Metal terminal adhesive film, method of manufacturing the same, metal terminal with metal terminal adhesive film, power storage device, and method of manufacturing the power storage device

Abstract

To provide a metal terminal adhesive film excellent in heat resistance and sealability.SOLUTION: Provided is a metal terminal adhesive film interposed between a metal terminal electrically connected with an electrode of a power storage device element and a power storage device sheath material for encapsulating the power storage device element. The metal terminal adhesive film is configured by a laminate at least comprising a polyester resin layer, an imine-modified polyolefin resin layer, and a polyolefin resin layer in this order.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Various types of electricity storage devices have been developed to date, and in all electricity storage devices, exterior materials for electricity storage devices have become essential components for sealing electricity storage device elements such as electrodes and electrolytes. Metal exterior materials for electricity storage devices have traditionally been widely used as exterior materials for electricity storage devices. However, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like, electricity storage devices are being required to have a variety of shapes, as well as to be thinner and lighter. However, the metal exterior materials for electricity storage devices that have traditionally been widely used have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how much they can be made lighter.

[0003] Therefore, in recent years, a laminate sheet in which a base layer / adhesive layer / barrier layer / thermal adhesive resin layer are laminated in this order has been proposed as an electrical storage device packaging material that can be easily processed into a variety of shapes and can achieve thinning and weight reduction. When such a laminate film-like electrical storage device packaging material is used, the electrical storage device elements are sealed in the electrical storage device packaging material by heat-sealing the peripheral edge of the electrical storage device packaging material with the innermost thermal adhesive resin layers facing each other.

[0004] Metal terminals protrude from the heat-sealed portions of the exterior material for an electricity storage device, and the electricity storage device elements sealed with the exterior material for an electricity storage device are electrically connected to the outside via the metal terminals electrically connected to the electrodes of the electricity storage device elements. That is, the portions of the heat-sealed exterior material for an electricity storage device where the metal terminals are present are heat-sealed in a state where the metal terminals are sandwiched between the heat-sealable resin layers. Because the metal terminals and the heat-sealable resin layer are made of different materials, adhesion is likely to decrease at the interface between the metal terminals and the heat-sealable resin layer.

[0005] For this reason, an adhesive film is sometimes disposed between the metal terminal and the heat-sealable resin layer in order to improve adhesion between them, etc. Examples of such adhesive films include those described in Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-79638 Summary of the Invention [Problem to be solved by the invention]

[0007] The adhesive film disposed between the metal terminal and the heat-sealable resin layer is required to have heat resistance and sealing properties because it is heat-sealed at high temperature and pressure between the exterior material for the electricity storage device and the metal terminal.

[0008] The energy storage devices in which adhesive films are used are generally those containing an electrolyte, such as lithium-ion batteries, but all-solid-state batteries, which use a solid electrolyte, are also known. Because the electrolyte of all-solid-state batteries is solid, they are capable of rapid charging at high temperatures compared to energy storage devices using an electrolyte, and are expected to be used in higher temperature environments than lithium-ion batteries and the like.

[0009] Furthermore, in the manufacturing process of all-solid-state batteries, in order to increase the ionic conductivity of the solid electrolyte, the cells may be pressed at high temperatures and pressures (for example, at a temperature of 120°C to 150°C and a pressure of about 100 MPa) with metal terminals attached, which may result in the metal terminals reaching high temperatures. Therefore, when the above-mentioned adhesive film is applied to an all-solid-state battery, particularly excellent heat-resistant sealing properties are required.

[0010] Furthermore, not only in all-solid-state batteries but also in electricity storage devices, for example, during rapid charging and discharging, the temperature of the metal terminals can reach approximately 150°C due to resistance heating. Therefore, it is desirable to impart excellent heat resistance and sealing properties to adhesive films used in various electricity storage devices.

[0011] To improve the heat resistance of adhesive films, resin films with high melting points, such as polyester films, can be used as adhesive films, but polyester films have poor adhesion to metal terminals. Also, in order to bond polyester films to metal terminals, they must be heated at very high temperatures (e.g., 160°C or higher) for a long time, which does not provide good sealing properties.

[0012] In light of these circumstances, a primary object of the present disclosure is to provide an adhesive film for metal terminals that has excellent heat resistance and sealing properties. Further, the present disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals that uses the adhesive film for metal terminals, an electricity storage device that uses the adhesive film for metal terminals, and a method for manufacturing the electricity storage device. [Means for solving the problem]

[0013] The inventors of the present disclosure have conducted extensive research to solve the above-mentioned problems. As a result, they have found that, in an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, the adhesive film for metal terminals is composed of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order, so that the adhesive film for metal terminals exhibits excellent heat resistance and sealing properties. The present disclosure has been completed through further research based on this finding.

[0014] That is, the present disclosure provides the inventions of the following aspects. An adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, The adhesive film for metal terminals is composed of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide an adhesive film for a metal terminal that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, the adhesive film for a metal terminal having excellent heat resistance and sealing properties. Furthermore, the present disclosure can also provide a metal terminal with an adhesive film for a metal terminal, an electricity storage device, and a method for manufacturing the electricity storage device. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic plan view of an electricity storage device according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line AA' in FIG. [Figure 3]FIG. 2 is a schematic cross-sectional view taken along line BB' in FIG. [Figure 4] 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. [Figure 5] 1 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 6] FIG. 2 is a schematic diagram for explaining a method for evaluating sealing properties in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0017] The adhesive film for metal terminals of the present disclosure is an adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, and is characterized in that the adhesive film for metal terminals is composed of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order.

[0018] Because the adhesive film for metal terminals of the present disclosure has these characteristics, the adhesive film for metal terminals exhibits excellent heat resistance and sealing properties. In the present disclosure, "an adhesive film for metal terminals exhibits excellent heat resistance" specifically means that the adhesive film for metal terminals exhibits high sealing strength with the exterior packaging material for an electricity storage device even when the adhesive film for metal terminals is adhered to a metal terminal and placed in a high-temperature environment (e.g., 150°C). In the present disclosure, "an adhesive film for metal terminals exhibits excellent sealing properties" also means that when the adhesive film for metal terminals is heat-sealed at a temperature of about 170 to 210°C, the adhesive film for metal terminals undergoes little change in shape due to thermal shrinkage and is heat-sealed along the shape of the metal terminal, making it less likely to form gaps around the metal terminal. Specific evaluation methods are, for example, as described in the Examples.

[0019] The electricity storage device of the present disclosure is also an electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, and is characterized in that an adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for an electricity storage device.

[0020] The adhesive film for metal terminal and its manufacturing method, and the electricity storage device and its manufacturing method according to the present disclosure will be described in detail below.

[0021] In this specification, numerical ranges indicated with "to" mean "greater than or equal to" or "less than or equal to." For example, the expression 2 to 15 mm means 2 mm or greater and 15 mm or less.

[0022] Another method for confirming the MD of an adhesive film for metal terminals is to observe the cross section of the adhesive film for metal terminals (e.g., cross sections of a polyester resin layer, an imine-modified polyolefin resin layer, and a polyolefin resin layer) using an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section in which the average diameter of the island shapes in the direction perpendicular to the thickness direction of the adhesive film for metal terminals is the largest can be determined as the MD. Specifically, the sea-island structure is confirmed by observing the longitudinal cross section of the adhesive film for metal terminals and each cross section at an angle of 10 degrees from the direction parallel to the longitudinal cross section to the direction perpendicular to the longitudinal cross section (a total of 10 cross sections) using an electron microscope. Next, the shape of each individual island is observed in each cross section. For each island shape, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the adhesive film for metal terminals to the rightmost end in that vertical direction is defined as the diameter y. For each cross section, the average of the diameters y of the top 20 island shapes in order of largest diameter y is calculated. The direction parallel to the cross section in which the average diameter y of the island shape is the largest is determined to be the MD. Alternatively, for example, the adhesive film for metal terminals can be left in an environment of 150°C for 2 minutes, and the thermal shrinkage rate measured, and the direction with the larger shrinkage rate determined to be the MD.

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

[0024] As mentioned above, temperatures of approximately 150°C are expected to be reached during, for example, the hot pressing process in the manufacturing process of an all-solid-state battery or during rapid charging, and a temperature tolerance of approximately 150°C is required. Therefore, a heat-sealable resin layer with a melting point of 150°C or higher must be used for the exterior material 3 for an electric storage device. The heating temperature for heat-sealing the edges of the exterior material for an electric storage device is typically in the range of approximately 160 to 250°C, and the pressure is typically in the range of approximately 0.5 to 2.0 MPa, using a flat metal seal bar. The edges where the metal terminal and the exterior material for an electric storage device are heat-sealed via the adhesive film for the metal terminal are similarly sealed using a stepped metal seal head, with a step provided in the relevant portion of the seal head to adjust for differences in thickness due to the metal terminal and the adhesive film for the metal terminal, at a temperature typically in the range of approximately 160 to 250°C and a pressure typically in the range of approximately 0.5 to 2.0 MPa.

