JP7234794B2 - Exterior material for power storage device, method for producing the same, power storage device, and polyamide film - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to an exterior material for an electricity storage device, a method for manufacturing the same, an electricity storage device, and a polyamide film.

Conventionally, various types of electricity storage devices have been developed, and in all electricity storage devices, an exterior material is an indispensable member for sealing electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been frequently used as exterior materials for power storage devices.

On the other hand, in recent years, as the performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc. has improved, power storage devices are required to have various shapes, and are required to be thinner and lighter. However, conventionally widely used metallic exterior materials for electric storage devices have the drawback that it is difficult to follow the diversification of shapes and that there is a limit to weight reduction.

Therefore, in recent years, a film-like exterior material that can be easily processed into various shapes and that can realize thinness and weight reduction has been developed. Laminates have been proposed (see Patent Document 1, for example).

In such an electric storage device exterior material, generally, a recess is formed by cold molding, and an electric storage device element such as an electrode or an electrolytic solution is placed in the space formed by the recess, and a heat-sealing resin is used. By heat-sealing the layers, an electricity storage device in which an electricity storage device element is accommodated inside the exterior material for an electricity storage device can be obtained.

JP 2008-287971 A

Ingredients such as rare metals are used in electricity storage device elements, and the demand for these ingredients is rapidly increasing. Therefore, in various products such as electrical equipment, it is required to remove the power storage device from the product when replacing the power storage device, and to recover and reuse various components contained in the power storage device elements.

2. Description of the Related Art In various products such as electrical equipment, power storage devices are firmly fixed to product housings with double-sided tape, adhesives, or the like. Therefore, when the power storage device is removed from the housing of the product, a large external force is applied to the power storage device. Specifically, in general, a metal spatula or the like is used to remove the power storage device from the housing, and a large external force is applied to the power storage device. When the electricity storage device is removed, if a large external force is applied to the exterior material for the electricity storage device made of the film-like laminate, the exterior material for the electricity storage device may be damaged.

Under such circumstances, the present disclosure provides an exterior material for an electricity storage device that suppresses damage to the exterior material for an electricity storage device when the electricity storage device fixed to the casing with double-sided tape or the like is peeled off from the casing. The main purpose is to provide

The inventors of the present disclosure conducted extensive studies to solve the above problems. As a result, it is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, the base layer containing a polyamide film, and Fourier transform infrared spectroscopy The exterior material for an electricity storage device, in which the crystallization index of the polyamide film measured by the transmission method of the method is a predetermined value or more, is used when the electricity storage device fixed to the casing with double-sided tape or the like is peeled off from the casing. It has been found that damage to the device exterior material is suppressed.

The present disclosure has been completed through further studies based on these findings. That is, the present disclosure provides inventions in the following aspects.
Consists of a laminate comprising, in order from the outside, at least a substrate layer, a barrier layer, and a heat-fusible resin layer,
The base layer contains a polyamide film,
An exterior material for an electric storage device, wherein the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy.

According to the present disclosure, an electric storage device for an electric storage device in which damage to an electric storage device exterior material is suppressed when an electric storage device fixed to a housing with double-sided tape or the like is peeled off from the housing using a metal spatula or the like. Exterior material can be provided. Further, according to the present disclosure, a method for producing the exterior material for an electricity storage device, an electricity storage device using the exterior material for the electricity storage device, and a polyamide film suitable for use as a base layer of the exterior material for the electricity storage device can also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device of the present disclosure; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device of the present disclosure; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device of the present disclosure; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior material for an electricity storage device of the present disclosure; FIG. 3 is a schematic diagram for explaining a procedure for preparing a sample used for a peeling test of an electricity storage device in Examples. FIG. 4A is a side view (a) and a plan view (b) of a sample used for a peeling test of an electricity storage device in an example. It is the side view (a) and the top view (b) at the time of sticking a double-sided tape to the sample used for the peeling-off test of the electrical storage device in an Example. FIG. 4 is a schematic diagram showing how the electricity storage device is peeled off from the stainless steel plate using a metal spoon in the peeling test of the electricity storage device in the example.

The exterior material for an electricity storage device of the present disclosure is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, and the base layer includes a polyamide film. The polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. In the power storage device exterior material of the present disclosure, damage to the power storage device exterior material is suppressed when the power storage device fixed to the housing with double-sided tape or the like is peeled off from the housing.

Hereinafter, the exterior material for an electricity storage device of the present disclosure will be described in detail. In this specification, the numerical range indicated by "-" means "more than" and "less than". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Laminated Structure and Physical Properties of Electricity Storage Device Exterior Material For example, as shown in FIG. is composed of a laminate comprising In the power storage device exterior material 10, the base material layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When an electricity storage device is assembled using the electricity storage device exterior material 10 and an electricity storage device element, the heat-sealable resin layers 4 of the electricity storage device exterior material 10 face each other, and the peripheral edges are heat-sealed. The electricity storage device element is accommodated in the space formed by . In the laminate constituting the exterior material 10 for an electricity storage device of the present disclosure, the barrier layer 3 is the reference, the heat-fusible resin layer 4 side is inner than the barrier layer 3, and the base layer 1 side is more than the barrier layer 3. outside.

For example, as shown in FIGS. 2 to 4, the electrical storage device exterior material 10 is provided between the base material layer 1 and the barrier layer 3 for the purpose of improving the adhesion between these layers, if necessary. It may have an adhesive layer 2 . For example, as shown in FIGS. 3 and 4, an adhesive layer 5 may optionally be provided between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of enhancing the adhesion between these layers. may have Further, as shown in FIG. 5, a surface coating layer 6 or the like may be provided on the outside of the base material layer 1 (the side opposite to the heat-fusible resin layer 4 side), if necessary.

The thickness of the laminate constituting the power storage device exterior material 10 is not particularly limited, but the upper limit is preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less from the viewpoint of cost reduction, energy density improvement, etc. The lower limit is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more from the viewpoint of maintaining the function of the electricity storage device exterior material to protect the electricity storage device element. , 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 preferable.

The base layer 1 of the power storage device exterior material 10 of the present disclosure contains a polyamide film, and the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. . A method for measuring the crystallization index (transmission method) of a polyamide film is as follows.

<Measurement of crystallization index (transmission method) of polyamide film>
A sample is prepared by cutting a polyamide film into a square of 100 mm×100 mm. Using the FT-IR transmission measurement mode, 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%. As an apparatus, for example, Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, the peak intensity P near 1200 cm ^-1 derived from the absorption of the α-crystal of nylon and the peak strength Q near 1370 cm ^-1 derived from the absorption unrelated to the crystal were measured, and the peak intensity Q The intensity ratio X=P/Q of the peak intensity P to is calculated as the crystallization index. In addition, when obtaining a polyamide film from an electricity storage device or an exterior material for an electricity storage device and measuring the crystallization index of the polyamide film, the electricity storage device is measured from the top or bottom surface, not the heat-sealed portion or side surface of the electricity storage device. A sample is prepared by acquiring the exterior material for the vehicle.
(Measurement condition)
Method: transmission method Wavenumber resolution: 8 cm ^-1
Accumulated times: 32 times Detector: DTGS detector Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

In the polyamide film, the crystallization index (transmission method) may be 1.80 or more, but from the viewpoint of more effectively suppressing damage to the exterior material for an electricity storage device during the above-described peeling off. Therefore, it is more preferably 1.85 or more. Moreover, the upper limit of the crystallization index (by transmission method) is not particularly limited, but examples thereof include 2.50 or less and 2.10 or less. Preferred ranges of the crystallization index include, for example, 1.80 to 2.50, 1.85 to 2.50, 1.80 to 2.10, 1.85 to 2.10.

