JP7715180B2 - Exterior material for power storage device, manufacturing method thereof, and power storage device - Google Patents

Description

This disclosure relates to an exterior material for an electricity storage device, a method for manufacturing the same, and an electricity storage device.

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

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and other devices, there has been a demand for energy storage devices to be thinner and lighter, as well as have a variety of shapes. However, the metal exterior materials for energy storage devices that have traditionally been widely used have the drawback of being difficult to adapt to the increasing variety of shapes, and there are also limitations to how light they can be made.

In recent years, therefore, film-like laminates, in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated, have been proposed as packaging materials for electricity storage devices that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

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

Japanese Patent Application Laid-Open No. 2008-287971 Japanese Patent Application Laid-Open No. 2015-166261

For example, power storage devices such as lithium-ion secondary batteries are sometimes required to be colored black to match the appearance and color of the electrical equipment to which they are attached (see, for example, Patent Document 2).

Meanwhile, in the manufacturing process for an electricity storage device using an exterior material for an electricity storage device, an identification mark such as product information (for example, letters or numbers indicating a lot number, a barcode, or a symbol) may be printed on the surface of the electricity storage device. By attaching an identification mark to the surface of the electricity storage device, it is possible to distinguish between genuine products and counterfeit products, for example. Similarly, in the manufacturing process for an electricity storage device exterior material, an identification mark may be printed on the outer surface.

However, after investigations, the inventors of the present disclosure discovered a new problem: when an electricity storage device or an exterior material for an electricity storage device is colored so that its appearance appears black, the identifiability of printed identification marks, etc., is reduced during the manufacturing process.

Specifically, in the manufacturing process of electricity storage devices and packaging materials for electricity storage devices, processing and inspection are sometimes carried out under yellow light sources, such as in a yellow room. However, it has been discovered that when an identification label or the like is printed on an electricity storage device or packaging material for an electricity storage device, which has a black appearance, and processing and inspection are carried out under the light source in a yellow room, the identification label's identifiability is reduced, potentially making it impossible to accurately read product information, etc.

Under these circumstances, the primary objective of this disclosure is to provide an exterior packaging material for an electricity storage device that has a black appearance but allows for excellent identification of the identification markings printed on the surface under the light source in a yellow room.

The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems, and as a result, they discovered that in an exterior packaging material for an electricity storage device that is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer and has a black appearance, by setting the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside under specified conditions to a specified value or less, it is possible to adjust the color of black to a black that exhibits a bluish hue that is the complementary color of yellow, and thereby improve the identifiability of an identification mark printed on the surface in a yellow room or under an orange to yellow lamp light source.

The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects.
An exterior material for an electricity storage device that has a black appearance,
the electrical storage device packaging material is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer;
An exterior material for a storage battery device, wherein the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is −0.20 or less.

The present disclosure makes it possible to provide an electrical storage device packaging material that, despite having a black appearance, allows for excellent identification of an identification mark printed on the surface in a yellow room or under an orange to yellow lamp (Na lamp) light source. The present disclosure also makes it possible to provide a method for manufacturing the electrical storage device packaging material, and an electrical storage device that uses the electrical storage device packaging material.

1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure.

The electrical storage device packaging material of the present disclosure is an electrical storage device packaging material that has a black appearance, and is composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer, and is characterized in that the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside under measurement conditions of the SCI method, a field of view of 10°, and light source F2 is −0.20 or less. Due to the configuration of the electrical storage device packaging material of the present disclosure, despite the electrical storage device packaging material having a black appearance, it is possible for an identification mark printed on the surface to exhibit excellent identification under a light source in a yellow room.

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

Furthermore, in the electrical storage device exterior material of the present disclosure, "exhibiting a black appearance" means that the electrical storage device exterior material is recognized as black when observed from the outside with the naked eye. More specifically, the "black" in "exhibiting a black appearance" refers to an L ^* value of 40 or less, preferably 35 or less, in the CIE 1976 L ^* a ^* b ^* (CIELAB) chromaticity coordinates. The L ^* value is also measured from the outside under the measurement conditions of the SCI method, a 10° field of view, and an F2 light source in the L ^* a ^* b ^* color space of reflected light. In addition to the L ^* value, black preferably also has an a ^* value of -20 to +20, more preferably -10 to +10. The electrical storage device exterior material of the present disclosure is characterized in that in addition to exhibiting a black appearance, it also has a b ^* value of -0.20 or less.

As described below, the appearance of the electrical storage device exterior material can be made black and the b* value and other properties can be adjusted by adjusting the composition, such as the type and content of additives and colorants contained in each layer constituting the electrical storage device exterior material of the present disclosure (layers located outside the barrier layer, such as the substrate layer, adhesive layer, colored layer, and surface coating layer), the composition of the layers located outside the barrier layer, and the aging treatment conditions of the electrical storage device exterior material, which will be described later. It is preferable to adjust ^{the b* value} using at least a black additive or colorant (e.g., a black pigment). However, the b ^* value may also be adjusted by mixing multiple types of additives and colorants other than black to achieve a black color. Furthermore, the b* value may also be adjusted by using multiple layers, such as using a black additive or colorant in one layer and a non-black (e.g., blue) additive or colorant in the other layers, among the layers constituting the ^electrical storage device exterior material of the present disclosure.

A yellow room refers to a room where light with wavelengths of 500 nm or less, including ultraviolet light, is blocked, and light in such a room appears yellow. Yellow rooms are commonly used, for example, in clean rooms in semiconductor factories to carry out photolithography processes that involve the handling of photosensitive materials.

1. Laminated Structure and Physical Properties of the Electricity Storage Device Exterior Material As shown in FIG. 1 , the exterior packaging material 10 for an electricity storage device according to the present disclosure is composed of a laminate including, in order from the outside, a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4. In the exterior packaging material 10 for an electricity storage device, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electricity storage device using the exterior packaging material 10 for an electricity storage device and an electricity storage device element, the heat-sealable resin layers 4 of the exterior packaging material 10 for an electricity storage device are placed opposite each other, and the peripheral portions are heat-sealed to form a space, in which the electricity storage device element is housed. In the laminate constituting the exterior packaging material 10 for an electricity storage device according to the present disclosure, the barrier layer 3 is used as the reference, and the heat-sealable resin layer 4 side is the inner side relative to the barrier layer 3, and the base material layer 1 side is the outer side relative to the barrier layer 3.

As shown in Figures 2, 4 to 6, the electrical storage device packaging material 10 may optionally include an adhesive layer 2 between the substrate layer 1 and the barrier layer 3 to enhance adhesion between these layers (and, as described below, to color the electrical storage device packaging material 10). As shown in Figures 3 and 4, a coloring layer 21 may optionally be included between the substrate layer 1 and the barrier layer 3 to enhance adhesion between these layers. As shown in Figures 5 and 6, an adhesive layer 5 may optionally be included between the barrier layer 3 and the heat-sealable resin layer 4 to enhance adhesion between these layers. As shown in Figure 6, a surface coating layer 6 may optionally be provided on the outer side of the substrate layer 1 (the side opposite the heat-sealable resin layer 4).