[0025] It is also desirable to adhere the adhesive film to a predetermined position on the metal terminal in advance. For example, when adhering by thermal welding, it is common to perform multiple heating and pressure applications, such as a temporary adhesion process to the metal terminal and a final adhesion process.

[0026] The temporary bonding process is a process in which the adhesive film for metal terminals is temporarily attached to the metal terminal and air bubbles are removed, and the main bonding process is a process in which the adhesive film for metal terminals is bonded to the metal terminal by applying heat and pressure once or multiple times under higher temperature conditions than in the temporary bonding process.

[0027] The process of temporarily adhering an adhesive film for metal terminals to a metal terminal is carried out, for example, once or twice using a metal seal head covered with heat-resistant rubber having a hardness of approximately 20 to 50 and a thickness of approximately 2 to 5 mm at a temperature of approximately 160 to 230°C, a pressure of approximately 0.1 to 0.5 MPa, and a time of approximately 10 to 20 seconds.

[0028] The purpose of this bonding process is to achieve thermal fusion between the adhesive film for metal terminals and the metal terminal, and it is carried out under conditions such as a temperature of about 180 to 250°C, a pressure of about 0.2 to 1.0 MPa, a time of about 10 to 20 seconds, and once or twice using a metal seal head covered with heat-resistant rubber having a hardness of about 20 to 50 and a thickness of about 2 to 5 mm.

[0029] Furthermore, if necessary, efficient welding can be achieved by providing a step in the relevant portion of the seal head to adjust for differences in thickness between the metal terminal and the adhesive film for a metal terminal. Furthermore, by providing an adhesive layer on the surface of the adhesive film for a metal terminal facing the metal terminal, the metal terminal and the adhesive film for a metal terminal can be bonded at a relatively low temperature.

[0030] For example, a thermosetting resin capable of adhering to metal can be laminated as an adhesive layer on the surface of the metal terminal in an incomplete state, and then the metal terminal and adhesive film for metal terminals are heat-sealed together, and then aged to harden and provide heat resistance. In this case, the sealing conditions for the metal terminal and adhesive film for metal terminals are, for example, about 100°C to 200°C and a pressure of about 0.2 to 3.0 MPa, and the aging conditions are about 40 to 150°C and several minutes to 5 days.

[0031] In addition, when the electricity storage device to which the adhesive film for metal terminal of the present disclosure is applied is an all-solid-state battery, high temperature and high pressure will be particularly applied to the adhesive film for metal terminal. The method of attaching the adhesive film for metal terminal exemplified here is one example and is not limited to a specific method. For example, the pressure application time and the like are appropriately adjusted depending on the thickness of the adhesive film for metal terminal and the like.

[0032] The adhesive film 1 for metal terminals of the present disclosure is provided to improve adhesion between the metal terminal 2 and the exterior packaging material 3 for an electricity storage device. Improved adhesion between the metal terminal 2 and the exterior packaging material 3 for an electricity storage device improves the sealing performance of the electricity storage device element 4. As described above, when the electricity storage device element 4 is heat-sealed, the electricity storage device element is sealed such that the metal terminal 2 electrically connected to the electrode of the electricity storage device element 4 protrudes outside the exterior packaging material 3 for an electricity storage device. At this time, the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer made of a heat-sealable resin such as polyolefin) located in the innermost layer of the exterior packaging material 3 for an electricity storage device are made of different materials. Therefore, without using such an adhesive film, the sealing performance of the electricity storage device element is likely to be reduced at the interface between the metal terminal 2 and the heat-sealable resin layer 35.

[0033] The adhesive film 1 for metal terminals of the present disclosure includes a configuration in which at least a polyester-based resin layer 11, an imine-modified polyolefin-based resin layer 13, and a polyolefin-based resin layer 12 are laminated in this order, as shown in Fig. 4. In the adhesive film 1 for metal terminals of Fig. 4, the polyester-based resin layer 11 forms the surface facing the exterior packaging material 3 for an electricity storage device, and the polyolefin-based resin layer 12 forms the surface facing the metal terminal 2, but in the adhesive film 1 for metal terminals of the present disclosure, the polyester-based resin layer 11 and the polyolefin-based resin layer 12 do not necessarily have to form the surface of the adhesive film 1 for metal terminals. In particular, when an acid-modified polyolefin, which will be described later, is used as the resin for the polyolefin-based resin layer 12, it has good adhesion to the metal terminal 2 (acid-modified polyolefins have a high affinity for metals), so it is preferable for the polyolefin-based resin layer 12 to constitute the surface on the metal terminal 2 side, but as the polyester-based resin layer 11 mainly contributes to improving the heat resistance of the adhesive film for metal terminal 1, it is preferable for the polyester-based resin layer 11 to constitute the surface of the adhesive film for metal terminal 1, or it is also preferable for it not to constitute the surface. For example, it is also preferable that both sides of the adhesive film for metal terminal 1 are constituted by the polyolefin-based resin layer 12.

[0034] The adhesive film 1 for metal terminals may contain only one layer or two or more layers of each of the polyester-based resin layer 11, the imine-modified polyolefin-based resin layer 13, and the polyolefin-based resin layer 12. The adhesive film 1 for metal terminals may also contain layers other than these, as long as the effects of the present disclosure are not impaired.

[0035] Furthermore, the imine-modified polyolefin resin layer 13 is preferably in contact with each of the polyester resin layer 11 and the polyolefin resin layer 12. This is because polyester resins and polyolefin resins generally have low affinity, making it difficult to bond the polyester resin and the polyolefin resin with high adhesive strength. The imine-modified polyolefin resin layer 13 can suitably function as a layer that bonds the polyester resin layer 11 and the polyolefin resin layer 12.

[0036] Specific examples of the laminate structure of the adhesive film for metal terminal 1 of the present disclosure include a laminate structure in which a polyester-based resin layer 11 / imine-modified polyolefin-based resin layer 13 / polyolefin-based resin layer 12 are laminated in this order; a laminate structure in which a polyolefin-based resin layer 12 / imine-modified polyolefin-based resin layer 13 / polyester-based resin layer 11 / imine-modified polyolefin-based resin layer 13 / polyolefin-based resin layer 12 are laminated in this order; and a laminate structure in which a polyester-based resin layer 11 / imine-modified polyolefin-based resin layer 13 / polyolefin-based resin layer 12 / polyolefin-based resin layer 12 are laminated in this order. Among these, from the viewpoint of adhesion between the exterior material for an electricity storage device 3 and the metal terminal 2 and the adhesive film for metal terminal 1, a three-layer structure in which a polyester-based resin layer 11 / imine-modified polyolefin-based resin layer 13 / polyolefin-based resin layer 12 are laminated in this order is preferred.

[0037] In the adhesive film for metal terminal 1 of the present disclosure, the polyester-based resin layer 11 is a layer containing a polyester-based resin. As described below, the polyester-based resin layer 11 preferably contains at least one of polyethylene terephthalate and polybutylene terephthalate as a resin among polyester-based resins.

[0038] In the adhesive film for metal terminal 1 of the present disclosure, the polyolefin resin layer 12 is a layer containing a polyolefin resin (i.e., having a polyolefin skeleton). Because it has excellent adhesion to the metal terminal 2, the polyolefin resin layer 12 preferably contains an acid-modified polyolefin resin as the resin. The resin contained in the polyolefin resin layer 12 is preferably an acid-modified polyolefin resin. The acid-modified polyolefin resin is a polyolefin resin that has been acid-modified. Examples of acid-modified polyolefin resins include polyethylene and polypropylene.

[0039] In the adhesive film for metal terminal 1 of the present disclosure, the imine-modified polyolefin resin layer 13 is a layer containing an imine-modified polyolefin resin. The imine-modified polyolefin resin is a polyolefin resin that has been imine-modified. Examples of imine-modified polyolefin resins include polyethylene and polypropylene.

[0040] When the adhesive film 1 for metal terminals of the present disclosure is placed between the metal terminal 2 of the electricity storage device 10 and the exterior material 3 for electricity storage devices, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin or polyester) of the exterior material 3 for electricity storage devices are bonded via the adhesive film for metal terminals 1. For example, the polyolefin-based resin layer 12 side of the adhesive film 1 for metal terminals is placed on the metal terminal 2 side, and the polyester-based resin layer 11 side is placed on the exterior material 3 for electricity storage devices, with the polyolefin-based resin layer 12 side in close contact with the metal terminal 2 and the polyester-based resin layer 11 side in close contact with the heat-sealable resin layer 35 of the exterior material 3 for electricity storage devices.