As a method for increasing the crystallization index (permeation method) of the polyamide film contained in the base material layer 1 of the power storage device exterior material 10 to 1.80 or more, the draw ratio in the production process of the polyamide film, the heat setting temperature, and A method of promoting crystallization (promoting the formation of α-crystals) by changing the temperature and time of post-heating can be mentioned.

In addition, regarding the crystallization index (ATR method) of the base layer of the exterior material for an electricity storage device measured by the ATR method of Fourier transform infrared spectroscopy, the exterior material for an electricity storage device is damaged during the above-mentioned peeling off. From the viewpoint of more effectively suppressing this, it is preferably 1.50 or more, more preferably 1.55 or more, still more preferably 1.60 or more, and particularly preferably 1.65 or more. Moreover, the upper limit of the crystallization index (ATR method) is not particularly limited, but examples thereof include 2.50 or less and 1.80 or less. The method for measuring the crystallization index (ATR method) is as follows. Preferred ranges of the crystallization index are, 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 1.50. 80, 1.65 to 1.80, and the like.

<Measurement of crystallization index (ATR method) of base material layer of exterior material for power storage device>
A sample is prepared by cutting an exterior material for an electricity storage device into a square of 100 mm×100 mm. Using the ATR measurement mode of FT-IR, the surface of the polyamide film located outside 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%. As an apparatus, for example, Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, the peak intensity P near 1200 cm ^-1 derived from the absorption of the α-crystal of nylon and the peak strength Q near 1370 cm ^-1 derived from the absorption unrelated to the crystal were measured, and the peak intensity Q The intensity ratio X=P/Q of the peak intensity P to is calculated as the crystallization index. In addition, when the power storage device exterior material is obtained from the power storage device and the crystallization index of the base material layer is measured, the power storage device exterior material is measured from the top surface or bottom surface, not the heat-sealed portion or side surface of the power storage device. Obtain the material and prepare the sample.
(Measurement condition)
Method: Macro ATR method Wave number resolution: 8 cm ^-1
Accumulation times: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

When the outer surface of the power storage device exterior material 10 is composed of the polyamide film of the base material layer 1, the power storage device exterior material 10 can be used as it is for the measurement of the crystallization index (ATR method). can be done. Further, when the base material layer 1 has a multilayer structure as described later, and a resin film different from the polyamide film (for example, a polyester film) is positioned outside the polyamide film, or when the base material layer 1 When the outer surface of the power storage device exterior material 10 is not composed of the polyamide film of the base material layer 1, such as when the surface coating layer 6 described later is laminated on the outside, it is positioned outside the polyamide film. The crystallization index (ATR method) can be measured in a state in which the layer is removed from the electrical storage device exterior material 10 to expose the surface of the polyamide film.

As a method for increasing the crystallization index (ATR method) of the polyamide film contained in the base material layer 1 of the power storage device exterior material 10 to 1.50 or more, the draw ratio in the production process of the polyamide film, the heat setting temperature, A method of promoting crystallization (promoting the formation of α-crystals) by changing the temperature and time of post-heating can be mentioned.

2. Each layer forming the exterior material for the electricity storage device [base layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exhibiting a function as a base material of an exterior material for an electric storage device. The base material layer 1 is located on the outer layer side of the exterior material for electrical storage devices.

The base material layer 1 contains a polyamide film. As described above, the crystallization index of the polyamide film measured by the transmission method of Fourier transform infrared spectroscopy is 1.80 or more.

Polyamides that form the polyamide film may be those 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. mentioned. These polyamides may be used singly or in combination of two or more. Preferably, the polyamide film is a nylon film.

The polyamide film may be an unstretched film or a stretched film. When the base material layer 1 contains an unstretched film, when laminating each layer of the exterior material 10 for an electric storage device, the unstretched film may be formed by extrusion, or an unstretched film prepared in advance may be laminated. Alternatively, a resin (polyamide) may be applied to form an unstretched film. Methods for applying the resin include a roll coating method, a gravure coating method, an extrusion coating method, and the like. Moreover, when the base material layer 1 is a stretched film, when laminating|stacking each layer of the exterior material 10 for electrical storage devices, the stretched film prepared previously is bonded together. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include successive biaxial stretching, inflation, and simultaneous biaxial stretching.

The polyamide film is particularly preferably a biaxially oriented nylon film.

In the power storage device exterior material 10 of the present disclosure, a polyamide film having a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy may be used as the base layer 1 to produce it. Alternatively, the crystallization index can be increased to 1.80 or more by applying heat to the polyamide film during the manufacturing process of the power storage device exterior material 10 . Polyamide film” described later, in the power storage device exterior material 10 of the present disclosure, the crystallization index (transmission method) measured by the transmission method of Fourier transform infrared spectroscopy is 1. It is preferable that the substrate layer 1 be manufactured using a polyamide film having a viscosity of 0.80 or more. That is, by using a polyamide film whose crystallization index (permeation method) has been adjusted to 1.80 or more in advance as the base material layer 1 and laminating it with each layer such as the barrier layer 3 and the heat-fusible resin layer 4 , it is preferable to manufacture the power storage device exterior material 10 of the present disclosure. In addition, as shown in the examples below, the polyamide contained in the base material layer 1 laminated on the power storage device exterior material 10 is more than the polyamide film before being applied to the power storage device exterior material 10. The crystallization index (transmission method) of the film can be increased.

The thickness of the polyamide film is preferably about 3 μm or more, more preferably about 10 μm or more, from the viewpoint of more effectively suppressing breakage of the power storage device exterior material when peeled off as described above. , preferably about 50 μm or less, more preferably about 35 μm or less. degree is particularly preferred.

The base material layer 1 may further have a resin film different from the polyamide film. Resins that form resin films different from polyamide films include, for example, polyesters, polyolefins, epoxy resins, acrylic resins, fluororesins, polyurethanes, silicon resins, phenolic resins, and modified products of these resins. . Further, the resin may 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 preferred.

Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester. Examples of copolyester include copolyester having ethylene terephthalate as a main repeating unit. Specifically, copolymer polyester polymerized with ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated after polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), polyethylene (terephthalate/decanedicarboxylate), and the like. These polyesters may be used singly 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 particularly preferably a biaxially stretched polyethylene terephthalate film or a biaxially stretched polybutylene terephthalate film.

When the substrate layer 1 further has a resin film different from 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, preferably about 3 μm or more, or more. It is preferably about 10 μm or more, more preferably about 50 μm or less, more preferably about 35 μm or less, and the preferable range is about 3 to 50 μm, about 3 to 35 μm, about 10 to 50 μm, and about 10 to 35 μm. Among these, a thickness of about 10 to 35 μm is particularly preferable.

As long as the base layer 1 contains a polyamide film, it may be a single layer or may be composed of two or more layers. A single layer is preferred.

When the substrate layer 1 is composed of two or more layers, the substrate layer 1 may be a laminate obtained by laminating resin films with an adhesive or the like, or may be formed by co-extrusion of resin to form two or more layers. It may also be a laminate of resin films. A laminate of two or more resin films formed by coextrusion of resin may be used as the base material layer 1 without being stretched, or may be used as the base material layer 1 by being uniaxially or biaxially stretched.

