WO2025018353A1 - Metal terminal adhesive film and method for producing same, metal terminal provided with metal terminal adhesive film, power storage device covering material, kit comprising power storage device covering material and metal terminal adhesive film, and power storage device and method for producing same - Google Patents

Abstract

Provided is a metal terminal adhesive film which is interposed between a metal terminal electrically connected to an electrode of a power storage device element and a power storage device covering material that encapsulates the power storage device element. The adhesive film exhibits high adhesive strength when the adhesive film and a thermally-bondable resin layer of the power storage device covering material are thermally bonded together.

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 with the exterior material for an electricity storage device.

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 heat-sealed 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

As mentioned above, the heat-sealable resin layer and the metal terminal of the exterior material for an electricity storage device are made of different materials, so adhesion is likely to decrease at the interface between the metal terminal and the heat-sealable resin layer. For this reason, an adhesive film is sometimes placed between the metal terminal and the heat-sealable resin layer for the purpose of improving adhesion between them.

Even when an adhesive film is used, if the adhesive strength when the adhesive film is heat-sealed to the heat-sealable resin layer of the exterior material for the energy storage device can be increased, it is possible to further improve the sealing performance of the energy storage device.

The main object 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 seals the electricity storage device element, and that can exhibit high adhesive strength when the adhesive film is heat-sealed to the heat-sealable resin layer of the exterior material for an electricity storage device. 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 have conducted intensive research to solve the above problems. As a result, in an adhesive film for metal terminal 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 exterior material for an electricity storage device has a heat-sealable resin layer arranged on the outermost surface on the electricity storage device element side, one surface of the adhesive film for metal terminal is composed of resin layer A, and the adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to form a metal terminal arranged so that the resin layer A is located on the surface. It was found that when a metal terminal with an adhesive film for terminals is obtained, and the adhesive film for metal terminals of the metal terminal with the adhesive film for metal terminals is heat-sealed under specified conditions with a heat-sealable resin layer having a specified crystalline lamellar thickness, if the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminals and the crystalline lamellar thickness B of the heat-sealable resin layer at the heat-sealed portion between the adhesive film for metal terminals and the heat-sealable resin layer is a specified value or less, high adhesive strength can be exhibited when the adhesive film and the heat-sealable resin layer of the exterior material for an electricity storage device are heat-sealed.

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 electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
The adhesive film for metal terminal has one surface composed of a resin layer A,
The adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminal, in which the resin layer A is positioned on the surface; and when the adhesive film for metal terminal of the metal terminal with the adhesive film for metal terminal and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminal and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminal and the heat-sealable resin 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 can exhibit high adhesive strength when the adhesive film and the heat-sealable resin layer of the exterior material for an electricity storage device are heat-sealed. Furthermore, it is an object of the present disclosure 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. FIG. 2 is a schematic diagram for explaining a method for measuring the adhesive strength between an adhesive film and an exterior material. FIG. 2 is a schematic diagram for explaining a method for measuring the adhesive strength between an adhesive film and an exterior material.

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 encapsulates the electricity storage device element. The exterior material for an electricity storage device has a heat-sealable resin layer that is disposed on the outermost surface on the electricity storage device element side. The adhesive film for metal terminals has one surface made of resin layer A, and the adhesive film for metal terminals and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminals arranged so that the resin layer A is located on the surface, and when the adhesive film for metal terminals of the metal terminal with adhesive film for metal terminals and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminals and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminals and the heat-sealable resin layer.

The adhesive film for metal terminals disclosed herein has these characteristics, and therefore can exhibit high adhesive strength when the adhesive film is heat-sealed to the heat-sealable resin layer of the exterior material for the electricity storage device.

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.

Also, as a method for confirming the MD of an adhesive film for metal terminals, there is a method of observing a cross section of the adhesive film for metal terminals (e.g., a cross section of an acid-modified polyolefin layer or a polyolefin layer) with an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section in which the average diameter of the island shape in the direction perpendicular to the thickness direction of the adhesive film for metal terminals was the largest can be determined as the MD. Specifically, the cross section in the length direction of the adhesive film for metal terminals and each cross section (10 cross sections in total) at an angle of 10 degrees from the direction parallel to the cross section in the length direction to the direction perpendicular to the cross section in the length direction are observed with an electron microscope to confirm the sea-island structure. Next, the shape of each individual island is observed in each cross section. For each island shape, the straight line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the adhesive film for metal terminals and the rightmost end in the perpendicular direction is taken as the diameter y. In each cross section, the average of the diameters y of the top 20 island shapes in descending order of diameter y is calculated. The direction parallel to the cross section in which the average diameter y of the island shape is the largest is determined to be the MD. In addition, for example, the adhesive film for metal terminals can be left in a 150°C environment for 2 minutes, and the thermal shrinkage rate measured, and the direction with the larger shrinkage rate can be determined to be the MD.

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, for example, under conditions of a temperature of about 140-160°C, a pressure of about 0.01-1.0 MPa, a time of about 3-15 seconds, and a number of times of about 3-6, while the main adhesion process is carried out, for example, under conditions of a temperature of about 160-240°C, a pressure of about 0.01-1.0 MPa, a time of about 3-15 seconds, and a number of times of about 1-3. 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 1.0-5.0 MPa, a time of about 1-5 seconds, and a number of times of about 1.

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.

[Resin layer A]
The adhesive film 1 for metal terminal of the present disclosure includes at least a resin layer A. The resin layer A forms at least one surface of the adhesive film 1 for metal terminal and is the outermost layer. That is, the adhesive film 1 for metal terminal of the present disclosure includes at least one resin layer A, and at least one surface of the adhesive film 1 for metal terminal is formed by the resin layer A. As long as the effects of the present disclosure are achieved, the adhesive film 1 for metal terminal of the present disclosure may be a single layer as shown in FIG. 4, or may have a multilayer structure (multiple layers) 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 resin layer A, and the surface on the metal terminal side and the surface of the exterior material for a storage battery device are formed by the resin layer A. In this case, the resin forming the surface on the exterior material for a storage battery 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., the resin constituting the resin layer A). Note that the resin forming the surface on the exterior material for a storage battery 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 preferably the same, more preferably 90% by mass or more are the same, even more preferably 95% by mass or more are the same, and even more preferably 100% by mass are the same.

When the adhesive film 1 for metal terminals of the present disclosure has a multi-layer structure (multi-layer), at least one layer may be composed of the resin layer A. 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. As described later, in the present disclosure, of these layers, the second resin layer 12b is composed of the resin layer A. Furthermore, by forming the surface of the outer layer material for the electric storage device, in the state of the metal terminal with the adhesive film for metal terminals, the second resin layer 12b (resin layer A) faces the heat-sealable resin layer of the outer layer material for the electric storage device and can be heat-sealed. Even when the adhesive film 1 for metal terminals of the present disclosure has a multi-layer structure (multi-layer), the resin forming the surface of the outer layer material for the electric storage device and the resin forming the surface of the metal terminal 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.

The surface of the adhesive film 1 for metal terminals of the present disclosure that faces the exterior material for an electrical storage device (i.e., the surface of the second resin layer 12b (resin layer A)) has thermal adhesion to the thermally adhesive resin layer described below. In the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the second resin layer 12b is formed by the resin layer A.

The first resin layer 12a constituting the surface on the metal terminal side of the adhesive film 1 for metal terminals of the present disclosure has thermal adhesion to metal (the metal constituting the metal terminal). Therefore, when using the adhesive film 1 for metal terminals of the present disclosure, it is preferable to use the first resin layer 12a by placing it on the metal terminal side.

The resin layer A is preferably a layer containing a polyolefin skeleton such as polyolefin, and more preferably a layer containing polyolefin. From the viewpoint of more suitably exerting the effects of the present disclosure, the resin layer A is preferably formed from polyolefin. In other words, the resin layer A can be suitably constituted from a polyolefin film.

Specific examples of polyolefins 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 may be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of 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 constituent monomer.

In addition, when the adhesive film 1 for metal terminals is a single layer as shown in FIG. 4, the adhesive film 1 for metal terminals must have thermal adhesion to the surface of the metal terminal and the surface of the exterior material for the electrical storage device, and in particular, taking into consideration thermal adhesion to metals, the polyolefin may be an acid-modified polyolefin (i.e., an acid-modified polyolefin). There are no particular limitations on the acid-modified polyolefin, so long as it is an acid-modified polyolefin, but preferred examples include 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 that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers that are constituent monomers of 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 constituent monomer.

Examples of the carboxylic acid or its anhydride used for the acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When the resin layer A is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers of about 1760 cm ^-1 and about 1780 cm ^-1 . When the resin layer A 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.

Furthermore, when the adhesive film 1 for metal terminals has a multilayer structure (multiple layers) as shown in Figures 5 to 7, it is sufficient that the surface on the metal terminal side is provided with a resin layer that has thermal adhesion to the metal, while the surface of the exterior material for an electricity storage device is provided with a resin layer A that has thermal adhesion only to the thermally adhesive resin layer of the exterior material for an electricity storage device. Therefore, considering that the resin used in the thermally adhesive resin layer of the exterior material for an electricity storage device is an acid-unmodified polyolefin, particularly an acid-unmodified polypropylene, and that resins of the same type have excellent thermal adhesion, the resin layer A can be suitably constituted by an acid-unmodified polyolefin film, particularly an acid-unmodified polypropylene film.