[0041] The thickness (total thickness) of the laminate constituting the adhesive film for metal terminal 1 of the present disclosure is, for example, about 50 μm or more, preferably about 60 μm or more, and more preferably about 80 μm or more, from the viewpoint of improving conformability to the shape of the metal terminal 2. The total thickness of the adhesive film for metal terminal 1 of the present disclosure is preferably about 500 μm or less, more preferably about 200 μm or less, and even more preferably about 180 μm or less. Preferred ranges for the total thickness of the adhesive film for metal terminal 1 of the present disclosure include about 50 to 500 μm, about 50 to 250 μm, about 50 to 200 μm, about 50 to 180 μm, about 60 to 500 μm, about 60 to 250 μm, about 60 to 200 μm, about 60 to 180 μm, about 80 to 500 μm, about 80 to 250 μm, about 80 to 200 μm, and about 80 to 180 μm. As a more specific example, when the adhesive film 1 for metal terminals of the present disclosure is used in a consumer electricity storage device, the total thickness is preferably about 60 to 100 μm, and when it is used in an in-vehicle electricity storage device, the total thickness is preferably about 100 to 200 μm.

[0042] The materials constituting the polyester resin layer 11, the imine-modified polyolefin resin layer 13, and the polyolefin resin layer 12, their thicknesses, etc. will be described in detail below.

[0043] As shown in Fig. 4, the adhesive film 1 for metal terminals of the present disclosure comprises a polyester-based resin layer 11 on one side of an imine-modified polyolefin-based resin layer 13, and a polyolefin-based resin layer 12 on the other side. In the adhesive film 1 for metal terminals of the present disclosure, the polyester-based resin layer 11 side is preferably disposed on the side of the exterior packaging material 3 for an electricity storage device. Furthermore, the polyolefin-based resin layer 12 side is preferably disposed on the side of the metal terminal 2.

[0044] In the adhesive film for metal terminal 1 of the present disclosure, a polyester-based resin layer 11 and a polyolefin-based resin layer 12 are located on the surfaces of both sides. As described above, in the adhesive film for metal terminal 1 of FIG. 4, the polyester-based resin layer 11 constitutes the surface on the exterior material 3 for an electrical storage device, and the polyolefin-based resin layer 12 constitutes the surface on the metal terminal 2 side. However, in the adhesive film for metal terminal 1 of the present disclosure, the polyester-based resin layer 11 and the polyolefin-based resin layer 12 do not have to constitute the surface of the adhesive film for metal terminal 1. In particular, when an acid-modified polyolefin is used as the resin for the polyolefin-based resin layer 12, it has good adhesion to the metal terminal 2 (acid-modified polyolefin has a high affinity for metal), so it is preferable that the polyolefin-based resin layer 12 constitutes the surface on the metal terminal 2 side. However, since the polyester-based resin layer 11 mainly contributes to improving the heat resistance of the adhesive film for metal terminal 1, it is preferable that the polyester-based resin layer 11 constitutes the surface of the adhesive film for metal terminal 1, or it is also preferable that it does not constitute the surface. For example, it is also preferred that both surfaces of the adhesive film 1 for metal terminals are composed of polyolefin-based resin layers 12. When the polyester-based resin layer 11 constitutes the surface of the adhesive film 1 for metal terminals facing the exterior packaging material for an electricity storage device, the polyester-based resin layer 11 has excellent heat resistance, and therefore has the advantage that the adhesive film 1 for metal terminals interposed between the metal terminal and the exterior packaging material for an electricity storage device is less likely to be crushed when the exterior packaging material for an electricity storage device is heat-sealed.

[0045] The adhesive film 1 for metal terminals may contain only one layer or two or more layers of each of the polyester-based resin layer 11, the imine-modified polyolefin-based resin layer 13, and the polyolefin-based resin layer 12. Furthermore, the adhesive film 1 for metal terminals may contain layers other than these, as long as the effects of the present disclosure are not impaired.

[0046] [Polyester-based resin layer 11] The polyester-based resin layer 11 is a layer containing a polyester-based resin.

[0047] Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

[0048] The polyester-based resin layer 11 preferably contains at least one of polyethylene terephthalate and polybutylene terephthalate as a resin among polyester-based resins. The resin contained in the polyester-based resin layer 11 is preferably at least one of polyethylene terephthalate and polybutylene terephthalate.

[0049] The polyester-based resin layer 11 may be formed of a single resin component alone or a blend polymer of two or more resin components. Furthermore, the polyester-based resin layer 11 may be formed of only one layer, or two or more layers of the same or different resin components.

[0050] The polyester-based resin layer 11 preferably contains a polyester-based resin and an elastomer. The elastomer contained in the polyester-based resin layer 11 may be any elastomer that enhances the flexibility of the adhesive film for metal terminal 1 while ensuring excellent heat resistance and sealing properties. Preferred elastomers include at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, polyethers, and acrylics, or thermoplastic elastomers that are copolymers of these. More preferred examples include thermoplastic elastomers composed of a block copolymer of polybutylene terephthalate and polyether, and thermoplastic elastomers composed of an α-olefin copolymer of polymethylpentene. In the thermoplastic elastomer composed of a block copolymer of polybutylene terephthalate and polyether, the polyether component may be a copolymer of terephthalic acid and polytetramethylene ether glycol. Specific preferred examples of polyether-based thermoplastic elastomers include polytetramethylene glycol and polyepsilon caprolactam. The content of the elastomer in the polyester resin layer 11 is not particularly limited as long as it ensures excellent heat resistance and sealing properties of the adhesive film for metal terminal 1 while increasing its flexibility, and is, for example, about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. The content is, for example, about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges for the content include about 0.1 to 10.0 mass%, about 0.1 to 8.0 mass%, about 0.1 to 5.0 mass%, about 0.5 to 10.0 mass%, about 0.5 to 8.0 mass%, about 0.5 to 5.0 mass%, about 1.0 to 10.0 mass%, about 1.0 to 8.0 mass%, about 1.0 to 5.0 mass%, about 3.0 to 10.0 mass%, about 3.0 to 8.0 mass%, and about 3.0 to 5.0 mass%, etc.

[0051] The melting point of the polyester-based resin layer 11 is preferably at least 20° C. higher than the melting point of the polyolefin-based resin layer 12, more preferably at least 40° C. higher, and even more preferably at least 60° C. higher. The melting point of the polyester-based resin layer 11 is preferably at least 180° C., more preferably at least 190° C., and even more preferably at least 200° C., and is preferably at most 240° C., more preferably at most 230° C., and even more preferably at most 220° C.

[0052] To more suitably achieve the effects of the present disclosure, the thickness of the polyester resin layer 11 is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is preferably about 60 μm or less, more preferably about 55 μm or less, and even more preferably 50 μm or less. Preferred thickness ranges for the polyester resin layer 11 include about 10 to 60 μm, about 10 to 55 μm, about 10 to 50 μm, about 15 to 60 μm, about 15 to 55 μm, about 15 to 50 μm, about 20 to 60 μm, about 20 to 55 μm, and about 20 to 50 μm, respectively.

[0053] In the present disclosure, from the viewpoint of more suitably exerting the effects of the present disclosure, the ratio of the thickness of the polyester resin layer 11 to the total thickness (100%) of the adhesive film 1 for metal terminals is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and also preferably 80% or less, more preferably 70% or less, even more preferably 60% or less.

[0054] [Polyolefin resin layer 12] In the adhesive film for metal terminal 1 of the present disclosure, the polyolefin resin layer 12 is a layer containing a polyolefin resin (i.e., having a polyolefin skeleton). Because it has excellent adhesion to the metal terminal, the polyolefin resin layer 12 preferably contains an acid-modified polyolefin resin as the resin. The resin contained in the polyolefin resin layer 12 is preferably an acid-modified polyolefin resin. The acid-modified polyolefin resin is a polyolefin resin that has been acid-modified. Examples of acid-modified polyolefin resins include polyethylene and polypropylene.

[0055] Acid-modified polyolefins have a high affinity for metals. Therefore, in the adhesive film for metal terminal 1 of the present disclosure, by arranging a polyolefin-based resin layer 12 containing an acid-modified polyolefin-based resin on the metal terminal 2 side, excellent adhesion can be exhibited at the interface between the adhesive film for metal terminal 1 and the metal terminal 2. Note that polyolefin-based resins have excellent adhesion to the heat-sealable resin layer 35 (made of polyolefin or the like) of the packaging material for an electricity storage device, and therefore, by arranging the polyolefin-based resin layer 12 on the heat-sealable resin layer 35 side of the packaging material for an electricity storage device 3, even better adhesion can be exhibited at the interface between the adhesive film for metal terminal 1 and the heat-sealable resin layer 35.

[0056] The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferred examples include polyolefins graft-modified with an unsaturated carboxylic acid or an anhydride thereof.

