Adhesive film for metal terminals, method for manufacturing adhesive film for metal terminals, metal terminal with adhesive film for metal terminals, energy storage device, and method for manufacturing energy storage device

Abstract

To provide an adhesive film for a metal terminal, which is configured from a laminate comprising an acid-modified polyolefin layer constituting a metal-terminal side surface, and a polyolefin layer constituting a power storage device cladding side surface and which allows the metal-terminal side surface and the power storage device cladding side surface to be easily distinguished.SOLUTION: Provided is an adhesive film for a metal terminal, which is interposed between a metal terminal that is electrically connected to an electrode of a power storage device element and a power storage device cladding that seals the power storage device element. The adhesive film for a metal terminal is configured from a laminate comprising at least an acid-modified polyolefin layer constituting a metal-terminal side surface, and a polyolefin layer constituting a power storage device cladding side surface, and a ratio of RaA (μm) that is the arithmetic surface roughness of the metal-terminal side surface of the acid-modified polyolefin layer to RaB(μm) that is the arithmetic surface roughness of the power storage device cladding side surface of the polyolefin layer satisfies a relationship of RaA / RaB>1.2.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an adhesive film for metal terminals, a method for manufacturing an adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, a power storage device, and a method for manufacturing a power storage device.

Background Art

[0002] Conventionally, various types of power storage devices have been developed. In all power storage devices, an exterior material for the power storage device is an essential member for sealing power storage device elements such as electrodes and electrolytes. Conventionally, a metal exterior material for the power storage device has been frequently used as the exterior material for the power storage device. However, in recent years, with the improvement in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., the power storage device is required to have various shapes, and at the same time, thinning and weight reduction are required. However, the conventionally frequently used metal exterior material for the power storage device has the disadvantages that it is difficult to follow the diversification of shapes and there is also a limit to weight reduction.

[0003] Therefore, in recent years, as an exterior material for the power storage device that can be easily processed into various shapes and can achieve thinning and weight reduction, a laminated sheet in which a base material layer / an adhesive layer / a barrier layer / a heat-sealable resin layer are sequentially laminated has been proposed. When using such a laminated film-shaped exterior material for the power storage device, with the heat-sealable resin layers located in the innermost layer of the exterior material for the power storage device facing each other, the peripheral portion of the exterior material for the power storage device is heat-sealed by heat sealing, whereby the power storage device element is sealed by the exterior material for the power storage device.

[0004] Metal terminals protrude from the heat-sealed portion of the casing material for energy storage devices. The energy storage device element sealed by the casing material is electrically connected to the outside by the metal terminals, which are electrically connected to the electrodes of the energy storage device element. In other words, in the heat-sealed portion of the casing material for energy storage devices, the portion where the metal terminals are present is heat-sealed with the metal terminals sandwiched between heat-fusible resin layers. Since the metal terminals and the heat-fusible resin layer are composed of dissimilar materials, adhesion tends to decrease at the interface between the metal terminals and the heat-fusible resin layer.

[0005] For this reason, an adhesive film is sometimes placed between the metal terminal and the heat-sealable resin layer to improve their adhesion. An example of such an adhesive film is the one described in Patent Document 1. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-79638 [Patent Document 2] Japanese Patent Publication No. 2002-8616 [Overview of the project] [Problems that the invention aims to solve]

[0007] The adhesive film placed between the metal terminal and the heat-sealable resin layer is required to adhere tightly between the exterior material of the energy storage device and the metal terminal, thereby sealing the energy storage device. For example, a particularly high level of sealing is required in energy storage devices used in automobiles.

[0008] Since the heat-sealable resin layer of the exterior material for energy storage devices is generally made of polyolefin, the layer constituting the surface of the adhesive film on the exterior material side for energy storage devices is also made of a polyolefin layer, just like the heat-sealable resin layer, to achieve high adhesion between these layers.

[0009] On the other hand, metal terminals are made of metal and generally do not adhere well to resin, but acid-modified polyolefins have high adhesion to metal. Therefore, by forming the layer constituting the metal terminal side surface of the adhesive film with an acid-modified polyolefin layer, high adhesion is achieved between these layers.

[0010] In other words, in an adhesive film for metal terminals, in order to achieve particularly high adhesion between the exterior material for energy storage devices and the metal terminals, it is desirable that the surface on the exterior material side of the energy storage device be composed of a polyolefin layer, and the surface on the metal terminal side be composed of an acid-modified polyolefin layer.

[0011] However, the polyolefin layer and the acid-modified polyolefin layer of the adhesive film for metal terminals are indistinguishable by appearance. As a result, problems can occur where the adhesive film for metal terminals is not properly positioned to achieve high sealing performance, such as by mistakenly placing the polyolefin layer side of the adhesive film on the metal terminal side.

[0012] Under these circumstances, the primary objective of this disclosure is to provide an adhesive film for metal terminals, comprising a laminate comprising an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for an energy storage device, wherein the metal terminal side surface and the exterior material side surface for an energy storage device can be easily distinguished. Furthermore, this disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with the adhesive film for metal terminals attached, an energy storage device, and a method for manufacturing the energy storage device. [Means for solving the problem]

[0013] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that in an adhesive film for metal terminals composed of a laminate comprising an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for energy storage devices, if the ratio of the arithmetic surface roughness RaA (μm) of the acid-modified polyolefin layer on the metal terminal side surface to the arithmetic surface roughness RaB (μm) of the polyolefin layer on the exterior material side surface for energy storage devices is designed to satisfy the relationship RaA / RaB > 1.2, it is possible to easily distinguish between the metal terminal side surface and the exterior material side surface for energy storage devices. Because the adhesive film for metal terminals of this disclosure makes it easy to distinguish between the metal terminal side surface and the exterior material side surface for energy storage devices, it is possible to appropriately position the adhesive film for metal terminals to exhibit high sealing performance. This disclosure was completed by further studies based on this finding.

[0014] In other words, this disclosure provides inventions in the following embodiments. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. An adhesive film for metal terminals, wherein the ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.2. [Effects of the Invention]

[0015] According to the present disclosure, there is provided an adhesive film for a metal terminal, which is composed of a laminate including an acid-modified polyolefin layer constituting the surface on the metal terminal side and a polyolefin layer constituting the surface on the side of the exterior material for the power storage device, and the surface on the metal terminal side and the surface on the side of the exterior material for the power storage device can be easily distinguished visually. Since the adhesive film for a metal terminal of the present disclosure can easily distinguish the surface on the metal terminal side and the surface on the side of the exterior material for the power storage device, it is possible to appropriately arrange the adhesive film for a metal terminal so that it exhibits high sealing performance. Further, it is also an object of the present disclosure to provide a method for manufacturing the adhesive film for a metal terminal, a metal terminal with the adhesive film for a metal terminal, a power storage device, and a method for manufacturing the power storage device.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic plan view of the power storage device of the present disclosure. [Figure 2] It is a schematic cross-sectional view taken along line A-A' of FIG. 1. [Figure 3] It is a schematic cross-sectional view taken along line B-B' of FIG. 1. [Figure 4] It is a schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [Figure 5] It is a schematic cross-sectional view of the adhesive film for a metal terminal of the present disclosure. [Figure 6] It is a schematic cross-sectional view of the exterior material for the power storage device of the present disclosure. [Figure 7] In the examples, it is a schematic diagram for explaining a method for confirming the generation of bubbles.

Embodiments for Carrying Out the Invention

[0017] The adhesive film for metal terminals of the present disclosure is an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element. The adhesive film for metal terminals is composed of a laminate including at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the power storage device. The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface for the power storage device of the polyolefin layer satisfies the relationship RaA / RaB > 1.2.

[0018] Since the adhesive film for metal terminals of the present disclosure has such characteristics, it is possible to easily distinguish between the metal terminal side surface and the exterior material side surface for the power storage device of the adhesive film for metal terminals by visual inspection.

[0019] Further, the power storage device of the present disclosure is a power storage device including at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for a power storage device that seals the power storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode respectively and protruding outside the exterior material for the power storage device. The adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for the power storage device.

[0020] Hereinafter, the adhesive film for metal terminals of the present disclosure, its manufacturing method, the power storage device, and its manufacturing method will be described in detail.

[0021] In this specification, for numerical ranges, the numerical range indicated by "~" means "above" and "below". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less.

[0022] Another method for confirming the MD (Mass Variability) of adhesive films for metal terminals involves observing a cross-section of the adhesive film (for example, 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 where the average diameter of the island shapes perpendicular to the thickness direction of the adhesive film is maximized can be identified as the MD. Specifically, the sea-island structure is confirmed by observing electron microscope images of each of the following cross-sections (a total of 10 cross-sections): the cross-section in the length direction of the adhesive film for metal terminals, and each cross-section from the direction parallel to the length direction, with angles changed by 10 degrees increments, up to the direction perpendicular to the length direction. Next, the shape of each individual island is observed in each cross-section. For each island shape, the diameter y is defined as the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the adhesive film for metal terminals and the rightmost point perpendicular to that direction. In each cross-section, the average of the top 20 island shapes with the largest diameter y is calculated. The direction parallel to the cross-section where the average of the island's shape's diameter y is largest is determined to be the MD (Mass Distribution). Alternatively, for example, the heat shrinkage rate of an adhesive film for metal terminals can be measured after being left in a 150°C environment for 2 minutes, and the direction with the greater shrinkage rate can be determined to be the MD.

