JP7567417B2 - Exterior material for power storage device, manufacturing method thereof, power storage device, and polyamide film - Google Patents

Description

This disclosure relates to an exterior material for an electricity storage device, a manufacturing method thereof, an electricity storage device, and a polyamide film.

Various types of electricity storage devices have been developed, but in all electricity storage devices, exterior materials are essential components for sealing the electricity storage device elements such as electrodes and electrolytes. Traditionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like, there is a demand for electricity storage devices to have a variety of shapes, as well as to be thinner and lighter. However, the metallic exterior materials for electricity storage devices that have been widely used in the past have the disadvantage that they are difficult to keep up with the diversification of shapes, and there is also a limit to how much they can be made lighter.

In recent years, a film-like laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are laminated in this order has been proposed as an exterior material for electricity storage devices that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

In such electrical storage device exterior materials, recesses are generally formed by cold forming, electrical storage device elements such as electrodes and electrolyte are placed in the space formed by the recesses, and the heat-sealable resin layer is heat-sealed to obtain an electrical storage device in which the electrical storage device elements are housed inside the electrical storage device exterior material.

JP 2008-287971 A

Electricity storage device elements contain components such as rare metals, and the demand for these components is rapidly increasing. For this reason, when replacing an electricity storage device in various products such as electrical equipment, there is a demand to remove the electricity storage device from the product and recover and reuse the various components contained in the electricity storage device element.

In various products such as electrical equipment, the electricity storage device is firmly fixed to the housing of the product by double-sided tape, adhesive, or the like. For this reason, when removing the electricity storage device from the housing of the product, a large external force is applied to the electricity storage device. Specifically, the electricity storage device is generally removed from the housing using a metal spatula or the like, and a large external force is applied to the electricity storage device. If a large external force is applied to the exterior material for the electricity storage device, which is made of a film-like laminate, when removing the electricity storage device, there is a risk that the exterior material for the electricity storage device will be damaged.

In light of these circumstances, the main objective of the present disclosure is to provide an exterior material for an electricity storage device that is prevented from being damaged when the electricity storage device is peeled off from the housing after being fixed to the housing with double-sided tape or the like.

The inventors of the present disclosure conducted intensive research to solve the above-mentioned problems. As a result, they discovered that an exterior material for an electricity storage device, which is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, the base layer includes a polyamide film, and the crystallization index of the polyamide film measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy is a predetermined value or more, is suppressed from being damaged when the electricity storage device fixed to the housing with double-sided tape or the like is peeled off from the housing.

The present disclosure has been completed based on these findings and through further investigations. That is, the present disclosure provides the invention of the following aspects.
The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
An exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy.

According to the present disclosure, it is possible to provide an exterior material for an electricity storage device that is suppressed from being damaged when an electricity storage device fixed to a housing with double-sided tape or the like is peeled off from the housing with a metal spatula or the like. In addition, according to the present disclosure, it is also possible to provide a manufacturing method for the exterior material for an electricity storage device, an electricity storage device that uses the exterior material for an electricity storage device, and a polyamide film that is suitable for use as a base layer of the exterior material for an electricity storage device.

1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. 4A to 4C are schematic diagrams illustrating a procedure for producing a sample used in a peel test of an electricity storage device in an example. 3A and 3B are a side view and a plan view, respectively, of a sample used in a peel test of an electricity storage device in an example. 4A and 4B are a side view and a plan view of a double-sided tape attached to a sample used in a peel test of an electricity storage device in an example. FIG. 2 is a schematic diagram showing how an electricity storage device is peeled off from a stainless steel plate using a metal spoon in a peel test of the electricity storage device in the examples.

The exterior material for an electricity storage device disclosed herein is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, and the base layer includes a polyamide film, and the polyamide film has a crystallization index of 1.50 or more measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy. The exterior material for an electricity storage device disclosed herein is suppressed from being damaged when the electricity storage device fixed to the housing with double-sided tape or the like is peeled off from the housing.

The exterior material for an electricity storage device disclosed herein is described in detail below. In this specification, the numerical range indicated by "-" means "greater than or equal to" or "less than or equal to." For example, the expression 2-15 mm means 2 mm or more and 15 mm or less.

1. Laminated structure and physical properties of the exterior material for an electric storage device The exterior material for an electric storage device 10 of the present disclosure is composed of a laminate including, in order from the outside, a base layer 1, a barrier layer 3, and a heat-sealable resin layer 4, as shown in FIG. 1 for example. In the exterior material for an electric storage device 10, the base layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electric storage device using the exterior material for an electric storage device 10 and an electric storage device element, the heat-sealable resin layers 4 of the exterior material for an electric storage device 10 are opposed to each other, and the electric storage device element is accommodated in a space formed by heat-sealing the periphery. In the laminate constituting the exterior material for an electric storage device 10 of the present disclosure, the barrier layer 3 is used as a reference, and the heat-sealable resin layer 4 side is the inner side of the barrier layer 3, and the base layer 1 side is the outer side of the barrier layer 3.

As shown in Figs. 2 to 4, the exterior material 10 for an electric storage device may have an adhesive layer 2 between the base layer 1 and the barrier layer 3, if necessary, for the purpose of increasing the adhesion between these layers. Also, as shown in Figs. 3 and 4, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-sealable resin layer 4, if necessary, for the purpose of increasing the adhesion between these layers. Also, as shown in Fig. 5, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (the side opposite to the heat-sealable resin layer 4) if necessary.

The thickness of the laminate constituting the exterior material for electricity storage devices 10 is not particularly limited, but from the viewpoints of cost reduction and energy density improvement, the upper limit is preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less, and from the viewpoints of maintaining the function of the exterior material for electricity storage devices to protect the electricity storage device elements, the lower limit is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more, and preferred ranges include, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, and among these, 60 to 120 μm is particularly preferred.

In the exterior material for a power storage device 10, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 provided as needed, the barrier layer 3, the adhesive layer 5 provided as needed, the heat-sealable resin layer 4, and the surface coating layer 6 provided as needed to the thickness (total thickness) of the laminate constituting the exterior material for a power storage device 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the exterior material for a power storage device 10 of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material for a power storage device 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

The substrate layer 1 of the exterior material 10 for an electric storage device of the present disclosure contains a polyamide film, and the crystallization index of the polyamide film measured from the outside of the substrate layer 1 by the ATR method of Fourier transform infrared spectroscopy is 1.50 or more. The method for measuring the crystallization index of the substrate layer 1 of the exterior material 10 for an electric storage device of the present disclosure is as follows.

<Measurement of Crystallization Index of Base Material Layer of Exterior Material for Electricity Storage Device>
The exterior material for an electric storage device is cut into a square of 100 mm x 100 mm to prepare a sample. The surface of the polyamide film located on the outside of the obtained sample is subjected to infrared absorption spectrum measurement under an environment of a temperature of 25 ° C. and a relative humidity of 50% using the ATR measurement mode of FT-IR. As an apparatus, for example, Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, a peak intensity P at about 1200 cm ^-1 resulting from the absorption of α crystals of nylon and a peak intensity Q at about 1370 cm ^-1 resulting from the absorption unrelated to crystals are measured, and the intensity ratio X = P / Q of the peak intensity P to the peak intensity Q is calculated as the crystallization index. Note that, when the exterior material for an electric storage device is obtained from the electric storage device to measure the crystallization index of the base layer, the exterior material for an electric storage device is obtained from the top or bottom surface of the electric storage device, not from the heat-sealed portion or side surface, to prepare a sample.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

In addition, when the outer surface of the exterior material 10 for a power storage device is composed of the polyamide film of the base material layer 1, the exterior material 10 for a power storage device can be used as it is to measure the crystallization index. In addition, when the outer surface of the exterior material 10 for a power storage device is not composed of the polyamide film of the base material layer 1, such as when the base material layer 1 has a multilayer structure as described below and a resin film (e.g., a polyester film) different from the polyamide film is located outside the polyamide film, or when the surface coating layer 6 described below is laminated on the outside of the base material layer 1, the layer located outside the polyamide film can be removed from the exterior material 10 for a power storage device to expose the surface of the polyamide film, and the crystallization index can be measured.

