Adhesive film for metal terminal, method for manufacturing adhesive film for metal terminal, metal terminal with adhesive film for metal terminal, electricity storage device using said adhesive film for metal terminal, and method for manufacturing electricity storage device

Abstract

The present invention provides an adhesive film for metal terminals, said adhesive film being capable of achieving high sealing performance between itself and a thermally fusible resin layer of an outer covering material in a short time, while being suppressed in collapse due to heat sealing and having excellent followability.　An adhesive film for metal terminals, said adhesive film being interposed between a metal terminal that is electrically connected to an electrode of an electricity storage device element, and an outer covering material for electricity storage devices, said outer covering material sealing the electricity storage device element. This adhesive film for metal terminals is configured from a multilayer body which is sequentially provided, in the following order, with: a first polyolefin layer that is arranged on the metal terminal side; a base material; and a second polyolefin layer that is arranged on the outer covering material for electricity storage devices side. The heat of fusion ∆H1 of the first polyolefin layer and the heat of fusion ∆H2 of the second polyolefin layer as determined in accordance with JIS K 7122 (2012) satisfy the relational expression ∆H1 > ∆H2; and the heat of fusion ∆H3 of the base material as determined in accordance with JIS K 7122 (2012) is 70 J / g or more.

Description

[Technical Field]

[0001] The present disclosure relates to an adhesive film for metal terminals, a method for manufacturing an adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals, an electricity storage device using the adhesive film for metal terminals, 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 material 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 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] As described above, the adhesive film disposed between the heat-sealable resin layer and the metal terminal of the packaging material for an electricity storage device is required to have adhesion to the heat-sealable resin layer and the metal terminal by heat sealing.

[0008] In the process of bonding a metal terminal and an electrical storage device exterior material via an adhesive film, the metal terminal and the adhesive film are generally heat-sealed to prepare a metal terminal with an adhesive film in advance. Next, in a state where the heat-sealable resin layers are opposed to each other at the periphery of the electrical storage device exterior material, the metal terminal with the adhesive film is interposed between the opposing heat-sealable resin layers, and the periphery is heat-sealed, thereby heat-sealing the heat-sealable resin layers to each other and between the heat-sealable resin layer and the adhesive film, thereby sealing the electrical storage device element with the electrical storage device exterior material.

[0009] In this way, the adhesive film is subjected to heat sealing at least twice: once when it is bonded to the metal terminal and once when it is bonded to the heat-fusible resin layer of the exterior packaging material for an electricity storage device.

[0010] Furthermore, when adhering an adhesive film to a metal terminal, it is common for heat and pressure to be applied multiple times, such as a temporary adhesion process and a final adhesion process. The temporary adhesion process is a process in which the adhesive film is temporarily attached to the metal terminal and air bubbles are removed, and the final adhesion process is a process in which heat and pressure are applied one or more times at higher temperatures than in the temporary adhesion process to adhere the adhesive film to the metal terminal.

[0011] Therefore, the adhesive film is subjected to heating and pressure by heat sealing multiple times before the electrical storage device exterior material is sealed. This causes a problem that the adhesive film is crushed and its thickness is reduced by the multiple heat sealings at high temperature and high pressure before the electrical storage device exterior material is sealed. If the thickness of the adhesive film is reduced, the sealing ability of the electrical storage device exterior material is likely to be reduced.

[0012] Furthermore, in order to improve the productivity of electricity storage devices, it is necessary to shorten the heat sealing time (i.e., the time for applying heat and pressure) of the electrical storage device packaging material. If the time for heat sealing the peripheral edge of the electrical storage device packaging material is reduced from 3 seconds to 1 second, for example, the heat sealing time will be reduced to one-third, thereby improving productivity. However, if the heat sealing is performed for a short time, there is a problem in that it is difficult to obtain high adhesion between the heat-fusible resin layer of the electrical storage device packaging material and the adhesive film.

[0013] Furthermore, when the heat-sealable resin layer and adhesive film of the electrical storage device packaging material are heat-sealed in a short time, the adhesive film does not conform sufficiently to the electrical storage device packaging material during heat sealing, and gaps remain between the adhesive film and the heat-sealable resin layer, which can lead to a problem that the sealing ability of the electrical storage device is easily reduced.

[0014] In light of these circumstances, a primary object of the present disclosure is to provide an adhesive film for metal terminals that can achieve high sealing performance with a heat-sealable resin layer of an electrical storage device exterior material in a short time, that is suppressed from collapsing due to heat sealing, and that has excellent conformability of the adhesive film to the electrical storage device exterior material during heat sealing. Further objects of the present disclosure include providing 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 electrical storage device that uses the adhesive film for metal terminals, and a method for manufacturing the electrical storage device. [Means for solving the problem]

[0015] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. As a result, they found that in an adhesive film for metal terminals composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electrical storage device exterior material side, by setting the heat of fusion ΔH1 of the first polyolefin layer and the heat of fusion ΔH2 of the second polyolefin layer to satisfy the relationship ΔH1 > ΔH2 and further setting the heat of fusion ΔH3 of the substrate to 70 J / g or more, it is possible to obtain an adhesive film for metal terminals that can achieve high sealing performance with the heat-sealable resin layer of the electrical storage device exterior material in a short period of time, suppress collapse due to heat sealing, and exhibit excellent conformability to the electrical storage device exterior material during heat sealing. The present disclosure was completed through further research based on this finding.

[0016] 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 terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the exterior material side for an electricity storage device; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; An adhesive film for metal terminals, wherein the heat of fusion ΔH3 of the substrate is 70 J / g or more, as measured in accordance with the provisions of JIS K 7122:2012. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide an adhesive film for metal terminals that can achieve high sealing performance with a heat-sealable resin layer of an electrical storage device exterior material in a short time, is suppressed from collapsing due to heat sealing, and has excellent conformability to the electrical storage device exterior material.Furthermore, the present disclosure also aims to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with an adhesive film for metal terminals that uses the adhesive film for metal terminals, an electrical storage device that uses the adhesive film for metal terminals, and a method for manufacturing the electrical storage device. [Brief explanation of the drawings]

[0018] [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 adhesive film for metal terminals according to the present disclosure. [Figure 6] 1 is a schematic cross-sectional view of an exterior material for an electricity storage device according to the present disclosure. [Figure 7] FIG. 2 is a schematic cross-sectional view of a portion where heat-fusible resin layers are heat-sealed together via a metal terminal with an adhesive film in an example. [Figure 8] FIG. 2 is a schematic diagram illustrating a method for preparing samples for evaluating adhesion, conformability, and crushing in the examples. [Figure 9] FIG. 2 is a schematic diagram illustrating a method for preparing samples for evaluating adhesion, conformability, and crushing in the examples. [Figure 10] FIG. 2 is a schematic diagram illustrating a method for preparing a sample for evaluating tracking ability in the examples. [Figure 11] 1 is a DSC curve obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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 seals the electricity storage device element, and is composed of a laminate having, in this order, a first polyolefin layer that is arranged on the metal terminal side, a substrate, and a second polyolefin layer that is arranged on the exterior material for an electricity storage device, and is characterized in that the heat of fusion ΔH1 of the first polyolefin layer and the heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1 > ΔH2, and the heat of fusion ΔH3 of the substrate, measured in accordance with the provisions of JIS K 7122:2012, is 70 J / g or more.

[0020] Because the adhesive film for metal terminals of the present disclosure has these characteristics, it can achieve high sealing performance with the heat-sealable resin layer of the exterior material in a short period of time, suppressing crushing due to heat sealing, and also has excellent conformability to the exterior material for the energy storage device.

[0021] The present disclosure also provides 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 encapsulates the electricity storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding outside the exterior material for an electricity storage device, wherein the adhesive film for a metal terminal of the present disclosure is interposed between the metal terminal and the exterior material for an electricity storage device. The adhesive film for a metal terminal and a method for manufacturing the same of the present disclosure, and an electricity storage device using the adhesive film for a metal terminal and a method for manufacturing the same are described in detail below.

[0022] 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.

[0023] Another method for confirming the MD (Machine Direction) of an adhesive film for metal terminals is to observe a cross section of the adhesive film for metal terminals (e.g., a cross section of the first polyolefin layer, the substrate, or the second polyolefin 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, using an electron microscope, a cross section in the length direction of the adhesive film for metal terminals and each cross section at an angle of 10 degrees from the direction parallel to the cross section in the length direction up to the direction perpendicular to the cross section in the length direction (a total of 10 cross sections). 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 the 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 where the average diameter y of the island shape was the largest was determined to be the MD.

[0024] 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.

[0025] In the present disclosure, the temporary bonding step of the adhesive film for metal terminal to the metal terminal is carried out, for example, at a temperature of about 140 to 160°C, under a pressure of about 0.01 to 1.0 MPa, for about 3 to 15 seconds, and about 3 to 6 cycles, while the main bonding step is carried out, for example, at a temperature of about 160 to 240°C, under a pressure of about 0.01 to 1.0 MPa, for about 3 to 15 seconds, and about 1 to 3 cycles. Furthermore, when the metal terminal with the adhesive film is interposed in the exterior material for an electricity storage device and heat-sealed, the heating temperature is typically in the range of about 180 to 210°C, and the pressure is typically about 1.0 to 2.0 MPa, for about 3 to 5 seconds, and about 1 cycle. Since the adhesive film of the present disclosure can achieve high sealing performance in a short time when combined with the heat-sealable resin layer of the exterior material, the heat sealing time when heat-sealing the exterior material for an electricity storage device with a metal terminal with an adhesive film interposed therebetween can be set to about 0.5 to 3 seconds, about 0.5 to 2 seconds, or even about 0.5 to 1 second.

