WO2024210218A1 - Metal-terminal adhesive film and manufacturing method therefor, metal terminal equipped with metal-terminal adhesive film, power-storage-device external packaging material, kit comprising power-storage-device external packaging material and metal-terminal adhesive film, and power storage device and manufacturing method therefor - Google Patents

Abstract

Provided is a metal-terminal adhesive film interposed between a metal terminal that is electrically connected to an electrode of a power storage device element and a power-storage-device exterior material that seals the power storage device element, wherein the metal-terminal adhesive film comprises a thermochromic layer.

Description

Adhesive film for metal terminal and manufacturing method thereof, metal terminal with adhesive film for metal terminal, exterior material for power storage device, kit including exterior material for power storage device and adhesive film for metal terminal, and power storage device and manufacturing method thereof

The present disclosure relates to an adhesive film for metal terminals and a manufacturing method thereof, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for metal terminals, and an electricity storage device and a manufacturing method thereof.

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

In recent years, therefore, a laminate sheet in which a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer are laminated in that order has been proposed as an exterior material for an electricity storage device that can be easily processed into a variety of shapes and can be made thinner and lighter. When using such an exterior material for an electricity storage device in the form of a laminate film, the heat-sealable resin layers located in the innermost layers of the exterior material for an electricity storage device are placed opposite each other, and the peripheral portion of the exterior material for an electricity storage device is heat-sealed to seal the electricity storage device element.

Metal terminals protrude from the heat-sealed portion of the exterior material for electricity storage devices, and the electricity storage device element sealed with the exterior material for electricity storage devices is electrically connected to the outside via the metal terminals that are electrically connected to the electrodes of the electricity storage device element. In other words, the portion of the exterior material for electricity storage devices where the metal terminals are present is heat-sealed in a state where the metal terminals are sandwiched between the heat-sealable resin layer. Because the metal terminals and the heat-sealable resin layer are made of different materials, adhesion is likely to decrease at the interface between the metal terminals and the heat-sealable resin layer.

For this reason, an adhesive film may be placed between the metal terminal and the heat-sealable resin layer in order to improve adhesion between them. An example of such an adhesive film is that described in Patent Document 1.

JP 2015-79638 A

The adhesive film disposed between the metal terminal and the exterior material for the electricity storage device covers the periphery of the metal terminal by sandwiching the metal terminal on both sides with the adhesive film and heat sealing the exterior material. For example, during heat sealing, the adhesive film is heated to a high temperature. Also, during the manufacture of the adhesive film, the resin that forms the adhesive film is melted and formed into a film, so the resin that forms the adhesive film is heated to a high temperature. Furthermore, even after the adhesive film is applied to the electricity storage device, if the electricity storage device is exposed to a high-temperature environment or generates heat and becomes hot, the adhesive film will also be heated to a high temperature.

In this way, the adhesive film disposed between the metal terminal and the exterior material for the electricity storage device may be exposed to a high-temperature environment during the manufacture of the adhesive film, when the adhesive film is applied to the electricity storage device, and even after application.

If the resin that forms the adhesive film is exposed to high temperatures, the resin may deteriorate, causing the properties of the adhesive film to decrease (for example, reduced adhesion to metal terminals).

The inventors of this disclosure have set a new problem: determining from the appearance that the resin forming the adhesive film has been heated to a specified temperature. If such a problem is solved, it will have an excellent effect of making it possible to identify from the appearance, for example, an adhesive film whose characteristics may have deteriorated.

Under these circumstances, the main objective of the present disclosure is to provide an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, and that allows the appearance of the film to indicate that it has been heated to a predetermined temperature. Furthermore, the present disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and the adhesive film for metal terminals, an electricity storage device, and a method for manufacturing the electricity storage device.

The inventors of the present disclosure conducted intensive research to solve the above problems. As a result, they discovered that by providing a thermochromic layer in an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, it is possible to tell from the outside that the resin contained in the adhesive film for metal terminals has been heated to a predetermined temperature. The present disclosure was completed through further research based on this knowledge.

That is, the present disclosure provides the inventions of the following aspects.
An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element,
The adhesive film for a metal terminal includes a thermochromic layer.

According to the present disclosure, it is possible to provide an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, and that allows the appearance of the adhesive film to indicate that it has been heated to a predetermined temperature. Furthermore, the present disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for metal terminals, and an electricity storage device and a method for manufacturing the same.

FIG. 2 is a schematic plan view of the electricity storage device of the present disclosure. 2 is a schematic cross-sectional view taken along line A-A' in FIG. 1. 2 is a schematic cross-sectional view taken along line B-B' in FIG. 1. 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. 1 is a schematic cross-sectional view of an exterior material for an electricity storage device according to the present disclosure.

The adhesive film for metal terminals disclosed herein is an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, and is characterized in that the adhesive film for metal terminals has a thermochromic layer.

The electricity storage device of the present disclosure is an electricity storage device that includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, and is characterized in that the adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for an electricity storage device.

The adhesive film for metal terminals and its manufacturing method, and the electricity storage device and its manufacturing method disclosed herein are described in detail below.

In this specification, the numerical ranges indicated with "~" mean "greater than or equal to" or "less than or equal to." For example, the expression 2 to 15 mm means 2 mm or greater and 15 mm or less. In the numerical ranges described in this disclosure in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, a numerical range may be formed by combining an upper limit value and an upper limit value, an upper limit value and a lower limit value, or a lower limit value and a lower limit value, each of which is described separately. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

1. Adhesive film for metal terminal The adhesive film for metal terminal of the present disclosure is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element. Specifically, as shown in, for example, Figures 1 to 3, the adhesive film for metal terminal 1 of the present disclosure is interposed between a metal terminal 2 electrically connected to an electrode of an electricity storage device element 4 and an exterior material for an electricity storage device 3 that seals the electricity storage device element 4. In addition, the metal terminal 2 protrudes outside the exterior material for an electricity storage device 3, and is sandwiched by the exterior material for an electricity storage device 3 via the adhesive film for metal terminal 1 at the peripheral portion 3a of the heat-sealed exterior material for an electricity storage device 3.

In the present disclosure, the temporary adhesion process of the adhesive film for metal terminals to the metal terminals is carried out under conditions of, for example, a temperature of about 140-160°C, a pressure of about 0.01-1.0 MPa, a time of about 3-15 seconds, and about 3-6 cycles, while the main adhesion process is carried out under conditions of, for example, a temperature of about 160-240°C, a pressure of about 0.01-1.0 MPa, a time of about 3-15 seconds, and about 1-3 cycles. In addition, the heating temperature when the metal terminal with the adhesive film for metal terminal is interposed between the exterior material for the electricity storage device and heat sealed is usually in the range of about 180-210°C, and the pressure is usually about 1.0-2.0 MPa, a time of about 3-5 seconds, and about 1 cycle.

The adhesive film 1 for metal terminals of the present disclosure is provided to improve the adhesion between the metal terminal 2 and the exterior material 3 for the electric storage device. By improving the adhesion between the metal terminal 2 and the exterior material 3 for the electric storage device, the sealing property of the electric storage device element 4 is improved. As described above, when the electric storage device element 4 is heat-sealed, the electric storage device element is sealed so that the metal terminal 2 electrically connected to the electrode of the electric storage device element 4 protrudes outside the exterior material 3 for the electric storage device. At this time, since the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer made of a heat-sealable resin such as polyolefin) located in the innermost layer of the exterior material 3 for the electric storage device are made of different materials, if such an adhesive film is not used, the sealing property of the electric storage device element is likely to be reduced at the interface between the metal terminal 2 and the heat-sealable resin layer 35.

[Thermochromic layer]
The adhesive film 1 for metal terminals of the present disclosure includes at least a thermochromic layer. The thermochromic layer is, for example, a resin layer formed of a resin composition containing a temperature indicator and a resin. The temperature indicator means a material (compound) that has a property of changing color when placed in a certain temperature environment. As described later, various inorganic compounds and organic compounds are known as materials that have such a property.

The thermochromic layer may be a layer that forms at least one surface of the adhesive film for metal terminals 1 (i.e., the outermost layer, such as the first resin layer 12a or the second resin layer 12b described below), or it may be a layer that does not form the surface (such as the intermediate layer 11 or the adhesion promoter layer 13 described below).

As long as the effects of the present disclosure are achieved, the adhesive film 1 for metal terminals of the present disclosure may be a single layer as shown in FIG. 4, or may be multilayer as shown in FIGS. 5 to 7.