In the exterior material 10 for an electrical storage device, the crystallization index may be 1.50 or more, but from the viewpoint of more effectively preventing damage to the exterior material for an electrical storage device during the aforementioned peeling, it is more preferably 1.55 or more, even more preferably 1.60 or more, and particularly preferably 1.65 or more. There is no particular limit to the upper limit of the crystallization index, but examples of the upper limit include 2.50 or less and 1.80 or less. Examples of preferred ranges of the crystallization index include 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.50 to 1.80, 1.60 to 1.80, and 1.65 to 1.80.

Methods for increasing the crystallization index of the polyamide film contained in the base material layer 1 of the exterior material 10 for an electrical storage device to 1.50 or more include promoting crystallization (promoting the formation of α crystals) by adjusting the stretching ratio, heat setting temperature, and even the post-heating temperature and time during the polyamide film manufacturing process.

2. Layers forming the exterior material for an electricity storage device [Base material layer 1]
In the present disclosure, the substrate layer 1 is a layer provided for the purpose of exhibiting the function as a substrate of the exterior material for an electricity storage device, etc. The substrate layer 1 is located on the outer layer side of the exterior material for an electricity storage device.

The substrate layer 1 contains a polyamide film. As described above, the crystallization index of the polyamide film measured from the outside of the substrate layer 1 by the ATR method of Fourier transform infrared spectroscopy is 1.50 or more.

The polyamide forming the polyamide film may be any polyamide having α crystals, and specific examples include aliphatic polyamides such as nylon 6, nylon 66, nylon 46, and copolymers of nylon 6 and nylon 66. These polyamides may be used alone or in combination of two or more. The polyamide film is preferably a nylon film.

The polyamide film may be an unstretched film or a stretched film. When the base material layer 1 includes an unstretched film, when laminating each layer of the exterior material 10 for a storage device, the unstretched film may be extruded to form an unstretched film, a previously prepared unstretched film may be laminated, or a resin (polyamide) may be applied to form an unstretched film. Examples of a method for applying a resin include a roll coating method, a gravure coating method, and an extrusion coating method. When the base material layer 1 is a stretched film, a previously prepared stretched film is laminated when laminating each layer of the exterior material 10 for a storage device. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferable. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method.

The polyamide film is preferably a biaxially oriented nylon film.

In the exterior material 10 for a storage battery device of the present disclosure, a polyamide film having a crystallization index of 1.50 or more measured by the ATR method of Fourier transform infrared spectroscopy can be used as the base material layer 1, or the crystallization index can be increased to 1.50 or more by applying heat to the polyamide film during the manufacturing process of the exterior material 10 for a storage battery device. As described in the section "5. Polyamide film" below, the exterior material 10 for a storage battery device of the present disclosure is preferably manufactured using a polyamide film having a crystallization index of 1.50 or more measured by the ATR method of Fourier transform infrared spectroscopy as the base material layer 1. That is, it is preferable to manufacture the exterior material 10 for a storage battery device of the present disclosure by laminating each layer such as the barrier layer 3 and the heat-sealable resin layer 4 with a polyamide film having a crystallization index of 1.50 or more measured by the ATR method of Fourier transform infrared spectroscopy as the base material layer 1. As will be shown in the examples described later, the crystallization index of the polyamide film laminated to the exterior material 10 for the electric storage device and included in the base layer 1 can be increased compared to the polyamide film before it is applied to the exterior material 10 for the electric storage device.

The thickness of the polyamide film is preferably at least about 3 μm, more preferably at least about 10 μm, and is preferably no more than about 50 μm, more preferably no more than about 35 μm, from the viewpoint of more effectively preventing damage to the exterior material for an electricity storage device during the aforementioned peeling off. Preferred ranges include about 3 to 50 μm, about 3 to 35 μm, about 10 to 50 μm, and about 10 to 35 μm, and of these, about 10 to 35 μm is particularly preferred.

The substrate layer 1 may further have a resin film different from the polyamide film. Examples of resins that form a resin film different from the polyamide film include polyester, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, phenolic resin, and other resins, as well as modified products of these resins. The resin may also be a copolymer of these resins, or a modified product of the copolymer. Furthermore, it may be a mixture of these resins. Among these, polyester is preferable.

Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), and polyethylene (terephthalate/decane dicarboxylate). These polyesters may be used alone or in combination of two or more. Among these, polyethylene terephthalate and polybutylene terephthalate are preferred.

The polyester film is preferably a stretched polyester film, more preferably a biaxially stretched polyester film.

The polyester film is preferably a biaxially oriented polyethylene terephthalate film or a biaxially oriented polybutylene terephthalate film.

When the base layer 1 further has a resin film other than the polyamide film, the thickness of the other resin film is not particularly limited as long as it does not impair the effects of the present invention, and is preferably about 3 μm or more, more preferably about 10 μm or more, and is preferably about 50 μm or less, more preferably about 35 μm or less. Preferred ranges include about 3 to 50 μm, about 3 to 35 μm, about 10 to 50 μm, and about 10 to 35 μm, and of these, about 10 to 35 μm is particularly preferred.

As long as the base material layer 1 contains a polyamide film, it may be a single layer or may be composed of two or more layers, and from the viewpoint of making the exterior material 10 for an electricity storage device thinner, it is preferable that it is a single layer of polyamide film.

When the base layer 1 is composed of two or more layers, the base layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. In addition, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base layer 1.

Specific examples of laminates of two or more resin films in the base layer 1 include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, etc., and preferably a laminate of a stretched nylon film and a stretched polyester film, or a laminate of two or more stretched nylon films. For example, when the base layer 1 is a laminate of two resin films, a laminate of a polyamide resin film and a polyamide resin film, or a laminate of a polyester resin film and a polyamide resin film, is preferred, and a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film, is more preferred. In addition, when the base layer 1 is a laminate of two or more resin films, it is preferred that the polyester resin film is located as the outermost layer of the base layer 1, because polyester resin is less likely to discolor when, for example, an electrolyte is attached to the surface.

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

Additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and interior of the base layer 1. Only one type of additive may be used, or two or more types may be mixed together.

In the present disclosure, from the viewpoint of improving the formability of the exterior material for a power storage device, it is preferable that a lubricant is present on the surface of the base material layer 1. The lubricant is not particularly limited, but is preferably an amide-based lubricant. Specific examples of amide-based lubricants include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, 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 amides, palmitic acid amides, stearic acid amides, behenic acid amides, and hydroxystearic acid amides. Specific examples of unsaturated fatty acid amides include oleic acid amides and erucic acid amides. Specific examples of substituted amides include N-oleyl palmitic acid amides, N-stearyl stearic acid amides, N-stearyl oleic acid amides, N-oleyl stearic acid amides, and N-stearyl erucic acid amides. Specific examples of methylol amides include methylol stearic acid amides. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamide ethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N,N'-distearylisophthalic acid amide. The lubricant may be used alone or in combination of two or more types.

When a lubricant is present on the surface of the base layer 1, the amount thereof is not particularly limited, but is preferably about 3 mg/m2 or ^more , more preferably about 4 to 15 mg/ ^m2 , and even more preferably about ⁵ to 14 mg/m2.

The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1.

The total thickness of the substrate layer 1 is not particularly limited as long as it functions as a substrate, but may be, for example, about 3 to 50 μm, and preferably about 10 to 35 μm.