In the present disclosure, the adhesive film for metal terminals has one surface composed of resin layer A, and the adhesive film for metal terminals and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds (one time) to obtain a metal terminal with an adhesive film arranged so that resin layer A is located on the surface, and when the adhesive film of the metal terminal with adhesive film is heat-sealed to a heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film and the heat-sealable resin layer.

From the viewpoint of more optimally exerting the effects of the present disclosure, the difference is preferably 0.29 nm or less, more preferably 0.25 nm or less, and even more preferably 0.20 nm or less. The lower limit of the difference can be, for example, 0.00 nm or 0.01 nm, and preferred ranges include about 0.00 to 0.30 nm, about 0.00 to 0.29 nm, about 0.00 to 0.25 nm, about 0.00 to 0.20 nm, about 0.1 to 0.30 nm, about 0.10 to 0.29 nm, about 0.10 to 0.25 nm, and about 0.10 to 0.20 nm.

The crystalline lamellar thickness A of the resin layer A of the adhesive film is preferably 4.0 nm or more, more preferably 4.5 nm or more, and even more preferably 5.0 nm or more, and is preferably 10.0 nm or less, more preferably 9.5 nm or less, and even more preferably 9.0 nm or less. Preferred ranges include about 4.0 to 10.0 nm, about 4.0 to 9.5 nm, about 4.0 to 9.0 nm, about 4.5 to 10.0 nm, about 4.5 to 9.5 nm, about 4.5 to 9.0 nm, about 5.0 to 10.0 nm, about 5.0 to 9.5 nm, and about 5.0 to 9.0 nm.

The crystal lamella thickness B of the heat-sealable resin layer of the exterior material for an electrical storage device is preferably 5.1 nm or more, more preferably 5.5 nm or more, and even more preferably 6.0 nm or more, and is preferably 9.0 nm or less, more preferably 8.5 nm or less, and even more preferably 8.0 nm or less. Preferred ranges include about 5.0 to 9.0 nm, about 5.0 to 8.5 nm, about 5.0 to 8.0 nm, about 5.1 to 9.0 nm, about 5.1 to 8.5 nm, about 5.1 to 8.0 nm, about 5.5 to 9.0 nm, about 5.5 to 8.5 nm, about 5.5 to 8.0 nm, about 6.0 to 9.0 nm, about 6.0 to 8.5 nm, and about 6.0 to 8.0 nm.

<Measurement of crystalline lamella thickness A of resin layer A of adhesive film and crystalline lamella thickness B of heat-fusible resin layer of exterior material>
The other surface of the adhesive film (MD 25 mm, TD 20 mm) having the resin layer A constituting one surface and the metal terminal (length 22.5 mm, width 30 mm, thickness 0.4 mm) are heat-sealed under the conditions of a temperature of 200° C., a pressure of 0.25 MPa, and a time of 16 seconds (one time) to obtain a metal terminal with an adhesive film arranged so that the resin layer A is located on the surface. At this time, the MD of the adhesive film and the vertical direction of the metal terminal are made to coincide. Furthermore, in the state of a metal terminal with an adhesive film for a metal terminal, the resin layer A is arranged on the outermost surface. Next, the adhesive film of the metal terminal with the adhesive film and a heat-sealable resin layer (heat-sealable resin layer made of random polypropylene resin (MD 120 mm, TD 30 mm, thickness 80 μm)) having a crystal lamellar thickness of 5.0 to 9.0 nm of the exterior material for a storage battery device are heat-sealed under the conditions of a temperature of 200° C., a pressure of 1.0 MPa, and a time of 3 seconds to obtain a sample for measurement. At this time, the MD of the adhesive film and the TD of the heat-sealable resin layer of the electrical storage device packaging material are made to coincide with each other. STEM observation is performed from the cross-sectional direction of the heat-sealed portion between the adhesive film and the heat-sealable resin layer under the following measurement conditions, and the crystalline lamellar thickness A of the resin layer A of the adhesive film and the crystalline lamellar thickness B of the heat-sealable resin layer of the electrical storage device packaging material are measured under the following measurement conditions using the following image processing conditions for the obtained image data.

(Measurement conditions)
[Pretreatment]
After cutting the sample into strips, it is embedded in a thermosetting resin and hardened at 50° C. for 12 hours. Then, a cross section is prepared using an ultramicrotome (using a glass knife: finishing thickness 0.5 um) and then Ru staining is performed. Furthermore, an ultrathin section is prepared using an ultramicrotome (using a diamond knife: finishing thickness 80 nm).

[STEM observation]
・Measuring device: STEM
Acceleration voltage: 30.0 kV
Emission current: 10 μA
・W.D: 8mm
Detector: TE
・Number of captured pixels: 5120 x 3840
Scan speed: 80 sec

[Image processing conditions]
<Binarization process>
Using an image processing program such as Python's OpenCV library, the STEM image is binarized in black and white according to the following procedure, so that white parts represent crystalline parts of a lamellar structure and black parts represent amorphous parts of a lamellar structure. Note that a lamellar structure is a periodic structure formed by alternating crystalline and amorphous parts of polymer molecules.
1. Crop 512px x 512px from the measurement image. 2. Adaptive contrast flattening (clipLimit = 2.0, tileGridSize = (8, 8)).
3. Contrast flattening 4. Binarization (threshold brightness = 127)
5. Noise removal (removal of white areas less than 5px^2)
6. Noise removal (removal of black areas less than 5px^2)
7. Morphological transformation-Open processing (kernel size = 3px x 3px)
8. Morphological transformation-Close processing (kernel size = 3px x 3px)

[Quantification of Crystalline Lamella Thickness]
For the white parts of the binarized image, ImageJ, an image analysis freeware developed by the National Institutes of Health (NIH), is used to calculate the local thickness for each pixel in the white parts. Then, the average value of the local thickness of the entire image area is calculated for the local thickness values of pixels with a non-zero local thickness value. This calculation is performed for 20 images, and the average value is derived, converted to nm from the magnification at the time of imaging, and defined as the crystalline lamella thickness. The crystalline lamella thicknesses A and B are calculated for the resin layer A and the heat-sealable resin layer. The absolute value of the difference between the crystalline lamella thicknesses A and B is defined as the crystalline lamella thickness difference.

Methods for adjusting the crystalline lamellar thickness A of the resin layer A of the adhesive film include, for example, the molding method when forming the resin layer A (for example, the type of molding method such as extrusion method or inflation method, cooling temperature, cooling time, line speed, clearance), resin blend, and selection of resin type. For example, if the cooling rate after film formation is slowed, the crystalline lamellar thickness A tends to increase, and, for example, if the cooling rate after film formation is fast, the crystalline lamellar thickness A tends to decrease. In particular, in the molding of the resin layer A, the film formation temperature, film formation speed, and cooling conditions (chill roll temperature) are conditions that have a large effect on the cooling rate of the resin layer A. For example, if the film formation temperature and film formation speed are high and the chill roll temperature is low, the extruded resin will be rapidly cooled. This will result in a small crystalline lamellar thickness. On the other hand, if the film formation temperature and film formation speed are low and the chill roll temperature is high, the extruded resin will be slowly cooled, and the crystalline lamellar thickness will increase. The thickness of the resin layer A also affects the crystalline lamellar thickness. A heat-sealable resin layer with a crystalline lamellar thickness of 5.0 to 9.0 nm is prepared, and a measurement sample is prepared as described above to measure the crystalline lamellar thicknesses A and B. From these measurement results, a resin film for forming the resin layer A is selected (for example, it may be selected from commercially available products, etc.), and the resin film with a difference between the crystalline lamellar thicknesses A and B of 0.3 nm or less is used as the resin layer A of the present disclosure.

In the adhesive film 1 for metal terminals of the present disclosure, the difference between the crystalline lamellar thicknesses A and B is 0.3 nm or less, so that high adhesive strength can be exhibited when the adhesive film and the heat-sealable resin layer of the exterior material for the electric storage device are heat-sealed. The reason for this can be considered as follows. That is, after the resin layer A of the adhesive film and the heat-sealable resin layer of the exterior material for the electric storage device are heat-sealed, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film and the crystalline lamellar thickness B of the heat-sealable resin layer of the exterior material for the electric storage device is a very small value of 0.3 nm or less, so that it can be evaluated that these layers are easily mixed at the interface between the resin layer A and the heat-sealable resin layer, and integration is promoted, and as a result, it can be considered that these layers are firmly bonded to each other, and high adhesive strength is exhibited.

