°C × 0.5 MPa × 6 seconds using a sealing machine with an upper metal head and a lower rubber head. The obtained laminate is cut, and a 15 mm strip-shaped test piece (one side of each of the two resin films for energy storage devices, which are placed on both sides of the metal terminal, is heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film for energy storage devices is sandwiched between the heat-sealable resin layers of the exterior material for energy storage devices) is obtained. The seal strength of the obtained test piece at temperatures A and B is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at temperatures A and B, one outer casing material and the opposite outer casing material are chucked and pulled at a speed of 300 mm / min with a peel angle of 180° (chuck distance of 50 mm), and the seal strength A (N / 15 mm) at temperature A and the seal strength B (N / 15 mm) at temperature B are measured. A thermocouple is attached to the test piece, and the test piece itself is heated to temperature A or B, held for 1 minute, and then the pulling is started.

[0277] (Opening Test 3) When the resin film for energy storage devices of this disclosure is used as a heat-sealable resin layer for an exterior material for an energy storage device (see Use 2 above), or as an adhesive layer between the barrier layer and the heat-sealable resin layer for an exterior material for an energy storage device (see Use 3 above), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 3.

[0278] (procedure) A biaxially oriented PET film (12 μm thick) and a biaxially oriented nylon film (3 μm thick) are laminated in this order as base layers using a dry lamination method. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021 H-O, 40 μm thick) with corrosion-resistant coatings formed on both sides is laminated using a dry lamination method. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of the PET film to form an adhesive layer (3 μm thick after curing) on ​​the PET film. Next, the biaxially oriented nylon film is laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of the aluminum foil with corrosion-resistant coatings formed on both sides to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Next, the adhesive layer on the aluminum foil and the PET film / nylon film laminate are laminated in a direction in which the nylon film is in contact with the aluminum foil, and then an aging treatment is performed to create a laminate of a base layer / adhesive layer / barrier layer.

[0279] Next, in the case where "the resin film for energy storage devices of this disclosure is used as a heat-sealable resin layer for an exterior material for energy storage devices (see Application 2 above))", a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, the resin film for energy storage devices is laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the obtained laminate is aged and heated to obtain an exterior material for energy storage devices (total thickness 123 μm) in which a biaxially oriented PET film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (3 μm) / heat-sealable resin layer (50 μm) are laminated in this order.

[0280] On the other hand, when the resin film for energy storage devices of this disclosure is "used as an adhesive layer between the barrier layer and the heat-fusible resin layer of an exterior material for energy storage devices (see Application 3 above))", the adhesive layer / heat-fusible resin layer is laminated on top of the barrier layer of each laminate obtained above by co-extruding a resin that forms the adhesive layer (30 μm thick) as a resin film for energy storage devices and random polypropylene (peak melting temperature 140°C) that forms the heat-fusible resin layer (10 μm thick) on top of the barrier layer of each laminate obtained above. Next, the obtained laminate is aged and heated to obtain an exterior material for energy storage devices (total thickness 113 μm) in which a biaxially oriented PET film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (30 μm) / heat-fusible resin layer (10 μm) are laminated in this order.

[0281] Following the above procedure, one casing material for the energy storage device is prepared. The casing material for the energy storage device is folded in half so that the heat-sealable resin layer is on the inside, and a φ11 mm hole is made in one place on one side (exactly in the center of the rectangle measuring 8 cm wide x 9.5 cm high). A jig for installing a tube to supply air into the sample during opening test 3 is attached to the position of the hole. As shown in the schematic diagrams of Figures 6 and 7, the short side and two long sides of the test piece, which is the casing material for the energy storage device, are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in the oven, and a φ5 mm tube is attached to the jig installed above so as not to leak air. Air is supplied into the sample through the tube and the pressure is increased to 0.1 MPa. With the pressure increased to 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature B (°C) is defined as temperature A - 20°C.