Specific examples of the laminate of two or more resin films in the substrate layer 1 include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, etc., preferably stretched nylon. A laminate of a film and a stretched polyester film, and a laminate of two or more layers of stretched nylon films are preferred. For example, when the substrate 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 preferable, and a nylon film and a nylon film are preferably used. A laminate or a laminate of a polyethylene terephthalate film and a nylon film is more preferable. In addition, the polyester resin is resistant to discoloration when, for example, an electrolytic solution adheres to the surface. It is preferably located in the outermost layer.

When the substrate layer 1 is a laminate of two or more layers of resin films, the two or more layers of resin films may be laminated via an adhesive. Preferred adhesives are the same as those exemplified for the adhesive layer 2 described later. The method for laminating two or more layers of resin films is not particularly limited, and known methods can be employed. Examples thereof include dry lamination, sandwich lamination, extrusion lamination, thermal lamination, and the like. A lamination method is mentioned. When laminating by dry lamination, it is preferable to use a polyurethane adhesive as the adhesive. At this time, 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. As the anchor coat layer, the same adhesives as those exemplified in the adhesive layer 2 described later can be used. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

At least one of the surface and the inside of the substrate layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. good. Only one type of additive may be used, or two or more types may be mixed and used.

In the present disclosure, it is preferable that a lubricant exists on the surface of the base material layer 1 from the viewpoint of improving the moldability of the exterior material for an electricity storage device. The lubricant is not particularly limited, but preferably includes an amide-based lubricant. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide and the like. Further, specific examples of methylolamide include methylol stearamide. Specific examples of saturated fatty acid bisamides include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearin. acid amide, hexamethylenebisbehenamide, hexamethylenehydroxystearic acid amide, N,N'-distearyladipic acid amide, N,N'-distearylsebacic acid amide and the like. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide, ethylenebiserucic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleylsebacic acid amide. etc. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Further, specific examples of the aromatic bisamide include m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide and the like. Lubricants may be used singly or in combination of two or more.

When a lubricant exists on the surface of the base material layer 1, its amount is not particularly limited, but is preferably about 3 mg/m ² or more, more preferably about 4 to 15 mg/m ² , and still more preferably 5 to 14 mg. / m ² degree.

The lubricant present on the surface of the substrate layer 1 may be obtained by exuding the lubricant contained in the resin constituting the substrate layer 1, or by coating the surface of the substrate layer 1 with the lubricant. may

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

[Adhesive layer 2]
In the power storage device exterior material of the present disclosure, the adhesive layer 2 is a layer provided between the base layer 1 and the barrier layer 3 as necessary for the purpose of enhancing the adhesiveness between them.

The adhesive layer 2 is made of an adhesive capable of bonding the base material layer 1 and the barrier layer 3 together. The adhesive used to form the adhesive layer 2 is not limited, but may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, and the like. Further, it may be a two-liquid curing adhesive (two-liquid adhesive), a one-liquid curing adhesive (one-liquid adhesive), or a resin that does not involve a curing reaction. Further, the adhesive layer 2 may be a single layer or multiple layers.

Specific examples of the adhesive component contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether; polyurethane; epoxy resin; Phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimide; polycarbonate; amino resin such as urea resin and melamine resin; rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; These adhesive components may be used singly or in combination of two or more. Among these adhesive components, polyurethane adhesives are preferred. In addition, an appropriate curing agent can be used in combination with these adhesive component resins to increase the adhesive strength. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of polyurethane adhesives include polyurethane adhesives containing a main agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing type polyurethane adhesives using polyols such as polyester polyols, polyether polyols, and acrylic polyols as main agents and aromatic or aliphatic polyisocyanates as curing agents are preferred. Moreover, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in a side chain in addition to the terminal hydroxyl group of the repeating unit. Since the adhesive layer 2 is formed of a polyurethane adhesive, the exterior material for an electric storage device is imparted with excellent electrolyte resistance, and even if the electrolyte adheres to the side surface, the base layer 1 is suppressed from being peeled off. .

Further, the adhesive layer 2 may contain other components as long as they do not impede adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. Since the adhesive layer 2 contains a coloring agent, the exterior material for an electric storage device can be colored. Known substances such as pigments and dyes can be used as the colorant. In addition, only one type of colorant may be used, or two or more types may be mixed and used.

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-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments. Examples of pigments include carbon black, titanium oxide, cadmium, lead, chromium oxide, and iron pigments, as well as fine powder of mica and fish scale foil.

Among the coloring agents, carbon black is preferable, for example, in order to make the external appearance of the exterior material for an electric storage device black.

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

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the power storage device exterior material is colored, and is, for example, about 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as the substrate layer 1 and the barrier layer 3 can be adhered. , about 5 μm or less, and preferable ranges include 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 provided as necessary between the base layer 1 and the barrier layer 3 (not shown). When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2 and between the adhesive layer 2 and the barrier layer 3 . Further, a colored layer may be provided outside the base material layer 1 . By providing the colored layer, the exterior material for an electricity storage device can be colored.

The colored layer can be formed, for example, by applying ink containing a coloring agent to the surface of the substrate layer 1, the adhesive layer 2, or the barrier layer 3. Known substances such as pigments and dyes can be used as the colorant. In addition, only one type of colorant may be used, or two or more types may be mixed and used.

Specific examples of the colorant contained in the colored layer are the same as those exemplified in the section [Adhesive layer 2].

[Barrier layer 3]
In the power storage device exterior material, the barrier layer 3 is a layer that at least prevents permeation of moisture.

As the barrier layer 3, for example, a metal foil, a deposited film, a resin layer, or the like having barrier properties can be used. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, fluorine-containing resins such as polymers containing fluoroalkyl units as a main component, and ethylene vinyl alcohol copolymers. The barrier layer 3 may also include a resin film provided with at least one of these deposited films and resin layers. A plurality of barrier layers 3 may be provided. The barrier layer 3 preferably includes a layer made of a metal material. Specific examples of the metal material that constitutes the barrier layer 3 include aluminum alloys, stainless steels, titanium steels, and steel plates. When used as a metal foil, at least one of an aluminum alloy foil and a stainless steel foil is included. is preferred.

The aluminum alloy foil is more preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, from the viewpoint of improving the formability of the exterior material for an electricity storage device, and from the viewpoint of further improving the formability. Therefore, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain an exterior material for an electricity storage device having superior moldability. When the iron content is 9.0% by mass or less, it is possible to obtain an exterior material for an electricity storage device that is more excellent in flexibility. As the soft aluminum alloy foil, for example, JIS H4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000: 2014 A8021P-O, or an aluminum alloy having a composition specified by JIS H4000: 2014 A8079P-O foil. Moreover, silicon, magnesium, copper, manganese, etc. may be added as needed. Moreover, softening can be performed by annealing treatment or the like.

Examples of stainless steel foils include austenitic, ferritic, austenitic/ferritic, martensitic, and precipitation hardened stainless steel foils. Furthermore, from the viewpoint of providing an exterior material for an electricity storage device with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferable.