When the adhesive film 1 for metal terminals of the present disclosure is a single layer, the adhesive film 1 for metal terminals is composed of a thermochromic layer, and the surface on the metal terminal side and the surface of the exterior material for a storage device are formed by the thermochromic layer. In this case, the resin forming the surface on the exterior material for a storage device side of the adhesive film 1 for metal terminals and the resin forming the surface on the metal terminal side are a common resin (i.e., a resin that forms a thermochromic layer). Note that the resin forming the surface on the exterior material for a storage device side of the adhesive film 1 for metal terminals and the resin forming the surface on the metal terminal side being common means that, for example, 80% by mass or more of the components in these resins are the same, 90% by mass or more are the same, 95% by mass or more are the same, or 100% by mass are the same.

When the adhesive film 1 for metal terminals of the present disclosure is a multi-layer structure, for example as shown in FIG. 5, when the adhesive film 1 for metal terminals of the present disclosure has a two-layer structure, the adhesive film 1 for metal terminals is a laminate of a first resin layer 12a and a second resin layer 12b, and at least one of the first resin layer 12a and the second resin layer 12b is a thermochromic layer. Even when the adhesive film 1 for metal terminals of the present disclosure is a multi-layer structure, the resin forming the surface on the exterior material side for the electricity storage device and the resin forming the surface on the metal terminal side may be the same resin.

For example, as shown in FIG. 6, when the adhesive film 1 for metal terminals of the present disclosure has a three-layer structure, the adhesive film 1 for metal terminals is a laminate in which a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b are laminated in this order. In the present disclosure, the first resin layer 12a forms the surface on the metal terminal side, and the second resin layer 12b forms the surface on the exterior material side for the electricity storage device.

In the adhesive film 1 for metal terminals of the present disclosure, it is preferable that the thermochromic layer has thermal adhesion to metal (the metal constituting the metal terminal). In this case, the thermochromic layer can be disposed on the metal terminal side of the adhesive film 1 for metal terminals. For example, in the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the first resin layer 12a can be formed by the thermochromic layer.

The surface of the adhesive film 1 for metal terminals of the present disclosure that faces the exterior material for an electrical storage device (e.g., the second resin layer 12b) has thermal adhesion to the thermally adhesive resin layer described below. It is preferable that the thermochromic layer also has thermal adhesion to the thermally adhesive resin layer described below. The thermochromic layer can be disposed on the exterior material side for an electrical storage device of the adhesive film 1 for metal terminals and used. For example, in the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the second resin layer 12b can be formed by a thermochromic layer.

The thermochromic layer can also be used as an intermediate layer 11 located between the first resin layer 12a and the second resin layer 12b.

The thermochromic layer is a layer that contains a temperature-indicating material. That is, the thermochromic layer is, for example, a resin layer formed from a resin composition that contains a temperature-indicating material and a resin.

There are no particular limitations on the temperature-indicating material, so long as it is a material (compound) that has the property of changing color when placed in a certain temperature environment, and various inorganic and organic compounds are known as materials that have this property.

The temperature at which the temperature indicator changes color when heated from room temperature (25°C) is unique to each temperature indicator, so a temperature indicator can be selected according to the heating temperature to be determined from the appearance of the adhesive film 1 for metal terminals. Examples of the temperature range at which the temperature indicator used in this disclosure changes color when heated from room temperature (25°C) include between 120 and 150°C, between 200 and 240°C, and between 280 and 320°C. For example, if the adhesive film 1 for metal terminals contains polyolefin, it is preferable that the color change occurs between 280 and 320°C, at which point the polyolefin begins to deteriorate. In addition, when the adhesive film 1 for metal terminals is preheat-sealed to the metal terminal, and when the exterior material for the power storage device is heat-sealed via the adhesive film 1 for metal terminals, it is preferable that the color change occurs between 200 and 240°C from the viewpoint of confirming that the adhesive film 1 for metal terminals has been heat-sealed, and it is preferable that the color change occurs between 280 and 320°C from the viewpoint of determining that the temperature during heat sealing was too high. In addition, if the adhesive film 1 for metal terminals is used to determine whether the power storage device has experienced thermal runaway and is reaching a high temperature, it is preferable for the color to change between 120 and 150°C. As mentioned above, for example, titanium nitride changes from black to white when heated to about 300°C.

For example, titanium nitride (titanium black), which is preferably used as a temperature indicator in this disclosure, is black at room temperature (25°C) and remains black even when heated to, for example, 280°C, but when heated to 300°C, it is oxidized to titanium dioxide and changes color to white. Therefore, if titanium nitride (titanium black) is used as a temperature indicator for the thermochromic layer, the adhesive film 1 for metal terminals retains its black color from room temperature to 280°C, but changes color to white when heated to 300°C, so that it can be determined from the appearance that it has been exposed to a very high temperature environment of 300°C. When the adhesive film 1 for metal terminals is exposed to a high temperature environment of 300°C, the resin deteriorates and the properties of the adhesive film 1 for metal terminals tend to deteriorate, so that it is possible to determine from the appearance whether the properties of the adhesive film 1 for metal terminals are likely to deteriorate. In addition, the resin may be heated to 300°C in the manufacturing process of the adhesive film 1 for metal terminals. Even in such cases, by confirming that the thermochromic layer, which should have been manufactured as black, has changed to white, it is possible to judge from the appearance whether there is a risk of a deterioration in the properties of the adhesive film 1 for metal terminals.

Specific examples of the temperature indicator include inorganic compounds such as titanium nitride (titanium black), titanium dioxide, and zinc sulfide, and organic compounds such as thermochromic liquid crystals (cholesterol derivatives and cyanobiphenyls). For example, inorganic particles are unlikely to dissolve in the electrolyte. In addition, inorganic particles have a large coloring effect and can obtain a sufficient coloring effect with an amount added that does not inhibit adhesion, and can increase the apparent melt viscosity of the added resin without melting with heat. Furthermore, they can prevent the pressurized part from becoming thin during thermal adhesion (heat sealing), and can provide excellent sealing between the exterior material for the power storage device and the metal terminal. The thermochromic layer may contain only one type of temperature indicator, or two or more types. From the viewpoint of more suitably exerting the effects of the present disclosure, titanium nitride (titanium black) is particularly preferable among these temperature indicators.

The color of the temperature indicator is not particularly limited, but from the viewpoint of more optimally exerting the effects of the present disclosure, black, gray, etc. are preferred, and black is particularly preferred. The thermochromic layer can be colored in a color corresponding to the color of the temperature indicator, and the adhesive film 1 for metal terminals of the present disclosure allows the color of the thermochromic layer to be visually recognized from the outside.

The thermochromic layer has an L ^* value in the L ^* a ^* b ^* color space of reflected light measured under the measurement conditions of the SCI method, a visual field of 10°, and a light source F2, which is preferably about 90 or less, more preferably about 80 or less, and even more preferably about 70 or less, and is preferably about 10 or more, more preferably about 20 or more, and even more preferably about 30 or more. Preferred ranges include about 10 to 90, about 10 to 80, about 10 to 70, about 20 to 90, about 20 to 80, about 20 to 70, about 30 to 90, about 30 to 80, and about 30 to 70.

Furthermore, the greater the difference in L ^* before and after heating the adhesive film 1 for metal terminal, the easier it is to recognize the change in appearance due to the color of the adhesive film 1 for metal terminal before and after heating. For this reason, the difference in L ^* before and after heating the adhesive film 1 for metal terminal is preferably about 10 or more, more preferably about 20 or more, and even more preferably about 30 or more, with the upper limit usually being about 90 or less, and preferred ranges include about 10 to 90, about 20 to 90, and about 30 to 90.

In order to more effectively exert the effects of the present disclosure, the average particle diameter of the temperature indicator is preferably about 300 nm or less, more preferably about 200 nm or less, and even more preferably about 100 nm or less, and is preferably about 10 nm or more, more preferably about 20 nm or more, even more preferably about 30 nm or more, and even more preferably about 50 nm or more. Preferred ranges include about 10 to 300 nm, about 10 to 200 nm, about 10 to 100 nm, about 20 to 300 nm, about 20 to 200 nm, about 20 to 100 nm, about 30 to 300 nm, about 30 to 200 nm, about 30 to 100 nm, about 50 to 300 nm, about 50 to 200 nm, and about 50 to 100 nm. The average particle diameter of the temperature indicator is the median diameter measured by a laser diffraction/scattering type particle size distribution measuring device.