[Coat layer]
The exterior material for an electric storage device according to the present disclosure may have a coating layer (not shown) on the substrate layer 1 (the side opposite to the barrier layer 3 side of the substrate layer 1) as necessary for the purpose of improving printability, moldability, and the like. The coating layer is provided so as to be in contact with the substrate layer 1. The thickness of the coating layer is not particularly limited as long as it exhibits the above-mentioned function as a coating layer, and may be, for example, about 0.01 to 0.40 μm, preferably about 0.01 to 0.30 μm, and more preferably about 0.1 to 0.30 μm. By having a thickness of 0.01 μm or more, a layer with a uniform film thickness can be formed on the substrate layer 1. As a result, the exterior material for an electric storage device according to the present disclosure can be printed uniformly without unevenness, and uniform moldability can be obtained.

Examples of resins that form the coating layer include various synthetic resins such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, polyolefin, acid-modified polyolefin, polyester, epoxy resin, phenolic resin, fluororesin, cellulose ester, polyurethane, acrylic resin, and polyamide. Among these, polyurethane, polyester, and acrylic resin are preferred.

The coating layer may contain lubricants and additives as necessary to improve slipperiness. Examples of lubricants include the same lubricants as those described above. Examples of additives include the same additives as those exemplified for the surface coating layer 6 described below. The content and particle size of these lubricants and additives are appropriately adjusted according to the thickness of the coating layer.

In addition, the exterior material for a storage battery device of the present disclosure may have a coating layer (not shown) on one side (the barrier layer 3 side of the substrate layer 1 or the side opposite to the barrier layer 3 of the substrate layer 1) or on both sides of the substrate layer 1, as necessary, for the purpose of improving adhesion to the layer adjacent to the substrate layer. That is, the coating layer provided on the substrate layer may be a layer intended to improve printability, formability, etc., or may be a layer intended to improve the adhesiveness of the substrate layer. Even when the coating layer is intended to improve the adhesiveness of the substrate layer, the resin forming the coating layer and the thickness are exemplified as the resin and thickness of the coating layer described above. In addition, the above-mentioned lubricants and additives may be included, but if there is an adjacent layer on the opposite side of the substrate layer to the coating layer, it is preferable not to include lubricants or additives.

[Adhesive layer 2]
In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as necessary for the purpose of increasing the adhesion between them.

The adhesive layer 2 is formed from an adhesive capable of bonding the base layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

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

The polyurethane adhesive may be, for example, a polyurethane adhesive containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. A two-component curing type polyurethane adhesive is preferably used, in which a polyol such as polyester polyol, polyether polyol, or acrylic polyol is used as the base agent, and an aromatic or aliphatic polyisocyanate is used as the curing agent. In addition, it is preferable to use a polyester polyol having a hydroxyl group on the side chain in addition to the hydroxyl group at the end of the repeating unit, as the polyol compound. Since the adhesive layer 2 is formed from a polyurethane adhesive, the exterior material for the electricity storage device is given excellent electrolyte resistance, and the base layer 1 is prevented from peeling off even if the electrolyte adheres to the side surface.

In addition, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. By including a colorant in the adhesive layer 2, the exterior material for the power storage device can be colored. As the colorant, known colorants such as pigments and dyes can be used. In addition, only one type of colorant may be used, or two or more types may be mixed together.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindolenine, and benzimidazolone pigments. Examples of inorganic pigments include carbon black, titanium oxide, cadmium, lead, chromium oxide, iron, and copper pigments. Other examples include fine mica powder and fish scale foil. Pigments can be used alone or in combination of two or more types, such as an organic pigment and an inorganic pigment.

Among colorants, carbon black is preferred, for example to give the exterior material for an electricity storage device a black appearance.

The average particle size of the pigment is not particularly limited, and may be, for example, about 0.05 to 5 μm, and preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured with a laser diffraction/scattering type particle size distribution measuring device.

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the exterior material for the electricity storage device is colored, and may be, for example, about 5 to 60% by mass, and preferably 8 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3, but the lower limit is, for example, about 1 μm or more, about 2 μm or more, the upper limit is about 10 μm or less, about 5 μm or less, and preferred ranges are about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[Colored layer]
The colored layer is a layer (not shown) that is provided between the base material layer 1 and the barrier layer 3 as necessary. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Also, a colored layer may be provided on the outside of the base material layer 1. By providing a colored layer, the exterior material for an electricity storage device can be colored.

The colored layer can be formed, for example, by applying an ink containing a colorant to the surface of the base layer 1, the surface of the adhesive layer 2, or the surface of the barrier layer 3. As the colorant, known pigments, dyes, and the like can be used. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

Specific examples of colorants contained in the colored layer include those exemplified in the [Adhesive layer 2] section.

[Barrier layer 3]
In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the infiltration of moisture.

Examples of the barrier layer 3 include metal foils, vapor deposition films, and resin layers having barrier properties. Examples of the vapor deposition films include metal vapor deposition films, inorganic oxide vapor deposition films, and carbon-containing inorganic oxide vapor deposition films. Examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 include resin films having at least one layer of these vapor deposition films and resin layers. The barrier layer 3 may be provided in multiple layers. It is preferable that the barrier layer 3 includes a layer composed of a metal material. Specific examples of the metal material constituting the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that the barrier layer 3 includes at least one of aluminum alloy foil and stainless steel foil.

From the viewpoint of improving the formability of the exterior material for an electric storage device, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability, the aluminum alloy foil is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100 mass%), the iron content is preferably 0.1 to 9.0 mass%, and more preferably 0.5 to 2.0 mass%. By having an iron content of 0.1 mass% or more, an exterior material for an electric storage device having better formability can be obtained. By having an iron content of 9.0 mass% or less, an exterior material for an electric storage device having better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition 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 necessary. Softening can be achieved by annealing or the like.

Examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior material for an electricity storage device with excellent formability, it is preferable that the stainless steel foil is made of austenitic stainless steel.

Specific examples of austenitic stainless steels that make up the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

The thickness of the barrier layer 3, in the case of a metal foil, should be such that it at least functions as a barrier layer to prevent the penetration of moisture, and may be, for example, approximately 9 to 200 μm. The thickness of the barrier layer 3 is, for example, 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, and preferably about 10 μm or more, more preferably about 20 μm or more, and more preferably about 25 μm or more, with the thickness being preferably in the range of 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, with about 25 to 40 μm being particularly preferred. When the barrier layer 3 is made of an aluminum alloy foil, the above-mentioned range is particularly preferred. In particular, when the barrier layer 3 is made of stainless steel foil, the upper limit of 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 particularly preferably about 25 μm or less, and the lower limit is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred thickness ranges 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.

In addition, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite to the base layer is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant film on both sides. Here, the corrosion-resistant film refers to a thin film that is provided with corrosion resistance by performing, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, or corrosion prevention treatment by applying a coating agent on the surface of the barrier layer. The treatment for forming the corrosion-resistant film may be one type, or two or more types may be combined. In addition, it is possible to form not only one layer but also multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the metal foil surface is dissolved by a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of chemical conversion treatment. In addition, when the barrier layer 3 has a corrosion-resistant film, the corrosion-resistant film is included in the barrier layer 3.

The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during molding of the exterior material for the power storage device, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and in particular prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is an aluminum alloy foil, and improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the base layer and barrier layer during heat sealing and between the base layer and barrier layer during molding.