The thickness of the barrier layer 3, in the case of a metal foil, is sufficient to exhibit at least the function of a barrier layer that prevents permeation of moisture, and is, for example, about 9 to 200 μm. Regarding the thickness of the barrier layer 3, for example, the upper limit is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. 10 μm or more, more preferably about 20 μm or more, more preferably about 25 μm or more. about 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, and among these, about 25 to 40 μm is particularly preferred. preferable. When the barrier layer 3 is made of an aluminum alloy foil, the above 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, and even more preferably about 40 μm or less. It is more preferably about 30 μm or less, 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. about 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.

Moreover, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite to the base material 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 coating on both sides. Here, the corrosion-resistant film includes, for example, hydrothermal transformation treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel and chromium, and corrosion prevention treatment such as applying a coating agent to the surface of the barrier layer. A thin film that provides corrosion resistance to the barrier layer. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be used in combination. Also, not only one layer but also multiple layers can be used. Furthermore, among these treatments, the hydrothermal transformation treatment and the anodizing treatment are treatments in which the surface of the metal foil is dissolved with a treating agent to form a metal compound having excellent corrosion resistance. These treatments are sometimes included in the definition of chemical conversion treatment. When the barrier layer 3 has a corrosion-resistant film, the barrier layer 3 includes the corrosion-resistant film.

The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during the molding of the exterior material for power storage devices, and the hydrogen fluoride generated by the reaction between the electrolyte and moisture. , the dissolution and corrosion of the barrier layer surface, especially when the barrier layer is an aluminum alloy foil, the aluminum oxide present on the barrier layer surface is prevented from dissolving and corroding, and the adhesion (wettability) of the barrier layer surface is improved. , and exhibits the effect of preventing delamination between the base material layer and the barrier layer during heat sealing and preventing delamination between the base material layer and the barrier layer during molding.

Various types of corrosion-resistant coatings formed by chemical conversion treatment are known, and are mainly composed of at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. and corrosion-resistant coatings containing. Examples of chemical conversion treatments using phosphate and chromate include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment. Examples of compounds include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromium acetyl acetate, chromium chloride, potassium chromium sulfate, and the like. Phosphorus compounds used for these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, and the like. Examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating-type chromate treatment, etc., and coating-type chromate treatment is preferred. In this coating-type chromate treatment, at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) is first subjected to a well-known method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, or the like. After degreasing by a treatment method, metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (zinc) phosphate is applied to the degreased surface. A processing solution mainly composed of a salt and a mixture of these metal salts, a processing solution mainly composed of a non-metal phosphate salt and a mixture of these non-metal salts, or a mixture of these and a synthetic resin. This is a treatment in which a treatment liquid composed of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method, or an immersion method, and then dried. Various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents can be used as the treatment liquid, and water is preferred. In addition, the resin component used at this time includes polymers such as phenolic resins and acrylic resins. and the chromate treatment used. In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained singly or in any combination of two or more. good too. The acrylic resin is polyacrylic acid, acrylic acid methacrylic acid ester copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, and amine salts. is preferred. In particular, derivatives of polyacrylic acid such as ammonium salt, sodium salt or amine salt of polyacrylic acid are preferred. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Further, the acrylic resin is preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, and the ammonium salt, sodium salt, Alternatively, it is also preferably an amine salt. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

In general formulas (1) to (4), X represents a hydrogen atom, hydroxy group, alkyl group, hydroxyalkyl group, allyl group or benzyl group. R ¹ and R ² are the same or different and represent a hydroxy group, an alkyl group or a hydroxyalkyl group. Examples of alkyl groups represented by X, R ¹ and R ² in general formulas (1) to (4) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, A linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group can be mentioned. Examples of hydroxyalkyl groups represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3- A straight or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group and 4-hydroxybutyl group An alkyl group is mentioned. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by formulas (1) to (4) is, for example, preferably about 500 to 1,000,000, more preferably about 1,000 to 20,000. more preferred. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound and formaldehyde to produce a polymer comprising repeating units represented by the general formula (1) or general formula (3), followed by formaldehyde. and an amine (R ¹ R ² NH) to introduce a functional group (--CH ₂ NR ¹ R ² ) into the polymer obtained above. An aminated phenol polymer is used individually by 1 type or in mixture of 2 or more types.

Another example of the corrosion-resistant film is 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. A thin film that is The coating agent may further contain phosphoric acid or a phosphate, a cross-linking agent for cross-linking the polymer. In the rare earth element oxide sol, rare earth element oxide fine particles (for example, particles having an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, and cerium oxide is preferable from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used singly or in combination of two or more. As the liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, with water being preferred. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of a polymer containing polyethyleneimine and carboxylic acid, a primary amine-grafted acrylic resin obtained by graft-polymerizing a primary amine to an acrylic backbone, polyallylamine, or a derivative thereof. , aminated phenols and the like are preferred. The anionic polymer is preferably poly(meth)acrylic acid or a salt thereof, or a copolymer containing (meth)acrylic acid or a salt thereof as a main component. Moreover, the cross-linking agent is preferably at least one selected from the group consisting of a compound having a functional group such as an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. Further, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

As an example of the corrosion-resistant film, fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, and barium sulfate are dispersed in phosphoric acid, which is applied to the surface of the barrier layer. C. or more, and those formed by performing baking processing are mentioned.

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

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

The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment ^is not particularly limited. is about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of chromium, the phosphorus compound is about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of phosphorus, and aminated phenol polymer is contained in a ratio of, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm, from the viewpoint of cohesion of the coating and adhesion to the barrier layer and the heat-sealable resin layer. about 1 nm to 50 nm, more preferably about 1 nm to 50 nm. 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 beam energy loss spectroscopy. By analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions composed of Ce, P and O (for example, at least one of Ce ₂ PO ₄ ⁺ and CePO ₄ ⁻ species) and, for example, secondary ions composed of Cr, P, and O (eg, at least one of CrPO ₂ ⁺ and CrPO ₄ ⁻ ) are detected.

Chemical conversion treatment involves 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, roll coating method, gravure coating method, immersion method, etc., and then changing the temperature of the barrier layer. is carried out by heating so that the temperature is about 70 to 200°C. In addition, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be previously subjected to a degreasing treatment by an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this way, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. In addition, by using an acid degreasing agent obtained by dissolving a fluorine-containing compound in an inorganic acid for degreasing treatment, it is possible to form not only the degreasing effect of the metal foil but also the passive metal fluoride. In such cases, only degreasing treatment may be performed.

[Heat-fusible resin layer 4]
In the power storage device exterior material of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and has the function of sealing the power storage device element by heat-sealing the heat-fusible resin layers to each other when assembling the power storage device. It is a layer (sealant layer) that exhibits

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing polyolefin skeletons such as polyolefins and acid-modified polyolefins are preferable. The inclusion of a polyolefin skeleton in the resin constituting the heat-fusible resin layer 4 can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Further, when the resin constituting the heat-fusible 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, peaks derived from maleic anhydride are detected near wavenumbers of 1760 cm ⁻¹ and 1780 cm ⁻¹ . In the case where the heat-fusible resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid denaturation is low, the peak may be too small to be 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; block copolymers of ethylene), random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; 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-based resins may be used alone or in combination of two or more.

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

Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the above polyolefin, a copolymer obtained by copolymerizing the above polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as crosslinked polyolefin can be used. Examples of acid components used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride and itaconic anhydride, and anhydrides thereof.