[0057] In the polyolefin-based resin layer 12, examples of the polyolefin (acid-modified polyolefin for the polyolefin-based resin layer 12) include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, polypropylene block copolymers (e.g., propylene-ethylene block copolymers), and polypropylene random copolymers (e.g., propylene-ethylene random copolymers); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred, with polypropylene being particularly preferred. Furthermore, among polypropylenes, homopolypropylene (i.e., polypropylene homopolymers) are preferred because of their excellent heat resistance. For example, acid-modified polyolefin-based resins preferably contain acid-modified homopolypropylene because of their excellent heat resistance, and are more preferably formed from acid-modified homopolypropylene.

[0058] The polyolefin may also be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a cyclic polyolefin by substituting an α,β-unsaturated carboxylic acid or an anhydride thereof for some of the monomers constituting the cyclic polyolefin, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof with a cyclic polyolefin.

[0059] Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of the olefins constituting the cyclic polyolefins include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers constituting the 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 is also an example of a constituting monomer.

[0060] Examples of carboxylic acids or anhydrides thereof used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. When the polyolefin resin layer 12 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around . That is, in this case, when the polyolefin resin layer 12 is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected. However, if the degree of acid modification is low, the peak may be small and not be detected. In that case, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0061] The polyolefin resin layer 12 may be formed of one type of resin component alone, or may be formed of a blend polymer combining two or more types of resin components. Furthermore, the polyolefin resin layer 12 may be formed of only one layer, or may be formed of two or more layers using the same or different resin components. From the viewpoint of film formability of the polyolefin resin layer 12, it is preferable to form it of a blend polymer combining two or more types of resin components. When using a blend polymer, the polyolefin resin layer 12 preferably contains acid-modified polypropylene as the main component (50% by mass or more) and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). Furthermore, the polyolefin resin layer 12 preferably contains polypropylene as the main component (50% by mass or more) and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the polyolefin resin layer 12, it is preferable that the polyolefin resin layer 12 contains acid-modified polypropylene alone as the resin, and it is preferable that the polyolefin resin layer 12 contains polypropylene alone as the resin.

[0062] The melting point of the polyolefin resin layer 12 is preferably 155°C or higher, more preferably 160°C or higher, and even more preferably 165°C or higher, and is preferably 170°C or lower, more preferably 165°C or lower, and even more preferably 160°C or lower.

[0063] From the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the polyolefin-based resin layer 12 is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is preferably about 120 μm or less, more preferably about 110 μm or less, even more preferably 100 μm or less, and even more preferably 80 μm or less. Preferred ranges for the thickness of the polyolefin-based resin layer 12 are about 10 to 120 μm, about 10 to 110 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 110 μm, about 15 to 100 μm, about 15 to 80 μm, and about 20 to 120 μm, respectively. degree, about 20 to 110 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0064] In the present disclosure, from the viewpoint of more suitably exerting the effects of the present disclosure, the ratio of the thickness of the polyolefin resin layer 12 to the total thickness (100%) of the adhesive film 1 for metal terminals is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and also preferably 80% or less, more preferably 70% or less, even more preferably 60% or less.

[0065] [Imine-modified polyolefin resin layer 13] In the adhesive film for metal terminal 1 of the present disclosure, the imine-modified polyolefin resin layer 13 is a layer containing a polyolefin resin (i.e., having a polyolefin skeleton). The resin contained in the imine-modified polyolefin resin layer 13 is preferably an imine-modified polyolefin resin. The imine-modified polyolefin resin is a polyolefin resin that has been imine-modified. Examples of imine-modified polyolefin resins include polyethylene and polypropylene.

[0066] The imine modification is preferably obtained by grafting a polyimine compound having a plurality of imino groups onto a polyolefin in the presence of a radical generator. The imine-modified polyolefin is preferably an imine-modified polypropylene grafted with polypropyleneimine.

[0067] The imine-modified polyolefin resin layer 13 is preferably in contact with each of the polyester resin layer 11 and the polyolefin resin layer 12. This is because polyester resins and polyolefin resins generally have low affinity, making it difficult to bond the polyester resin and the polyolefin resin with high adhesive strength. The imine-modified polyolefin resin layer 13 can suitably function as a layer that bonds the polyester resin layer 11 and the polyolefin resin layer 12.

[0068] The imine-modified polyolefin-based resin layer 13 may be formed of one type of resin component alone or a blend polymer of two or more types of resin components. Furthermore, the imine-modified polyolefin-based resin layer 13 may be formed of only one layer, or two or more layers of the same or different resin components.

[0069] The melting point of the imine-modified polyolefin resin layer 13 is preferably 155°C or higher, more preferably 160°C or higher, even more preferably 165°C or higher, and preferably 170°C or lower, more preferably 165°C or lower, even more preferably 160°C or lower.

[0070] From the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the imine-modified polyolefin resin layer 13 is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is preferably about 60 μm or less, more preferably about 55 μm or less, and even more preferably 50 μm or less. Preferred thickness ranges for the imine-modified polyolefin resin layer 13 include about 10 to 60 μm, about 10 to 55 μm, about 10 to 50 μm, about 15 to 60 μm, about 15 to 55 μm, about 15 to 50 μm, about 20 to 60 μm, about 20 to 55 μm, and about 20 to 50 μm, respectively.

[0071] In the present disclosure, from the viewpoint of more suitably exerting the effects of the present disclosure, the ratio of the thickness of the imine-modified polyolefin resin layer 13 to the total thickness (100%) of the adhesive film 1 for metal terminals is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and is also preferably 10% or less, more preferably 20% or less, even more preferably 30% or less.

[0072] (additives) Furthermore, the polyester resin layer 11, the polyolefin resin layer 12, and the imine-modified polyolefin resin layer 13 may each contain additives such as colorants such as pigments, fillers, and lubricants in addition to the resin.

[0073] Various inorganic pigments can be used as the pigment. A specific example of a pigment is carbon (carbon, graphite), which is exemplified as a filler described below. Carbon (carbon, graphite) is a material commonly used inside an electricity storage device and is unlikely to leach into the electrolyte solution. Therefore, it can be suitably incorporated when the polyolefin resin layer 12 is located on the metal terminal 2 side. Furthermore, it has a significant coloring effect, and a sufficient coloring effect can be obtained with an amount added that does not impair adhesion. Furthermore, it does not melt due to heat, and can increase the apparent melt viscosity of the added resin. Furthermore, it prevents the pressed portion from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing between the electricity storage device exterior material and the metal terminal.

[0074] When a pigment is added to the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13, the amount of the pigment added is, for example, about 0.05 to 0.3 parts by mass, and preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin components forming the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13, when carbon black with a particle size of about 0.03 μm is used. Adding a pigment to only one of the polyester-based resin layer 11 and the polyolefin-based resin layer 12 (preferably only the polyolefin-based resin layer 12) makes it possible to easily distinguish between the surface on the metal terminal side and the surface on the electricity storage device exterior packaging material side. When both a pigment and a filler are added to the exterior packaging material 3 for an electrical storage device, both the filler pigments may be added to the same polyester-based resin layer 11 or polyolefin-based resin layer 12, but from the viewpoint of not impairing the thermal fusion properties of the adhesive film 1 for metal terminals, it is preferable to add the filler and pigment separately to the polyester-based resin layer 11 and the polyolefin-based resin layer 12.

[0075] By including a filler in at least one of the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13, the filler functions as a spacer, making it possible to effectively prevent short circuits between the metal terminal 2 and the barrier layer 33 of the electrical storage device packaging material 3. The particle size of the filler is about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. The content of the filler is about 5 to 30 parts by mass, more preferably about 10 to 20 parts by mass, relative to 100 parts by mass of the resin components forming the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13, respectively.

[0076] The filler may be either inorganic or organic. 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, cross-linked polymethyl methacrylates, and cross-linked polyethylenes. From the standpoints of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesins, acrylic resins, and benzoguanamine-formaldehyde condensates are preferred, with spherical aluminum oxide and silica being particularly preferred. As a method for mixing the filler into the resin components that form the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13, a method in which the two are melt-blended in advance using a Banbury mixer or the like to form a masterbatch and then adjusted to a predetermined mixing ratio, or a method in which the filler is directly mixed with the resin components can be used.

[0077] From the viewpoint of improving the sealing properties of the electricity storage device of the present disclosure, it is preferable that a lubricant be contained in each of the layers (e.g., polyester-based resin layer 11, polyolefin-based resin layer 12) that constitute the surface of the adhesive film for metal terminal 1. The concentration of the lubricant is preferably 2000 ppm or less, more preferably 1500 ppm or less, and even more preferably 1000 ppm or less, and is preferably 200 ppm or more, more preferably 500 ppm or more, with preferred ranges being about 200 to 2000 ppm, about 200 to 1500 ppm, about 200 to 1000 ppm, about 500 to 2000 ppm, about 500 to 1500 ppm, and about 500 to 1000 ppm.

[0078] The lubricant is not particularly limited, but preferably includes amide-based lubricants. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, and N,N'-distearyl sebacic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

[0079] When the polyester-based resin layer 11, the polyolefin-based resin layer 12, and the imine-modified polyolefin-based resin layer 13 are each composed of a resin film, the surfaces of these layers may be subjected to known adhesion-facilitating means such as corona discharge treatment, ozone treatment, or plasma treatment, as necessary.