Various corrosion-resistant films formed by chemical conversion treatments are known, including mainly corrosion-resistant films containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Chemical conversion treatments using phosphates and chromates include, for example, chromate chromate treatment, phosphoric acid chromate treatment, phosphoric acid-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, chromate acetyl acetate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. In this coating-type chromate treatment, at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) is first degreased by a known method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or an acid activation method, and then a treatment liquid mainly composed of a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, or Zn (zinc) phosphate, or a mixture of these metal salts, or a treatment liquid mainly composed of a nonmetallic phosphate and a mixture of these nonmetallic salts, or a treatment liquid consisting of a mixture of these with a synthetic resin, or the like, is applied to the degreased surface by a known coating method such as a roll coating method, a gravure printing method, a dipping method, or the like, and then dried. As the treatment liquid, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents can be used, and water is preferred. The resin component used here may be a polymer such as a phenolic resin or an acrylic resin, and may be a chromate treatment using an aminated phenolic polymer having a repeating unit represented by the following general formulas (1) to (4). In the aminated phenolic polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. The acrylic resin is preferably polyacrylic acid, acrylic acid methacrylic acid ester copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. In particular, a derivative of polyacrylic acid such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid is preferable. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic anhydride, and is also preferably an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

In the general formulae (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. R ¹ and R ² may be the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In the general formulae (1) to (4), examples of the alkyl group represented by X, R ¹ , and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the hydroxyalkyl group represented by X, R ^1, and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms and substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. In the general formulae (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ^1, and R ² may be the same or different. In the general formulae (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 units represented by the general formulae (1) to (4) is preferably about 500 to 1,000,000, for example, and 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 with formaldehyde to produce a polymer consisting of the repeating units represented by the general formula (1) or (3), and then introducing a functional group (-CH ₂ NR ¹ R ² ) into the polymer obtained above using formaldehyde and an amine (R ¹ R ² NH). The aminated phenol polymer may be used alone or in combination of two or more types.

Other examples of corrosion-resistant films include thin films formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol has rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, and cerium oxide is preferred from the viewpoint of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant film can be used alone or in combination of two or more types. Examples of liquid dispersion media for the rare earth element oxide sol include various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, and water is preferred. As the cationic polymer, for example, polyethyleneimine, an ionic polymer complex consisting of a polymer having polyethyleneimine and a carboxylic acid, a primary amine grafted acrylic resin in which a primary amine is graft-polymerized to an acrylic main skeleton, polyallylamine or a derivative thereof, aminated phenol, etc. are preferable. As the anionic polymer, poly(meth)acrylic acid or a salt thereof, or a copolymer mainly composed of (meth)acrylic acid or a salt thereof is preferable. Furthermore, it is preferable that the crosslinking agent is at least one selected from the group consisting of a compound having any one of the functional groups of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. Furthermore, it is preferable that the phosphoric acid or the phosphoric acid salt is a condensed phosphoric acid or a condensed phosphate salt.

One example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of the barrier layer and baking the coating at 150°C or higher.

If necessary, the corrosion-resistant coating may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of the cationic polymer and anionic polymer include those described above.

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

The amount of the corrosion-resistant coating formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of performing a coating-type chromate treatment, it is desirable for the chromate compound to be contained in an amount, calculated as chromium, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, per 1 ^m2 of the surface of the barrier layer 3, of a phosphorus compound, calculated as phosphorus, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, and of an aminated phenol polymer, calculated as phosphorus, of about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant film is not particularly limited, but 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, from the viewpoint of the cohesive force of the film and the adhesive force with the barrier layer and the heat-sealable resin layer. The thickness of the corrosion-resistant film 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 energy loss spectroscopy. By analyzing the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry, for example, peaks derived from secondary ions composed of Ce, P, and O (for example, at least one of Ce ₂ PO ₄ ⁺ and CePO ₄ ^- ) or secondary ions composed of Cr, P, and O (for example, at least one of CrPO ₂ ⁺ and CrPO ₄ ^- ) are detected.

The chemical conversion treatment is carried out by applying a solution containing a compound used to form a corrosion-resistant film to the surface of the barrier layer by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then heating the barrier layer so that the temperature of the barrier layer is about 70 to 200°C. In addition, before applying the chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By carrying out the degreasing treatment in this manner, the chemical conversion treatment of the surface of the barrier layer can be carried out more efficiently. In addition, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for the degreasing treatment, it is possible to not only degrease the metal foil but also form a fluoride of the metal, which is a passive state, and in such a case, only the degreasing treatment may be carried out.

[Thermofusible resin layer 4]
In the exterior packaging material for an electricity storage device according to the present disclosure, the heat-sealable resin layer 4 corresponds to the innermost layer, and has the function of sealing the electricity storage device elements by heat-sealing the heat-sealable resin layers to each other when assembling the electricity storage device. It is a layer (sealant layer) that exhibits the above-mentioned properties.

The resin constituting the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but is preferably a resin containing a polyolefin skeleton such as polyolefin or acid-modified polyolefin. The resin constituting the heat-sealable resin layer 4 can be analyzed to contain a polyolefin skeleton, for example, by infrared spectroscopy, gas chromatography mass spectrometry, etc. In addition, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected near the wave number 1760 cm ^-1 and near the wave number 1780 cm ^-1 . When the heat-sealable resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected by infrared spectroscopy. However, if the degree of acid modification is low, the peak may be small and not detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more types.

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

An acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. The polyolefin to be acid-modified may be the above-mentioned polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as a cross-linked polyolefin. In addition, examples of the acid component used for acid modification include carboxylic acids or anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. An acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block-polymerizing or graft-polymerizing an acid component to the cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin described above.

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

The heat-sealable resin layer 4 may be formed of one type of resin alone, or may be formed of a blend polymer of two or more types of resin. Furthermore, the heat-sealable resin layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

The heat-sealable resin layer 4 may also contain a lubricant, etc., if necessary. When the heat-sealable resin layer 4 contains a lubricant, the moldability of the exterior material for the power storage device can be improved. There are no particular limitations on the lubricant, and any known lubricant can be used. The lubricant may be used alone or in combination of two or more types.

The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of the lubricant include those exemplified for the base layer 1. The lubricant may be used alone or in combination of two or more types.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount of the lubricant present is not particularly limited, but from the viewpoint of improving the formability of the exterior material for an electrical storage device, the amount is preferably about ¹⁰ to 50 mg/m2, and more preferably about 15 to 40 mg/ ^m2 .

The lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin that constitutes the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

The thickness of the heat-sealable resin layer 4 is not particularly limited as long as the heat-sealable resin layers are heat-sealed to each other to seal the electricity storage device element, but may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-sealable resin layer 4 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[Adhesive layer 5]
In the packaging material for an electricity storage device according to the present disclosure, the adhesive layer 5 is a layer that is provided, if necessary, between the barrier layer 3 (or the corrosion-resistant coating) and the heat-sealable resin layer 4 in order to firmly bond them together.

The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. The resin used to form the adhesive layer 5 may be, for example, the same adhesive as that exemplified for the adhesive layer 2. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, and examples thereof include the polyolefin and acid-modified polyolefin exemplified for the heat-sealable resin layer 4. The resin constituting the adhesive layer 5 may contain a polyolefin skeleton, for example, by infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. In addition, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of about 1760 cm ^-1 and a wave number of about 1780 cm ^-1 . However, if the degree of acid modification is low, the peak may be small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

From the viewpoint of firmly adhering the barrier layer 3 and the heat-sealable resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred examples of the acid-modified polyolefin include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

Furthermore, from the viewpoint of making the electrical storage device exterior material thin while providing an electrical storage device exterior material with excellent shape stability after molding, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of the acid-modified polyolefin include those mentioned above.

The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group, and is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 is preferably at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As the polyester, for example, an amide ester resin is preferable. Amide ester resins are generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. In addition, if unreacted compounds having an isocyanate group, compounds having an oxazoline group, or curing agents such as epoxy resins remain in the adhesive layer 5, the presence of the unreacted compounds can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), etc.

