JP7474563B2 - Packaging material for batteries, its manufacturing method, roll of packaging material for batteries, and battery - Google Patents

Description

The present invention relates to a packaging material for batteries, a manufacturing method thereof, a roll of the packaging material for batteries, and a battery.

Traditionally, various types of batteries have been developed, and packaging materials are essential components for sealing battery elements such as electrodes and electrolytes in all batteries. Traditionally, metallic packaging materials have been widely used for packaging batteries, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have a variety of shapes and are also required to be thinner and lighter. However, the metallic battery packaging materials that have been widely used traditionally have the disadvantage that they are difficult to keep up with the diversification of shapes and also have limitations on how much they can be made lighter.

A film-like laminate in which a base layer, a metal foil layer, and a heat-sealable resin layer are laminated in this order has been proposed as a battery packaging material that can be easily processed into various shapes and can be made thinner and lighter (see, for example, Patent Document 1). In such a film-like battery packaging material, the heat-sealable resin layers are placed opposite each other and the peripheral portions are heat-sealed to seal the battery element.

Such battery packaging materials are generally manufactured on the production line as strip-shaped laminated film, which is then wound into a roll for storage, transport, etc. When batteries are manufactured, the battery packaging material is unwound from the roll and cut into a specified shape according to the product specifications of the battery for use.

JP 2008-287971 A

To improve the safety and extend the life of batteries that use battery packaging materials made of such laminated films, it is necessary to minimize moisture permeation through the battery packaging material. Therefore, in general, the manufacturing process for battery packaging materials is managed and produced with particular emphasis on pinholes in the metal foil layer, and battery packaging materials in which pinholes of a certain size exist in the metal foil layer are manufactured by uniformly removing the surrounding area where the pinhole exists.

However, removing the pinholes in the metal foil layer reduces the yield of battery packaging materials and increases the manufacturing costs of the batteries. In addition, when moisture control becomes stricter, for example when using solid electrolyte batteries, pinhole inspection becomes more complicated, resulting in higher inspection costs.

In addition, by improving the manufacturing process of the metal foil, metal foils that have as few pinholes as possible have been produced, but because such metal foils are expensive, the problem of increased battery manufacturing costs has not been resolved in this case either.

In view of these problems with the conventional technology, the main objective of the present invention is to provide a packaging material for batteries that can effectively prevent moisture from penetrating into the battery and can effectively prevent increases in the manufacturing costs of the battery.

The present inventors have conducted intensive research to solve the above problems. As a result, it has been found that a battery packaging material composed of a laminate having at least a base material layer, a metal foil layer, and a heat-sealable resin layer in this order, in which the metal foil layer has pinholes with a total area of 1.0 x 10 ⁶ μm ² or less per area of the battery packaging material used for one battery, the laminate further has at least one gas barrier layer on the base material layer side of the heat-sealable resin layer, and the gas barrier layer includes a thin film layer of 5 μm or less composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic and inorganic composite materials, can effectively suppress moisture permeation into the battery and can effectively suppress an increase in the manufacturing cost of the battery. The present invention has been completed based on these findings and through further research.

That is, the present invention provides the following aspects.
Item 1. A battery packaging material comprising a laminate including at least a base layer, a metal foil layer, and a heat-sealable resin layer in this order,
the metal foil layer has pinholes with a total area of 1.0×10 ⁶ μm ² or less per area of the battery packaging material used for one battery;
The laminate further includes at least one gas barrier layer on the base layer side of the thermally adhesive resin layer,
The gas barrier layer comprises a thin film layer having a thickness of 5 μm or less and composed of at least one material selected from the group consisting of an inorganic material, an organic material, and an organic-inorganic composite material.
Item 2. The battery packaging material according to Item 1, wherein the gas barrier layer further includes a resin film layer.
Item 3. The battery packaging material according to Item 1 or 2, wherein the thin film layer is made of aluminum or silica.
Item 4. A roll of a battery packaging material comprising a laminate including at least a base layer, a metal foil layer, and a heat-sealable resin layer in this order,
When a section having an area of ²⁵⁰⁰ mm2 is defined in the metal foil layer of the roll, at least one section has pinholes with a total area of 1.0 x ^{106 μm2} or less,
The laminate further includes at least one gas barrier layer on the base layer side of the thermally adhesive resin layer,
The gas barrier layer comprises a thin film layer having a thickness of 5 μm or less and composed of at least one material selected from the group consisting of an inorganic material, an organic material, and an organic-inorganic composite material.
Item 5. A battery, in which at least a positive electrode, a negative electrode, and an electrolyte are housed in a package formed from the battery packaging material according to any one of Items 1 to 3.
Item 6. A method for producing a battery packaging material, comprising a step of laminating at least a base material layer, a metal foil layer, and a heat-sealable resin layer in this order,
the metal foil layer has pinholes with a total area of 1.0×10 ⁶ μm ² or less per area of the battery packaging material used for one battery;
further laminating at least one gas barrier layer on the base layer side of the thermally adhesive resin layer of the laminate,
The method for producing a packaging material for batteries, wherein the gas barrier layer includes a thin film layer having a thickness of 5 μm or less and composed of at least one material selected from the group consisting of an inorganic material, an organic material, and an organic-inorganic composite material.
Item 7. An aluminum alloy foil for use in a metal foil layer of a packaging material for batteries, comprising:
The battery packaging material is composed of a laminate including at least a base layer, the metal foil layer, and a heat-sealable resin layer in this order,
The laminate further includes at least one gas barrier layer on the base layer side of the thermally adhesive resin layer,
the gas barrier layer includes a thin film layer having a thickness of 5 μm or less and made of at least one material selected from the group consisting of an inorganic material, an organic material, and an organic-inorganic composite material;
The aluminum alloy foil for use as a battery packaging material has pinholes with a total area of 1.0 x ¹⁰⁶ µm2 or ^less per area of the battery packaging material used for one battery.

According to the present invention, it is possible to provide a battery packaging material that can effectively suppress moisture permeation into the battery and effectively suppress increases in the manufacturing costs of the battery. In addition, according to the present invention, it is also possible to provide a manufacturing method of the battery packaging material, a roll of the battery packaging material, and a battery using the battery packaging material.

1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention. 1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention. 1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention. 1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention. 1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention. 1 is a diagram showing an example of a cross-sectional structure of a battery packaging material of the present invention.

The battery packaging material of the present invention is a battery packaging material composed of a laminate having at least a base layer, a metal foil layer, and a heat-sealable resin layer in this order, and the metal foil layer has pinholes with a total area of 1.0 x 10 ⁶ μm ² or less per area of the battery packaging material used for one battery, and the laminate further has at least one gas barrier layer on the base layer side of the heat-sealable resin layer, and the gas barrier layer includes a thin film layer of 5 μm or less composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic and inorganic composite materials. In the battery packaging material of the present invention, by having such a configuration, it is possible to effectively suppress moisture permeation into the battery, and since it is not necessary to use expensive metal foil without pinholes as the metal foil layer, it is possible to effectively suppress an increase in the manufacturing cost of the battery. Furthermore, the battery packaging material of the present invention can prevent the diffusion and leakage of the electrolyte from the inside. The battery packaging material of the present invention will be described in detail below.

In this specification, the numerical range indicated by "~" means "greater than or equal to" or "less than or equal to." For example, the expression 2-15 mm means 2 mm or more and 15 mm or less.

1. Laminated Structure of Battery Packaging Material The battery packaging material 10 of the present invention is composed of a laminate including at least a base material layer 1, a metal foil layer 3, and a heat-sealable resin layer 4 in this order, as shown in Fig. 1. In the battery packaging material 10 of the present invention, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. That is, when the battery is assembled, the heat-sealable resin layers 4 located on the periphery of the battery element are heat-sealed to each other to seal the battery element, thereby sealing the battery element.

As shown in Figs. 1 to 6, the laminate constituting the battery packaging material 10 of the present invention further comprises at least one gas barrier layer 6 on the substrate layer 1 side of the heat-sealable resin layer 4. As described below, the gas barrier layer 6 includes a thin film layer 61 composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic-inorganic composite materials. The gas barrier layer 6 may be composed of only the thin film layer 61, or may further include a resin film layer 62. Figs. 1 to 3 show an example in which the gas barrier layer 6 is composed of only the thin film layer 61. Also, Figs. 4 to 6 show an example in which the gas barrier layer 6 is composed of a laminate of the thin film layer 61 and the resin film layer 62.

In the battery packaging material 10 of the present invention, the position where the gas barrier layer 6 is laminated is not particularly limited as long as it is not on the surface side of the heat-sealable resin layer 4 (i.e., the surface opposite the base layer 1 of the laminate). The gas barrier layer 6 can be provided at least in one or more locations among, for example, between the base layer 1 and the metal foil layer 3, between the metal foil layer 3 and the heat-sealable resin layer 4, between the base layer 1 and the adhesive layer 2, between the adhesive layer 2 and the metal foil layer 3, between the metal foil layer 3 and the adhesive layer 5, between the adhesive layer 5 and the heat-sealable resin layer 4, between the surface coating layer and the base layer 1, and on the surface of the base layer 1 side of the laminate. The gas barrier layer 6 may be laminated in a plurality of layers. When multiple gas barrier layers 6 are laminated, the multiple gas barrier layers 6 may be laminated adjacent to each other (for example, two gas barrier layers 6 are laminated between the base layer 1 and the metal foil layer 3) or may be laminated at different positions (for example, a gas barrier layer 6 is provided between the base layer 1 and the metal foil layer 3, and a gas barrier layer 6 is further provided between the metal foil layer 3 and the heat-sealable resin layer 4).