[0080] The adhesive film 1 for metal terminals of the present disclosure can be produced, for example, by laminating a polyester-based resin layer 11 and a polyolefin-based resin layer 12 on the surface of an imine-modified polyolefin-based resin layer 13. The imine-modified polyolefin-based resin layer 13 can be laminated with the polyester-based resin layer 11 and the polyolefin-based resin layer 12 by a known method such as extrusion lamination, T-die lamination, inflation lamination, or thermal lamination.

[0081] The method for interposing the adhesive film 1 for a metal terminal between the metal terminal 2 and the exterior packaging material 3 for an electricity storage device is not particularly limited, and for example, as shown in Figures 1 to 3, the adhesive film 1 for a metal terminal may be wrapped around the metal terminal 2 in the portion where the metal terminal 2 is sandwiched by the exterior packaging material 3 for an electricity storage device. Furthermore, although not shown, in the portion where the metal terminal 2 is sandwiched by the exterior packaging material 3 for an electricity storage device, the adhesive film 1 for a metal terminal may be arranged on both sides of the metal terminal 2 so as to cross the two metal terminals 2.

[0082] [Metal terminal 2] The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between a metal terminal 2 and an exterior material 3 for an electricity storage device. The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive or negative electrode) of an electricity storage device element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium ion electricity storage device is usually made of aluminum or the like. The metal terminal 2 connected to the negative electrode of a lithium ion electricity storage device is usually made of copper, nickel, or the like, and from the viewpoints of low resistance and prevention of surface deterioration, it is made of nickel-plated copper or a nickel-copper clad material or the like.

[0083] The surface of the metal terminal 2 is preferably subjected to a chemical conversion treatment in order to enhance electrolyte resistance. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming a corrosion-resistant film using phosphates, chromates, fluorides, triazine thiol compounds, acrylates, etc. Among the methods for forming a corrosion-resistant film, preferred are phosphate chromate treatments using a three-component system consisting of a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid, or a three-component system consisting of an acrylic resin, a chromium (III) nitrate compound, and phosphoric acid.

[0084] The size of the metal terminal 2 may be set appropriately depending on the size of the electricity storage device to be used. The thickness of the metal terminal 2 is preferably about 50 to 4000 μm, more preferably about 60 to 3000 μm, and even more preferably about 70 to 1000 μm. The length of the metal terminal 2 is preferably about 1 to 500 mm, and more preferably about 3 to 300 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, and more preferably about 3 to 150 mm.

[0085] [Exterior materials for energy storage devices 3] The electrical storage device packaging material 3 may have a laminated structure including at least a substrate layer 31, a barrier layer 33, and a heat-sealable resin layer 35, in this order. FIG. 5 shows an example of the cross-sectional structure of the electrical storage device packaging material 3, in which the substrate layer 31, an optional adhesive layer 32, a barrier layer 33, an optional adhesive layer 34, and a heat-sealable resin layer 35 are laminated in this order. In the electrical storage device packaging material 3, the substrate layer 31 is the outer layer, and the heat-sealable resin layer 35 is the innermost layer. During assembly of the electrical storage device, the electrical storage device elements 4 are sealed by bringing the heat-sealable resin layers 35 located on the periphery of the electrical storage device elements 4 into contact with each other and heat-sealing them, thereby sealing the electrical storage device elements 4. While FIGS. 1 to 3 illustrate an electrical storage device 10 using an embossed type electrical storage device packaging material 3 formed by embossing or the like, the electrical storage device packaging material 3 may be an unformed pouch type. The pouch type includes three-sided seal, four-sided seal, pillow type, etc., and any type may be used.

[0086] The thickness of the laminate constituting the electricity storage device packaging material 3 is not particularly limited, but from the viewpoints of cost reduction, improving energy density, and the like, the upper limit is 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, or about 120 μm or less, and from the viewpoint of maintaining the function of the electricity storage device packaging material 3 to protect the electricity storage device elements 4, the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, or about 80 μm or more, and preferred ranges are, for example, about 35 to 180 μm, 35 to 1 Examples include about 60 μm, about 35 to 155 μm, about 35 to 140 μm, about 35 to 130 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 160 μm, about 45 to 155 μm, about 45 to 140 μm, about 45 to 130 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm, about 60 to 120 μm, about 80 to 180 μm, about 80 to 160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm, and about 80 to 120 μm.

[0087] Furthermore, the adhesive film 1 for metal terminals of the present disclosure can be suitably applied to packaging materials for all-solid-state batteries, and the thickness of the laminate constituting the packaging material for all-solid-state batteries is not particularly limited, but from the viewpoints of cost reduction, improving energy density, etc., it is preferably about 10,000 μm or less, about 8,000 μm or less, about 5,000 μm or less, and about 500 μm or less. From the viewpoint of maintaining the function of the packaging material for all-solid-state batteries, which is to protect the battery element, it is preferably about 100 μm or more, about Examples of the thickness include 150 μm or more and approximately 200 μm or more, and preferred ranges include, for example, about 100 to 10,000 μm, about 100 to 8,000 μm, about 100 to 5,000 μm, about 150 to 10,000 μm, about 150 to 8,000 μm, about 150 to 5,000 μm, about 200 to 10,000 μm, about 200 to 8,000 μm, about 200 to 5,000 μm, 150 to 500 μm, and about 200 to 500 μm, with about 100 to 500 μm being particularly preferred.

[0088] (Base material layer 31) In the packaging material 3 for an electricity storage device, the base material layer 31 is a layer that functions as the base material of the packaging material for an electricity storage device, and is a layer that forms the outermost layer side.

[0089] The material for forming the base layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as materials for forming the base layer 31. Furthermore, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the base layer 31 during molding, and is therefore preferably used as materials for forming the base layer 31.

[0090] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, is preferably used as the base layer 31 because its heat resistance is improved by oriented crystallization.

[0091] Among these, nylon and polyester are preferred, and biaxially oriented nylon and biaxially oriented polyester are more preferred as the resin film forming the base layer 31. In addition, all-solid-state batteries are designed to withstand temperatures of 150°C or higher, so they are often sealed at high temperatures of 200°C or higher, and biaxially oriented polyester is the most suitable.

[0092] The base layer 31 can be formed by laminating resin films made of different materials to improve pinhole resistance and insulation when used as a package for an electricity storage device. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated together, or a multilayer structure in which a biaxially oriented polyester film and a biaxially oriented nylon film are laminated together. When the base layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be directly laminated together without an adhesive. Bonding without an adhesive can be achieved by, for example, a method of bonding in a hot-melt state, such as coextrusion, sand lamination, or thermal lamination. For the high-temperature sealing described above, it is desirable that at least the outermost layer be made of biaxially oriented polyester.

[0093] The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, or a combination thereof may be used.

[0094] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0095] (Adhesive layer 32) In the packaging material 3 for an electricity storage device, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as necessary in order to impart adhesion to the base material layer 31. In other words, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0096] The adhesive layer 32 is formed of an adhesive capable of bonding the base material 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. The bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, or the like.

[0097] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and effectively suppressing a decrease in the laminate strength between the base layer 31 and the barrier layer 33 and preventing delamination.

[0098] Furthermore, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin that has excellent adhesion to the base material layer 31 as the adhesive component disposed on the base material layer 31 side, and an adhesive component that has excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, preferred examples of the adhesive component disposed on the barrier layer 33 side include acid-modified polyolefin, metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, and a resin containing copolymer polyester.

[0099] Furthermore, when the packaging material 3 for an electricity storage device is a packaging material for an all-solid-state battery, the adhesive layer 32 is preferably formed from a cured product of a resin composition containing at least one of polyester and polycarbonate and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound. This prevents delamination between the barrier layer 33 and the heat-fusible resin layer 35 in a high-temperature environment, and also enables the packaging material for an all-solid-state battery to exhibit high seal strength.

[0100] The polyester is preferably a polyester polyol. There are no particular limitations on the polyester polyol as long as it has an ester bond in the polymer main chain and a plurality of hydroxyl groups at the terminal or side chain. The polycarbonate is preferably a polycarbonate polyol. There are no particular limitations on the polyester polyol as long as it has a carbonate bond in the polymer main chain and a plurality of hydroxyl groups at the terminal or side chain. The polyester is preferably, for example, a polyester obtained by previously reacting a polyester polyol with a polyisocyanate (e.g., diisocyanate) to extend the urethane chain, or a polycarbonate obtained by previously reacting a polycarbonate polyol with a polyisocyanate (e.g., diisocyanate) to extend the urethane chain. The polyester and polycarbonate contained in the resin composition forming the adhesive layer 5 may each be one type or two or more types.