[0282] (Measurement of seal strength A and B at temperatures A and B determined in opening test 3) The sealing strengths A and B of the resin film for energy storage devices were measured at temperatures A and B determined in opening test 3 using the following procedure. The results are shown in Table 1.

[0283] (procedure) After cutting the exterior material for the energy storage device obtained by the above procedure (a total thickness of 113 μm) consisting of a biaxially oriented PET film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (30 μm) / heat-sealable resin layer (10 μm) laminated in this order), into a size of 60 mm in the MD direction and 150 mm in the TD direction, the exterior material for the energy storage device is folded in half with the heat-sealable resin layer facing inward. In this state, the heat-sealable resin layers of the exterior material for the energy storage device are heat-sealed together using a heat sealing machine with 7 mm wide upper and lower metal heads at a temperature of 190 °C, a surface pressure of 0.5 MPa, and for 3 seconds to obtain a laminate. The obtained laminate is cut to obtain 15 mm strip-shaped test pieces. For the obtained test specimens, the seal strength at temperatures A and B is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at temperatures A and B, one exterior material for a power storage device and the opposite exterior material for a power storage device are chucked at a speed of 300 mm / min and pulled at a peel angle of 180° (chuck distance is 50 mm), and the seal strength A (N / 15 mm) at temperature A and the seal strength B (N / 15 mm) at temperature B are measured.

[0284] (Opening Test 4) When the resin film for energy storage devices of this disclosure is used interposed between the exterior material and the lid of the energy storage device (see Application 5 above), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 4.

[0285] (procedure) Prepare one 153μm thick exterior material for an energy storage device (360mm in the MD direction x 180mm in the TD direction), with the following layers stacked in this order: base layer (PET (thickness 12μm) / adhesive (thickness 3μm) / nylon (thickness 15μm) / adhesive layer (thickness 3μm) / barrier layer (aluminum alloy foil, thickness 40μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140℃, thickness 40μm). Wrap the exterior material around a dummy cell (aluminum metal block) measuring 100mm (vertical) x 140mm (horizontal) x 30mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the exterior material for the energy storage device faces the block. Covers 60 (100mm (vertical) x 5mm (horizontal) x 30mm (thickness), polypropylene) are placed on the openings (left and right) of the exterior material for the energy storage device. Set one of each (melting peak temperature 140°C). A resin film for the energy storage device is sandwiched between one of the lids 60 and the outer material for the energy storage device. After wrapping the lid 60 and dummy cell and applying tension so that there is no gap, the heat-sealable resin layers of the outer material for the energy storage device are heat-sealed at the heat-sealed portion 70 where they meet, using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. Lid The contact surface between 60 and the exterior material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and a time of 3 seconds to obtain a test sample in which the exterior body of the energy storage device includes the exterior material for the energy storage device and a lid, and is interposed between the exterior material for the energy storage device and the lid. In the test sample, a φ11 mm hole is pre-drilled in the center of an aluminum metal block measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which is used as a dummy cell. At this time, a similar hole is drilled in the same position as the dummy cell. To ensure a match, a φ11mm hole is pre-drilled in the outer casing. A jig is attached to the hole in the test sample, and a φ5mm tube is then attached to the jig, ensuring no air leaks. Air is introduced into the sample through the tube, and the pressure is increased to 0.1 MPa. With the pressure at 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C).

[0286] (Measurement of seal strength A and B at temperatures A and B determined in opening test 4) The seal strengths A and B of the resin film for energy storage devices were measured at temperatures A and B determined in opening test 4 using the following procedure. The results are shown in Table 1.