The thickness of the laminate constituting the electrical storage device exterior material 10 is not particularly limited, but from the viewpoints of cost reduction, improved energy density, etc., it is preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the electrical storage device exterior material to protect the electrical storage device elements, the thickness of the laminate constituting the electrical storage device exterior material 10 is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the thickness of the laminate constituting the electrical storage device exterior material 10 include, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm.

The electrical storage device exterior material 10 of the present disclosure has a b ^* value of −0.20 or less in the L ^* a ^* b ^* color space of reflected light measured from the outside under measurement conditions of the SCI method, a field of view of 10°, and light source F2. By setting the upper limit of the b ^* value to such a specific value, an electrical storage device exterior material that has a black appearance can be adjusted to a black that has a bluish hue that is the complementary color of yellow, and excellent identification of an identification mark printed on the surface is exhibited in a yellow room or under a yellow light source.

The b ^* value is not particularly limited, but is limited to -0.20 or less, but from the viewpoint of further improving distinguishability and enabling the appearance to be suitably recognized as black, it is preferably about -0.50 or less, more preferably about -0.80 or less. From the same viewpoint, the b ^* value is preferably about -5.00 or more, more preferably about -4.00 or more, even more preferably about -2.00 or more, and even more preferably about -1.50 or more. Preferred ranges for the b ^* value include about -5.00 to -0.20, about -5.00 to -0.50, about -5.00 to -0.80, about -4.00 to -0.20, about -4.00 to -0.50, about -4.00 to -0.80, about -2.00 to -0.20, about -2.00 to -0.50, about -2.00 to -0.80, about -1.50 to -0.20, about -1.50 to -0.50, and about -1.50 to -0.80. Among these, the b ^* value is particularly preferably about -1.50 to -0.80.

Furthermore, the exterior packaging material 10 for an electricity storage device according to the present disclosure preferably has an a ^* value of +0.20 or less in the L ^* a ^* b ^* color space of reflected light measured from the outside under the measurement conditions of the SCI method, a field of view of 10°, and light source F2. This further improves distinguishability and enables the appearance to be suitably recognized as black.

From the viewpoint of further improving the distinguishability and suitably recognizing that the appearance is black, the a ^* value is more preferably about +0.10 or less, even more preferably about +0.04 or less, even more preferably about +0.02 or less, even more preferably about 0.00 or less, and even more preferably about -0.01 or less. From the same viewpoint, the a ^* value is preferably about -3.50 or more, more preferably about -3.00 or more, even more preferably about -2.00 or more, even more preferably about -0.50 or more, even more preferably about -0.30 or more, even more preferably about -0.15 or more, and even more preferably about -0.10 or more. ^* Preferable ranges for the value are approximately -3.50 to +0.20, approximately -3.50 to +0.10, approximately -3.50 to +0.04, approximately -3.50 to +0.02, approximately -3.50 to 0.00, approximately -3.50 to -0.01, approximately -3.00 to +0.20, approximately -3.00 to +0.10, approximately -3.00 to +0.04, and -3.00 to +0.02 degree, -3.00 to about 0.00, -3.00 to -0.01, -2.00 to +0.20, -2.00 to +0.10, -2.00 to +0.04, -2. 00 to +0.02, -2.00 to 0.00, -2.00 to -0.01, -0.50 to +0.20, -0.50 to +0.10, -0.50 to +0. 04, -0.50 to +0.02, -0.50 to 0.00, -0.50 to -0.01, -0.30 to +0.20, -0.30 to +0.10, - 0.30 to +0.04, -0.30 to +0.02, -0.30 to 0.00, -0.30 to -0.01, -0.15 to +0.20, -0.15 to + Examples of the a* value include about 0.10, about -0.15 to +0.04, about -0.15 to +0.02, about -0.15 to 0.00, about -0.15 to -0.01, about -0.10 to +0.20, about -0.10 to +0.10, about -0.10 to +0.04, about -0.10 to +0.02, about -0.10 to 0.00, and about -0.10 to -0.01. Among these, the a ^* value is particularly preferably about -0.30 to -0.01, or about -0.10 to -0.01.

Furthermore, the exterior packaging material 10 for an electricity storage device according to the present disclosure preferably has an L ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside under measurement conditions of the SCI method, a field of view of 10°, and light source F2 of 35.0 or less, which further improves distinguishability and makes it possible to suitably recognize that the appearance is black.

The L ^* value is preferably about 33.0 or less, more preferably about 30.0 or less, and even more preferably about 28.0 or less, from the viewpoint of further improving distinguishability and ensuring that the appearance is suitably recognized as black. From the same viewpoint, the L ^* value is preferably about 25.0 or more, more preferably about 26.0 or more. Preferred ranges for the L ^* value include about 25.0 to 35.0, about 25.0 to 33.0, about 25.0 to 30.0, about 25.0 to 28.0, about 26.0 to 35.0, about 26.0 to 33.0, about 26.0 to 30.0, and about 26.0 to 28.0. Among these, the L ^* value is particularly preferably about 25.0 to 30.0, about 26.0 to 30.0, even about 26.0 to 29.0, and even about 26.0 to 28.0.

<Measurement of L ^* value, a ^* value, and b ^* value>
In the present disclosure, the L ^* value, a ^* value, and b ^* value are values measured by the following method. For an electrical storage device exterior material, a spectrophotometer (e.g., a CM-700d manufactured by Konica Minolta) calibrated with a white calibration cap (e.g., a CM-A177 manufactured by Konica Minolta) is used with the observation conditions set to 10°, the observation light source set to F2, and SCI mode (JIS Z8722-2009), and the L ^* , a ^* , and b ^* values of the outer (substrate layer side) surface are measured at room temperature and humidity. Three measurements are taken for each sample, and the average value is used as the measured value. Alternatively, the electrical storage device exterior material can be obtained from the electrical storage device, and the L ^* value, a ^* value, and b ^* value can be measured from the outside of the laminate constituting the electrical storage device exterior material. When the electrical storage device exterior material is obtained from the electrical storage device and measured, the top surface portion of the electrical storage device exterior material that has not been stretched by molding is the object of measurement.

In the electrical storage device packaging material of the present disclosure and in the electrical storage device using the same, the printed identification markings include, for example, letters and numbers indicating the lot number, barcodes, symbols, etc. Furthermore, the color of the ink used to print the identification markings (i.e., the color of the identification markings) is preferably white, as this provides excellent identification in the electrical storage device packaging material of the present disclosure, which has a black appearance.