[0023] 1. Adhesive film for metal terminals The adhesive film for metal terminals of this disclosure is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element. Specifically, as shown in Figures 1 to 3, for example, the adhesive film for metal terminals 1 of this disclosure is interposed between a metal terminal 2 electrically connected to the electrodes of an energy storage device element 4 and an outer casing material 3 for an energy storage device that seals the energy storage device element 4. The metal terminal 2 protrudes to the outside of the outer casing material 3 and is sandwiched between the outer casing material 3 and the heat-sealed outer casing material 3 via the adhesive film for metal terminals 1 at the peripheral edge 3a of the outer casing material 3.

[0024] In this disclosure, the preliminary bonding process of the adhesive film for metal terminals to the metal terminals is performed under conditions such as a temperature of approximately 140 to 160°C, a pressure of approximately 0.01 to 1.0 MPa, a time of approximately 3 to 15 seconds, and 3 to 6 times. The main bonding process is performed under conditions such as a temperature of approximately 160 to 240°C, a pressure of approximately 0.01 to 1.0 MPa, a time of approximately 3 to 15 seconds, and 1 to 3 times. Furthermore, when heat sealing a metal terminal with an adhesive film for metal terminals interposed in an outer casing material for an energy storage device, the heating temperature is typically in the range of approximately 180 to 210°C, the pressure is typically approximately 1.0 to 2.0 MPa, the time of approximately 1 to 5 seconds, and 1 time.

[0025] The adhesive film 1 for metal terminals of this disclosure is provided to improve the adhesion between the metal terminals 2 and the exterior material 3 for the energy storage device. By improving the adhesion between the metal terminals 2 and the exterior material 3 for the energy storage device, the sealing performance of the energy storage device element 4 is improved. As described above, when heat sealing the energy storage device element 4, the metal terminals 2 electrically connected to the electrodes of the energy storage device element 4 protrude to the outside of the exterior material 3 for the energy storage device, thereby sealing the energy storage device element. At this time, since the metal terminals 2, which are made of metal, and the heat-fusible resin layer 35 (a layer made of a heat-fusible resin such as polyolefin) located in the innermost layer of the exterior material 3 for the energy storage device are made of different materials, if such an adhesive film is not used, the sealing performance of the energy storage device element tends to be low at the interface between the metal terminals 2 and the heat-fusible resin layer 35.

[0026] As shown in Figure 4, the adhesive film 1 for metal terminals of this disclosure includes a structure in which at least an acid-modified polyolefin layer 11 and a polyolefin layer 12 are laminated. The acid-modified polyolefin layer 11 is positioned on the metal terminal 2 side. The polyolefin layer 12 is positioned on the exterior material 3 side for the energy storage device. In the adhesive film 1 for metal terminals of this disclosure, the acid-modified polyolefin layer 11 and the polyolefin layer 12 are located on the surfaces of both sides, respectively. The acid-modified polyolefin layer 11, the intermediate layer 13, and the polyolefin layer 12 may each be single layers or multi-layer layers. Furthermore, the acid-modified polyolefin layer 11, the intermediate layer 13, and the polyolefin layer 12 may each contain a coloring agent. If the acid-modified polyolefin layer 11, the intermediate layer 13, and the polyolefin layer 12 are multi-layer layers, at least one layer may contain a coloring agent. Furthermore, in the pre-sealing process in which the adhesive film 1 for metal terminals is welded to the metal terminals, the heat generated during pre-sealing can cause the coloring agent in the innermost layer (the layer welded to the metal terminals) to leak out, making it difficult to control the welding position using positioning sensors or the like. This is especially likely to occur when the process includes a step of preheating the metal terminals. By making the layer to which the coloring agent is added in the adhesive film 1 for metal terminals an inner layer of the adhesive film 1 for metal terminals, the leakage of the coloring agent is suppressed, and the control of the welding position becomes easier.

[0027] From the viewpoint of more favorably achieving the effects of the present invention, it is preferable that an intermediate layer 13 is laminated between the acid-modified polyolefin layer 11 and the polyolefin layer 12, as shown in Figure 5. Furthermore, it is preferable that the acid-modified polyolefin layer 11 and the intermediate layer 13 are in contact with each other, and that the polyolefin layer 12 and the intermediate layer 13 are in contact with each other.

[0028] In the adhesive film 1 for metal terminals of this disclosure, the acid-modified polyolefin layer 11 and the polyolefin layer 12 are each layers containing a polyolefin resin. The acid-modified polyolefin layer 11 contains an acid-modified polyolefin among polyolefin resins, and is more preferably a layer formed of an acid-modified polyolefin. Furthermore, the polyolefin layer 12 contains a polyolefin among polyolefin resins, and is even more preferably a layer formed of a polyolefin.

[0029] Furthermore, the intermediate layer 13 preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains polyolefin, and more preferably is a layer formed of polyolefin.

[0030] In the acid-modified polyolefin layer 11, the polyolefin layer 12, and the optional intermediate layer 13, the polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene. The polyolefin and acid-modified polyolefin may each contain known additives, pigments, fillers, etc., as described later.

[0031] Specific examples of preferred lamination configurations for the adhesive film 1 for metal terminals of this disclosure include a two-layer configuration in which an acid-modified polyolefin layer formed from acid-modified polypropylene and a polyolefin layer formed from polypropylene are laminated; and a three-layer configuration in which an acid-modified polyolefin layer formed from acid-modified polypropylene, an intermediate layer formed from polypropylene, and a polyolefin layer formed from polypropylene are laminated in this order. Among these, the three-layer configuration is particularly preferred from the viewpoint of adhesion between the heat-fusible resin layer 35 of the exterior material 3 for energy storage devices and the polyolefin layer 12.

[0032] Details of the acid-modified polyolefin layer 11, the polyolefin layer 12, and the intermediate layer 13, which may be provided as needed, will be described later.

[0033] When the adhesive film 1 for metal terminals of this disclosure is placed between the metal terminals 2 of the energy storage device 10 and the exterior material 3 for the energy storage device, the surface of the metal terminals 2, which are made of metal, and the heat-fusible resin layer 35 (a layer formed of a heat-fusible resin such as polyolefin) of the exterior material 3 for the energy storage device are bonded together via the adhesive film 1. The acid-modified polyolefin layer 11 of the adhesive film 1 for metal terminals is positioned on the metal terminal 2 side, and the polyolefin layer 12 is positioned on the exterior material 3 side for the energy storage device, with the acid-modified polyolefin layer 11 in close contact with the metal terminals 2 and the polyolefin layer 12 in close contact with the heat-fusible resin layer 35 of the exterior material 3 for the energy storage device.

[0034] The thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals of this disclosure is, for example, about 50 μm or more, preferably about 60 μm or more, more preferably about 80 μm or more, even more preferably about 100 μm or more, and particularly preferably about 120 μm or more. Furthermore, the total thickness of the adhesive film 1 for metal terminals of this disclosure is preferably about 500 μm or less, more preferably about 300 μm or less, even more preferably about 250 μm or less, even more preferably about 200 μm or less, and even more preferably about 180 μm or less. The preferred total thickness range for the adhesive film 1 for metal terminals of this disclosure is approximately 50-500 μm, 50-300 μm, 50-250 μm, 50-200 μm, 50-180 μm, 60-500 μm, 60-300 μm, 60-250 μm, 60-200 μm, 60-180 μm, 80-500 μm, and 80-300 μm. Examples of thicknesses include approximately 80-250 μm, 80-200 μm, 80-180 μm, 100-500 μm, 100-300 μm, 100-250 μm, 100-200 μm, 100-180 μm, 120-500 μm, 120-300 μm, 120-250 μm, 120-200 μm, and 120-180 μm. In particular, by having a total thickness of 120 μm or more for the laminate constituting the adhesive film 1 for metal terminals, sufficient thickness of the adhesive film 1 for metal terminals is ensured, and the formation of air bubbles at the interface between the adhesive film and the metal terminals can be effectively suppressed.

[0035] The following details the materials, thicknesses, etc., that constitute the acid-modified polyolefin layer 11, the polyolefin layer 12, and the intermediate layer 13.

[0036] [Acid-modified polyolefin layer 11 and polyolefin layer 12] As shown in Figures 4 and 5, the adhesive film 1 for metal terminals of this disclosure comprises an acid-modified polyolefin layer 11 on one side and a polyolefin layer 12 on the other side. The acid-modified polyolefin layer 11 is positioned on the metal terminal 2 side. The polyolefin layer 12 is positioned on the exterior material 3 side for the energy storage device. In the adhesive film 1 for metal terminals of this disclosure, the acid-modified polyolefin layer 11 and the polyolefin layer 12 are located on the surfaces of both sides, respectively.

[0037] In this disclosure, the ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer 11 to the arithmetic surface roughness RaB (μm) of the polyolefin layer 12 on the exterior material side for energy storage devices satisfies the relationship RaA / RaB > 1.2. This relationship allows for easy distinction between the metal terminal side surface and the exterior material side surface of the energy storage device in the exterior material 3 of this disclosure. The arithmetic surface roughness RaA (μm) of the acid-modified polyolefin layer 11 and the arithmetic surface roughness RaB (μm) of the polyolefin layer 12 can be adjusted by pressing the resin against a cooling roll with a finely textured surface during the cooling and solidification process after melt extrusion, thereby transferring the surface shape. That is, the surface roughness can be adjusted to satisfy the aforementioned relationship depending on the surface roughness of each cooling roll. Furthermore, adjustment can also be made using a technique known as chemical embossing. Chemical embossing is a technique that creates a textured surface by blending resins with different melting points and shrinkage rates, forming a film, and utilizing the fine phase separation that occurs during cooling and solidification. The texture can also be adjusted by adding foaming agents or large inorganic fillers.