[0101] The alicyclic isocyanate compound is not particularly limited as long as it is a compound having an alicyclic structure and an isocyanate group. The alicyclic isocyanate compound preferably has two or more isocyanate groups. Specific examples of the alicyclic isocyanate compound include isophorone diisocyanate (IPDI), bis(4-isocyanatocyclohexyl)methane, 1,3-bis(isocyanatomethyl)cyclohexane, methylenebis(4,1-cyclohexylene)diisocyanate, and the like, as well as their polymers or nurates, mixtures thereof, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates. The alicyclic isocyanate compound is preferably a polyol-modified polyisocyanate obtained by reacting an alicyclic isocyanate with a polyol (e.g., polyester polyol) in advance. The resin composition forming the adhesive layer 5 may contain one or more types of alicyclic isocyanate compounds.

[0102] The aromatic isocyanate compound is not particularly limited as long as it is a compound having an aromatic ring and an isocyanate group. Preferably, the aromatic isocyanate compound has two or more isocyanate groups. Specific examples of aromatic isocyanate compounds include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), their polymers or nurates, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates. Preferably, the aromatic isocyanate compound is a polyol-modified polyisocyanate obtained by reacting an aromatic isocyanate with a polyol (e.g., polyester polyol) in advance. The aromatic isocyanate compound contained in the resin composition forming the adhesive layer 5 may be one type or two or more types.

[0103] The resin composition forming the adhesive layer 32 may, for example, contain an alicyclic isocyanate compound but not contain an aromatic isocyanate compound, or may, for example, contain an aromatic isocyanate compound but not contain an alicyclic isocyanate compound, or may, for example, contain both an alicyclic isocyanate compound and an aromatic isocyanate compound. The resin composition forming the adhesive layer 32 preferably contains an aromatic isocyanate compound.

[0104] The content of the alicyclic isocyanate compound and aromatic isocyanate compound in the adhesive layer 32 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. Furthermore, when the adhesive layer 5 contains both an alicyclic isocyanate compound and an aromatic isocyanate compound, the total content thereof in the resin composition constituting the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %.

[0105] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0106] (Barrier layer 33) In the electrical storage device packaging material, the barrier layer 33 is a layer that not only improves the strength of the electrical storage device packaging material but also has the function of preventing water vapor, oxygen, light, and the like from penetrating into the electrical storage device. The barrier layer 33 is preferably a metal layer, i.e., a layer formed of a metal. Specific examples of metals constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and aluminum is preferred. The barrier layer 33 can be formed, for example, from a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with any of these vapor deposition films. It is preferably formed from a metal foil, and more preferably from an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the production of the packaging material for an electricity storage device, it is more preferable that the barrier layer be formed from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0107] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, and more preferably about 20 to 100 μm, from the viewpoint of making the packaging material for an electricity storage device thinner and making it less likely to produce pinholes during molding.

[0108] Furthermore, it is preferable that at least one surface, and preferably both surfaces, of the barrier layer 33 be chemically treated to stabilize adhesion, prevent dissolution and corrosion, etc. Here, chemical treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0109] (adhesive layer 34) In the packaging material 3 for an electricity storage device, the adhesive layer 34 is a layer that is provided as needed between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

[0110] The adhesive layer 34 is formed of 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 thereof include an adhesive made of a polyester polyol compound and an alicyclic isocyanate compound.

[0111] It is also preferable that the adhesive layer 34 is a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group, and it is particularly preferable that the adhesive layer 34 is a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group.

[0112] Furthermore, when the packaging material 3 for an electricity storage device is a packaging material for an all-solid-state battery, similar to the adhesive layer 32, the adhesive layer 34 is preferably formed from a cured product of a resin composition containing at least one of polyester and polycarbonate, and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound.

[0113] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0114] (Thermal adhesive resin layer 35) In the packaging material 3 for an electricity storage device, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the electricity storage device elements by heat-sealing the heat-sealable resin layers together when assembling the electricity storage device.

[0115] The resin component used in the heat-sealable resin layer 35 is not particularly limited as long as it is heat-sealable, but for example, in the case of an exterior material for an electricity storage device, polyolefins and cyclic polyolefins are generally used.

[0116] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0117] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene is also an example of a constituting monomer.

[0118] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and blend polymers of two or more of these.

[0119] The heat-fusible resin layer 35 may be formed of one type of resin component alone, or may be formed of a blend polymer of two or more types of resin components. Furthermore, the heat-fusible resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resin components.

[0120] The thickness of the heat-fusible resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0121] Furthermore, the adhesive film 1 for metal terminals of the present disclosure can be particularly suitably applied to packaging materials for all-solid-state batteries, and the melting point of the heat-sealable resin layer 35 of the packaging material for all-solid-state batteries is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C.

[0122] Examples of resins contained in the heat-sealable resin layer 35 of the all-solid-state battery packaging material include polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the all-solid-state battery packaging material, the heat-sealable resin layer 35 is preferably formed from a polybutylene terephthalate film. Furthermore, by forming the heat-sealable resin layer 35 from a polybutylene terephthalate film, adhesion to the resin layer of the adhesive film for metal terminal of the present disclosure is also excellent. The polybutylene terephthalate film forming the heat-sealable resin layer 35 may be formed by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34 to form the heat-sealable resin layer 35, or by melt-extruding the resin forming the polybutylene terephthalate film to form a film and laminating it with the adhesive layer 34, or by co-extruding the adhesive layer 34 and the polybutylene terephthalate and laminating it on the barrier layer 33.

[0123] The polybutylene terephthalate film may be a stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and is preferably an unstretched polybutylene terephthalate film.

[0124] The polybutylene terephthalate film preferably further contains an elastomer in addition to polybutylene terephthalate. The elastomer serves to ensure the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. Preferred elastomers include at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or thermoplastic elastomer copolymers thereof. The content of the elastomer in the polybutylene terephthalate film is not particularly limited as long as it ensures the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. For example, the content is about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. The content may be, for example, about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges for the content include about 0.1 to 10.0 mass%, about 0.1 to 8.0 mass%, about 0.1 to 5.0 mass%, about 0.5 to 10.0 mass%, about 0.5 to 8.0 mass%, about 0.5 to 5.0 mass%, about 1.0 to 10.0 mass%, about 1.0 to 8.0 mass%, about 1.0 to 5.0 mass%, about 3.0 to 10.0 mass%, about 3.0 to 8.0 mass%, and about 3.0 to 5.0 mass%, etc.

[0125] The heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed of two or more layers, at least one layer is formed of a polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the all-solid-state battery packaging material. Furthermore, the layer bonded to the adhesive layer 34 is preferably a polybutylene terephthalate film. When the heat-sealable resin layer 35 is formed of two or more layers, the layer not formed of a polybutylene terephthalate film may be formed of, for example, a polyolefin such as polypropylene or polyethylene, or an acid-modified polyolefin such as acid-modified polypropylene or acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments than polybutylene terephthalate, the heat-sealable resin layer 35 is preferably formed of only a polybutylene terephthalate film.

[0126] 2. Energy storage devices An electricity storage device 10 of the present disclosure comprises at least an electricity storage device element 4 having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device 3 that seals the electricity storage device element 4, and metal terminals 2 that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device 3. The electricity storage device 10 of the present disclosure is characterized in that an adhesive film for a metal terminal 1 of the present disclosure is interposed between the metal terminal 2 and the exterior material for an electricity storage device 3. In other words, the electricity storage device 10 of the present disclosure can be produced by a method that includes a step of interposing an adhesive film for a metal terminal 1 of the present disclosure between the metal terminal 2 and the exterior material for an electricity storage device 3.

[0127] Specifically, an electricity storage device element 4 including at least a positive electrode, a negative electrode, and an electrolyte is enclosed in an electricity storage device packaging material 3, with metal terminals 2 connected to the positive and negative electrodes protruding outward, and an adhesive film 1 for metal terminals of the present disclosure is interposed between the metal terminals 2 and a heat-sealable resin layer 35, and the electricity storage device element 4 is covered around its periphery so as to form a flange portion of the electricity storage device packaging material (a region where the heat-sealable resin layers 35 come into contact with each other, i.e., the peripheral portion 3a of the electricity storage device packaging material), and the heat-sealable resin layers 35 of the flange portion are heat-sealed to provide an electricity storage device 10 using the electricity storage device packaging material 3. When the electricity storage device element 4 is housed using the electricity storage device packaging material 3, the heat-sealable resin layer 35 of the electricity storage device packaging material 3 is used so that it faces inside (the surface in contact with the electricity storage device element 4).

[0128] The exterior material for an electricity storage device according to the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device according to the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior material for an electricity storage device according to the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material for an electricity storage device according to the present disclosure.