1, 4, and 6 show an embodiment in which the gas barrier layer 6 is provided between the substrate layer 1 and the metal foil layer 3. More specifically, FIG. 1 shows an embodiment in which the gas barrier layer 6 is provided between the substrate layer 1 and the adhesive layer 2, and is made of a thin film layer 61. FIG. 4 shows an embodiment in which the gas barrier layer 6 is provided between the substrate layer 1 and the adhesive layer 2, and is made of a thin film layer 61 and a resin film layer 62. FIG. 6 shows an embodiment in which the gas barrier layer 6 is provided between the substrate layer 1 and the metal foil layer 3, and is made of a thin film layer 61 and a resin film layer 62. In the battery packaging material 10 of the present invention, the gas barrier layer 6 may also serve as the adhesive layer 5 that bonds the layers together.

For example, Figs. 2 and 5 show an example in which the gas barrier layer 6 is provided between the metal foil layer 3 and the heat-sealable resin layer 4. More specifically, Fig. 2 shows an example in which the gas barrier layer 6 made of a thin film layer 61 is provided between the adhesive layer 5 and the heat-sealable resin layer 4. Fig. 5 shows an example in which the gas barrier layer 6 made of a thin film layer 61 and a resin film layer 62 is provided between the adhesive layer 5 and the heat-sealable resin layer 4.

For example, FIG. 3 shows an embodiment in which the gas barrier layer 6 is provided on the surface of the base layer 1 side of the laminate constituting the battery packaging material 10. More specifically, FIG. 3 shows an embodiment in which the gas barrier layer 6 made of a thin film layer 61 is provided on the surface of the base layer 1.

The battery packaging material 10 of the present invention may have an adhesive layer 2 between the base layer 1 and the metal foil layer 3, as shown in, for example, Figures 1 to 5. Also, as shown in Figures 2 and 5, an adhesive layer 5 may be provided between the metal foil layer 3 and the heat-sealable resin layer 4. Furthermore, although not shown, a surface coating layer may be provided on the outside of the base layer 1 (the side opposite to the heat-sealable resin layer 4) as necessary. Also, although not shown, an adhesive layer 2 may be provided, as necessary, between, for example, the base layer 1 and the resin film layer 62 in Figure 4, or between, for example, the base layer 1 and the thin film layer 61 in Figure 6.

The thickness of the laminate constituting the battery packaging material 10 of the present invention is not particularly limited, but from the viewpoint of reducing the thickness of the battery packaging material 10 to increase the energy density of the battery while providing a battery packaging material 10 with excellent moldability, the thickness may be, for example, about 180 μm or less, preferably about 150 μm or less, more preferably about 60 to 180 μm, and even more preferably about 60 to 150 μm.

As described below, the battery packaging material 10 of the present invention can be stored and distributed, for example, in the form of a roll, and can be cut to the desired size for use when manufacturing batteries.

The water vapor transmission rate per ^m2 of the battery packaging material of the present invention is preferably about 1.1× ^10-3 g/ ^m2 /24h or less, more preferably about 8.0× ^10-4 g/ ^m2 /24h or less, and even more preferably about 5.2× ^10-4 g/ ^m2 /24h or less. The lower limit of the total water vapor transmission rate is, for example, about 9.7× ^10-6 g/ ^m2 /24h, about 9.7× ^10-7 g/ ^m2 /24h, about 9.7× ^10-8 g/ ^m2 /24h, etc. The water vapor transmission rate is measured as follows.

<Measurement of water vapor transmission rate per ¹ m2>
The water vapor transmission rate (g/ ^m2 /24h) per ^m2 (area of one side) of the battery packaging material is measured by the following method. A method conforming to the ISO15106-5 2008 regulations is adopted, and the sample is placed so that there is a pinhole within the measurement area of the aluminum alloy foil under the measurement conditions of a temperature of 40°C, a relative humidity of 90%, a measurement period of 24 hours, and a measurement area of 8 cmφ, and the measurement is performed using a water vapor transmission rate measuring device using a differential pressure method. The water vapor transmission rate per ^m2 is a value converted to ^m2 using the ISO water vapor transmission rate measurement method.

The total water vapor transmission rate per day (24 hours) of the pinhole site of the battery packaging material of the present invention is preferably about 5.5×10 ⁻⁶ g/24 h or less, more preferably about 4.1×10 ⁻⁶ g/24 h or less, and even more preferably about 2.7×10 ⁻⁶ g/24 h or less. The lower limit of the total water vapor transmission rate is, for example, about 5.0×10 ⁻⁸ g/24 h, about 5.0×10 ⁻⁹ g/24 h, about 5.0×10 ⁻¹⁰ g/24 h, etc. The method for measuring the total water vapor transmission rate is as follows.

<Total water vapor transmission rate at pinhole locations>
The total water vapor transmission rate per ^m2 of the battery packaging material measured by the method described in the Examples below is used to calculate the total water vapor transmission rate of the pinhole area in one day (24 hours). The total water vapor transmission rate of the pinhole area is the total water vapor transmission rate of the area where the pinhole exists (however, the area other than the pinhole area is set to zero). More specifically, the method described in the Examples is adopted.

2. Layers forming the battery packaging material [Gas barrier layer 6]
The gas barrier layer 6 is a layer provided in the battery packaging material 10 of the present invention, which has a pinhole of a predetermined size in the metal foil layer, in order to suppress moisture permeation into the battery. In the battery packaging material 10 of the present invention, the position at which the gas barrier layer 6 is laminated is not particularly limited as long as it is not on the front side of the heat-sealable resin layer 4 (i.e., the surface of the laminate opposite the base material layer 1), and specific examples of the position at which the gas barrier layer 6 is provided are as described above.

As described above, the gas barrier layer 6 includes a thin film layer 61 made of at least one material selected from the group consisting of an inorganic material, an organic material, and an organic-inorganic composite material. The thin film layer 61 may be a single layer or a multilayer. For example, the thin film layer 61 may be a laminate of a layer made of an organic material and a layer made of an inorganic material. The gas barrier layer 6 may be made of only the thin film layer 61, or may further include a resin film layer 62.

In the thin film layer 61, the inorganic material is not particularly limited as long as it exhibits the function of suppressing moisture permeation, and examples thereof include metals such as aluminum, stainless steel, and titanium; and carbon-containing inorganic oxides such as inorganic oxides such as silicon oxide, titanium oxide, aluminum oxide, and manganese oxide. The thin film layer 61 is preferably a vapor deposition film of these metals, inorganic oxides, or carbon-containing inorganic oxides, and is particularly preferably a vapor deposition film of aluminum. The vapor deposition film may be made of only one type of component, or two or more types.

The organic material in the thin film layer 61 is not particularly limited as long as it has the function of suppressing moisture permeation, and examples of the organic material include polyacrylic acid, epoxy resin, and polyvinyl alcohol. The organic material constituting the thin film layer 61 may be of only one type, or of two or more types.

In addition, in the thin film layer 61, the organic-inorganic composite material is not particularly limited as long as it exhibits the function of suppressing moisture permeation, and examples thereof include composite materials of silica as an inorganic component and resin as an organic component. Composite materials of inorganic and organic components are known to be formed, for example, by employing a sol-gel method, and a specific example is a composite material of silica and polyvinyl alcohol (silica uniformly dispersed in polyvinyl alcohol (PVA)). In the sol-gel method, in addition to PVA, PVA modified with a carboxyl group or an acetoacetyl group can be used as the organic component, and silicon alkoxide (tetraethoxysilane, methyltriethoxysilane, etc.) can be used as the inorganic component. In the organic-inorganic composite material, the inorganic material is uniformly dispersed in the organic material to form the thin film layer 61. The organic-inorganic composite material constituting the thin film layer 61 may be only one type, or may be two or more types.

In the present invention, for example, by providing a gas barrier layer 6 including a thin film layer 61 between the base material layer 1 and the adhesive layer 2, the adhesive strength between the base material layer 1 and the metal foil layer 3 can be improved, and the adhesive layer 2 that bonds the base material layer 1 and the metal foil layer 3 can be easily selected. That is, the adhesion between the base material layer 1 made of a resin and the metal foil layer 3 made of a metal is generally between different materials, so there are restrictions on the selection of the adhesive layer 2 that increases the adhesive strength between these layers. In contrast, when a thin film layer 61 made of an inorganic material such as a metal is provided between the base material layer 1 and the adhesive layer 2, the adhesive layer 2 bonds between the thin film layer 61 made of an inorganic material and the metal foil layer 3, and the adhesive layer 2 bonds between the same materials, improving the adhesive strength and making it easier to select an adhesive that forms the adhesive layer 2.

The thickness of the thin film layer 61 is preferably 5 μm or less, and from the viewpoint of exerting the function of suppressing moisture permeation, the lower limit is preferably about 0.01 μm or more, more preferably about 0.02 μm or more, and the upper limit is preferably about 3 μm or less, more preferably about 1 μm or less. Preferred ranges of the thickness of the thin film layer 61 include about 0.01 to 5 μm, about 0.01 to 3 μm, about 0.01 to 1 μm, about 0.02 to 5 μm, about 0.03 to 5 μm, and about 0.02 to 1 μm. By making the thickness of the thin film layer 61 5 μm or less, it is possible to suppress an increase in the thickness of the battery packaging material 10 while maintaining the gas barrier properties of the battery packaging material 10, and also to reduce costs and reduce the possibility of cracks due to thickening when molding.