[0038] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, a large RaA / RaB ratio is desirable, preferably about 1.5 or more, and more preferably about 2.0 or more. The upper limit of this ratio is, for example, about 5.0. Preferred ranges for this ratio include about 1.2 to 5.0, about 1.5 to 5.0, and about 2.0 to 5.0.

[0039] In this disclosure, there are no particular limitations on the method for satisfying the relationship RaA / RaB > 1.2 in the ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer 11 to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer 12 for energy storage devices. However, as described above, for example, when forming the acid-modified polyolefin layer 11 and the polyolefin layer 12 by melt extrusion molding, a cooling roll having a predetermined surface roughness can be used, and the surface of the cooling roll can be pressed against the surfaces of the acid-modified polyolefin layer 11 and the polyolefin layer 12 to form the acid-modified polyolefin layer 11 and the polyolefin layer 12. In this case, the cooling roll used to form the acid-modified polyolefin layer 11 and the cooling roll used to form the polyolefin layer 12 have different surface shapes.

[0040] The reason for making the arithmetic surface roughness RaA of the metal terminal side surface of the acid-modified polyolefin layer 11 greater than the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer 12 for energy storage devices is to make it easier to peel off the acid-modified polyolefin layer 11 from the cooling roll during the manufacturing process. In other words, when the acid-modified polyolefin is melt-extruded and nipped by a cooling roll (metal roll), the acid-modified polyolefin has adhesion to the metal, making it difficult for the acid-modified polyolefin layer 11 to peel off the cooling roll. Therefore, by increasing the arithmetic surface roughness RaA of the metal terminal side surface of the acid-modified polyolefin layer 11 (i.e., reducing the contact area of ​​the metal terminal side surface of the acid-modified polyolefin layer 11 with the cooling roll), the acid-modified polyolefin layer 11 is made easier to peel off from the cooling roll. In addition, having an appropriate surface roughness can suppress the formation of air bubbles at the interface between the adhesive film for metal terminals and the metal terminals when the adhesive film for metal terminals is heat-fused to the metal terminals. The formation of air bubbles can lead to problems such as reduced seal strength, electrolyte retention, and cosmetic defects.

[0041] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer 11 is preferably about 15 μm or less, more preferably about 5 μm or less, even more preferably about 1.0 μm or less, and also preferably about 0.4 μm or more, more preferably about 0.5 μm, even more preferably about 0.7 μm or more. Preferred ranges include about 0.4 to 15 μm, about 0.4 to 5 μm, about 0.4 to 1.0 μm, about 0.5 to 15 μm, about 0.5 to 5 μm, about 0.5 to 1.0 μm, about 0.7 to 15 μm, about 0.7 to 5 μm, and about 0.7 to 1.0 μm. When the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer 11 is 0.4 μm or more, the coefficient of dynamic friction of the metal terminal side surface of the acid-modified polyolefin layer 11 tends to be small. Furthermore, because RaA is 0.4 μm or more, friction on the surface of the acid-modified polyolefin layer 11 can be reduced without adding a lubricant, so the acid-modified polyolefin layer 11 follows the shape of the metal terminal, reducing the likelihood of air bubbles remaining. In addition, it also acts as a passage for air to escape when the acid-modified polyolefin layer 11 comes into contact with the metal terminal surface, which tends to reduce the likelihood of air bubbles remaining. Adding a lubricant to the acid-modified polyolefin layer 11 is undesirable because the lubricant may bleed onto the surface of the acid-modified polyolefin layer 11, potentially adversely affecting the seal between the acid-modified polyolefin layer 11 and the metal terminal. Moreover, when RaA (μm) is 15 μm or less, the formation of air bubbles at the interface between the adhesive film for metal terminals and the metal terminals can be effectively suppressed. The arithmetic surface roughness RaB (μm) of the polyolefin layer 12 on the exterior material side for energy storage devices is preferably about 0.6 μm or less, more preferably about 0.4 μm or less, and also preferably about 0.1 μm or more, more preferably about 0.3 μm or more. Preferred ranges include about 0.1 to 0.6 μm, about 0.1 to 0.4 μm, about 0.3 to 0.6 μm, and about 0.3 to 0.4 μm. By having an arithmetic surface roughness RaB (μm) of 0.1 μm or more on the exterior material side for energy storage devices for polyolefin layer 12, the slipperiness of the polyolefin layer 12 immediately after film formation can be improved.A RaB (μm) of 0.6 μm or less makes it easier to distinguish between the metal terminal surface and the exterior material surface for the energy storage device. The measurement methods for the arithmetic surface roughness RaA and RaB are as follows.

[0042] <Arithmetic surface roughness Ra> For adhesive films for metal terminals, the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer and the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for energy storage devices are measured using a commercially available optical surface texture analyzer (New View 7300, manufactured by Zygo).

[0043] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the glossiness GuA(GU) measured at an incident angle of 60° on the metal terminal side surface of the acid-modified polyolefin layer 11 is preferably about 1 GU or more, more preferably about 5 GU or more, and also preferably about 15 GU or less, more preferably about 10 GU or less, with preferred ranges including about 1 to 15 GU, about 1 to 10 GU, about 5 to 15 GU, and about 5 to 10 GU. Furthermore, the glossiness GuB(GU) measured at an incident angle of 60° on the exterior material side surface of the polyolefin layer 12 for energy storage devices is preferably about 15 GU or more, more preferably about 30 GU or more, and also preferably about 100 GU or less, more preferably about 80 GU or less, with preferred ranges including about 15 to 100 GU, about 15 to 80 GU, about 30 to 100 GU, and about 30 to 80 GU. The gloss levels GuA of the acid-modified polyolefin layer 11 and GuB of the polyolefin layer 12 can be formed by pressing the resin against a cooling roll with a finely textured surface during the cooling and solidification process after melt extrusion, thereby transferring the surface shape. In other words, the gloss levels can be adjusted by the surface roughness of each cooling roll. The method for measuring the gloss levels GuA and GuB is as follows.

[0044] <Glossiness (GU value)> In accordance with JIS Z 8741:1997, a commercially available gloss meter was used to measure gloss at a 60° angle of incident light on the metal terminal side surface of the adhesive film for metal terminals or the exterior material side surface of the energy storage device. The observed Gu value was defined as the gloss level. The average value of n=5 measurements was used.

[0045] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the coefficient of dynamic friction μA measured on the metal terminal side surface of the acid-modified polyolefin layer 11 in accordance with the provisions of JIS K7125:1999 8.1 film to film is preferably about 0.1 or more, more preferably about 0.2 or more, and also preferably about 0.7 or less, more preferably about 0.5 or less, with a preferred range of about 0.1 to 0.7, about 0.1 to 0.5, about 0.2 to 0.7, and about 0.2 to 0.5. Furthermore, the dynamic friction coefficient μB of the polyolefin layer 12 on the exterior material side for energy storage devices, measured in accordance with the provisions of JIS K7125:1999 8.1 film to film, is preferably about 0.1 or more, more preferably about 0.2 or more, and also preferably about 0.7 or less, more preferably about 0.5 or less, with a preferred range of approximately 0.1 to 0.7, 0.1 to 0.5, 0.2 to 0.7, and 0.2 to 0.5. The dynamic friction coefficients μA of the acid-modified polyolefin layer 11 and μB of the polyolefin layer 12 can be formed by pressing the resin against a cooling roll with a finely textured surface during the cooling and solidification process after melt extrusion, and transferring the surface shape, or by adjusting with a lubricant. That is, they can be adjusted by the surface roughness of each cooling roll and the use of a lubricant. The methods for measuring the dynamic friction coefficients μA and μB are as follows.

[0046] <Coefficient of Dynamic Friction> A friction test will be conducted according to the method specified in JIS K7125:1999, 8.1, for film-to-film measurement. First, two samples of the exterior material for energy storage devices will be cut out, each measuring 80 mm in the TD direction and 200 mm in the MD direction. Next, to measure the coefficient of dynamic friction μA of the metal terminal side surface of the acid-modified polyolefin layer, the samples will be stacked so that the metal terminal side surfaces of the acid-modified polyolefin layers face each other, and a sliding piece will be placed on top. Rubber will be attached to the bottom surface of the sliding piece, and the total mass of the sliding piece will be 200 g, ensuring that the sample and the sliding piece are in close contact and do not slip. Next, the sliding piece will be pulled at a speed of 100 mm / min, and the dynamic friction force (N) between the two samples will be measured. The coefficient of dynamic friction μA will be calculated by dividing the dynamic friction force by the normal force of the sliding piece (1.96 N). The coefficient of dynamic friction μB of the exterior material side surface of the polyolefin layer for energy storage devices will be calculated by stacking the samples so that the exterior material side surfaces of the polyolefin layer face each other and conducting the test. The coefficient of kinetic friction is determined by ignoring the peak of static friction and using the average value up to the first 30 mm after the relative shearing motion between the contact surfaces begins. The load cell is directly connected to the sliding piece.

[0047] In the adhesive film 1 for metal terminals of this disclosure, the acid-modified polyolefin layer 11 and the polyolefin layer 12 are each layers containing a polyolefin resin. The acid-modified polyolefin layer 11 preferably contains an acid-modified polyolefin among polyolefin resins and is formed of an acid-modified polyolefin. Similarly, the polyolefin layer 12 preferably contains a polyolefin among polyolefin resins and is formed of a polyolefin. Acid-modified polyolefins have significantly higher affinity with metals than polyolefins, but their affinity with polyolefins is generally somewhat inferior to the affinity between polyolefins. Therefore, in the adhesive film 1 for metal terminals of this disclosure, by arranging the acid-modified polyolefin layer 11 on the metal terminal 2 side, excellent adhesion can be achieved at the interface between the adhesive film 1 for metal terminals and the metal terminal 2. Furthermore, by arranging the polyolefin layer 12 on the heat-fusible resin layer 35 side of the exterior material 3 for energy storage devices, even better adhesion can be achieved at the interface between the adhesive film 1 for metal terminals and the heat-fusible resin layer 35.