[0026] 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.

[0027] As shown in Figures 4 and 5, the adhesive film 1 for metal terminals of the present disclosure has a configuration in which at least a first polyolefin layer 12a, a substrate 11, and a second polyolefin layer 12b are laminated in this order. The first polyolefin layer 12a is disposed on the metal terminal 2 side. The second polyolefin layer 12b is disposed on the electricity storage device exterior packaging material 3 side. In the adhesive film 1 for metal terminals of the present disclosure, the first polyolefin layer 12a and the second polyolefin layer 12b are located on the surfaces of both sides, respectively.

[0028] In the adhesive film for metal terminal 1 of the present disclosure, the first polyolefin layer 12a and the second polyolefin layer 12b are each a layer containing a polyolefin-based resin. Examples of polyolefin-based resins include polyolefin and acid-modified polyolefin. The first polyolefin layer 12a preferably contains an acid-modified polyolefin among polyolefin-based resins, and is more preferably a layer formed from an acid-modified polyolefin. The second polyolefin layer 12b preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, and is more preferably a layer formed from a polyolefin.

[0029] Furthermore, the substrate 11 preferably contains a polyolefin resin, preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin.

[0030] In the first polyolefin layer 12a, the second polyolefin layer 12b, and the substrate 11, the polyolefin resin is preferably a polypropylene resin, the polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene. Note that polyolefin resins such as polyolefins and acid-modified polyolefins may contain known additives, fillers, pigments, etc., which will be described later.

[0031] Specific examples of preferred laminate structures for the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from polypropylene are laminated in this order; a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from acid-modified polypropylene are laminated in this order; and among these, a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from polypropylene are laminated in this order is particularly preferred.

[0032] The materials constituting the first polyolefin layer 12a, the second polyolefin layer 12b and the substrate 11 will be described in detail below.

[0033] 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) of the exterior material 3 for electricity storage devices are bonded via the adhesive film 1 for metal terminals. The first polyolefin layer 12a of the adhesive film 1 for metal terminals is placed on the metal terminal 2 side, and the second polyolefin layer 12b is placed on the exterior material 3 for electricity storage devices, with the first polyolefin layer 12a in close contact with the metal terminal 2 and the second polyolefin layer 12b in close contact with the heat-sealable resin layer 35 of the exterior material 3 for electricity storage devices.

[0034] In the adhesive film for metal terminal 1 of the present disclosure, the heat of fusion ΔH1 of the first polyolefin layer 12a and the heat of fusion ΔH2 of the second polyolefin layer 12b, measured in accordance with JIS K 7122:2012, satisfy the relationship ΔH1 > ΔH2. Furthermore, the heat of fusion ΔH3 of the substrate 11, measured in accordance with JIS K 7122:2012, is 70 J / g or more. In the present disclosure, the heat of fusion is measured as follows.

[0035] <Measurement of heat of fusion> The heat of fusion of each sample is measured according to the JIS K 7122:2012 standard. Measurements are performed using a differential scanning calorimeter (DSC, e.g., a TA Instruments Q200). The sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a rate of 10°C / min. The first heat of fusion, ΔH (J / g), is measured, and the sample is then held at 210°C for 10 minutes. The sample is then cooled from 210°C to -50°C at a rate of 10°C / min and held for 15 minutes. The sample is then heated from -50°C to 210°C at a rate of 10°C / min. The second heat of fusion, ΔH (J / g), is measured. The nitrogen gas flow rate is 50 ml / min. The value of the heat of fusion, ΔH (J / g), measured in the first measurement is used. The heat of fusion is the area enclosed by the baseline (the line formed by connecting the start and end points of the ridge from base to base) and the peak in the DSC curve. The measurement sample can be obtained by obtaining the first polyolefin layer and the second polyolefin layer from the adhesive film for metal terminals. The heat of fusion of the substrate can be determined by measuring the heats of fusion of the first polyolefin layer, the second polyolefin layer, and the adhesive film for metal terminals, and then subtracting the heats of fusion of the first and second polyolefin layers from the heat of fusion measured for the adhesive film for metal terminals to determine the heat of fusion of the substrate.

[0036] The heat of fusion of the substrate, the first polyolefin layer, the second polyolefin layer, and the adhesive film for metal terminals can be adjusted by the composition of each resin (e.g., the blending ratio of polyethylene components, etc.), molecular skeleton, dispersibility, molecular weight, melting point, MFR, and further conditions such as the T-die and inflation used in producing the adhesive film for metal terminals (e.g., the extrusion width from the T-die, stretching ratio, stretching speed, heat treatment temperature, and further the line speed during extrusion, cooling speed, extrusion temperature, etc.).

[0037] In the adhesive film for metal terminal 1 of the present disclosure, from the viewpoint of further improving the high short-term sealing performance, suppression of collapse, and conformability, the difference between the heat of fusion ΔH1 of the first polyolefin layer 12a and the heat of fusion ΔH2 of the second polyolefin layer 12b is preferably about 3.0 J / g or more, more preferably about 5.0 J / g or more, and even more preferably about 10.0 J / g or more. From the same viewpoint, the difference is preferably about 18.0 J / g or less, more preferably about 15.0 J / g or less, and even more preferably about 12.0 J / g or less. Preferred ranges for the difference include about 3.0 to 18.0 J / g, about 3.0 to 15.0 J / g, about 3.0 to 12.0 J / g, about 5.0 to 18.0 J / g, about 5.0 to 15.0 J / g, about 5.0 to 12.0 J / g, about 10.0 to 18.0 J / g, about 10.0 to 15.0 J / g, and about 10.0 to 12.0 J / g. In particular, from the viewpoint of suppressing crushing of the adhesive film 1 for metal terminals, it is preferable that the difference be about 3.0 J / g or more.

[0038] From the same viewpoint, the difference between the heat of fusion ΔH3 of the substrate 11 and the heat of fusion ΔH1 of the first polyolefin layer 12a is preferably about 15.0 J / g or more, more preferably about 18.0 J / g or more, and even more preferably about 21.0 J / g or more. From the same viewpoint, the difference is preferably about 35.0 J / g or less, more preferably about 32.0 J / g or less, and even more preferably about 29.0 J / g or less. Preferred ranges for the difference include about 15.0 to 35.0 J / g, about 15.0 to 32.0 J / g, about 15.0 to 29.0 J / g, about 18.0 to 35.0 J / g, about 18.0 to 32.0 J / g, about 18.0 to 29.0 J / g, about 21.0 to 35.0 J / g, about 21.0 to 32.0 J / g, and about 21.0 to 29.0 J / g. In particular, from the viewpoint of suppressing crushing of the adhesive film 1 for metal terminals, it is preferable that the difference be about 15.0 J / g or more.

[0039] From the same viewpoint, it is preferable that the heat of fusion ΔH1 of the first polyolefin layer 12a, the heat of fusion ΔH2 of the second polyolefin layer 12b, and the heat of fusion ΔH3 of the base material 11 satisfy the relationship ΔH3≧ΔH1>ΔH2, and it is more preferable that the relationship ΔH3>ΔH1>ΔH2 be satisfied. Among the heat of fusion ΔH1 of the first polyolefin layer 12a, the heat of fusion ΔH2 of the second polyolefin layer 12b, and the heat of fusion ΔH3 of the base material 11, the heat of fusion ΔH3 of the base material 11 is the largest, so that crushing of the adhesive film 1 can be suitably suppressed. Furthermore, by satisfying this relationship, when the outer casing material 3 for an electricity storage device is heat-sealed with a metal terminal with an adhesive film interposed therebetween, the substrate 11 absorbs the excess heat transferred from the second polyolefin layer 12b side to the first polyolefin layer 12a, thereby suppressing a decrease in adhesion to the metal terminal 2 due to excessive heating of the first polyolefin layer 12a.

[0040] From a similar viewpoint, the absolute value of the difference between the heat of fusion ΔH4 of the heat-sealable resin layer 35 of the packaging material 3 for an electrical storage device in which the adhesive film for metal terminal 1 is used and the heat of fusion ΔH2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0.0 to 5.0 J / g, and more preferably about 0.0 to 3.0 J / g. The smaller the absolute value of the difference between the heat of fusion ΔH4 and the heat of fusion ΔH2 (i.e., the closer the absolute value of the difference is to 0.0 J / g), the easier it is to improve the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35. In particular, from the viewpoint of the short-term sealing properties and conformability of the adhesive film for metal terminal 1, it is preferable that the difference be about 0.0 J / g or more.

[0041] In the adhesive film for metal terminal 1 of the present disclosure, from the viewpoint of further improving the high short-term sealing performance, crushing prevention, and conformability described above, the heat of fusion ΔH1 of the first polyolefin layer 12a disposed on the metal terminal 2 side is preferably about 30.0 J / g or more, more preferably about 45.0 J / g or more. From the same viewpoint, the heat of fusion ΔH1 is preferably about 80.0 J / g or less, more preferably about 60.0 J / g or less. Preferred ranges for the heat of fusion ΔH1 include about 30.0 to 80.0 J / g, about 30.0 to 60.0 J / g, about 45.0 to 80.0 J / g, and about 45.0 to 60.0 J / g. Furthermore, from the viewpoint of improving the film-forming properties of the first polyolefin layer 12a, the heat of fusion ΔH1 is preferably not more than about 60.0 J / g, more preferably not more than 58.5 J / g, and preferred ranges are about 30.0 to 60.0 J / g, about 30.0 to 58.5 J / g, about 45.0 to 60.0 J / g, and about 45.0 to 58.5 J / g.