[0129] Among these, the adhesive film for metal terminal 1 of the present disclosure can be suitably applied to all-solid-state batteries. [Example]

[0130] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0131] <Production of adhesive film for metal terminals> Example 1 A laminate was produced by coextrusion molding in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming the polyolefin resin layer, imine-modified polypropylene (random type) as the imine-modified polyolefin resin layer, and polybutylene terephthalate (homotype) forming the polyester resin layer were laminated in this order, and a polyolefin resin layer (h-PPa layer, thickness 20 μm, melting point 165 ° C) / imine-modified polyolefin resin layer (r-IP layer, thickness 20 μm, melting point 141 ° C) / polyester resin layer (h-PBT layer, thickness 60 μm, melting point 224 ° C) was laminated in this order to obtain an adhesive film for metal terminals (thickness 100 μm). The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0132] Example 2 A laminate was produced by coextrusion molding in which a maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin-based resin layer, an imine-modified polypropylene (random type) as an imine-modified polyolefin-based resin layer, and a polybutylene terephthalate (homotype) forming a polyester-based resin layer were laminated in this order, and a polyolefin-based resin layer (h-PPa layer, thickness 30 μm, melting point 165 ° C) / imine-modified polyolefin-based resin layer (r-IP layer, thickness 30 μm, melting point 141 ° C) / polyester-based resin layer (h-PBT layer, thickness 40 μm, melting point 224 ° C) was laminated in this order to obtain an adhesive film for metal terminals (thickness 100 μm). The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0133] Example 3 A laminate was produced by coextrusion molding in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming the polyolefin resin layer, imine-modified polypropylene (random type) as the imine-modified polyolefin resin layer, and polybutylene terephthalate (homotype) forming the polyester resin layer were laminated in this order, and a polyolefin resin layer (h-PPa layer, thickness 40 μm, melting point 165 ° C) / imine-modified polyolefin resin layer (r-IP layer, thickness 20 μm, melting point 141 ° C) / polyester resin layer (h-PBT layer, thickness 40 μm, melting point 224 ° C) was laminated in this order to obtain an adhesive film for metal terminals (thickness 100 μm). The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0134] Example 4 A laminate was produced by coextrusion molding in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming the polyolefin resin layer, imine-modified polypropylene (random type) as the imine-modified polyolefin resin layer, and polybutylene terephthalate (homotype) forming the polyester resin layer were laminated in this order, and a polyolefin resin layer (h-PPa layer, thickness 60 μm, melting point 165 ° C) / imine-modified polyolefin resin layer (r-IP layer, thickness 20 μm, melting point 141 ° C) / polyester resin layer (h-PBT layer, thickness 20 μm, melting point 224 ° C) was laminated in this order to obtain an adhesive film for metal terminals (thickness 100 μm). The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0135] Example 5 A laminate was produced by coextrusion molding in which a maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin-based resin layer, an imine-modified polypropylene (random type) as an imine-modified polyolefin-based resin layer, and a polybutylene terephthalate (copolymer type obtained by copolymerizing polyester and polyether) forming a polyester-based resin layer were laminated in this order, and a polyolefin-based resin layer (h-PPa layer, thickness 30 μm, melting point 165 ° C) / imine-modified polyolefin-based resin layer (r-IP layer, thickness 30 μm, melting point 141 ° C) / polyester-based resin layer (copolymer PBT layer, thickness 40 μm, melting point 213 ° C) was laminated in this order to obtain an adhesive film (thickness 100 μm) for metal terminals. The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0136] Example 6 A laminate was produced by coextrusion molding in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming the polyolefin resin layer, imine-modified polypropylene (homotype) as the imine-modified polyolefin resin layer, and polybutylene terephthalate (homotype) forming the polyester resin layer were laminated in this order, and an adhesive film (thickness 100 μm) for metal terminals was obtained, in which the polyolefin resin layer (h-PPa layer, thickness 30 μm, melting point 165 ° C) / imine-modified polyolefin resin layer (h-IP layer, thickness 30 μm, melting point 160 ° C) / polyester resin layer (h-PBT layer, thickness 40 μm, melting point 224 ° C) was laminated in this order. The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0137] Example 7 A laminate was produced by coextrusion molding in which a maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming the polyolefin resin layer, a polypropylene (homotype) forming the polyolefin resin layer, an imine-modified polypropylene (random type) as the imine-modified polyolefin resin layer, and a polybutylene terephthalate (copolymer type) forming the polyester resin layer were laminated in this order, and a polyolefin resin layer (h-PPa layer, thickness 30 μm, melting point 165 ° C) / polyolefin resin layer (h-PP layer, thickness 10 μm, melting point 165 ° C) / imine-modified polyolefin resin layer (r-IP layer, thickness 20 μm, melting point 141 ° C) / polyester resin layer (h-PBT layer, thickness 40 μm, melting point 224 ° C) was laminated in this order to obtain an adhesive film for metal terminals (thickness 100 μm). The laminate configuration of the adhesive film for metal terminals is shown in Table 1.

[0138] Example 8 A laminate in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, polybutylene terephthalate (homotype) forming a polyester resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, and maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin resin layer were laminated in this order was produced by coextrusion molding, and the laminate had a structure of polyolefin resin layer (h-PPa layer, thickness 20 μm, melting point 165°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyester resin layer (h-PBT layer, thickness 40 μm, melting point 224°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyolefin resin layer (h-PPa layer, thickness 20 μm The laminate structure of the adhesive film for metal terminal is shown in Table 1.

[0139] Example 9 A laminate in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, polybutylene terephthalate (homotype) forming a polyester resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, and polypropylene (homotype) forming a polyolefin resin layer were laminated in this order was produced by coextrusion molding, and the laminate had a structure of polyolefin resin layer (h-PPa layer, thickness 20 μm, melting point 165°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyester resin layer (h-PBT layer, thickness 40 μm, melting point 224°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyolefin resin (h-PP layer, thickness 20 μm The laminate structure of the adhesive film for metal terminal is shown in Table 1.

[0140] Example 10 A laminate in which maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) forming a polyolefin resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, polyethylene terephthalate forming a polyester resin layer, imine-modified polypropylene (random type) as an imine-modified polyolefin resin layer, and polypropylene (homotype) forming a polyolefin resin layer were laminated in this order was produced by co-extrusion molding, and a polyolefin resin layer (h-PPa layer, thickness 20 μm, melting point 165°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyester resin layer (PET layer An adhesive film for metal terminals (thickness 100 μm) was obtained in which the following layers were laminated in order: (thickness 40 μm, melting point 225°C) / imine-modified polyolefin resin layer (r-IP layer, thickness 10 μm, melting point 141°C) / polyolefin resin (h-PP layer, thickness 20 μm, melting point 165°C). The laminate structure of the adhesive film for metal terminals is shown in Table 1.

[0141] Comparative Example 1 A maleic anhydride-modified random polypropylene film (random polypropylene modified with maleic anhydride) (thickness 80 μm, melting point 140°C, random type) was prepared to form a polyolefin resin layer, and the maleic anhydride-modified polypropylene film single layer was used as an adhesive film for metal terminals.

[0142] Comparative Example 2 Using an extruder and a T-die casting machine, maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) was extruded onto one side of a polypropylene film (80 μm thick, homotype), and maleic anhydride-modified polypropylene (random polypropylene modified with maleic anhydride) was extruded onto the other side at a temperature of 270 ° C., resulting in a polyolefin resin layer (r-PPa layer, thickness 35 μm, melting point 140 ° C.) / polyolefin resin layer (h-PP layer, thickness 80 μm, melting point 165 ° C.) / polyolefin resin layer (r-PPa layer, thickness 35 μm, melting point 140 ° C.) laminated in this order to obtain an adhesive film for metal terminals (thickness 150 μm). The laminate structure of the adhesive film for metal terminals is shown in Table 1.

[0143] Comparative Example 3 Using an extruder and a T-die casting machine, maleic anhydride-modified polypropylene (homopolypropylene modified with maleic anhydride) was extruded at 165°C onto one side of a polybutylene terephthalate film (50µm thick, homotype), to obtain an adhesive film for metal terminals (100µm thick) consisting of a polyolefin resin layer (h-PPa layer, 50µm thick, melting point 224°C) and a polyester resin layer (h-PBT layer, 50µm thick, melting point 224°C). The laminate structure of the adhesive film for metal terminals is shown in Table 1.

[0144] Comparative Example 4 A polybutylene terephthalate film (thickness 100 μm, melting point 225° C., homotype) was prepared, and a single layer of the polybutylene terephthalate film was used as an adhesive film for metal terminals.