In order to more effectively exert the effects of the present disclosure, the content of the temperature indicator in the thermochromic layer is preferably about 50% by mass or less, more preferably about 40% by mass or less, even more preferably about 30% by mass or less, and even more preferably about 20% by mass or less, and is preferably about 0.01% by mass or more, more preferably about 0.1% by mass or more, and preferred ranges include about 0.01 to 50% by mass, about 0.01 to 40% by mass, about 0.01 to 30% by mass, about 0.01 to 20% by mass, about 0.1 to 50% by mass, about 0.1 to 40% by mass, about 0.1 to 30% by mass, and about 0.1 to 20% by mass.

Examples of resins contained in the thermochromic layer include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof, among which polyolefin resins are particularly preferred. Examples of polyolefin resins include polyolefins and acid-modified polyolefins.

From the viewpoint of more optimally exerting the effects of the present disclosure, the thermochromic layer preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. Of the polyolefin resins, the thermochromic layer preferably contains a polyolefin or an acid-modified polyolefin. Furthermore, the polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene.

The thermochromic layer may contain only one type of resin, or two or more types. From the viewpoint of film-forming properties, the resin of the thermochromic layer is preferably a blended polymer combining two or more types of resin components. In the case of a blended polymer, for example, a thermochromic layer containing acid-modified polypropylene is preferably made of acid-modified polypropylene as the main component (50% by mass or more of a component) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). Also, a thermochromic layer containing polypropylene is preferably made of polypropylene as the main component (50% by mass or more of a component) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of electrolyte resistance of the thermochromic layer, a thermochromic layer containing acid-modified polypropylene preferably contains acid-modified polypropylene alone as a resin, and a thermochromic layer containing polypropylene is preferably made of acid-modified polypropylene or polypropylene alone as a resin.

The thermochromic layer preferably contains an acid-modified polyolefin, since this provides excellent adhesion to the metal terminal. From the viewpoint of more suitably exerting the effects of the present disclosure, the thermochromic layer is preferably formed from an acid-modified polyolefin containing a temperature indicator. In other words, the thermochromic layer can be suitably formed from an acid-modified polyolefin film containing a temperature indicator.

The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably includes polyolefins graft-modified with an unsaturated carboxylic acid or anhydride thereof.

Specific examples of polyolefins to be acid-modified include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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, and polypropylene is particularly preferred.

The polyolefin to be acid-modified may also be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or its anhydride, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or its anhydride onto a cyclic polyolefin.

The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and 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 even more preferred. Styrene is also an example of a constituting monomer.

Examples of the carboxylic acid or its anhydride used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When the thermochromic layer is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of about 1760 cm ^- 1 and a wave number of about 1780 cm ^-1 . When the thermochromic layer is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected by infrared spectroscopy. However, if the degree of acid modification is low, the peak may be small and not detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

The thermochromic layer may contain, in addition to the temperature indicator and resin, known additives such as fillers, as necessary, to the extent that the effect of the present disclosure is not impaired.

For example, the thermochromic layer may contain a filler as necessary. When the thermochromic layer contains a filler, the filler functions as a spacer, making it possible to effectively suppress short circuits between the metal terminal 2 and the barrier layer 33 of the exterior material 3 for a storage battery device. The particle size of the filler is about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. The content of the filler is about 5 to 30 parts by mass, and more preferably about 10 to 20 parts by mass, per 100 parts by mass of the resin component that forms the thermochromic layer.

Both inorganic and organic fillers can be used. Examples of inorganic fillers include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, etc. Examples of organic fillers include fluororesin, phenolic resin, urea resin, epoxy resin, acrylic resin, benzoguanamine-formaldehyde condensate, melamine-formaldehyde condensate, polymethyl methacrylate crosslinked product, polyethylene crosslinked product, etc. From the viewpoints of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesin, acrylic resin, and benzoguanamine-formaldehyde condensate are preferred, and among these, spherical aluminum oxide and silica are more preferred. The filler can be mixed into the resin component that forms the thermochromic layer by melt-blending the two in advance using a Banbury mixer or similar to create a master batch and mixing it in a specified ratio, or by directly mixing it with the resin component.

When adding a filler to the thermochromic layer, a temperature indicator and a pigment may be added to the thermochromic layer, but from the viewpoint of not impairing the thermal fusion properties of the adhesive film for metal terminals 1, it is preferable to add the filler and pigment separately to different layers (for example, the first resin layer 12a, the second resin layer 12b, the intermediate layer 11, etc. described below).

From the viewpoint of more suitably achieving the effects of the present disclosure, the melting peak temperature of the thermochromic layer is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. From the same viewpoint, the melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. Preferred ranges of the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C. In this disclosure, the method for measuring the melting peak temperature is as follows.

<Measurement of Melting Peak Temperature>
The melting peak temperature of each measurement sample is measured in accordance with the provisions of JIS K7121:2012 (Method of measuring transition temperature of plastics (JIS K7121:1987 Supplement 1)). The measurement is performed using a differential scanning calorimeter (DSC, for example, a differential scanning calorimeter Q200 manufactured by TA Instruments). The measurement sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C/min, the first melting peak temperature P (°C) is measured, and then held at 210°C for 10 minutes. Next, the temperature is lowered from 210°C to -50°C at a heating rate of 10°C/min and held for 15 minutes. Furthermore, the temperature is raised from -50°C to 210°C at a heating rate of 10°C/min to measure the second melting peak temperature Q (°C). The flow rate of nitrogen gas is 50 ml/min. By the above procedure, the melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time are obtained. The melting peak temperature P (°C) measured the first time by the above procedure is adopted.

When the adhesive film 1 for metal terminals disclosed herein is composed of a single layer of a thermochromic layer, the total thickness of the adhesive film 1 for metal terminals described below corresponds to the thickness of the thermochromic layer.

When the adhesive film 1 for metal terminals of the present disclosure is composed of multiple layers, from the viewpoint of more suitably exerting the effects of the present disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges of the thickness of the thermochromic layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm. Note that when the adhesive film 1 for metal terminals of the present disclosure includes multiple thermochromic layers, it is preferable that the thickness of each thermochromic layer is the above-mentioned thickness.

In addition, when the adhesive film 1 for metal terminals of the present disclosure has a thermochromic layer as the first resin layer 12a, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges for the thickness of the thermochromic layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

Furthermore, when the adhesive film 1 for metal terminals of the present disclosure has a thermochromic layer as the second resin layer 12b, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. A preferred range for the thickness of the thermochromic layer is about 40 to 100 μm.

When the adhesive film 1 for metal terminals of the present disclosure has a thermochromic layer as the intermediate layer 11, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the thermochromic layer is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges for the thickness of the thermochromic layer include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

As described above, the adhesive film 1 for metal terminals of the present disclosure can be configured, for example as shown in FIG. 6, to have at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b laminated in this order. In the adhesive film 1 for metal terminals of the present disclosure, in this configuration, the first resin layer 12a is disposed on the metal terminal 2 side, and the second resin layer 12b is disposed on the exterior material 3 side for an electrical storage device. In this configuration, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

The second resin layer 12b is a layer made of resin. The second resin layer 12b may be formed of a thermochromic layer, or may be formed of a resin layer B different from the thermochromic layer (i.e., the resin layer B is a resin layer that does not contain a thermochromic material).

The intermediate layer 11 may also be formed from a thermochromic layer, or may be formed from a resin layer B that is different from the thermochromic layer.

[Resin layer B]
Resin layer B is a resin layer different from the thermochromic layer (i.e., resin layer B can be said to be a non-thermochromic layer that does not thermochromic at the temperature at which the thermochromic layer thermochromic changes, for example, a resin layer that does not contain a temperature indicating material).

Examples of the resin constituting the resin layer B include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof, among which polyolefin resins are particularly preferred. Examples of polyolefin resins include polyolefins and acid-modified polyolefins.