[0042] From the same viewpoint, the heat of fusion ΔH2 of the second polyolefin layer 12b disposed on the side of the electrical storage device sheathing material 3 is preferably about 20.0 J / g or more, more preferably about 35.0 J / g or more. From the same viewpoint, the heat of fusion ΔH2 is preferably about 70.0 J / g or less, more preferably about 55.0 J / g or less. Preferred ranges for the heat of fusion ΔH2 include about 20.0 to 70.0 J / g, about 20.0 to 55.0 J / g, about 35.0 to 70.0 J / g, and about 35.0 to 55.0 J / g. In particular, from the viewpoint of the short-term sealing properties and conformability of the adhesive film 1 for metal terminals, the heat of fusion ΔH2 is preferably about 55.0 J / g or less.

[0043] From the same viewpoint, the heat of fusion ΔH3 of the substrate 11 is 70.0 J / g or more, preferably about 75.0 J / g or more, and more preferably about 80.0 J / g or more. From the same viewpoint, the heat of fusion ΔH3 is preferably about 100.0 J / g or less, and more preferably about 90.0 J / g or less. Preferred ranges for the heat of fusion ΔH1 include about 70.0 to 100.0 J / g, about 70.0 to 90.0 J / g, about 75.0 to 100.0 J / g, about 75.0 to 90.0 J / g, about 80.0 to 100.0 J / g, and about 80.0 to 90.0 J / g. In particular, from the viewpoint of suppressing collapse of the adhesive film for metal terminal 1, the heat of fusion ΔH3 is preferably about 70.0 J / g or more.

[0044] In addition, in order to further improve the high short-term sealing performance, crushing suppression, and conformability of the adhesive film 1 for metal terminals of the present disclosure, it is preferable that the melting peak temperature mp1 of the first polyolefin layer 12a and the melting peak temperature mp2 of the second polyolefin layer 12b satisfy the relationship mp1 > mp2. In the present disclosure, the melting peak temperatures are measured as follows.

[0045] <Measurement of melting peak temperature> The melting peak temperature of each sample is measured in accordance with JIS K7121:2012 (Method for measuring transition temperatures of plastics (JIS K7121:1987, Supplement 1)). Measurements are performed using a differential scanning calorimeter (DSC, e.g., a TA Instruments Q200 differential scanning calorimeter). The sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min. The first melting peak temperature, P (°C), is measured, and the sample is then held at 210°C for 10 minutes. The sample is then cooled from 210°C to -50°C at a heating rate of 10°C / min and held for 15 minutes. The sample is then heated from -50°C to 210°C at a heating rate of 10°C / min. The second melting peak temperature, Q (°C), is measured. The nitrogen gas flow rate is 50 ml / min. Using the above procedure, the melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time are determined. The value of the melting peak temperature P (°C) measured the first time using the above procedure is used.

[0046] From the same viewpoint, the melting peak temperature mp1 of the first polyolefin layer 12a disposed on the metal terminal 2 side is preferably about 130°C or higher, more preferably about 135°C or higher. From the same viewpoint, the melting peak temperature mp1 is preferably about 160°C or lower, more preferably about 150°C or lower. Preferred ranges for the melting peak temperature mp1 include about 130 to 160°C, about 130 to 150°C, about 135 to 160°C, and about 135 to 150°C.

[0047] From the same viewpoint, the melting peak temperature mp2 of the second polyolefin layer 12b arranged on the side of the packaging material 3 for an electricity storage device is preferably about 130°C or higher, and more preferably about 135°C or higher. From the same viewpoint, the melting peak temperature mp2 is preferably about 160°C or lower, and more preferably about 150°C or lower. Preferred ranges for the melting peak temperature mp2 include about 130 to 160°C, about 130 to 150°C, about 135 to 160°C, and about 135 to 150°C.

[0048] From the same viewpoint, the melting peak temperature mp3 of the substrate 11 is 140°C or higher, preferably about 150°C or higher, and more preferably about 160°C or higher. From the same viewpoint, the melting peak temperature mp3 is preferably about 180°C or lower, and more preferably about 170°C or lower. Preferred ranges for the melting peak temperature mp3 include about 140 to 180°C, about 140 to 170°C, about 150 to 180°C, about 150 to 170°C, about 160 to 180°C, and about 160 to 170°C.

[0049] From the same viewpoint, the absolute value of the difference between the melting peak temperature mp1 of the first polyolefin layer 12a and the melting peak temperature mp2 of the second polyolefin layer 12b is preferably about 0 to 10°C, more preferably about 0 to 5°C.

[0050] From a similar viewpoint, the melting peak temperature mp3 of the substrate 11 is preferably greater than the melting peak temperature mp1 of the first polyolefin layer 12a, and the difference between the melting peak temperature mp3 of the substrate 11 and the melting peak temperature mp1 of the first polyolefin layer 12a (melting peak temperature mp3 - melting peak temperature mp1) is preferably about 10°C or greater, more preferably about 15°C or greater, and even more preferably about 20°C or greater. From a similar viewpoint, the difference is preferably about 30°C or less, more preferably about 27°C or less, and even more preferably about 25°C or less. Preferred ranges for the difference include about 10 to 30°C, about 10 to 27°C, about 10 to 25°C, about 15 to 30°C, about 15 to 27°C, about 15 to 25°C, about 20 to 30°C, about 20 to 27°C, and about 20 to 25°C.

[0051] From a similar viewpoint, it is preferable that the melting peak temperature mp1 of the first polyolefin layer 12a, the melting peak temperature mp2 of the second polyolefin layer 12b, and the melting peak temperature mp3 of the substrate 11 satisfy the relationship mp3≧mp1>mp2, and it is more preferable that they satisfy the relationship mp3>mp1>mp2.

[0052] From a similar perspective, the absolute value of the difference between the peak melting temperature mp4 of the heat-sealable resin layer 35 of the packaging material 3 for an electrical storage device in which the adhesive film for metal terminal 1 is used and the peak melting temperature mp2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0 to 5°C, for example about 0 to 3°C. The smaller the absolute value of the difference between the peak melting temperature mp4 and the peak melting temperature mp2 (i.e., the closer the absolute value of the difference is to 0°C), the easier it is to improve the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35. In particular, the smaller the absolute value of the difference between the peak melting temperature mp4 and the peak melting temperature mp2, the more likely it is that the adhesive film for metal terminal 1 of the present disclosure will be able to further improve the high short-term sealing performance and conformability described above.

[0053] In addition, in order to further improve the high short-term sealing performance, crushing suppression, and conformability of the adhesive film 1 for metal terminals of the present disclosure, it is preferable that the melt mass-flow rate (MFR) T1 of the first polyolefin layer 12a and the melt mass-flow rate (MFR) T2 of the second polyolefin layer 12b satisfy the relationship T2>T1. In the present disclosure, the melt mass-flow rate (MFR) is measured as follows.

[0054] <Melt Mass Flow Rate (MFR) Measurement> For each measurement sample, the melt mass flow rate (g / 10 min) is measured using a melt indexer at a measurement temperature of 230°C and a load of 2.16 kg. For polyolefins, for example, a method conforming to Method A of JIS K7210:2014 can be used. Alternatively, the measurement sample can be obtained by obtaining the first polyolefin layer, the second polyolefin layer, and the substrate from the adhesive film for metal terminals.

[0055] From the same viewpoint, the melt mass-flow rate (MFR) T1 of the first polyolefin layer 12a disposed on the metal terminal 2 side is preferably about 5.0 g / 10 min or more, more preferably about 6.0 g / 10 min or more. From the same viewpoint, the melt mass-flow rate (MFR) T1 is preferably about 10.0 g / 10 min or less, more preferably about 8.0 g / 10 min or less. Preferred ranges for the melt mass-flow rate (MFR) T1 include about 5.0 to 10.0 g / 10 min, about 5.0 to 8.0 g / 10 min, about 6.0 to 10.0 g / 10 min, and about 6.0 to 8.0 g / 10 min.

[0056] From the same viewpoint, the melt mass-flow rate (MFR) T2 of the second polyolefin layer 12b disposed on the side of the electrical storage device packaging material 3 is preferably about 8.0 g / 10 min or more, more preferably about 10.0 g / 10 min or more. From the same viewpoint, the melt mass-flow rate (MFR) T2 is preferably about 15.0 g / 10 min or less, more preferably about 13.0 g / 10 min or less. Preferred ranges for the melt mass-flow rate (MFR) T2 include about 8.0 to 15.0 g / 10 min, about 8.0 to 13.0 g / 10 min, about 10.0 to 15.0 g / 10 min, and about 10.0 to 13.0 g / 10 min.

[0057] From the same viewpoint, the melt mass-flow rate (MFR) T3 of the substrate 11 is 1.0 g / 10 min or more, preferably about 1.5 g / 10 min or more, and more preferably about 2.0 g / 10 min or more. From the same viewpoint, the melt mass-flow rate (MFR) T3 is preferably about 5.0 g / 10 min or less, and more preferably about 4.0 g / 10 min or less. Preferred ranges of the melt mass-flow rate (MFR) T3 include about 1.0 to 5.0 g / 10 min, about 1.0 to 4.0 g / 10 min, about 1.5 to 5.0 g / 10 min, about 1.5 to 4.0 g / 10 min, about 2.0 to 5.0 g / 10 min, and about 2.0 to 4.0 g / 10 min.