The adhesive film of the present disclosure has a temperature at 90% volume melting (the melting temperature (°C) when the adhesive film of the present disclosure is heated by the method described below and the melting ratio is 90% by volume) of preferably 100°C or higher, more preferably 105°C or higher, even more preferably 107°C or higher, and preferably 120°C or lower, more preferably 117°C or lower, even more preferably 115°C or lower, with preferred ranges being approximately 100-120°C, approximately 100-117°C, approximately 100-115°C, approximately 105-120°C, approximately 105-117°C, approximately 105-115°C, approximately 107-120°C, approximately 107-117°C, and approximately 107-115°C. Furthermore, the temperature of resin layer A at 75% by volume melting is preferably 100°C or higher, more preferably 103°C or higher, and even more preferably 105°C or higher, and is preferably 120°C or lower, more preferably 118°C or lower, and even more preferably 116°C or lower, with preferred ranges being about 100 to 120°C, about 100 to 118°C, about 100 to 116°C, about 103 to 120°C, about 103 to 118°C, about 103 to 116°C, about 105 to 120°C, about 105 to 118°C, and about 105 to 116°C. Furthermore, the temperature of resin layer A at 50% by volume melting is preferably 95°C or higher, more preferably 98°C or higher, and even more preferably 100°C or higher, and is preferably 115°C or lower, more preferably 112°C or lower, and even more preferably 110°C or lower, with preferred ranges being about 95 to 115°C, about 95 to 112°C, about 95 to 110°C, about 98 to 115°C, about 98 to 112°C, about 98 to 110°C, about 100 to 115°C, about 100 to 112°C, and about 100 to 110°C. Furthermore, the temperature of resin layer A at 25% by volume melting is preferably 90°C or higher, more preferably 92°C or higher, and even more preferably 94°C or higher, and is preferably 108°C or lower, more preferably 106°C or lower, and even more preferably 104°C or lower, with preferred ranges being about 90 to 108°C, about 90 to 106°C, about 90 to 104°C, about 92 to 108°C, about 92 to 106°C, about 92 to 104°C, about 94 to 108°C, about 94 to 106°C, and about 94 to 104°C. Furthermore, the temperature of the resin layer A at 10% volume melting is preferably 84°C or higher, more preferably 86°C or higher, and even more preferably 88°C or higher, and is preferably 102°C or lower, more preferably 100°C or lower, and even more preferably 98°C or lower, with preferred ranges being about 84-102°C, about 84-100°C, about 84-98°C, about 86-102°C, about 86-100°C, about 86-98°C, about 88-102°C, about 88-100°C, and about 88-98°C. For example, if the temperature at 25% volume melting is low, it is advantageous when the heat-sealable resin layer of the exterior material and the adhesive film are heat-sealed in a low-temperature environment.

<Melting ratio (volume %) and melting temperature (°C) of adhesive film>
According to the following procedure, an adhesive film is heated to 210°C to melt it, and then cooled from 210°C at a temperature drop rate of 10°C/min, and the temperatures when the adhesive film is 90% melted by volume, 75% melted by volume, 50% melted by volume, 25% melted by volume, and 10% melted by volume are measured.

The heat of fusion of each measurement sample is measured in accordance with the provisions of JIS K 7122:2012. The measurement is performed using a differential scanning calorimeter. 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 heat of fusion ΔH (J/g) 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 heat of fusion ΔH (J/g). The flow rate of nitrogen gas is 50 ml/min. The value of the heat of fusion ΔH (J/g) measured in the first time by the above procedure is adopted. The heat of fusion is defined as the melting peak area surrounded by the baseline (a straight line connecting 80°C to 170°C on the DSC curve) and the peak in the DSC curve. Meanwhile, the heat of fusion of crystals in a temperature range below X°C is calculated from the area of the melting peak area in the temperature range below X°C when calculating the total heat of fusion of crystals. In other words, the "melting rate at temperature X°C" is a value calculated from the following formula.
Melting rate (%) at temperature X°C = {(area of melting peak area in the temperature range equal to or lower than temperature X) / (melting peak area)} × 100 ... formula Therefore, the temperature at 25% melting is temperature X°C at which the melting rate at temperature X (melting proportion (volume %)) = 25 is satisfied.

The resin layer A may be formed from one type of resin component alone, or from a blended polymer combining two or more types of resin components. From the viewpoint of film formability, it is preferable that the resin layer A is formed from a blended polymer combining two or more types of resin components. When using a blended polymer, it is preferable that the resin layer A contains, for example, polypropylene as the main component (a component of 50% by mass or more) and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the resin layer A, it is preferable that the resin layer A contains polypropylene alone as the resin.

Resin layer A may contain known additives as necessary, to the extent that they do not impair the effects of the present disclosure.

For example, the resin layer A may contain a filler as necessary. When the resin layer A 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 an electrical storage 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, relative to 100 parts by mass of the resin component that forms the resin layer A.

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 resistance to contents, aluminum oxide, silica, fluororesin, acrylic resin, and benzoguanamine-formaldehyde condensate are preferred, and among these, spherical aluminum oxide and silica are particularly preferred. The filler can be mixed into the resin component that forms the resin layer A by melt-blending the two in advance using a Banbury mixer or the like to create a master batch and mixing it in a specified ratio, or by directly mixing it with the resin component.

The resin layer A may also contain a pigment if necessary. As the pigment, various inorganic pigments can be used. A specific example of the pigment is preferably carbon (carbon, graphite) as exemplified in the filler above. Carbon (carbon, graphite) is a material that is generally used inside an electricity storage device and is not likely to dissolve in the electrolyte. In addition, it has a large coloring effect and can obtain a sufficient coloring effect with an amount added that does not inhibit adhesion, and it does not melt due to heat, and can increase the apparent melt viscosity of the added resin. Furthermore, it can prevent the pressurized part from becoming thin during heat adhesion (heat sealing), and can provide excellent sealing between the exterior material for electricity storage devices and the metal terminal.

When adding a pigment to the resin layer A, the amount of the pigment added is, for example, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin components forming the resin layer A when carbon black with a particle size of about 0.03 μm is used. By adding a pigment to the resin layer A, the presence or absence of the adhesive film 1 for metal terminals can be detected by a sensor or visually inspected. When adding a filler and a pigment to the resin layer A, the filler and the pigment may be added to the same resin layer A, but from the viewpoint of not impairing the thermal fusion properties of the adhesive film 1 for metal terminals, it is preferable to add the filler and the 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 resin layer A is preferably 125°C or higher, more preferably about 130°C or higher, and even more preferably about 135°C or higher. From the same viewpoint, the melting peak temperature is, for example, 180°C or lower, preferably 175°C or lower, more preferably 170°C or lower, even more preferably about 165°C or lower, and even more preferably about 160°C or lower. Preferred ranges of the melting peak temperature include about 125 to 180°C, about 125 to 175°C, about 125 to 170°C, about 125 to 165°C, about 125 to 160°C, about 130 to 180°C, about 130 to 175°C, about 130 to 170°C, about 130 to 165°C, about 130 to 160°C, about 135 to 180°C, about 135 to 175°C, about 135 to 170°C, about 135 to 165°C, and about 135 to 160°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). 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 of the present disclosure is composed of a single layer of resin layer A, the total thickness of the adhesive film 1 for metal terminals, which will be described later, corresponds to the thickness of resin layer A.

Furthermore, when the adhesive film 1 for metal terminals of the present disclosure is constructed with a multilayer structure (multiple layers), from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer A is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, even more preferably about 30 μm or more, even more preferably about 40 μm or more, even more preferably about 50 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, even more preferably 80 μm or less. Preferred ranges of the thickness of the resin layer A include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, about 20 to 80 μm, about 30 to 120 μm, about 30 to 100 μm, about 30 to 80 μm, about 40 to 120 μm, about 40 to 100 μm, about 40 to 80 μm, about 50 to 120 μm, about 50 to 100 μm, and about 50 to 80 μm. From the viewpoint of improving the insulating properties of the adhesive film for metal terminals, the thickness of the resin layer A is preferably about 55 μm or more, more preferably about 60 μm or more, and is also preferably about 100 μm or less, more preferably about 90 μm or less, with preferred ranges including about 55 to 100 μm, about 55 to 90 μm, about 60 to 100 μm, and about 60 to 90 μm. When the adhesive film for metal terminals 1 of the present disclosure includes multiple resin layers A, it is preferable that the thickness of each resin layer A is the above-mentioned thickness.

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 this configuration, the first resin layer 12a is disposed on the metal terminal 2 side. In this configuration, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively. In addition, since the second resin layer 12b constitutes the surface on the side of the exterior material 3 for an electricity storage device, at least the second resin layer 12b is referred to as resin layer A.

The first resin layer 12a is a layer made of resin. The first resin layer 12a may be formed of resin layer A, or may be formed of resin layer B different from resin layer A. Since the first resin layer 12a is disposed on the metal terminal 2 side, it preferably contains the acid-modified polyolefin described above, and is preferably formed of acid-modified polyolefin. In other words, the first resin layer 12a can be suitably formed of an acid-modified polyolefin film. The acid-modified polyolefin is as described for resin layer A.

Furthermore, the intermediate layer 11 may be formed from a resin layer A, or may be formed from a resin layer B that is different from the resin layer A.