The resin contained in the resin layer B may be only one type, or may be two or more types. From the viewpoint of film-forming properties, the resin of the resin layer B is preferably a blended polymer combining two or more types of resin components. In the case of a blended polymer, for example, if the resin layer B contains acid-modified polypropylene, it is preferable that the acid-modified polypropylene is the main component (a component of 50 mass% or more) and 50 mass% or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). Also, if the resin layer B contains polypropylene, it is preferable that the polypropylene is the main component (a component of 50 mass% or more) and 50 mass% or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the resin layer B, the resin layer B containing acid-modified polypropylene preferably contains acid-modified polypropylene alone as a resin, and the resin layer B containing polypropylene preferably contains acid-modified polypropylene or polypropylene alone as a resin.

The melting peak temperature of resin layer B is preferably 110° C. or higher, more preferably about 120° C. or higher, and even more preferably about 130° C. or higher. The melting peak temperature is, for example, 200° C. or lower, preferably 190° C. or lower, more preferably 180° C. or lower, even more preferably about 175° C. or lower, and even more preferably about 170° C. or lower. Preferred ranges for the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C.

In addition, when the adhesive film 1 for metal terminals of the present disclosure has a resin layer B as the first resin layer 12a, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

When the adhesive film 1 for metal terminals of the present disclosure has a resin layer B as the second resin layer 12b, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

When the adhesive film 1 for metal terminals of the present disclosure has a resin layer B as the intermediate layer 11, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 20 μm or more, more preferably about 30 μm or more, even more preferably about 40 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably 100 μm or less. Preferred ranges for the thickness of the resin layer B include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

　Like the thermochromic layer, the resin layer B may contain known additives (pigments, fillers, etc.). For example, the resin layer B may contain a pigment. As the pigment, various inorganic pigments can be used. As a specific example of the pigment, carbon (carbon, graphite) exemplified as the filler above can be preferably exemplified. Carbon (carbon, graphite) is a material generally used inside the electric storage device, and there is no risk of dissolving in the electrolyte. In addition, it has a large coloring effect, and a sufficient coloring effect can be obtained with an amount added that does not inhibit adhesion, and it does not melt with heat, and the apparent melt viscosity of the added resin can be increased. Furthermore, it is possible to prevent the pressurized part from becoming thin during heat adhesion (heat sealing), and to provide excellent sealing between the exterior material for the electric storage device and the metal terminal. In addition, for example, the resin layer B may contain a filler. The type and amount of the filler are the same as those of the thermochromic layer.

The resin layer B may be colored or colorless and transparent.

From the viewpoint of more suitably achieving the effects of the present disclosure, the total thickness of the adhesive film 1 for metal terminals is, for example, about 50 μm or more, preferably about 100 μm or more, and more preferably about 150 μm or more. The total thickness of the adhesive film 1 for metal terminals of the present disclosure is preferably about 400 μm or less, more preferably about 350 μm or less, and even more preferably about 300 μm or less. Preferred ranges for the total thickness of the adhesive film 1 for metal terminals of the present disclosure include about 50 to 400 μm, about 50 to 350 μm, about 50 to 300 μm, about 100 to 400 μm, about 100 to 350 μm, about 100 to 300 μm, about 150 to 400 μm, about 150 to 350 μm, and about 150 to 300 μm.

The adhesive film 1 for metal terminals of the present disclosure preferably has fine irregularities on at least one surface of the outermost layer. This can further improve adhesion to the heat-sealable resin layer 35 of the exterior material 3 for an electrical storage device or the metal terminal 2. Methods for forming fine irregularities on the surface of the outermost layer of the adhesive film 1 for metal terminals include a method of adding additives such as fine particles to the outermost layer, and a method of applying a cooling roll having an irregular surface to the outermost layer to form a shape. As for the fine irregularities, the ten-point average roughness of the surface of the outermost layer is preferably about 0.1 μm or more, more preferably about 0.2 μm or more, and is also preferably about 35 μm or less, more preferably about 10 μm or less, with preferred ranges being about 0.1 to 35 μm, about 0.1 to 10 μm, about 0.2 to 35 μm, and about 0.2 to 10 μm. The ten-point average roughness was measured using a Keyence VK-9710 laser microscope in accordance with the method specified in JIS B0601:1994, with an objective lens of 50x and no cutoff.

The adhesive film 1 for metal terminals of the present disclosure is preferably formed from a polyolefin resin. For example, the resin components contained in the adhesive film 1 for metal terminals of the present disclosure are preferably only acid-modified polyolefins, or only acid-modified polyolefins and polyolefins. The preferred acid-modified polyolefins and polyolefins are as described in the thermochromic layer and resin layer B.

The adhesive film 1 for metal terminals of the present disclosure is preferably composed of a laminate having a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b in this order. Below, a preferred embodiment of the adhesive film 1 for metal terminals of the present disclosure will be described in detail, taking as an example a case where the adhesive film 1 for metal terminals of the present disclosure is composed of a laminate having at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b in this order.

When the adhesive film 1 for metal terminals of the present disclosure is placed between the metal terminal 2 of the electricity storage device 10 and the exterior material 3 for the electricity storage device, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) of the exterior material 3 for the electricity storage device are bonded via the adhesive film 1 for metal terminals. The first resin layer 12a of the adhesive film 1 for metal terminals is placed on the metal terminal 2 side, and the second resin layer 12b is placed on the exterior material 3 for the electricity storage device, with the first resin layer 12a in close contact with the metal terminal 2 and the second resin layer 12b in close contact with the heat-sealable resin layer 35 of the exterior material 3 for the electricity storage device.

[First resin layer 12a and second resin layer 12b]
As shown in Fig. 6, the adhesive film 1 for metal terminal according to a preferred embodiment of the present disclosure comprises a first resin layer 12a on one side of an intermediate layer 11, and a second resin layer 12b on the other side. The first resin layer 12a is disposed on the metal terminal 2 side. The second resin layer 12b is disposed on the exterior material 3 for an electrical storage device. In the adhesive film 1 for metal terminal according to the present disclosure, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

In the present disclosure, at least one of the first resin layer 12a, the intermediate layer 11, and the second resin layer 12b is formed from the aforementioned thermochromic layer.

As described above, the first resin layer 12a and the second resin layer 12b each preferably contain a polyolefin-based resin (i.e., have a polyolefin skeleton), preferably contain a polyolefin, and more preferably are layers formed of a polyolefin. The first resin layer 12a preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, more preferably contains an acid-modified polyolefin, and more preferably is a layer formed of an acid-modified polyolefin film. The polyolefin-based resin is preferably a polypropylene-based resin. The second resin layer 12b preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, more preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin film. The polyolefin-based resin is preferably a polypropylene-based resin. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably polypropylene.

The melting peak temperature of the first resin layer 12a is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. The melting peak temperature is, for example, 200°C or lower, preferably 190°C or lower, more preferably 180°C or lower, even more preferably about 175°C or lower, and even more preferably about 170°C or lower. Preferred ranges for the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C.

The melting peak temperature of the second resin layer 12b is preferably 110° C. or higher, more preferably about 120° C. or higher, and even more preferably about 130° C. or higher. The melting peak temperature is, for example, 200° C. or lower, preferably 190° C. or lower, more preferably 180° C. or lower, even more preferably about 175° C. or lower, and even more preferably about 170° C. or lower. Preferred ranges for the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 175°C, about 110 to 170°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 175°C, about 120 to 170°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 175°C, and about 130 to 170°C.

From the viewpoint of more optimally achieving the effects of the present disclosure, the thickness of the first resin layer 12a is preferably at least about 20 μm, more preferably at least about 30 μm, even more preferably at least about 40 μm, and is preferably no more than about 200 μm, more preferably no more than about 150 μm, even more preferably no more than 100 μm. A preferred range for the thickness of the first resin layer 12a is about 40 to 100 μm.

In order to more effectively achieve the effects of the present disclosure, the thickness of the second resin layer 12b is preferably at least about 20 μm, more preferably at least about 30 μm, and even more preferably at least about 40 μm, and is preferably no more than about 200 μm, more preferably no more than about 150 μm, and even more preferably no more than 100 μm. Preferred ranges for the thickness of the second resin layer 12b include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

[Intermediate layer 11]
In the adhesive film 1 for a metal terminal, the intermediate layer 11 is a layer that functions as a support for the adhesive film 1 for a metal terminal.

The intermediate layer 11 may be formed from the thermochromic layer described above, or may be formed from the resin layer B described above.

The material forming the intermediate layer 11 is not particularly limited. Examples of materials forming the intermediate layer 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof. Among these, polyolefin resins are particularly preferred. In other words, the material forming the intermediate layer 11 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. Whether the resin constituting the intermediate layer 11 contains a polyolefin skeleton can be analyzed, for example, by infrared spectroscopy, gas chromatography mass spectrometry, or the like.