[0058] The absolute value of the difference between the melt mass flow rate (MFR) T1 of the first polyolefin layer 12a and the melt mass flow rate (MFR) T2 of the second polyolefin layer 12b is preferably about 2.0 to 6.0 g / 10 min, and more preferably about 3.0 to 5.0 g / 10 min.

[0059] From the same viewpoint, the melt mass-flow rate (MFR) T1 of the first polyolefin layer 12a is preferably larger than the melt mass-flow rate (MFR) T3 of the substrate 11, and the difference between the melt mass-flow rate (MFR) T3 of the substrate 11 and the melt mass-flow rate (MFR) T1 of the first polyolefin layer 12a (melt mass-flow rate (MFR) T3 - melt mass-flow rate (MFR) T1) is preferably about 2.0 g / 10 min or more, more preferably about 2.5 g / 10 min or more, and even more preferably about 3.0 g / 10 min or more. From the same viewpoint, the difference is preferably about 6.0 g / 10 min or less, more preferably about 5.5 g / 10 min or less, and even more preferably about 5.0 g / 10 min or less. Preferred ranges of the difference include about 2.0 to 6.0 g / 10 min, about 2.0 to 5.5 g / 10 min, about 2.0 to 5.0 g / 10 min, about 2.5 to 6.0 g / 10 min, about 2.5 to 5.5 g / 10 min, about 2.5 to 5.0 g / 10 min, about 3.0 to 6.0 g / 10 min, about 3.0 to 5.5 g / 10 min, and about 3.0 to 5.0 g / 10 min.

[0060] From a similar viewpoint, it is preferable that the melt mass flow rate (MFR) T1 of the first polyolefin layer 12a, the melt mass flow rate (MFR) T2 of the second polyolefin layer 12b, and the melt mass flow rate (MFR) T3 of the substrate 11 satisfy the relationship T2>T1>T3.

[0061] From a similar viewpoint, the absolute value of the difference between the melt mass-flow rate (MFR) T4 of the heat-sealable resin layer 35 of the packaging material for an electricity storage device in which the adhesive film for metal terminal 1 is used and the melt mass-flow rate (MFR) T2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0.0 to 5.0 g / 10 min, or about 0.0 to 3.0 g / 10 min. The smaller the absolute value of the difference between the melt mass-flow rate (MFR) T4 and the melt mass-flow rate (MFR) T2 (i.e., the closer the absolute value of the difference is to 0.0 g / 10 min), the easier it is to improve the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35. In particular, the smaller the absolute value of the difference between the melt mass-flow rate (MFR) T4 and the melt mass-flow rate (MFR) T2, the more the adhesive film for metal terminal 1 of the present disclosure can further improve the high sealing properties and conformability in a short period of time.

[0062] In order to further improve the high short-term sealing performance, crush suppression, and conformability of the adhesive film 1 for metal terminal of the present disclosure, the total thickness of the adhesive film 1 for metal terminal is, for example, about 60 μm or more, preferably about 80 μm or more, more preferably about 100 μm or more, more preferably about 120 μm or more, and even more preferably about 150 μm or more. The total thickness of the adhesive film 1 for metal terminal of the present disclosure is preferably about 300 μm or less, more preferably 220 μm or less. Preferred ranges for the total thickness of the adhesive film 1 for metal terminal of the present disclosure include about 60 to 300 μm, about 60 to 220 μm, about 80 to 300 μm, about 80 to 220 μm, about 100 to 300 μm, about 100 to 220 μm, about 120 to 300 μm, about 120 to 220 μm, about 150 to 300 μm, and about 150 to 220 μm. More specific examples include, for example, when the adhesive film 1 for metal terminal of the present disclosure is used in a consumer electricity storage device, the total thickness is preferably about 60 to 100 μm, and when used in an in-vehicle electricity storage device, the total thickness is preferably about 100 to 220 μm.

[0063] The materials constituting the first polyolefin layer 12a, the second polyolefin layer 12b, and the substrate 11, their thicknesses, etc. will be described in detail below.

[0064] [First Polyolefin Layer 12a and Second Polyolefin Layer 12b] As shown in Figures 4 and 5, the adhesive film 1 for metal terminals of the present disclosure comprises a first polyolefin layer 12a on one side of a substrate 11 and a second polyolefin layer 12b on the other side. The first polyolefin layer 12a is disposed on the metal terminal 2 side. The second polyolefin layer 12b is disposed on the exterior material 3 for an electricity storage device. In the adhesive film 1 for metal terminals of the present disclosure, the first polyolefin layer 12a and the second polyolefin layer 12b are located on the surfaces of both sides, respectively.

[0065] In the adhesive film for metal terminal 1 of the present disclosure, the first polyolefin layer 12a and the second polyolefin layer 12b are each a layer containing a polyolefin-based resin. Examples of polyolefin-based resins include polyolefin and acid-modified polyolefin. The first polyolefin layer 12a preferably contains an acid-modified polyolefin among polyolefin-based resins, and is more preferably a layer formed from an acid-modified polyolefin. The second polyolefin layer 12b preferably contains a polyolefin or an acid-modified polyolefin among polyolefin-based resins, and is more preferably a polyolefin, and is even more preferably a layer formed from a polyolefin. Acid-modified polyolefins have a high affinity with metals. Polyolefins also have a high affinity with heat-sealable resins such as polyolefins. Therefore, in the adhesive film for metal terminal 1 of the present disclosure, by arranging the first polyolefin layer 12a formed from an acid-modified polyolefin on the metal terminal 2 side, even better adhesion can be achieved at the interface between the adhesive film for metal terminal 1 and the metal terminal 2. Furthermore, by placing the second polyolefin layer 12b formed from polyolefin on the heat-sealable resin layer 35 side of the packaging material 3 for an electrical storage device, even better adhesion can be achieved at the interface between the adhesive film 1 for metal terminals and the heat-sealable resin layer 35.

[0066] Specific examples of preferred laminate structures for the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from polypropylene are laminated in this order; a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from acid-modified polypropylene are laminated in this order; and among these, a three-layer structure in which a first polyolefin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second polyolefin layer formed from polypropylene are laminated in this order is particularly preferred.

[0067] 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.

[0068] Specific examples of acid-modified polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is particularly preferred.

[0069] The acid-modified polyolefin may 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.

[0070] The acid-modified 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, preferred are cyclic alkenes, and more preferred are norbornene. Styrene is also an example of a constituting monomer.

[0071] 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 first polyolefin layer 12a 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 near . When the first polyolefin layer 12a or the second polyolefin layer 12b is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0072] The first polyolefin layer 12a and the second polyolefin layer 12b may each be formed of a single resin component or a blend polymer of two or more resin components. Furthermore, the first polyolefin layer 12a and the second polyolefin layer 12b may each be formed of a single layer or two or more layers of the same or different resin components. From the viewpoint of film-forming properties of the first polyolefin layer 12a and the second polyolefin layer 12b, these layers are preferably formed of a blend polymer of two or more resin components. When using a blend polymer, the first polyolefin layer 12a 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). The second polyolefin layer 12b 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 first polyolefin layer 12a and the second polyolefin layer 12b, it is preferable that the first polyolefin layer 12a contains only acid-modified polypropylene as the resin, and it is preferable that the second polyolefin layer 12b contains only polypropylene as the resin.

[0073] Furthermore, the first polyolefin layer 12a and the second polyolefin layer 12b may each contain a filler, if necessary. When the first polyolefin layer 12a and the second polyolefin layer 12b contain a filler, 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 packaging material 3 for an electrical storage device. The particle size of the filler is approximately 0.1 to 35 μm, preferably approximately 5.0 to 30 μm, and more preferably approximately 10 to 25 μm. The content of the filler is approximately 5 to 30 parts by mass, more preferably approximately 10 to 20 parts by mass, per 100 parts by mass of the resin components forming the first polyolefin layer 12a and the second polyolefin layer 12b, respectively.

[0074] 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 forming the first polyolefin layer 12a and the second polyolefin layer 12b, 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.

[0075] The first polyolefin layer 12a and the second polyolefin layer 12b may each contain a pigment, if necessary. Various inorganic pigments can be used as the pigment. A specific example of the pigment is preferably carbon (carbon, graphite), which is one of the fillers exemplified above. Carbon (carbon, graphite) is a material commonly used inside electricity storage devices and is unlikely to leach into the electrolyte solution. Furthermore, the pigment has a significant coloring effect, and a sufficient coloring effect can be obtained with an amount that does not impair adhesion. Furthermore, the pigment does not melt due to heat, and the apparent melt viscosity of the added resin can be increased. Furthermore, the pigment can prevent the pressurized portion from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing between the electricity storage device exterior material and the metal terminal.

[0076] When a pigment is added to the first polyolefin layer 12a or the second polyolefin layer 12b, the amount of pigment added is, for example, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin components forming the first polyolefin layer 12a or the second polyolefin layer 12b when carbon black with a particle size of about 0.03 μm is used. By adding a pigment to the first polyolefin layer 12a or the second polyolefin layer 12b, the presence or absence of the adhesive film for metal terminal 1 can be detected by a sensor or visually inspected. It is particularly preferred that the first polyolefin layer 12a contain a pigment. When adding a filler and a pigment to the first polyolefin layer 12a and the second polyolefin layer 12b, the filler and the pigment may be added to the same first polyolefin layer 12a and second polyolefin layer 12b, but from the viewpoint of not impairing the thermal fusion properties of the adhesive film 1 for metal terminals, it is preferable to add the filler and the pigment separately to the first polyolefin layer 12a and the second polyolefin layer 12b.