In order to further increase the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C=N bond, and a C-O-C bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C=N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a C-O-C bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate-based curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions of these, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret forms, and isocyanurates.

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

The compound having an oxazoline group is not particularly limited as long as it has an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. In addition, examples of commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

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

An example of a compound having an epoxy group is an epoxy resin. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the epoxy group present in the molecule, and any known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and even more preferably about 200 to 800. In the first disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. One type of epoxy resin may be used alone, or two or more types may be used in combination.

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

There are no particular limitations on the polyurethane, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component curing polyurethane.

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass % in the resin composition constituting the adhesive layer 5, and more preferably in the range of 0.5 to 40 mass %. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as an electrolyte.

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

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

[Surface coating layer 6]
The exterior material for an electricity storage device according to the present disclosure may, if necessary, have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for an electricity storage device when an electricity storage device is assembled using the exterior material for an electricity storage device.

The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

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

Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curing polyurethanes are used that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Moreover, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Since the surface coating layer 6 is formed from polyurethane, the exterior material for the electricity storage device is endowed with excellent electrolyte resistance.

At least one of the surface and the interior of the surface coating layer 6 may contain additives such as the above-mentioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, depending on the functionality to be provided to the surface of the surface coating layer 6. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median size measured by a laser diffraction/scattering type particle size distribution measuring device.

The additives may be either inorganic or organic. There are also no particular limitations on the shape of the additives, and examples of such shapes include spherical, fibrous, plate-like, amorphous, and scaly.

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

The method for forming the surface coating layer 6 is not particularly limited, and examples include a method of applying a resin that forms the surface coating layer 6. When an additive is added to the surface coating layer 6, a resin mixed with the additive may be applied.

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

3. Manufacturing method of the exterior material for an electric storage device The manufacturing method of the exterior material for an electric storage device is not particularly limited as long as a laminate in which each layer included in the exterior material for an electric storage device of the present disclosure is laminated can be obtained, and an example of such a method includes a step of laminating, in this order from the outside, at least a base layer 1, a barrier layer 3, and a heat-sealable resin layer 4. Specifically, the manufacturing method of the exterior material for an electric storage device of the present disclosure includes a step of obtaining a laminate in which, in this order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer are laminated, the base layer includes a polyamide film, and the crystallization index of the polyamide film measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy is 1.50 or more.

An example of a method for manufacturing an exterior material for a power storage device according to the present disclosure is as follows. First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which a base layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form adhesive layer 2 is applied to base layer 1 or to barrier layer 3, the surface of which has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then dried, and the barrier layer 3 or base layer 1 is laminated thereon to cure adhesive layer 2.

Next, the heat-sealable resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-sealable resin layer 4 is directly laminated on the barrier layer 3, the heat-sealable resin layer 4 may be laminated on the barrier layer 3 of the laminate A by a method such as thermal lamination or extrusion lamination. When an adhesive layer 5 is provided between the barrier layer 3 and the heat-sealable resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them on the barrier layer 3 of the laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and laminating this on the barrier layer 3 of the laminate A by a thermal lamination method, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this with the heat-sealable resin layer 4 by a thermal lamination method. (3) a method in which a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-sealable resin layer 4 previously formed into a sheet, and the laminate A and the heat-sealable resin layer 4 are bonded together via the adhesive layer 5 (sandwich lamination method); (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated on the barrier layer 3 of the laminate A, and then the adhesive is dried or baked, and the heat-sealable resin layer 4 previously formed into a sheet is laminated on the adhesive layer 5.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the substrate layer 1 opposite the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin that forms the surface coating layer 6 to the surface of the substrate layer 1. The order of the step of laminating the barrier layer 3 on the surface of the substrate layer 1 and the step of laminating the surface coating layer 6 on the surface of the substrate layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the substrate layer 1, the barrier layer 3 may be formed on the surface of the substrate layer 1 opposite the surface coating layer 6.

As described above, a laminate is formed that includes, from the outside, an optional surface coating layer 6, a substrate layer 1, an optional adhesive layer 2, a barrier layer 3, an optional adhesive layer 5, and a heat-sealable resin layer 4. In order to strengthen the adhesion of the optional adhesive layer 2 and adhesive layer 5, the laminate may be subjected to a heat treatment.

In the exterior material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as necessary, to improve the suitability for processing. For example, by subjecting the surface of the base layer 1 opposite the barrier layer 3 to corona treatment, the printability of the ink on the surface of the base layer 1 can be improved.

The exterior material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. In other words, an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte can be housed in a package formed from the exterior material for an electricity storage device according to the present disclosure to form an electricity storage device.

Specifically, an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is covered with the exterior material for an electricity storage device of the present disclosure in such a manner that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed on the periphery of the electricity storage device element with the metal terminals connected to each of the positive electrode and negative electrode protruding outward, and the heat-sealable resin layers of the flange portion are heat-sealed to provide an electricity storage device using the exterior material for an electricity storage device. Note that when an electricity storage device element is housed in a package formed from the exterior material for an electricity storage device of the present disclosure, the package is formed so that the heat-sealable resin portion of the exterior material for an electricity storage device of the present disclosure faces inside (the surface in contact with the electricity storage device element).

The exterior material for an electric storage device of the present disclosure can be suitably used for an electric storage device such as a battery (including a condenser, a capacitor, etc.). The exterior material for an electric storage device of the present disclosure may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the exterior material for an electric storage device of the present disclosure is applied is not particularly limited, and examples thereof include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, capacitors, etc. Among these secondary batteries, the exterior material for an electric storage device of the present disclosure is suitably applied to lithium ion batteries and lithium ion polymer batteries.

An electricity storage device is generally fixed to the housing of various products via double-sided tape or adhesive. That is, the exterior material 10 for an electricity storage device disclosed herein is fixed to the housing of various products via double-sided tape or adhesive. The material of the housing varies depending on the type of product, and is diverse, including metals such as stainless steel, aluminum alloy, and nickel alloy, plastics such as polyolefin, polyamide, polyester, polyimide, and polystyrene, and glass.

The adhesive strength between the electricity storage device and the housing is adjusted, for example, to such an extent that the electricity storage device can be peeled off from the housing. The peel strength between the electricity storage device and the housing is preferably fixed using a double-sided tape that has a peel strength against a stainless steel plate of about 5 to 15 N/7.5 mm as measured in the (Measuring the peel strength of double-sided tape) method described below. The exterior material 10 for an electricity storage device can be suitably used for an electricity storage device that is fixed to a housing using a double-sided tape that has a peel strength against the housing of about 5 to 15 N/7.5 mm.

The polyamide film of the present disclosure is a polyamide film for use in a base layer of an electrical storage device exterior material composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer, and has a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy. Details of the electrical storage device exterior material 10 are as described above.

By using the polyamide film of the present disclosure as the base layer 1 of the exterior material for a storage device, the crystallization index of the polyamide film of the base layer 1 of the exterior material for a storage device 10 can be suitably set to 1.50 or more, and the damage of the exterior material for a storage device during the above-mentioned peeling can be effectively suppressed. That is, it is preferable to manufacture the exterior material for a storage device 10 of the present disclosure by using the polyamide film of the present disclosure, the crystallization index of which has been adjusted in advance to 1.50 or more, as the base layer 1 and laminating it with each layer such as the barrier layer 3 and the heat-sealable resin layer 4. As described above, the crystallization index of the polyamide film laminated to the exterior material for a storage device 10 and included in the base layer 1 can be increased compared to the polyamide film before it is applied to the exterior material for a storage device 10. Specifically, the crystallization index can also be increased by applying heat to the polyamide film during the manufacturing process of the exterior material for a storage device 10.