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

Preferred acid-modified polyolefins include carboxylic acid- or anhydride-modified polyolefins, carboxylic acid- or anhydride-modified polypropylenes, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

The heat-fusible resin layer 4 may be formed of one type of resin alone, or may be formed of a blend polymer in which two or more types of resin are combined. Furthermore, the heat-fusible 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.

Moreover, the heat-fusible resin layer 4 may contain a lubricant or the like as necessary. When the heat-fusible resin layer 4 contains a lubricant, it is possible to improve the moldability of the power storage device exterior material. The lubricant is not particularly limited, and known lubricants can be used. Lubricants may be used singly or in combination of two or more.

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

When a lubricant exists on the surface of the heat-sealable resin layer 4, the amount of the lubricant is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for an electricity storage device, the amount is preferably about 10 to 50 mg/m ² . , and more preferably about 15 to 40 mg/m ² .

The lubricant present on the surface of the heat-fusible resin layer 4 may be obtained by exuding the lubricant contained in the resin constituting the heat-fusible resin layer 4 . The surface may be coated with a lubricant.

The thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers are heat-sealed to each other to exhibit the function of sealing the electricity storage device element. About 85 μm or less, more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm. When the thickness of the adhesive layer 5 described later is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 is preferably about 20 μm or more, more preferably 35 to 85 μm. degree.

[Adhesion layer 5]
In the power storage device exterior material of the present disclosure, the adhesive layer 5 is provided between the barrier layer 3 (or the acid-resistant film) and the heat-fusible resin layer 4 as necessary in order to firmly bond them. layer.

The adhesive layer 5 is made of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4 together. As the resin used for forming the adhesive layer 5, for example, the same adhesives as those exemplified for the adhesive layer 2 can be used. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, and includes the polyolefins and acid-modified polyolefins exemplified for the heat-fusible resin layer 4 described above. Whether the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. Further, when the resin forming the adhesive layer 5 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, peaks derived from maleic anhydride are detected near wavenumbers of 1760 cm ⁻¹ and 1780 cm ⁻¹ . However, if the degree of acid denaturation is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

From the viewpoint of firmly bonding the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred acid-modified polyolefins are polyolefins modified with carboxylic acid or its anhydride, polypropylene modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefin, and maleic anhydride-modified polypropylene.

Furthermore, from the viewpoint of making the power storage device exterior material excellent in shape stability after molding while reducing the thickness of the power storage device exterior material, the adhesive layer 5 is made of a resin composition containing an acid-modified polyolefin and a curing agent. is more preferably a cured product of Preferred examples of the acid-modified polyolefin include those mentioned above.

Further, the adhesive layer 5 is a cured product of a resin composition containing 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. 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 is particularly preferred. Moreover, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As the polyester, for example, an amide ester resin is preferable. Amide ester resins are generally produced by the reaction of carboxyl groups and oxazoline groups. More preferably, the adhesive layer 5 is a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. In the case where the adhesive layer 5 contains an isocyanate group-containing compound, an oxazoline group-containing compound, or an unreacted product of a curing agent such as an epoxy resin, the presence of the unreacted product can be detected by, for example, infrared spectroscopy, It can be confirmed by a method selected from Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

In addition, from the viewpoint of further increasing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 contains at least It is preferably a cured product of a resin composition containing one curing agent. The curing agent having a heterocyclic ring includes, for example, a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. Moreover, the curing agent having a C═N bond includes a curing agent having an oxazoline group, a curing agent having an isocyanate group, and the like. Further, examples of curing agents having a C—O—C bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethanes. The adhesive layer 5 is a cured product of a resin composition containing these curing agents, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF -SIMS) and X-ray photoelectron spectroscopy (XPS).

The isocyanate group-containing compound is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the barrier layer 3 and the adhesive layer 5, polyfunctional isocyanate compounds are preferred. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerization and nurate compounds, mixtures thereof, copolymers with other polymers, and the like. In addition, adducts, burettes, isocyanurates and the like are included.

The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, more preferably 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. A range is more preferred. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

The compound having an oxazoline group is not particularly limited as long as it is a compound having 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. Moreover, as a commercial item, the Epocross series by Nippon Shokubai Co., Ltd. etc. are mentioned, for example.

The ratio of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5. is more preferable. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

Examples of compounds having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure with epoxy groups present in the molecule, and known epoxy resins can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, still 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, novolak glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, and the like. An epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more types.

The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5. is more preferred. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

Polyurethane is not particularly limited, and known polyurethanes can be used. The adhesive layer 5 may be, for example, a cured product of two-component curing type polyurethane.

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5. more preferred. As a result, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced in an atmosphere containing a component that induces corrosion of the barrier layer, such as an electrolytic solution.

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. , about 0.5 μm or more, and 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, 0 .1 to 5 μm, 0.5 to 50 μm, 0.5 to 40 μm, 0.5 to 30 μm, 0.5 to 20 μm, and 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified for the adhesive layer 2 or the cured product of acid-modified polyolefin and curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. In the case of using the resin exemplified for the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified for the adhesive layer 2 or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, for example, the resin composition is applied and cured by heating or the like. Thus, the adhesive layer 5 can be formed. Further, when using the resin exemplified for the heat-fusible resin layer 4, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example.

[Surface coating layer 6]
For the purpose of at least one of improving design, electrolyte resistance, scratch resistance, moldability, etc., the exterior material for an electricity storage device of the present disclosure is provided on the base layer 1 (base layer 1 (the side opposite to the barrier layer 3) may be provided with a surface coating layer 6. The surface coating layer 6 is a layer positioned 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 of resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, and epoxy resin, for example.

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, preferably the two-component curable type. Examples of the two-liquid curing resin include two-liquid curing polyurethane, two-liquid curing polyester, and two-liquid curing epoxy resin. Among these, two-liquid curable polyurethane is preferred.

Examples of two-liquid curable polyurethanes include polyurethanes containing a main agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferable examples include two-component curing type polyurethanes using polyols such as polyester polyols, polyether polyols, and acrylic polyols as main agents and aromatic or aliphatic polyisocyanates as curing agents. Moreover, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in a side chain in addition to the terminal hydroxyl group of the repeating unit. Since the surface coating layer 6 is made of polyurethane, the exterior material for an electric storage device is imparted with excellent electrolyte resistance.

At least one of the surface and the inside of the surface coating layer 6 may be coated with the above-described lubricant or anti-rust agent as necessary depending on the functionality to be provided on the surface coating layer 6 and its surface. Additives such as blocking agents, matting agents, flame retardants, antioxidants, tackifiers and antistatic agents may be included. Examples of the additive include fine particles having an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median size measured with a laser diffraction/scattering particle size distribution analyzer.

Additives may be either inorganic or organic. Also, the shape of the additive is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, scale-like, and the like.

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, and 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 nanotube, high melting point nylon, acrylate resin, Crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, and the like. Additives may be used singly or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, the additive may be subjected to various surface treatments such as insulation treatment and high-dispersion treatment.

A method for forming the surface coating layer 6 is not particularly limited, and an example thereof includes a method of applying a resin for forming the surface coating layer 6 . When adding additives to the surface coating layer 6, a resin mixed with the additives may be applied.