[0077] In the adhesive film 1 for metal terminals of the present disclosure, from the viewpoint of further improving the high sealing properties, crushing prevention, and conformability in a short period of time, the thickness of the first polyolefin layer 12a and the second polyolefin layer 12b is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, and even more preferably 30 μm or more, and is preferably about 60 μm or less, more preferably about 55 μm or less, even more preferably 50 μm or less, and even more preferably 40 μm or less. Preferred ranges for the thickness of the first polyolefin layer 12a and the second polyolefin layer 12b include approximately 10 to 60 μm, approximately 10 to 55 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 15 to 60 μm, approximately 15 to 55 μm, approximately 15 to 50 μm, approximately 15 to 40 μm, approximately 20 to 60 μm, approximately 20 to 55 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 30 to 60 μm, approximately 30 to 55 μm, approximately 30 to 50 μm, and approximately 30 to 40 μm, respectively.

[0078] From the same viewpoint, the ratio of the thickness of the substrate 11 to the total thickness of the first polyolefin layer 12a and the second polyolefin layer 12b is preferably about 0.3 or more, more preferably about 0.4 or more, and even more preferably 0.5 or more, and is preferably about 1.0 or less, more preferably about 0.8 or less, and preferred ranges include about 0.3 to 1.0, about 0.3 to 0.8, about 0.4 to 1.0, about 0.4 to 0.8, about 0.5 to 1.0, and about 0.5 to 0.8.

[0079] Furthermore, when the total thickness of the adhesive film 1 for a metal terminal is taken as 100%, the proportion of the total thickness of the first polyolefin layer 12a and the second polyolefin layer 12b is preferably about 30 to 80%, more preferably about 50 to 70%.

[0080] [Base material 11] In the adhesive film for a metal terminal 1, the substrate 11 is a layer that functions as a support for the adhesive film for a metal terminal 1, and is provided as needed.

[0081] The material forming the substrate 11 is not particularly limited. Examples of materials that can be used to form the substrate 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. Among these, polyolefin resins are particularly preferred. That is, the material forming the substrate 11 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. Whether the resin constituting the substrate 11 contains a polyolefin skeleton can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like.

[0082] As described above, the substrate 11 preferably contains a polyolefin resin, preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin. The polyolefin layer may be a stretched polyolefin film or an unstretched polyolefin film, but is preferably an unstretched polyolefin film. Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, 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, and polypropylene is more preferred. Furthermore, because of its excellent electrolyte resistance, the substrate 11 preferably contains homopolypropylene, is more preferably formed of homopolypropylene, and is even more preferably an unstretched homopolypropylene film.

[0083] Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and copolymers thereof. These polyamides may be used alone or in combination of two or more.

[0084] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymer polyesters whose repeating units are mainly ethylene terephthalate, copolymer polyesters whose repeating units are mainly butylene terephthalate, etc. Specific examples of copolymer polyesters whose repeating units are mainly ethylene terephthalate include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), etc. Specific examples of copolymer polyesters containing butylene terephthalate as the main repeating unit include copolymer polyesters in which butylene terephthalate is the main repeating unit and is polymerized with butylene isophthalate (hereinafter abbreviated as polybutylene (terephthalate / isophthalate)), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. These polyesters may be used alone or in combination of two or more.

[0085] The substrate 11 may also be formed of a nonwoven fabric made of the above-mentioned resin. When the substrate 11 is a nonwoven fabric, the substrate 11 is preferably made of the above-mentioned polyolefin resin, polyamide resin, or the like.

[0086] The substrate 11 may be a single layer or a multi-layer. When the substrate 11 is a multi-layer, at least one layer needs to include a layer having a heat of fusion ΔH3 of 70 J / g or more. A specific example of a multi-layer structure is a three-layer structure in which block polypropylene / homopolypropylene / block polypropylene are laminated in this order.

[0087] Furthermore, by blending a colorant into the substrate 11, the substrate 11 can be made into a layer containing a colorant. Furthermore, light transmittance can be adjusted by selecting a resin with low transparency. When the substrate 11 is a film, a colored film or a film with low transparency can be used. When the substrate 11 is a nonwoven fabric, a nonwoven fabric using a fiber or binder containing a colorant or a nonwoven fabric with low transparency can be used.

[0088] When the substrate 11 is made of a resin film, the surface of the substrate 11 may be subjected to a known adhesion-facilitating treatment such as corona discharge treatment, ozone treatment, or plasma treatment, if necessary.

[0089] In the adhesive film for metal terminal 1 of the present disclosure, from the viewpoint of further improving the high short-term sealing performance, crush suppression, and conformability, the thickness of the substrate 11 is preferably 120 μm or less, more preferably 100 μm or less, even more preferably about 80 μm or less, and even more preferably about 70 μm or less. The thickness of the substrate 11 is preferably about 20 μm or more, more preferably about 30 μm or more, and even more preferably about 40 μm or more. Preferred thickness ranges for the substrate 11 include about 20 to 120 μm, about 20 to 100 μm, about 20 to 80 μm, about 20 to 70 μm, about 30 to 120 μm, about 30 to 100 μm, about 30 to 80 μm, about 30 to 70 μm, about 40 to 120 μm, about 40 to 100 μm, about 40 to 80 μm, and about 40 to 70 μm.

[0090] [Adhesion promoter layer 13] The adhesion promoter layer 13 is a layer that is provided as needed for the purpose of firmly adhering the substrate 11 to the first polyolefin layer 12a and the second polyolefin layer 12b (see FIG. 5). The adhesion promoter layer 13 may be provided on only one side between the substrate 11 and the first polyolefin layer 12a and the second polyolefin layer 12b, or on both sides.

[0091] The adhesion promoter layer 13 can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, and polybutadiene-based. From the viewpoint of further improving electrolyte resistance, it is preferable to form the layer using an isocyanate-based adhesion promoter. Among the isocyanate-based adhesion promoters, those containing an isocyanate component selected from triisocyanate monomer and polymeric MDI provide excellent laminate strength and show little decrease in laminate strength after immersion in an electrolyte. It is particularly preferable to form the adhesive layer using an adhesion promoter made from triphenylmethane-4,4',4"-triisocyanate, a triisocyanate monomer, or polymethylene polyphenyl polyisocyanate, a polymeric MDI (NCO content of approximately 30%, viscosity of 200 to 700 mPa·s). It is also preferable to form the adhesive layer using tris(p-isocyanatephenyl)thiophosphate, a triisocyanate monomer, or a two-component curing adhesion promoter that uses a polyethyleneimine-based compound as the main component and polycarbodiimide as the crosslinking agent.

[0092] The adhesion promoter layer 13 can be formed by coating and drying using a known coating method such as bar coating, roll coating, or gravure coating. The amount of the adhesion promoter to be applied is 20 to 100 mg / m when the adhesion promoter is made of triisocyanate. 2 Approximately, preferably 40 to 60 mg / m 2 In the case of adhesion promoters made of polymeric MDI, the concentration is 40 to 150 mg / m 2 Approximately, preferably 60 to 100 mg / m 2In the case of a two-component curing adhesion promoter that uses polyethyleneimine as the main component and polycarbodiimide as the crosslinking agent, the adhesive strength is about 5 to 50 mg / m 2 about 10 to 30 mg / m 2 Triisocyanate monomer is a monomer with three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers formed by polymerizing MDI, and is represented by the following formula:

[0093] [ka]

[0094] The adhesive film 1 for metal terminals of the present disclosure can be produced, for example, by laminating a first polyolefin layer 12a and a second polyolefin layer 12b, respectively, on both surfaces of a substrate 11. The substrate 11 and the first polyolefin layer 12a and the second polyolefin layer 12b can be laminated by known methods such as extrusion lamination, T-die lamination, inflation lamination, and thermal lamination. Furthermore, when laminating the substrate 11 and the first polyolefin layer 12a and the second polyolefin layer 12b via an adhesion promoter layer 13, for example, the adhesion promoter that constitutes the adhesion promoter layer 13 may be applied to the substrate 11 by the above-described method and dried, and the first polyolefin layer 12a and the second polyolefin layer 12b may then be laminated on top of the adhesion promoter layer 13.

[0095] 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.

[0096] [Metal terminal 2] The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between a metal terminal 2 and an exterior material 3 for an electricity storage device. The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive electrode or negative electrode) of an electricity storage device element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, copper, etc. For example, the metal terminal 2 connected to the positive electrode of a lithium ion electricity storage device is usually made of aluminum, etc. Furthermore, the metal terminal 2 connected to the negative electrode of a lithium ion electricity storage device is usually made of copper, nickel, etc.

[0097] To enhance electrolyte resistance, the surface of the metal terminal 2 is preferably subjected to a chemical conversion treatment. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming a corrosion-resistant film using phosphates, chromates, fluorides, triazine thiol compounds, etc. Among the methods for forming a corrosion-resistant film, a preferred method is a phosphate chromate treatment using a compound consisting of three components: a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid.

[0098] The size of the metal terminal 2 may be set appropriately depending on the size of the electricity storage device to be used. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0099] [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. 6 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.

[0100] The thickness of the laminate constituting the electricity storage device packaging material 3 is not particularly limited, but the upper limit, from the viewpoints of cost reduction, energy density improvement, etc., is preferably about 190 μm or less, 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 the lower limit, from the viewpoint of maintaining the function of the electricity storage device packaging material 3 to protect the electricity storage device elements 4, 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 190 μm, about 35 to 180 μm, or about 35 to 160 μm. , about 35-155μm, about 35-140μm, about 35-130μm, about 35-120μm, about 45-190μm, about 45-180μm, 45- Approx. 160μm, approx. 45~155μm, approx. 45~140μm, approx. 45~130μm, approx. 45~120μm, approx. 60~190μm, 60~180μm Examples include about 60 to 160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm, about 60 to 120 μm, about 80 to 190 μm, about 80 to 180 μm, about 80 to 160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm, and about 80 to 120 μm.