The method for measuring the crystallization index for the polyamide film of the present disclosure is as follows:

<Measurement of Crystallization Index of Polyamide Film>
A polyamide film is cut into a square of 100 mm x 100 mm to prepare a sample. The surface of the obtained sample is subjected to infrared absorption spectrum measurement under an environment of a temperature of 25°C and a relative humidity of 50% using the ATR measurement mode of FT-IR. As an apparatus, for example, a Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, a peak intensity P at about 1200 cm ^-1 resulting from the absorption of α-crystals of nylon and a peak intensity Q at about 1370 cm ^-1 resulting from absorption unrelated to crystals are measured, and the intensity ratio X = P/Q of the peak intensity P to the peak intensity Q is calculated as a crystallization index.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

In the polyamide film of the present disclosure, the crystallization index may be 1.50 or more, but from the viewpoint of more effectively suppressing damage to the electrical storage device exterior material during the aforementioned peeling, it is more preferably 1.55 or more, even more preferably 1.60 or more, and particularly preferably 1.65 or more. There is no particular limit to the upper limit of the crystallization index, but examples of the upper limit include 2.50 or less and 1.80 or less. Preferred ranges of the crystallization index include, for example, 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.50 to 1.80, 1.60 to 1.80, and 1.65 to 1.80.

Specific examples of polyamides that form the polyamide film are as described in the section on the base material layer 1 of the exterior material 10 for a storage battery device. The polyamide film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying resin include roll coating, gravure coating, and extrusion coating.

The polyamide film is preferably a biaxially oriented nylon film.

The thickness of the polyamide film is preferably at least about 3 μm, more preferably at least about 10 μm, and is preferably no more than about 50 μm, more preferably no more than about 35 μm, from the viewpoint of more effectively preventing damage to the exterior material for an electricity storage device during the aforementioned peeling off. Preferred ranges include about 3 to 50 μm, about 3 to 35 μm, about 10 to 50 μm, and about 10 to 35 μm, and of these, about 10 to 35 μm is particularly preferred.

Additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and interior of the polyamide film. Only one type of additive may be used, or two or more types may be mixed and used. Details of the additives are as explained in the section on the base layer 1 of the exterior material 10 for an electrical storage device.

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

<Production of exterior materials for power storage devices>
Examples 1-3 and Comparative Examples 1-2
As the substrate layer, a stretched nylon (ONy) film (thickness 25 μm) was prepared. As described later, the stretched nylon films used in Examples 1-3 and Comparative Examples 1-2 were adjusted to the crystallization index values shown in Table 1 by changing the stretch ratio and heat setting temperature. The stretched nylon film was coated with erucic acid amide as a lubricant. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared. Next, an adhesive (two-liquid urethane adhesive) was applied to one side of the aluminum alloy foil and dried. Next, the adhesive on the barrier layer and the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a substrate layer (thickness 25 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and baking the solution.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 23 μm) and random polypropylene as a heat-sealable resin layer (thickness 23 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on the barrier layer, and aging was performed to obtain a laminate (total thickness 114 μm) in which, from the outside, the substrate layer (thickness 25 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (23 μm)/heat-sealable resin layer (23 μm) were laminated.

Example 4
As the substrate layer, a stretched nylon (ONy) film (thickness 20 μm) was prepared. As described later, the stretched nylon film used in Example 4 was adjusted to the crystallization index shown in Table 1 by changing the stretch ratio and heat setting temperature. The stretched nylon film had a coating layer (a polyester polyurethane containing a lubricant applied to a thickness of 300 nm or less) on the surface opposite to the barrier layer, and a coating layer (a polyester polyurethane applied to a thickness of 300 nm or less) on the surface on the barrier layer side. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 35 μm)) was prepared as the barrier layer. Next, an adhesive (two-liquid urethane adhesive) was applied to one side of the aluminum alloy foil and dried. Next, the adhesive on the barrier layer and the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 35 μm). Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by a roll coating method so that the coating amount of chromium was 10 mg/ ^m2 (dry mass), and baking.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 15 μm) and random polypropylene as a heat-sealable resin layer (thickness 15 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on the barrier layer, and aging was performed to obtain a laminate (total thickness 88 μm) in which, from the outside, the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated.

Example 5
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 5 was the same as that used in Example 4. The oriented nylon film had a coating layer (a polyester polyurethane containing a lubricant applied to a thickness of 300 nm or less) on the surface opposite to the barrier layer, and a coating layer (a polyester polyurethane applied to a thickness of 300 nm or less) on the surface on the barrier layer side. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 30 μm)) was prepared. Next, an adhesive (two-liquid urethane adhesive) was applied to one side of the aluminum alloy foil and dried. Next, the adhesive on the barrier layer and the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 30 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and baking the solution.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on the barrier layer, and aging was performed to obtain a laminate (total thickness 77 μm) in which, from the outside, the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (30 μm)/adhesive layer (14 μm)/heat-sealable resin layer (10 μm) were laminated.

Example 6
A laminate (total thickness 114 μm) having, from the outside, the following laminate structure was obtained in the same manner as in Example 1, except that a stretched nylon (ONy) film having a coating layer (a polyester polyurethane applied to a thickness of 300 nm or less) on the surface on the barrier layer side was used as the base material layer.

Example 7
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 7 was the same as that used in Example 4. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 35 μm)) was prepared. Next, the barrier layer and the substrate layer were laminated by a dry lamination method using an adhesive (a two-liquid type urethane adhesive containing carbon black), and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 35 μm). Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and baking.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 15 μm) and random polypropylene as a heat-sealable resin layer (thickness 15 μm) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer to obtain a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated in that order. Next, a two-liquid urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the obtained laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 91 μm) in which, from the outside, the surface coating layer (thickness 3 μm)/base layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (15 μm)/thermal adhesive resin layer (15 μm) were laminated.

Example 8
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 8 was the same as that used in Example 4. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared. Next, an adhesive (two-liquid type urethane adhesive) was applied to one side of the aluminum alloy foil and dried. Next, the adhesive on the barrier layer and the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and baking the solution.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on the barrier layer, and aging was performed to obtain a laminate (total thickness 87 μm) in which, from the outside, the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (14 μm)/heat-sealable resin layer (10 μm) were laminated.

Example 9
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 9 was the same as that used in Example 4. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared. Next, the barrier layer and the substrate layer were laminated by a dry lamination method using an adhesive (a two-liquid type urethane adhesive containing carbon black), and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 40 μm). Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and baking.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, thereby obtaining a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (14 μm)/heat-sealable resin layer (10 μm) were laminated in that order. Next, a two-liquid urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the obtained laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 90 μm) in which, from the outside, the surface coating layer (thickness 3 μm)/base layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (14 μm)/thermal adhesive resin layer (10 μm) were laminated.

Example 10
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 10 was the same as that used in Example 4. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared. Next, an adhesive (two-liquid urethane adhesive) was applied to one side of the aluminum alloy foil and dried. Next, the adhesive on the barrier layer and the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and baking the solution.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 15 μm) and random polypropylene as a heat-sealable resin layer (thickness 15 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on the barrier layer, and aging was performed to obtain a laminate (total thickness 93 μm) in which, from the outside, the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated.

Example 11
As the substrate layer, an oriented nylon (ONy) film (thickness 20 μm) was prepared. The oriented nylon film used in Example 11 was the same as that used in Example 4. As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared. Next, the barrier layer and the substrate layer were laminated by a dry lamination method using an adhesive (a two-liquid type urethane adhesive containing carbon black), and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 40 μm). Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by a roll coating method so that the amount of chromium applied was 10 mg/m ² (dry mass), and baking.

Next, maleic anhydride modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, thereby obtaining a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated in that order. Next, a two-liquid urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the obtained laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 96 μm) in which, from the outside, the surface coating layer (thickness 3 μm)/base layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (15 μm)/thermal adhesive resin layer (15 μm) were laminated.