The resin film layer 62 is a layer that is provided to form the gas barrier layer 6 together with the thin film layer 61 as necessary. The resin film layer 62 is provided between the base material layer 1 and the heat-sealable resin layer 4. For example, when the thin film layer 61 has a thickness of 5 μm or less, it is difficult to handle it by itself. However, by preparing a laminate film in which the thin film layer 61 is laminated on the surface of the resin film layer 62 as the gas barrier layer 6 in advance, and laminating it with the base material layer 1, the metal foil layer 3, and the heat-sealable resin layer 4 described below, the battery packaging material 10 of the present invention can be easily manufactured.

For example, when the thin film layer 61 is formed on the surface of the base layer 1, the battery packaging material 10 of the present invention can be easily manufactured by first preparing the thin film layer 61 laminated on the surface of the base layer 1 and then laminating this with the metal foil layer 3 and the heat-sealable resin layer 4 described below. In such a case, the resin film layer 62 is not particularly required.

The material forming the resin film layer 62 is not particularly limited, and examples thereof include the resin films exemplified in the substrate layer 1 described below, and preferably polyester resins and polyamide resins. Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and copolymer polyesters. Specific examples of polyamide resins include nylon 6, nylon 66, copolymers of nylon 6 and nylon 66, nylon 6,10, and polyamide MXD6 (polymetaxylylene adipamide).

In the gas barrier layer 6, the thin film layer 61 may be a single layer or multiple layers. When the thin film layer 61 is multiple layers, the gas barrier layer 6 may have a laminated structure in which the thin film layer 61/thin film layer 61/resin film layer 62 are laminated in this order, or a laminated structure in which the thin film layer 61/resin film layer 62/thin film layer 61/resin film layer 62 are laminated in this order.

The thickness of the resin film layer 62 is not particularly limited, but from the viewpoint of suitably laminating the laminate film in which the thin film layer 61 is laminated on the resin film layer 62 as the gas barrier layer 6 with other layers, the thickness is preferably about 5 to 50 μm, and more preferably about 10 to 30 μm.

The total thickness of the gas barrier layer 6 is not particularly limited, but is preferably about 0.01 to 50 μm, and more preferably about 0.02 to 30 μm.

The water vapor transmission rate of the gas barrier layer 6 is preferably about 10 g/m ² ·24 h or less, more preferably about 5 g/m ² ·24 h or less, and even more preferably about 2 g/m ² ·24 h or less. The preferred lower limit of the water vapor transmission rate of the gas barrier layer 6 is 1.0×10 ⁻¹⁰ g/m ² ·24 h. More specifically, in the battery packaging material 10 of the present invention, when the pinhole area present per m ² of the battery packaging material 10 is 10,000 μm ² or less, the water vapor transmission rate of the gas barrier layer 6 is preferably about 10 g/m ² ·24 h or less, more preferably about 5 g/m ² ·24 h or less, and even more preferably about 2 g/m ² ·24 h or less. In addition, when the pinhole area present in ¹ m2 of the battery packaging material 10 is more than 10,000 ^{μm2 and} 100,000 ^μm2 or less, the water vapor transmission rate of the gas barrier layer 6 is preferably about 2 g/ ^m2 ·24 h or less, more preferably about 1.5 g/ ^m2 ·24 h or less, and even more preferably about 1 g/ ^m2 ·24 h or less. In addition, when the pinhole area present in ¹ m2 of the battery packaging material ¹⁰ is more than 100,000 μm2 and 500,000 μm2 ^or less, the water vapor transmission rate of the gas barrier layer 6 is preferably about 0.5 g/ ^m2 ·24 h or less, more preferably about 0.3 g/ ^m2 ·24 h or less, and even more preferably about 0.2 g/ ^m2 ·24 h or less. Furthermore, when the area of pinholes present per ^m2 of the battery packaging material 10 is more than 500,000 ^μm2 and 1,000,000 ^μm2 or less, the water vapor transmission rate of the gas barrier layer 6 is preferably about 0.2 g/ ^m2 ·24 h or less, more preferably about 0.1 g/ ^m2 ·24 h or less, and even more preferably about 0.08 g/ ^m2 ·24 h or less. The preferred lower limit of the water vapor transmission rate of the gas barrier layer 6 is 1.0× ^10-10 g/ ^m2 ·24 h. The water vapor transmission rate of the battery packaging material 10 is a value measured by the following method. The water vapor transmission rate of the gas barrier layer 6 is a value measured by the following method.

<Measurement of water vapor transmission rate per ^m2 of gas barrier layer>
The water vapor transmission rate (g/ ^m2 /24h) per ^m2 (area of one side) of the gas barrier layer is measured using a water vapor transmission rate measuring device (DELTAPERM, product name, manufactured by Techno-I Co., Ltd.) using a differential pressure method under measurement conditions of a temperature of 40°C, a relative humidity of 90%, a measurement period of 24 hours, and a measurement area of 8 cmφ, in accordance with the method of ISO15106-5 2008. The water vapor transmission rate per ^m2 is a value converted to ^m2 using the ISO water vapor transmission rate measurement method.

[Base layer 1]
In the battery packaging material 10 of the present invention, the base layer 1 is a layer located on the outermost layer side. The material forming the base layer 1 is not particularly limited as long as it has insulating properties. Examples of materials forming the base layer 1 include resin films such as polyester resin, polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenolic resin, polycarbonate, and mixtures and copolymers thereof. Among these, polyester resin and polyamide resin are preferable, and biaxially oriented polyester resin and biaxially oriented polyamide resin are more preferable. Specific examples of polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and copolymer polyester. Specific examples of polyamide resin include nylon 6, nylon 66, a copolymer of nylon 6 and nylon 66, nylon 6,10, and polymetaxylylene adipamide (MXD6).

The base layer 1 may be formed of one layer of resin film, but may be formed of two or more layers of resin film in order to improve pinhole resistance and insulation. Specifically, a multi-layer structure in which a polyester film and a nylon film are laminated, a multi-layer structure in which multiple nylon films are laminated, a multi-layer structure in which multiple polyester films are laminated, etc. are mentioned. When the base layer 1 has a multi-layer structure, a laminate of a biaxially oriented nylon film and a biaxially oriented polyester film, a laminate of multiple biaxially oriented nylon films, and a laminate of multiple biaxially oriented polyester films are preferred. For example, when the base layer 1 is formed of two layers of resin film, it is preferable to have a structure in which polyester resin and polyester resin are laminated, a structure in which polyamide resin and polyamide resin are laminated, or a structure in which polyester resin and polyamide resin are laminated, and it is more preferable to have a structure in which polyethylene terephthalate and polyethylene terephthalate are laminated, a structure in which nylon and nylon are laminated, or a structure in which polyethylene terephthalate and nylon are laminated. In addition, since polyester resin is less likely to discolor when an electrolyte solution adheres to the surface, it is preferable to laminate the base material layer 1 so that the polyester resin is located in the outermost layer in this laminated structure. When the base material layer 1 has a multi-layer structure, the thickness of each layer is preferably about 2 to 25 μm.

When the base layer 1 is formed of a multi-layer resin film, two or more resin films may be laminated via an adhesive component such as an adhesive or adhesive resin, and the type and amount of the adhesive component used are the same as those for the adhesive layer 2 described below. The method for laminating two or more layers of resin films is not particularly limited, and any known method can be used, such as the dry lamination method and sandwich lamination method, with the dry lamination method being preferred. When laminating using the dry lamination method, it is preferable to use a urethane adhesive as the adhesive layer. In this case, the thickness of the adhesive layer can be, for example, about 1 to 5 μm.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material 10, it is preferable that a lubricant is attached to 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 the same ones as those exemplified for the heat-sealable resin layer 4 described below.

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 in an environment of a temperature of 24°C and a relative humidity of 60%.

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

There are no particular limitations on the thickness of the substrate layer 1 as long as it functions as a substrate, but it may be, for example, about 3 to 50 μm, and preferably about 10 to 35 μm.

[Adhesive layer 2]
In the battery packaging material 10 of the present invention, the adhesive layer 2 is a layer that is provided, as necessary, between the base material layer 1 and the metal foil layer 3, the base material layer 1 and the gas barrier layer 6, the gas barrier layer 6 and the metal foil layer 3, or the gas barrier layer 6 and the heat-sealable resin layer 4 in order to firmly bond them together.

The adhesive layer 2 is formed by an adhesive capable of bonding the base layer 1 and the metal foil layer 3, the base layer 1 and the gas barrier layer 6, or the gas barrier layer 6 and the metal foil layer 3. The adhesive used to form the adhesive layer 2 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the adhesive used to form the adhesive layer 2 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a thermal melting type, a thermal pressure type, etc.

Specific examples of adhesive components that can be used to form the adhesive layer 2 include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyester; polycarbonate-based resins; polyether-based resins; polyurethane-based resins; epoxy-based resins; phenolic resin-based resins; polyamide-based resins such as nylon 6, nylon 66, nylon 12, and copolymer polyamide; polyolefin-based resins such as polyolefin, carboxylic acid-modified polyolefin, and metal-modified polyolefin; polyvinyl acetate-based resins; cellulose-based adhesives; (meth)acrylic resins; polyimide-based resins; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone-based resins. These adhesive components may be used alone or in combination of two or more. In addition, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent can be appropriately selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components. As these adhesive components and curing agents, polyurethane adhesives made of various polyols and polyisocyanates are preferred. More preferred are two-component curing polyurethane adhesives that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the main component and an aromatic or aliphatic polyisocyanate as the curing agent.

The adhesive layer 2 may contain a colorant such as a pigment.

There are no particular limitations on the thickness of the adhesive layer 2 as long as it functions as an adhesive layer, but examples of the thickness include about 1 to 10 μm, and preferably about 2 to 5 μm.