[0101] (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.

[0102] 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.

[0103] 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.

[0104] Among these, the resin film forming the base layer 31 is preferably nylon or polyester, and more preferably biaxially oriented nylon or biaxially oriented polyester.

[0105] The base material layer 31 may 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 material layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be laminated together directly without an adhesive. When bonding without an adhesive, examples of methods that bond the films in a hot-melt state include coextrusion, sand lamination, and thermal lamination.

[0106] 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.

[0107] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0108] (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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0113] (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).

[0114] 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.

[0115] 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.

[0116] (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.

[0117] The adhesive layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-sealable resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, and examples thereof include a resin composition containing an acid-modified polyolefin. Examples of acid-modified polyolefins include the same as those exemplified for the first polyolefin layer 12a and the second polyolefin layer 12b.

[0118] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0119] (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.

[0120] As described above, the absolute value of the difference between the heat of fusion ΔH4 of the heat-sealable resin layer 35 of the packaging material for an electricity storage device 3 in which the adhesive film for metal terminal 1 of the present disclosure is used and the heat of fusion ΔH2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0.0 to 5.0 J / g, or about 0.0 to 3.0 J / g. The smaller the absolute value of the difference between the heat of fusion ΔH4 and the heat of fusion ΔH2 (i.e., the closer the absolute value of the difference is to 0.0 J / g), the easier it is to improve the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35.

[0121] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, and examples thereof include polyolefins and cyclic polyolefins.

[0122] Furthermore, as described above, the absolute value of the difference between the melting peak temperature mp4 of the heat-sealable resin layer 35 of the packaging material for an electricity storage device in which the adhesive film for metal terminal 1 of the present disclosure is used, and the melting peak temperature mp2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0 to 5° C., or about 0 to 3° C. The smaller the absolute value of the difference between the melting peak temperature mp4 and the melting peak temperature mp2 (i.e., the closer the absolute value of the difference is to 0° C.), the easier it is to increase the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35.

[0123] Furthermore, as described above, the absolute value of the difference between the melt mass-flow rate (MFR) T4 of the heat-sealable resin layer 35 of the packaging material for an electricity storage device in which the adhesive film for metal terminal 1 of the present disclosure is used and the melt mass-flow rate (MFR) T2 of the second polyolefin layer 12b of the adhesive film for metal terminal 1 is preferably about 0 to 5 g / 10 min, or about 0 to 3 g / 10 min. The smaller the absolute value of the difference between the melt mass-flow rate (MFR) T4 and the melt mass-flow rate (MFR) T2 (i.e., the closer the absolute value of the difference is to 0 g / 10 min), the easier it is to improve the adhesion between the second polyolefin layer 12b and the heat-sealable resin layer 35.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] The heat-sealable resin layer 35 may be formed of a single resin component, or may be formed of a blend polymer of two or more resin components. 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 resin components. It is particularly preferred that the second polyolefin layer 12b and the heat-sealable resin layer 35 use the same resin, as this improves adhesion between these layers.

[0128] 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.

[0129] 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.

[0130] 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).

[0131] 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. [Example]

[0132] 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.

[0133] <Production of adhesive film for metal terminals> Examples 1-8, 10, 11, and 13 In each example, a maleic anhydride-modified polypropylene (PPa) was used as the polyolefin forming the first polyolefin layer located on the metal terminal side, a polypropylene (PP) was used as the polyolefin forming the second polyolefin layer located on the exterior material for an electrical storage device side, and an unstretched polypropylene film (CPP, homopolypropylene) was used as the substrate. Next, for Examples 1-8, 10, 11, and 13, maleic anhydride-modified polypropylene (PPa) was extruded onto one side of the substrate (CPP) using a T-die extruder to form a first polypropylene layer, and polypropylene (PP) was extruded onto the other side of the substrate (CPP) using a T-die extruder to form a second polypropylene layer, thereby obtaining an adhesive film for metal terminal in which the first polyolefin layer (PPa layer), substrate (CPP layer), and second polyolefin layer (PP layer) were laminated in this order. Regarding the layer structure, including the thickness of each layer, Examples 1, 2, and 10 are: first polyolefin layer (PPa layer, 50 μm thick) / substrate (CPP layer, 50 μm thick) / second polyolefin layer (PP layer, 50 μm thick); Examples 3-8 and 11 are: first polyolefin layer (PPa layer, 50 μm thick) / substrate (CPP layer, 60 μm thick) / second polyolefin layer (PP layer, 40 μm thick); and Example 13 is: first polyolefin layer (PPa layer, 20 μm thick) / substrate (CPP layer, 40 μm thick) / second polyolefin layer (PP layer, 20 μm thick). The heat of fusion, melting peak temperature, and melt mass-flow rate (MFR) of the first polyolefin layer, second polyolefin layer, and substrate are shown in Tables 1-3. These physical properties were adjusted by adjusting the composition (composition ratio of polyethylene component, etc.) and molecular weight of each resin.

[0134] Example 9 An adhesive film for metal terminals was obtained in the same manner as in Example 1, except that a three-layer film consisting of block polypropylene (5 μm thick), homopolypropylene (40 μm thick), and block polypropylene (5 μm thick) was used as the substrate instead of unstretched polypropylene film (CPP, homopolypropylene). The adhesive film was composed of a first polyolefin layer (PPa layer, 50 μm thick), substrate (total thickness of the three-layer film, 50 μm), and second polyolefin layer (PP layer, 50 μm thick). The heats of fusion, peak fusion temperatures, and melt mass-flow rates (MFR) of the first polyolefin layer, second polyolefin layer, and substrate are shown in Table 1-3. These physical properties were adjusted by adjusting the composition (the blending ratio of polyethylene component, etc.) and molecular weight of each resin.

[0135] Example 12 On one side of the substrate (thickness 50 μm, CPP, homopolypropylene), maleic anhydride-modified polypropylene (PPa) was extruded with a T-die extruder to form a first polypropylene layer (thickness 100 μm), and on the other side of the substrate, polypropylene (PP) was extruded with a T-die extruder to form a second polypropylene layer (thickness 50 μm). An adhesive film for metal terminals was obtained in the same manner as in Example 1, except that the first polyolefin layer (PPa layer) / substrate (CPP layer) / second polyolefin layer (PP layer) were laminated in this order. The heat of fusion, peak melting temperature, and melt mass-flow rate (MFR) of the first polyolefin layer, the second polyolefin layer, and the substrate are as shown in Table 1-3. These physical property values ​​are adjusted by the composition (mixing ratio of polyethylene component, etc.) and molecular weight of each resin.

[0136] Comparative Example 1 The first polyolefin layer was made of maleic anhydride-modified polypropylene (PPa), the second polyolefin layer was made of polypropylene (PP), and the substrate layer was made of a polypropylene film (PP) colored black with carbon black. The maleic anhydride-modified polypropylene (PPa) and polypropylene (PP) were coextruded without a substrate to obtain an adhesive film for metal terminals, laminated in the following order: first polyolefin layer (PPa layer, 70 μm thick), substrate (PP layer, 50 μm thick), and second polyolefin layer (PP layer, 30 μm thick). The heats of fusion, peak melting temperatures, and melt mass-flow rates (MFR) of the first polyolefin layer, second polyolefin layer, and substrate are shown in Table 1-3. These physical properties were adjusted by adjusting the composition (the blending ratio of polyethylene components, etc.) and molecular weight of each resin.

[0137] Comparative Example 2 The first polyolefin layer was made of maleic anhydride-modified polypropylene (PPa), the second polyolefin layer was made of maleic anhydride-modified polypropylene (PPa), and the substrate was a polypropylene film (PP, homopolypropylene). The resins for each layer were subjected to multilayer air-cooled inflation molding to obtain an adhesive film for metal terminals, laminated in the following order: first polyolefin layer (PPa layer, 35 μm thick), substrate (PP layer, 80 μm thick), and second polyolefin layer (PPa layer, 35 μm thick). The heats of fusion, peak melting temperatures, and melt mass-flow rates (MFR) of the first polyolefin layer, second polyolefin layer, and substrate are shown in Table 1-3. These physical properties were adjusted by adjusting the composition (the blending ratio of polyethylene components, etc.) and molecular weight of each resin.

[0138] <Measurement of heat of fusion> The first polyolefin layer, the second polyolefin layer, and the heat-sealable resin layer of the outer casing were extracted from the adhesive film for metal terminals and used as measurement samples. The heat of fusion of the substrate was measured by measuring the heats of fusion of the first polyolefin layer, the second polyolefin layer, and the adhesive film for metal terminals. The heat of fusion of the substrate was determined by subtracting the heats of fusion of the first and second polyolefin layers from the heat of fusion measured for the adhesive film for metal terminals. The heats of fusion ΔH1, ΔH2, ΔH3, and ΔH4 of each measurement sample were measured in accordance with JIS K 7122:2012. Measurements were performed using a differential scanning calorimeter (DSC, e.g., a Q200 differential scanning calorimeter manufactured by TA Instruments). The sample was held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min. The first heat of fusion, ΔH (J / g), was measured, and the sample was then held at 210°C for 10 minutes. The sample was then cooled from 210°C to -50°C at a heating rate of 10°C / min and held for 15 minutes. The sample was then heated from -50°C to 210°C at a heating rate of 10°C / min, and the second heat of fusion, ΔH (J / g), was measured. The nitrogen gas flow rate was 50 ml / min. The value of the heat of fusion, ΔH (J / g), measured the first time through the above procedure was used. The heat of fusion was defined as the area enclosed by the baseline (the line connecting the start and end points of the ridgeline from base to base) and the peak in the DSC curve. For reference, the DSC curve obtained in Example 1 is shown in Figure 11. In Figure 11, the baseline is indicated by a dashed line.