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

As described below, the first resin layer 12a preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed from a polyolefin. The first resin layer 12a preferably contains, among the polyolefin resins, a polyolefin or an acid-modified polyolefin, more preferably contains an acid-modified polyolefin, and is even more preferably a layer formed from an acid-modified polyolefin.

Furthermore, the intermediate layer 11 preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and more preferably is a layer formed from a polyolefin.

In the resin layer B used in the first resin layer 12a and the intermediate layer 11, the polyolefin resin is preferably a polypropylene resin. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene.

The resin layer B may be formed of one type of resin component alone, or may be formed of a blend polymer combining two or more types of resin components. From the viewpoint of film formability, it is preferable that the resin layer B is formed of a blend polymer combining two or more types of resin components. When using a blend polymer, it is preferable that the resin layer B has acid-modified polypropylene as 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). Furthermore, it is preferable that the resin layer B containing acid-modified polypropylene has acid-modified polypropylene as 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, it is preferable that the resin layer B contains acid-modified polypropylene alone as a resin.

The polyester resin constituting the resin layer B is, for example, one that contains a polyester structure such as polyethylene terephthalate or polybutylene terephthalate. In addition to the polyethylene terephthalate structure or polybutylene terephthalate structure, the polyester structure may further contain a polyether structure, and the polyether structure may have a polycondensation structure of at least one of polytetramethylene ether glycol and neopentyl glycol and terephthalic acid of a polybutylene terephthalate structure. In addition to the polyethylene terephthalate structure or polybutylene terephthalate structure, the polyester structure may further contain another polyester structure, and the polyester structure may have a polycondensation structure of at least one selected from the group consisting of isophthalic acid, dodecanedioic acid, and sebacic acid and 1,4-butanediol of a polybutylene terephthalate structure.

The melting peak temperature of resin layer B is preferably 125°C or higher, more preferably about 130°C or higher, and even more preferably about 135°C or higher. The melting peak temperature is, for example, 180°C or lower, preferably 175°C or lower, more preferably 170°C or lower, even more preferably about 165°C or lower, and even more preferably about 160°C or lower. Preferred ranges for the melting peak temperature include about 125 to 180°C, about 125 to 175°C, about 125 to 170°C, about 125 to 165°C, about 125 to 160°C, about 130 to 180°C, about 130 to 175°C, about 130 to 170°C, about 130 to 165°C, about 130 to 160°C, about 135 to 180°C, about 135 to 175°C, about 135 to 170°C, about 135 to 165°C, and about 135 to 160°C.

Furthermore, when the adhesive film 1 for metal terminals of the present disclosure has 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 resin layer B is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, even more preferably about 30 μm or more, even more preferably about 40 μm or more, even more preferably about 50 μm or more, even more preferably more than about 50 μm, even more preferably about 60 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, even more preferably 80 μm or less, even more preferably 50 μm or less. Preferred ranges of the thickness of the resin layer B are about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 10 to 50 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 15 to 50 μm, about 20 to 120 μm, about 20 to 100 μm, about 20 to 80 μm, about 20 to 50 μm, and about 30 to 120 μm. , about 30 to 100 μm, about 30 to 80 μm, about 30 to 50 μm, about 40 to 120 μm, about 40 to 100 μm, about 40 to 80 μm, about 40 to 50 μm, about 50 to 120 μm, about 50 to 100 μm, about 50 to 80 μm, more than 50 μm and up to about 120 μm, more than 50 μm and up to about 100 μm, and more than 50 μm and up to about 80 μm.

In addition, 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 10 μm or more, more preferably about 20 μm or more, and even more preferably about 30 μm or more. When the adhesive film 1 for metal terminals of the present disclosure is used in a relatively large storage device such as a power storage device for a power storage system or an in-vehicle storage device, the thickness of the resin layer B is preferably about 50 μm or more, more preferably more than about 50 μm. In addition, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 120 μm or less, more preferably about 110 μm or less, and even more preferably 100 μm or less. When the adhesive film 1 for metal terminals of the present disclosure is used in a relatively small storage device such as a storage device for a mobile phone, a storage device for a smartphone, or a storage device for a tablet terminal, the thickness of the resin layer B is preferably about 50 μm or less, or about 30 μm or less. Preferred ranges for the thickness of the resin layer B include about 10 to 120 μm, about 10 to 110 μm, about 10 to 100 μm, about 10 to 50 μm, about 10 to 30 μm, about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 20 to 50 μm, about 20 to 30 μm, about 30 to 120 μm, about 30 to 110 μm, about 30 to 100 μm, about 30 to 50 μm, about 50 to 120 μm, about 50 to 110 μm, about 50 to 100 μm, more than 50 μm and up to about 120 μm, more than 50 μm and up to about 110 μm, and more than 50 μm and up to about 100 μm.

In addition, resin layer B may contain known additives (such as the above-mentioned fillers and pigments) just like resin layer A. The types and amounts of fillers and pigments to be added are the same as those for resin layer A.

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 80 μm or more, more preferably about 90 μm or more, and even more preferably about 100 μm or more. The total thickness of the adhesive film 1 for metal terminals of the present disclosure is about 500 μm or less, preferably about 300 μm or less, more preferably about 250 μm or less, even more preferably 200 μm or less, and even more preferably 180 μm or less. Preferred ranges of the total thickness of the adhesive film 1 for metal terminals of the present disclosure include about 50 to 500 μm, about 50 to 300 μm, about 50 to 250 μm, about 50 to 200 μm, about 50 to 180 μm, about 80 to 500 μm, about 80 to 300 μm, about 80 to 250 μm, about 80 to 200 μm, about 80 to 180 μm, about 90 to 500 μm, about 90 to 300 μm, about 90 to 250 μm, about 90 to 200 μm, about 90 to 180 μm, about 100 to 500 μm, about 100 to 300 μm, about 100 to 250 μm, about 100 to 200 μm, and about 100 to 180 μm. As a more specific example, when the adhesive film 1 for metal terminals of the present disclosure is used in a relatively small power storage device for a mobile phone, smartphone, or tablet, the total thickness is preferably about 60 to 100 μm, and when it is used in a relatively large power storage device for a power storage system or vehicle, the total thickness is preferably about 100 to 200 μm.

From the viewpoint of more optimally achieving the effects of the present disclosure, the adhesive film 1 for metal terminals of the present disclosure has an adhesive strength (peel strength in a 25°C environment) with the heat-sealable resin layer of the exterior material, measured by the following method, of preferably about 80 N/15 mm or more, more preferably about 90 N/15 mm or more, and even more preferably about 100 N/15 mm or more, and the upper limit of the adhesive strength (in a 25°C environment) is usually about 140 N/15 mm or less, with preferred ranges being about 80 to 140 N/15 mm, about 90 to 140 N/15 mm, and about 100 to 140 N/15 mm.

In addition, from the viewpoint of more suitably achieving the effects of the present disclosure, the adhesive film 1 for metal terminals of the present disclosure has an adhesive strength (peel strength in a 60°C environment) with the heat-sealable resin layer of the exterior material, measured by the following method, of preferably about 60 N/15 mm or more, more preferably about 70 N/15 mm or more, and even more preferably about 80 N/15 mm or more, and the upper limit of the adhesive strength (in a 60°C environment) is usually about 120 N/15 mm or less, with preferred ranges being about 60 to 120 N/15 mm, about 70 to 120 N/15 mm, and about 80 to 120 N/15 mm.

<Measurement of adhesive strength between adhesive film and exterior material (25° C. environment or 60° C. environment)>
The adhesive strength (peel strength) between the adhesive film exterior material and the metal terminal is measured by the following procedure. (Preparation of Exterior Material)
First, an exterior material for a power storage device (hereinafter, sometimes simply referred to as "exterior material") is prepared by the following procedure. A base layer (thickness 30 μm) consisting of a polyethylene terephthalate film (thickness 12 μm)/adhesive layer (thickness 3 μm)/nylon film (thickness 15 μm) is laminated on an aluminum alloy foil (thickness 40 μm) by a dry lamination method, and a heat-sealing resin layer is laminated on the other surface by co-extrusion. Specifically, a two-liquid urethane adhesive (a polyol compound and an aromatic isocyanate compound) is applied on the nylon film, and an adhesive layer (thickness 3 μm) is formed on the nylon film. Next, the adhesive layer and a polyethylene terephthalate film are laminated on the nylon film to prepare a base layer. Next, a two-liquid urethane adhesive (a polyol compound and an aromatic isocyanate compound) is applied on one surface of a barrier layer consisting of an aluminum alloy foil, and an adhesive layer (thickness 3 μm) is formed on the aluminum alloy foil. Next, the adhesive layer and the substrate layer with the nylon film side as the adhesive surface are laminated on the aluminum alloy foil, and then aging treatment is performed to produce a substrate layer/adhesive layer/barrier layer laminate. Next, an adhesive layer (40 μm thick, arranged on the metal layer side) made of maleic anhydride-modified polypropylene resin and a heat-sealable resin layer (40 μm crystalline lamella thickness, innermost layer) made of random polypropylene resin are co-extruded on the barrier layer of the laminate to laminate the adhesive layer/heat-sealable resin layer on the barrier layer, thereby obtaining an exterior material for a storage battery device in which the substrate layer, adhesive layer, barrier layer, adhesive layer, and heat-sealable resin layer are laminated in this order. The crystalline lamella thickness of the heat-sealable resin layer of the obtained exterior material for a storage battery device is 5.0 to 9.0 nm.