As described above, the intermediate layer 11 preferably contains a polyolefin resin, more preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin. The layer formed of a polyolefin may be a stretched polyolefin film or an unstretched polyolefin film, but is preferably an unstretched polyolefin film. Specific examples of polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block 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, and polypropylene is more preferred. In addition, because of its excellent electrolyte resistance, the intermediate layer 11 preferably contains homopolypropylene, more preferably is formed of homopolypropylene, and even more preferably is an unstretched homopolypropylene film.

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

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

The intermediate layer 11 may also be formed of a nonwoven fabric made of the above-mentioned resin. When the intermediate layer 11 is a nonwoven fabric, it is preferable that the intermediate layer 11 is composed of the above-mentioned polyolefin resin, polyamide resin, etc.

The melting peak temperature of the intermediate layer 11 is preferably 110°C or higher, more preferably about 120°C or higher, and even more preferably about 130°C or higher. From a similar perspective, the melting peak temperature is, for example, 300°C or lower, preferably 290°C or lower, more preferably 280°C or lower, even more preferably about 275°C or lower, and even more preferably about 270°C or lower. Preferred ranges for the melting peak temperature include about 110 to 300°C, about 110 to 290°C, about 110 to 280°C, about 110 to 275°C, about 110 to 270°C, about 120 to 300°C, about 120 to 290°C, about 120 to 280°C, about 120 to 275°C, about 120 to 270°C, about 130 to 300°C, about 130 to 290°C, about 130 to 280°C, about 130 to 275°C, and about 130 to 270°C.

The intermediate layer 11 may be a single layer or multiple layers.

Furthermore, by blending a colorant into the intermediate layer 11, the intermediate layer 11 can be a layer containing the colorant. Also, light transmittance can be adjusted by selecting a resin with low transparency. If the intermediate layer 11 is a film, a colored film or a film with low transparency can be used. If the intermediate layer 11 is a nonwoven fabric, a nonwoven fabric using fibers or a binder containing a colorant, or a nonwoven fabric with low transparency can be used.

When the intermediate layer 11 is made of a resin film, the surface of the intermediate layer 11 may be subjected to a known adhesion enhancing method such as corona discharge treatment, ozone treatment, or plasma treatment, if necessary.

In order to more effectively achieve the effects of the present disclosure, the thickness of the intermediate layer 11 is preferably at least about 20 μm, more preferably at least about 30 μm, and even more preferably at least about 40 μm, and is preferably no more than about 200 μm, more preferably no more than about 150 μm, and even more preferably no more than 100 μm. Preferred ranges for the thickness of the intermediate layer 11 include about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 30 to 200 μm, about 30 to 150 μm, about 30 to 100 μm, about 40 to 200 μm, about 40 to 150 μm, and about 40 to 100 μm.

From the same viewpoint, the ratio of the thickness of the intermediate layer 11 to the total thickness of the first resin layer 12a and the second resin layer 12b is preferably at least about 0.3, more preferably at least about 0.4, and is preferably at most about 1.0, more preferably at most about 0.8, with preferred ranges being around 0.3 to 1.0, around 0.3 to 0.8, around 0.4 to 1.0, and around 0.4 to 0.8.

In addition, if the total thickness of the adhesive film 1 for metal terminals is taken as 100%, the ratio of the total thickness of the first resin layer 12a and the second resin layer 12b is preferably about 30 to 80%, and more preferably about 50 to 70%.

The adhesive film 1 for metal terminals of the present disclosure can be manufactured, for example, by laminating a first resin layer 12a and a second resin layer 12b on both surfaces of an intermediate layer 11. The intermediate layer 11 can be laminated with the first resin layer 12a and the second resin layer 12b by a known method such as an extrusion lamination method, a T-die method, an inflation method, or a thermal lamination method.

The method for interposing the adhesive film 1 for metal terminals between the metal terminal 2 and the exterior material 3 for the electricity storage device is not particularly limited, and for example, as shown in Figures 1 to 3, the adhesive film 1 for metal terminals may be wrapped around the metal terminal 2 in the portion where the metal terminal 2 is sandwiched by the exterior material 3 for the electricity storage device. In addition, although not shown, the adhesive film 1 for metal terminals may be disposed on both sides of the metal terminal 2 so as to cross the two metal terminals 2 in the portion where the metal terminal 2 is sandwiched by the exterior material 3 for the electricity storage device.

The adhesion promoter layer 13 is a layer that is provided as necessary for the purpose of firmly adhering the intermediate layer 11 to the first resin layer 12a, and between the intermediate layer 11 and the second resin layer 12b (see FIG. 7). The adhesion promoter layer 13 may be provided on only one side between the intermediate layer 11 and the first resin layer 12a and between the intermediate layer 11 and the second resin layer 12b, or on both sides. The adhesion promoter layer may contain a temperature indicator.

The adhesion promoter layer 13 can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, polybutadiene-based, etc. From the viewpoint of obtaining strong adhesion strength, it is preferable that it is formed using an isocyanate-based adhesion promoter. As an isocyanate-based adhesion promoter, one consisting of an isocyanate component selected from triisocyanate monomer and polymeric MDI has excellent laminate strength and suffers little deterioration in laminate strength at high temperatures. It is particularly preferable to form the adhesive using an adhesion promoter made of triphenylmethane-4,4',4"-triisocyanate, which is a triisocyanate monomer, or polymethylene polyphenyl polyisocyanate, which is a polymeric MDI (NCO content of about 30%, viscosity of 200 to 700 mPa·s). It is also preferable to form the adhesive using triisocyanate monomer tris(p-isocyanatephenyl)thiophosphate, or a two-component curing adhesion promoter that uses a polyethyleneimine system as the main agent and polycarbodiimide as the crosslinking agent.

The adhesion promoter layer 13 can be formed by coating and drying using a known coating method such as bar coating, roll coating, gravure coating, etc. The amount of the adhesion promoter to be applied is about 20 to 100 mg/m ² , preferably about 40 to 60 mg/m ² , in the case of an adhesion promoter made of triisocyanate, about 40 to 150 mg/m ² , preferably about 60 to 100 mg/m ² , in the case of an adhesion promoter made of polymeric MDI, and about 5 to 50 mg/m ² , preferably about 10 to 30 mg/m ² , in the case of a two-liquid curing type adhesion promoter with a polyethyleneimine system as the main agent and a polycarbodiimide as the crosslinking agent. The triisocyanate monomer is a monomer having three isocyanate groups in one molecule, and the polymeric MDI is a mixture of MDI and MDI oligomers polymerized from MDI, and is represented by the following formula.

In order to more effectively achieve the effects of the present invention, it is preferable that the first resin layer 12a and the intermediate layer 11 are in contact with each other, and that the second resin layer 12b and the intermediate layer 11 are in contact with each other.

Specific examples of preferred laminated structures of the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first resin layer formed from acid-modified polypropylene/an intermediate layer (substrate) formed from polypropylene/a second resin layer formed from acid-modified polypropylene are laminated in this order; a three-layer structure in which a first resin layer formed from acid-modified polypropylene/an intermediate layer (substrate) formed from polypropylene/a second resin layer formed from polypropylene are laminated in this order, and among these, the latter three-layer structure is particularly preferred in terms of adhesion between the heat-sealable resin layer 35 and the second resin layer 12b of the exterior material 3 for electrical storage devices.

[Metal terminal 2]
The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between a metal terminal 2 and an exterior material 3 for an electricity storage device. The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive electrode or negative electrode) of an electricity storage device element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, copper, and the like. For example, the metal terminal 2 connected to the positive electrode of a lithium ion electricity storage device is usually made of aluminum, etc. In addition, the metal terminal 2 connected to the negative electrode of a lithium ion electricity storage device is usually made of copper, nickel, etc.

The surface of the metal terminal 2 is preferably subjected to a chemical conversion treatment in order to enhance resistance to electrolyte. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming a corrosion-resistant film using phosphates, chromates, fluorides, triazine thiol compounds, etc. Among the methods for forming a corrosion-resistant film, a phosphate chromate treatment using a compound consisting of three components: phenolic resin, chromium (III) fluoride compound, and phosphoric acid is preferable.