[0048] Specific examples of preferred lamination configurations of the adhesive film 1 for metal terminals of this disclosure include a two-layer configuration in which an acid-modified polyolefin layer formed from acid-modified polypropylene and a polyolefin layer formed from polypropylene are laminated; and a three-layer configuration in which an acid-modified polyolefin layer formed from acid-modified polypropylene, an intermediate layer formed from polypropylene, and a polyolefin layer formed from polypropylene are laminated in this order. Among these, the three-layer configuration is particularly preferred.

[0049] The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably it is a polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride.

[0050] In the acid-modified polyolefin layer 11 and the polyolefin layer 12, the polyolefin (in the case of the acid-modified polyolefin layer 11, the polyolefin that is acid-modified) can be polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, etc.; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene, random copolymer of propylene and butene, etc.); and ethylene-butene-propylene terpolymer, etc. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is particularly preferred. Among polypropylene, random polypropylene (i.e., random copolymer of polypropylene (e.g., random copolymer of propylene and ethylene)) is preferred. For example, in the case of the acid-modified polyolefin layer 11, it is preferable to include acid-modified random polypropylene, and more preferably to be formed of acid-modified random polypropylene. Similarly, in the case of the polyolefin layer 12, it is preferable to include random polypropylene, and more preferably to be formed of random polypropylene.

[0051] Furthermore, the polyolefin may 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 polymerization or graft polymerization of an α,β-unsaturated carboxylic acid or its anhydride to a cyclic polyolefin.

[0052] Cyclic polyolefins are copolymers of olefins and cyclic monomers. Examples of olefins that are constituent monomers of cyclic polyolefins include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of cyclic polyolefins 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 can also be used as a constituent monomer.

[0053] Examples of carboxylic acids or their anhydrides used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When the acid-modified polyolefin layer 11 is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. In other words, when the acid-modified polyolefin layer 11 is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0054] The acid-modified polyolefin layer 11 and the polyolefin layer 12 may each be formed from a single resin component, or from a blended polymer combining two or more resin components. Furthermore, the acid-modified polyolefin layer 11 and the polyolefin layer 12 may each be formed as a single layer, or as two or more layers made from the same or different resin components. From the viewpoint of film-forming properties of the acid-modified polyolefin layer 11 and the polyolefin layer 12, it is preferable that these layers each be formed from a blended polymer combining two or more resin components. When a blended polymer is used, for the acid-modified polyolefin layer 11, it is preferable that acid-modified polypropylene be the main component (50% by mass or more of the component) and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). Similarly, for the polyolefin layer 12, it is preferable that polypropylene be the main component (50% by mass or more of the component) 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 acid-modified polyolefin layer 11 and the polyolefin layer 12, it is preferable that the acid-modified polyolefin layer 11 contains acid-modified polypropylene alone as the resin, and it is preferable that the polyolefin layer 12 contains polypropylene alone as the resin.

[0055] From the viewpoint of further improving the sealing performance of energy storage devices, in this disclosure, it is preferable that the resin forming the heat-fusible resin layer of the exterior material for energy storage devices is the same type as the resin forming the polyolefin layer 12. More specifically, the resins forming the heat-fusible resin layer 35 and the polyolefin layer 12 are preferably polyolefin, more preferably polypropylene, and even more preferably random polypropylene, respectively. This particularly enhances the adhesion between the heat-fusible resin layer 35 and the polyolefin layer 12.

[0056] Furthermore, the acid-modified polyolefin layer 11 and the polyolefin layer 12 may each contain colorants such as pigments as needed. Various inorganic pigments can be used as pigments. Preferably, the pigment is at least one of a white pigment and a black pigment. Specific examples of pigments include black pigments such as carbon (carbon, graphite) and titanium nitride, as exemplified in the fillers described later, and white pigments such as titanium oxide. Carbon (carbon, graphite) is a material generally used inside energy storage devices and does not leach into the electrolyte, so it can be suitably incorporated into the acid-modified polyolefin layer 11 located on the metal terminal side. In addition, a sufficient coloring effect can be obtained with an amount that has a large coloring effect without hindering adhesion, and it does not melt with heat, thus increasing the apparent melt viscosity of the added resin. Furthermore, it prevents the pressurized part from becoming thin during heat bonding (heat sealing), providing excellent sealing between the exterior material for the energy storage device and the metal terminal.

[0057] For example, the pigment content in the pigment-containing layer can be approximately 0.05 to 5.00% by mass. When the acid-modified polyolefin layer 11 and the polyolefin layer 12 contain pigment, their respective pigment content can be approximately 0.05 to 5.00% by mass. By adding the pigment to only one of the acid-modified polyolefin layer 11 and the polyolefin layer 12 (preferably only the acid-modified polyolefin layer 11), it becomes easier to distinguish between the metal terminal side surface and the exterior material side surface for the energy storage device. When both the pigment and filler are added to the exterior material 3 for the energy storage device, the filler and pigment may be added to the same acid-modified polyolefin layer 11 or polyolefin layer 12. However, from the viewpoint of not hindering the heat-sealing properties of the adhesive film 1 for the metal terminal, it is preferable to add the filler and pigment separately to the acid-modified polyolefin layer 11 and the polyolefin layer 12.

[0058] The acid-modified polyolefin layer 11 and the polyolefin layer 12 may each contain a filler as needed. The inclusion of a filler in the acid-modified polyolefin layer 11 and the polyolefin layer 12 allows the filler to function as a spacer, effectively suppressing short circuits between the metal terminal 2 and the barrier layer 33 of the energy storage device exterior material 3. The particle size of the filler can range from approximately 0.1 to 35 μm, preferably 5.0 to 30 μm, and more preferably 10 to 25 μm. The filler content can be approximately 5 to 30 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the resin component forming the acid-modified polyolefin layer 11 and the polyolefin layer 12.

[0059] 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, and calcium carbonate. Examples of organic fillers include fluororesins, phenolic resins, urea resins, epoxy resins, acrylic resins, benzoguanamine-formaldehyde condensates, melamine-formaldehyde condensates, polymethyl methacrylate crosslinked products, and polyethylene crosslinked products. From the viewpoint of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, and among these, spherical aluminum oxide and silica are particularly preferred. As for the method of mixing the filler into the resin components that form the acid-modified polyolefin layer 11 and the polyolefin layer 12, methods such as melt-blending the two in advance using a Banbury mixer or the like to create a masterbatch and then mixing it in a predetermined ratio can be employed, or a direct mixing method with the resin components can be employed.

[0060] From the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the acid-modified polyolefin layer 11 and the polyolefin layer 12 is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, and also preferably 120 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, even more preferably about 60 μm or less, even more preferably about 55 μm or less, and even more preferably 50 μm or less. Preferred thickness ranges for the acid-modified polyolefin layer 11 and the polyolefin layer 12 include approximately 10-120 μm, 10-100 μm, 10-80 μm, 10-60 μm, 10-55 μm, 10-50 μm, 15-120 μm, 15-100 μm, 15-80 μm, 15-60 μm, 15-55 μm, 15-50 μm, 20-120 μm, 20-100 μm, 20-80 μm, 20-60 μm, 20-55 μm, and 20-50 μm, respectively. As a more specific example, when the adhesive film 1 for metal terminals of this disclosure is used in consumer energy storage devices, the thickness of the acid-modified polyolefin layer 11 and the polyolefin layer 12 is preferably about 10 to 30 μm each, and when used in automotive energy storage devices, it is preferably about 30 to 120 μm each.

[0061] The thickness of the acid-modified polyolefin layer 11 is preferably greater than the thickness of the polyolefin layer 12. That is, it is preferable to satisfy the relationship: thickness of the acid-modified polyolefin layer > thickness of the polyolefin layer. Satisfying this relationship makes it easier to fill the area around the metal terminal with the acid-modified polyolefin layer, thereby improving the sealing and insulation properties around the metal terminal. On the other hand, if the relationship: thickness of the acid-modified polyolefin layer < thickness of the polyolefin layer is satisfied, the sealing strength between the polyolefin layer and the exterior material for the energy storage device is increased, thereby improving the sealing and impact resistance of the exterior material for the energy storage device.

[0062] From the viewpoint of improving the sealing performance of the energy storage device of this disclosure, it is preferable that at least one of the acid-modified polyolefin layer 11 and the polyolefin layer 12 contains a lubricant. The concentration of the lubricant is preferably 1500 ppm or less, more preferably 1000 ppm or less, and also preferably 200 ppm or more, more preferably 500 ppm or more, with preferred ranges being approximately 200 to 1500 ppm, approximately 200 to 1000 ppm, approximately 500 to 1500 ppm, and approximately 500 to 1000 ppm.

[0063] The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide. The lubricant may be used alone or in combination of two or more types.

[0064] [Middle class 13] In the adhesive film 1 for metal terminals, the intermediate layer 13 is a layer that functions as a support for the adhesive film 1 for metal terminals and is provided as needed.

[0065] The material forming the intermediate layer 13 is not particularly limited. Examples of materials for forming the intermediate layer 13 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicon resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof, among which polyolefin resins are particularly preferred. In other words, the material forming the intermediate layer 13 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. The presence of a polyolefin skeleton in the resin constituting the intermediate layer 13 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry.