Next, a piece of aluminum foil (JIS H4160:1994 A8079H-O) with an MD of 40 mm, TD of 22.5 mm and thickness of 400 μm is prepared as the metal terminal 2. The adhesive film 1 is cut to a length of 45 mm and a width of 20 mm. Next, as shown in the schematic diagram of Figure 9, the metal terminal is sandwiched between two adhesive films to obtain an adhesive film/metal terminal/adhesive film laminate. At this time, the MD and TD of the metal terminal are aligned with the length and width directions of the adhesive film, respectively, and the metal terminal and adhesive film are laminated so that their centers are aligned (see Figure 9(a)). The first resin layer of the adhesive film is also arranged on the metal terminal side. Next, the laminate is sandwiched between two polytetrafluoroethylene films (PTFE films, thickness 100 μm), and heated under conditions of a temperature of 200 ° C., a surface pressure of 0.25 MPa, and 16 seconds (once), to heat-seal the first resin layer of the adhesive film to the metal terminal to produce a metal terminal with an adhesive film (see FIG. 9 (b)). At this time, as shown in the schematic diagram of FIG. 9, the metal terminal is sandwiched between the adhesive films, so that the periphery of the metal terminal is covered with the adhesive film, and a portion in which the two adhesive films are heat-sealed to each other is formed. Next, the exterior material is cut to a size of TD 60 mm and MD 200 mm, and as shown in the schematic diagram of FIG. 10, the exterior material is placed facing each other with the heat-sealable resin layer of the exterior material facing inside, and the obtained laminate is sandwiched between the opposing heat-sealable resin layers (see FIG. 10 (a)). At this time, the exterior material is laminated so that the MD and TD correspond to the width direction and length direction of the laminate, respectively. In this state, a heat seal tester is used to perform heat sealing (see the shaded area S in FIG. 10(b)) at a width of 7 mm (7 mm in the y-axis direction in FIG. 10(b)), at 200°C, with a surface pressure of 1.0 MPa, for 3.0 seconds, and the laminate is naturally cooled to 25°C to obtain a laminate in which the exterior material and the adhesive film are heat-sealed (see FIG. 10(b)). Next, the center of the short side direction of the obtained laminate is cut to a width of 15 mm (see the two-dot dashed line in FIG. 10(b) for the cutting position). Next, in an environment of 25°C or 60°C, the adhesive film and the heat-sealable resin layer of the exterior material are peeled off using a Tensilon universal material testing machine. The maximum strength at the time of peeling is the peel strength (N/15 mm) against the exterior material. The peel speed is 20 mm/min, the peel angle is 180°, and the chuck distance is 30 mm, and the average value is obtained by measuring three times.

The adhesive film 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 for the power storage device or to the metal terminal. Methods for forming fine irregularities on the surface of the outermost layer of the adhesive film 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 the surface. 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, and preferred ranges include 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 is a value measured by a method conforming to the provisions of JIS B0601:1994.

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 for resin layer A 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 using an example in which 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, and the second resin layer 12b is resin layer A.

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. The first resin layer 12a may be a single layer or a multi-layer structure (multi-layer). The second resin layer 12b may be a single layer or a multi-layer structure (multi-layer).

[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, the second resin layer 12b is formed from the aforementioned resin layer A. The first resin layer 12a may be formed from the aforementioned resin layer A or may be formed from the aforementioned resin layer B.

The first resin layer 12a and the second resin layer 12b can each be formed, for example, from a resin film. When the first resin layer 12a and the second resin layer 12b are each formed from a resin film, when the first resin layer 12a and the second resin layer 12b are laminated with the intermediate layer 11 or the like to manufacture the adhesive film 1 for metal terminals of the present disclosure, a preformed resin film may be used as the first resin layer 12a and the second resin layer 12b, respectively. In addition, the resins forming the first resin layer 12a and the second resin layer 12b may each be formed into a film on the surface of the intermediate layer 11 or the like by extrusion molding or coating, and used as the first resin layer 12a and the second resin layer 12b formed from the resin film.

The first resin layer 12a arranged on the metal terminal 2 side preferably contains an acid-modified polyolefin as a main component, and even more preferably contains an acid-modified polypropylene as a main component. Here, the main component means that the content of the resin components contained in the first resin layer 12a is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, the first resin layer 12a containing acid-modified polypropylene as a main component means that the content of acid-modified polypropylene among the resin components contained in the first resin layer 12a is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

As described above, the second resin layer 12b preferably contains a polyolefin-based resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. The second resin layer 12b preferably contains, among the polyolefin-based resins, a polyolefin or an acid-modified polyolefin, more preferably contains a polyolefin (polyolefin that is not acid-modified), and is even more preferably a layer formed of a polyolefin (polyolefin that is not acid-modified). The polyolefin-based resin is preferably a polypropylene-based resin. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably polypropylene.

The second resin layer 12b (resin layer A) arranged on the side of the exterior material 3 for the electric storage device more preferably contains polyolefin as a main component, and even more preferably contains polypropylene as a main component. Here, the main component means that the content of the resin components contained in the second resin layer 12b is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more. For example, the second resin layer 12b containing polypropylene as a main component means that the content of polypropylene among the resin components contained in the second resin layer 12b is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more.

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. From a similar perspective, 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 170°C or lower, and even more preferably about 160°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 170°C, about 110 to 160°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 170°C, about 120 to 160°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 170°C, and about 130 to 160°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 10 μm, more preferably at least about 15 μm, even more preferably at least about 20 μm, and is preferably no more than about 120 μm, more preferably no more than about 100 μm, even more preferably no more than 80 μm. Preferred ranges for the thickness of the first resin layer 12a include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 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 10 μm, more preferably at least about 15 μm, and even more preferably at least about 20 μm, and is preferably no more than about 120 μm, more preferably no more than about 100 μm, and even more preferably no more than 80 μm. Preferred ranges for the thickness of the second resin layer 12b include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

A colorant may be blended into at least one of the first resin layer 12a and the second resin layer 12b. Specific examples of colorants include those exemplified for the intermediate layer 11 described below.

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

The intermediate layer 11 may be formed from the aforementioned resin layer A, or may be formed from the aforementioned resin layer B.

The intermediate layer 11 can be formed, for example, from a resin film. When the intermediate layer 11 is formed from a resin film, a pre-formed resin film may be used as the intermediate layer 11 when the intermediate layer 11 is laminated with the first resin layer 12a or the like to manufacture the adhesive film for metal terminal 1 of the present disclosure. In addition, the resin forming the intermediate layer 11 may be formed into a film on the surface of the first resin layer 12a or the like by extrusion molding, coating, or the like, to form the intermediate layer 11 from a resin film.

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 repeating units are mainly ethylene terephthalate, and copolymer polyesters whose repeating units are mainly butylene terephthalate. Specific examples of copolymer polyesters whose repeating units are mainly 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, polyester resin, etc.

The melting peak temperature of the intermediate layer 11 is preferably 120°C or higher, more preferably about 130°C or higher, and even more preferably about 140°C or higher. From a similar perspective, the melting peak temperature is, for example, 210°C or lower, preferably 200°C or lower, more preferably 190°C or lower, even more preferably about 180°C or lower, and even more preferably about 170°C or lower. Preferred ranges for the melting peak temperature include about 120 to 210°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 170°C, about 130 to 210°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 170°C, about 140 to 210°C, about 140 to 200°C, about 140 to 190°C, about 140 to 180°C, and about 140 to 170°C.

The intermediate layer 11 may be a single layer or a multi-layer structure (multi-layer).

Furthermore, by blending a colorant into the intermediate layer 11, the intermediate layer 11 can be a layer containing the colorant. Also, the 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.

The colorant is not particularly limited, and a colorant capable of coloring the intermediate layer 11 can be suitably used. Specific examples of colorants include pigments. Various inorganic or organic pigments can be used as the pigment. Specific examples of pigments include the carbon (carbon, graphite), silica, titanium oxide, iron oxide, zinc oxide, magnesium oxide, and calcium oxide exemplified as the filler described above, as well as inorganic oxides such as titanium nitride, zirconia black, copper oxide, cobalt oxide, and barium sulfate, and organic pigments such as quinacridone pigments, polyazo pigments, and isoindolinone pigments. Carbon (carbon, graphite) is a material that is generally used inside an electricity storage device, and there is no risk of it 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 portion from becoming thin during heat fusion (heat sealing), thereby providing excellent sealing between the exterior material for the electricity storage device and the metal terminal. The color of the colorant is preferably black, gray, or white.