The size of the metal terminal 2 may be set appropriately depending on the size of the electricity storage device to be used. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[Exterior material 3 for electricity storage device]
The exterior material 3 for an electric storage device may have a laminated structure including at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order. FIG. 8 shows an example of a cross-sectional structure of the exterior material 3 for an electric storage device, in which the base material layer 31, an adhesive layer 32 provided as needed, a barrier layer 33, an adhesive layer 34 provided as needed, and a heat-sealable resin layer 35 are laminated in this order. In the exterior material 3 for an electric storage device, the base material layer 31 is the outer layer, and the heat-sealable resin layer 35 is the innermost layer. When assembling the electric storage device, the heat-sealable resin layers 35 located on the periphery of the electric storage device element 4 are brought into contact with each other and heat-sealed to seal the electric storage device element 4. Note that FIGS. 1 to 3 show the electric storage device 10 in the case where an embossed type exterior material 3 for an electric storage device formed by embossing or the like is used, but the exterior material 3 for an electric storage device may be an unformed pouch type. The pouch type includes three-sided seal, four-sided seal, pillow type, etc., and any type may be used.

The thickness of the laminate constituting the exterior material 3 for the electric storage device is not particularly limited, but from the viewpoint of cost reduction, energy density improvement, etc., the upper limit is, for example, about 190 μm or less, preferably about 180 μm or less, about 160 μm or less, about 155 μm or less, about 140 μm or less, about 130 μm or less, and about 120 μm or less, and from the viewpoint of maintaining the function of the exterior material 3 for the electric storage device to protect the electric storage device element 4, the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, and about 80 μm or more, and preferred ranges are, for example, about 35 to 190 μm, about 35 to 180 μm, and about 35 to 160 μm. degree, about 35-155 μm, about 35-140 μm, about 35-130 μm, about 35-120 μm, about 45-190 μm, about 45-180 μm, about 45-160 μm, about 45-155 μm, about 45-140 μm, about 45-130 μm, about 45-120 μm, about 60-190 μm, 60~180μ These include about 60 to 160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm, about 60 to 120 μm, about 80 to 190 μm, about 80 to 180 μm, about 80 to 160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm, and about 80 to 120 μm.

(Base material layer 31)
In the electrical storage device packaging material 3, the base material layer 31 is a layer that functions as a base material of the electrical storage device packaging material, and is a layer that forms the outermost layer side.

The material forming the base layer 31 is not particularly limited, as long as it is insulating. Examples of materials forming the base layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures and copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as materials for forming the base layer 31. In addition, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the base layer 31 during molding, and is therefore preferably used as materials for forming the base layer 31.

The substrate layer 31 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, uniaxially or biaxially stretched resin films, especially biaxially stretched resin films, are preferably used as the substrate layer 31 because their heat resistance is improved by oriented crystallization.

Among these, the resin film forming the base layer 31 is preferably nylon or polyester, and more preferably biaxially oriented nylon or biaxially oriented polyester.

The base layer 31 can be made by laminating resin films of different materials in order to improve pinhole resistance and insulation when used as a package for an electricity storage device. Specific examples include a multi-layer structure in which a polyester film is laminated with a nylon film, or a multi-layer structure in which biaxially oriented polyester is laminated with a biaxially oriented nylon. When the base layer 31 has a multi-layer structure, the resin films may be bonded via an adhesive, or may be laminated directly without an adhesive. When bonding without an adhesive, examples include a method of bonding in a hot melt state, such as co-extrusion, sand lamination, or thermal lamination.

The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, there are no particular limitations on the coefficient of friction of its surface, but an example of this is 1.0 or less. Examples of ways to make the base layer 31 low-friction include matte treatment, forming a thin layer of a slip agent, and combinations of these.

The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

(Adhesive layer 32)
In the exterior material 3 for an electricity storage device, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as necessary in order to impart adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

The adhesive layer 32 is formed from an adhesive capable of bonding the base layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. There are also no particular limitations on the adhesion mechanism of the adhesive used to form the adhesive layer 32, and it may be any of a chemical reaction type, a solvent volatilization type, a thermal melting type, a thermal pressure type, etc.

The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and effectively suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33 and preventing the occurrence of delamination.

The adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin with excellent adhesion to the base layer 31 as the adhesive component arranged on the base layer 31 side, and an adhesive component with excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, the adhesive component arranged on the barrier layer 33 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, a resin containing a copolymerized polyester, etc.

The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

(Barrier layer 33)
In the electrical storage device exterior material 3, the barrier layer 33 is a layer that has a function of preventing water vapor, oxygen, light, and the like from penetrating into the electrical storage device in addition to improving the strength of the electrical storage device exterior material. The barrier layer 33 is preferably a metal layer, that is, a layer formed of a metal. Specific examples of the metal constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and preferably aluminum. The barrier layer 33 can be formed, for example, of a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with these vapor deposition films, and is preferably formed of a metal foil, and more preferably formed of an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the production of the exterior material for an electricity storage device, the barrier layer is more preferably formed from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

The thickness of the barrier layer 33 is preferably about 10 to 200 μm, and more preferably about 20 to 100 μm, from the viewpoint of making the exterior material for the power storage device thinner while making it difficult for pinholes to occur during molding.

In addition, it is preferable that at least one surface, and preferably both surfaces, of the barrier layer 33 are chemically treated to stabilize adhesion and prevent dissolution and corrosion. Here, chemical treatment refers to a process for forming a corrosion-resistant film on the surface of the barrier layer.

(Adhesive layer 34)
In the exterior packaging material 3 for an electricity storage device, the adhesive layer 34 is a layer that is provided, if necessary, between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35 .

The adhesive layer 34 is formed from an adhesive capable of bonding the barrier layer 33 and the heat-sealable resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include a resin composition containing an acid-modified polyolefin. Examples of acid-modified polyolefins include the same ones exemplified for the first resin layer 12a and the second resin layer 12b.

The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

(Thermofusible resin layer 35)
In the exterior packaging material 3 for an electricity storage device, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the electricity storage device elements by heat-sealing the heat-sealable resin layers together when assembling the electricity storage device. .

The resin components used in the heat-sealable resin layer 35 are not particularly limited, as long as they are heat-sealable, but examples include polyolefins and cyclic polyolefins.

Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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, and 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. Styrene is also an example of a constituting monomer.

Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blended polymers thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and blended polymers of two or more of these.

The heat-sealable resin layer 35 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 35 may be formed from only one layer, or may be formed from two or more layers of the same or different resin components. It is particularly preferable that the second resin layer 12b and the heat-sealable resin layer 35 are made of the same resin, as this improves the adhesion between these layers.

The thickness of the heat-sealable resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm. The thickness of the heat-sealable resin layer 35 may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 34 described below is 10 μm or more, the thickness of the heat-sealable resin layer 35 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 34 described above is less than 10 μm or when the adhesive layer 34 is not provided, the thickness of the heat-sealable resin layer 35 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

The exterior material for an electricity storage device of the present disclosure can also be in the form of a kit including the exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for metal terminals of the present disclosure. In this case as well, the electricity storage device to which it is applied includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device. The kit of the present disclosure is used such that, when in use, the adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for an electricity storage device.

2. Electricity Storage Device The electricity storage device 10 of the present disclosure comprises at least an electricity storage device element 4 having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device 3 that seals the electricity storage device element 4, and a metal terminal 2 that is electrically connected to each of the positive electrode and the negative electrode and protrudes to the outside of the exterior material for an electricity storage device 3. The electricity storage device 10 of the present disclosure is characterized in that the adhesive film for a metal terminal 1 of the present disclosure is interposed between the metal terminal 2 and the exterior material for an electricity storage device 3. That is, the electricity storage device 10 of the present disclosure can be manufactured by a method including a step of interposing the adhesive film for a metal terminal 1 of the present disclosure between the metal terminal 2 and the exterior material for an electricity storage device 3.

Specifically, an electric storage device element 4 having at least a positive electrode, a negative electrode, and an electrolyte is covered with an exterior material 3 for an electric storage device by interposing an adhesive film 1 for metal terminals of the present disclosure between the metal terminals 2 and a heat-sealable resin layer 35 in a state in which the metal terminals 2 connected to the positive and negative electrodes are protruding outward, and the electric storage device element 4 is covered so that a flange portion (a region where the heat-sealable resin layers 35 contact each other, the peripheral portion 3a of the exterior material 3 for an electric storage device) of the exterior material 3 for an electric storage device is formed, and the heat-sealable resin layers 35 of the flange portion are heat-sealed to seal them, thereby providing an electric storage device 10 using the exterior material 3 for an electric storage device. When the exterior material 3 for an electric storage device is used to house the electric storage device element 4, the exterior material 3 for an electric storage device is used so that the heat-sealable resin layer 35 of the exterior material 3 for an electric storage device is on the inside (the surface in contact with the electric storage device element 4).