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

The material for forming the substrate layer 1 is not particularly limited as long as it functions as a substrate, i.e., has at least insulating properties. The substrate layer 1 can be formed using, for example, a resin, which may contain an additive described below. For example, the L ^* value, a ^* value, and b ^* value can be adjusted by blending an additive or a colorant described below into the substrate layer.

When the base layer 1 is formed from a resin, the base layer 1 may be, for example, a resin film formed from a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Stretching methods for forming biaxially stretched films include, for example, sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Resin application methods include roll coating, gravure coating, and extrusion coating.

Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins, or a modified version of the copolymer. It may also be a mixture of these resins.

Of these, polyester and polyamide are preferred as resins for forming the base layer 1.

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

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain structural units derived from terephthalic acid and/or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and other polyamide copolymers. These polyamides may be used alone or in combination of two or more.

The substrate layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and even more preferably at least one of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polybutylene terephthalate film, a biaxially oriented nylon film, and a biaxially oriented polypropylene film.

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

Specific examples of laminates of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon film layers, and a laminate of two or more polyester film layers. Preferably, they are a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon film layers, or a laminate of two or more stretched polyester film layers. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred. A laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, because polyester resins are less likely to discolor when electrolyte solution adheres to their surface, it is preferable that the polyester resin film be the outermost layer of the base layer 1 when the base layer 1 is a laminate of two or more resin films.

When the base layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include those similar to those exemplified for adhesive layer 2, described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating using the dry lamination method, a polyurethane adhesive is preferably used as the adhesive. In this case, the adhesive thickness can be, for example, approximately 2 to 5 μm. Alternatively, an anchor coat layer can be formed on the resin film before lamination. Examples of the anchor coat layer include those similar to those exemplified for adhesive layer 2, described below. In this case, the anchor coat layer thickness can be, for example, approximately 0.01 to 1.0 μm.

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

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

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

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

The thickness of the substrate layer 1 is not particularly limited as long as it functions as a substrate, but examples include approximately 3 to 50 μm, and preferably approximately 10 to 35 μm. When the substrate layer 1 is a laminate of two or more resin film layers, the thickness of each resin film constituting each layer is preferably approximately 2 to 25 μm.

For example, if the adhesive layer is a layer colored black, it is preferable that the substrate layer located outside the adhesive layer be transparent or translucent.

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

Furthermore, in the electrical storage device packaging material of the present disclosure, the adhesive layer 2 may be colored black. By coloring the adhesive layer 2 black, the electrical storage device packaging material can be obtained with a black appearance, and the b ^* value can be suitably set to −0.20 or less. However, simply coloring the adhesive layer 2 black does not necessarily result in the b ^* value being −0.20 or less. By adjusting the composition, such as the type and content of the colorant contained in the adhesive layer 2, the composition of the base material layer 1, and layers positioned outside the barrier layer 3, such as the surface coating layer 6 and colored layer 21, which are optionally provided, and the aging treatment conditions of the electrical storage device packaging material, which will be described later, the appearance of the electrical storage device packaging material can be made black, and the b ^* value can be set to −0.20 or less. The same applies to setting the L ^* value and the a ^* value.

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

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

Examples of polyurethane adhesives include those containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, with a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate-modified compounds of one or more of these diisocyanates. Furthermore, polymers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such polymers include adducts, biurets, and nurates. Note that an aliphatic isocyanate compound refers to an isocyanate that has an aliphatic group but no aromatic ring, an alicyclic isocyanate compound refers to an isocyanate that has an alicyclic hydrocarbon group, and an aromatic isocyanate compound refers to an isocyanate that has an aromatic ring. Forming the adhesive layer 2 from a polyurethane adhesive provides the electrical storage device packaging material with excellent electrolyte resistance, and prevents the base layer 1 from peeling off even if the electrolyte adheres to the side surface.

In addition, the adhesive layer 2 may contain other components as long as they do not impair adhesion, such as colorants, thermoplastic elastomers, tackifiers, and fillers. By including a colorant in the adhesive layer 2, the electrical storage device packaging material can be colored. Known colorants such as pigments and dyes can be used. A single colorant may be used, or two or more colorants may be mixed together.

The type of pigment is not particularly limited as long as it has a b ^* value of −0.20 or less and 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, while examples of inorganic pigments include carbon black-based, titanium-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include finely powdered mica and fish scale foil.

The average particle diameter of the pigment is not particularly limited as long as the b ^* value is −0.20 or less and the adhesive properties of the adhesive layer 2 are not impaired. Examples of the average particle diameter of the pigment include approximately 0.05 to 5 μm, and preferably approximately 0.08 to 2 μm. The average particle diameter of the pigment is the median diameter measured using a laser diffraction/scattering particle size distribution analyzer. If the primary particle diameter of the pigment changes, the L ^* , a ^* , and b ^* values will also change, even for the same type of pigment. For example, if the primary particle diameter of a black pigment increases, the resulting black color may have a slight bluish tinge. For this reason, in the present disclosure, it is also preferable to adjust the primary particle diameter of the pigment used when setting the L ^* , a ^* , and b ^* values. The secondary particle diameter of the pigment is preferably approximately 0.8 μm or less, more preferably approximately 0.6 μm or less, and even more preferably approximately 0.4 μm or less. The secondary particle diameter of the pigment is preferably approximately 0.05 μm or more, more preferably approximately 0.1 μm or more. Preferred ranges for the secondary particle size of the pigment include about 0.05 to 0.8 μm, about 0.05 to 0.6 μm, about 0.05 to 0.4 μm, about 0.1 to 0.8 μm, about 0.1 to 0.6 μm, and about 0.1 to 0.4 μm.

Among colorants, it is preferable to use a black agent to give the exterior material for an electrical storage device a black appearance. A black agent is an additive such as a pigment or dye that can be colored black; it is a black colorant. Examples of black agents include black pigments. Carbon and titanium-based pigments are preferred as black pigments. Black pigments made of carbon are generally called carbon black. Titanium black is preferred as a titanium-based pigment. Carbon black and titanium black may also be used in combination.

Furthermore, from the viewpoint of improving distinguishability by setting the b ^* value to preferably −0.20 or less while giving the exterior appearance of the electrical storage device packaging material a black color, it is preferable that the adhesive layer 2 further contains a blue agent in addition to the black agent. The blue agent is an additive such as a pigment or dye that can be colored blue, and is a blue colorant. Examples of blue agents include dyes such as anthraquinone and indigoid, and pigments such as phthalocyanine, ultramarine, ferric ferrocyanide, and Prussian blue. Examples of phthalocyanines include copper phthalocyanine and metal-free phthalocyanine, with copper phthalocyanine being preferred. Copper phthalocyanine is known as a blue pigment.