[0066] As described above, the intermediate layer 13 preferably contains a polyolefin resin, 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 it is preferably an unstretched polyolefin film. Specifically, examples of polyolefins 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 copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymer. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is more preferred. Furthermore, polypropylene may be either a homopolymer (homotype polypropylene) or a copolymer, and if it is a copolymer, it may be either random polypropylene or block polypropylene, or a terpolymer. Furthermore, from the viewpoint of excellent electrolyte resistance and heat shrinkage, the intermediate layer 13 preferably contains homopolypropylene, more preferably is formed of homopolypropylene, and even more preferably is an unstretched homopolypropylene film.

[0067] Specifically, examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; 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 polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and copolymers thereof. These polyamides may be used individually or in combination of two or more.

[0068] Specifically, examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters with ethylene terephthalate as the main repeating unit, and copolymer polyesters with butylene terephthalate as the main repeating unit. Furthermore, specific examples of copolymer polyesters with ethylene terephthalate as the main repeating unit include copolymer polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (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). Furthermore, specific examples of copolymer polyesters with butylene terephthalate as the main repeating unit include copolymer polyesters polymerized with butylene isophthalate using butylene terephthalate as the main repeating unit (hereinafter abbreviated as polybutylene(terephthalate / isophthalate)), polybutylene(terephthalate / adipate), polybutylene(terephthalate / sebacate), polybutylene(terephthalate / decanedicarboxylate), and polybutylene naphthalate. These polyesters may be used individually or in combination of two or more types.

[0069] Furthermore, the intermediate layer 13 may be formed from a nonwoven fabric made of the above-mentioned resin. When the intermediate layer 13 is a nonwoven fabric, it is preferable that the intermediate layer 13 is made of the aforementioned polyolefin resin, polyamide resin, etc.

[0070] The intermediate layer 13 may be a single layer or a multi-layer layer. A specific example of a multi-layer layer is a three-layer structure in which block polypropylene / homopolypropylene / block polypropylene are laminated in that order.

[0071] Furthermore, by incorporating a coloring agent into the intermediate layer 13, the intermediate layer 13 can be made into a layer containing a coloring agent. Examples of coloring agents include those exemplified in the acid-modified polyolefin layer 11 and the polyolefin layer 12. It is also possible to adjust the light transmittance by selecting a resin with low transparency. If the intermediate layer 13 is a film, a colored film or a film with low transparency can be used. If the intermediate layer 13 is a nonwoven fabric, a nonwoven fabric using fibers or binders containing a coloring agent, or a nonwoven fabric with low transparency can be used. If the intermediate layer 13 contains a pigment, its content can be, for example, about 0.05 to 5.00% by mass.

[0072] If the intermediate layer 13 is made of a resin film, the surface of the intermediate layer 13 may be subjected to known easy-adhesion methods such as corona discharge treatment, ozone treatment, or plasma treatment, as needed.

[0073] From the viewpoint of more favorably achieving the effects of this disclosure, the thickness of the intermediate layer 13 is preferably 120 μm or less, more preferably 110 μm or less, even more preferably about 100 μm or less, and even more preferably about 90 μm or less. Also, the thickness of the intermediate layer 13 is preferably about 20 μm or more, more preferably about 30 μm or more, and even more preferably about 40 μm or more. Preferred ranges for the thickness of the intermediate layer 13 include about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 20 to 90 μm, about 30 to 120 μm, about 30 to 110 μm, about 30 to 100 μm, about 30 to 90 μm, about 40 to 120 μm, about 40 to 110 μm, about 40 to 100 μm, and about 40 to 90 μm.

[0074] From the viewpoint of improving the sealing performance of the energy storage device of this disclosure, if the adhesive film 1 for metal terminals has an intermediate layer 13, it is preferable that the relationship between the thickness of the intermediate layer 13 > the thickness of the acid-modified polyolefin layer 11 > the thickness of the polyolefin layer 12 is satisfied.

[0075] From the viewpoint of improving the sealing performance of the energy storage device of this disclosure, when the adhesive film 1 for metal terminals has an intermediate layer, the ratio of the thickness of the intermediate layer 13 to the total thickness of the acid-modified polyolefin layer 11 and the polyolefin layer 12 is preferably about 0.2 or more, more preferably about 0.3 or more, and also preferably about 2.0 or less, more preferably about 0.8 or less. Preferred ranges include about 0.2 to 2.0, about 0.2 to 0.8, about 0.3 to 2.0, and about 0.3 to 0.8.

[0076] Furthermore, from the viewpoint of improving the sealing performance of the energy storage device of this disclosure, if the adhesive film 1 for metal terminals has an intermediate layer, and the total thickness of the adhesive film 1 for metal terminals is 100%, then the ratio of the total thickness of the acid-modified polyolefin layer 11 and the polyolefin layer 12 is preferably about 30 to 90%, more preferably about 50 to 80%.

[0077] The adhesive film 1 for metal terminals of this disclosure can be manufactured, for example, by laminating an acid-modified polyolefin layer 11 and a polyolefin layer 12 on both surfaces of an intermediate layer 13, respectively. The lamination of the intermediate layer 13 with the acid-modified polyolefin layer 11 and the polyolefin layer 12 can be carried out by known methods such as extrusion lamination, T-die lamination, inflation lamination, and thermal lamination.

[0078] There are no particular limitations on the method of interposing the adhesive film 1 for metal terminals between the metal terminals 2 and the outer casing material 3 for the energy storage device. For example, as shown in Figures 1 to 3, the adhesive film 1 for metal terminals may be wrapped around the metal terminals 2 in the portion where the metal terminals 2 are sandwiched by the outer casing material 3 for the energy storage device. Although not shown in the figures, the adhesive film 1 for metal terminals may also be placed on both sides of the metal terminals 2 so as to cross both metal terminals 2 in the portion where the metal terminals 2 are sandwiched by the outer casing material 3 for the energy storage device.

[0079] [Metal terminal 2] The adhesive film 1 for metal terminals of this disclosure is used interposed between a metal terminal 2 and an outer casing material 3 for an energy storage device. The metal terminal 2 (tab) is a conductive member electrically connected to the electrode (positive or negative electrode) of an energy storage device element 4, and is made of a metallic material. The metallic material constituting the metal terminal 2 is not particularly limited and includes, for example, aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium-ion energy storage device is usually made of aluminum or the like. Also, the metal terminal 2 connected to the negative electrode of a lithium-ion energy storage device is usually made of copper, nickel, or the like.

[0080] From the viewpoint of improving electrolyte resistance, it is preferable that the surface of the metal terminal 2 be subjected to a chemical conversion treatment. For example, when the metal terminal 2 is made of aluminum, specific examples of chemical conversion treatment include known methods for forming corrosion-resistant coatings such as phosphates, chromates, fluorides, and triazinethiol compounds. Among the methods for forming corrosion-resistant coatings, phosphate chromate treatment using a material composed of three components: phenolic resin, chromium(III) fluoride compound, and phosphoric acid is preferred.

[0081] The size of the metal terminal 2 can be appropriately set according to the size of the energy storage device 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.

[0082] [Exterior material for energy storage devices 3] An example of an exterior material 3 for an energy storage device is one having a laminated structure consisting of a base layer 31, a barrier layer 33, and a heat-fusible resin layer 35 in that order. Figure 6 shows an example of the cross-sectional structure of the exterior material 3 for an energy storage device, in which the base layer 31, an adhesive layer 32 (if necessary), a barrier layer 33, an adhesive layer 34 (if necessary), and a heat-fusible resin layer 35 are laminated in that order. In the exterior material 3 for an energy storage device, the base layer 31 is the outer layer, and the heat-fusible resin layer 35 is the innermost layer. When assembling the energy storage device, the heat-fusible resin layers 35 located around the periphery of the energy storage device element 4 are brought into contact and heat-fused to seal the energy storage device element 4, thereby sealing the energy storage device element 4. Figures 1 to 3 show an energy storage device 10 using an embossed type exterior material 3 for an energy storage device formed by embossing, but the exterior material 3 for an energy storage device may be an unformed pouch type. Note that pouch-type packaging includes three-sided seal, four-sided seal, and pillow-type packaging, but any type is acceptable.

[0083] The thickness of the laminate constituting the outer casing material 3 for the energy storage device is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, the upper limit is preferably 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 outer casing material 3 for the energy storage device, which is to protect the energy 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. A preferred range is, 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 approximately m, 60-160 μm, 60-155 μm, 60-140 μm, 60-130 μm, 60-120 μm, 80-190 μm, 80-180 μm, 80-160 μm, 80-155 μm, 80-140 μm, 80-130 μm, and 80-120 μm.

[0084] (Base material layer 31) In the exterior material 3 for the energy storage device, the base layer 31 is a layer that functions as the base material for the exterior material of the energy storage device and is the layer that forms the outermost layer.

[0085] The material forming the base layer 31 is not particularly limited, as long as it possesses insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have excellent electrolyte resistance and are less prone to whitening when exposed to electrolyte, making them suitable for use as a material for forming the base layer 31. Polyamide films also have excellent stretchability, which can prevent whitening due to resin cracking of the base layer 31 during molding, making them suitable for use as a material for forming the base layer 31.

[0086] The base layer 31 may be formed from a uniaxially or biaxially stretched resin film, or from an unstretched resin film. Among these, uniaxially or biaxially stretched resin films, and especially biaxially stretched resin films, are suitable for use as the base layer 31 because their heat resistance is improved by oriented crystallization.

[0087] Among these, the resin film forming the base layer 31 is preferably nylon, polyester, and more preferably biaxially oriented nylon and biaxially oriented polyester.