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

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

<Production of adhesive film for metal terminals>
Example 1
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the polypropylene as an intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) containing 0.1 mass% titanium nitride (average particle diameter 70 nm) as a temperature indicator as the first resin layer (thermochromic layer) on the metal terminal side (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) was obtained. The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and the second resin layer were colorless and transparent.

Example 2
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the intermediate layer as the second resin layer on the exterior material side (PPa layer, melting peak temperature 124 ° C.), and on the other side as the first resin layer (thermochromic layer) on the metal terminal side as the first resin layer (thermochromic layer) on the metal terminal side. Maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) containing 1.0 mass% titanium nitride (average particle diameter 70 nm) as a temperature indicator was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) was obtained. The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and the second resin layer were colorless and transparent.

Example 3
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the polypropylene as an intermediate layer (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as the second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124 ° C.) containing 1.0 mass% titanium nitride (average particle diameter 20 nm) as a temperature indicator as the first resin layer (thermochromic layer) on the metal terminal side (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) was obtained. The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and the second resin layer were colorless and transparent.

Example 4
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the intermediate layer as the second resin layer on the exterior material side (PPa layer, melting peak temperature 124 ° C.), and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) containing 1.0 mass% titanium nitride (average particle diameter 50 nm) as a temperature indicator was extruded on the other side as the first resin layer (thermochromic layer) on the metal terminal side, each with a thickness of 50 μm, to obtain an adhesive film (total thickness 150 μm) in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) were laminated in order. The adhesive film thus obtained had a black appearance due to the inclusion of black titanium nitride in the first resin layer (thermochromic layer), while the intermediate layer and the second resin layer were colorless and transparent.

Example 5
Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a polypropylene layer containing 10.0 mass% titanium nitride (average particle size 70 nm) as a temperature indicator was formed on the other side of the first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) was obtained in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in order. The obtained adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

Example 6
Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a polypropylene resin layer containing 0.01 mass% titanium nitride (average particle size 70 nm) as a temperature indicator was formed on the other side of the first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) was obtained in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in order. The obtained adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

Example 7
Using an extruder and a T-die casting machine, a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) was formed on one side of the outer casing material side of a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) as a second resin layer on the exterior material side, and a polypropylene layer containing 50.0 mass% titanium nitride (average particle size 70 nm) as a temperature indicator was formed on the other side of the outer casing material side of a first resin layer (thermochromic layer) on the metal terminal side. Water-maleic acid modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 50 μm, and an adhesive film (total thickness 150 μm) was obtained in which the first resin layer (thermochromic layer containing titanium nitride, PPa layer, melting peak temperature 140°C, thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124°C, thickness 50 μm) were laminated in order. The obtained adhesive film had a black appearance because the first resin layer (thermochromic layer) contained black titanium nitride. The intermediate layer and the second resin layer were colorless and transparent.

Comparative Example 1
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the polypropylene as an intermediate layer as the second resin layer on the exterior material side (PPa layer, melting peak temperature 124 ° C.), and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) containing 0.5% by mass of carbon black (average particle diameter 300 nm) was extruded on the other side as the first resin layer on the metal terminal side to a thickness of 50 μm, respectively, to obtain an adhesive film (total thickness 150 μm) in which the first resin layer (layer containing carbon black, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) were laminated in this order. The adhesive film obtained had a black appearance because the first resin layer contained black carbon black, while the intermediate layer and the second resin layer were colorless and transparent.

Comparative Example 2
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50μm) was extruded on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50μm) as a second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was extruded on the other side of a first resin layer on the metal terminal side, each with a thickness of 50μm, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (PPa layer, melting peak temperature 140°C, thickness 50μm)/intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50μm)/second resin layer (PPa layer, melting peak temperature 124°C, thickness 50μm) were laminated in this order. The obtained adhesive film was colorless and transparent.

Comparative Example 3
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50μm) was extruded on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50μm) as a second resin layer on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 124°C) was extruded on the other side of a first resin layer on the metal terminal side, each with a thickness of 50μm, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (PPa layer, melting peak temperature 140°C, thickness 50μm)/intermediate layer (substrate) (PP layer, melting peak temperature 163°C, thickness 50μm)/second resin layer (PPa layer, melting peak temperature 124°C, thickness 50μm) were laminated in this order. The obtained adhesive film was colorless and transparent.

Comparative Example 4
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) was extruded on one side of the polypropylene as an intermediate layer as the second resin layer on the exterior material side (PPa layer, melting peak temperature 124 ° C.), and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) containing 1.0 mass% carbon black (average particle diameter 300 nm) as the first resin layer on the metal terminal side on the other side, each with a thickness of 50 μm, to obtain an adhesive film (total thickness 150 μm) in which the first resin layer (layer containing carbon black, PPa layer, melting peak temperature 140 ° C., thickness 50 μm) / intermediate layer (substrate) (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (PPa layer, melting peak temperature 124 ° C., thickness 50 μm) were laminated in this order. The adhesive film obtained had a black appearance because the first resin layer contained black carbon black, while the intermediate layer and the second resin layer were colorless and transparent.

<Measurement of Melting Peak Temperature>
The adhesive film is measured for the melting peak temperature in accordance with the provisions of JIS K7121:2012 (Method for measuring transition temperature of plastics (JIS K7121:1987 Supplement 1)). The measurement was performed using a differential scanning calorimeter (DSC, differential scanning calorimeter Q200 manufactured by TA Instruments). The measurement sample was held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C/min, the first melting peak temperature P (°C) was measured, and then held at 210°C for 10 minutes. Next, the temperature was lowered from 210°C to -50°C at a heating rate of 10°C/min and held for 15 minutes. Furthermore, the temperature was raised from -50°C to 210°C at a heating rate of 10°C/min to measure the second melting peak temperature Q (°C). The flow rate of nitrogen gas was 50 ml/min. The melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time were determined by the above procedure. The melting peak temperature P (°C) measured the first time was used.

<Measurement of L ^* value before and after heating of adhesive film>
As the metal terminal, aluminum (JIS H4160:1994 A8079H-O) with a length of 50 mm, a width of 45 mm, and a thickness of 0.4 mm was prepared. In addition, the adhesive film for metal terminal of the example and the comparative example was cut to a length of 45 mm and a width of 10 mm, and two sheets were prepared. Next, the adhesive film for metal terminal was sandwiched between the two adhesive films to obtain a laminate of adhesive film/metal terminal/adhesive film. At this time, the vertical direction and horizontal direction of the metal terminal were aligned with the width direction and length direction of the adhesive film for metal terminal, respectively, and the metal terminal and the adhesive film for metal terminal were aligned with each other. The obtained laminate was placed on a hot plate. Next, the adhesive film was heated under each heating condition (heating temperature of 280°C and 300°C, heating pressure of 0.25 MPa, heating time of 16 seconds). Next, the L ^* value in the L ^* a ^* b ^* color space was measured for the first resin layer side surface of the adhesive film before and after heating under the following conditions. The observation conditions of a Konica Minolta spectrophotometer (CM-700d) calibrated with a white calibration cap (CM-A177: manufactured by Konica Minolta) were set to 10°, the observation light source was set to F2, and SCI mode (JIS Z8722-2009). Next, the L ^* value of the first resin layer side surface was measured at normal temperature and humidity. The measurement diameter was set to 8 mmφ. The results are shown in Table 1. In Table 1, the L ^* value was rounded off to the nearest tenth of a decimal point.