[0287] (procedure) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) One sheet of exterior material for energy storage devices (360mm in the MD direction x 180mm in the TD direction) with a total thickness of 153μm is prepared, consisting of layers with a melting peak temperature of 140℃ and a thickness of 40μm stacked in this order. A dummy cell (aluminum metal block) measuring 100mm in length x 140mm in width x 30mm in thickness, which mimics an electrode body, is wrapped around the exterior material for energy storage devices so that the heat-sealable resin layer faces the block. One lid 60 (100mm in length x 5mm in width x 30mm in thickness, polypropylene, melting peak temperature 140℃) is set on each side. At this time, a resin film for energy storage devices is sandwiched between one lid 60 and the exterior material for energy storage devices, and after wrapping, tension is applied so that there is no gap between the lid 60 and the dummy cell, and the parts where the heat-sealable resin layers of the exterior material for energy storage devices meet facing each other are sealed using a special machine for wrapping and sealing at a temperature of 220℃ and pressure. The upper metal sealing bar and lower silicone rubber were heat-sealed under conditions of 1.0 MPa force and 5 seconds. Subsequently, the contact edges of the lid 60 and the exterior material for the energy storage device were heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and a time of 3 seconds to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. An incision was made in the test sample with a cutter along the long side direction of the lid material (MD direction of the exterior material for the energy storage device), and the dummy cell that was placed inside was removed. An incision of 15 mm width was made in the exterior material for the energy storage device at the position including the installation position of the resin film for the energy storage device, and a test piece was obtained in which the exterior material for the energy storage device and the resin film for the energy storage device were 15 mm wide and sealed to the lid. The obtained test piece was subjected to JIS In accordance with the provisions of K7127:1999, the seal strength at the measurement temperatures of temperature A and temperature B shall be measured as follows:Using a tensile testing machine with a constant temperature chamber, the exterior material for one energy storage device and the lid facing it are chucked and pulled at a speed of 300 mm / min in the measurement environments of temperature A and temperature B, respectively, with a peel angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) between the exterior material for the energy storage device / resin film for the energy storage device / lid at each temperature is measured.

[0288] (Opening test 5) When the resin film for energy storage devices of this disclosure is used to be interposed between the lid body and the covering of the exterior of the energy storage device (see Application 6 above), the temperatures A and B used to measure the seal strengths A and B are determined by the procedure of the following opening test 5.

[0289] (procedure) Prepare one 153μm thick exterior material for an energy storage device (360mm in the MD direction x 180mm in the TD direction), consisting of the following layers: base layer (PET (thickness 12μm) / adhesive (thickness 3μm) / nylon (thickness 15μm) / adhesive layer (thickness 3μm) / barrier layer (aluminum alloy foil, thickness 40μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140℃, thickness 40μm). Wrap the exterior material for the energy storage device around a dummy cell (aluminum metal block) measuring 100mm (vertical) x 140mm (horizontal) x 30mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the exterior material for the energy storage device faces the block. Set one lid 60 on each of the openings (left and right) of the exterior material for the energy storage device. A cover 60 was formed by insert molding a 1mm thick polypropylene (peak melting temperature 140°C), which is heat-sealable to the exterior of an energy storage device, onto the periphery of an aluminum frame measuring 98mm in length, 5mm in width, and 28mm in thickness, as a covering 61. At this time, before injection molding, a resin film for energy storage devices, cut to a size of 8mm in the MD direction and 50mm in the TD direction, was placed on one of the longitudinal sides of the cover body 62 and injected molded so that it was sandwiched between the cover body 62 and the covering 61. 60. After wrapping the dummy cell and applying tension to ensure there is no floating, the heat-sealable resin layers of the outer material for the energy storage device are heat-sealed at the heat-sealable portion 70 where they meet using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. The contact surface between the lid 60 and the outer material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, so that the outer body of the energy storage device is sealed to the energy storage device. A test sample is obtained that includes an exterior material for a pipe and a lid, wherein the lid includes a lid body and a covering that covers the periphery of the lid body, and is interposed between the lid body and the covering. In the test sample, a φ11 mm hole is pre-drilled in the center of an aluminum metal block measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which is used as a dummy cell. At this time, a φ11 mm hole is also pre-drilled in the exterior material so that a similar hole aligns with the dummy cell.A jig is attached to the hole in the test sample, and a φ5mm tube is then attached to the jig in a way that prevents air leakage. Air is introduced into the sample through the tube to increase the pressure to 0.1 MPa. With the pressure at 0.1 MPa, the test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C), and temperature B (°C) is defined as temperature A - 20°C.