[Metal foil layer 3]
In the battery packaging material 10, the metal foil layer 3 is a layer that has the function of preventing water vapor, oxygen, light, and the like from penetrating into the inside of the battery in addition to improving the strength of the battery packaging material 10. Specific examples of metals constituting the metal foil layer 3 include aluminum, stainless steel, and titanium steel, and aluminum is preferred. From the viewpoint of suppressing the occurrence of wrinkles and pinholes in the metal foil layer 3 during the production of the battery packaging material 10, it is more preferable that the metal foil layer 3 is formed from an aluminum alloy foil or stainless steel foil.

The aluminum alloy foil is preferably made of soft aluminum alloy foil such as annealed aluminum alloy foil (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

Examples of stainless steel foil include austenitic stainless steel foil and ferritic stainless steel foil. It is preferable that the stainless steel foil is made of austenitic stainless steel.

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

As mentioned above, in order to improve the safety and extend the life of batteries using the battery packaging material 10, it is necessary to minimize moisture permeation through the battery packaging material 10. Therefore, in the manufacturing process of the battery packaging material 10, particular emphasis is generally placed on pinholes in the metal foil layer 3 during management and production, and battery packaging materials 10 in which pinholes of a certain size exist in the metal foil layer 3 are manufactured by uniformly removing the surrounding area where the pinhole exists.

In contrast, in the battery packaging material 10 of the present invention, the metal foil layer 3 has pinholes with a total area of 1.0 × 10 ⁶ μm ² or less per area of the battery packaging material 10 used for one battery. That is, in the battery packaging material 10 of the present invention, the gas barrier layer 6 including the above-mentioned thin film layer 61 with a thickness of 5 μm or less is provided, so that even if the periphery of the pinholes with the above total area is not uniformly removed from the metal foil layer 3, it is possible to effectively suppress an increase in the manufacturing cost of the battery while suppressing moisture permeation into the battery.

In the battery packaging material 10 of the present invention, the area of the battery packaging material 10 used for one battery is not particularly limited and is appropriately designed according to the application of the battery. For example, when comparing an in-vehicle battery with a mobile battery, the in-vehicle battery has a larger battery size than the mobile battery, and therefore the area of the battery packaging material 10 is also larger. Examples of the lower limit of the area include ¹⁰ cm2 or more, ³⁰ cm2 or more, ¹⁰⁰ cm2 or more, 500 ^cm2 or more, and ⁸⁰⁰ cm2 or more, and examples of the upper limit include ²⁰⁰⁰ cm2 or less, 1500 ^cm2 or less, and ¹²⁰⁰ cm2 or less. Examples of the area range include about 10 to 2000 cm ² , about 10 to 1500 cm ² , about 10 to 1200 cm ² , about 30 to 2000 cm ² , about 30 to 1500 cm ² , about 30 to 1200 cm ² , about 100 to 2000 cm ² , about 100 to 1500 cm ² , about 100 to 1200 cm ² , about 500 to 2000 cm ² , about 500 to 1500 cm ² , about 500 to 1200 cm ² , about 800 to 2000 cm ² , about 800 to 1500 cm ² , and about 800 to 1200 cm ² . In addition, a battery in which the battery packaging material 10 of the present invention is used has at least a positive electrode, a negative electrode, and an electrolyte contained in a package formed from the battery packaging material 10 of the present invention, and both sides of the battery can be formed from the battery packaging material 10 of the present invention.

Typical battery sizes (length x width) include, for example, 50 mm x 50 mm, 50 mm x 70 mm, 100 mm x 150 mm, 200 mm x 250 mm, 250 mm x 250 mm, etc.

The lower limit of the total area of pinholes in the metal foil layer 3 is not particularly limited as long as the manufacturing cost of the battery can be reduced, and may be, for example, ⁸⁰ μm2 or more, ¹⁰⁰ μm2 or more, or ¹⁰⁰⁰ μm2 or more. The upper limit of the total area of pinholes in the metal foil layer 3 is not particularly limited as long as moisture permeation into the battery can be effectively suppressed, and is preferably 5.0 × ¹⁰⁵ μm2 ^or less, more preferably 3.0 × ¹⁰⁵ μm2 ^or less, and even more preferably 1.0 × ¹⁰⁵ μm2 or ^less . From the viewpoint of suitably suppressing moisture permeation into the battery while preventing an increase in the manufacturing cost of the battery, preferred ranges for the total area of pinholes in the metal foil layer 3 are preferably about 80 to 5.0 x 10 ⁵ μm ² , about 80 to 3.0 x 10 ⁵ μm ² , about 80 to 1.0 x 10 ⁵ μm ² , about 100 to 5.0 x 10 ⁵ μm ² , about 100 to 3.0 x 10 ⁵ μm ² , about 100 to 1.0 x 10 ⁵ μm ² , about 1000 to 5.0 x 10 ⁵ μm ² , about 1000 to 3.0 x 10 ⁵ μm ² , and about 1000 to 1.0 x 10 ⁵ μm ² .

The number of pinholes is not particularly limited as long as the total area is 1.0×10 ⁶ μm ² or less, and may be one or more. This is because the moisture permeation into the battery depends on the total area of the pinholes, not on the number of pinholes. The number of pinholes may be, for example, 1 to 5.

In the present invention, the position and area of the pinholes in the metal foil layer 3 are measured using an optical pinhole inspection device, and can be measured using, for example, an optical pinhole inspection unit C12190 manufactured by Hamamatsu Photonics KK The total area of pinholes in a given range (i.e., the area of the battery packaging material 10 used for one battery) is a value obtained by inspecting pinholes in a given range using an optical pinhole inspection device and adding up the areas of the pinholes included in the given range.

The thickness of the metal foil layer 3 is not particularly limited as long as it functions as a barrier layer against water vapor, etc., but from the viewpoint of reducing the thickness of the battery packaging material 10, the upper limit is preferably about 100 μm or less, more preferably about 80 μm or less, and the lower limit is preferably about 10 μm or more. The thickness range is preferably about 10 to 100 μm or about 10 to 80 μm. This thickness is particularly suitable when the barrier layer is made of aluminum alloy foil. When the metal foil layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. The lower limit is about 10 μm or more, and the preferred thickness range is about 10 to 85 μm, about 10 to 50 μm, more preferably about 10 to 40 μm, more preferably about 10 to 30 μm, and even more preferably about 15 to 25 μm.

In addition, it is preferable that at least one surface, preferably both surfaces, of the metal foil layer 3 are chemically treated in order to stabilize adhesion and prevent dissolution and corrosion. Here, chemical conversion treatment refers to a treatment for forming an acid-resistant film on the surface of the metal foil layer 3. When an acid-resistant film is formed on the surface of the metal foil layer 3 of the present invention, the metal foil layer 3 includes an acid-resistant film. Examples of chemical conversion treatments include chromate treatment using chromium compounds such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetyl acetate, chromium chloride, and potassium chromium sulfate; phosphate treatment using phosphate compounds such as sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid; and chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4). In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.

In the general formulae (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. R ¹ and R ² may be the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In the general formulae (1) to (4), examples of the alkyl group represented by X, R ¹ , and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the hydroxyalkyl group represented by X, R ¹ , and R ² include linear or branched alkyl groups having 1 to 4 carbon atoms and substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. In the general formulae (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, ^R1 , and ^R2 may be the same or different. In the general formulae (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating units represented by the general formulae (1) to (4) is preferably, for example, about 500 to 1,000,000, and more preferably about 1,000 to 20,000.

In addition, as a chemical conversion treatment method for imparting corrosion resistance to the metal foil layer 3, a method is given in which fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate are dispersed in phosphoric acid, and then baking is performed at 150°C or higher to form an acid-resistant film on the surface of the metal foil layer 3. In addition, a resin layer in which a cationic polymer is crosslinked with a crosslinking agent may be further formed on the acid-resistant film. Here, examples of the cationic polymer include polyethyleneimine, an ionic polymer complex consisting of a polymer having polyethyleneimine and a carboxylic acid, a primary amine graft acrylic resin in which a primary amine is graft-polymerized to an acrylic main skeleton, polyallylamine or a derivative thereof, and aminophenol. These cationic polymers may be used alone or in combination of two or more types. Examples of the crosslinking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, a silane coupling agent, and the like. These crosslinking agents may be used alone or in combination of two or more types.

As a specific method for providing an acid-resistant coating, for example, at least the inner surface of the aluminum alloy foil is first degreased by a known method such as alkali immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation, and then the degreased surface is coated with a treatment liquid (aqueous solution) mainly composed of metal phosphates such as chromium phosphates, titanium phosphates, zirconium phosphates, and zinc phosphates, or mixtures of these metal salts, or a treatment liquid (aqueous solution) mainly composed of non-metallic phosphates and mixtures of these non-metallic salts, or a treatment liquid (aqueous solution) consisting of a mixture of these with a water-based synthetic resin such as an acrylic resin, a phenolic resin, or a urethane resin, by a known coating method such as roll coating, gravure printing, or immersion, to form an acid-resistant coating. For example, when treated with a chromium phosphate-based treatment solution, an acid-resistant film made of chromium phosphate, aluminum phosphate, aluminum oxide, aluminum hydroxide, aluminum fluoride, etc. is formed, and when treated with a zinc phosphate-based treatment solution, an acid-resistant film made of zinc phosphate hydrate, aluminum phosphate, aluminum oxide, aluminum hydroxide, aluminum fluoride, etc. is formed.

As another example of a specific method for providing an acid-resistant coating, for example, at least the inner surface of the aluminum alloy foil is first degreased using a known method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation, and then the degreased surface is subjected to a known anodizing treatment to form an acid-resistant coating.