[0139] <Measurement of melting peak temperature> The first polyolefin layer, the second polyolefin layer, and the substrate were separated from the adhesive film for metal terminals to prepare measurement samples. The melting peak temperatures (mp1, mp2, and mp3) of each measurement sample were measured in accordance with JIS K7121:2012 (Method for Measuring Transition Temperature of Plastics (JIS K7121:1987, Supplement 1)). Measurements were performed using a differential scanning calorimeter (DSC, e.g., a TA Instruments Q200 differential scanning calorimeter). The measurement sample was held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min. The first melting peak temperature (P) was measured, and the sample was then held at 210°C for 10 minutes. The sample was then cooled from 210°C to -50°C at a cooling rate of 10°C / min and held for 15 minutes. Furthermore, the temperature is raised from -50°C to 210°C at a rate of 10°C / min, and the second melting peak temperature Q (°C) is measured. The flow rate of nitrogen gas is 50 ml / min. Using the above procedure, the first melting peak temperature P (°C) and the second melting peak temperature Q (°C) are determined, and the first melting peak temperature P measured is taken as the melting peak temperature.

[0140] <Melt Mass Flow Rate (MFR) Measurement> The resins constituting the first polyolefin layer, the second polyolefin layer, and the substrate used in producing the adhesive film for metal terminals were each used as a measurement sample. For each measurement sample, the melt mass flow rate (g / 10 min) was measured using a melt indexer at a measurement temperature of 230°C and a load of 2.16 kg, according to Method A of JIS K 7210:2014.

[0141] <Measurement of adhesion strength between adhesive film for metal terminals and heat-sealable resin layer> (Fabrication of exterior materials) First, an exterior packaging material for an electricity storage device (hereinafter, sometimes simply referred to as "exterior packaging material") was prepared according to the following procedure. A substrate layer (30 μm thick) consisting of a polyethylene terephthalate film (12 μm thick), an adhesive layer (3 μm thick), and a nylon film (15 μm thick) was laminated onto an aluminum alloy foil (40 μm thick) by dry lamination, and a heat-sealable resin layer was laminated onto the other surface by coextrusion. Specifically, a two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied onto the nylon film to form an adhesive layer (3 μm thick) on the nylon film. Next, the adhesive layer and a polyethylene terephthalate film were laminated onto the nylon film to prepare a substrate layer. Next, a two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one surface of a barrier layer made of aluminum alloy foil to form an adhesive layer (3 μm thick) on the aluminum alloy foil. Next, an adhesive layer and a substrate layer with the nylon film facing the adhesive surface were laminated on an aluminum alloy foil, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Next, an adhesive layer (40 μm thick, positioned on the metal layer side) made of maleic anhydride-modified polypropylene resin and a heat-sealable resin layer (40 μm thick, innermost layer) made of random polypropylene resin were co-extruded onto the barrier layer of the laminate, resulting in an adhesive layer / heat-sealable resin layer laminated on the barrier layer. The resulting laminate was then heated at 190°C for 2 minutes to produce an electrical storage device packaging material consisting of a substrate layer, adhesive layer, barrier layer, adhesive layer, and heat-sealable resin layer laminated in this order. The heat of fusion ΔH4, melting peak temperature mp4, and melt mass-flow rate (MFR) T4 of the heat-sealable resin layer are shown in Table 1-3. These measurement methods were the same as those for adhesive films for metal terminals, except that the heat-sealable resin layer was used as the measurement sample.

[0142] (Evaluation of adhesion when heat sealed for 3 seconds) Aluminum foil (JIS H4160:1994 A8079H-O) with a MD of 40 mm, TD of 22.5 mm, and thickness of 400 μm was prepared as the metal terminal. Each adhesive film obtained in the Examples and Comparative Examples was cut to a length (MD) of 45 mm and a width (TD) of 20 mm. Next, as shown in the schematic diagram of FIG. 8, the metal terminal was sandwiched between two adhesive films to obtain an adhesive film / metal terminal / adhesive film laminate. The metal terminal was laminated so that the MD and TD of the metal terminal coincided with the length direction (MD) and width direction (TD) of the adhesive film, respectively, and the centers of the metal terminal and adhesive film were aligned. Next, the laminate was sandwiched between two tetrafluoroethylene-ethylene copolymer films (ETFE films, 100 μm thick) and placed on a hot plate heated to 190°C. A 500 g sponge-equipped weight was placed on top and left for 12 seconds to heat-seal the adhesive film to the metal terminal, producing a metal terminal with an adhesive film. As shown in the schematic diagram of FIG. 8, the metal terminal was sandwiched between the adhesive films, so that the periphery of the metal terminal was covered with the adhesive film and a portion where the two adhesive films were heat-sealed to each other was formed. Next, the exterior packaging material was cut to a size of 60 mm in TD and 200 mm in MD. As shown in the schematic diagram of FIG. 9, the pieces were placed facing each other with the heat-sealable resin layer on the inside so that the MD length was 100 mm, half the original length. The resulting laminate was sandwiched between the opposing heat-sealable resin layers. The exterior packaging material was laminated so that the MD and TD directions of the exterior packaging material were aligned with the width direction (TD) and length direction (MD) of the laminate, respectively. In this state, a heat seal tester was used to heat seal the laminate at a width of 7 mm (7 mm in the y-axis direction in Figure 9(b)), at 190°C, with a surface pressure of 1.0 MPa for 3 seconds (see the hatched area S in Figure 9(b)). The laminate was then allowed to cool naturally to 25°C, yielding a laminate in which the exterior material and the adhesive film were heat-sealed (see the schematic diagram in Figure 9(b)).

[0143] Next, the center of the TD of the resulting laminated exterior material was cut to a width of 15 mm (see the two-dot dash line in Figure 9(b) for the cutting position). Next, in an environment of 25°C, the exterior material and metal terminal were chucked using a Tensilon universal material testing machine (RTG-1210 manufactured by A&D Co., Ltd.), and the adhesive film and the heat-sealable resin layer of the exterior material were peeled in the y direction in Figure 9(b). The maximum strength during peeling was recorded as the peel strength (N / 15 mm) to the exterior material. The peel speed was 300 mm / min, the peel angle was 180°, and the chuck distance was 30 mm. The average value was calculated by measuring three times. A: Peel strength is 120N / 15mm or more. B: The peel strength is 100N / 15mm or more and less than 120N / 15mm. C: The ratio of the peel strength to the standard peel strength is less than 100 N / 15 mm.

[0144] (Evaluation of adhesion when heat sealed for a short time (1 second)) In the above (adhesion when heat-sealed for 3 seconds), the heat-sealing conditions using the heat seal tester were changed to 190°C, a surface pressure of 1.0 MPa, and a short time of 1 second, and the adhesive film and the heat-fusible resin layer of the packaging material were peeled off in the same manner as above, to measure the peel strength. A: Peel strength is 100N / 15mm or more. B: The peel strength is 80N / 15mm or more and less than 100N / 15mm. C: The ratio of the peel strength to the standard peel strength is less than 80N / 15mm.

[0145] <Follow-up evaluation> Ten samples were prepared for each of the laminates (see FIG. 10 ) of the packaging material and adhesive film obtained in the above-described procedure (evaluation of adhesion when heat-sealed for a short time (1 second)). For each sample, the y1 side in the schematic diagram of FIG. 10 was positioned on the top and the y2 side on the bottom. The opposing heat-sealable resin layers were opened, and a highly penetrating dye solution (Microcheck, manufactured by Taiho Kozai Co., Ltd.) was sprayed from the top (y1 side) onto both ends where the adhesive film was heat-sealed and the metal terminals were exposed (the positions indicated by the arrows at both ends in the x-axis direction in FIG. 10 ). The penetration of the dye solution into the gap between the adhesive film and the packaging material was confirmed, and the adhesive film's ability to conform to the packaging material after heat sealing was evaluated. The evaluation was based on the number of samples in which the dye solution penetrated into the gap between the adhesive film and the packaging material. When the dyeing solution penetrated from the upper side (y1 side) to the lower side (y2 side) in Figure 10, passing through the heat-sealed portion S and reaching the lower side (y2 side), it was evaluated as the dyeing solution having penetrated into the gap. The penetration of the dyeing solution was confirmed by cutting each sample at a position 1 mm further outward from the adhesive film (see the position of the two-dot chain line in Figure 10) and observing the cross section. The evaluation criteria were as follows. The results are shown in Table 4. A: Of the 10 samples, the dye solution did not penetrate into the gaps in any of them. B: Of 10 samples, the dye solution penetrated into the gaps in 1 to 2 samples. C: Of 10 samples, the dye solution penetrated into the gaps in 3 or more samples.