[0290] (Measurement of seal strength A and B at temperatures A and B determined in opening test 5) The seal strengths A and B of the resin film for energy storage devices were measured at temperatures A and B determined in opening test 5 using the following procedure. The results are shown in Table 1.

[0291] (procedure) Prepare one casing material for an energy storage device with a total thickness of 153 μm (360 mm in the MD direction x 180 mm in the TD direction), consisting of the following layers: base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm). Wrap the casing material around a dummy cell (aluminum metal block) measuring 100 mm (vertical) x 140 mm (horizontal) x 30 mm (thickness), which mimics an electrode body, so that the heat-sealable resin layer of the casing material for the energy storage device faces the block. Set one lid 60 on each of the openings (left and right) of the casing material for the energy storage device. Lid body 62 (vertical x horizontal) A lid 60 is formed by insert molding a 1mm thick polypropylene (peak melting temperature 140°C), which is heat-sealable to the exterior of an energy storage device, onto the periphery of a 5mm x 28mm thick aluminum material as a covering 61. At this time, before injection molding, a resin film for energy storage devices, cut to a size of 8mm in the MD direction x 50mm in the TD direction, is placed on one of the longitudinal sides of the lid body 62 and injection molded so that it is sandwiched between the lid body 62 and the covering 61. There is no gap in the lid 60 or the dummy cell. After wrapping, the heat-sealable resin layers of the exterior material for the energy storage device are applied under tension, and the heat-sealable portion 70 where these layers meet is heat-sealed using a dedicated machine for wrapping and sealing, at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, using an upper metal sealing bar and a lower silicone rubber. The contact surface between the lid 60 and the exterior material for the energy storage device is heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, so that the exterior body of the energy storage device includes the exterior material for the energy storage device and the lid, and the lid is a lid A test sample is obtained that includes a main body and a covering that covers the periphery of the lid body, with the covering being interposed between the lid body and the covering. An incision is made in the test sample with a cutter along the long side direction of the lid material (MD direction of the outer material), and the dummy cell that was placed inside is removed. A 15 mm wide incision is made in the outer material for the energy storage device at a position including the installation position of the resin film for the energy storage device, and a test piece is obtained in which the outer material for the energy storage device is 15 mm wide and sealed to the lid body.For the obtained test specimens, the seal strength at the measurement temperatures A and B is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at the measurement environments of temperatures A and B, one outer casing material and the opposite lid are chucked and pulled at a speed of 300 mm / min with a peel angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) at each temperature between the outer casing material for the energy storage device / covering of the lid / resin layer for the energy storage device / lid body is measured. A thermocouple is attached to the test specimen, and after the temperature of the test specimen itself reaches temperature A or B and is held for 1 minute, pulling is started.

[0292] [Table 1]

[0293] In Table 1, PP stands for polypropylene, PE for polyethylene, PPa for acid-modified polypropylene, and PEN for polyethylene naphthalate.