Other examples of acid-resistant coatings include phosphate-based and chromate-based coatings. Phosphate-based coatings include zinc phosphate, iron phosphate, manganese phosphate, calcium phosphate, and chromium phosphate, while chromate-based coatings include chromium chromate.

As another example of an acid-resistant film, an acid-resistant film made of phosphate, chromate, fluoride, triazine thiol compound, etc. can be formed to prevent delamination between the aluminum and the base layer 1 during embossing, prevent dissolution and corrosion of the aluminum surface, particularly aluminum oxide present on the aluminum surface, caused by hydrogen fluoride produced by the reaction of electrolyte with water, and improve the adhesion (wettability) of the aluminum surface, preventing delamination between the base layer 1 and aluminum during heat sealing, and in the case of the embossed type, preventing delamination between the base layer 1 and aluminum during press molding. Among the substances that form acid-resistant films, an aqueous solution composed of three components, phenol resin, chromium (III) fluoride compound, and phosphoric acid, can be applied to the aluminum surface and dried and baked well.

The acid-resistant coating may include a layer having cerium oxide, phosphoric acid or a phosphate, an anionic polymer, and a crosslinking agent that crosslinks the anionic polymer, and the phosphoric acid or phosphate may be blended in an amount of about 1 to 100 parts by mass per 100 parts by mass of the cerium oxide. It is preferable that the acid-resistant coating has a multilayer structure further including a layer having a cationic polymer and a crosslinking agent that crosslinks the cationic polymer.

Furthermore, it is preferable that the anionic polymer is poly(meth)acrylic acid or a salt thereof, or a copolymer mainly composed of (meth)acrylic acid or a salt thereof. It is also preferable that the crosslinking agent is at least one selected from the group consisting of a compound having any one of the functional groups of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent.

It is also preferable that the phosphoric acid or phosphate is a condensed phosphoric acid or a condensed phosphate.

The chemical conversion treatment may be performed using only one type of chemical conversion treatment, or two or more types of chemical conversion treatments in combination. Furthermore, these chemical conversion treatments may be performed using one type of compound alone, or two or more types of compounds in combination. Among the chemical conversion treatments, chromate treatments and chemical conversion treatments combining chromium compounds, phosphate compounds, and aminated phenol polymers are preferred. Among the chromium compounds, chromate compounds are preferred.

Specific examples of acid-resistant coatings include those containing at least one of phosphates, chromates, fluorides, and triazine thiols. Acid-resistant coatings containing a cerium compound are also preferred. As a cerium compound, cerium oxide is preferred.

Specific examples of acid-resistant films include phosphate-based films, chromate-based films, fluoride-based films, and triazine thiol compound films. The acid-resistant film may be one of these films, or a combination of multiple films. Furthermore, the acid-resistant film may be formed by degreasing the chemically treated surface of the aluminum alloy foil, using a treatment liquid consisting of a mixture of a metal phosphate and a water-based synthetic resin, or a treatment liquid consisting of a mixture of a non-metal phosphate and a water-based synthetic resin.

The composition of the acid-resistant coating can be analyzed by, for example, time-of-flight secondary ion mass spectrometry. By analyzing the composition of the acid-resistant coating using time-of-flight secondary ion mass spectrometry, for example, a peak derived from at least one of Ce ⁺ and Cr ⁺ is detected.

It is preferable that the surface of the aluminum alloy foil is provided with an acid-resistant film containing at least one element selected from the group consisting of phosphorus, chromium, and cerium. The presence of at least one element selected from the group consisting of phosphorus, chromium, and cerium in the acid-resistant film on the surface of the aluminum alloy foil of the battery packaging material 10 can be confirmed using X-ray photoelectron spectroscopy. Specifically, first, the heat-sealable resin layer 4 and adhesive layer laminated on the aluminum alloy foil in the battery packaging material 10 are physically peeled off. Next, the aluminum alloy foil is placed in an electric furnace and organic components present on the surface of the aluminum alloy foil are removed at about 300°C for about 30 minutes. Then, the presence of these elements is confirmed using X-ray photoelectron spectroscopy of the surface of the aluminum alloy foil.

The amount of the acid-resistant coating formed on the surface of the metal foil layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of carrying out the above-mentioned chromate treatment, it is desirable that the metal foil layer ³ contains, per square meter of its surface, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of chromium compounds, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of phosphorus compounds, and about 1 to 200 mg, preferably about 5.0 to 150 mg, of aminated phenol polymers, calculated in terms of phosphorus.

The thickness of the acid-resistant coating is not particularly limited, but is preferably about 1 nm to 10 μm, more preferably about 1 to 100 nm, and even more preferably about 1 to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesion strength with the metal foil layer 3 and the heat-sealable resin layer. The thickness of the acid-resistant coating can be measured by observation with a transmission electron microscope, or a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy.

The chemical conversion treatment is carried out by applying a solution containing a compound used to form an acid-resistant film to the surface of the metal foil layer 3 by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then heating the metal foil layer 3 so that the temperature of the metal foil layer 3 is about 70 to 200°C. In addition, before the chemical conversion treatment is carried out on the metal foil layer 3, the metal foil layer 3 may be subjected to a degreasing treatment in advance by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By carrying out a degreasing treatment in this manner, the chemical conversion treatment of the surface of the metal foil layer 3 can be carried out more efficiently.

[Heat-fusible resin layer 4]
In the battery packaging material 10 of the present invention, the heat-sealable resin layer 4 corresponds to the innermost layer, and is a layer that seals the battery element by being heat-sealed to each other by the heat-sealable resin layers 4 during assembly of the battery.

The resin component used in the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, and examples thereof include polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin. That is, the resin constituting the heat-sealable resin layer 4 may or may not contain a polyolefin skeleton, and preferably contains a polyolefin skeleton. The resin constituting the heat-sealable resin layer 4 can be analyzed to determine whether it contains a polyolefin skeleton, for example, by infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wavenumbers of about 1760 cm ^-1 and about 1780 cm ^-1 . However, if the degree of acid modification is low, the peaks may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; 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); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred.

The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of the polyolefin with an acid component such as a carboxylic acid. Examples of the acid component used for modification include carboxylic acids or their anhydrides, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing them with an α,β-unsaturated carboxylic acid or its anhydride, or by block-polymerizing or graft-polymerizing an α,β-unsaturated carboxylic acid or its anhydride to a cyclic polyolefin. The cyclic polyolefin to be modified with a carboxylic acid is the same as described above. The carboxylic acid used for the modification is the same as the acid component used for the modification of the polyolefin.

Among these resin components, polyolefins such as polypropylene and carboxylic acid-modified polyolefins are preferred; polypropylene and acid-modified polypropylene are even more preferred.

The heat-sealable resin layer 4 may be formed from one type of resin component alone, or may be formed from a blend polymer of two or more types of resin components. 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 resin components.

In the present invention, from the viewpoint of improving the moldability of the battery packaging material 10, it is preferable that a lubricant is attached to the surface of the heat-sealable resin layer 4. The lubricant is not particularly limited, but is preferably an amide-based lubricant. Specific examples of amide-based lubricants include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides. Specific examples of saturated fatty acid amides include lauric acid amides, palmitic acid amides, stearic acid amides, behenic acid amides, and hydroxystearic acid amides. Specific examples of unsaturated fatty acid amides include oleic acid amides and erucic acid amides. Specific examples of substituted amides include N-oleyl palmitic acid amides, N-stearyl stearic acid amides, N-stearyl oleic acid amides, N-oleyl stearic acid amides, and N-stearyl erucic acid amides. Specific examples of methylol amides include methylol stearic acid amides. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamide ethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N,N'-distearylisophthalic acid amide. The lubricant may be used alone or in combination of two or more types.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount of the lubricant 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 in an environment of a temperature of 24°C and a relative humidity of 60%.

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

The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it functions as a heat-sealable resin layer, but is preferably about 60 μm or less, more preferably about 15 to 60 μm, and even more preferably about 15 to 40 μm.

[Adhesive layer 5]
In the battery packaging material 10 of the present invention, the adhesive layer 5 is a layer that is provided, if necessary, between the metal foil layer 3 and the heat-sealable resin layer 4 in order to firmly bond them together.

The adhesive layer 5 is formed by a resin capable of bonding the metal foil layer 3 and the heat-sealable resin layer 4. The adhesive mechanism, the type of adhesive component, and the like of the resin used to form the adhesive layer 5 can be the same as those of the adhesive layer 2. In addition, the resin used to form the adhesive layer 5 can also be a polyolefin-based resin such as polyolefin, cyclic polyolefin, carboxylic acid-modified polyolefin, and carboxylic acid-modified cyclic polyolefin exemplified in the heat-sealable resin layer 4. From the viewpoint of excellent adhesion between the metal foil layer 3 and the heat-sealable resin layer 4, carboxylic acid-modified polyolefin is preferable as the polyolefin, and carboxylic acid-modified polypropylene is particularly preferable. That is, the resin constituting the adhesive layer 5 may or may not contain a polyolefin skeleton, and it is preferable that it contains a polyolefin skeleton. The resin constituting the adhesive layer 5 can be analyzed to contain a polyolefin skeleton, for example, by infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, maleic anhydride-derived peaks are detected near wavenumber 1760 cm ^-1 and near wavenumber 1780 cm ^-1 . However, if the degree of acid denaturation is low, the peaks may be small and not detectable, in which case analysis can be performed using nuclear magnetic resonance spectroscopy.

Furthermore, from the viewpoint of making the battery packaging material 10 thin while providing a battery packaging material 10 with excellent shape stability after molding, the adhesive layer 5 may be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. As the acid-modified polyolefin, the same carboxylic acid-modified polyolefin and carboxylic acid-modified cyclic polyolefin as exemplified in the heat-sealable resin layer 4 can be preferably exemplified.