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 at most about 120 μm, more preferably at most about 110 μm, and even more preferably at most 100 μm. Preferred ranges for the thickness of the intermediate layer 11 include about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 30 to 120 μm, about 30 to 110 μm, about 30 to 100 μm, about 40 to 120 μm, about 40 to 110 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 about 0.3 or more, more preferably about 0.4 or more, and also preferably about 1.0 or less, more preferably about 0.8 or less, with preferred ranges being about 0.3 to 1.0, about 0.3 to 0.8, about 0.4 to 1.0, and about 0.4 to 0.8. From the viewpoint of improving the insulation of the adhesive film 1 for metal terminals, the ratio is preferably about 0.55 or more, more preferably about 0.60 or more, and also preferably about 1.0 or less, more preferably about 0.9 or less, with preferred ranges being about 0.55 to 1.0, about 0.55 to 0.9, about 0.60 to 1.0, and about 0.60 to 0.9.

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 of 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 arranged 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 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/a substrate formed from polypropylene/a second resin layer formed from acid-modified polypropylene are laminated in this order; and a three-layer structure in which a first resin layer formed from acid-modified polypropylene/a substrate formed from polypropylene/a second resin layer formed from polypropylene are laminated in this order. 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. Furthermore, 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 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. 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. Preferred ranges are, for example, about 35 to 190 μm, about 35 to 180 μm, and about 35 to 160 μm. degree, about 35 to 155 μm, about 35 to 140 μm, about 35 to 130 μm, about 35 to 120 μm, about 45 to 190 μm, about 45 to 180 μm, 45 ～160μm, 45-155μm, 45-140μm, 45-130μm, 45-120μm, 60-190μm, 60-180μm Examples 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 has insulating properties. 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, more preferably about 20 to 100 μm, about 20 to 45 μm, about 45 to 65 μm, or about 65 to 85 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.

(Heat-fusible 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 in which the heat-sealable resin layers are heat-sealed to each other to seal the electricity storage device elements when the electricity storage device is assembled. The heat-sealable resin layer 35 is disposed on the outermost surface on the electricity storage device element side.

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 crystalline lamellar thickness of the heat-sealable resin layer 35 is preferably in the range of 5.0 to 9.0 nm. The crystalline lamellar thickness is measured in the same manner as the measurement of the crystalline lamellar thickness B described above, using the heat-sealable resin layer 35 as the measurement sample.

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 below 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 the present disclosure 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. When in use, the kit of the present disclosure is used such 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.

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 power storage device element may be sealed by a lid in addition to the exterior material for the power storage device. That is, the exterior material for the power storage device and the lid constitute an exterior body (exterior body for the power storage device) that seals the power storage device element. For example, the power storage device element may be housed inside the exterior material for the power storage device that is configured in a cylindrical shape, and the opening may be closed by the lid. In another example, the power storage device element connected to the lid may be housed inside the exterior material for the power storage device that is configured in a cylindrical shape so that an opening is formed, and the opening may be closed by the lid. The lid and the exterior material for the power storage device are preferably joined by any means. From the viewpoint of reducing the dead space between the power storage device element and the exterior material for the power storage device in order to improve the volumetric energy density of the power storage device, the exterior material for the power storage device is preferably wrapped around the power storage device element and the lid.

The lid body can be formed, for example, from a resin molded product, a metal molded product, an exterior material for an electricity storage device, or a combination of these. In this disclosure, when the lid body is expressed as a resin molded product, this does not include an embodiment in which the lid body is composed only of a film as defined by JIS K6900-1994 [Plastics terminology]. When the lid body is a metal molded product, the lid body also functions as a metal terminal, so the metal terminal can be omitted. The lid body may be composed of a resin material and a conductive material.

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

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>
Example 1, Comparative Examples 1 and 2
Using an extruder, polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 80 μm) as an intermediate layer was extruded on one side as a second resin layer (resin layer A) on the exterior material side (PP layer, melting peak temperature 140 ° C.), and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded on the other side as a first resin layer on the metal terminal side with a thickness of 60 μm, respectively, to obtain an adhesive film (total thickness 200 μm) in which the first resin layer (PP layer, melting peak temperature 140 ° C., thickness 60 μm) / substrate (PP layer, melting peak temperature 163 ° C., thickness 80 μm) / second resin layer (resin layer A, PP layer, melting peak temperature 140 ° C., thickness 60 μm) were laminated in order. The second resin layer, which was the resin layer A, was manufactured under the film-forming temperature standard conditions, film-forming speed standard conditions, and cooling standard conditions to adjust the crystal lamellar thickness. Specifically, the temperature standard conditions, film-forming rate standard conditions, and cooling conditions (chill roll temperature) of Example 1 were used as references, and the temperature, film-forming rate, and chill roll temperature were all lowered in Comparative Example 1. Meanwhile, in Comparative Example 2, the temperature and film-forming rate were increased, and the chill roll temperature was lowered.

Example 2
Using an extruder and a T-die casting device, polypropylene (resin layer A, PP layer, melting peak temperature 140°C) was extruded as the second resin layer (resin layer A) on the exterior material side on one side of the polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 50 μm) as the intermediate layer, and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded 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 (PP layer, melting peak temperature 140°C, thickness 50 μm) / substrate (PP layer, melting peak temperature 163°C, thickness 50 μm) / second resin layer (resin layer A, PP layer, melting peak temperature 140°C, thickness 50 μm) were laminated in this order. The second resin layer, which was used as the resin layer A, was produced under standard film-forming temperature conditions, standard film-forming speed conditions, and standard cooling conditions, thereby adjusting the crystal lamella thickness.

Examples 3 and 4
Using an extruder and a T-die casting device, polypropylene (PP layer, melting peak temperature 140°C) was extruded to a thickness of 40 μm as the second resin layer (resin layer A) on the exterior material side on one side of the carbon black-containing polypropylene (PP layer, homopolypropylene, melting peak temperature 160°C, thickness 60 μm) as the intermediate layer, and maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 50 μm as the first resin layer on the metal terminal side on the other side, and an adhesive film (total thickness 150 μm) in which the first resin layer (PP layer, melting peak temperature 140°C, thickness 50 μm) / substrate (PP layer, melting peak temperature 160°C, thickness 60 μm) / second resin layer (resin layer A, PP layer, melting peak temperature 140°C, thickness 40 μm) was obtained. The second resin layer, which was used as resin layer A, was produced under conditions of a lower film-forming temperature standard, a faster film-forming speed standard, and a slower cooling standard, thereby adjusting the crystal lamella thickness.

Comparative Example 3
Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PP layer, random polypropylene, melting peak temperature 143 ° C., thickness 100 μm) was extruded on one side of the polypropylene (PP layer, random polypropylene, melting peak temperature 143 ° C., thickness 100 μm) as the intermediate layer, as the second resin layer (resin layer A) on the exterior material side, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded on the other side as the first resin layer on the metal terminal side, each with a thickness of 25 μm, to obtain an adhesive film (total thickness 150 μm) in which the first resin layer (PP layer, melting peak temperature 140 ° C., thickness 25 μm) / substrate (PP layer, melting peak temperature 143 ° C., thickness 100 μm) / second resin layer (resin layer A, PPa layer, melting peak temperature 140 ° C., thickness 25 μm) was laminated in this order. The second resin layer, which was used as resin layer A, was produced under conditions of a film-forming temperature significantly lower than the standard film-forming speed, a film-forming rate significantly slower than the standard film-forming speed, and a cooling rate faster than the standard cooling rate, thereby adjusting the crystal lamella thickness.

Comparative Example 4
Using an inflation extrusion device, a maleic anhydride-modified polypropylene (resin layer A, PPa layer, melting peak temperature 140°C) was extruded as the second resin layer (resin layer A) on the exterior material side on one side of a polypropylene (PP layer, homopolypropylene, melting peak temperature 160°C, thickness 80μm) as an intermediate layer, and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded as the first resin layer on the metal terminal side on the other side, each with a thickness of 35μm, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (PP layer, melting peak temperature 140°C, thickness 35μm)/base material (PP layer, melting peak temperature 160°C, thickness 80μm)/second resin layer (resin layer A, PPa layer, melting peak temperature 140°C, thickness 35μm) were laminated in this order. The second resin layer, which was used as resin layer A, was produced under conditions of a lower film-forming temperature standard, a significantly slower film-forming speed standard, and a significantly slower cooling speed standard, thereby adjusting the crystal lamella thickness.

Example 5
Using an extruder, polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C., thickness 50 μm) as an intermediate layer was extruded on one side as a second resin layer (resin layer A) on the exterior material side (PP layer, melting peak temperature 140 ° C.), and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded on the other side as a first resin layer on the metal terminal side with a thickness of 75 μm, respectively, to obtain an adhesive film (total thickness 200 μm) in which the first resin layer (PP layer, melting peak temperature 140 ° C., thickness 75 μm) / substrate (PP layer, melting peak temperature 163 ° C., thickness 50 μm) / second resin layer (resin layer A, PP layer, melting peak temperature 140 ° C., thickness 75 μm) was laminated in order. The second resin layer, which was the resin layer A, was manufactured under the film-forming temperature standard conditions, film-forming speed standard conditions, and cooling standard conditions to adjust the crystal lamellar thickness.