[0294] As described above, this disclosure provides inventions in the following embodiments. Item 1. Resin film for energy storage devices, The resin film for the energy storage device includes at least a resin layer A, The resin layer A is a resin film for energy storage devices in which, in a DSC curve obtained by differential scanning calorimetry, the full width at half maximum of melting peaks with a peak height of 0.3 or more is 25°C or less, with the height of the melting peak with the maximum peak height being defined as 1.0. Item 2. The resin film for energy storage devices according to Item 1, wherein the kurtosis value of the melting peak of the DSC curve obtained by differential scanning calorimetry is 1.5 or greater. Item 3. The resin film for energy storage devices according to item 1 or 2, wherein the resin film for energy storage devices comprises at least one selected from the group consisting of polyolefin, acid-modified polyolefin, polyester, and polyamide. Item 4. The resin film for energy storage devices according to any one of items 1 to 3, wherein the resin film for energy storage devices is composed of a single layer or a multilayer. Item 5. The resin film for the energy storage device is composed of multiple layers, A resin film for an energy storage device according to any one of items 1 to 4, wherein the ratio of the thickness of resin layer A to the total thickness of resin layers other than resin layer A is 0.1 or more. Item 6. A resin film for energy storage devices according to any one of items 1 to 5, wherein the melting peak temperature of the resin layer A is 80°C or higher. Item 7. The resin film for energy storage devices according to any one of items 1 to 6, wherein the melting peak temperature of the resin film for energy storage devices is 60°C or higher and 250°C or lower. Item 8. A resin film for energy storage devices according to any one of items 1 to 7, having the characteristic that the ratio of the following seal strength B (N / 15mm) to the following seal strength A (N / 15mm) is 2.0 or greater. <Measurement conditions for seal strength A and B> The temperatures A and B used when measuring seal strengths A and B are determined by performing the following opening test 1. (Opening Test 1) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) Prepare one casing material for an energy storage device (8cm wide x 19cm high) with a total thickness of 153μm, consisting of layers with a melting peak temperature of 140℃ and a thickness of 40μm. Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place a resin film between the heat-sealable resin layers on the short side (horizontal). The size of the resin film should be 3cm wide x 1.5cm high. Position the casing material and the resin film so that their horizontal and vertical dimensions match. More specifically, horizontally, position the center of the test piece and the resin film to match, and vertically, position the casing material and the resin film to match. The resin film is positioned so that its vertical bottom edge aligns with the 8cm short side, which is the vertical bottom edge of the chair exterior material. Next, the short side with the resin film positioned and the two long sides of the energy storage device exterior material are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and it is placed in an oven, and a φ5 mm tube is attached to a jig for attaching the tube. Air is blown into the test sample from the attached tube and the internal pressure is maintained at a constant level once it reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature when the test sample is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C). (Measurement of seal strength A and B at temperatures A and B determined in opening test 1) Base layer (PET (thickness 12μm) / Adhesive (thickness 3μm) / Nylon (thickness 15μm) / Adhesive layer (thickness 3μm) / Barrier layer (Aluminum alloy foil, thickness 40μm) / Adhesive layer (Maleic acid anhydride modified polypropylene, thickness 40μm) / Heat-sealable resin layer (Polypropylene) A casing material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers in the following order (melting peak temperature 140°C, thickness 40 μm), and cut to a size of 60 mm (Z direction) x 150 mm (X direction). The heat-sealable resin layer of the casing material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film (60 mm in the Z direction, 15 mm in the