The curing agent is not particularly limited as long as it cures the acid-modified polyolefin. Examples of the curing agent include epoxy-based curing agents, polyfunctional isocyanate-based curing agents, carbodiimide-based curing agents, and oxazoline-based curing agents.

The epoxy-based curing agent is not particularly limited as long as it is a compound having at least one epoxy group. Examples of epoxy-based curing agents include epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

The polyfunctional isocyanate curing agent is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions of these, mixtures of these, and copolymers with other polymers.

The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (-N=C=N-). As the carbodiimide-based curing agent, a polycarbodiimide compound having at least two carbodiimide groups is preferable.

There are no particular limitations on the oxazoline-based curing agent, so long as it is a compound that has an oxazoline skeleton. Specific examples of oxazoline-based curing agents include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

From the viewpoint of increasing the adhesion between the metal foil layer 3 and the heat-sealable resin layer 4 by the adhesive layer 5, the curing agent may be composed of two or more types of compounds.

The content of the curing agent in the resin composition forming the adhesive layer 5 is preferably in the range of about 0.1 to 50% by mass, more preferably in the range of about 0.1 to 30% by mass, and even more preferably in the range of about 0.1 to 10% by mass.

The thickness of the adhesive layer 5 is not particularly limited as long as it functions as an adhesive layer, but if an adhesive exemplified in the adhesive layer 2 is used, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. If a resin exemplified in the heat-sealable resin layer 4 is used, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. If the adhesive layer 5 is a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 30 μm or less, more preferably about 0.1 to 20 μm, and even more preferably about 0.5 to 5 μm. If the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed by applying the resin composition and curing it by heating or the like.

[Surface coating layer]
In the battery packaging material 10 of the present invention, a surface coating layer may be provided on the substrate layer 1 (the side of the substrate layer 1 opposite the metal foil layer 3) as necessary for the purpose of improving design, electrolyte resistance, abrasion resistance, formability, etc. The surface coating layer is a layer located on the outermost layer when the battery is assembled.

The surface coating layer can be formed from, for example, polyvinylidene chloride, polyester resin, urethane resin, acrylic resin, epoxy resin, etc. Among these, it is preferable to form the surface coating layer from a two-component curing resin. Examples of the two-component curing resin that forms the surface coating layer include a two-component curing urethane resin, a two-component curing polyester resin, and a two-component curing epoxy resin. In addition, an additive may be blended into the surface coating layer.

Examples of additives include fine particles with a particle size of about 0.5 nm to 5 μm. The material of the additive is not particularly limited, but examples include metals, metal oxides, inorganic substances, and organic substances. The shape of the additive is also not particularly limited, but examples include spherical, fibrous, plate-like, amorphous, and balloon-like. Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, synthetic 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 nylon, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. These additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferable from the viewpoints of dispersion stability and cost. In addition, the additives may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment.

The content of the additive in the surface coating layer is not particularly limited, but is preferably about 0.05 to 1.0 mass%, and more preferably about 0.1 to 0.5 mass%.

The method for forming the surface coating layer is not particularly limited, but for example, a method of applying a two-component curing resin that forms the surface coating layer to one surface of the base layer 1 can be used. When an additive is added, the additive can be added to the two-component curing resin, mixed, and then applied.

The thickness of the surface coating layer is not particularly limited as long as it is set according to the function to be imparted as a surface coating layer, but may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. Manufacturing method of battery packaging material The manufacturing method of the battery packaging material 10 of the present invention is not particularly limited as long as a laminate in which each layer of a predetermined composition is laminated can be obtained. That is, the manufacturing method of the battery packaging material 10 of the present invention includes a step of laminating at least a base layer 1, a metal foil layer 3, and a heat-sealable resin layer 4 in this order, and includes a step of further laminating at least one gas barrier layer 6 on the base layer ¹ side of the heat-sealable resin layer 4, the gas barrier layer 6 including ^a thin film layer ⁶¹ of 5 μm or less composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic and inorganic composite materials.

An example of a method for manufacturing the battery packaging material 10 of the present invention is as follows. First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which a base layer 1, an adhesive layer 2, and a metal foil layer 3 are laminated in this order. At this time, when a gas barrier layer 6 is provided on the laminate A, at least one gas barrier layer 6 is laminated to form the laminate A. The laminate A can be formed by a dry lamination method in which an adhesive used to form the adhesive layer 2 is applied and dried to the base layer 1 or the metal foil layer 3, the surface of which has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then the metal foil layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured. As described above, for example, when the gas barrier layer 6 consisting of the thin film layer 61 is provided between the base layer 1 and the adhesive layer 2, a laminate film in which the thin film layer 61 is laminated on the base layer 1 is prepared, and the metal foil layer 3 is laminated on the thin film layer 61 by dry lamination to obtain a laminate A in which the base layer 1 / thin film layer 61 (gas barrier layer 6) / adhesive layer 2 / metal foil layer 3 are laminated in this order. In addition, when the gas barrier layer 6 is a resin film layer 62 on which the thin film layer 61 is laminated, a laminate of the resin film layer 62 and the thin film layer 61 is prepared in advance as the gas barrier layer 6, and the gas barrier layer 6 is laminated between the base layer 1 and the metal foil layer 3, for example.

As a method for laminating the gas barrier layer 6 on the surface of the base layer 1, for example, when the thin film layer 61 constitutes the gas barrier layer 6 and is a vapor deposition film of a metal, an inorganic oxide, or a carbon-containing inorganic oxide, the gas barrier layer 6 can be formed by forming a vapor deposition film on the surface of the base layer 1 using a vapor deposition method or the like. Also, as described above, when the thin film layer 61 is an organic-inorganic composite material, the thin film layer 61 can be formed on the surface of the base layer 1 by a sol-gel method. Furthermore, when the thin film layer 61 and the resin film layer 62 constitute the gas barrier layer 6, the thin film layer 61 can be formed on the surface of the resin film layer 62 by a vapor deposition method or a sol-gel method to prepare the gas barrier layer 6 in advance, and this can be laminated with the base layer 1, the metal foil layer 3, etc.

Next, the adhesive layer 5 and the heat-sealable resin layer 4 are laminated in this order on the metal foil layer 3 of the laminate A. If a gas barrier layer 6 is provided between the metal foil layer 3 and the heat-sealable resin layer 4, at least one gas barrier layer 6 is laminated. For example, there may be mentioned (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 on the metal foil layer 3 of the laminate A by co-extruding (co-extrusion lamination method); (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and laminating this on the metal foil layer 3 of the laminate A by a thermal lamination method; (3) a method of laminating an adhesive for forming the adhesive layer 5 on the metal foil layer 3 of the laminate A by an extrusion method or a solution coating, drying at a high temperature, and baking, and laminating the heat-sealable resin layer 4, which has been previously formed into a film, on this adhesive layer 5 by a thermal lamination method; and (4) a method of laminating the laminate A and the heat-sealable resin layer 4 via the adhesive layer 5 while pouring a molten adhesive layer 5 between the metal foil layer 3 of the laminate A and the heat-sealable resin layer 4, which has been previously formed into a sheet-like film (sandwich lamination method). As described above, a gas barrier layer 6 may be laminated between the metal foil layer 3 and the heat-sealable resin layer 4, between the metal foil layer 3 and the adhesive layer 5, and between the adhesive layer 5 and the heat-sealable resin layer 4 when these layers are laminated.

When a surface coating layer is provided, the surface coating layer is laminated on the surface of the base layer 1 opposite the metal foil layer 3. The surface coating layer can be formed, for example, by applying the above-mentioned resin that forms the surface coating layer to the surface of the base layer 1. The order of the step of laminating the metal foil layer 3 on the surface of the base layer 1 and the step of laminating the surface coating layer on the surface of the base layer 1 is not particularly limited. For example, after forming the surface coating layer on the surface of the base layer 1, the metal foil layer 3 may be formed on the surface of the base layer 1 opposite the surface coating layer. In addition, a gas barrier layer 6 may be formed between the surface coating layer and the base layer 1, or further outside the surface coating layer.

As described above, in a laminate consisting of a surface coating layer (optional), a base layer 1, an adhesive layer 2 (optional), a metal foil layer 3 whose surface is chemically treated (optional), an adhesive layer 5 (optional), and a heat-sealable resin layer 4, a battery packaging material 10 is formed in which a gas barrier layer 6 is provided at least in one location on the base layer 1 side of the heat-sealable resin layer 4. In order to strengthen the adhesiveness of the adhesive layer 2 or the adhesive layer 5, the battery packaging material 10 may be subjected to a heat treatment such as a hot roll contact type, a hot air type, a near infrared type, or a far infrared type.

In the battery packaging material 10 of the present invention, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, if necessary, in order to improve or stabilize the film-forming properties, lamination processing, and suitability for secondary processing of the final product (pouching, embossing), etc.

4. Configuration of the Rolled Body The rolled body of the present invention is configured by winding the above-described battery packaging material 10 into a roll.

That is, the wound body of the battery packaging material 10 of the present invention is a wound body of the battery packaging material 10 composed of a laminate having at least a base material layer 1, a metal foil layer 3, and a heat-sealable resin layer 4 in this order, and when a section having an area of ²⁵⁰⁰ mm2 is set, the metal foil layer 3 of the wound body has at least one section having a pinhole with a total area of 1.0 x ¹⁰⁶ μm2 or ^less , and the laminate further has at least one gas barrier layer 6 on the base material layer 1 side of the heat-sealable resin layer 4, and the gas barrier layer 6 includes a thin film layer 61 of 5 μm or less composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic and inorganic composite materials. The details of the configuration of the battery packaging material 10 are as described above.