<Evaluation of adhesion to metal terminals>
In the above-mentioned <Measurement of L ^* value before and after heating of adhesive film>, adhesive films of the examples and comparative examples were prepared by heating and pressing under the same conditions as the adhesive films heated at 280 ° C. and 300 ° C., respectively, and the adhesion of these adhesive films to metal terminals was evaluated by the following method. The results are shown in Table 1. In addition, in expressing the size of the rectangular strip adhesive film, the description of length and width specifies the length in the MD direction and the width in the TD direction. As the metal terminal, aluminum (JIS H4160: 1994 A8079H-O) with a length of 50 mm, a width of 22.5 mm, and a thickness of 0.4 mm was prepared. In addition, the adhesive film for metal terminal was cut to a length of 45 mm and a width of 10 mm. Next, the adhesive film for metal terminal was placed on the metal terminal to obtain a laminate of metal terminal/adhesive film. At this time, the metal terminal was laminated so that the longitudinal direction and the lateral direction of the metal terminal adhesive film were aligned with the longitudinal direction and the width direction of the metal terminal adhesive film, respectively, and the centers of the metal terminal and the metal terminal adhesive film were aligned. In addition, the first resin layer of the metal terminal adhesive film was disposed on the metal terminal side. Next, a tetrafluoroethylene-ethylene copolymer film (ETFE film, thickness 100 μm) was placed on the metal terminal adhesive film of the laminate (the surface of the metal terminal adhesive film was covered with the ETFE film), and the laminate was placed on a press machine heated to 200 ° C. (the metal terminal was on the hot plate side), and a silicone sponge sheet was placed on the laminate, and the laminate was left at a pressure of 0.25 MPa for 16 seconds to heat-seal the adhesive film to the metal terminal. The laminate after heat-sealing was naturally cooled to 25 ° C. Next, in an environment of 25 ° C., the adhesive film for metal terminal was peeled off from the metal terminal using a Tensilon universal material testing machine (RTG-1210 manufactured by A & D Co., Ltd.). The maximum strength at the time of peeling was taken as the adhesion strength (N/15 mm) to the metal terminal. The adhesion strength was a converted value from the measurement result at a width of 10 mm to the measurement value at a width of 15 mm. The peel speed was 50 mm/min, the peel angle was 180°, and the chuck distance was 30 mm, and the average value was taken from three measurements. The process of leaving the sample for 16 seconds in a heating and pressurizing environment at a temperature of 200°C and a surface pressure of 0.25 MPa was a process that assumed the heat and pressure applied in the temporary adhesion process and the main adhesion process.
(Evaluation criteria for adhesion at 280°C and 300°C)
A: Adhesion strength is 40N/15mm or more. B: Adhesion strength is less than 40N/15mm.

The adhesive films for metal terminals of Examples 1 to 7 each have a thermochromic layer containing titanium nitride as a temperature indicator, and the L ^* value changes significantly between 280°C and 320°C. It was possible to tell from the appearance that the film had been heated to a specified temperature.

As described above, the present disclosure provides the inventions of the following aspects.
Item 1. An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element,
The adhesive film for a metal terminal includes a thermochromic layer.
Item 2. The adhesive film for a metal terminal according to item 1, wherein the thermochromic layer is formed of a resin composition containing a temperature indicating material and a resin.
Item 3. The adhesive film for a metal terminal according to item 2, wherein the temperature indicator contains an inorganic compound.
Item 4. The adhesive film for a metal terminal according to item 2 or 3, wherein the temperature indicator has an average particle size of 10 nm or more and 100 nm or less.
Item 5. The adhesive film for metal terminal according to any one of Items 2 to 4, wherein the content of the temperature indicator in the thermochromic layer is 0.01% by mass or more and 50% by mass or less.
Item 6. The adhesive film for a metal terminal according to any one of Items 2 to 5, wherein the temperature indicator is titanium nitride.
Item 7. The adhesive film for a metal terminal according to any one of Items 1 to 6, wherein the thermochromic layer has a polyolefin skeleton.
Item 8. The adhesive film for a metal terminal according to any one of Items 1 to 7, wherein when the thermochromic layer is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is detected.
Item 9. The adhesive film for metal terminal according to any one of items 1 to 8, wherein the thermochromic layer has an L ^* value in the L ^* a ^* b ^* color space of reflected light measured under the measurement conditions of SCI method, visual field 10°, and light source F2, of 80 or less.
Item 10. The adhesive film for a metal terminal is composed of a laminate including, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the exterior material for an electrical storage device;
Item 10. The adhesive film for metal terminal according to any one of items 1 to 9, wherein at least one of the first resin layer, the intermediate layer, and the second resin layer is the thermochromic layer.
Item 11. The adhesive film for a metal terminal according to any one of Items 1 to 10, wherein the adhesive film for a metal terminal is formed of a polyolefin resin.
Item 12. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising:
The method for producing an adhesive film for a metal terminal, wherein the adhesive film for a metal terminal has a thermochromic layer.
Item 13. A metal terminal with an adhesive film for a metal terminal, comprising the adhesive film for a metal terminal according to any one of items 1 to 11 attached to a metal terminal.
Item 14. An electricity storage device including at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device,
Item 12. An electricity storage device, comprising the adhesive film for a metal terminal according to any one of items 1 to 11 interposed between the metal terminal and the exterior material for the electricity storage device.
Item 15. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device,
Item 12. A method for manufacturing an electricity storage device, comprising: interposing the adhesive film for metal terminal according to any one of items 1 to 11 between the metal terminal and the exterior material for an electricity storage device; and sealing the electricity storage device element with the exterior material for an electricity storage device.
Item 16. An exterior material for an electricity storage device for use in an electricity storage device,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, and an adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device,
The adhesive film for metal terminal is the adhesive film for metal terminal according to any one of items 1 to 11,
The electrical storage device packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer.
Item 17. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal according to any one of items 1 to 11,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and the metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device,
The kit is used such that, when in use, the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device.

REFERENCE SIGNS LIST 1 adhesive film for metal terminal 2 metal terminal 3 exterior material for electricity storage device 3a peripheral portion of exterior material for electricity storage device 4 electricity storage device element 10 electricity storage device 11 intermediate layer 12a first resin layer 12b second resin layer 31 substrate layer 32 adhesive layer 33 barrier layer 34 adhesive layer 35 heat-sealable resin layer

Claims (17)

An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element,
The adhesive film for a metal terminal includes a thermochromic layer. The adhesive film for metal terminals according to claim 1, wherein the thermochromic layer is formed from a resin composition containing a temperature indicator and a resin. The adhesive film for metal terminals according to claim 2, wherein the temperature indicator includes an inorganic compound. The adhesive film for metal terminals according to claim 2 or 3, wherein the temperature indicator has an average particle size of 10 nm or more and 100 nm or less. The adhesive film for metal terminals according to claim 2 or 3, wherein the content of the temperature indicator in the thermochromic layer is 0.01% by mass or more and 50% by mass or less. The adhesive film for metal terminals according to claim 2 or 3, wherein the temperature indicator is titanium nitride. The adhesive film for metal terminals according to claim 1 or 2, wherein the thermochromic layer has a polyolefin skeleton. The adhesive film for metal terminals according to claim 1 or 2, wherein when the thermochromic layer is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is detected. 3. An adhesive film for metal terminals as described in claim 1 or 2, wherein the thermochromic layer has an L ^* value in the L ^* a ^* b ^* color space of reflected light measured under measurement conditions of SCI method, field of view 10° and light source F2 of 80 or less. The adhesive film for a metal terminal is composed of a laminate including, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the exterior material for an electricity storage device,
The adhesive film for metal terminal according to claim 1 or 2, wherein at least one of the first resin layer, the intermediate layer and the second resin layer is the thermochromic layer. The adhesive film for metal terminals according to claim 1 or 2, wherein the adhesive film for metal terminals is formed from a polyolefin resin. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising:
The method for producing an adhesive film for a metal terminal, wherein the adhesive film for a metal terminal has a thermochromic layer. A metal terminal with an adhesive film for metal terminal, comprising the adhesive film for metal terminal according to claim 1 or 2 attached to the metal terminal. An electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to an outside of the exterior material for an electricity storage device,
3. An electricity storage device, comprising the adhesive film for a metal terminal according to claim 1 or 2 interposed between the metal terminal and the exterior material for an electricity storage device. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to an outside of the exterior material for an electricity storage device,
A method for manufacturing an electricity storage device, comprising a step of interposing the adhesive film for metal terminals according to claim 1 or 2 between the metal terminal and the exterior material for an electricity storage device, and sealing the electricity storage device element with the exterior material for an electricity storage device. An exterior material for an electricity storage device for use in an electricity storage device,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, and an adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device,
The adhesive film for a metal terminal is the adhesive film for a metal terminal according to claim 1 or 2,
The electrical storage device packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal according to claim 1 or 2,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and the metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device,
The kit is used such that, when in use, the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device.