X direction) is sandwiched between them. In this state, a laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads under the conditions of 190°C x 0.5 MPa x 3 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (where both sides of the resin film are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film is sandwiched between the heat-sealable resin layers. The obtained test piece is subjected to JIS In accordance with the provisions of K7127:1999, the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature -20°C) shall be measured as follows: Using a tensile testing machine with a constant temperature chamber, one outer packaging material and the opposite outer packaging material shall be chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) at each temperature shall be measured. (Measurement of seal strength A and B) After cutting the exterior material for the energy storage device to a size of 60 mm in the MD direction and 150 mm in the TD direction, the heat-sealable resin layer of the exterior material for the energy storage device is folded in half with the heat-sealable resin layer facing inward, and a resin film is sandwiched between the two halves. In this state, using a heat sealing machine with 7 mm wide upper and lower metal heads, the resin film between the heat-sealable resin layers is heat-sealed at a temperature of 190°C, a surface pressure of 0.5 MPa, and for 3 seconds to obtain a laminate. The obtained laminate is cut, and a 15 mm strip-shaped test piece (where both sides of the resin film are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film is sandwiched between the heat-sealable resin layers. The seal strength of the obtained test piece at temperatures A and B is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, at temperatures A and B, one outer casing material and the opposite outer casing material are chucked and pulled at a speed of 300 mm / min with a peel angle of 180° (chuck distance of 50 mm), and the seal strength A (N / 15 mm) at temperature A and the seal strength B (N / 15 mm) at temperature B are measured. Item 9. The resin film for the energy storage device is 1) In applications where the heat-sealable resin layers of the exterior material for energy storage devices are heat-sealed together, the material is interposed between the heat-sealable resin layers. 2) Applications in which it is used as a heat-sealable resin layer for exterior materials of energy storage devices. 3) Applications where it is used as an adhesive layer between the barrier layer and the heat-fusible resin layer of the exterior material for energy storage devices. 4) An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrode of a power storage device element and an outer casing that seals the power storage device element. 5) The casing of the energy storage device includes an casing material for the energy storage device and a cover. Applications in which the device is interposed between the exterior material for the energy storage device and the cover, 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. Applications in which it is interposed between the lid body and the covering, A resin film for energy storage devices as described in any one of items 1 to 8, used for any of the following purposes. Item 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 by an outer casing, An energy storage device comprising a resin film for energy storage devices described in any one of items 1 to 9 in at least one of the following embodiments: 1) to 6). 1) An embodiment in which the heat-sealable resin layers of the exterior material for an energy storage device are interposed between the heat-sealable resin layers at the position where they are heat-sealed together. 2) Embodiments included as a heat-fusible resin layer for exterior material of energy storage device 3) An embodiment that includes an adhesive layer between the barrier layer and the heat-fusible resin layer of an exterior material for an energy storage device. 4) An embodiment that includes an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing that seals the energy storage device element. 5) The casing of the energy storage device includes an casing material for the energy storage device and a cover. A component included between the exterior material for the energy storage device and the lid. 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering. [Explanation of Symbols]