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

3. Method for producing an exterior material for an electricity storage device The method for producing an exterior material for an electricity storage device is not particularly limited as long as a laminate obtained by laminating each layer included in the exterior material for an electricity storage device of the present disclosure is obtained. At least, a method including a step of laminating the substrate layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order can be mentioned. Specifically, the method for producing an exterior material for an electricity storage device of the present disclosure includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order from the outside. The base layer contains a polyamide film, and the polyamide film has a crystallization index (transmission method) of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy.

An example of the method for manufacturing the exterior material for an electricity storage device of the present disclosure is as follows. First, a layered body (hereinafter also referred to as "layered body A") is formed by laminating a substrate layer 1, an adhesive layer 2, and a barrier layer 3 in this order. Specifically, the laminate A is formed by applying an adhesive used for forming the adhesive layer 2 on the substrate layer 1 or on the barrier layer 3 whose surface is chemically treated as necessary, by a gravure coating method, It can be performed by a dry lamination method in which the barrier layer 3 or the substrate layer 1 is laminated and the adhesive layer 2 is cured after coating and drying by a coating method such as a roll coating method.

Next, on the barrier layer 3 of the laminate A, the heat-fusible resin layer 4 is laminated. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A by a method such as thermal lamination or extrusion lamination. do it. When the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) the adhesive layer 5 and the heat-fusible resin layer are placed on the barrier layer 3 of the laminate A. 4 (co-extrusion lamination method, tandem lamination method); A method of laminating on the barrier layer 3 of the laminate A by a thermal lamination method, or forming a laminate in which an adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this with a heat-fusible resin layer 4 by a thermal lamination method Lamination method (3) While pouring the melted adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 formed into a sheet in advance, the adhesive layer 5 is interposed. (4) coating the barrier layer 3 of the laminate A with an adhesive for forming the adhesive layer 5 in solution, A drying method, a baking method, or the like is used to laminate the adhesive layer 5 , and a heat-fusible resin layer 4 that has been formed into a sheet in advance is laminated on the adhesive layer 5 .

When providing the surface coating layer 6 , the surface coating layer 6 is laminated on the surface of the substrate layer 1 opposite to the barrier layer 3 . The surface coating layer 6 can be formed, for example, by coating the surface of the substrate layer 1 with the above-described resin for forming the surface coating layer 6 . The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the substrate layer 1 , the barrier layer 3 may be formed on the surface of the substrate layer 1 opposite to the surface coating layer 6 .

As described above, in order from the outside, surface coating layer 6 provided as necessary/base material layer 1/adhesive layer 2 provided as needed/barrier layer 3/adhesive layer 5 provided as needed / A laminate including the heat-fusible resin layer 4 is formed, but in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, it may be subjected to heat treatment. good.

In the exterior material for an electricity storage device, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blasting treatment, oxidation treatment, and ozone treatment to improve processability as necessary. . For example, by subjecting the surface of the substrate layer 1 opposite to the barrier layer 3 to corona treatment, the printability of the ink onto the surface of the substrate layer 1 can be improved.

4. Use of Power Storage Device Exterior Material The power storage device exterior material of the present disclosure is used in a packaging body for sealingly housing power storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an electricity storage device can be obtained by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed by the electricity storage device exterior material of the present disclosure.

Specifically, an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is placed in the exterior material for an electricity storage device of the present disclosure in a state in which metal terminals connected to the positive electrode and the negative electrode protrude outward. , covering the periphery of the electricity storage device element so as to form a flange portion (area where the heat-fusible resin layers contact each other), and heat-sealing the heat-fusible resin layers of the flange portion to seal. provides an electricity storage device using an exterior material for an electricity storage device. In addition, when housing an electricity storage device element in a package formed by the electricity storage device exterior material of the present disclosure, the heat-fusible resin portion of the electricity storage device exterior material of the present disclosure is on the inside (surface in contact with the electricity storage device element ) to form a package.

The power storage device exterior material of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Moreover, although the exterior material for an electricity storage device of the present disclosure may be used for either a primary battery or a secondary battery, it is preferably a secondary battery. The type of secondary battery to which the power storage device exterior material of the present disclosure is applied is not particularly limited. Cadmium storage batteries, nickel/iron storage batteries, nickel/zinc storage batteries, silver oxide/zinc storage batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries can be mentioned as suitable targets for application of the power storage device exterior material of the present disclosure.

Electricity storage devices are generally fixed to housings of various products via double-sided tapes or adhesives. That is, the power storage device exterior material 10 of the present disclosure is fixed to housings of various products via a double-sided tape or an adhesive. The material of the housing varies depending on the type of product, and includes a wide variety of materials such as metals such as stainless steel, aluminum alloys and nickel alloys, plastics such as polyolefins, polyamides, polyesters, polyimides and polystyrenes, and glass.

Also, the adhesive strength between the power storage device and the housing is adjusted, for example, to such an extent that the power storage device can be peeled off from the housing. For the peel strength between the power storage device and the housing, for example, a double-sided tape is used such that the peel strength against a stainless steel plate measured in (Measurement of peel strength of double-sided tape) described later is about 5 to 15 N / 7.5 mm. It is preferably fixed The electric storage device exterior material 10 can be suitably used for an electric storage device fixed to a housing with a double-faced tape having a peel strength of about 5 to 15 N/7.5 mm.

5. Polyamide film The polyamide film of the present disclosure is a polyamide film for use as a base layer of an exterior material for an electric storage device, which is composed of a laminate including at least a base layer, a barrier layer, and a heat-fusible resin layer. and the crystallization index (transmission method) measured by the transmission method of Fourier transform infrared spectroscopy is 1.80 or more. The details of the power storage device exterior material 10 are as described above.

By using the polyamide film of the present disclosure for the base layer 1 of the power storage device exterior material, the polyamide film of the base layer 1 of the power storage device exterior material 10 preferably has a crystallization index (transmission method) of 1.80. The above can be set, and it is possible to effectively suppress damage to the power storage device exterior material during the above-described peeling. That is, the polyamide film of the present disclosure whose crystallization index (permeation method) is adjusted in advance to 1.80 or more is used as the base layer 1, and laminated with each layer such as the barrier layer 3 and the heat-fusible resin layer 4. By doing so, it is preferable to manufacture the power storage device exterior material 10 of the present disclosure. As described above, the crystallization index (transmission method) of the polyamide film laminated on the power storage device exterior material 10 and contained in the base layer 1 is increased more than the polyamide film before being applied to the power storage device exterior material 10. be able to. Specifically, the crystallization index (permeation method) can be increased by applying heat to the polyamide film during the manufacturing process of the power storage device exterior material 10 .

The method for measuring the crystallization index (transmission method) of the polyamide film of the present disclosure is as described in the above item <Measurement of crystallization index (transmission method) of polyamide film>.

In addition, from the viewpoint of more effectively suppressing damage to the exterior material for an electricity storage device during the above-described peeling, the polyamide film of the present disclosure is a crystal measured by the ATR method of Fourier transform infrared spectroscopy. conversion index (ATR method) is preferably 1.50 or more, more preferably 1.55 or more, still more preferably 1.60 or more, and particularly preferably 1.65 or more. Moreover, the upper limit of the crystallization index (ATR method) is not particularly limited, but examples thereof include 2.50 or less and 1.80 or less. Preferred ranges of the crystallization index are, 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 1.50. 80, 1.65 to 1.80, and the like. The method for measuring the crystallization index (ATR method) is as follows.