[0088] The base layer 31 can also be constructed by laminating resin films of different materials to improve pinhole resistance and insulation when used as packaging for energy storage devices. Specifically, examples include a multilayer structure in which polyester film and nylon film are laminated, or a multilayer structure in which biaxially oriented polyester and biaxially oriented nylon are laminated. When the base layer 31 is made into a multilayer structure, each resin film may be bonded via an adhesive, or it may be laminated directly without an adhesive. When bonding without an adhesive, examples include bonding in a thermally fused state such as co-extrusion, sand lamination, or thermal lamination.

[0089] Furthermore, the base layer 31 may be made friction-reducing to improve moldability. When the base layer 31 is made friction-reducing, there are no particular restrictions on the coefficient of friction of its surface, but for example, it may be 1.0 or less. Examples of methods for making the base layer 31 friction-reducing include mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

[0090] The thickness of the substrate layer 31 can be, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[0091] (Adhesive layer 32) In the exterior material 3 for the energy storage device, the adhesive layer 32 is a layer that is placed on the base material layer 31 as needed in order to provide 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.

[0092] The adhesive layer 32 is formed by 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. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited and may be a chemical reaction type, solvent evaporation type, thermal melting type, hot pressure type, etc.

[0093] As for the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing suppression effect, and heat degradation suppression effect during heat sealing, and effectively suppressing the occurrence of delamination by suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33, two-component curable polyurethane adhesives; polyamide, polyester, or blended resins of these with modified polyolefins are preferred.

[0094] Furthermore, the adhesive layer 32 may be multilayered with different adhesive components. When the adhesive layer 32 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material 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. Specifically, when the adhesive layer 32 is multilayered with different adhesive components, preferred adhesive components arranged on the barrier layer 33 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyester and acid-modified polyolefins, and resins containing copolymerized polyesters.

[0095] The thickness of the adhesive layer 32 can be, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[0096] (Barrier layer 33) In the exterior material 3 for energy storage devices, the barrier layer 33 is a layer that not only improves the strength of the exterior material for energy storage devices but also prevents water vapor, oxygen, light, etc. from entering the inside of the energy storage device. The barrier layer 33 is preferably a metal layer, that is, a layer made of metal. Specifically, examples of metals that make up the barrier layer 33 include aluminum, stainless steel, and titanium, with aluminum being preferred. The barrier layer 33 can be formed from, for example, metal foil, metal vapor-deposited film, inorganic oxide vapor-deposited film, carbon-containing inorganic oxide vapor-deposited film, or a film provided with these vapor-deposited films, and it is preferably formed from metal foil, and even more preferably from aluminum foil. From the viewpoint of preventing wrinkles and pinholes from occurring in the barrier layer 33 during the manufacturing of the exterior material for energy storage devices, it is more preferable that the barrier layer be formed from 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).

[0097] Regarding the thickness of the barrier layer 33, from the viewpoint of making the exterior material for the energy storage device thinner while also making it less likely for pinholes to occur during molding, it 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.

[0098] Furthermore, it is preferable that at least one surface, preferably both surfaces, of the barrier layer 33 be chemically treated to stabilize adhesion and prevent dissolution and corrosion. Here, chemical treatment refers to a treatment that forms a corrosion-resistant film on the surface of the barrier layer.

[0099] (adhesive layer 34) In the exterior material 3 for the energy storage device, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as needed, in order to firmly bond the heat-fusible resin layer 35.

[0100] The adhesive layer 34 is formed by an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include resin compositions containing acid-modified polyolefins. Examples of acid-modified polyolefins include those exemplified in the acid-modified polyolefin layer 11 and the polyolefin layer 12.

[0101] The thickness of the adhesive layer 34 can be, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[0102] (Thermal adhesive resin layer 35) In the exterior material 3 for the energy storage device, the heat-sealable resin layer 35 is the innermost layer, and during the assembly of the energy storage device, the heat-sealable resin layers heat-seal each other to seal the energy storage device elements.

[0103] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, but examples include polyolefins and cyclic polyolefins.

[0104] Specifically, the polyolefins 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 copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0105] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. 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, norbornadiene, etc. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0106] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blends thereof; more preferably, polyethylene, polypropylene, copolymers of ethylene and norbornene, and blends of two or more of these.

[0107] The heat-fusible resin layer 35 may be formed by a single resin component or by a blended polymer combining two or more resin components. Furthermore, the heat-fusible resin layer 35 may be formed as a single layer or as two or more layers made of the same or different resin components. It is particularly preferable that the resins of the polyolefin layer 12 and the heat-fusible resin layer 35 are the same, as this improves the adhesion between these layers.

[0108] Furthermore, the thickness of the heat-sealable resin layer 35 is not particularly limited, but is preferably about 2 to 2000 μm, more preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0109] 2. Energy storage devices The energy storage device 10 of this disclosure comprises at least an energy storage device element 4 having a positive electrode, a negative electrode, and an electrolyte; an outer casing material 3 for the energy storage device that seals the energy storage device element 4; and metal terminals 2 electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material 3 for the energy storage device. The energy storage device 10 of this disclosure is characterized in that the adhesive film 1 for metal terminals of this disclosure is interposed between the metal terminals 2 and the outer casing material 3 for the energy storage device. That is, the energy storage device 10 of this disclosure can be manufactured by a method that includes a step of interposing the adhesive film 1 for metal terminals of this disclosure between the metal terminals 2 and the outer casing material 3 for the energy storage device.

[0110] Specifically, a storage device element 4 comprising at least a positive electrode, a negative electrode, and an electrolyte is covered with a storage device exterior material 3, with the metal terminals 2 connected to the positive and negative electrodes respectively protruding outwards. The adhesive film 1 for metal terminals of this disclosure is interposed between the metal terminals 2 and the heat-sealable resin layer 35. A flange portion (the area where the heat-sealable resin layers 35 come into contact with each other, and the peripheral edge portion 3a of the storage device exterior material 3) of the storage device exterior material 3 is formed around the periphery of the storage device element 4. The heat-sealable resin layers 35 of the flange portion are then heat-sealed to create a sealed storage device 10 using the storage device exterior material 3. When housing the storage device element 4 using the storage device exterior material 3, the heat-sealable resin layer 35 of the storage device exterior material 3 is used so that it faces inwards (the surface in contact with the storage device element 4).

[0111] The energy storage device of this disclosure can be suitably used as an energy storage device such as a battery (including capacitors, capacitors, etc.). The energy storage device of this disclosure may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery is not particularly limited and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly preferred. [Examples]

[0112] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0113] <Manufacturing of adhesive films for metal terminals> Example 1 Using an extruder and a T-die casting apparatus, an acid-modified polyolefin layer was formed on one side of an unstretched polypropylene film (homopolypropylene, 60 μm thick) as an intermediate layer. This was made by extruding maleic anhydride-modified polypropylene (random polypropylene (a random copolymer of ethylene and propylene) modified with maleic anhydride) and a polyolefin layer was made on the other side. These layers were then extruded at a temperature of 260°C, resulting in the sequential lamination of an acid-modified polyolefin layer (PPa layer, 50 μm thick), an intermediate layer (CPP layer, 60 μm thick), and a polyolefin layer (PP layer, 40 μm thick). The result was an adhesive film for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient described in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for their respective formation. As shown in Table 1, no colorant was added to the adhesive film for metal terminals in Example 1. Furthermore, erucic acid amide was added as a lubricant at a concentration of 700 ppm to the random polypropylene that forms the polyolefin layer.

[0114] Examples 2-9 and Comparative Examples 1-2 As shown in Table 1, in the adhesive films for metal terminals of Examples 2-9 and Comparative Examples 1-2, carbon black was added to the acid-modified polyolefin layer as a coloring agent at a concentration of 0.15% by mass, and erucic acid amide was added to the random polypropylene forming the polyolefin layer as a lubricant at the concentrations shown in Table 1. Except for these differences, the process was the same as in Example 1, with an acid-modified polyolefin layer (PPa layer, thickness 50 μm) / intermediate layer (CPP layer, thickness 60 μm) / polyolefin layer (PP layer, thickness 40 μm) being laminated in sequence, resulting in adhesive films for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient shown in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted according to the surface shape of the cooling roll used for their respective formation.

[0115] Example 10 Using an extruder and a T-die casting apparatus, an acid-modified polyolefin layer was formed on one side of an unstretched polypropylene film (homopolypropylene, 50 μm thick) as an intermediate layer. This was made by extruding maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) and a polyolefin layer was made on the other side. Both layers were extruded at a temperature of 260°C. As a result, the acid-modified polyolefin layer (PPa layer, 50 μm thick), the intermediate layer (CPP layer, 50 μm thick), and the polyolefin layer (PP layer, 50 μm thick) were laminated in sequence, yielding an adhesive film for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient listed in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for each layer's formation. As shown in Table 1, in the adhesive film for metal terminals of Example 10, carbon black was blended into the acid-modified polyolefin layer at a concentration of 0.15% by mass as a coloring agent, and erucic acid amide was blended into the random polypropylene forming the polyolefin layer at a concentration of 700 ppm as a lubricant.

[0116] Example 11 Using an extruder and a T-die casting apparatus, maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) is extruded at a temperature of 260°C to form an acid-modified polyolefin layer on one side of an unstretched polypropylene film (random polypropylene, 50 μm thick) as an intermediate layer, and a polyolefin layer on the other side of the random polypropylene. The resulting layers are: acid-modified polyolefin layer (PPa layer, 50 μm thick) / intermediate layer (CPP layer, 50 μm thick) / polyolefin layer (PP layer). A 50 μm thick layer was laminated to obtain an adhesive film for metal terminals having the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient described in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted according to the surface shape of the cooling roll used for their respective formation. As described in Table 1, in the adhesive film for metal terminals of Example 11, carbon black was blended into the acid-modified polyolefin layer at a concentration of 0.15% by mass as a coloring agent, and erucic acid amide was blended into the random polypropylene forming the polyolefin layer at a concentration of 700 ppm as a lubricant.