[0295] 1. Resin film for energy storage devices 2 metal terminals 3. Exterior materials for energy storage devices 3a Peripheral edge of exterior material 4 Energy Storage Device Elements 5. Adhesive film for metal terminals 10 Energy storage devices 11 1st layer 12 2nd layer 13 3rd layer 30 Exterior 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-fusible resin layer 60 Lid 61 Covering 62 Lid body 70 Heat-sealed joint between heat-sealable resin layers A Resin layer A

Claims

1. A resin film for energy storage devices, The resin film for the energy storage device includes at least a resin layer A, The resin layer A comprises at least one selected from the group consisting of polyolefins and acid-modified polyolefins. In the resin layer A, when the height of the melting peak with the maximum peak height is set to 1.0 in the DSC curve obtained by differential scanning calorimetry, the full width at half maximum of the melting peak with a peak height of 0.3 or more is 25°C or less. With respect to the resin layer A, the kurtosis value calculated for the entire melting peak in the DSC curve obtained by differential scanning calorimetry is 2.5 or greater. The melting peak temperature of the resin layer A is 80°C or higher and 140°C or lower. A resin film for energy storage devices having the characteristic that the ratio of the following seal strength B (N / 15mm) to the following seal strength A (N / 15mm) is 2.7 or higher. <Measurement conditions for seal strength A and B> The temperatures A and B used when measuring seal strengths A and B are determined by performing the following opening test 1. (Opening test 1) Base layer (PET (thickness 12 μm) / Adhesive (thickness 3 μm) / Nylon (thickness 15 μm) / Adhesive layer (thickness 3 μm) / Barrier layer (aluminum alloy foil, thickness 40 μm) / Adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / Heat-sealable resin layer (polypropylene) Prepare one casing material for an energy storage device (8 cm wide x 19 cm high) with a total thickness of 153 μm, made by laminating layers in the following order: melting peak temperature of 140°C, thickness of 40 μm. Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11 mm hole in one place on one side (exactly in the center of the 8 cm wide x 9.5 cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device should be 3 cm wide x 1.5 cm high. Position the casing material and the resin film for the energy storage device so that their horizontal and vertical dimensions match. More specifically, horizontally, position the casing material and the resin film so that their centers match, and vertically, position the casing material and the resin film so that their centers match. The 3 cm long side of the resin film for the energy storage device is positioned so that it aligns with the 8 cm short side, which is the bottom vertical edge of the vise casing material. Next, the short side on which the resin film for the energy storage device is positioned and the two long sides of the casing material are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in an oven, and a φ5 mm tube is attached to a jig for attaching the tube. Air is blown into the test sample from the attached tube and the internal pressure is kept constant once it reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature when the test sample is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C). (Measurement of seal strength A and B at temperatures A and B determined in opening test 1) Base layer (PET (thickness 12 μm) / Adhesive (thickness 3 μm) / Nylon (thickness 15 μm) / Adhesive layer (thickness 3 μm) / Barrier layer (aluminum alloy foil, thickness 40 μm) / Adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / Heat-sealable resin layer (polypropylene) A casing material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers in the following order (melting peak temperature 140°C, thickness 40 μm), and cut to a size of 60 mm horizontally (Z direction) x 150 mm vertically (X direction). The heat-sealable resin layer of the casing material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film for energy storage devices (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between the layers. In this state, a laminate is obtained by heat-sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (both sides of the resin film for energy storage devices are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film is sandwiched between the heat-sealable resin layers. The obtained test piece is subjected to JIS In accordance with K7127:1999, the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature - 20°C) shall be measured as follows: Using a tensile testing machine with a constant temperature chamber, at each measurement environment temperature, one exterior material for the energy storage device and the opposite exterior material for the energy storage device are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) at each temperature shall be measured. At this time, a thermocouple shall be attached to the exterior material for the energy storage device, and pulling shall be started after the sample has reached temperature A and temperature B and been held for 1 minute.

2. The resin film for energy storage devices according to Claim 1, wherein the kurtosis value calculated for the entire melting peak in the DSC curve obtained by differential scanning calorimetry is 3.0 or more for the resin layer A.

3. The resin film for the energy storage device according to claim 1 or 2, wherein the resin film for the energy storage device comprises a polyolefin and an acid-modified polyolefin.

4. The resin film for energy storage devices according to claim 1 or 2, wherein the resin film for energy storage devices is composed of a single layer or multiple layers.

5. The resin film for the energy storage device is composed of multiple layers. The resin film for an energy storage device according to claim 1 or 2, wherein the ratio of the thickness of resin layer A to the total thickness of resin layers other than resin layer A is 0.1 or more.

6. The resin film for energy storage devices according to claim 1, wherein the melting peak temperature of the resin layer A is 90°C or higher and 140°C or lower.

7. The resin film for energy storage devices according to claim 1 or 2, wherein the melting peak temperature of the melting peak with the maximum peak height in the DSC curve obtained by differential scanning calorimetry of the resin film for energy storage devices is 60°C or higher and 250°C or lower.