<Measurement of crystallization index (ATR method) of polyamide film>
A sample is prepared by cutting a polyamide film into a square of 100 mm×100 mm. Using the ATR measurement mode of FT-IR, 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%. As an apparatus, for example, Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, the peak intensity P near 1200 cm ^-1 derived from the absorption of the α-crystal of nylon and the peak strength Q near 1370 cm ^-1 derived from the absorption unrelated to the crystal were measured, and the peak intensity Q The intensity ratio X=P/Q of the peak intensity P to is calculated as the crystallization index.
(Measurement condition)
Method: Macro ATR method Wave number resolution: 8 cm ^-1
Accumulation times: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

Specific examples of the polyamide forming the polyamide film are as described in the item of the base material layer 1 of the power storage device exterior material 10 . 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 a biaxially stretched film include successive biaxial stretching, inflation, and simultaneous biaxial stretching. Methods for applying the resin include a roll coating method, a gravure coating method, an extrusion coating method, and the like.

The polyamide film is particularly preferably a biaxially oriented nylon film.

The thickness of the polyamide film is preferably about 3 μm or more, more preferably about 10 μm or more, from the viewpoint of more effectively suppressing breakage of the power storage device exterior material when peeled off as described above. , preferably about 50 μm or less, more preferably about 35 μm or less. degree 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. The details of the additive are as described in the item of the base material layer 1 of the exterior material 10 for an electric storage device.

EXAMPLES 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.

<Manufacturing exterior materials for power storage devices>
Example 1-3 and Comparative Example 1-2
An oriented nylon (ONy) film (thickness: 25 μm) was prepared as a substrate layer. As will be described later, the stretched nylon films used in Examples 1-3 and Comparative Examples 1-2 were each adjusted to have a crystallization index as shown in Table 1 by changing the stretching ratio and the heat setting temperature. be. The oriented nylon film is coated with erucamide as a lubricant. As a barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared. Next, an adhesive (two-component urethane adhesive) was applied to one surface of the aluminum alloy foil and dried. Next, after laminating the adhesive on the barrier layer and the substrate layer by a dry lamination method, an aging treatment is performed to obtain a substrate layer (thickness of 25 μm)/adhesive layer (thickness of 3 μm after curing)/ A laminate of barrier layers (40 μm thick) was produced. Both sides of the aluminum alloy foil are chemically treated. The chemical conversion treatment of the aluminum alloy foil is carried out by roll-coating the aluminum alloy foil with a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid so that the coating amount of chromium is 10 mg/m ² (dry mass). It was carried out by coating on both sides and baking.

Next, on the barrier layer of each laminate obtained above, maleic anhydride-modified polypropylene as an adhesive layer (thickness 23 μm) and random polypropylene as a heat-fusible resin layer (thickness 23 μm). By co-extrusion, the adhesive layer / heat-fusible resin layer is laminated on the barrier layer, aged, and sequentially from the outside, the base layer (thickness 25 μm) / adhesive layer (3 μm) A laminate (total thickness: 114 μm) in which /barrier layer (40 μm)/adhesive layer (23 μm)/thermal adhesive resin layer (23 μm) was laminated was obtained.

<Measurement of crystallization index (ATR method) of base material layer of exterior material for power storage device>
A sample was prepared by cutting the exterior material for an electricity storage device into a square of 100 mm×100 mm. The surface of the stretched nylon film located outside the obtained sample was measured using the ATR measurement mode of Nicolet iS10 FT-IR manufactured by Thermo Fisher Scientific Co., Ltd. under an environment of a temperature of 25 ° C. and a relative humidity of 50%. Infrared absorption spectrum measurement was carried out at From the obtained absorption spectrum, the peak intensity P near 1200 cm ^-1 derived from the absorption of the α-crystal of nylon and the peak strength Q near 1370 cm ^-1 derived from the absorption unrelated to the crystal were measured, and the peak intensity Q The intensity ratio X=P/Q of the peak intensity P to the was calculated as the crystallization index. Table 1 shows the results.
(Measurement condition)
Method: Macro ATR method Wave number resolution: 8 cm ^-1
Accumulation times: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

<Measurement of crystallization index of stretched nylon film (transmission method and ATR method)>
A sample was prepared by cutting the stretched nylon film used for the base material layer of the exterior material for an electric storage device into a square of 100 mm×100 mm. The surface of the obtained sample was measured using the transmission measurement mode or ATR measurement mode of Nicolet iS10 FT-IR manufactured by Thermo Fisher Scientific Co., respectively, at a temperature of 25 ° C. and a relative humidity of 50%. A spectral measurement was performed. From the obtained absorption spectrum, the peak intensity P near 1200 cm ^-1 derived from the absorption of the α-crystal of nylon and the peak strength Q near 1370 cm ^-1 derived from the absorption unrelated to the crystal were measured, and the peak intensity Q The intensity ratio X=P/Q of the peak intensity P to the was calculated as the crystallization index. Table 1 shows the results.

(Measurement conditions (transmission method))
Method: transmission method Wavenumber resolution: 8 cm ^-1
Accumulated times: 32 times Detector: DTGS detector Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

(Measurement conditions (ATR method))
Method: Macro ATR method Wave number resolution: 8 cm ^-1
Accumulation times: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as linear approximation between wavenumbers of 1100 cm ^-1 and 1400 cm ^-1 .
Absorption peak intensity Y ₁₂₀₀ : 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 : peak intensity in the wavenumber range of 1365 cm ^-1 to 1375 cm ^-1 the maximum value minus the baseline value

<Peeling off test of power storage device>
A peeling test of the electricity storage device was performed according to the following procedure. Description will be made with reference to FIGS. 5 to 8. FIG. First, a procedure for preparing a sample used for a peeling test of an electricity storage device will be described with reference to FIG. As shown in FIG. 5a, the exterior material for an electric 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 a diameter of 55 mm (MD) x 32 mm (TD) and a molding die (male die) corresponding to this, 15 mm from the short side of the electrical storage device exterior material At a separate position, cold molding was performed to a depth of 5.0 mm from the heat-sealable resin layer side to form a recess M (area surrounded by a broken 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 (Fig. 5b,c). Next, the molded electric storage device exterior material was folded in half in the TD direction at the position of the fold line P (position along the short side of the recess M) so that the recess M faced the inside (Fig. 5d). Next, along the periphery of the concave portion M, the overlapping portions of the heat-fusible resin layers were heat-sealed along MD and TD at three locations (190°C, 3 seconds, surface pressure 1 MPa), The recess M was sealed (Fig. 5e). In FIG. 5e, the colored area S is the portion that is heat sealed. Next, as shown in FIG. 5f, trimming along the recess M to a size of 60 mm in length (MD) and 37 mm in width (TD), sample 12 used for the peeling test of the electricity storage device was produced. 6 shows a side view (FIG. 6a) and a plan view (FIG. 6b) of sample 12. FIG.

Next, as shown in the schematic diagram of FIG. 7, on the flat side surface of the sample 12 (the surface opposite to the surface on which the recessed portion M is formed), three surfaces along the longitudinal direction (MD) A tape (width 7.5 mm, length 55 mm) was applied to both ends and the center position. The peel strength of the double-sided tape to the target object was measured by the method described below.