When X-ray fluorescence analysis (XRF) is performed from the outside of the laminate constituting the electrical storage device exterior material of the present disclosure, Cu element is preferably detected. For example, when the adhesive layer 2 of the electrical storage device exterior material contains a copper-containing pigment (e.g., copper phthalocyanine) as the pigment, Cu element is detected when X-ray fluorescence analysis (XRF) is performed from the outside of the laminate. As described below, when the surface coating layer 6 or the colored layer 21 contains a copper-containing pigment (e.g., copper phthalocyanine), Cu element is also detected when X-ray fluorescence analysis (XRF) is performed from the outside. The measurement conditions described in the examples can be used to detect Cu element by X-ray fluorescence analysis (XRF).

The content of the colorant in the adhesive layer 2 is not particularly limited as long as the electrical storage device packaging material is colored black and the b ^* value is −0.20 or less. From the viewpoint of appropriate coloring, the content is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of appropriately maintaining the adhesion between the base material layer 1 and the barrier layer 3, the content of the colorant in the adhesive layer 2 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the colorant in the adhesive layer 2 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass.

Furthermore, when a black agent is blended as a colorant in the adhesive layer 2, the content of the black agent in the adhesive layer 2 is not particularly limited as long as the electrical storage device packaging material is colored black and the b ^* value is −0.20 or less. From the viewpoint of appropriate coloring, the content is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. From the viewpoint of appropriately maintaining the adhesion between the base material layer 1 and the barrier layer 3, the content of the black agent in the adhesive layer 2 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the black agent in the adhesive layer 2 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass. Furthermore, when a blue agent is blended into the adhesive layer 2, the content of the blue agent in the adhesive layer 2 is not particularly limited as long as the packaging material for an electricity storage device is colored black, and may be, for example, about 0.5 to 30 mass %, and preferably 1 to 20 mass %.

Furthermore, when a black agent and a blue agent are blended into the adhesive layer 2, the ratio of the black agent to the blue agent in the adhesive layer 2 is preferably about 0.1 mass parts or more, more preferably about 1 mass parts or more, and even more preferably about 10 mass parts or more, based on 100 parts by mass of the black agent. The ratio of the blue agent is preferably about 150 mass parts or less, more preferably about 100 mass parts or less. Preferred ranges for the ratio of the blue agent are about 0.1 to 150 mass parts, about 0.1 to 100 mass parts, about 1 to 150 mass parts, about 1 to 100 mass parts, about 10 to 150 mass parts, and about 10 to 100 mass parts. As described above, the L* value, a* value, and b ^{* value} can be set by adjusting the primary particle size of the pigment used, the composition of the layer located outside the ^barrier layer 3, and the aging treatment conditions of the electrical storage device exterior material, which will be described later. Therefore, the adhesive layer 2 may contain only a black agent as a colorant, and may not contain, for example, a blue agent.

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

[Colored layer 21]
The colored layer 21 is a layer that is provided, if necessary, between the base material layer 1 and the barrier layer 3. When the adhesive layer 2 is provided, the colored layer 21 may be provided at least either between the base material layer 1 and the adhesive layer 2 or between the adhesive layer 2 and the barrier layer 3. The colored layer 21 may also be provided on the outer side of the base material layer 1. By providing the colored layer 21, the packaging material for an electricity storage device can be suitably colored black.

Furthermore, in the electrical storage device packaging material of the present disclosure, by coloring the colored layer 21 black, the electrical storage device packaging material can be obtained with a black appearance, and the b ^* value can be suitably set to −0.20 or less. However, as in the case of coloring the adhesive layer 2 described above black, simply coloring the colored layer 21 black does not necessarily result in the b ^* value being −0.20 or less. By adjusting the composition, such as the type and content of the colorant contained in the colored layer 21, the composition of the layers positioned outside the barrier layer 3, such as the base layer 1 and the optional surface coating layer 6 and adhesive layer 2, and the aging treatment conditions for the electrical storage device packaging material described below, the electrical storage device packaging material can be made to have a black appearance and the b ^* value can be set to −0.20 or less. The same applies to setting the L ^* value and the a ^* value.

The colored layer 21 can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1 or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used as colorants. Furthermore, a single type of colorant may be used, or two or more types may be mixed together.

Specific examples of colorants contained in colored layer 21 include the same as those exemplified in the [Adhesive Layer 2] section.

The content of the colorant in the colored layer 21 is not particularly limited as long as the electrical storage device packaging material is colored black and the b ^* value is −0.20 or less. From the viewpoint of appropriate coloring, the content is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of appropriate formation of the colored layer 21, the content of the colorant in the colored layer 21 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the colorant in the colored layer 21 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass.

Furthermore, when a black agent is blended into the colored layer 21, the content of the black agent in the colored layer 21 is not particularly limited as long as the electrical storage device packaging material is colored black and the b ^* value is −0.20 or less. From the viewpoint of appropriate coloring, the content is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. From the viewpoint of appropriate formation of the colored layer 21, the content of the black agent in the colored layer 21 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the black agent in the colored layer 21 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass. Furthermore, when a blue agent is blended into the colored layer 21, the content of the blue agent in the colored layer 21 is not particularly limited as long as the exterior material for an electricity storage device is colored black, and may be, for example, about 0.5 to 30 mass %, and preferably 1 to 20 mass %.

When a black agent and a blue agent are blended into the colored layer 21, the ratio of the black agent to the blue agent in the colored layer 21 is preferably about 0.1 parts by mass or more, more preferably about 1 part by mass or more, and even more preferably about 10 parts by mass or more, based on 100 parts by mass of the black agent. The ratio of the blue agent is preferably about 150 parts by mass or less, more preferably about 100 parts by mass or less. Preferred ranges for the blue agent are approximately 0.1 to 150 parts by mass, approximately 0.1 to 100 parts by mass, approximately 1 to 150 parts by mass, approximately 1 to 100 parts by mass, approximately 10 to 150 parts by mass, and approximately 10 to 100 parts by mass.

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

Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers with barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers containing fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 also include resin films comprising at least one of these vapor-deposited films and resin layers. The barrier layer 3 may comprise multiple layers. The barrier layer 3 preferably includes a layer composed of a metal material. Specific examples of metal materials that make up the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the barrier layer 3 preferably includes at least one of aluminum alloy foil and stainless steel foil.

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

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

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

In the case of a metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer to prevent moisture penetration, and can be, for example, approximately 9 to 200 μm. The thickness of the barrier layer 3 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. The thickness of the barrier layer 3 is preferably approximately 10 μm or more, even more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred thickness ranges include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred thickness ranges for the stainless steel foil include approximately 10 to 60 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 30 μm, approximately 10 to 25 μm, approximately 15 to 60 μm, approximately 15 to 50 μm, approximately 15 to 40 μm, approximately 15 to 30 μm, and approximately 15 to 25 μm.