8. A resin film for an energy storage device according to claim 1 or 2, having the characteristic that the ratio of the following seal strength B (N / 15 mm) to the following seal strength A (N / 15 mm) is 2.7 or more and 40 or less. <Measurement conditions for seal strength A and B> The temperatures A and B used when measuring seal strengths A and B are determined by performing the following opening test 1. (Opening test 1) Base layer (PET (thickness 12 μm) / Adhesive (thickness 3 μm) / Nylon (thickness 15 μm) / Adhesive layer (thickness 3 μm) / Barrier layer (aluminum alloy foil, thickness 40 μm) / Adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / Heat-sealable resin layer (polypropylene) Prepare one casing material for an energy storage device (8 cm wide x 19 cm high) with a total thickness of 153 μm, made by laminating layers in the following order: melting peak temperature of 140°C, thickness of 40 μm. Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11 mm hole in one place on one side (exactly in the center of the 8 cm wide x 9.5 cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device should be 3 cm wide x 1.5 cm high. Position the casing material and the resin film for the energy storage device so that their horizontal and vertical dimensions match. More specifically, horizontally, position the casing material and the resin film so that their centers match, and vertically, position the casing material and the resin film so that their centers match. The 3 cm long side of the resin film for the energy storage device is positioned so that it aligns with the 8 cm short side, which is the bottom vertical edge of the vise casing material. Next, the short side on which the resin film for the energy storage device is positioned and the two long sides of the casing material are heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm to create a test sample. At this time, both sides of the resin film for the energy storage device are heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in an oven, and a φ5 mm tube is attached to a jig for attaching the tube. Air is blown into the test sample from the attached tube and the internal pressure is kept constant once it reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reaches 150°C. The opening temperature when the test sample is opened is defined as temperature A (°C), and temperature A - 20°C is defined as temperature B (°C). (Measurement of seal strength A and B at temperatures A and B determined in opening test 1) Base layer (PET (thickness 12 μm) / Adhesive (thickness 3 μm) / Nylon (thickness 15 μm) / Adhesive layer (thickness 3 μm) / Barrier layer (aluminum alloy foil, thickness 40 μm) / Adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / Heat-sealable resin layer (polypropylene) A casing material for energy storage devices with a total thickness of 153 μm is prepared by laminating layers in the following order (melting peak temperature 140°C, thickness 40 μm), and cut to a size of 60 mm horizontally (Z direction) x 150 mm vertically (X direction). The heat-sealable resin layer of the casing material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film for energy storage devices (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between the layers. In this state, a laminate is obtained by heat-sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The obtained laminate is cut, and a 15 mm strip-shaped test piece (both sides of the resin film for energy storage devices are heat-sealed to the heat-sealable resin layer) is obtained from the center of the position where the resin film is sandwiched between the heat-sealable resin layers. The obtained test piece is subjected to JIS In accordance with K7127:1999, the seal strength in environments with temperature A (opening temperature) and temperature B (opening temperature - 20°C) shall be measured as follows: Using a tensile testing machine with a constant temperature chamber, at each measurement environment temperature, one exterior material for the energy storage device and the opposite exterior material for the energy storage device are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance of 50 mm), and the seal strength (N / 15 mm) at each temperature shall be measured. At this time, a thermocouple shall be attached to the exterior material for the energy storage device, and pulling shall be started after the sample has reached temperature A and temperature B and been held for 1 minute.

9. The aforementioned resin film for the energy storage device is 1) In applications where the heat-sealable resin layers of the exterior material for energy storage devices are heat-sealed together, the material is interposed between the heat-sealable resin layers. 2) Applications in which it is used as a heat-sealable resin layer for exterior materials of energy storage devices. 3) Applications in which it is used as an adhesive layer between the barrier layer and the heat-sealable resin layer of the exterior material for energy storage devices. 4) Applications in which a metal terminal is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing that seals the energy storage device element, 5) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. Applications in which the device is interposed between the exterior material for the energy storage device and the cover, 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. Applications in which it is interposed between the lid body and the covering, A resin film for an energy storage device according to claim 1 or 2, used for any of the following purposes.

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 by an outer casing, An energy storage device comprising a resin film for energy storage devices as described in claim 1 or 2 in at least one of the following embodiments 1) to 6). 1) An embodiment in which the heat-sealable resin layers of the exterior material for an energy storage device are interposed between the heat-sealable resin layers at the location where they are heat-sealed together. 2) Embodiments included as a heat-sealable resin layer for an exterior material for an energy storage device 3) An embodiment that includes an adhesive layer between the barrier layer and the heat-fusible resin layer of an exterior material for an energy storage device. 4) An embodiment that includes an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing that seals the energy storage device element. 5) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. A component included between the exterior material for the energy storage device and the lid. 6) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering.

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