Next, the sample 12 attached with double-sided tape was attached to a stainless steel plate and cured in a 60° C. environment for 24 hours. It should be noted that the stainless steel plate is used as a housing for fixing the power storage device with 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. For each of them, evaluation was performed in a peeling test of the electricity storage device 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 . Table 1 shows the results.
A: All three samples had no 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 3 are composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer, and the base material layer is made of polyamide. The polyamide film has a crystallization index (transmission method) of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. Further, the polyamide film used for the base material layer of the exterior material for an electric storage device in Examples 1 to 3 has a crystallization index (transmission method) measured by the ATR method of Fourier transform infrared spectroscopy of 1.80 or more. is. It can be seen that the power storage device exterior materials of Examples 1 to 3 effectively suppress damage to the power storage device exterior materials when the power storage device fixed with double-sided tape or the like is peeled off from the housing.

The difference between the crystallization index (ATR method) measured for the base material layer of the power storage device exterior material and the crystallization index (ATR method) measured for the stretched nylon film is due to the influence of aging of the power storage device exterior material. Conceivable. The stretched nylon films used in Comparative Examples 1 and 2 have significantly smaller values of crystallization index (ATR method) than those of Examples 1 to 3, but were measured after being used as the base layer of the exterior material for an electric storage device. The values are considerably higher than those measured in oriented nylon films. However, in Comparative Examples 1 and 2, the crystallization index (ATR method) of the polyamide film measured from the outside of the base material layer was not increased to 1.50 or more by aging the exterior material for an electricity storage device. The peel test evaluation of the device was inferior to Examples 1-3.

(Measurement of peel strength of double-sided tape)
Exterior material for electricity storage device of Example 1-3 (length 15 mm × width 70 mm), double-sided tape (length 7.5 mm × width 60 mm) used in <Electricity storage device peeling test>, aluminum foil (thickness 35 μm x length 15 mm x width 150 mm), a fixing double-sided adhesive tape (length 5 mm x width 60 mm), and an acrylic plate (thickness 3 mm x length 50 mm x width 70 mm) were prepared. First, the surface of the stretched nylon film of the exterior material for the electric storage device and one side of the double-sided tape are pasted together, and then the other side of the double-sided tape is pasted with aluminum foil. to obtain a laminate P. Moreover, the laminated body Q was obtained by pasting together the acrylic plate and the one side of the double-sided adhesive tape for fixation. Furthermore, the surface of the heat-fusible resin layer of the electrical storage device exterior material of the laminate P is adhered to the other side of the double-faced adhesive tape for fixing of the laminate Q, and pressed by hand to attach the acrylic plate and the double-sided adhesive for fixing. A laminate R in which a tape, an exterior material for an electricity storage device, a double-sided tape, and an aluminum foil were laminated in this order was obtained, and this was used as a test sample M. The test sample M was stored for 24 hours in an environment with a temperature of 60°C. Next, the surface of the stretched nylon film of the exterior material for an electric storage device and the end of the double-sided tape were separated by about 1 mm to provide a starting portion for measuring the peel strength. Next, the acrylic plate of the test sample M was fixed, and a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)) was used under conditions of a tensile angle of 180°, a peeling speed of 300 mm/min, and a peeling distance of 50 mm or more. The aluminum foil is pulled and peeled off at the interface between the stretched nylon film surface of the exterior material for the electric storage device and the double-sided tape (from the trigger portion), and the peel strength at peel distances of 10 mm, 20 mm, 30 mm, and 40 mm, and 10 The average of a total of 5 peel strengths of the maximum peel strength between ~40 mm was calculated as the peel strength (peeling strength of the double-sided tape to the stretched nylon film (N/7.5 mm)). Table 2 shows the results.

Next, the stainless steel plate (thickness 3 mm × length 50 mm × width 70 mm) and double-sided tape (length 7.5 mm × width 60 mm) used in <Peeling test of electricity storage device>, and the aluminum foil (thickness 35 μm) × length 15 mm × width 150 mm) was prepared. The surface of the stainless steel plate and one side of the double-sided tape are pasted together, and the other side of the double-sided tape is pasted with aluminum foil. It 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 surface of the stainless steel plate and the edge of the double-sided tape were peeled off by about 1 mm to provide a starting portion for measuring the peel strength. Next, the stainless steel plate of test sample N was fixed, and a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)) was used to perform the conditions of a tensile angle of 180°, a peel speed of 300 mm/min, and a peel distance of 50 mm or more. The aluminum foil is pulled and peeled off at the interface between the stainless steel plate surface and the double-sided tape (from the trigger part), and the peel strength at peel distances of 10 mm, 20 mm, 30 mm, and 40 mm, and the maximum peel strength between 10 and 40 mm. The average of the five peel strengths in total was calculated as the peel strength (the peel strength of the double-sided tape against the stainless steel plate (N/7.5 mm)). Table 2 shows the results.

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

As described above, the present disclosure provides inventions in the following aspects.
Section 1. Consists of a laminate comprising, in order from the outside, at least a substrate layer, a barrier layer, and a heat-fusible resin layer,
The base layer contains a polyamide film,
An exterior material for an electric storage device, wherein the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy.
Section 2. Item 2. The power storage device exterior material according to Item 1, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy.
Item 3. Item 3. The exterior material for an electricity storage device according to Item 1 or 2, further comprising an adhesive layer between the base material layer and the barrier layer.
Section 4. Item 4. The power storage device exterior material according to any one of Items 1 to 3, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.
Item 5. obtaining a laminate in which at least a substrate layer, a barrier layer, and a heat-fusible resin layer are laminated in order from the outside,
The base layer contains a polyamide film,
A method for producing an exterior material for an electric storage device, wherein the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy.
Item 6. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is accommodated in a package formed of the electricity storage device exterior material according to any one of Items 1 to 4.
Item 7. A polyamide film for use as the base layer of an exterior material for an electricity storage device, which is composed of a laminate including at least a base layer, a barrier layer, and a heat-fusible resin layer,
The polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy.
Item 8. Item 8. The polyamide film according to item 7, wherein 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 heat-fusible resin layer 5 adhesive layer 6 surface coating layer 10 exterior material for electric storage device

Claims (8)

Consists of a laminate comprising, in order from the outside, at least a substrate layer, a barrier layer, and a heat-fusible resin layer,
The base layer contains a polyamide film,
An exterior material for an electric storage device, wherein the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. The exterior material for an electric storage device according to claim 1, wherein the polyamide film has a crystallization index of 1.50 or more measured from the outside of the base material layer by ATR method of Fourier transform infrared spectroscopy. 3. The exterior material for an electricity storage device according to claim 1, further comprising an adhesive layer between said base material layer and said barrier layer. 4. The power storage device exterior material according to claim 1, further comprising an adhesive layer between said barrier layer and said heat-fusible resin layer. obtaining a laminate in which at least a substrate layer, a barrier layer, and a heat-fusible resin layer are laminated in order from the outside,
The base layer contains a polyamide film,
A method for producing an exterior material for an electric storage device, wherein the polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed by the exterior material for an electricity storage device according to any one of claims 1 to 4. A polyamide film for use as the base layer of an exterior material for an electricity storage device, which is composed of a laminate including at least a base layer, a barrier layer, and a heat-fusible resin layer,
The polyamide film has a crystallization index of 1.80 or more as measured by a transmission method of Fourier transform infrared spectroscopy. The polyamide film according to claim 7, wherein the polyamide film has a crystallization index of 1.50 or more as measured by ATR method of Fourier transform infrared spectroscopy.

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