Furthermore, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite the substrate layer be provided with a corrosion-resistant coating to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer that is corrosion-resistant, and is obtained by, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent. A single type of treatment may be used to form the corrosion-resistant coating, or two or more types may be combined. Furthermore, multiple layers may be formed, rather than a single layer. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Furthermore, when the barrier layer 3 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 3.

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

Various corrosion-resistant coatings formed by chemical conversion treatments are known, including those containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution containing, as its main component, a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, or zinc (Zn) phosphate, or a mixture of these metal salts, or a treatment solution containing, as its main component, a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, by a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may include polymers such as phenolic resins and acrylic resins, and examples thereof include chromate treatment using an aminated phenolic polymer having repeating units represented by the following general formulas (1) to (4). The aminated phenolic polymer may contain one repeating unit represented by the following general formulas (1) to (4) alone, or any combination of two or more repeating units. The acrylic resin is preferably polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or a derivative thereof, such as a sodium salt, an ammonium salt, or an amine salt. Derivatives of polyacrylic acid, such as the ammonium salt, sodium salt, or amine salt of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, and preferably an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed together.

In general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. ^R1 and ^R2 , which may be the same or different, represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to (4), examples of the alkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the hydroxyalkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms and substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, ^R1 , and ^R2 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 general formulas (1) to (4) is preferably, for example, about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by general formula ( ₁ ) or ( ³ ), and then introducing a functional group ( ^—CH2NR1R2 ) into the resulting polymer using formaldehyde and an amine ( ^R1R2NH ) ^. The aminated phenol polymer may be used alone or in combination of two or more types.

Other examples of corrosion-resistant coatings include thin films formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. The coating agent may further contain phosphoric acid or phosphate salts, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol contains rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred for improved adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used alone or in combination of two or more. Liquid dispersion media for the rare earth element oxide sol can include various solvents, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes consisting of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of compounds having a functional group selected from isocyanate, glycidyl, carboxyl, and oxazoline groups, and silane coupling agents. The phosphoric acid or phosphoric acid salt is preferably condensed phosphoric acid or a condensed phosphate salt.

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

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

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

The amount of the corrosion-resistant coating formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of a paint-type chromate treatment, it is desirable that the barrier layer 3 contain, per square ^meter of its surface, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a chromium-equivalent chromate compound, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a phosphorus compound, and about 1.0 to 200 mg, preferably about 5.0 to 150 mg, of an aminated phenol polymer, in phosphorus-equivalent amounts.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesion strength with the barrier layer and the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry detects peaks derived from, for example, secondary ions composed of Ce, P, and O (e.g., at least one of Ce ₂ PO ₄ ⁺ and CePO ₄ ⁻ ) or secondary ions composed of Cr, P, and O (e.g., at least one of CrPO ₂ ⁺ and CrPO ₄ ⁻ ).

Chemical conversion treatment is performed by applying a solution containing the compound used to form the corrosion-resistant coating to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. Performing such a degreasing treatment allows for more efficient chemical conversion treatment of the barrier layer surface. Furthermore, using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid not only degreases the metal foil but also forms a passive metal fluoride. In such cases, it is possible to perform only the degreasing treatment.

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

The resin constituting the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but resins containing a polyolefin skeleton, such as polyolefins and acid-modified polyolefins, are preferred. The polyolefin skeleton of the resin constituting the heat-sealable resin layer 4 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, peaks derived from maleic anhydride are preferably detected. For example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers 1760 cm ⁻¹ and 1780 cm ⁻¹ . When the heat-sealable resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, peaks derived from maleic anhydride are detected by infrared spectroscopy. However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

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

The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers. Examples of olefins that constitute the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers that constitute the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is even more preferred.

Acid-modified polyolefins are polymers modified by block or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the polyolefins listed above, copolymers of the polyolefins with polar molecules such as acrylic acid or methacrylic acid, and cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

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

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

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

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

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

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

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

The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it functions to heat-seal the heat-sealable resin layers together and seal the electricity storage device element, but examples include approximately 100 μm or less, preferably approximately 85 μm or less, and more preferably approximately 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described below is 10 μm or greater, the thickness of the heat-sealable resin layer 4 is preferably approximately 85 μm or less, more preferably approximately 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described below is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably approximately 20 μm or greater, more preferably approximately 35 to 85 μm.

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

The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. Examples of resins used to form the adhesive layer 5 include the same adhesives as those exemplified for the adhesive layer 2. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry; any analytical method is acceptable. Furthermore, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, peaks derived from maleic anhydride are preferably detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers 1760 cm ⁻¹ and 1780 cm ⁻¹ . However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis by nuclear magnetic resonance spectroscopy is possible.

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

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

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

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

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

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

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

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

An example of a compound having an epoxy group is an epoxy resin. There are no particular restrictions on the epoxy resin, so long as it is a resin capable of forming a crosslinked structure via the epoxy groups present in the molecule, and any known epoxy resin can be used. The weight-average molecular weight of the epoxy resin is preferably approximately 50 to 2,000, more preferably approximately 100 to 1,000, and even more preferably approximately 200 to 800. In this disclosure, the weight-average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard sample.

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

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

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

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

When 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 the base resin, 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 thickness of adhesive layer 5 is preferably approximately 50 μm or less, approximately 40 μm or less, approximately 30 μm or less, approximately 20 μm or less, or approximately 5 μm or less. Furthermore, the thickness of adhesive layer 5 is preferably approximately 0.1 μm or more, or approximately 0.5 μm or more. Examples of thickness ranges include approximately 0.1 to 50 μm, approximately 0.1 to 40 μm, approximately 0.1 to 30 μm, approximately 0.1 to 20 μm, approximately 0.1 to 5 μm, approximately 0.5 to 50 μm, approximately 0.5 to 40 μm, approximately 0.5 to 30 μm, approximately 0.5 to 20 μm, and approximately 0.5 to 5 μm. More specifically, for adhesives such as those exemplified for adhesive layer 2, or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably approximately 1 to 10 μm, and more preferably approximately 1 to 5 μm. Furthermore, when using a resin exemplified for the heat-sealable resin layer 4, the thickness is preferably about 2 to 50 μm, and more preferably about 10 to 40 μm. When the adhesive layer 5 is an adhesive exemplified for the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. When using a resin exemplified for the heat-sealable resin layer 4, the heat-sealable resin layer 4 and the adhesive layer 5 can be formed, for example, by extrusion molding.