[0117] Example 12 Using an extruder and a T-die casting apparatus, an acid-modified polyolefin layer was formed on one side of an unstretched polypropylene film (homopolypropylene, 40 μm thick) as an intermediate layer. This was made by extruding maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) and a polyolefin layer was made on the other side of the film at a temperature of 260°C. The resulting layers were sequentially laminated as follows: acid-modified polyolefin layer (PPa layer, 30 μm thick) / intermediate layer (CPP layer, 40 μm thick) / polyolefin layer (PP layer, 30 μm thick). This yielded an adhesive film for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient listed in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for their respective formation. As shown in Table 1, in the adhesive film for metal terminals of Example 12, carbon black was blended into the acid-modified polyolefin layer at a concentration of 0.15% by mass as a coloring agent, and erucic acid amide was blended into the random polypropylene forming the polyolefin layer at a concentration of 700 ppm as a lubricant.

[0118] Example 13 Using an extruder and a T-die casting apparatus, an acid-modified polyolefin layer was formed on one side of an unstretched polypropylene film (homopolypropylene, 80 μm thick) as an intermediate layer. This was made by extruding maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) and a polyolefin layer was made on the other side of the film at a temperature of 260°C. The resulting layers were then laminated in the following order: acid-modified polyolefin layer (PPa layer, 60 μm thick) / intermediate layer (CPP layer, 80 μm thick) / polyolefin layer (PP layer, 60 μm thick). This yielded an adhesive film for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient described in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for their respective formation. As shown in Table 1, in the adhesive film for metal terminals of Example 13, carbon black was blended into the acid-modified polyolefin layer as a coloring agent at a concentration of 0.15% by mass, and erucic acid amide was blended into the random polypropylene forming the polyolefin layer at a concentration of 700 ppm as a lubricant.

[0119] Example 14 Using an extruder and a T-die casting apparatus, an acid-modified polyolefin layer was formed on one side of an unstretched polypropylene film (homopolypropylene, 80 μm thick) as an intermediate layer. This was made by extruding maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) and a polyolefin layer was made on the other side of the film at a temperature of 260°C. The resulting layers were then laminated in the following order: acid-modified polyolefin layer (PPa layer, 60 μm thick) / intermediate layer (CPP layer, 80 μm thick) / polyolefin layer (PP layer, 60 μm thick). This yielded an adhesive film for metal terminals with the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient described in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for their respective formation. As shown in Table 1, in the adhesive film for metal terminals of Example 14, carbon black was blended as a coloring agent in the intermediate layer at a concentration of 0.15% by mass, and erucic acid amide was blended as a lubricant at a concentration of 700 ppm in the random polypropylene that forms the polyolefin layer.

[0120] Example 15 Using an extruder and a T-die casting apparatus, two layers of maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) 6, which forms an acid-modified polyolefin layer, were extruded at a temperature of 260°C onto one side of an unstretched polypropylene film (homopolypropylene, 60 μm thick) as an intermediate layer, and random polypropylene, which forms a polyolefin layer, was extruded onto the other side. As a result, the layers were sequentially laminated as follows: acid-modified polyolefin layer (PPa layer, 40 μm thick) / acid-modified polyolefin layer (PPa layer, 40 μm thick) / intermediate layer (CPP layer, 60 μm thick) / polyolefin layer (PP layer, 60 μm thick). An adhesive film for metal terminals was obtained having the arithmetic surface roughness, gloss (GU value), and dynamic friction coefficient described in Table 1. The arithmetic surface roughness of the acid-modified polyolefin layer and the polyolefin layer were adjusted by the surface shape of the cooling roll used for each layer's formation. As shown in Table 1, in the adhesive film for metal terminals of Example 15, carbon black was blended as a coloring agent at a concentration of 0.15% by mass in the acid-modified polyolefin layer adjacent to the intermediate layer, and erucic acid amide was blended as a lubricant at a concentration of 700 ppm in the random polypropylene forming the polyolefin layer.

[0121] <Arithmetic surface roughness Ra> For adhesive films for metal terminals, the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer and the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for energy storage devices were measured using an optical surface texture analyzer (Zygo New View 7300). The average value was taken from n=3 measurements. The measurement results are shown in Table 1.

[0122] <Glossiness (GU value)> For adhesive films for metal terminals, the glossiness GuA (GU) of the metal terminal side surface of the acid-modified polyolefin layer and the glossiness GuB (GU) of the exterior material side surface of the polyolefin layer for energy storage devices were measured as follows. In accordance with JIS Z 8741:1997, a Microtrigloss AG-4430 manufactured by BYK-Gardner was used, and the observed Gu value was defined as the glossiness under conditions of a light incidence angle of 60° on either the metal terminal side surface or the exterior material side surface of the adhesive film for metal terminals. The average value of n=5 measurements was used. The measurement results are shown in Table 1.

[0123] <Coefficient of Dynamic Friction> For adhesive films for metal terminals, the coefficient of dynamic friction μA of the metal terminal side surface of the acid-modified polyolefin layer and the coefficient of dynamic friction μB of the exterior material side surface of the polyolefin layer for energy storage devices were measured as follows. Friction tests were conducted according to the method specified in JIS K7125:1999, 8.1, for film-to-film measurement. First, two samples of the exterior material for energy storage devices were cut out, measuring 80 mm in the TD direction and 200 mm in the MD direction. Next, to measure the coefficient of dynamic friction μA of the metal terminal side surface of the acid-modified polyolefin layer, the samples were stacked with the metal terminal side surfaces of the acid-modified polyolefin layers facing each other, and a sliding piece was placed on top. Rubber was attached to the bottom surface of the sliding piece, and the total mass of the sliding piece was set to 200 g, ensuring that the sample and the sliding piece were in close contact and did not slip. Next, the sliding piece was pulled at a speed of 100 mm / min, and the kinetic friction force (N) between the two samples was measured. The coefficient of kinetic friction was calculated by dividing the kinetic friction force by the normal force of the sliding piece (1.96 N). The coefficient of kinetic friction μB of the polyolefin layer on the exterior material side for energy storage devices was calculated by stacking the samples so that the exterior material side surfaces of the polyolefin layers faced each other and conducting the test. The coefficient of kinetic friction was determined from the average value up to the first 30 mm after the start of relative shear motion between the contact surfaces, neglecting the peak of static friction force. The load cell was directly connected to the sliding piece. The measurement results are shown in Table 1.

[0124] <Rating> The following adhesive films for metal terminals were evaluated from the perspectives of surface identification, bubble generation, and thermal shrinkage. The evaluation results are shown in Table 1.

[0125] [Distinguishing between surfaces] Adhesive film for metal terminals was cut into 10cm squares, and each piece was arranged so that the metal terminal side surface and the energy storage device casing material side surface were facing upwards. Next, the adhesive film for metal terminals was observed from a distance of 1.0m, and the ease of distinguishing between the metal terminal side surface and the energy storage device casing material side surface was evaluated according to the following criteria. A: They can be easily distinguished. B: They can be distinguished. C: It's somewhat difficult to distinguish, but it is distinguishable. D: Indistinguishable.

[0126] [Bubble formation] Adhesive film for metal terminals was cut to a size of TD10mm x MD55mm, and two pieces of adhesive film for metal terminals were prepared. In addition, an aluminum alloy metal terminal (width 45mm, length 60mm, thickness 400μm) was prepared. As shown in the schematic diagram of Figure 7, the MD of the adhesive film was aligned with the width direction of the metal terminal, and the acid-modified polyolefin layer of the adhesive film for metal terminals was placed on both sides of the center of the metal terminal, facing the metal terminal. The metal terminals were then heat-sealed in a flatbed press with a metal head fitted with 3.0mm thick, hardness 40 silicone rubber on both the top and bottom at 190℃ x 0.25MPa (surface pressure on the silicone rubber) x 10 seconds to prepare metal terminals with adhesive film. The metal terminals with adhesive film were observed using a magnifying glass (magnification 20x) to confirm the generation of air bubbles at the interface between the adhesive film and the metal terminal. The evaluation criteria are as follows. The 10-second sealing time was set to 2 / 3 of the normal time to simulate harsh conditions where air bubbles are likely to form. A: No air bubbles were observed. B: Small air bubbles have formed on the side (thickness direction) of the metal terminal. C: Air bubbles have formed on the side (thickness direction) and surface (perpendicular to the side) of the metal terminal.

[0127] [Heat shrinkage] Adhesive film for metal terminals was cut to a size of TD10mm x MD120mm, and markings were made at 100mm intervals. Next, the adhesive film for metal terminals was heated in a 180°C oven for 2 minutes by suspending it with one of the markings sandwiched between the two, and the length between the markings was measured. The length retention rate between the markings (length after heating / length before heating) was calculated, and the suppression of thermal shrinkage was evaluated according to the following criteria. A: The length retention rate between gauge marks is 0.7 or higher, indicating that thermal shrinkage is sufficiently suppressed. C: The length retention rate of the gauge spacing is less than 0.7, indicating insufficient suppression of thermal shrinkage.

[0128] [Table 1]

[0129] In the laminate configurations shown in Table 1, rPP refers to random polypropylene, hPP refers to homopolypropylene, and rPPa refers to random polypropylene modified with maleic anhydride. The numbers in parentheses represent the thickness (μm).