<Measurement of Crystallization Index of Base Material Layer of Exterior Material for Electricity Storage Device>
The exterior material for a storage device was cut into a square of 100 mm x 100 mm to prepare a sample. The surface of the stretched nylon film located on the outside of the obtained sample was subjected to infrared absorption spectrum measurement under an environment of a temperature of 25 ° C. and a relative humidity of 50% using the ATR measurement mode of Nicolet iS10 FT-IR manufactured by Thermo Fisher Scientific Co., Ltd. From the obtained absorption spectrum, a peak intensity P at about 1200 cm ^-1 due to the absorption of α crystals of nylon and a peak intensity Q at about 1370 cm ^-1 due to absorption unrelated to crystals were measured, and the intensity ratio X = P / Q of the peak intensity P to the peak intensity Q was calculated as the crystallization index. For Examples 7, 9, and 11, the measurement was performed before applying the surface coating layer. The results are shown in Table 1.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

<Measurement of Crystallization Index of Stretched Nylon Film>
The stretched nylon film used in the base layer of the exterior material for the power storage device was cut into a square of 100 mm x 100 mm to prepare a sample. The surface of the obtained sample was subjected to infrared absorption spectrum measurement under an environment of a temperature of 25 ° C. and a relative humidity of 50% using the ATR measurement mode of Nicolet iS10 FT-IR manufactured by Thermo Fisher Scientific Co., Ltd. From the obtained absorption spectrum, a peak intensity P at about 1200 cm ^-1 due to the absorption of α crystals of nylon and a peak intensity Q at about 1370 cm ^-1 due to absorption unrelated to crystals were measured, and the intensity ratio X = P / Q of the peak intensity P to the peak intensity Q was calculated as the crystallization index. The results are shown in Table 1.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : A value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

<Electricity storage device peeling test>
The peel test of the electricity storage device was carried out according to the following procedure. The following description will be given with reference to Figs. 5 to 8. First, the procedure for preparing a sample used in the peel test of the electricity storage device will be described with reference to Fig. 5. As shown in Fig. 5a, the exterior material for the electricity storage device is cut into a rectangular shape with a length (MD) of 200 mm and a width (TD) of 90 mm. Next, using a molding die (female die) with an aperture of 55 mm (MD) x 32 mm (TD) and a molding die (male die) corresponding to this, the exterior material for the electricity storage device was cold-molded to a depth of 5.0 mm from the heat-sealable resin layer side at a position 15 mm away from the short side of the exterior material for the electricity storage device, to form a recess M (the area surrounded by the dashed line in Fig. 5a). Next, an acrylic plate with a length of 55 mm, a width of 32 mm, and a thickness of 5 mm was inserted into the recess M (Figs. 5b and 5c). Next, the molded exterior material for the power storage device was folded in half in the TD direction at the crease P (the position along the short side of the recess M) so that the recess M was on the inside (FIG. 5d). Next, along the periphery of the recess M, the overlapping portions of the heat-fusible resin layers were heat-sealed (190° C., 3 seconds, surface pressure 1 MPa) at three locations along the MD and TD to seal the recess M (FIG. 5e). In FIG. 5e, the colored area S is the heat-sealed portion. Next, as shown in FIG. 5f, the sample 12 used in the peel test of the power storage device was prepared by trimming the sample 12 to a size of 60 mm in length (MD) and 37 mm in width (TD) along the recess M. FIG. 6 shows a side view (FIG. 6a) and a plan view (FIG. 6b) of the sample 12.

Next, as shown in the schematic diagram of Figure 7, three strips of double-sided tape (7.5 mm wide, 55 mm long) were attached to both ends and the center of the flat surface of sample 12 (the surface opposite to the surface on which the recesses M were formed) along the machine direction (MD). The peel strength of the double-sided tape to the object was measured using the method described below.

Next, the sample 12 with the double-sided tape attached was attached to a stainless steel plate and cured in a 60°C environment for 24 hours. The stainless steel plate was used as a case for fixing the power storage device with the double-sided tape. Next, as shown in the schematic diagram of FIG. 8, the sample 12 was carefully peeled off from the stainless steel plate using a metal spatula, and the presence or absence of holes in the peeled sample 12 was visually confirmed, and the peel test of the power storage device was evaluated for each of three samples according to the following criteria. As shown in FIG. 8, the power storage device was peeled off by applying force from the lateral direction (TD) of the sample 12. The results are shown in Table 1.
A: All three samples were free of holes.
B: One or two samples had holes.
C: All three samples had holes.

The exterior materials for electric storage devices of Examples 1 to 11 are composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, and the base layer includes a polyamide film, and the crystallization index of the polyamide film measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy is 1.50 or more. The polyamide film used in the base layer of the exterior materials for electric storage devices of Examples 1 to 11 also has a crystallization index of 1.50 or more measured by the ATR method of Fourier transform infrared spectroscopy. It can be seen that the exterior materials for electric storage devices of Examples 1 to 11 effectively prevent damage to the exterior materials for electric storage devices when peeling off an electric storage device fixed with double-sided tape or the like from a housing.

The difference between the crystallization index measured for the base layer of the exterior material for electricity storage devices and the crystallization index measured for the stretched nylon film is thought to be due to the aging of the exterior material for electricity storage devices. The stretched nylon film used in Comparative Examples 1 and 2 had a crystallization index value significantly smaller than that of Examples 1 to 11, but the value measured after it was used as the base layer of the exterior material for electricity storage devices was significantly larger than the value measured in the stretched nylon film state. However, in Comparative Examples 1 and 2, the crystallization index of the polyamide film measured from the outside of the base layer could not be increased to 1.50 or more by aging the exterior material for electricity storage devices, and the peel test evaluation of the electricity storage device was inferior to that of Examples 1 to 11.

(Measurement of peel strength of double-sided tape)
The exterior materials for the power storage device of Examples 1 to 11 (15 mm long x 70 mm wide), the double-sided tape (7.5 mm long x 60 mm wide) used in the <Peel test of the power storage device>, aluminum foil (35 μm thick x 15 mm long x 150 mm wide), the double-sided adhesive tape for fixing (5 mm long x 60 mm wide), and the acrylic plate (3 mm thick x 50 mm long x 70 mm wide) were prepared. First, the surface of the stretched nylon film side of the exterior material for the power storage device (the surface of the coating layer on the stretched nylon film in Examples 4 and 5, and the surface of the surface coating layer on the stretched nylon film in Examples 7, 9, and 11) was bonded to one side of the double-sided tape, and aluminum foil was further bonded to the other side of the double-sided tape, and a 2 kg roller was rolled back and forth from above the aluminum foil to obtain a laminate P. Also, the acrylic plate was bonded to one side of the double-sided adhesive tape for fixing to obtain a laminate Q. Furthermore, the surface of the heat-fusible resin layer of the electrical storage device exterior material of the laminate P was attached to the other side of the fixing double-sided adhesive tape of the laminate Q, and pressed down by hand to obtain a laminate R in which an acrylic plate, a fixing double-sided adhesive tape, an electrical storage device exterior material, a double-sided tape, and an aluminum foil were laminated in this order, which was used as a test sample M. The test sample M was stored in an environment at a temperature of 60° C. for 24 hours. Next, the stretched nylon film surface of the electrical storage device exterior material and the end of the double-sided tape were peeled off by about 1 mm to provide a trigger portion for measuring the peel strength. Next, the acrylic plate of test sample M was fixed, and the aluminum foil was pulled using a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)) under conditions of a pulling angle of 180°, a peeling speed of 300 mm/min, and a peeling distance of 50 mm or more, and peeled at the interface between the stretched nylon film surface of the electrical storage device exterior material and the double-sided tape (from the trigger portion described above), and the average of the five peel strengths at peel distances of 10 mm, 20 mm, 30 mm, and 40 mm, and the maximum peel strength between 10 and 40 mm, was calculated to obtain the peel strength (peel strength of the double-sided tape to the stretched nylon film (N/7.5 mm)). The results are shown in Table 2.