[Surface coating layer 6]
The electrical storage device packaging material of the present disclosure may optionally include a surface coating layer 6 on the substrate layer 1 (the opposite side of the substrate layer 1 from the barrier layer 3) for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, and formability. The surface coating layer 6 is a layer located on the outermost layer side of the electrical storage device packaging material when an electrical storage device is assembled using the electrical storage device packaging material. As described above, in the electrical storage device packaging material of the present disclosure, the b ^* value being −0.20 or less, excellent distinguishability of an identification mark printed on the surface is achieved under a light source in a yellow room. However, although the electrical storage device packaging material may exhibit a slight bluish color and visually recognize color unevenness, when the surface coating layer 6 is provided on the outermost layer of the electrical storage device packaging material of the present disclosure, the surface coating layer has the effect of diffusing light and suppressing gloss, thereby advantageously suppressing color unevenness and improving visual uniformity. On the other hand, when the outermost layer of the packaging material for an electricity storage device according to the present disclosure does not have the surface coating layer 6, the surface gloss of the packaging material for an electricity storage device is high and scratches are easily noticeable, but when the surface coating layer 6 is provided, the surface coating layer has the effect of diffusing light and suppressing gloss, which has the advantage of making scratches less noticeable. These advantages are particularly likely to be exhibited when the surface coating layer 6 contains the additives (particularly the matting agent) described below.

Furthermore, in the electrical storage device packaging material of the present disclosure, by coloring the surface coating layer 6 black, the electrical storage device packaging material can be obtained with a black appearance, and the b ^* value can be suitably set to −0.20 or less. However, as in the case of coloring the adhesive layer 2 or the colored layer 21 described above black, simply coloring the surface coating layer 6 black does not necessarily result in the b ^* value being −0.20 or less. By adjusting the composition, such as the type and content of the colorant contained in the surface coating layer 6, the composition of the layers positioned outside the barrier layer 3, such as the base layer 1 and the adhesive layer 2 or colored layer 21 that are provided as needed, and the aging treatment conditions for the electrical storage device packaging material described below, the electrical storage device packaging material can be made to have a black appearance and the b ^* value can be set to −0.20 or less. The same applies to setting the ^L* value and the a ^* value.

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

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

Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate modifications of one or more of these diisocyanates. Multimers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such multimers include adducts, biurets, and nurates. Forming the surface coating layer 6 from polyurethane provides the electrical storage device exterior material with excellent electrolyte resistance.

The surface coating layer 6 may contain additives such as the aforementioned lubricants, colorants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and/or inside of the surface coating layer 6, as needed, depending on the functionality to be imparted to the surface of the surface coating layer 6. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured using a laser diffraction/scattering particle size distribution analyzer.

Additives may be either inorganic or organic. There are also no particular restrictions on the shape of the additive, and examples include spherical, fibrous, plate-like, irregular, and scaly shapes.

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone or in combination of two or more. Among these additives, calcium carbonate is preferred from the viewpoint of improving distinguishability. Because calcium carbonate has a bluish tint, its use as an additive in the surface coating layer allows the b ^* value to be suitably set to −0.20 or less. It is also preferred to use a mixture of silica and calcium carbonate as additives. The use of silica as an additive in the surface coating layer facilitates the diffusion of reflected light, making it possible to impart a bluish tint to the appearance of the electrical storage device packaging material, and the b ^* value can be suitably set to -0.20 or less. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoints of dispersion stability and cost. The additives may also be subjected to various surface treatments, such as an insulating treatment and a high-dispersibility treatment.

When the surface coating layer 6 contains a colorant, known colorants such as pigments and dyes can be used. Furthermore, a single colorant may be used, or two or more colorants may be mixed. Specific examples of colorants contained in the surface coating layer 6 include the same as those exemplified in the [Adhesive layer 2] section. Furthermore, the preferred content of the colorant contained in the surface coating layer 6 is also the same as the content described in the [Adhesive layer 2] section.

For example, when a black agent is blended into the surface coating layer 6, the content of the black agent in the surface coating layer 6 is not particularly limited as long as the electrical storage device exterior material is colored black, and may be, for example, approximately 5 to 60% by mass, and preferably 10 to 40% by mass. Furthermore, when a blue agent is blended into the surface coating layer 6, the content of the blue agent in the surface coating layer 6 is not particularly limited as long as the electrical storage device exterior material is colored black, and may be, for example, approximately 0.5 to 30% by mass, and preferably 1 to 20% by mass.

For example, when a black agent and a blue agent are blended into the surface coating layer 6, the ratio of the black agent to the blue agent in the surface coating layer 6 is preferably about 0.1 parts by mass or more, more preferably about 1 part by mass or more, and even more preferably about 10 parts by mass or more, based on 100 parts by mass of the black agent. The ratio of the blue agent is preferably about 150 parts by mass or less, more preferably about 100 parts by mass or less. Preferred ranges for the blue agent are approximately 0.1 to 150 parts by mass, approximately 0.1 to 100 parts by mass, approximately 1 to 150 parts by mass, approximately 1 to 100 parts by mass, approximately 10 to 150 parts by mass, and approximately 10 to 100 parts by mass.

The method for forming the surface coating layer 6 is not particularly limited, and examples include a method of applying a resin to form the surface coating layer 6. If an additive is to be blended into the surface coating layer 6, a resin mixed with the additive may be applied.

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

For example, if the adhesive layer is a black-colored layer, it is preferable that the surface coating layer located outside the adhesive layer be transparent or translucent.

3. Manufacturing Method of Electricity Storage Device Exterior Material The manufacturing method of an electricity storage device exterior material is not particularly limited as long as it can obtain a laminate in which each layer included in the electricity storage device exterior material of the present disclosure is laminated, and examples include a method comprising a step of laminating at least a substrate layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. Specifically, the manufacturing method of an electricity storage device exterior material of the present disclosure is a manufacturing method of an electricity storage device exterior material that exhibits a black appearance, and comprises a step of obtaining a laminate in which, from the outside, at least a substrate layer, a barrier layer, and a heat-sealable resin layer are laminated, in this order, and the b ^* value of reflected light in the L ^* a ^* b ^* color space measured from the outside of the laminate under measurement conditions of the SCI method, a field of view of 10°, and light source F2 is −0.20 or less.

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

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

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

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

In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as necessary, to improve its processability. For example, corona treatment can be performed on the surface of the base layer 1 opposite the barrier layer 3, thereby improving the printability of ink on the surface of the base layer 1.

The electrical storage device packaging material is preferably subjected to an aging treatment after laminating each layer. By changing the aging treatment conditions of the electrical storage device packaging material, the L ^* value, a ^* value, and b ^* value of the electrical storage device packaging material having a black appearance can be changed. Therefore, it is preferable to select the aging treatment conditions for the purpose of adjusting the L ^* value, a ^* value, and b ^* value. Examples of adjustment items for the aging treatment conditions include the temperature rise rate, heating temperature, heating time, whether or not pretreatment is performed, and the temperature thereof. Note that the main factor that causes the L ^* value, a ^* value, and b ^* value to change depending on the aging treatment conditions is that the degree of aggregation of the colorant contained in the electrical storage device packaging material changes depending on the aging treatment conditions.