The wound battery packaging material 10 of the present invention is characterized in that, when sections of 2500 mm2 are set in the metal foil layer ³ , there is at least one section in which a pinhole with a total area of 1.0 x ¹⁰⁶ μm2 or ^less is present. That is, in the wound battery packaging material 10 of the present invention, assuming that inspection sections of 2500 mm2 are set randomly (the positions of the sections are random) on the surface of the metal foil layer ³ and pinhole inspection is performed over the entire surface of the metal foil layer 3, at least one section will have a pinhole with the above total area. That is, in the wound battery packaging material 10 of the present invention, at least one section in which a pinhole with the above total area is present can be set. For example, the surface area (surface area on the substrate layer 1 side) of the battery packaging material 10 used for individual batteries such as mobile devices is often within 2500 ^mm2 , so when the battery packaging material 10 is unwound from a roll and cut to the size required for manufacturing individual batteries, the above-mentioned pinhole will be present in the battery packaging material 10 used to manufacture at least one battery. Even when the battery packaging material 10 having such a pinhole is used to manufacture a battery, the roll of the battery packaging material 10 of the present invention has the above-mentioned gas barrier layer 6, so that moisture permeation into the battery can be effectively suppressed. In addition, since it is not necessary to uniformly remove the periphery of the portion where the pinhole exists in the metal foil layer 3, an increase in the manufacturing cost of the battery can be effectively suppressed.

The roll of the battery packaging material 10 of the present invention may be wound so that the heat-sealing resin layer 4 of the battery packaging material 10 faces inward, or it may be wound so that the base material layer 1 faces inward.

In the wound body of the present invention, the length of the laminate constituting the battery packaging material 10 is not particularly limited, but may be, for example, 200 m or more, preferably about 200 to 4000 m. The width of the laminate may be, for example, about 0.01 to 1 m, preferably about 0.1 to 1 m. In the roll-shaped wound body, the diameter of the cross section in the direction perpendicular to the width direction of the laminate film is preferably 150 mm or more, more preferably 220 mm or more. The upper limit of the diameter of the circular cross section is usually about 1000 mm. However, the diameter of the circular cross section of the wound body is the diameter when the battery packaging material 10 is wound around a core tube formed of resin, paper, or the like, and the outer diameter of the core tube is usually about 70 to 180 mm.

The battery packaging material 10 of the present invention is used for a package for hermetically housing battery elements such as a positive electrode, a negative electrode, an electrolyte, etc. That is, a battery element including at least a positive electrode, a negative electrode, and an electrolyte can be housed in a package formed from the battery packaging material 10 of the present invention to form a battery.

Specifically, a battery element having at least a positive electrode, a negative electrode, and an electrolyte is covered with the battery packaging material 10 of the present invention in such a manner that a flange portion (a region where the heat-sealable resin layers 4 contact each other) can be formed around the periphery of the battery element, with the metal terminals connected to each of the positive electrode and negative electrode protruding outward, and the heat-sealable resin layers 4 of the flange portion are heat-sealed to provide a battery using the battery packaging material 10. When a battery element is housed in a package formed with the battery packaging material 10 of the present invention, the package is formed so that the heat-sealable resin portion of the battery packaging material 10 of the present invention faces inside (the surface in contact with the battery element).

The battery packaging material 10 of the present invention may be used for either primary or secondary batteries, but is preferably used for secondary batteries. There are no particular limitations on the type of secondary battery to which the battery packaging material 10 of the present invention is applied, and examples include lithium ion batteries, lithium ion polymer 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, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications of the battery packaging material 10 of the present invention.

6. Aluminum alloy foil The aluminum alloy foil of the present invention is an aluminum alloy foil for use in the metal foil layer 3 of the battery packaging material 10. The battery packaging material 10 is composed of a laminate including at least a base layer 1, a metal foil layer 3, and a heat-sealable resin layer 4 in this order. The laminate further includes at least one gas barrier layer 6 on the base layer 1 side of the heat-sealable resin layer 4. The gas barrier layer 6 includes a thin film layer 61 of 5 μm or less that is composed of at least one material selected from the group consisting of inorganic materials, organic materials, and organic-inorganic composite materials. The aluminum alloy foil of the present invention has pinholes with a total area of 1.0×10 ⁶ μm ² or less.

The aluminum alloy foil of the present invention is the same as the aluminum alloy foil exemplified as the metal foil layer 3 of the battery packaging material 10 of the present invention. The configuration of the battery packaging material 10 in which the aluminum alloy foil of the present invention is used is also the same as that of the battery packaging material 10 of the present invention.

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

(Examples 1 to 4 and Comparative Example 1)
<Production of Battery Packaging Material>
As a laminate of a substrate layer and a gas barrier layer (thin film layer), a gas barrier film ("VM-PET MWR2" manufactured by Saichi Kogyo Co., Ltd., thickness 12 μm, water vapor transmission rate 0.7 g / m ² · 24 h) in which an aluminum deposition layer (deposited Al, thickness 0.05 μm or less) was formed on a PET film was prepared. Next, a metal foil layer composed of an aluminum alloy foil (Al foil, each thickness listed in Table 1) was laminated on the deposited Al by a dry lamination method. Specifically, a two-liquid urethane adhesive (AD, polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on both sides of which an acid-resistant film was formed, and an adhesive layer (thickness 3 μm) was formed on the aluminum alloy foil. Next, the adhesive layer on the surface of the aluminum alloy foil and the deposited Al side of the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a substrate layer / gas barrier layer (deposited Al) / adhesive layer / aluminum alloy foil layer laminate.

Each of the aluminum alloy foil layers used in Examples 1-4 and Comparative Example 1 has one square pinhole (shape observed from a direction perpendicular to the surface of the aluminum alloy foil layer) having a side length as shown in Table 1. For example, in Example 1, the square pinhole has a side length of 266 μm and an area of ^70,756 μm2. The position and area of the pinhole in the metal foil layer 3 were measured using an optical pinhole inspection unit C12190 manufactured by Hamamatsu Photonics KK The "pinhole size (μmφ)" in Table 1 is the diameter of the pinhole detected as a circle by the inspection unit.

The acid-resistant coating on the aluminum alloy foil was formed by a chemical conversion treatment in which a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid was applied to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and the solution was then baked.

Next, maleic anhydride modified polypropylene (PPa, thickness 15 μm, metal foil layer side) and random polypropylene (PP, thickness 20 μm, innermost layer) were laminated on the surface of the aluminum alloy foil of the obtained laminate by co-extrusion lamination to obtain a battery packaging material having a base layer/gas barrier layer (vapor-deposited Al)/adhesive layer/aluminum alloy foil layer/adhesive layer/thermally adhesive resin layer laminated in this order.

Example 5
A two-liquid urethane adhesive (AD, polyol compound and aromatic isocyanate compound) was applied to the surface of the PET film side of the gas barrier film ("VM-PET MWR2" manufactured by Saichi Kogyo Co., Ltd., thickness 12 μm, water vapor transmission rate 0.7 g / m ² · 24 h) used in Examples 1-4 and Comparative Example 1, and a PET film (thickness 12 μm) was laminated. Next, a metal foil layer composed of an aluminum alloy foil (Al foil, 35 μm) was laminated on the evaporated Al by a dry lamination method. Specifically, a two-liquid urethane adhesive (AD, polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on both sides of which an acid-resistant film was formed, and an adhesive layer (thickness 3 μm) was formed on the aluminum alloy foil. Next, the adhesive layer on the surface of the aluminum alloy foil and the vapor-deposited Al side of the base material layer were laminated by a dry lamination method, and then an aging treatment was carried out to produce a laminate of the base material layer (a laminate of two PET films)/gas barrier layer (vapor-deposited Al)/adhesive layer/aluminum alloy foil layer.

Each aluminum alloy foil layer used in Example 5 has one square pinhole (shape observed from a direction perpendicular to the surface of the aluminum alloy foil layer) with a side length as shown in Table 1. The acid-resistant coating of the aluminum alloy foil is the same as that of Examples 1-4 and Comparative Example 1.

Next, maleic anhydride modified polypropylene (PPa, thickness 15 μm, metal foil layer side) and random polypropylene (PP, thickness 20 μm, innermost layer) were laminated on the surface of the aluminum alloy foil of the obtained laminate by co-extrusion lamination to obtain a battery packaging material laminated in the following order: base layer (laminate of two PET films)/gas barrier layer (vapor-deposited Al)/adhesive layer/aluminum alloy foil layer/adhesive layer/thermally adhesive resin layer.

(Comparative Examples 2-3 and Reference Examples 1-5)
<Production of Battery Packaging Material>
A metal foil layer made of aluminum alloy foil (Al foil, each having a thickness as shown in Table 1) was laminated by dry lamination on one side of the 12 μm-thick biaxially stretched polyethylene terephthalate film (PET) that was corona-treated on both sides and used as the substrate layer in Examples 1-4 and Comparative Example 1. Specifically, a two-liquid urethane adhesive (AD, a polyol compound and an aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which an acid-resistant coating was formed on both sides, and an adhesive layer (thickness 3 μm) was formed on the aluminum alloy foil. Next, the adhesive layer on the surface of the aluminum alloy foil and the substrate layer were laminated by dry lamination, and then aging treatment was performed to produce a substrate layer/adhesive layer/aluminum alloy foil layer laminate.