[0145] [Seal strength measurement in a 150°C environment (heat resistance evaluation)] An all-solid-state battery exterior material (a laminated film consisting of a substrate layer (polyethylene terephthalate (25 μm)) / adhesive layer (urethane adhesive 3 μm) / aluminum foil (40 μm) / adhesive layer (urethane adhesive (3 μm)) / heat-sealable resin layer (polybutylene terephthalate (25 μm)) laminated in this order) was prepared and cut to a size of TD 30 × MD 150 mm. In addition, aluminum foil (JIS H4160:1994) was used as a metal terminal with an adhesive film for the metal terminal. A8079H-O) (TD 22.5 mm, MD 180 mm, thickness 400 μm) was prepared. Adhesive films for metal terminals (width (TD) 20 mm, length (MD) 165 mm) were placed on both sides of the metal terminal. At this time, the MD and TD of the metal terminal were aligned with the length direction (MD) and width direction (TD) of the adhesive film, respectively, and the metal terminal and adhesive film were laminated so that their centers were aligned. Next, the temperature was 200°C, the surface pressure was approximately 0.25 MPa, and the adhesive film was heated for 1 hour. The laminate was heat-sealed for 6 seconds to produce a laminate in which the adhesive film for metal terminals / metal terminal / adhesive film for metal terminals were laminated in this order. Furthermore, the metal terminals with the adhesive film for metal terminals were cut into 6 equal pieces in the length direction (MD), each with a width of 25 mm. Next, the laminate was folded in half in the length direction (MD) with the heat-sealable resin layers of the all-solid-state battery exterior material (exterior material) facing inward (TD 30 mm x MD 75 mm), and the adhesive film for metal terminals was inserted between the pieces. A metal terminal (25 mm wide x 20 mm long) was sandwiched between the adhesive film for metal terminals. The metal terminal with the adhesive film for metal terminals was sandwiched against the inside fold of the exterior material, with the MD of the adhesive film for metal terminals perpendicular to the MD of the exterior material. In this state, the laminate was heat-sealed at 240°C, 1.0 MPa, and 12 seconds using a 7 mm wide upper and lower metal head sealer. The heat-sealed portion of the resulting laminate consisted of exterior material / adhesive film for metal terminal / metal terminal / adhesive film for metal terminal / exterior material stacked in this order. Next, the laminate was cut perpendicular to the 7 mm seal width to obtain 15 mm wide samples. The samples were taken from the center of the laminate. Next, the exterior material and metal terminal on one side of the sample were chucked, and the exterior material and metal terminal were pulled in a tensile tester with a thermostatic chamber at 150°C in a 180°C direction at a rate of 300 mm / min. The seal strength at 150°C was measured.

[0146] [Sealing performance evaluation] <Conformity to metal terminals> The adhesive film for metal terminals was cut to a size of 55 mm x 10 mm, and two sheets of adhesive film for metal terminals were prepared. Additionally, aluminum alloy metal terminals (45 mm wide, 60 mm long, 400 μm thick) were prepared. As shown in the schematic diagram in Figure 6, the polyolefin resin layer of the adhesive film for metal terminals was placed on both sides of the center of the metal terminal, facing the metal terminal side. The metal terminals were then heat-sealed at 200°C for 12 seconds using a metal-head flat press equipped with 3.0 mm thick, 40-hardness silicone rubber on both the top and bottom at 0.25 MPa (surface pressure applied to the silicone rubber). The metal terminals with adhesive film for metal terminals were then observed using a magnifying glass (20x magnification) to confirm the appearance of the area around the metal terminal where the adhesive film for metal terminals was heat-sealed. The evaluation criteria were as follows: A: The adhesive film conforms to the shape of the metal terminal, and no gaps are formed between the metal terminal and the adhesive film. B: The adhesive film generally conforms to the shape of the metal terminal, and there is a small gap between the metal terminal and the adhesive film. C: The adhesive film did not conform to the shape of the metal terminal sufficiently, and there was a large gap between the metal terminal and the adhesive film.

[0147] <Heat shrinkage of adhesive film> The adhesive film for metal terminals was cut to a size of 10 mm x 120 mm, and marked lines were added at 100 mm intervals. The adhesive film for metal terminals was then hung and heated in an oven at 190°C for 3 minutes, and the length between the marked lines was measured. The length retention rate of the marked line interval (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 of the gauge interval is 0.7 or more, and thermal shrinkage is sufficiently suppressed. C: The length maintenance rate of the gauge interval is less than 0.7, and the suppression of thermal shrinkage is insufficient.

[0148] [Table 1]

[0149] In the layer configurations shown in Table 1, h-PPa means homopolypropylene modified with maleic anhydride, r-PPa means random polypropylene modified with maleic anhydride, h-IP means imine-modified homopolypropylene, r-IP means imine-modified random polypropylene, and h-PBT means homopolybutylene terephthalate, and the numbers in parentheses indicate the thickness (μm).

[0150] As described above, the present disclosure provides the following aspects of the invention. Item 1. An adhesive film for metal terminals that is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, The adhesive film for metal terminals is composed of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order. Item 2. The adhesive film for metal terminal according to Item 1, wherein the polyolefin resin layer constitutes the surface of the adhesive film for metal terminal on the side of the metal terminal. Item 3. The adhesive film for metal terminal according to Item 1 or 2, wherein the melting point of the polyester-based resin layer is at least 20° C. higher than the melting point of the polyolefin-based resin layer. Item 4. The adhesive film for a metal terminal according to any one of Items 1 to 3, wherein the polyester-based resin layer contains a polyester-based resin and an elastomer. Item 5. The adhesive film for metal terminal according to any one of Items 1 to 4, wherein the melting point of the polyolefin resin layer is 155° C. or higher. Item 6. The adhesive film for metal terminal according to any one of Items 1 to 5, wherein the imine-modified polyolefin resin layer has a melting point of 140° C. or higher. Item 7. The adhesive film for a metal terminal according to any one of Items 1 to 6, wherein the adhesive film for a metal terminal has a thickness of 50 μm or more and 500 μm or less. Item 8. The adhesive film for metal terminal according to any one of Items 1 to 7, wherein the exterior packaging material for an electricity storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside. Item 9. A metal terminal with an adhesive film for a metal terminal, comprising the adhesive film for a metal terminal according to any one of Items 1 to 8 attached to a metal terminal. Item 10. An electricity storage device including at least the electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, the electricity storage device casing material that seals the electricity storage device element, and the metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and that protrude outside the electricity storage device casing material, Item 9. An electricity storage device, wherein the adhesive film for a metal terminal according to any one of items 1 to 8 is interposed between the metal terminal and the exterior material for an electricity storage device. Item 11. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, A method for manufacturing an electricity storage device, comprising a step of interposing the adhesive film for metal terminal according to any one of items 1 to 8 between the metal terminal and the exterior material for an electricity storage device, and sealing the electricity storage device element with the exterior material for an electricity storage device. Item 12. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: A method for producing an adhesive film for metal terminals, which produces an adhesive film for metal terminals consisting of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order. [Explanation of symbols]

[0151] 1. Adhesive film for metal terminals 2 metal terminals 3. Exterior materials for energy storage devices 3a Peripheral part of the exterior material for the electricity storage device 4. Energy storage device elements 10. Energy storage devices 11 Polyester resin layer 12 Polyolefin resin layer 13 Imine-modified polyolefin resin layer 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, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, The adhesive film for metal terminals is composed of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order.

2. The adhesive film for a metal terminal according to claim 1 , wherein the polyolefin-based resin layer constitutes the surface of the adhesive film for a metal terminal on the side of the metal terminal.

3. The adhesive film for a metal terminal according to claim 1 or 2, wherein the melting point of the polyester-based resin layer is higher by 20° C. or more than the melting point of the polyolefin-based resin layer.

4. The adhesive film for metal terminal according to any one of claims 1 to 3, wherein the polyester-based resin layer contains a polyester-based resin and an elastomer.

5. The adhesive film for metal terminal according to any one of claims 1 to 4, wherein the melting point of the polyolefin resin layer is 155°C or higher.

6. The adhesive film for metal terminals according to any one of claims 1 to 5, wherein the melting point of the imine-modified polyolefin resin layer is 140°C or higher.

7. The adhesive film for metal terminal according to any one of claims 1 to 6, wherein the thickness of the adhesive film for metal terminal is 50 µm or more and 500 µm or less.

8. The electrical storage device packaging material is composed of a laminate having, from the outside, at least a base material 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 7.

9. A metal terminal with an adhesive film for a metal terminal, comprising the adhesive film for a metal terminal according to any one of claims 1 to 8 attached to a metal terminal.

10. an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electricity storage device that seals the electricity storage device element; and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, An electricity storage device, comprising the adhesive film for metal terminals according to any one of claims 1 to 8 interposed between the metal terminals and the exterior material for electricity storage devices.

11. a manufacturing method for an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electricity storage device that seals the electricity storage device element; and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, A method for manufacturing an electricity storage device, comprising a step of interposing the adhesive film for metal terminals according to any one of claims 1 to 8 between the metal terminals and the exterior material for electricity storage devices, and sealing the electricity storage device elements with the exterior material for electricity storage devices.

12. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: A method for producing an adhesive film for metal terminals, which produces an adhesive film for metal terminals consisting of a laminate having at least a polyester-based resin layer, an imine-modified polyolefin-based resin layer, and a polyolefin-based resin layer in this order.

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