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

Specifically, an electricity storage device using the electricity storage device packaging material of the present disclosure is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure, with metal terminals connected to the positive electrode and negative electrode protruding outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) is formed around the periphery of the electricity storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed to form a hermetic seal. When an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inward (the surface that contacts the electricity storage device element).

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

The present disclosure will be explained in detail below using examples and comparative examples. However, the present disclosure is not limited to the examples.

<Manufacturing of exterior materials for electricity storage devices>
Examples 1-7, 14, 15 and Comparative Example 1
An oriented nylon (ONy) film (thickness: 15 μm) was prepared as the substrate layer. Furthermore, aluminum foil (JIS H4160:1994 A8021H-O (thickness: 35 μm)) was prepared as the barrier layer. Next, the barrier layer and the substrate layer were laminated by dry lamination using the adhesive (a two-component urethane adhesive containing a colorant) described below, followed by aging treatment to produce a substrate layer/adhesive layer/barrier layer laminate. Both sides of the aluminum foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum foil by roll coating so that the coating amount of chromium was 10 mg/m ² (dry mass), followed by baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick) and random polypropylene as a heat-sealable resin layer (20 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer. Furthermore, a resin composition containing silica particles (a polyurethane resin formed from a mixture of a polyol compound and an isocyanate compound) was applied to the surface of the substrate layer of the obtained laminate to a thickness of 3 μm to form a matte surface coating layer, resulting in a laminate (total thickness 96 μm) consisting of, from outside in, surface coating layer (3 μm), substrate layer (15 μm thick), adhesive layer (3 μm), barrier layer (35 μm), adhesive layer (20 μm), and heat-sealable resin layer (20 μm).

Example 8
A laminate (total thickness 93 μm) in which a base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 1, except that the surface coating layer in Example 1 was not formed.

Example 9
A laminate (total thickness 93 μm) in which a base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 3, except that the surface coating layer was not formed.

Example 10
A laminate (total thickness 93 μm) in which a base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 4, except that the surface coating layer was not formed.

Example 11
A laminate (total thickness 93 μm) in which the base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 5, except that the surface coating layer was not formed.

Example 12
A laminate (total thickness 93 μm) in which a base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 2, except that the surface coating layer was not formed.

Examples 13, 16-20
A laminate (total thickness 93 μm) in which the base material layer (thickness 15 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (20 μm)/thermally adhesive resin layer (20 μm) were laminated was obtained in the same manner as in Example 1, except that no surface coating layer was formed and that adhesives B and C4 to C8 shown in Table 1 were used instead of adhesive A as the adhesive used to form the adhesive layer.

<Adhesive>
The following adhesives were used to form the adhesive layer between the substrate layer and the barrier layer. The types of adhesives used in each example and comparative example are shown in Table 1.
[Adhesive A]
Two-component urethane adhesive (a mixture of polyol compounds and aromatic isocyanate compounds) containing carbon black (secondary particle diameter 0.2 μm) as a blackening agent
[Adhesive B]
A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing, as a blackening agent, carbon black (secondary particle diameter 0.2 μm) with a larger primary particle diameter than the carbon black contained in adhesive A.
[Adhesive C1]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 26 parts by mass of carbon black and 4 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C2]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 15 parts by mass of carbon black and 15 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C3]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 13 parts by mass of carbon black and 17 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C4]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 20 parts by mass of carbon black and 10 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C5]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 18 parts by mass of carbon black and 12 parts by mass of copper phthalocyanine as a blue agent.
[Adhesive C6]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 22 parts by mass of carbon black and 8 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C7]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 16 parts by mass of carbon black and 14 parts by mass of copper phthalocyanine as a blue agent was used.
[Adhesive C8]
The black agent used was the same carbon black as that contained in adhesive A. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 14 parts by mass of carbon black and 16 parts by mass of copper phthalocyanine as a blue agent was used.

<Aging treatment conditions>
The aging treatment conditions used to adjust the color observed from the outside for the exterior packaging materials for an electricity storage device produced in each of the Examples and Comparative Examples are as follows.
[Condition A]
The mixture is left standing in an 80°C environment for 12 hours.
[Condition B]
First, in step 1, the sample is left standing at room temperature (approximately 25°C) for 3 hours. Next, in step 2, the sample is left standing in a 55°C environment for 3 hours. Next, in step 3, the sample is left standing in an 80°C environment for 12 hours.
[Condition C]
The container is left standing in an environment of 60 to 100°C for 3 days.

<Measurement of L ^* value, a ^* value, and b ^* value>
For the exterior packaging materials for electricity storage devices obtained in each Example and Comparative Example, the L*, a*, and b* of the outer (substrate layer side) surface were measured at room temperature and humidity using a spectrophotometer (CM-700d ⁾ manufactured by Konica Minolta, calibrated with a white calibration cap (CM- ^A177 : manufactured by Konica Minolta), with the observation conditions set to 10°, the observation light source set to ^F2 , and SCI mode (JIS Z8722-2009). Three points were measured for each sample, and the average values are shown in Table 1 as evaluation results.

<Measurement of Cu element by X-ray fluorescence spectrometry (XRF)>
The presence or absence of detection of Cu element was confirmed by X-ray fluorescence analysis (XRF) under the following measurement conditions for the exterior packaging materials for electricity storage devices obtained in Examples 1 to 5 and Comparative Example 1. As a result, no peaks derived from Cu element were detected in Examples 1 and 2 and Comparative Example 1. Furthermore, peaks derived from Cu element were detected in Examples 3, 4, and 5. The CuKα peak intensity was 0.4 in Example 3, 1.2 in Example 4, and 1.2 in Example 5.
(Measurement conditions)
Equipment used: EDX-800HS (Shimadzu Corporation)
X-ray: Rh target voltage: 50 kV
Current: 1000μA
Irradiation area: 100φ
Measurement time: 100 seconds
Measurement atmosphere: vacuum Measurement surface: outside (X-rays are irradiated onto the outside of the exterior material for an electricity storage device)
Analysis method: Automatic intensity calculation is performed using the software "PCEDX" attached to the EDX-800HS (Shimadzu Corporation). Specifically, peak detection is performed on the spectrum obtained by measurement. The coefficient of the peak detection condition is set to 10. Next, the detected intensity is calculated for the detected peaks.