Each aluminum alloy foil layer used in Comparative Examples 2-3 and Reference Examples 1-5 had one square pinhole (shape observed from a direction perpendicular to the surface of the aluminum alloy foil layer) with a side length as shown in Table 1. The acid-resistant coating on the aluminum alloy foil was formed by the same chemical conversion treatment as in Examples 1-4 and Comparative Example 1.

Next, maleic anhydride modified polypropylene (PPa, thickness 15 μm, metal foil layer side) and random polypropylene (PP, thickness 20 μm, innermost layer) were laminated on the surface of the aluminum alloy foil of the obtained laminate by co-extrusion lamination to obtain a battery packaging material having a base layer/adhesive layer/aluminum alloy foil layer/adhesive layer/thermally adhesive resin layer laminated in this order.

<Measurement of water vapor transmission rate per ¹ m2>
The water vapor transmission rate (g/m ² /24h) per m ² (area of one side) of each battery packaging material obtained above was measured by the following method. A method conforming to the provisions of ISO15106-5 2008 was adopted, and the sample was placed so that a pinhole was present within the measurement area of the aluminum alloy foil under the measurement conditions of temperature 40°C, relative humidity 90%, measurement period 24 hours, and measurement area 8 cmφ, and was measured using a water vapor transmission rate measuring device (trade name DELTAPERM manufactured by Techno-I Co., Ltd.) using a differential pressure method. The water vapor transmission rate per m ² is a value converted to m ² by the ISO water vapor transmission rate measurement method. The results are shown in Table 1.

<Total water vapor transmission rate at pinhole locations>
The water vapor transmission rate per ^m2 of each battery packaging material obtained above was converted by the measurement area (8 cmφ) to calculate the total water vapor transmission rate of the pinhole location in one day (24 hours). As described above, the aluminum alloy foil of each battery packaging material is provided with a square pinhole with the length (μm) of one side of the pinhole shown in Table 1, assuming the pinhole size (μmφ) shown in Table 1. The total water vapor transmission rate of the pinhole location is the total water vapor transmission rate of the location where the pinhole exists (however, the area other than the pinhole location is set to zero). The results are shown in Table 1. In Examples 1-5, Comparative Examples 1-3, and Reference Examples 1-5, the number of pinholes was set to one in the experiments, but the same water vapor transmission rate is obtained even when the total area of multiple pinholes is the value shown in Table 1, so here it is expressed as the total water vapor transmission rate of the pinhole location.

The total water vapor transmission rate (mg/10 years) through the pinhole area was calculated from the total water vapor transmission rate (g/24 h) through the pinhole area in one day. The results are shown in Table 1.

Although the battery packaging material of Example 1-5 has a pinhole area significantly larger than that of Reference Example 1-5, it has the same or higher moisture permeation suppression performance. Therefore, the battery packaging material of Example 1-5 can be suitably used for all-solid-state lithium-ion batteries that require strict moisture control. On the other hand, the battery packaging material of Comparative Example 1-3 has a very large moisture permeation suppression performance and is not suitable for practical use.

(Examples 6 to 8)
<Production of Battery Packaging Material>
As a laminate of a substrate layer and a gas barrier layer (thin film layer), a gas barrier film (IB-PET-PXB manufactured by Dai Nippon Printing Co., Ltd., thickness 12 μm, water vapor transmission rate 0.05 g/ ^m2 ·24 h) in which a vapor-deposited silica layer was formed on a PET film was prepared. Next, a metal foil layer composed of an aluminum alloy foil (Al foil, thickness 35 μm) was laminated on the vapor-deposited silica layer by a dry lamination method. Specifically, a two-liquid urethane adhesive (AD, polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which an acid-resistant film was formed on both sides, and an adhesive layer (thickness 3 μm) was formed on the aluminum alloy foil. Next, the adhesive layer on the surface of the aluminum alloy foil and the vapor-deposited silica layer side of the substrate layer were laminated by a dry lamination method, and then aging treatment was performed to produce a substrate layer/gas barrier layer (vapor-deposited silica)/adhesive layer/aluminum alloy foil layer laminate.

Each of the aluminum alloy foil layers used in Examples 6 to 8 has one square pinhole (shape observed from a direction perpendicular to the surface of the aluminum alloy foil layer) with a side length as shown in Table 2. For example, in Example 6, the square pinhole has a side length of 89 μm and an area of ⁷⁹²¹ μm2. The position and area of the pinhole in the metal foil layer 3 were measured using an optical pinhole inspection unit C12190 manufactured by Hamamatsu Photonics KK The "pinhole size (μmφ)" in Table 2 is the diameter of the pinhole detected as a circle by the inspection unit.

The acid-resistant coating on the aluminum alloy foil was formed by a chemical conversion treatment in which a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid was applied to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and the solution was then baked.

Next, maleic anhydride modified polypropylene (PPa, thickness 15 μm, metal foil layer side) and random polypropylene (PP, thickness 20 μm, innermost layer) were laminated on the surface of the aluminum alloy foil of the obtained laminate by co-extrusion lamination to obtain a battery packaging material having a base layer/gas barrier layer (vapor-deposited silica)/adhesive layer/aluminum alloy foil layer/adhesive layer/thermally adhesive resin layer laminated in this order.

The battery packaging materials of Examples 6-8 also have high moisture permeation suppression performance, and can be used favorably in all-solid-state lithium-ion batteries, which require strict moisture control.

1... base material layer 2... adhesive layer 3... metal foil layer 4... heat-sealable resin layer 5... adhesive layer 6... gas barrier layer 61... thin film layer 62... resin film layer 10... battery packaging material

Claims (7)

A battery packaging material composed of a laminate having at least a base layer, an adhesive layer, a metal foil layer, and a heat-sealable resin layer in this order (however , this does not include a battery packaging material composed of a laminate film having at least a metal layer and a heat-sealable resin layer, in which pinholes are present in the metal layer, and in which, when a battery element is sealed with the battery packaging material, the area of the battery packaging material is A and the total area of pinholes present in the metal layer of the battery packaging material is B, the value of B/A is 3× ^10-6 or less),
the metal foil layer has pinholes with a total area of 1.0×10 ⁵ μm ² or less per area of the battery packaging material used for one battery;
The laminate further includes at least one gas barrier layer on the base layer side of the heat-fusible resin layer,
the gas barrier layer is provided between the base layer and the adhesive layer,
The gas barrier layer comprises a thin film layer having a thickness of 5 μm or less and made of at least one material selected from the group consisting of inorganic materials and organic-inorganic composite materials. The battery packaging material according to claim 1, wherein the gas barrier layer further comprises a resin film layer. The battery packaging material according to claim 1 or 2, wherein the thin film layer is made of aluminum or silica. A roll of a battery packaging material made of a laminate having at least a base layer, an adhesive layer, a metal foil layer, and a heat-sealable resin layer in this order (however , this does not include a battery packaging material made of a laminate film having at least a metal layer and a heat-sealable resin layer, in which pinholes are present in the metal layer, and in which, when a battery element is sealed with the battery packaging material, the area of the battery packaging material is A and the total area of pinholes present in the metal layer of the battery packaging material is B, the value of B/A is 3× ^10-6 or less),
When a section having an area of ²⁵⁰⁰ mm2 is defined in the metal foil layer of the roll, at least one section has pinholes with a total area of 1.0 x 105 ^μm2 or ^less ,
The laminate further includes at least one gas barrier layer on the base layer side of the heat-fusible resin layer,
the gas barrier layer is provided between the base layer and the adhesive layer,
The gas barrier layer comprises a thin film layer having a thickness of 5 μm or less and made of at least one material selected from the group consisting of inorganic materials and organic-inorganic composite materials. A battery, comprising at least a positive electrode, a negative electrode, and an electrolyte housed in a package formed from the battery packaging material according to any one of claims 1 to 3. A method for producing a battery packaging material, comprising a step of laminating at least a base layer, an adhesive layer, a metal foil layer, and a heat-sealable resin layer in this order to obtain a laminate (however , this does not include a battery packaging material made of a laminate film including at least a metal layer and a heat-sealable resin layer, in which pinholes are present in the metal layer, and in which, when a battery element is sealed with the battery packaging material, the area of the battery packaging material is A and the total area of pinholes present in the metal layer of the battery packaging material is B, the value of B/A is 3× ^10-6 or less),
the metal foil layer has pinholes with a total area of 1.0×10 ⁵ μm ² or less per area of the battery packaging material used in one battery;
further laminating at least one gas barrier layer on the base layer side of the thermally adhesive resin layer of the laminate,
the gas barrier layer is provided between the base layer and the adhesive layer,
The gas barrier layer includes a thin film layer having a thickness of 5 μm or less and composed of at least one material selected from the group consisting of inorganic materials and organic-inorganic composite materials. An aluminum alloy foil for use in a metal foil layer of a packaging material for a battery, comprising:
The battery packaging material is composed of a laminate having at least a base layer, an adhesive layer, a metal foil layer, and a heat-sealable resin layer in this order (however , this does not include a battery packaging material composed of a laminate film having at least a metal layer and a heat-sealable resin layer, in which pinholes exist in the metal layer, and in which, when a battery element is sealed with the battery packaging material, the area of the battery packaging material is A and the total area of pinholes existing in the metal layer of the battery packaging material is B, the value of B/A is 3×10 ⁻⁶ or less).
The laminate further includes at least one gas barrier layer on the base layer side of the thermally adhesive resin layer,
the gas barrier layer is provided between the base layer and the adhesive layer,
the gas barrier layer includes a thin film layer having a thickness of 5 μm or less and made of at least one material selected from the group consisting of inorganic materials and organic-inorganic composite materials;
The aluminum alloy foil for use as a battery packaging material has pinholes with a total area of 1.0 x 105 ^µm2 or ^less per area of the battery packaging material used for one battery.