Next, a stainless steel plate (3 mm thick x 50 mm long x 70 mm wide) and double-sided tape (7.5 mm long x 60 mm wide), as well as the above-mentioned aluminum foil (35 μm thick x 15 mm long x 150 mm wide) were prepared for use in the <Peel Test of Electricity Storage Device>. The surface of the stainless steel plate was bonded to one side of the double-sided tape, and aluminum foil was then bonded to the other side of the double-sided tape. A 2 kg roller was rolled back and forth once on the aluminum foil to obtain a laminate, which was designated as Test Sample N. Test Sample N was stored in an environment at a temperature of 60°C for 24 hours. Next, the end of the double-sided tape was peeled off about 1 mm from the surface of the stainless steel plate to provide a trigger for measuring the peel strength. Next, the stainless steel plate of test sample N was fixed, and the aluminum foil was pulled using a tensile tester (Shimadzu Corporation, AG-Xplus (product name)) at a pulling angle of 180°, a peeling speed of 300 mm/min, and a peeling distance of 50 mm or more, and peeled at the interface between the stainless steel plate surface and the double-sided tape (from the aforementioned trigger portion). The peel strengths at peel distances of 10 mm, 20 mm, 30 mm, and 40 mm, as well as the maximum peel strength between 10 and 40 mm, were averaged to obtain the peel strength (peel strength of the double-sided tape to the stainless steel plate (N/7.5 mm)). The results are shown in Table 2.

As is clear from the results shown in Table 2, the peel strength of the double-sided tape used in the "energy storage device peel test" was comparable to that of the stretched nylon film and the stainless steel plate.

As described above, the present disclosure provides the following aspects of the invention.
Item 1. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
An exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy.
Item 2. The exterior material for an electricity storage device according to Item 1, further comprising an adhesive layer between the base layer and the barrier layer.
Item 3. The packaging material for an electricity storage device according to Item 1 or 2, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer.
Item 4. The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a heat-sealable resin layer are laminated in this order from the outside,
The substrate layer includes a polyamide film,
A method for producing an exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy.
Item 5. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an electricity storage device according to any one of Items 1 to 3.
Item 6. A polyamide film for use in a base material layer of an exterior material for an electricity storage device, the base material layer being composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer,
The polyamide film has a crystallization index of 1.50 or more as measured by an ATR method of Fourier transform infrared spectroscopy.

REFERENCE SIGNS LIST 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Thermally adhesive resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for power storage device

Claims (33)

The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The exterior material for an electricity storage device, wherein the laminate has a thickness of 120 μm or less. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The exterior material for an electricity storage device, wherein two or more types of lubricants are present on at least one of the surface and the interior of the base layer. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
An exterior material for an electricity storage device, wherein at least two types selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides are present on at least one of the surface and interior of the base layer. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The thermally adhesive resin layer is made of a resin containing a polyolefin skeleton. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The exterior material for an electricity storage device, wherein two or more types of lubricants are present on at least one of the surface and the interior of the heat-sealable resin layer. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The exterior material for an electricity storage device further comprises a coating layer on one or both sides of the base layer . The laminate includes, in order from the outside, at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The exterior material for an electricity storage device, wherein the adhesive layer contains a colorant. The laminate includes, in order from the outside, at least a base layer, a colored layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
An exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy. The laminate includes, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The polyamide film has a thickness of 20 μm. The exterior material for an electricity storage device according to claim 9, wherein the thickness of the barrier layer is 40 μm. The laminate includes, in order from the outside, at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer,
The substrate layer includes a polyamide film,
An exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy. The exterior material for an electricity storage device according to claim 11, wherein at least one of the surface and the interior of the surface coating layer contains titanium oxide. The exterior material for an electricity storage device according to claim 11, wherein at least one of the surface and the interior of the surface coating layer contains silica. The exterior material for a power storage device according to claim 11, wherein at least one of the surface and the interior of the surface coating layer contains kaolin. The exterior material for a power storage device according to claim 11, wherein at least one of the surface and the interior of the surface coating layer contains at least two selected from the group consisting of talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The laminate includes, in order from the outside, at least a surface coating layer, a coating layer, a substrate layer, a barrier layer, and a heat-sealable resin layer.
The substrate layer includes a polyamide film,
An exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy. The exterior material for an electricity storage device according to any one of claims 1 to 16, comprising an adhesive layer between the base layer and the barrier layer. The exterior material for an electricity storage device according to any one of claims 1 to 17, comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. The exterior material for an electricity storage device according to any one of claims 1 to 18, wherein the heat-sealable resin layer contains at least one selected from the group consisting of polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins. The exterior material for an electricity storage device according to any one of claims 1 to 19, wherein the heat-sealable resin layer is formed from a blend polymer that combines two or more types of resin. The exterior material for an electricity storage device according to any one of claims 1 to 20, wherein the heat-sealable resin layer is formed of two or more layers of the same or different resins. a surface coating layer on the opposite side of the base layer to the barrier layer,
The exterior material for an electricity storage device according to any one of claims 1 to 21, wherein a lubricant is present on at least one of the surface and the interior of the surface coating layer. The exterior material for an electric storage device according to claim 22, wherein two or more types of lubricants are present on at least one of the surface and the interior of the surface coating layer. The exterior material for an electricity storage device according to any one of claims 1 to 8 and 11 to 23, wherein the polyamide film has a thickness of 20 μm. The exterior material for an electricity storage device according to claim 24, wherein the thickness of the barrier layer is 40 μm. a surface coating layer on the opposite side of the base layer to the barrier layer,
The exterior material for an electricity storage device according to any one of claims 1 to 10, wherein at least one of a surface and an interior of the surface coating layer contains titanium oxide. a surface coating layer on the opposite side of the base layer to the barrier layer,
The exterior material for an electricity storage device according to any one of claims 1 to 10, wherein at least one of a surface and an interior of the surface coating layer contains silica. a surface coating layer on the opposite side of the base layer to the barrier layer,
The exterior material for an electricity storage device according to any one of claims 1 to 10, wherein at least one of a surface and an interior of the surface coating layer contains kaolin. a surface coating layer on the opposite side of the base layer to the barrier layer,
At least one of the surface and the inside of the surface coating layer includes at least two selected from the group consisting of talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, acrylate resin, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The exterior material for a storage battery device according to any one of claims 1 to 10. The exterior material for an electricity storage device according to any one of claims 1 to 10, comprising a surface coating layer and a coating layer on the side of the substrate layer opposite the barrier layer. The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, an adhesive layer, and a thermally adhesive resin layer are laminated in this order from the outside,
The substrate layer includes a polyamide film,
The crystallization index of the polyamide film measured from the outside of the base layer by an ATR method of Fourier transform infrared spectroscopy is 1.50 or more;
The adhesive layer and the heat-sealable resin layer are formed by a co-extrusion lamination method, a tandem lamination method, a thermal lamination method, a sandwich lamination method, or a method of laminating an adhesive for forming the adhesive layer on the barrier layer, and laminating the heat-sealable resin layer, which has been formed in advance into a sheet shape, on the adhesive layer. An adhesive layer is further provided between the barrier layer and the thermal adhesive resin layer,
The method for producing an exterior material for an electricity storage device according to claim 31 , wherein the heat-sealable resin layer is formed of two or more layers made of the same or different resins. An electricity storage device, comprising: an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte; and the electricity storage device element is housed in a package formed from the exterior material for an electricity storage device according to any one of claims 1 to 30.

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