<Measurement of crystalline lamella thickness A of resin layer A of adhesive film and crystalline lamella thickness B of heat-fusible resin layer of exterior material>
The other surface of the adhesive film (MD 25 mm, TD 20 mm) having the resin layer A constituting one surface and the metal terminal (length 22.5 mm, width 30 mm, thickness 0.4 mm) were heat-sealed under the conditions of a temperature of 200 ° C., a pressure of 0.25 MPa, and 16 seconds (1 time), to obtain a metal terminal with an adhesive film arranged so that the resin layer A was located on the surface. At this time, the MD of the adhesive film and the vertical direction of the metal terminal were made to coincide. Next, the adhesive film of the metal terminal with the adhesive film and a heat-sealable resin layer (heat-sealable resin layer made of random polypropylene resin (MD 120 mm, TD 30 mm, thickness 80 μm)) of the crystalline lamellar thickness of the exterior material for a storage device described later were heat-sealed under the conditions of a temperature of 200 ° C., a pressure of 1.0 MPa, and 3 seconds to obtain a sample for measurement. At this time, the MD of the adhesive film and the TD of the heat-sealable resin layer of the exterior material for a storage device were made to coincide. Furthermore, in the state of the metal terminal with the adhesive film for a metal terminal, the resin layer A is disposed on the outermost surface. In Examples 1-3 and Comparative Examples 3 and 4, a heat-sealable resin layer having a crystalline lamellar thickness of 7.09 nm was used, in Example 4, a heat-sealable resin layer having a crystalline lamellar thickness of 5.89 nm was used, in Comparative Example 1, a heat-sealable resin layer having a crystalline lamellar thickness of 5.73 nm was used, and in Comparative Example 2, a heat-sealable resin layer having a crystalline lamellar thickness of 6.28 nm was used. Under the following measurement conditions, STEM observation was performed from the cross-sectional direction on the heat-sealed portion between the adhesive film and the heat-sealable resin layer, and the obtained image data was subjected to the following image processing conditions to measure the crystalline lamellar thickness A of the resin layer A of the adhesive film and the crystalline lamellar thickness B of the heat-sealable resin layer of the exterior material for a storage device under the following measurement conditions.

(Measurement conditions)
[Pretreatment]
After cutting the sample into strips, it is embedded in a thermosetting resin and hardened at 50°C for 12 hours. Then, a cross section is prepared in the MD direction using an ultramicrotome (using a glass knife: finishing thickness 0.5 um), and then Ru staining is performed. Furthermore, an ultrathin section is prepared using an ultramicrotome (using a diamond knife: finishing thickness 80 nm).

[STEM observation]
Measurement equipment: STEM = Hitachi High-Technologies Corporation S-4800 TYPE II
Acceleration voltage: 30.0 kV
Emission current: 10 μA
・W.D: 8mm
Detector: TE
・Number of captured pixels: 5120 x 3840
Scan speed: 80 sec

[Image processing conditions]
<Binarization process>
Using an image processing program such as Python's OpenCV library, the STEM image is binarized in black and white according to the following procedure, so that white parts represent crystalline parts of the lamellar structure and black parts represent amorphous parts of the lamellar structure. A lamellar structure is a periodic structure formed by alternating overlapping of crystalline and amorphous parts of polymer molecules.
1. Crop 512px x 512px from the measurement image. 2. Adaptive contrast flattening (clipLimit = 2.0, tileGridSize = (8, 8)).
3. Contrast flattening 4. Binarization (threshold brightness = 127)
5. Noise removal (removal of white areas less than 5px^2)
6. Noise removal (removal of black areas less than 5px^2)
7. Morphological transformation-Open processing (kernel size = 3px x 3px)
8. Morphological transformation-Close processing (kernel size = 3px x 3px)

[Quantification of Crystalline Lamella Thickness]
For the white parts of the binarized image, ImageJ, an image analysis freeware developed by the National Institutes of Health (NIH), is used to calculate the local thickness for each pixel in the white parts. Then, the average value of the local thickness of the entire image area is calculated for the local thickness values of pixels with a non-zero local thickness value. This calculation is performed for 20 images to derive the average value, which is converted to nm from the magnification at the time of imaging and defined as the crystalline lamella thickness. The crystalline lamella thicknesses A and B are calculated for the resin layer A and the heat-sealable resin layer. The absolute value of the difference between the crystalline lamella thicknesses A and B is defined as the crystalline lamella thickness difference.

<Melting ratio (volume %) and melting temperature (°C) of adhesive film>
According to the following procedure, the adhesive film was heated to 210°C to melt, and cooled from 210°C at a temperature drop rate of 10°C/min, and the temperatures at which the adhesive film was 90% melted by volume, 75% melted by volume, 50% melted by volume, 25% melted by volume, and 10% melted by volume were measured. The results are shown in Table 1.

The heat of fusion of each measurement sample is measured in accordance with the provisions of JIS K 7122:2012. The measurement is performed using a differential scanning calorimeter (DSC, 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 heat of fusion ΔH (J/g) 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 heat of fusion ΔH (J/g). The flow rate of nitrogen gas is 50 ml/min. The value of the heat of fusion ΔH (J/g) measured in the first measurement by the above procedure is adopted. The heat of fusion is defined as the melting peak area surrounded by the baseline (a straight line connecting 80°C to 170°C on the DSC curve) and the peak in the DSC curve. Meanwhile, the heat of fusion of crystals in a temperature range below X°C is calculated from the area of the melting peak area in the temperature range below X°C when calculating the total heat of fusion of crystals. In other words, the "melting rate at temperature X°C" is a value calculated from the following formula.
Melting rate (%) at temperature X°C = {(area of melting peak area in the temperature range equal to or lower than temperature X) / (melting peak area)} × 100 ... formula Therefore, the temperature at 25% melting is temperature X°C at which the melting rate at temperature X (melting proportion (volume %)) = 25 is satisfied.

<Measurement of adhesive strength between adhesive film and exterior material (25° C. environment or 60° C. environment)>
The adhesive strength (peel strength) between the exterior material of the adhesive film and the metal terminal was measured by the following procedure. The results are shown in Table 1.
(Preparation of exterior materials)
First, an exterior material for a power storage device (hereinafter, sometimes simply referred to as "exterior material") was prepared by the following procedure. A base layer (thickness 30 μm) consisting of a polyethylene terephthalate film (thickness 12 μm)/adhesive layer (thickness 3 μm)/nylon film (thickness 15 μm) was laminated on an aluminum alloy foil (thickness 40 μm) by a dry lamination method, and a heat-sealing resin layer was laminated on the other surface by co-extrusion. Specifically, a two-liquid urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied on the nylon film, and an adhesive layer (thickness 3 μm) was formed on the nylon film. Next, the adhesive layer and a polyethylene terephthalate film were laminated on the nylon film to prepare a base layer. Next, a two-liquid urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied on one surface of a barrier layer consisting of an aluminum alloy foil, and an adhesive layer (thickness 3 μm) was formed on the aluminum alloy foil. Next, the adhesive layer and the substrate layer with the nylon film side as the adhesive surface were laminated on the aluminum alloy foil, and then aging treatment was performed to produce a substrate layer/adhesive layer/barrier layer laminate. Next, an adhesive layer (40 μm thick, arranged on the metal layer side) made of maleic anhydride-modified polypropylene resin and a heat-sealable resin layer (80 μm thick, innermost layer) made of random polypropylene resin were co-extruded on the barrier layer of the laminate to laminate the adhesive layer/heat-sealable resin layer on the barrier layer, thereby obtaining an exterior material for a power storage device in which the substrate layer, adhesive layer, barrier layer, adhesive layer, and heat-sealable resin layer were laminated in this order. In Examples 1-3 and Comparative Examples 3 and 4, a heat-sealable resin layer having a crystalline lamella thickness of 7.09 nm was used, in Example 4, a heat-sealable resin layer having a crystalline lamella thickness of 5.89 nm was used, in Comparative Example 1, a heat-sealable resin layer having a crystalline lamella thickness of 5.73 nm was used, and in Comparative Example 2, a heat-sealable resin layer having a crystalline lamella thickness of 6.28 nm was used.