[0146] <Collapse evaluation> The laminate of the packaging material and adhesive film obtained in the above-mentioned procedure (evaluation of adhesion when heat-sealed for a short time (1 second)) was used as a sample, and the adhesive film was cut in the thickness direction at the center of the heat-sealed part (cut in the y-axis direction and thickness direction at the center of the x-axis direction of the laminate shown in Figure 9(b)), and the thickness of the adhesive film was measured. The thickness before heat-sealing the adhesive film was taken as 100%, and crushing was evaluated based on the thickness ratio after heat-sealing according to the following criteria. The thickness is the average thickness of the two adhesive films located above and below the metal terminal. The results are shown in Table 4. A: The thickness of the adhesive film after heat sealing is 95% or more of the thickness before heat sealing. B: The thickness of the adhesive film after heat sealing is 80% or more and less than 95% of the thickness before heat sealing. C: The thickness of the adhesive film after heat sealing is less than 80% of the thickness before heat sealing.

[0147] <Film-forming property evaluation> The film-forming properties of the first polyolefin layer in the above-mentioned <Production of adhesive film for metal terminal> were evaluated. Specifically, the unevenness in the width direction (TD) during film formation of the first polyolefin layer was evaluated. The unevenness in the width direction was evaluated by measuring the thickness of the first polyolefin layer at 5 mm intervals in the width direction and evaluating it according to the following criteria based on 2σ. The results are shown in Table 4. A: 2σ of unevenness in the width direction is less than 2.5 B: 2σ of unevenness in the width direction is 2.5 to 3.0 C: 2σ of unevenness in the width direction is more than 3.0

[0148] [Table 1]

[0149] [Table 2]

[0150] [Table 3]

[0151] [Table 4]

[0152] 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 terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the exterior material side for the electricity storage device; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; An adhesive film for metal terminals, wherein the heat of fusion ΔH3 of the substrate is 70 J / g or more, as measured in accordance with the provisions of JIS K 7122:2012. Item 2. An adhesive film for metal terminals according to Item 1, wherein the heat of fusion ΔH1 of the first polyolefin layer, the heat of fusion ΔH2 of the second polyolefin layer, and the heat of fusion ΔH3 of the substrate satisfy the relationship ΔH3≧ΔH1>ΔH2. Item 3. The adhesive film for metal terminal according to Item 1 or 2, wherein the second polyolefin layer has a heat of fusion ΔH2 of 20 J / g or more and 70 J / g or less. Item 4. The adhesive film for metal terminal according to any one of Items 1 to 3, wherein the first polyolefin layer has a heat of fusion ΔH1 of 30 J / g or more and 80 J / g or less. Item 5. The adhesive film for metal terminals according to any one of Items 1 to 4, wherein the melting peak temperature mp1 of the first polyolefin layer, the melting peak temperature mp2 of the second polyolefin layer, and the melting peak temperature mp3 of the substrate, measured in accordance with the provisions of JIS K7121:2012, satisfy the relationship mp3≧mp1>mp2. Item 6. The adhesive film for metal terminal according to any one of Items 1 to 5, wherein the melt mass-flow rate T1 of the first polyolefin layer, the melt mass-flow rate T2 of the second polyolefin layer, and the melt mass-flow rate T3 of the substrate at 230°C satisfy the relationship T2>T1>T3. Item 7. The adhesive film for a metal terminal according to any one of Items 1 to 6, wherein the substrate includes a polyolefin skeleton. Item 8. The adhesive film for a metal terminal according to any one of Items 1 to 7, wherein the first polyolefin layer and the second polyolefin layer each have a thickness of 60 μm or less. Item 9. The adhesive film for a metal terminal according to any one of Items 1 to 8, wherein the thickness of the substrate is 120 μm or less. Item 10. The adhesive film for a metal terminal according to any one of Items 1 to 9, wherein the adhesive film for a metal terminal has a thickness of 220 μm or less. Item 11. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: the adhesive film for metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the exterior material side for the electricity storage device; obtaining a laminate having the first polyolefin layer, the substrate, and the second polyolefin layer in this order, a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; A method for producing an adhesive film for metal terminals, wherein the heat of fusion ΔH3 of the substrate, measured in accordance with the provisions of JIS K 7122:2012, is 70 J / g or more. Item 12. 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 10 attached to a metal terminal. Item 13. 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 11. An electricity storage device, wherein the adhesive film for a metal terminal according to any one of items 1 to 10 is interposed between the metal terminal and the exterior material for an electricity storage device. Item 14. 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 producing an electricity storage device, comprising a step of interposing the adhesive film for metal terminal according to any one of items 1 to 10 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. [Explanation of symbols]

[0153] 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 Base material 12a First polyolefin layer 12b Second polyolefin layer 13 Adhesion promoter 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 a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, a heat of fusion ΔH1 of the first polyolefin layer, a heat of fusion ΔH2 of the second polyolefin layer, and a heat of fusion ΔH3 of the base material satisfy the relationship ΔH3≧ΔH1>ΔH2; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The adhesive film for metal terminals has a heat of fusion ΔH2 of 35.0 to 55.0 J / g.

2. 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 a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, a peak melting temperature (mp1) of the first polyolefin layer, a peak melting temperature (mp2) of the second polyolefin layer, and a peak melting temperature (mp3) of the substrate, which are measured in accordance with the provisions of JIS K7121:2012, satisfy the relationship: mp3≧mp1>mp2; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The adhesive film for metal terminals has a heat of fusion ΔH2 of 35.0 to 55.0 J / g.

3. 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 a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, the substrate comprises a polyolefin backbone; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The adhesive film for metal terminals has a heat of fusion ΔH2 of 35.0 to 55.0 J / g.

4. 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 a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, The thickness of the substrate is 120 μm or less, the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The adhesive film for metal terminals has a heat of fusion ΔH2 of 35.0 to 55.0 J / g.

5. The heat of fusion ΔH1 of the first polyolefin layer, the heat of fusion ΔH2 of the second polyolefin layer, and the heat of fusion ΔH3 of the base material satisfy the relationship ΔH3 ≧ ΔH1 > ΔH2. An adhesive film for metal terminals according to any one of claims 2 to 4.

6. 5. An adhesive film for metal terminals according to claim 1, 3, or 4, wherein the melting peak temperature mp1 of the first polyolefin layer, the melting peak temperature mp2 of the second polyolefin layer, and the melting peak temperature mp3 of the substrate, measured in accordance with the provisions of JIS K7121:2012, satisfy the relationship mp3≧mp1>mp2.

7. 5. The adhesive film for a metal terminal according to claim 1, wherein the substrate comprises a polyolefin skeleton.

8. The adhesive film for metal terminals according to any one of claims 1 to 3, wherein the thickness of the substrate is 120 µm or less.

9. The melt mass-flow rate T1 of the first polyolefin layer, the melt mass-flow rate T2 of the second polyolefin layer, and the melt mass-flow rate T3 of the substrate at 230 ° C. satisfy the relationship T2 > T1 > T3. An adhesive film for metal terminals according to any one of claims 1 to 8.

10. The adhesive film for metal terminals according to any one of claims 1 to 9, wherein the thickness of the first polyolefin layer and the second polyolefin layer is 60 µm or less.

11. The adhesive film for a metal terminal according to any one of claims 1 to 10, wherein the thickness of the adhesive film for a metal terminal is 220 µm or less.

12. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: the adhesive film for a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; obtaining a laminate comprising the first polyolefin layer, the substrate, and the second polyolefin layer in this order; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, a heat of fusion ΔH1 of the first polyolefin layer, a heat of fusion ΔH2 of the second polyolefin layer, and a heat of fusion ΔH3 of the base material satisfy the relationship ΔH3≧ΔH1>ΔH2; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The method for producing an adhesive film for a metal terminal, wherein the heat of fusion ΔH2 is 35.0 to 55.0 J / g.

13. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: the adhesive film for a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; obtaining a laminate comprising the first polyolefin layer, the substrate, and the second polyolefin layer in this order; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, a peak melting temperature (mp1) of the first polyolefin layer, a peak melting temperature (mp2) of the second polyolefin layer, and a peak melting temperature (mp3) of the substrate, which are measured in accordance with the provisions of JIS K7121:2012, satisfy the relationship: mp3≧mp1>mp2; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The method for producing an adhesive film for a metal terminal, wherein the heat of fusion ΔH2 is 35.0 to 55.0 J / g.

14. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: the adhesive film for a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; obtaining a laminate comprising the first polyolefin layer, the substrate, and the second polyolefin layer in this order; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, the substrate comprises a polyolefin backbone; the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The method for producing an adhesive film for a metal terminal, wherein the heat of fusion ΔH2 is 35.0 to 55.0 J / g.

15. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: the adhesive film for a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on the metal terminal side, a substrate, and a second polyolefin layer disposed on the electricity storage device exterior material side; obtaining a laminate comprising the first polyolefin layer, the substrate, and the second polyolefin layer in this order; a heat of fusion ΔH1 of the first polyolefin layer and a heat of fusion ΔH2 of the second polyolefin layer, measured in accordance with the provisions of JIS K 7122:2012, satisfy the relationship ΔH1>ΔH2; The heat of fusion ΔH3 of the base material measured in accordance with JIS K 7122:2012 is 70 J / g or more, The thickness of the substrate is 120 μm or less, the heat of fusion ΔH1 is 45.0 to 60.0 J / g; The method for producing an adhesive film for a metal terminal, wherein the heat of fusion ΔH2 is 35.0 to 55.0 J / g.

16. 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 11 attached to a metal terminal.

17. 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 11 interposed between the metal terminals and the exterior material for electricity storage devices.

18. 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 terminal according to any one of claims 1 to 11 between the metal terminal and the exterior material for an electricity storage device, and sealing the electricity storage device element with the exterior material for an electricity storage device.

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