<Distinguishing ability in the yellow room>
The surface of the surface coating layer of the exterior materials for electrical storage devices obtained in each Example and Comparative Example was printed with an inkjet printer (Model 9040, manufactured by Markem Image Co., Ltd.) to create a sample, printing the number string "0123456789" with a dot diameter of approximately 0.3 mm and a character string height of approximately 1.5 mm. The ink used for printing was white. Next, each sample was observed with the naked eye from a distance of 30 cm in a yellow room, and the distinctiveness was evaluated according to the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
A: Immediate recognition possible B: Recognition takes several seconds C: Recognition possible by changing the sample angle

<Black exterior>
Each sample prepared in the above "Distinguishing ability in a yellow room" was observed with the naked eye in a room under fluorescent lighting, and evaluated for whether its appearance was recognized as black according to the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
A: It is clearly recognized as black.
B: A slight blue or red color is perceived, but the color is perceived as black without any problems. C: A clear blue or red color is perceived, and there is a risk that the color may not be perceived as black.

As is clear from the results shown in Table 1, the electrical storage device packaging materials of Examples 1 to 20 had b ^* values in the L ^* a ^* b ^* color space of reflected light measured from the outside using the SCI method, a field of view of 10°, and light source F2, of -0.20 or less. This indicates that, despite being electrical storage device packaging materials with a black appearance, they had excellent recognizability of the identification mark printed on their surfaces in a yellow room. The electrical storage device packaging materials of Examples 1 to 20 also had excellent recognizability of the identification mark printed on their surfaces not only in a yellow room but also indoors under general fluorescent lighting. Furthermore, the electrical storage device packaging materials of Examples 1 to 20 could be easily recognized as having a black appearance indoors under general fluorescent lighting.

As described above, the present disclosure provides the following aspects of the invention.
Item 1. An exterior packaging material for an electricity storage device that has a black appearance,
the electrical storage device packaging material is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer;
An exterior material for a storage battery device, wherein the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is −0.20 or less.
Item 2. The exterior material for a storage battery device according to Item 1, wherein the a ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is +0.2 or less.
Item 3. An adhesive layer is provided between the base layer and the barrier layer,
Item 3. The packaging material for an electricity storage device according to Item 1 or 2, wherein the adhesive layer contains a colorant.
Item 4. A colored layer is provided between the substrate layer and the barrier layer,
Item 4. The electrical storage device packaging material according to any one of items 1 to 3, wherein the colored layer contains a pigment.
Item 5. The packaging material for an electricity storage device according to any one of Items 1 to 4, further comprising a surface coating layer on the side of the base material layer opposite to the barrier layer side.
Item 6. The packaging material for an electricity storage device according to any one of Items 1 to 5, wherein elemental Cu is detected when the laminate is analyzed from the outside by fluorescent X-ray analysis.
Item 7. A method for producing an exterior material for an electricity storage device having a black appearance, comprising:
The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a thermally adhesive resin layer are laminated in this order from the outside,
A method for producing an exterior material for an electricity storage device, wherein the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is −0.20 or less.
Item 8. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an electricity storage device according to any one of Items 1 to 6.

REFERENCE SIGNS LIST 1 Base material layer 2 Adhesive layer 21 Colored layer 3 Barrier layer 4 Heat-sealable resin layer 5 Adhesive layer 6 Surface coating layer 10 Electricity storage device packaging material

Claims (17)

An exterior material for an electricity storage device that has a black appearance,
the electrical storage device packaging material is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer;
the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is −5.00 or more and −0.20 or less ;
the a ^* value of the reflected light in the L ^* a ^* b ^* color space is −3.50 or more and +0.20 or less;
The exterior material for an electricity storage device, wherein the reflected light has an L ^* value of 40 or less in the L ^* a ^* b ^* color space. 2. The exterior material for a storage battery device according to claim 1, wherein the a ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10 °, and a light source F2 is +0.10 or less. an adhesive layer is provided between the substrate layer and the barrier layer,
The packaging material for an electricity storage device according to claim 1 or 2, wherein the adhesive layer contains a colorant. a colored layer is provided between the substrate layer and the barrier layer,
The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein the colored layer contains a pigment. The exterior packaging material for an electricity storage device according to any one of claims 1 to 4, further comprising a surface coating layer on the side of the substrate layer opposite the barrier layer. The exterior packaging material for an electricity storage device according to any one of claims 1 to 5, wherein Cu element is detected when the laminate is analyzed from the outside by fluorescent X-ray analysis. The packaging material for an electricity storage device according to any one of claims 1 to 6, wherein the b ^* value of reflected light in the L ^* a ^* b ^* color space is -1.20 or more. The exterior packaging material for an electricity storage device according to any one of claims 1 to 7, wherein the a ^* value of reflected light in the L ^* a ^* b ^* color space is -0.07 or more. a lubricant is present on the surface of the heat-sealable resin layer;
The exterior packaging material for an electricity storage device according to any one of claims 1 to 8, wherein the lubricant is present in an amount of 10 mg/m2 or ^more . The packaging material for an electricity storage device according to any one of claims 1 to 9, wherein two or more types of lubricants are present on at least one of the surface and interior of the heat-sealable resin layer. The exterior packaging material for an electricity storage device according to any one of claims 1 to 10, wherein at least two or more compounds selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides are present on at least one of the surface and interior of the heat-sealable resin layer. a surface coating layer on the opposite side of the substrate layer from the barrier layer,
The packaging material for an electricity storage device according to any one of claims 1 to 11, wherein a lubricant is present on at least one of the surface and the interior of the surface coating layer. a surface coating layer on the opposite side of the substrate layer from the barrier layer,
The exterior packaging material for an electricity storage device according to any one of claims 1 to 12, wherein two or more types of lubricants are present on at least one of the surface and the interior of the surface coating layer. a surface coating layer on the opposite side of the substrate layer from the barrier layer,
The exterior material for a storage battery device according to any one of claims 1 to 13, wherein at least two or more selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides are present on at least one of the surface and the interior of the surface coating layer. A method for producing an exterior material for an electricity storage device having a black appearance,
The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a thermally adhesive resin layer are laminated in this order from the outside,
the b ^* value in the L ^* a ^* b ^* color space of reflected light measured from the outside of the laminate under measurement conditions of an SCI method, a field of view of 10°, and a light source F2 is −5.00 or more and −0.20 or less ;
the a ^* value of the reflected light in the L ^* a ^* b ^* color space is −3.50 or more and +0.20 or less;
The method for producing an exterior material for an electricity storage device, wherein the reflected light has an L ^* value of 40 or less in an L ^* a ^* b ^* color space. an adhesive layer is provided between the barrier layer and the heat-sealable resin layer,
16. The method for producing an exterior material for an electricity storage device according to claim 15, wherein the barrier layer and the heat-sealable resin layer are formed by a co-extrusion lamination method, a tandem lamination method, a thermal lamination method, a sandwich lamination method, or a method of solution-coating an adhesive for forming the adhesive layer onto the barrier layer, and laminating the heat-sealable resin layer, which has been formed in advance into a sheet shape, onto the adhesive layer. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of claims 1 to 14.