Next, an aluminum foil (JIS H4160:1994 A8079H-O) with an MD of 40 mm, TD of 22.5 mm, and thickness of 400 μm was prepared as the metal terminal 2. In addition, each adhesive film 1 obtained in the examples and comparative examples was cut to a length of 45 mm and a width of 20 mm. Next, as shown in the schematic diagram of Figure 9, a metal terminal was sandwiched between two adhesive films to obtain an adhesive film/metal terminal/adhesive film laminate. At this time, the MD and TD of the metal terminal were aligned with the length direction and width direction of the adhesive film, respectively, and the metal terminal and adhesive film were laminated so that their centers were aligned (see Figure 9(a)). In addition, the first resin layer of the adhesive film for the metal terminal was arranged on the metal terminal side. Next, the laminate was sandwiched between two polytetrafluoroethylene films (PTFE films, thickness 100 μm), and heated at a temperature of 200 ° C., a surface pressure of 0.25 MPa, and a time of 16 seconds (once), to heat-seal the first resin layer of the adhesive film to the metal terminal, thereby producing a metal terminal with an adhesive film (see FIG. 9 (b)). At this time, as shown in the schematic diagram of FIG. 9, the metal terminal was sandwiched between the adhesive films, so that the periphery of the metal terminal was covered with the adhesive film, and a portion in which the two adhesive films were heat-sealed to each other was formed. Next, the exterior material was cut to a size of TD 60 mm and MD 200 mm, and as shown in the schematic diagram of FIG. 10, the exterior material was placed facing each other with the heat-sealable resin layer of the exterior material facing inside, and the obtained laminate was sandwiched between the opposing heat-sealable resin layers (see FIG. 10 (a)). At this time, the exterior material was laminated so that the MD and TD of the exterior material were aligned with the width direction and length direction of the laminate, respectively. In this state, a heat seal tester was used to perform heat sealing (see the shaded area S in FIG. 10(b)) under conditions of a width of 7 mm (7 mm in the y-axis direction in FIG. 10(b)), 200°C, surface pressure of 1.0 MPa, and 3.0 seconds, and the laminate was naturally cooled to 25°C to obtain a laminate in which the exterior material and the adhesive film were heat-sealed (see FIG. 10(b)). Next, the central part in the short side direction of the obtained laminate was cut to a width of 15 mm (see the two-dot dashed line in FIG. 10(b) for the cutting position). Next, in an environment of 25°C or 60°C, the adhesive film and the heat-sealable resin layer of the exterior material were peeled off 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 peel strength (N/15 mm) against the exterior material. The peel speed was 20 mm/min, the peel angle was 180°, the chuck distance was 30 mm, and the average value was calculated from three measurements.

The evaluation criteria for adhesive strength in a 25° C. environment and a 60° C. environment are as follows.
(Evaluation criteria for adhesive strength in a 25°C environment)
A: Peel strength is 100 N/15 mm or more B: Peel strength is less than 100 N/15 mm (evaluation criteria for adhesive strength in a 60° C. environment)
A: Peel strength is 80N/15mm or more B: Peel strength is less than 80N/15mm

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 electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
The adhesive film for metal terminal has one surface composed of a resin layer A,
The adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminal, in which the resin layer A is positioned on the surface; and when the adhesive film for metal terminal of the metal terminal with the adhesive film for metal terminal and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminal and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminal and the heat-sealable resin layer.
Item 2. The adhesive film for metal terminal according to item 1, which contains a polyolefin skeleton.
Item 3. The adhesive film for a metal terminal according to item 1 or 2, which has a multilayer structure.
Item 4. The adhesive film for metal terminal according to any one of Items 1 to 3, wherein the adhesive film for 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 side for the electric storage device.
Item 5. The adhesive film for a metal terminal according to Item 4, wherein the second resin layer disposed on the exterior material side for an electricity storage device is the resin layer A.
Item 6. The adhesive film for metal terminal according to any one of items 1 to 5, having a thickness of 100 μm or more.
Item 7. 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 electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
The adhesive film for metal terminal has one surface composed of a resin layer A,
The adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminal, in which the resin layer A is positioned on the surface; and when the adhesive film for metal terminal of the metal terminal with the adhesive film for metal terminal and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminal and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminal and the heat-sealable resin layer.
Item 8. A metal terminal with an adhesive film for a metal terminal, comprising a metal terminal and an adhesive film for a metal terminal attached thereto,
The metal terminal is used so as to be electrically connected to an electrode of an electricity storage device element,
The adhesive film for a metal terminal is used by being interposed between the metal terminal and an exterior material for an electricity storage device that encapsulates the electricity storage device element,
the electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
A metal terminal with an adhesive film for a metal terminal, wherein when a resin layer A constituting the surface of the adhesive film for a metal terminal of the metal terminal with the adhesive film for a metal terminal and the heat-fusible resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-fused under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, at the heat-fused portion between the adhesive film for a metal terminal and the heat-fusible resin layer, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for a metal terminal and the crystalline lamellar thickness B of the heat-fusible resin layer is 0.3 nm or less.
Item 9. 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,
The electrical storage device packaging material is composed of a laminate having at least a base layer, a barrier layer, and a thermally adhesive resin layer in this order,
an adhesive film for a metal terminal is interposed between the metal terminal and the heat-sealable resin layer of the exterior material for an electricity storage device,
The crystalline lamellar thickness B of the heat-fusible resin layer is 5.0 to 9.0 nm,
An electricity storage device, wherein the difference between a crystalline lamellar thickness A measured for a resin layer A constituting one surface of the adhesive film for metal terminals and a crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less.
Item 10. 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, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material, and an adhesive film for metal terminals is interposed between the metal terminals and the electricity storage device exterior material,
The adhesive film for metal terminal is the adhesive film for metal terminal according to any one of items 1 to 6,
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 in this order.
Item 11. 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 6,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material,
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.
Item 12. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the metal terminal with an adhesive film for a metal terminal according to Item 8,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and a metal terminal with the adhesive film for metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the electricity storage device exterior material,
The electrical storage device packaging material is composed of a laminate having at least a base layer, a barrier layer, and a thermally adhesive resin layer in this order,
The kit is used such that, when used, the metal terminal with the adhesive film for a metal terminal is interposed between the heat-sealable resin layers of 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 (12)

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 electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
The adhesive film for metal terminal has one surface composed of a resin layer A,
The adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminal, in which the resin layer A is positioned on the surface; and when the adhesive film for metal terminal of the metal terminal with the adhesive film for metal terminal and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminal and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminal and the heat-sealable resin layer. The adhesive film for metal terminals according to claim 1, which contains a polyolefin skeleton. The adhesive film for metal terminals according to claim 1 or 2, which has a multilayer structure. The adhesive film for metal terminals according to claim 1 or 2, which is composed of a laminate including, in this order, a first resin layer arranged on the metal terminal side, an intermediate layer, and a second resin layer arranged on the exterior material side for the electricity storage device. The adhesive film for metal terminals according to claim 4, wherein the second resin layer arranged on the exterior material side for the electric storage device is the resin layer A. The adhesive film for metal terminals according to claim 1 or 2, having a thickness of 100 μm or more. 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 electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
The adhesive film for metal terminal has one surface composed of a resin layer A,
The adhesive film for metal terminal and the metal terminal are heat-sealed under conditions of a temperature of 200°C, a pressure of 0.25 MPa, and a time of 16 seconds to obtain a metal terminal with an adhesive film for metal terminal, in which the resin layer A is positioned on the surface; and when the adhesive film for metal terminal of the metal terminal with the adhesive film for metal terminal and the heat-sealable resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-sealed under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for metal terminal and the crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less at the heat-sealed portion between the adhesive film for metal terminal and the heat-sealable resin layer. A metal terminal with an adhesive film for a metal terminal, comprising a metal terminal and an adhesive film for a metal terminal attached thereto,
The metal terminal is used so as to be electrically connected to an electrode of an electricity storage device element,
The adhesive film for a metal terminal is used by being interposed between the metal terminal and an exterior material for an electricity storage device that encapsulates the electricity storage device element,
the electrical storage device exterior material includes a thermally adhesive resin layer disposed on an outermost surface on the electrical storage device element side,
A metal terminal with an adhesive film for a metal terminal, wherein when a resin layer A constituting the surface of the adhesive film for a metal terminal of the metal terminal with the adhesive film for a metal terminal and the heat-fusible resin layer having a crystalline lamellar thickness of 5.0 to 9.0 nm are heat-fused under conditions of a temperature of 200°C, a pressure of 1.0 MPa, and a time of 3 seconds, at the heat-fused portion between the adhesive film for a metal terminal and the heat-fusible resin layer, the difference between the crystalline lamellar thickness A of the resin layer A of the adhesive film for a metal terminal and the crystalline lamellar thickness B of the heat-fusible resin layer is 0.3 nm or less. 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,
The electrical storage device packaging material is composed of a laminate having at least a base layer, a barrier layer, and a thermally adhesive resin layer in this order,
an adhesive film for a metal terminal is interposed between the metal terminal and the heat-sealable resin layer of the exterior material for an electricity storage device,
The crystalline lamellar thickness B of the heat-fusible resin layer is 5.0 to 9.0 nm,
An electricity storage device, wherein the difference between a crystalline lamellar thickness A measured for a resin layer A constituting one surface of the adhesive film for metal terminals and a crystalline lamellar thickness B of the heat-sealable resin layer is 0.3 nm or less. 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, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material, and an adhesive film for metal terminals is interposed between the metal terminals and the electricity storage device exterior material,
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 in this order. 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, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material,
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. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the metal terminal with the adhesive film for a metal terminal according to claim 8,
The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and a metal terminal with the adhesive film for metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the electricity storage device exterior material,
The electrical storage device packaging material is composed of a laminate having at least a base layer, a barrier layer, and a thermally adhesive resin layer in this order,
The kit is used such that, when used, the metal terminal with the adhesive film for a metal terminal is interposed between the heat-sealable resin layers of the exterior material for an electricity storage device.