[0130] As described above, this disclosure provides inventions in the following embodiments. Item 1. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. An adhesive film for metal terminals, wherein the ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.2. Item 2. The adhesive film for metal terminals according to Item 1, wherein the arithmetic surface roughness RaB (μm) is 0.6 μm or less. Item 3. The adhesive film for metal terminals according to Item 1 or 2, wherein the glossiness GuB(GU) of the surface of the polyolefin layer on the exterior material side for the energy storage device, measured at an incident angle of 60°, is 15 GU or more. Item 4. A metal terminal adhesive film according to any one of items 1 to 3, wherein the coefficient of dynamic friction is measured in accordance with the provisions of JIS K7125:1999, 8.1 Film to Film, and the coefficient of dynamic friction of the polyolefin layer on the exterior material side for the energy storage device μB and the coefficient of dynamic friction of the acid-modified polyolefin layer on the metal terminal side μA are both in the range of 0.1 to 0.5. Item 5. The adhesive film for metal terminals according to any one of items 1 to 4, wherein at least one of the acid-modified polyolefin layer and the polyolefin layer contains a lubricant in an amount of 1500 ppm or less. Item 6. The adhesive film for metal terminals according to any one of items 1 to 5, wherein the polyolefin layer comprises at least one of random polypropylene and a terpolymer consisting of ethylene-propylene-butene. Item 7. The adhesive film for metal terminals according to any one of items 1 to 6, wherein the acid-modified polyolefin layer comprises acid-modified random polypropylene. Item 8. An intermediate layer is provided between the acid-modified polyolefin layer and the polyolefin layer. The intermediate layer comprises homopolypropylene, and is an adhesive film for metal terminals according to any one of claims 1 to 7. Item 9. An intermediate layer is provided between the acid-modified polyolefin layer and the polyolefin layer. An adhesive film for metal terminals according to any one of items 1 to 8, satisfying the relationship: thickness of the intermediate layer > thickness of the acid-modified polyolefin layer > thickness of the polyolefin layer. Item 10. An adhesive film for metal terminals as described in any one of items 1 to 9, having a thickness of 50 μm or more and 250 μm or less. Item 11. The exterior material for the energy storage device is composed of a laminate comprising, at least from the outside, a base layer, a barrier layer, and a heat-sealable resin layer in this order. The adhesive film for metal terminals according to any one of claims 1 to 10, wherein the resin forming the heat-fusible resin layer is of the same type as the resin forming the polyolefin layer. Item 12. The adhesive film for metal terminals is an adhesive film for metal terminals according to any one of items 1 to 11, comprising a pigment. Item 13. The pigment is at least one of a black pigment and a white pigment. The adhesive film for metal terminals according to item 12, wherein the pigment content in the layer containing the pigment is 0.05% by mass or more and 5.00% by mass or less. Item 14. A method for manufacturing an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrodes of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The process includes at least the step of obtaining a laminate comprising the polyolefin layer and the acid-modified polyolefin layer, A method for manufacturing an adhesive film for metal terminals, wherein the ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.2. Item 15. A metal terminal with an adhesive film for metal terminals, wherein an adhesive film for metal terminals described in any one of items 1 to 13 is attached to the metal terminal. Item 16. A power storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the power storage device that seals the power storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding from the outer casing material for the power storage device, An energy storage device in which an adhesive film for metal terminals according to any one of items 1 to 13 is interposed between the metal terminal and the exterior material for the energy storage device. Item 17. A method for manufacturing an energy storage device comprising at least a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the energy storage device that seals the energy storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, A method for manufacturing an energy storage device, comprising the step of interposing an adhesive film for metal terminals described in any one of items 1 to 13 between the metal terminals and the exterior material for the energy storage device, and sealing the energy storage device element with the exterior material for the energy storage device. Item 18. A kit comprising an exterior material for energy storage devices and an adhesive film for metal terminals, The energy storage device includes an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte, an outer casing material for the energy storage device that seals the energy storage device element, and metal terminals protruding from the outside of the energy storage device. The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.2. The kit is used to seal the energy storage device element with the energy storage device exterior material by interposing the adhesive film for metal terminals between the metal terminals and the exterior material for the energy storage device during use. Item 19. The kit according to item 18, wherein the adhesive film for metal terminals is attached to the metal terminals. Item 20. Exterior material for energy storage devices, for use in energy storage devices, The energy storage device includes an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte, an outer casing material for the energy storage device that seals the energy storage device element, and metal terminals protruding from the outside of the energy storage device. The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.2. The exterior material for the energy storage device is composed of a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer. [Explanation of Symbols]

[0131] 1. Adhesive film for metal terminals 2 metal terminals 3. Exterior materials for energy storage devices 3a Peripheral edge of exterior material for energy storage device 4 Energy Storage Device Elements 10 Energy storage devices 11. Acid-modified polyolefin layer 12 Polyolefin layer 13. Middle Class 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-fusible resin layer

Claims

1. An adhesive film for metal terminals, interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.

5. The arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer is 0.4 μm or more. The arithmetic surface roughness RaB (μm) is 0.4 μm or less, and the adhesive film is for metal terminals.

2. The adhesive film for metal terminals according to claim 1, wherein the arithmetic surface roughness RaB (μm) is 0.1 μm or more.

3. The adhesive film for metal terminals according to claim 1 or 2, wherein the glossiness GuB (GU) of the surface of the polyolefin layer on the exterior material side for the energy storage device, measured at an incident angle of 60°, is 15 GU or more.

4. The adhesive film for metal terminals according to claim 1 or 2, wherein the coefficient of dynamic friction measured in accordance with the provisions of JIS K7125:1999, 8.1 Film to Film, is such that the coefficient of dynamic friction μB of the polyolefin layer on the exterior material side for the energy storage device and the coefficient of dynamic friction μA of the acid-modified polyolefin layer on the metal terminal side are both in the range of 0.1 to 0.

5.

5. The adhesive film for metal terminals according to claim 1 or 2, wherein the polyolefin layer comprises at least one of random polypropylene and a terpolymer consisting of ethylene-propylene-butene.

6. The adhesive film for metal terminals according to claim 1 or 2, wherein the acid-modified polyolefin layer comprises acid-modified random polypropylene.

7. An intermediate layer is provided between the acid-modified polyolefin layer and the polyolefin layer. The adhesive film for metal terminals according to claim 1 or 2, wherein the intermediate layer comprises homopolypropylene.

8. An intermediate layer is provided between the acid-modified polyolefin layer and the polyolefin layer. The adhesive film for metal terminals according to claim 1 or 2, satisfying the relationship: thickness of the intermediate layer > thickness of the acid-modified polyolefin layer > thickness of the polyolefin layer.

9. The adhesive film for metal terminals according to claim 1 or 2, wherein the thickness is 50 μm or more and 250 μm or less.

10. The exterior material for the energy storage device is composed of a laminate comprising, at least from the outside, a base layer, a barrier layer, and a heat-sealable resin layer in that order. The adhesive film for metal terminals according to claim 1 or 2, wherein the resin forming the heat-fusible resin layer is of the same type as the resin forming the polyolefin layer.

11. The adhesive film for metal terminals according to claim 1 or 2, wherein the adhesive film for metal terminals contains a pigment.

12. The aforementioned pigment is at least one of a black pigment and a white pigment. The adhesive film for metal terminals according to claim 11, wherein the pigment content in the layer containing the pigment is 0.05% by mass or more and 5.00% by mass or less.

13. A method for manufacturing an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to the electrode of an energy storage device element and an outer casing material for an energy storage device that seals the energy storage device element, The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The process includes at least the step of obtaining a laminate comprising the polyolefin layer and the acid-modified polyolefin layer, The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.

5. The arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer is 0.4 μm or more. A method for manufacturing an adhesive film for metal terminals, wherein the arithmetic surface roughness RaB (μm) is 0.4 μm or less.

14. A metal terminal with an adhesive film for metal terminals, wherein the adhesive film for metal terminals described in claim 1 or 2 is attached to the metal terminal.

15. A power storage device comprising, at least, a positive electrode, a negative electrode, and an electrolyte; an outer casing material for the power storage device that seals the power storage device element; and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the power storage device, An energy storage device comprising an adhesive film for metal terminals according to claim 1 or 2 interposed between the metal terminal and the exterior material for the energy storage device.

16. A method for manufacturing an energy storage device comprising at least a positive electrode, a negative electrode, and an electrolyte, an outer casing material for the energy storage device that seals the energy storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the outer casing material for the energy storage device, A method for manufacturing an energy storage device, comprising the step of interposing an adhesive film for metal terminals according to claim 1 or 2 between the metal terminal and the exterior material for the energy storage device, and sealing the energy storage device element with the exterior material for the energy storage device.

17. A kit comprising an exterior material for energy storage devices and an adhesive film for metal terminals, The energy storage device includes an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte, an outer casing material for the energy storage device that seals the energy storage device element, and metal terminals protruding from the outside of the energy storage device. The adhesive film for metal terminals is composed of a laminate comprising at least an acid-modified polyolefin layer constituting the metal terminal side surface and a polyolefin layer constituting the exterior material side surface for the energy storage device. The ratio of the arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer to the arithmetic surface roughness RaB (μm) of the exterior material side surface of the polyolefin layer for the energy storage device satisfies the relationship RaA / RaB > 1.

5. The arithmetic surface roughness RaA (μm) of the metal terminal side surface of the acid-modified polyolefin layer is 0.4 μm or more. The arithmetic surface roughness RaB (μm) is 0.4 μm or less. The kit is used to seal the energy storage device element with the energy storage device exterior material by interposing the adhesive film for metal terminals between the metal terminals and the exterior material for the energy storage device during use.

18. The kit according to claim 17, wherein the adhesive film for metal terminals is attached to the metal terminals.

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